JP4241602B2 - Image quality evaluation method for image forming apparatus, method for manufacturing image forming apparatus, method for modifying image forming apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, a method for manufacturing the image forming apparatus, a method for modifying the image forming apparatus, and a sound quality evaluation method.

JP-A-9-193506 JP-A-10-232163 Japanese Patent Laid-Open No. 10-253440 Japanese Patent Laid-Open No. 10-253442 JP-A-10-267742 Japanese Patent Laid-Open No. 10-267743 JP 2001-336975 A JP 2002-128316 A

  In offices and the like, image forming apparatuses such as copying machines, printers, and facsimile machines are widely used. This type of image forming apparatus is configured by mechanically connecting many parts. In addition, the image forming apparatus has a motor for driving these mechanisms and the like, and during the image forming operation, an operation sound of each part of the apparatus is generated. Sometimes it becomes. In the past, these devices only had to be convenient. However, as the environment in the office has improved, there has been an increasing demand for solving noise problems for OA devices. For this reason, the noise reduction of the image forming apparatus has been promoted, and considerable noise reduction has been achieved as compared with before.

  As a technique for solving the noise problem in the image forming apparatus, for example, there is a technique described in each of the above Patent Documents 1. The present invention relates to a noise masking device such as a laser beam printer or a copying machine, and has a drive mechanism that is a source of noise during operation and generates a masking sound for masking the noise, and the sound generation. And a masking sound control means for controlling a body and generating a masking sound having a frequency in a range including the main component frequency of the noise, thereby reducing noise discomfort.

  However, the present invention does not reduce the generated sound, but adds a masking sound to the generated sound (operation sound), which may increase the noise level. In addition, a sounding body for generating a masking sound and a control device and a speaker for generating a masking sound only during the generation time of the masked sound are required. There is a drawback that the cost is significantly increased.

Moreover, there exists a thing of the said patent documents 2-7 as a thing regarding a sound quality evaluation apparatus and a sound quality evaluation method.
Only the “go” sound, which is a serious noise of low-frequency random noise generated in an air flow system such as an exhaust sound, from a noise composed of many timbres of the image forming apparatus is disclosed in Patent Document 2. Is a sound quality evaluation device, a sound quality evaluation method, and a sound quality evaluation device that enable evaluation of sound quality and facilitate the correspondence with psychological annoyance.

  The one described in Patent Document 3 is a “Kean” sound that is recognized as an annoying sound from the noise composed of many timbre sounds of the image forming apparatus and is a continuous pure sound generated by a scanner motor or a charging device. A sound quality evaluation method and a sound quality evaluation apparatus that extract and evaluate only sound.

  Patent Document 4 describes a sound quality evaluation that can evaluate only “shear” sound, which is high-frequency random noise due to paper rubbing, among noises composed of many timbres of an image forming apparatus. A method and a sound quality evaluation apparatus.

  Patent Document 5 describes only “won won” sound composed of pure sounds having peaks at a plurality of adjacent frequencies due to the beat of the drive system, particularly from noise composed of many timbre sounds of the image forming apparatus. Are a sound quality evaluation method and a sound quality evaluation apparatus.

  In the device described in Patent Document 6, it is felt that it is smoother that there is no pure tone or beat, that is, there is no protruding component in the frequency waveform in the noise composed of many tones of the image forming apparatus. Therefore, the present invention is a sound quality evaluation method and a sound quality evaluation apparatus that collectively refer to the annoyance that a person feels as smoothness and enable the evaluation of the smoothness of sound.

  The thing of patent document 7 provides the sound quality evaluation apparatus and the sound quality evaluation method which can evaluate comprehensive sound quality in consideration of the influence which it gives to the human subjective sensation about the noises etc. which arise from office equipment etc. As a solution, the digital signal of the sound to be evaluated is input to the sound quality index calculation unit, and after performing preprocessing necessary for calculation of various acoustic indexes in the waveform preprocessing unit, A plurality of acoustic indexes are calculated by the acoustic index calculation unit. At this time, not only the loudness index calculation unit, but also the influence on the subjective annoyance and discomfort of noise, the high frequency pure tone index and broadband noise figure are calculated respectively. And broadband noise figure calculation unit. Based on the obtained magnitude index, high frequency pure tone index, and wideband noise index, the total sound quality index calculation unit calculates the total sound quality index and displays it on the calculation result display unit.

  However, those described in Patent Documents 2 to 7 are a sound quality evaluation device and a sound quality evaluation method, and only a presentation of the sound quality evaluation method does not mention a sound quality improvement method of an actual product.

  The one described in Patent Document 8 was separately proposed by the applicant of the present application, and based on an objective evaluation standard, psychological problems caused by sounds generated from the device to humans around the device. The problem is to be able to alleviate the feeling of pleasure, and as a means for solving the problem, a conveyance mechanism is used in a paper guide path that guides the paper to a predetermined route via an image forming unit that forms an image on the paper. In an image forming apparatus configured to convey a sheet, when the sheet is conveyed by the conveyance mechanism, it is obtained based on a loudness value A and a sharpness value B of an operating sound generated from the apparatus body measured at a position 1 m away from the apparatus body. The paper conveying means is improved to reduce the discomfort so that the discomfort index S of the operating sound to be set is set within a predetermined range.

  By the way, as a method for evaluating noise in an image forming apparatus, an acoustic power level and a sound pressure level (ISO 7779) are generally used. However, since these are values of acoustic energy generated from office equipment such as copying machines and printers, the correlation with human subjective discomfort with noise may not be very good. For example, when listening to sounds with the same sound pressure level (equivalent noise level Leq: energy averaged over the entire measurement time), the differences in sound frequency distribution and the presence or absence of impact sounds can cause discomfort. There may be. Moreover, even if the value of the sound pressure level is small, it may be uncomfortable if a high frequency component, a pure sound component, or the like is included.

  Therefore, in order to improve the office environment in the future, it is necessary not only to evaluate and reduce the sound power level and sound pressure level of OA equipment, but also to simultaneously evaluate and improve sound quality. In order to evaluate and improve sound quality, it is necessary to quantitatively measure the sound quality for grasping the current situation and to measure how much it has been improved before and after the improvement.

  However, since sound quality is not a physical quantity, quantitative measurement cannot be performed. Therefore, it is difficult to set a target value. In the case of human sound quality evaluation, the expression is qualitative, such as “sound quality improved a little” or “substantially improved”. Furthermore, because of individual differences, it may be difficult to determine whether the evaluation differs from person to person or whether the obtained results can be generally said.

  If the sound quality is not quantitatively expressed by physical characteristics, it is impossible to objectively evaluate whether the measure was effective or how effective. For this reason, it is necessary to perform subjective evaluation experiments and perform statistical processing on the results to quantify sound quality.

By the way, as a physical quantity for evaluating sound quality, there is a psychoacoustic parameter. Typical examples are as follows (for example, the Japan Society of Mechanical Engineers "7th Design Engineering and System Division Lecture" Aiming for an innovative leap in design and systems for the 21st century! "" November 1997 10th and 11th, refer to “Sound / Vibration and Design, Color and Design (1)”, Section 089B “Sound Quality Evaluation System Using Dummy Head”.
・ Loudness (sone): loudness ・ sharpness (acum): relative distribution of high frequency components ・ tonality (tu): articulation, relative distribution of pure tones ・ asper: coarse sound Sensation, Fractation Strength (vacil): Fluctuation intensity, Brow feeling In addition to this, devices that can measure psychoacoustic parameters such as impulsiveness (iu): impact have emerged.

  These psychoacoustic parameters tend to increase discomfort as the values of all parameters increase. Among these, only loudness is standardized by ISO532B. For other parameters, the basic concept and definition are the same, but since the programs and calculation methods differ depending on the original research by the measuring instrument manufacturer, the measured values usually differ slightly from manufacturer to manufacturer. In addition, like impulsiveness, there are original parameters developed by measuring instrument manufacturers.

  The noise generated from office automation equipment such as copiers and printers is composed of many timbres due to the complexity of the mechanism. For example, low-frequency heavy sounds, high-frequency high-pitched sounds, shocking sounds, etc. However, it occurs while changing over time from a plurality of sound sources such as a motor, paper, and solenoid. Although humans judge these sounds comprehensively to determine whether they are uncomfortable, it is considered that they are determined by weighting which part of the sound is particularly related to discomfort. That is, there are psychoacoustic parameters that have a large influence on discomfort due to the timbre of the machine and psychoacoustic parameters that have a small influence.

  By the way, there are various types of image forming devices, such as small low-speed machines installed on the desk, medium-sized medium-speed machines installed on the desk side, and slightly spaced from the desk on the office floor. There is a large high-speed machine. Furthermore, there is a case where the mode can be set by changing the resolution, color, or monochrome image of a single machine, or by the difference in thickness or material of the sheet member that outputs the image. In this case, the image forming speed and the operating part of the machine may be different in one machine.

  These are used differently depending on the size of the office and the needs of the users. Naturally, the structure strength, the mechanical configuration, and the image forming process conditions differ depending on the machine, and the characteristics of the operating sound differ depending on the machine. In the case of a single image forming apparatus having multiple modes, there are multiple image forming speeds depending on the selected mode, and the parts that operate inside the image forming apparatus differ, so multiple operating sounds are generated depending on the mode. There is a case.

  Therefore, it is conceivable that the impression of the operating sound differs depending on the type of the image forming apparatus, and the uncomfortable sound source varies. In one machine, when the image forming mode is changed, the rotational speed of the drive system is changed, the generated frequency is changed, and the number of times the impact sound is generated per unit time is changed. In addition, the sound that is generated varies depending on the part that operates. In other words, the impression of the operating sound varies depending on the mode, and the sound source that feels uncomfortable varies.

  Therefore, the sound source that requires sound quality improvement may differ depending on the type of image forming apparatus. Furthermore, depending on the mode of the image forming apparatus, the sound source that requires sound quality improvement may differ. In other words, in the case of various types of image forming apparatuses and image forming apparatuses that have a plurality of operation modes and generate different sounds depending on the mode, only a single apparatus or a single mode sound quality evaluation is required to improve sound quality. However, it is not sufficient, and it is necessary to perform sound quality evaluation for each device and mode.

  Therefore, the inventor of the present application has performed sound quality evaluation of a plurality of image forming apparatuses and an image forming apparatus having a plurality of image forming modes for each apparatus and mode, and comprehensively analyzed the results to derive an accurate sound quality evaluation formula. Then, by using the sound quality evaluation formula, it is possible to improve the unpleasant sound source and lower the psychoacoustic parameter value, and to provide an image forming apparatus having a sound quality evaluation value or less that is acceptable to the user. The sound quality evaluation formula was derived by combining a decision tree and multiple logistic regression analysis as a result of the sound pair comparison in order to accurately predict sound quality.

  Then, by providing each image forming apparatus and an apparatus that has been improved in sound quality so as to be lower than the allowable sound quality corresponding to the image forming mode, any mode can be used regardless of which mode is used. Even if it is used, the problem of unpleasant noise in the image forming apparatus is solved.

  That is, the present invention solves the problem of unpleasant sound generation in the conventional image forming apparatus, provides a sound quality evaluation method capable of accurately evaluating the sound quality of the operation sound regardless of the apparatus type and the apparatus mode, and generates the unpleasant sound. It is an object to provide a reduced image forming apparatus. It is another object of the present invention to provide an image forming apparatus manufacturing method and an image forming apparatus remodeling method in which generation of unpleasant noise is reduced.

According to the present invention, there is provided a method for evaluating a sound generated by an image forming apparatus during image formation. The image forming apparatus extracts two arbitrary sounds from a plurality of types of sounds generated during image formation, and performs a pair comparison. The principal component analysis to the factor analysis of the difference in acoustic physical quantities of the two sounds when the two sounds are compared as a pair with the distance of the uncomfortable sound of the two sounds as an objective variable. A multiple regression analysis is performed using a plurality of factors as an explanatory variable, and a formula (A) for predicting the distance of discomfort of two sounds by a linear combination of factors is derived. From the formula (A), a paired comparison experiment is performed. The sound, which is the average value of the acoustic physical quantities of all used sounds (population), is defined as the sound quality evaluation value α ₀ = 0, thereby deriving a sound quality evaluation formula that predicts the discomfort of a single sound, By performing sound quality evaluation using the derived sound quality evaluation formula Solved.

The present invention also provides a method for manufacturing an image forming apparatus according to the present invention, wherein two arbitrary sounds are extracted from a plurality of types of sounds generated by the image forming apparatus during image formation, and evaluation is performed by a paired comparison method. , Using the distance of the uncomfortable sound of the two sounds by the evaluation as an objective variable, a plurality of results of factor analysis from the principal component analysis with respect to the value of the difference in the acoustic physical quantity of the two sounds when the two sounds are compared in pairs. A multiple regression analysis is performed using the factors as explanatory variables, and a formula (A) for predicting the distance of unpleasantness of two sounds is derived by linear combination of the factors. From the formula (A), all the sounds used in the paired comparison experiment are derived. The sound that is the average value of the acoustic physical quantities of (population) is defined as a sound quality evaluation value α ₀ = 0, thereby deriving a sound quality evaluation formula that predicts the discomfort of a single sound, and the derived sound quality evaluation formula And the sound quality evaluation using the sound quality evaluation formula satisfies a predetermined condition. This is solved by a method of manufacturing an image forming apparatus, wherein each part of the apparatus is designed and the image forming apparatus is manufactured according to the design contents.

In addition, the above-described problem is a method for remodeling an image forming apparatus according to the present invention, wherein two arbitrary sounds are extracted from a plurality of types of sounds generated by the image forming apparatus during image formation and evaluated by a paired comparison method. , Using the distance of the uncomfortable sound of the two sounds by the evaluation as an objective variable, a plurality of results of factor analysis from the principal component analysis with respect to the value of the difference in the acoustic physical quantity of the two sounds when the two sounds are compared in pairs. A multiple regression analysis is performed using the factors as explanatory variables, and a formula (A) for predicting the distance of unpleasantness of two sounds is derived by linear combination of the factors. From the formula (A), all the sounds used in the paired comparison experiment are derived. The sound that is the average value of the acoustic physical quantities of (population) is defined as a sound quality evaluation value α ₀ = 0, thereby deriving a sound quality evaluation formula that predicts the discomfort of a single sound, and the derived sound quality evaluation formula Of sound produced by the image forming device to be modified This is solved by a remodeling method for an image forming apparatus, wherein the image forming apparatus is remodeled based on the sound quality evaluation result.

  In addition, according to the present invention, there is provided an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming target is picked up at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus. Paired comparison of sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of acoustic physical quantity obtained from sound emitted by image forming apparatus when image forming is performed on sheet, and sound of image forming apparatus The discomfort factor component obtained from the results and the average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment are the sound pressure level average value, loudness average value, sharpness average value, tonality average value, Sound quality rating calculated by equation (a) using the average value of pulsiness and the output numerical value (ppm) of the image forming object sheet (A4 size lateral direction) per minute. Value S is solved by an image forming apparatus and satisfies the condition (b).

  Further, according to the present invention, there is provided an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming apparatus collects sound at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus. A pair of sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of acoustic physical quantity obtained from sound emitted by the image forming apparatus when image formation is performed on the target sheet, and sound of the image forming apparatus. The discomfort factor component obtained from the comparison result and the average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, Using the average impulsiveness value and the output numerical value (ppm) of the image forming target sheet (A4 size lateral direction) per minute, the sound quality calculated by the equation (c) Value S is solved by an image forming apparatus and satisfies the condition (b).

  Further, according to the present invention, there is provided an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming apparatus collects sound at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus. A pair of sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of acoustic physical quantity obtained from sound emitted by the image forming apparatus when image formation is performed on the target sheet, and sound of the image forming apparatus. The discomfort factor component obtained from the comparison result and the average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, Using the impulsiveness average value and the image forming speed (v: mm / s) for the image forming target sheet, the sound quality evaluation value S calculated by the equation (a) is (d) It is solved by an image forming apparatus according to claim meet.

  Further, according to the present invention, there is provided an image forming apparatus for forming an image on an image forming target sheet, wherein the image forming apparatus collects sound at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus. A pair of sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value of acoustic physical quantity obtained from sound emitted by the image forming apparatus when image formation is performed on the target sheet, and sound of the image forming apparatus. The discomfort factor component obtained from the comparison result and the average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, Using the impulsiveness average value and the image forming speed (v: mm / s) for the image forming target sheet, the sound quality evaluation value S calculated by the equation (c) is a condition ( ) It is solved by an image forming apparatus characterized by satisfying.

  Further, it is preferable that a plurality of image forming speeds or a plurality of operation modes are provided and the sound quality evaluation value S satisfies the above condition regardless of the image forming speed or the operation mode.

  The sound collection position is a neighbor position defined in ISO (International Organization For Standardization) 7779, and at least the sound quality evaluation value S calculated from the sound collection result of the sound in the front direction of the apparatus satisfies the condition. It is preferable to satisfy it.

  The sound collection position is a neighbor position defined by ISO (International Organization For Standardization) 7779, and the sound quality evaluation value S calculated from the sound collection results of the sound in the four directions of the front, rear, left and right of the apparatus. It is preferable that the average value of the above satisfies the above condition.

  The sound collection position is a neighbor position defined by ISO (International Organization For Standardization) 7779, and the sound quality evaluation value calculated from the sound collection result of sound in any one of the front, rear, left and right directions of the apparatus. It is preferable that S satisfies the above condition.

  The sound collection position is a neighbor position defined in ISO (International Organization For Standardization) 7779, and all the sound quality evaluations calculated from the sound collection results of the sound in the four directions of the front, rear, left and right of the device. It is preferred that the value S satisfies the above conditions.

In addition, it is preferable that a reduction unit that reduces a sound generated by the apparatus during image formation on the image formation target sheet is provided.
The image forming apparatus further includes a stepping motor that drives a predetermined portion during image formation on the image forming target sheet, and a bracket member that holds the stepping motor, and the reduction unit includes the stepping motor and the bracket member. It is preferable to have an elastic body interposed between them.

  It is preferable that the image forming apparatus further includes a stepping motor that drives a predetermined portion during image formation on the image forming target sheet, and the reduction unit includes a drive control unit that drives the stepping motor microsteps. .

  Further, it is preferable that a motor for driving a predetermined part at the time of image formation on the image forming target sheet is further provided, and the reduction means has a Helmholtz resonator disposed in the vicinity of the motor.

  Further, the image bearing member further includes a cylindrical image carrier having a hollow portion, and a charging unit that charges the surface of the image carrier, and the reduction unit includes a vibration of the image carrier in the hollow portion of the image carrier. It is preferable to have a damping member that suppresses vibration.

  Further, the guide member is formed of a flexible sheet that guides the image forming target sheet along a predetermined transport path, and an end portion that is in contact with the transported image forming target sheet is a bent portion of the flexible sheet. It is preferable to further include a guide member.

Further, it is preferable that the toner used for image formation on the image forming target sheet is a toner containing wax.
The reduction means is a paper feed conveyance control means for controlling the operation of the electromagnetic clutch provided in each of the paper feed conveyance paths having a plurality of paper feed stages to be an electromagnetic clutch higher than the paper feed stage to be used. This is preferable.

  In addition, the above-described problem is a method of manufacturing an image forming apparatus for forming an image on an image forming target sheet according to the present invention, and a sound collection position that is approximately 1 m away from an end surface of the image forming apparatus to be manufactured. The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness of the acoustic physical quantity obtained from the sound emitted by the image forming apparatus when the image is formed on the image forming target sheet. Sound pressure level average value, loudness average, which is the average value of the values, the uncomfortable factor component obtained from the paired comparison result of the sound of the image forming apparatus, and the acoustic physical quantity of all the test sounds used in the paired comparison experiment Value, sharpness average value, tonality average value, impulsiveness average value, and output numerical value (ppm) of the image forming target sheet (A4 size lateral direction) per minute. A design step for designing each part of the apparatus so that the sound quality evaluation value S calculated by the equation (a) satisfies the condition (b), and a manufacturing step for manufacturing the image forming apparatus according to the design contents made by the design step. It is solved by the manufacturing method of the image forming apparatus characterized by comprising.

  In addition, the above-described problem is a method of manufacturing an image forming apparatus for forming an image on an image forming target sheet according to the present invention, and a sound collection position that is approximately 1 m away from an end surface of the image forming apparatus to be manufactured. The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness of the acoustic physical quantity obtained from the sound emitted by the image forming apparatus when the image is formed on the image forming target sheet. Sound pressure level average value, loudness average, which is the average value of the values, the uncomfortable factor component obtained from the paired comparison result of the sound of the image forming apparatus, and the acoustic physical quantity of all the test sounds used in the paired comparison experiment Value, sharpness average value, tonality average value, impulsiveness average value, and output numerical value (ppm) of the image forming target sheet (A4 size lateral direction) per minute. In addition, a design step for designing each part of the apparatus so that the sound quality evaluation value S calculated by the equation (c) satisfies the condition (b), and manufacture for manufacturing the image forming apparatus according to the design contents made by the design step. The method is solved by a method for manufacturing an image forming apparatus.

  In addition, the above-described problem is a method of manufacturing an image forming apparatus for forming an image on an image forming target sheet according to the present invention, and a sound collection position that is approximately 1 m away from an end surface of the image forming apparatus to be manufactured. The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness of the acoustic physical quantity obtained from the sound emitted by the image forming apparatus when the image is formed on the image forming target sheet. Sound pressure level average value, loudness average, which is the average value of the values, the uncomfortable factor component obtained from the paired comparison result of the sound of the image forming apparatus, and the acoustic physical quantity of all the test sounds used in the paired comparison experiment Value, sharpness average value, tonality average value, impulsiveness average value, and image forming speed (v: mm / s) for the image forming target sheet, The calculated sound quality evaluation value S includes a design step of designing each part of the apparatus so as to satisfy the condition (d), and a manufacturing step of manufacturing the image forming apparatus according to the design contents made by the design step. This is solved by the manufacturing method of the image forming apparatus.

  In addition, the above-described problem is a method of manufacturing an image forming apparatus for forming an image on an image forming target sheet according to the present invention, and a sound collection position that is approximately 1 m away from an end surface of the image forming apparatus to be manufactured. The sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness of the acoustic physical quantity obtained from the sound emitted by the image forming apparatus when the image is formed on the image forming target sheet. Sound pressure level average value, loudness average, which is the average value of the values, the uncomfortable factor component obtained from the paired comparison result of the sound of the image forming apparatus, and the acoustic physical quantity of all the test sounds used in the paired comparison experiment Value, sharpness average value, tonality average value, impulsiveness average value, and image forming speed (v: mm / s) for the image forming target sheet, The calculated sound quality evaluation value S includes a design step of designing each part of the apparatus so as to satisfy the condition (d), and a manufacturing step of manufacturing the image forming apparatus according to the design contents made by the design step. This is solved by the manufacturing method of the image forming apparatus.

  Further, the above-described problem is a method of remodeling an image forming apparatus for forming an image on an image forming target sheet according to the present invention, and a sound collecting position that is approximately 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collecting step for picking up sound generated by the image forming apparatus when image formation is performed on the image forming target sheet, and a sound pressure level of an acoustic physical quantity obtained from a sound collecting result in the sound collecting step. Value, loudness value, sharpness value, tonality value, impulsiveness value, factor component of discomfort obtained from the paired comparison result of the sound of the image forming apparatus, and the acoustic physical quantity of all the test sounds used in the paired comparison experiment Sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value, and the image forming target sheet per minute A modification step of modifying the configuration of the device so that the sound quality evaluation value S calculated by the equation (a) satisfies the condition (b) using the output numerical value (ppm) of (A4 size lateral direction). This is solved by a method for remodeling an image forming apparatus.

  Further, the above-described problem is a method of remodeling an image forming apparatus for forming an image on an image forming target sheet according to the present invention, and a sound collecting position that is approximately 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collecting step for picking up sound generated by the image forming apparatus when image formation is performed on the image forming target sheet, and a sound pressure level of an acoustic physical quantity obtained from a sound collecting result in the sound collecting step. Value, loudness value, sharpness value, tonality value, impulsiveness value, factor component of discomfort obtained from the paired comparison result of the sound of the image forming apparatus, and the acoustic physical quantity of all the test sounds used in the paired comparison experiment Sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value, and the image forming target sheet per minute A modification step of modifying the configuration of the device so that the sound quality evaluation value S calculated by the equation (c) satisfies the condition (b) using the output numerical value (ppm in the A4 size lateral direction). This is solved by a method for remodeling an image forming apparatus.

  Further, the above-described problem is a method of remodeling an image forming apparatus for forming an image on an image forming target sheet according to the present invention, and a sound collecting position that is approximately 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collecting step for picking up sound generated by the image forming apparatus when image formation is performed on the image forming target sheet, and a sound pressure level of an acoustic physical quantity obtained from a sound collecting result in the sound collecting step. Value, loudness value, sharpness value, tonality value, impulsiveness value, factor component of discomfort obtained from the paired comparison result of the sound of the image forming apparatus, and the acoustic physical quantity of all the test sounds used in the paired comparison experiment Sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value, and an image form for the image forming sheet. The sound quality evaluation value S calculated by the equation (a) using the speed (v: mm / s) includes a modification step for modifying the configuration of the device so as to satisfy the condition (d). This is solved by a method for remodeling the image forming apparatus.

  Further, the above-described problem is a method of remodeling an image forming apparatus for forming an image on an image forming target sheet according to the present invention, and a sound collecting position that is approximately 1 m away from an end surface of the image forming apparatus to be remodeled. A sound collecting step for picking up sound generated by the image forming apparatus when image formation is performed on the image forming target sheet, and a sound pressure level of an acoustic physical quantity obtained from a sound collecting result in the sound collecting step. Value, loudness value, sharpness value, tonality value, impulsiveness value, factor component of discomfort obtained from the paired comparison result of the sound of the image forming apparatus, and the acoustic physical quantity of all the test sounds used in the paired comparison experiment Sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value, and an image form for the image forming sheet. The sound quality evaluation value S calculated by the equation (c) using the speed (v: mm / s) includes a remodeling step for modifying the configuration of the device so as to satisfy the condition (d). This is solved by a method for remodeling the image forming apparatus.

  According to the sound quality evaluation method of claim 1, after deriving a model for predicting the distance of discomfort of two sounds in the analysis combining the result of the paired comparison method and the factor analysis and the multiple regression analysis, it is used for the paired comparison. By defining the output (sound quality evaluation value S) as S = 0 (center value) when the average value of the acoustic physical quantity of the test sound was input, the average of the acoustic physical quantity of the sound and the population of the sound When the difference between the values is input, it is possible to derive a high-accuracy sound quality evaluation formula capable of outputting the distance of discomfort when compared with the sound of the sound quality evaluation value = 0. Moreover, the evaluation can be performed without performing a relatively large number of experiments, and as a result, the work relating to the sound quality evaluation is simplified.

  According to the method of manufacturing the image forming apparatus of the second aspect, since the apparatus is manufactured based on sound quality evaluation using a highly accurate sound quality evaluation formula, it is possible to provide an image forming apparatus that hardly emits unpleasant sound. .

  According to the remodeling method of the image forming apparatus of the third aspect, since the apparatus is remodeled based on sound quality evaluation using a highly accurate sound quality evaluation formula, an image forming apparatus that hardly generates unpleasant sound can be provided. .

  The image forming apparatus according to claim 4 is configured such that the sound quality evaluation value S derived by the sound quality evaluation formula (a) matches the condition (b) corresponding to the output numerical value of the image forming target sheet per minute. Therefore, the discomfort given to the user by the sound generated by the image forming apparatus can be reduced.

  Further, since the condition (b) varies depending on the output value of the image formation target sheet, even if the apparatus has a plurality of operation modes and the image formation speed varies in each mode, the operation sound The sound quality evaluation value S can be obtained by using one sound quality evaluation formula (a), and the sound quality evaluation value S satisfies a condition that fluctuates depending on the speed. Regardless of the mode, it is possible to reduce the uncomfortable feeling given to the user by the operation sound.

  The image forming apparatus according to claim 5 is configured such that the sound quality evaluation value S derived by the sound quality evaluation formula (c) matches the condition (b) corresponding to the output numerical value of the image forming target sheet per minute. Therefore, the discomfort given to the user by the sound generated by the image forming apparatus can be reduced.

  Further, since the condition (b) varies depending on the output value of the image formation target sheet, even if the apparatus has a plurality of operation modes and the image formation speed varies in each mode, the operation sound Since the sound quality evaluation value S can be obtained from the parameter values obtained from the above using one sound quality evaluation formula (c), and the sound quality evaluation value S satisfies the condition that varies depending on the speed, the image formation target sheet Regardless of the output value or mode, it is possible to reduce the discomfort given to the user by the operation sound.

  The image forming apparatus according to claim 6 is configured such that the sound quality evaluation value S derived by the sound quality evaluation formula (a) matches the condition (d) corresponding to the output numerical value of the image forming target sheet per minute. Therefore, the discomfort given to the user by the sound generated by the image forming apparatus can be reduced.

  Further, since the condition (d) varies depending on the output value of the image formation target sheet, even if the apparatus has a plurality of operation modes and the image formation speed varies in each mode, the operation sound The sound quality evaluation value S can be obtained using the single sound quality evaluation formula (a), and the sound quality evaluation value S satisfies the condition that varies depending on the speed. Regardless of the output value or mode, there is also an effect that the discomfort given to the user by the operation sound can be reduced.

  The image forming apparatus according to claim 7 is configured such that the sound quality evaluation value S derived by the sound quality evaluation formula (c) matches the condition (d) corresponding to the output numerical value of the image forming target sheet per minute. Therefore, the discomfort given to the user by the sound generated by the image forming apparatus can be reduced.

  Further, since the condition (d) varies depending on the output value of the image formation target sheet, even if the apparatus has a plurality of operation modes and the image formation speed varies in each mode, the operation sound Since the sound quality evaluation value S can be obtained from the parameter values obtained from the above using one sound quality evaluation formula (c), and the sound quality evaluation value S satisfies the condition that varies depending on the speed, the image formation target sheet Regardless of the output value or mode, there is also an effect that the discomfort given to the user by the operation sound can be reduced.

According to the configuration of the eighth aspect, it is possible to reduce discomfort given to the user by the operation sound of the apparatus regardless of the image forming speed and the operation mode.
According to the configuration of the ninth aspect, the sound quality evaluation value S obtained from the result of sound collection at a position on the front side of the apparatus where the user of the image forming apparatus is likely to be normally positioned satisfies the above-described condition. Therefore, it is possible to reduce discomfort given to the user by the operation sound of the image forming apparatus.

  According to the configuration of the tenth aspect, the sound quality evaluation value S is derived from the sound collected in the four directions of the image forming apparatus, and the average value satisfies the condition. The discomfort given to the user can be reduced.

  According to the configuration of claim 11, since the sound quality evaluation value S derived from the sound collected on at least one direction side of the image forming apparatus satisfies the condition, the operation of the image forming apparatus with respect to the user on the direction side The discomfort that the sound gives to the user can be reduced.

  According to the configuration of the twelfth aspect, since the sound quality evaluation value S derived from the sound collected in all the anteroposterior and lateral directions of the image forming apparatus satisfies the condition, the image can be displayed regardless of the direction of the user. The discomfort that the operation sound of the forming apparatus gives to the user can be reduced.

  According to the configuration of the thirteenth aspect, it is possible to reduce the sound emitted from the image forming apparatus during image formation by the reducing unit, whereby the sound quality evaluation value S derived from the sound emitted from the image forming apparatus satisfies the condition, and the image forming apparatus The discomfort given to the user by the operation sound can be reduced.

  According to the structure of the fourteenth aspect, since vibration during operation of the stepping motor is not directly transmitted to the bracket member but is absorbed by the elastic body, vibration transmitted to the bracket member is reduced, and sound generated due to this vibration is reduced. Can be reduced.

  With the configuration of the fifteenth aspect, the stepping motor can be driven with a step angle smaller than the step angle of a normal stepping motor determined mechanically by microstep driving the stepping motor. As a result, the rotor driving of the stepping motor becomes smooth, generation of vibrations can be suppressed, and operating noise can be reduced.

  According to the configuration of the sixteenth aspect, the Helmholtz resonator has a function of confining the sound component of the Helmholtz resonance frequency determined from its shape and the like in the cavity, that is, attenuating the sound component of the resonance frequency. Therefore, by installing a Helmholtz resonator having a resonance frequency corresponding to the main frequency component of the sound generated by the motor in the vicinity, the amount of the sound generated by the motor leaking outside the apparatus can be reduced.

  According to the structure of claim 17, when the charging means is charged to the image carrier, the image carrier vibrates due to the charging action, and a sound is generated due to this vibration, but the image carrier is generated in the image carrier. Vibration can be suppressed by the damping member, and generated sound can be reduced. Further, since the vibration damping member is disposed inside the image carrier, an effect that it is not necessary to prepare a new installation space or the like can be obtained.

  According to the structure of the eighteenth aspect, since the bent portion of the flexible sheet in the guide member comes into contact with the image forming target sheet to be conveyed, it is possible to reduce the sound generated by the contact. In other words, when the flexible sheet has a predetermined size, it is usually cut, but the cut portion of the flexible sheet has burrs or the like, and when this portion comes into contact with the image forming target sheet, an irritating sound is generated. . On the other hand, since the bent portion, not the cut portion, is in contact with the image forming target sheet as described above, generation of annoying sound can be reduced.

  According to the structure of claim 19, by using a toner containing wax, an operation such as oil application to the fixing member in order to improve the detachability between the fixing member and the image forming target sheet during the fixing process in image formation. There is no need to do. Therefore, it is possible to reduce the sound generated with the oil application work.

  According to the structure of the twentieth aspect, by operating only the electromagnetic clutch of the paper feed stage to be used to reduce the metal impact sound, the impulsiveness value is lowered, so that the generation of harsh sound can be reduced.

  According to the image forming apparatus manufacturing method of claim 21, the sound quality evaluation value S derived by the sound quality evaluation formula (a) matches the condition (b) corresponding to the output numerical value of the image forming target sheet per minute. Since each part of the apparatus is designed and the image forming apparatus is manufactured based on the design contents, an image forming apparatus that reduces the discomfort given to the user by the operation sound can be manufactured and provided to the user. .

  Further, since the condition (b) varies depending on the output value of the image forming target sheet, the parameter value obtained from the operation sound is used for the sound quality using one sound quality evaluation formula (a) regardless of the image forming speed and the operation mode. The evaluation value S can be obtained, and the sound quality evaluation value S satisfies the condition that fluctuates depending on the speed, so that the discomfort given to the user by the operation sound can be reduced regardless of the image forming speed and the operation mode. An effect is obtained.

According to the method of manufacturing an image forming apparatus of claim 22, the sound quality evaluation value S derived by the sound quality evaluation formula (c) matches the condition (b) corresponding to the output value of the image forming target sheet per minute. Since each part of the apparatus is designed and the image forming apparatus is manufactured based on the design contents, an image forming apparatus that reduces the discomfort given to the user by the operation sound can be manufactured and provided to the user. .

  In addition, since the condition (b) varies depending on the output value of the image forming target sheet, the parameter value obtained from the operation sound is obtained by using one sound quality evaluation formula (c) regardless of the image forming speed and the operation mode. The evaluation value S can be obtained, and the sound quality evaluation value S satisfies the condition that fluctuates depending on the speed, so that the discomfort given to the user by the operation sound can be reduced regardless of the image forming speed and the operation mode. An effect is obtained.

  According to the image forming apparatus manufacturing method of claim 23, the sound quality evaluation value S derived by the sound quality evaluation formula (a) matches the condition (d) corresponding to the output numerical value of the image forming target sheet per minute. Since each part of the apparatus is designed and the image forming apparatus is manufactured based on the design contents, it is possible to manufacture and provide the user with the image forming apparatus in which the discomfort caused by the operation sound to the user is reduced.

  Further, since the condition (b) varies depending on the output value of the image forming target sheet, the parameter value obtained from the operation sound is used for the sound quality using one sound quality evaluation formula (a) regardless of the image forming speed and the operation mode. The evaluation value S can be obtained, and the sound quality evaluation value S satisfies the condition that fluctuates depending on the speed, so that the discomfort given to the user by the operation sound can be reduced regardless of the image forming speed and the operation mode. An effect is obtained.

  According to the method of manufacturing an image forming apparatus of claim 24, the sound quality evaluation value S derived by the sound quality evaluation formula (c) matches the condition (d) corresponding to the output numerical value of the image forming target sheet per minute. Since each part of the apparatus is designed and the image forming apparatus is manufactured based on the design contents, an image forming apparatus that reduces the discomfort given to the user by the operation sound can be manufactured and provided to the user. .

  In addition, since the condition (b) varies depending on the output value of the image forming target sheet, the parameter value obtained from the operation sound is obtained by using one sound quality evaluation formula (c) regardless of the image forming speed and the operation mode. The evaluation value S can be obtained, and the sound quality evaluation value S satisfies the condition that fluctuates depending on the speed, so that the discomfort given to the user by the operation sound can be reduced regardless of the image forming speed and the operation mode. An effect is obtained.

  According to the method of manufacturing an image forming apparatus of claim 25, the sound quality evaluation value S derived by the sound quality evaluation formula (a) matches the condition (b) corresponding to the output value of the image forming target sheet per minute. Thus, since the configuration of each part of the apparatus is modified, it is possible to provide an image forming apparatus in which the discomfort that the operation sound gives to the user is reduced.

  Further, since the condition (b) varies depending on the output value of the image forming target sheet, the parameter value obtained from the device operation sound after the modification is used as one sound quality evaluation formula regardless of the output value of the image forming target sheet and the operation mode. The sound quality evaluation value S can be obtained using (a), and the sound quality evaluation value S satisfies a condition that varies depending on the output value of the image forming target sheet. Regardless of the mode, it is possible to reduce the discomfort that the operation sound gives to the user.

  According to the manufacturing method of the image forming apparatus of claim 26, the sound quality evaluation value S derived by the sound quality evaluation formula (c) matches the condition (b) corresponding to the output value of the image forming target sheet per minute. Since the configuration of each part of the apparatus is remodeled as described above, it is possible to provide an image forming apparatus in which the discomfort given to the user by the operation sound is reduced.

  Further, since the condition (b) varies depending on the output value of the image forming target sheet, the parameter value obtained from the device operation sound after the modification is used as one sound quality evaluation formula regardless of the output value of the image forming target sheet and the operation mode. The sound quality evaluation value S can be obtained using (c), and the sound quality evaluation value S satisfies a condition that varies depending on the output value of the image forming target sheet. Regardless of the mode, it is possible to reduce the discomfort that the operation sound gives to the user.

  According to the manufacturing method of the image forming apparatus of claim 27, the sound quality evaluation value S derived by the sound quality evaluation formula (a) matches the condition (d) corresponding to the output value of the image forming target sheet per minute. Since the configuration of each part of the apparatus is remodeled as described above, it is possible to provide an image forming apparatus in which the discomfort given to the user by the operation sound is reduced.

  In addition, since the condition (d) varies depending on the output value of the image forming target sheet, the parameter value obtained from the device operation sound after the modification is used as one sound quality evaluation formula regardless of the output value of the image forming target sheet and the operation mode. The sound quality evaluation value S can be obtained using (a), and the sound quality evaluation value S satisfies a condition that varies depending on the output value of the image forming target sheet. Regardless of the mode, it is possible to reduce the discomfort that the operation sound gives to the user.

  According to the method of manufacturing an image forming apparatus of claim 28, the sound quality evaluation value S derived by the sound quality evaluation formula (c) matches the condition (d) corresponding to the output value of the image forming target sheet per minute. Since the configuration of each part of the apparatus is remodeled as described above, it is possible to provide an image forming apparatus in which the discomfort given to the user by the operation sound is reduced.

  In addition, since the condition (d) varies depending on the output value of the image forming target sheet, the parameter value obtained from the device operation sound after the modification is used as one sound quality evaluation formula regardless of the output value of the image forming target sheet and the operation mode. The sound quality evaluation value S can be obtained using (c), and the sound quality evaluation value S satisfies a condition that varies depending on the output value of the image forming target sheet. Regardless of the mode, it is possible to reduce the discomfort that the operation sound gives to the user.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The sound quality evaluation method of the present invention evaluates noise generated by various image forming apparatuses, and performs sound quality evaluation of the image forming apparatus using a sound quality evaluation formula described below, and the evaluation result is a predetermined condition. By designing, manufacturing, or remodeling the image forming apparatus so as to satisfy the above, it is possible to provide an image forming apparatus that hardly generates unpleasant noise. The image forming apparatus used for noise evaluation will be described later, and a method for evaluating noise generated by the image forming apparatus during image formation will be described first.

[I. Sound quality evaluation method]
As a method for evaluating sound quality, it is conceivable to derive a sound quality evaluation formula that can predict sound quality using an acoustic physical quantity from experimental results obtained by the Scheffe paired comparison method.

  The paired comparison method creates two pairs of stimuli for stimuli that are difficult to be absolutely evaluated, such as sound, smell, and taste. Then, all the combinations of stimuli to be evaluated are paired, the difference between the scores is obtained, and a relative average score is given for each stimulus. This method focuses on the fact that it is difficult for humans to evaluate one stimulus, but it is relatively easy to compare two stimuli to determine which is better or worse. It is.

For example, when there are three stimuli A1, A2, and A3, the respective stimulus models are y1 = μ + α1, y2 = μ + α2, and y3 = μ + α3. For simplicity, it is assumed that this model is composed only of the total average μ and the main effect αi (i = 1, 2, 3). In addition, the sum of the main effects is set to 0, as in the general constraint necessary for parameter estimation in the design of experiments.
α1 + α2 + α3 = 0 ... Formula 1

The fact that absolute evaluation is impossible means that there is no idea about the value of μ, and that y1, y2, and y3 cannot be measured directly, but as described above, the difference between the two stimuli is taken. Then, μ disappears and can be expressed by the difference of the main effect only.
y1−y2 = (μ + α1) − (μ + α2) = α1−α2 (2)
y1−y3 = (μ + α1) − (μ + α3) = α1−α3 (3)
y2−y3 = (μ + α2) − (μ + α3) = α2−α3 (4)

Here, Expression 2 + Expression 3 is
2y1- (y2 + y3) = 2α1- (α2 + α3)
However, 2y1− (y2 + y3) = 3α1 according to the above constraint 1
It becomes. That is, the effect of each stimulus can be extracted. And if the effect of each stimulus at this time is expressed by a linear function by the difference in the acoustic physical properties of the image forming apparatus,
α1−α2 = b (x1−x2)...
The relationship is obtained. Here, b is a constant, and xi is i = 1, 2, 3,... N. The intercept cancels because it models the difference between the two stimuli.

Next, principal component analysis will be described.
The purpose of principal component analysis is to explain the correlation structure between variables using some linear combination of variables. This is the creation and preferred interpretation of a new evaluation index by shaping and combining. In order to make effective use of principal component analysis, it is desirable that the variables can be assumed to follow a multivariate normal distribution. Moreover, it is necessary to be able to measure an appropriate correlation between the variables. Principal component analysis is useful when you want to explain multivariate data with a small number of orthogonal indices.

When there are n original variables, n principal components are formed.
The principal component is a composite variable obtained by linear combination of the original variables. The first principal component has the largest variance, and the second principal component having the next largest variance is orthogonal to the first principal component (no correlation) ) Will be decided. Each principal component is calculated by linearly combining the eigenvector of the correlation matrix between variables and the original variable that has been averaged. That is, in order to perform the principal component analysis, it is necessary to first perform a correlation analysis of the original variables (acoustic physical quantities in this case).

When principal component analysis is performed, there are the following outputs.
The eigenvalue is an index representing the variance of the principal component and the magnitude of the information amount of the obtained principal component.
The eigenvector is a coefficient of linear combination of the original variables. It becomes the weight to the main component.

The contribution rate is an index representing how much the information amount of the original variable can be explained. The higher the correlation, the higher the contribution rate.
The cumulative contribution rate is an index in which the contribution rate is accumulated from the one having a large eigenvalue.

The factor loading is the correlation between the principal component and the original variable. Used to interpret principal components. When the absolute value of the factor loading is large, the relation with the main component is strong.
If all n principal components are employed, the total variance and structure are the same as the original variable group. Since there is a condition that there is no correlation between each principal component and the previous principal component (orthogonality), the dispersion is always smaller than that of the previous principal component. Also, most of the sample variance can be explained by just the first few principal components.

  An example of principal component analysis is shown in the figure. FIG. 1 shows a strong correlation between x and y. When the variables are linearly combined and the most accurate representation of the point distribution is calculated, P1 in the figure is obtained. When the plot is rotated and inverted so that P1 becomes the principal axis, the result is as shown in FIG. 2, and a set of two-dimensional points x and y is approximated in one dimension. The second main component P2 is distributed in a form orthogonal to P1.

Even in the case of high-order data, if the first three principal components are plotted as the rotation axes, a three-dimensional display with an optimum angle is often obtained.
When principal component analysis is performed with the original variables assigned to two or three axes, the principal components are displayed as lines from the center on the rotation plot. These lines are called P-lines (bi-plot lines) and represent approximations of the principal components as linear combinations of variables on the axis. If there are only two or three variables, the line represents the principal component itself. The length of the line from the center corresponds to the eigenvalue or variance of the principal component. Since the first principal component covers most of the variance, the P1 line is much longer than the other lines. In addition, the main component having a small variance does not need to be considered because the influence is small. Whether to consider is determined by whether the variance is smaller than 1. If there are 5 variables, the total eigenvalue of the principal component is 5. When the eigenvalue is less than 1, the information amount of the original variable is 1, so that the main component having only less information amount as a synthesis index is often not interpreted. However, when it is difficult to interpret the principal component, a simple structuring is attempted by varimax rotation. However, since the eigenvalue may be changed by the simple structuring, it is necessary to perform trial and error.

  Factor analysis (Factor-Analysis) is to rotate the principal component and compare the direction of the component with the analysis variable so that it can be easily interpreted. Whether or not the interpretation is simplified by the rotation greatly depends on the number of components to be rotated. This rotation method is called the varimax rotation method and has been conventionally used in factor analysis (Kaiser, H.F.1958).

  Therefore, in the present invention, with respect to the sound generated by the image forming apparatus, the difference between the scores (the difference between the scores of a pair of sounds obtained by a paired comparison method experiment) is used as an objective variable, and a plurality of factor components are used as explanatory variable groups. If regression analysis is performed, a model for predicting the difference in evaluation can be obtained. In addition, since the factor component is composed of acoustic physical quantities, when the physical characteristic values of the two sounds to be compared are input to the factor component, a prediction of the difference in evaluation such as how discomfort the two sounds differ can be output. A model is obtained.

Next, the process will be described in detail based on actual experiments, analysis, and the like.
The flow of the sound quality evaluation experiment of the image forming apparatus, the identification of the unpleasant sound source, and the sound quality evaluation formula derivation is as follows.
(1) Collection of operation sound of image forming apparatus (2) Analysis of operation sound (3) Creation of test sound from collected operation sound (4) Acoustic physical quantity (psychoacoustic parameters, sound pressure level) of test sound Measurement (5) Paired comparison method experiment with test sound for each model or mode (Scheffe's paired comparison method Ura's variation)
(6) Identification of unpleasant sound source (7) Creation of analysis data of difference model (8) Principal component analysis (9) Factor analysis (10) Difference in predicting “difference in subjective evaluation value between two sounds” by “factor” Derivation of model formula for each layer (11) Derivation of relative model formula (sound quality evaluation formula) for predicting the discomfort of a single sound (12) Verification of derived sound quality evaluation formula

Details of the above process will be described below.
(1) Collection of operation sound of image forming apparatus The operation sound of the image forming apparatus was collected by binaural (binaural) recording using a head acoustic system dummy head HMS (Head Measurement System) III. This is because by performing binaural recording and reproducing with dedicated headphones in this way, it can be reproduced as if a human actually heard the sound generated by the machine.

  In addition, the image forming apparatus which is a device to be measured executes an image forming operation at three types of image forming speeds according to the operation mode with respect to an image forming apparatus having a plurality of modes to be described later. Measurements were made for each of the three operating modes.

  Further, since a desktop type (desktop) image forming apparatus, a medium-speed image forming apparatus, and a large-sized (console type) image forming apparatus, which will be described later, have only a monochrome single mode, the operation was measured.

The measurement conditions are as follows (see FIG. 3).
・ Recording environment: Semi-anechoic room ・ Dummy head 503 ear position (sound collection position) 504: Height 1.2 m, horizontal distance 1 m (1 ± 0.03 m) from the measured device 501 end surface, width direction Is the central position of the device, the recording direction ... the front (the surface where the operation unit 502 of the image forming apparatus is located), the rear, the left and right four directions, the recording mode ... FF (free field: for anechoic room)
・ HP filter: 22Hz

  The height of the dummy head is set to 1.2 m in consideration of the fact that there are many cases where an instruction is issued from a personal computer or the like while the user is seated as a recent method of using the image forming apparatus. . Of course, the dummy head may be installed at a height of 1.5 m in consideration of a state where a human is standing.

  By the way, the sound emitted by the image forming apparatus is usually different for each direction. This is because the positions of various motors, the sheet conveyance path, and the position of the paper discharge port are not located at the center of the apparatus but are distributed. Therefore, the sound produced by a certain sound source (such as a motor) can be heard well on the right side, but the sound collected for each direction is different, such as not being heard well on the left side. The sample sound used for the experiment described below may be collected in any direction, but when performing a paired comparison experiment, it is necessary to unify the sample sound in any one direction. Therefore, in this experiment, it is considered that the user has the most chances to hear on the front side, but the rear side of the image forming apparatus is usually installed along the wall, so there is little opportunity to hear the sound on the rear side. Therefore, it was decided to use what was collected on the front side as the test sound.

(2) Analysis of operation sound Next, the operation sound of the image forming apparatus collected as described above was analyzed.
First, when the color printer 100 described later as an image forming apparatus having a plurality of modes is analyzed for noise when operating at a color of 28 ppm, that is, at a printing speed of 28 ppm, an analysis result as shown in FIG. 4 is obtained. . The upper side of FIG. 4 represents the collected sound on the time axis, and the lower side of FIG. 4 represents the collected sound on the frequency axis. In this specification, “ppm” is the number of output sheets per minute of A4 landscape paper.

  From this result, seven main sound sources were extracted. First, the fixing oil application impact sound of the fixing unit 50 was extracted on the time axis. On the frequency axis, color development drive system sound, paper feed stepping motor sound, charging sound, drum drive stepping motor sound, polygon mirror motor sound, and paper sliding sound were extracted.

  When the noise when the color was 14 ppm, that is, when the printing speed was 14 ppm, was analyzed, an analysis result as shown in FIG. 5 was obtained. The upper side of FIG. 5 represents the collected sound on the time axis, and the lower side of FIG. 5 represents the collected sound on the frequency axis. From this result, as the main sound source, the fixing oil application impact sound is extracted on the time axis, and the feeding stepping motor sound, charging sound, drum drive motor sound, polygon mirror motor sound, paper sliding sound are extracted on the frequency axis. Extracted.

  Analysis of noise at monochrome 38 ppm, that is, when operating at a printing speed of 38 ppm, the analysis results shown in FIG. 6 were obtained. The upper side of FIG. 6 represents the collected sound on the time axis, and the lower side of FIG. 6 represents the collected sound on the frequency axis. From this result, as a main sound source, fixing oil application impact sound was extracted on the time axis, and development drive system sound, charging sound, drum driving stepping motor sound, and paper sliding sound were extracted on the frequency axis.

  Next, when noise was analyzed when a monochrome printer 200 (20 ppm), which will be described later, was operated as a desktop (desktop) image forming apparatus, an analysis result as shown in FIG. 7 was obtained. The upper side of FIG. 7 represents the collected sound on the time axis, and the lower side of FIG. 7 represents the collected sound on the frequency axis. From these results, metal (clutch / solenoid) impact sound and paper impact sound were extracted on the time axis as main sound sources, and main motor sound and AC charging sound were extracted on the frequency axis.

  Next, analysis of noise when an in-body paper discharge type copying machine 300 (27 ppm), which will be described later, operates as a medium-speed image forming apparatus, an analysis result as shown in FIG. 8 was obtained. The upper side of FIG. 8 represents the collected sound on the time axis, and the lower side of FIG. 8 represents the collected sound on the frequency axis. From these results, as the main sound source, paper feed sound and metal (clutch / solenoid) impact sound were extracted on the time axis, and main motor sound, paper feed sound, and paper sliding sound were extracted on the frequency axis.

  Next, when the noise when the copier 400 with ADF 400 (65 ppm) described later is operated as a large-sized (console type) image forming apparatus is analyzed, an analysis result as shown in FIG. 9 is obtained. The upper side of FIG. 9 represents the collected sound on the time axis, and the lower side of FIG. 9 represents the collected sound on the frequency axis. From these results, paper impact sounds and metal (clutch / solenoid) impact sounds are extracted on the time axis as main sound sources, and paper impact sounds, bank motor sounds, development motor sounds, main motor sounds, paper on the frequency axis. The sliding sound was extracted.

(3) Creation of test sound from the collected operation sound Next, as described above, the sound collected at the position on the front side of the device was collected using “ArtemiS”, a sound quality analysis software manufactured by Head Acoustics. The sound was processed.

  As a sound processing method performed in this experiment, a sound during one cycle of the printing operation was cut out from the collected original sound. Then, among the sounds in one cycle period, a filter process was performed on the frequency source or the time axis on the part related to the main sound source extracted as described above, and a process of attenuating or enhancing these parts was performed. That is, three levels of sound (emphasis / original sound / attenuation) were created for each sound source extracted in one mode. When the created test sound is presented to the subject, it is difficult to make a judgment because it is too short if one cycle of sound is heard.

  As described above, the sounds collected on the front, rear, left and right sides of the image forming apparatus are different from each other, but on the front side created in this experiment rather than the range of psychoacoustic parameter values obtained from such four-direction sounds. It has been confirmed that the range of psychoacoustic parameter values obtained from three test sounds obtained by emphasizing and attenuating the collected sounds is wider. In other words, a subjective evaluation experiment using three sounds obtained by emphasizing and attenuating sounds collected on the front side as in this experiment covers the characteristics of sounds obtained from sounds collected in four directions. Therefore, the discomfort in the four directions can be calculated from the sound quality evaluation formula.

  Based on the sound collected on the front side as described above, if three levels of sound (emphasis, original sound, attenuation) are created from the sound emitted by the main sound source extracted for each image forming apparatus, the sound generated at the time of each image formation Nine sounds were created based on the L9 orthogonal table with different levels of sound sources extracted for. In the Scheffe paired comparison method (Ura's variation), it is necessary to carry out a comparison experiment with a brute force combination of the test sounds. 72 comparisons were made.

  First, an image forming apparatus having a plurality of modes will be described. Tables 1, 2, 3 and 4 are descriptions of the respective modes of the image forming apparatus (color printer 100) having a plurality of modes. Here, Table 1 shows three-level sounds created for the main sound sources (seven) extracted from sounds collected when the image forming apparatus having a plurality of modes operates at a color of 28 ppm, that is, at a printing speed of 28 ppm. The result of having created nine test sounds by allocating based on the L9 direct table is shown. By assigning to an orthogonal table in this way, there is no correlation between the factors (changes in the level of the sound source), so analysis can be performed ignoring changes in other factors.

  In Table 1 above (the same applies to the following tables), “−1” is a sound that is attenuated until it is almost inaudible, “0” is a sound at the level of the original sound, and “1” is the original sound. The sound is emphasized until the difference in level is clearly understood. For example, the test sound “color 28 ppm (9)” in Table 1 is “0” for all sound sources, indicating that all remain as the original sound.

  In Tables 1 to 8, subjective evaluation values (scores) of each test sound obtained by the Scheffe paired comparison method (Ura's modified method) are also shown. The total subjective evaluation values (total of nine sounds) in Tables 1 to 8 are set to 0 in each table.

  Next, Table 2 shows the three-level sounds created for the main sound sources (six) extracted from the sounds collected when operating at 14 ppm color, that is, at a printing speed of 14 ppm, based on the L9 orthogonal table. Results are shown. However, since the charging sound, the drum driving stepping motor sound, and the polygon mirror motor sound are sounds of the same tonality component, each test sound was set to the same level. The paper feed stepping motor sound is also a tonality component, but since this is an intermittently generated sound, it was decided to swing the level separately from the motor sound.

  Table 3 shows the result of allocating three levels of sounds created for the main sound sources (five) extracted from sounds collected when operating at 38 ppm monochrome, that is, at a printing speed of 38 ppm, based on the L9 orthogonal table. Indicates. However, since the charging sound and the drum driving stepping motor sound have the same tonality component, each test sound has the same level.

  Also, in this experiment, three levels of sound were obtained from the psychoacoustic parameters loudness value, sharpness value, tonality value and impulsiveness value obtained from the sound collected in the front when the above three modes were mixed. (Emphasis, original sound, attenuation) were created, and these sounds were assigned based on the L9 orthogonal table to create test sounds. The results are shown in Table 4.

  In addition, regarding the assignment of the loudness value, the emphasis was given for 38 ppm of monochrome, the intermediate one for 28 ppm, and the attenuated one for 14 ppm. That is, each level value of loudness was assigned according to the printing speed. The numerical values in parentheses in the table indicate each parameter value. In this experiment, since the effect of the printing speed (ppm), that is, the effect of the printing speed is also confirmed, the effect cannot be analyzed if the printing speed and the loudness value change in a completely proportional manner. Therefore, as shown in Table 4, even if the loudness value is the same level, a difference of about 1 (one) is given to make a difference in the level of hearing.

Similarly, similar operations were performed on image forming apparatuses at other speeds.
Table 5 shows the result of allocating the three levels of sounds created for the main sound sources (three) extracted from the sound collected when operating at monochrome 20 ppm based on the L9 orthogonal table.

  Table 6 shows the results of allocating three levels of sounds created for the main sound sources (four) extracted from the sound collected when operating at monochrome 27 ppm, based on the L9 orthogonal table.

  Table 7 shows the result of allocating three levels of sounds created for the main sound sources (six) extracted from the sound collected when operating at 65 ppm monochrome based on the L9 orthogonal table.

  Also, in this experiment, three values were obtained from the loudness value, sharpness value, tonality value, and impulsiveness value, which are psychoacoustic parameters obtained from the sound collected at the front when the three speeds of the monochrome machine were mixed. Sounds of levels (emphasis, original sound, attenuation) were created, and these sounds were assigned based on the L9 direct table to create test sounds. The results are shown in Table 8.

  Furthermore, six sounds related to an image forming apparatus having a plurality of modes (14 ppm for color, 28 ppm for color, and 38 ppm for monochrome) were compared with six sounds for an image forming apparatus having a single monochrome mode. The 12 sounds are shown in Table 9.

  The above is the details of the process of creating a test sound from the collected operating sound and creating an experiment.

(4) Measurement of psychoacoustic parameters of test sound Next, the psychoacoustic parameters of the test sound created as described above were obtained using the sound quality analysis software “ArtemiS” manufactured by Head Acoustics. In this sound quality analysis software, various settings can be selected when obtaining psychoacoustic parameters. In this experiment, default settings were adopted.

  For example, for loudness, “FFT / ISO0532”, “Filter / ISO0532” and “FFT / HEAD” can be selected as “Caluculation method”, but the default “FFT / ISO0532” is adopted, and “Spectrum Size” is the default. It was done with “4096”. For sharpness, the default “FFT / ISO532” was adopted for the “Caluculation method”, and the default “Aures” of “Aures” and “von Bismarck” was adopted for the “Sharpness method”. “Spectrum Size” was the default “4096”. Other psychoacoustic parameters correlate with loudness and automatically change depending on the loudness setting.

  Using the sound quality analysis software set as described above, the psychoacoustic parameter values of the test sound created in the process of (3) above were obtained. The results are shown in Table 10. In addition, the result of Table 10 is the result of rounding off the PPM value to the first decimal place, and the rest to the second decimal place.

(5) Pair comparison method experiment using test sound for each model or mode (Scheffe's pair comparison method Ura's variation)
Next, subjects who have the test sounds created as described above are evaluated, and the test sounds (1) to (9) (Table 9) created for each model or mode (Tables 1 to 9) are collected by the subjects. Only the test sounds (1) to (12)) were compared to determine which is uncomfortable.

  In the comparison experiment, all combinations of two test sounds are extracted from nine test sounds, and N subjects compare all of the combinations. That is, since there are nine test sounds in one mode, there are 72 combinations, and the subject is made to compare them. Therefore, the evaluation of the combination of the sample sound (1) and the sample sound (2) is different from the evaluation of the combination of the sample sound (2) and the sample sound (1). Combinations with different values are also subject to experimentation.

  In this comparison, for example, the test sound (1) is compared with the test sound (2), and if the subject evaluates the test sound (1) as uncomfortable, “1 point” If (2) is uncomfortable, the result is “−1”, and the results are aggregated and subjected to statistical processing. As a result, relative subjective evaluations are made in the range of −1 to 1 for the nine test sounds. Got the value. Such subjective evaluation values are also shown in Tables 1 to 4. Since the evaluation as described above is performed, it means that the larger the subjective evaluation value, the more unpleasant.

  For the combinations shown in Table 9, the scale of the experiment becomes large when a pairwise comparison of 12 sounds is performed. In this experiment, the sounds of the image forming apparatuses having a plurality of modes and the sounds of the image forming apparatuses of the monochrome single mode are compared. Was not carried out since it was conducted in another experiment (group I and group III, group II and group IV in the table below were not compared).

  That is, (1) Group I and Group II, (2) Group I and Group IV, (3) Group II and Group III, and (4) Group III and Group IV were compared. Considering the order of comparison, one subject made 72 comparisons at a time. Since it is not a brute force pair comparison, a relative score of 12 sounds cannot be calculated, but difference data of discomfort of 2 sounds can be obtained.

(6) Identification of unpleasant sound source Next, the unpleasant sound source is identified by six operating sounds of “color 28 ppm”, “color 14 ppm”, “monochrome 38 ppm”, “monochrome 20 ppm”, “monochrome 27 ppm”, and “monochrome 65 ppm”. It carried out for every experimental result implemented. 10 to 24 are graphs showing the relationship between the levels (emphasis, original sound, attenuation) of each sound source shown in Tables 1 to 3 and the subjective evaluation values.

  25 to 28 for Table 5, FIGS. 29 to 32 for Table 6, and FIGS. 33 to 38 for Table 7 for each sound source level (emphasis, original sound, attenuation), subjective evaluation values, The relationship is shown in a graph.

  In these graphs, the vertical axis represents the subjective evaluation value α, which means that the higher the value is, the more uncomfortable it is. The horizontal axis of the graph is the level of the sound source, that is, the sound pressure level level, “−1” attenuates the sound source, “0” remains the original sound, and “+1” emphasizes the sound source.

Further, “R ² ” in each figure is a contribution rate, and “R” is a correlation function. Here, the contribution rate indicates what percentage the sound source contributes to discomfort. The results shown in FIG. 10 indicate that the fixing oil application impact sound contributes 51% to discomfort. That is, if the correlation between the sound source level change and the subjective evaluation value (discomfort) change is high, the contribution rate increases. Note that the total contribution rate of each sound source in one mode is 100%, but there are some that are not exactly 100% due to rounding.

First, an unpleasant sound source of an image forming apparatus (color printer 100) having a plurality of modes is examined.
Referring to the contribution ratio of each sound source of “Color 28 ppm” shown in FIGS. 10 to 16, the color development driving sound system, the paper feeding stepping motor sound, the charging sound, and the polygon mirror motor sound hardly contribute to the unpleasantness. I understand that. However, according to later analysis, the three sound sources of the feeding stepping motor sound, charging sound, and polygon mirror motor sound are strongly related to the tonality (pure tone) component, which is actually unpleasant, but if the frequency of the pure tone is close, no measures are taken at the same time And found that discomfort is not improved.

  Therefore, in other modes, these sound sources are set to the same level for each sample sound (see the process (3) and Tables 2 and 3). For this reason, only the color development driving sound among the sound sources hardly contributes to discomfort, so it is considered that there is no need for noise countermeasures. However, there are cases where improvement is necessary in the evaluation based on the sound power level.

  On the other hand, the fixing oil application impact sound contributes most to the unpleasantness of “color 28 ppm”, and the paper sliding sound contributes next.

  According to the unpleasant sound source analysis results of “color 14 ppm” shown in FIGS. 17 to 20, fixing oil application impact sound 43%, paper sliding sound 35%, paper feed stepping motor sound 17%, charging sound, polygon mirror motor sound The total of the three sound sources of the drum drive motor sound was 3%.

  According to the unpleasant sound source analysis results of “monochrome 38 ppm” shown in FIGS. 21 to 24, the fixing oil application impact sound is 43%, the paper sliding sound is 35%, the sum of the charging sound and the drum drive motor sound is 10%, and the development drive The sound system was 3%.

  From the above analysis results, in an image forming apparatus having a plurality of modes, sound sources other than the sound of the development drive system contribute to discomfort, and discomfort can be reduced by taking noise countermeasures for these sound sources. I understand.

Next, an unpleasant sound source of the desktop (desktop) image forming apparatus (monochrome printer 200) is examined.
Since there are few conspicuous sound sources for this device, one of the factors that change the level was substituted with loudness. Referring to the contribution ratio of each sound source of “monochrome 20 ppm” shown in FIG. 25 to FIG. 28, the influence of loudness is large, and the discomfort of each sound source cannot be accurately understood. It has been found that reducing the overall volume of hearing leads to a reduction in discomfort.

Next, an unpleasant sound source of the medium-speed image forming apparatus (in-body discharge type copying machine 300) is examined.
Referring to the contribution ratio of each sound source of “monochrome 27 ppm” shown in FIGS. 29 to 32, the paper feed sound was 9%, the paper sliding sound was 61%, the metal impact sound was 13%, and the motor drive system sound was 1%. . In the medium-speed image forming apparatus, the paper sliding sound and the metal impact sound contribute to the uncomfortableness, and it can be understood that the discomfort can be reduced by taking noise countermeasures for these sound sources.

Next, an unpleasant sound source of the large-sized (console type) image forming apparatus (the copying machine with ADF 400) is examined.
Referring to the contribution ratio of each sound source of “monochrome 65 ppm” shown in FIGS. 33 to 38, metal impact sound 29%, paper sliding sound 42%, paper impact sound 0%, bank motor sound 3%, development motor sound 10%, main motor sound 1%. In a large-sized (console type) image forming apparatus, metal impact sound and paper sliding sound contribute to discomfort, and it can be seen that discomfort can be reduced by taking noise countermeasures for these sound sources.

(7) Creation of analysis data of difference model Next, the difference between the subjective evaluation values (scores) of two sounds was calculated using the experimental results obtained by the paired comparison method experiment in the process of (5) above. The method for creating the difference data is as follows.

  When there are 36 subjects in a paired comparison experiment, the test sound (1) and the test sound (2) are compared, and if the test sound (1) is uncomfortable, “1 point” The case where the sound (2) is uncomfortable is calculated as “−1 point”. In this case, assuming that there are 30 people who are uncomfortable with the test sound (1) and 6 people who are uncomfortable with the test sound (2), the total score is 30−6 = 24. A value obtained by dividing this value by the number of subjects “36” is the difference “0.667” in the subjective evaluation value (score). In this way, the difference in subjective evaluation value (score) is calculated for each combination. On the other hand, the value of the difference between the acoustic physical quantities of the test sound (1) and the test sound (2) is calculated. In this way, the difference between the subjective evaluation value (score) and the difference between the acoustic physical quantities is calculated for each combination.

(8) Principal component analysis Furthermore, a principal component analysis is performed about the difference of an acoustic physical quantity.
The principal component analysis can be performed by using various commercially available spreadsheet software and statistical analysis software. For example, statistical analysis software “JMP (registered trademark of SAS Institute Inc)” or “SPSS (registered trademark of SPSS Inc)” can be used. In the present invention, JMP was used.

  First, the relationship between the difference data of five acoustic physical quantities (sound pressure level, loudness, sharpness, tonality, impulsiveness) was examined by JMP using a scatter diagram and a correlation coefficient matrix. 39 shows a correlation diagram matrix, and Table 11 shows a correlation coefficient matrix. There is a strong positive correlation between sound pressure level and loudness, and a weak negative correlation between loudness and impulsiveness, and tonality and impulsiveness. Other relationships are close to uncorrelated. Also, the plot does not seem to have a large outlier.

Here, principal component analysis was performed. Table 12 shows the results.

From Table 12, the main component is interpreted.
The eigenvalue of the first principal component is about 1.9, which is the largest. The contribution rate is also about 38%. The sound pressure level and the loudness eigenvector are large, which is considered to represent the volume.
The eigenvalue of the second principal component is about 1.3. The contribution rate is about 27%. From the sign of the eigenvector, it can be considered as an opposite concept of tonality and impulsiveness. Tonality is pure tone content and impulsiveness is impact.
The eigenvalue of the third principal component is about 1.0. The contribution rate is about 20%. It can be considered as a component of sharpness (high frequency sound) from the size of the eigenvector.
The eigenvalue of the fourth principal component is about 0.7. The contribution rate is about 13%. Since the eigenvalue is 1 or less, there is a high possibility of a residual, but if it is intentionally analyzed, it can be considered as a component of tonality and impulsiveness from the size of the eigenvector.
Since the fifth principal component has an eigenvalue of less than 0.1 and a contribution rate of only 1.5%, it is treated as a residual.

(9) Factor analysis When interpreting principal component analysis, it is difficult to put a smart catchphrase on conflicting concepts. The main component is rotated using a method called varimax rotation. The new component obtained by the rotation is called a factor, and the individual ability-variate classification is derived to simplify the structure. In other words, it is possible to eliminate the concept of conflict by rotating the principal component, and the interpretation of the factors becomes easy. Such a method is called factor analysis.

Here, factor analysis is performed based on principal component analysis. For the time being, factor analysis was performed by setting up to 4 main components to be rotated. As a result, the results of Table 13 to Table 17 were obtained.
Table 13 shows variance, contribution ratio, and cumulative contribution ratio Table 14 shows twiddle factor patterns.
Table 15 shows the rotation matrix.
Table 16 shows commonality.
Table 17 shows standard score coefficients.

  From the variance, contribution rate, and cumulative contribution rate in Table 13, the variances (= eigenvalues) of each factor all exceed 1. That is, the rotation of the principal component means that the variance of all four factors exceeded 1, and all became effective components. Further, when the cumulative contribution rate up to the fourth component in Table 12 of the main component and the cumulative contribution rate up to the fourth factor in Table 13 are compared, they agree. This means that the amount of information does not change with rotation.

Table 14 shows twiddle factor patterns.
A correlation coefficient (factor loading) between the first factor, the second factor, the third factor, the fourth factor, and the original variable (acoustic physical quantity) is shown.

  The sound pressure level and loudness of the original variable have a large correlation with the first factor and a small correlation with other factors. In addition, impulsiveness has a high correlation with the second factor and a small correlation with other factors. Sharpness has a large correlation with the third factor and a small correlation with other factors. Tonality has a large correlation with the fourth factor and a small correlation with other factors.

  It can be seen that due to the varimax rotation, the components are converted in such a direction that several factor loadings each factor is close to zero and some factor loadings whose absolute values are close to 1 are likely to exist.

  If the absolute value of the variable and the factor loading of the factor is close to 1, it can be interpreted that there is a clear relationship, and if it is close to 0, it can be treated as irrelevant. Therefore, the first factor is considered as a factor representing the sound pressure level and loudness such as loudness. It is considered that the second factor represents the impact of sound, the third factor represents the content of the high frequency component of the sound, and the fourth factor represents the content of the pure sound component. Since the cumulative contribution rate exceeds 98%, it can be said that MFPs (multifunction devices), printers, etc. can be expressed by these factors.

  Next, the factor and the principal component are compared. The values of the rotation matrix in Table 15 represent the correlation between the first factor to the fourth factor and the first principal component to the fourth principal component, and the first principal component and the second principal component centering on the origin. , The rotation amount from the third principal component and the fourth principal component. It can be seen that the rotation is 162.9 degrees (from cos θ = −0.95581) by the varimax rotation.

Table 16 shows commonality and is a ratio that can explain the original variable by the first factor to the fourth factor. All five variables have an explanatory power of 96% or more.

Table 17 shows standard score coefficients, which are coefficients for obtaining factor scores, and are standardized so that the variance is 1. These values are values that should be multiplied by the original variable, and mean that the variance of the factor scores thus obtained is 1 and the average is 0.
Factor score = Σ (standard score coefficient * (variable-average) / standard deviation of variables

Table 18 below shows the coefficients and intercepts for calculating these factors from the original variables by JMP.

(10) Deriving a difference model formula that predicts “difference in subjective evaluation value between two sounds” by “factor” Statistical analysis software JMP calculates factors, and based on this, predicts discomfort . That is, “difference in subjective evaluation value between two sounds” is set as an objective variable, and the first factor, second factor, third factor, and fourth factor are set as explanatory variables, and multiple regression analysis is performed.

  Table 19 shows a part of the difference between the scores calculated as described above, the difference between the acoustic physical quantities, and the factor analysis result (analysis data of the difference model). Table 19 shows a part of the results for the test sound of “Color 28 ppm (1) to (9)”.

Using the data of 623 for which a pair comparison was made, a multiple regression analysis was performed using the difference in subjective evaluation values between two sounds as an objective variable and factors as explanatory variable groups.
Data that was judged as unpleasant by one person at the time of pair comparison was excluded from the analysis because the human sense was scaled over. In addition, since this is a model of difference in scores, the multiple regression analysis was performed with the intercept set to zero. The analysis of variance table is as follows.

here,
Contribution rate = sum of squares by regression / total sum of squares = 181.8 / 235.4 = 0.722
Therefore, it was found that the sum of the four factors contributed 77.2% to the discomfort in the difference model formula. Table 21 shows partial regression coefficients (regression coefficients at the time of multiple regression analysis) of the four factors selected as variables. Since the difference data was analyzed, the intercept was fixed at 0.

  In addition, an upper limit value and a lower limit value at which the partial regression coefficient has a reliability of 95% are shown. The upper limit value and the lower limit value are obtained by adding a value (2σ) about twice the standard error corresponding to the estimated value of the regression coefficient. When the difference model is expressed as an equation, the following equation (A) is obtained.

[Formula (A)]
αi-αj = -0.462623 x first factor + 0.1649484 x second factor
-0.217222 × Third factor + 0.0623665 × Fourth factor αn (n = 1, 2,..., I,..., J,..., N): Subjective table value for sound discomfort (score)
First factor = −0.137615532 × (sound pressure level i−sound pressure level j)
-0.250138895 x (Loudness i-Loudness j)
+ 0.0482463 × (Sharpness i−Sharpness j)
-0.198127191 x (Tourity i-Tonality j)
-0.336676968 × (Impulsiveness i-Impulsiveness j)
+0.006868023
Second factor = + 0.055367659 × (sound pressure level i−sound pressure level j)
-0.076387277 × (Loudness i-Loudness j)
+ 0.093894443 × (Sharpness i−Sharpness j)
+2.82214291 x (Tourity i-Tonality j)
+ 5.016501215 × (impulsiveness i-impulsiveness j)
-0.005558113
Third factor = + 0.018654275 × (sound pressure level i−sound pressure level j)
-0.022574832 × (Loudness i-Loudness j)
-1.808975756 × (Sharpness i−Sharpness j)
-1.201786255 x (Tourity i-Tonality j)
-0.226269754 × (Impulsiveness i-Impulsiveness j)
+0.017818196
Fourth factor = + 0.026081471 × (sound pressure level i−sound pressure level j)
-0.048289133 × (Loudness i-Loudness j)
+ 0.140321797 × (Sharpness i−Sharpness j)
+ 17.9461075 × (Tourity i-Tonality j)
+ 0.756312336 × (impulsiveness i-impulsiveness j)
-0.004379473

  From the above, a line format that can calculate the difference in discomfort was derived by substituting the acoustic physical quantities of the two sounds.

FIG. 40 shows a scatter diagram of the actually measured values of the difference of the scores and the predicted values based on the formula (A).
The difference between the scores is that, if the result of the pair comparison shows that all of them are uncomfortable, the maximum is -1 or 1, so only a range of -1 to 1 can be obtained, but the predicted value is about -2 to 2 It can be seen that it is slightly expanded.

(11) Derivation of relative model formula (sound quality evaluation formula) that predicts the discomfort of a single sound The difference model is inconvenient because it can only be used when two sounds are compared. The aim is to evaluate a single sound. Therefore, consider the change from the difference model to the relative model.

In Formula (A), for each acoustic physical quantity value, the formula is converted by defining the discomfort of the sound at the average value of the test sound used in the experiment as α ₀ = 0.
That is, the effect α ₀ of the coordinates of the center of gravity is set to 0, and the average value of the sound pressure level, loudness, sharpness, tonality, and impulsiveness at that time is substituted. The average value uses the calculation result of Table 10.

αi−α0 = −0.462623 × first factor + 0.1649484 × second factor−0.217222 × third factor + 0.0623665 × fourth factor αn (n = 1, 2,..., j,. , n): Subjective table value for sound discomfort (score)

That means
αi = -0.462623 x first factor + 0.1649484 x second factor -0.217222 x third factor + 0.0623665 x fourth factor

If αi is defined as the predicted sound quality evaluation value S to make it easier to use, the following equation (c) is obtained.
[Formula (c)]
S = −0.462623 × first factor + 0.1649484 × second factor−0.217222 × third factor + 0.0623665 × fourth factor first factor = −0.137615532 × (sound pressure level i−sound pressure level average value)
-0.250138895 x (Loudness i-Loudness average value)
+0.0482463 x (Sharpness i-Sharpness average value)
-0.198127191 x (Tourity i-Tonality average)
-0.336676968 x (impulsiveness i-impulsiveness average value)
+0.006868023
Second factor = + 0.055367659 × (sound pressure level i−sound pressure level average value)
-0.076387277 x (loudness i-average loudness)
+0.093894443 x (Sharpness i-Sharpness average value)
+2.82214291 x (Tourity i-Tonality average)
+5.016501215 x (impulsiveness i-impulsiveness average value)
-0.005558113
Third factor = +0.018654275 x (sound pressure level i-sound pressure level average value)
-0.022574832 x (loudness i-average loudness)
-1.808975756 × (Sharpness i−Sharpness average value)
-1.201786255 x (Tonality i-Average Tonality)
-0.226269754 x (impulsiveness i-impulsiveness average value)
+0.017818196
Fourth factor = + 0.026081471 × (sound pressure level i−sound pressure level average value)
-0.048289133 × (Loudness i-Loudness j)
+ 0.140321797 × (Sharpness i−Sharpness average value)
+ 17.9461075 × (Tourity i-Tonality j)
+0.756312336 x (impulsiveness i-impulsiveness average value)
-0.004379473

  By converting the equation in this way, it is possible to calculate the score of the sound when compared with the sound of the average value. This is called a relative model formula.

The regression coefficient takes a 95% confidence interval as shown in Table 21.
This is used in the following equation (a).

[Formula (a)]
S = A × (first factor) + B × (second factor) + C × (third factor) + D × (fourth factor)
Range of coefficient for each parameter
-0.485785 ≤ A ≤ -0.439461

0.141786 ≦ B ≦ 0.1881104
-0.240384 ≤ C ≤ -0.19406
0.0392045 ≦ D ≦ 0.0855286
First factor = -0.137615532 x (sound pressure level-sound pressure level average value)
-0.250138895 x (loudness-average loudness)
+0.0482463 x (Sharpness-Sharpness average value)
-0.198127191 x (Tourity-Tonality average value)
-0.336676968 x (impulsiveness-impulsiveness average value)
+0.006868023
Second factor = + 0.055367659 × (sound pressure level−sound pressure level average value)
-0.076387277 x (loudness-average loudness)
+0.093894443 x (Sharpness-Sharpness average value)
+2.82214291 x (Tourity-Tonality average value)
+5.016501215 x (impulsiveness-impulsiveness average value)
-0.005558113
Third factor = +0.018654275 x (sound pressure level-sound pressure level average value)
-0.022574832 x (loudness-average loudness)
-1.808975756 × (Sharpness−Sharpness average value)
-1.201786255 × (Tourity-Tonality average value)
-0.226269754 x (impulsiveness-average impulsiveness)
+0.017818196
Fourth factor = +0.026081471 x (sound pressure level-sound pressure level average value)
-0.048289133 x (Loudness-Loudness j)
+ 0.140321797 × (Sharpness−Sharpness average value)
+ 17.9461075 × (Tourity-Tonality j)
+0.756312336 x (impulsiveness-impulsiveness average value)
-0.004379473

(12) Verification of derived sound quality evaluation formula Next, the prediction accuracy of the prediction formula (sound quality evaluation formula) of the predicted sound quality evaluation value S derived as described above was verified.

  This verification was performed by comparing the measured value of the subjective evaluation value (score) with the predicted sound quality evaluation value S derived using the sound quality evaluation formula (c). The actual measurement values of the subjective evaluation values (scores) are the above eight experiments ("Color 28ppm", "Color 14ppm", "Monochrome 38ppm", "Mode Mix", "Monochrome 20ppm", "Monochrome 27ppm", "Monochrome 65ppm" , “Monochrome Mix”), the actual value of the subjective evaluation value (score) is obtained, and the predicted sound quality evaluation value S corresponding to these is derived using the sound quality evaluation formula.

The actual value of the subjective evaluation value (score) was the result of Scheffe's paired comparison method obtained for each of the eight experiments.
However, this measured value is the result of performing a brute force paired comparison experiment for nine test sounds for each of eight experiments, and the sum of the measured values of subjective evaluation values (scores) in each experiment. This is a result obtained when a relative comparison is made among the nine sounds in each experiment.

  Therefore, in the predicted value, using the formula (c), for example, when predicting the sound quality evaluation value of the color 28 ppm (1), “acoustic physical quantity of the color 28 ppm (1)” and “in the population” Instead of using the “average value of acoustic physical quantities in color”, “the acoustic physical quantity of color 28 ppm (1)” and “the average value of acoustic physical quantities of color 28 ppm (1) to (9) (the average value of acoustic physical quantities in the experiment). The predicted sound quality evaluation value S is calculated using the value of the difference from “)”.

  This kind of adjustment is done because we want to compare the actual measurement results of the paired comparison method with the prediction results of the sound quality evaluation formula. An average value of physical quantities may be used.

  According to the above procedure, an actual measurement value of sound quality evaluation is obtained for each test sound of each of the eight experiments, and the sound physical quantity (psychoacoustic parameter) and the average value of the sound physical quantity for each experiment are calculated using the above sound quality evaluation formula. A predicted value is obtained by substituting for (c). In this manner, the actual evaluation value and the predicted evaluation value for each sample sound in each mode can be obtained, and the results are shown in Table 22.

  41 to 48 show eight experiments (“monochrome 20 ppm”, “monochrome 27 ppm”, “monochrome 65 ppm”, “monochrome Mix”, “color 28 ppm”, “color 14 ppm”, “monochrome 38 ppm”, “mode mix”). It is the graph which carried out the comparison plot of the value (horizontal axis) estimated using the said Formula (c) for every every, and an actual measurement value (vertical axis).

  In the scatter diagram of the difference model, the accuracy in the vicinity of 1 and −1 was deteriorated, but it was improved when the sound quality of the sound alone was predicted using the relative model. This is considered to be because the number of points N = 623 (623 pairs of comparison results) in the difference model is averaged to the number of points N = 72 (72 sounds) in the relative model, thereby reducing variation. As shown in these figures, the contribution ratios in all experiments exceeded 90%, and the prediction accuracy of discomfort is high.

FIG. 49 summarizes all these results.
Table 9 shows a comparison of 6 sounds related to an image forming apparatus having a plurality of modes (color 14 ppm, color 28 ppm, monochrome 38 ppm) and 6 sounds related to an image forming apparatus having a monochrome single mode. Since it is not a comparison of hit combinations, the relative discomfort index of 12 sounds cannot be calculated. For this reason, it was not possible to plot on the graph.

  As shown in FIG. 49, the overall slope of this graph is 0.9, and the overall contribution rate is 92%. Therefore, in any of the eight experiments, it is considered that the accuracy of the predicted value of the score derived by the above equation (a) is high.

  Now, it is considered that the accuracy of the predicted value (evaluation) obtained by the equation (a) derived as described above is high, but when the discomfort index S, which is the evaluation obtained in this way, becomes a value, the person is uncomfortable. It is important to stop feeling.

  Therefore, the following experiment was conducted to confirm this. For the test sound of color 14 ppm, color 28 ppm, monochrome 38 ppm, monochrome 65 ppm, the subject randomly listened to all the test sounds (1) to (9) for each speed experiment, and then made one sound again. An experiment was conducted in which each of the test sounds was evaluated for three levels of discomfort.

  Note that the monochrome 65ppm test sound was larger between the test sound (1) and the test sound (5) than the interval between the other sounds, so between the test sounds (1) and (5) Pre-established test sounds (10) and (11) prepared in advance were prepared.

  As a result, the results shown in Table 23 to Table 26 were obtained. Table 27 shows the physical quantities of the test sounds (10) and (11).

  In the table, evaluation “A” is an acceptable sound, evaluation “C” is an unacceptable sound, and evaluation “B” is an intermediate sound. Of the sound quality evaluation values of the sound evaluated as “A” (value calculated by the formula (A)), assuming that the largest value is an allowable value, ppm of each experiment and image formation speed (mm / s) The allowable values for each are as shown in Table 28.

FIG. 50 is a graph in which the relationship between the ppm value and the allowable value is approximated based on the results shown in Table 28. The approximate expression is
S ≦ 0.4646Ln (ppm)-1.8426 ・ ・ ・ ・ ・ ・ （b）
14 ≦ ppm ≦ 65
It is.

FIG. 51 is a graph in which the relationship between the image forming speed v (mm / s) and the allowable value is approximated based on the results shown in Table 28. The approximate expression is
S ≤ 0.4101Ln (v)-2.2997 (d)
62.5 ≦ v ≦ 362
It is.

  As shown in FIGS. 50 and 51, the sound quality evaluation value calculated from the sound emitted when operating at each speed (ppm or image forming speed mm / s) is less than the allowable value (the area below the line of the graph). If it is, it will be almost uncomfortable.

  As described above, by using the above formula (c) or formula (a), it is uncomfortable just to acquire a psychoacoustic parameter value that can be acquired from a physical quantity of sound without actually performing a subjective evaluation experiment. The sound quality evaluation value S, which is an evaluation of Even in an apparatus having a plurality of operation modes having different image forming speeds (mm / s and ppm) or an image forming apparatus having different image forming speeds according to the conditions (b) and (d) described above, It is possible to determine what kind of value the sound quality evaluation value S obtained for each item does not cause discomfort.

  The above is the method for evaluating the quality of sound emitted by the image forming apparatus and the method for deriving the sound quality evaluation formula used for the sound quality evaluation.

[II. Application of Invention]
The present invention can provide an image forming apparatus in which the sound quality evaluation formula derived as described above is used to evaluate the sound quality of the image forming apparatus and the evaluation result (sound quality evaluation value S) satisfies a predetermined condition. It is to make. Therefore, as shown in FIG. 52, the present invention can be applied when developing and manufacturing a new product.

  Specifically, as shown in the flowchart of FIG. 52, what configuration is adopted for each part of the image forming apparatus so that the sound quality evaluation (sound quality evaluation value S) based on the sound quality evaluation formula satisfies a predetermined condition. Is designed (S1: design process). Then, the image forming apparatus is manufactured according to the design contents in which the sound quality evaluation value S obtained from the sound emitted from the image forming apparatus satisfies a predetermined condition (S2: manufacturing process). Through such a manufacturing process, an image forming apparatus that hardly generates unpleasant noise can be manufactured, and such an image forming apparatus can be provided to the user.

[III. Configuration of image forming apparatus]
Next, four examples of the image forming apparatus used for the sound quality evaluation will be described.
FIG. 53 is a cross-sectional configuration diagram illustrating an outline of a tandem color printer which is an example of an image forming apparatus having a plurality of modes. A color printer 100 shown in this figure includes a writing optical unit 1, a photosensitive unit 3, a developing unit 4, a transfer unit 5, a fixing unit 46, and a paper feeding unit 11.

  At the time of image formation, an image formation target sheet (including printing paper, OHP sheet, etc., but hereinafter referred to as paper) housed in a paper feeding unit 11 disposed at the bottom of the image forming apparatus is shown from the lower right side of the figure. It is transported along a predetermined transport path that rises diagonally to the left. The sheet thus transported is fed from the sheet feeding unit 11 and is conveyed to the upper side of the sheet feeding unit 11 along an oblique conveyance path from the lower right to the upper left in the drawing. During this time, the sheet is similarly passed between the four photosensitive units 3, the developing unit 4 and the transfer unit 5 arranged side by side along the conveyance path, and a predetermined image is transferred. The sheet on which the image has been transferred is conveyed to a fixing unit 46 that is disposed further obliquely to the left of the photosensitive unit 3, the developing unit 4, and the transfer unit 5, and the transferred image is fixed by the fixing unit 46.

  As shown in FIG. 54, the optical unit 1 is a unit that extends along a sheet conveyance path that is an oblique direction such as the lower right to the upper left direction of FIG. 54, and includes a housing 12 arranged along that direction. Have. Laser diodes (LD) 17 (Bk: black), 18 (C: cyan), 19 (M: magenta), and 20 (Y: yellow) for each of four colors are attached to the upper portion of the housing 12.

  The housing 12 also includes a polygon mirror motor 2 for main operation line operation, two-layer fθ lenses 21 and 22 for dot position correction, and long WTL lenses 23, 24, 25 for surface tilt correction. 26, a cylinder lens or the like for correcting a laser beam diameter (not shown) is attached.

  The polygon mirror motor 2 is integrally formed with two upper and lower six-sided mirrors 27, and the polygon mirror 27 is irradiated with laser light emitted from the LDs 17, 18, 19, and 20.

  The LDs 17, 18, 19, and 20 corresponding to the respective colors emit light in accordance with the conveyance timing of the paper, and the light (indicated by a thick line in the figure) is a cylinder lens, a polygon mirror 27, two-layer fθ lenses 21 and 22, a long length. The photosensitive drum 28 of each color is irradiated via the WTL lenses 23, 24, 25, and 26.

  As the LD unit 17 corresponding to black, it is preferable to adopt a two-beam type. That is, by adopting a two-beam LD, two beams can be written simultaneously when forming a monochrome image, and rapid writing can be performed while suppressing the number of rotations of the polygon mirror motor 2. By reducing the rotation speed of the polygon mirror motor 2 in this way, it is possible to obtain an effect of suppressing noise and an effect of extending the life of the motor. For example, when printing in the color mode, the rotation speed of the polygon mirror 27 is 29528 rpm (revolutions per minute) and the printing speed is 28 ppm (pages per minute), but the rotation speed of the polygon mirror 27 is 21850 rpm and the rotation speed is monochrome printing. Despite being small, the printing speed is 38 ppm.

  Returning to FIG. 53, the configuration of the photosensitive unit 3, the developing unit 4, and the transfer unit 5 in the image forming apparatus will be described. As shown in the figure, this image forming apparatus employs a four-drum tandem image forming method, and this method improves the printing speed in the full-color printing mode and the monochrome printing mode. . Further, as described above, the photoconductor unit 3, the developing unit 4, and the transfer unit 5 are disposed obliquely, thereby reducing the installation space, thereby reducing the size of the entire apparatus.

  The photosensitive unit 3 and the developing unit 4 are independent units for each color. That is, the photosensitive unit 3 and developing unit 4 for magenta (M), the photosensitive unit 3 and developing unit 4 for cyan (C), the photosensitive unit 3 and developing unit 4 for yellow (Y), and black (Bk). ) Photosensitive unit 3 and developing unit 4, which are arranged in the above order from the lower right side to the upper left side of FIG. The M, C, and Y photoconductor units 3 except for Bk have exactly the same structure, so that any new unit (M, C, Y) may be used. Good.

  The transfer unit 5 is a unit extending along the oblique direction below the photosensitive unit 3 and the developing unit 4 arranged in the oblique direction in the above-described order, and is disposed along the oblique direction. Yes. The transfer unit 5 includes a plurality of rollers and an endless transfer belt 29 wound around the rollers. When the roller is rotated by a motor (not shown), the transfer belt 29 is rotated counterclockwise in the drawing, and the sheet fed from the paper feeding unit 110 is placed on the transfer belt 29 and is moved from the lower right side to the upper left side of the drawing. To the side. Further, a P sensor 6 is disposed on the downstream side in the transport direction of the transfer unit 5 (upper left in the drawing), and the P sensor 6 detects the density of the P sensor pattern formed on the transfer belt 29. The detection result is used for control.

  Here, FIG. 55 shows a cross-sectional view of the photosensitive unit 3 and the developing unit 4 corresponding to a certain color. As shown in the figure, the photosensitive unit 3 has a photosensitive drum 28 (for example, φ30). The photosensitive drum 28 has a hollow cylindrical shape and can be rotated clockwise in the drawing by a driving mechanism described later.

  A charging roller 36 (for example, φ11) is disposed above the photosensitive drum 28. The surface of the charging roller 36 is disposed at a position separated from the surface of the photosensitive drum 28 by about 0.05 mm. The charging roller 36 is rotated in the opposite direction to the photosensitive drum 28, that is, counterclockwise in the drawing, and applies a uniform charge on the surface of the photosensitive drum 28.

  A cleaning brush 37 is disposed above the charging roller 36. A cleaning brush 39 and a counter blade 38 are disposed on the upper left side of the photosensitive drum 28, and the photosensitive drum 28 is cleaned by these.

  A waste toner collecting coil 40 is disposed on the left side of the cleaning brush 39, and the waste toner collected by the waste toner collecting coil 40 is conveyed to the waste toner bolt 16 shown in FIG. ing.

  The developing unit 4 employs a dry two-component magnetic brush developing system, and includes a developing roller 30, a developing doctor 31, a conveying screw left 32, a conveying screw right 33, a toner concentration sensor 34, and an agent cartridge 35. With.

  Next, the drive mechanism of the photoreceptor unit 3 will be described with reference to FIG. The photoconductor unit 3 is provided for each color, and there are four units. Three photoconductor units 3 for M, C, and Y (for color), and a photoconductor unit 3 for Bk Are driven by separate drive mechanisms. That is, the color photoconductor unit 3 is driven by the color drum drive motor 41 as a drive source and the gears 43 and 44 and the joint 45 that transmit this drive force.

  On the other hand, the black photoconductor unit 3 is driven by another gear 44 and a joint 45 which use another black drum drive motor 42 as a drive source and transmit this drive force. Accordingly, during color mode printing, only the color drum drive motor 41 operates and the black drum drive motor 42 stops. On the other hand, during monochrome mode printing, only the black drum drive motor 42 operates and the color drum drive motor 41 stops. The color drum drive motor 41 and the black drum drive motor 42 are stepping motors.

  As shown in FIGS. 57 and 58, the fixing unit 46 employs a belt fixing method, and the belt has a smaller heat capacity than the fixing roller. There are advantages over the method used, such as shortening the warm-up time and lowering the roller set temperature during standby.

  The fixing unit 46 heats and pressurizes the sheet on which the image has been transferred, and fixes the toner image on the sheet. The fixing unit 46 includes a fixing belt 13 and an oil application unit 47. In the oil application unit 47, the gel oozes out from the oil and is supplied from the application felt 48 to the application roller 49. A small amount of silicone oil is applied to the fixing belt 13 while the application roller 49 rotates. By thus applying oil to the fixing belt 13, the fixing belt 13 and the paper are easily peeled off. The application operation by the oil application unit 47 is performed every time one sheet is conveyed, and oil application is performed each time one sheet is conveyed by a mechanism having a solenoid and a spring (not shown). The unit 47 is driven and brought into contact with the fixing belt 13. On the other hand, when one sheet of paper passes, the oil application unit 47 is separated from the fixing belt 13 by the above mechanism.

  As shown in FIG. 57, a cleaning roller 50 is provided on the upstream side of the fixing belt 13 in the sheet conveying direction, and the cleaning roller 50 adsorbs dirt on the fixing belt 13, thereby performing belt cleaning. Made.

  The above is the configuration of the fixing unit 46, and the sheet that has passed through the fixing unit 46 is conveyed to the main body tray 15 shown in FIG.

  Next, the configuration of the paper feeding unit 11 will be described with reference to FIG. The sheet feeding unit 11 has three trays, a first tray 9, a second tray 10, and a manual sheet feeding tray 8. Each of these trays employs an FRR paper feeding system as a system for feeding out the paper stored in the tray. The feed mechanism using the FRR paper feed system is reversely rotated with respect to the paper feed roller that is driven to rotate in the paper feed direction in order to separate the paper fed from the paper bundle stacked in the paper feed tray one by one. It has a configuration in which a roller is in contact.

  Under this configuration, the reverse roller is applied with a weak torque in the opposite direction to the paper feed roller via the torque limiter, so that the reverse roller is in contact with the paper feed roller, or one sheet of paper is In the state of entering between the rollers, the sheet rotates with the sheet feeding roller, while in the state of being separated from the sheet feeding roller, or in the state in which two or more sheets enter between the rollers, it rotates in the reverse direction. For this reason, when the multi-feed paper enters, the paper in contact with the reversing roller is returned to the downstream side in the paper feeding direction, and multi-feed is prevented.

  The sheets stored in the first tray 9 are separated by the first sheet feeding unit 51 and sent out from the first tray 9. Then, the fed sheet is transported by the relay roller 53 and reaches the transport roller 55. Here, the sheet is conveyed toward the upper left registration roller 7 while being turned by the conveyance roller 55.

  The conveyed sheet hits the resist roller 7 that is stopped, and thereby the skew of the sheet is corrected. Then, timing adjustment with the image forming process by the photoconductor unit 3 or the like is performed, a registration clutch (not shown) is connected at a predetermined timing, the registration roller 7 is driven, and the sheet is conveyed toward the transfer unit. Thereafter, the sheet is conveyed by the transfer belt 29 as described above, and is subjected to processing such as predetermined image transfer.

  The paper stored in the second tray 10 is sent out by the second paper feed unit 52 and the relay roller 54 toward the transport roller 55, and thereafter the same as the paper stored in the first tray 9. It is. The paper set on the manual feed tray 8 is transported toward the registration roller 7 by the paper supply unit 56, and the subsequent processing is the same as the paper transport from the first tray 9.

  Next, a configuration for driving the first paper feeding unit 51 and the second paper feeding unit that feeds paper from the first tray 9 and the second tray 10 as described above will be described. As shown in FIG. 60, both these units are driven by a single stepping motor 56, and driving force is transmitted to each unit via a first paper feed clutch 57 and a second paper feed clutch 58. Is called. That is, when the paper is sent out from the first tray 9, only the first paper feed clutch 57 is connected, and when the paper is sent out from the second tray 10, only the second paper feed clutch 58 is connected. As described above, this image forming apparatus has the color photoconductor unit 3 and the like, and can perform color printing as well as monochrome printing. More specifically, as shown in Table 29, there are four printing modes such as “monochrome mode”, “color mode (1)”, “color mode (2)”, and “OHP / thick paper mode”. When the user selects a mode by operating the operation unit or the like, a control unit (operation control unit) of the image forming apparatus (not shown) controls each unit according to the selection and operates each unit in the operation mode. . In this image forming apparatus, three types of image forming speeds (182.5 mm / s = 38 ppm (pages per minute), 125.0 mm / s = 28 ppm, 62.5 mm / s = depending on the mode selected by the user by the control unit). 14 ppm). In other words, the rotational speeds of the motors such as the stepping motor 56, the black drum driving motor 42, and the color drum driving motor 41 are controlled to change according to the selected operation mode.

  Here, in the high-resolution “color mode (2)” and “OHP / thick paper mode”, the printing speed (image forming speed) is 14 ppm, whereas in the “monochrome mode”, the printing speed is 38 ppm. There is a speed difference close to twice. In order to realize such a large speed difference with a single motor, this image forming apparatus employs a stepping motor as a drive source for a paper transport mechanism system and the like.

  FIG. 61 is a cross-sectional configuration diagram illustrating an outline of a monochrome printer 200 which is an example of a desktop (desktop) image forming apparatus. The image forming apparatus of this example is a digital printer that employs an electrophotographic system, and operates in a single mode (monochrome print only).

  In FIG. 61, reference numeral 201 denotes a photosensitive drum on which an electrostatic latent image and a toner image are formed, reference numeral 202 denotes a transfer roller for transferring the toner image formed on the photosensitive drum 201 to a recording sheet, and reference numeral 203 denotes A process cartridge for forming a toner image on the photosensitive drum 201, a reference numeral 204 is a main body paper feed tray for feeding out recording paper one by one, and a reference numeral 205 is a bank for feeding out the recording paper one by one in the same manner as the main body paper feeding tray 204. Reference numeral 206 is a manual feed tray for feeding paper by inserting one sheet of recording paper, reference numeral 207 is a fixing unit for fixing the toner image transferred to the recording paper by the action of heat and pressure, and reference numeral 208 is A writing unit for writing an image on the photosensitive drum 201, 209 is a paper discharge tray for discharging recording paper after fixing, and 210 is a recording paper. Reference numeral 211 denotes a registration roller that is activated / stopped so as to align with the toner image on the photosensitive drum 201. Reference numeral 212 denotes a discharge roller that conveys the recording paper to the discharge tray 209. Reference numeral 213 Indicates a conveying roller.

  In the image forming apparatus shown in FIG. 61, a sheet feeding conveyance system such as a main body sheet feeding tray 204, a bank sheet feeding tray 205, a manual feed tray 206, a sheet feeding roller 210, and a registration roller 211 is disposed. After the image is transferred from the paper feed conveyance system through the image forming side of the process cartridge 203, the image is discharged to the paper discharge tray 209 through the fixing unit 207 and the paper discharge roller 212. The image forming speed is 90 mm / s.

  A writing unit 208 including an LD unit, a polygon mirror, an fθ lens (all not shown) and the like are disposed above the process cartridge 203. Although not shown, a drive transmission system including a drive motor, a solenoid, and a clutch (mechanical clutch, electromagnetic clutch) for rotationally driving the photosensitive drum 201 and each roller is provided. In the image forming apparatus configured as described above, driving sound of the drive motor and the drive transmission system, operation sound of the solenoid clutch, feeding sound of the recording paper, charging sound, and the like are emitted during image formation.

  62 is a cross-sectional view showing a configuration example of the process cartridge 203 in FIG. The process cartridge 203 includes a charging roller 221 as a charging unit, a developing roller 222 as a developing unit, a cleaning blade 223 as a cleaning unit, an agitator 225 that stirs toner 224 and sends it to the developing roller 222, and a stirring shaft 226. And a developing blade 227. The charging roller 221 includes a cored bar 221a and a charging unit 221b.

  Around the photosensitive drum 201 as an image carrier, a charging roller 221, a developing roller 222, and a cleaning blade 223 are arranged under predetermined conditions. The toner 224 in the process cartridge 203 is stirred by the agitator 225 and the stirring shaft 226 and is carried to the developing roller 222. The toner 224 attached to the roller surface by the magnetic force in the developing roller 222 is negatively charged by frictional charging when passing through the developing blade 227. The negatively charged toner moves to the photosensitive drum 201 by the bias voltage and adheres to the electrostatic latent image.

  When the recording paper sent by the registration roller 211 passes between the photosensitive drum 201 and the transfer roller 202, the toner on the photosensitive drum 201 is transferred to the recording paper by the positive charge from the transfer roller 202. The toner remaining on the photosensitive drum 201 is scraped off by the cleaning blade 223 and is collected as waste toner in a tank above the cleaning blade 223. The parts other than the transfer roller 202 are integrated as a process cartridge 203 so that the user can replace them.

  FIG. 63 is an explanatory diagram showing the configuration of the charging roller 221 in FIG. As shown in FIG. 62 and FIG. 63, the charging roller 221 is charged so that the surface of the photosensitive drum 201 is uniformly primary charged by being driven by frictional force while always contacting the photosensitive drum 201 at a predetermined pressure. It is a member. As shown in FIG. 62, the charging roller 221 includes a cored bar 221a serving as a rotation shaft and a charging unit 221b formed concentrically around the cored bar 221a.

  When the charging process is performed on the charging roller 221, an AC voltage is superimposed on the DC voltage on the cored bar portion 221 a via the electrode terminal 231, the charging roller pressure spring 232, and the conductive bearing 233 from a high voltage power source. The applied bias voltage is applied, and the charging roller 221 uniformly charges the photosensitive drum 201 to the same voltage as the DC component of the bias voltage. The AC component of the bias voltage serves to uniformly charge the photosensitive drum 201 by the charging roller 221.

  By the way, when the photosensitive drum 201 is contact-charged by the charging roller 221, an attractive force and a repulsive force act alternately between the surface of the charging roller 221 and the photosensitive drum 201 due to the AC component of the bias voltage, and the charging roller 221. Causes vibration. This vibration of the charging roller 221 generates an irritating vibration sound (charging sound) having a high frequency in the charging roller 221 itself, and is also transmitted to the photosensitive drum 201 side, causing the photosensitive drum 201 to vibrate and generating noise. Let

FIG. 64 is a cross-sectional configuration diagram showing an outline of an in-body paper discharge type digital copying machine 300 as an example of a medium-speed image forming apparatus.
In FIG. 64, the image forming apparatus mainly includes a main body 301 and a paper feed bank unit 302 capable of two-stage paper feed. Since the main body 301 is provided with a two-stage paper feed tray, the function of the image forming apparatus can be exhibited only by the main body 301 without the paper feed bank unit 302. Further, an inexpensive supply storage table (not shown) having the same outer shape can be attached instead of the paper feed bank unit 302. In the drawing, a route indicated by a solid arrow is a paper conveyance route at the time of image formation when paper is fed from the first tray 310 of the main body 301. When paper is fed from the second-stage tray 311 of the main body 301 and the first-stage tray 312 and second-stage tray 313 of the paper supply bank unit 302, the paper conveyance route is indicated by a broken line. Specifically, it joins the same route as the first stage tray 310 of the main body 301.

  Inside the main body 301, a charging roller 307, a writing system optical unit 304, a developing roller 308, a transfer roller 309, and the like disposed around a drum-shaped photoconductor 306 are disposed. A unit 303, a registration roller pair 316, a toner bottle 321, a fixing device 317, a paper discharge roller pair 319, and the like are arranged.

  The operation of the copying machine 300 configured as described above will be briefly described. First, document data is read by the reading system optical unit 303 and converted into a digital electric signal. This digital electrical signal is subjected to image processing and sent to the writing optical unit 304. A light beam 305 based on the digital signal is emitted from the writing system optical unit 304 and irradiated onto the photoconductor 306. The photosensitive member 306 is rotationally driven in the counterclockwise direction of FIG. 64, the surface is uniformly charged by the charging roller 307, and the original image is written onto the charged surface by the writing system optical unit 304 as described above. As a result, an electrostatic latent image is formed on the photosensitive member 306, and this latent image is visualized as a toner image by the developing roller 308. The toner is supplied from the toner bottle 321 to the developing unit including the developing roller 308.

  On the other hand, a paper supply operation will be described using an example in which paper is fed from the first tray 310 of the main body 301. Only one sheet is separated from the first-stage tray 310 in which the sheets are stacked and stored by the sheet feeding roller 314. The separated sheet is turned tightly while being assisted by the conveyance auxiliary roller 315, and is directed upward. After being abutted against the registration roller pair 316 and subjected to registration adjustment and timing adjustment, the sheet is directed to the image forming unit. .

  An image formed of toner on the photoconductor 306 is transferred to the paper when the paper passes between the photoconductor 306 and the transfer roller 309. Thereafter, the toner is conveyed to the fixing device 317, and the toner is fixed on the paper by the fixing roller pair 318 of the fixing device 317, and is discharged to the paper discharge tray 320 by the paper discharge roller pair 319. The image forming speed in this example is, for example, about 122 mm / s, and 27 images can be formed per minute.

  FIG. 65 is a cross-sectional configuration diagram showing an outline of a copying machine with ADF 400 which is an example of a large (console type) image forming apparatus. The copier 400 with ADF of this example is designed to have a high overall height so that it can be installed and used on the floor. The upper unit is an ADF (automatic document feeder) 410, a scanner 420, a writing unit 430, and an image forming engine 440. A console type digital MFP (multi-function printer) comprising a device main body and the like, and a bank paper feeding unit 570 as a lower unit. In other words, there may be provided a normal copy function, a printer function according to an instruction from a personal computer, and a facsimile function. This type of image forming apparatus is generally a high speed machine.

  The main body of the apparatus has an optical unit 421 in which optical elements (scanner 420, writing unit 430) are housed in a housing, and an image forming engine 440 positioned below the optical unit 421, and an ADF 410 is disposed on the top of the housing. is doing.

  In FIG. 65, reference numeral 401 denotes a photosensitive drum as an image carrier on which an electrostatic latent image is formed, reference numeral 402 denotes a charging charger, reference numeral 403 denotes a developing unit, reference numeral 404 denotes a transfer / separation charger, reference numeral 405 denotes a cleaning unit, Reference numeral 406 is a fixing unit, reference numeral 407 is a registration roller, reference numeral 411 is a document table, reference numeral 412 is a contact glass, reference numeral 413 is an exposure lamp, reference numeral 414 is a first mirror, reference numeral 415 is a second mirror, and reference numeral 416 is a third mirror. 417 is an imaging lens, 418 is a CCD, 419 is a mirror, and 490 is a caster with a lock function.

  That is, the scanner 420 includes a contact glass 412 for placing a document and a scanning optical system. The scanning optical system includes a first carriage on which the exposure lamp 413 and the first mirror 414 are mounted, a second carriage that holds the second mirror 415 and the third mirror 416, an imaging lens 417, and a CCD 418. Yes. A first carriage that is driven by a stepping motor and moves at a constant speed when reading an original is provided, and a second carriage that is driven at a speed half that of the first carriage.

  An original (not shown) on the contact glass 412 is optically scanned by the first carriage and the second carriage, and the reflected light obtained there is an exposure lamp 413, a first mirror 414, a second mirror 415, a third one. An image is formed on the CCD 419 via the mirror 416 and the imaging lens 417, and photoelectrically converted.

  The writing unit 430 includes a laser output unit, an fθ lens, a mirror (all not shown), and the like. The laser output unit is provided with a laser diode and a polygon mirror which are laser light sources.

  The image signal output from the image processing unit is converted into a laser beam having an intensity corresponding to the image signal by the writing unit 430, and is shaped into a light beam having a fixed shape by a collimating lens, an aperture, and a cylinder lens, and then converted into a polygon mirror. Irradiated and output. The laser beam output from the writing unit 430 is applied to the photosensitive drum 401 through the mirror 419. The laser beam that has passed through the fθ lens is applied to a beam sensor (not shown) that generates a main scanning synchronization detection signal arranged outside the image area.

  The ADF 410 conveys the original set on the original table 411 to the contact glass 412 one by one, and discharges it after reading. That is, the document is set on the document table 411 and the width direction is aligned by the side guide. Documents on the document table 411 are fed one by one from the bottom document by a feed roller, and are fed onto the contact glass 401 by the transport belt 453. After the reading on the contact glass 412 is completed, the original is discharged onto the discharge tray by the conveyance belt and the discharge roller.

  The recording sheets stacked on the first tray 471, the second tray 472, the third tray 473, and the fourth tray 474 of the bank sheet feeding unit 470 are respectively the first sheet feeding device 475, the second sheet feeding device 476, and the second sheet feeding device 476. The paper is fed by the third paper feeding device 477 and the fourth paper feeding device 478 and further conveyed by the bank vertical conveying unit 479 and the main body vertical conveying unit 480. When the leading edge of the recording paper is detected by a registration sensor (not shown), the recording paper is conveyed for a predetermined time, and then temporarily stops at the nip portion of the registration roller 407 and enters a standby state.

  The waiting recording paper is sent to the photosensitive drum 401 in accordance with the timing of the image valid signal, and is brought into close contact with the photosensitive drum 401 when the transfer / separation charger 404 is turned on, so that the image is transferred. Further, the recording paper is separated from the photosensitive drum 401 by separating from the photosensitive drum 401. The recording paper onto which the toner image has been transferred is conveyed by a conveying device, fixed by the heat and pressure action of the fixing unit 406 composed of a fixing roller and a pressure roller, and discharged outside the apparatus by a paper discharge roller 481. . The image forming speed in this example is, for example, about 362 mm / s.

  As described above, the image formation on the photosensitive drum 401 is performed by irradiating the laser beam with the electric charge charged on the photosensitive drum 401 by the charging charger 402, and forming the electrostatic latent image by the developing unit 403. An image is formed on the drum 401.

  When duplex printing is performed using the duplex unit 485, the recording paper after fixing is guided to the duplex conveyance path 486 by the switching claw 428, passes through the feed roller 432 and the separation roller 433, and is accumulated on the duplex tray. The recording paper accumulated in the tray comes into contact with the feed roller when the tray rises, and is fed to the main body vertical conveyance unit 480 when the feed roller rotates, and is fed again to the registration roller 407 and then back to the back surface. Is printed.

  When performing reverse paper discharge, the switching claw 467 guides the recording paper toward the reverse tray 464, and when the rear end of the recording paper passes the reverse detection sensor 468, the transport roller 469 reverses and the paper discharge tray direction And discharge the paper to a preset tray.

[IV. Remodeling method of image forming apparatus]
By the way, the sound quality evaluation method of the present invention can be applied to noise countermeasures for image forming apparatuses that have already been manufactured or already sold. That is, the sound generated by the image forming apparatus that has already been sold is measured as described above, and the sound quality evaluation value S is derived from the measurement result using the sound quality evaluation formula. Then, it is determined whether or not the calculated sound quality evaluation value S satisfies a predetermined condition, and if it satisfies the condition, it is considered that almost no unpleasant noise is generated, and it is determined that no modification is necessary. On the other hand, when the calculated sound quality evaluation value S does not satisfy the predetermined condition, various modifications are made to each part of the image forming apparatus so that the sound quality evaluation value S satisfies the predetermined condition, thereby causing unpleasant noise. It is possible to provide an image forming apparatus that hardly emits light.

  In the following, specific examples of countermeasures for modifying the image forming apparatus to reduce the discomfort of the sound generated by the image forming apparatus will be described by taking the case of the four example image forming apparatuses described above as an example. explain.

  First, in order to evaluate the sound emitted from the image forming apparatus, the sound emitted from the image forming apparatus is collected by the same method as the above-described sound quality evaluation method (1). Here, the sampling position is the position of a neighbor specified in ISO 7779, at a distance of 1.00 ± 0.03 m from the projection of the horizontal plane of the reference box, and the height is 1.2 ± 0.03 m above the floor or The position is 1.50 ± 0.03 m.

  Also, as shown in FIG. 3, sound is collected on all four sides, such as the front, left and right, and rear surfaces where the operation unit is provided, and the acoustic physical quantity is obtained from each sound collection result to obtain the sound quality evaluation value S as the sound quality. It is possible to determine whether the sound quality evaluation value S for each surface is within an allowable value by using an evaluation formula, or to evaluate the sound quality from the sound collection results collected only on the front surface or only one surface side. The determination may be made by obtaining the value S.

  Further, an average value of psychoacoustic parameter values obtained from sounds collected on the four sides may be derived, and it may be determined whether or not the sound quality evaluation value S obtained from the average value is within an allowable value.

  In order to prevent people on any of the four sides from feeling uncomfortable, it is preferable to collect sound at all positions on the four sides. Satisfactory evaluation can also be made by collecting sound on the front side, which has high characteristics.

  When the sound quality evaluation value S obtained as described above exceeds the allowable value described above, it is very likely that the person feels uncomfortable, so that the sound quality evaluation value S is less than the allowable value. Various modifications are made to each part of the device. On the other hand, when the sound quality evaluation value S is less than or equal to the allowable value, it is less likely that a person feels uncomfortable, and it can be determined that it is not particularly necessary to take measures against noise.

  As described above, the sound quality evaluation value S is given to a person by reducing the first factor (volume), the second factor (impact), the third factor (high frequency component), and the fourth factor (pure sound component). Discomfort can be reduced. Therefore, in the following, a specific countermeasure example for reducing the above factors will be described.

(1) Countermeasure for reducing fourth factor (pure sound component) Image forming apparatus (color printer 100) having a plurality of modes (1-1) Reduction of drum driving stepping motor sound

  First, an example of measures for reducing the fourth factor (pure sound component) will be described. As a measure for reducing the fourth factor (pure sound component), there is a method of reducing drum drive stepping motor sound. As shown in FIGS. 4, 5, and 6, the drum drive motor generates sound in any of the operation modes. And this sound contains many frequency components of the input pulse to the stepping motor.

  66 and 67 are views showing a drum drive mechanism including a color drum drive motor 41 and a black drum drive motor 42 before modification. As shown in these drawings, the color drum drive motor 41, the black drum drive motor 42, and the gears 43 and 44 are held by a motor bracket 59.

  The motor bracket 59 is a member obtained by giving strength to a sheet metal by drawing or the like. A housing attachment portion (screw hole or the like) of the image forming apparatus is formed by bending, and the motor bracket 59 is fixed to the housing at this attachment portion.

  Four gears 44 arranged side by side are rotatably held by the motor bracket 59. Of these gears 44, the rightmost gear 44 in FIG. 66 and the gear 61 attached to the motor shaft of the black drum drive motor 42 are engaged with each other. As a result, the gear 44 is rotated by the black drum driving motor 42, and the photosensitive drum 28 (see FIG. 55) for forming a monochrome image is rotated accordingly.

Of the three gears 44 other than the gear 44, the left two gears 44 in FIG. 66 are rotated by the motor shaft 62 of the color drum drive motor 41.
Further, the second gear 44 and the third gear 44 from the left are both meshed with the relay gear 43, whereby the third gear 44 is rotated with the rotation of the second gear 44. That is, with the rotation of the color drum drive motor 41, the three gears 44 are rotated, whereby the C, M, and Y photoconductive drums 28 (see FIG. 55) are simultaneously rotated. Yes.

  The gear for driving the photosensitive drum as described above adopts a special anti-vibration structure etc. for the motor installation so that the distance between the shafts of the gear can be accurately adjusted to the design value with module 0.5. Not done. That is, the black drum drive motor 42 and the color drum drive motor 41 are directly attached to the motor bracket 59 and fixed.

  By directly attaching the motor to the motor bracket 59 in this way, the vibration of the motor during operation propagates to the motor bracket 59 solidly and is amplified and radiated. The sound generated due to this is a sound containing a lot of driving frequency components of the stepping motor which is a drum driving motor.

  In order to reduce the generation of sound with a significant driving frequency component of such a stepping motor, as shown in FIG. 68, the color drum driving motor 41 and the black drum driving motor 42 are connected to a motor bracket 65 via an anti-vibration rubber mount 60. To be attached to. That is, the anti-vibration rubber mount 60 serves as a reduction means for reducing the sound generated as described above.

  As the anti-vibration rubber mount 60, for example, a stepping motor mount manufactured by NOK Co., Ltd. can be used, and the stepping motor mount is used in a test to test the effect of noise countermeasures described later.

A drum drive mechanism in which an anti-vibration rubber mount 60 is interposed between the motor bracket 65 and the drum drive motor will be described with reference to FIGS. 69 and 70. FIG.
If the anti-vibration rubber mount 60 is interposed between the drum drive motor and the motor bracket 65, the accuracy of the inter-shaft distance of each gear deteriorates. For this reason, this drum drive mechanism is configured to transmit the driving force from the motor shaft to the gear 44 and the like via the timing belt mechanism, instead of directly engaging the motor shaft with the gear.

  More specifically, timing pulleys 66 and 67 are attached to the motor shafts of the color drum driving motor 41 and the black drum driving motor 42, respectively, and a two-stage gear / motor is driven by the timing belt 70 wound around the timing pulleys 66 and 67. The driving force of the motor is transmitted to the pulleys 63 and 64. That is, the two-stage gear / pulleys 63 and 64 are rotated with the rotation of the motor shaft.

  The two-stage gear / pulley gear is engaged with the drum driving gear 44 described above. As a result, the gear 44 can be rotated in accordance with the rotation of the drum drive motor, and the photosensitive drum 28 (see FIG. 55) can be rotated, as in the configuration before the remodeling.

  The motor bracket 65 is bent so that the portion that holds the motor (the lower portion in FIG. 70) protrudes to the opposite side of the motor from the upper portion. The anti-vibration rubber mount 60 is arranged in contact with the motor bracket 65 in the space formed in the protruding portion, and the motor (41, 42) on the opposite side of the anti-vibration rubber mount 60 from the motor bracket 65 has its motor shaft mounted on the motor bracket 65. Is arranged so as to protrude from the surface on the opposite side (left side in FIG. 70). In this manner, the structure is such that the motor bracket 65 and the motor are not directly held, but are held with the anti-vibration rubber mount 60 interposed therebetween.

  In this configuration, the two-stage gear / pulleys 63 and 64 are arranged on the left side of the motor bracket 65 in FIG. 70 (the side on which the gear 44 is arranged), so that the motor shaft protrudes to the left side in FIG. It is necessary to let However, by forming a protruding portion on the motor bracket 65 as described above, the motor arrangement position itself can be set to the left side of FIG. 70, thereby eliminating the need to lengthen the motor shaft. Therefore, it is possible to suppress the eccentricity of the motor shaft that may be caused by lengthening the motor shaft and the generation of noise caused by the eccentricity.

  In this configuration, it is preferable to increase the strength of the stud 69 for attaching the two-stage gear / pulleys 63 and 64. If the strength of the stud 69 is insufficient, the gear 44 and the two-stage gear / pulley are engaged with each other while being eccentric, and the drum shaft 68 is also eccentric via the bearing 70. This is because the eccentricity of the drum shaft 68 may affect the image formed on the paper, and it is necessary to increase the strength of the stud 69 in order to prevent such a problem.

In addition to the above-described anti-vibration rubber mount, an elastic body that can absorb the vibration of the motor to some extent may be used.
The above is a measure for reducing the noise of the drum driving stepping motor.

(1-2) Reduction of Stepping Motor Sound for Paper Feeding Next, measures for reducing the noise of the stepping motor for paper feeding will be described. As described above, the sheet feeding motor of the image forming apparatus is the stepping motor 83 (see FIG. 60), and the conveyance of the sheet from the tray is performed by controlling the driving of the stepping motor. As a measure for reducing the motor noise, there is a method of setting the drive control contents of the stepping motor 56 as follows, and the control contents will be described below.

  FIG. 71 is a diagram for explaining the movement of the rotor of the stepping motor driven at the step angle θ0. The step angle of the stepping motor is determined by the mechanical structure. Normally, the rotor moves at a time by such a step angle θ, so if the step angle θ is large, the movement is not smooth and vibrations occur. This causes noise.

  Therefore, in this configuration, so-called micro-step driving is performed in which the stepping motor is driven at a step angle smaller than the step angle θ determined by the mechanical structure by control by an electronic circuit as shown in the figure. That is, by performing current supply control such that the current value supplied to one phase of the excitation phase is gradually increased while the current value supplied to the other one phase is gradually decreased ((1) to FIG. 71). (Refer to (5)), it is possible to drive at a step angle smaller than the step angle θ, and smooth the movement to reduce noise.

  FIG. 72 is a diagram showing a 1-2 phase excitation sequence which is one of microstep driving of the stepping motor. 1-2 phase excitation is an excitation method that alternately repeats one phase excitation for exciting a coil one phase and two phase excitation for exciting a coil two phases. When a stepping motor is driven using this excitation method, The motor step angle is halved, and the movement of the rotor is smoother than normal driving, and vibration can be reduced.

(1-3) Reduction of Polygon Mirror Motor Sound Next, a countermeasure for reducing the sound generated by the polygon mirror motor will be described with reference to FIG. As shown in the figure, in this measure, a Helmholtz resonator 71 is attached in the vicinity of the polygon mirror motor 2. More specifically, a Helmholtz resonator 71 is attached to the upper part of the housing 12 that holds the polygon mirror motor 2.

  The Helmholtz resonator 71 has a cavity forming member 72a for forming a cavity 72 having a volume V1. The cavity forming member 72 a is formed integrally with the housing 12, and an opening hole 73 (cross-sectional area Sb) leading to the cavity 72 is formed at a portion facing the polygon mirror motor. Here, if the thickness of the portion where the opening hole 73 is formed is Tb, the opening hole 73 corresponds to a short tube having a length Tb and an opening area Sb in a general Helmholtz resonator. This structure functions as a Helmholtz resonator 71.

  Under this configuration, when the polygon mirror motor 2 is driven and a sound pressure acts on the entrance of the opening hole 73 by the vibration, the air (medium) in the opening hole 73 (short pipe) performs an integral motion, and the inside of the cavity 72 This causes a pressure change in the air. Such a phenomenon is equivalent to the mass point-spring model of the dynamic system, assuming that the air in the opening hole 73 (short pipe) is a mass point and the pressure change due to the volume change of the air in the cavity 72 is a spring. Resonance (resonance) occurs with respect to the Helmholtz resonance frequency. That is, since the acoustic energy of this Helmholtz resonance frequency is confined in the cavity 72, the sound is reduced for the external space.

Here, the Helmholtz resonance frequency Fh (Hz) is calculated by the following equation.
Fh = C / 2π (Sb / (V1 · Tb)) 1/2
C: Speed of sound

  That is, the resonance frequency is changed by changing the opening area Sb, the length Tb (that is, the plate thickness of the portion of the housing 11 where the opening hole 73 is provided), and the volume V1 of the cavity 72 formed by the cavity forming member 72a. Fh, that is, the frequency of the sound to be reduced can be changed. Therefore, if the dimensions and the like of the above parts are designed so as to match the frequency at which the level becomes the highest among the sounds generated when the polygon mirror motor 2 is driven, the sounds generated by the polygon mirror motor 2 can be effectively obtained. Can be reduced.

  From the noise measurement results described above (see FIGS. 4 to 6), although the polygon mirror motor sound is extracted as noise in the color mode, the sound is not so noticeable as noise in the monochrome mode. . In such a case, the dimensions and the like of each part may be determined so that the Helmholtz resonance frequency matches the frequency of the highest level among the sounds generated by the polygon mirror motor in the color mode as described above. On the other hand, when the level of other frequencies is high in the monochrome mode, a Helmholtz resonator may be separately provided so that this frequency becomes the resonance frequency.

  In addition, a Helmholtz resonator may be provided for each corresponding frequency as described above, but a mechanism for changing the opening area Sb of the opening hole 73 in the color mode and the monochrome mode may be provided. . For example, by providing a lid member or the like that can be moved between a position where the opening hole 73 is blocked to some extent and a position where the opening hole 73 is not blocked, and moving the lid member according to the mode, the resonance frequency in each mode is changed to each mode. It may be varied so as to match the frequency at which the level sometimes increases.

(1-4) Reduction of electrification noise Next, measures for reduction of electrification noise will be explained. The charged sound is sound generated as follows. That is, when the charging roller 36 charges the photosensitive drum 28 (see FIG. 55), an attractive force is generally generated between the surface of the charging roller 36 and the surface of the photosensitive drum 28 due to the AC component of the bias voltage. Repulsive forces act alternately, causing vibration between them. The sound radiated from the photosensitive drum 28 by this vibration is a charging sound, and the sound is an unpleasant pure sound with a high frequency, and is generally an AC component frequency and an integral multiple frequency component (harmonic component). Consists of.

  Such measures for reducing the charging noise will be described with reference to FIGS. 74 and 75. FIG. As shown in FIG. 74, a vibration damping member 74 is disposed in the hollow portion of the photosensitive drum 28 in which measures against charging noise are taken. The damping member 74 has a hollow cylindrical base portion 75 extending in the axial direction of the photosensitive drum 28 and a plurality of blade portions 76 projecting radially from the base portion 75, and the central axis of the base portion 75 is photosensitive. It arrange | positions so that it may correspond with the center axis | shaft of the body drum 28 substantially.

  The tip of each blade portion 76 of the damping member is in pressure contact with the inner surface of the photosensitive drum 28, whereby the damping member 74 is held in the photosensitive drum 28. Here, it is preferable that the blade | wing part 76 is comprised with elastic materials, such as thermoplastic resin materials, such as rubber | gum, resin, or the material containing these, for example, the material containing urethane rubber, a polypropylene resin, a polyamide resin. By using an elastic material as the blade portion 76, the tip of the blade portion 76 is pressed against and held by the photosensitive drum 28 by its elastic force. This eliminates the need for a bonding operation or a positioning operation using an adhesive or the like, and facilitates an attachment operation and a removal operation.

  As described above, the vibration damping member 74 is arranged so that the blade portion 76 is in pressure contact with the inner surface side of the photosensitive drum 28, so that the vibration damping member 74 acts to suppress vibration of the photosensitive drum 28. Accordingly, it is possible to suppress vibration of the photosensitive drum 28 that occurs during charging by the charging roller 36 described above. In addition, since the member for suppressing the vibration of the photosensitive drum 28 is installed inside the photosensitive drum 28 as described above, it is not necessary to take measures such as newly taking a space for installing the damping member. .

  The means for suppressing the vibration of the photosensitive drum 28 to reduce the noise is not limited to the vibration damping member 74 having the above-described configuration, and measures such as fitting a metal column into the hollow portion of the photosensitive drum 28 are taken. Alternatively, a commercially available damping material (for example, a rubber damper manufactured by Yokohama Rubber Co., Ltd.) may be attached.

About Desktop Type (Desktop) Image Forming Apparatus As shown in FIG. 7, AC charging sound is also generated in the monochrome printer 200 which is a desktop type (desktop) image forming apparatus. Also in this case, the generation of AC charging sound can be suppressed by the same means as in the case of the color printer 100.

(2) Countermeasure for reducing third factor (high frequency component) Image forming apparatus (monochrome printer 200) having a plurality of modes (2-1) Reduction of paper sliding noise

  Next, measures for reducing sharpness (high frequency components) will be described. As a measure for reducing sharpness, there is a method of reducing paper sliding noise. Note that the paper sliding noise is a sound generated when the conveyed paper slides with a member or the like.

  As described above, the sheets stored in the first tray 9 or the second tray 10 of the image forming apparatus having a plurality of modes are fed out from each tray by the first sheet feeding unit 51 or the second sheet feeding unit 52 and relayed. It is conveyed to the position of the registration roller 7 by the roller 53 and the conveyance roller 55 (see FIG. 59).

  Here, FIGS. 76A and 76B show a case where the paper stored in the first tray 9 or the second tray 10 is conveyed to form an image (during normal printing) and a case where printing is performed without conveying the paper (free). The result of frequency analysis (1/3 octave band analysis) by measuring the noise generated by the image forming apparatus is shown. FIG. 77 is a graph showing the sound pressure level difference in each frequency band obtained from the noise during normal printing and free-running indicated in this analysis result.

  That is, the sound pressure level for each frequency band shown in FIG. 77 is a difference in noise content generated by the image forming apparatus due to whether or not the paper is sent out from the first tray 9 or the second tray 10 and conveyed. It means that the sound pressure level is increased in each frequency band as shown in FIG. 77 by conveying the paper.

  From the graph shown in FIG. 77, there are two differences of 3 (dB) or more between normal printing and free running in a band centering on 200 to 250 Hz and a band of 3.15 kHz or more. . Note that the difference of 3 dB or more means that the acoustic energy is twice or more.

  Examining the above analysis results, it has been found that the band component centered at 200 to 250 Hz is caused by the sound generated when the sheet and the registration roller 7 collide. On the other hand, it has been found that the component in the frequency band of 3.15 kHz or more is caused by the sound generated when the sheet slides on the member or the like during sheet conveyance.

  Further, in the band centered on 12.5 kHz to 16 kHz, there is a difference of 7 (dB) or more, and this band has a great influence on the sharpness value. From this, it can be seen that reducing the sheet sliding noise is effective as a noise countermeasure.

Hereinafter, a countermeasure for reducing the sliding noise of the sheet conveyed by the sheet feeding unit, the relay roller 53, and the conveying roller 55 will be described with reference to FIG.
As shown in the figure, the transport roller 55 is a roller that has a plurality of rollers passing through its shaft, and includes a roller 55a and a roller 55b that are disposed to face each other across the paper transport path. Then, the sheet 55 conveyed along the conveyance path A (the sheet fed from the first tray 9) or the sheet conveyed along the conveyance path B (the sheet fed from the second tray 10) is applied to the roller 55a. , 55b and conveyed toward the registration roller 7 by rollers 55a, 55b.

Guide members 80, 81, 82 for conveying the paper along a predetermined path are disposed in the vicinity of the conveyance roller 55.
The guide member 80 forms a space for guiding the paper conveyed along the conveyance path A together with the rollers 55a between the rollers 55a and 55b. The guide member 80 forms a space for guiding the sheet conveyed along the conveyance path B together with the guide member 81 toward the rollers 55a and 55b.

  A guide member 77 made of a treadable sheet (for example, a mylar sheet) extending in the paper conveyance direction (vertical direction in the figure) is attached to the downstream side of the guide member 80 in the conveyance direction (upper side in FIG. 78). The guide member 77 guides the sheet conveyed from the conveying paths A and B toward the rollers 55a and 55b.

  As shown in FIG. 79, a cutout portion 77a is formed by cutting or the like at a position where the roller 55a is arranged so as not to intersect with the roller 55a in the leading end portion of the guide member 77. The tip is brought into contact with the roller 55a and 55b so as to be surely guided.

  Therefore, as shown in FIG. 80, the sheet from the conveyance path A is conveyed while sliding on the leading end portion of the guide member 77. The conventional general guide member 77 is manufactured by shearing a flexible sheet into a predetermined shape, and a burr is usually provided at the tip portion (shear portion). It is very difficult to remove such burrs one by one, which requires cost and time. Therefore, normally, such an operation is not performed, and an awkward noise is generated by the sliding of the front end portion with the burr and the paper.

  Therefore, in this configuration, by employing the guide member 78 having the configuration shown in FIG. 81, it is possible to reduce annoying noise caused by the sliding of the paper and the leading end portion of the guide member 78 as described above. .

  As shown in FIG. 82, a guide member made of a conventional flexible sheet is a flexible sheet having a thickness t sheared into a predetermined shape as a guide member 77 as it is, and the leading end on which the paper slides. The part is a sheared part. On the other hand, in the configuration shown in FIG. 81, a flexible sheet having a thickness of t / 2 is folded to overlap two sheets so that the bent portion becomes the tip portion of the guide member 78. By adopting the guide member 78 having such a configuration, the leading end portion on which the sheet conveyed as described above slides is a bent portion, a portion not subjected to shearing, and a smooth R shape. Become. Therefore, it is possible to reduce generation of annoying noise caused by burrs in the sheared portion as described above. Further, since the thickness of the two stacked sheets is the same as that of the conventional guide member 77, the required elastic force can be exhibited and the function as the guide member is not hindered.

About Large (Console Type) Image Forming Apparatus An example of reducing sheet sliding noise will be shown for the copying machine 400 with ADF, which is a large (console type) image forming apparatus.

  First, the configuration of the conveyance path, which is the sound source of the paper sliding sound, and the cause of occurrence will be described. FIG. 83 is an explanatory diagram showing a detailed configuration of the rollers and guide plates of the main body vertical conveyance unit 480 in the image forming apparatus shown in FIG. That is, it is a cross-sectional view of a conveyance portion that guides conveyance from a paper feed tray and conveyance from an intermediate tray for double-sided copying in the direction of a registration roller. FIG. 84 is an explanatory diagram showing the relationship between the recording paper and the flexible sheet 459 when noise is not taken.

  In FIG. 83, reference numerals 450 and 451 denote rollers provided with a plurality of rollers on a shaft. The roller 450 and the roller 451 are paired to form a first transport roller pair that transports the recording paper, and rotates so as to transport the recording paper transported from the paper feed tray in the A direction shown in the figure. Reference numerals 452, 453, and 454 denote rollers provided with a plurality of rollers on a shaft. The roller 452 and the roller 453 are paired to form a second transport roller pair for transporting the recording paper, and the recording paper transported from the intermediate tray is rotated so as to transport in the direction B shown in the drawing. Further, the roller 452 and the roller 454 are paired to form a third conveyance roller pair for conveying the recording paper, and the roller 452 and the roller 454 are rotated so as to be conveyed in the direction C in FIG.

  Guide plates 455 and 456 are provided on the conveyance path of the first conveyance roller pair rotated so as to convey in the direction of arrow A, and the guide plates 455 and 456 have roller portions of the rollers 450 and 451. There is a hole to escape. Similarly, guide plates 457 and 458 are provided in the transport path of the second transport roller pair that rotates so as to transport in the direction of arrow B. The guide plates 457 and 458 include rollers 452 and 453. There is a hole to escape the roller. Further, in the conveyance path of the third conveyance roller pair that rotates so as to convey in the direction of arrow C, there are extended portions of the guide plates 456 and 457, so that the roller portions of the rollers 452 and 454 can escape. There is a hole in. That is, the conveyance force by the conveyance roller pair and the conveyance performance by the guide plate are ensured.

  A flexible sheet 459 extending in the conveyance direction of the recording paper is attached to the downstream end of the guide plate 455, and is provided so as to guide the recording paper. A conveyance path is formed so that the recording paper conveyed from the A direction is also conveyed in the C direction.

  Here, the recording paper conveyed in the B direction from the intermediate tray often has a downward curl, and in order to prevent the occurrence of folding and jamming (paper jam), a flexible sheet (specifically, Polyester film, product name: Mylar) 459 is bent in the right direction in the figure. Accordingly, the recording paper conveyed in the direction A from the paper feed tray enters between the rollers 452 and 454 by bypassing the front end of the flexible sheet 459.

  At this time, in the case of an unmeasured flexible sheet 459 as shown in FIG. 84, the recording paper is conveyed while sliding on the tip of the flexible sheet 459. However, since the surface of the recording paper has fiber irregularities, and the flexible sheet 459 is burred at the end surface by shearing processing, the irregularities progress on the fibers on the recording paper surface, so that the flexible sheet The burrs at the edge of 459 and the recording paper vibrate to generate a loud sound and become noise. Note that it is very costly and time-consuming to remove burrs at the edge of the flexible sheet 459 one by one. Therefore, as shown below, countermeasures to reduce paper sliding noise were made by devising the flexible sheet 59.

Examples of the flexible sheet according to the embodiment of the present invention are shown in FIGS. This is the same as in the case of an image forming apparatus having a plurality of modes.
85 and 86, the leading edge of the flexible sheet 459B attached to the guide plate 555 slides when the recording paper conveyed from the direction of arrow A in FIG. The surface of the paper has a certain degree of surface roughness, and a bent portion 459a is formed in order to reduce the occurrence of a sound containing a high frequency component when the edge is slid. The surface of the flexible sheet 459B is extremely smooth, and even when the bent portion 459a is provided, the smoothness is not lost.

(3) Reduction Factor of Second Factor (Impactability) Image Forming Apparatus Having Multiple Modes In the image forming apparatus (color printer 100) configured as described above, the occurrence of impulsiveness is mostly caused by fixing oil application sound. (See FIGS. 4 to 6). In the image forming apparatus configured as described above, the fixing oil application sound is configured to drive the oil application unit 47 and contact the fixing belt 13 each time a sheet is conveyed in order to suppress an increase in oil consumption. Adopted (see FIG. 58). Since such a contact / separation sound generated every time the sheet is conveyed is generated shockingly, an unpleasant feeling is given.

  The noise problem due to the fixing oil application sound can be solved by using an oilless toner as a toner used for image formation. That is, since the oil-less toner includes wax in the toner, the separation between the fixing belt and the paper is good without performing the oil application operation as described above. For this reason, it is not necessary to use the oil application unit 47, and it is possible to prevent the generation of impact sound due to the contact and separation between the oil application unit 47 and the fixing belt 13 described above. When using oilless toner, it is necessary to modify the image forming process configuration of the photoconductor unit 3 and the like so as to be suitable for the oilless toner.

Large-sized (console type) image forming apparatus FIG. 87 is an explanatory diagram showing the configuration of the paper feed / drive system of the bank paper feed unit 470 in FIG. As shown in FIG. 65, the image forming apparatus in this embodiment is configured to be capable of four-stage sheet feeding, and the upper stage is faster in image formation because the transport path is shorter. Therefore, frequently used A4 size recording paper is set in the first level (the top level), and the B4 and A3 sizes, which are generally used less frequently, are set in the third and fourth levels (lower level). Often, this type of recording paper is loaded.

  87, grip rollers 467 are provided in each of the four stages of paper feeding devices, and the recording paper fed from each paper feeding device goes upward through the grip rollers 467. The grip roller 467 is provided with a driven roller 469 facing each other and is pressurized by a pressure spring 470. The grip roller 467 and a paper separation mechanism (not shown) are driven by a bank motor 461 and convey the recording paper to the upper portion 400.

  An intermediate clutch 462, an intermediate clutch 463, an intermediate clutch 464, and an intermediate clutch 465 are provided on each shaft of the grip roller 467 from above. These intermediate clutches 462 to 465 are constituted by electromagnetic clutches, and grip the driving force using the bank motor 451 that is transmitted to the gears of the electromagnetic clutch via the timing belt and the gear train as the current is turned on / off. The roller 467 rotates or does not rotate. This drive mechanism is provided in order to increase the processing efficiency by feeding the recording paper during image formation to control the space between the recording papers to the minimum. The relay sensor 466 is used for taking an image writing timing and for detecting a jam (paper jam).

  By the way, the main factor of the metal impact sound in the image forming apparatus is the operation sound of the intermediate clutch of the bank paper feeding unit 570 (the metal collision sound that the disks are attracted by the force of the electromagnet in the clutch ON operation). I know. These four intermediate clutches operate each time one sheet of recording paper is fed. In order to simplify the control, the bank paper feeding unit 470 is configured to operate even when paper is fed from any stage. For this reason, even if paper is fed from the first stage of the bank paper feeding unit 470, the second to fourth stage grip rollers 467 that do not need to be driven are also driven. When paper is fed from the fourth stage (bottom 1), the recording paper is not conveyed upward unless all the grip rollers 467 are operated, so that all of the intermediate clutches 462 to 465 need to be operated.

  However, as described above, the most frequently used is paper feeding from the uppermost stage or the second tray of the bank paper feeding unit 470. The third and fourth stages are used less frequently because they are loaded with recording paper having a low usage frequency.

  The metal impact sound is generated greatly when the intermediate clutches 462 to 465 of the bank paper feeding unit 470 are operated simultaneously. Therefore, when the first stage of the bank is used, only the intermediate clutch 462 is operated. The energy generation of the metal impact sound can be suppressed to ¼. In this way, by controlling so that only the intermediate clutch in the upper stage of the bank used for paper feeding is operated, it is possible to suppress noise and consumption of electric energy.

  FIG. 88 is a flowchart showing an example of control of the intermediate clutch of the bank paper feeding unit 470. First, it is determined whether or not the first stage paper feed (step S11). If the first stage paper feed, the intermediate clutch 462 is operated (step S12). In step S11, if it is not the first-stage paper feed, it is further determined whether or not it is the second-stage paper feed (step S13). If it is the second-stage paper feed, the intermediate clutches 462 and 463 are operated. (Step S14). In step S13, if it is not the second stage paper feed, it is further determined whether or not the third stage paper feed is made (step S15). If it is the third stage paper feed, the intermediate clutches 462 to 464 are operated (step S13). S16) If the third-stage sheet feeding is not performed, that is, the fourth-stage sheet feeding (sheet feeding from the lowest tray), the intermediate clutches 462 to 465 are operated (step S17).

In this way, by performing control to turn on only the necessary intermediate clutch and not operating the lower intermediate clutch that is less frequently used, it is possible to suppress the occurrence of metal impact noise.

  FIG. 89 is a graph showing changes in metal impact sound before and after improvement of control of the intermediate clutch. “Before improvement” means that four intermediate clutches are operated simultaneously. The metal impact sound improvement is obtained by operating only the first-stage intermediate clutch 462. According to this, the impact sound of the clutch is a high-frequency broadband noise of about 1 k to 20 kHz and contributes not only to impulsiveness but also to sharpness and loudness. In this way, the unpleasant sound can be reduced by suppressing the sound source of the impact sound.

By reducing these sound sources, the first factor (volume) can also be automatically reduced.
The above is a specific example of measures for reducing the sound quality evaluation value S.

  The inventor of the present application measures the sound generated by the image forming apparatus to which the above measures are taken under the same conditions as when the sound generated by the image forming apparatus before the measures are measured, and the effect of the measures is determined from the measurement results. confirmed. The measurement results to be compared below were obtained by collecting sound on the front side of the image forming apparatus when the image forming apparatus was operated at a color of 28 ppm.

  FIG. 90 shows the analysis result of noise after the front countermeasure of the color 28 ppm machine. The upper side shows the change in sound pressure on the time axis, and the lower side shows the sound pressure level on the frequency axis. Comparing the analysis results after the countermeasures shown in the figure with the analysis results before the countermeasures (see FIG. 4), the paper feeding stepping motor noise is reduced by about 10 (dB) and the charging noise is about 5 from the frequency axis comparison. (DB), the drum drive motor sound is reduced by about 8 (dB), and the polygon mirror motor sound is also reduced by about 10 (dB).

  In addition, the comparison of sound pressure on the time axis also eliminated the fixing oil application sound. From the above, it can be seen that the sound produced by each sound source can be reduced by taking the above measures.

  FIG. 91 to FIG. 94 further compare the frequency distribution of the color 28 ppm machine according to the front, rear, left and right directions before and after the countermeasure. The pure tone component is reduced in each direction. In addition, although the cause is unknown in four directions, 400Hz rose.

  Table 30 shows a comparison result of the acoustic physical quantity obtained from the measurement result before the countermeasure and the sound quality evaluation value S based on the sound quality evaluation formula (c). Table 31 shows a comparison result between the acoustic physical quantity obtained from the measurement result after the countermeasure and the sound quality evaluation value S based on the sound quality evaluation formula (c).

As can be seen from this table, the sound quality evaluation value S is lower after taking countermeasures in the average values of the four directions.
Also,
S ≦ 0.4646Ln (ppm)-1.8426 ・ ・ ・ ・ ・ ・ （b）
Or S ≤ 0.4101Ln (v)-2.2997 (d)
Therefore, the allowable value of discomfort at 28 ppm (125 mm / s) is −0.29 in the case of the formula (b), and −0.32 in the case of the formula (c).

Only the left surface exceeded the allowable value with the sound quality evaluation value S = −0.11, but the average value in the other surfaces and the four directions was smaller than the allowable value.
Therefore, the image forming apparatus has been remodeled so as to cause almost no discomfort except for the right side by the above measures, and it can be said that the image forming apparatus hardly feels discomfort considering the average values in the four directions. Further, from the results of FIGS. 91 to 94, it is possible to expect further improvement in sound quality by reducing the 400 Hz sound whose cause is unknown, and the right side surface can also be reduced to an allowable value or less.

Although the present invention has been described above, the present invention is not limited to the above examples.
For example, the sound quality evaluation method according to the present invention can be used for the evaluation of noise (sound quality) generated by general office automation equipment other than image forming apparatuses, printing presses, home appliances, etc., and can be applied to the manufacture or modification of such equipment. It is.

It is a graph which shows the example of principal component analysis in sound quality evaluation. It is the graph which rotated and reversed the plot so that P1 component in FIG. 1 may become a main axis. FIG. 4 is a schematic diagram illustrating a state where an operation sound of the image forming apparatus is collected. It is a graph which shows the sound extract | collected when the color is 28 ppm. It is a graph which shows the sound extract | collected when the color is 14 ppm. It is a graph which shows the sound extract | collected at monochrome 38ppm. It is a graph which shows the analysis result of a desktop type image forming device (20 ppm) operation sound. It is a graph which shows the analysis result of a medium-speed image forming apparatus (27 ppm) operation sound. It is a graph which shows the analysis result of a large-sized image forming device (65 ppm) operation sound. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a graph which shows the relationship between the level of the measured sound source, and a subjective evaluation value. It is a correlation diagram regarding five acoustic physical quantities. It is a scatter diagram of the predicted value related to sound discomfort. It is the graph which comparatively plotted the sound quality evaluation predicted value of the apparatus operation mode and the actual measurement value. It is the graph which comparatively plotted the sound quality evaluation predicted value of the apparatus operation mode and the actual measurement value. It is the graph which comparatively plotted the sound quality evaluation predicted value of the apparatus operation mode and the actual measurement value. It is the graph which comparatively plotted the sound quality evaluation predicted value of the apparatus operation mode and the actual measurement value. It is the graph which comparatively plotted the sound quality evaluation predicted value of the apparatus operation mode and the actual measurement value. It is the graph which comparatively plotted the sound quality evaluation predicted value of the apparatus operation mode and the actual measurement value. It is the graph which comparatively plotted the sound quality evaluation predicted value of the apparatus operation mode and the actual measurement value. It is the graph which comparatively plotted the sound quality evaluation predicted value of the apparatus operation mode and the actual measurement value. It is the graph which put together the comparison plot of FIGS. It is the graph which approximated the relationship between ppm value in sound quality evaluation, and permissible value. It is the graph which approximated the relationship between the image formation speed and allowable value in sound quality evaluation. It is a flowchart which applies the sound quality evaluation method of this invention to development and manufacture of a new product. It is a cross-sectional block diagram which shows the outline of the tandem-type color printer used for sound quality evaluation. It is a cross-sectional block diagram which shows the optical unit of the color printer. 2 is a cross-sectional view of a photosensitive unit and a developing unit of the color printer. FIG. It is a perspective view showing a drive mechanism of a photosensitive unit of the color printer. FIG. 3 is a perspective view showing a fixing unit of the color printer. FIG. 3 is a cross-sectional view of a part of the fixing unit. It is sectional drawing which shows the structure of the paper feed part of the color printer. It is a perspective view which shows the structure which drives a paper feed unit. It is a cross-sectional block diagram which shows the outline of the desktop type image forming apparatus used for sound quality evaluation. FIG. 3 is a cross-sectional view illustrating a configuration example of a process cartridge of the image forming apparatus. It is explanatory drawing which shows the structure of a charging roller. It is a cross-sectional block diagram which shows the outline of the medium-speed image forming apparatus used for sound quality evaluation. It is a cross-sectional block diagram which shows the outline of the large sized image forming apparatus used for sound quality evaluation. It is a perspective view of the drum drive mechanism before taking a noise countermeasure. It is a schematic diagram for demonstrating the motor attachment part of the drum drive mechanism. It is a schematic diagram which shows the noise countermeasures applied to the motor attachment part of a drum drive mechanism. It is a perspective view of the drum drive mechanism which gave the noise countermeasure. It is a top view which shows the motor attachment part. It is a figure for demonstrating the motion of the rotor of the stepping motor for paper feeding. It is a figure which shows the sequence of 1-2 phase excitation which is one of the micro step drive of a stepping motor. It is a fragmentary sectional view for demonstrating the sound which a polygon mirror motor emits. FIG. 3 is a cross-sectional view of a photoconductor unit in which measures against charging noise are taken. It is a perspective view which shows the damping member arrange | positioned in a photoconductor drum. It is a graph which shows the result of having measured the noise at the time of normal printing, and the time of free-run, and performing frequency analysis. It is a graph which shows the sound pressure level difference of each frequency band obtained from the analysis result. FIG. 6 is a side view of a paper transport unit for explaining measures for reducing paper sliding noise. FIG. 6 is a front view illustrating a guide member disposed in a paper transport unit. FIG. 6 is a side view of a paper transport unit showing how a paper is transported. It is a side view which shows the guide member which gave the noise countermeasure. It is a side view which shows the conventional guide member. FIG. 66 is a side view showing a detailed configuration of a paper transport unit in the image forming apparatus of FIG. 65. It is explanatory drawing which shows the relationship between the recording paper at the time of noise non-measures, and a flexible sheet. FIG. 6 is a partial side view of a paper conveyance path to which a flexible sheet with noise countermeasures is attached. It is the front view. FIG. 66 is an explanatory diagram illustrating a configuration of a sheet feeding / driving system in the image forming apparatus of FIG. 65. 3 is a flowchart showing an example of control of the paper feed / drive system. It is a graph which shows the change of the metal impact sound before and behind improvement of intermediate clutch control. It is a graph which shows the analysis result of the noise after the front measures of a color 28ppm machine. It is the graph which compared the frequency distribution of the front side of a color 28ppm machine before and after countermeasures. It is the graph which compared the frequency distribution of the rear side of a color 28ppm machine before and after countermeasures. It is the graph which compared the frequency distribution of the left side of a color 28ppm machine before and after countermeasures. It is the graph which compared the frequency distribution of the right side surface of a color 28ppm machine before and after countermeasures.

Explanation of symbols

60 Anti-vibration rubber mount 65 Motor bracket 42 Drum drive motor 74 Damping member 78 Paper guide member 100 Color printer (image forming apparatus having a plurality of modes)
200 Monochrome printer (desktop image forming device)
300 In-body discharge copier (medium-speed image forming device)
400 Copier with ADF (Large image forming device)
501 Device under test 503 Dummy head 504 Ear position (sound collection position)

Claims (28)

A method for evaluating sound generated by an image forming apparatus during image formation,
The image forming apparatus takes any two sounds from the multiple types of sounds that are emitted during image formation, and evaluates them using a paired comparison method.
The objective variable is the distance between the discomfort of two sounds by the evaluation,
A multiple regression analysis is performed using a plurality of factors obtained as a result of factor analysis from the principal component analysis for the value of the difference between the two sound acoustic physical quantities when the two sounds are compared as a pair. The following formula (A) for predicting the distance of discomfort of two sounds is derived,
From the equation (A), the sound that is the average value of the acoustic physical quantities of all sounds (population) used in the paired comparison experiment is defined as the sound quality evaluation value α ₀ = 0.
Deriving a sound quality evaluation formula that predicts the discomfort of a single sound,
A sound quality evaluation method, wherein sound quality evaluation is performed using the derived sound quality evaluation formula. An image forming apparatus manufacturing method comprising:
The image forming apparatus takes any two sounds from the multiple types of sounds that are emitted during image formation, and evaluates them using a paired comparison method.
The objective variable is the distance between the discomfort of two sounds by the evaluation,
A multiple regression analysis is performed using a plurality of factors obtained as a result of factor analysis from the principal component analysis for the value of the difference between the two sound acoustic physical quantities when the two sounds are compared as a pair. The following formula (A) for predicting the distance of discomfort of two sounds is derived,
From the equation (A), the sound that is the average value of the acoustic physical quantities of all sounds (population) used in the paired comparison experiment is defined as the sound quality evaluation value α ₀ = 0.
Deriving a sound quality evaluation formula that predicts the discomfort of a single sound,
Using the derived sound quality evaluation formula, each part of the device is designed so that the sound quality evaluation based on the sound quality evaluation formula satisfies a predetermined condition,
An image forming apparatus manufacturing method, wherein the image forming apparatus is manufactured according to the design contents. A method for remodeling an image forming apparatus,
The image forming apparatus takes any two sounds from the multiple types of sounds that are emitted during image formation, and evaluates them using a paired comparison method.
The objective variable is the distance between the discomfort of two sounds by the evaluation,
A multiple regression analysis is performed using a plurality of factors obtained as a result of factor analysis from the principal component analysis for the value of the difference between the two sound acoustic physical quantities when the two sounds are compared as a pair. The following formula (A) for predicting the distance of discomfort of two sounds is derived,
From the equation (A), the sound that is the average value of the acoustic physical quantities of all sounds (population) used in the paired comparison experiment is defined as the sound quality evaluation value α ₀ = 0.
Deriving a sound quality evaluation formula that predicts the discomfort of a single sound,
Perform the sound quality evaluation of the sound emitted by the image forming apparatus to be modified using the derived sound quality evaluation formula,
A remodeling method for an image forming apparatus, comprising remodeling the configuration of the image forming apparatus to be remodeled based on the sound quality evaluation result. An image forming apparatus for forming an image on an image formation target sheet,
The sound pressure level value and the loudness value of the acoustic physical quantity obtained from the sound emitted by the image forming apparatus when image formation is performed on the image forming target sheet picked up at the sound collecting position approximately 1 m away from the end face of the image forming apparatus. , Sharpness value, tonality value, impulsiveness value,
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the output numerical value (ppm) of the image formation target sheet (A4 size lateral direction) per minute,
The sound quality evaluation value S calculated by the following equation (a) satisfies the following condition (b).
An image forming apparatus. An image forming apparatus for forming an image on an image formation target sheet,
Sound pressure level value and loudness of an acoustic physical quantity obtained from sound generated by the image forming apparatus when the image is formed on the image forming target sheet, which is picked up at a sound collecting position approximately 1 m away from the end face of the image forming apparatus. Value, sharpness value, tonality value, impulsiveness value,
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the output numerical value (ppm) of the image formation target sheet (A4 size lateral direction) per minute,
The sound quality evaluation value S calculated by the following equation (c) satisfies the following condition (b).
An image forming apparatus. An image forming apparatus for forming an image on an image formation target sheet,
Sound pressure level value and loudness of an acoustic physical quantity obtained from sound generated by the image forming apparatus when the image is formed on the image forming target sheet, which is picked up at a sound collecting position approximately 1 m away from the end face of the image forming apparatus. Value, sharpness value, tonality value, impulsiveness value,
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the image forming speed (v: mm / s) for the image forming target sheet,
The sound quality evaluation value S calculated by the following equation (a) satisfies the following condition (d).
An image forming apparatus. An image forming apparatus for forming an image on an image formation target sheet,
Sound pressure level value and loudness of an acoustic physical quantity obtained from sound generated by the image forming apparatus when the image is formed on the image forming target sheet, which is picked up at a sound collecting position approximately 1 m away from the end face of the image forming apparatus. Value, sharpness value, tonality value, impulsiveness value,
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the image forming speed (v: mm / s) for the image forming target sheet,
The sound quality evaluation value S calculated by the following equation (c) satisfies the following condition (d).
An image forming apparatus. Has multiple image forming speeds or multiple operating modes,
The image forming apparatus according to claim 4, wherein the sound quality evaluation value S satisfies the condition regardless of the image forming speed or the operation mode. The sound collection position is a neighbor position defined in ISO (International Organization For Standardization) 7779, and at least the sound quality evaluation value S calculated from the sound collection result of the sound in the front direction of the apparatus satisfies the condition. The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. The sound collection position is a neighbor position defined by ISO (International Organization For Standardization) 7779, and is an average of the sound quality evaluation values S calculated from the sound collection results of sound in four directions, front, rear, left, and right of the apparatus. The image forming apparatus according to claim 4, wherein a value satisfies the condition. The sound collection position is a neighbor position defined in ISO (International Organization For Standardization) 7779, and the sound quality evaluation value S calculated from the sound collection result of sound in any one direction of the front, rear, left and right of the apparatus is at least The image forming apparatus according to claim 4, wherein the condition is satisfied. The sound collection position is a neighbor position specified in ISO (International Organization For Standardization) 7779, and all the sound quality evaluation values S calculated from the sound collection results of the sound in the four directions of the front, rear, left and right of the apparatus. The image forming apparatus according to claim 4, wherein the condition satisfies the condition. The image forming apparatus according to claim 4, further comprising a reduction unit that reduces a sound generated by the apparatus during image formation on the image forming target sheet. A stepping motor that drives a predetermined part during image formation on the image forming target sheet; and a bracket member that holds the stepping motor;
The image forming apparatus according to claim 13, wherein the reducing unit includes an elastic body disposed between the stepping motor and the bracket member. A stepping motor for driving a predetermined part at the time of image formation on the image forming target sheet;
The image forming apparatus according to claim 13, wherein the reducing unit includes a drive control unit that micro-steps the stepping motor. A motor for driving a predetermined part at the time of image formation on the image forming target sheet;
The image forming apparatus according to claim 13, wherein the reducing unit includes a Helmholtz resonator disposed in the vicinity of the motor. A columnar image carrier having a hollow portion, and a charging means for charging the surface of the image carrier,
The image forming apparatus according to claim 13, wherein the reducing unit includes a damping member that suppresses vibration of the image carrier in a hollow portion of the image carrier. A guide member made of a flexible sheet for guiding the image forming target sheet along a predetermined transport path, wherein an end portion in contact with the image forming target sheet to be transported is a bent portion of the flexible sheet. The image forming apparatus according to claim 13, further comprising a guiding member. The image forming apparatus according to claim 13, wherein the toner used for image formation on the image forming target sheet is a toner containing wax. The reduction means is a paper feed conveyance control means for controlling the operation of the electromagnetic clutch provided in each of the paper feed conveyance paths having a plurality of paper feed stages so as to be an electromagnetic clutch higher than the paper feed stage to be used. The image forming apparatus according to claim 13. A method of manufacturing an image forming apparatus for forming an image on an image forming target sheet,
The acoustic physical quantity obtained from the sound produced by the image forming apparatus when the image is formed on the image forming target sheet, which is collected at a sound collecting position approximately 1 m away from the end face of the image forming apparatus to be manufactured. Sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value,
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the output numerical value (ppm) of the image formation target sheet (A4 size lateral direction) per minute,
A design step of designing each part of the apparatus so that the sound quality evaluation value S calculated by the following equation (a) satisfies the following condition (b):
And a manufacturing step of manufacturing the image forming apparatus in accordance with the design contents made in the designing step. A method of manufacturing an image forming apparatus for forming an image on an image forming target sheet,
The acoustic physical quantity obtained from the sound produced by the image forming apparatus when the image is formed on the image forming target sheet, which is collected at a sound collecting position approximately 1 m away from the end face of the image forming apparatus to be manufactured. Sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value,
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the output numerical value (ppm) of the image formation target sheet (A4 size lateral direction) per minute,
A design step of designing each part of the apparatus so that the sound quality evaluation value S calculated by the following equation (c) satisfies the following condition (b):
And a manufacturing step of manufacturing the image forming apparatus in accordance with the design contents made in the designing step. A method of manufacturing an image forming apparatus for forming an image on an image forming target sheet,
The acoustic physical quantity obtained from the sound produced by the image forming apparatus when the image is formed on the image forming target sheet, which is collected at a sound collecting position approximately 1 m away from the end face of the image forming apparatus to be manufactured. Sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value,
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the image forming speed (v: mm / s) for the image forming target sheet,
A design step of designing each part of the device so that the sound quality evaluation value S calculated by the following equation (a) satisfies the following condition (d):
And a manufacturing step of manufacturing the image forming apparatus in accordance with the design contents made in the designing step. A method of manufacturing an image forming apparatus for forming an image on an image forming target sheet,
The acoustic physical quantity obtained from the sound produced by the image forming apparatus when the image is formed on the image forming target sheet, which is collected at a sound collecting position approximately 1 m away from the end face of the image forming apparatus to be manufactured. Sound pressure level value, loudness value, sharpness value, tonality value, impulsiveness value,
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the image forming speed (v: mm / s) for the image forming target sheet,
A design step of designing each part of the apparatus so that the sound quality evaluation value S calculated by the following equation (c) satisfies the following condition (d):
And a manufacturing step of manufacturing the image forming apparatus in accordance with the design contents made in the designing step. A method of remodeling an image forming apparatus for forming an image on an image formation target sheet,
A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed on the image forming target sheet at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified;
A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from the sound collecting result in the sound collecting step;
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the output numerical value (ppm) of the image formation target sheet (A4 size lateral direction) per minute,
A modification step for modifying the configuration of the apparatus so that the sound quality evaluation value S calculated by the following equation (a) satisfies the following condition (b):
A method for remodeling an image forming apparatus, comprising: A method of remodeling an image forming apparatus for forming an image on an image formation target sheet,
A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed on the image forming target sheet at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified;
A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from the sound collecting result in the sound collecting step;
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the output numerical value (ppm) of the image formation target sheet (A4 size lateral direction) per minute,
A modification step for modifying the configuration of the device so that the sound quality evaluation value S calculated by the following equation (c) satisfies the following condition (b):
A method for remodeling an image forming apparatus, comprising: A method of remodeling an image forming apparatus for forming an image on an image formation target sheet,
A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed on the image forming target sheet at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified;
A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from the sound collecting result in the sound collecting step;
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the image forming speed (v: mm / s) for the image forming target sheet,
A modification step for modifying the configuration of the device so that the sound quality evaluation value S calculated by the following equation (a) satisfies the following condition (d):
A method for remodeling an image forming apparatus, comprising: A method of remodeling an image forming apparatus for forming an image on an image formation target sheet,
A sound collecting step for collecting sound generated by the image forming apparatus when image formation is performed on the image forming target sheet at a sound collecting position approximately 1 m away from an end surface of the image forming apparatus to be modified;
A sound pressure level value, a loudness value, a sharpness value, a tonality value, an impulsiveness value of an acoustic physical quantity obtained from the sound collecting result in the sound collecting step;
An unpleasant factor component obtained from a paired comparison result of sound of the image forming apparatus,
The average value of the acoustic physical quantities of all the test sounds used in the paired comparison experiment, sound pressure level average value, loudness average value, sharpness average value, tonality average value, impulsiveness average value,
Using the image forming speed (v: mm / s) for the image forming target sheet,
A modification step for modifying the configuration of the device so that the sound quality evaluation value S calculated by the following equation (c) satisfies the following condition (d):
A method for remodeling an image forming apparatus, comprising: