JP4347151B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a failure determination function of a drive system device such as an electric motor that rotationally drives an image carrier, and more particularly, to the amount of reflected light from the image carrier measured using a reflective photosensor. The present invention relates to an image forming apparatus capable of determining a failure of a drive system device such as an electric motor based on the above.

An electrophotographic image forming apparatus such as a copying machine, a facsimile machine, or a printer is provided with an electric motor such as a motor that rotationally drives an image carrier such as a photosensitive member or an intermediate transfer belt provided in the image forming apparatus. . The rotational torque of the electric motor is transmitted to the rotational input shaft of the image carrier through torque transmission means such as a plurality of drive gears and drive belts connected to the output shaft of the electric motor.
By the way, the cause of failure of the image forming apparatus or the occurrence of abnormal operation includes failure of the motor itself and failure of the torque transmitting means (such as poor engagement of the drive gear and slipping of the drive belt). Conventionally, in the image forming apparatus, regarding the failure of the motor, an output signal of a rotation sensor such as an encoder or a photo interrupter attached to the output shaft of the motor is fed back to a computer or the like to monitor the rotation state of the motor. (Refer to the description column of the prior art in Patent Document 1).
Japanese Patent Laid-Open No. 06-095490

  However, in the above conventional method of directly detecting the rotation state by the rotation sensor attached to the output shaft of the motor, even if the failure of the motor can be detected, the engagement of the drive gear or the drive belt There is a problem that a failure or failure of the torque transmission means such as slippage cannot be detected. Of course, the rotation input shaft of the image carrier is provided with the rotation sensor for detecting the rotation state of the rotation input shaft, and by monitoring the rotation state of the image carrier, the failure of the electric motor or the torque transmission means Although it is possible to detect a malfunction, it may be difficult to attach the rotation sensor to the rotation input shaft of the image carrier due to a space problem. Further, even if the rotation sensor can be attached to the rotation input shaft of the image carrier, for example, a support roller (a driving roller, a driven roller, etc.) that rotatably supports an intermediate transfer belt (an example of an image carrier) ) And the intermediate transfer belt cannot be detected. Therefore, in the conventional method, a failure or malfunction (such as malfunction or abnormal operation) that occurs in a drive system device (corresponding to an image carrier drive unit) such as the electric motor, the torque transmission unit, or the support roller is detected. It may not be possible.

In the conventional method, a rotation sensor such as an encoder must be provided inside the image forming apparatus only for directly detecting the rotation state of the drive system device. Further, it is necessary to provide a new input port for receiving an output signal from the rotation sensor as a feedback signal, a new signal converter such as an A / D converter, a new processing circuit, or the like. However, newly installing these electrical devices and circuits will lead to an increase in the number of parts and the number of parts to be installed, leading to an increase in manufacturing costs, and the use of parts placement space or effective use of input / output ports. It is not preferable also from a viewpoint.
Japanese Patent Application Laid-Open No. 2005-228561 discloses a method for determining whether or not the toner stirring roller in the developing device is rotating in accordance with a change in the output level of a toner sensor provided in the developing device. In this method, even if it is possible to determine whether or not the toner stirring roller is rotating, whether or not there is a failure or malfunction of the drive system device (motor, torque transmission means, support roller, etc.) that rotates the image carrier. Cannot be judged.
Therefore, the present invention has been made in view of the above circumstances, and the object of the present invention is to provide an electric motor and torque transmission without providing unnecessary new parts or the like in order to detect a failure of the drive system device. Provided is an image forming apparatus capable of accurately detecting the drive state of the drive system device without failing to detect a failure or failure occurring in the drive system device such as a means or a support roller of an image carrier. There is.

In order to achieve the above object, the present invention provides a reflection during driving in a non-image carrying portion on an image carrier such as an intermediate transfer belt during drive control of an image carrier drive means such as a motor by a drive control means such as a motor driver. Either or both of the comparison between the fluctuation rate of the light quantity and the preset fluctuation rate of the reflected light quantity at the stop time and the comparison between the average value of the reflected light quantity at the time of driving and the preset average value of the reflected light quantity at the stop time And the driving state of the image carrier driving means is determined based on the comparison result .
By configuring the present invention in this way, it is possible to reliably detect failure factors such as abnormal rotation of torque transmission means such as motors and drive gears, and slipping and vibration occurring between the intermediate transfer belt and the support roller. As a result, it is possible to accurately determine the driving state of the image carrier driving means, that is, whether the image carrier driving means is in a failure state or a normal state. As a specific example of the image carrier driving means, in addition to the motor (electric motor), for example, an output torque (rotational drive torque) of a motor for rotating the image carrier is applied to the rotation input shaft of the image carrier. A torque transmission means such as a driving gear and a driving belt for transmission, an instruction roller such as a driving roller and a driven roller for supporting an intermediate transfer belt which is an example of an image carrier, and the like are conceivable.

According to the present invention, the determination as to whether or not the image carrier driving means is out of order is a variation rate or average value of the reflected light amount during driving continuously measured from a non-image carrier on the image carrier, or Based on both. Thereby, for example, by setting (storing) the threshold value of the variation rate or the average value in advance, the image carrier driving means is compared by comparing the variation rate or average value of the reflected light amount during driving with the threshold value. The drive state can be determined more accurately. In this case, it is desirable to provide driving reflected light amount storage means for storing the driving reflected light amount.
The determination as to whether or not the image carrier driving means has failed may be performed by, for example, measuring the amount of reflected light (stop) continuously measured from the non-image carrier on the image carrier in advance during stop control of the image carrier driving means. Comparison between the fluctuation rate of the reflected light amount during driving and the fluctuation rate of the reflected light amount during driving, and the comparison between the average value of reflected light amount during stop and the average value of reflected light amount during driving, or both You may perform based on a comparison result. In this case as well, it is desirable to provide stop reflected light amount storage means for storing the stop reflected light amount measured in advance.
Here, it is desirable that the reflected light amount during driving is measured continuously for a certain period after the drive control of the image carrier driving means by the drive control means is started. As a result, even if the image carrier driving means is driven to perform image forming processing in the image forming apparatus, the non-image carrier before the toner image visualized on the image carrier is carried. The amount of reflected light can be measured.

  As a specific example of the means for measuring the amount of reflected light at the time of driving or stopping (reflected light measuring means), the amount of reflected light from a visualized image carried on the image carrier is measured and visualized. In order to detect the density of the printed image, it is conceivable to use an image density detecting means such as a density sensor provided in advance in the image forming apparatus. This makes it possible to use the existing density sensor to measure the reflected light amount at the time of driving and the reflected light amount at the time of stop, so that a new part or the like is required for detecting a failure of the image carrier driving means. Without being provided as described above, it is possible to detect the driving state of the image carrier driving means.

As described above, according to the present invention, the fluctuation rate of the reflected light amount at the time of driving in the non-image bearing portion on the image carrier measured by the reflected light amount measuring unit during the drive control of the image carrier driving means by the drive control unit Comparison is made by comparing either or both of the comparison with the preset fluctuation rate of the reflected light amount at stop and the average value of the reflected light amount at the time of driving and the preset average value of the reflected light amount at stop. Since it is configured to determine the driving state of the image carrier driving means based on the result , a malfunction such as a rotation abnormality of a motor or a driving gear or a slip or vibration generated between an intermediate transfer belt or the like and a support roller. It is possible to detect the factor reliably, and as a result, it is possible to accurately determine the driving state of the image carrier driving means, that is, whether the image carrier driving means is in a failure state or a normal state. Is possible That.
As a specific example of the reflected light measuring means, an image forming apparatus is used in advance to measure the amount of reflected light from a visualized image carried on the image carrier and detect the density of the visualized image. By using the image density detecting means such as the provided density sensor, it is possible to measure the reflected light amount at the time of driving and the reflected light amount at the time of stopping without providing new parts more than necessary.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
1 is a schematic diagram for explaining the outline of the image forming unit of the image forming apparatus according to the embodiment of the present invention, FIG. 2 is a schematic diagram for explaining the schematic configuration of the image forming unit, and FIG. 3 is an intermediate transfer belt. FIG. 4 is a block diagram illustrating a schematic configuration of a drive control unit that drives and controls a drive system device such as a motor that rotates and drives, and FIG. 4 is a graph that plots the measured reflected light amount during driving and reflected light amount when stopped; FIG. 5 is a flowchart illustrating an example of a procedure of failure determination processing executed by the CPU of the drive control unit.

First, the schematic configuration and basic operation of the image forming unit 100 of the image forming apparatus according to the embodiment of the present invention will be briefly described with reference to the schematic diagrams of FIGS. 1 and 2. The image forming apparatus according to this embodiment is described as a tandem color copier, but this is merely an example of the image forming apparatus. Other examples of the image forming apparatus include, for example, a monochrome copying machine, a printer apparatus, a facsimile apparatus, or a complex machine having these functions. The present invention can also be applied to such an image forming apparatus.
As shown in FIG. 1, the image forming unit 100 is roughly divided into an image forming unit 10 (10a to 10d) corresponding to each color of YMCK, an intermediate transfer belt 3 (corresponding to an image carrier), and the intermediate. A driving roller 9a and driven rollers 9b and 9c for rotatably supporting the transfer belt 3, a motor 5 connected to the driving roller 9a via a torque transmission means 1 such as a driving gear or a driving belt, and the motor 5 or A drive control unit 6 having a motor driver 62 (see FIG. 3) which is an example of a drive control means for driving and controlling the torque transmission means 1 and the drive roller 9a via the motor 5, and a density sensor 8 (amount of reflected light) And a secondary transfer roller 4 for transferring the toner image transferred onto the outer peripheral surface of the intermediate transfer belt 3 to the transfer paper S. There. In the following description, the motor 5, the drive roller 9a and driven rollers 9b and 9c driven by the motor 5, and the torque transmission means 1 are collectively referred to as drive system devices (an example of image carrier drive means). ).

Next, a schematic configuration of the Y-color image forming unit 10a will be described with reference to FIG. The other color image forming units 10b to 10d are configured in the same manner as the Y color image forming unit 10a, and thus the description thereof is omitted here.
As shown in FIG. 2, the image forming unit 10a includes a photosensitive drum 15a carrying an electrostatic latent image, a charging device 11a for uniformly charging the surface on the photosensitive drum 15a around the photosensitive drum 15a, An exposure device 12a for forming an electrostatic latent image by irradiating the surface of the photosensitive drum 15a with a laser beam, and a developing device for forming a toner image on the surface of the photosensitive drum 15a by attaching toner to the electrostatic latent image. 13a, an intermediate transfer roller 2a for transferring the developed toner image onto the intermediate transfer belt 3, a neutralization device for neutralizing residual charges remaining on the surface of the photosensitive drum 15a after the toner image transfer, and a cleaning for removing residual toner. The apparatus 14a etc. are arrange | positioned and comprised.

As shown in FIGS. 1 and 2, the intermediate transfer belt 3 is disposed below the photosensitive drum 15. The intermediate transfer belt 3 is configured as a loop-like endless belt by being stretched by a driving roller 9a and driven rollers 9b and 9c. A rotation input shaft (not shown) of the drive roller 9a is connected to an output shaft of the motor 5 via torque transmission means 1 such as a drive gear or a drive belt. Therefore, when the motor 5 is driven by the drive controller 6, the rotational drive torque of the motor 5 is transmitted from the output shaft of the motor 5 to the rotational input shaft of the drive roller 9a via the torque transmission means 1. Thus, the drive roller 9a is rotationally driven in a predetermined direction. Thus, the intermediate transfer belt 3 rotatably supported by the drive roller 9a and the driven rollers 9b and 9c is rotationally driven in the direction of arrow P in FIG. In this manner, the motor 5 for rotating the intermediate transfer belt 3 and the drive system equipment such as the torque transmission means 1 such as the drive roller 9a and the driven rollers 9b and 9c correspond to the image carrier drive means.
The present invention relates to failure determination for determining whether or not these drive system devices have failed or malfunctioned. A specific processing procedure for determining the failure of the drive system device will be described in detail later using a flowchart. The failure or failure of the drive system device includes not only the failure of the motor 5 itself, but also the engagement of the drive gear or the engagement failure of the drive belt, which is an example of the torque transmission means 1, the drive roller 9a, For example, poor adhesion of the driven rollers 9b and 9c.

  The intermediate transfer rollers 2 (2a to 2d) corresponding to the photosensitive drums 15 are disposed at positions facing the photosensitive drums 15 of the respective colors with the intermediate transfer belt 3 interposed therebetween. The intermediate transfer roller 2 is applied with a transfer bias having a polarity opposite to the toner charging polarity in order to transfer the toner image carried on the surface of the photosensitive drum 15 onto the intermediate transfer belt 3. As a result, the YMCK color toner images (corresponding to the visualized images) formed on the photosensitive drums 15 of the respective colors are sequentially superimposed on the outer peripheral surface of the intermediate transfer belt 3, and the outer peripheral surface of the intermediate transfer belt 3. A full color toner image is carried (formed).

The intermediate transfer belt 3 and the toner image carried on the outer peripheral surface of the intermediate transfer belt 3 are conveyed in the direction P in FIG. 1 when the driving roller 9a is rotationally driven by the motor 5. The toner image conveyed in the P direction is disposed downstream of the intermediate transfer belt 3 in the image forming unit 10a after the conveying direction is once deflected in the Q direction (see FIG. 1) by the drive roller 9a. The toner density is detected by the provided density sensor 8. The density value (density signal) detected by the density sensor 8 is sent to an image processing unit (not shown) and used for a known density correction process executed by the image processing unit. Normally, in an image forming apparatus such as a color copying machine, the density correction process is performed. Therefore, the density is set at a position where the density of the toner carried on the surface of the intermediate transfer belt 3 or the photosensitive drum 15 can be detected. A sensor 8 is provided.
The concentration sensor 8 includes at least a light emitting diode 8a such as an LED and a light receiving diode 8b that outputs an electric signal (current or voltage) corresponding to the amount of light input. The toner density of the toner image carried on the surface of the intermediate transfer belt 3 is measured by the light receiving diode 8b receiving the amount of light reflected from the light emitting diode 8a toward the intermediate transfer belt 3. It is obtained based on the reflected light quantity. A specific example of such a density sensor 8 is an optical sensor such as a diffuse reflector type or a specular reflection type photo reflector.
In the present embodiment, the density sensor 8 detects not only the density of the toner image on the intermediate transfer belt 3 but also the toner image on the intermediate transfer belt 3 during the drive control of the motor 5. A sensor that continuously measures the amount of reflected light (hereinafter referred to as the amount of reflected light during driving) reflected from the surface of the intermediate transfer belt 3 before transfer (corresponding to a non-image carrying portion) or stop control of the motor 5 Sometimes, a sensor that continuously measures the amount of reflected light (hereinafter referred to as the amount of reflected light at stop) reflected from the surface of the intermediate transfer belt 3 (corresponding to a non-image carrying portion) in a state where the toner image is not carried. Used. The drive reflected light amount and the stop reflected light amount measured by the density sensor 8 are sent to the drive control unit 6, and a failure of a drive system device such as the motor 5, the torque transmission means 1, or the drive roller 9a, which will be described later. It is used for judgment processing. Of course, an optical sensor similar to the density sensor 8 provided separately from the density sensor 8 may be provided, and the reflected light amount at the time of driving and the reflected light amount at the time of stop may be measured by the optical sensor. The reflected light amount such as the reflected light amount during driving measured by the density signal is output as an electrical signal such as a voltage signal. In the present embodiment, the reflected light amount during driving is simply used for the sake of simplicity. This is referred to as the amount of light or the amount of reflected light when stopped.
After the toner image carried on the intermediate transfer belt 3 passes through the density sensor 8, the toner image faces the driven roller 9c located further downstream in the rotational direction P of the density sensor 8. Then, the toner image is transferred onto the transfer sheet S by the secondary transfer roller 4 disposed in this manner. The transfer sheet S on which the toner image is transferred in this way is then fixed on the recording sheet by a fixing device (not shown).

Next, the schematic configuration of the drive control unit 6 will be described with reference to the block diagram of FIG.
The drive control unit 6 includes an input port 61 for receiving the drive reflected light amount and the stop reflected light amount output from the density sensor 8, and a motor driver 62 (drive control means) for controlling the drive and stop of the motor 5. An example), a data storage area 63a for storing the driving reflected light amount and the stop reflected light amount input from the input port 61, and a program storage area 63b for storing a program for executing a failure determination process described later. And a storage unit 63 (an example of a reflected light amount storage device at the time of driving and an example of a reflected light amount storage device at the time of stoppage), a RAM 64 used for developing or calculating predetermined data and the like, and a CPU 65 that controls the above-described units in an integrated manner A central processing unit).
The drive reflected light amount and the stop reflected light amount continuously measured by the density sensor 8 are input to the input port 61. The input reflected light amounts are sequentially stored in the data storage area 63a by the CPU 65. In FIG. 4, the number of measurement points (sampling points) when the reflected light amount at the time of driving and the reflected light amount at the time of stop are measured continuously every 2 ms for 200 ms, and the reflected light amount at the time of driving and the above described The plot data A of the reflected light amount at the time of driving and the plot data B of the reflected light amount at the time of stop when the output voltage of the density sensor 8 indicating the reflected light amount at the time of stop is the vertical axis are shown.

Next, referring to the plot data A and B of FIG. 4, an example of the procedure of the drive system device failure determination process executed by the CPU 65 of the drive control unit 6 will be described using the flowchart of FIG.
The failure determination processing described here determines whether the drive system device has failed or malfunctioned by comparing the drive reflected light amount measured by the density sensor 8 with a predetermined threshold value. It is. Therefore, it is necessary to determine the threshold value in advance. As the threshold value, a threshold value set in advance by the manufacturer or user of the image forming apparatus can be used. In the present embodiment, the above-mentioned stop reflected light amount measured in advance by the density sensor 8 is used as the threshold value. A processing example used as will be described. In the figure, S10, S20,... Indicate process procedure (step) numbers, and the process starts from step S10.
First, in step S <b> 10, the CPU 65 determines whether a motor drive signal for driving the motor 5 is input to the drive control unit 6. This determination is output from, for example, a main control unit (not shown) that performs overall control of the image forming apparatus in response to an image formation instruction (copy start, etc.) by a user from an operation unit (not shown) provided in the image forming apparatus. This is performed by detecting whether or not the motor drive signal is input to the drive control unit 6. If the image forming apparatus has a network printer function or a network FAX function, the determination in step S10 is based on whether the motor drive signal is in accordance with an image forming instruction from an information processing apparatus or facsimile apparatus connected to the network. This is performed depending on whether or not an input is made to the drive control unit 6. The determination in step S10 is repeatedly performed until the input of the motor drive signal is confirmed.

If it is determined in step S10 that the motor drive signal has been input, then in step S20, it is determined whether or not the stop reflected light amount is stored in the data storage area 63a (FIG. 3). If it is determined that the stop-time reflected light amount is stored in the data storage area 63a, the process proceeds to step S30. If it is determined that the information is not stored, the process proceeds to steps S40 to S42, the process of measuring the reflected light amount at stop (S40), and the process of storing the measured reflected light amount at stop in the data storage area 63a (S41). ), Processing for calculating an average value Nb of the measured reflected light amount at stop (see Table 1 below) (S42), a maximum measured value Nbmax of the reflected light amount at stop when the average value Nb is used as a reference, and A process (S43) for calculating the fluctuation rate of the minimum measured value Nbmin (vs. the average value fluctuation ratio in Table 1) is performed. Thereafter, the process proceeds to step S50. The processes in steps S40 to S43 are the same as the processes in steps S60 to S90 described later except that the reflected light amount at the time of stop is measured in the stop state of the intermediate transfer belt 3 in step S41. Refer to the description of the processing in steps S60 to S90.
When the process proceeds to step S30, the CPU 65 determines here whether or not it is necessary to update the stop reflected light amount stored in the data storage area 63a.
In the present embodiment, a failure of a drive system device such as a motor is determined by performing threshold determination processing (S90) to be described later on the stop reflected light amount and the operating reflected light amount, which are threshold values. The amount of reflected light during operation tends to decrease with time due to deterioration or contamination of the light emitting diode 8a built in the sensor 8. Nevertheless, if the reflected light amount at stop used as the threshold value remains constant, the difference between the measured reflected light amount during operation and the reflected light amount at stop increases as time passes. , This will hinder the threshold judgment processing (S90) described later. For this purpose, in step S30, a process for determining whether or not the reflected light amount at the time of stop is updated is performed. Note that this determination is made, for example, based on whether or not a fixed non-update time has elapsed since the previous update. Of course, the reflected light amount during driving may be updated at a timing arbitrarily determined by the user.
If it is determined in step S30 that it is not necessary to update the amount of reflected light at stop, the process proceeds to step S50. If it is determined that the update is necessary, the process proceeds to steps S40 to S43, and after the process of measuring the amount of reflected light at the stop is performed, the process proceeds to step S50. In this case, the storage processing (processing for storing the measured stop reflected light amount in the data storage area 63a) in step S41 overwrites and stores the pre-update stop reflected light amount stored in the data storage area 63a. This process updates the amount of reflected light at stop. As described above, the CPU 65 that executes the processes of steps S40 to S43 after it is determined that the update is necessary in step S30 corresponds to the reflected light amount update unit at the time of stop.

  When the process proceeds to step 50, here, the CPU 65 transfers the motor drive signal inputted thereto to the motor driver 62, thereby starting drive control of the motor 5 by the motor driver 62. As a result, when the motor 5 is rotationally driven, the rotational driving torque of the motor 5 is transmitted to the driving roller 9a via the torque transmitting means 1 (FIG. 1), and the driving roller 9a and the driven rollers 9b, 9c are transmitted. The supported intermediate transfer belt 3 is driven. At this time, if the motor 5 or the torque transmission means 1 or the driving roller 9a and the driven rollers 9b and 9c have some trouble or malfunction, the intermediate transfer belt 3 is not driven normally. If the motor 5 is broken or if the torque transmission means 1 is broken or defective, the intermediate transfer belt 3 stops or operates abnormally, and the drive roller 9a and the driven rollers 9b and 9c are, for example, If the intermediate transfer belt 3 is attached in a direction in which the tension is weakened, the intermediate transfer belt 3 may slip or vibrate, or the belt may idle.

In the next step S60, as soon as the drive control of the motor 5 is started, the CPU 65 executes processing for causing the density sensor 8 to measure the amount of reflected light from the outer peripheral surface of the intermediate transfer belt 3. Since this process is executed immediately after the motor 5 is driven and controlled, the amount of reflected light on the outer peripheral surface of the intermediate transfer belt 3 in a state where the toner image has not yet been transferred, that is, on the intermediate transfer belt 3. The reflected light amount (driving reflected light amount) of the non-image forming unit is measured.
Specifically, in the process of step S60, a constant voltage is applied to the light emitting diode 8a constituting the concentration sensor 8 for 200 ms (corresponding to a certain period) immediately after the drive control of the motor 5 is started. Then, the output voltage of the light receiving diode 8b constituting the density sensor 8 is read every 2 ms. Accordingly, the reflected light quantity of 100 measurement points (sampling points) is continuously measured from the outer peripheral surface of the intermediate transfer belt 3 by the density sensor 8 every 2 ms for 200 ms. Note that the plot data A shown in FIG. 4 indicates the amount of reflected light during driving measured as described above.

When the driving reflected light amount is continuously measured every 2 ms, the continuously measured driving reflected light amount is sequentially stored in the data storage area 63a (S70). The drive reflected light amount thus stored is then calculated in step S80 as an average value Na (see Table 1) of drive reflected light amounts at all the measurement points, and then in step S90 the average value is calculated. Variation rate (maximum variation ratio in Table 1) of the maximum measured value Namax and the minimum measured value Namin of the reflected light amount at the time of driving when using Na as a reference, and the average value Nb of the reflected light amount at the time of stop (calculated in S42) The attenuation ratio of the average value Na of the reflected light amount during driving with reference to the above is calculated. Each calculated value calculated in this way is stored in the data storage area 63a as tabulated data as shown in Table 1 below.

Subsequently, in step S100, based on the driving reflected light quantity measured in step S60, it is determined whether or not the driving state of the drive system device, that is, whether or not a failure or failure has occurred in the drive system device. Specifically, when the motor 5 is controlled to stop when the fluctuation rate and average value Na of the reflected light amount during driving obtained by the processes of steps S60 to S80 are the same as the processes of steps S60 to S80. Is compared with the fluctuation rate and average value Nb of the reflected light quantity at the time of stop, which is measured in advance and stored in the data storage area 63a, and the drive system device such as the motor 5 is based on the comparison result. The driving state is determined.
When determining the driving state of the drive system device based on the fluctuation rate, paying attention to the fact that the fluctuation of the reflected light quantity at the time of stop is smaller than the fluctuation of the reflected light quantity at the time of driving, when the motor is stopped in Table 1. This is carried out by comparing the fluctuation ratio with respect to average value and the fluctuation ratio with respect to average value when the motor is driven. As can be understood from Table 1 above, in this case, the ratio of fluctuation in the amount of reflected light at the time of stop is 99.5% to 100.5%, so that the average value Nb is about ± 0.5%. Only increase or decrease. On the other hand, the fluctuation ratio of the reflected light amount during driving to the average value is 97.35% to 102.65%, and the fluctuation ratio (100 ± 2.65%) is relatively large. The reason why the fluctuation rate of the reflected light quantity at the time of driving is large is that the surface state of the intermediate transfer belt 3 is not uniform in the rotation direction, and therefore when the intermediate transfer belt 3 is driven by the rotation drive of the motor 5, the intermediate transfer belt 3 is driven. 3 because the amount of reflected light from the outer peripheral surface is not constant compared to when the intermediate transfer belt 3 is stopped. Therefore, when the motor drive control is performed by the motor driver 62, the intermediate transfer belt 3 is normal if the ratio of the reflected light amount during driving to the average value variation ratio is larger than the ratio of the reflected light amount during stop to the average value variation ratio. It is determined that it is driving. Further, if the ratio of fluctuation of the reflected light amount during driving to the average value fluctuation ratio is smaller than or substantially the same as the ratio of fluctuation of the reflected light amount during stoppage, the intermediate transfer belt 3 is stopped due to a malfunction of the drive system device or the like. It can be determined that the vehicle is idling, that is, it can be determined that the drive system device has failed. Each reflected light amount input to the drive control unit 6 may be quantized. Considering a quantization error caused by the quantization, the determination of the drive state of the drive system device is performed by the reflection at stop. It is preferable to compare the fluctuation ratio of the reflected light quantity with respect to the average value based on the fluctuation ratio obtained by adding the quantization error to the fluctuation ratio of the light quantity to the average value.
Even if the intermediate transfer belt 3 is driven, there is a case where the intermediate transfer belt 3 is not driven normally and an abnormal operation such as slipping occurs due to a malfunction in the drive system device. is there. Such an abnormal operation can be detected by appropriately changing the threshold value. That is, it is considered that the fluctuation of the reflected light quantity when the intermediate transfer belt 3 slips is larger than the fluctuation of the reflected light quantity at the stop, but smaller than the fluctuation of the reflected light quantity at the time of driving. Accordingly, in this case, based on the ratio of fluctuation in the amount of reflected light during driving to the average value fluctuation ratio, the average value fluctuation ratio is compared with the appropriately changed threshold value, and abnormal operation such as slippage of the intermediate transfer belt 3 is detected. By detecting it, it becomes possible to determine the drive state of the drive system device.

When determining the driving state of the drive system device based on the average value of the reflected light amount, the average value Na (Table 1) of the reflected light amount at the time of driving is smaller than the average value Nb of the reflected light amount at the time of stop. Paying attention to this, it is performed by comparing the average values when the motor is stopped and when the motor is driven. In this case, from Table 1 above, since the average value Nb of the reflected light amount at the time of stop is 2.00 [V], the average value Na of the reflected light amount at the time of driving is 1.89 [V]. When the motor drive control is performed by the motor driver 62, the intermediate transfer belt 3 is normally driven if the average value Na of the reflected light amount during driving is smaller than the average value Nb of the reflected light amount during stop. It is judged. Further, if the average value Na of the reflected light amount at the time of driving is smaller than or substantially the same as the average value Nb of the reflected light amount at the time of stopping, it is determined that the intermediate transfer belt 3 has stopped for some reason, that is, It can be determined that the drive system device has failed. The difference in the average value between when the motor is driven and when it is stopped is caused by the fact that the amount of light that is irregularly reflected on the outer peripheral surface of the intermediate transfer belt 3 is greater during driving than when the intermediate transfer belt 3 is stopped. It is. Even when the drive state of the drive system device is determined based on the average value of the reflected light amount, the drive system device detects an abnormal operation such as slipping of the intermediate transfer belt 3 by appropriately changing the threshold value. Can be accurately determined.
If it is determined in step S100 that the drive system device is faulty, an error display or the like indicating that the drive system device is faulty is performed in step S110, and it is determined that the drive system device is normal. , A series of failure determination processing ends.
By performing the failure determination process in this way, it is possible to reliably detect the failure factor of the drive system equipment such as the motor 5, the torque transmission means 1, or the drive roller 9a, the driven rollers 9b and 9c. As a result, it is possible to accurately determine the drive state of the drive system device, that is, whether the drive system device is in a failure state or a normal state.

FIG. 2 is a schematic diagram illustrating an outline of an image forming unit of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a schematic configuration of an image forming unit. FIG. 3 is a block diagram illustrating a schematic configuration of a drive control unit that drives and controls a drive system device such as a motor that rotationally drives the intermediate transfer belt. The graph figure which plotted and graphed the reflected light amount at the time of a drive, and the reflected light amount at the time of a stop. The flowchart which shows an example of the procedure of the failure determination process performed by CPU of a drive control part.

Explanation of symbols

1. Torque transmission means (an example of image carrier driving means)
2 ... Intermediate transfer roller 3 ... Intermediate transfer belt 4 ... Secondary transfer roller 5 ... Motor (an example of image carrier driving means)
6 ... Drive control unit 8 ... Density sensor (an example of reflected light amount measuring means, image density detecting means)
9a: Driving roller (an example of image carrier driving means)
9b, 9c ... driven roller (an example of image carrier driving means)
DESCRIPTION OF SYMBOLS 10 ... Image forming unit 61 ... Input port 62 ... Motor driver (an example of a drive control means)
63... Data storage unit (an example of the reflected light amount storage means during driving and the reflected light amount storage means during stop)
64 ... RAM
65 ... CPU

Claims (6)

Image carrier driving means for rotationally driving one or a plurality of image carriers carrying a visualized image;
Drive control means for performing drive control of the image carrier drive means;
A reflected light amount measuring means for measuring a reflected light amount of light irradiated on the image carrier, and an image forming apparatus comprising:
During the drive control of the image carrier driving means by the drive control means, the fluctuation rate of the reflected light quantity during driving in the non-image carrying part on the image carrier measured by the reflected light quantity measuring means and a preset stop time One or both of the comparison with the fluctuation rate of the reflected light amount and the comparison between the average value of the reflected light amount at the time of driving and the preset average value of the reflected light amount at the time of stop are performed, and the image is based on the comparison result. An image forming apparatus comprising drive state determination means for determining a drive state of a carrier drive means. A driving reflected light amount storage means for storing the driving reflected light amount continuously measured by the reflected light amount measuring means during drive control of the image carrier driving means;
The drive state determination means compares the fluctuation rate of the reflected light quantity during driving stored in the reflected light quantity storage means during driving with the fluctuation rate of the reflected light quantity during stop, and is stored in the reflected light quantity storage means during driving. One or both of the comparison of the average value of the reflected light amount at the time of driving and the average value of the reflected light amount at the time of stop is performed, and the driving state of the image carrier driving means is determined based on the comparison result. The image forming apparatus according to claim 1. When the stop control of the image carrier driving means, either one of the change rate及beauty average value of the stop-state reflected light in the non-image bearing portion of the continuously measured the image carrier by the reflected light amount measuring means Or a stop reflected light amount storage means for storing both in advance,
The drive state determination means compares the fluctuation rate of the stop reflected light quantity stored in the stop reflected light quantity storage means with the fluctuation rate of the drive reflected light quantity, and is stored in the stop reflected light quantity storage means. In addition, one or both of the comparison between the average value of the reflected light amount at the time of stop and the average value of the reflected light amount at the time of driving is performed, and the driving state of the image carrier driving means is determined based on the comparison result. The image forming apparatus according to claim 1 or 2.   The image forming apparatus according to claim 3, further comprising a stop reflected light amount update unit that updates the stop reflected light amount stored in the stop reflected light amount storage unit.   5. The reflected light amount during driving is measured by the reflected light amount measuring means continuously for a certain period after the drive control of the image carrier driving means by the drive control means is started. The image forming apparatus according to any one of the above.   As the reflected light measuring means, provided in advance in the image forming apparatus in order to detect the density of the visualized image by measuring the amount of reflected light from the visualized image carried on the image carrier. 6. The image forming apparatus according to claim 1, wherein the image density detecting unit is used.

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