JP6891435B2 - Image forming device and image forming program - Google Patents

Description

The present invention relates to an image forming apparatus and an image forming program.

Conventionally, an image forming apparatus including a forming portion for forming a toner image on an endless belt-shaped image holder has been known. In the image forming apparatus, an endless belt-shaped image holder may come into contact with, for example, a rotating body used for transferring a toner image. If a long time elapses while the image holder is in contact with the rotating body or the like, the image holder may be deformed following the outer shape of the rotating body or the like.

Deformation of the image retainer may affect the density of the toner image formed on the image retainer. Therefore, for example, the density of the toner image formed on the endless belt-shaped image holder is detected based on the amount of reflected light of the image holder, and even if the image holder is deformed, the effect of the deformation is affected. An image forming apparatus for detecting the density of a toner image while suppressing the above is disclosed (see, for example, Patent Document 1). In this technology, the density of the toner image is detected while suppressing the influence of deformation of the image holder by setting the detection length to a distance longer than the length of the deformation region in the image holder along the moving direction of the image holder. ing.

Japanese Unexamined Patent Publication No. 2011-048077

By the way, when a toner image is formed on the image holder while the image holder is deformed, the density of the toner image is higher at the portion where the image holder is deformed than at the portion where the image holder is not deformed. Fluctuations appear remarkably and become apparent as deterioration of image quality.
INDUSTRIAL APPLICABILITY The present invention can suppress the deterioration of image quality caused by the deformation of the image holder as compared with the case of detecting the density of the toner image formed on the image holder while suppressing the influence of the deformation on the image holder. An object of the present invention is to provide an image forming apparatus capable of forming an image and an image forming program.

In order to achieve the above object, the image forming apparatus of the first aspect includes an endless belt-shaped image holder, a forming portion that forms a toner image on the image forming surface of the image holder, and an image of the image holder. An image formation exclusion region includes a detection unit that detects a deformed portion that affects image quality deterioration on the formed surface, and an image formation exclusion region that detects the deformed portion when the detection unit detects the deformed portion. set, predetermined given time during the time required to return to the state in which the deformed portion does not affect the image quality deterioration, excluding the image formation exclusion area set as said detected deformed portion by the detecting unit area In addition, the forming portion is controlled so that the toner image is formed, and when the deformed portion is not detected by the detecting portion when the predetermined time elapses, the deformed portion does not affect the image quality deterioration. Control to cancel the setting of the image formation exclusion region and control the forming portion so that the toner image is formed in the region including the released image formation exclusion region as the portion where the deformation is restored. It has a part and.

In the second aspect , in the image forming apparatus of the first aspect , the deformed portion is a portion in which the fluctuation amount of the belt surface displacement of the endless belt-shaped image holder exceeds a predetermined fluctuation amount. ..

The third aspect is that in the image forming apparatus of the first aspect , when the deformed portion forms a toner image having a predetermined density in the forming portion, the density of the formed toner image becomes the predetermined density. On the other hand, this is the part where the concentration fluctuation exceeds the predetermined fluctuation amount.

The fourth aspect is the image forming apparatus according to any one aspect of the third embodiment from the first embodiment, the deformed portion, the amount of deformation deformation amount relative to the from the state before the deformation is predetermined It is a part beyond.

The fifth aspect is the image forming apparatus according to any one aspect of the fourth embodiment from the first embodiment, the control unit is in a region other than the deformed portion to said deformed portion by the detecting unit is no longer detected The forming portion is controlled so that the toner image is formed.

The image forming program of the sixth aspect detects a deformed portion of the image forming surface of the endless belt-shaped image holder on which the toner image is formed, which affects the deterioration of image quality, and the deformed portion where the deformation occurs is used. when it is detected, and set the detected said deformed portion to the image forming exclusion area, a predetermined given time between, said detected variations as time to return to the state in which the deformed portion does not affect the image quality deterioration The toner image is controlled to be formed in a region excluding the image formation exclusion region set as a portion, and when the deformed portion is not detected after the predetermined time has elapsed, the deformed portion has an image quality. When the state is restored to a state that does not affect the deterioration, the setting of the image formation exclusion region is released, and the toner image is controlled to be formed in the region including the released image formation exclusion region as the portion where the deformation is restored. Let the computer perform the processing including.

According to the first aspect and the sixth aspect , the toner generated by the deformation of the image holder is compared with the case where the density of the toner image formed on the image holder is detected while suppressing the influence of the deformation on the image holder. It has the effect of suppressing deterioration of image quality.

According to the second aspect , deterioration of the image quality due to the density fluctuation of the toner image can be suppressed as compared with the case where the portion where the displacement fluctuation of the belt surface exceeding the predetermined fluctuation amount is not used as the deformed portion. , Has the effect.

According to the third aspect , the deterioration of the image quality due to the density fluctuation of the toner image can be suppressed as compared with the case where the portion where the density fluctuation exceeding the predetermined fluctuation amount is not made into the deformed portion. Has.

According to the fourth aspect , deterioration of image quality due to the deformed portion can be suppressed as compared with the case where the portion exceeding the predetermined amount of deformation based on the state before the deformation occurs is not regarded as the deformed portion. Has an effect.

According to the fifth aspect , there is an effect that the deterioration of the image quality caused by the deformation of the image holder can be further suppressed as compared with the case where the toner image is formed regardless of the presence or absence of the deformed portion.

It is a schematic side view which shows an example of the main part structure of an image forming apparatus. It is a schematic diagram provided for the explanation of the main part structure of a transfer apparatus. It is a block diagram which shows an example of the structure of the image formation control part. It is an image figure which shows an example of the state which the contact habit occurs in the intermediate transfer belt. It is an image diagram which shows an example of the deformation region generated on the intermediate transfer belt. It is explanatory drawing of the transfer | transfer of a plurality of toner images to an intermediate transfer belt. It is an image figure which shows an example of the time characteristic that the deformation region of an intermediate transfer belt returns. It is an image figure which shows the state which developed the intermediate transfer belt on a plane. It is a flowchart which shows the processing flow of an image formation control program. It is a flowchart which shows an example of the flow of image formation processing. It is an image figure which shows an example of the state which a part of the deformed region of an intermediate transfer belt is restored.

Hereinafter, an example of the image forming apparatus according to the embodiment of the present invention will be described in detail with reference to the drawings. It should be noted that components and processes having the same function and function may be given the same code throughout the drawings, and duplicate explanations may be omitted as appropriate.

FIG. 1 shows a schematic side view showing a main configuration of an image forming apparatus 20 using the electrophotographic method according to the present embodiment. The image forming apparatus 20 is equipped with an image forming function that receives various data via a communication line (not shown) and performs color image forming processing based on the received data.

The case where the image forming apparatus 20 according to the present embodiment performs the color image forming process using four colors of yellow, magenta, cyan, and black will be described, but the colors used for the color image forming process are limited to four colors. It's not a thing. For example, the three colors of yellow, magenta, and cyan may be used, or a plurality of colors in which one or more different colors are added to the three colors of yellow, magenta, and cyan may be used.

Further, regarding the colors, each of yellow, magenta, cyan, and black will be described by notating them with alphabetic characters (color codes) of Y, M, C, and K. Further, when distinguishing each color of yellow, magenta, cyan, and black in the constituent elements of the image forming apparatus 20, the letters Y, M, C, and K (color codes) are added after the numbers. When it is not necessary to distinguish each color, the letters Y, M, C, and K (color code) after the number are omitted.

The image forming apparatus 20 includes a photoconductor 1, a charger 2, a laser output unit 3, a developer 4, and a primary transfer device 5. Each of the photoconductor 1, the charger 2, the laser output unit 3, the developing roll 34, the developing device 4, and the primary transfer device 5 is provided for each of the colors Y, M, C, and K.

The photoconductor 1 includes photoconductors 1Y, 1M, 1C, and 1K that rotate in the direction of arrow A in the drawing, and the charger 2 charges the surface of each photoconductor by applying a charging bias. It has 2M, 2C and 2K. The laser output unit 3 exposes the surface of the charged photoconductor 1 with exposure light modulated based on the image information of each color, and forms an electrostatic latent image on the photoconductor 1. Laser output units 3Y, 3M, 3C It has 3K. The developer 4 includes a developing roll 34, which is a developer holder that holds a developer (toner) of each color. The developer 4 includes developers 4Y, 4M, 4C, and 4K, and by applying a development bias to the development rolls 34Y, 34M, 34C, and 34K with a development bias power supply (not shown), electrostatic latency on the photoconductor 1 is obtained. The image is developed with toner of each color to form a toner image on the photoconductor 1. The primary transfer device 5 includes primary transfer devices 5Y, 5M, 5C, and 5K that transfer each color toner image on the photoconductor 1 to the intermediate transfer belt 6.

Further, the image forming apparatus 20 fixes the paper accommodating portion T for accommodating the paper P, the secondary transfer device 7 for transferring the toner image on the intermediate transfer belt 6 to the paper P, and the toner image transferred to the paper P. The fixing device 9 and the belt cleaner 8 for cleaning the toner remaining on the surface of the intermediate transfer belt 6 after transferring the toner image to the paper P are provided. Further, the image forming apparatus 20 includes a cleaner (not shown) for cleaning the surface of each photoconductor 1 and a static eliminator (not shown) for removing the residual charge on the surface of each photoconductor 1.

Further, in the present embodiment, the image forming apparatus 20 detects the position of the density sensor 60 that detects the density of the toner image transferred to the intermediate transfer belt 6 and the position of the intermediate transfer belt 6 that detects the density of the toner image. A sensor 61 is provided.

Furthermore, the image forming apparatus 20 includes an image forming control unit 40 that controls image formation as a control unit.

Next, an outline of the image forming operation in the image forming apparatus 20 shown in FIG. 1 will be described.

First, the original image information of the image forming target is output to the image forming apparatus 20 from a terminal device such as a personal computer (not shown) via a communication line (not shown). When the original image information is input to the image forming apparatus 20, the image forming apparatus 20 applies a charging bias to the charging device 2 to charge the surface of the photoconductor 1 to the negative electrode.

On the other hand, the original image information is input to the image formation control unit 40. The image formation control unit 40 decomposes the original image information into image data of each color of YMCK, and then outputs a modulation signal based on the image data of each color to the laser output unit 3 of the corresponding color. The laser output unit 3 outputs the laser beam 11 modulated according to the input modulation signal.

The modulated laser beam 11 irradiates the surface of the photoconductor 1. The surface of the photoconductor 1 is in a state of being charged to the negative electrode by the charger 2, and when the surface of the photoconductor 1 is irradiated with the laser beam 11, the charge of the portion irradiated with the laser beam 11 disappears and the photoconductor 1 is irradiated. An electrostatic latent image corresponding to the image data (each color of YMCK) included in the original image information is formed on the 1.

Further, the developing devices 4Y, 4M, 4C, and 4K of each color include toners colored in Y, M, C, and K and charged on the negative electrode, and a developing roll 34 for adhering each toner to the surface of the photoconductor 1.

When the electrostatic latent image formed on the photoconductor 1 reaches the developing device 4, a developing bias is applied to the developing roll 34 in the developing device 4 by a developing bias power supply (not shown). Then, the toners of each color held on the peripheral surfaces of the developing rolls 34Y, 34M, 34C, and 34K adhere to the electrostatic latent images of the photoconductors 1Y, 1M, 1C, and 1K, respectively, and the photoconductors 1Y, 1M, 1C, A toner image corresponding to the image data of each color of the original image information is formed in 1K.

Further, the rollers 12A, 12D, 12E, and the backup roll 7A of the secondary transfer device 7 are rotated by a motor (not shown), and the intermediate transfer belt 6 is conveyed to the gap formed by the primary transfer device 5 and the photoconductor 1. Then, the intermediate transfer belt 6 is pressed against the photoconductor 1. At this time, when the primary transfer bias is applied by the primary transfer device 5, the toner image of the image data of each color formed on the photoconductor 1 is transferred to the intermediate transfer belt 6. Therefore, by controlling the rotation of the rollers 12A, 7A, 12D, and 12E so that the transfer start positions of the toner images of each color to the intermediate transfer belt 6 are matched, the toner images of each color are superimposed to correspond to the original image information. The toner image is formed on the intermediate transfer belt 6.

In the photoconductor 1 on which the toner image is transferred to the intermediate transfer belt 6, deposits such as residual toner adhering to the surface of the photoconductor 1 are removed by a cleaner (not shown), and residual charges are removed by a static eliminator (not shown).

On the other hand, the secondary transfer device 7 includes a backup roll 7A for stretching the intermediate transfer belt 6 and a secondary transfer roll 7B, and the secondary transfer roll 7B comes into contact with the intermediate transfer belt 6 to contact the intermediate transfer belt 6 and the intermediate transfer belt 6 It rotates following the transport of.

Further, when the paper transport roller 13 is rotated by a motor (not shown), the paper P in the paper accommodating portion T is transferred to the backup roll 7A of the secondary transfer device 7 via the transport path 7J including the transport roller (not shown). It is conveyed to the gap between the roll 7B (hereinafter referred to as a roll pair).

When the paper P is pressed against the intermediate transfer belt 6 by the roll pair while facing the surface of the intermediate transfer belt 6 on which the toner image is formed, a secondary transfer bias is applied to the roll pair and the intermediate transfer belt is applied. The toner image corresponding to the original image information formed in No. 6 is transferred to the paper P. The toner image transferred onto the paper P is heated and melted by the fixing device 9 and fixed on the paper P.

Further, the intermediate transfer belt 6 on which the toner image is transferred to the paper P is removed by the belt cleaner 8 from deposits such as residual toner adhering to the surface.

As described above, the image corresponding to the original image information is formed on the paper P, and the image forming operation is completed.

FIG. 2 shows an example of the configuration of the secondary transfer device 7 of the image forming device 20 according to the present embodiment. The transfer operation to the paper P when the image is formed on the paper P by the secondary transfer device 7 shown in FIG. 2 will be described.

The secondary transfer device 7 is provided at a position facing the backup roll 7A with the intermediate transfer belt 6 sandwiched between the backup roll 7A which is conveyed while the intermediate transfer belt 6 is stretched together with the rollers 12A, 12D, and 12E by a motor (not shown). The secondary transfer roll 7B is composed of a secondary transfer power source 7G that supplies electric power (voltage and current) to the roll pair, and a detection unit 7H that detects the electric power (voltage and current) flowing through the roll pair. The detection unit 7H is an ammeter that detects the current flowing through the roll pair when a voltage is applied to the roll pair by the secondary transfer power supply 7G, and a roll pair when a current is applied to the roll pair by the secondary transfer power supply 7G. Includes an ammeter to detect voltage.

The voltage (or current) applied to the roll pair by the secondary transfer power source 7G can be adjusted by a transfer control unit (not shown). The positive electrode of the secondary transfer power source 7G is connected to the ground potential (for example, 0V) which is the reference potential (not shown), and the negative electrode is connected to the metal shaft 7D of the backup roll 7A. The detection unit 7H is also connected to the metal shaft 7D of the backup roll 7A.

The backup roll 7A is, for example, a rotatable roller having a diameter of 18 mm in which a solid rubber 7C is formed around a metal shaft 7D having a diameter of 14 mm. In solid rubber 7C, an ionic conductive agent is mixed with acrylonitrile butadiene rubber (NBR), which has excellent oil resistance, wear resistance, and aging resistance, to reduce the resistance value to 1 × 10 ⁶ Ω or more and 1 × 10 ⁷ Ω or less. A conditioned conductive material is used.

As an example of the solid rubber 7C, a conductive material in which NBR and epichlorohydrin rubber (ECO) are blended can also be used. Further, as another example, a conductive material made of urethane rubber in which an ionic conductive agent is mixed with rubber obtained by reacting a polyether polyol with isodianate can be used. Furthermore, as another example, a conductive material made of ethylene propylene diene rubber (EPDM) can be used.

On the other hand, the secondary transfer roll 7B is, for example, a rotatable roller having a diameter of 18 mm in which foam rubber 7E is formed around a metal shaft 7F having a diameter of 12 mm. A conductive material is mixed to adjust the resistance value of the foam rubber 7E to 1 × 10 ⁷ Ω or more and 1 × 10 ⁸ Ω or less. The metal shaft 7F is connected to the ground potential.

The transfer control unit (not shown) of the secondary transfer device 7 applies the voltage of the negative electrode from the secondary transfer power source 7G to the roll pair at the timing when the paper P is conveyed to the gap formed by the roll pair.

Then, the toner image charged on the negative electrode is peeled off from the intermediate transfer belt 6 by the electric field of the negative electrode generated in the gap between the roll pairs in addition to the pressing force pressing the paper P and the intermediate transfer belt 6 while the roll pair rotates. A force is generated to transfer the toner image formed on the intermediate transfer belt 6 to the paper P.

FIG. 3 shows an example of the configuration of the image forming control unit 40 that performs the image forming operation by the image forming apparatus 20. FIG. 3 shows an example of a computer 40X in which the image formation control unit 40 is composed of a computer. The computer 40X has a CPU (Central Processing Unit) 40A, a ROM (Read Only Memory) 40B, a RAM (Random Access Memory) 40C, a non-volatile memory 40D, and an input / output interface (I / O) 40E via a bus 40F. The I / O 40E is connected to an image forming unit 50, an operation display unit 52, a paper supply unit 54, a paper ejection unit 56, a density sensor 60, a position sensor 61, and a communication I / F 62. ..

The image formation control program 40P to be executed by the computer 40X is stored in the ROM 40B. The CPU 40A expands the image formation control program 40P from the ROM 40B into the reading RAM 40C, and executes processing by the image formation control program 40P. When the CPU 40A executes the process by the image formation control program 40P, the computer 40X operates as the image formation control unit 40. The image formation control program 40P may be provided by a recording medium such as a CD-ROM.

The image forming unit 50 is a device necessary for the image forming apparatus 20 to perform an image forming operation, for example, a photoconductor 1, a charger 2, a laser output unit 3, a developing device 4, an intermediate transfer belt 6, and a secondary. It includes a transfer device 7, a fixing device 9, and the like.

The operation display unit 52 includes a display button for receiving operation instructions, a touch panel type display (not shown) for displaying various information, and hardware keys (not shown) such as a numeric keypad and a start button. ..

The paper supply unit 54 includes, for example, a paper storage unit T in which the paper P is stored, a supply mechanism for supplying the paper P from the paper storage unit T to the image forming unit 50, and the like.

The paper ejection unit 56 includes, for example, an ejection unit from which the paper P is ejected, an ejection mechanism for ejecting the paper P on which the image is formed by the image forming unit 50 onto the ejection unit, and the like.

The communication I / F 62 is an interface for mutual data communication with a terminal device such as a personal computer (not shown).

The density sensor 60 detects the density of the toner image formed on the intermediate transfer belt 6. The position sensor 61 detects the position of the toner image formed on the intermediate transfer belt 6.

By the way, when the intermediate transfer belt 6 is formed in the shape of an endless belt, the intermediate transfer belt 6 is plastically deformed due to moisture absorption or the like, and is stretched or abutted by various rolls in contact with the intermediate transfer belt 6. A contact habit may occur as a deformation that follows the outer shape of various rolls. In particular, the present inventors, when the intermediate transfer belt 6 is left for a long period of time in a high temperature and high humidity environment (for example, temperature 28 degrees, humidity 80%), the contact habit becomes a remarkable deformation that affects the image quality deterioration. I found that. Here, the contact habit means that the intermediate transfer belt 6 is plastically deformed according to the outer shape of various rolls.

FIG. 4 shows an example of the secondary transfer device 7 in a state where the intermediate transfer belt 6 has a contact habit.
As shown in FIG. 4, in the intermediate transfer belt 6 of the secondary transfer device 7, the deformation region 6P is generated in a state where the contact habit is generated. That is, when the secondary transfer roll 7B is pressed against the backup roll 7A in which the intermediate transfer belt 6 is stretched and left unattended, the deformation region 6P is generated. For example, as shown in FIG. 4, when the backup roll 7A has a higher hardness than the secondary transfer roll 7B, the intermediate transfer belt 6 follows the backup roll 7A to which the secondary transfer roll 7B is pressed, and the backup roll 7A Orbit to. However, the intermediate transfer belt 6 stretched by the backup roll 7A and the roller 12A is pressed against the backup roll 7A by the secondary transfer roll 7B to generate a deformation region 6P. The deformed region 6P generated by the contact habit with the intermediate transfer belt 6 remains substantially as it is even when the intermediate transfer belt 6 is rotated.

FIG. 5 shows an example of a deformed region generated on the endless belt-shaped intermediate transfer belt 6 as an image holder.
FIG. 5 (A) shows a plan view of the intermediate transfer belt 6 in an unfolded state, and FIG. 5 (B) shows a cross-sectional view obtained by cutting out the periphery of the deformation region 6P of the intermediate transfer belt 6 in the direction along the moving direction. .. As shown in FIG. 5A, a deformation region 6P is generated on the intermediate transfer belt 6 over the width direction of the intermediate transfer belt 6. Further, as shown in FIG. 5B, the deformed region 6P of the intermediate transfer belt 6 is a recess having a length Lp and a depth Dp from the deepest portion from the position of the intermediate transfer belt 6 in a linear state by the tension rack. It becomes (dent).

In the present embodiment, the density sensor 60 detects the deformed region 6P generated by the contact habit with the intermediate transfer belt 6.

In the image forming apparatus 20, a control toner image for controlling the image density, the amount of toner supplied to the developing device 4, the charging potential of the photoconductor drum 5, and the like on the intermediate transfer belt 6 (hereinafter referred to as “toner patch”). ) Are formed at a predetermined density, and the density of the toner patch (for example, each color of YMCK) formed on the intermediate transfer belt 6 is detected by the density sensor 60 provided in the moving path of the intermediate transfer belt 6. It is configured in. Further, in the present embodiment, a plurality of density sensors 60 are arranged along the direction intersecting the moving direction of the intermediate transfer belt 6, and are formed by the plurality of density sensors 60 in the width direction of the intermediate transfer belt 6. It is configured to detect the reflectance of the toner patch and the surface of the intermediate transfer belt 6 itself.

As shown in FIG. 4, the density sensor 60 irradiates the surface of the intermediate transfer belt 6 and the surface of the intermediate transfer belt 6 on which the toner image is formed with the light emitted from the light emitting element 60A such as an LED, and the intermediate transfer belt 60. A specular reflection type sensor that detects the specular reflected light from the surface of No. 6 by the light receiving element 60B is used. The output from the density sensor 60 increases or decreases according to the increase or decrease in the amount of toner. Further, when the density sensor 60 detects the reflected light on the surface of the intermediate transfer belt 6 before the toner image is formed, the output from the density sensor 60 corresponds to the deformation of the intermediate transfer belt 6. That is, when the intermediate transfer belt 6 is orbited without deformation of the intermediate transfer belt 6, the output from the density sensor 60 is a constant output or a predetermined fluctuation range having variation in the reflected light on the surface of the intermediate transfer belt 6. Is the output of. On the other hand, when the intermediate transfer belt 6 has the deformed region 6P, the amount of specularly reflected light received from the surface of the intermediate transfer belt 6 decreases according to the depth of the deformed region 6P. The relationship between the depth of the deformation region 6P and the amount of specularly reflected light received from the surface of the intermediate transfer belt 6 can be determined in advance by experiments.

Therefore, when the deformation region 6P is not generated on the intermediate transfer belt 6 due to the contact habit, the output of the density sensor 60 is stable, and when the deformation region 6P is generated, the output varies from the stable output of the density sensor 60. Therefore, it is possible to determine whether or not the deformation region 6P is generated due to the contact habit, and detect the deformation region 6P.

When a toner image is transferred to form a toner image while the deformation region 6P is generated, an electric field required for transfer is formed in a recess (dent) having a length Lp and a depth Dp that constitutes the deformation region 6P. Since the toner is not transferred, the toner may not be transferred, resulting in an image on a line and causing deterioration in image quality. Therefore, in the present embodiment, the image formation control unit 40 (computer 40X) of the image forming apparatus 20 controls so as to form a toner image on the intermediate transfer belt 6 in the region excluding the deformation region 6P.

FIG. 6 shows an example of a state in which the intermediate transfer belt 6 is developed on a plane for explaining that a plurality of toner images Img1 to Img4 are transferred to the endless belt-shaped intermediate transfer belt 6 as an image holder. .. FIG. 6A shows an example of a state in which the intermediate transfer belt 6 for transferring a plurality of toner images Img1 to Img4 is developed on a plane. FIG. 6B shows an example of the deformation region 6P generated in the intermediate transfer belt 6. FIG. 6C shows an example of a state in which a plurality of toner images Img1 to Img4 are transferred when the deformation region 6P is generated on the intermediate transfer belt 6.

As shown in FIG. 6A, an image forming region G on which the toner image can be transferred is defined on the intermediate transfer belt 6. In the example shown in FIG. 6A, the image forming surface on the intermediate transfer belt 6 is defined in the image forming region G. Then, as shown in FIG. 6 (A), when a plurality of toner images Img1 to Img4 are transferred to the intermediate transfer belt 6, a deformed region 6P is generated on the intermediate transfer belt 6 as shown in FIG. 6 (B). If this is the case, image quality deterioration may occur in the toner image Img2 formed on the deformation region 6P. Therefore, in the present embodiment, as shown in FIG. 6C, the region within the image forming region G and corresponding to the deformation region 6P is set as the image formation exclusion region Gx that prohibits image formation. Therefore, the image forming apparatus 20 according to the present embodiment forms an image in the image forming region G excluding the image forming exclusion region Gx. As a result, the image quality of the toner image formed on the intermediate transfer belt 6 does not deteriorate.

By the way, the deformed region 6P generated due to the contact habit with the intermediate transfer belt 6, which affects the deterioration of image quality, remains substantially as it is even when the intermediate transfer belt 6 is rotated. However, the deformed region 6P may return to a linear (planar) region by orbiting the intermediate transfer belt 6 for a long time due to the tension of the intermediate transfer belt 6 or the rigidity of the intermediate transfer belt 6.

FIG. 7 shows the time characteristic in which the deformed region 6P of the intermediate transfer belt 6 returns to the linear (planar) region.
In FIG. 7, the backup roll 7A and the intermediate transfer belt 6 are secondarily transferred so that the intermediate transfer belt 6 has a deformed region 6P of a recess (dent) having a length Lp and a depth Dp of Dmax from a flat state. The roll 7B is in contact with the roll 7B, and the elapsed time of the contact state is on the horizontal axis. Further, the vertical axis shows the deformation of the intermediate transfer belt 6 when the contact state is released and a predetermined time (for example, one round time of the intermediate transfer belt 6) elapses after the elapsed time of the contact state has elapsed. The amount (depth Dmax) is shown. In FIG. 7, the deformation amount Dth indicates the deformation amount of the intermediate transfer belt 6 that does not affect the image quality deterioration. That is, in FIG. 7, after the time T1 has elapsed in the contact state where the backup roll 7A and the intermediate transfer belt 6 and the secondary transfer roll 7B are in contact with each other, for example, one round time of the intermediate transfer belt 6 has elapsed. After that, it is shown that the deformation amount of the intermediate transfer belt 6 is restored to the deformation amount Dth which does not affect the image quality deterioration.

Therefore, the deformation of the intermediate transfer belt 6 having a deformation amount within the deformation amount Dth is acceptable as the deformation that does not affect the image quality deterioration. The deformation amount Dth that does not affect the image quality deterioration is a state in which, for example, a linear image does not appear in the deformed region when the toner image is transferred to the deformed intermediate transfer belt 6 to form an image (a state in which visual inspection is difficult). The amount of deformation that becomes can be obtained experimentally in advance.

It should be noted that the maintenance and restoration characteristics of the deformed state when the intermediate transfer belt 6 is deformed due to the contact habit are the material and outer shape (for example, diameter, winding angle) of various rolls on which the intermediate transfer belt 6 is stretched or abutted. , And at least one of the abutting lengths). Therefore, the maintenance and restoration characteristics of the deformed state are preferably determined according to the components such as various rolls that come into contact with the intermediate transfer belt 6.

Further, in the present embodiment, the case where the density sensor 60 is also used as a detector for detecting the deformation of the intermediate transfer belt 6 will be described, but a detector for detecting the deformation of the intermediate transfer belt 6 may be provided independently. Good.

On the other hand, in the present embodiment, the position of the deformation region 6P generated on the intermediate transfer belt 6 is detected by the position sensor 61.

FIG. 8 shows a state in which an endless belt-shaped intermediate transfer belt 6 as an image holder is developed on a plane.
As shown in FIG. 8, the intermediate transfer belt 6 developed on a flat surface has a shape of width W and length L, and an image forming region G on which a toner image can be transferred is defined in the flat surface portion. ing. Further, marks 6M are formed at regular intervals in the length direction of the intermediate transfer belt 6 in the margin portion in the width direction of the intermediate transfer belt 6. In the present embodiment, the position on the intermediate transfer belt 6 is detected by detecting the mark 6M formed on the intermediate transfer belt 6 with the position sensor 61 while moving the intermediate transfer belt 6.

In this embodiment, the case where the position sensor 61 is provided independently will be described, but the density sensor 60 may also be used.

Further, in the present embodiment, the case where the position of the intermediate transfer belt 6 in which the density of the toner image is detected by the position sensor 61 is detected has been described, but the case is limited to detecting the position of the intermediate transfer belt 6 by the position sensor 61. Not a thing. For example, the rotation angle of any roller in contact with the intermediate transfer belt 6 may be detected, and the position of the intermediate transfer belt 6 corresponding to the detected rotation angle may be detected.

Further, in the present embodiment, the case of detecting the position of the deformed region 6P generated in the intermediate transfer belt 6 has been described, but the position of the deformed region 6P may be detected constantly or periodically. Further, one round of the intermediate transfer belt 6 may be detected at the beginning of starting the image forming apparatus 20, the detected position may be stored, and the stored position of the deformed region 6P may be used from the next time.

Furthermore, in the present embodiment, the case where the deformation region 6P generated in the intermediate transfer belt 6 is detected by using the density sensor 60 has been described, but the detection of the deformation region 6P is limited to the density detection using the density sensor 60. It is not something that is done. That is, the deformation region 6P may be detected only by detecting the image forming surface of the image holder, that is, the deformed portion of the intermediate transfer belt 6 in which the deformation that affects the image quality deterioration occurs. For example, the unevenness generated on the surface of the intermediate transfer belt 6 May be detected. As for the unevenness generated on the surface of the intermediate transfer belt 6, the fluctuation amount of the surface displacement of the intermediate transfer belt 6 may be detected, and the region where the detected fluctuation amount exceeds the predetermined fluctuation amount may be designated as the deformation region 6P.

Next, the image forming operation in the image forming apparatus 20 according to the present embodiment will be described in detail.

The amount of deformation Dth used in the following description is a magnitude that affects the deterioration of image quality, and the deformation due to the deformation characteristics of the intermediate transfer belt 6 under a standard environmental condition is obtained in advance by an experiment or the like, and the non-volatile memory 82 It shall be memorized in advance.

FIG. 9 shows a flow of processing of the image formation control program 40P executed by the CPU 40A of the computer 40X that operates as the image formation control unit 40 at the time of image formation.

The image formation control program 40P is executed by the CPU 40A when the power is turned on to the image forming apparatus 20 and an image formation start instruction is received from the CPU 40A.

First, in step S100, information indicating the belt profile is acquired as the deformed state of the intermediate transfer belt 6 that affects the image quality deterioration formed by the image forming apparatus 20. The information indicating the belt profile is information in which the position of the intermediate transfer belt 6 in the moving direction and the deformation amount Dp are associated with each other. That is, the CPU 40A acquires information in which the position of the intermediate transfer belt 6 detected by the position sensor 61 is associated with the deformation amount Dp according to the density detected by the density sensor 60 as information indicating the belt profile.

Next, in step S102, the deformation amount Dp is transformed into the intermediate transfer belt 6 by determining whether or not the deformation amount Dp exceeds the deformation amount Dth that does not affect the image quality deterioration by using the information indicating the belt profile acquired in step S100. Judge whether or not If an affirmative determination is made in step S102, the process proceeds to step S108 after the transformation mode process is executed in step S104. On the other hand, if a negative determination is made in step S102, the process proceeds to step S108 after the normal mode process is executed in step S106.

The deformation mode process is a process of setting a portion of the intermediate transfer belt 6 in which deformation that affects image quality deterioration occurs in the image formation exclusion region Gx (see FIG. 6C). That is, in step S104, the portion including the position where the deformation amount Dp exceeds the deformation amount Dth is set in the image formation exclusion region Gx by using the information indicating the belt profile.

The normal mode process is a process of setting all the image-forming regions of the intermediate transfer belt 6 initially set in the image-forming region G (see FIG. 6A). This normal mode process includes a process of releasing the image formation exclusion region Gx set in the image formation region G of the intermediate transfer belt 6. If the image formation exclusion region Gx has been set up to the previous time and there is no portion in the information indicating the belt profile (step S100) that includes the position where the deformation amount Dp exceeds the deformation amount Dth, the image formation exclusion region Gx has been set by the previous time. The set image formation exclusion region Gx is released. As a result, all of the initially set image-forming regions of the intermediate transfer belt 6 can be set in the image-forming region G.

In step S108, an image forming process for forming an image in the image forming region G of the intermediate transfer belt 6 set in the deformation mode of step S104 or the image forming region G of the intermediate transfer belt 6 set in the normal mode of step S106 is performed. It is executed, and the process shifts to step S110. In step S110, it is determined whether or not the transfer processing of the toner image on the paper P is completed, and in the case of an affirmative determination, the processing of the image formation control program 40P is terminated. If a negative determination is made in step S110, the process proceeds to step S112.

In step S112, it is determined whether or not the setting time for reviewing the belt profile has arrived. The setting time for reviewing the belt profile can be set to a predetermined time from the time characteristic that the deformation region 6P of the intermediate transfer belt 6 returns to the linear (planar) region. For example, as a setting time for reviewing the belt profile, a time corresponding to a predetermined number of laps of the intermediate transfer belt 6 may be set. If the affirmative judgment is made in step S112, the process returns to step S100, the information indicating the belt profile is acquired again, and the above process is repeated. On the other hand, if a negative determination is made in step S112, the process returns to step S108, and the image formation process is repeated with the already set image formation exclusion region Gx still set.

As described above, the image forming apparatus 20 according to the present embodiment forms an image in the image forming region G excluding the image forming exclusion region Gx. As a result, the image quality of the toner image formed on the intermediate transfer belt 6 does not deteriorate.

In an example of the process shown in FIG. 9, in step S112, it is determined whether or not the setting time for reviewing the belt profile has arrived, but the determination is not limited to determining whether or not the setting time for reviewing the belt profile has arrived. .. For example, in the process shown in FIG. 9, a toner image is not formed in the image formation exclusion region Gx. Therefore, for the image formation exclusion region Gx in the orbital unit of the intermediate transfer belt 6, the deformation amount Dp is detected by the density sensor 60, and when it is detected, it is determined whether or not the deformation amount Dth that does not affect the image quality deterioration is exceeded. It is also possible to perform interrupt processing. When this interrupt processing is performed, if a positive determination is made (when the detected deformation amount Dp is within the deformation amount Dth), the processing may be shifted to step S102.

FIG. 10 shows an example of the flow of the image formation process in step S108 of the image formation control program 40P.

First, in step S200, the positions of the image formation region G of the initial intermediate transfer belt 6 (the image formation exclusion region Gx is not set) and the image formation exclusion region Gx set in the image formation region G of the intermediate transfer belt 6 To get. That is, the image formation region G of the intermediate transfer belt 6 excluding the image formation exclusion region Gx set in the deformation mode of step S104, or the image formation exclusion region Gx set in the normal mode of step S106 is released from the intermediate transfer belt. Information indicating the portion of the image forming region G of No. 6 is acquired. In the next step S202, after acquiring the image data of the toner image formed on the intermediate transfer belt 6, the process proceeds to step S204.

In step S204, the arrangement of the toner image on the intermediate transfer belt 6 is derived so that the toner image is formed in the image forming region G of the intermediate transfer belt 6 excluding the image formation exclusion region Gx. Next, the image formation timing for forming the toner image on the intermediate transfer belt 6 is determined by the derived arrangement.

In the next step S206, the image forming unit 50 is controlled so that the image is formed according to the image forming timing determined in step S204. That is, the image forming operation is executed by controlling, for example, the photoconductor 1, the charging device 2, the laser output unit 3, and the developing device 4 that constitute the image forming unit 50. Then, in the next step S208, the image formation process is executed until the determination as to whether or not the image formation process is completed is affirmed, and in the case of the affirmative determination, the present processing routine is terminated.

As described above, according to the present embodiment, the image forming region G of the intermediate transfer belt 6 excluding the portion (image formation exclusion region Gx) in which the intermediate transfer belt 6 is deformed to affect the image quality deterioration. Since the image is formed, even if the intermediate transfer belt 6 is deformed, the deterioration of the image quality due to the deformation can be suppressed. For example, even if a contact habit occurs as a deformation following the outer shape of various rolls in a region stretched or abutted by various rolls in contact with the intermediate transfer belt 6, it is caused by the deformation due to the contact habit. Deterioration of image quality can be suppressed.

Specifically, when the secondary transfer roll 7B is pressed against the backup roll 7A in a state where the intermediate transfer belt 6 is stretched and left in a contact state, it imitates a part of the deformed backup roll 7A. Even when the deformation region 6P of the intermediate transfer belt 6 does not return to flatness, the remaining deformation region is excluded from the image formation region G, so that deterioration of image quality due to deformation due to contact habit can be suppressed. it can.

The deformed region 6P generated due to the contact habit with the intermediate transfer belt 6, which affects the deterioration of image quality, may return to a linear (planar) region with the passage of time. In the process of returning in this way, the intermediate transfer belt 6 may not be returned evenly in the width direction.

FIG. 11 shows an example of a state in the process in which the deformed region 6P of the intermediate transfer belt 6 returns to the linear (planar) region.
In FIG. 11, in the process of returning the deformation region 6P of the intermediate transfer belt 6, a part of the intermediate transfer belt 6 in the width direction (the portion indicated by the distance wx in FIG. 11) remains as deformation affecting the image quality deterioration. An example is shown. In this case, it is preferable to set all the regions in the width direction of the intermediate transfer belt 6 including a part in the width direction of the intermediate transfer belt 6 (the portion indicated by the distance wx in FIG. 11) as the deformation region 6P. This is a process in which a deformation region that affects image quality deterioration and a region that does not affect image quality deterioration coexist in the width direction of the intermediate transfer belt 6, and the image formation process is separated for each and the process is executed. This is because it is preferable to suppress the complexity.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various changes or improvements can be made to the above embodiments without departing from the gist of the invention, and the modified or improved forms are also included in the technical scope of the present invention.

Further, in the above embodiment, the case where the transfer control process is realized by the software configuration by the process using the flowcharts shown in FIGS. 9 and 10 has been described, but the present invention is not limited to this, and for example, image formation. The control process may be realized by a hardware configuration.

Although the image forming apparatus 20 according to the present embodiment is intended to form a color image, it goes without saying that the image forming apparatus 20 may be an image forming apparatus 20 that forms a monochrome image. Further, the secondary transfer roll 7B of the transfer device 7 according to the present embodiment is not limited to a form composed of a single roller, for example, a secondary transfer roll 7B, another roller (not shown), and a secondary transfer roll. It may be composed of a plurality of rollers and belts, including a belt stretched around 7B and another roller (not shown).

Further, in the secondary transfer device 7 according to the present embodiment, the case where the intermediate transfer belt 6 is deformed to affect the image quality deterioration has been described, but the present invention is not limited to the secondary transfer device 7, and the intermediate transfer belt 6 is not limited to the secondary transfer device 7. Any component may be applied as long as it causes deformation that affects image quality deterioration.

1 Photoreceptor 2 Charger 3 Laser output unit 4 Developer 5 Primary transfer device 6 Intermediate transfer belt 7 Transfer device 7A Backup roll 7B Secondary transfer roll 8 Belt cleaner 9 Fixer 13 Paper transfer roller 20 Image forming device 34 Development roll 40 Image formation control unit 40X computer

Claims (6)

An endless belt-shaped image holder and
A forming portion that forms a toner image on the image forming surface of the image holder, and
A detection unit that detects a deformed portion of the image forming surface of the image holder that affects image quality deterioration, and a detection unit that detects the deformed portion.
When the deformed portion is detected by the detection unit, the deformed portion detected by the detection unit is set in the image formation exclusion region, and the time required for the deformed portion to return to a state in which the image quality deterioration is not affected is set. preset predetermined time while, in the region excluding the image-forming exclusion area set as said detected deformed portion by the detection unit, controlling the forming unit so that the toner image is formed, the predetermined time When the deformed portion is not detected by the detection unit and the deformed portion is restored to a state in which the image quality deterioration is not affected , the setting of the image formation exclusion region is canceled and the deformed portion is restored. A control unit that controls the forming unit so that the toner image is formed in a region including the image formation exclusion region that has been released.
An image forming apparatus equipped with. The image forming apparatus according to claim 1, wherein the deformed portion is a portion in which a displacement fluctuation amount of the belt surface displacement of the endless belt-shaped image holder exceeds a predetermined fluctuation amount. In the deformed portion, when a toner image having a predetermined density was formed in the forming portion, the density of the formed toner image fluctuated more than the predetermined fluctuation amount with respect to the predetermined density. The image forming apparatus according to claim 1, which is a part. The image forming apparatus according to any one of claims 1 to 3, wherein the deformed portion is a portion in which the amount of deformation based on the state before the deformation occurs exceeds a predetermined amount of deformation. Any of claims 1 to 4, wherein the control unit controls the forming unit so that the toner image is formed in a region excluding the deformed portion until the deformed portion is no longer detected by the detecting unit. The image forming apparatus according to item 1. Detects the deformed portion of the image forming surface of the endless belt-shaped image holder on which the toner image is formed, which affects the deterioration of image quality.
When the deformed portion in which the deformation occurs is detected, the detected deformed portion is set in the image formation exclusion region, and a predetermined time is set in advance as a time until the deformed portion returns to a state in which the image quality deterioration is not affected. time between, on the region excluding the image-forming exclusion area set as said detected deformed portion, the control such that the toner image is formed, not the deformed portion is detected when a lapse of the predetermined time In this case, the setting of the image formation exclusion region is canceled assuming that the deformed portion is restored to a state that does not affect the image quality deterioration, and the toner image is formed in the region including the released image formation exclusion region as the portion where the deformation is restored. An image forming program that causes a computer to perform processing, including controlling the formation of.

Images