JP2023149900A - Method for controlling image forming apparatus, and image forming apparatus - Google Patents

Abstract

To reduce the amount of toner adhering to a secondary transfer body when toner discharge processing is executed.SOLUTION: A processor 81 sets a discharge time according to an index value of the amount of toner stored by recovery members, and causes a plurality of first cleaning units 45 to execute toner discharge processing for the discharge time (S3). When the index value is within a reference rage, the processor 81 causes the plurality of first cleaning units 45 to execute the toner discharge processing at timing when a plurality of discharged toner parts do not overlap each other on a surface of an intermediate transfer body 441. When the index value is out of the reference range, the processor 81 causes the plurality of first cleaning units 45 to execute the toner discharge processing at timing when the plurality of discharged toner parts partially overlap each other on the surface of the intermediate transfer body 441.SELECTED DRAWING: Figure 3

Description

The present invention relates to an image forming apparatus and a control method for an image forming apparatus capable of collecting toner from an image bearing member and discharging toner to the image bearing member.

An electrophotographic image forming apparatus may include a tandem printing apparatus capable of forming a color image. The printing device includes an image forming section, a primary transfer device, and a secondary transfer device.

The image forming section forms toner images on the surfaces of a plurality of image carriers. The primary transfer device transfers the toner images on the surfaces of the plurality of image carriers to an intermediate transfer member. The secondary transfer device transfers the toner image on the surface of the intermediate transfer body to a sheet.

The image forming apparatus further includes a plurality of first cleaning devices and a plurality of second cleaning devices. Each of the plurality of first cleaning devices executes toner collection processing. The toner recovery process is a process of recovering toner from the surface of each of the plurality of image carriers. A second cleaning device removes toner from the surface of the intermediate transfer body.

Each of the plurality of first cleaning devices can also perform a toner release process (for example, see Patent Document 1). The toner release process is a process of releasing the collected toner to each of the plurality of image carriers.

Each of the plurality of first cleaning devices includes a recovery member and a recovery voltage output section. The collection member is disposed in contact with the surface of the image carrier and is capable of holding toner. For example, the collection member is a porous member such as a sponge.

The recovery voltage output section is capable of applying a recovery bias voltage or an emission bias voltage to the recovery member. The recovery bias voltage has a polarity different from the charging polarity of the toner. The emission bias voltage has the same polarity as the charging polarity of the toner.

By applying the collection bias voltage to the collection member, toner remaining on the surface of the image carrier is electrically attracted to the collection member. The attracted toner is retained by the collecting member.

As the toner accumulates on the collection member, the toner collection performance of the collection member is degraded.

On the other hand, by applying the discharge bias voltage to the collection member, the toner held in the collection member is discharged to the collection member. This improves the toner recovery performance of the recovery member.

By executing the toner discharge process, a plurality of discharged toner portions are formed on the surfaces of the plurality of image carriers. The plurality of emitted toner portions are transferred from the plurality of image carriers to the intermediate transfer member. Further, the plurality of discharged toner portions are removed from the intermediate transfer body by the second cleaning device.

Japanese Patent Application Publication No. 2015-87416

Incidentally, the plurality of emitted toner portions on the surface of the intermediate transfer member reach the second cleaning device via the secondary transfer device. In the secondary transfer device, the secondary transfer body contacts the plurality of discharged toner parts.

When the plurality of emitted toner parts come into contact with the secondary transfer body, the secondary transfer device applies a reverse transfer bias voltage to the secondary transfer body. The reverse transfer bias voltage has the same polarity as the charging polarity of the toner.

The process of applying the reverse transfer bias voltage to the secondary transfer body is a process for reducing the amount of toner adhering to the secondary transfer body.

When the toner release process is executed, a thick toner layer may be formed on the intermediate transfer body. In this case, even if the reverse transfer bias voltage is applied to the secondary transfer body, there is a risk that the amount of the toner adhering to the secondary transfer body may increase.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling an image forming apparatus and an image forming apparatus that can reduce the amount of toner adhering to a secondary transfer member when toner release processing is executed.

A method according to one aspect of the present invention is a method for controlling an image forming apparatus. The image forming apparatus includes an image forming section, an intermediate transfer body, a plurality of primary transfer sections, a secondary transfer section, a plurality of first cleaning sections, and a second cleaning section. The image forming section includes a plurality of rotating image carriers, and is capable of forming toner images on surfaces of the plurality of image carriers. The intermediate transfer member rotates while contacting the plurality of image carriers. The plurality of primary transfer units are capable of performing a primary transfer process of transferring the toner on the surface of the plurality of image carriers to the surface of the intermediate transfer body, respectively, at a plurality of primary transfer positions along the intermediate transfer body. be. The secondary transfer unit is capable of performing a secondary transfer process of transferring the toner transferred onto the surface of the intermediate transfer body to a sheet. The plurality of first cleaning sections collect the toner on the surface of each of the plurality of image carriers at a portion of the surface of each of the plurality of image carriers that has passed through each of the plurality of primary transfer sections. It is possible to perform processing and toner release processing for releasing the toner onto the surface of each of the plurality of image carriers. The second cleaning section removes the toner from a portion of the surface of the intermediate transfer body that has passed through the secondary transfer section. Each of the plurality of first cleaning sections includes a recovery member and a recovery voltage output section. The collecting member rotates while contacting the surface of each of the plurality of image carriers, and is capable of holding the toner. The collection voltage output unit applies a collection bias voltage having a polarity different from the charging polarity of the toner to the collection member in the toner collection process, and applies a collection bias voltage having the same polarity as the charging polarity of the toner to the collection member in the toner discharge process. Apply an emission bias voltage. The secondary transfer section includes a secondary transfer body and a secondary voltage output section. The secondary transfer body rotates while contacting the surface of the intermediate transfer body. The secondary voltage output section is capable of applying a bias voltage to the secondary transfer body. The control method includes the processor acquiring an index value of the amount of toner accumulated in the collection members of the plurality of first cleaning sections. Further, the control method includes the processor setting a discharge time according to the index value, and causing the plurality of first cleaning units to execute the toner discharge process for the discharge time. Further, in the control method, the processor causes the plurality of primary transfer parts to perform the primary transfer process on the plurality of released toner parts formed on the surfaces of the plurality of image carriers by the toner release process. include. Further, in the control method, when each of the plurality of emitted toner portions transferred to the surface of the intermediate transfer member passes through a position of the secondary transfer member, the processor controls the charge polarity of the toner to be the same as the charge polarity of the toner. The method includes outputting a polar reverse transfer bias voltage to the secondary voltage output section. The processor sets a predetermined section travel time or a time less than or equal to the section travel time as the release time when the index value is within the reference range, and when the index value falls outside the reference range. , the release time is set to be longer than the section travel time. The section movement time is the time required for the plurality of emitted toner parts transferred to the surface of the intermediate transfer member to move a section distance that is an interval between the plurality of primary transfer positions. When the index value is within the reference range, the processor causes the plurality of first cleaning units to execute the toner release process at a timing when the plurality of ejected toner parts do not overlap on the surface of the intermediate transfer member. . When the index value deviates from the reference range, the processor executes the toner release process on the plurality of first cleaning units at a timing when the plurality of release toner units partially overlap each other on the surface of the intermediate transfer member. let

The image forming apparatus according to another aspect of the present invention includes the image forming section, the intermediate transfer body, the plurality of primary transfer sections, the secondary transfer section, the plurality of first cleaning sections, and the plurality of first cleaning sections. The apparatus includes a second cleaning section and the processor that implements the control method.

According to the present invention, it is possible to provide a method for controlling an image forming apparatus and an image forming apparatus that can reduce the amount of toner adhering to a secondary transfer member when toner release processing is executed.

FIG. 1 is a configuration diagram of an image forming apparatus according to the first embodiment. FIG. 2 is a block diagram showing the configuration of a control device in the image forming apparatus according to the first embodiment. FIG. 3 is a flowchart illustrating an example of a reproduction control procedure in the image forming apparatus according to the first embodiment. FIG. 4 is a schematic diagram showing a first example of a plurality of discharged toner portions on the intermediate transfer belt in the image forming apparatus according to the first embodiment. FIG. 5 is a schematic diagram showing a second example of a plurality of discharged toner portions on the intermediate transfer belt in the image forming apparatus according to the first embodiment. FIG. 6 is a schematic diagram showing a third example of a plurality of discharge toner portions on the intermediate transfer belt in the image forming apparatus according to the first embodiment. FIG. 7 is a schematic diagram showing a fourth example of a plurality of discharged toner portions on the intermediate transfer belt in the image forming apparatus according to the first embodiment. FIG. 8 is a configuration diagram of an image forming apparatus according to the second embodiment.

Embodiments of the present invention will be described below with reference to the drawings. Note that the following embodiments are examples of embodying the present invention, and do not limit the technical scope of the present invention.

[First embodiment]
The image forming apparatus 10 according to the first embodiment is an apparatus that performs print processing using an electrophotographic method. The printing process is a process of forming an image on the sheet 9. The sheet 9 is an image forming medium such as paper or a sheet-like resin member.

[Configuration of image forming apparatus 10]
As shown in FIG. 1, the image forming apparatus 10 includes a sheet storage section 2, a sheet conveyance path 30, a sheet conveyance device 3, and a printing device 4. Furthermore, the image forming apparatus 10 also includes an operating device 801, a display device 802, and a control device 8.

The sheet conveying path 30, the sheet conveying device 3, the printing device 4, and the control device 8 are housed in the housing 1.

The sheet storage section 2 stores the sheet 9. The sheet conveyance device 3 feeds the sheet 9 from the sheet storage section 2 to the sheet conveyance path 30, and further conveys the sheet 9 along the sheet conveyance path 30.

The sheet conveying device 3 includes a sheet feeding mechanism 31 and a plurality of pairs of conveying rollers 32.

The sheet feeding mechanism 31 feeds the sheet 9 in the sheet storage section 2 to the sheet conveyance path 30. The plurality of conveyance roller pairs 32 convey the sheet 9 along the sheet conveyance path 30. Furthermore, one set of the plurality of transport roller pairs 32 discharges the sheet 9 from the sheet transport path 30 onto the discharge tray 101 .

The printing device 4 performs the printing process on the sheet 9 conveyed along the sheet conveyance path 30 . In this embodiment, the printing device 4 is a tandem color printing device.

The printing device 4 forms a toner image on the sheet 9 in the printing process. The toner image is an image using toner as a developer. The toner is an example of the granular developer.

The printing device 4 includes a plurality of monochrome image forming sections 4x, an optical scanning device 40, a transfer device 44, and a fixing device 46. In this embodiment, the printing device 4 includes four monochrome image forming sections 4x corresponding to four colors: yellow, cyan, magenta, and black.

Note that the number of monochrome image forming units 4x in the printing device 4 is the number of toner colors used.

Each of the monochrome image forming sections 4x includes a drum-shaped photoreceptor 41, a charging device 42, a developing device 43, a first cleaning device 45, and the like. That is, the printing device 4 includes four photoreceptors 41, four charging devices 42, four developing devices 43, and four first cleaning devices 45.

In each monochrome image forming section 4x, the photoreceptor 41 rotates, and the charging device 42 performs charging processing. The charging process is a process of charging the surface of the photoreceptor 41. Furthermore, the optical scanning device 40 forms an electrostatic latent image on the charged surface of the photoreceptor 41 by scanning with laser light.

The optical scanning device 40 is an example of a latent image forming unit that forms the electrostatic latent image on the surface of the charged photoreceptor 41.

Furthermore, the developing device 43 supplies the toner to the surface of the photoreceptor 41 to develop the electrostatic latent image into the toner image. The developing device 43 supplies the toner to the photoreceptor 41 at a developing position on the outer periphery of the photoreceptor 41 . The developing device 43 is an example of a developing section.

The charging device 42 includes a charging member 421 and a charging voltage output device 422. The charging member 421 is disposed facing the photoreceptor 41 at a charging position on the outer periphery of the photoreceptor 41 . The charging voltage output device 422 applies a charging bias voltage to the charging member 421 . The charging bias voltage is a bias voltage applied in the charging process.

The charging bias voltage is applied to the photoreceptor 41 from the charging voltage output device 422 through the charging member 421. As a result, the surface of the photoreceptor 41 is charged. The charging device 42 is an example of a charging section.

The developing device 43 includes a developing roller 431 and a developing voltage output device 432. The developing roller 431 is disposed facing the photoreceptor 41 at the developing position. The developing roller 431 rotates while carrying toner.

The developing voltage output device 432 applies a developing bias voltage to the developing roller 431. In this embodiment, the developing bias voltage is a voltage in which an alternating current voltage is superimposed on a direct current voltage.

The developing roller 431 rotates while carrying toner, and supplies the toner to the surface of the photoreceptor 41 at the developing position. The developing roller 431 is an example of a developing body. The development voltage output device 432 is an example of a development voltage output section.

The toner carried on the developing roller 431 is transferred to the electrostatic latent image portion on the surface of the photoreceptor 41 due to an electric field generated between the developing roller 431 and the photoreceptor 41 .

At the development position, the toner moves from the development roller 431 to the electrostatic latent image on the surface of the photoreceptor 41. Thereby, the electrostatic latent image is developed into the toner image. The four photoreceptors 41 are an example of a plurality of image carriers each carrying the toner image.

As shown above, the optical scanning device 40 and each of the four monochrome image forming sections 4x can form the toner image on the surface of the photoreceptor 41. The optical scanning device 40 and the four monochrome image forming sections 4x are examples of image forming sections.

In this embodiment, the developing device 43 performs development using a two-component developing method. That is, the developing device 43 charges the toner by stirring a two-component developer containing the toner and a magnetic carrier. Further, the developing device 43 supplies the charged toner to the photoreceptor 41 .

The magnetic carrier is a granular material having magnetism. For example, the magnetic carrier is a granular magnetic material whose surface is coated. The coating is made of synthetic resin such as epoxy resin.

In this embodiment, the printing device 4 further includes a roller moving mechanism 433. The roller moving mechanism 433 is a mechanism that moves the developing rollers 431 of the four developing devices 43 between the developing position and the retracted position under the control of the control device 8 (see FIG. 1).

The development position is a position where toner can be supplied from the development roller 431 to the photoreceptor 41. The retreat position is a position farther from the photoreceptor 41 than the development position. When the developing roller 431 is in the retracted position, toner does not move between the photoreceptor 41 and the developing roller 431.

For example, the roller moving mechanism 433 includes a motor and a cam mechanism driven by the motor. The cam mechanism is driven by the motor to move each of the four developing rollers 431 from one of the developing position and the retracted position to the other.

When developing the toner image, the roller moving mechanism 433 holds the four developing rollers 431 at the developing position.

The transfer device 44 includes an intermediate transfer belt 441, four primary transfer devices 442 corresponding to the four monochrome image forming units 4x, a secondary transfer device 443, and a second cleaning device 444.

Intermediate transfer belt 441 is supported by a plurality of support rollers 440. One of the plurality of support rollers 440 is rotated by power received from a motor (not shown). As a result, the intermediate transfer belt 441 rotates while contacting the surfaces of the four photoreceptors 41.

Each of the photoreceptors 41 is in contact with the intermediate transfer belt 441 at each of four primary transfer positions P1 along the surface of the intermediate transfer belt 441.

Each of the primary transfer devices 442 can perform a primary transfer process at each of the primary transfer positions P1. The primary transfer process is a process of transferring the toner image on the surface of the photoreceptor 41 to the surface of the intermediate transfer belt 441.

As the four primary transfer devices 442 execute the primary transfer process, the toner images of four colors are formed on the surface of the intermediate transfer belt 441.

Each primary transfer device 442 includes a primary transfer body 4421 and a primary voltage output device 4422. The primary transfer body 4421 is arranged to face the photoreceptor 41 with the intermediate transfer belt 441 interposed therebetween.

The primary voltage output device 4422 applies a primary transfer bias voltage to the primary transfer body 4421. The toner image formed on the surface of the photoreceptor 41 is transferred to the surface of the intermediate transfer belt 441 by an electric field generated between the photoreceptor 41 and the primary transfer member 4421. The polarity of the primary transfer bias voltage is opposite to the charging polarity of the toner.

For example, in each of the primary transfer devices 442, the primary transfer body 4421 is a roller that rotates while contacting the inner surface of the intermediate transfer belt 441. The four primary transfer devices 442 are an example of a plurality of primary transfer sections. The primary voltage output device 4422 is an example of a primary voltage output section.

The secondary transfer device 443 can perform secondary transfer processing. The secondary transfer process is a process in which the toner image formed on the intermediate transfer belt 441 is transferred to the sheet 9 at the secondary transfer position of the sheet conveyance path 30.

The secondary transfer device 443 includes a secondary transfer body 4431 and a secondary voltage output device 4432. The secondary transfer body 4431 is a roller that rotates while contacting the intermediate transfer belt 441. The secondary transfer device 443 is an example of a secondary transfer section.

The secondary transfer body 4431 is in contact with the intermediate transfer belt 441 at the secondary transfer position. Sheet 9 passes between intermediate transfer belt 441 and secondary transfer body 4431. Note that the secondary transfer position is the position of the secondary transfer body 4431.

The secondary voltage output device 4432 applies a secondary transfer bias voltage to the secondary transfer body 4431. The polarity of the secondary transfer bias voltage is opposite to the charging polarity of the toner. The toner image formed on the surface of the intermediate transfer belt 441 is transferred to the sheet 9 by an electric field generated between the intermediate transfer belt 441 and the secondary transfer body 4431.

Note that the intermediate transfer belt 441 is an example of an intermediate transfer body. The transfer device 44 is an example of a transfer unit that can perform the primary transfer process and the secondary transfer process.

Each of the first cleaning devices 45 executes toner collection processing. The toner recovery process is a process of recovering toner present in the portions of the surface of each of the photoreceptors 41 that have passed through each of the primary transfer positions P1.

Further, each of the first cleaning devices 45 can also perform a toner release process. The toner release process is a process in which toner collected from the surface of each photoreceptor 41 is released onto the surface of each photoreceptor 41.

The four first cleaning devices 45 are an example of a plurality of first cleaning sections.

Each of the first cleaning devices 45 includes a recovery member 451 and a recovery voltage output device 452. Each of the collection members 451 is a member capable of holding the toner. For example, each collection member 451 is a porous member such as a sponge.

Each recovery member 451 rotates while contacting the surface of each photoreceptor 41 . Each recovery member 451 is in contact with the surface of each photoreceptor 41 at a recovery position on the outer periphery of each photoreceptor 41 . The recovery position is a position between each primary transfer position P1 on the outer periphery of each photoreceptor 41 and the charging position.

The recovery voltage output device 452 can apply a recovery bias voltage or a discharge bias voltage to the recovery member 451. Recovery voltage output device 452 is an example of a recovery voltage output section.

The recovery bias voltage has a polarity different from the charging polarity of the toner. The emission bias voltage has the same polarity as the charging polarity of the toner.

The collection voltage output device 452 applies the collection bias voltage to the collection member 451 in the toner collection process. As a result, the toner on the surface of the photoreceptor 41 is electrically attracted to the collection member 451 and held by the collection member 451. The toner collected by the collection member 451 is accumulated in a plurality of holes formed on the surface of the collection member 451.

On the other hand, the collection voltage output device 452 applies the discharge bias voltage to the collection member 451 in the toner discharge process. As a result, the toner held by the collection member 451 is electrically attracted to the surface of the photoreceptor 41 and is released from the collection member 451 onto the surface of the photoreceptor 41 .

When the print process is executed, the toner collection process is executed. By executing the toner collection process, toner that has not been transferred to the intermediate transfer belt 441 at each of the primary transfer positions P1 is collected by each of the collection members 451.

However, as the toner accumulates in the collection member 451, the toner collection performance of the collection member 451 deteriorates.

On the other hand, when a predetermined regeneration condition is satisfied in a situation where the print process is not being executed, the toner release process is executed. By executing the toner discharge process, the toner recovery performance of the recovery member 451 is improved.

By executing the toner release process, four release toner portions G1 are formed on the surfaces of the four photoreceptors 41 (see FIGS. 4 and 5). The four discharged toner portions G1 are transferred from the four photoreceptors 41 to the intermediate transfer belt 441.

The second cleaning device 444 removes toner from the portion of the intermediate transfer belt 441 that has passed through the secondary transfer position. For example, the second cleaning device 444 scrapes toner off the surface of the intermediate transfer belt 441 with a cleaning blade. The second cleaning device 444 is an example of a second cleaning section.

When the toner discharge process is executed, the four discharged toner portions G1 are removed from the intermediate transfer belt 441 by the second cleaning device 444.

The fixing device 46 applies pressure to the toner image on the sheet 9 while heating it. Thereby, the fixing device 46 fixes the toner image on the sheet 9.

The operating device 801 is a device that accepts human operations. For example, the operating device 801 includes operating buttons and a touch panel.

The display device 802 is a device that displays information. For example, display device 802 includes a panel display device such as a liquid crystal display unit.

The image forming apparatus 10 further includes a density sensor 5 (see FIG. 1). The density sensor 5 detects the density of the toner image in a portion of the surface of the intermediate transfer belt 441 that has passed through the secondary transfer position.

The density sensor 5 detects the density of the toner image at a position on the outer periphery of the intermediate transfer belt 441 between the secondary transfer position and the position of the second cleaning device 444.

For example, the concentration sensor 5 is a CIS (Contact Image Sensor). The density sensor 5 is an example of a density detection unit that detects the density of the toner image on the intermediate transfer member.

[Configuration of control device 8]
As shown in FIG. 2, the control device 8 includes a CPU (Central Processing Unit) 81, a RAM (Random Access Memory) 82, a secondary storage device 83, a signal interface 84, a communication device 85, and the like.

The secondary storage device 83 is a computer-readable nonvolatile storage device. The secondary storage device 83 can store and update computer programs and various data. For example, one or both of a flash memory and a hard disk drive may be employed as the secondary storage device 83.

The signal interface 84 converts signals output from various sensors into digital data, and transmits the converted digital data to the CPU 81. Further, the signal interface 84 converts the control command output by the CPU 81 into a control signal, and transmits the control signal to the device to be controlled.

The communication device 85 performs communication with other devices such as a host device (not shown). The CPU 81 communicates with the other devices through the communication device 85.

The CPU 81 is a processor that performs various data processing and control by executing the computer program. A control device 8 including a CPU 81 controls the sheet conveying device 3, the printing device 4, the display device 802, the communication device 85, and the like.

RAM 82 is a computer readable volatile storage device. The RAM 82 temporarily stores the computer program executed by the CPU 81 and data output and referred to during the process of the CPU 81 executing various processes.

The CPU 81 includes a plurality of processing modules realized by executing the computer program. The plurality of processing modules include a main processing section 8a, a job control section 8b, an adjustment control section 8c, and the like.

The main processing unit 8a executes processing for starting various processes in response to operations on the operating device 801, control of the display device 802, and the like.

The job control unit 8b controls the sheet conveyance device 3. Thereby, the job control section 8b controls the feeding of the sheet 9 from the sheet storage section 2 and the conveyance of the sheet 9 in the sheet conveyance path 30.

Further, the job control unit 8b controls the printing device 4. The job control unit 8b causes the printing device 4 to execute the printing process in synchronization with the conveyance of the sheet 9 by the sheet conveyance device 3.

The adjustment control unit 8c determines whether the reproduction condition is satisfied in a situation where the printing process is not executed. For example, the reproduction conditions include one or both of a print count condition and a remaining toner condition.

The print count condition is a condition that the number of page prints reaches a predetermined number based on the start of use of the image forming apparatus 10 or the time when the previous toner discharge process was executed. The page print is the print process on one page of the sheet 9.

The remaining toner condition is a condition that the density detected by the density sensor 5 when the printing process is executed exceeds the permissible density.

By the way, the four discharged toner portions G1 on the surface of the intermediate transfer belt 441 reach the second cleaning device 444 via the secondary transfer device 443. In the secondary transfer device 443, the secondary transfer body 4431 comes into contact with the four discharged toner portions G1.

When the four released toner portions G1 come into contact with the secondary transfer body 4431, the secondary voltage output device 4432 applies a reverse transfer bias voltage to the secondary transfer body 4431. The reverse transfer bias voltage has the same polarity as the charging polarity of the toner.

The process of applying the reverse transfer bias voltage to the secondary transfer body 4431 is a process for reducing the amount of toner adhering to the secondary transfer body 4431. Secondary voltage output device 4432 is an example of a secondary voltage output section.

When the toner release process is executed, a thick toner layer may be formed on the intermediate transfer belt 441 in some cases. In this case, even if the reverse transfer bias voltage is applied to the secondary transfer body 4431, the amount of toner adhering to the secondary transfer body 4431 may increase.

In this embodiment, the adjustment control unit 8c executes the regeneration control when the regeneration conditions are satisfied (see FIG. 3). The adjustment control unit 8c causes the first cleaning device 45 to execute the toner release process in the regeneration control.

[Playback control]
The adjustment control unit 8c executes the reproduction control when the reproduction condition is satisfied in a situation where the printing process is not executed.

The adjustment control unit 8c determines whether the reproduction condition is satisfied in a situation where the printing process is not executed. For example, the reproduction conditions include one or both of a print count condition and a remaining toner condition.

The number-of-prints condition is a condition that the number of times the page is printed reaches a predetermined number with reference to the time when the image forming apparatus 10 is started to be used or the time when the previous toner discharge process was executed.

The remaining toner condition is a condition that the density detected by the density sensor 5 when the printing process is executed exceeds the permissible density.

Hereinafter, an example of the reproduction control procedure will be described with reference to the flowchart shown in FIG. 3.

Note that the playback control is an example of a process that implements a method of controlling the image forming apparatus 10. The CPU 81 is an example of a processor that implements a method of controlling the image forming apparatus 10.

In the following description, S1, S2, . . . represent identification codes of a plurality of steps in the regeneration control. In the reproduction control, first, the processing of step S1 is executed.

<Step S1>
In step S1, the adjustment control unit 8c acquires four pixel number integrated values corresponding to the four monochrome image forming units 4x from the secondary storage device 83.

Each of the pixel number integrated values is an integrated value of the number of drawn pixels in the toner image formed on the surface of each of the four photoreceptors 41 by the image forming section. As described above, the image forming section includes four monochrome image forming sections 4x and an optical scanning device 40.

In this embodiment, the job control unit 8b calculates the four pixel number integrated values and records them in the secondary storage device 83 each time the printing device 4 executes the page printing. The adjustment control unit 8c initializes the pixel number integrated value when executing the reproduction control.

Each of the pixel count integrated values is an example of an index value of the amount of toner accumulated in the collection member 451 of each of the first cleaning devices 45. A large integrated value of the number of pixels indicates that the amount of accumulated toner is large.

After executing the process of step S1, the adjustment control unit 8c moves the process to step S2.

<Step S2>
In step S2, the adjustment control unit 8c sets the emission time according to the four integrated values of the number of pixels. The release time is a time period for the toner release process by the plurality of first cleaning units.

In this embodiment, the four primary transfer positions P1 are equally spaced. In FIGS. 4 to 7, the section distance D1 is the interval between the four primary transfer positions P1. In the following description, the time required for the four emitted toner portions G1 transferred to the surface of the intermediate transfer belt 441 to move the section distance D1 will be referred to as section movement time.

Further, a representative value of the four pixel number integrated values is referred to as a pixel number representative value. For example, the representative pixel number value is a maximum value, a weighted average value, or an average value of the four pixel number integrated values.

When the representative value of the number of pixels is within a predetermined reference range, the adjustment control unit 8c sets the section moving time or a time equal to or less than the section moving time as the emission time.

For example, the adjustment control unit 8c sets the section movement time as the emission time when the representative value of the number of pixels is within the reference range.

Further, when the pixel number representative value is within the reference range, the adjustment control unit 8c controls the adjustment control unit 8c to adjust the time period to be less than or equal to the section movement time according to the ratio between the pixel number representative value and the maximum value of the reference range. The release time may be set as the above-mentioned release time.

On the other hand, when the representative value of the number of pixels exceeds the reference range, the adjustment control unit 8c sets a time longer than the section movement time as the emission time.

For example, when the representative value of the number of pixels exceeds the reference range, the adjustment control unit 8c sets a time that is an integral multiple of the section movement time as the emission time.

More specifically, a plurality of classification ranges of values exceeding the reference range are set in advance. Each of the plurality of classification ranges is set to correspond to an integer of 2 or more.

The adjustment control unit 8c specifies a target range to which the pixel number representative value belongs among the plurality of classification ranges. Furthermore, the adjustment control unit 8c sets the time obtained by multiplying the section movement time by an integer corresponding to the target range as the release time.

After executing the process of step S2, the adjustment control unit 8c moves the process to step S3.

<Step S3>
In step S3, the adjustment control unit 8c causes each of the four first cleaning devices 45 to execute the toner release process for the release time set in step S2.

In step S3, the four first cleaning devices 45 execute the toner release process by applying the release bias voltage from the collection voltage output device 452 to the collection member 451.

By executing the toner release process, four release toner portions G1 are formed on the surfaces of the four photoreceptors 41. Furthermore, by executing the processes S4 and S5, which will be described later, the four discharged toner portions G1 are transferred onto the surface of the intermediate transfer belt 441 (see FIGS. 4 to 7).

The adjustment control unit 8c causes the four first cleaning devices 45 to eject the toner at a timing when the four ejected toner portions G1 do not overlap on the surface of the intermediate transfer belt 441 when the representative value of the number of pixels is within the reference range. Execute the process.

On the other hand, when the representative value of the number of pixels exceeds the reference range, the adjustment control unit 8c controls the four first cleaning devices 45 at the timing when the four emitted toner portions G1 partially overlap on the surface of the intermediate transfer belt 441. The toner release process is executed.

FIG. 4 shows four released toner portions G1 transferred to the surface of the intermediate transfer belt 441 in the first example of the process of step S3. FIG. 4 shows the four discharged toner portions G1 seen from above the intermediate transfer belt 441. As shown in FIG.

In FIGS. 4 to 7, the advancing direction DR1 is the moving direction of the portion of the intermediate transfer belt 441 along the plurality of primary transfer positions P1.

In the first example, the adjustment control unit 8c causes the four first cleaning devices 45 to simultaneously start the toner release process. Furthermore, the adjustment control unit 8c causes the four first cleaning devices 45 to end the toner release process when the release time has elapsed from the time when the four first cleaning devices 45 started the toner release process.

In the first example, the set release time is the section travel time. In the first example, the length L1 of each discharge toner portion G1 is equal to the section distance D1. Therefore, the four discharged toner portions G1 are continuous without overlapping on the surface of the intermediate transfer belt 441.

FIG. 5 shows four released toner portions G1 transferred to the surface of the intermediate transfer belt 441 in the second example of the process of step S3. FIG. 5 shows the four discharged toner portions G1 viewed from above the intermediate transfer belt 441. As shown in FIG.

In the second example, the adjustment control unit 8c causes the four first cleaning devices 45 to start the toner discharge process in a predetermined order at timings shifted by a set shift time. The predetermined order is an order in which the arrangement position is prioritized on the upstream side in the traveling direction DR1 (see FIG. 5). The traveling direction DR1 is the moving direction of the portion of the intermediate transfer belt 441 along the plurality of primary transfer positions P1.

In the second example, the adjustment control unit 8c causes the four first cleaning devices 45 to release the toner when the set release time has elapsed from the time when the four first cleaning devices 45 sequentially started the toner release process. Finish the processing in sequence.

In the second example, the set release time is shorter than the section movement time. Therefore, the length L1 of each discharged toner portion G1 is shorter than the section distance D1. Further, the sum of the set shift time and the set discharge time is the section movement time. As a result, the four discharged toner portions G1 are continuous on the surface of the intermediate transfer belt 441 without overlapping.

Since the four discharged toner portions G1 are connected on the surface of the intermediate transfer belt 441, the time required for the four discharged toner portions G1 to be removed by the second cleaning device 444 is shortened.

FIG. 6 shows four released toner portions G1 transferred to the surface of the intermediate transfer belt 441 in the third example of the process of step S3. FIG. 6 shows the four discharged toner sections G1 as seen from the side of the intermediate transfer belt 441. As shown in FIG.

In the following description, two of the four discharged toner portions G1 that are transferred from two adjacent photoreceptors 41 to the intermediate transfer belt 441 are referred to as two continuously discharged toner portions.

In the third example, the adjustment control unit 8c causes the four first cleaning devices 45 to simultaneously start the toner release process. Furthermore, the adjustment control unit 8c causes the four first cleaning devices 45 to end the toner release process when the release time has elapsed from the time when the four first cleaning devices 45 started the toner release process.

In the third example, the set release time is twice the section movement time. In the third example, the length L1 of each discharged toner portion G1 is twice the section distance D1. Therefore, the two continuous toner portions are formed to overlap on the surface of the intermediate transfer belt 441 by a length equal to the section distance D1.

FIG. 7 shows four released toner portions G1 transferred to the surface of the intermediate transfer belt 441 in the fourth example of the process of step S3. FIG. 7 shows the four discharged toner portions G1 viewed from the side of the intermediate transfer belt 441.

In the fourth example, the adjustment control unit 8c causes the four first cleaning devices 45 to simultaneously start the toner release process. Furthermore, the adjustment control unit 8c causes the four first cleaning devices 45 to end the toner release process when the release time has elapsed from the time when the four first cleaning devices 45 started the toner release process.

In the fourth example, the set release time is three times the section movement time. In the fourth example, the length L1 of each discharged toner portion G1 is three times the length of the section distance D1. Therefore, the two continuous toner portions are formed to overlap on the surface of the intermediate transfer belt 441 by a length twice the section distance D1.

Note that the third example and the fourth example are cases in which the four discharged toner portions G1 partially overlap each other on the surface of the intermediate transfer belt 441.

After executing the process of step S3, the adjustment control unit 8c moves the process to step S4.

<Step S4>
In step S4, the adjustment control section 8c executes roller retraction control when each of the four discharged toner sections G1 passes through the development position of each monochrome image forming section 4x.

The roller retraction control is a control that causes the roller moving mechanism 433 to perform an operation of moving the developing rollers 431 of the four developing devices 43 from the development position to the retraction position. By executing the roller retraction control, the developing rollers 431 of the four developing devices 43 are held at the retracted position.

The process in step S4 is a process for causing the roller moving mechanism 433 to hold the developing rollers 431 of the four developing devices 43 at the retracted position. After executing the process of step S4, the adjustment control unit 8c moves the process to step S5.

<Step S5>
In step S5, the adjustment control unit 8c causes the four primary transfer devices 442 to execute the primary transfer process for the four discharged toner portions G1.

The primary transfer process for the four released toner parts G1 is a process of transferring the four released toner parts G1 formed on the surfaces of the four photoreceptors 41 by the toner release process to the intermediate transfer belt 441.

After executing the process of step S5, the adjustment control unit 8c moves the process to step S6.

<Step S6>
In step S6, the adjustment control unit 8c determines whether the four discharged toner portions G1 are in the secondary position passing state or in the secondary position non-passing state.

The secondary position passing state is a state in which any one of the four discharged toner portions G1 is passing through the secondary transfer position. The secondary position non-passing state is a state in which the non-transfer area on the surface of the intermediate transfer belt 441 passes through the secondary transfer position. The non-transfer area is an area where none of the plurality of discharged toner parts G1 is transferred.

When the adjustment control section 8c determines that the four discharged toner sections G1 are in the secondary position passing state, the adjustment control section 8c shifts the process to step S7. On the other hand, when the adjustment control section 8c determines that the four discharged toner sections G1 are not passing through the secondary position, the adjustment control section 8c shifts the process to step S8.

<Step S7>
In step S7, the adjustment control unit 8c causes the secondary voltage output device 4432 to execute a process of outputting the reverse transfer bias voltage. As a result, the reverse transfer bias voltage is applied to the secondary transfer body 4431.

After executing the process of step S7, the adjustment control unit 8c moves the process to step S6.

<Step S8>
In step S8, the adjustment control unit 8c causes the secondary voltage output device 4432 to execute a process of outputting the secondary transfer bias voltage. As a result, the secondary transfer bias voltage is applied to the secondary transfer body 4431.

The secondary transfer bias voltage is an example of a forward transfer bias voltage having a polarity different from the charging polarity of the toner.

Each of the discharged toner portions G1 may contain oppositely charged toner charged to a polarity opposite to the charged polarity of the toner. The oppositely charged toner tends to adhere to the secondary transfer body 4431 through the process in step S7.

The process in step S8 is a process for returning the oppositely charged toner from the secondary transfer body 4431 to the intermediate transfer belt 441. After executing the process of step S8, the adjustment control unit 8c moves the process to step S9.

<Step S9>
In step S9, the adjustment control unit 8c determines whether the condition for ending the regeneration control is satisfied or not.

For example, the termination condition is that the intermediate transfer belt 441 has rotated at least once after all four discharged toner portions G1 have passed through the secondary transfer position.

When the adjustment control unit 8c determines that the termination condition is not satisfied, the adjustment control unit 8c shifts the process to step S6. On the other hand, the adjustment control unit 8c terminates the reproduction control when determining that the termination condition is satisfied.

The adjustment control unit 8c may perform the processing of steps S1 to S8 multiple times in the regeneration control. In this case, the termination condition also includes the condition that the processes of steps S1 to S8 have been executed a predetermined number of times.

In this embodiment, when the amount of toner accumulated in the collection member 451 is not large, the four discharged toner portions G1 do not overlap on the surface of the intermediate transfer belt 441. Therefore, formation of a thick toner layer on the surface of the intermediate transfer belt 441 is avoided. As a result, the amount of toner adhering to the secondary transfer body 4431 is reduced.

Further, in step S3, if the set discharge time is equal to the section movement time, the four discharge toner portions G1 are continuous without overlapping on the surface of the intermediate transfer belt 441 (see FIG. 4). Thereby, the thickness of each of the four discharged toner portions G1 can be reduced without reducing the amount of toner discharged from each collection member 451.

On the other hand, in this embodiment, when the amount of toner accumulated in the collection member 451 is large, a stacked toner portion is formed on the surface of the intermediate transfer belt 441. The laminated toner portion is a portion where all or part of the four discharged toner portions G1 overlap.

However, the four discharged toner portions G1 partially overlap each other on the surface of the intermediate transfer belt 441. Thereby, the thickness of the laminated toner portion is reduced as much as possible.

That is, the thickness of each of the four discharged toner parts G1 on the surface of the intermediate transfer belt 441 or the thickness of the laminated toner part is reduced. This reduces the amount of toner adhering to the secondary transfer body 4431.

In the present embodiment, the reproduction condition may include a first toner amount condition regarding the four pixel number integrated values. For example, the first toner amount condition is that at least one of the four pixel number integrated values exceeds a predetermined reference value.

[Second embodiment]
Next, an image forming apparatus 10A according to a second embodiment will be described with reference to FIG. 8.

The image forming apparatus 10A includes a configuration in which a plurality of current measuring units 453 are added to the image forming apparatus 10. In this embodiment, the image forming apparatus 10A includes four current measuring units 453 corresponding to the four first cleaning devices 45.

Each of the current measurement units 453 is a circuit that measures the current flowing through the recovery member 451 of each of the four first cleaning devices 45.

In each of the first cleaning devices 45, when the amount of toner accumulated in the collection member 451 increases, the current flowing through the collection member 451 when the toner collection process is executed decreases.

That is, the measured current of each of the four current measuring units 453 is an example of an index value of the amount of toner accumulated in the collecting member 451 of each of the first cleaning devices 45.

For example, the job control unit 8b records the latest measured current value of each of the four current measurement units 453 in the secondary storage device 83 every time the toner collection process is executed.

The adjustment control unit 8c of this embodiment acquires the four measured current values from the secondary storage device 83 in the reproduction control step S1. Hereinafter, a representative value of the four measured current values will be referred to as a representative measured current value. For example, the representative value is a minimum value, a weighted average value, or an average value.

Further, the adjustment control unit 8c of the present embodiment sets the emission time according to the four representative measured current values in step S2 of the regeneration control. For example, the adjustment control unit 8c sets the emission time according to the representative measured current value.

When the representative measured current value is within a predetermined reference range, the adjustment control unit 8c sets the section moving time or a time equal to or less than the section moving time as the emission time.

On the other hand, when the representative measured current value is below the reference range, the adjustment control unit 8c sets a time longer than the section movement time as the emission time. For example, the adjustment control unit 8c sets the release time as in the first embodiment.

For example, when the representative measured current value is below the reference range, the adjustment control unit 8c sets a time that is an integral multiple of the section movement time as the emission time. For example, the adjustment control unit 8c sets the release time as in the first embodiment.

In the present embodiment, the reproduction conditions may include a second toner amount condition regarding the measured current of each of the four current measuring units 453. For example, the second toner amount condition is a condition that at least one of the measured currents of each of the four current measuring units 453 when the toner collection process was most recently executed is less than a predetermined reference value.

When the image forming apparatus 10A is employed, the same effects as when the image forming apparatus 10 is employed can be obtained.

[First application example]
Next, a first application example of the image forming apparatuses 10 and 10A will be described.

In step S3 of the reproduction control, the adjustment control unit 8c causes each of the four first cleaning devices 45 to execute a first bias up process when the representative value of the number of pixels exceeds the reference range.

The first bias up process is a process of increasing the level of the ejection bias voltage every time the section movement time elapses in the toner ejection process.

Further, in step S3 of the regeneration control, the adjustment control unit 8c causes each of the four first cleaning devices 45 to execute the first bias up process when the representative measured current value is below the reference range. Good too.

Under the condition where the constant discharge bias voltage is applied to the collection member 451, as the amount of toner accumulated in the collection member 451 decreases, the amount of toner discharged per unit time from the collection member 451 decreases.

On the other hand, by increasing the level of the discharge bias voltage, the efficiency of toner discharge from the collection member 451 to the photoreceptor 41 is improved. By executing the first bias up process, variations in the thickness of each of the four discharged toner portions G1 are reduced.

[Second application example]
Next, a second application example of the image forming apparatuses 10 and 10A will be described.

In step S3 of the regeneration control, the adjustment control unit 8c causes each of the four first cleaning devices 45 to execute a second bias up process. The second bias up process is a process of increasing the level of the discharge bias voltage according to the elapsed time in the toner discharge process.

For example, the second bias up process is a process in which the level of the ejection bias voltage is increased by a unit amount per unit time in the toner ejection process. The unit time is shorter than the section travel time.

By executing the second bias up process, variations in the thickness of each of the four discharged toner parts G1 are reduced, similarly to when the first bias up process is executed.

[Third application example]
Next, a third application example of the image forming apparatuses 10 and 10A will be described.

In this application example, the developing device 43 is an interactive touch-down developing type or jumping developing type device.

In this application example, the developing device 43 does not include the roller moving mechanism 433. The adjustment control unit 8c does not cause the developing voltage output devices 432 of the four monochrome image forming units 4x to output voltage in the reproduction control step S4. This prevents the toner constituting each discharged toner portion G1 from transferring to each developing device 43.

4: Printing device 5: Density sensor 10, 10A: Image forming device 40: Optical scanning device 41: Photoreceptor (image carrier)
42: Charging device 43: Developing device 44: Transfer device 45: First cleaning device 421: Charging member 422: Charging voltage output device 431: Developing roller 432: Developing voltage output device 433: Roller moving mechanism 441: Intermediate transfer belt 442: Primary transfer device 443 : Secondary transfer device 444 : Second cleaning device 451 : Recovery member 452 : Recovery voltage output device 453 : Current measuring section 4421 : Primary transfer body 4422 : Primary voltage output device 4431 : Secondary transfer body 4432 : Second Next voltage output device

Claims (8)

A method for controlling an image forming apparatus, the method comprising:
The image forming apparatus includes:
an image forming section that includes a plurality of rotating image carriers and is capable of forming toner images on surfaces of the plurality of image carriers;
an intermediate transfer member that rotates while contacting the plurality of image carriers;
a plurality of primary transfer parts each capable of performing a primary transfer process of transferring toner on the surface of the plurality of image carriers to the surface of the intermediate transfer body at a plurality of primary transfer positions along the intermediate transfer body;
a secondary transfer unit capable of performing a secondary transfer process of transferring the toner transferred to the surface of the intermediate transfer body to a sheet;
A toner collection process for collecting the toner on the surface of each of the plurality of image carriers in a portion of the surface of each of the plurality of image carriers that has passed through each of the plurality of primary transfer portions; a plurality of first cleaning units capable of performing a toner release process that releases the toner to a surface;
a second cleaning section that removes the toner from a portion of the surface of the intermediate transfer body that has passed through the secondary transfer section;
Each of the plurality of first cleaning parts includes:
a collection member capable of rotating while contacting the surface of each of the plurality of image carriers and retaining the toner;
In the toner recovery process, a recovery bias voltage having a polarity different from the charge polarity of the toner is applied to the recovery member, and in the toner release process, a discharge bias voltage having the same polarity as the charge polarity of the toner is applied to the recovery member. A voltage output section;
The secondary transfer section is
a secondary transfer body that rotates while contacting the surface of the intermediate transfer body;
a secondary voltage output unit capable of applying a bias voltage to the secondary transfer body,
The control method includes:
the processor acquires an index value of the amount of toner accumulated in the collection member of the plurality of first cleaning units;
the processor sets a discharge time according to the index value, and causes the plurality of first cleaning units to execute the toner discharge process for the discharge time;
The processor causes the plurality of primary transfer units to perform the primary transfer process on the plurality of released toner parts formed on the surfaces of the plurality of image carriers by the toner release process;
The processor applies a reverse transfer bias voltage having the same polarity as the charge polarity of the toner when each of the plurality of emitted toner portions transferred to the surface of the intermediate transfer member passes through the position of the secondary transfer member. outputting to the secondary voltage output section,
The processor sets a predetermined section travel time or a time less than or equal to the section travel time as the release time when the index value is within the reference range, and when the index value falls outside the reference range. , setting a time longer than the section travel time as the release time;
The section movement time is the time required for the plurality of emitted toner portions transferred to the surface of the intermediate transfer body to move a section distance that is an interval between the plurality of primary transfer positions,
When the index value is within the reference range, the processor causes the plurality of first cleaning units to execute the toner discharge process at a timing when the plurality of discharge toner parts do not overlap on the surface of the intermediate transfer body. ,
When the index value deviates from the reference range, the processor executes the toner release process on the plurality of first cleaning units at a timing when the plurality of release toner units partially overlap each other on the surface of the intermediate transfer body. A method for controlling an image forming apparatus. 2. The method of controlling an image forming apparatus according to claim 1, wherein the processor sets a time that is an integral multiple of the section movement time as the release time when the index value deviates from the reference range. 3. The processor according to claim 1, wherein the processor obtains, as the index value, an integrated value of the number of drawn pixels in the toner image formed on the surface of each of the plurality of image carriers by the image forming unit. A method for controlling an image forming apparatus. When the image forming apparatus includes a plurality of current measuring units that measure the current flowing through the collecting member of each of the plurality of first cleaning units,
3. The method of controlling an image forming apparatus according to claim 1, wherein the processor obtains a measured current value of each of the plurality of current measuring units as the index value. When the index value deviates from the reference range, the processor increases the level of the ejection bias voltage for each of the plurality of first cleaning units each time the section movement time elapses in the toner ejection process. 5. The method for controlling an image forming apparatus according to claim 4, wherein: When the processor passes through the position of the secondary transfer body, a non-transfer area on the surface of the intermediate transfer body where none of the plurality of emitted toner parts are transferred, the charge polarity of the toner is different from that of the toner. 6. The method of controlling an image forming apparatus according to claim 1, further comprising causing the secondary voltage output unit to output a polar forward transfer bias voltage. The image forming section
a plurality of developing rollers each supplying the toner to the plurality of image carriers at a development position on the outer periphery of the plurality of image carriers;
a roller moving mechanism that moves the plurality of developing rollers between the developing position and a retracted position farther from the plurality of image carriers than the developing position;
The processor causes the roller moving mechanism to hold the plurality of developing rollers at the retracted position when the plurality of emitted toner portions formed on the surfaces of the plurality of image carriers pass through the developing position. 7. The method of controlling an image forming apparatus according to claim 1, further comprising the steps of: . an image forming section that includes a plurality of rotating image carriers and is capable of forming toner images on surfaces of the plurality of image carriers;
an intermediate transfer member that rotates while contacting the plurality of image carriers;
a plurality of primary transfer units each capable of performing a primary transfer process of transferring toner on the surface of the plurality of image carriers to the surface of the intermediate transfer body;
a secondary transfer unit capable of performing a secondary transfer process of transferring the toner transferred to the surface of the intermediate transfer body to a sheet;
A toner recovery process for collecting the toner on the surface of each of the plurality of image carriers at a portion of the surface of each of the plurality of image carriers that has passed through each of the plurality of primary transfer portions, and each of the plurality of image carriers. a plurality of first cleaning units capable of performing a toner release process of releasing the toner onto the surface of the cleaning unit;
a second cleaning section that removes the toner from a portion of the surface of the intermediate transfer body that has passed through the secondary transfer section;
A processor that implements the method for controlling an image forming apparatus according to any one of claims 1 to 7,
Each of the plurality of first cleaning parts,
a collection member capable of rotating while contacting the surface of each of the plurality of image carriers and retaining the toner;
In the toner recovery process, a recovery bias voltage having a polarity different from the charge polarity of the toner is applied to the recovery member, and in the toner release process, a discharge bias voltage having the same polarity as the charge polarity of the toner is applied to the recovery member. A voltage output section;
The secondary transfer section is
a secondary transfer body that rotates while contacting the surface of the intermediate transfer body;
An image forming apparatus comprising: a secondary voltage output section capable of applying a bias voltage to the secondary transfer body.

Images