JP2023162673A - Method for adjusting image forming apparatus, and image forming apparatus - Google Patents

Abstract

To execute adjustment processing according to a cause of image fogging.SOLUTION: A processor 81 acquires first target density for a first specific transfer area detected by a main density detection unit 5a (S2). The processor 81 acquires second target density for a second specific transfer area detected by the main density detection unit 5a (S7). The processor 81 selects processing to execute from a plurality of adjustment processing candidates according to the first target density and the second target density (S11, S12). A first specific developing area is an area with no image passing through a developing position when a developing unit 43 is in an operating state. The first specific transfer area is an area corresponding to the first specific developing area in the transfer area. A second specific developing area is an area with no image passing through the developing position when the developing unit 43 is in a non-operating state. The second specific transfer area is an area corresponding to the second specific developing area in the transfer area.SELECTED DRAWING: Figure 4

Description

The present invention relates to an adjustment method for an image forming apparatus and an image forming apparatus for executing adjustment processing according to the cause of image fog.

An electrophotographic image forming apparatus includes a photoreceptor, a charging section, an exposure section, a developing section, a transfer section, and a cleaning section.

The charging unit charges the surface of the rotating photoreceptor. The exposure section writes an electrostatic latent image on the charged surface of the photoreceptor. The developing section develops the electrostatic latent image into a toner image by supplying toner to the surface of the photoreceptor.

The transfer section transfers the toner image formed on the surface of the photoreceptor to the surface of a sheet. The cleaning section removes residual toner from the surface of the photoreceptor.

The transfer section may include an intermediate transfer body, a primary transfer section, and a secondary transfer section. The primary transfer section transfers the toner image formed on the surface of the photoreceptor to the surface of the intermediate transfer member. The secondary transfer section transfers the toner image transferred onto the surface of the intermediate transfer body to the sheet.

Image fogging may occur on the surface of the photoreceptor. The image fog is a phenomenon in which toner adheres to areas on the surface of a photoreceptor where toner images should not be formed.

The image forming apparatus includes a density detection section that detects toner density on the surface of the photoreceptor or the intermediate transfer member. The density detection section can detect the image fog.

That is, when the image fog occurs, the density detection section detects a toner density that exceeds the permissible density in a background area on the surface of the photoreceptor or a part corresponding to the background area on the surface of the intermediate transfer body. To detect.

The background portion is a portion of the development area on the surface of the photoreceptor where the toner image is not formed.

Furthermore, it is known to adjust the transfer current in the transfer section when the image fog is detected by the density detection section (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2013-137401

Incidentally, the cause of the image fogging is considered to be a defective condition of the developing section and a defective condition of the cleaning section. Therefore, an appropriate adjustment process for the image fog differs depending on the cause of the image fog.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and an adjustment method for an image forming apparatus that can perform adjustment processing depending on the cause of image fog.

A method for adjusting an image forming apparatus according to one aspect of the present invention is such that the image forming apparatus includes a rotating photoreceptor, a charging section, an exposing section, a developing section, a transfer section, a cleaning section, a main density This is realized when the detection unit includes a detection unit. The charging section charges the surface of the photoreceptor. The exposure section writes an electrostatic latent image on the charged surface of the photoreceptor. The developing section develops the electrostatic latent image into a toner image by supplying toner to a development area on the surface of the photoreceptor at a development position on the outer periphery of the photoreceptor. The transfer unit transfers the toner image formed on the surface of the photoreceptor to a transfer area on the surface of the sheet or the intermediate transfer member at a transfer position on the outer periphery of the photoreceptor. The cleaning section removes residual toner from a portion of the surface of the photoreceptor that has passed through the transfer position. The main density detection section is capable of detecting toner density in the development area of the photoconductor or the transfer area of the intermediate transfer body. The developing section is capable of switching from one of an operating state in which the toner can be supplied to the surface of the photoconductor and a non-operating state in which the toner cannot be supplied to the surface of the photoconductor to the other according to a control command. . The adjustment method includes a processor controlling the developing section to the operating state by outputting the control command. Further, in the adjustment method, the processor detects a first target density detected by the main density detection unit for a first specific development area of the development area or a first specific transfer area of the transfer area by the main density detection. Including obtaining from the department. Furthermore, the adjustment method includes the processor controlling the developing section to the non-operating state by outputting the control command. Further, in the adjustment method, the processor detects a second target density detected by the main density detection unit for a second specific development area of the development area or a second specific transfer area of the transfer area by the main density detection. Including obtaining from the department. Further, the adjustment method includes the processor selecting a process to be executed from a plurality of adjustment process candidates according to the first target density and the second target density. The first specific development area is a non-image area in the development area that passes through the development position when the development section is in the operating state. The first specific transfer area is an area corresponding to the first specific development area in the transfer area. The second specific development area is a non-image area in the development area that passes through the development position when the development section is in the non-operating state. The second specific transfer area is an area corresponding to the second specific development area in the transfer area.

The image forming apparatus according to another aspect of the present invention includes the photoconductor, the charging section, the exposing section, the developing section, the transferring section, the cleaning section, and the main density detecting section. and the processor that implements the adjustment method.

According to the present invention, it is possible to provide an adjustment method for an image forming apparatus and an image forming apparatus that can perform adjustment processing according to the cause of image fog.

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 plan view showing an intermediate transfer belt and two density sensors in the image forming apparatus according to the first embodiment. FIG. 4 is a flowchart illustrating an example of the procedure of image quality adjustment processing in the image forming apparatus according to the first embodiment. FIG. 5 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 an exposure section.

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 on its surface.

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. Each photoreceptor 41 is an example of an image carrier that carries 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.

A magnetic brush is formed on the surface of the developing roller 431 by the magnetic carrier carrying the toner. The developing roller 431 supplies the charged toner to the surface of the photoreceptor 41 using the magnetic brush.

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, each developing device 43 further includes a roller moving mechanism 433. The roller moving mechanism 433 moves the developing roller 431 between the developing position and the retracted position according to a control command received from 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. The developing roller 431 cannot supply toner to the photoreceptor 41 when it is in the retracted position.

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.

In each of the developing devices 43, a state in which the developing roller 431 is held at the developing position is an operating state in which the toner can be supplied to the surface of the photoreceptor 41. On the other hand, in each of the developing devices 43, a state in which the developing roller 431 is held at the retracted position is a non-operating state in which the toner cannot be supplied to the surface of the photoreceptor 41.

That is, each of the developing devices 43 can be switched from one of the operating state and the non-operating state to the other according to the control command.

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 positions P1 is a position on the outer periphery of each of the photoreceptors 41.

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.

Each of the first cleaning devices 45 is an example of a cleaning unit that removes residual toner from a portion of the surface of each photoreceptor 41 that has passed through the primary transfer position P1.

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 to the recovery member 451. The recovery bias voltage has a polarity different from 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.

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 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 two density sensors 5a and 5b (see FIGS. 1 and 3). The two density sensors 5a and 5b detect the toner density of a portion of the surface of the intermediate transfer belt 441 that has passed through the secondary transfer position.

The two density sensors 5a and 5b are arranged between the secondary transfer position on the outer periphery of the intermediate transfer belt 441 and the position of the second cleaning device 444.

Each of the two concentration sensors 5a and 5b includes a light emitting section and a photoelectric conversion element. The light emitting section irradiates the surface of the intermediate transfer belt 441 with light. The photoelectric conversion element receives light diffusely reflected by the intermediate transfer belt 441 and outputs a detection signal representing the amount of received light. The level of the detection signal represents the toner concentration.

[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 executes an image quality adjustment process, which will be described later, when the print process is not being executed (see FIG. 4).

The adjustment control unit 8c determines the occurrence of image fogging on the surface of each photoreceptor 41 in the image quality adjustment process. Further, the adjustment control section 8c adjusts each of the monochrome image forming sections 4x when determining that the image fogging has occurred.

Incidentally, the cause of the image fogging is thought to be a defective condition of the developing device 43 and a defective condition of the first cleaning device 45. Therefore, an appropriate adjustment process for the image fog differs depending on the cause of the image fog.

The adjustment control unit 8c executes the image quality adjustment process according to the procedure shown in FIG. 4, for example. Thereby, it is possible to perform adjustment processing according to the cause of the image fog.

[Image quality adjustment processing]
The adjustment control unit 8c starts the image quality adjustment process when a predetermined adjustment start condition is satisfied. For example, the adjustment start condition includes a condition that the image forming apparatus 10 has been started.

Further, the adjustment start condition includes a condition that the cumulative number of printed sheets has reached a reference number of sheets when the print processing job is completed. The count value of the cumulative number of prints is reset each time the image quality adjustment process is executed.

Note that other conditions may be included in the adjustment start conditions.

Hereinafter, an example of the procedure of the image quality adjustment process will be described with reference to the flowchart shown in FIG. 4. The adjustment control unit 8c executes the image quality adjustment process for each monochrome image forming unit 4x.

Note that the image quality adjustment process is an example of a process that implements an adjustment method for the image forming apparatus 10. The CPU 81 is an example of a processor that implements the adjustment method of the image forming apparatus 10.

In the following description, S1, S2, . . . represent identification codes of a plurality of steps in the image quality adjustment process. In the image quality adjustment process, first, the process of step S1 is executed.

<Step S1>
In step S1, the adjustment control unit 8c executes first non-printing control.

The first non-printing control includes control for causing the charging device 42, the developing device 43, the primary transfer device 442, and the first cleaning device 45 to perform normal processing. Furthermore, the first non-printing control includes control for causing the secondary transfer device 443 to perform non-transfer processing.

The normal processing is the same processing as that of the charging device 42, the developing device 43, the primary transfer device 442, and the first cleaning device 45 when the printing processing is executed.

That is, the normal process of the charging device 42 is a process of charging the surface of the photoreceptor 41 by outputting the charging bias voltage. Further, the normal process of the developing device 43 is a process of applying the developing bias voltage to the developing roller 431 while holding the developing roller 431 at the developing position.

The adjustment control unit 8c outputs the control command to the roller moving mechanism 433 to maintain the developing roller 431 at the developing position. As a result, the developing device 43 is controlled to the operating state. The developing device 43 is capable of supplying the toner to the surface of the photoreceptor 41 in the operating state.

The normal process of the primary transfer device 442 is a process of applying the primary transfer bias voltage to the primary transfer body 4421. The normal process of the first cleaning device 45 is a process of applying the recovery bias voltage to the recovery member 451.

In the following description, a defective state in which the developing device 43 causes image fogging will be referred to as a developing defective state. Furthermore, a state in which the first cleaning device 45 is in a defective state that causes the image fogging is referred to as a cleaning defect state.

If the poor development state occurs, noise toner due to the poor development state adheres to the surface of the photoreceptor 41 by executing the process of step S1.

Similarly, when the poor cleaning state occurs, noise toner caused by the poor cleaning state adheres to the surface of the photoreceptor 41 by executing the processing in step S1.

The noise toner adheres to the development area A1 on the surface of the photoreceptor 41 (see FIG. 3). The developing area A1 is an area to which the developing device 43 can supply toner in the main scanning direction.

In this embodiment, the development area A1 is an area on the surface of the photoreceptor 41 that the magnetic brush on the development roller 431 comes into contact with.

Further, the noise toner is transferred from the development area A1 on the surface of the photoreceptor 41 to the transfer area A2 on the surface of the intermediate transfer belt 441 when the process of step S1 is executed (see FIG. 3). The transfer area A2 is an area in the main scanning direction that corresponds to the development area A1.

On the other hand, the non-transfer process is a process in which a reverse transfer bias voltage is applied to the secondary transfer body 4431. The polarity of the reverse transfer bias voltage is the same as the charging polarity of the toner.

By performing the non-transfer process, the noise toner transferred to the transfer area A2 on the surface of the intermediate transfer belt 441 is removed by the second cleaning device 444 after passing through the secondary transfer position.

As shown in FIG. 3, the two concentration sensors 5a and 5b include a first concentration sensor 5a and a second concentration sensor 5b.

The first density sensor 5a is arranged at a position where it can detect the toner density in the transfer area A2 on the surface of the intermediate transfer belt 441. Therefore, the first density sensor 5a can detect the density of the noise toner caused by the poor development state or the poor cleaning state.

On the other hand, the second density sensor 5b is arranged at a position where it can detect the toner density in the non-transfer area A3 on the surface of the intermediate transfer belt 441. The non-transfer area A3 is an area other than the transfer area A2 on the surface of the intermediate transfer belt 441.

The second density sensor 5b outputs a detection signal reflecting the state of light reflection on the surface of the intermediate transfer belt 441, which may vary due to factors unrelated to the image fog. For example, the detection signal from the second density sensor 5b represents the state of the surface of the intermediate transfer belt 441, such as the material and surface roughness.

Note that the first concentration sensor 5a is an example of a main concentration detection section. The second concentration sensor 5b is an example of a reference concentration detection section.

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

In the following description, the non-image area in the development area A1 on the surface of the photoreceptor 41 will be referred to as a primary non-image area A10 (see FIG. 3).

Further, an area corresponding to the primary non-image area A10 in the transfer area A2 on the surface of the intermediate transfer belt 441 is referred to as a secondary non-image area A20 (see FIG. 3). The secondary non-image area A20 passes through the primary transfer position P1 at the same time as the primary non-image area A10.

The primary non-image area A10 and the secondary non-image area A20 are areas where the toner image G1 is not formed. The noise toner existing in the primary non-image area A10 is transferred to the secondary non-image area A20.

<Step S2>
In step S2, the adjustment control unit 8c obtains the first target concentration from the first concentration sensor 5a. The first target density is the toner density detected in the first specific transfer area on the surface of the intermediate transfer belt 441 by the first density sensor 5a.

Here, the primary non-image area A10 passing through the developing position when the developing device 43 is in the operating state is referred to as a first specific developing area. The first specific transfer area is a secondary non-image area A20 corresponding to the first specific development area in the transfer area A2.

That is, when the secondary non-image area A20 corresponding to the primary non-image area A10 that has passed through the development position when the developing device 43 is in the operating state reaches the position of the first density sensor 5a, the adjustment control section 8c acquires the detection value of the first concentration sensor 5a.

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 obtains the first reference density from the second density sensor 5b.

The first reference density is the toner density detected by the second density sensor 5b when the adjustment control unit 8c obtains the first target density.

Note that the processes in step S2 and step S3 may be performed in the reverse order to the order shown in FIG. 4. Moreover, the processes of step S2 and step S3 may be performed simultaneously.

After executing the processes of steps S2 and S3, the adjustment control unit 8c moves the process to step S4.

<Step S4>
In step S4, the adjustment control unit 8c derives a first comparison value representing the result of comparing the first target density and the first reference density. The first comparison value represents the magnitude of the first target density based on the first reference density.

For example, the first comparison value is the difference between the first target density and the first reference density. Further, the first comparison value may be a ratio of the first target density to the first reference density.

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 determines the level of the first comparison value, and selects a destination of processing according to the determination result.

Specifically, the adjustment control unit 8c ends the image quality adjustment process when the first comparison value is within a predetermined tolerance range. In this embodiment, the permissible range is a range below a predetermined reference upper limit.

On the other hand, when the first comparison value exceeds the allowable range, the adjustment control unit 8c causes the process to proceed to step S6. A state in which the first comparison value exceeds the allowable range is a state in which the noise toner is considered to be attached to the surface of the photoreceptor 41.

<Step S6>
In step S6, the adjustment control unit 8c executes second non-printing control.

The second non-printing control includes control for causing the charging device 42, the primary transfer device 442, and the first cleaning device 45 to execute the normal processing.

Further, the second non-printing control includes controlling the developing device 43 to the non-operating state. Furthermore, the first non-print control includes control for causing the secondary transfer device 443 to execute the non-transfer process.

The adjustment control unit 8c outputs the control command to the roller moving mechanism 433 to maintain the developing roller 431 at the retracted position. As a result, the developing device 43 is controlled to the non-operating state. The developing device 43 cannot supply the toner to the surface of the photoreceptor 41 in the non-operating state.

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

<Step S7>
In step S7, the adjustment control unit 8c obtains the second target concentration from the first concentration sensor 5a. The second target density is the toner density detected in the second specific transfer area on the surface of the intermediate transfer belt 441 by the first density sensor 5a.

Here, the primary non-image area A10 passing through the development position when the developing device 43 is in the non-operating state is referred to as a second specific development area. The second specific transfer area is a secondary non-image area A20 corresponding to the second specific development area in the transfer area A2.

That is, when the secondary non-image area A20 corresponding to the primary non-image area A10 that passed through the development position when the developing device 43 is in the non-operating state reaches the position of the first density sensor 5a, the adjustment control is performed. The unit 8c acquires the detected value of the first concentration sensor 5a.

After executing the process of step S7, the adjustment control unit 8c moves the process to step S8.

<Step S8>
In step S8, the adjustment control unit 8c obtains the second reference density from the second density sensor 5b.

The second reference density is the toner density detected by the second density sensor 5b when the adjustment control unit 8c obtains the second target density.

Note that the processes in step S7 and step S8 may be performed in the reverse order to the order shown in FIG. 4. Moreover, the processes of step S7 and step S8 may be performed simultaneously.

After executing the processes of steps S7 and S8, the adjustment control unit 8c moves the process to step S9.

<Step S9>
In step S9, the adjustment control unit 8c derives a second comparison value representing the result of comparing the second target density and the second reference density. The second comparison value represents the magnitude of the second target density based on the second reference density.

For example, the second comparison value is the difference between the second target density and the second reference density. Further, the second comparison value may be a ratio of the second target density to the second reference density.

After executing the process of step S9, the adjustment control unit 8c moves the process to step S10.

<Step S10>
In step S10, the adjustment control unit 8c determines the level of the second comparison value, and selects a destination of processing according to the determination result.

Specifically, the adjustment control unit 8c causes the process to proceed to step S11 when the second comparison value is within the allowable range.

In step S11, the fact that the second comparison value is within the allowable range means that the noise toner occurs when the developing device 43 is in the operating state, and occurs when the developing device 43 is in the inactive state. Show that you do not.

Therefore, the fact that the second comparison value is within the allowable range in step S11 indicates that the development failure state has occurred.

On the other hand, when the second comparison value exceeds the allowable range, the adjustment control unit 8c causes the process to proceed to step S12.

The fact that the second comparison value exceeds the allowable range in step S11 indicates that the noise toner is generated regardless of whether the developing device 43 is in the operating state or the non-operating state.

Therefore, the fact that the second comparison value exceeds the allowable range in step S11 indicates that the poor cleaning condition has occurred.

<Step S11>
In step S11, the adjustment control unit 8c executes the first adjustment process out of the predetermined first adjustment process and second adjustment process.

The first adjustment process and the second adjustment process include a plurality of candidates for adjustment processes of the monochrome image forming section 4x to improve the image fog. For example, the plurality of candidates include some or all of charging bias adjustment processing, development bias adjustment processing, development refresh processing, cleaning bias adjustment processing, and transfer bias adjustment processing.

The charging bias adjustment process is a process for adjusting the charging bias voltage of the charging device 42. The developing bias adjustment process is a process for adjusting the developing bias voltage of the developing device 43.

The development refresh process is a process in which existing toner in the developing device 43 is discharged and new toner is supplied to the developing device 43. The transfer bias adjustment process is a process for adjusting the primary transfer bias voltage of the primary transfer device 442.

The cleaning bias adjustment process is a process for adjusting the recovery bias voltage of the first cleaning device 45. The recovery bias voltage is an example of a cleaning bias voltage.

For example, the first adjustment process includes one or more of the charging bias adjustment process, the development bias adjustment process, and the development refresh process. The first adjustment process is a process corresponding to the image fog caused by the poor development state.

After executing the process of step S11, the adjustment control unit 8c ends the image quality adjustment process.

<Step S12>
In step S12, the adjustment control unit 8c executes the second adjustment process out of the first adjustment process and the second adjustment process.

For example, the second adjustment process includes one or both of the cleaning bias adjustment process and the transfer bias adjustment process. The second adjustment process is a process corresponding to the image fog caused by the poor cleaning state.

After executing the process of step S12, the adjustment control unit 8c ends the image quality adjustment process.

As shown above, the adjustment control unit 8c selects a process to be executed from a plurality of adjustment process candidates according to the first target density and the second target density (steps S5 and S10 to S12). reference).

More specifically, the adjustment control unit 8c selects a process to be executed from among the plural adjustment process candidates according to the first comparison value and the second comparison value (see step S5 and steps S10 to S12). ).

Therefore, the adjustment control unit 8c can execute adjustment processing according to the cause of the image fog. In this embodiment, the candidates for the cause of the image fog are the poor development state and the poor cleaning state.

[First application example]
A first application example of the image forming apparatus 10 will be described below.

In this application example, the second concentration sensor 5b is omitted. Therefore, in this application example, steps S3, S4, S8, and S9 of the image quality adjustment process are omitted (see FIG. 4).

<Step S5>
In step S5 of the image quality adjustment process, the adjustment control unit 8c of this application example determines the level of the first target density, and selects a processing destination according to the determination result.

Specifically, the adjustment control unit 8c ends the image quality adjustment process when the first target density is within the allowable range. Note that the upper limit value of the allowable range is different from the case where the first comparison value is used.

On the other hand, when the first target concentration exceeds the allowable range, the adjustment control unit 8c causes the process to proceed to step S6.

<Step S10>
The adjustment control unit 8c of this application example determines the level of the second target density in step S10 of the image quality adjustment process, and selects a destination of the process according to the determination result.

Specifically, the adjustment control unit 8c causes the process to proceed to step S11 when the second target concentration is within the allowable range.

On the other hand, if the second target concentration exceeds the allowable range, the adjustment control unit 8c causes the process to proceed to step S12.

When this application example is adopted, the same effects as in the case where the first embodiment is adopted can be obtained.

[Second application example]
Next, a second application example of the image forming apparatus 10 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.

In the developing device 43 of this application example, the state in which the developing bias voltage is applied to the developing roller 431 is the operating state of the developing device 43. On the other hand, the state in which the developing bias voltage is not applied to the developing roller 431 is the non-operating state of the developing device 43.

That is, the developing device 43 of this application example can be switched from one of the operating state and the non-operating state to the other according to the control command regarding the developing bias voltage.

<Step S1>
The adjustment control unit 8c of this application example causes the development voltage output device 432 to output the development bias voltage in step S1 of the image quality adjustment control. As a result, the developing device 43 is controlled to be able to supply the toner from the developing roller 431 to the photoreceptor 41.

<Step S6>
On the other hand, the adjustment control unit 8c of this application example causes the development voltage output device 432 to stop outputting the development bias voltage in step S6 of the image quality adjustment control. As a result, the developing device 43 is controlled such that the toner cannot be supplied from the developing roller 431 to the photoreceptor 41.

When this application example is adopted, the same effects as in the case where the first embodiment is adopted can be obtained.

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

In FIG. 5, the same components as those shown in FIG. 1 are given the same reference numerals. Hereinafter, the differences between the image forming apparatus 10A and the image forming apparatus 10 will be explained.

The image forming apparatus 10A includes a printing device 4A that can form only monochrome images. The printing device 4A has a configuration in which the four monochrome image forming sections 4x and the transfer device 44 in the printing device 4 of the image forming apparatus 10 are replaced with one monochrome image forming section 4x and a transfer device 44X.

One monochrome image forming section 4x forms the electrostatic latent image on the surface of the photoreceptor 41 and develops the electrostatic latent image into the toner image.

The transfer device 44X transfers the toner image formed on the surface of the photoreceptor 41 onto the sheet 9. The transfer device 44X transfers the toner image from the photoreceptor 41 to the sheet 9 at a transfer position P0 on the outer periphery of the photoreceptor 41.

The transfer device 44X is an example of a transfer unit that transfers the toner image formed on the surface of the photoreceptor 41 to the surface of the sheet 9. The transfer position P0 corresponds to the primary transfer position P1 and the secondary transfer position in the image forming apparatus 10.

In the image forming apparatus 10A, the first density sensor 5a detects the toner density in the development area A1 on the surface of the photoreceptor 41. Note that in the image forming apparatus 10A, the second density sensor 5b is omitted.

In the image forming apparatus 10A, the first density sensor 5a is arranged between the transfer position P0 on the outer periphery of the photoreceptor 41 and the position of the first cleaning device 45.

The adjustment control unit 8c of the image forming apparatus 10A also executes the image quality adjustment process. However, similarly to the first application example, the image adjustment process in this embodiment is executed by omitting steps S3, S4, S8, and S9 from the procedure shown in FIG.

<Step S2>
The adjustment control unit 8c of this embodiment obtains the first target concentration from the first concentration sensor 5a in step S2.

In this embodiment, the first target concentration is the concentration detected by the first concentration sensor 5a for the first specific area. As described above, the first specific area is the primary non-image area A10 that passes through the developing position when the developing device 43 is in the operating state.

<Step S5>
In step S5, the adjustment control unit 8c of the present embodiment determines the level of the first target density, and selects a processing destination according to the determination result.

Specifically, the adjustment control unit 8c ends the image quality adjustment process when the first target density is within the allowable range. Note that the upper limit value of the allowable range is different from the case where the first comparison value is used.

On the other hand, when the first target concentration exceeds the allowable range, the adjustment control unit 8c causes the process to proceed to step S6.

<Step S7>
The adjustment control unit 8c of this embodiment acquires the second target concentration from the first concentration sensor 5a in step S7.

In this embodiment, the second target concentration is the concentration detected by the first concentration sensor 5a for the second specific area. As described above, the second specific area is the primary non-image area A10 that passes through the developing position when the developing device 43 is in the non-operating state.

<Step S10>
In step S10, the adjustment control unit 8c of the present embodiment determines the level of the second target density, and selects a processing destination according to the determination result.

Specifically, the adjustment control unit 8c causes the process to proceed to step S11 when the second target concentration is within the allowable range.

On the other hand, if the second target concentration exceeds the allowable range, the adjustment control unit 8c causes the process to proceed to step S12.

Even when this embodiment is adopted, the same effects as in the case where the first embodiment or the applied example is adopted can be obtained.

[Additional notes to the invention]
Hereinafter, a summary of the invention extracted from the above-described embodiments will be added. Note that each configuration and each processing function described in the following supplementary notes can be selected and combined as desired.

<Additional note 1>
A method for adjusting an image forming apparatus, the method comprising:
The image forming apparatus includes:
A rotating photoconductor,
a charging unit that charges the surface of the photoreceptor;
an exposure unit that writes an electrostatic latent image on the surface of the charged photoreceptor;
a developing section that develops the electrostatic latent image into a toner image by supplying toner to a development area on the surface of the photoreceptor at a development position on the outer periphery of the photoreceptor;
a transfer unit that transfers the toner image formed on the surface of the photoreceptor to a transfer area on the surface of the sheet or the surface of the intermediate transfer member at a transfer position on the outer periphery of the photoreceptor;
a cleaning section that removes residual toner from a portion of the surface of the photoreceptor that has passed through the transfer position;
a main density detection section capable of detecting toner density in the development area of the photoconductor or the transfer area of the intermediate transfer body;
The developing section is capable of switching from one of an operating state in which the toner can be supplied to the surface of the photoconductor and a non-operating state in which the toner cannot be supplied to the surface of the photoconductor to the other according to a control command. In case,
The adjustment method is
a processor controlling the developing section to the operating state by outputting the control command;
The processor acquires from the main density detection unit a first target density detected by the main density detection unit for a first specific development area of the development area or a first specific transfer area of the transfer area. ,
the processor controls the developing section to the non-operating state by outputting the control command;
The processor acquires, from the main density detection unit, a second target density detected by the main density detection unit for a second specific development area of the development area or a second specific transfer area of the transfer area. ,
the processor selects a process to be executed from a plurality of adjustment process candidates according to the first target density and the second target density,
The first specific development area is a non-image area in the development area that passes through the development position when the development section is in the operating state,
The first specific transfer area is an area corresponding to the first specific development area in the transfer area,
The second specific development area is a non-image area in the development area that passes through the development position when the development section is in the non-operating state,
The method for adjusting an image forming apparatus, wherein the second specific transfer area is an area corresponding to the second specific development area in the transfer area.

<Additional note 2>
The image forming apparatus further includes a reference density detection unit capable of detecting toner density in a non-transfer area other than the transfer area on the surface of the intermediate transfer body,
When the main density detection section is capable of detecting the toner density in the transfer area of the intermediate transfer body,
The processor obtains a first reference density detected by the reference density detection unit when obtaining the first target density from the reference density detection unit;
The processor further comprises: acquiring from the reference concentration detection section a second reference concentration detected by the reference concentration detection section when acquiring the second target concentration;
The processor executes the adjustment process from among the plural adjustment processing candidates according to the ratio or difference between the first target density and the first reference density, and the ratio or difference between the second target density and the second reference density. The method for adjusting an image forming apparatus according to Supplementary Note 1, which selects a process to be performed.

<Additional note 3>
The candidates for the plurality of adjustment processes are:
A process of adjusting the charging bias voltage of the charging section;
A process of adjusting a developing bias voltage of the developing section;
Refreshing the developing section;
a process of adjusting a cleaning bias voltage of the cleaning section;
The method for adjusting an image forming apparatus according to Supplementary note 1 or 2, including a part or all of the process of adjusting the transfer voltage of the transfer unit.

<Additional note 4>
A rotating photoreceptor,
a charging unit that charges the surface of the photoreceptor;
an exposure unit that writes an electrostatic latent image on the surface of the charged photoreceptor;
a developing section that develops the electrostatic latent image into a toner image by supplying toner to a development area on the surface of the photoreceptor at a development position on the outer periphery of the photoreceptor;
a transfer unit that transfers the toner image formed on the surface of the photoreceptor to a transfer area on the surface of the sheet or the surface of the intermediate transfer member at a transfer position on the outer periphery of the photoreceptor;
a cleaning section that removes residual toner from a portion of the surface of the photoreceptor that has passed through the transfer position;
a main density detection section capable of detecting toner density in the development area of the photoconductor or the transfer area of the intermediate transfer body;
A processor that implements the method for adjusting an image forming apparatus according to any one of Supplementary Notes 1 to 3,
The developing section is capable of switching from one of an operating state in which the toner can be supplied to the surface of the photoconductor and a non-operating state in which the toner cannot be supplied to the surface of the photoconductor to the other according to a control command. , image forming device.

<Additional note 5>
The developing section includes:
a developing roller that is disposed opposite to the photoreceptor and rotates while supporting the toner on the surface;
a roller moving mechanism that moves the developing roller between the developing position and a retracted position farther from the photoreceptor than the developing position, in accordance with the control command;
The developing unit is in the operating state when the developing roller is located at the developing position, and the developing unit is in the inactive state when the developing roller is located at the retracted position. Image forming device.

3: Sheet conveyance device 4, 4A: Printing device 4x: Monochrome image forming section 5a: First density sensor (main density detection section)
5b: Second concentration sensor (reference concentration detection section)
8: Control device 9: Sheet 10: Image forming device 10A: Image forming device 40: Optical scanning device (exposure section)
41: Photoreceptor 42: Charging device 43: Developing device 44, 44X: Transfer device 45: First cleaning device 46: Fixing device 81: CPU (processor)
421: Charging member 422: Charging voltage output device 431: Developing roller 432: Developing voltage output device 433: Roller moving mechanism 441: Intermediate transfer belt (intermediate transfer body)
442: Primary transfer device 443: Secondary transfer device 444: Second cleaning device 451: Recovery member 452: Recovery voltage output device 4421: Primary transfer body 4422: Primary voltage output device 4431: Secondary transfer body 4432: Secondary voltage output Device

Claims (5)

A method for adjusting an image forming apparatus, the method comprising:
The image forming apparatus includes:
A rotating photoconductor,
a charging unit that charges the surface of the photoreceptor;
an exposure unit that writes an electrostatic latent image on the surface of the charged photoreceptor;
a developing section that develops the electrostatic latent image into a toner image by supplying toner to a development area on the surface of the photoreceptor at a development position on the outer periphery of the photoreceptor;
a transfer unit that transfers the toner image formed on the surface of the photoreceptor to a transfer area on the surface of the sheet or the surface of the intermediate transfer member at a transfer position on the outer periphery of the photoreceptor;
a cleaning section that removes residual toner from a portion of the surface of the photoreceptor that has passed through the transfer position;
a main density detection section capable of detecting toner density in the development area of the photoconductor or the transfer area of the intermediate transfer body;
The developing section is capable of switching from one of an operating state in which the toner can be supplied to the surface of the photoconductor and a non-operating state in which the toner cannot be supplied to the surface of the photoconductor to the other according to a control command. In case,
The adjustment method is
a processor controlling the developing section to the operating state by outputting the control command;
The processor acquires from the main density detection unit a first target density detected by the main density detection unit for a first specific development area of the development area or a first specific transfer area of the transfer area. ,
the processor controls the developing section to the non-operating state by outputting the control command;
The processor acquires, from the main density detection unit, a second target density detected by the main density detection unit for a second specific development area of the development area or a second specific transfer area of the transfer area. ,
the processor selects a process to be executed from a plurality of adjustment process candidates according to the first target density and the second target density,
The first specific development area is a non-image area in the development area that passes through the development position when the development section is in the operating state,
The first specific transfer area is an area corresponding to the first specific development area in the transfer area,
The second specific development area is a non-image area in the development area that passes through the development position when the development section is in the non-operating state,
The method for adjusting an image forming apparatus, wherein the second specific transfer area is an area corresponding to the second specific development area in the transfer area. The image forming apparatus further includes a reference density detection unit capable of detecting a toner density in a non-transfer area other than the transfer area on the surface of the intermediate transfer body,
When the main density detection section is capable of detecting the toner density in the transfer area of the intermediate transfer body,
The processor obtains a first reference density detected by the reference density detection unit when obtaining the first target density from the reference density detection unit;
The processor further comprises: acquiring from the reference concentration detection section a second reference concentration detected by the reference concentration detection section when acquiring the second target concentration;
The processor executes the adjustment process from among the plural adjustment processing candidates according to the ratio or difference between the first target density and the first reference density, and the ratio or difference between the second target density and the second reference density. The method for adjusting an image forming apparatus according to claim 1, further comprising selecting a process to be performed. The candidates for the plurality of adjustment processes are:
A process of adjusting the charging bias voltage of the charging section;
A process of adjusting a developing bias voltage of the developing section;
Refreshing the developing section;
a process of adjusting a cleaning bias voltage of the cleaning section;
3. The method for adjusting an image forming apparatus according to claim 1, comprising a part or all of adjusting the transfer voltage of the transfer section. A rotating photoreceptor,
a charging unit that charges the surface of the photoreceptor;
an exposure unit that writes an electrostatic latent image on the surface of the charged photoreceptor;
a developing section that develops the electrostatic latent image into a toner image by supplying toner to a development area on the surface of the photoreceptor at a development position on the outer periphery of the photoreceptor;
a transfer unit that transfers the toner image formed on the surface of the photoreceptor to a transfer area on the surface of the sheet or the surface of the intermediate transfer member at a transfer position on the outer periphery of the photoreceptor;
a cleaning section that removes residual toner from a portion of the surface of the photoreceptor that has passed through the transfer position;
a main density detection section capable of detecting toner density in the development area of the photoconductor or the transfer area of the intermediate transfer body;
A processor that implements the method for adjusting an image forming apparatus according to claim 1 or 2,
The developing section is capable of switching from one of an operating state in which the toner can be supplied to the surface of the photoconductor and a non-operating state in which the toner cannot be supplied to the surface of the photoconductor to the other according to a control command. , image forming device. The developing section includes:
a developing roller that is disposed opposite to the photoreceptor and rotates while supporting the toner on the surface;
a roller moving mechanism that moves the developing roller between the developing position and a retracted position farther from the photoreceptor than the developing position, in accordance with the control command;
The developing section is in the operating state when the developing roller is located at the developing position, and the developing section is in the inactive state when the developing roller is located at the retracted position. image forming device.