JP2000259057A - Image forming device and method for cleaning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device and a method for cleaning capable of removing reversely charged toner hindering uniform electrostatic charge of a photoreceptor surface potential. SOLUTION: At the time of a cleaning mode, the device is to stop application of a positive voltage on a transfer roller 9, when the surface of the photoreceptor drum 1 uniformly charged in negative potential by the electrifying roller 2 reaching the electrifying roller 2 after one round, to stop application of the negative voltage on the electrifying roller 2, to shift the reverse charged toner stuck to the surface of the electrifying roller 2 to the photoreceptor drum 1, and to scrape them off by a cleaning blade 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic image forming apparatus and a cleaning method.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a photoconductor is rotated in a predetermined direction, the surface of the photoconductor is charged to a uniform potential by a charging unit, and an electrostatic latent image is formed by an exposure unit. Is formed, a developing toner is supplied from a developing unit to the electrostatic latent image to form a toner image, and the toner image is transferred from the surface of the photoreceptor to a printing medium by a transfer unit, and the development remaining on the surface of the photoreceptor is performed. There is a type in which toner (hereinafter referred to as residual toner) is scraped off by a cleaning blade.

In the course of the printing process, a small amount of oppositely charged toner may adhere to the photoreceptor. The reverse charging toner has a polarity opposite to the polarity of the electric charge carried by the developing toner, and is generated when a toner layer is formed in the developing portion, and is influenced by a transfer voltage by the transferring portion in the transferring process. It is thought to occur in. The oppositely charged toner on the photoreceptor is scraped off by a cleaning blade together with the residual toner.

[0004] In recent years, as toner particles have been miniaturized and spherical toners have been used by polymerization, the cleaning blade has not been scraped off by the cleaning blade but has adhered to the photosensitive member. Something slips through the road. In the case of toner particles formed in a spherical shape by a polymerization method, the spherical shape makes it difficult to catch the cleaning blade, and the elasticity of the toner itself flattens the clearance of the cleaning blade. It is easy to slip through.

[0005]

In a conventional image forming apparatus, when printing is performed on 1,000 or 2,000 sheets, the residual toner on the photoreceptor and the oppositely charged toner become a cleaning blade. Without being scraped off,
Something slips through the cleaning blade. The residual toner is finally collected in the developing section as the photoconductor rotates. However, there is a problem that the oppositely charged toner adheres and accumulates on the charged portion, thereby preventing uniform charging of the photosensitive member.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus and a cleaning method which can remove, from a charged portion, a reversely charged toner which prevents uniform charging of the photosensitive member surface potential.

[0007]

In order to achieve the above object, in an image forming apparatus according to the present invention, a reversely charged toner which has a polarity opposite to that of a charge carried by a developing toner and adheres to a charging portion is provided. Is moved from the charging section to the surface of the photoreceptor, and a cleaning mode is provided for scraping off the cleaning blade.

In order to achieve the same object, in the cleaning method of the image forming apparatus of the present invention, a cleaning roller composed of a porous sponge is disposed upstream of the cleaning blade. , Printing, cleaning low
The oppositely charged toner is aggregated in the hole of
At the time of cleaning, the aggregated oppositely charged toner is moved from the cleaning roller to the surface of the photoreceptor, and is scraped off by a cleaning blade.

[0009]

Embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals. First Embodiment FIG. 1 is a block diagram illustrating a configuration of an image forming apparatus according to a first embodiment. The image forming apparatus includes a photosensitive drum 1 (hereinafter, referred to as a photosensitive drum 1), a photosensitive drum 1
, A power supply unit 3 for applying a negative voltage to the charging roller 2, a developing roller 4 for supplying a developing toner to the photosensitive drum 1, and a positive roller for the developing roller 4. A power supply unit 5 for applying a voltage or a negative voltage, and a developing toner on a developing roller 4
A toner regulating member 6 for keeping the amount constant, a transfer belt 8 for transferring the developed toner to a print medium 7, and a power supply unit 1 for applying a positive voltage or a negative voltage to the transfer belt 8 via a transfer roller 9
0, scraping residual toner on the photosensitive drum 1, for example, a cleaning blade 11 made of silicon rubber,
It comprises a recording head 12 for selectively exposing the photosensitive drum 1, a motor 13 for rotating and driving the photosensitive drum 1 and each roller and the transfer belt 8, and a control unit 14 for controlling these.

The charging roller 2, the developing roller 4, and the transfer belt 8 are in contact with the photosensitive drum 1 at a predetermined pressure.

In the developing method of the image forming apparatus according to the present embodiment, the developing toner is a reversal development having a charge having the same polarity as the uniform charging polarity of the photosensitive drum 1, and the developing toner is charged with a negative charge.

FIG. 2 is a time chart showing the operation of the first embodiment. (A) to (D) show the timing of the driving of the motor 13, the voltage applied to the charging roller 2, the voltage applied to the developing roller 4, and the voltage applied to the transfer belt 8.

Next, the operation will be described. At time t0, the control unit 14 turns on the motor 13 and enters the print mode.
The photosensitive drum 1 and each roller and belt are driven to rotate by a motor 13. The photosensitive drum 1 rotates in the direction of arrow A, the charging roller 2 rotates in the direction of arrow B, the developing roller 5 rotates in the direction of arrow C, the transfer belt 8 rotates in the direction of arrow D, and printing is performed. The medium 7 advances in the direction of arrow E.

At time t1, the control unit 14 switches the output of the power supply unit 3 from 0V to -1300V and changes the output of the power supply unit 5 to 0V.
From + V to + 400V, and at time t2, the output of the power supply unit 10 is switched from 0V to a positive voltage. During this time, the photosensitive drum 1
Is uniformly charged to a surface potential of -800 V by contact with the charging roller 2 to which a negative voltage is applied from the power supply unit 3, and an arrow A
By rotating in the direction, the surface of the photosensitive drum 1 uniformly charged reaches below the recording head 12.

The surface of the photosensitive drum 1 is selectively exposed by a recording head 12 in accordance with an image to be formed, and the surface potential of the photosensitive drum 1 in a portion where an electrostatic latent image has been written is a non-exposed portion. The value is closer to the 0 V side.

The surface of the photosensitive drum 1 on which the electrostatic latent image has been written comes into contact with the developing roller 4 by continuing rotation in the direction of arrow A. The developing roller 4 contacts the photosensitive drum 1 with a predetermined pressure and rotates in the direction of arrow C.

At time t3, the control section 14 switches the output of the power supply section 5 from + 400V to -250V. The developing toner on the developing roller 4 is thinned by the toner regulating member 6 and is charged with a negative charge, so that the electrostatic latent image is developed as a toner image by contact with the photosensitive drum 1.

After the development, the surface of the photosensitive drum 1 comes into contact with the transfer belt 8 by rotating in the direction of arrow A. The transfer belt 8 comes into contact with the photoreceptor 1 at a predetermined pressure and moves in the direction of arrow D. The transfer belt 8 is a power supply unit 10
, A positive voltage is applied to charge the positive charge, and the toner image on the photosensitive drum 1 is transferred to the print medium 7 traveling in the direction of arrow E. The print medium 7 after the transfer is the photosensitive drum 1
From the image forming apparatus, and inserted into a fixing device (not shown).

After the transfer is completed, a part of the developing toner remains on the surface of the photosensitive drum 1 as a residual toner, but the surface of the photosensitive drum 1 is continuously rotated together with the residual toner by rotating in the direction of arrow A. Contact with the blade 9. The remaining toner on the photosensitive drum 1 is scraped off by a cleaning blade 9. That is, the remaining toner is removed from the photosensitive drum 1. The photoreceptor drum 1 from which the residual toner has been removed is continuously rotated in the direction of arrow A, and enters the charging step again.

When printing of one page is completed, the control unit 14 enters a cleaning mode at time t4 as shown in FIG. Upon completion of the printing operation, the control unit 14 transfers the transfer roller 9.
The output of the power supply unit 10 to which a positive voltage has been applied is switched to the application of 0V.

The photosensitive drum 1 before contacting the transfer belt 8
Is charged to -800 V by the charging roller 2, but since the transfer belt 8 is at 0 V, the charging potential is lowered after passing through the transfer belt 8 to about -500 V. After passing through the transfer belt 8, the surface of the photosensitive drum 1 contacts the cleaning blade 9 by rotating in the direction of arrow A. Since no voltage is applied to the cleaning blade 9, the surface potential of the photosensitive drum 1 does not change. Further, the surface of the photosensitive drum 1 comes into contact with the charging roller 2 at time t5 by rotation in the direction of arrow A.

At time t5, the control section 14 switches the output of the power supply section 3 from -1300V to 0V application. As a result, the oppositely charged toner adhering to the charging roller 2 receives the cloning force on the negatively charged photosensitive drum 1 side, moves to the photosensitive drum 1 side and adheres. , Photosensitive drum 1
Does not change.

The time T1 during which 0 V is applied to the charging roller 2 is at least one rotation of the charging roller 2 in order to move the oppositely charged toner toward the photosensitive drum 1. is necessary. When the amount of adhered reversely charged toner is large, it is of course possible to increase the time during which 0 V is applied to two or three rounds.

However, as will be described later, the power supply unit 10 applying the voltage to the transfer belt 8 keeps the power supply unit 10 OFF for a period of time (T1 + α).
Since V is applied, the power supply unit 10 applying 0 V to the transfer belt 8 until the surface of the photosensitive drum 1 in contact with the charging roller 2 contacts the transfer belt 8 at time t5. Must be switched to the application of
1 has a limit due to the circumference of the photosensitive drum 1.

The surface of the photosensitive drum 1 to which the oppositely charged toner adheres is eventually rotated by the rotation in the direction of arrow A so that the developing roller 4
Touch

At time t6, the control section 14 switches the output of the power supply section 5 from -250V to 0V. As a result, the oppositely charged toner on the photosensitive drum 1 receives a Clon force on the photosensitive drum 1 side and continues to adhere to the photosensitive drum 1.

After a lapse of time (T1 + α) from time t4, at time t7, the control unit 14 sets the output voltage of the power supply unit 10 to 0.
Switch from V to positive voltage. power supply unit 3
While 0 V is applied to the charging roller 2, the area of the photosensitive drum 1 passing therethrough is surely connected to the power supply unit 1 by the transfer belt 8.
0 is a margin for the area of the photosensitive drum 1 that has passed while applying 0V.

After a lapse of time T1 from time t5, time t1
8, the control unit 14 changes the output voltage of the power supply unit 3 from 0 V to -13.
Switch to 00V. During this time, the charging roller 2 makes at least one rotation.

After a lapse of time (T1 + β) from time t6, at time t9, the control unit 14 changes the output voltage of the power supply unit 5 to 0V.
To -250V. Here is the value of β,
While the area of the photosensitive drum 1 that passes while the power supply unit 3 is applying 0 V to the charging roller 2 passes through the portion in contact with the developing roller 4, the power supply unit 5 ensures that the developing roller -0 in LA4
A margin to which V can be applied.

The reversely charged toner on the photosensitive drum 1 that has passed through the developing roller 4 comes into contact with the transfer belt 8 as it rotates in the direction of arrow A. At this time, the power supply unit 10 has already
, The oppositely charged toner on the photosensitive drum 1 passes through the transfer belt 8 while adhering to the photosensitive drum 1.

Further, by the rotation in the direction of arrow A, the oppositely charged toner on the photosensitive drum 1 is cleaned by a cleaning blade 9.
And the photosensitive drum 1 by the cleaning blade 9
The upper oppositely charged toner is scraped off.

At time t after the oppositely charged toner on the photosensitive drum 1 has completely passed through the cleaning blade 9.
At 10 the control unit 14 ends the cleaning mode and at time t
In step 11, the motor 13 is stopped, and the rotation of the photosensitive drum 1 and the rollers and belts in contact with the photosensitive drum 1 are stopped.

In this embodiment, the cleaning mode is always set at the end of printing regardless of whether printing is performed on a page-by-page basis or in continuous printing. However, there is a possibility that the printing performance may be degraded. Also, depending on the cleaning blade's scraping ability, it is not necessary to enter the cleaning mode so frequently. Conversely, in the case of continuous printing, the cleaning mode may not be entered.

In order to solve the above problem, one page
When the number of prints reaches a predetermined number of N (N: an integer) regardless of whether printing is performed for each page or continuous printing and the printing of the Nth page is completed, the printer enters the cleaning mode from the print mode. You may do so.

According to the first embodiment, a cleaning mode is inserted at the end of printing, and a voltage of 0 V is applied to the charging roller 2 for a certain period during the printing mode. 2 can be removed, and the photosensitive drum 1 can always be charged to a uniform surface potential.

According to the first embodiment, in the printing mode, a negative voltage is applied to the charging roller to charge the surface of the photosensitive drum to a uniform negative potential, thereby forming an electrostatic latent image. The supplied developing toner is charged with a negative charge, and a positive voltage is applied to the transfer roller to transfer the toner image from the surface of the photosensitive drum to the printing medium. In the cleaning mode, the transfer roller is used. The application of a positive voltage to the charging roller is stopped, and when the surface of the photosensitive drum charged to a uniform negative potential by the charging roller makes a circuit and reaches the charging roller, the negative voltage is applied to the charging roller. By stopping the application and moving the oppositely charged toner adhering to the surface of the charging roller to the surface of the photosensitive drum and scraping it by a cleaning blade, the oppositely charged toner on the charging roller is removed. Since the toner can be removed, the photosensitive drum is always charged to a uniform surface potential. Can.

Second Embodiment In the first embodiment, it was necessary to switch the voltage applied to the transfer belt in the cleaning mode.
In this embodiment, the cleaning operation can be performed while the voltage applied to the transfer belt is maintained at a positive voltage. The second embodiment has the same configuration as the first embodiment except for the operation of the control unit.

FIG. 3 is a time chart showing the operation in the cleaning mode of the second embodiment. (A) ~
(D) shows the timing of the driving of the motor 13, the voltage applied to the charging roller 2, the voltage applied to the developing roller 4, and the voltage applied to the transfer belt 8, respectively.

The insertion timing of the cleaning mode can correspond to both intermittent printing and continuous printing. In the present embodiment, however, the number of prints reaches N (N: an integer) and N pages
A cleaning module inserted after the printing of the jig is completed.
Talk about

When the printing operation is completed, the control unit 14 switches the apparatus to the cleaning mode at time t30. Control unit 1
Reference numeral 4 denotes a positive voltage to the transfer belt 8 (this voltage varies depending on the thickness of the print medium), for example, the power supply unit 10 which has applied 1 KV continuously applies a positive voltage. Here, the current value of the power supply unit 10 applying a positive voltage to the transfer belt 8 is represented by It.
The current value at which the power supply unit 3 applying a negative voltage to the charging roller 2 normally charges the surface of the photosensitive drum 1 to -800 V is defined as Ic. From the time t30 when the cleaning mode starts, to the time t36 when the cleaning mode ends, it is set so that the relationship of It <Ic is maintained.

With this setting, the surface potential of the photosensitive drum 1 before contacting the transfer belt 8 is reduced by -8 by the charging roller 2.
Although it is charged to 00V, the surface potential of the photosensitive drum 1 after passing through the transfer belt 8 changes to about -100V,
Maintain the negative voltage potential.

The surface of the photosensitive drum 1 after passing through the transfer belt 8 contacts the cleaning blade 9 by rotating in the direction of arrow A. Since no voltage is applied to the cleaning blade 9, the surface potential of the photosensitive drum 1 does not change. Further, the surface of the photosensitive drum 1 comes into contact with the charging roller 2 at time t31 by rotation in the direction of arrow A.

At time t31, the control section 14 switches the output voltage of the power supply section 3 from -1300V to 0V. Charging roller 2
The negatively charged toner adhering to the photosensitive drum 1 receives a cloning force on the negatively charged photosensitive drum 1 side, moves to the photosensitive drum 1 side, and adheres. The surface potential of the photosensitive drum 1 does not change.

The time T1 when 0 V is applied to the charging roller 2 is at least one rotation of the charging roller 2 in order to move the oppositely charged toner toward the photosensitive drum 1. is necessary. When the amount of the reversely charged toner is large, it is of course possible to increase the time during which 0 V is applied to two or three rounds.

At the time t32, the surface of the photosensitive drum 1 on which the oppositely charged toner is adhered is rotated by the rotation in the direction of arrow A so that the developing roller is rotated.
It touches LA4. At this time, the surface potential of the photosensitive drum 1 is 0
Close to V.

At time t32, the control unit 14 switches the output voltage of the power supply unit 5 from -250V to 0V. This allows
The oppositely charged toner on the photosensitive drum 1 receives a Clon force on the photosensitive drum 1 side, and continues to adhere to the photosensitive drum 1.

After a lapse of time T1 from time t31, time t1
At 33, the control unit 14 changes the output voltage of the power supply unit 3 from 0V to -13.
Switch to 00V. During this time, the charging roller 2 makes one or more rounds.

After a lapse of time (T1 + β) from time t32, at time t34, the control unit 14 sets the output voltage of the power supply unit 5 to 0V.
To -250V. Here is the value of β,
While the area of the photosensitive drum 1 that passes while the power supply unit 3 is applying 0 V to the charging roller 2 passes through the portion in contact with the developing roller 4, the power supply unit 5 ensures that the developing roller -0 in LA4
A margin to which V can be applied.

The reversely charged toner on the photosensitive drum 1 that has passed through the developing roller 4 comes into contact with the transfer belt 8 as it rotates in the direction of arrow A. Since the power supply unit 10 applies a positive voltage to the transfer belt 8, the oppositely charged toner on the photosensitive drum 1 passes through the transfer belt 8 while being attached to the photosensitive drum 1.

Further, by the rotation in the direction of arrow A, the oppositely charged toner on the photosensitive drum 1 is cleaned by a cleaning blade 9.
And the photosensitive drum 1 by the cleaning blade 9
The upper oppositely charged toner is scraped off.

After the oppositely charged toner adhering portion of the photosensitive drum 1 has completely passed through the cleaning blade 9, the control unit 14 terminates the cleaning mode at time t35. Control unit 1
4 switches the apparatus to the printing mode to start the next printing operation, or stops the motor 13 at time t36, and rotates the photosensitive drum 1 and the rollers and belts in contact with the photosensitive drum 1. Stop.

According to the second embodiment, the voltage applied to the transfer belt is maintained at the positive voltage even during the cleaning mode, so that the voltage switching is more complicated than in the first embodiment. Is simplified.

Third Embodiment In a third embodiment, a description will be given of cleaning in which a cleaning blade is combined with a cleaning roller as a reverse-charged toner aggregating means.

FIG. 4 is a block diagram showing the configuration of an image forming apparatus according to the third embodiment. The difference from the first and second embodiments is that a cleaning roller 15 and a power supply unit 16 are added. FIG. 6 is a time chart showing the operation in the cleaning mode according to the third embodiment. (A) to (E) show the driving of the motor 13,
The voltage applied to the charging roller 2, the voltage applied to the developing roller 4, the voltage applied to the transfer belt 8, the cleaning roller
4 shows the timing of the frame 15.

In the printing mode, the control section 14 controls the power supply section 16 so as to apply a voltage of -1250 V to the cleaning roller 12. Accordingly, the oppositely charged toner adhering to the photosensitive drum 1 is attached to the cleaning roller 12 by receiving the cron force.

The cleaning roller 15 is composed of a porous sponge, and the oppositely charged toner adheres and accumulates in the mesh of the cleaning roller 15 while aggregating.
The developing toner on the photosensitive drum 1 is
Since no cleaning force is applied to the cleaning roller 15 side, the cleaning roller 15 passes through the cleaning roller 15, and thereafter, the arrow A
With the rotation in the direction, it is scraped off by the cleaning blade 9.

When the printing operation is completed, the control unit 14 switches the apparatus to the cleaning mode at time t40. Control unit 1
Reference numeral 4 switches the output voltage of the power supply unit 10 from a positive voltage, for example, from 1 KV to 0 V. The surface potential of the photosensitive drum 1 before contacting the transfer belt 8 is charged to −800 V by the charging roller 2, but since the transfer belt 8 is 0 V, the charging potential is lowered after passing through the transfer belt 8. It is about -500V. The surface of the photosensitive drum 1 after passing through the transfer belt 8 is brought into contact with the cleaning roller 15 at time t41 by rotation in the direction of arrow A.

At time t41, the control section 14 switches the output voltage of the power supply section 16 from -1250V to + 400V. During the printing operation, the oppositely charged toner deposited and deposited on the cleaning roller 15 receives a cloning force on the photosensitive drum 1 side, and moves to and adheres to the photosensitive drum 1 side. The surface of the photosensitive drum 1 to which the oppositely charged toner has adhered rotates in the direction of arrow A and comes into contact with the cleaning blade 9. The oppositely charged toner on the photosensitive drum 1 is scraped off by a cleaning blade 9.

After a lapse of time (T2 + γ) from time t40, at time t42, the control unit 14 sets the output voltage of the power supply unit 10 to 0.
Switch from V to 1KV. Here, the value of γ is that while the area of the photosensitive drum 1 that passes while the power supply unit 16 applies +400 V to the cleaning roller 15 passes through the portion that is in contact with the transfer belt 8, The power supply unit 10 can reliably apply 0 V to the transfer belt 8.

After a lapse of time T2 from time t41, time t
At 43, the control unit 14 switches the output voltage of the power supply unit 16 from + 400V to -1250V. During this time, the cleaning roller 15 makes one or more rounds. Cleaning roller 12
When -1250V is applied to the cleaning roller 12,
Is charged to about -750V.

At time t44, the control unit 14 switches the output voltage of the power supply unit 3 from -1300V to 0V. Normally, the oppositely charged toner on the photosensitive drum 1 is removed by a cleaning roller 12 and a cleaning blade 9, but a small amount of the toner remaining on the photosensitive drum 1 is replaced by a charging roller. 2
Adhered to. When the power supply unit 3 is switched to the application of 0 V, the oppositely charged toner on the charging roller 2 receives a cloning force on the photosensitive drum 1 side and moves and adheres.

The time T1 during which 0 V is applied to the charging roller 2 is required, but at least one rotation of the charging roller 2 is required. When the amount of the reversely charged toner is large, it is of course possible to increase the time during which 0 V is applied to two or three rounds.

At time t45, the control section 14 switches the output voltage of the power supply section 5 from -250V to 0V. At this time, the surface of the photosensitive drum 1 to which the oppositely charged toner has adhered comes into contact with the developing roller 4 by rotation in the direction of arrow A. Since the surface potential of the photosensitive drum 1 is about -500 V, the photosensitive drum 1
The upper oppositely charged toner receives a Clon force on the photosensitive drum 1 side and continues to adhere to the photosensitive drum 1.

After a lapse of time T1 from time t44, time t
At 46, the control unit 14 changes the output voltage of the power supply unit 3 from 0V to -13.
Switch to 00V. During this time, the charging roller 2 makes one or more rounds.

After a lapse of time (T1 + β) from time t45, control unit 14 switches the output voltage of power supply unit 5 from 0V to -250V at time t47. Here, the value of β is used while the area of the photosensitive drum 1 that passes while the power supply unit 3 applies 0 V to the charging roller 2 passes through a portion that contacts the developing roller 4. The power supply unit 5 is surely connected to the developing roller 4.
Is a margin to which 0V can be applied.

The oppositely charged toner on the photosensitive drum 1 that has passed through the developing roller 4 comes into contact with the transfer belt 8 as it rotates in the direction of arrow A. Since the power supply unit 10 applies a positive voltage to the transfer belt 8, the oppositely charged toner on the photosensitive drum 1 passes through the transfer belt 8 while being attached to the photosensitive drum 1.

Further, by the rotation in the direction of arrow A, the oppositely charged toner on the photosensitive drum 1 is cleaned by the cleaning roller 12.
Touch The power supply unit 13 is connected to the cleaning roller 12 by -1.
Since a voltage of 250 V is applied, the oppositely charged toner on the photosensitive drum 1 receives a cloning force toward the cleaning roller 12 and moves and adheres. After all the oppositely charged toners on the photosensitive drum 1 have been deposited on the photosensitive drum 1, the cleaning mode is ended at time t48. Control unit 14
Switches the device to print mode and starts the next print operation,
Alternatively, at time t49, the motor 13 is stopped and the photosensitive drum 1 is stopped.
Then, the rotation of the roller and the belt in contact with the photosensitive drum 1 is stopped.

According to the third embodiment, the oppositely charged toner on the photosensitive drum is adhered to the cleaning roller during printing and is aggregated in the mesh of the cleaning roller.
The toner having a large particle size can be obtained. Next, in a cleaning mode, the photosensitive drum is charged with a reversely charged toner.
Is released and is scraped off by a cleaning blade provided downstream. However, since the oppositely charged toner has a large particle size, it can be reliably removed by the cleaning blade.

[0069]

Since the present invention is configured as described above, it has the following effects. Development toner
A cleaning mode is provided in which a reversely charged toner, which has a polarity opposite to that of the charged electric charge and adheres to the charged portion, is moved from the charged portion to the surface of the photoreceptor, and is scraped by a cleaning blade. As a result, the oppositely charged toner adhered and deposited on the charging portion is removed, and the surface potential of the photoreceptor is uniformly charged.
Improve print quality.

Further, a cleaning roller composed of a porous sponge is used as a reversely charged toner aggregating means.
It is arranged upstream of the cleaning blade, and the oppositely charged toner is aggregated in the holes of the cleaning roller at the time of printing, and the aggregated oppositely charged toner is exposed from the cleaning roller at the time of the cleaning mode. By moving to the surface of the body and scraping with a cleaning blade, even toner particles formed into a spherical shape by the polymerization method can be reliably caught and removed by the cleaning blade. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image forming apparatus according to a first embodiment.

FIG. 2 is a time chart showing the operation of the first embodiment.

FIG. 3 is a time chart showing the operation of the second embodiment.

FIG. 4 is a block diagram illustrating a configuration of an image forming apparatus according to a third embodiment.

FIG. 5 is a time chart showing the operation of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor drum 2 Charging roller 11 Cleaning blade 15 Cleaning roller

Claims (8)

[Claims] 1. A developing toner in which a surface of a photoreceptor rotating in a predetermined direction is charged to a uniform potential by a charging unit, and an electrostatic latent image formed by exposure is charged with the same polarity as the charging polarity of the photoreceptor. Is supplied to form a toner image.
In an image forming apparatus for transferring an image from the surface of a photoreceptor to a print medium and scraping off residual toner remaining on the surface of the photoreceptor by a cleaning blade, a polarity opposite to the polarity of the charge carried by the developing toner is obtained. A cleaning mode is provided in which a reversely charged toner, which has a polarity of and adheres to the charging section, is moved from the charging section to the surface of the photoreceptor, and is scraped off by the cleaning blade. Image forming device. 2. The method according to claim 1, further comprising the step of: placing a reverse-charged toner aggregating means upstream of the cleaning blade; 2. The image forming apparatus according to claim 1, wherein the aggregated oppositely charged toner is moved from the oppositely charged toner aggregation unit to the surface of the photoconductor, and is scraped off by the cleaning blade. 3. The image forming apparatus according to claim 2, wherein said reversely charged toner aggregating means is a cleaning roller formed of a porous sponge for aggregating said oppositely charged toner. 4. A negative voltage is applied to the charging unit to charge the surface of the photoconductor to a uniform negative potential, and a positive voltage is applied to the transfer unit to transfer the toner image on the photoconductor. The image forming apparatus according to claim 1, wherein the image is transferred from the front surface to the print medium. 5. In the cleaning mode, the application of a positive voltage to the transfer section is stopped, and the surface of the photoconductor charged to a uniform negative potential by the charging section makes a round to reach the charging section. 5. The cleaning blade according to claim 4, wherein the application of the negative voltage to the charging portion is stopped when the toner reaches the toner, and the oppositely charged toner attached to the surface of the charging portion is moved to the surface of the photosensitive member and scraped off by the cleaning blade. Image forming device. 6. In the cleaning mode, application of a positive voltage to the transfer section is continued, and the surface of the photoconductor charged to a uniform negative potential by the charging section makes a round to reach the charging section. When it reaches, stop applying the negative voltage to the charging unit,
5. The image forming apparatus according to claim 4, wherein the oppositely charged toner adhered to the surface of the charging unit is moved to the surface of the photoreceptor and is scraped off by the cleaning blade. 7. A negative voltage is applied to the charging unit to charge the surface of the photosensitive member to a uniform negative potential, and a positive voltage is applied to the transfer unit to transfer the toner image to the photosensitive member. The toner is transferred from the surface to the printing medium, and a negative voltage is applied to the cleaning roller to cause the oppositely charged toner to aggregate in the holes of the cleaning roller. In the cleaning mode, the toner is aggregated. 4. An image forming apparatus according to claim 3, wherein an oppositely charged toner is moved from said cleaning roller to a surface of said photosensitive member, and is scraped off by said cleaning blade. 8. A cleaning method for an image forming apparatus, in which a developing blade remaining on a surface of a photoreceptor is scraped by a cleaning blade, the cleaning roller comprising a porous sponge is provided. An oppositely charged toner having a polarity opposite to the polarity of the electric charge carried by the developing toner at the time of printing, which is arranged upstream of the cleaning blade, and agglomerated in the holes of the cleaning roller, A cleaning method for an image forming apparatus, wherein in a cleaning mode, an aggregated oppositely charged toner is moved from a cleaning roller to the surface of the photoreceptor, and is scraped off with a cleaning blade.