JPH05119677A - Cleaning device - Google Patents

Abstract

PURPOSE:To prevent cleaning effect from being decreased, because a residual substance which is attracted to a conductive fur brush once adheres to a photosensitive body again by injecting charge from the photosensitive body, in the case that the conductive fur brush is always brought into contact with the photosensitive body. CONSTITUTION:In the case of impressing alternating electric field in a semi-cycle during which the residual substance attracted to the conductive fur brush 10 is recovered by a recovering roller 11 out of the alternating electric field impressed between the fur brush 10 and the roller 11, the brush 10 is separated from the surface of the drum 1, and then the alternating electric field is cyclically impressed between the brush 10 and the roller 11 in a state where the brush 10 is separated from the surface of the drum 1, so that the effectiveness of cleaning is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device, and more particularly to a cleaning device for removing residual toner from the surface of an image bearing member which has been transferred in an image forming process of an image forming device utilizing an electrophotographic process. Regarding improvement of a cleaning device.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer or a facsimile apparatus utilizing an electrophotographic process, an optically reflected light such as an original reflected light is formed on a uniformly charged photosensitive member (image carrier). An electrostatic latent image is formed by irradiating image information, and the latent image is visualized by applying toner from a developing device, and this visible image is transferred onto a recording paper.
An image is formed by fixing. Since residual toner or the like is attached to the surface of the photoconductor after the transfer, it is removed and collected by the cleaning device arranged on the downstream side of the transfer device.

In Japanese Laid-Open Patent Publication No. 2-11911, a conductive fur brush for rubbing the surface of a photosensitive drum to remove residual toner and a collecting roller for collecting the toner attached to the fur brush are disclosed. An alternating electric field is formed, and the residue on the surface of the photoconductor drum is adsorbed and removed from the surface of the photoconductor drum by the electric field of a half cycle of the alternating electric field. There is disclosed a cleaning device that collects a residue adsorbed on a brush from a fur brush toward a collection roller.

However, in the above-mentioned conventional example, a half-cycle alternating electric field is applied between the conductive brush and the collecting roller so that the collecting roller collects the residue adsorbed on the conductive fur brush. At this time, a phenomenon occurs in which electric charge is injected into the residue that is once adsorbed from the surface of the photoconductor drum to the conductive fur brush, and the charge-injected residue is transferred from the conductive fur brush to the photoconductor drum. When an electrostatic force is applied toward the surface, the electrostatic force is applied to the surface of the photoconductor drum, which causes a problem that the cleaning effect on the surface is diminished.

[0005]

SUMMARY OF THE INVENTION To solve the above problems, the present invention provides
Of the alternating electric field applied between the conductive fur brush and the recovery roller, when a half cycle alternating electric field is applied so that the residue adsorbed on the conductive fur brush is recovered by the recovery brush. In the state where the conductive fur brush is separated from the surface of the photosensitive drum and the conductive fur brush is separated from the surface of the photosensitive drum, an alternating electric field is periodically generated between the conductive fur brush and the collecting roller. It is an object of the present invention to provide a cleaning device which is applied between the two and improves the effectiveness of cleaning.

[0006]

In order to achieve the above object, the present invention provides a cleaning device for an image forming apparatus, which forms a developed image on the surface of an image bearing member and utilizes the developed image for transfer. A first cleaning means for rubbing to remove and adsorb the residue from the surface, and a second cleaning means for constantly rubbing with the first cleaning means to collect the removed adsorbed material adsorbed by this means. Corresponding to the contact with or the separation from the surface of the image carrier, an electric field for adsorbing and recovering the residue on the surface of the image carrier or a residue between the first cleaning means and the second cleaning means. A configuration is provided that includes a voltage switching application unit that switches and applies a voltage that forms an electrostatic force for collecting an object to the second cleaning unit, and the first cleaning unit is separated from the surface of the carrier. When It is configured to have an alternating electric power applying means for alternately switching and applying a voltage forming an electrostatic force and a reverse voltage having a polarity opposite to this voltage. Further, the contact or separation operation is synchronized with the developing cycle in multicolor superimposing development. It was configured to do.

[0007]

According to the present invention having the above-mentioned structure, when the residue is adsorbed from the surface of the photosensitive drum to the conductive fur brush, the brush is brought into contact with the surface of the photosensitive drum and the photosensitive drum is collected. When a half cycle of an alternating electric field for attracting the residue is applied between the roller and the roller to remove the residue from the conductive fur brush to the recovery roller, the brush and the surface of the photosensitive drum are separated from each other. , A subsequent half cycle of an alternating electric field for recovering the residue is applied between the photosensitive drum and the recovery roller.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 (a) and 1 (b) show a schematic configuration of an image forming apparatus to which an embodiment of a cleaning device according to the present invention is applied. Reference numeral 1 is a photosensitive drum composed of a photoconductive layer 2 and a conductive support 3. Reference numeral 4 is a charging device for uniformly charging the photosensitive member, and 5 is a light image irradiating device for projecting a reflected light of the document or a light beam modulated by an image signal. By these, an electrostatic latent image is formed on the photoconductive layer 2. A developing device 6 applies toner to the electrostatic latent image on the photoconductive layer 2 to form a toner particle visible image. An apparatus 7 transfers the toner image onto the transfer material 8.

Incidentally, in order to improve transferability, electric charges may be previously attached to a visible image by corona discharge or the like before transfer.
Reference numeral 9 denotes a cleaning device according to the present invention for cleaning and removing the residual toner on the photoconductive layer 2 after the transfer so as to prepare for reuse of the photoconductor.

The cleaning device 9 is in contact with the surface of the photosensitive drum 1 and has a cylindrical conductive fur brush (first cleaning means) 10 for adsorbing the toner adhering to the surface, and the conductive material. A collection roller (second cleaning means) 11 for collecting the toner adhering to the bristles constituting the brush 10 by sliding contact with the fur brush 10, and a rubber blade 12 for removing the toner on the collection roller 11. Have. Reference numeral 13 denotes a light source for irradiating the photoconductive layer 2 with light to improve the cleaning by removing the charge from the photoconductive layer 2 before the cleaning. The electro-conductive fur brush 10 has a cylindrical shape in which a large number of electro-conductive bristles are planted on the outer circumference of the shaft.

During the rotation period of the photosensitive drum 1 facing the image area, the conductive fur brush 10 continues to rub the peripheral surface of the photosensitive drum 1 in the image area (see FIG. 1).
(a)). On the other hand, in the rotation period of the photosensitive drum 1 not facing the image region, the conductive fur brush is used.
10 continues to separate from the peripheral surface of the non-image area of the photosensitive drum 1 (FIG. 1 (b)). The separation / contact driving means 14 operates the cleaning device 9 as described above. The control means 15, which has received the separation / connection timing signal from the separation / connection driving means 14, controls the alternating power supply 16 for operating the applied voltage. That is, when the conductive fur brush 10 is rubbing against the photosensitive drum 1,
By applying a negative voltage to the collecting roller 11, the photosensitive drum 1
The toner on the surface of is attracted to the conductive fur brush 10 by the electric field between the conductive fur brush 10 and the photosensitive drum 1. Further, when the conductive fur brush 10 is separated from the photosensitive drum 1, a voltage having a polarity opposite to that in the above case, that is, a positive polarity voltage is applied to remove the toner attracted to the conductive fur brush 10. The toner is collected by the collection roller 11 by the electrostatic force acting between the collection roller 11 and the collection roller 11. In this case, charge injection occurs due to the application of the positive voltage to a part of the toner adsorbed on the conductive fur brush 10, but the conductive fur brush 10 and the photosensitive drum 1 are separated. Therefore, the charged toner is accumulated in the brush 10 and does not adhere to the surface of the photosensitive drum 1. The accumulated toner is collected toward the collecting roller 11 by the reversal electric field applied to the collecting roller 11 when the photosensitive drum 1 is cleaned next. In addition, alternating power source 16
The control means 15 constitutes the voltage switching application means 17.

In the above description, the control of the voltage operation of the alternating power source is performed by alternately applying the alternating voltage to the collecting roller 11 in synchronization with the contact and the separation of the conductive fur brush 10 with respect to the photosensitive drum 1. However, the control means 15 receiving the separation timing signal from the separation / contact driving means 14 may operate the alternating power source so as to apply the alternating voltage to the collecting roller 11 during the separation period. By doing so, the positive polarity toner accumulated in the conductive fur brush 10 due to the charge injection as described above is collected by the collecting roller by the reversal electric field applied to the collecting roller 11 during the separation period. Therefore, the effectiveness of cleaning is further improved in the next contact period of the conductive fur brush 10 with the photosensitive drum 1. In this case, the alternating power source 16 and the control means 15 constitute an alternating voltage applying means 17.

FIG. 2 shows a multicolor superimposing image forming apparatus to which an embodiment of the cleaning apparatus according to the present invention is applied. When a print command is issued to this device, the photosensitive drum 21 is driven. Next, a cleaning device composed of the conductive fur brush 22, the collection roller 23, the contact / separation drive means 24, etc. slides the conductive fur brush 22 on the surface of the photosensitive drum 21.
A control unit 27 receives a contact timing signal between the conductive fur brush 22 and the photoconductor drum 21 from the contact / separation drive unit 24 between the photoconductor drum 21 and the collection roller 23 that have been discharged by the pre-charger 26. An electric field is applied from the alternating power source 28 based on the control signal of the voltage operation, and the toner on the surface of the photosensitive drum 21 is adsorbed by the conductive fur brush 22. Removal lamp
Reference numeral 29 prepares for an image forming process by erasing the residual charges on the surface of the photosensitive drum 21. In the next image forming process, the charger 30
Thereby charges the surface of the photoconductor drum 21 to a negative potential. Next, the light image irradiation device 31 projects the light beam or the like modulated by the original image or the like onto the surface of the charged photosensitive drum 21.
An electrostatic latent image is formed on the surface of the photosensitive drum 21. One of the four developing devices 32A for multicolor development forms a toner image. Photosensitive drum with this first color developed
An AC electric field is applied to the surface of 21 to bring its surface potential to near zero potential. Next, the surface potential of the photoconductor drum 21 is uniformly made negative by the charging charger 30 again. At this time, as will be described later, the cleaning device 25 is separated and driven by the separation and contact driving means 21 immediately after the initial cleaning is completed, and the conductive fur brush 22 has already been separated from the surface of the photosensitive drum 21.

Next, the developing device 32B forms a second color toner image. Similarly, the developing device 32C forms a third color toner image and the developing device 32D forms a fourth color toner image. After the formation of the toner image of the fourth color is completed, the paper 34 is conveyed from the paper feed cassette 33 to the transfer charger 36 via the paper feed roller pair 35, and by the transfer charger 36, the developing devices 32A and 32B are processed in the above steps. , 32C, 32D, the toner images of four colors superposed by the developing action are collectively transferred to the paper 34, and the paper 34 collectively transferred by the separation charger 37 is a photosensitive drum.
It is separated from the surface of 21 and is sent to a fixing roller pair 39 via a conveyor belt 38 to be fixed and printed.

Toner remaining on the surface of the photosensitive drum 1 without being transferred to the paper 34 by the transfer charger 37 is controlled in polarity and charge by a superposed electric field of an alternating electric field and a direct electric field applied by the pre-charger 26. At this stage, the cleaning device 25 is contact driven by the separation / contact driving means 24, and the conductive fur brush 22 is rubbed against the surface of the photosensitive drum 21. When the control means 27 receives the contact timing signal from the contact / separation drive means 24, a control electric field is applied from the alternating power source 28 to the collecting roller 23 in the same manner as described above, and the residual toner on the surface of the photoconductor drum 21 is the conductive fur brush 22. Is adsorbed on.

In the rotation period of the photosensitive drum 21, which belongs to the four-color superimposing batch image region, the conductive fur brush 22 continues to rub the peripheral portion of the photoconductor drum 21 in the batch image region.

On the other hand, of the rotation range of the photosensitive drum 21, in the rotation period in the image area which does not belong to the collective image area,
The conductive fur brush 22 continues to separate from the peripheral portion of the image area of the photosensitive drum 21. Upon receiving the separation / contact timing signal from the separation / connection driving means 24, the control means 27 controls the applied voltage operation with respect to the alternating power source 28. When the conductive fur brush 22 is rubbing against the photosensitive drum 21, a negative voltage is applied to the collecting roller 23 to transfer the toner on the surface of the photosensitive drum 21 to the conductive fur brush 22 and the photosensitive drum 21. It is adsorbed to the conductive fur brush 22 by the electric field between. When the conductive fur brush 22 is separated from the photoconductor drum 21, a polarity opposite to the above case, that is, a positive voltage is applied,
The toner is collected by the collecting roller 23 by the electrostatic force acting between the toner attracted to the conductive fur brush 22 and the collecting roller 23. In this case, charge injection occurs due to the application of the positive voltage to some of the toner adsorbed on the conductive fur brush, but since the conductive fur brush 22 and the photosensitive drum 21 are separated. The charged toner collects in the brush and does not adhere to the photoconductor drum 21. The accumulated toner is collected toward the collecting roller 23 by the reversal electric field applied to the collecting roller 23 when the photosensitive drum 21 is cleaned next time.

In the above description, the control for operating the voltage of the alternating power source is controlled by the photosensitive drum 21 of the conductive fur brush 22.
Alternating voltage is collected alternately in synchronization with contact with and release from the roller
It was realized by applying to
The control means 27, which receives the release timing signal from, may operate the alternating power source so as to apply the alternating voltage to the collecting roller 23 during the leaving period. By doing so, the positive polarity toner accumulated in the conductive fur brush 22 due to the charge injection as described above is collected by the collecting roller by the reversal electric field applied to the collecting roller 23 during the separation period. So the next conductive fur brush 10
The cleaning effectiveness during the contact period with the photosensitive drum 1 is further improved.

[0019]

As is clear from the above description,
Alternating voltage is applied to the collection roller in synchronism with the contact and separation of the conductive fur brush and the surface of the photoconductor to attract and collect the residual toner. The effect of improving the effectiveness of cleaning is achieved without adhering.

By applying an alternating voltage to the collecting roller during the disengagement period, the effectiveness can be further improved.

[Brief description of drawings]

1A and 1B are a schematic configuration diagram and an operation explanatory diagram of an image forming unit of an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic configuration diagram in which an embodiment of the present invention is applied to a multicolor superimposing image forming apparatus.

[Explanation of symbols]

1, 21 ... Photosensitive member, 4, 30 ... Photosensitive charging device, 5, 31 ... Optical image irradiation device, 9, 25 ... Cleaning device, 10, 22 ... Conductive fur brush, 11, 23 ... Collection roller, 14, 24 ... Separating / connecting drive means, 15, 27 ... Control means, 16, 28 ... Alternating power source, 17 ...
Voltage switching applying means (alternating voltage applying means), 32A, 32B,
32C, 33D ... Developing device, 35 ... Paper feed roller pair, 36 ... Transfer charger, 37 ... Separation charger, 39 ... Fixing roller pair.

Claims (3)

[Claims] 1. A cleaning device for an image forming apparatus, which forms a developed image on the surface of an image carrier and uses the developed image for transfer, rubbing the surface of the image carrier to remove a residue from the surface. First cleaning means for removing and adsorbing;
A second cleaning unit that constantly rubs against the first cleaning unit to collect the removed adsorbate adsorbed by the first cleaning unit; and the first cleaning unit on the surface of the image carrier. In the contact state, an electric field is formed between the image carrier and the first cleaning unit to apply a voltage for adsorbing and collecting the residue on the surface of the image carrier, and the first cleaning unit applies the voltage. In the state of being separated from the surface, an electrostatic force is formed between the residue on the first cleaning means side and the second cleaning means, and a voltage for adsorbing and collecting the residue on the second cleaning means side is applied. To apply,
A cleaning device, comprising: a voltage switching application means for switching application to the second cleaning means. 2. When the first cleaning means is separated from the surface of the carrier, an alternating voltage for alternately applying a voltage forming the electrostatic force and a voltage having a polarity opposite to this voltage. The cleaning device according to claim 1, further comprising a voltage applying unit. 3. The cleaning apparatus according to claim 1, wherein the contacting or releasing operation is synchronized with a developing cycle in multicolor superimposing development.