JP2002023580A - Cleaning device, process cartridge, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device, a process cartridge, and an image forming device which clean an image carrier by using a cleaning roller applied with a bias voltage as to electrophotographic image formation and solve the problem that the inside of the image forming device is soiled by toner sticking on the width-directional end parts of an image carrier. SOLUTION: The width that a cleaning roller which suctionally removes residual toner electrostatically by applying the bias voltage comes into contact with the image carrier is made less than effective electrostatic charging width that an electrostatic charger can changes the image carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device for cleaning an image carrier of an electrophotographic image forming apparatus applied to a copying machine, a laser printer, a facsimile, and the like.
More particularly, the present invention relates to a cleaning device, a process cartridge and an image forming apparatus for cleaning an image carrier using a cleaning roller.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus,
Various cleaning devices arranged on the periphery of the image carrier for cleaning the surface of the image carrier have been proposed. As one of them, a cleaning roller to which a bias voltage is applied is brought into contact with the image carrier. A known method is to remove residual toner and the like by electrostatically adsorbing and removing the residual toner.

In this system, the bias voltage applied to the cleaning roller has a polarity opposite to the polarity of the toner adhered on the image carrier.

[0004] For example, when the image carrier is an OPC photoconductor (organic photoconductor), the photoconductor is uniformly negatively charged by a charger, and then exposed to attenuate the negatively charged position imagewise. Then, a negatively charged toner is attached to the attenuated portion (image portion) to perform development. That is, since the toner on the image carrier is normally negatively charged, a positive bias voltage is applied to the cleaning roller. When the cleaning roller to which the positive bias voltage is applied comes into contact with the image carrier, the surface of the image carrier is positively charged. However, the positive charge of the image carrier is removed by a cleaning device located immediately downstream of the cleaning device. It cannot be canceled by the light of the electric appliance, and is removed only by negative uniform charging by the further downstream electric charger.

In general, the cleaning device needs to clean the entire surface of the image carrier, so that the width of the cleaning roller in contact with the image carrier (the length in the direction perpendicular to the moving direction of the image carrier relative to the cleaning device) is required. ) Is about the same as or larger than the width of the image carrier (the width of the photosensitive layer), so that the image that exceeds the effective charging width (the maximum width over which the image carrier can be charged by the charger). Positive charges accumulate at both ends of the carrier without being canceled. Then, it has been found that the negatively charged toner adheres to the portion on which the positive charge is applied, which causes problems such as contamination of the inside of the image forming apparatus.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of cleaning an image carrier using a cleaning roller to which a bias voltage is applied in image formation of an electrophotographic system. It is an object of the present invention to provide a cleaning device, a process cartridge, and an image forming apparatus which have solved the problem that toner adheres to an end of the image forming apparatus and stains the inside of the image forming apparatus.

[0007]

The above objects of the present invention have been attained by the following constitutions.

[0008] 1. A cleaning device for cleaning an image carrier, comprising: a cleaning roller that contacts and cleans the image carrier; and a bias voltage application unit that applies a bias voltage to the cleaning roller. A width of contact with the image carrier being shorter than an effective charging width of the image carrier.

[0009] 2. 2. The cleaning device according to claim 1, wherein a width of the cleaning roller in contact with the image carrier is longer than an image forming width of the image carrier.

[0010] 3. 3. The cleaning device according to the above item 1 or 2, wherein the cleaning roller is a conductive elastic roller.

4. A cleaning blade is provided downstream of the cleaning roller.
4. The cleaning device according to any one of 3.

5. A process cartridge detachable from the image forming apparatus main body, the process cartridge including at least an image carrier and the cleaning device according to any one of the above items 1 to 4.

6. An image forming apparatus comprising the cleaning device according to any one of the above items 1 to 4.

7. An image forming apparatus to which the process cartridge according to the above 5 is mounted.

[0015]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

FIG. 1 is a diagram showing the relationship between the cleaning device and the image carrier of the present invention, and a charger and a developing device.
FIG. 1A is a schematic cross-sectional view, and FIG. 1B is a schematic diagram showing a length relationship in the width direction of each member.

First, FIG. 1A will be described. In the figure, reference numeral 10 denotes a photosensitive drum serving as an image carrier, 11 denotes a static eliminator for canceling a remaining charged position on the surface of the photosensitive drum 10, and 12 denotes a uniform charging of the entire surface of the photosensitive drum 10. A charging device, a developing device 14 for adhering toner to the photosensitive drum 10 to form an image, a cleaning device 22;
221 is a cleaning blade for cleaning the end by pressing the photosensitive drum 10, 222 is a spring for pressing the cleaning blade 221 against the photosensitive drum 10, and 223 is biased and rotated. A cleaning roller for electrostatically removing and cleaning the photosensitive drum 10 by contacting the photosensitive drum 10
Reference numeral 224 denotes a blade for scraping toner adhered to the cleaning roller 223, and reference numeral 225 denotes a cleaning roller 223.
A toner collection roller 227 for collecting the toner scraped off from the cleaning roller 224 by a blade 224 and sending the collected toner to a recycling pipe (not shown) connected to a developing device is a bias voltage applying means for applying a bias voltage to the cleaning roller 223. A power supply 228 is a power supply controller as control means for controlling the power supply 227 at a constant current.

Since the cleaning roller 223 contacts the photosensitive drum 10 and electrostatically removes the toner by electrostatic force, the bias voltage applied to the cleaning roller 223 changes the photosensitive member at the position where the cleaning roller 223 contacts. It is necessary that the polarity of the toner on the drum 10 is opposite to that of the toner on the drum 10. That is, the power supply 227 applies a positive bias voltage to the cleaning roller 223 when the toner is negatively charged, and applies a negative bias voltage when the toner is positively charged. When the photoconductor drum 10 is an OPC photoconductor (organic photoconductor), the applied bias voltage is positive because the toner has a negative potential. The bias voltage applied at this time is controlled by the power supply controller 228 at a constant current. With the constant current control, a constant voltage can be applied to the toner per unit amount regardless of the amount of the residual toner adhering to the photoconductor drum 10, so that the portion where the toner adheres much is Even if there is a small portion, it is preferable because the toner can be removed by suction without unevenness. The constant current value in the case of the constant current control is 5 μA depending on the performance and characteristics of the image carrier and the cleaning device.
About 30 μA is preferable.

When the photosensitive drum 10 rotates in the direction of the arrow, the cleaning roller 223, which is located on the upstream side of the cleaning device 22 and has a bias voltage applied thereto, comes into contact with the photosensitive drum 10. Cleaning roller 223
Rotates in the direction of the arrow that does not oppose the rotation of the photosensitive drum 10 and electrostatically attracts and adheres to the surface of the foreign matter such as residual toner and paper powder attached to the photosensitive drum 10. The toner and the like adhering to the cleaning roller 223 further rotate and reach the position of the blade 224, and are scraped off by the blade 224. The scraped-off toner and the like are rotated by the rotation of the toner collecting roller 225 to form a recycling pipe. (Shown in FIG. 3), and is reused as toner for development. When the photosensitive drum 10 further rotates and reaches a position where the tip of the cleaning blade 221 comes into pressure contact, the residual toner and the like are scraped off at once, and the scraped off toner and the like are the same as in the case of the cleaning roller 223. Is guided to the recycling pipe by the toner collecting roller 225. Then, the cleaning blade 221 wears and deteriorates, and the photosensitive drum 1
0, and even if the toner or the like slips through the gap, the cleaning blade 221 is again
Is removed by the cleaning roller 223 located upstream of the cleaning device 22. Therefore, the cleaning ability of the cleaning device 22 does not decrease over time, and the image carrier can be sufficiently cleaned continuously.

The cleaning roller 223 is preferably a conductive elastic roller. In order to apply a bias voltage to the cleaning roller 223 and efficiently electrostatically attract toner and the like on the photosensitive drum 10, the surface resistance of the cleaning roller 223 is preferably 10 ⁵ Ω to 1Ω.
It is preferable that a conductive 0 ⁸ Omega.

Further, if the cleaning roller 223 is elastic, even if a foreign substance is caught between the cleaning roller 223 and the photosensitive drum 10, the cleaning roller 223 can be carried into the cleaning device 22 without damaging the surface of the photosensitive drum 10. I do.
In addition, when the cleaning roller 223 is elastic, the degree of adhesion to the photosensitive drum 10 is increased, and not only the removal of toner and the like on the photosensitive drum 10 by electrostatic suction but also a wiping effect can be expected. Increase. When the cleaning roller 223 is elastic, the surface hardness is preferably Asker C 20 ° to 40 °.

Specifically, as a preferred conductive elastic roller, a ruby cell roller (having a hardness of Asker C of 32 °) manufactured by Toyo Polymer Co., Ltd. or the like can be mentioned.

Next, FIG. 1B will be described. Figure 1
The horizontal direction of the drawing in (b) is the width direction of the charger 12, the developing device 14, the photosensitive drum 10, the cleaning roller 223, and the cleaning blade 221, which are arranged vertically so that the relationship between the widths can be understood. . The stripe portions at both left and right ends of the photosensitive drum 10 have no photosensitive layer,
This is a portion where the base material such as aluminum is exposed, and an image cannot be formed in this portion.

The charger 12 has an “effective charging width L” capable of charging the surface of the photosensitive drum 10.

The developing device 14 forms a toner image by attaching toner to an electrostatic latent image formed by an image exposing device (eg, an LED) not shown in FIG. The maximum width over which the toner can adhere is the “image formation width S”.

In the cleaning device of the present invention, the width of the cleaning roller 223 in contact with the photosensitive drum 10, that is, the "width M of the cleaning roller in contact with the image carrier" is larger than the "effective charging width L". It needs to be short. When cleaning the photosensitive drum 10 by the cleaning roller 223 alone, it is preferable in terms of cleaning performance that the “width M of the cleaning roller that contacts the image carrier” is longer than the “image forming width S”.

On the other hand, the photosensitive drum 1 of the cleaning blade 221 located downstream of the cleaning roller 223
It is necessary that the width of contact with 0 is at least “image forming width S” or more.

FIG. 2 is a sectional view showing an example of the image forming apparatus of the present invention. In FIG. 2, a member denoted by reference numeral 10 is a photosensitive drum, which is an image carrier, and is driven to rotate clockwise. In this embodiment, an OPC photoconductor (organic photoconductor) is used as the photoconductor drum 10. Reference numeral 12 denotes a charger such as a scorotron, which applies uniform charging (minus charging in the present embodiment) to the peripheral surface of the photosensitive drum 10 by corona discharge. Prior to the charging by the scorotron charger 12, in order to remove the history in the previous image, exposure is performed by the charge remover 11 using a light emitting diode or the like to cancel the negative charge on the peripheral surface of the photoconductor, and charge is removed.

After the photosensitive drum 10 is uniformly charged, the image exposure device 13 performs image exposure based on the image signal. The image exposure device 13 in this figure uses a laser diode (not shown) as a light source. Rotating polygon mirror 131, f
The light on the photosensitive drum is scanned by the light whose optical path is bent by the reflection mirror 132 through the θ lens, and an electrostatic latent image is formed.

The electrostatic latent image is then developed by the developing device 14. At the periphery of the photoreceptor drum 10, there is arranged a developing device 14 containing a developer composed of toner and carrier such as yellow, magenta, cyan, and black. The rotation is performed by the developing sleeve 141 that rotates. The developer is composed of, for example, a carrier in which ferrite is used as a core and an insulating resin is coated around the core, and a polyester is used as a main material, and a pigment according to a color, a charge control agent, silica, and a toner to which titanium oxide is added. The agent is applied on the developing sleeve 141 by a layer forming means (not shown).
The toner is conveyed to the development zone while being regulated to a thickness of μm, and development is performed. At this time, normally, DC and AC biases are applied between the photosensitive drum 10 and the developing sleeve 141 to perform the development.

In the color image formation, after the visualization of the first color is completed, the second color image forming process is started, and uniform charging is performed again by the scorotron charger 12 to form the latent image of the second color. This is performed by the exposure unit 13. The image formation for the third and fourth colors is performed in the same manner as for the second color.
Four color toner images are formed on the 0 circumference. on the other hand,
In a monochrome electrophotographic apparatus, the developing device 14 is a single-color toner 1
And a toner image is formed by one development.

After the formation of the toner image on the photosensitive drum 10, the recording paper P is fed to the transfer area by the rotation of the paper feed roller 17 when the transfer timing is adjusted. In the transfer area, a transfer roller (transfer device) 18 is pressed against the peripheral surface of the photoreceptor drum 10 in synchronization with the transfer timing, and the fed recording paper P is narrowed to transfer the color toner image at once. You.

Next, the recording paper P is neutralized by a separation brush (separator) 19 brought into pressure contact with the transfer roller 18, separated from the peripheral surface of the photosensitive drum 10, conveyed to the fixing device 20, and pressed against the heat roller 201. Heating of the roller 202,
After the toner is fused by pressurization, the toner is discharged to the outside of the apparatus via the discharge roller 21. After the transfer roller 18 and the separation brush 19 have passed the recording paper P, they are retracted from the peripheral surface of the photosensitive drum 10 to prepare for the next toner image formation. On the other hand, after the recording paper P is separated, the photosensitive drum 10 contacts the cleaning roller 223 applied with the bias voltage of the cleaning device 22 to the photosensitive drum 10 by electrostatic attraction, and thereafter, is located downstream. The tip of the cleaning blade 221 is pressed against the photoconductor drum 10 and scraped off to remove and clean residual toner and paper dust on the photoconductor drum 10, and then neutralized again by the neutralizer 11 and charged by the scorotron charger 12 again. In preparation for the next toner image formation. The cleaning device 22 is the same as that described with reference to FIG.

When a color image is formed by superimposing a toner image on the photosensitive drum 10, the cleaning roller 223 and the cleaning blade 221 are retracted from the peripheral surface of the photosensitive drum 10 immediately after cleaning.

Reference numeral 30 denotes a photosensitive drum,
This is a process cartridge which is integrally detachable by integrating a charging device, a transfer device, a separator and a cleaning device. In the present embodiment, the process cartridge 30 is a plastic housing enclosing the above-mentioned members. It may be a single unit, and it may be configured to be detachable with guide means such as rails of the apparatus main body.All components of the charger, image exposure unit, developing unit, transfer unit, and cleaning device together with the photosensitive drum are process cartridges. The unit may be integrally connected, and the unit may be configured to be detachable from the apparatus main body.

The image exposure is performed by irradiating the photoreceptor with reflected light or transmitted light from the original when used as a copying machine or a printer, or by reading the original with a sensor and converting it into a signal.
Irradiation of a laser beam, driving of an LED array, and driving of a liquid crystal shutter array are performed according to this signal, and the photosensitive member is irradiated with light. In the case of a facsimile printer, the image exposure unit 13 performs exposure for printing received data.

The image forming apparatus of the present invention shown in FIG.
After repeating 000 sheets, no defect such as stain on the output image occurred. No dirt was found in the image forming apparatus.

As a comparison, in the image forming apparatus shown in FIG. 2, the toner M is completely filled in the image forming width S in the same manner except that the width M of the cleaning roller 223 in contact with the photosensitive drum 10 is longer than the effective charging width L. When the operation of forming an image was repeated, contamination of the transfer roller 18 and the separation brush 19 with toner was observed. The position of the stain almost coincided with the position outside the effective charging width L. With respect to defects such as stains in the output image, toner stains were observed on a part of the back surface of the output image in the latter half of the running.

[0039]

According to the present invention, in an electrophotographic image forming method, an image carrier is cleaned using a cleaning roller to which a bias voltage is applied. Toner adheres to an end of the image carrier in a width direction, and an image is formed. A cleaning device, a process cartridge, and an image forming device that solve the problem of fouling the inside of the forming device can be provided.

[Brief description of the drawings]

FIG. 1 shows a cleaning device and an image carrier of the present invention;
FIG. 3 is a diagram illustrating a relationship between a charger and a developing device.

FIG. 2 is a sectional view showing an example of the image forming apparatus of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 photoconductor drum (image carrier) 11 static eliminator 12 charger 13 image exposure device 14 developing device 17 paper feed roller 18 transfer roller 19 separation brush 20 fixing device 21 paper discharge roller 22 cleaning device 30 process cartridge 221 cleaning blade 222 spring 223 Cleaning roller 224 Blade 225 Toner recovery roller 227 Power supply (bias voltage applying means) 228 Power supply controller

Claims (7)

[Claims] 1. A cleaning device for cleaning an image carrier, the cleaning device comprising: a cleaning roller for cleaning by contacting the image carrier; and a bias voltage application unit for applying a bias voltage to the cleaning roller. Wherein the width of contact with the image carrier is shorter than the effective charging width of the image carrier. 2. The cleaning device according to claim 1, wherein a width of the cleaning roller in contact with the image carrier is longer than an image forming width of the image carrier. 3. The cleaning device according to claim 1, wherein the cleaning roller is a conductive elastic roller. 4. The apparatus according to claim 1, further comprising a cleaning blade downstream of said cleaning roller.
4. The cleaning device according to any one of 3. 5. A process cartridge detachable from a main body of an image forming apparatus, the process cartridge comprising at least an image carrier and the cleaning device according to claim 1. Description: 6. An image forming apparatus comprising the cleaning device according to claim 1. Description: 7. An image forming apparatus to which the process cartridge according to claim 5 is mounted.