JP2010032586A - Cleaning device for image carrier, cleaning method, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve cost reduction with a small power supply, while effectively removing an external additive remaining on an image carrier after transfer. <P>SOLUTION: The cleaning device for a photoreceptor 2 includes: a destaticizing device 3 that eliminates potential of the photoreceptor 2 with destaticizing light after transfer; a brush roller 4a that electrostatically removes at least residual non-transferred toner remaining on the destaticized photoreceptor 2 by forming electric field between the photoreceptor 2 and the brush roller when predetermined bias is applied thereto; and a control means that changes the destaticizing light quantity of the destaticizing device 3 between when an image is formed and when an image is not formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a cleaning device and a cleaning method for an image carrier for removing residual toner and external additives remaining after transfer, and an electrophotographic apparatus such as an electrostatic copying machine, a printer, and a facsimile equipped with the cleaning device. The present invention relates to the technical field of image forming apparatuses.

2. Description of the Related Art Conventionally, in an image forming apparatus, a residual toner after transfer at the time of image formation is charged to a predetermined polarity by a first brush roller, and then the charged residual toner is electrically adsorbed by a second brush roller to photoconductor After the image forming process is completed, the polarity of the voltage applied to the first brush roller is reversed with respect to the previous polarity, and the residual toner between the first and second brush rollers is removed from the first brush roller. A method and apparatus for cleaning a photoconductor that is removed by a brush roller has been proposed (see, for example, Patent Document 1).
Japanese Patent No. 3050689.

In the photoconductor cleaning method and apparatus described in Patent Document 1, the polarity of the bias applied to the first brush roller is changed between non-image formation and image formation. For this reason, it is necessary to largely change the bias of the first brush roller between non-image formation and image formation. Therefore, a large power supply must be used, and not only the cost is high, but there is a problem that noise is generated.

The present invention has been made in view of such circumstances, and an object thereof is to achieve cost reduction with a small power source while effectively removing external additives remaining on an image carrier after transfer. An image bearing member cleaning device, a cleaning method, and an image forming apparatus that can perform the above operation are provided.

In order to solve the above-described problem, in the carrier cleaning device, the cleaning method, and the image forming apparatus according to the present invention, the amount of static elimination of the static elimination member is changed between image formation and non-image formation. This changes the direction of the electric field between the image carrier and the conductive member during image formation and during non-image formation. During image formation, the transfer residual toner and external additives of the image carrier are transferred to the conductive member. At the time of non-image formation, the transfer residual toner and external additive of the conductive member can be moved to the image carrier and removed from the conductive member. That is, the image carrier can be effectively cleaned and the conductive member can be effectively prevented from being stained. Therefore, since both the cleaning and charging of the image carrier can be maintained well, an image with good image quality can be formed over a long period of time.
In particular, the bias applied to the conductive member during image formation and during non-image formation has the same polarity as the polarity of the toner used during image formation, and the direction of the electric field between the image carrier and the conductive member By controlling so as to change, it is possible to more effectively remove the transfer residual toner and the external additive of the image carrier.

Further, since it is not necessary to change the polarity of the bias of the conductive member when the image carrier is cleaned (during non-image formation), the change in the bias is small, the power supply can be reduced correspondingly, and the cost can be reduced. Generation can be suppressed.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically and partially showing an example of an embodiment of an image forming apparatus according to the present invention. Further, the toner includes toner base particles and an external additive externally added to the toner base particles.
In the image forming apparatus 1 of this example, image formation is performed using negatively charged toner. Of course, image formation can also be performed using positively charged toner. In the following description, the image forming apparatus 1 is described as using negatively charged toner. However, when positively charged toner is used, the charging potential of each member described below may be reversed.

As shown in FIG. 1, the image forming apparatus 1 of this example includes a photoreceptor 2 that is an image carrier on which an electrostatic latent image and a toner image are formed. The photosensitive member 2 is composed of a photosensitive drum, and a photosensitive layer having a predetermined thickness is formed on the outer peripheral surface of a cylindrical metal base tube in the same manner as a conventionally known photosensitive drum.
A conductive tube such as aluminum is used for the metal base tube in the photoreceptor 2 and a conventionally known organic photoreceptor is used for the photosensitive layer.

Around the photosensitive member 2, a static eliminating device 3, a cleaning device 4, a charging device 5, an exposure device 6, a developing device 7, and a transfer device 8 are arranged in the order of rotation of the photosensitive member 2 (see FIG. 1). Then, it is arranged along the clockwise direction. Although not shown, the image forming apparatus 1 of this example is
An electronic control device (control means) for controlling the photoreceptor 2, the charge eliminating device 3, the cleaning device 4, the charging device 5, the exposure device 6, the developing device 7, and the transfer device 8 is provided.
The neutralizing device 3 neutralizes the potential of the photosensitive member 2 after the transfer with a neutralizing light. In this case, a conventionally known static elimination device can be used as the static elimination device 3.

The cleaning device 4 has a brush roller 4a that is rotatably provided. The second brush roller 4 a has a large number of bristles 4 b, and these bristles 4 b are disposed in contact with the surface of the photoreceptor 2. As an example of this brush roller 4a, brush bristles 3b
The material is 6 nylon, the fineness is 220T / 96F, the density is 240 kf / inch ² , the yarn resistance is 7.1 LogΩ, the pile length is 5 mm, and the photosensitive member 2 of the charging brush roller 3a.
(Length along the axial direction) is 300 mm. A brush roller manufactured by Toei Sangyo Co., Ltd. can be used as the brush roller 4a.

A negative direct current (DC) bias V ₁ (V) having the same polarity as the toner is applied to the brush roller 4a. In this case, the bias V ₁ (V) is set to such a magnitude that no discharge occurs between the brush bristles 4b and the surface of the photosensitive member 2, that is, a magnitude that does not exceed the discharge limit. Then, the bias V ₁ (V) is applied to the brush roller 4a, whereby the photosensitive member 2 and the brush roller 4a.
An electric field is formed between the two. The rotation control of the brush roller 4a and the bias application control are as follows:
This is done with an electronic control unit. The cleaning device 4 can use a rubber roller or the like in addition to the brush roller.

The charging device 5 charges the surface of the photoconductor 2 to a predetermined potential set at the time of image formation. As the charging device 5, a conventionally known charging device can be used. Similarly, conventionally well-known and commonly used exposure devices, developing devices, and transfer devices can be used for the exposure device 6, the developing device 7, and the transfer device 8, respectively.

By the way, in the image forming apparatus 1 of this example, the electronic control unit controls the static elimination light amount of the static elimination apparatus 3 so as to change between image formation and non-image formation. Further, the bias V ₁ (V) applied to the brush roller 4a by the electronic control unit is the same as the polarity of the toner used during image formation during image formation and during non-image formation, and the photosensitive member 2 It is controlled to change the direction of the electric field between the brush roller 4a. As a result, the untransferred toner and the external additive remaining on the surface of the photoreceptor 2 after the transfer process is moved during image formation to the brush roller 4a, and the untransferred toner moved to the brush roller 4a during non-image formation. The external additive is controlled to move to the photoreceptor 2.

Next, the operation of the image forming apparatus 1 of this example will be described.
When the image forming operation of the image forming apparatus 1 is started, the photoconductor 2 is rotated and the surface of the photoconductor 2 is uniformly charged by the charging device 5. Next, the exposure device 6 exposes the surface of the photoconductor 2 to write an image, and an electrostatic latent image having a negative polarity potential is formed on the photoconductor 2. The electrostatic latent image on the photoreceptor 2 is developed with toner charged to a predetermined potential from the developing device 7, and a toner image is formed on the photoreceptor 2. The toner image on the photoreceptor 2 is transferred to the transfer device 8.
Is transferred to a transfer medium 9 such as a transfer material such as paper or an intermediate transfer medium. Similar to the conventional image forming apparatus, when the transfer medium 9 is a transfer material such as paper, it is fixed by a fixing device (not shown) to form a fixed image on the transfer material. When the transfer medium 9 is an intermediate transfer medium, the toner image transferred onto the intermediate transfer medium is further transferred onto a transfer material by a second transfer device (not shown) and then fixed in the same manner as described above. The image is fixed by the apparatus to form a fixed image on the transfer material.

After the transfer process is completed, the surface charge of the photosensitive member 2 is reduced in absolute value by the charge removal performed by the charge removal light set at the time of image formation from the charge removal device 3. Further, by applying a predetermined bias V ₁ (V) set at the time of image formation to the brush roller 4a, the photoreceptor 2 and the brush roller 4a.
An electric field is formed between the two. Thereby, after the transfer process is completed, the transfer residual toner and the external additive remaining on the photoreceptor 2 are electrostatically attracted toward the brush roller 4a. The attracted toner adheres to the brush bristles 4b.
Next, the surface of the photoreceptor 2 is uniformly charged again by the charging device 5. Thus, the next image forming operation is performed.

On the other hand, the electronic control unit drives the image forming apparatus 1 in order to clean the photoreceptor 2 during non-image formation. At this time, the charge removal amount of the charge removal device 3 is changed with respect to the charge removal amount at the time of image formation, and the bias V ₁ (V) applied to the brush roller 4a is in the direction opposite to that at the time of image formation. It is controlled to become. As a result, the toner adhering to the brush bristles 4b of the brush roller 4a is drawn toward the photosensitive member 2. The toner moved to the photosensitive member 2 is transferred and removed by the transfer device 8.

According to the image forming apparatus 1 of this example, the amount of charge removed by the charge removal apparatus 3 is changed between image formation and non-image formation. As a result, the direction of the electric field between the photoconductor 2 and the brush roller 4a is changed during image formation and during non-image formation. During image formation, residual toner and external additives on the photoconductor 2 are transferred to the brush roller 4a. At the time of non-image formation, the transfer residual toner and the external additive of the brush roller 4a can be moved to the photoreceptor 2 and removed from the brush roller 4a. That is, the photosensitive member 2 can be effectively cleaned, and contamination of the brush roller 4a can be effectively suppressed.
Therefore, both the cleaning and charging of the photoreceptor 2 can be maintained well, and an image with good image quality can be formed over a long period of time.

In particular, the bias applied to the brush roller 4a during image formation and during non-image formation has the same polarity as the polarity of the toner used during image formation, and the direction of the electric field between the photoreceptor 2 and the brush roller 4a. By controlling so as to change, it is possible to more effectively remove the transfer residual toner and the external additive of the photoreceptor 2.

In addition, the bias V ₁ of the brush roller 4a when the photosensitive member 2 is cleaned (when an image is not formed).
Since it is not necessary to change the polarity of (V), the change of the bias V ₁ (V) can be reduced, the power supply can be reduced accordingly, the cost can be reduced, and the generation of noise can be suppressed.
As shown in FIG. 1, the neutralization device 3 and the cleaning device 4 in the image forming apparatus 1 of this example are shown to be different from each other, but as is clear from the above description, the neutralization device 3.
Has a cleaning function. Therefore, the cleaning device 4 may include the static elimination device 3.

FIG. 2 is a diagram schematically and partially showing another example of the embodiment of the image forming apparatus of the present invention.
As shown in FIG. 2, the image forming apparatus 1 of this example is not provided with the charging device 5 shown in FIG.
In the image forming apparatus 1 of this example, the brush roller 4 a of the cleaning device 4 also charges the photosensitive member 2. That is, the brush roller 4a of the cleaning device 4 is also configured as a charging brush roller of the charging device.
Other configurations of the image forming apparatus 1 of this example are the same as those of the image forming apparatus 1 of the example shown in FIG.
The operational effects of the image forming apparatus 1 of this example are the same as those of the image forming apparatus 1 of the example shown in FIG.

Next, Examples 1 to 3 and Comparative Example 1 of each bias in the cleaning device 4 and the image forming apparatus 1 of the present invention will be described. In this case, each of Examples 1 to 3 and Comparative Example 1 is an example in which a color printer LP9000C (discharge start voltage Vth (V): −600 V) manufactured by Seiko Epson Corporation is partially modified and applied. And it is a comparative example.
Example 1 is shown in Table 1.

Example 1 is an example of the image forming apparatus shown in FIG.
This is an example using positively charged toner. As shown in Table 1, in Example 1, the static eliminator 3 is turned ON during image formation. As a result, the photosensitive member 2 is neutralized by the neutralizing light from the neutralizing device 3 after the transfer process, and the surface potential of the photosensitive member becomes approximately −20V. Brush roller 4
A bias of −300 V is applied to a, and the untransferred toner and the external additive move from the photoreceptor 2 to the brush roller 4a.

On the other hand, at the time of non-image formation after the end of image formation, the static eliminator 3 is turned off. This
The static elimination light from the static elimination device 3 disappears. That is, at the time of non-image formation, the charge removal amount of the charge removal device 3 is changed as compared to the image formation. Therefore, the photoreceptor 2 is not neutralized, and the photoreceptor surface potential is approximately −300V. Further, a bias of −100 V is applied to the brush roller 4a. That is, at the time of non-image formation, the bias applied to the brush roller 4a is changed in the same polarity as that at the time of image formation. Then, during non-image formation, the direction of the electric field formed between the photoreceptor 2 and the brush roller 4a changes in the opposite direction to that during image formation. As a result, the untransferred toner and the external additive that have moved to the brush roller 4 a move to the photoreceptor 2.
Example 2 is shown in Table 2.

In the second embodiment, similarly to the first embodiment, the transfer residual toner (positively charged toner) of the negative charging process is used in the image forming apparatus shown in FIG. As shown in Table 2, this Example 2
Then, during image formation, the static eliminator 3 is turned on. As a result, the photosensitive member 2 is neutralized by the neutralizing light from the neutralizing device 3 after the transfer process, and the surface potential of the photosensitive member becomes approximately −20V. Further, a bias of −200 V is applied to the brush roller 4a, and the transfer residual toner and the external additive move from the photoreceptor 2 to the brush roller 4a.

On the other hand, at the time of non-image formation after the end of image formation, the static eliminator 3 is turned off. This
The static elimination light from the static elimination device 3 disappears. That is, at the time of non-image formation, the charge removal amount of the charge removal device 3 is changed as compared to the image formation. Therefore, the photoreceptor 2 is not neutralized, and the photoreceptor surface potential is approximately −300V. Further, a bias of −200 V is applied to the brush roller 4a. That is, the bias applied to the brush roller 4a is not changed between image formation and non-image formation. However, by changing the amount of charge removal, the direction of the electric field formed between the photoconductor 2 and the brush roller 4a changes in the opposite direction to that during image formation during non-image formation. As a result, the untransferred toner and the external additive that have moved to the brush roller 4 a move to the photoreceptor 2.
Example 3 is shown in Table 3.

Example 3 is a transfer residual toner (positive charging process) in the image forming apparatus shown in FIG.
This is an example using negatively charged toner. As shown in Table 3, in Example 3, the static eliminator 3 is turned off during image formation. Thereby, the static elimination light from the static elimination apparatus 3 disappears. Therefore, the photoreceptor 2 is not neutralized, and the photoreceptor surface potential is approximately −300V. Further, a bias of −100 V is applied to the brush roller 4a, and the transfer residual toner and the external additive move from the photoreceptor 2 to the brush roller 4a.

On the other hand, at the time of non-image formation after completion of image formation, the static eliminator 3 is turned on. As a result, the photosensitive member 2 is neutralized by the neutralizing light from the neutralizing device 3 after the transfer process, and the surface potential of the photosensitive member becomes approximately −20V. That is, at the time of non-image formation, the charge removal amount of the charge removal device 3 is changed as compared to the image formation. Further, a bias of −300 V is applied to the brush roller 4a. That is, at the time of non-image formation, the bias applied to the brush roller 4a is changed in the same polarity as that at the time of image formation. Then, during non-image formation, the direction of the electric field formed between the photoreceptor 2 and the brush roller 4a changes in the opposite direction to that during image formation. As a result, the untransferred toner and the external additive that have moved to the brush roller 4 a move to the photoreceptor 2.
Example 4 is shown in Table 4.

Example 4 is an example in which the transfer residual toner (positively charged toner) of the negative charging process is used in the image forming apparatus of the example shown in FIG. 2, that is, the image forming apparatus in which the brush roller 4 also serves as a charging brush roller. As shown in Table 4, in Example 4, the static eliminator 3 is turned on during image formation.
To. As a result, the photoreceptor 2 is neutralized by the neutralizing light from the neutralizing device 3 after the transfer process,
The photoreceptor surface potential is approximately −20V. In addition, a large bias of −1200 V is applied to the brush roller 4a to charge the photosensitive member 2 and transfer residual toner and external additives move from the photosensitive member 2 to the brush roller 4a.

On the other hand, at the time of non-image formation after the end of image formation, the static eliminator 3 is turned off. This
The static elimination light from the static elimination device 3 disappears. That is, at the time of non-image formation, the charge removal amount of the charge removal device 3 is changed from that at the time of image formation. Therefore, the photoreceptor 2 is not neutralized, and the photoreceptor surface potential is approximately −300V. Further, a bias of −100 V is applied to the brush roller 4a. That is, at the time of non-image formation, the bias applied to the brush roller 4a is changed in the same polarity as that at the time of image formation. Then, during non-image formation, the direction of the electric field formed between the photoreceptor 2 and the brush roller 4a changes in the opposite direction to that during image formation. As a result, the untransferred toner and the external additive that have moved to the brush roller 4 a move to the photoreceptor 2.
Table 5 shows Comparative Example 1.

Comparative Example 1 is an example using the conventional image forming apparatus shown in FIG. As shown in FIG. 3, this image forming apparatus changes the polarity of the bias applied to the brush roller 4a in the image forming apparatus shown in FIG. 1 between image formation and non-image formation. Further, in Comparative Example 1, untransferred toner (positively charged toner) in the negative charging process is used. As shown in Table 5, in this comparative example 1, the static eliminator 3 is turned on during image formation. Thereby, after the transfer step, the photosensitive member 2
Is neutralized by the neutralizing light from the neutralizing device 3, and the surface potential of the photosensitive member becomes approximately -20V.
In addition, a bias of −300 V is applied to the brush roller 4a, and the untransferred toner and the external additive move from the photosensitive member 2 to the brush roller 4a.

On the other hand, the static eliminator 3 is kept ON even during non-image formation after completion of image formation. As a result, the charge is removed by the charge removal light from the charge removal device 3, and the surface potential of the photosensitive member becomes approximately -20V. That is, the amount of electricity removed from the electricity removal apparatus 3 is not changed between non-image formation and image formation. In addition, a bias of +300 V is applied to the brush roller 4a. That is, during non-image formation,
The applied bias of the brush roller 4a has a reverse polarity and a large bias with respect to image formation. Therefore, in Comparative Example 1, the polarity of the bias applied to the brush roller 4a is changed between non-image formation and image formation. As a result, the untransferred toner and the external additive that have moved to the brush roller 4 a move to the photoreceptor 2.
As described above, in Comparative Example 1, the amount of charge removal of the charge removal device 3 is not changed, and the brush roller 4
The polarity and magnitude of the bias V ₁ (V) of a are changed. Therefore, a correspondingly large power source is required, which not only increases the cost but also generates noise.

1 is a diagram schematically and partially showing an example of an embodiment of an image forming apparatus according to the present invention. It is a figure showing other examples of an embodiment of an image forming device concerning the present invention typically and partially. It is a figure which shows the conventional image forming apparatus as a comparative example typically and partially.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Photoconductor, 3 ... Static elimination apparatus, 4 ... Cleaning apparatus, 4a ... Brush roller, 5 ... Charging apparatus, 6 ... Exposure apparatus, 7 ... Developing apparatus, 8 ... Transfer apparatus, 9 ... Transfer medium

Claims (9)

A static elimination member that neutralizes the potential of the image carrier with static elimination light after transfer;
A conductive member that electrostatically removes at least transfer residual toner remaining on the image carrier that has been neutralized by forming an electric field between the image carrier and a predetermined bias applied;
A control means for changing the amount of static elimination of the static elimination member between image formation and non-image formation;
An image carrier cleaning device comprising: The control means controls the bias applied to the conductive member so as to change the direction of the electric field with the same polarity as the polarity of toner used during image formation, during image formation and during non-image formation. The image carrier cleaning device according to claim 1, wherein A static elimination member that neutralizes the potential of the image carrier with static elimination light after transfer;
A conductive member that electrostatically removes at least transfer residual toner remaining on the image carrier that has been neutralized by forming an electric field between the image carrier and a predetermined bias applied;
Control means for controlling the bias applied to the conductive member during image formation and during non-image formation to change the direction of the electric field with the same polarity as the polarity of the toner used during image formation;
An image carrier cleaning device comprising: 4. The image carrier cleaning apparatus according to claim 1, wherein the conductive member is a cleaning brush roller that cleans the image carrier. 5. 4. The image carrier cleaning apparatus according to claim 1, wherein the conductive member is a charging brush roller that charges the image carrier. A neutralization step of neutralizing the potential of the image bearing member with a neutralizing light after transfer;
A cleaning process for electrostatically removing at least transfer residual toner remaining on the image carrier that has been neutralized by forming an electric field between the conductive member to which a predetermined bias is applied and the image carrier; ,
A static elimination light control step for changing the static elimination light amount of the static elimination member between image formation and non-image formation,
An image carrier cleaning method comprising: A conductive member bias control step for changing a bias applied to the conductive member at the time of image formation and non-image formation to the same polarity as the toner used at the time of image formation and changing the direction of the electric field;
The image carrier cleaning method according to claim 6, further comprising: A neutralization step of neutralizing the potential of the image bearing member with a neutralizing light after transfer;
A cleaning process for electrostatically removing at least transfer residual toner remaining on the image carrier that has been neutralized by forming an electric field between the conductive member to which a predetermined bias is applied and the image carrier; ,
A conductive member bias control step for changing a bias applied to the conductive member at the time of image formation and non-image formation to the same polarity as the toner used at the time of image formation and changing the direction of the electric field;
An image carrier cleaning method comprising: An image carrier provided rotatably and on which a latent image is formed;
An exposure device for writing a latent image on the image carrier;
A developing device that develops the latent image of the image carrier with toner charged to a predetermined polarity and externally added;
A transfer device for transferring the developed toner image on the image carrier to a transfer medium;
A cleaning device according to any one of claims 1 to 5, wherein the transfer residual toner remaining on the image carrier after the transfer is removed by a conductive member.
An image forming apparatus comprising:

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