JP2002251076A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device constituted so that the occurrence of an afterimage, filming on an intermediate transfer medium, toner scattering and the mixture of color may be prevented by stabilizing the unstable electrified polarity of toner left on the intermediate transfer medium after a transfer process and enhancing the performance of a cleaning device. SOLUTION: The polarity of a bias applied on a fur brush 10 positioned at the prestage of an electrostatic recovering roller 20 in the traveling direction of the intermediate transfer belt 501 is made the same as that of the toner left after the transfer process. The fur brush 10 is rotated in a direction opposite to the traveling direction of the intermediate transfer belt 501, and the rotating speed is made >=2 times as high as the traveling speed of the intermediate transfer belt 501. The polarity of a bias applied on the electrostatic recovering roller 20 is made opposite to that of the bias applied on the fur brush 10. The voltage level of the bias applied on the electrostatic recovering roller 20 is controlled to be equal to or below the voltage of the bias applied on the conductive fur brush. Besides, the intermediate transfer belt 501 is wound around the electrostatic recovering roller 20 so as to rotate together. The surface layer of the intermediate transfer belt 501 is constituted of an elastic body, and the base layer is constituted of a hard body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.
In particular, the present invention relates to an image forming apparatus having a cleaning device for an intermediate transfer medium.

[0002]

2. Description of the Related Art Conventionally, as a full-color image forming apparatus, for example, after a toner image formed on an image carrier is primarily transferred onto an intermediate transfer medium, a transfer belt for conveying a final transfer medium is provided. In a secondary transfer nip portion where an intermediate transfer medium is pressed against, a configuration is generally known in which an image is formed by secondary transfer from the intermediate transfer medium to transfer paper. In the case of the above configuration, in order to overlap the toner image on the intermediate transfer medium, the cleaning device is brought into contact with and separated from the intermediate transfer medium in the non-image area according to the toner image formation,
It is necessary to clean the surface of the intermediate transfer medium. When the contact and separation are performed in the image area, the toner stain on the intermediate transfer medium generated at the time of the contact and separation becomes an image stain. Therefore, the contact and separation are performed in the non-image area.

As a cleaning device for an intermediate transfer medium, a cleaning blade system has been generally used. FIG. 1 is a schematic configuration diagram of an image forming unit as a main part in a general image forming apparatus using a cleaning blade system. However, in the cleaning blade method, the toner easily accumulates at the edge of the cleaning blade 2, and the toner drops and scatters when the cleaning blade 2 comes into contact with and separates from the cleaning blade 2. If the cleaning performance of the intermediate transfer medium 5 is insufficient, an afterimage or transfer failure unevenness due to a resistance change due to toner filming of the intermediate transfer medium 5 occurs. Further, the toner scattered due to the impact at the time of contact and separation easily adheres not only to the cleaning blade 2 of the intermediate transfer medium 5 but also to the surface of the intermediate transfer medium 5 in a wide area because the toner spreads during scattering. To prevent the scattering toner from adhering to the image area, it is good to set the non-image area to be large. However, in the recent miniaturized image forming apparatus, it is not possible to make the non-image area larger than necessary due to the limitation of the circumference of the intermediate transfer medium 5. It is not a practical solution. Further, when an elastic material is used as the material of the intermediate transfer medium 5 in the image forming apparatus using the cleaning blade system, the friction with the cleaning blade 2 increases, and the cleaning blade 2 may sound or be involved.

As one method for solving such a problem, there is a brush cleaning method using a fur brush. This method includes a method using an insulating fur brush and a method applying a cleaning voltage to the conductive fur brush. However, the charge polarity of the toner remaining without being transferred is unstable, and the polarity may be reversed by the paper transfer electric field. Therefore, even if a bias having a polarity opposite to the normal toner polarity is applied to the conductive fur brush, toner that cannot be removed may remain.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention stabilizes the unstable charging polarity of the toner remaining on the intermediate transfer medium without being transferred, and reduces the residual toner by the cleaning device for the intermediate transfer medium. It is an object of the present invention to provide an image forming apparatus which can improve the performance of removing an image and prevent the occurrence of an afterimage, filming of an intermediate transfer medium, toner scattering, and color mixing.

[0006]

According to the first aspect of the present invention, an electrostatic latent image formed on an image bearing member is visualized as a toner image using a toner. The toner image is primarily transferred onto an intermediate transfer medium running endlessly, the toner image formed on the intermediate transfer medium is secondarily transferred onto the transfer medium, and is transferred onto the intermediate transfer medium without being transferred onto the transfer medium. A full-color image forming apparatus having a cleaning device for an intermediate transfer medium for removing residual toner, wherein a bias is applied to a conductive fur brush and electrostatic transfer recovery is performed by a conductive roller; I do. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the conductive fur brush is located upstream of the conductive roller that performs electrostatic transfer and recovery in the intermediate transfer medium traveling direction. Equipment. According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein a bias applied to the conductive fur brush has the same polarity as that of the residual toner. The present invention described in claim 4 is based on claim 1.
4. The image forming apparatus according to any one of claims 1 to 3, wherein the conductive fur brush rotates in a direction in which the intermediate transfer medium runs and in a counter direction.
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the rotational speed of the conductive fur brush is at least twice the traveling speed of the intermediate transfer medium. Image forming apparatus. According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the bias applied to the conductive roller for electrostatic transfer recovery is the reverse of the bias applied to the conductive fur brush. The image forming apparatus is characterized by having a polarity of According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, a bias voltage applied to the electrostatic recovery roller is equal to or less than a bias voltage applied to the conductive fur brush. The image forming apparatus is characterized in that: The present invention described in claim 8 is the first invention.
8. The image forming apparatus according to any one of claims 1 to 7, wherein the electrostatic recovery roller rotates around the intermediate transfer medium while traveling. According to a ninth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to eighth aspects, wherein the intermediate transfer medium is wound around the electrostatic recovery roller and bent. According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, the surface layer of the intermediate transfer medium is an elastic body, and the base layer is a hard body. A forming device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram of the image forming unit according to the present invention. The image forming apparatus includes, in addition to the image forming unit shown in FIG. 2, a color image reading unit (not shown), a paper feeding unit, a control unit, and the like. The image forming unit includes a photoconductor drum 100 as an image carrier, a charging charger 200, a photoconductor cleaning device 300 including a cleaning blade and a fur brush, a writing optical device (not shown), a revolver developing device 400, and an intermediate transfer including an intermediate transfer medium. Device 500, paper transfer device 600, and fixing roller pair 701
The fixing device 700 mainly includes a fixing device 700.

The photosensitive drum 100 is rotated in a counterclockwise direction indicated by an arrow by a drive motor (not shown). Around the charger, a selected developing device of a charging device 200, a photosensitive member cleaning device 300, and a revolver developing device 400, an intermediate transfer device An intermediate transfer belt 501 as an intermediate transfer medium in the apparatus 500 is arranged.

The revolver developing device 400 has a Bk (Bla
ck) Bk developing device 401 using toner, C (Cya)
n) C developing device 402 using toner, M (Magent)
a) M developing device 403 using toner, Y (Yellow)
w) A Y developing device 404 using toner, a developing revolver driving unit (not shown) for rotating the entire device counterclockwise, and the like. The toner in each developing unit is charged to a desired polarity by agitation with the carrier, and a developing bias voltage is applied to each developing sleeve by a developing bias power supply (not shown).
The bias is biased to a predetermined potential with respect to the metal substrate layer No. 00.

The intermediate transfer device 500 includes an intermediate transfer belt 501 stretched over a plurality of rollers and the like. Around the intermediate transfer belt 501, a pre-transfer charger 502 as a pre-transfer charging unit, and a paper transfer unit 600 A secondary transfer belt 601 as a transfer material carrier, a secondary transfer bias roller 605 as a secondary transfer charge applying unit, and the like are disposed so as to face each other. Intermediate transfer belt 501
Is driven clockwise by an arrow by an intermediate transfer belt driving roller 508 rotated by a driving motor (not shown). The intermediate transfer belt 501 is stretched around a plurality of rollers. Specifically, a primary transfer bias roller 507 as a primary transfer charge applying unit, a belt driving roller 508,
Belt tension roller 509, secondary transfer facing roller 5
10, a cleaning opposing roller 511, and a belt discharging roller 512 as a pre-primary transfer discharging device. Each roller is formed of a conductive material, and each roller other than the primary transfer bias roller 507 is grounded. 1
A transfer bias having a predetermined magnitude of current or voltage is applied to the next transfer bias roller 507 by a primary transfer power supply 801 controlled by a constant current or constant voltage method according to the number of superimposed toner images.

In the primary transfer section where the toner image on the photosensitive drum 100 is transferred to the intermediate transfer belt 501, the intermediate transfer is performed by a primary transfer bias roller 507 and an intermediate transfer body belt discharging roller 512 as a pre-primary transfer discharging device. The belt 501 is stretched so as to be pressed against the photosensitive drum 100 side, so that the photosensitive drum 1
A nip portion having a predetermined width is formed between the intermediate transfer belt 501 and the intermediate transfer belt 501. Further, a grounded intermediate transfer belt static elimination brush 513 as a primary transfer unit static elimination means is in contact with the inner peripheral surface of the intermediate transfer belt 501 in the nip portion.

The pre-transfer charger 502 is an intermediate transfer belt 5 transferred from the photosensitive drum 100 in a primary transfer section.
Before the toner image on the image No. 01 is transferred to transfer paper as a transfer medium, the toner image is charged uniformly.

The fur brush 10 is conductive, and can switch between contact and separation with the intermediate transfer belt 501 by a contact / separation mechanism (not shown).
The fur brush 10 has the same polarity as that of the transfer residual toner in order to make the transfer residual toner having an unstable polarity remaining on the intermediate transfer belt 501 stable due to peeling discharge generated when the transfer paper is separated after the secondary transfer. Polarity DC voltage is bias power 1
1 is applied. Further, in order to efficiently and uniformly apply the bias, the rotation direction of the fur brush 10 is rotated in the counter direction with respect to the traveling direction of the intermediate transfer belt 501, and the rotation speed of the fur brush 10 is set to the traveling speed of the intermediate transfer belt 501. Is preferably two times or more. Further, an electrostatic recovery roller 20 is provided on the rear stage side of the fur brush 10, and the contact and separation of the intermediate transfer belt 501 can be switched by a contact / separation mechanism (not shown).

Electrostatic recovery roller 2 as conductive roller
0 indicates that a DC voltage having a polarity opposite to the polarity of the bias applied by the fur brush 10 is applied by the bias power supply 21 in order to remove the transfer residual toner having a stable polarity by the fur brush 10 from the intermediate transfer belt 501. Have been. In order to prevent the transfer residual toner from being reversely transferred to the intermediate transfer belt 501, the voltage applied to the electrostatic recovery roller 20 is set to be equal to or less than the voltage applied to the fur brush 10.
The transfer residual toner that has been electrostatically transferred and removed by the electrostatic recovery roller 20 is recovered by a toner recovery blade (not shown) in contact with the electrostatic recovery roller 20 and stored in the image forming apparatus.

Fur brush 10 and electrostatic recovery roller 20
Is separated from the intermediate transfer belt 501 while the toner image is being formed on the intermediate transfer belt 501, and after the secondary transfer is completed, the fur brush 10 and the electrostatic recovery roller 20 are brought into contact with each other to clean the transfer residual toner. I do.

FIG. 3 is a schematic structural view of an image forming section according to claims 8 and 9 of the present invention. Intermediate transfer belt 50
Reference numeral 1 denotes a surface that holds the toner image, which is pressed by an electrostatic recovery roller 20 to bend in the opposite direction, so that the electrostatic recovery nip is enlarged to improve transfer efficiency and reduce friction. The size is made large so that the electrostatic recovery roller 20 rotates with the intermediate transfer belt 501 without slipping.

The intermediate transfer belt 501 includes a surface layer, an intermediate layer,
It is composed of a belt material having a multilayer structure consisting of a base layer.
The outer peripheral surface in contact with the photoreceptor drum 100 is a surface layer and an elastic layer, and the inner peripheral surface is a base layer and a hard layer that does not expand and contract. An adhesive layer for bonding the two layers is interposed between the intermediate layer and the base layer. When the surface layer is formed of an elastic body, the contact state with the transfer paper is improved, and when the base layer is formed of a hard body, stretching due to stretching does not occur, and image displacement does not occur.

[0018]

As described above, according to the first aspect of the present invention, since the bias is applied to the conductive fur brush and the electrostatic recovery is performed by the conductive roller, the transfer residual toner is reduced. Accordingly, it is possible to provide an image forming apparatus in which occurrence of afterimages, filming, toner scattering, and color mixing are prevented. According to the second aspect of the present invention, since the conductive fur brush is located upstream of the conductive roller for electrostatic recovery in the running direction of the intermediate transfer medium, the toner has a polarity different from that of the untransferred toner such as untransferred toner. Can be recovered by the conductive fur brush, and it is possible to provide an image forming apparatus in which generation of an afterimage, filming, toner scattering, and color mixing are prevented. According to the present invention as set forth in claim 3,
Since the bias applied to the conductive fur brush has the same polarity as the transfer residual toner, it is possible to stabilize the polarity of the transfer residual toner that has become unstable due to peeling discharge generated when the transfer paper is separated after the secondary transfer. Thus, it is possible to provide an image forming apparatus that prevents occurrence of an afterimage, filming, toner scattering, and color mixing. According to the present invention, since the conductive fur brush rotates in the counter-direction and in the running direction of the intermediate transfer medium, the conductive fur brush can be used for toner having a polarity different from that of the untransferred toner such as untransferred toner. Thus, an image forming apparatus can be provided which can apply a bias evenly and prevent occurrence of an afterimage, filming, toner scattering, and color mixing. According to the fifth aspect of the present invention, the rotational speed of the conductive fur brush is twice or more the running speed of the intermediate transfer medium.
Even toner whose polarity is different from that of untransferred toner such as untransferred toner can be collected by the conductive fur brush.
It is possible to provide an image forming apparatus that can apply a bias evenly and prevent occurrence of an afterimage, filming, toner scattering, and color mixing. According to the sixth aspect of the present invention, since the bias applied to the electrostatic recovery roller has the opposite polarity to the bias applied to the conductive fur brush, the transfer residual toner is efficiently transferred and recovered by the electrostatic recovery roller. Thus, it is possible to provide an image forming apparatus in which occurrence of an afterimage, filming, toner scattering, and color mixing are prevented. Claim 7
According to the present invention, since the bias voltage applied to the electrostatic recovery roller is equal to or less than the bias voltage applied to the conductive fur brush, it is possible to prevent the transfer residual toner from being reversely transferred to the intermediate transfer medium, and to generate the residual image. Forming apparatus capable of preventing filming, toner scattering, and color mixing. According to the present invention, since the electrostatic recovery roller rotates along with the travel of the intermediate transfer medium, the linear speed fluctuation of the intermediate transfer medium due to the fluctuation of the rotation of the electrostatic recovery roller can be suppressed, and the afterimage can be suppressed. It is possible to provide an image forming apparatus in which occurrence of filming, filming, toner scattering, and color mixing are prevented. According to the ninth aspect of the present invention, by winding and bending the intermediate transfer medium around the electrostatic recovery roller, the degree of freedom of arrangement can be increased, and the nip of the electrostatic recovery section can be increased to increase the electrostatic transfer efficiency. In addition, by increasing the friction by winding, the electrostatic recovery roller can be rotated without slipping, and an image forming apparatus can be provided in which occurrence of an afterimage, filming, toner scattering, and color mixing are prevented. According to the tenth aspect of the present invention, the surface layer of the intermediate transfer medium is an elastic body, and the base layer is a hard body. The present invention provides an image forming apparatus in which a desired contact state is formed during printing, a transfer failure due to a step of a toner image or the like can be prevented, and occurrence of image shift or residual image, filming, toner scattering, and color mixing are prevented. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming unit in a conventional image forming apparatus.

FIG. 2 is a schematic configuration diagram of an image forming unit in the image forming apparatus of the present invention.

FIG. 3 is a schematic configuration diagram of an image forming unit in the image forming apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 2 Cleaning blade 3 Conveyor belt 4 Developing device 5 Intermediate transfer medium 6 Paper transfer device 7 Fixing device 10 Fur brush 11 Bias power supply 20 Electrostatic recovery roller 21 Bias power supply 100 Photoconductor drum 200 Charger 300 Photoconductor cleaning device 400 Revolver developing device 401 B developing device 402 C developing device 403 M developing device 404 Y developing device 500 Intermediate transfer device 501 Intermediate transfer belt 502 Pre-transfer charger 507 Primary transfer bias roller 508 Intermediate transfer belt drive roller 509 Intermediate transfer belt tension roller 510 Secondary transfer facing roller 512 Intermediate transfer belt static elimination roller 513 Intermediate transfer belt static elimination brush 600 Paper transfer unit 601 Secondary transfer belt 701 Primary transfer power supply

Claims (10)

[Claims] 1. An electrostatic latent image formed on an image carrier is visualized as a toner image by toner, and the visualized toner image is subjected to primary transfer onto an endlessly running intermediate transfer medium, thereby performing intermediate transfer. A full-color image forming apparatus having an intermediate transfer medium cleaning device that secondary-transfers a toner image formed on a medium to a transfer medium and removes toner remaining on the intermediate transfer medium without being transferred to the transfer medium, An image forming apparatus, wherein a bias is applied to a conductive fur brush and electrostatic transfer recovery is performed by a conductive roller. 2. The image forming apparatus according to claim 1, wherein the conductive fur brush is located upstream of the conductive roller for electrostatic transfer and collection in the running direction of the intermediate transfer medium. 3. The image forming apparatus according to claim 1, wherein the bias applied to the conductive fur brush has the same polarity as that of the residual toner. 4. The image forming apparatus according to claim 1, wherein the conductive fur brush rotates in a direction in which the intermediate transfer medium runs and in a counter direction. 5. The image forming apparatus according to claim 1, wherein the rotation speed of the conductive fur brush is twice or more the running speed of the intermediate transfer medium. 6. The image forming apparatus according to claim 1, wherein the bias applied to the conductive roller for electrostatic transfer collection is:
An image forming apparatus having a polarity opposite to a bias applied to a conductive fur brush. 7. The image forming apparatus according to claim 1, wherein a bias voltage applied to the electrostatic recovery roller is equal to or less than a bias voltage applied to the conductive fur brush. Image forming apparatus. 8. The image forming apparatus according to claim 1, wherein the electrostatic recovery roller rotates around the intermediate transfer medium. 9. The image forming apparatus according to claim 1, wherein the intermediate transfer medium is wound around the electrostatic recovery roller and bent.
An image forming apparatus comprising: 10. The image forming apparatus according to claim 1, wherein a surface layer of the intermediate transfer medium is an elastic body, and a base layer is a hard body.