JP2002214996A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which prevents lowering the picture quality of subsequent toner picture formed in an image forming region owing to the attachment of scattered toner which is scattered from a cleaning member to the image forming region of an image carrier which is deprived of the remaining toner by the cleaning member. SOLUTION: This image forming device is constituted in such a manner that a release position of the cleaning blade 504 is shifted by 20 mm toward the back end position of the preceding picture from the present release position on the basis of the tip position of the subsequent picture of an intermediate transfer belt 501. Thereby, the distance L from the tip position of the subsequent picture of intermediate transfer belt 501 to the release position of the cleaning blade 504 is equal to 61 mm and the toner dropping ranking to the tip of the subsequent picture enters in the range >=4 which allows the attachment of the scattered toner.

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.
An image forming apparatus including a cleaning unit that removes residual toner on an image carrier after transferring a toner image to a transfer material by bringing a cleaning member that comes into contact with and separates from the surface of the image carrier into contact with the surface. It is to be.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus of this type, an image carrier such as a photosensitive drum, a photosensitive belt, or an intermediate transfer belt has been used, and a toner image carried on the image carrier is transferred. There is known an image forming apparatus which transfers an image to a transfer material such as a sheet or an OHP sheet by means to form an image. In this image forming apparatus, after the toner image carried on the image carrier is transferred to the transfer material, the residual toner remaining on the image carrier without being transferred to the transfer material is removed by a cleaning unit. It is configured to remove.

For example, in an "image forming apparatus" disclosed in Japanese Patent Application Laid-Open No. 11-231667, residual toner on a photosensitive drum as the image carrier is removed by using a cleaning blade and a fur brush which are cleaning members of the cleaning means. To remove it. Further, in this image forming apparatus, the residual toner on the intermediate transfer belt carrying the toner image primarily transferred from the photosensitive drum is removed by using a belt cleaning blade as the cleaning member. .

When the toner image is carried on the image carrier, the cleaning member is separated from the surface of the image carrier, and the image carrier is removed only when the residual toner on the image carrier is removed. It is configured to be able to freely contact and separate from the image carrier by a contact / separation mechanism so as to contact the surface of the body.

[0005]

However, as described above, in an image forming apparatus configured to remove the residual toner by using a cleaning member that comes into contact with and separates from the image carrier, the image forming apparatus removes the residual toner during the process of removing the residual toner. The toner adhered to the cleaning member sometimes scattered when the cleaning member was separated from the surface of the image carrier. It is considered that such toner scattering is caused by vibration or impact applied to the cleaning member when the cleaning member is separated from the surface of the image carrier by the contact / separation mechanism.

Therefore, in this type of conventional image forming apparatus, the scattered toner scattered from the cleaning member adheres to the image forming area of the image carrier from which the residual toner has been removed by the cleaning member. The image quality of the next toner image formed in the image forming area sometimes deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to disperse scattered particles from the cleaning member to the image forming area of the image carrier from which residual toner has been removed by the cleaning member. It is an object of the present invention to provide an image forming apparatus capable of preventing the image quality of the next toner image formed in the image forming area from deteriorating due to toner adhesion.

[0008]

According to one aspect of the present invention, there is provided an image carrier that carries a toner image on a surface thereof and moves the toner image on the surface of the image carrier. A transfer unit that transfers an image to a transfer material, and a cleaning member configured to be able to freely contact and separate from the surface of the image carrier, by moving the image carrier in contact with the surface,
A cleaning unit that removes residual toner on the image carrier after transferring the toner image to the transfer material, wherein the residual toner on the image carrier is brought into contact with the surface of the image carrier. The release position of the cleaning member on the image carrier at which the cleaning member from which the cleaning member is removed is separated from the surface of the image carrier is determined with reference to the tip position of the next image forming area formed on the image carrier. The image is shifted toward the rear end position of the image before the residual toner is removed by the cleaning member.

In this image forming apparatus, the distance in the image carrier moving direction from the release position of the cleaning member on the image carrier to the tip of the next image forming area of the image carrier becomes large. This makes it difficult for the scattered toner scattered from the cleaning unit to reach the next image forming area. This makes it difficult for the scattered toner to adhere to the next image forming area of the image carrier, thereby preventing the image quality of the next toner image formed in the next image forming area from being degraded.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the cleaning unit is configured to contact and separate the surface of the image carrier with respect to the moving direction upstream of the cleaning member. It is characterized by having a member.

In this type of image forming apparatus, in the process of removing the residual toner on the image carrier by the cleaning member of the cleaning means, a part of the residual toner removed by the cleaning member is removed by the cleaning member. There is a possibility that the toner is not collected by a predetermined toner collecting unit of the means and falls off and scatters on the conveyance path of the transfer material. The toner seal member is provided to prevent such falling toner from scattering. However,
In an image forming apparatus having such a toner seal member, scattering is prevented by the toner seal member, and toner attached to the toner seal member is scattered when the toner seal member is separated from the surface of the image carrier. Sometimes. In the image forming apparatus of the present invention, the release position of the cleaning member is shifted, so that the release position of the toner seal member from the image carrier can also be shifted. This makes it difficult for the scattered toner scattered from the toner seal member to reach the next image forming area of the image carrier, and is formed in the next image formed area by the scattered toner scattered from the toner seal member. It is possible to suppress a decrease in image quality of the next toner image.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the image forming apparatus further includes a lubricant applying member which comes into contact with and separates from the surface of the image carrier and applies a lubricant to the surface. An application member contacting / separating means for bringing the lubricant applying member into contact with / separating from the surface of the body, independent of a cleaning member contacting / separating means for bringing the cleaning member of the cleaning means into contact with / separating from the surface of the image carrier; Further, the lubricant applying member is configured to be brought into contact with and separated from a non-image area on the surface of the image carrier.

As this type of image forming apparatus, for example, a lubricant is applied to the surface of an image carrier and a filming layer is formed on the surface, as in "Image Forming Apparatus" in JP-A-11-231667. There is known one that prevents it from being formed. The lubricant is applied to the surface of the image carrier after the residual toner has been removed by the cleaning member. That is, the lubricant applying member for applying the lubricant is disposed at a position downstream of the cleaning unit in the moving direction of the image carrier. Therefore, in this type of image forming apparatus, usually, a cleaning member contacting / separating unit for bringing a cleaning member of a cleaning unit into contact with / separating from the surface of the image carrier is used to connect the lubricant application member to the image carrier. It is configured to contact and separate from the surface. Further, in this type of image formation, in order to prevent the cleaning member from getting caught in the blade when removing the residual toner, the lubricant is surely applied to at least the image forming area on the surface of the image carrier. It is applied. That is, the lubricating member is brought into contact with and separated from the surface of the image carrier in a non-image area of the image carrier.
However, in the image forming apparatus of the present invention, as described above, the distance from the release position of the cleaning member to the leading end of the next image area is different from that of the next image forming area. The distance is set to be difficult to reach. That is, the release position of the cleaning member of the image forming apparatus of the present invention is a position shifted to the downstream side in the image carrier moving direction from the release position of the conventional cleaning member. For this reason, when the lubricant applying member is configured to be brought into contact with and separated from the cleaning member by the cleaning member contacting / separating means, the release position of the lubricant applying member is located downstream of the rear end of the previous image forming area in the image carrier moving direction. There is a possibility that the lubricant may not be applied to the rear end of the preceding image forming area because of the position shifted to the side part. In particular,
In order to make effective use of the surface of the image carrier, an A4 size image can be formed on two surfaces of the image carrier.
In the image forming apparatus having the 4-Fc2 chamfering configuration, the distance from the rear end of the preceding image forming area to the front end of the next image forming area is set shorter. For this reason, when the present invention is applied to the image forming apparatus having the A4 / Fc2 chamfering configuration, an area where the lubricant is not applied is generated at the rear end of the previous image forming area. Therefore,
In the image forming apparatus of the present invention, the coating member contacting / separating means for bringing the lubricant applying member into contact with / separating from the surface of the image carrier,
The cleaning member is separated from the cleaning member contacting / separating means for bringing the cleaning member of the cleaning means into and out of contact with the surface of the image carrier. Then, the lubricant applying member is made to independently approach and separate from the non-image area on the surface of the image carrier by the applying member approaching / separating means. This makes it possible to apply the lubricant reliably to at least the image forming area on the surface of the image carrier, and to prevent the cleaning member from getting caught in the blade when removing the residual toner. Become like

According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, as the lubricant applying member, a lubricant which is brought into contact with a solid lubricant and is scraped off is applied to the surface of the image carrier. A rotating brush is used.

By using a rotary brush as the lubricant applying member, there is an advantage that the means for applying the lubricant can be configured simply and inexpensively. However, when a lubricant is applied to the surface of the image carrier using the rotating brush,
Separated position (release position) of the rotating brush on the surface of the image carrier
In some cases, traces of release of the rotary brush (print traces of the lubricant applied by the rotary brush) may remain. If the release mark of the rotating brush remains in the image forming area of the image carrier, the image quality of the toner image formed in the image forming area may be deteriorated by the release mark. Therefore, when such a rotating brush is used as a lubricant applying member, the rotating brush is configured to be able to contact and separate from the non-image area of the image carrier, and the rotating brush is moved to the image forming area of the image carrier. It is preferable that no release marks remain. In the image forming apparatus of the present invention, as described above, the lubricant application member can be brought into contact with and separated from the non-image area on the surface of the image carrier. Therefore, in the image forming apparatus of the present invention, even if a rotary brush is used as the lubricant applying member, it is possible to prevent the release trace of the rotary brush from being left in the image forming area of the image carrier.

Further, the invention of claim 5 is the invention according to claims 1, 2,
The image forming apparatus according to (3) or (4), further comprising a charge removing member that comes into contact with and separates from the surface of the image carrier after transferring the toner image to the transfer material, and removes residual charge remaining on the surface of the image carrier. A static elimination member contacting / separating means for bringing the static elimination member into and out of contact with the surface of the image carrier at a position upstream of the cleaning member release position of the cleaning member on the surface of the image carrier; The discharging member is brought into contact with the surface of the image carrier, and the discharging member is separated from the surface of the image carrier at a position on the downstream side in the moving direction of the image carrier. is there.

In this type of image forming apparatus, after the cleaning member removes the residual toner on the image carrier and separates from the surface of the image carrier, the toner that cannot be completely removed by the cleaning member is removed. In some cases, the toner particles become so-called toner streaks and remain on the surface of the image carrier.
Further, as a charge removing means for removing the residual charge on the surface of the image carrier after removing the residual toner, a charge removing bias is applied by contacting a surface of the image carrier with a charge removing brush or a bias roller. There is a charge removing member for removing charges. When such a contact type static elimination member is used, the static elimination member may come into contact with the above-mentioned streak-like toner, and the toner may be diffused into the image forming area of the image carrier. As described above, when the streak-like toner remaining on the image carrier is diffused into the image forming area of the image carrier, the image quality of the toner image formed in the image forming area deteriorates. Therefore, in the image forming apparatus of the present invention, the discharging member contacting / separating means causes the discharging member to move at a position upstream of the cleaning member release position on the surface of the image carrier in the image carrier moving direction. The charge removing member is brought into contact with the surface of the image carrier, and is separated from the surface of the image carrier at a position on the downstream side in the moving direction of the image carrier. Accordingly, the charge eliminating member does not contact the streaky toner remaining on the surface of the image carrier, and the toner is not diffused to the image forming area of the image carrier by the charge eliminating member. .

The invention according to claim 6 is based on claims 1, 2,
In the image forming apparatus according to any one of 3, 4 and 5, after the toner image is primarily transferred from a latent image bearing member on which the toner image is formed by a primary transfer unit, the toner image is transferred to the latent image bearing member. An intermediate transfer belt comprising a multi-layered endless belt having a high resistance layer, which is secondarily transferred to the transfer material by a next transfer unit.

When a multi-layered endless belt having a high-resistance layer is used as the image carrier, when the toner image is continuously and primary-transferred onto the image carrier, the residual electric charge remains on the high-resistance layer. Is easily accumulated. For this reason, in an image forming apparatus using an intermediate transfer belt including such an endless belt, scattered toner scattered from the cleaning unit adheres to the endless belt due to residual charges remaining on the intermediate transfer belt. Easier to do. The image forming apparatus of the present invention is configured such that the scattering toner is prevented from adhering to the image forming area of the intermediate transfer belt including the endless belt. Therefore, even if the scattered toner easily adheres to the intermediate transfer belt due to the residual charge, the scattered toner is less likely to degrade the image quality of the toner image formed in the image forming area of the intermediate transfer belt.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic color copying machine (hereinafter, referred to as a color copying machine) as an image forming apparatus will be described. First, the schematic configuration and operation of the color copying machine according to the present embodiment will be described with reference to FIG. This color copier includes a color image reading device (hereinafter, referred to as a color scanner) 1,
Color image recording device (hereinafter referred to as color printer)
2, a paper feed bank 3 and the like.

The color scanner 1 converts the image of the document 4 on the contact glass 121 into an illumination lamp 122, mirror groups 123a, 123b, 123c, and a lens 124.
And form an image on the color sensor 125 via. Then, the color image information of the document 4 is stored in, for example, Red, Green.
The image data is read for each of n, Blue (hereinafter, R, G, B) color separation lights and converted into an electric image signal. The color sensor 125 of this example is composed of R, G, and B color separation means and a photoelectric conversion element such as a CCD, and photoelectrically converts a three-color image of the document 4 separated by the color separation means. Reading by the element at the same time. Then, based on the intensity levels of the R, G, B color separation image signals obtained by the color scanner 1, a color conversion process is performed by an image processing unit (not shown), and Black (hereinafter, referred to as Bk), Cyan
(Hereinafter, referred to as C), Magenta (hereinafter, referred to as M), and Yellow (hereinafter, referred to as Y) color image data are obtained.

The operation of the color scanner 1 for obtaining the color image data of Bk, C, M and Y is as follows. Upon receiving a scanner start signal that is timed with the operation of the color printer 2 described later, an optical system including an illumination lamp 122 and mirror groups 123a, 123b, 123c scans the document 4 in the left direction of the arrow, and performs once. To obtain four color image data. This is stored in a memory (not shown) and pulled out, thereby sequentially obtaining four color image data. Then, each time the color printer 2 sequentially visualizes and superimposes the images to form a final four-color full-color image.

The color printer 2 includes a photosensitive drum 200 as an image carrier, a writing optical unit 220,
Revolver developing unit 230, intermediate transfer unit 50
0, a secondary transfer device 600, a fixing device 270, and the like. The photosensitive drum 200 rotates in the counterclockwise direction indicated by the arrow, and the photosensitive drum cleaning device 20
1. Static elimination lamp 202, charger 203, potential sensor 20
4, the selected developing device of the revolver developing unit 230,
Development density pattern detector 205, intermediate transfer unit 50
0, a secondary transfer device 600 and the like are arranged.

The writing optical unit 220
Converts the color image data from the color scanner 1 into an optical signal, performs optical writing corresponding to the image of the document 4, and forms an electrostatic latent image on the photosensitive drum 200. The writing optical unit 220 includes a semiconductor laser 221 as a light source, a laser emission drive control unit (not shown), a polygon mirror 222 and a rotation motor 223, an f / θ lens 224, a reflection mirror 225, and the like.

The revolver developing unit 230
Is composed of a Bk developing unit 231K, a C developing unit 231C, an M developing unit 231M, a Y developing unit 231Y, and a revolver rotation drive unit which rotates each developing unit in a counterclockwise direction indicated by an arrow. A developing bias in which an AC voltage Vac is superimposed on a negative DC voltage Vdc is applied to each developing sleeve by a developing bias power supply (not shown), and the developing sleeve is set at a predetermined potential with respect to the metal base layer of the photosensitive drum 200. Biased.

When the copier main body is in a standby state, the revolver developing unit 230 moves the Bk developing device 231K to the developing position 30K.
When the copy operation is started, reading of the Bk color image data is started from the color scanner 1 at a predetermined timing. Image formation starts (hereinafter, an electrostatic latent image based on Bk image data is converted to Bk image data).
It is called a latent image. The same applies to C, M, and Y). Before the front end of the electrostatic latent image reaches the Bk developing position, the Bk developing unit 231K is moved to the developing position and the rotation of the Bk developing sleeve is started before the front end of the electrostatic latent image reaches the Bk developing position so that development can be performed from the front end of the Bk electrostatic latent image. And B
The k electrostatic latent image is developed with Bk toner. And after that Bk
The developing operation of the electrostatic latent image area is continued, but when the trailing end of the electrostatic latent image passes the Bk developing position, the revolver developing unit 230 is immediately moved until the developing device for the next color comes to the developing position.
Rotates. This is completed at least before the leading end of the electrostatic latent image based on the next image data arrives.

As shown in FIG. 2, the intermediate transfer unit 500 includes an intermediate transfer belt 501 which is an intermediate transfer member stretched over a plurality of rollers. Around the intermediate transfer belt 501, a secondary transfer bias roller 605, which is a secondary transfer charge applying unit of the secondary transfer device 600,
A belt cleaning blade 504 serving as an intermediate transfer body cleaning unit, a lubricant applying brush 505 serving as a lubricant applying member of a lubricant applying unit, and the like are disposed so as to face each other.

A position detecting mark is provided on the outer peripheral surface or the inner peripheral surface of the intermediate transfer belt 501. However, on the outer peripheral surface side of the intermediate transfer belt 501, it is necessary to devise a method of providing a position detection mark so as to avoid the pass area of the belt cleaning blade 504, and it may be difficult to arrange the mark. A position detection mark is provided on the inner peripheral surface side of the intermediate transfer belt 501. An optical sensor 514 as a mark detecting sensor is provided with an intermediate transfer belt 501.
Are provided between the primary transfer bias roller 507 and the drive roller 508, which are bridged.

The intermediate transfer belt 501 includes a primary transfer bias applying roller 507, a belt driving roller 508, a belt tension roller 509, and a primary transfer charge applying means.
Secondary transfer opposed roller 510, cleaning opposed roller 5
11 and a feedback current detection roller 512. Each roller is formed of a conductive material, and each roller other than the primary transfer bias roller 507 is grounded. A transfer bias controlled to a predetermined magnitude of current or voltage in accordance with the number of superimposed toner images is applied to the primary transfer bias roller 507 by a primary transfer power supply 801 controlled by a constant current or a constant voltage. ing.

The intermediate transfer belt 501 is driven in the direction of the arrow by a belt drive roller 508 that is rotated in the direction of the arrow by a drive motor (not shown). The intermediate transfer belt 501 is made of a semiconductor or an insulator and has a single-layer or multilayer structure. Further, the intermediate transfer belt is set to be larger than the maximum paper-passable size in order to overlap the toner images formed on the photosensitive drum 200.

A secondary transfer bias roller 605 serving as a secondary transfer means can be brought into contact with and separated from the surface of the intermediate transfer belt 501 at a portion stretched around the secondary transfer opposing roller 510. The secondary transfer bias roller 605 is a portion of the intermediate transfer belt 5 stretched over the secondary transfer opposing roller 510.
The recording paper P is interposed between the secondary transfer power supply 01 and a transfer bias of a predetermined current is applied by a secondary transfer power supply 802 controlled at a constant current.

The registration roller 610 feeds the transfer paper P as a transfer material at a predetermined timing between the secondary transfer bias roller 605 and the intermediate transfer belt 501 stretched over the secondary transfer opposing roller 510. A cleaning blade 608, which is a cleaning unit, is in contact with the secondary transfer bias roller 605. The cleaning blade 608 is for removing the adhered matter attached to the surface of the secondary transfer bias roller 605 for cleaning.

In a color copying machine having such a configuration,
When the image forming cycle is started, the photosensitive drum 200
Is rotated in a counterclockwise direction indicated by an arrow by a drive motor (not shown), and Bk toner image formation, C toner image formation, M toner image formation, and Y toner image formation are performed on the photosensitive drum 200. The intermediate transfer belt 501 is rotated clockwise by an arrow by a belt driving roller 508.
The Bk toner image, the C toner image, the M toner image, and the Y toner are transferred by a transfer bias caused by a voltage applied to the primary transfer bias roller 507 with the rotation of the intermediate transfer belt 501.
The primary transfer of the toner image is performed, and finally Bk, C, M,
The toner images are formed on the intermediate transfer belt 501 in the order of Y so as to overlap each other.

For example, the formation of the Bk toner image is performed as follows. In FIG. 2, the charging charger 203 includes:
The surface of the photosensitive drum 200 is uniformly charged to a predetermined potential with a negative charge by corona discharge. The timing is determined based on the belt mark detection signal, and a writing optical unit (not shown) performs raster exposure using laser light based on the Bk color image signal. When this raster image is exposed, in the exposed portion of the surface of the photosensitive drum 200 that is initially uniformly charged, the charge proportional to the amount of exposure light disappears, and a Bk electrostatic latent image is formed. In this Bk electrostatic latent image,
The negatively charged Bk on the developing roller of the Bk developing device 231K
Due to the contact of the toner, the toner does not adhere to the portion of the photosensitive drum 200 where the charge remains, and the toner is attracted to the portion having no charge, that is, the exposed portion, and Bk similar to the electrostatic latent image is obtained. A toner image is formed.

The Bk toner image formed on the photosensitive drum 200 in this manner is primarily transferred onto the surface of the intermediate transfer belt 501 which is rotating at a constant speed while being in contact with the photosensitive drum 200. The photosensitive drum 20 after this primary transfer
A small amount of untransferred residual toner remaining on the surface of
The photoconductor drum 200 is cleaned by the photoconductor cleaning device 201 in preparation for reuse. This photosensitive drum 200
On the side, the process proceeds to the Y image forming process after the Bk image forming process, and the reading of the Y image data by the color scanner starts at a predetermined timing.
An electrostatic latent image is formed.

Then, after the trailing end of the previous Bk electrostatic latent image has passed and before the leading end of the T electrostatic latent image has reached, the rotating operation of the revolver developing unit 230 is performed, and the Y developing device is rotated. 231Y is set at the development position, and the Y electrostatic latent image is developed with the Y toner. Thereafter, the development of the Y electrostatic latent image area is continued, but when the rear end of the Y electrostatic latent image passes, the revolver developing unit rotates as in the case of the Bk developing machine 231K, and the next operation is performed. Is moved to the developing position. This is also completed before the leading end of the next C electrostatic latent image reaches the developing position. In the image forming processes of C and M, the operations of reading the color image data, forming the electrostatic latent image, and developing are the same as those in the processes of Bk and Y described above, and thus the description is omitted.

The Bk, Y, C, and M toner images sequentially formed on the photosensitive drum 200 in this manner are sequentially aligned on the same surface of the intermediate transfer belt 501 and are primarily transferred. As a result, a toner image in which a maximum of four colors are superimposed on the intermediate transfer belt 501 is formed. on the other hand,
At the time when the image forming operation is started, the transfer paper P is fed from a paper feed unit such as a transfer paper cassette or a manual feed tray, and stands by at the nip of the registration roller 610.

The front end of the toner image on the intermediate transfer belt 501 is applied to a secondary transfer portion where a nip is formed by the intermediate transfer belt 501 stretched around the secondary transfer opposing roller 510 and the secondary transfer bias roller 605. When the transfer paper P is moved, the registration roller 610 is driven so that the leading end of the transfer paper P coincides with the leading end of the toner image.
And the toner image are registered.

As described above, when the transfer paper P passes through the secondary transfer section, four colors on the intermediate transfer belt 501 are generated by the transfer bias by the voltage applied to the secondary transfer bias roller 605 by the secondary transfer power supply 802. The superimposed toner image is collectively transferred (secondarily transferred) onto the transfer paper P. The transfer paper P is neutralized by passing through a portion facing a transfer paper neutralization charger 606 disposed on the downstream side of the secondary transfer unit.
0 (see FIG. 1). Then, the transfer paper P is melted and fixed at the nip portion between the fixing rollers 271 and 272 of the fixing device 270,
The paper is sent out of the apparatus main body 2 and is stacked face up on a copy tray (not shown).

On the other hand, the photosensitive drum 2 after the belt transfer
The surface of the cleaning member 201 is cleaned by the photoconductor cleaning device 201, and is uniformly discharged by the discharging lamp 202. Further, the residual toner remaining on the surface of the intermediate transfer belt 501 after the secondary transfer of the toner image onto the transfer paper P is cleaned by the belt cleaning blade 504. The belt cleaning blade 504 is brought into and out of contact with the surface of the intermediate transfer belt 501 at a predetermined timing by a cleaning member separation / contact mechanism (not shown). An upstream side of the belt cleaning blade 504 in the moving direction of the intermediate transfer belt 501 is provided with a toner seal member 5 that comes into contact with or separates from the surface of the intermediate transfer belt 501.
03 is provided. This toner seal member 503
Receives the dropped toner dropped from the belt cleaning blade 504 during the cleaning of the residual toner, and prevents the dropped toner from scattering on the transfer path of the transfer paper P. This toner seal member 503
Is brought into and out of contact with the surface of the intermediate transfer belt 501 together with the belt cleaning blade 504 by the cleaning member separation / contact mechanism.

The lubricant 506 shaved off by the lubricant application brush 505 is applied to the surface of the intermediate transfer belt 501 from which the residual toner has been removed.
The lubricant 506 is made of, for example, a solid such as zinc stearate, and is provided so as to be in contact with the lubricant applying brush 505. Also, the intermediate transfer belt 501
Remaining on the surface of the intermediate transfer belt 501
The toner is removed by the charge removing bias applied by the belt charge removing brush 502 in contact with the surface of the sheet. Here, the lubricant applying brush 505 and the belt neutralizing brush 502
Are brought into contact with and separated from the surface of the intermediate transfer belt 501 at a predetermined timing by respective contact / separation mechanisms (not shown).

Here, at the time of the repeat copy, the operation of the color scanner and the image formation on the photosensitive drum 200 are as follows.
After the fourth sheet (M) image forming step of the first sheet, the process proceeds to the second sheet first color (Bk) image forming step at a predetermined timing. Further, after the batch transfer process of the first four-color superimposed toner image onto the transfer paper, the second Bk toner image is formed on the surface of the intermediate transfer belt 501 by the belt cleaning blade 504. The primary transfer is performed. Thereafter, the operation is the same as that of the first sheet.
The above is the copy mode for obtaining a four-color full-color copy. However, in the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. In the case of the single color copy mode,
Until the predetermined number of sheets is completed, the revolver developing unit 2
The copying operation is performed with only the 30 color developing machines in the developing operation state and the belt cleaning blade 504 kept in contact with the intermediate transfer belt 501.

The above is the copy mode for obtaining a four-color full-color copy. However, in the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. Become. In the case of the single color copy mode, only the developing device of the predetermined color of the revolver developing unit 230 is in the developing operation state until the predetermined number of copies are completed, and the belt cleaning blade 504 is brought into contact with the intermediate transfer belt 501. The copy operation is performed in the state in which the copy operation is performed.

As described above, in a copying machine having a configuration in which the residual toner is removed by using the belt cleaning blade 504 that comes in contact with and separates from the intermediate transfer belt 501 as an image carrier, the intermediate transfer belt 501 In the process of removing the residual toner, the belt cleaning blade 50 is used.
In some cases, the toner adhered to the sheet No. 4 may be scattered when the belt cleaning blade 504 separates from the intermediate transfer belt 501. Then, the scattered toner scattered from the belt cleaning blade 504 forms the next toner image on the leading end of the next image forming area of the intermediate transfer belt 501 from which the residual toner has been removed by the belt cleaning blade 504, that is, the intermediate transfer belt 501. In some cases, the toner adheres to the leading end of the next primary transfer area where the primary transfer is performed, and the image quality of the next toner image formed in the next image forming area deteriorates.

The adhesion of the toner scattered from the belt cleaning blade 504 to the leading end of the next image forming area of the intermediate transfer belt 501 is caused by the intermediate transfer belt 50 of the belt cleaning blade 504.
This occurs because the leading end of the next image forming area of the intermediate transfer belt 501 enters the toner scattered area of the scattered toner scattered at the time of separation from 1. Accordingly, the presence or absence of the toner scattered from the belt cleaning blade 504 on the leading end of the next image forming area of the intermediate transfer belt 501 causes the belt cleaning blade 504 to be separated from the intermediate transfer belt 501. It is considered that the release position of the belt cleaning blade 504 is closely related.

Therefore, the present inventors set the position where the cleaning blade 504 is released from the intermediate transfer belt 501 with respect to the image forming area on the surface of the intermediate transfer belt 501, and the next image formation of the intermediate transfer belt 501. The belt cleaning blade 504 to the tip of the area
The following experiment was conducted in order to investigate the relationship with the state of adhesion of the scattered toner scattered from the toner.

In this experiment, the intermediate transfer belt 501 was used.
A copying machine having an A4 / Fc2 chamfering configuration capable of forming two A4 size images on the surface of the image forming apparatus was used. FIG.
Next, each image forming area of the intermediate transfer belt 501 in the current copying machine in which no measures are taken to prevent the scattering toner from adhering to the leading end of the next image forming area of the intermediate transfer belt 501, the cleaning blade 504, The positional relationship between the release position and the contact position of the rotating brush 505 with respect to the intermediate transfer belt 501 is shown. In FIG. 3, the rear end position and the front end position of the image are described as being synonymous with the front end position and the rear end position of the transfer paper P.

In the copying machine used in this experiment,
As shown in FIG. 3, the distance from the rear end position of the image before being formed on the intermediate transfer belt 501 to the front end of the next image is short. That is, the length of the non-image area of the intermediate transfer belt 501 is small. Since the release position and the contact position of the cleaning blade 504 need to be within the non-image area of the intermediate transfer belt 501, the degree of freedom of the release position and the contact position is small. In the case of the letter size, the rear end position of the image is smaller than the rear end position of the A4 size image.
Since the distance is 6 mm closer to the tip of the next image, the degree of freedom is further reduced.

In the copying machine having the A4 / Fc2 chamfering configuration, as shown in FIG. 3, the rear end position of the next image is closer to the front end position of the next image by 27 mm than the rear end position of the previous image. The state is shifted to. Further, in this type of copying machine, the rotating brush 505 serving as the lubricant applying member is provided with a rotating brush 505 as a lubricant applying member so as not to cause a problem such as the blade entangling of the cleaning blade 504 when removing the residual toner. It has been said that it is necessary to contact all the image forming areas of the intermediate transfer belt 501 including the image forming area. Therefore, in the current copying machine used in this experiment, the release mark of the rotating brush 505 and the previous image were cleaned in the next image forming area of the intermediate transfer belt 501 that cleaned the previous image. As shown in FIG. 3, a position 8 mm from the rear end position of the next image, as shown in FIG. 3, in consideration of the margin in the letter size, with the intention of not leaving it in the next image forming area of the intermediate transfer belt 501. Is the release position of the rotating brush 505, and the position 33 mm from the rear end position of the next image is the release position of the cleaning blade 504.

In this experiment, the above-structured 6
The cleaning blade 504 is used from the leading end position of the next image on the intermediate transfer belt 501 using one copying machine.
By changing the distance L (in the current copying machine, L = 41 mm) in the moving direction of the intermediate transfer belt 501 up to the release position of, image formation was performed on ten transfer papers P for each copying machine. . Then, the degree of adhesion of the scattered toner to the leading end of each of ten transfer papers P of each copying machine was classified into five levels of leading end toner drop rank. Here, rank 5 is a state in which the scattered toner is not attached at all, rank 3 or higher is a state in which the scattered toner is in an allowable range, rank 3 is a state in which the scattered toner is not in an allowable range, and rank 1 is. Indicates the state in which the scattering toner is most remarkably attached.

As a result, from the leading end position of the next image on the intermediate transfer belt 501, the cleaning blade 50
It has been found that there is a relationship as shown in the graph of FIG. 4 between the distance L to the release position of No. 4 and the above-described five-step leading edge toner drop rank. As is clear from this graph, the smaller the distance L from the leading end position of the next image on the intermediate transfer belt 501 to the release position of the cleaning blade 504, the more the distance L to the leading end of the next image on the intermediate transfer belt 501 becomes. The amount of scattered toner is increased (the above-described leading end toner drop rank is lowered). Conversely, as the distance L increases, the amount of scattered toner attached to the leading end of the next image on the intermediate transfer belt 501 decreases (the leading end toner drop rank increases).

For example, in the current copying machine in which the distance L is set to 41 mm, the top toner drop rank is less than rank 3, which is in a state where the adhesion of the scattered toner cannot be tolerated. On the other hand, in a copying machine in which the distance L is set to 45 mm or more, the leading end toner drop rank becomes 3 or more, which is a range in which the adhesion of the scattered toner is allowed.

Therefore, in the color copying machine according to the present embodiment, as shown in FIG. 5, the release position of the cleaning blade 504 has a margin based on the leading end position of the next image on the intermediate transfer belt 501. In consideration of this, the configuration is shifted to the rear end position of the previous image by 20 mm from the current release position. Thereby, the intermediate transfer belt 50
The distance L from the leading edge position of the next image to the release position of the cleaning blade 504 is L = 61 mm, and the leading edge toner drop rank is as shown in FIG.
This is a range in which the adhesion of the scattered toner having a rank of 4 or more is allowable.

The top toner drop ranks obtained by the above-described experiments for the current copying machine and the color copying machine according to the present embodiment are as shown in Tables 1 to 6 below.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

Numerical values in Tables 1 to 6 indicate the total number of transfer papers P of nine sheets that are sorted into each of the above-described five-stage leading edge toner drop ranks. Here, when the image was formed on the first sheet of transfer paper P, since the scattered toner was not generated, it was treated as a non-target.

As is apparent from Tables 1 to 6, in the color copying machine according to the present embodiment, the tip toner drop rank of all nine transfer papers P is equal to or less than 3 for the adhesion of the scattered toner. It is within the acceptable range. As described above, the use of the color copying machine according to the present embodiment makes it difficult for the scattered toner scattered from the cleaning blade 504 to adhere to the next image forming area of the intermediate transfer belt 501. This can prevent the image quality of the next image formed in the next image forming area from being degraded.

Incidentally, when the toner seal member 503 as shown in FIG.
3 may be scattered when the toner seal member 503 is separated from the intermediate transfer belt 501. However, in the color copying machine according to the present embodiment, when the release position of the cleaning blade 504 is shifted, the release position of the toner seal member 503 from the intermediate transfer belt 501 can also be shifted. This makes it difficult for the scattered toner scattered from the toner seal member 503 to reach the leading end of the next image.

The rotating brush 505 for applying the lubricant 506 to the surface of the intermediate transfer belt 501 is
The lubricant applying device is disposed in a cleaning device (not shown) in which the cleaning blade 504 is disposed, and is brought into and out of contact with the intermediate transfer belt 501 by using a contacting / separating mechanism of the cleaning blade 504. It can be simplified. However, with such a configuration, as shown in FIG. 5, by shifting the release position of the cleaning blade 504 toward the rear end position of the previous image, the release position of the rotating brush 505 is changed to the next image. The rear end position is shifted downstream in the belt moving direction. For this reason, in this configuration, a release mark (brush mark) of the rotating brush 505 remains in the image forming area of the next image.

Therefore, in the color copying machine according to the present embodiment, the coating member contacting / separating means for bringing the rotating brush 505 into and out of contact with the intermediate transfer belt 501 is separated from the cleaning member contacting / separating means of the cleaning blade 504. Independent configuration. Then, the rotating brush 505 is moved by the applying member contacting / separating means as shown in FIG.
The non-image area of the intermediate transfer belt 501 can be independently contacted and separated. As a result, the lubricant 506 can be reliably applied to the image forming area of the intermediate transfer belt 501, and it is possible to prevent the cleaning blade 504 from entangling the blade when removing the residual toner. Become like Further, the release mark of the rotating brush 505 can be prevented from being left in the image forming area of the intermediate transfer belt 501.

When the residual charge on the intermediate transfer belt 501 is removed by using a contact-type belt neutralizing brush 502 as shown in FIG. The belt static elimination brush 502 may come into contact with the toner remaining on the intermediate transfer belt 501 like this, and the toner may be diffused to the image forming area of the image carrier. Therefore, in the color copying machine according to the present embodiment, the cleaning blade 504 on the surface of the intermediate transfer belt 501 is used.
The belt neutralizing brush 502 is brought into contact with the surface of the intermediate transfer belt 501 at a position on the upstream side in the belt moving direction from the release position of the belt, and the belt neutralizing brush 502 is placed on the intermediate transfer belt 501 at a position on the downstream side in the belt moving direction. Away from the surface. As a result, the belt neutralizing brush 502 does not contact the streak-like toner remaining on the surface of the intermediate transfer belt 501, and the belt neutralizing brush 502 transfers the toner to the next image forming area of the intermediate transfer belt 501. Will not be spread.

When a multi-layered endless belt having a high resistance layer is used as the intermediate transfer belt 501, a toner image is continuously formed on the intermediate transfer belt 501 by one.
At the time of the next transfer, residual charges are likely to be accumulated in the high resistance layer. Therefore, the scattered toner scattered from the cleaning blade 504 easily adheres to the image forming area of the intermediate transfer belt 501 due to the residual charge remaining on the intermediate transfer belt 501. The color copying machine according to the present embodiment is configured to minimize the adhesion of the scattered toner to the image forming area of the intermediate transfer belt 501, so that the scattered toner is scattered on the intermediate transfer belt 501 by the residual charge. Even if toner becomes easy to adhere,
The scattered toner is less likely to degrade the image quality of the toner image formed in the image forming area of the intermediate transfer belt 501.

In this embodiment, the case where the image carrier is a belt-shaped intermediate transfer member (intermediate transfer belt 501) has been described. However, in the present invention, an image in which the image carrier is a drum-shaped intermediate transfer member is provided. It can also be applied to a forming apparatus. Further, the present embodiment is an example in which the present invention is applied to an image forming apparatus including the intermediate transfer unit 500. For example, a transfer material that does not include the intermediate transfer unit and is transported from the image carrier by a transfer material transport belt. The present invention can be similarly applied to an image forming apparatus having a configuration in which image data is directly transferred to an image forming apparatus. In this case, the transfer material transport belt serves as an image carrier.

In the above embodiment, the photosensitive drum 2
In the present invention, the charging potential of the photosensitive drum 200 is negative, and the charging potential of the photosensitive drum 200 is negative. The present invention is not limited to a certain type, and can be similarly applied to a type using a one-component developer or a type using a regular developing method.

[0064]

According to the first to sixth aspects of the present invention, the scattered toner hardly adheres to the next image forming area of the image carrier, and the image of the next toner image formed in the next image forming area is reduced. There is an excellent effect that deterioration in quality can be prevented.

In particular, according to the second aspect of the invention, it is possible to suppress the deterioration of the image quality of the next toner image formed in the next image forming area due to the scattered toner scattered from the toner seal member. Has an effect.

According to the third to eighth aspects of the present invention, the lubricant can be reliably applied to at least the image forming area on the surface of the image bearing member, and the residual toner is removed. This has an excellent effect that the cleaning member can be prevented from entangling the blade.

According to the fourth aspect of the present invention, even if a rotary brush is used as the lubricant applying member, it is possible to prevent the release mark of the rotary brush from being left in the image forming area of the image carrier. Has an excellent effect.

According to the fifth aspect of the present invention, the charge removing member does not contact the streak-like toner remaining on the surface of the image carrier, and the toner removes the image on the image carrier by the charge removing member. There is an excellent effect that diffusion to the formation region is eliminated.

According to the sixth aspect of the present invention, even if the scattered toner easily adheres to the intermediate transfer belt due to the residual charge, the image of the toner image formed in the image forming area of the intermediate transfer belt by the scattered toner is formed. There is an excellent effect that there is little possibility that the quality is reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of a color copying machine according to an embodiment of the present invention.

FIG. 2 is a front view showing a schematic configuration of a main part of the color copying machine.

FIG. 3 shows each image forming area of the intermediate transfer belt in a current copying machine in which no measures are taken to prevent scattering toner from adhering to the leading end of the next image forming area of the intermediate transfer belt; FIG. 3 is a schematic diagram illustrating a positional relationship between a release position and a contact position with respect to the intermediate transfer belt.

FIG. 4 is a graph showing a relationship between a distance L to a release position of the cleaning blade and five ranks of toner drop at the leading end.

FIG. 5 is a schematic diagram showing a positional relationship between each image forming area of the intermediate transfer belt and a release position and a contact position of the cleaning blade and the rotating brush with respect to the intermediate transfer belt in the color copying machine according to the embodiment of the present invention. .

[Explanation of symbols]

200 Photoconductor drum 203 Charger 220 Writing optical unit 230 Revolver developing unit 500 Intermediate transfer unit 501 Intermediate transfer belt 502 Belt discharging brush 503 Toner seal member 504 Belt cleaning blade 505 Lubricant application brush 506 Lubricant 507 Primary transfer bias roller 508 Belt drive roller 600 Secondary transfer device 605 Secondary transfer bias roller 606 Transfer paper discharging charger L Distance in the belt movement direction from the leading end position of the next image on the intermediate transfer belt to the release position of the cleaning blade P Transfer paper

Continued on the front page (72) Inventor Takeshi Shintani 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H032 BA07 BA23 BA29 BA30 2H034 AA07 BA02 BA05 BD07 BD10 BF01 BF08 BF12 2H035 AA14 AB02 AB06 AC03 AC04 AZ11

Claims (6)

[Claims] An image carrier that moves while carrying a toner image on a surface thereof; transfer means for transferring the toner image carried on the surface of the image carrier onto a transfer material; The image carrier moves while the cleaning member, which is configured to be able to contact and separate, is in contact with the surface, thereby removing residual toner on the image carrier after transferring the toner image to the transfer material. An image forming apparatus provided with a cleaning unit, wherein the cleaning member, which is in contact with the surface of the image carrier to remove residual toner on the image carrier, is separated from the surface of the image carrier. The release position on the carrier is shifted to the rear end position of the image before the residual toner is removed by the cleaning member with reference to the leading end position of the next image forming area formed on the image carrier. Characterized by Image forming device. 2. An image forming apparatus according to claim 1, wherein said cleaning means has a toner seal member which comes into contact with and separates from a surface of the image carrier on the upstream side in the movement direction of the image carrier with respect to the cleaning member. An image forming apparatus comprising: 3. The image forming apparatus according to claim 1, further comprising: a lubricant applying member which comes into contact with and separates from the surface of the image carrier and applies a lubricant to the surface. And a coating member contacting / separating means for bringing the lubricant applying member into and out of contact with the cleaning member contacting / separating means for bringing the cleaning member of the cleaning means into and out of contact with the surface of the image carrier. An image forming apparatus, wherein the lubricant applying member is configured to be brought into contact with and separated from a non-image area on a body surface. 4. The image forming apparatus according to claim 3, wherein the lubricant applying member uses a rotary brush which applies a lubricant which has been scraped off by rotating in contact with a solid lubricant on the surface of the image carrier. Characteristic image forming apparatus. 5. The image forming apparatus according to claim 1, wherein the toner image is transferred to and from the surface of the image carrier after the toner image has been transferred to the transfer material and remains on the surface of the image carrier. A static elimination member for removing the residual charge, and a static elimination member contacting / separating means for bringing the static elimination member into and out of contact with the surface of the image carrier, relative to the release position of the cleaning member on the image carrier surface. Contacting the neutralizing member with the surface of the image carrier at a position on the upstream side in the image carrier moving direction, and separating the neutralizing member from the surface of the image carrier at a position on the downstream side in the image carrier moving direction. An image forming apparatus comprising: 6. The image forming apparatus according to claim 1, wherein said image bearing member transfers said toner image from a latent image bearing member on which said toner image is formed by primary transfer means. An image forming apparatus comprising: an intermediate transfer belt comprising a multi-layered endless belt having a high resistance layer, wherein the toner image is secondarily transferred to the transfer material by a secondary transfer unit after the next transfer. apparatus.