JP2003330289A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve cleaning property of an intermediate transfer body and shortening of jamming recovery time. <P>SOLUTION: When cleaning the intermediate transfer body at jamming recovery, etc., AC bias is applied at a secondary transfer part and cleaning is carried out after weakening the attracting force between the intermediate transfer body and toner by destaticizing toner triboelectricity. <P>COPYRIGHT: (C)2004,JPO

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 using an electrophotographic system, and in particular, a transferable image (toner image) formed on a first image carrier is temporarily transferred to a second image carrier. The primary transfer is performed on the intermediate transfer body, and the transfer material as the third image carrier is pressed against the intermediate transfer body by the contact transfer member and secondarily transferred to the transfer material to obtain image formation (copy / print). The present invention relates to image forming apparatuses such as copiers, printers, and fax machines.

In the above, the first image carrier is, for example, an electrophotographic photoreceptor, an electrostatic recording dielectric material, a magnetic recording magnetic material, or the like.

The process of forming a transferable image on the first image carrier is, for example, an electrophotographic process, an electrostatic recording process, a magnetic recording process or the like.

The intermediate transfer member as the second image carrier is
Examples include roller-shaped bodies (drum-shaped bodies) and belt-shaped bodies.

The transfer material as the third image carrier is transfer paper, recording paper, printing paper, card, envelope, postcard, etc.,
The material is not limited to paper.

[0006]

2. Description of the Related Art Conventionally, an image forming apparatus using an intermediate transfer member is formed on the intermediate transfer member by repeating the formation of a transferable image on a first image carrier and the primary transfer process of the image onto the intermediate transfer member. A device for forming a color image (or a multicolor image) composed of developers of a plurality of colors, and then secondarily transferring the images collectively onto a transfer material to output an image-formed product in which color image information is synthesized and reproduced. Alternatively, it is effective as an image forming apparatus having a color image forming function, and it is possible to obtain an image having no misregistration (color misregistration) of respective component color images.

FIG. 2 is a schematic sectional view of a color image forming apparatus (copier or laser printer) utilizing an electrophotographic process. The intermediate transfer belt 130 having a low resistance is used as an intermediate transfer member, and the secondary transfer roller 11 is used as a secondary contact transfer unit.
Are using.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) which is repeatedly used as a first image bearing member, and has a predetermined peripheral speed (process speed) in a counterclockwise direction indicated by an arrow. Is driven to rotate.

The photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by the primary charging roller 24 in the course of rotation, and then an image exposing means (not shown) (color separation / image forming exposure optical for color original image). System, a first color component image of a target color image by being subjected to image exposure 3 by a scanning exposure system by a laser scanner that outputs a laser beam modulated corresponding to a time series electric digital pixel signal of image information). An electrostatic latent image corresponding to (for example, a yellow component image) is formed.

Then, the electrostatic latent image is transferred to the first developing device 1a.
(Yellow developing device) develops with the first color yellow toner Y. Developing device 1a ・ 1b ・ 1c ・ 1d
Each developing device (yellow, magenta, cyan, black) is rotated in the direction of the arrow in the drawing by a rotation driving device (not shown), and each developing device is arranged so as to face the photosensitive drum 3 in the developing process. There is.

The intermediate transfer member 130 is rotationally driven in the direction of the arrow at the same peripheral speed as the photosensitive drum 3.

The first color yellow toner image formed and carried on the photosensitive drum 3a passes through the nip portion between the photosensitive drum 3 and the intermediate transfer member 130, and is transferred to the intermediate transfer member 1 in the process.
By the electric field and pressure formed by the primary transfer bias applied to 30, the intermediate transfer is performed on the outer peripheral surface of the intermediate transfer body 130. Hereinafter, this process is called primary transfer.

Similarly, a magenta toner image of the second color, a cyan toner image of the third color, and a black toner image of the fourth color are successively superposed and transferred onto the intermediate transfer member 130, and combined in accordance with the target color image. A color toner image is formed.

Reference numeral 11 denotes a secondary transfer roller, which is an intermediate transfer member 13.
Corresponding to 0, bearings are arranged in parallel so as to be in contact with the lower surface portion. A desired secondary transfer bias is applied to the secondary transfer roller 11 by a secondary transfer bias source.

The primary transfer bias for sequentially superposing and transferring the toner images of the first to fourth colors from the photosensitive drum 3 to the intermediate transfer member 130 is applied from the bias power source with the polarity (+) opposite to that of the toner. .

The transfer of the composite color toner image superposedly transferred onto the intermediate transfer member 130 to the transfer material P is carried out from the paper feed cassette 10 through the registration roller 12 and the pre-transfer guide, and then the secondary transfer with the intermediate transfer member 130. The transfer material P is fed to the contact nip with the roller 11 at a predetermined timing, and at the same time, the secondary transfer bias is applied from the bias power source. This 2
The composite color toner image is transferred from the intermediate transfer member 130 to the transfer material P by the next transfer bias. After this step 2
It is called next transcription.

The transfer material P that has received the toner image transfer is introduced into the fixing device 9 and is heated and fixed.

After the image transfer to the transfer material P is completed, the transfer residual toner on the intermediate transfer member 130 is cleaned by contacting the intermediate transfer member web 22.

[0019]

By the way, in the image forming apparatus, the supply of the recording material to the intermediary transfer belt 130 may be defective or the error may occur.
Due to poor conveyance of the recording material by the next transfer roller 11,
A recording material jam (paper jam) may occur.

The cleaning web 22 has insufficient cleaning performance for the intermediate transfer belt 130 on which such a toner image has been left, and the intermediate transfer belt 130 needs an intermediate transfer to clean the intermediate transfer belt 130 cleanly. It is not enough to pass the belt 130 through the cleaning web 22 once, and it is necessary to pass the belt 130 a plurality of times.

Normally, when a jam occurs, the image forming apparatus ends all the operations once, and after the jammed recording material is removed, a return mode is performed so that a new image forming operation can be performed. However, in this return mode, the transfer belt 130 is also cleaned. However, if the transfer of the toner image occurs as described above, it takes time to clean the intermediate transfer belt 130, which may cause a problem that a great amount of time is required for the return mode until the device returns after the jam processing. .

An object of the present invention is to improve the cleaning performance of the cleaning means so that even if a toner image is transferred onto a recording material conveying member due to a jam of the recording material,
An object of the present invention is to provide an image forming apparatus capable of efficiently cleaning the recording material conveying member to which the toner image has been transferred, and shortening the time until the apparatus returns after a jam process or the like.

[0023]

That is, according to the present invention, an image formed on a first image carrier is firstly transferred and formed on a second image carrier, and then secondarily transferred on a transfer material. In an image forming apparatus for obtaining an image, the secondary transfer bias is AC and DC.
And an image forming apparatus characterized by being switchable between image formation and non-image formation.

Therefore, according to the present invention, the secondary transfer bias at the time of normal image formation is set to DC to transfer the toner image from the intermediate transfer member to the transfer material, and the residual toner on the intermediate transfer member is recovered when the paper jam is recovered. The secondary transfer bias for cleaning the intermediate transfer member can be satisfactorily cleaned by sending AC to the cleaner of the intermediate transfer member after removing the polarity of the residual toner as AC.

Since the intermediate transfer member can be satisfactorily cleaned only by the charge eliminating bias in the secondary transfer portion and the cleaner portion, the time required for the return mode can be greatly shortened as compared with the conventional case. I understand.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention. In the image forming apparatus of this embodiment, the cleaning device for the intermediate transfer belt 130 includes the conductive fur brush 20 and the metal roller 21. The present invention is characterized in that the cleaning performance of the intermediate transfer belt 130 by this cleaning device is improved. Other configurations of this embodiment are basically the same as those of the conventional image forming apparatus of FIG. 2. In FIG. 1, the same members as those of FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

The cleaning device for the intermediate transfer belt 130 is installed downstream of the secondary transfer portion of the intermediate transfer belt 130 and above the fixing device 9. This cleaning device
As described above, the fur brush 20 and the metal roller 21 are electrically conductive and are grounded.

The conductive fur brush 20 serves as a cleaning member, is in contact with the surface of the intermediate transfer belt 130, and is in the direction opposite to the moving direction of the intermediate transfer belt 130, that is, in contact with the transfer belt 130. The part is actively rotated in the opposite direction. In this embodiment, the rotation speed of the fur brush 20 is 1600 rpm. The metal roller 21 serves as a facing member of the fur brush 20, and is in contact with the surface (back surface) on the opposite side of the intermediate transfer belt 130 at the position where the fur brush 20 is installed. Is driven to rotate in the same direction.

During image formation, the first to fourth image forming portions Pa to
After the secondary transfer onto the recording material, the transport belt 130 that transports the toner image through the primary transfer portion of Pd has the toner and other foreign matter remaining on the surface by the conductive fur brush 20 that rotates in the opposite direction. Is scraped off and cleaned thoroughly so that the surface is free of toner and other foreign matter. At the same time, the electrostatic charge remaining on the intermediate transfer belt 130 escapes to the ground of the main body of the apparatus through the conductive fur brush 20 and the metal roller 21, and the intermediate transfer belt 130 is discharged.

A recording material jam (paper jam) may occur and a toner image may remain on the intermediate transfer belt 130.

When a jam occurs, the image forming apparatus finishes all the operations once, removes the jammed recording material, and then executes a return mode so that it can respond to a new image forming operation. Mode intermediate transfer belt 1
Cleaning of 30 is also performed. Therefore, if it takes time to clean the intermediate transfer belt 130 due to the toner image remaining on the intermediate transfer belt 130, the time until the device returns after the jam processing, that is, the return mode time becomes long.

Therefore, in the present invention, in the return mode, the secondary transfer roller 11 which is normally separated is brought into contact with the intermediate transfer belt 130 while the AC bias is applied to clean the intermediate transfer belt 130. According to this, since the secondary transfer roller 11 removes the charge of the toner electrostatically adsorbed on the intermediate transfer belt 130 to reduce the charge amount, the fur brush 20 scrapes off the toner, and thus the intermediate transfer belt 130. The toner can be easily removed from the top of the intermediate transfer belt 130, and the intermediate transfer belt 130 can be cleanly cleaned without toner in a short time.

In this embodiment, cleaning was carried out on the intermediate transfer belt 130 in which four color toner images of maximum density are left and the worst toner stain occurs.

When the image forming apparatus is temporarily stopped by jam of the recording material, the jammed recording material is removed, and the recovery mode is entered, first, the conductive fur brush 20 is started to rotate at 1600 rpm, and the secondary transfer roller 11 is started. To the intermediate transfer belt 130 by static elimination AC bias of 1 kVpp, 500 Hz
The application of the AC high voltage is started. After that, the intermediate transfer belt 130 is driven and rotated at a process speed of 135 mm / sec, and the intermediate transfer belt 130 is rotated by the secondary transfer roller 1.
Therefore, the fur brush 20 is used for cleaning while removing the charge. Then, until the entire intermediate transfer belt 130 passes through the fur brush 20 three times in the state of being discharged,
That is, while rotating the intermediate transfer belt 130 by three rounds and the distance from the secondary transfer roller 11 to the fur brush 20, the secondary transfer roller 11 continues to remove electricity and the fur brush 20 to continue cleaning. The operation of the secondary transfer roller 20 and the secondary transfer roller 11 was stopped, and the cleaning was completed.

As a result, according to this embodiment, the intermediate transfer belt 130 could be completely cleaned without toner after passing through the fur brush 20 three times.

For comparison, cleaning was carried out under the same conditions as described above, except that the secondary transfer roller 11 was not used to eliminate static electricity. As a result, it took six passes of the fur brush 20 to completely clean the intermediate transfer belt 130, which has the same toner stains as described above, so that there is no toner.

Therefore, according to the present embodiment, it can be seen that the time required for the return mode can be reduced by almost half compared with the conventional case.

(Embodiment 2) In this embodiment, the transfer belt is cleaned in the return mode under the following conditions.

Conductive fur brush 20 at 1600 rpm
Then, the secondary transfer roller 11 started to apply to the intermediate transfer belt 130 an AC high voltage of 500 Hz (frequency is the same as in Example 1) of 2 kVpp larger than 1 kVpp in Example 1. These fur brushes 20
From the operation of the secondary transfer roller 11, the intermediate transfer belt 130 is driven and rotated at a process speed of 135 mm / sec, and the secondary transfer roller 11 is neutralized while passing through the fur brush 20 twice (intermediate transfer The belt 130 is rotated by two rotations of the belt 130 and the distance from the secondary transfer roller 11 to the fur brush 20 to perform cleaning, and then the fur brush 20 and the secondary transfer roller 1 are rotated.
The operation of 1 was stopped, and the cleaning was completed.

As a result, the intermediate transfer belt 130 in which the toner image of the maximum density has been transferred for four colors and the worst toner stain has occurred is completely cleaned so that there is no toner between the two passes of the fur brush 20. did it.

On the other hand, when the cleaning is performed under the same conditions as above except that the secondary transfer roller 11 does not perform the charge removal, the intermediate transfer belt 130 having the same toner stain passes through the fur brush 20 six times. For the first time, I was able to completely clean it without toner.

Therefore, the time required for the return mode in this embodiment is shortened to 1/3 that of the conventional case.

(Embodiment 3) In this embodiment, the conductive fur brush 20 is started to rotate at 1600 rpm, and the secondary transfer roller 11 applies the same high voltage of 2 kVpp and 500 Hz to the intermediate transfer belt 130 as in Embodiment 2. The application was started. After that, the fur brush 20 and the secondary transfer roller 1
1, the transfer belt 130 is operated at the process speed 13
It is driven and rotated at a speed of 67.5 mm / sec, which is half of 5 mm / sec, and the intermediate transfer belt 130 is neutralized by the secondary transfer roller 11 while passing through the fur brush 20 once (for one rotation of the intermediate transfer belt 130). The secondary transfer roller 11 and the fur brush 20 are rotated by an amount corresponding to the added distance) to perform cleaning, and then the fur brush 20 and the secondary transfer roller 1
The operation of 1 was stopped, and the cleaning was completed.

As a result, the intermediate transfer belt 130 in which the toner image of the maximum density has been transferred for four colors and which has the worst toner stain is completely cleaned so that there is no toner in one pass of the fur brush 20. did it.

On the other hand, when cleaning is performed under the same conditions as above except that the secondary transfer roller 11 is not used to eliminate the charge, the fur brush 20 passes through the intermediate transfer belt 130 having the same toner stain six times. For the first time, I was able to completely clean it without toner.

Therefore, also in this embodiment, the time required for the return mode can be shortened to 1/3 of the conventional time. Further, in the present embodiment, since the rotation of the intermediate transfer belt 130 is reduced to about one rotation, there is less chance of contact with the members such as the photosensitive drums photosensitive drums 3a to 3d that come into contact with the surface side of the intermediate transfer belt 130. As a result, it was possible to prevent the toner on the surface of the intermediate transfer belt 130 from transferring to the contact members during cleaning.

In each of the above embodiments, the cleaning in the return mode after the jam of the recording material is shown, but the present invention is not limited to this, and after the recording material is discharged in the normal image forming mode or the paper is ejected. The present invention can also be applied to cleaning of an intermediate transfer belt that does not require high cleaning performance such as during a jam, and similarly, when the cleaning is performed by the conductive fur brush 20, a reduction of the toner charge amount by the secondary transfer roller 11 is added. Thereby, the intermediate transfer belt 130 can be efficiently cleaned.

Although one of the cleaning devices is a conductive fur brush, a conductive web or the like may be used.

[0049]

As described above, according to the present invention,
In an image forming apparatus in which an image formed on a first image carrier is primarily transferred and formed on a second image carrier and is secondarily transferred to a transfer material to obtain an image, a secondary transfer bias is AC. The image forming apparatus is characterized in that it can be switched between image formation and non-image formation.

Therefore, according to the present invention, the secondary transfer bias at the time of normal image formation is set to DC to transfer the toner image from the intermediate transfer member to the transfer material, and the residual toner on the intermediate transfer member is returned when the paper jam is recovered. The secondary transfer bias for cleaning the intermediate transfer member can be satisfactorily cleaned by sending AC to the cleaner of the intermediate transfer member after removing the polarity of the residual toner as AC.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram of a conventional image forming apparatus.

[Explanation of symbols]

1: Developing device 2: charging roller 3: Photosensitive drum 4: Photosensitive drum cleaner 9: Fixing device 11: Secondary transfer roller 22: Intermediate transfer member cleaner 24: Primary transfer roller 130: Intermediate transfer belt

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DC14 EA03 EA09 ED24 EE01                       EF09 EK04                 2H200 FA08 GA12 GA23 GB12 GB22                       GB25 HA02 HB12 HB48 JA02                       JA28 JA29 JC03 JC07 JC11                       JC12 LA24 LB02 LB03 LB09                       LB12 NA02 NA03 NA09 NA10                       PA01 PA02 PA10 PA20 PA28                       PB26                 2H300 EA18 EB04 EB07 EB12 EC02                       EC05 EF08 EF14 EF15 EF17                       EG02 EJ09 EL04 FF05 GG02                       GG44 PP02 PP03 PP07 PP10                       QQ01 QQ02 QQ10 RR26 TT04

Claims (5)

[Claims] 1. An image forming apparatus for obtaining an image by primary transfer of an image formed on a first image carrier to a second image carrier to form the image and secondary transfer to a transfer material to obtain an image. An image forming apparatus characterized in that the next transfer bias is composed of AC and DC and can be switched between image formation and non-image formation. 2. The image forming apparatus according to claim 1, wherein the secondary transfer bias is DC during normal image formation and AC during non-image formation. 3. The image forming apparatus according to claim 2, wherein the secondary transfer bias is set to AC when the transfer material jam recovery operation is performed. 4. The image forming apparatus according to claim 1, wherein the second image carrier is provided with a cleaning unit. 5. An image formed on a first image carrier is first transferred onto a second image carrier by first primary transfer of a plurality of colors from the first color, and then secondarily transferred onto a transfer material all at once. The color image forming apparatus according to any one of claims 1 to 4, which obtains a color image.