JPH1010939A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the high cleanability at all times by removing the toner, the paper powder or the like on a pointed end of a cleaning blade, by using an image carrier which can be rotated in the both directions, and reversing the image carrier after the rotation of the image carrier has been finished after the image formation. SOLUTION: An intermediate transfer belt 10 as an image carrier, is reversed by a prescribed amount (b direction), after the rotation (a direction) of the intermediate transfer belt has been finished after the image formation. An image forming brush 13 such as the primary transfer brush is separated from the image carrier when the image carrier is reversed after the image formation. That is, a cam 100 for contact and separation, is rotated to a prescribed position, for separating the pointed end of the primary transfer brush 13 from the intermediate transfer belt 10 at the reversing. Thereby the pointed end of the primary transfer brush can be prevented from untidied. Further the untidiness of the pointed end of the image forming brush caused by the reversing of the image carrier, can be prevented by adjusting the reversing amount of the image carrier to be less than 1/2 of the projecting amount of the image forming brush, for the desired image formation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile, and a printer.
In particular, the present invention relates to an image forming apparatus that cleans an image carrier using a cleaning blade.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus,
As is well known, a toner image formed on an image carrier (photoreceptor) is transferred to a transfer paper or an intermediate transfer body, and then a residual toner or paper dust on the image carrier is removed by a cleaning device. Then, the image carrier is configured to be cleaned. This type of image-bearing carrier cleaning device includes a blade that scrapes off residual toner and paper dust on the image-bearing body by using a tip of a cleaning blade that is in contact with the surface of the image-bearing body. 2. Description of the Related Art A cleaning device of the type is known.

In an image forming apparatus in which the image carrier is cleaned by a cleaning blade, residual toner and paper dust scraped off from the image carrier are deposited on the tip of the cleaning blade due to long-term use. In some cases, the toner adheres and accumulates, lowering the cleaning performance of the cleaning blade and causing poor cleaning.

Conventionally, in order to prevent the cleaning performance of the cleaning blade from deteriorating, a blade cleaning member is pressed against the vicinity of the front edge of the cleaning blade, and adheres to the front edge as the cleaning blade moves away. "Cleaning device" (Japanese Patent Publication No. 1-28943), which is arranged in such a manner as to scrape off the powder, and "Recording device", in which a cleaning blade is intermittently contacted with an image carrier (Japanese Patent Application Laid-Open No. 61-132981).
Japanese Patent Application Laid-Open No. 62-49178), and an "electrophotographic apparatus" in which a cleaning blade is caused to collide with a recording medium (image carrier) during non-cleaning.

[0005]

By the way, in the above-mentioned conventional image forming apparatus, the image forming apparatus adheres to the tip of the cleaning blade.
In order to remove accumulated toner powder and the like, a blade cleaning member is provided in contact with the tip of the cleaning blade, and the cleaning blade is disposed so as to be capable of moving toward and away from the image carrier. With the relative movement between the blade cleaning member and the cleaning blade, the blade cleaning member is configured to rub the tip of the cleaning blade for cleaning. However, in the image forming apparatus having such a configuration, it is necessary to secure a space for disposing the support means of the blade cleaning member, and thus there is a problem that the cleaning apparatus is complicated and large. Further, in recent image forming apparatuses, it has become difficult to arrange the above-described blade cleaning member in the cleaning apparatus with the downsizing of the apparatus main body.

[0006]

According to the present invention, after the rotation of the image carrier having completed the image formation, the image carrier is reversed. In this way, by reversing the image carrier after the completion of the image forming rotation, stagnation of toner or paper dust at the tip of the cleaning blade, which causes adhesion of toner or paper dust to the cleaning blade, that is, The rotation of the image carrier does not stop while the toner or paper dust adheres and accumulates at the tip of the cleaning blade, and the cleaning performance of the cleaning blade is maintained in the substantially initial state.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an image forming apparatus according to the present invention, the image carrier is configured to be rotatable forward and backward, and after the rotation of the image carrier at the end of image formation, the image carrier is reversed. Let it.

Further, in an image forming apparatus provided with an image forming brush in contact with the image carrier, the image carrier is rotated after the rotation of the image carrier at the end of image formation as described above. If the image carrier is reversed, the tip of the image forming brush is dislodged due to the reversal of the image carrier, which adversely affects the image forming performance. Therefore, in this image forming apparatus, the image forming brush is configured to be separated from the image carrier when the image carrier is reversed at the end of image formation.

Further, in an image forming apparatus provided with an image forming brush which comes into contact with the image carrier as described above, and in which the image carrier is reversed at the end of image formation,
It is preferable that the amount of reversal of the image carrier be 1 to 5 mm in order to prevent the tip of the image forming brush from being loosened due to the reversal of the image carrier and to perform good image formation.

Further, in an image forming apparatus provided with an image forming brush which comes into contact with the image carrier as described above, and in which the image carrier is reversed at the end of image formation,
By making the amount of reversal of the image carrier less than or equal to 1/2 of the amount of protrusion of the image forming brush, it is possible to prevent the tip of the image forming brush from being dislodged due to the reversal of the image carrier and to obtain a good image. It is preferable in performing.

The image carrier is an intermediate transfer member to which a toner image formed on a photoconductor is transferred, and the image forming brush converts the toner image formed on the photoconductor into the intermediate transfer member. A primary transfer brush for transferring to a transfer member,
This is effective in preventing the tip of the primary transfer brush from being loosened due to the reverse rotation of the image carrier, and always maintaining good transferability of the intermediate transfer member.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of a multicolor image forming apparatus embodying the present invention. In FIG. 1, a photoreceptor 1, which is a belt-shaped image carrier, is provided between rotating rollers 2 and 3, and is rotated clockwise by driving the rotating roller 3. A charging device 4, a discharging lamp L, and a cleaning blade 15A for the photoconductor are arranged on the outer peripheral portion of the photoconductor 1. Further, at a downstream position of the charging device 4, there is an optical writing unit to which a laser beam 5 </ b> D emitted from the laser writing unit 5 is applied. At a position downstream of the optical writing unit, a multicolor developing device 6 in which a plurality of developing units are supported in a switchable manner is arranged. The multicolor developing device 6 of the present embodiment includes a yellow developing unit Y, a magenta developing unit M, and a cyan developing unit C for each of the colors of the stored toner. Furthermore, on the upper part of the multicolor developing device 6,
A black developing unit 7 containing black toner is arranged.

One of the developing units containing the toner of the corresponding color moves to a developable position in synchronization with the developing timing of the corresponding color. The multicolor developing device 6 in the present embodiment has a function of selecting a developing unit containing the toner of the corresponding color by rotating each developing unit 120 degrees on the circumference. When the developing unit of the multicolor developing device 6 operates, the black developing unit 7 moves to a position separated from the photoconductor 1. The movement of the black developing unit 7 is controlled by the rotation of the cam 45.

The laser writing unit 5 scans light from a laser light source (not shown) by a polygon mirror 5B which is driven to rotate by a motor 5A.
Then, the photoconductor 1 is irradiated via the mirror 5F and the like, and a latent image corresponding to the written information is formed on the photoconductor 1 charged by the charging device 4. The latent image formed on the photoconductor 1 is developed by each of the above-described developing units, and a visible image (toner image) using toner is formed and held on the surface of the photoconductor 1. The photosensitive member 1 has an upper part in contact with the intermediate transfer belt 10.

The intermediate transfer belt 10 includes a rotating roller 11,
12 rotatably supported. A transfer bias is applied to the toner image on the photoreceptor 1 to the back surface of the intermediate transfer belt 10 by an image forming brush (here, a primary transfer brush 13) as a bias unit disposed on the back side of the intermediate transfer belt 10. As a result, the image is transferred onto the surface of the intermediate transfer belt 10.

The photoreceptor 1 is cleaned for each color by a photoreceptor cleaning blade 15a, and a toner image of a predetermined color is formed on the photoreceptor 1 sequentially. The toner images of each color sequentially formed on the photoconductor 1 are transferred to the intermediate transfer belt 10.
The image is transferred to the same position on the intermediate transfer body 10 each time the image is rotated, thereby being superimposed on the intermediate transfer belt 10 to form a color toner image. This intermediate transfer belt 1
The color toner image superimposed on 0 is transferred onto a recording medium such as a transfer sheet or a plastic sheet to form a color copy.

The transfer paper 17A is stored in a paper feeder (paper feed cassette) 17, and is transferred via a paper feed roller 18, a pair of transport rollers 19, and a pair of registration rollers 20 when a color toner image is transferred. The paper is conveyed to the nip between the intermediate transfer belt 10 and the transfer roller 14 at a timing so that the color toner image is located in a predetermined copy area of the paper 17A.

The transfer paper 17A on which the color toner images on the intermediate transfer belt 10 are collectively transferred by the operation of the transfer roller 14 is sent to a fixing device 50, where the transferred color toner images are fixed. Then, the transfer paper 17A on which the color toner image is fixed is formed by a pair of paper discharge rollers 51.
The paper is discharged to the paper discharge stack 52 on the upper part of the main body frame 9.

The intermediate transfer belt 10 includes a rotating roller 11
Is provided with a cleaning device 16 for the intermediate transfer belt, and the cleaning blade 16A can freely contact and separate from the surface (toner image bearing surface) of the intermediate transfer belt 10 via the contact and separation arm 16C. Are located. In the step of transferring the toner image on the photoreceptor 1 to the intermediate transfer belt 10, the cleaning blade 16A separates from the intermediate transfer belt 10 and transfers the toner image carried on the intermediate transfer belt 10 to the transfer paper 17A. After the transfer, the residual toner on the intermediate transfer belt 10 is scraped off by contacting the surface of the intermediate transfer belt 10.

The residual toner scraped off by the cleaning blade 16A is transferred into a collection container 15 as waste toner by an auger 16B provided inside the cleaning device 16 for the intermediate transfer belt and a conveying means (not shown). It is transported and collected. This collection container 15
Is configured to also collect the residual toner on the photoconductor 1 scraped by the cleaning blade 15A for the photoconductor, and the full toner sensor (not shown) provided in the collection container 15 removes the collected waste toner. Replaced when full.

In this embodiment, the photosensitive member 1, the charging device 4, the intermediate transfer belt 10, the cleaning device 16, the transport guide 30 for forming the paper transport path, and the like are integrally incorporated in a unitized process cartridge 31. It is configured so that it can be replaced at the end of its life.

In addition, in this embodiment, the multi-color developing device 6 and the black developing unit 7 are also replaced at the end of their service life. However, in order to facilitate the exchangeability and the processing of jammed transfer paper, etc. A part of the front frame 8 of the apparatus main body is configured to be rotatable and openable about a support shaft 9A provided on the main body frame 9 as a center of rotation.

Further, behind the multicolor developing device 6 of the apparatus main body, an electric device / control device E for controlling the operation of each of the above-mentioned image forming means is accommodated. Further, a fan F for exhausting air is provided above the electric device / control device E to prevent an excessive rise in the temperature inside the device. The transport guide 30
Is provided with another relatively small paper feeder MF.

By the way, in this type of image forming apparatus, as described above, a blade cleaning member abutting on the tip of the cleaning blade is provided in order to remove toner powder and the like adhering and accumulating on the tip of the cleaning blade. ,
With the miniaturization of the apparatus main body, it has become difficult to dispose the above blade cleaning member in the cleaning apparatus.

Therefore, in the image forming apparatus of the present invention, FIG.
As shown in (a), after the rotation of the intermediate transfer belt 10 as the image carrier on which image formation has been completed in the direction of arrow a,
As shown in FIG. 2B, the intermediate transfer belt 10 is
It is reversed by a predetermined amount in the direction of arrow b. By reversing the intermediate transfer belt 10 after the completion of the image forming rotation, the toner and paper dust scraped off by the cleaning blade 16A solidify and adhere to the tip of the cleaning blade 16A while stagnating. Therefore, the cleaning performance of the cleaning blade 16A can be maintained in the substantially initial state.

Here, the forward / reverse rotation of the intermediate transfer belt 10 is performed by rotating the drive motor (not shown) of the rotating roller 11 (or 12) in a forward / reverse controlled rotation by the electric equipment / control device E. Although the image carrier to be controlled is the intermediate transfer belt 10 here, the photosensitive blade 1 is the control object, and the cleaning blade 15A
Of course, the adhesion of the toner powder or the like to the toner may be prevented. FIG. 3 shows a basic control flow of this embodiment.
Shown in

However, an image forming brush which comes into contact with the image carrier, for example, a neutralizing brush for removing a residual charge on the photosensitive member, or a primary brush for transferring a toner image on the photosensitive member to an intermediate transfer member. In an image forming apparatus provided with a transfer brush or the like, after the rotation of the image carrier at the end of image formation as described above, when the image carrier is reversed, by the reverse rotation of the image carrier, The tip of the imaging brush is loosened and loosened, which adversely affects the imaging performance.

Therefore, in the image forming apparatus of the present invention, the image forming brush is configured to be separated from the image carrier when the image carrier is reversed at the end of image formation. FIG. 4 shows a basic control flow of this embodiment. Specifically, as shown in FIG. 5, a support arm 13a of a primary transfer brush 13 provided inside the intermediate transfer belt 10 for transferring a toner image on the photoconductor 1 to the intermediate transfer belt 10 is provided. The primary transfer brush 1 is supported on the support shaft 13b so as to contact the peripheral surface of the contact / separation cam 100 formed of an eccentric rotating cam, and the primary transfer brush 1
3 is configured to be freely contactable and detachable, and as shown in FIG. 5B, when the intermediate transfer belt 10 is rotated in the reverse direction of the arrow b, the contact / separation cam 100 is rotated to a predetermined position, and the intermediate transfer belt is rotated. The distal end of the primary transfer brush 13 is separated from 10. Thereby, when the intermediate transfer belt 10 rotates in the reverse direction, the tip of the primary transfer brush 13 is prevented from coming loose, and its transfer performance is always maintained in a good state. FIG. 6 shows an example of the control flow of this embodiment. Here, the image carrier to be controlled is the intermediate transfer belt 10, and the primary transfer brush 13 is moved toward and away from the intermediate transfer belt 10. 1
Needless to say, a neutralization brush (not shown) may be brought into contact with or separated from the battery.

By the way, as shown in FIG. 7, in the image forming apparatus having the structure in which the primary transfer brush 13 is fixed to the inner peripheral surface of the intermediate transfer belt 10 by bringing the tip of the primary transfer brush 13 into contact therewith, as described above. After the completion of the formation rotation, the intermediate transfer belt 10 is rotated in the reverse direction so that the cleaning blade 16A
As a result of conducting an experiment for examining the state of adhesion of toner, paper powder, and the like to the leading end of the intermediate transfer belt 10, if the reverse rotation amount A of the intermediate transfer belt 10 is 1 mm or more even when the primary transfer brush 13 is fixed, the cleaning blade 16A If the amount of reversal A of the intermediate transfer belt 10 is 5 mm or less, the tip of the primary transfer brush 13 will not be loosened and dislodged if the toner powder or the like is solidified and adhered to the tip of the intermediate transfer belt 10 while staying. It was revealed. Therefore, a static elimination brush or a transfer brush as an image forming brush that is in contact with the image carrier is provided inside the photoreceptor or the intermediate transfer member as described above, and the image carrier is provided. In an image forming apparatus having a configuration in which the body is reversed at the end of image formation, the amount of reversal A of the image carrier is
Is preferably 1 to 5 mm from the viewpoint of preventing the tip of the image forming brush from being loosened due to the reverse rotation of the image carrier and performing good image formation.

As in the above-described experiment, as shown in FIG. 8, in the image forming apparatus having the structure in which the primary transfer brush 13 is fixed to the inner peripheral surface of the intermediate transfer belt 10 by bringing the tip of the primary transfer brush 13 into contact therewith. As described above, as a result of an experiment in which the intermediate transfer belt 10 after the completion of the image forming rotation is rotated in reverse to check the adhesion state of toner, paper dust, and the like to the tip of the cleaning blade 16A, the primary transfer brush 13 Even if it is fixed, the reverse rotation amount A of the intermediate transfer belt 10
Is 1 mm or more, the cleaning blade 16A
The toner powder and the like are not solidified and adhered to the leading end of the primary transfer brush 13, and if the protrusion amount B of the primary transfer brush 13 is 以下 or less, the leading end of the primary transfer brush 13 is not loosened and separated. It became clear. Therefore, in the image forming apparatus in which the image forming brush which comes into contact with the image carrier is provided inside the image carrier as described above, and the image carrier is reversed at the end of the image formation. It is preferable that the amount of reversal of the image carrier is set to be equal to or less than 1/2 of the amount of protrusion of the image forming brush, so that the tip of the image forming brush due to the reversal of the image carrier is prevented from being loosened. It is preferable for performing an image.

Here, the image carrier is an intermediate transfer belt 10 to which a toner image formed on the photoconductor 1 is transferred, and the image forming brush is a toner image formed on the photoconductor 1. Is transferred to the intermediate transfer belt 10 to prevent the tip of the primary transfer brush 13 from being loosened due to the reverse rotation of the intermediate transfer belt 10, so that the transferability of the intermediate transfer belt 10 is improved. Is effective in maintaining

[0032]

The present invention is embodied in the form described above and has the following effects.

The image carrier is configured to be freely rotatable in the normal and reverse directions. After the image carrier is rotated at the end of the image formation, the image carrier is rotated in the reverse direction, so that the toner accumulated at the tip of the cleaning blade is removed. , Paper dust and the like can be removed, and good cleaning properties can always be maintained.

In an image forming apparatus provided with an image forming brush which is in contact with the image carrier, the image forming brush is moved away from the image carrier when the image carrier is reversed at the end of image formation. By separating, the tip of the image forming brush is prevented from being loosened when the image carrier is reversed, and the contact of the image forming brush with the image carrier is always good, so that a good image is formed. Can do it.

Further, in an image forming apparatus provided with an image forming brush which comes into contact with the image carrier as described above, and in which the image carrier is reversed at the end of image formation,
By defining the amount of reversal of the image carrier to be 1 to 5 mm, it is possible to prevent the tip of the image forming brush from being loosened due to the reversal of the image carrier, and to always perform good image formation.

Further, in the image forming apparatus provided with the image forming brush which comes into contact with the image carrier as described above, and in which the image carrier is reversed at the end of the image formation,
By setting the amount of reversal of the image carrier to be equal to or less than 1/2 of the amount of protrusion of the image forming brush, it is possible to prevent the tip of the image forming brush from being dislodged due to the reversal of the image carrier, thereby achieving good image formation. Images can be made.

The image carrier is an intermediate transfer member to which the toner image formed on the photoconductor is transferred, and the image forming brush converts the toner image formed on the photoconductor into the intermediate transfer member. By using the primary transfer brush for transferring to the transfer member, it is possible to prevent the tip of the primary transfer brush from being loosened due to the reverse rotation of the image carrier, and to always maintain good transferability of the intermediate transfer member. it can.

[Brief description of the drawings]

FIG. 1 is a schematic center sectional view of a multicolor image forming apparatus embodying the present invention.

FIG. 2 is a schematic cross-sectional view of a main part for describing an operation and an operation in the embodiment of the present invention.

FIG. 3 is a flowchart illustrating an example of a control operation according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating an example of a control operation according to another embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a main part for describing an operation and an operation in another embodiment of the present invention.

FIG. 6 is a flowchart illustrating an example of a control operation according to still another embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view of a main part for describing an operation and an operation in still another embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view of a main part for describing an operation and an operation in still another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 4 charging device 5 laser writing unit 6 multicolor developing device 7 black developing unit 10 intermediate transfer belt 13 primary transfer brush 14 transfer roller 15A cleaning blade for photoconductor 16 cleaning device for intermediate transfer belt 16A for intermediate transfer belt Cleaning blade 17 Paper feeder 18 Paper feed roller 19 Conveyance roller 20 Registration roller 100 Cam for contacting / separating primary transfer brush A Amount of reverse rotation of image carrier B Projection amount of image forming brush E Electrical / control device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Yoshiaki Miyashita 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Yoshiaki Nagao 1-3-6 Nakamagome, Ota-ku, Tokyo・ In Ricoh Co., Ltd.

Claims (5)

[Claims] An image forming apparatus for cleaning an image carrier with a cleaning blade, wherein the image carrier is reversed after rotation of the image carrier at the end of image formation. Forming equipment. 2. An image forming apparatus according to claim 1, further comprising an image forming brush provided in contact with said image carrier, wherein said image carrier is reversed when image formation is completed. An image forming apparatus, wherein the image forming brush is sometimes separated from the image carrier. 3. An image forming apparatus comprising: an image forming brush provided in contact with an image carrier; and wherein the image carrier is reversed at the end of image formation. An image forming apparatus having an amount of 1 to 5 mm. 4. An image forming apparatus comprising an image forming brush provided in contact with an image carrier and wherein the image carrier is reversed at the end of image formation. An image forming apparatus characterized in that the amount is not more than の of the protrusion amount of the image forming brush. 5. The image bearing member is an intermediate transfer member to which a toner image formed on a photoconductor is transferred, and the image forming brush transfers the toner image formed on the photoconductor to the intermediate transfer member. The image forming apparatus according to claim 2, wherein the image forming apparatus is a primary transfer brush for transferring the image onto a body.