JP2002351228A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus with high image quality and high durability at low cost by enhancing the durability of a cleaning means. SOLUTION: In the apparatus, a multiple number of image carriers, a belt member abutted to the multiple number of image carriers, a tension roll where the belt member is hung, an energizing means to impart hanging force to the tension roll, a holding means to support the shaft of the tension roll to be able to be freely rotated and a cleaning means of the belt member installed in the holding means and abutted to the tension roll through the belt member are provided. In this case, hanging force is imparted to the tension roll by the energizing means in a position different from the holding means.

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 for transferring an image by using a belt member, and more particularly, to an apparatus in which a tension roller for stretching a belt member and cleaning means are integrally formed.

[0002]

2. Description of the Related Art In recent years, downsizing of an entire image forming apparatus has been regarded as important. One technique for downsizing is to transfer toner images of each color on a plurality of image carriers onto an intermediate transfer belt in a superimposed manner. Then, there is an image forming apparatus which adopts a method of transferring the image to a transfer material at once.

A configuration of a conventional intermediate transfer belt unit will be described with reference to FIGS. FIG. 4 is a perspective view illustrating an intermediate transfer belt according to a conventional example, and FIG. 5 is an enlarged view of a main part illustrating a tension applying mechanism.

The intermediate transfer belt 101 shown in FIG. 4 is stretched by a driving roller 102, an opposing roller 103, and a tension roller 104. A plurality of primary transfer rollers 105 are disposed inside the intermediate transfer belt 101, and the intermediate transfer belt 101
Is brought into contact with the image carrier 100 (see FIG. 5) to transfer the toner image on the image carrier 100. Further, the toner image on the intermediate transfer belt 101 is transferred to the opposing roller 103 and the secondary transfer roller 106 (FIG. 5).
When the transfer material is nipped and conveyed by (see), it is collectively transferred to the transfer material.

A driving roller 102 and an opposing roller 103 are rotatably supported by a frame 107.
The shaft 104a of 04 is rotatably supported by the bearing part 108a of the holding member 108. The holding member 108 is a long groove 107 of the frame 107.
a, and is configured to be slidable while maintaining a constant posture. End surface 107b of long groove 107a and holding member
A compression spring 109, which is an urging means, is attached between the pressure members 108. The tension force is applied to the tension roller 104 by urging the holding member 108 with the compression spring 109. The material of the holding member 108 is a conductive polyacetal resin in order to electrically ground the tension roller 104.

A cleaner case 110 is supported so that both ends are supported by the holding member. As shown in FIG. 5, a blade 111 serving as a cleaning means is mounted inside the cleaner case 110. The blade 111 is for scraping off the toner remaining on the intermediate transfer belt 101 and is in contact with the tension roller 104 at a predetermined angle with the intermediate transfer belt 101 interposed therebetween. The residual toner scraped off by the blade 111 is
It is transported to the outside of the case by the auger 112 arranged inside.

As described above, since the tension roller 104 and the cleaner case 110 are both attached to the holding member 108 and integrally formed, the relative position between the tension roller 104 and the blade 111 of the cleaner is assured. It is a configuration that can exhibit performance stably.

[0008]

However, in the above-mentioned conventional construction, since the bearing 108a of the tension roller 104 is formed on the holding member 108, the tension is applied to the inner wall of the bearing 108a of the holding member 108. The shaft 104 a of the roller 104 rotates while being pressed by the compression spring 109. As a result, the inner wall of the bearing portion 108a wears, and as a result, the holding member 1
08 and the relative position of the tension roller 104 change. As a result, the contact position of the blade 111 also changes. Therefore, as shown in FIG.
In some cases, a gap S is generated between the two and the cleaning performance is significantly reduced.

On the other hand, it is conceivable to use a bearing for the bearing portion 108a, but there is a problem because it causes an increase in production cost. In particular, since conduction cannot be guaranteed with a normal bearing, a bearing filled with conductive grease is used, which further increases the cost.

On the other hand, if the urging force of the compression spring 109 is weakened, wear can be reduced. However, conversely, slippage occurs between the drive roller 102 and the intermediate transfer belt 101, which affects image formation. Therefore, it is difficult to reduce the load so that abrasion can be prevented.

Accordingly, an object of the present invention is to provide an image forming apparatus having high image quality, high durability and low cost by increasing the durability of the cleaning means.

[0012]

In order to solve the above-mentioned problems, a typical configuration of an image forming apparatus according to the present invention includes a plurality of image carriers, and a belt member which contacts the plurality of image carriers. A tension roller for stretching the belt member,
Urging means for applying tension to the tension roller,
Holding means for rotatably supporting the tension roller, and cleaning means for a belt member provided on the holding means and abutting on the tension roller via the belt member, wherein the urging means comprises: A tension force is applied to the tension roller at a position different from the holding means.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is an enlarged perspective view of a main part for explaining a tension applying mechanism of the intermediate transfer belt according to the present embodiment, FIG. 2 is a side view showing an overall configuration of the image forming apparatus, and FIG. 3 is a side view of the intermediate transfer belt.

First, the overall configuration of the image forming apparatus will be described with reference to FIG. The illustrated image forming apparatus 1 is a four-drum full-color image forming apparatus having an intermediate transfer belt 30. A cassette 20 for stacking and storing a plurality of transfer materials P is removably mounted on the image forming apparatus 1. The cassette 20 is fed by a feed roller 21 and separated by a separation roller pair 22. The sheet is conveyed to the registration roller pair 24 by the roller pair 23. The registration roller pair 24 stops rotating when the transfer material P is transported, and the skew of the transfer material P is corrected by abutting the transfer material P against the nip.

In the apparatus, yellow, magenta, cyan,
Four process cartridges including image carriers 26Y, 26M, 26C, and 26Bk of each color of black are arranged in parallel, and an optical scanning system 28Y, 28M, 28C, 28Bk is provided for each process cartridge. A toner image is formed on the image carrier 26 for each color by the image signal.

As shown in FIG. 3, the intermediate transfer belt 30 is disposed so as to abut on all the image carriers, and is stretched by a driving roller 31, an opposing roller 32, and a tension roller 33. A primary transfer roller 34 is disposed at a position facing the image carrier 26, and the toner image on the image carrier 26 is transferred onto the intermediate transfer belt 30 in a superimposed manner. The transfer material P conveyed at a predetermined timing by the transfer roller 27 is nipped and conveyed, and the color toner images are collectively transferred.

Then, as shown in FIG. 2, the transfer material P on which the toner image has been transferred is conveyed to a fixing device 25, where heat and pressure are applied to fix the toner image.
The sheets are discharged and stacked outside the apparatus by a and 29b.

Next, the structure near the tension roller 33 according to the present invention will be described with reference to FIGS. The driving roller 31 and the opposing roller 32 are rotatably supported on the frame 35 as in the conventional example, and the shaft 33a of the tension roller 33 is rotatably supported on the bearing 36a of the holding member 36 (see FIG. 3). The holding member 36 is fitted in the long groove 35a of the frame 35, and is configured to be slidable while maintaining a constant posture.

A cleaner case 37 is supported so that both ends are supported by the holding member 36, and a blade 38 as cleaning means is mounted inside the cleaner case 37. The blade 38 scrapes off the toner remaining on the intermediate transfer belt 30 and is in contact with the tension roller 33 at a predetermined angle with the intermediate transfer belt 30 interposed therebetween. The residual toner scraped off by the blade 38 is conveyed to the outside of the cleaner case 37 by an auger 39 arranged inside the case.

As shown in FIG. 1, a tension bearing 40 is rotated on a shaft 33a of the tension roller 33 as a biasing means for applying a tension to the tension roller 33 at a position different from the holding member 36. Mounted freely. End surface 40a of tension bearing 40 and wall surface 35 of frame 35
A compression spring 41 is attached between the intermediate transfer belt 30 and the intermediate transfer belt 30 by urging a shaft 33a of the tension roller 33 with the compression spring 41. The material of the tension bearing 40 is a conductive polyacetal resin, and the tension roller 33 is electrically grounded.

With this configuration, the holding member
Although the shaft 36a and the shaft 33a of the tension roller 33 rotate and slide as in the prior art, the load applied to the inner wall of the bearing portion 36a of the holding member 36 is reduced, and the abrasion of the inner wall surface can be almost eliminated. On the other hand, abrasion occurs on the inner wall 40b of the tension bearing 40 due to the sliding of the tension roller 33 with the shaft 33a. Has no effect on the relative positional relationship between the roller and the tension roller 33. Although the urging force of the compression spring 41 slightly decreases due to the wear, the conveyance of the intermediate transfer belt 30 does not slip due to the amount of change.

In this embodiment, a four-drum full-color image forming apparatus has been described as an image forming apparatus. However, the present invention is not limited to this, and one image carrier and one intermediate transfer belt are used. The same effect can be obtained in a frame sequential full color image forming apparatus and an image forming apparatus having a transfer material carrier that carries and conveys a transfer material as a belt member and abuts a plurality of image carriers.

Although the present embodiment has been described using a conductive polyacetal resin as the material of the tension bearing, similar effects can be obtained by using, for example, an iron-based or copper-based oil-impregnated sintered material. Obtainable.

[0024]

As described above, in the present invention,
In the image forming apparatus using the belt member, the urging means of the tension roller is configured to apply a tension force to the tension roller at a position different from the holding means for integrally holding the tension roller and the cleaning means. As a result, the durability of the cleaning unit can be enhanced, and an image forming apparatus with high image quality, high durability, and low cost can be provided.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view of a main part for explaining a tension applying mechanism of an intermediate transfer belt according to an embodiment of the present invention.

FIG. 2 is a side view illustrating an overall configuration of the image forming apparatus.

FIG. 3 is a side view of the intermediate transfer belt.

FIG. 4 is a perspective view illustrating an intermediate transfer belt according to a conventional example.

FIG. 5 is an enlarged view of a main part for explaining a tension applying mechanism.

FIG. 6 is an enlarged view of a main part for explaining a tension applying mechanism.

[Explanation of symbols]

 P: transfer material 1: image forming apparatus 20: cassette 21: feed roller 22: separating roller pair 23: transport roller pair 24: registration roller pair 25: fixing device 26: image carrier 27: secondary transfer roller 28: optical Scanning system 29: Discharge roller pair 30: Intermediate transfer belt 31: Driving roller 32: Opposing roller 33: Tension roller 33a: Shaft 34: Primary transfer roller 35: Frame 35a: Long groove 35b: Wall surface 36: Holding member 36a: Bearing 37 ... Cleaner case 38 ... Blade 39 ... Auger 40 ... Tension bearing 40a ... End face 40b ... Inner wall 41 ... Compression spring 100 ... Image carrier 101 ... Intermediate transfer belt 102 ... Driving roller 103 ... Opposing roller 104 ... Tension roller 104a ... Shaft 105 ... Primary transfer roller 106 ... Secondary transfer roller 107 ... Frame 107a ... Long groove 107b ... End face 108 ... Holding member 108a ... Bearing part 109 ... Compression spring 110 ... Cleaner case 111 ... Blade 112 ... auger

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H030 AB02 BB42 2H200 FA08 GA12 GA23 GA47 JB06 JB31 JB42 JB45 JB46 JC03 JC07 JC12 JC15 JC16 LA17 LA29 LB02 LB08 LB13 MA01 MA02 MB01

Claims (2)

[Claims] 1. A plurality of image carriers, a belt member that contacts the plurality of image carriers, a tension roller that stretches the belt member, and a biasing unit that applies a tension force to the tension roller. Holding means for rotatably supporting the tension roller, and cleaning means for a belt member provided on the holding means and abutting on the tension roller via the belt member, the urging means, An image forming apparatus, wherein a tension force is applied to the tension roller at a position different from the holding unit. 2. The image forming apparatus according to claim 1, wherein the belt member is an intermediate transfer belt that carries a plurality of toner images transferred from the plurality of image carriers in a superimposed manner, or carries and conveys a transfer material to the plurality of image carriers. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a transfer material carrier that is in contact with the image forming apparatus.