JPH09152787A - Transfer device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of a transfer belt by providing a transfer belt between a driving roller and a driven roller, an elastic roller formed of an elastic body and being contact with the inside face of the transfer belt, and a cleaning blade being press-contact with the elastic roller from the outside of the transfer belt through the transfer belt. SOLUTION: In the transfer device 10, the cleaning blade 38 is brought into press contact with the surface of the transfer belt 33, and the press-contact force of the cleaning blade 38 is given to the elastic roller 37 through the transfer belt 33, then, the circumferential surface of the elastic roller 32 is elastically deformed. The transfer belt 33 is held between the elastic roller 37 and the cleaning blade 38 while being bitten into the elastic roller 37. All the leading end of the cleaning blade 38 is bitten into the surface of the transfer belt 33, then, the toner sticking to the surface of the transfer belt 33 is surely scraped by the cleaning blade 38. The hardness of the elastic roller 37 is made lower, so that the cleaning blade 38 can be bitten into the roller 37 through the transfer belt 33 even in the case of reducing the press contact force of the cleaning blade.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device of an image forming apparatus, and more particularly to a transfer device of an image forming apparatus for transferring a toner image carried by an image carrier of the image forming apparatus onto a sheet.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as a copying machine, an image of a document read by an exposure unit is formed on a photosensitive drum which is an image carrier. A charging device, a developing device, a transfer device, a cleaning device, and the like are arranged around the photosensitive drum. First, the surface of the photosensitive drum is charged by the charging device to form an electrostatic latent image of the original image read by the exposure section. In the developing device, a toner image is formed according to the electrostatic latent image formed on the photosensitive drum.

In the transfer device, the toner image on the photosensitive drum is transferred to a sheet, and the sheet after the toner image is transferred is separated from the photosensitive drum. The cleaning device removes the toner remaining on the surface of the photoconductor drum after transferring the toner image on the paper. In the transfer device of the image forming apparatus as described above, a corona discharge method using a discharge wire is generally used. This transfer method using corona discharge has problems that the transferability is poor when the humidity is high, and that transfer failure is likely to occur due to dirt on the discharge wire, wrinkles on the transfer paper, or the like.

In order to solve such a problem, a transfer including a driving roller, a driven roller arranged at a distance from the driving roller, and a transfer belt stretched between the driving roller and the driven roller. There is a device in which the device is disposed opposite to the photosensitive drum. In such a transfer device, a transfer roller is arranged at a position facing the photosensitive drum with the transfer belt interposed therebetween, and a high voltage is applied to the transfer roller to charge the transfer roller. As a result, charges are applied by the transfer roller from the back surface of the sheet conveyed between the photoconductor drum and the transfer belt, and the toner on the photoconductor drum is adsorbed on the surface of the sheet.

At this time, since the toner separated from the photosensitive drum is adsorbed and contaminated on the surface of the transfer belt, it is indispensable to install a cleaning device for removing the toner attached to the transfer belt. As this cleaning device, a device in which a cleaning blade is pressed against a transfer belt is generally used.

[0006]

In the above-described transfer device, since the transfer belt is stretched between the driving roller and the driven roller, it is difficult to press the cleaning blade against the transfer belt with a uniform force. Is. Further, in order to effectively clean the transfer belt, it is necessary to increase the pressure contact force of the cleaning blade with the transfer belt to improve the toner scraping performance.
However, since the drive torque of the drive roller increases, a power source with high capacity is required. Moreover, a great deal of stress is applied to the surface of the transfer belt, which may shorten the life of the transfer belt.

On the other hand, when the pressure contact force of the cleaning blade with respect to the transfer belt is weakened, a gap is likely to be formed between the edge of the cleaning blade and the surface of the transfer belt. In this case, there is a problem that the toner adhering to the transfer belt is not completely removed, and the back surface of the supplied sheet is likely to be contaminated with toner. An object of the present invention is to maintain a good cleaning property of a transfer belt by a cleaning blade and to bring the cleaning blade into contact with the transfer belt with a weak pressure contact force, thereby making it possible to prolong the life of the transfer belt. It is to provide a transfer device of a forming device.

[0008]

A transfer device of an image forming apparatus according to the present invention comprises a driving roller, a driven roller, a transfer belt, a voltage applying means, an elastic roller and a cleaning blade. . The driven roller is arranged at a distance from the drive roller. The transfer belt is stretched between a driving roller and a driven roller, and contacts the image carrier of the image forming apparatus via the paper. The voltage applying unit applies an electric charge for transferring the toner image formed on the image carrier to the sheet supplied between the transfer belt and the image carrier. The elastic roller is arranged so as to contact the inner surface of the transfer belt and is made of an elastic material. The cleaning blade is pressed against the elastic roller from the outside of the transfer belt via the transfer belt.

In this case, the cleaning blade can be pressed against the transfer belt while the elastic roller is elastically deformed, and good cleaning performance can be maintained with a weak pressing force. The elastic roller can be made of any material of silicone rubber, urethane rubber, foamed polyurethane, and foamed polyurethane having a skin layer on the surface. Further, the elastic roller may have a lower hardness than the cleaning blade. Here, the hardness of the elastic roller is ASKER-F20 ° to ASKER.
It is preferably −C70 °. This hardness is ASKER-F2 when the hardness of the sample using Asker rubber hardness meter F type manufactured by Kobunshi Keiki Co., Ltd. is 20 °.
When the hardness of the sample is 0 ° and the hardness of the sample is 70 ° when using Asker rubber hardness tester C type manufactured by the same company, ASKER-C
Set to 70 °.

Further, the elastic roller may have a structure in which an elastic member made of an elastic material of at least 2 mm is formed on the outer periphery of the core material.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic vertical sectional view of a copying machine to which an embodiment of the present invention is applied. The copying machine 1 is provided with an exposure section 5 for reading a document on the upper part thereof. The exposure unit 5 includes a light source, a mirror, a lens unit, and the like. Further, an image forming unit 6 for forming a toner image of the read original is formed in the center of the copying machine 1. The image forming unit 6 has a photosensitive drum 7 on the surface of which an electrostatic latent image is formed. Around the photosensitive drum 7, a charging device 8, a developing device 9, a transfer device 10, and a cleaning device 11 are arranged.

A paper feed unit 12 is provided below the copying machine 1. The paper feeding unit 12 includes a bypass table 13 provided on the right side of the copying machine 1 in FIG. 1 and three paper feeding cassettes 14, 15, 16 arranged vertically below the copying machine 1.
A paper feed tray 17, a bypass table 13, and a paper feed device 18 for feeding the paper stored in the paper feed cassettes 14 to 17 to the image forming unit 6. On the downstream side of the image forming unit 6 in the sheet conveying direction, a sheet discharge conveying path 19 for conveying the sheet to the left side of the apparatus in FIG. 1, a fixing device 20 for melting and fixing a toner image on the sheet, and a sheet at the time of fixing A discharge roller 21 for discharging the sheet and a sheet discharge tray 22 for receiving the sheet are provided.

As shown in FIG. 2, the transfer device 10 includes a drive roller 31, a driven roller 32 spaced apart from the drive roller 31, and a transfer belt 33 stretched over the drive roller 31 and the driven roller 32. It has and. The drive roller 31 has its rotation shaft connected to a drive motor via a power transmission mechanism such as a gear (not shown). Driven roller 32
Are arranged apart from the driving roller 31 and are rotatably supported by the shaft. The transfer belt 33 is made of a semi-conductive material and has an endless shape.
1 drives the photosensitive drum 7 to rotate at substantially the same speed as the peripheral surface speed of the photosensitive drum 7.

The transfer device 10 further includes a transfer belt 33.
Guide rollers 34 and 35 that contact the inner peripheral surface of the are provided. The guide rollers 34, 35 have their tangent lines contacting both outer circumferences of the guide rollers 34, 35 so that the peripheral surface of the transfer belt 33 is in pressure contact with the peripheral surface of the photoconductor drum 7.
It is arranged so that it crosses. Guide rollers 34, 35
A transfer roller 36 facing the photosensitive drum 7 via the transfer belt 33 is provided in the middle of. The transfer roller 36 is made of a conductive material and is connected to a high-voltage charge applying unit (not shown).

Further, the driving roller 31 and the driven roller 32
An elastic roller 37 that is in contact with the inner surface of the transfer belt 33 is disposed in the middle of the above. This elastic roller 37
Is formed by winding an elastically deformable elastic body material around a central shaft member. As the elastic material, silicon rubber, urethane rubber, foamed polyurethane, or the like can be used. Further, as shown in FIG. 3, an elastic roller 37 having an elastic member 43 made of an elastic material such as foamed polyurethane around the shaft member and a skin layer 44 made of silicon rubber, urethane rubber or the like formed on the surface thereof. Can also be used. The elastic body roller 37 is formed by laminating such elastic body material on the peripheral surface of a shaft member such as stainless steel by at least 2 mm or more, and as a whole, ASKER-F 20 ° to ASKE
It is preferable that the hardness is R-C 70 °.

Further, the elastic roller 37 is constructed so as to be able to transmit drive, and for example, the peripheral speed can be rotationally driven to be substantially the same as the moving speed of the transfer belt 33. It can also be configured to rotate. The transfer device 10 is further provided with a cleaning blade 38 whose tip is pressed against the peripheral surface of the elastic roller 37 via the transfer belt 33. The cleaning blade 38 has at least the same width as the width of the transfer belt 33, and a pressure contact force is applied to the tip thereof to such an extent that the peripheral surface of the elastic roller 37 is elastically deformed. The cleaning blade 38 is made of an elastic material or a thin metal plate such as stainless steel, and has a hardness higher than that of the elastic roller 37.

The cleaning blade 38 is fixed to a base 39. The base 39 is supported by a rotating shaft 40, and the tip of the cleaning blade 38 has the elastic roller 3
It is possible to rotate in the direction in which it is attached to and detached from the peripheral surface of 7. The lower surface of the base 39 is supported by a pressure contact rod 41. The pressure contact rod 41 is arranged at a position where the pressure contact force at the tip of the cleaning blade 38 becomes appropriate. When adjusting the pressure contact force at the tip of the cleaning blade 38, a thin film sheet 42 such as a polyester sheet is inserted between the pressure contact rod 41 and the base 39.

In the transfer device 10 of the present invention as described above, the cleaning blade 38 is pressed against the surface of the transfer belt 33. As a result, the elastic roller 37 receives the pressure contact force from the cleaning blade 38 via the transfer belt 33, and the peripheral surface is elastically deformed. The transfer belt 33 is sandwiched between the elastic roller 37 and the cleaning blade 38 so as to bite into the elastic roller 37. The tip of the cleaning blade 38 bites into the surface of the transfer belt 33 over the entire area, and it is possible to reliably scrape off the toner attached to the surface of the transfer belt 33.

Since the hardness of the elastic roller 37 is low, even if the pressing force of the cleaning blade 38 is lowered,
The elastic roller 37 can be surely bitten through the transfer belt 33, and deterioration of the surface of the transfer belt 33 can be reduced. The transfer belt 33 is attached to the elastic roller 37.
Since the cleaning is carried out by sandwiching the transfer belt 33 between the cleaning belt 38 and the cleaning blade 38, the tension of the transfer belt 33 can be kept low, and the transfer belt 3 can be used.
3 can be extended. Further, the elastic roller 37 is capable of transmitting drive, and especially when the elastic roller 37 is rotationally driven in the moving direction of the transfer belt 33,
The driving torque of 1 can be reduced, and the deterioration of the transfer belt 33 can be further reduced.

[0020]

In the transfer device of the image forming apparatus according to the present invention, the transfer belt is sandwiched by the elastic roller and the cleaning blade so as to bite into the surface of the elastic roller, and the pressure contact force of the cleaning blade is maintained uniform. It is possible to reliably scrape off the toner attached to the surface of the transfer belt. Further, the toner on the surface of the transfer belt can be reliably removed even if the pressure contact force of the cleaning blade is lowered, and the deterioration of the transfer belt can be reduced. Further, since the transfer belt is sandwiched between the elastic roller and the cleaning blade for cleaning, the transfer belt can be used with a low tension, and the life of the transfer belt can be extended.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional configuration diagram of a copying machine to which an embodiment of the present invention is applied.

FIG. 2 is an enlarged view of a main part thereof.

FIG. 3 is an explanatory diagram of an elastic roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copier 6 Image forming part 7 Photosensitive drum 8 Charging device 9 Developing device 10 Transfer device 11 Cleaning device 12 Paper feeding part 18 Paper feeding device 19 Paper discharge conveying path 20 Fixing device 31 Driving roller 32 Driven roller 33 Transfer belt 34 Guide Roller 35 Guide roller 36 Transfer roller 37 Elastic roller 38 Cleaning blade 39 Base 40 Rotating shaft 41 Pressure contact rod 42 Thin film sheet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naofumi Miyake 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Industrial Co., Ltd. (72) Yukinori Akiyama 1-228 Tamatsukuri, Chuo-ku, Osaka Within Mita Engineering Co., Ltd.

Claims (5)

[Claims] 1. A transfer device of an image forming apparatus for transferring a toner image carried on an image bearing member of the image forming apparatus onto a sheet, the drive device comprising a drive roller and a space provided between the drive roller and the drive roller. A driven roller, a transfer belt stretched between the drive roller and the driven roller and contacting the image carrier of the image forming apparatus via the sheet, and the transfer belt is supplied between the transfer belt and the image carrier. A voltage applying unit that applies a charge for transferring a toner image formed on an image carrier to a sheet, an elastic roller that is made of an elastic body and contacts the inner surface of the transfer belt, and an outer side of the transfer belt. A transfer device of an image forming apparatus, comprising: a cleaning blade that comes into pressure contact with an elastic roller via the transfer belt. 2. The transfer device for an image forming apparatus according to claim 1, wherein the elastic roller is made of any one of silicon rubber, urethane rubber, foamed polyurethane, and foamed polyurethane having a skin layer on its surface. . 3. The transfer device of the image forming apparatus according to claim 1, wherein the elastic roller has a hardness lower than that of the cleaning blade. 4. The hardness of the elastic roller is ASKER-
F20 ° to ASKER-C70 °.
The transfer device of the image forming apparatus according to any one of 1. 5. The transfer device for an image forming apparatus according to claim 1, wherein the elastic roller has an elastic member made of an elastic material of at least 2 mm formed on an outer periphery of a core material. .