JPH10221977A - Transfer device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the number of times of maintenance of a transfer roller, extend the life of the transfer roller, and prevent back stains on recording paper. An arm (5) that rotates about a center support shaft (4).
Transfer rollers 2 and 2 are attached to both ends of the revolver, respectively. The cleaning member 3 is in contact with the transfer roller 2 opposite to the transfer roller 2 at the transfer position. The two transfer rollers 2 and 2 are alternately switched during the same use period regardless of the recording paper size and copy conditions. During standby, both the transfer rollers 2 and 2 are separated from the photosensitive drum 1.
A transfer bias and a cleaning bias are applied to both transfer rollers 2 and 2 by a high voltage power supply 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device for an electrophotographic apparatus such as a copying machine, a facsimile, and a printer.
In particular, the present invention relates to a transfer device of the type in which a recording paper is pressed against a toner image on a photosensitive member by a transfer roller and the toner image is transferred to the recording paper.

[0002]

2. Description of the Related Art A transfer device of an electrophotographic apparatus has a transfer roller, and the transfer roller presses a recording sheet against a toner image on a photosensitive drum, in other words, a nip between the photosensitive drum and the transfer roller. There is known a roller transfer type transfer device for holding a recording sheet and transferring the toner image onto the recording sheet.

Further, a transfer charger is provided in close proximity to the photosensitive member, and a bias voltage having a polarity opposite to that of the toner is applied to the back surface of the recording paper in contact with the photosensitive member at the transfer position by the transfer charger. Also, a transfer device of a transfer charger type, which transfers data to recording paper, is widely used.

The most common configuration of a transfer device of a roller transfer type is, for example, as shown in Japanese Patent Application Laid-Open No. 5-53456, in which a developing device disposed around a photosensitive drum rotates in a direction of rotation of the photosensitive drum. In the vicinity of the downstream side, the transfer roller is disposed in contact with the photosensitive drum. Then, a toner removing member for scraping off the toner attached to the outer peripheral surface of the transfer roller is brought into contact with the transfer roller.

As described above, a roller transfer type transfer apparatus is most commonly provided with a single transfer roller. However, since there is only one transfer roller, all residual toner on the surface of the photoreceptor is removed. The toner adheres to the one transfer roller, and the cleaning member may not be able to complete the cleaning. In this case, dirt due to the toner easily accumulates on the surface of the transfer roller, and causes the back dirt of the recording paper. Further, the number of times of maintenance of the transfer roller also increases.

A technique for preparing a plurality of transfer rollers and using them in a switched manner is disclosed in, for example, Japanese Patent Laid-Open No. 4-20897.
No. 3 and Japanese Patent Application Laid-Open No. 6-308841.

In the technique described in Japanese Patent Application Laid-Open No. 4-208973, four transfer rollers are provided on a rotary plate, and these are selectively used depending on the paper size.

In the technique described in Japanese Patent Application Laid-Open No. Hei 6-308841, a transfer roller is attached to each of two arms and selectively used in accordance with copying conditions and environment.

[0009]

However, Japanese Patent Laid-Open Publication No.
In the case of the technology described in Japanese Patent Application Laid-Open No. 08973, the transfer roller is switched according to the size of the paper. Therefore, when printing the same size of paper continuously, only the same transfer roller is used, so that the transfer roller is easily stained. In addition, if only the same transfer roller is used, the life of the transfer roller will be shortened, and replacement work and cost will be required.

Also, in the technique described in Japanese Patent Application Laid-Open No. 6-308841, when the same transfer roller is used under the same conditions, only the same transfer roller is used, and the same problem as described above occurs.

The present invention has been made in view of such a background, and is based on the premise that a plurality of transfer rollers are used.
It is an object of the present invention to provide a transfer device capable of reducing the number of maintenance operations of a transfer roller, extending the life of the transfer roller, and preventing back contamination of recording paper.

[0012]

In order to achieve the above object, according to the first aspect of the present invention, a recording paper is pressed against a toner image formed on a photoreceptor, and the toner image is transferred onto the recording paper. Transfer device provided with a plurality of transfer rollers for the transfer, each transfer roller can be alternately switched to the transfer position regardless of the paper size and the copy condition.

According to a second aspect of the present invention, in the first aspect of the present invention, two transfer rollers are mounted in a revolver shape at both ends of an arm that rotates about a central support shaft, and a transfer position is provided. The cleaning member is in contact with the transfer roller on the opposite side of the transfer roller.

According to a third aspect of the present invention, in the first or second aspect of the invention, when the transfer operation is not performed, all the transfer rollers are separated from the transfer position and are on standby. Is what you do.

According to a fourth aspect of the present invention, in the second aspect of the present invention, a voltage having a polarity opposite to that of the toner is applied to the transfer roller at the transfer position, and the same voltage as the toner is applied to the transfer roller in contact with the cleaning member. A high voltage power supply for applying a polarity voltage is provided.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram showing a state of an operation of the transfer apparatus according to the first embodiment of the present invention, and FIG. 2 is a configuration showing a state of the transfer apparatus according to the first embodiment of the present invention in a standby state. FIG. The transfer device for transferring the toner image formed on the photosensitive drum 1 to the recording paper P conveyed to the transfer position of the photosensitive drum 1 includes two transfer rollers 2 and a cleaning member 3.

Each of the two transfer rollers 2 is pivotally supported on both ends of an arm 5 rotatable, for example, in the direction of an arrow A (clockwise) about a central support shaft 4 in a revolver shape.
One transfer roller 2 is at the transfer position, that is, the photosensitive drum 1
The other transfer roller 2 is in contact with the cleaning member 3.

The recording paper P is fed from a paper feeding device (not shown), and is conveyed along a recording paper conveying path in the direction of arrow B toward the transfer position. In the transfer section, the photosensitive drum 1 and the transfer roller at the transfer position 2 and is conveyed further downstream. In this process, the recording paper P is transferred to the transfer roller 2
As a result, the photosensitive drum 1 is pressed against the toner image on the photosensitive drum 1. This pressing causes the toner image to be transferred to the recording paper P.

The two transfer rollers 2 of the present invention are made of the same material and have the same shape, and can be switched at an arbitrary switching timing. That is, unlike the conventional example, the switching is not performed according to the paper size or the copy condition, but is performed so as to have the same use frequency.

Therefore, the two transfer rollers 2 are used equally, and the amount of adhered toner can be evenly dispersed, so that one cleaning member 3 can surely perform cleaning. As a result, the transfer roller 2 is less liable to be stained by the toner, so that the number of maintenance operations can be reduced and the life can be prolonged. Also, the back dirt can be eliminated.

At the time of standby, that is, at the time of non-image forming operation, FIG.
As shown in (1), the arm 5 is horizontal, and both transfer rollers 2 are separated from the photosensitive drum 1. By doing so, it is possible to prevent the transfer roller 2 from deteriorating due to the pressure contact with the photosensitive drum 1 and to prevent the residual toner on the photosensitive drum 1 from adhering to the transfer roller 2. can do.

FIG. 3 is a configuration diagram showing a state of the transfer apparatus according to the second embodiment of the present invention during operation. The transfer device according to the second embodiment also includes a transfer roller 2 having a revolver shape, and a cleaning member 3 that is in contact with the transfer roller 2 that is not used. The transfer device of the present embodiment is provided with a high-voltage power supply 6 in addition to the above. The high-voltage power supply 6 is a first power supply 6a that applies a voltage having a polarity opposite to that of the toner to the transfer roller 2 during operation at the transfer position.
And a second power supply 6b for applying a voltage of the same polarity as that of the toner to the transfer roller 2 opposite to the transfer roller 2 performing the transfer operation, that is, the transfer roller 2 in contact with the cleaning member 3. I have. Therefore, the toner image is efficiently transferred to the recording paper P (see FIG. 1) by the transfer bias, and the cleaning effect by the cleaning member 3 is enhanced.

[0023]

According to the first and second aspects of the present invention, the plurality of transfer rollers are alternately used regardless of the recording paper size and copying conditions, so that toner adhesion to the transfer rollers is evenly distributed. Thus, the load of the cleaning member on one transfer roller is reduced, and the toner adhering to the transfer roller can be efficiently cleaned. As a result, the number of maintenance of the transfer roller can be reduced, and the life can be extended. Further, it is possible to prevent the back stain of the recording paper.

According to the third aspect of the present invention, all the transfer rollers are separated from the photosensitive member during non-transfer, so that the toner attached to the photosensitive member can be prevented from being transferred to the transfer roller.

According to the present invention, a voltage having a polarity opposite to that of the toner is applied to the transfer roller at the transfer position, and a voltage having the same polarity as the toner is applied to the transfer roller that comes into contact with the cleaning member. Therefore, transfer efficiency and cleaning efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a state of an operation of a transfer device according to a first exemplary embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a standby state of the transfer apparatus according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a state during operation of a transfer device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Transfer roller 3 Cleaning member 4 Support shaft 5 Arm 6 High voltage power supply 6a First power supply 6b Second power supply P Recording paper

Claims (4)

[Claims] 1. A transfer apparatus comprising a plurality of transfer rollers for pressing a recording sheet against a toner image formed on a photoreceptor and transferring the toner image to the recording sheet, irrespective of the sheet size and copying conditions. A transfer device wherein each transfer roller is alternately switched to a transfer position. 2. The transfer roller according to claim 1, wherein the two transfer rollers are mounted in a revolver shape on both ends of an arm that rotates about a central support shaft, and are provided on a transfer roller opposite to the transfer position. A transfer device having a cleaning member in contact therewith. 3. The transfer device according to claim 1, wherein all the transfer rollers are separated from the transfer position and are on standby when the transfer operation is not performed. 4. The high-voltage power supply according to claim 2, wherein a voltage having a polarity opposite to that of the toner is applied to the transfer roller at the transfer position, and a voltage having the same polarity as the toner is applied to the transfer roller that contacts the cleaning member. A transfer device comprising: