JPH06149095A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a hollow character phenomenon (void) similarly to a conventional device and to eliminate an extension of a transfer image on a transfer material and a trouble caused by slip in the direction of rotation. CONSTITUTION:In an image forming device which elastically brings a transfer roller 2 into contact with an image carrier 1 and transfers a toner image on the image carrier 1 onto a transfer material passing between them, the image carrier 1 and the transfer roller 2 are made equal in peripheral speed to each other and are relatively reciprocated in the axial direction.

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 such as a copying machine or a laser beam printer. The present invention relates to an image forming apparatus configured to transfer the toner image of 1.

[0002]

2. Description of the Related Art As a conventional example of an image forming apparatus having the image bearing member and a transfer roller which is elastically contacted with the image bearing member, there is one disclosed in Japanese Patent Laid-Open No. 196087. In this conventional example, the peripheral speed of the contact portion between the image carrier and the transfer roller is changed, and the image carrier and the transfer roller rotate while slipping. It is possible to prevent a so-called holographic character phenomenon in which white spots occur in an island shape.

However, the transfer roller is pressed against the image carrier by a spring, and a bias voltage is applied to the transfer roller to transfer the toner image on the image carrier to the transfer material (sheet). If there is a difference in the peripheral speed between the image carrier and the transfer roller, the image transferred to the transfer material will be extended, or the behavior when slipping in the rotational direction will be the speed fluctuation of the drum-shaped image carrier. As a result, when halftone is created by a digital copying machine, a laser beam printer, or the like, banding with a striped pattern may occur.

The present invention has been made in view of the above, and it is possible to prevent a holographic character from occurring, and to prevent the occurrence of a problem due to the above-mentioned conventional problems such as image extension and slip in the rotational direction. It is intended to provide.

[0005]

In order to achieve the above object, an image forming apparatus according to the present invention is configured such that a transfer roller 2 is elastically brought into contact with an image carrier 1 and an image is carried on a transfer material passing between the two. In an image forming apparatus configured to transfer the toner image of the body 1, the image carrier 1 and the transfer roller 2 have the same peripheral speed, and the image carrier 1 and the transfer roller 2 relatively reciprocate in the axial direction. Is configured to. Further, the transfer roller 2 is movable in the axial direction, an axial biasing mechanism such as a spring 7 is provided on the transfer roller 2, and a cam 10 is provided at an end face portion of the transfer roller 2 on the axial biasing side. This cam 10
The cam follower 9 is brought into contact with the above.

[0006]

[Operation] The image carrier 1 and the transfer roller 2 rotate at the same peripheral speed, reciprocate in the axial direction, and slip in the axial direction during mutual rotation. Then, the material to be transferred passes between the image carrier 1 and the transfer roller 2, whereby the toner on the side of the image carrier 1 is transferred to the material to be transferred.

[0007]

EXAMPLES Examples of the present invention will be described with reference to the drawings. In the figure, 1 is an image bearing member configured in a drum shape, and 2 is a transfer roller which is in rolling contact with the image bearing member 1. A driven gear 3 is concentrically fixed to one end of the image carrier 1, and the driven gear 3 is meshed with a first drive gear provided on the main body side. A driven gear 5 is provided at the other end of the transfer roller 2.
Are fixed concentrically with each other, and the driven gear 5 is meshed with the second drive gear 6 provided on the main body side. 1st
The second drive gears 4 and 6 rotate the image carrier 1 and the transfer roller 2 in the same tangential direction. The drive gear line on the side of the image carrier 1 and the drive gear ratio on the side of the transfer roller 2 are set so that the peripheral speed of the image carrier 1 and the circumference of the transfer roller 2 are the same.

The transfer roller 2 is arranged in the axial direction and in the image carrier 1.
It is movable in the direction, is urged by the spring 7 toward the driven gear 5 side of the transfer roller 2, and is urged by the spring 8 toward the image carrier 1. The driven gear 5 of the transfer roller 2
A cam follower 9 that receives the urging force of the spring 7 urging in the axial direction is in contact with the end surface of the driven gear 5, and a cam 10 that is inclined in the circumferential direction is formed on the end surface of the driven gear 5. Further, in FIG. 1, 10 is a developing device, 11 is a cleaning device, 12 is a paper feeding device, and 13 is a fixing device. A bias voltage is applied to the transfer roller 2.

In the above structure, the first and second drive gears 4 and 6 on the main body side are driven to rotate the image carrier 1 and the transfer roller 2 while rolling them at the same peripheral speed. At this time, according to the rotation of the transfer roll 2, the cam 10 formed on the end surface of the driven gear 5 reciprocates in the axial direction by the height of the cam 10 and slips in the axial direction.

In the example shown in FIG. 2, the driven gear 5 of the transfer roller 2 is meshed with the second drive gear 6 different from the first drive gear 4 for driving the image carrier 1. As shown in FIG. 3, the driven gear 5 of the transfer roller 2 may be meshed with the driven gear 3 on the image carrier 1 side, and the cam follower 9 may be brought into contact with the cam 5 formed on the end surface of the driven gear 3. .

FIG. 4 shows another embodiment. As in the case shown in FIG. 3, the driven gear 5a of the transfer roller 2 meshes with the driven gear 3a of the image carrier 1 to be driven. There is. The drive gear 4a and the driven gears 3a and 5a.
It is a helical gear, and the inclination direction of each gear is
The driven gear 5a of the transfer roller 2 is inclined in the direction in which the axial force acts in the gear end surface direction (rightward in the drawing). The end surface of the driven gear 5a of the transfer roller 2 has a cam 1 inclined in the circumferential direction.
0, and the cam follower 9 is in contact with this.

According to this structure, the transfer roller 2 is rotated by being driven by the rotation of the image carrier 1. At this time, the transfer roller 2 is constantly driven by the axial force at the time of meshing of the helical gears. It is urged toward the end surface, but its movement is caused by the cam 10.
By being regulated by the cam follower 9, the transfer roller 2 is reciprocated in the axial direction by the height of the cam 10a in accordance with the rotation.

[0013]

According to the present invention, the peripheral speed of the contact portion between the image bearing member 1 and the transfer roller 2 is the same, and by reciprocating in the axial direction, the hollow character development is performed in the same manner as the conventional one. In addition to the prevention, it is possible to prevent the occurrence of a defect due to the extension of the transfer image on the transfer material and the slip in the rotation direction.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view of an image forming apparatus to which the apparatus of the present invention is applied.

FIG. 2 is a schematic configuration explanatory view showing a first embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a modification of the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a second embodiment of the present invention.

[Explanation of symbols]

1 ... Image carrier, 2 ... Transfer roller, 3, 3a, 5, 5a ...
Driven gears, 4, 6 ... Drive gears, 7, 8 ... Spring, 9 ... Cam followers, 10 ... Developing device, 11 ... Cleaning device, 12 ... Paper feeding device, 13 ... Fixing device.

Claims (2)

[Claims] 1. An image forming apparatus in which a toner image of the image carrier 1 is transferred to a transfer material passing between the image carrier 1 and the transfer roller 2 by elastic contact with the image carrier 1. An image forming apparatus characterized in that the transfer rollers 2 have the same peripheral speed, and the image carrier 1 and the transfer roller 2 are relatively reciprocally moved in the axial direction. 2. The transfer roller 2 is made movable in the axial direction, an axial biasing mechanism such as a spring 7 is provided on the transfer roller 2, and the cam 1 is provided on the end face portion of the transfer roller 2 on the axial biasing side.
2. The image forming apparatus according to claim 1, wherein 0 is provided and the cam follower 9 is brought into contact with the cam 10.