Image formation device

Abstract

An image formation device includes an image-bearing body that rotates, a charging roller that contacts the image-bearing body and is rotated by the rotation of the image-bearing body, and charges the image-bearing body, a cleaning roller that contacts the charging roller and is rotated by the rotation of the charging roller, and cleans the charging roller, and a first auxiliary roller that is provided coaxially with the charging roller, contacts the image-bearing body and is rotated by the rotation of the image-bearing body. The image formation device satisfies the following relation:

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described in detail based on the following figures, in which:

FIG. 1 is a structural view showing general structure of an image formation device according to an embodiment of the present invention;

FIG. 2 is an enlarged view showing structure of a photosensitive drum, a charging roller and a cleaning roller which are installed in the image formation device of FIG. 1;

FIG. 3 is a partial sectional side view showing structure of the photosensitive drum, the charging roller, the cleaning roller, auxiliary rollers and a holder according to the embodiment of the present invention;

FIG. 4 is a perspective view showing a state in which the charging roller and the cleaning roller according to the embodiment of the present invention are axially supported at a bearing member;

FIG. 5 is a partial sectional side view showing the state in which the charging roller and the cleaning roller according to the embodiment of the present invention are axially supported at the bearing member; and

FIG. 6 is an enlarged view, corresponding with FIG. 3, showing mounting positions of the auxiliary rollers according to the embodiment of the present invention.

Claims

1. An image formation device comprising: an image-bearing body that rotates;a charging roller that contacts the image-bearing body and is rotated by the rotation of the image-bearing body, and charges the image-bearing body;a cleaning roller that contacts the charging roller and is rotated by the rotation of the charging roller, and cleans the charging roller; anda first auxiliary roller that is provided coaxially with the charging roller, contacts the image-bearing body and is rotated by the rotation of the image-bearing body,wherein the image formation device satisfies the following relation: F1>F2>F3

2. The image formation device of claim 1, further comprising a second auxiliary roller that is provided coaxially with the cleaning roller, contacts the first auxiliary roller and is rotated by the rotation of the first auxiliary roller, wherein the image formation device satisfies the following relation: F1>F4>F2>F3where F1 represents a friction force between the first auxiliary roller and the image-bearing body, F4 represents a friction force between the first auxiliary roller and the second auxiliary roller, F2 represents a friction force between the image-bearing body and the charging roller and F3 represents a friction force between the charging roller and the cleaning roller.

3. The image formation device of claim 1, wherein the device satisfies the following relation: R1>R2where R1 represents a resilient force of a surface of the charging roller and R2 represents a resilient force of a surface of the first auxiliary roller.

4. The image formation device of claim 2, wherein the device satisfies the following relation: R1>R2

5. The image formation device of claim 1, wherein the device satisfies the following relation: D1≧D2

6. The image formation device of claim 2, wherein the device satisfies the following relation: D1≧D2

7. The image formation device of claim 3, wherein the device satisfies the following relation: D1≧D2

8. The image formation device of claim 2, wherein the device satisfies the following relation: D3≧D4

9. The image formation device of claim 1, wherein the first auxiliary roller is disposed outside an image formation region of the image-bearing body.

10. The image formation device of claim 2, wherein the first auxiliary roller is disposed outside an image formation region of the image-bearing body.

11. The image formation device of claim 3, wherein the first auxiliary roller is disposed outside an image formation region of the image-bearing body.

12. The image formation device of claim 5, wherein the first auxiliary roller is disposed outside an image formation region of the image-bearing body.

13. The image formation device of claim 8, wherein the first auxiliary roller is disposed outside an image formation region of the image-bearing body.