Image forming apparatus

Abstract

An image forming apparatus includes a plurality of rotors, and an endless belt that is supported with tension by the plurality of rotors and rotated by the rotors. Herein, at least one of the plurality of rotors is provided, at a first end, with a belt restraining member that has a restraining face for restraining displacement of the endless belt toward the first end and that is rotatable with respect to the rotor; and the belt restraining member is arranged such that an angle between the restraining face of the belt restraining member and a rotation shaft of the rotor is greater at a contact start point at which the endless belt begins contact with the belt restraining member during rotation than at a contact end point at which the endless belt ends contact with the belt restraining member during rotation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a structure of an image forming apparatus in accordance with an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a fixing device provided with an endless fixing belt in accordance with the embodiment;

FIG. 3 is a side cross-sectional view to be referred to by the description of the structure and operation of a belt restraining member of the fixing device in accordance with the embodiment;

FIG. 4 is A-A cross-sectional view in accordance with FIG. 3;

FIGS. 5 a and 5b are C-C cross-sectional views in accordance with FIG. 4; and

FIG. 6 is a diagram showing an example of a fixing device in a prior art having a structure for restraining deviation of a fixing belt.

Claims

1. An image forming apparatus, comprising: a plurality of rotors; andan endless belt that is supported with tension by the rotors and that is rotated by the rotors,wherein at least one of the plurality of rotors is provided at a first end with a belt restraining member that has a restraining face for restraining displacement of the endless belt toward the first end and that is smoothly rotatable with respect to the rotor; andwherein the belt restraining member is arranged such that an angle between the restraining face of the belt restraining member and a rotation shaft of the rotor is greater at a contact start point at which the endless belt begins contact with the belt restraining member during rotation than at a contact end point at which the endless belt ends contact with the belt restraining member during rotation.

2. The image forming apparatus of claim 1, further comprising: an angle adjusting member for adjusting an angle of the restraining face of the restraining member with respect to the rotation shaft of the rotor.

3. The image forming apparatus of claim 2, wherein the angle adjusting member includes a contact section contactable with a face, of the belt restraining member, opposite to the restraining face; andthe contact section is formed such that the restraining face of the belt restraining member is inclined from a direction orthogonal to the rotation shaft, the belt restraining member being in contact with the contact section due to a pushing force from the endless belt.

4. The image forming apparatus of claim 1, wherein the belt restraining member is arranged such that the angle between the restraining face and the rotation shaft of the rotor becomes a maximum at the contact start point at which the endless belt begins contact with the belt restraining member during rotation.

5. The image forming apparatus of claim 1, wherein the belt restraining member is arranged such that the angle between the restraining face and a direction orthogonal to the rotation shaft of the rotor is in a range from 1 degree to 2 degrees at the contact start point at which the endless belt begins contact with the belt restraining member during rotation.

6. The image forming apparatus of claim 1 further comprising the belt restraining member provided at a second end being an another end to the first end of the rotor.

7. The image forming apparatus of claim 1, wherein the endless belt comprises a fixing belt.

8. The image forming apparatus of claim 1, wherein the endless belt comprises an intermediate transfer belt.

9. The image forming apparatus of claim 1, wherein the endless belt comprises a recording medium conveying belt.

10. The image forming apparatus of claim 1, wherein the endless belt comprises a photoreceptor belt.