Fixing device and image forming apparatus

Abstract
A fixing device for fixing a toner image onto a recording medium, includes: a belt member rotatably provided; a heating section that heats the belt member; a pressurization member, placed so as to be pressed against the belt member, that forms a nip portion to allow the recording medium to pass through between the pressurization member and the belt member; and an uniforming section that uniforms a temperature distribution in a longitudinal direction of the pressurization member.
Description

BRIEF DESCRIPTION OF THE DRAWINGS

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



FIG. 1 is a schematic configuration drawing to show an image formation apparatus of a first exemplary embodiment of the invention;



FIG. 2 is a sectional view to show the schematic configuration of a fixing device of the exemplary embodiment of the invention;



FIG. 3 is a schematic representation to show the form when the fixing device 60 is viewed from the right side;



FIGS. 4A to 4C are schematic representations to show change in the temperature distribution on the surface of a pressurization roll with a contact member and a heater;



FIGS. 5A to 5C are schematic representations to show a modified example of the contact member, etc., and change in the temperature distribution of the pressurization roll with the contact member;



FIG. 6 is a schematic representation to show the placement mode, etc., of the contact member in corner registration;



FIG. 7 is schematic configuration drawing to show a fixing device of a second exemplary embodiment of the invention;



FIG. 8 is a configuration drawing to show the periphery of a support member in FIG. 7;



FIG. 9 is a schematic drawing to describe the cross-sectional configuration of the fixing device;



FIG. 10 is a schematic representation to show details of a fixing belt; and



FIGS. 11A and 11B are schematic representations to show in detail the periphery of a pressurization roll when the pressurization roll terminally expands.


Claims
  • 1. A fixing device for fixing a toner image onto a recording medium, the fixing device comprising: a belt member rotatably provided;a heating section that heats the belt member;a pressurization member, placed so as to be pressed against the belt member, that forms a nip portion to allow the recording medium to pass through between the pressurization member and the belt member; andan uniforming section that uniforms a temperature distribution in a longitudinal direction of the pressurization member.
  • 2. The fixing device as claimed in claim 1, wherein the uniforming section comprises a contact member that comes in contact with at least a part of the pressurization member, andthe contact member heats or cools the pressurization member in a contact place with the pressurization member.
  • 3. The fixing device as claimed in claim 2, wherein the contact place where the contact member comes in contact with the part of the pressurization member is a first area through which a recording medium having a narrower width than the maximum paper passage width is to pass.
  • 4. The fixing device as claimed in claim 3, wherein the contact member is a roll-like member, anda first outer diameter in the first area of the contact member is formed larger than a second outer diameter in a second area which is any other area than the first area of the contact member.
  • 5. The fixing device as claimed in claim 2, wherein the contact place where the contact member comes in contact with the part of the pressurization member is a second area which is any other area than a first area through which a recording medium having a narrower width than the maximum paper passage width is to pass.
  • 6. The fixing device as claimed in claim 5, wherein the contact member is a roll-like member, andwherein a first outer diameter in the first area of the contact member is formed smaller than a second outer diameter in the second area of the contact member.
  • 7. The fixing device as claimed in claim 2, wherein the uniforming section further comprises a cooling section that cools a surface of the contact member.
  • 8. The fixing device as claimed in claim 2, wherein the contact member comprises a heating section that heats the pressurization member.
  • 9. The fixing device as claimed in claim 2, wherein the uniforming section further comprises a cooling section that cools a surface of the contact member,the contact member comprises a heating section that heats the pressurization member, andthe fixing device further comprises a switch section that switches between a heating state of the heating section and a cooling state of the cooling section in response to a size of the recording medium.
  • 10. The fixing device as claimed in claim 2 further comprising a move section that brings the contact member in contact with the pressurization member away from the pressurization member.
  • 11. The fixing device as claimed in claim 2, wherein the pressurization member comprises an elastic layer for becoming deformed in the nip portion.
  • 12. A fixing device for fixing a toner image onto a recording medium, the fixing device comprising: a belt member rotatably provided;a heating section used that heats the belt member;a pressurization member, placed so as to be pressed against the belt member, that forms a nip portion to allow the recording medium to pass through between the pressurization member and the belt member; anda cooling member, placed at a distance from the pressurization member, that comes in contact with the pressurization member when the pressurization member thermally expands so as to cool the pressurization member.
  • 13. The fixing device as claimed in claim 12, wherein a place where the cooling member comes in contact with the pressurization member when the pressurization member thermally expands is a second area which is any other area than a first area through which a recording medium having a narrower width than the maximum paper passage width is to pass.
  • 14. The fixing device as claimed in claim 12, wherein the pressurization member has, in its longitudinal direction, a first area through which a small-size recording medium having a narrower width than the maximum recording medium passage width is to pass and a second area other than the first area,and wherein the following expression is satisfied: 0<Eta<A≦Etbwhere A represents a distance between a surface of the pressurization member and a surface of the cooling member, Eta represents a thermal expansion amount of the pressurization member in the first area when the small-size recording medium is continuously passed through, and Etb represents a thermal expansion amount of the pressurization member in the second area when the small-size recording medium is continuously passed through.
  • 15. The fixing device as claimed in claim 12, wherein the cooling member has a thermal conductivity for allowing heat to be easily transmitted in a longitudinal direction of the cooling member.
  • 16. The fixing device as claimed in claim 15, wherein the cooling member is a heat pipe.
  • 17. The fixing device as claimed in claim 15, wherein the cooling member is an aluminum roll.
  • 18. The fixing device as claimed in claim 12, wherein the heating section that heats the belt member comprises a single heating source.
  • 19. An image forming apparatus comprising: an image forming device that forms a toner image on an image carrier;a transfer device that transfers the toner image onto a recording medium; anda fixing device that fixes the toner image onto the recording medium, the fixing device comprising:a belt member rotatably provided;a heating section that heats the belt member;a pressurization member, placed so as to be pressed against the belt member, that forms a nip portion to allow the recording medium to pass through between the pressurization member and the belt member; andan uniforming section that uniforms a temperature distribution in a longitudinal direction of the pressurization member.
  • 20. An image forming apparatus comprising: an image forming device that forms a toner image on an image carrier;a transfer device that transfers the toner image onto a recording medium; anda fixing device that fixes the toner image onto the recording medium, the fixing device comprising: a belt member rotatably provided;a heating section used that heats the belt member;a pressurization member, placed so as to be pressed against the belt member, that forms a nip portion to allow the recording medium to pass through between the pressurization member and the belt member; anda cooling member, placed at a distance from the pressurization member, that comes in contact with the pressurization member when the pressurization member thermally expands so as to cool the pressurization member.
Priority Claims (1)
Number Date Country Kind
P2006-008859 Jan 2006 JP national