FIXING DEVICE AND IMAGE FORMING APPARATUS

• US 20080013995A1
• Filed: 07/11/2007
• Published: 01/17/2008
• Est. Priority Date: 07/12/2006
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: KUBOTA, Keisuke, Suzuki, Takashi, Mitsuya, Teruaki, Sonohara, Yoshihiro
• Granted Patent: US 7,548,718 B2
• Time in Patent Office: Days
• US Class Current: 399/333
• CPC Class Codes: G03G 15/2042 specially for the axial heat partition

Abstract

A fixing device, which fixes an unfixed toner image on a recording medium, includes a heating roller, a fixing roller, a pressurizing roller, and an endless belt that stretches over the heating roller and the fixing roller. A heat source and a heat pipe are arranged in a heating roller. The heat pipe substantially uniformly heats the surface of the heating roller.

Claims

1. A fixing device that fixes an unfixed toner image on a recording medium, the fixing device comprising:

a fixing roller;

a pressurizing roller that opposes the fixing roller;

a heating roller that includes

a heating unit that is arranged in the heating roller and that heats the heating roller; and

a heat pipe that is arranged in the heating roller and near a surface of the heating roller and that substantially uniformly heats the surface; and

an endless fixing belt that stretches over the heating roller and the fixing roller and that conveys a recording medium with an unfixed toner image in a nip portion between the fixing roller and the pressurizing roller.

2. The fixing device according to claim 1, wherein the heating unit is elongated and arranged parallel to a rotation axis of the heating roller and has a uniform radiant flux along the rotation axis.

3. The fixing device according to claim 1, further comprising a temperature detecting unit that detects a temperature of the endless fixing belt stretched over the heating roller, wherein

the heating unit controls heating of the heating roller based on the temperature detected by the temperature detecting unit.

4. The fixing device according to claim 1, wherein the fixing belt includes a base layer and a rubber layer that serves as a heat storage layer and that is made of a material different from a material of the base layer, the rubber layer having a large heat capacity and conducting a large amount of heat.

5. The fixing device according to claim 4, wherein the rubber layer has a thermal conductivity λ

(W/m·

K) that satisfies 0.18≦

λ

≦

0.3.

6. The fixing device according to claim 4, wherein the rubber layer is made of silicone rubber.

7. The fixing device according to claim 6, wherein the rubber layer has a thickness L1 (μ

m) that satisfies 100≦

L1≦

400.

8. The fixing device according to claim 4, wherein the rubber layer includes a first layer and a second layer, the first layer being laid on the base layer and being made of silicone rubber, and the second layer being laid on the first layer and being made of fluorine rubber.

9. The fixing device according to claim 8, wherein the second layer has a thickness L2 (μ

m) that satisfies 20≦

L2≦

100.

10. The fixing device according to claim 9, wherein the first layer has a thickness L1 (μ

m) that satisfies 100≦

L1≦

400.

11. An image forming apparatus that includes a fixing device that fixes an unfixed toner image on a recording medium, the fixing device comprising:

a fixing roller;

a pressurizing roller that opposes the fixing roller;

a heating roller that includes

a heating unit that is arranged in the heating roller and that heats the heating roller; and

a heat pipe that is arranged in the heating roller and near a surface of the heating roller and that substantially uniformly heats the surface; and

an endless fixing belt that stretches over the heating roller and the fixing roller and that conveys a recording medium with an unfixed toner image in a nip portion between the fixing roller and the pressurizing roller.

12. The image forming apparatus according to claim 11, wherein the heating unit is elongated and arranged parallel to a rotation axis of the heating roller and has a uniform radiant flux along the rotation axis.

13. The image forming apparatus according to claim 11, further comprising a temperature detecting unit that detects a temperature of the endless fixing belt stretched over the heating roller, wherein

the heating unit controls heating of the heating roller based on the temperature detected by the temperature detecting unit.

14. The image forming apparatus according to claim 11, wherein the fixing belt includes a base layer and a rubber layer that serves as a heat storage layer and that is made of a material different from a material of the base layer, the rubber layer having a large heat capacity and conducting a large amount of heat.

15. The image forming apparatus according to claim 14, wherein the rubber layer has a thermal conductivity λ

(W/m·

K) that satisfies 0.18≦

λ

≦

0.3.

16. The image forming apparatus according to claim 14, wherein the rubber layer is made of silicone rubber.

17. The image forming apparatus according to claim 16, wherein the rubber layer has a thickness L1 (μ

m) that satisfies 100≦

L1≦

400.

18. The image forming apparatus according to claim 14, wherein the rubber layer includes a first layer and a second layer, the first layer being laid on the base layer and being made of silicone rubber, and the second layer being laid on the first layer and being made of fluorine rubber.

19. The image forming apparatus according to claim 18, wherein the second layer has a thickness L2 (λ

m) that satisfies 20≦

L2≦

100.

20. The image forming apparatus according to claim 19, wherein the first layer has a thickness L1 (μ

m) that satisfies 100≦

L1≦

400.