FIXING DEVICE AND FIXING METHOD

Abstract

A fixing device includes a first heater provided at a central part of a roller body in a longitudinal direction thereof and a second heater provided at the end of the roller body in the longitudinal direction thereof. A single thermostat is provided at a position where the difference between the first temperature when only the first heater lights and the second temperature when only the second heater lights is set within a predetermined range.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the constitution of the fixing device relating to the first embodiment of the present invention;

FIG. 2 is a flow chart showing the temperature control operation of the fixing device relating to the first embodiment of the present invention;

FIG. 3 is a graph for explaining the temperature distribution between the central part and the end of the heat roller depending on the lighting condition of the heater;

FIG. 4 is a schematic view showing the constitution of the fixing device relating to the second embodiment of the present invention; and

FIG. 5 is a schematic view showing the constitution of the fixing device relating to the third embodiment of the present invention.

Claims

1. A fixing device comprising: a roller body;a first heater provided at a central part of the roller body in a longitudinal direction;a second heater provided at an end of the roller body in the longitudinal direction; anda single thermostat provided at a position where a difference between a first temperature when only the first heater acts and a second temperature when only the second heater acts is set within a predetermined range.

2. The fixing device according to claim 1, wherein the predetermined range is lower than 20° C.

3. The fixing device according to claim 1, wherein the thermostat is provided at a position where the first temperature and the second temperature coincide with each other.

4. The fixing device according to claim 1, wherein the first heater is a lamp and the second heater is a lamp.

5. The fixing device according to claim 1, wherein the second heater is a first and a second filament provided at both internal ends of one lamp.

6. The fixing device according to claim 1, wherein the first and the second heater are respectively exciting coils for executing electromagnetic induction heating.

7. A fixing device comprising: first heating means for heating a central part of a roller body in a longitudinal direction;second heating means for heating an end of the roller body in the longitudinal direction; andinterruption means, installed at a position where a difference between a first temperature when only the first heating means heats and a second temperature when only the second heating means heats is set within a predetermined range, for interrupting a power supply to each of the first and second heating means.

8. The fixing device according to claim 7, wherein the predetermined range is lower than 20° C.

9. The fixing device according to claim 7, wherein the interruption means is provided at a position where the first temperature and the second temperature coincide with each other.

10. The fixing device according to claim 7, wherein the interruption means is a thermostat.

11. The fixing device according to claim 7, wherein the first heating means is a lamp and the second heating means is a lamp.

12. The fixing device according to claim 7, Wherein the second heating means is a first and a second filament provided at both internal ends of one lamp.

13. The fixing device according to claim 7, wherein the first and the second heating means are respectively heating coils of an electromagnetic induction type.

14. A fixing method comprising: heating a central part of a roller body in a longitudinal direction;heating an end of the roller body in the longitudinal direction; andinterrupting heating of the central part and the end of the roller body by a single power supply interruption member provided at a position where a difference between a first temperature when the central part is heated and a second temperature when the end is heated is set within a predetermined range when the heating temperature of the roller body exceeds a predetermined temperature.

15. The fixing method according to claim 14, wherein the power supply interruption member is a thermostat.

16. The fixing method according to claim 14, wherein the heating the central part is a lamp and the heating the end is a lamp.

17. The fixing method according to claim 14, wherein the heating the end is a first and a second filament provided at both internal ends of one lamp.

18. The fixing method according to claim 14, wherein the heating the center and end in the longitudinal direction are respectively heating coils of an electromagnetic induction type.

19. The fixing method according to claim 14, wherein the predetermined range is lower than 20° C.

20. The fixing method according to claim 17, wherein the power supply interruption member is provided at a position where the first temperature and the second temperature coincide with each other.