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Image heating apparatus and heater

Imported: 23 Feb '17 | Published: 22 Oct '02

Yasumasa Ohtsuka

USPTO - Utility Patents

Abstract

An image heating device includes a heater; a film having a surface in slidable contact with said heater and an opposite surface contactable to a recording material carrying an image; wherein the image on the recording material is heated by heat from said heater through said film; wherein said heater includes an elongated base material, a plurality of resistor extended in a longitudinal direction on said base material, and a temperature detecting element provided on said base material: wherein a resistance of a first portion of said resistor which is opposed to said temperature detecting element in the longitudinal direction of said resistor, has a resistance value higher than that in said second portion.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic section of an image forming apparatus to which the present invention is applicable.

FIG. 2 is a schematic section of a fixing apparatus.

FIG. 3 is an enlarged section of the adjacencies of a heating member.

FIG. 4 is an enlarged schematic section of the adjacencies of the heating member as seen from the direction in which a film is moved.

FIG. 5 is a plan view of the heating member.

FIG. 6 is a graph depicting the heat distribution of the heating member.

FIG. 7 is a plan view of a copy sheet, which depicts irregularity in glossiness.

FIG. 8 is an enlarged view of a part of the heating member, in which a part of one of two patterned heat generating resistors is narrowed.

FIG. 9 is an enlarged section of the adjacencies of the heating member.

FIG. 10 is a graph depicting the widthwise heat distribution of the heating member.

FIG. 11 is an enlarged view of a part of the heating member, in which a part of one of the two patterned heat generating resistors is narrowed.

FIG. 12 is an enlarged view of the part of the heating member, in which a part of one of the two patterned heat generating resistors is narrowed.

FIG. 13 is an enlarged view of the part of the heating member, in which a part of one of the two patterned heat generating resistors is narrowed.

FIG. 14 is an enlarged view of the part of the heating member, in which a part of one of the two patterned heat generating resistors is narrowed.

FIG. 15 is a graph depicting the widthwise heat distribution of the heating member.

FIG. 16, which includes

16(

a), (

b) and (

c), is an enlarged view of the part of the heating member, in which a part of one the two patterned heat generating resistors is narrowed

FIG. 17 is an enlarged view of the part of the heating member, in which a part of each of the two patterned heat generating resistors is narrowed.

FIG. 18 is a graph depicting the widthwise heat distribution of the heating member.

FIG. 19, which includes

19(

a), (

b) and (

c), is a schematic section of another fixing apparatus to which the present invention is applicable,

FIG.

20(

a) is an enlarged section of the adjacencies of the heating member, and

FIG.

20(

b) is a plan view of the heating member.

Claims

1. An image heating apparatus comprising:

2. An apparatus according to claim 1, wherein each of said resistors has a first portion disposed at a position corresponding in the longitudinal direction to said temperature detecting element and a second portion disposed in a position not corresponding thereto, and a width of said first portion measured in the longitudinal direction is smaller than that of said second portion.

3. An apparatus according to claim 1, wherein two of such resistors are provided, and only one of them has said first portion.

4. An apparatus according to claim 1, wherein two of such resistors are provided, and a gap between said the resistors, measured in the direction perpendicular to the longitudinal direction, is larger at said first portion than at said second portion.

5. An apparatus according to claim 4, wherein only one of said resistors has said first portion.

6. An apparatus according to claim 4, wherein each of said resistors has said first portion.

7. An apparatus according to claim 6, wherein said temperature detecting element is provided between said resistors.

8. An apparatus according to claim 1, wherein said first portion has a portion not having the resistor within the width thereof.

9. An apparatus according to claim 8, wherein two of such resistors are provided, and the portion not having said resistor is provided in each of said resistors.

10. An apparatus according to claim 8, wherein the portion not having said resistor is in the form of a slit.

11. An apparatus according to claim 1, wherein said temperature detecting element is provided on a side of said base member not having said resistor.

12. An apparatus according to claim 1, wherein said resistor generates heat upon electric energy supply thereto, and said temperature detecting element is a safety element for shutting-off of the electric energy supply to said resistor.

13. An apparatus according to claim 1, wherein two of such resistors are provided, and one longitudinal end portion of them is provided with an electroconductive portion for electrical connection of respective resistors, and the other longitudinal end portion is provided with an electrode portion.

14. An apparatus according to claim 1, wherein the longitudinal direction of said heater is perpendicular to a movement direction of said film.

15. An apparatus according to claim 1, further comprising a back-up member for forming a nip with said heater with said film therebetween, and the recording material is passed through the nip, by which the unfixed image is fixed.

16. A heater comprising:

17. A heater according to claim 16, wherein each of said resistors has the first portion disposed at a position corresponding in the longitudinal direction to said temperature detecting element and a second portion not corresponding thereto, and a width of said first portion measured in the longitudinal direction is smaller than that of said second portion.

18. A heater according to claim 16, wherein two of such resistors are provided, and only one of them has said first portion.

19. A heater according to claim 16, wherein two of such resistors are provided, and a gap between said the resistors, measured in the direction perpendicular to the longitudinal direction, is larger at said first portion than at said second portion.

20. A heater according to claim 19, wherein only one of said resistors has said first portion.

21. A heater according to claim 19, wherein each of said resistors has said first portion.

22. A heater according to claim 21, wherein said temperature detecting element is provided between said resistors.

23. A heater according to claim 16, wherein said first portion has a zigzag configuration.

24. A heater according to claim 16, wherein said first portion has a portion not having the resistor within the width thereof.

25. A heater according to claim 24, wherein two of such resistors a provided, and the portion not having said resistor is provided in each of said resistors.

26. A heater according to claim 24, wherein the portion not having said resistor is in the form of a slit.

27. A heater according to claim 16, wherein said temperature detecting element is provided on a side of said base member not having said resistor.

28. A heater according to claim 16, wherein said resistor generates heat upon electric energy supply thereto, and said temperature detecting element is a safety element for shutting-off of the electric energy supply to said resistor.

29. A heater according to claim 16, wherein two of such resistors are provided, and one longitudinal end portion of them is provided with an electroconductive portion for electrical connection of respective resistors, and the other longitudinal end portion of each of them is provided with an electrode portion.

30. A heater comprising:

31. A heater according to claim 30, wherein a width of each high resistance portion measured in a direction perpendicular to a longitudinal direction of said heater, is smaller than a width of the adjacent portion.

32. A heater according to claim 30, wherein an entire resistor comprising said first and second resistors has a uniform width, in the longitudinal direction.

33. A heater according to claim 32, wherein a distance between said first and second resistors at said high resistance portions is larger than a distance between them at the adjacent portion.

34. A heater according to claim 32, wherein each of said first and second resistors has a slit at said high resistance portion.

35. A heater according to claim 30, wherein said electrodes are provided only at one end portion of said base member, said heater further comprising a conducting portion for electric connection between said first and second resistors at the other end portion.

36. An image heating apparatus comprising:

37. An apparatus according to claim 36, further comprising a temperature detecting element, contacted to said base member, for detecting a temperature, wherein said temperature detecting element is provided at the same position as the high resistance portions, in the longitudinal direction of said resistors.

38. An apparatus according to claim 37, wherein said temperature detecting element is a safety element for shutting electric energy supply to said resistor.