Heating unit for an image forming apparatus

Patent metadata

Field	Value
Publication number	US-11822271-B2
Application number	US-202217575849-A
Country	US
Kind code	B2
Filing date	Jan 14, 2022
Priority date	Jan 15, 2021
Publication date	Nov 21, 2023
Grant date	Nov 21, 2023

Abstract

A heating unit includes a heater including a substrate and a resistance heating element, a temperature sensor, an endless belt, a holder, a first heat conductive sheet located between the heater and the holder, and a second heat conductive sheet which is smaller than the first heat conductive heat member. The first heat conductive sheet includes a first heater-side surface which is in contact with a back surface of the heater and a first opposite surface. The first heat conductive sheet has a heat conductivity higher than that of the substrate. The second heat conductive sheet includes a second heater-side surface which is in contact with the first opposite surface and a second opposite surface. The temperature sensor is in contact with the second opposite surface of the second heat conductive sheet.

First claim

What is claimed is:

1. A heating unit for an image forming apparatus, comprising:
a heater including a substrate and a resistance heating element provided on the substrate;
a temperature sensor configured to detect a temperature of the heater;
an endless belt configured to rotate around the heater;
a holder supporting the heater;
a first heat conductive member located between the heater and the holder, the first heat conductive member including a first heater-side surface, which is in contact with a back surface of the heater, and a first opposite surface located opposite to the first heater-side surface, the first heat conductive member having a heat conductivity that is higher than that of the substrate, the first heat conductive member being a graphite sheet; and
a second heat conductive member, which has a sheet shape and which is smaller than the first heat conductive heat member when viewed in an orthogonal direction orthogonal to the first opposite surface, the second heat conductive member including a second heater-side surface, which is in surface contact with the first opposite surface, and a second opposite surface located opposite to the second heater-side surface and parallel with respect to the second heat-side surface, the second heat conductive member having a heat conductivity higher than that of the substrate, the second conductive heat member being made of aluminum or an aluminum alloy, and
wherein the temperature sensor is in surface contact with the second opposite surface of the second heat conductive member.

2. The heating unit for an image forming apparatus according to claim 1 , wherein a length of the first heat conductive member in a longitudinal direction of the heater is longer than a length of the resistance heating element.

3. The heating unit for an image forming apparatus according to claim 1 , wherein, when viewed in the orthogonal direction orthogonal to the first opposite surface, a dimension of the second heat conductive member in a longitudinal direction of the heater is equal to or less than twice a dimension of a contact portion of the second opposite surface in the longitudinal direction, the contact portion being a portion of the second opposite surface with which the temperature sensor is in contact, and wherein, when viewed in the orthogonal direction, a dimension of the second heat conductive member in a short-side direction orthogonal to the orthogonal direction and the longitudinal direction is equal to or less than twice a dimension of the contact portion of the second opposite surface in the short-side direction.

4. The heating unit for an image forming apparatus according to claim 1 , wherein the temperature sensor is configured to detect the temperature at a position, in the longitudinal direction of the heater, in a range in which a recording medium with a maximum width usable in the heating unit passes and out of a range in which a recording medium with a minimum width usable in the heating unit passes.

5. The heating unit for an image forming apparatus according to claim 1 , wherein the temperature sensor is configured to detect the temperature at a position, in the longitudinal direction of the heater, in a range in which a recording medium with a minimum width usable in the heating unit passes.

6. The heating unit for an image forming apparatus according to claim 1 , wherein the first heat conductive member is an anisotropic heat conductive member in which a heat conductivity in a direction parallel to the first heater-side surface is higher than a heat conductivity in a direction orthogonal to the first heater-side surface.

7. The heating unit for an image forming apparatus according to claim 1 , wherein the temperature sensor includes a first protruding portion, and
wherein the second heat conductive member is positioned with respect to the temperature sensor by engaging with the first protruding portion.

8. The heating unit for an image forming apparatus according to claim 1 , wherein the second heat conductive member includes a second protruding portion, and
wherein the second protruding portion engages with the temperature sensor.

9. The heating unit for an image forming apparatus according to claim 1 , wherein a first member, which is one of the first heat conductive member and the second heat conductive member, includes a protrusion, and a second member, which is the other one of the first heat conductive member and the second heat conductive member, includes a recess with which the protrusion engages.

10. The heating unit for an image forming apparatus according to claim 1 , wherein the temperature sensor is a thermistor, or a thermostat configured to interrupt energization to the resistance heating element when the heater is abnormally increased in temperature.

11. A heating unit for an image forming apparatus, comprising: a heater including a substrate and two resistance heating elements provided on the substrate; a temperature sensor configured to detect a temperature of the heater; an endless belt configured to rotate around the heater; a holder supporting the heater; a first heat conductive member located between the heater and the holder, the first heat conductive member including a first heater-side surface, which is in contact with a back surface of the heater and a first opposite surface located opposite to the first heater-side surface, the first heat conductive member having a heat conductivity that is higher than that of the substrate; and a second heat conductive member, which has a sheet shape and which is smaller than the first heat conductive heat member when viewed in an orthogonal direction orthogonal to the first opposite surface, the second heat conductive member including a second heater-side surface, which is in surface contact with the first opposite surface, and a second opposite surface located opposite to the second heater-side surface and parallel with respect to the second heat side surface, the second heat conductive member having a heat conductivity higher than that of the substrate, wherein the temperature sensor is in contact with the second opposite surface of the second heat conductive member, wherein, when viewed in the orthogonal direction, a dimension of the first heat conductive member in a short-side direction orthogonal to the orthogonal direction and a longitudinal direction of the heater is larger than a range in the short-side direction in which the two resistance heating elements are disposed, and wherein, when viewed in the orthogonal direction, the second heat conductive member is located between the two resistance heating elements in the short-side direction.

12. The heating unit for an image forming apparatus according to claim 11 , wherein a length of the first heat conductive member in the longitudinal direction of the heater is longer than a length of the resistance heating element.

13. The heating unit for an image forming apparatus according to claim 11 , wherein, when viewed in the orthogonal direction, a dimension of the second heat conductive member in the longitudinal direction of the heater is equal to or less than twice a dimension of a contact portion of the second opposite surface in the longitudinal direction, the contact portion being a portion of the second opposite surface with which the temperature sensor is in contact, and
wherein, when viewed in the orthogonal direction, a dimension of the second heat conductive member in the short-side direction is equal to or less than twice a dimension of the contact portion of the second opposite surface in the short-side direction.

14. The heating unit for an image forming appa

Assignees

• Brother Ind Ltd

Inventors

• Maruyama Yasuhiro

Classifications

• G03G15/2053 Primary

  Structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating · CPC title

• G03G2215/2035

  the fixing nip having a stationary belt support member opposing a pressure member · CPC title