US-12619181-B2 - Fixing device

US12619181B2US 12619181 B2US12619181 B2US 12619181B2US-12619181-B2

Abstract

A fixing device includes a contact member contacting a belt in a nip. The contact member includes projections distributing on and outside the nip in a widthwise direction. When first region is outside the nip and second region is inside the first region, first ridge line is a line of an end portion, of a leading side of the projection, of which a length is longer in a conveyance direction and the length is LA, second ridge line is a line of the end portion of the outer side, of the leading side of the projection positioned on the outmost in the first region and the length is LB, average lengths of LA and LB of the projections along the conveyance direction are LA ave and LB ave , LB ave >LA ave is satisfied.

Inventors

MISA KAWASHIMA
Ikuo Nakamoto
Hiroki Kawai
Shohei Tsuzaki

Assignees

CANON KABUSHIKI KAISHA

Dates

Publication Date: 20260505
Application Date: 20250116
Priority Date: 20240229

Claims (16)

1 . A fixing device for fixing a toner image carried on a recording material to the recording material, the fixing device comprising: an endless and rotatable belt; a rotatable pressing member configured to contact an outer peripheral surface of the belt and form a nip portion for nipping and conveying the recording material between itself and the belt; and a contact member configured to contact an inner peripheral surface of the belt in the nip portion, wherein the inner peripheral surface of the belt slides with the contact member, wherein the contact member includes a plurality of projections provided on a side where the contact member slides with the belt and so as to project toward the inner peripheral surface of the belt, the plurality of the projections being distributed on the nip portion and outside the nip portion with respect to a widthwise direction of the recording material crossing a conveyance direction of the recording material, and wherein when in a region where the plurality of the projections of the contact member exist, a predetermined region outside the nip portion in the widthwise direction crossing the conveyance direction of the recording material is defined as a first region, and a region inside the first region in the widthwise direction and inside the nip portion is defined as a second region, of both end portions, in the widthwise direction, of a leading side surface of the projections in the second region, a line of the end portion of which a length is longer in the conveyance direction is defined as a first ridge line and the length of the first ridge line is defined as LA, a line of the end portion outside, in the widthwise direction, the leading side surface of the projection which is positioned on the outmost side with respect to the widthwise direction in the first region is defined as a second ridge line and the length of the second ridge line is defined as LB, of the plurality of the projections in the second region, an average length of the LA of the plurality of the projections in a line along the conveyance direction is defined as LA ave , and of the plurality of the projections in the first region, an average length of the LB of the plurality of the projections in a line along the conveyance direction is defined as LB ave , the following relationship is satisfied: LB ave >LA ave .
2 . The fixing device according to claim 1 , wherein the following relationship is satisfied: LB≥ 2 mm.
3 . The fixing device according to claim 1 , wherein the following relationship is satisfied: LB≤ 5 mm.
4 . The fixing device according to claim 1 , wherein the following relationship is satisfied: LA≥ 0.2 mm.
5 . The fixing device according to claim 1 , wherein the following relationship is satisfied: LA≤ 1 mm.
6 . The fixing device according to claim 1 , wherein the second ridge line is substantially parallel to the conveyance direction.
7 . The fixing device according to claim 1 , wherein the second ridge line is a line inclined to the conveyance direction.
8 . The fixing device according to claim 7 , wherein when an angle of the second ridge line to the conveyance direction is θ, the following relationship is satisfied: −15°≤θ≤15°.
9 . The fixing device according to claim 7 , wherein the contact member includes a sliding layer configured to cover a surface including the plurality of the projections and on a side where the contact member slides with the belt.
10 . The fixing device according to claim 1 , wherein the second ridge line is a curve, and when an inclined angle of a tangent line in the second ridge line to the conveyance direction is θ, the following relationship is satisfied: −15°≤θ≤15°.
11 . The fixing device according to claim 1 , wherein the contact member includes a base material layer formed of a metal.
12 . The fixing device according to claim 11 , wherein the plurality of the projections are provided toward the inner peripheral surface of the belt from the base material layer and are integrally formed with the base material layer.
13 . The fixing device according to claim 1 , wherein the pressing member is a pressing roller configured to press the belt toward the contact member.
14 . The fixing device according to claim 1 , further comprising a heating roller in contact with the inner peripheral surface of the belt, and a heat source configured to heat the heating roller.
15 . The fixing device according to claim 1 , wherein the leading side surface of the projection which is positioned on the outmost side with respect to the widthwise direction is a polygon.
16 . The fixing device according to claim 15 , wherein the leading side surface of the projections in the second region is a circle.

Description

FIELD OF THE INVENTION AND RELATED ART The present invention relates to a fixing device which fixes a toner image carried on a recording material to the recording material. As a fixing device, a configuration is conventionally known in which a nip portion for nipping and conveying is formed by a belt and a nip portion forming member such as a roller and the recording material passing through the nip portion is heated and pressed. In addition, in this configuration, by a sliding member being slid with an inner peripheral surface of the belt in the nip portion, the nip portion is formed between the belt and the nip portion forming member. In order to guarantee quality of an image to be fixed to the recording material, in the fixing device, it is required to suppress slippage between the recording material, which is conveyed by the nip portion, and the belt and between the recording material and the nip portion forming member. For this reason, it is required that frictional force between the belt and the sliding member is made to be less than these frictional force between the recording material and the belt and between the recording material and the nip portion forming member. In particular, in a configuration which includes a wide nip, in which a width of the nip portion is widened to increase heating efficiency, it is required that the frictional force between the belt and the sliding member is made to be less. For example, in Japanese Patent Application Laid-Open No. 2020-052354, a configuration, in which irregularities are formed on a sliding sheet, which slides with an inner peripheral surface of a belt in a nip portion to reduce frictional force between the sliding sheet and the belt, is disclosed. SUMMARY OF THE INVENTION According to an aspect of the present invention, there is provided a fixing device for fixing a toner image carried on a recording material to the recording material, the fixing device comprising: an endless and rotatable belt; a rotatable pressing member configured to contact an outer peripheral surface of the belt and form a nip portion for nipping and conveying the recording material between itself and the belt; and a contact member configured to contact an inner peripheral surface of the belt in the nip portion, wherein the inner peripheral surface of the belt slides with the contact member, wherein the contact member includes a plurality of projections provided on a side where the contact member slides with the belt and so as to project toward the inner peripheral surface of the belt, the plurality of the projections distributing on the nip portion and outside the nip portion with respect to a widthwise direction of the recording material crossing a conveyance direction of the recording material, and wherein when in a region where the plurality of the projections of the contact member exist, a predetermined region outside the nip portion in the widthwise direction crossing the conveyance direction of the recording material is defined as a first region, and a region inside the first region in the widthwise direction and inside the nip portion is defined as a second region, of both end portions, in the widthwise direction, of a leading side surface of the projections in the second region, a line of the end portion of which a length is longer in the conveyance direction is defined as a first ridge line and the length of the first ridge line is defined as LA, a line of the end portion outside, in the widthwise direction, the leading side surface of the projection which is positioned on the outmost side with respect to the widthwise direction in the first region is defined as a second ridge line and the length of the second ridge line is defined as LB, of the plurality of the projections in the second region, an average length of the LA of the plurality of the projections in a line along the conveyance direction is defined as LAave, and of the plurality of the projections in the first region, an average length of the LB of the plurality of the projections in a line along the conveyance direction is defined as LBave, the following relationship is satisfied: LBave>LAave. Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an outline configuration of an image forming apparatus according to an Embodiment 1. Part (a) of FIG. 2 is a cross-sectional view of an outline configuration of a fixing device according to the Embodiment 1, and part (b) of FIG. 2 is a schematic view illustrating an enlarged portion A in part (a). FIG. 3 includes a cross-sectional view in part (a) and a plan view in part (b), which schematically illustrate a sliding member according to the Embodiment 1. FIG. 4 is a cross-sectional view schematically illustrating relationship between the sliding member and a belt according to the Embodiment 1. F