Heating Unit Positioning via Bearing Engagement
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Solution Overview
Problem
Conventional fixing devices experience tilting of the heating unit with respect to the pressure roller due to thermal deformation, leading to sheet wrinkling during the thermal fixing process.
Innovation Solution
The fixing device incorporates a heating unit, a rotatable body, an urging mechanism, first and second bearings, and positioning members to securely position the heating unit relative to the pressure roller, preventing tilting through engagement with the bearings and maintaining alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the heating unit is supported by the frame with second wall portions, then the heating unit can be positioned in the sheet conveyance direction, but thermal deformation causes clearance increase and positioning displacement
Solution Approach 1:
The positioning function is segmented into two independent systems: the second wall portions provide movable support for adjustment, while the bearings and positioning members provide precise location fixing. This segmentation allows each component to perform its specialized function without interference from thermal deformation of the other.
Solution Approach 2:
The bearings act as intermediary elements between the heating unit and the frame's second wall portions. The positioning members extend from the heating unit to engage with the bearings, creating an intermediary positioning mechanism that isolates the heating unit from direct contact with thermally deforming frame portions.
2Ease of operation
If the heating unit is allowed to move toward and away from the pressure roller, then the urging mechanism can function, but thermal deformation causes tilting of the heating unit
Solution Approach 1:
The support structure is segmented into movable support functions (second wall portions allowing movement) and stable positioning functions (bearings and positioning members preventing tilting). This allows the heating unit to move axially while maintaining lateral alignment stability despite thermal deformation.
Solution Approach 2:
Different portions of the support structure have different properties: the second wall portions provide flexible movable support, while the bearing-mounted positioning members provide rigid positional stability. This local differentiation of support characteristics enables both movability and alignment stability.
Data Source
AI summary
A fixing device includes: a heating unit; a rotatable body; an urging mechanism; first and second bearings; a frame; first and second positioning members. The first and second bearings support first and second axial end portions of the rotatable body, respectively. The frame supports the heating unit and has two side walls. One of the side walls supports the first bearing, and the other supports the second bearing. Each side wall includes: a first wall portion supporting the first or second bearing; and second and third wall portions supporting the heating unit while interposing the heating unit therebetween. The first and second positioning members extend from the heating unit toward the first and second bearings, respectively. The heating unit is fixed in position relative to the first and second bearings upon engagement of the first and second positioning members with the first and second bearings, respectively.