Asymmetric Pivot Axis for Belt Driving Device Tension Control
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Solution Overview
Problem
Existing fixing devices with endless belts in image forming apparatuses face issues with belt stretching and uneven heating, leading to potential slack and temperature irregularities, which affect the fixation of toner images on sheets.
Innovation Solution
A belt driving device with a control member that pivots about a pivot axis positioned off-center relative to the endless belt's width direction, supported by a driving mechanism, ensures that the moving distances of the belt's edges are closer together, preventing stretching and maintaining uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pivot axis is located at the midpoint of the endless belt in the width direction, then the control member can be driven symmetrically, but the moving distances of two points on the control member aligned with the edges of the endless belt are farther apart, causing belt stretching and slack
Solution Approach 1:
The pivot axis is intentionally positioned asymmetrically shifted toward the driving mechanism side rather than at the midpoint. This asymmetric positioning causes the two points on the control member aligned with the belt edges to have closer moving distances, which prevents the belt from stretching and eliminates slack, thereby resolving the reliability issue while maintaining operational functionality
2Ease of operation
If the pivot axis is located at the midpoint of the endless belt, then the control member pivots centrally, but this causes uneven heating and temperature irregularities on the belt
Solution Approach 1:
By shifting the pivot axis position asymmetrically toward the driving mechanism side, the heating distribution on the belt is optimized. This asymmetric positioning ensures more uniform heat distribution across the belt width, preventing temperature irregularities that would occur with central pivoting, thereby improving the overall thermal performance of the system
3Device complexity
If the control member is supported in a pivotable manner with pivot axis at midpoint, then the structure is simple and symmetrical, but it cannot prevent belt stretching and maintain uniform tension
Solution Approach 1:
The invention introduces a simple asymmetric positioning of the pivot axis toward the driving mechanism side. This minimal structural modification effectively reduces the moving distance difference between the two edges of the belt, preventing belt stretching and maintaining uniform tension distribution without adding complex mechanisms, thereby resolving the reliability issue while keeping the structure relatively simple
Data Source
AI summary
A belt driving device includes an endless belt; support members that extend in a width direction of the endless belt and support the endless belt, the support members including a control member that controls the widthwise position of the endless belt; a support body that supports the support members; and a driving mechanism that drives one end of the control member to cause the control member to pivot about a pivot axis in a direction in which stretching of the endless belt is prevented. A portion of the control member shifted from the midpoint toward an edge of the endless belt is pivotably supported by the support member to serve as the pivot axis, so that the moving distances of two points on the control member aligned with the edges of the endless belt when the control member is driven by the driving mechanism are close to each other.