Roll Protruding Part Prevents Gap Discharge
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Solution Overview
Problem
Existing roll designs for image forming apparatuses experience discharge issues due to gaps forming between the annular member and the elastic layer over time, leading to secondary failures such as ignition of the elastic material.
Innovation Solution
A roll design featuring an electrically-conductive shaft with an elastic layer and a non-electrically-conductive annular unit attached to the shaft ends, where a protruding part with a smaller thickness cuts into the elastic layer's end surface, preventing gap formation and discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional annular member is attached to the shaft end without a protruding part, then the structure is simpler and easier to manufacture, but gaps form between the annular member and elastic layer over time causing discharge
Solution Approach 1:
The protruding part is designed to cut into the elastic layer during assembly, creating a preliminary mechanical interlock that prevents gap formation. This preliminary action of cutting into the elastic layer ensures continuous contact between the annular member and elastic layer, suppressing discharge occurrence even under high voltage conditions over time.
2Strength
If the protruding part thickness is larger, then the mechanical interlock is stronger, but the risk of damaging the elastic layer increases
Solution Approach 1:
The thickness of the protruding part is precisely controlled within a specific range (0.1-0.5mm) to optimize the balance between mechanical interlock strength and elastic layer protection. This parameter optimization ensures sufficient cutting depth for reliable gap prevention while minimizing damage risk to the elastic layer material.
Data Source
AI summary
A roll includes an electrically-conductive shaft; an elastic layer provided on the shaft; and a non-electrically-conductive annular unit that is attached to at least one of ends of the shaft that protrude from end surfaces of the elastic layer in a shaft direction while being in contact with the end surface of the elastic layer. A protruding part that protrudes so as to cut into the end surface of the elastic layer is provided on a part of the annular unit that makes contact with the end surface of the elastic layer, and the protruding part has a thickness smaller than a thickness of the part of the annular unit that makes contact with the end surface of the elastic layer.