Developing Roller Axial Accuracy Hollow Pipe Support
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Solution Overview
Problem
The existing developing rollers in image forming apparatuses face issues with increased weight due to metal cores, leading to reduced axial accuracy when assembled, and interference with photosensitive drums due to supporting members.
Innovation Solution
A processing unit with a hollow roller body and a conductive rubber covering layer, supported by a conductive resin supporting member that contacts the inner surface of the roller body, allowing for high axial accuracy and preventing interference with the photosensitive drum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal core is used in the developing roller, then the structural strength is improved, but the weight of the developing roller increases
Solution Approach 1:
The patent extracts the metal core from the developing roller structure and replaces it with a hollow pipe made of light-weight material. This removes the heavy component while maintaining the necessary structural framework, directly addressing the weight reduction goal while preserving structural integrity through the hollow pipe design.
Solution Approach 2:
The patent employs composite material construction by combining a hollow pipe (light-weight material) with a flange (structural component) and elastic rubber layer (functional coating). This composite structure achieves both weight reduction and structural strength requirements through the synergistic combination of different materials with complementary properties.
2Weight of moving object
If a flange with shaft is press-fitted into a hollow pipe, then the weight of the developing roller is reduced, but the axial accuracy of the developing roller to the casing becomes low
Solution Approach 1:
The patent removes the flange with shaft assembly from the hollow pipe structure. By eliminating this multi-element connection system, the design reduces complexity and potential sources of axial misalignment, thereby improving axial accuracy while maintaining the weight benefits of the hollow pipe construction.
Solution Approach 2:
The patent merges the supporting function directly into the casing structure through the supporting member that contacts the outer circumference of the hollow pipe. This integration eliminates intermediate connection elements (flange and shaft) and directly establishes the axial positioning relationship between the developing roller and casing, improving manufacturing precision.
3Manufacturing precision
If the outer circumference of the hollow pipe is supported by a supporting member, then the axial accuracy is improved, but the supporting member interferes with the photosensitive drum
Solution Approach 1:
The patent applies local quality by positioning the supporting member to contact the outer circumference of the hollow pipe at a specific location that provides axial support while maintaining clearance from the photosensitive drum. The supporting member is strategically placed only where needed for axial positioning, avoiding interference with adjacent components while maintaining manufacturing precision.
Solution Approach 2:
The patent resolves the interference issue by utilizing the radial dimension - the supporting member contacts the outer circumference of the hollow pipe in the radial direction to provide axial support. This dimensional approach allows the supporting member to fulfill its axial positioning function while being positioned radially outward, away from the photosensitive drum path, thereby eliminating interference.
Data Source
AI summary
A processing unit is provided. The processing unit includes: a housing; a developing roller that carries developer on a surface thereof, the developing roller including, a roller body, and a covering layer covering an outer circumferential surface of the roller body; a photosensitive drum that contacts the developing roller, wherein an end face of the photosensitive drum at a first side in an axial direction of the developing roller is located at an outer side in the axial direction compared to an end face of the developing roller at the first side in the axial direction, and wherein the developer on the developing roller is supplied to the photosensitive drum; and a supporting member that contacts an inner circumferential surface of the roller body at the first side in the axial direction, and supports the developing roller rotatably in the housing.