Charging Member Surface Shape Control for Image Density
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Solution Overview
Problem
In image forming apparatuses using electrophotographic systems, charging members with poor surface shape in the circumferential direction cause vibrations in image holding members, leading to density unevenness in images due to variations in the position where latent images are formed.
Innovation Solution
A charging member with a cylindrical or columnar conductive substrate, an elastic layer, and a surface layer, where the maximum amplitude values of the elastic and surface layers' circumferential direction periods are controlled to ensure a ratio of As/Ae ≤ 0.9, suppressing vibrations and density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a charging member with poor surface shape in the circumferential direction is used, then manufacturing is simpler, but vibrations occur in image holding members causing density unevenness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface shape parameters of the charging member, specifically the circumferential direction period and amplitude values (Ae and As), to achieve As/Ae ≤ 0.9. This quantitative parameter control reduces vibrations and density unevenness while maintaining manufacturing feasibility.
Solution Approach 2:
The patent applies partial action by focusing control efforts on specific surface shape characteristics (circumferential period and amplitude ratios) rather than requiring perfect surface precision across all dimensions. This targeted approach achieves the necessary vibration reduction without excessive manufacturing complexity.
2Manufacturing precision
If surface shape precision of the charging member is improved, then density unevenness is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent defines specific parameter ranges for surface shape control (circumferential period and amplitude values Ae and As with As/Ae ≤ 0.9), providing clear manufacturing targets that balance precision requirements with process feasibility.
Solution Approach 2:
The patent replaces complex mechanical surface finishing processes with controlled surface formation methods during manufacturing, achieving required precision through process control rather than post-manufacturing mechanical adjustment.
3Reliability
If the amplitude ratio As/Ae is kept low (≤0.9), then vibrations are suppressed, but surface shape control becomes more difficult
Solution Approach 1:
The patent establishes the amplitude ratio As/Ae ≤ 0.9 as a key control parameter that directly correlates with vibration suppression effectiveness, providing a clear target for manufacturing control while maintaining reliability.
Data Source
AI summary
A charging member includes a cylindrical or columnar conductive substrate, an elastic layer provided on the conductive substrate, and a surface layer provided on the elastic layer. When in analysis of a circumferential direction period of a surface shape of the elastic layer, a maximum amplitude value in a period region of less than 5 mm is Ae, and when in analysis of a circumferential direction period of a surface shape of the surface layer, a maximum amplitude value in the period region of less than 5 mm is As, the charging member satisfies As/Ae≤0.9.