Charging Member with Exposed Elastic Particles for Uniform Electrostatic Charging
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Solution Overview
Problem
Charging members for electrophotographic apparatuses face challenges in maintaining stable and uniform charging over long periods due to contamination accumulation, which affects image quality and consistency.
Innovation Solution
A charging member with an electro-conductive support and a surface layer featuring concave portions with exposed elastic particles, where the elastic particles have a Martens hardness of 0.1 N/mm2 to 3.0 N/mm2 and an elastic recovery power of 70% or more, forming convex portions that deform to prevent toner crushing and contamination, while the concave portion walls have a higher Martens hardness to prevent external additive adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a charging member has a smooth surface layer, then it is easy to manufacture and maintain, but contamination accumulates on the surface over time, affecting charging uniformity and image quality
Solution Approach 1:
The surface layer is designed with local variations in hardness: softer elastic particles (0.1-3.0 N/mm²) are embedded in the surface layer to provide deformation capability for preventing contamination, while the concave portion walls maintain higher hardness to prevent external additive adhesion. This local differentiation of material properties resolves the contradiction by making the surface both manufacturable and capable of maintaining charging performance over time.
Solution Approach 2:
The elastic particles with high elastic recovery power (70% or more) provide dynamic deformation capability to the surface layer. When the charging member contacts the photosensitive member, the elastic particles deform to create micro-gaps that prevent toner crushing and contamination accumulation, then recover their original shape. This dynamic behavior maintains charging uniformity over extended periods without requiring complex manufacturing processes.
2Object-affected harmful factors
If the surface layer has high hardness to prevent external additive adhesion, then contamination resistance improves, but the surface cannot deform to prevent toner crushing and contamination
Solution Approach 1:
The surface layer is designed with local variations in hardness: softer elastic particles (0.1-3.0 N/mm²) are embedded in the surface layer to provide deformation capability for preventing contamination, while the concave portion walls maintain higher hardness to prevent external additive adhesion. This local differentiation of material properties resolves the contradiction by making the surface both manufacturable and capable of maintaining charging performance over time.
Solution Approach 2:
The surface layer is segmented into functionally distinct regions: the elastic particles provide one function (deformation to prevent toner crushing), while the concave portion walls provide another function (high hardness to prevent external additive adhesion). This segmentation allows each component to optimize its specific function without compromising the other, resolving the contradiction between softness needed for deformation and hardness needed for contamination resistance.
3Manufacturing precision
If elastic particles are exposed at the surface to form convex portions, then charging uniformity improves, but the surface becomes more complex and harder to manufacture
Solution Approach 1:
The elastic particles are controlled to have specific parameters: Martens hardness of 0.1-3.0 N/mm² and elastic recovery power of 70% or more. These parameter specifications allow the particles to deform appropriately during charging contact while maintaining their structural integrity. By controlling these parameters, the surface structure achieves charging uniformity without requiring overly complex manufacturing processes.
Solution Approach 2:
The surface layer is a composite structure combining the electro-conductive support material with embedded elastic particles. This composite approach allows the elastic particles to be incorporated during the manufacturing process itself, rather than requiring post-processing steps to create the convex portions. The composite structure integrates multiple functions (electrical conductivity, deformation capability, contamination resistance) into a single manufacturable component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution ensures stable and uniform charging, reducing spot-like and stepped unevenness in image density, and suppressing horizontal streak-like image failures, thereby maintaining high-quality electrophotographic image formation over extended periods.
Implementation Method 1
the elastic particle has an elastic recovery power of 70% or more
Implementation Method 2
when each of the concave portions and the elastic particle held in each of the concave portions are orthogonally projected on a surface of the support and orthogonal projection image is obtained, in the orthogonal projection image, a site in which an outer edge of a projection image derived from each of the concave portions and an outer edge of a projection image derived from the elastic particle in the respective concave portions are separated, exists
Implementation Method 3
a charging member to be used for an electrophotographic apparatus... capable of uniformly charging, by applying only a DC voltage, a body to be charged
Data Source
AI summary
Provided a charging member including an electro-conductive support and a surface layer, the surface layer having in an outer surface thereof, concave portions and holding an elastic particle in each of the concave portions, the elastic particle being exposed at a surface of the charging member to form a convex portion in the surface of the charging member, and a part of a wall of each of the concave portions constituting a part of the surface of the charging member.