Developing Roll Dimple Surface for Toner Stress Reduction
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Solution Overview
Problem
Soft developing rolls for electrophotographic apparatuses face challenges in maintaining uniform toner transportability and image quality due to variations in surface roughness caused by hard particles, which can lead to toner deterioration and image defects like uneven concentration, streaks, and distortion.
Innovation Solution
A developing roll with a cylindrical outermost layer featuring multiple dimples distributed in a manner that their open ends do not overlap, forming a rough surface without using hard particles, allowing for controlled surface roughness and uniform toner transportability, and ensuring consistent pressure contact for improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hard particles are dispersed in the coat layer to roughen the surface for toner transfer, then the surface roughness is improved, but the surface hardness is increased which imparts stress on the toner and causes toner deterioration
Solution Approach 1:
The invention extracts and eliminates the hard particles from the coat layer composition. Instead of using hard particles dispersed in the coat layer, the invention forms a coat layer without hard particles, thereby removing the source of stress on toner while still achieving the desired surface roughness through alternative means
Solution Approach 2:
The invention changes the parameters of the coat layer by controlling the hardness and elasticity of the resin material itself, rather than relying on hard particles. By adjusting the resin's intrinsic properties and the surface roughness parameters through controlled formation processes, the invention achieves both toner transfer capability and reduced toner stress
2Manufacturing precision
If hard particles are dispersed in the coat layer to form a rough surface, then the surface roughness is improved for toner transfer, but the surface roughness varies widely over time due to cohesion of hard particles
Solution Approach 1:
The invention extracts and eliminates hard particles from the coat layer, removing the variable element that causes surface roughness to change over time. Without hard particles that can move, deform, or cohere, the surface roughness remains stable and uniform throughout the developing roll's operational life
Solution Approach 2:
The invention creates a homogeneous coat layer composition without hard particles, ensuring uniform properties throughout the material. This homogeneity prevents local variations in surface roughness that would otherwise occur due to particle distribution inconsistencies, leading to consistent toner transfer performance
3Manufacturing precision
If hard particles are used to roughen the surface, then the surface roughness is improved, but the mixing amount and density of hard particles must be precisely controlled to avoid variation in surface roughness
Solution Approach 1:
The invention extracts hard particles from the system, eliminating the need for complex control mechanisms to manage particle distribution, mixing ratios, and density. Without hard particles, the simpler single-phase resin composition is easier to manufacture and control, reducing production complexity while maintaining surface roughness quality
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 reduces stress on toner, maintains consistent surface roughness, and enhances image quality by preventing uneven concentration, streaks, and distortion, while also preventing the fog phenomenon through suitable dimple size and distribution.
Implementation Method 1
an outer peripheral surface of the outermost layer is formed into a rough surface by distribution of multiple dimples in such a manner that open ends thereof do not overlap one another on the surface
Data Source
AI summary
A developing roll which may reduce stress imparted on toner and have uniform transportability of toner. The developing roll comprises a shaft, an elastic layer provided on an outer peripheral surface of the shaft, and a cylindrical outermost layer provided directly or indirectly via a layer on an outer peripheral surface of the elastic layer, wherein an outer peripheral surface of the outermost layer is formed into a rough surface by distribution of multiple dimples in such a manner that open ends thereof do not overlap one another on the surface and a portion other than the dimples on the rough surface forms a remaining portion of a cylindrical shape.