Charging Roll Surface Layer for Uniform Photoconductor Discharge
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Solution Overview
Problem
Image forming apparatuses face challenges in achieving uniform image quality due to variations in the charged state of the photoconductor element, which is influenced by the surface roughness of the charging roll, and existing solutions do not adequately address these issues.
Innovation Solution
A charging roll design featuring a core member, an electroconductive rubber base material, and a surface layer with a specific density of peaks, where the surface layer includes an electroconductive matrix with dispersed insulating particles, optimizing the surface roughness to enhance discharge uniformity and reduce image unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface roughness of the charging roll is adjusted by use of fine particles in the surface layer, then the discharge uniformity is improved, but the image quality deteriorates due to image unevenness
Solution Approach 1:
The patent changes the critical parameter from particle size alone to a combination of particle size and density of peaks. By controlling the density of peaks (Spd) to be 93,406 1/mm² or more, the invention achieves both uniform discharge and high image quality, resolving the contradiction between discharge uniformity and image quality that plagued previous solutions using only fine particles.
2Reliability
If the surface layer contains only fine particles, then the discharge uniformity is improved, but the adhesion of external substances increases
Solution Approach 1:
The patent applies local quality by creating a surface layer with specific localized characteristics - high density of peaks (Spd ≥ 93,406 1/mm²) that provides both uniform discharge properties and reduced adhesion. The uneven surface structure created by controlling particle distribution provides discharge uniformity while the specific peak density prevents external substance adhesion, addressing both requirements simultaneously.
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 proposed charging roll design ensures uniform discharge between the photoconductor element and the charging roll, reducing image unevenness and enhancing the quality of the images produced by maintaining the desired density of peaks within a specific range.
Implementation Method 1
uniformity of a charged state of the photoconductor element, which is affected by the surface roughness of a charging roll
Implementation Method 2
the surface layer includes an electroconductive matrix that contains a base material formed of an electric insulator and an electroconductive material being dispersed in the base material
Data Source
Figure 1~2
Figure 3
AI summary
An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The density of peaks Spd of the surface of the surface layer is equal to or greater than 93,406 (1/mm2), and is equal to or less than 153,027 (1/mm2).