Conductive Roll Surface Curvature for Uniform Charging Discharge
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Solution Overview
Problem
Image forming apparatuses face challenges in achieving uniform image quality due to uneven discharge between the charging roll and the photoconductor element, which is influenced by the surface roughness of the charging roll.
Innovation Solution
An electroconductive roll with a core member, a rubber base material, and a surface layer having an arithmetic mean peak curvature of 1,880 to 14,024 (1/mm) is developed, where the surface layer includes an electroconductive matrix with dispersed insulating particles to enhance surface roughness and ensure uniform discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface roughness of the charging roll is increased to improve discharge uniformity, then image quality improves, but the surface becomes too rough causing non-uniform discharge
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness parameters (Ra: 0.3-1.5 μm, Rz: 1.5-4.0 μm) of the charging roll surface. By optimizing these specific numerical parameters, the invention achieves uniform discharge characteristics that improve image quality while preventing excessive roughness that would cause non-uniform discharge. This quantitative parameter optimization resolves the contradiction between needing sufficient roughness for discharge uniformity and avoiding excessive roughness.
2Manufacturing precision
If fine particles are used in the surface layer to control discharge, then image quality improves, but the surface roughness becomes insufficient
Solution Approach 1:
The patent employs composite materials by combining fine particles (for discharge control) with specific surface roughness characteristics (Ra: 0.3-1.5 μm, Rz: 1.5-4.0 μm) in the charging roll surface layer. This composite structure integrates both the electrical properties provided by fine particles and the surface morphology properties needed for adequate roughness, thereby simultaneously achieving uniform discharge and sufficient surface roughness that neither component alone could provide.
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
This configuration reduces image unevenness and ensures uniform discharge, leading to improved image quality by maintaining appropriate surface roughness and electrical conductivity.
Implementation Method 1
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 arithmetic mean peak curvature Spc of a surface of the surface layer is equal to or greater than 1,880 (1/mm), and is equal to or less than 14,024 (1/mm).