Charging Roll Surface Layer Topography for Uniform Discharge
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Solution Overview
Problem
Existing electroconductive rolls in image forming apparatuses face challenges in achieving uniform discharge, leading to image unevenness due to variations in surface roughness, which current techniques struggle to fully address.
Innovation Solution
An electroconductive roll design featuring a core member, a rubber base material, and a surface layer with specific surface roughness characteristics, including an arithmetic mean peak curvature of 1,880 to 14,024 (1/mm) and a density of peaks of 93,406 to 151,476 (1/mm^2), along with a surface area per unit projected area of 1.255 to 5.132, is implemented to enhance discharge uniformity.
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 applies parameter changes by precisely controlling the surface roughness parameters (arithmetic mean peak curvature Spc: 1,880 to 14,024 1/mm, density of peaks Spd: 93,406 to 151,476 1/mm²) through specific particle size distributions (d10: 3-10 μm, d50: 15-30 μm, d90: 45-80 μm) and composition ratios in the surface layer, achieving optimal discharge uniformity that eliminates image unevenness
Solution Approach 2:
The patent uses composite materials by combining multiple particle sizes (d10, d50, d90 components) with the base resin material to form a surface layer with optimized roughness characteristics. This composite structure enables controlled discharge while maintaining image quality, resolving the contradiction between discharge uniformity and image evenness
2Manufacturing precision
If the surface roughness parameters are optimized to reduce image unevenness, then the image quality is improved, but the discharge uniformity deteriorates
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: surface roughness (Spc: 1,880 to 14,024 1/mm, Spd: 93,406 to 151,476 1/mm²), particle size distribution (d10: 3-10 μm, d50: 15-30 μm, d90: 45-80 μm), and layer composition to achieve both improved image quality and discharge uniformity through coordinated parameter adjustment
3Reliability
If the surface layer composition is adjusted to control discharge, then the discharge uniformity is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent manages complexity by establishing specific parameter ranges for particle sizes (d10: 3-10 μm, d50: 15-30 μm, d90: 45-80 μm) and surface roughness (Spc: 1,880 to 14,024 1/mm, Spd: 93,406 to 151,476 1/mm²) that can be controlled through standardized manufacturing processes, balancing discharge uniformity with manufacturability
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 design effectively reduces image unevenness by ensuring uniform discharge between the photoconductor element and the charging roll, resulting in high-quality images with reduced local discharge and scumming.
Implementation Method 1
An object of JP-A-2015-121769, JP-A-2012-14141, and JP-A-2005-91414 is to control a discharge between the charging roll and the photoconductor element to make the discharge as uniform as possible
Data Source
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) 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 151,476 (1/mm2). The surface area of the surface layer per unit projected area is equal to or greater than 1.255, and is equal to or less than 5.132.