Electroconductive Roll Surface Texture for Uniform Charging
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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 is developed, where the rubber base material is ground to minimize surface roughness and the surface layer is formed with specific particle diameters and amounts of surface roughness enhancing materials to ensure uniform discharge and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface roughness of the charging roll is increased to enhance discharge uniformity, then image quality improves, but the surface becomes too rough causing uneven discharge and image defects
Solution Approach 1:
The patent applies local quality by creating a surface layer with a specific roughness profile that differs from the base material. The surface layer contains particles with controlled size distribution (D10, D50, D90 parameters) that create localized micro-irregularities on the charging roll surface. This localized surface modification ensures uniform discharge at the micro-level without making the entire surface excessively rough, thereby preventing image defects while achieving discharge uniformity.
Solution Approach 2:
The patent employs composite materials by formulating a surface layer that combines rubber base material with specific particles (silica, alumina, titanium oxide, zirconium oxide) in controlled proportions. This composite structure allows the charging roll to have a smooth base for overall stability while the particle-containing surface layer provides the necessary micro-roughness for uniform discharge. The composite material approach enables simultaneous achievement of discharge uniformity and prevention of image defects.
2Manufacturing precision
If the surface roughness is reduced to minimize image unevenness, then discharge uniformity improves, but the charging roll cannot provide sufficient discharge to the photoconductor element
Solution Approach 1:
The patent resolves this contradiction by applying local quality - the base material maintains smoothness for overall discharge capability, while the surface layer introduces controlled local micro-irregularities. This localized surface modification ensures that the bulk surface remains smooth enough for reliable discharge, while the particle-containing surface layer provides the necessary micro-texture for uniform discharge distribution, preventing both image unevenness and discharge insufficiency.
Solution Approach 2:
The patent applies dimensionality change by transitioning from controlling only the macro-scale surface roughness to controlling multi-scale surface characteristics. The surface layer particles create micro-scale irregularities (nanometer to micrometer scale) on top of the smooth macro-scale surface. This multi-dimensional surface control allows the charging roll to maintain sufficient discharge capability at the macro level while achieving uniform discharge through micro-level modifications.
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 effectively reduces image unevenness and ensures uniform discharge, resulting in high-quality images by adjusting the surface roughness and composition of the surface layer on the charging roll.
Implementation Method 1
the rubber base material is ground to minimize surface roughness
Implementation Method 2
the surface layer is formed with specific particle diameters and amounts of surface roughness enhancing materials to ensure uniform discharge and image quality
Implementation Method 3
uniform discharge between the charging roll and the photoconductor element
Data Source
Figure 1~2
Figure 3~4
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.