Charging Roll Bénard Cell Control for Uniform Image Quality
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Solution Overview
Problem
Existing charging rolls for electrophotographic equipment often suffer from uneven distribution of contaminants due to the generation of Bénard cells, leading to suboptimal image quality, as the height and size of these cells can affect surface roughness and electrostatic charge uniformity.
Innovation Solution
A charging roll with a surface layer containing polyamide and a modifier having a hydroxyl group, such as a fluorine-based, silicone-based, or acrylic modifier, is developed, which forms Bénard cells with controlled height and size, preventing local concentration of contaminants and ensuring uniform distribution of roughness-forming particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surface layer is formed on the charging roll, then charging characteristics are improved, but Bénard cells are generated on the surface causing uneven distribution of contaminants
Solution Approach 1:
The patent changes the physical and chemical parameters of the surface layer by incorporating porous resin particles with specific porosity (30-70%) and controlling the drying conditions to limit Bénard cell height to 0.1-1.0 μm. This parameter optimization allows the surface layer to maintain good charging characteristics while minimizing contaminant aggregation in Bénard cells
Solution Approach 2:
The surface layer is formed as a composite material containing binder resin, porous resin particles, and silicone oil. This composite structure improves charging characteristics through the porous particles while the silicone oil suppresses harmful contaminant concentration in Bénard cells, resolving the contradiction between charging performance and contaminant distribution
2Shape
If Bénard cells are present on the surface layer, then surface roughness is increased, but electrostatic charge uniformity deteriorates
Solution Approach 1:
The patent precisely controls the Bénard cell height parameter to be within 0.1-1.0 μm by adjusting the drying temperature (100-150°C) and time (30-60 minutes). This parameter control ensures sufficient surface roughness for charging while preventing excessive cell formation that would compromise electrostatic charge uniformity
Solution Approach 2:
The surface layer exhibits local quality variations through the controlled Bénard cell structure, where the cell walls provide localized roughness for charging characteristics while the overall cell distribution maintains electrostatic uniformity. The porous resin particles are strategically distributed to enhance local charging properties without disrupting global charge uniformity
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 enhances image quality by preventing contaminant aggregation and ensuring uniform surface roughness and electrostatic charge, resulting in improved charging characteristics and reduced streaks in printed images.
Implementation Method 1
the surface layer has Bénard cells with a height of 0.1 to 1.0 μm on a surface thereof
Data Source
AI summary
The disclosure provides a charging roll for excellent image quality electrophotographic equipment. This charging roll for electrophotographic equipment is provided with a shaft body, an elastic body layer formed on the outer periphery of the shaft body, and a surface layer formed on the outer periphery of the elastic body layer, wherein the surface layer contains a modifier having polyamide and a hydroxyl group, and has a Bénard cell with a height of 0.1 to 1.0 μm on the surface thereof. A fluorine-based modifier having a hydroxyl group, a silicone-based modifier having a hydroxyl group, and an acrylic modifier having a hydroxyl group can be cited as examples of the modifier having the hydroxyl group.