Spiral-Grooved Charging Roll for Uniform Discharge Roughness
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Solution Overview
Problem
Conventional charging rolls for electrophotographic apparatuses face issues with uniformity in surface roughness due to aggregation of roughness forming particles, leading to deteriorated discharge properties, especially when multiple particle sizes are used.
Innovation Solution
A charging roll design featuring a shaft with an elastic body layer and a surface layer, where grooves defining spirals are formed on the outer peripheral surface, with specific groove widths, depths, and area ratios, and incorporating roughness forming particles of polyurethane, polyamide, or acrylic resin, ensuring uniform discharge properties by controlling asperity configuration and binder polymer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If roughness forming particles are added to the surface layer, then surface roughness is formed to improve discharge properties, but the particles aggregate causing non-uniform surface roughness
Solution Approach 1:
The patent introduces grooves with specific dimensions (width 4-280 μm, depth 2-30 μm) and controlled area ratios (0.3-2.4) to create localized regions where roughness forming particles are concentrated. This local structuring ensures uniform particle distribution within each groove while maintaining overall surface uniformity, resolving the aggregation problem while preserving discharge properties.
Solution Approach 2:
The patent controls the aggregation of roughness forming particles by adjusting critical parameters including groove width (4-280 μm), groove depth (2-30 μm), area ratio of groove bottom to plane part (0.3-2.4), and binder polymer thickness. These parameter changes prevent particle aggregation and ensure uniform surface roughness while maintaining effective discharge properties.
2Shape
If multiple types of roughness forming particles with different particle diameters are used, then surface asperities are enhanced, but particle aggregation increases causing deterioration in surface roughness uniformity
Solution Approach 1:
The patent uses grooves to create localized zones where multiple particle sizes can be accommodated. Each groove acts as a confined space that organizes particles of different diameters, preventing their random aggregation across the surface. This local structuring maintains surface asperities while ensuring uniform roughness distribution.
Solution Approach 2:
The patent employs composite structures combining grooves with roughness forming particles of different diameters. The groove architecture serves as a matrix that integrates multiple particle types, allowing them to work together to enhance surface asperities without causing uniformity deterioration through aggregation.
3Manufacturing precision
If the binder polymer thickness is increased to cover roughness forming particles, then particle aggregation is reduced, but the surface roughness decreases affecting discharge properties
Solution Approach 1:
The patent applies binder polymer with controlled thickness specifically within groove regions versus plane parts. The groove structure allows for localized binder application that covers particles sufficiently to prevent aggregation while preserving the surface roughness needed for discharge. The grooves act as reservoirs that maintain particle exposure while ensuring uniform distribution.
Data Source
AI summary
In a charging roll, grooves regularly defining spirals are formed on an elastic body layer, with a groove width of 4 μm to 280 μm and a groove depth of 2 μm to 30 μm. On an outer peripheral surface of the elastic body layer, an area ratio between an area of a bottom surface of the groove and an area of a plane part is 0.3 to 2.4. The surface layer includes a binder polymer and a roughness forming particle. The roughness forming particle is arranged on the plane part and the groove. A surface roughness of the surface layer on the groove is 2 μm to 16 μm. A surface roughness of the entire surface layer is 5 μm to 26 μm. A thickness of the binder polymer covering the roughness forming particle on the groove is greater than that on the plane part.