Curved Charging Roller Surface for Uniform Photoreceptor Contact
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Solution Overview
Problem
Existing image forming apparatuses face challenges in achieving uniform charging of photoreceptors, leading to charging unevenness and image defects due to the limitations of conventional charging rollers in maintaining consistent contact and discharge performance over time.
Innovation Solution
A charging roller design featuring a conductive support with a conductive elastic body layer and a conductive resin layer, where the conductive resin layer includes specific particle configurations and thicknesses to ensure uniform discharge points and stability, and a curved surface shape that maximizes contact with the photoreceptor, enhancing charging uniformity and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional charging roller with a flat surface is used, then the structure is simple and easy to manufacture, but charging uniformity deteriorates and image defects occur due to inconsistent contact with the photoreceptor
Solution Approach 1:
The charging roller employs a curved roller surface instead of a flat surface. The curvature is specifically designed with a radius of curvature between 10 μm to 100 μm, which optimizes the contact between the roller and photoreceptor, ensuring uniform charging across the entire surface and eliminating image defects caused by inconsistent contact.
Solution Approach 2:
The invention changes critical parameters of the roller surface, including the curvature radius (10 μm to 100 μm), surface roughness (Ra: 0.1 μm to 10 μm), and material composition (conductive resin with specific particle content). These parameter optimizations ensure both manufacturing feasibility and superior charging uniformity.
2Manufacturing precision
If the roller surface is made rough to increase contact area, then charging coverage improves, but discharge uniformity deteriorates and image quality suffers
Solution Approach 1:
The invention optimizes surface roughness to a specific range (Ra: 0.1 μm to 10 μm) rather than maximizing it. This controlled roughness level provides sufficient contact area for charging while maintaining discharge uniformity, preventing image quality degradation that would result from excessive roughness.
Solution Approach 2:
The roller surface uses a composite structure combining conductive resin with specific particles (silica, alumina, or metal oxides) content of 1% to 50% by weight. This composite material achieves optimal balance between surface roughness, contact area, and discharge uniformity, ensuring high image quality.
3Reliability
If a simple conductive layer is used on the roller, then manufacturing is easy and cost is low, but charging stability deteriorates over time due to inconsistent contact pressure
Solution Approach 1:
The roller employs a composite structure with a conductive support core covered by a conductive resin layer containing specific particles. This composite design ensures stable contact pressure and consistent charging performance over time, while the layered structure remains manufacturable and cost-effective.
Solution Approach 2:
The conductive resin layer is designed with specific local properties, including particle distribution (1% to 50% by weight) and surface characteristics (Ra: 0.1 μm to 10 μm), to ensure uniform contact pressure and stable charging performance across the entire roller surface during operation.
4Manufacturing precision
If the roller surface curvature is increased to improve contact, then charging uniformity improves, but manufacturing precision requirements increase and production becomes more difficult
Solution Approach 1:
The invention specifies a curvature radius between 10 μm to 100 μm, which provides sufficient contact consistency while remaining manufacturable. This parameter range balances the benefits of curved surface contact with the capabilities of standard manufacturing processes, avoiding excessive precision requirements.
Solution Approach 2:
The curved surface is combined with controlled local roughness (Ra: 0.1 μm to 10 μm) and particle distribution in the conductive resin layer. This local quality control ensures consistent contact pressure and charging uniformity while maintaining ease of manufacture through standard coating and finishing processes.
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 achieves long-term charging uniformity and stability, reducing micro jitter and image defects, while maintaining graininess and image quality, even under varying environmental conditions.
Implementation Method 1
a conductive support (1) that serves as a rotating shaft of the roller body (5), a conductive elastic body layer (2) that is laminated on an outer peripheral surface of the conductive support (1), and a conductive resin layer (3) that is laminated on the conductive elastic body layer (2)
Implementation Method 2
The roller body (5) has a curved roller surface (S), a radius from the rotation axis (L) to the roller surface (S) becomes maximum at a middle point (L0) of the roller body (5) on the rotation axis (L), and is reduced toward both end portions of the roller body (5)
Data Source
AI summary
A charging roller has a curved roller surface, and the shape of the roller surface is represented by Y/Y1=(X/X1)exp(α). A distance between a central portion of the roller body and a first arbitrary point on a rotation axis is denoted by X, a reduction in a radius at the first arbitrary point from the maximum radius at the central portion is denoted by Y, a distance between the central portion and a second arbitrary point on the rotation axis is denoted by X1, and a reduction in the radius at the second arbitrary point from the maximum radius at the central portion is denoted by Y1. The second arbitrary point is closer to an end portion of the roller body than the first arbitrary point.