Charging Roller Surface Composition for Uniform Discharge
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Solution Overview
Problem
Conventional charging rollers fail to uniformly charge the surface of an image bearing member, leading to uneven discharge and image defects such as spotted unevenness or lateral streaked unevenness, and have high rotational resistance.
Innovation Solution
A charging roller with a surface layer containing a thermoplastic resin and a combination of metal oxide and other conductive particles, with a specific particle size distribution and content, to enhance electrical conductivity and reduce rotational resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional charging rollers are used, then the structure is simple, but uneven discharge occurs leading to image defects
Solution Approach 1:
The surface layer is constructed as a composite material containing thermoplastic resin as binder, metal oxide conductive particles, and other conductive particles. This composite structure achieves uniform charge distribution by combining the benefits of different materials: thermoplastic resin provides structural integrity and controlled water contact angle (40°-180°), metal oxide particles provide high electrical conductivity, and additional conductive particles enhance charge uniformity. The specific composition ratios and particle size distributions (with peaks at 0.01-1.00 μm) are optimized to eliminate uneven discharge while maintaining manufacturing feasibility.
2Force
If conventional charging rollers are used, then manufacturing is simple, but rotational resistance is high
Solution Approach 1:
The rotational resistance is reduced by optimizing key parameters of the surface layer: the water contact angle of thermoplastic resin is controlled within 40°-180° to balance hydrophobicity and charge transfer; conductive particles are distributed with specific concentration ratios (metal oxide particles at 15.0-200.0 parts by mass per 100.0 parts of binder resin); and particle size distribution is engineered with peaks at 0.01-1.00 μm to minimize friction while maintaining conductivity. These parameter optimizations enable smooth rotation with reduced resistance while keeping the manufacturing process within industrial feasibility.
3Reliability
If conventional charging rollers are used, then the structure is simple, but uneven discharge causes spotted unevenness and lateral streaked unevenness
Solution Approach 1:
The surface layer implements local quality optimization by distributing different types of conductive particles throughout the thermoplastic resin matrix. Metal oxide conductive particles are dispersed at controlled concentrations (15.0-200.0 parts by mass per 100.0 parts of binder resin) to create localized high-conductivity zones, while additional conductive particles fill interstitial spaces. The particle size distribution with peaks at 0.01-1.00 μm ensures fine-scale uniformity. This heterogeneous but controlled distribution pattern eliminates both spotted unevenness (caused by localized charge defects) and lateral streaked unevenness (caused by directional charge variations), achieving comprehensive discharge 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
The charging roller effectively suppresses uneven discharge and reduces rotational resistance, ensuring uniform charging and improved durability even in varying environmental conditions.
Implementation Method 1
The surface layer contains a binder resin and conductive particles. The conductive particles contain first conductive particles and second conductive particles. The first conductive particles are metal oxide particles.
Implementation Method 2
The thermoplastic resin has a water contact angle of not less than 40° but less than 180°
Data Source
AI summary
A charging roller comprises a conductive shaft, an elastic body layer, and a surface layer. The surface layer contains a binder resin and conductive particles. The binder resin contains only a thermoplastic resin. The thermoplastic resin has a water contact angle of not less than 40° but less than 180°. The conductive particles contain first conductive particles and second conductive particles. The first conductive particles are metal oxide particles. A content of the first conductive particles in the surface layer is not less than 15.0 parts by mass but not more than 200.0 parts by mass with respect to 100.0 parts by mass of the binder resin. A particle size distribution of the conductive particles has at least one peak within a range of not less than 0.01 μm but not more than 1.00 μm.