Thermoplastic Charging Roller Surface for Uniform Charge Distribution
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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 issues such as spotted unevenness and lateral streaked unevenness, and have high rotational resistance.
Innovation Solution
A charging roller design featuring a conductive shaft, an elastic body layer, and a surface layer composed of a thermoplastic resin and conductive particles, including carbon black and metal oxide particles, with specific particle size distribution and water contact angle conditions to ensure uniform charge distribution and low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional charging roller with insulating particles and resin film is used, then charging defects are suppressed, but uneven discharge still occurs and rotational resistance is high
Solution Approach 1:
The patent changes the material parameters of the surface layer by using a thermoplastic resin with specific water contact angle (40-180°) and controlling the particle size distribution of conductive particles (peak at 0.01-1 μm), which fundamentally alters the electrical and surface properties to achieve uniform charging and reduce rotational resistance
Solution Approach 2:
The patent creates a composite surface layer combining thermoplastic resin with conductive particles (carbon black and metal oxide), where the resin provides structural integrity and the conductive particles provide electrical conductivity, achieving both charging uniformity and low rotational resistance simultaneously
2Manufacturing precision
If the surface layer contains conductive particles with specific particle size distribution, then uniform charge distribution is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for particle size distribution (peak at 0.01-1 μm) and water contact angle (40-180°) to control the surface layer properties, ensuring uniform charge distribution while providing clear manufacturing guidelines
3Object-generated harmful factors
If the binder resin uses thermoplastic resin with controlled water contact angle, then rotational resistance is reduced, but material selection constraints increase
Solution Approach 1:
The patent establishes specific parameter ranges for thermoplastic resin water contact angle (40-180°) to optimize rotational resistance, providing clear criteria for material selection while reducing the complexity of testing and evaluation
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 smooth operation 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.
Implementation Method 2
A water contact angle of the thermoplastic resin and a content of the first conductive particles in the conductive particles satisfy expressions (1) to (3).
Data Source
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AI summary
A charging roller (51) includes a conductive shaft (51a), an elastic body layer (51b) formed on an outer periphery of the conductive shaft, and a surface layer (51c) formed on an outer periphery of the elastic body layer. The surface layer (51c) contains a binder resin (101) and conductive particles (102). The binder resin (101) contains only a thermoplastic resin. The conductive particles (102) contain first conductive particles (101a) and second conductive particles (101b). The first conductive particles (102a) are carbon black particles. A particle size distribution of the conductive particles (102) has at least one peak within a range of not less than 0.01 µm but not more than 1 µm. A water contact angle x of the thermoplastic resin and a content y of the first conductive particles in the conductive particles satisfy the following expressions: 40≤y, y≤(800/27)x+(280/9), and y≤-8x+200.