Thermoplastic Charging Roller Surface for Uniform Image Charging
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Solution Overview
Problem
Conventional charging rollers fail to uniformly charge the surface of an image bearing member, leading to image defects such as uneven discharge, and have high rotational resistance due to environmental dependency of thermosetting resins.
Innovation Solution
A charging roller with a surface layer containing a thermoplastic resin and a combination of metal oxide and other conductive particles, dispersed to a specific particle size range, reduces uneven discharge and rotational resistance by minimizing environmental dependency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional charging roller with thermosetting resin is used, then the charging roller can provide structural stability, but it exhibits high rotational resistance and environmental dependency leading to uneven discharge
Solution Approach 1:
The patent changes the material parameter from thermosetting resin to thermoplastic resin, which fundamentally alters the electrical resistance characteristics and environmental dependency. This parameter change enables the charging roller to maintain low rotational resistance while providing uniform charging across varying temperature and humidity conditions.
Solution Approach 2:
The patent creates a composite surface layer combining thermoplastic resin with conductive particles (metal oxide and carbon black). This composite structure achieves both low rotational resistance through the conductive particles and uniform charging through the thermoplastic resin's environmental stability, resolving the contradiction between charging uniformity and rotational resistance.
2Reliability
If the surface layer contains only thermosetting resin, then manufacturing is simplified, but uneven discharge occurs due to environmental dependency
Solution Approach 1:
The patent employs a composite surface layer consisting of thermoplastic resin as the base material combined with conductive particles (metal oxide particles and carbon black particles). This composite approach maintains manufacturing simplicity while the thermoplastic resin provides environmental stability to prevent uneven discharge, achieving both reliability and ease of manufacture.
Solution Approach 2:
The patent changes the resin type parameter from thermosetting to thermoplastic, which provides inherent environmental stability. This parameter change eliminates the need for complex additives or treatments to prevent uneven discharge, maintaining ease of manufacture while significantly improving charging uniformity across different environmental conditions.
3Reliability
If conductive particles are not properly dispersed, then manufacturing is easier, but uneven discharge occurs due to poor conductivity distribution
Solution Approach 1:
The patent specifies precise particle size parameters for the conductive particles (metal oxide particles: 0.003-0.1 μm, carbon black particles: 0.003-0.1 μm). By controlling these size parameters and their distribution, the patent ensures uniform conductivity throughout the surface layer, achieving reliable uniform charging while the thermoplastic resin matrix facilitates easy dispersion of the fine particles.
Solution Approach 2:
The composite surface layer structure with thermoplastic resin and fine conductive particles creates a matrix that naturally facilitates particle dispersion. The thermoplastic resin's properties allow for uniform distribution of the fine metal oxide and carbon black particles, achieving reliable charging uniformity without requiring overly complex dispersion control mechanisms.
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 maintains low rotational resistance across varying environmental conditions, ensuring uniform charging and improved durability.
Implementation Method 1
The thermoplastic resin has a water contact angle of not less than 40° but less than 180°
Implementation Method 2
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.
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 thermoplastic resin has a water contact angle of not less than 40° but less than 180°. The conductive particles (102) contain first conductive particles (102a) and second conductive particles (102b). The first conductive particles (102a) are metal oxide particles. A content of the first conductive particles (102a) in the surface layer (51c) is not less than 10.0% by mass but not more than 55.0% by mass. 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 1.00 µm.