Matrix-Domain Conductive Roller for Stable High-Speed Charging
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Solution Overview
Problem
Existing electro-conductive members used in electrophotographic image forming processes, such as charging members, fail to provide stable discharge at high speeds, leading to potential unevenness on the photosensitive drum surface and the formation of ghost images due to insufficient equalization of surface potential.
Innovation Solution
An electro-conductive member with a matrix-domain structure is developed, featuring a cross-linked rubber matrix and dispersed domains with conductive particles, where the volume resistivity of the matrix is greater than 1.0×10^12 Ωcm, and the domains have a lower resistivity, allowing for efficient charge accumulation and stable discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electro-conductive member with uniform composition is used, then the manufacturing process is simple, but the discharge stability is insufficient at high speeds leading to potential unevenness
Solution Approach 1:
The electro-conductive layer is segmented into a matrix phase and dispersed domain phases with different resistivity values. The matrix has higher resistivity (1.0×10^12 Ωcm or more) while the domains have lower resistivity (1.0×10^5 to 1.0×10^8 Ωcm), creating a heterogeneous structure that enables stable discharge at high speeds by preventing potential unevenness on the photosensitive drum surface.
Solution Approach 2:
Different regions of the electro-conductive layer are赋予 different electrical properties. The matrix regions provide insulation and structural integrity with high resistivity, while the dispersed domain regions provide conductive pathways for charge accumulation and discharge. This local differentiation of electrical properties enables the member to maintain stable discharge performance at high imaging speeds.
2Reliability
If the volume resistivity of the electro-conductive layer is reduced to improve charge transport, then charge accumulation becomes more efficient, but surface potential equalization deteriorates leading to ghost images
Solution Approach 1:
The electro-conductive layer is divided into matrix and domain phases with distinct resistivity values. The matrix phase with high resistivity (≥1.0×10^12 Ωcm) prevents excessive charge leakage and maintains surface potential uniformity, while the dispersed domain phases with lower resistivity (1.0×10^5 to 1.0×10^8 Ωcm) provide localized charge accumulation sites, achieving both uniform potential distribution and efficient charge transport.
3Productivity
If the electro-conductive member operates at high speed, then productivity increases, but discharge stability deteriorates causing potential unevenness and ghost images
Solution Approach 1:
The segmented structure with matrix and domain phases enables the electro-conductive member to maintain stable discharge characteristics at high imaging speeds. The domain phases with lower resistivity ensure sufficient charge accumulation rate to match high-speed operation, while the matrix phase with high resistivity maintains surface potential uniformity, preventing ghost images even during rapid imaging cycles.
Solution Approach 2:
The resistivity parameters of the electro-conductive layer are optimized by creating a bimodal distribution: the matrix phase has resistivity of 1.0×10^12 Ωcm or more while the domain phases have resistivity of 1.0×10^5 to 1.0×10^8 Ωcm. This parameter differentiation enables the member to achieve both stable discharge and high-speed operation capability.
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 electro-conductive member effectively equalizes surface potential unevenness, preventing ghost image formation and ensuring high-quality image formation even at high speeds by maintaining a stable discharge process.
Implementation Method 1
A charging member is a member which generates a discharge between itself and an electrophotographic photosensitive member to charge the photosensitive member surface
Implementation Method 2
the volume resistivity of the matrix is greater than 1.0×10^12 Ωcm, and the volume resistivity of the electro-conductive layer is 1.0×10^5 Ωcm or more to 1.0×10^8 Ωcm or less
Data Source
AI summary
The electro-conductive member has an electro-conductive support, and an electro-conductive layer, in which the electro-conductive layer has a matrix including a first rubber cross-linked product and domains dispersed in the matrix, each of the domains includes a second rubber cross-linked product and electro-conductive particles, an outer surface of the electro-conductive member has concave portions, a surface of at least a part of the domains is exposed to the outer surface of the electro-conductive member at bottom portions of the concave portions, a volume resistivity of the matrix is greater than 1×1012 Ωcm, a volume resistivity of the electro-conductive layer is 1×105 Ωcm to 1×108 Ωcm, and A2 is 20 times or more of A1.