Electrophotographic Photosensitive Member Concave Surface Geometry
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Solution Overview
Problem
Cylindrical electrophotographic photosensitive members experience stripe-like image defects, known as H/H initial streaks, when operating in low print mode under high temperature and highly humid environments due to increased resistance and moisture adsorption, which complicates surface refreshment and cleaning.
Innovation Solution
The cylindrical electrophotographic photosensitive member features concave portions with specific geometries, including an apex angle of 0° to 90° and a largest width of 20 µm to 80 µm, where the depth decreases from the deepest point towards the apex, enhancing the stability of the cleaning blade and reducing friction irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the resistance to wear of the circumferential surface is increased by using curable resins, then durability is improved, but image deletion occurs due to difficulty in refreshing the surface
Solution Approach 1:
The invention introduces a porous layer on the circumferential surface of the electrophotographic photosensitive member. This porous structure allows for easier refreshment of the surface by enabling removal of deteriorated material and adsorbed moisture, while the underlying curable resin provides the necessary wear resistance. The porosity creates channels for surface renewal without compromising the mechanical strength of the base material.
2Reliability
If concave portions are disposed on the circumferential surface, then image deletion is improved, but stripe-like image defects occur under high temperature and highly humid environment
Solution Approach 1:
The invention combines two different surface structures with distinct functions: concave portions are provided in specific regions to prevent image deletion by facilitating surface refreshment, while the porous layer is provided in regions prone to stripe-like defects to maintain surface uniformity. This spatial differentiation of surface properties allows each structure to address its specific problem without causing adverse effects elsewhere.
Solution Approach 2:
The invention creates a composite surface structure combining concave portions and porous layers. The concave portions provide localized surface renewal capability, while the porous layer provides overall surface uniformity and moisture management. The combination of these two different structural elements works synergistically to eliminate both image deletion and stripe-like defects.
3Reliability
If the circumferential surface is refreshed to remove deteriorated material, then image deletion is prevented, but cleaning performance reduces due to surface modification
Solution Approach 1:
The porous layer structure facilitates automatic surface refreshment through its interconnected pore network, which allows deteriorated material and moisture to be removed more easily. This self-refreshing capability reduces the need for aggressive mechanical cleaning that might damage the surface, thereby maintaining cleaning performance while preventing image deletion.
Data Source
Figure 1~2
Figure 3A~3J
Figure 4A~4H
AI summary
In an electrophotographic photosensitive member, a circumferential surface has concave portions that are independent one another; each of the concave portions has an opening, a contour of the opening has an apex having an angle a of more than 0° and 90° or less on at least an upstream side of a rotational direction of the electrophotographic photosensitive member, and has a largest width in an axial direction of the electrophotographic photosensitive member of 20 μκι or more and 80 μπι or less, a width of the contour in the axial direction of the electrophotographic photosensitive member decreasing from a portion having the largest width toward the apex, when viewing each of the concave portions in the axial direction, each of the concave portions has a depth that decreases from a deepest point of each of the concave portions toward the apex.