Electrophotographic Drum Wrinkle Surface Friction Reduction
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Solution Overview
Problem
Existing electrophotographic photosensitive drums face issues with high frictional force and cleaning failures due to the interaction with cleaning blades, leading to abrasion and streaky images, despite previous methods to reduce friction and improve cleanability being insufficient.
Innovation Solution
The electrophotographic photosensitive drum features a surface with wrinkles that intersect with multiple reference lines at varying angles, forming a complex concave and convex shape, reducing friction while preventing toner slip, achieved through a specific surface treatment and heat processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the outer surface of the electrophotographic photosensitive drum is made smooth by dip coating method, then the surface finish is improved, but the contact area with cleaning blade increases resulting in increased frictional force
Solution Approach 1:
The invention applies local quality by creating specific surface structures (concave-convex patterns, wrinkles, scratches) at the outer surface of the photosensitive drum. These localized surface modifications reduce the contact area between the cleaning blade and drum surface, thereby reducing frictional force while maintaining the overall smoothness achieved through dip coating. The surface is not uniformly modified but has specific regions with controlled irregularities that serve the friction reduction function.
2Force
If the outer surface is formed in concave and convex shape to reduce contact area, then frictional force is reduced, but unevenness occurs due to aggregation of fine particles causing cleaning failure
Solution Approach 1:
The invention applies parameter changes by precisely controlling the surface morphology parameters (concave-convex shape, wrinkle patterns, scratch orientations) and their geometric characteristics. By optimizing parameters such as the depth, width, distribution, and orientation of surface features, the invention reduces frictional force while ensuring uniformity that prevents toner slip during cleaning. The surface parameters are tuned to balance friction reduction with cleaning reliability.
3Force
If linear scratches are formed on the outer surface to reduce contact area, then frictional force is reduced, but residual toner slips through at low blade pressure resulting in streaky images
Solution Approach 1:
The invention applies asymmetry by creating surface features with specific directional characteristics (wrinkles and scratches oriented in particular directions) rather than uniform random patterns. The asymmetric orientation of these surface features is designed to interact specifically with the cleaning blade motion, reducing friction while maintaining effective toner removal. The directional asymmetry prevents toner from slipping through regardless of blade pressure level.
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3~5
AI summary
There is provided an electrophotographic photosensitive member having drum shape, the electrophotographic photosensitive member including a support and a photosensitive layer, wherein an outer surface of the electrophotographic photosensitive member has wrinkles, and when an observation region having square form with one side of 100 µm is placed at an arbitrary position on the outer surface, a line that passes through a central point of the observation region and is parallel to a circumferential direction of the electrophotographic photosensitive member is defined as a first reference line L1, and 3,599 reference lines obtained by rotating the first reference line L1 at every 0.1° around the central point are defined as L2 to L3,600, respectively, each of L1 to L3,600 intersects with convex portions of the wrinkles at a plurality of locations and has at least two different intersection angles selected from the plurality of locations.