Photosensitive Layer Thickness and Hardness Gradient for Image Quality
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Solution Overview
Problem
Electrophotographic photosensitive members with surface layers made of amorphous silicon carbide (a-SiC) suffer from defects such as flaws and variations in image density during printing due to uneven thickness and hardness, leading to issues like toner attachment and increased manufacturing time.
Innovation Solution
An electrophotographic photosensitive member with a cylindrical body having a photosensitive layer where the middle portion is pressed harder and thicker than the end portions, with a dynamic indentation hardness ratio of 1.03 to 1.25, and a surface layer thickness ratio of 1.03 to 1.25, to maintain image quality and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the photosensitive layer thickness is made substantially constant in the axial direction, then manufacturing precision is improved, but image quality deteriorates due to toner attachment and flaws at the middle portion
Solution Approach 1:
The patent applies local quality by making the photosensitive layer thickness non-uniform in the axial direction, specifically making the middle portion thicker than the end portions. This local variation in thickness prevents toner attachment and flaws at the middle portion during printing, while maintaining appropriate thickness at end portions for proper cleaning blade contact.
2Duration of action of stationary object
If the surface layer hardness is increased to prevent wear, then durability is improved, but image quality deteriorates due to flaws and variations in density
Solution Approach 1:
The patent applies local quality by creating a non-uniform hardness distribution in the surface layer, making the middle portion harder than the end portions. This local hardening prevents wear and maintains durability during extensive printing, while the softer end portions allow proper cleaning blade contact and prevent image degradation.
3Device complexity
If uniform pressing is applied across the entire photosensitive member, then manufacturing simplicity is maintained, but image quality deteriorates due to insufficient protection at the middle portion
Solution Approach 1:
The patent applies local quality by implementing a pressing mechanism that applies different pressing forces to different portions of the photosensitive member. The middle portion receives stronger pressing to prevent toner attachment and maintain image quality, while end portions receive lighter pressing to allow proper cleaning blade contact.
4Productivity
If the photosensitive layer is made thinner to reduce manufacturing time, then productivity is improved, but reliability deteriorates due to increased susceptibility to wear and damage
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness distribution where the middle portion is thicker and the end portions are thinner. This allows the middle portion to have sufficient thickness for wear resistance and durability during printing, while the thinner end portions reduce overall manufacturing time and material usage.
Data Source
AI summary
An electrophotographic photosensitive member rotatably supported in an image forming apparatus. The electrophotographic photosensitive member includes a substantially cylindrical body and a photosensitive layer formed thereon and having a latent image forming area. The photosensitive layer is, when incorporated in the image forming apparatus, pressed harder at a middle portion than at end portions in an axial direction of the latent image forming area, and a thickness at the middle portion is larger than at the end portions. The photosensitive layer may have a dynamic indentation hardness larger at the middle portion than at the end portions.