Amorphous Silicon Surface Layer Roughness Control for Moisture Resistance
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Solution Overview
Problem
Electrophotographic photosensitive members with amorphous silicon carbide (a-SiC) surface layers suffer from image deletion issues due to moisture absorption, especially in high humidity environments, leading to reduced electrical resistance and image quality, and existing solutions like heating or grinding increase costs and complexity.
Innovation Solution
The electrophotographic photosensitive member features a surface layer with controlled surface roughness, specifically a mean roughness Ra of not more than 5.35 nm and ten-point mean roughness Rz of not more than 50 nm, achieved without grinding, which prevents moisture absorption and maintains high durability and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a-SiC surface layer is used to improve electrical property and hardness, then endurance and image property are improved, but moisture absorption increases leading to image deletion
Solution Approach 1:
The invention changes the surface roughness parameter of the a-SiC layer to resolve the contradiction. By controlling the surface roughness to have a mean roughness Ra of 0.05 μm or less, the surface becomes sufficiently smooth to prevent moisture absorption while maintaining the layer's electrical and mechanical properties. This parameter optimization allows the a-SiC layer to provide high endurance without the harmful moisture absorption effect.
2Reliability
If grinding is performed to reduce surface roughness and prevent moisture absorption, then image deletion is prevented, but manufacturing complexity and cost increase
Solution Approach 1:
The invention applies preliminary action by controlling the surface roughness during the formation of the a-SiC layer itself, rather than performing grinding as a subsequent step. By optimizing the deposition process to produce a surface with Ra ≤ 0.05 μm from the beginning, the need for additional grinding operations is eliminated, simplifying the manufacturing process while ensuring long-term image quality stability.
3Reliability
If heater is used to remove absorbed moisture, then image deletion is prevented, but product cost and structural complexity increase
Solution Approach 1:
The invention extracts the moisture removal function by preventing moisture absorption at the source through surface roughness control, rather than using a heater to remove moisture after it is absorbed. By ensuring the a-SiC surface has Ra ≤ 0.05 μm, the surface inherently resists moisture absorption, making the heater function unnecessary and eliminating the associated structural complexity and cost.
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
This approach ensures long-term reliability and high-quality images without the need for heating or grinding, reducing production costs and maintaining image integrity even in high humidity conditions.
Implementation Method 1
the surface layer has a mean roughness Ra of not more than 5.35 nm per 10 μm square and a ten-point mean roughness Rz of not more than 50 nm
Implementation Method 2
prevents moisture absorption and maintains high durability and image quality
Implementation Method 3
water/moisture absorption at the surface layer due to corona discharge in printing
Implementation Method 4
Si atoms existing at the surface of the surface layer are oxidized in corona discharge, which increases hydrophilic property at the surface and thus increases moisture absorption
Implementation Method 5
In corona discharge, discharge products such as nitrate ion and ammonium ion are generated and absorbed at the surface layer
Implementation Method 6
An image forming apparatus such as a copying machine and a printer utilizing electrophotographic method is provided with an electrophotographic photosensitive member for forming electrostatic latent images
Data Source
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AI summary
The present invention relates to an electrophotographic photosensitive member 2 including a conductive body 20, a photoconductive layer 22 formed on the conductive body 20 using amorphous silicon, and a surface layer 23 formed on the photoconductive layer 22 using amorphous silicon. The present invention further relates to an image forming apparatus provided with the electrophotographic photosensitive member 2. The photoconductive layer 22 has a mean roughness Ra of not more than 10nm per 10µm square. The surface layer 23, without undergoing grinding process, has a mean roughness Ra of not more than 10nm per 10µm square.