Charging Device Clean Member Foam Cell Ratio Optimization
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Solution Overview
Problem
In electrophotographic systems, contaminants on the image holding member can transfer to the charging member, reducing its charging ability and leading to image defects like image streak failures, which existing charging devices fail to prevent effectively.
Innovation Solution
A charging device with a charging member that uses a conductive substrate and a surface layer, and a clean member with a foamed elastic layer, where the ratio of the distance between irregularities on the charging member's surface layer to the width of the nodal section of the foam cell wall surface in the clean member is optimized between 2.4 and 5.9, facilitating effective contaminant removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact charging method is used with a charging member having a surface layer, then charging ability is improved, but contaminants transfer from the image holding member to the charging member, reducing charging ability over time and causing image streak failures
Solution Approach 1:
The clean member is designed as a foamed body with a specific cell structure (average cell diameter 0.18mm to 1.0mm) that allows it to effectively capture and retain contaminants through its porous network, preventing their transfer to the charging member while maintaining charging ability
Solution Approach 2:
The invention optimizes the surface roughness parameters of the charging member (Rz: 1.1μm to 5.0μm, RSm: 30μm to 320μm) to create an irregular surface that reduces contaminant adhesion, combined with the foamed clean member's cell structure parameters to achieve effective contaminant removal
2Reliability
If the surface roughness of the charging member is increased to prevent contaminant adhesion, then charging reliability is improved, but image quality deteriorates due to increased surface irregularities
Solution Approach 1:
The invention defines specific ranges for surface roughness parameters (Rz: 1.1μm to 5.0μm, RSm: 30μm to 320μm) that balance contaminant removal effectiveness with image quality, ensuring the surface is sufficiently irregular to prevent contaminant adhesion but not so irregular as to cause image defects
Solution Approach 2:
The surface layer is designed with controlled local irregularities that provide contaminant removal functionality while maintaining overall surface smoothness for image quality, creating different functional zones on the surface
3Productivity
If a clean member with large foam cell diameter is used to remove contaminants, then contaminant removal ability is improved, but cleaning precision decreases leading to image streak failures
Solution Approach 1:
The invention optimizes the foam cell diameter parameters (average cell diameter 0.18mm to 1.0mm, number of cells 40 to 75 per 25mm) to achieve the right balance between contaminant removal capacity and cleaning precision, preventing both contaminant buildup and image streak failures
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 configuration prevents the occurrence of image streak failures by ensuring the clean member can effectively remove contaminants from the charging member, maintaining the charging ability over time and improving image quality.
Implementation Method 1
a charging member that charges an image holding member according to a contact charging method, and includes a conductive substrate and a surface layer provided on the conductive substrate
Implementation Method 2
a clean member that cleans the charging member while contacting the charging member, and includes a shaft and a foamed elastic layer provided on the shaft
Data Source
AI summary
A charging device includes: a charging member that charges an image holding member according to a contact charging method, and includes a conductive substrate and a surface layer provided on the conductive substrate; and a clean member that cleans the charging member while contacting the charging member, and includes a shaft and a foamed elastic layer provided on the shaft, wherein a ratio of a distance between irregularities in an axial direction of the surface layer in the charging member (Sm) to a width of a nodal section of a foam cell wall surface protruding from a surface of the foamed elastic layer in the clean member (W) satisfies 2.4≤Sm/W≤5.9.