Charging Roll Surface Texture to Prevent Local Discharge Streaking
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Solution Overview
Problem
Image forming apparatuses face challenges in achieving uniform image quality due to uneven discharge between the charging roll and the photoconductor element, which is influenced by the surface roughness of the charging roll.
Innovation Solution
A charging roll design featuring a core member, an electroconductive rubber base material, and a surface layer with specific surface roughness characteristics, including a ten-point height of irregularities (RZ) between 3.9 and 6.1 micrometers and a mean spacing between peaks (Sm) of 12.5 to 13.5 micrometers, is implemented to reduce image unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface roughness of the charging roll is adjusted by use of fine particles in the surface layer, then discharge uniformity is improved, but image unevenness occurs due to local discharge
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness parameters (Rz between 3.9-6.1 μm and Sm between 12.5-13.5 μm) of the charging roll surface layer. This specific parameter range prevents local discharge while maintaining discharge uniformity, thereby resolving the contradiction between discharge uniformity and image unevenness.
2Reliability
If the surface roughness is increased to prevent local discharge, then discharge uniformity improves, but image quality deteriorates due to image unevenness
Solution Approach 1:
The patent resolves this contradiction by optimizing the surface roughness parameters to specific ranges (Rz: 3.9-6.1 μm, Sm: 12.5-13.5 μm). These parameter values are carefully selected to ensure discharge uniformity while preventing image unevenness, thus improving both reliability and image quality simultaneously.
3Manufacturing precision
If the surface layer particles are made finer to reduce surface roughness, then image unevenness is reduced, but discharge uniformity deteriorates due to local discharge
Solution Approach 1:
The patent addresses this contradiction by establishing optimal parameter ranges for surface roughness (Rz: 3.9-6.1 μm, Sm: 12.5-13.5 μm). These parameters balance the competing requirements of image uniformity and discharge uniformity, preventing local discharge while maintaining smooth surface characteristics.
4Ease of manufacture
If the surface roughness parameters are not precisely controlled, then manufacturing is easier, but image quality deteriorates due to uneven discharge
Solution Approach 1:
The patent specifies precise parameter ranges (Rz: 3.9-6.1 μm, Sm: 12.5-13.5 μm) for the surface layer to ensure high image quality. While this requires precise control during manufacturing, it eliminates the need for complex adjustments and rework, ultimately improving ease of manufacture by providing clear manufacturing targets.
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 design ensures uniform discharge and reduces image unevenness, leading to improved image quality by maintaining appropriate surface roughness and preventing local discharge, thereby enhancing the density and consistency of printed images.
Implementation Method 1
An object of JP-A-2015-121769, JP-A-2012-14141 and JP-A-2005-91414 is to control a discharge between the charging roll and the photoconductor element to make the discharge as uniform as possible
Data Source
AI summary
A charging roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The ten point height of irregularities RZ of a surface of the surface layer is equal to or greater than 3.9 micrometers, and is equal to or less than 6.1 micrometers. The mean spacing between peaks Sm of the surface of the surface layer is equal to or greater than 12.5 micrometers and is equal to or less than 13.5 micrometers.