Charge Roller Stage Differences for Uniform Charging
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining uniform charge distribution due to variations in the gap between the photosensitive member and the charge roller, leading to charge irregularities and increased production costs for high-precision components.
Innovation Solution
A charge member with a rotatable roller surface featuring circumferential fluctuations of 4 to 80 μm and stage differences of 2 to 30 μm, arranged without contact with the photosensitive member, applies AC voltage superimposed on DC voltage to reduce charge irregularities while using an inexpensive charge member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a smooth charge roller surface is used to maintain constant relative position, then charge uniformity is improved, but manufacturing precision requirements increase and production costs rise
Solution Approach 1:
The charge roller surface is designed with localized stage differences (2-30 μm height variations) distributed across the surface, creating different local properties rather than uniform smoothness. This allows the surface to compensate for photosensitive member fluctuations locally, maintaining charge uniformity without requiring high overall manufacturing precision
Solution Approach 2:
The invention changes the surface topology parameter from completely smooth to having controlled stage differences. By introducing these micro-unevenness features with specific height ranges (2-30 μm) and densities (5-30 lines per 0.5mm circumferential distance), the system transforms the charge distribution mechanism to accommodate photosensitive member variations
2Productivity
If the gap between photosensitive member and charge roller is increased to allow discharge, then charging efficiency is improved, but charge density decreases
Solution Approach 1:
The stage differences create localized regions with varying gap distances between the charge roller and photosensitive member. Some regions have smaller effective gaps that concentrate discharge and achieve high charge density, while other regions provide sufficient spacing for discharge occurrence
Solution Approach 2:
The periodic stage differences around the charge roller circumference create alternating regions of high and low discharge activity. As the photosensitive member rotates, it passes through these periodic variations, receiving cumulative charging effects that maintain both efficiency and density
3Duration of action of stationary object
If AC voltage is superimposed on DC voltage to enable non-contact charging, then photosensitive member lifespan is extended, but charge irregularities increase due to gap variations
Solution Approach 1:
The stage differences create localized discharge paths that are less sensitive to overall gap variations. By concentrating discharge in specific regions where the gap is optimally sized, the system maintains charge uniformity even when the average gap varies due to photosensitive member fluctuations
Solution Approach 2:
The stage differences act as a passive feedback mechanism that automatically compensates for gap variations. When the gap increases, discharge occurs at the convex stage differences; when the gap decreases, discharge occurs at less pronounced stages, self-regulating the charge distribution
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 effectively minimizes charge irregularities and extends the lifespan of the charge member and photosensitive member, reducing production costs and maintaining high image quality without generating excessive ozone.
Implementation Method 1
discharge begins at 20 μm or more, and with a gap of 20 μm or more, the density of the discharge becomes smaller the wider the gap
Implementation Method 2
charge rollers have come to be used for the charge member in order to reduce the generation of harmful gases such as ozone and nitrous oxides (NOx)
Data Source
AI summary
A charge member that can reduce charge irregularities of a member to be charged caused by variations in the gap between the member to be charged and the charge member even when using a member to be charged (photosensitive member, and the like) that has circumferential fluctuations. The charge member which is arranged electrically without making contact with the member to be charged, and which charges the member to be charged by applying AC voltage superimposed on DC voltage, and which is formed of a rotatable roller, is arranged electrically without making contact with the member to be charged having circumferential fluctuations of 4 to 80 μm within the image formation area, and which has a plurality of stage differences with a height difference of 2 to 30 μm on the surface of the roller; and the stage differences in the area opposing the member to be charged are five to thirty in relation to a distance of 0.5 mm in the circumferential direction of the roller. Charging without charge irregularities is thereby possible.