Image Forming Apparatus: Coverage-Based Aging for Surface Potential
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Solution Overview
Problem
Conventional image forming apparatuses using electrophotographic systems face issues with non-uniform surface potential of the image carrier due to varying carrier quantities generated by triboelectrification, leading to bands and stripes in printed images.
Innovation Solution
Implement an aging process where the image carrier is rotated under light irradiation by the exposure unit, adjusting the light quantity based on the average coverage rate to uniformize the surface potential, by setting a higher light quantity for areas with higher coverage rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the image carrier is charged by triboelectrification during rotation, then the surface becomes electrically charged for image formation, but non-uniform surface potential occurs due to varying carrier quantities in different areas
Solution Approach 1:
The patent applies preliminary anti-action by exposing areas with higher coverage rates to greater light quantities during the aging process before actual image formation. This pre-compensates for the excessive carrier generation that would otherwise occur in these areas during charging, thereby preventing the non-uniform surface potential and image defects that would result from the triboelectrification process.
Solution Approach 2:
The patent changes the light quantity parameter during the aging process based on coverage rate areas. By adjusting the exposure intensity according to the specific area's coverage characteristics, the method modifies the physical state of the photosensitive layer to counterbalance the upcoming triboelectrification effects, ensuring uniform surface potential across different regions.
2Ease of operation
If uniform light quantity is applied during aging process, then the process is simple to control, but it cannot compensate for coverage rate differences and fails to uniformize surface potential
Solution Approach 1:
The patent applies local quality by differentiating the light quantity applied during aging based on the coverage rate characteristics of different areas. Instead of uniform treatment, each area receives a customized light quantity proportional to its coverage rate, making the aging process adaptive to local conditions and enabling effective compensation for carrier quantity variations.
3Manufacturing precision
If higher light quantity is applied to areas with larger coverage rates during aging, then surface potential uniformity is improved, but energy consumption increases
Solution Approach 1:
The patent optimizes energy usage by dynamically adjusting the light quantity parameter during aging based on actual coverage rate requirements. Areas with higher coverage rates receive proportionally higher light quantities only when needed, while other areas receive appropriate but reduced exposure. This parameter adaptation ensures surface potential uniformity is achieved with minimal necessary energy consumption.
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 maintains uniform surface potential of the image carrier, ensuring stable image quality by minimizing potential variations and preventing bands and stripes.
Implementation Method 1
an electrostatic latent image is formed by exposure of the LSU
Implementation Method 2
the cylindrical-shaped image carrier is rotated to make a surface of the image carrier electrically charged by the charging unit
Data Source
AI summary
The image forming apparatus includes an image carrier, a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning blade, and a controller. The controller detects printing-coverage rates on a basis of plural areas divided in the longitudinal direction of the image carrier. At a specified timing, the controller executes aging process in which the image carrier in a charged state is driven into rotation under light irradiation by the exposure unit. For the aging process, the controller sets a condition that a light quantity of the exposure unit for an area of larger coverage rate is larger than a light quantity of the exposure unit for an area of smaller coverage rate.