Image Forming Apparatus Potential Correction for Density Uniformity
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Solution Overview
Problem
The a-Si photoconductive body used in electrophotographic image forming apparatuses experiences potential irregularities due to film thickness and quality irregularities, leading to density irregularities in the images formed, which are exacerbated by post-charge potential attenuation and optical memory effects, making it challenging to maintain image quality over time and in varying use environments.
Innovation Solution
An image forming apparatus and method that includes characteristic storing means to record initial potential characteristics, potential characteristic correcting means to compensate for differences in potential characteristics, and transfer means to ensure uniform toner image transfer, using a potential characteristic obtaining step and characteristic difference calculating step to adjust exposure values based on stored data to correct potential irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a-Si photoconductive body is used for high-speed copying and laser beam printing, then high surface hardness and high sensitivity to semiconductor laser are achieved, but potential irregularity of about 20 volts occurs at developing locations causing density irregularity
Solution Approach 1:
The patent applies local quality by storing potential characteristic data for different regions of the photoconductive body and applying region-specific correction values. The correction unit adjusts exposure amounts based on location-specific potential characteristics, making each region have optimized local properties rather than requiring uniform properties across the entire surface.
Solution Approach 2:
The patent changes the exposure amount parameter dynamically based on stored potential characteristic data. By adjusting the exposure parameter according to location-specific potential characteristics, the system compensates for manufacturing variations and maintains uniform image density despite inherent potential irregularities in the a-Si photoconductive body.
2Measurement precision
If a-Si photoconductive body is used, then high sensitivity to semiconductor laser is achieved, but much larger post-charge potential attenuation occurs compared to OPC photoconductive body
Solution Approach 1:
The patent performs preliminary action by storing potential characteristic data before actual image formation occurs. The system pre-characterizes the photoconductive body's potential attenuation behavior at different locations and stores this data for later correction, allowing proactive compensation rather than reactive adjustment.
Solution Approach 2:
The patent implements feedback by using stored potential characteristic data to correct exposure amounts in real-time during image formation. The correction unit continuously references the stored characteristics and adjusts exposure parameters accordingly, creating a closed-loop system that compensates for potential attenuation variations.
3Loss of information
If pre-exposure is carried out to erase optical memory, then optical memory elimination is achieved, but potential irregularity remains due to film thickness and quality differences
Solution Approach 1:
The patent applies local quality by implementing location-specific exposure correction. Instead of relying solely on uniform pre-exposure to eliminate optical memory, the system stores and applies region-specific correction values that account for local film thickness and quality variations, ensuring uniform potential distribution despite manufacturing imperfections.
Solution Approach 2:
The patent uses a composite approach by combining pre-exposure with subsequent correction based on stored potential characteristics. The system integrates multiple methods (pre-exposure plus location-specific exposure adjustment) to achieve both optical memory elimination and potential uniformity, leveraging the strengths of each approach.
4Loss of information
If uniform pre-exposure is applied to erase optical memory, then optical memory is eliminated, but charging ability difference becomes conspicuous due to capacitance variation from film thickness irregularity
Solution Approach 1:
The patent applies local quality by storing charging characteristic data for different regions and applying location-specific exposure correction. The correction unit adjusts exposure amounts based on region-specific capacitance and charging characteristics, compensating for film thickness variations and maintaining uniform charging across the entire photoconductive body surface.
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 allows for the formation of images without density irregularities by compensating for potential differences, ensuring consistent image quality even as the photoconductive body characteristics change over time, thereby stabilizing image output.
Implementation Method 1
an image supporting body for forming an electrostatic latent image thereon
Implementation Method 2
a charge-injection blocking layer having a charge-injection blocking capability of blocking charges from being injected from the conductive support to the photoconductive layer
Implementation Method 3
The toner image on the photoconductive body is transferred onto the surface of the recording material by passing the recording material through the transfer section while supplying the transfer component with a transfer bias voltage opposite in polarity to the toner image on the photoconductive body
Data Source
AI summary
An image forming apparatus includes an electrophotographic photoconductive body for forming an electrostatic latent image thereon; an exposure device for exposing the electrophotographic photoconductive body to form an electrostatic latent image; a storage device for storing information related to potential characteristics at a plurality of areas divided on a surface of the electrophotographic photoconductive body in advance; an information obtaining device for obtaining the information related to potential characteristics, wherein light quantities exposed by the exposure device are determined according to the information related to potential characteristics stored by the storage device and the information related to potential characteristics obtained by the information obtaining device.