Image Forming Apparatus Trailing Edge Density Correction
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Solution Overview
Problem
Existing image forming apparatuses face high computational loads due to repetitive processing required to correct density variations caused by sweeping, which occurs when the surface speed of the developing roller exceeds that of the photosensitive drum, leading to image degradation and inefficient toner usage.
Innovation Solution
An image forming apparatus that determines a fixed correction amount of light for the trailing edge of an image based on the number of downstream pixels, smoothly reducing this correction amount over a predetermined region width from the leading edge side to the trailing edge side, thereby correcting density increases without repetitive processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If repetitive correction processing is performed to correct density variations caused by sweeping, then image quality is improved, but processing load increases
Solution Approach 1:
The patent applies preliminary action by calculating and storing the relationship between the number of downstream pixels and correction amounts in advance, before actual image processing. This pre-calculated data is then referenced during image formation to determine correction amounts without requiring repetitive complex calculations, thus improving image quality while reducing processing load during operation
Solution Approach 2:
The patent uses copying by creating a lookup table that stores pre-calculated correction amount data based on the number of downstream pixels. Instead of performing repetitive correction calculations for each pixel, the system copies and applies the appropriate correction amount from the stored table, significantly reducing computational load while maintaining correction effectiveness
2Manufacturing precision
If light amount is reduced for sweeping regions, then density increase is corrected, but new density increases occur in previously flat regions
Solution Approach 1:
The patent applies local quality by determining correction amounts based on the specific number of downstream pixels for each pixel position. This localized approach adjusts the correction amount according to the actual sweeping condition at each location, correcting density increases in sweeping regions while avoiding excessive correction that would create new density variations in non-sweeping regions
Solution Approach 2:
The patent uses feedback by considering the number of downstream pixels when determining correction amounts. This feedback mechanism allows the system to adapt the correction strength based on the actual sweeping condition, preventing over-correction that would create new density variations while ensuring adequate correction where sweeping occurs
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 effectively reduces processing load and improves image reproducibility by correcting density variations caused by sweeping, ensuring consistent print quality without excessive toner consumption.
Implementation Method 1
an exposure unit configured to expose the photosensitive drum to form an electrostatic latent image on a surface of the photosensitive drum
Implementation Method 2
a developing roller configured to develop the electrostatic latent image formed on the surface of the photosensitive drum by using a developer
Data Source
AI summary
An image forming apparatus obtains a number of pixels to be developed on a downstream side in a sub-scanning direction from each one of the predetermined pixels, in order to correct a density increase that occurs at the trailing edge of an image to be formed in accordance with a peripheral speed difference between a photosensitive drum and a developing roller, determines a correction amount of light amount for each one of the predetermined pixels in accordance with the obtained number of pixels, and generates image formation data.