Image Forming Apparatus Shading Correction via Scan Speed Interpolation
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Solution Overview
Problem
Image forming apparatuses face challenges in maintaining uniform light intensity across different scan speeds, leading to density unevenness in images due to the optical characteristics of the light scanning device, which existing shading correction methods fail to adequately address without increasing memory capacity and cost.
Innovation Solution
An image forming apparatus that uses light intensity correction data stored for a first scan speed to adjust the light intensity of a light beam during scanning at a second scan speed, by calculating and interpolating shading data to maintain consistent correction across varying scan speeds, reducing the need for extensive memory storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shading correction data is stored for each scan speed, then shading correction precision is improved, but memory capacity and cost increase
Solution Approach 1:
The patent makes a single set of shading correction data (stored at first scan speed) serve multiple scan speeds through speed ratio calculation and interpolation. Instead of having separate correction data for each scan speed, the system uses one universal correction dataset that can be adapted to any scan speed by applying the speed ratio, thereby reducing memory requirements while maintaining correction precision across different operating conditions
Solution Approach 2:
The patent changes the parameter of scan speed ratio to adapt the fixed shading correction data to different scan speeds. By calculating the ratio between the first scan speed and the current scan speed, and using this ratio to interpolate correction values from the stored data, the system dynamically adjusts the correction application without needing separate correction datasets for each speed
2Adaptability or versatility
If the light beam is scanned at different scan speeds, then adaptability to various sheet types is improved, but light intensity uniformity deteriorates
Solution Approach 1:
The patent changes the scan speed parameter while maintaining light intensity uniformity through interpolated correction. The system allows scan speed to vary according to sheet type requirements (improving adaptability) while simultaneously adjusting the light intensity correction based on the speed ratio calculation, thereby compensating for optical characteristic variations and maintaining uniformity across different scan speeds
3Device complexity
If shading correction is executed with fixed period Td, then correction timing is simplified, but correction accuracy deteriorates when scan speed changes
Solution Approach 1:
The patent introduces dynamic adjustment to the fixed period Td by applying the scan speed ratio. While the base period Td remains constant (maintaining simplicity), the actual correction timing is dynamically scaled by the speed ratio to match the current scan speed, ensuring that correction occurs at the appropriate moment regardless of speed variations, thereby maintaining both simplicity and accuracy
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 corrects light intensity variations across different scan speeds, improving image quality by reducing density unevenness without increasing memory requirements or costs, enabling the apparatus to handle multiple image forming speeds efficiently.
Implementation Method 1
a light source configured to emit a light beam
Implementation Method 2
a deflector configured to deflect the light beam emitted from the light source so that the light beam is scanned on the photosensitive member
Data Source
AI summary
An image forming apparatus including: a setting unit configured to set light intensity correction data stored in a storage unit according to an exposure position while a light beam is being scanned on a photosensitive member at a first scan speed; and a light intensity controller configured to control a light intensity based on the correction data set by the setting unit, wherein the setting unit calculates a light intensity correction data corresponding to a position between a plurality of positions based on the stored correction data, set the correction data according to the exposure position while the light beam is being scanned at a second scan speed lower than the first scan speed; and fixes a switching period for switching the correction data according to the exposure position while the light beam is being scanned on an image forming area of the photosensitive member regardless of the scan speed.