Color Shift Correction in Image Forming Apparatus
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Solution Overview
Problem
Image forming apparatuses using laser scanning units face color shifting due to differing magnification in the main scanning direction for each color, which is challenging to address without increasing component disposition constraints and costs, especially when only two alignment sensors are used instead of three.
Innovation Solution
An image forming apparatus that generates a correction sheet with single color regions at different positions, allowing a processor to calculate shift amounts based on RGB luminance values and correct the printer scan position for each color, eliminating the need for an alignment sensor at the center by using two sensors offset from the center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment sensors are disposed at three places including near the center position along the main scanning direction to correct color shifting, then color shift correction accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the alignment sensor from the center position along the main scanning direction, reducing the number of sensors from three to two. The center sensor is removed while maintaining correction capability through alternative positioning of two sensors at other locations, thereby simplifying device structure and reducing cost while preserving color shift correction functionality
Solution Approach 2:
The patent makes the two remaining alignment sensors perform multiple functions: they detect both the main scanning position and the color shift information. By processing the detection results from these two sensors through specific calculations, the system achieves both position alignment and color registration without requiring a dedicated center sensor, thus reducing component count while maintaining correction accuracy
2Measurement precision
If alignment sensors are disposed at three places including near the center position along the main scanning direction to correct color shifting, then color shift correction accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the alignment sensor from the center position along the main scanning direction, reducing the number of sensors from three to two. The center sensor is removed while maintaining correction capability through alternative positioning of two sensors at other locations, thereby simplifying device structure and reducing cost while preserving color shift correction functionality
Solution Approach 2:
The patent replaces the expensive three-sensor configuration with a more economical two-sensor arrangement. By using fewer sensors and eliminating the center sensor, the overall manufacturing cost is reduced while the system maintains adequate correction accuracy through intelligent signal processing and calculation algorithms
3Measurement precision
If three alignment sensors are used to correct color shifting, then color shift correction accuracy is improved, but the number of components increases
Solution Approach 1:
The patent extracts the alignment sensor from the center position along the main scanning direction, reducing the number of sensors from three to two. The center sensor is removed while maintaining correction capability through alternative positioning of two sensors at other locations, thereby simplifying device structure and reducing cost while preserving color shift correction functionality
Solution Approach 2:
The patent merges the functions of multiple sensors into a two-sensor configuration. The two remaining sensors collectively perform the work of what would traditionally require three sensors by working in combination and through coordinated signal processing, thereby reducing the total number of components while maintaining correction 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
Enables accurate color shift correction without a center alignment sensor, reducing component design constraints and costs while maintaining high accuracy even with low-resolution scanners, and allowing for efficient correction by forming a correction image with non-reference color patches between reference colors.
Implementation Method 1
an image reading unit to read the correction sheet
Implementation Method 2
calculate a shift amount in a main scanning direction of the printer unit for each single color region based on RGB luminance values of the single color region
Data Source
AI summary
An image forming apparatus of an embodiment comprises a printer unit to print a sheet with a plurality of single colors and generate a correction sheet including a plurality of single color regions at different positions between a first reference region and a second reference region. The first and second reference regions are a reference color. An image reading unit is configured to read the correction sheet. A processor is configured to calculate a shift amount in a main scanning direction of the printer unit for each single color region based on RGB luminance values obtained from the correction sheet by the image reading unit and to correct a printer scan position along the main scanning direction for each single color in the plurality of single colors corresponding to the single color regions using calculated shift amounts.