Image Reading Apparatus Sub-Scanning Color Shift Correction
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Solution Overview
Problem
Existing image reading apparatuses face challenges in correcting sub-scanning color shifts caused by various factors, including fluctuations in scanning speed and focal point shifts, which can lead to inaccurate color representation and misreading of monochromatic lines as color lines.
Innovation Solution
An image reading apparatus equipped with a reader unit having multiple line sensors, a storage unit for correction conditions, a determining unit to assess the need for correction, and a corrector to adjust the read data based on the determination, ensuring accurate color alignment and correction of sub-scanning color shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple line sensors are arranged at given intervals in the sub-scanning direction to read color images, then color image reading capability is improved, but sub-scanning color shifts occur due to scanning speed fluctuations and focal point shifts
Solution Approach 1:
The patent applies preliminary action by detecting sub-scanning color shifts and performing corrections on read data before final image processing. The determining unit identifies the presence of color shifts in advance, and the corrector pre-adjusts the read data to compensate for these shifts, ensuring accurate color alignment in the final output.
Solution Approach 2:
The patent implements feedback by using detected sub-scanning color shift information to adjust and correct read data. The determining unit continuously monitors for color shifts, and when detected, the corrector applies corrections based on this feedback, creating a closed-loop system that maintains color alignment accuracy despite scanning variations.
2Measurement precision
If read data is corrected for sub-scanning color shifts, then color alignment accuracy is improved, but processing time and computational complexity increase
Solution Approach 1:
The patent applies partial action by selectively correcting only those read data portions that contain sub-scanning color shifts. The determining unit identifies specific regions with color shift issues, and the corrector applies corrections only to these affected areas rather than processing the entire image, thereby reducing overall processing time while maintaining color alignment accuracy where needed.
3Ease of manufacture
If three light receiving element lines are arranged in the sub-scanning direction with gaps between them, then color separation for R, G, B reading is achieved, but reading points for different colors are not at the same location simultaneously
Solution Approach 1:
The patent applies preliminary action by detecting the positional offsets between reading points of different colors and pre-calculating correction amounts. The determining unit identifies the misalignment caused by the physical gaps between light receiving element lines, and the corrector applies preliminary corrections to compensate for these fixed offsets, ensuring that color information from different lines is properly aligned in the final image.
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
The solution effectively corrects sub-scanning color shifts, preventing tinting and ensuring accurate color representation by aligning R, G, and B read data, thereby improving the reliability of image reading processes.
Implementation Method 1
The light receiver includes as a light receiving element a photoelectric conversion element, for example. The photoelectric conversion element is built by, for example, forming an R (red) color filter, a G (green) color filter, and a B (blue) color filter through application on a light receiving surface
Implementation Method 2
The color filters separate the colors of light diffused by an original, and the light receiving elements receive the light passing through the color filters
Data Source
AI summary
An image reading apparatus includes a front-side reader, which includes a white LED configured to irradiate an original with light and a CMOS sensor configured to receive light that is reflected by the original. The front-side reader is configured to generate read data that represents a luminance value of an image on the original from the result of receiving light with the CMOS sensor. The image reading apparatus stores, in a non-volatile memory, a condition for determining whether there is a sub-scanning color shift, and uses a sub-scanning color shift detector to determine whether there is a sub-scanning color shift based on the read data obtained from the front-side reader and the condition stored in the non-volatile memory. When there is a sub-scanning color shift, the image reading apparatus corrects the sub-scanning color shift by correcting the read data with a color shift corrector.