Image Reading Apparatus Abnormal Reflection Correction
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Solution Overview
Problem
Image reading apparatuses struggle to obtain normal image data when scanning documents with unevenness and gloss, as existing technologies fail to effectively handle halation and abnormal light reflections.
Innovation Solution
An image reading apparatus equipped with a light emitting diode (LED) light source, a carriage for moving along a sub-scanning direction, light receiving elements, a clamp circuit for signal processing, and an image correction unit that compares first and second image data to detect and correct abnormal document areas by adjusting brightness levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the carriage moves in the sub-scanning direction to read the document image, then the document image can be captured, but abnormal reflected light occurs due to document unevenness and gloss causing halation
Solution Approach 1:
The patent applies preliminary action by performing multiple readings of the same document line at different positions before finalizing the image data. The carriage reads the document line multiple times while being positioned at different locations (first position, second position, third position), and the control unit selects appropriate data from these preliminary readings to construct the final image, thereby preventing the harmful effect of abnormal reflected light from document unevenness and gloss.
2Measurement precision
If multiple readings are performed at different carriage positions to correct abnormal light reflections, then image data accuracy improves, but reading time increases
Solution Approach 1:
The patent applies partial action by performing multiple readings only at specific critical positions (first, second, and third positions along the sub-scanning direction) rather than continuously throughout the entire reading process. The control unit selectively uses data from these partial readings to correct abnormal reflected light areas, achieving improved image accuracy without the excessive time cost of complete multiple-pass reading of the entire document.
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 apparatus successfully obtains normal image data even from documents with unevenness and gloss by detecting and correcting abnormal light reflections, ensuring accurate image capture and processing.
Implementation Method 1
a light emitting diode (LED) configured to illuminate capturing light onto the document
Implementation Method 2
condenses the reflected light to a photoelectric conversion element such as a Charge Coupled Device (CCD) image sensor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An image reading apparatus (2) is configured to: detect a document area where the reflected light is abnormal by comparing first image data (Da) with second image data (Db); and replace the first image data (Da) corresponding to the abnormal document area with third image data (Dc). The first image data (Da) is generated by movement of the carriage (35) in a sub-scanning direction of a first direction. The second image data (Db) is generated by movement of the carriage (35) in the sub-scanning direction of a second direction at a reduced luminescence level of the capturing light illuminated on the document compared with a luminescence level in the movement of the carriage (35) in the first direction. The third image data (Dc) is the second image data (Db) where at least brightness is adjusted.