Image Scanner External Light Suppression via Dual Resolution Reading
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Solution Overview
Problem
Conventional image reading apparatuses face inefficiencies in suppressing external light influence, leading to increased reading time and potential errors in document size detection, especially when reading thick documents or with the cover open, as they require reading each line twice and may not correctly remove reflected light due to flicker.
Innovation Solution
An image reading apparatus and control method that employs Light-on and Light-off reading processing modes, using a sensor to read images at different resolutions, and an image processing unit to remove external light influence and specify document boundaries, allowing for efficient suppression of external light effects while maintaining reading speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the cover is closed to suppress external light influence, then external light reflection is reduced, but reading time increases due to manual cover closing operation
Solution Approach 1:
The system performs preliminary reading operations in both Light-on and Light-off modes to capture external light characteristics before the actual reading process, enabling automatic external light removal without requiring manual cover closing operations
Solution Approach 2:
The system converts the harmful effect of external light reflection into a useful signal by reading in Light-off mode to capture external light characteristics, then using this information to automatically remove external light influence from the final image through image processing
2Object-affected harmful factors
If each line is read twice (Light-on and Light-off modes) to remove external light, then external light influence is reduced, but reading time doubles
Solution Approach 1:
The system performs Light-off mode reading at a lower resolution than the final output resolution, reducing the time penalty of the dual-reading approach while still capturing sufficient external light characteristics for effective removal processing
3Adaptability or versatility
If the cover is open to read thick documents, then document accessibility is improved, but external light reflection increases causing detection errors
Solution Approach 1:
The system converts the harmful external light reflection into a measurable signal by reading in Light-off mode, then uses image processing to subtract this external light component from the Light-on mode image, enabling accurate document size detection even with the cover open and thick documents in place
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 reduces external light influence, enabling accurate document size detection and position specification, while minimizing reading time by using different resolutions for Light-on and Light-off modes, thus improving productivity and accuracy.
Implementation Method 1
a light source that emits light toward the original document on the original platen
Implementation Method 2
a sensor that reads an image of the original document on the original platen
Data Source
AI summary
There is provided an image reading apparatus and a control method therefor, which can suppress the influence of external light, and obtain an appropriate read image. To accomplish this, the image reading apparatus executes a Light-on reading processing for turning on an LED and causing a sensor to read an original document on a original platen at the first resolution, and a Light-off reading processing for turning off a light source and causing the sensor to read the original document on the original platen at the second resolution. In accordance with the influence of external light in an Light-off mode image read by the Light-off reading processing, the image reading apparatus removes the influence of external light in a Light-on mode image read by the Light-on reading processing.