Image Reading Apparatus Shading Correction Switching
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Solution Overview
Problem
Existing image reading apparatuses face challenges in accurately determining and correcting for external light influence, which affects scanning quality due to varying structures and external light intensities, leading to inconsistent shading corrections.
Innovation Solution
The image reading apparatus includes a reading unit with distinct regions for external light suppression and a controller that calculates external light intensity based on reading values, switching between first and second shading corrections depending on whether the intensity exceeds a threshold, ensuring appropriate shading correction according to the apparatus's structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single shading correction method is used for all conditions, then the device structure is simple, but the scanning quality deteriorates under varying external light conditions
Solution Approach 1:
The patent implements dynamic switching between first and second shading correction methods based on external light intensity detection. The controller selects the appropriate correction method in real-time according to measured external light conditions, making the shading correction system adaptive rather than static. This resolves the contradiction by allowing the system to maintain high scanning quality across varying conditions without requiring multiple permanently configured correction systems.
Solution Approach 2:
The patent changes the correction parameters (shading correction data) based on external light intensity thresholds. When external light exceeds the threshold, the system applies first shading correction data; when below the threshold, it applies second shading correction data. This parameter-based switching enables the system to adapt to different lighting conditions while maintaining a unified correction framework, resolving the contradiction between reliability and complexity.
2Measurement precision
If external light measurement is performed continuously, then external light influence is accurately determined, but energy consumption and processing time increase
Solution Approach 1:
The patent performs external light measurement as a preliminary step before actual document scanning. By measuring external light intensity in advance and determining whether it exceeds the threshold before the main scanning operation, the system avoids continuous measurement during scanning. This preliminary action ensures accurate external light assessment while minimizing time loss, as the measurement is performed once per scanning session rather than continuously.
3Measurement precision
If the threshold value for external light is set low, then shading correction accuracy is improved, but the frequency of switching to first correction method increases, reducing productivity
Solution Approach 1:
The patent establishes an appropriate external light threshold value that balances correction accuracy and productivity. By carefully selecting the threshold, the system ensures that the first shading correction method is applied only when genuinely necessary (when external light actually degrades quality), rather than switching frequently due to an overly sensitive threshold. This parameter optimization resolves the contradiction by finding the optimal balance point.
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 allows for precise determination of external light intensity and effective shading correction, enhancing scanning quality by adapting to the specific structural features of the apparatus and minimizing external light interference.
Implementation Method 1
a reading unit (31) performing reading according to an amount of light received
Data Source
AI summary
The image reading apparatus includes a reading unit, a reading region in which a first region in which a member that suppresses entry of external light is disposed and a second region other than the first region are arranged in a main scanning direction of the reading unit, and a controller, wherein the controller calculates intensity of external light in the second region based on a reading value in the reading region, wherein the reading value is obtained by the reading unit, determines whether the intensity of the external light exceeds a threshold value, performs a first shading correction on a reading value of a document transported to the reading region when the intensity of the external light exceeds the threshold value, and performs a second shading correction on the reading value of the document when the intensity of the external light does not exceed the threshold value.