Document Size Detection Using Segmented Reference Patterns
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Solution Overview
Problem
Conventional image reading apparatuses struggle to accurately detect the size of transparent or semi-transparent documents due to interference from patterns on the document cover, and fail to differentiate between document edges and background patterns with similar colors.
Innovation Solution
The apparatus employs a document table with a first and second scanning direction, utilizing a light receiving unit and reference areas with different patterns to detect border positions and calculate document size, ensuring accurate detection even with transparent or semi-transparent documents by using a light quantity-based method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single belt-shaped pattern is used on the document table, then the device complexity is reduced, but the measurement precision of document size detection deteriorates when the document background is similar to the pattern color
Solution Approach 1:
The single belt-shaped pattern is segmented into multiple patterns (first belt-shaped pattern and second belt-shaped pattern) with different colors or luminance values. This segmentation allows the system to detect document edges more reliably by comparing against multiple reference patterns, preventing misidentification when document background color resembles one of the patterns.
Solution Approach 2:
Different regions of the document table are assigned different pattern characteristics (first pattern with specific color/luminance, second pattern with different color/luminance). This local quality variation ensures that at least one pattern will provide sufficient contrast against any given document background, maintaining detection precision without requiring complex global changes.
2Ease of operation
If a pattern is provided on the document cover pressing surface, then the document positioning is improved, but the measurement precision deteriorates for transparent or semi-transparent documents due to pattern interference
Solution Approach 1:
The detection system uses reflected light from the document table patterns as an intermediary to indirectly determine document edges. By detecting the presence or absence of pattern reflections in the captured image, the system can identify document boundaries without the pattern being in direct contact with the document, thus avoiding interference with transparent documents.
Solution Approach 2:
The mechanical contact-based detection (pattern on pressing surface) is replaced with an optical detection method using reflected light from the document table patterns. This substitution allows the system to maintain positioning functionality while eliminating the interference problem caused by direct pattern contact with transparent documents.
3Ease of manufacture
If the document table has a simple structure without multiple patterns, then the manufacturing cost is reduced, but the detection accuracy deteriorates when documents have backgrounds similar to the pattern
Solution Approach 1:
The document table pattern is segmented into multiple distinct patterns (first and second belt-shaped patterns with different characteristics). This segmentation provides multiple reference points for edge detection, ensuring that at least one pattern will have sufficient contrast against any document background, thereby maintaining detection accuracy.
Solution Approach 2:
The document table incorporates multiple pattern types with different optical properties (colors, luminance values) into a single structure. This composite approach ensures diverse contrast characteristics that can accommodate various document backgrounds, improving detection robustness without significantly complicating manufacturing.
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 enhances the accuracy of document size detection by distinguishing between reference areas and document edges, effectively addressing the limitations of previous methods and improving detection precision for non-standard document sizes.
Implementation Method 1
a light receiving unit that is provided to face one surface of the document placed on the placing surface, and receives reflected light of light emitted to the placing surface
Data Source
AI summary
A first positioning member is provided on a document table to extend in a first scanning direction and determines a position in a second scanning direction of an edge of a document placed on the placing surface. A first reference area holding member extends from a first positioning member over the placing surface and holds, on its surface opposing the placing surface, two reference areas extending parallel to the first scanning direction and including a first and second reference areas each having a different pattern from each other. A border position in the first scanning direction between at least one of the first and second reference areas and the document is detected, based on a received light quantity of reflected light. A size determining unit calculates a document length in the first scanning direction based on the detected border position.