Image Reading Apparatus Skew Detection via Background Plate
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Solution Overview
Problem
Existing image reading apparatuses struggle to accurately read images of sheets that are skewed or have high reflectivity, leading to incorrect data acquisition and misidentification of stains due to the sensitivity correction issues and the interference of background plates with low-reflectivity parts.
Innovation Solution
An image reading apparatus with a background plate featuring a diffusing/reflecting part and directional reflecting parts that maintain consistent light intensity, allowing for reliable detection of sheet skew and accurate image acquisition by inhibiting light when no sheet is present and reflecting it when a sheet is in position, thus reducing the impact of sheet orientation and reflectivity on image data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a background plate with low-reflectivity part (black part) is used to detect sheet skew, then the skew detection capability is improved, but the image reading accuracy deteriorates because light passes through thin sheets and reflects off the black part, creating false dark regions that are misidentified as stains
Solution Approach 1:
The background plate is divided into two distinct regions: a white-reference part with high reflectivity and a black-reference part with low reflectivity. Each region serves a specific function - the white part provides a reference for sensitivity correction while the black part enables skew detection. This local differentiation allows the system to simultaneously achieve both accurate image reading and reliable skew detection without the black part's reflected light interfering with the overall image quality.
2Adaptability or versatility
If sheets are transported in various orientations (skewed), then the adaptability of the system is improved, but the image collation accuracy deteriorates because skewed sheet images do not align with reference image data
Solution Approach 1:
The system performs skew detection using the black-reference part before proceeding with image collation. By detecting the sheet's orientation in advance and using this information to correct or adjust the collation process, the system maintains high accuracy even when sheets are transported in various orientations. This preliminary detection and correction approach allows the system to adapt to different sheet orientations while preserving collation precision.
3Illumination intensity
If sheets with high reflectivity are illuminated, then the image brightness is improved, but the contrast between different sheet regions deteriorates, making it difficult to distinguish stains from normal areas
Solution Approach 1:
The background plate acts as an intermediary element that provides a controlled reference background. The white-reference part and black-reference part create a known pattern that helps the sensor distinguish between variations in sheet reflectivity and actual stains. By comparing the sheet image against this controlled background pattern, the system can accurately identify stains even when the sheet itself has high and varying reflectivity.
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 enables reliable detection of sheet skew and accurate image reading, improving the ability to distinguish between sheet edges and stains, and maintaining consistent image quality regardless of sheet orientation or reflectivity.
Implementation Method 1
a background member having a white-reference part provided in a part of a photographing region of the sensor and a black-reference part configured to guide light reflected by the illuminating unit to the sensor
Implementation Method 2
a black-reference part configured to guide light reflected by the illuminating unit to the sensor when a sheet lies in the photographing region of the sensor, and to restrict application of the light reflected by the illuminating unit to the sensor when no sheets lie in the photographing region of the sensor
Data Source
AI summary
An image reading apparatus, in which sheets (8) being transported are illuminated by an illuminating unit, one after another, and a sensor (3) having an imaging elements arranged in a line photographs the sheets (8), one after another. A white-reference part (71) is provided in a part of the photographing region of the sensor (3). A black-reference part (72) guides the light reflected by the illuminating unit to the sensor (3) when a sheet (8) lies in the photographing region of the sensor (3), and to restrict application of the light reflected by the illuminating unit to the sensor (3) when no sheets (8) lie in the photographing region of the sensor (3).