Dual Illumination Image Reading Apparatus for Crease Detection
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Solution Overview
Problem
Conventional sheet processing apparatuses face challenges in accurately identifying creases and folds in sheets due to uniform illumination, which prevents the casting of shadows and subsequent detection of these features.
Innovation Solution
The apparatus employs a dual illumination system with visible and infrared light sources positioned on both sides of the imaging optical axis, allowing for non-uniform illumination that enhances the visibility of creases and folds, enabling accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the sheet is illuminated from both sides of the reading optical axis to achieve uniform illumination, then the uniformity of light intensity is improved, but the ability to detect creases and folds deteriorates
Solution Approach 1:
The illumination apparatus dynamically switches between two illumination modes: a first illumination mode that provides uniform illumination from both sides for general imaging, and a second illumination mode that provides non-uniform illumination from one side for detecting creases and folds. This dynamic switching allows the system to adapt to different detection requirements.
Solution Approach 2:
The system applies partial illumination action by selectively activating only one illumination unit at a time during the second illumination mode, rather than illuminating from both sides simultaneously. This partial action creates the necessary non-uniform lighting conditions for shadow-based detection of sheet defects.
2Productivity
If the sheet is conveyed at high speed to improve productivity, then the processing efficiency is improved, but the occurrence of flapping increases which deteriorates reading accuracy
Solution Approach 1:
The system dynamically adjusts illumination based on sheet position detection. When flapping is detected during high-speed conveyance, the illumination apparatus switches to the second illumination mode that is more tolerant of position variations, maintaining reading accuracy despite speed-induced instability.
Solution Approach 2:
The system uses feedback from position detection to control illumination mode selection. The detection unit monitors sheet position, and based on this feedback, the illumination apparatus adjusts its operation mode to compensate for flapping effects, ensuring accurate reading even at high conveyance speeds.
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 more accurate identification of sheet features like creases and folds, improving the overall image reading accuracy and processing capabilities.
Implementation Method 1
The image reading apparatus has an illumination unit (illuminating apparatus) and a line image sensor. The image reading apparatus irradiates a sheet with light from the illumination unit.
Implementation Method 2
The line image sensor of the image reading apparatus reads reflected light from the conveyed sheet and detects optical features (characteristics) of that sheet.
Data Source
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AI summary
According to one embodiment, an image reading apparatus that reads an image of a sheet (1) conveyed by a conveyance unit (12) includes a first illumination unit (21) to irradiate the sheet (1) with visible light, a second illumination unit (22) to irradiate the sheet with visible light and infrared light from an angle different from that of the first illumination unit (21), and an imaging unit (23) to receive visible light and infrared light reflected from the sheet (1) and to capture a visible image and an infrared image.