Document Image Length Correction Using Protective Sheet Ratio
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Solution Overview
Problem
Conventional imaging devices using protective sheets to convey documents often result in a mismatch between the actual document length and the document image length due to differences in thickness and friction coefficients, leading to inaccuracies in image conveying direction length.
Innovation Solution
An information processing device that acquires scanned images of documents and protective sheets, estimates the ratio between the conveying direction lengths of the document and its image by comparing the lengths of the protective sheet and the scanned image, and corrects the document image length to match the actual length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a protective sheet is used to sandwich the document during conveying, then the document is protected from damage, but the conveying direction length of the image becomes different from the actual conveying direction length of the document
Solution Approach 1:
The protective sheet acts as an intermediary between the conveying mechanism and the document. By measuring the conveying length of the protective sheet (which has different friction properties) and using it to calculate a correction ratio, the system compensates for the length discrepancy introduced by the protective sheet, thereby maintaining image length accuracy while preserving document protection
Solution Approach 2:
The system changes the parameter being measured from the document itself to the protective sheet. Since the protective sheet's conveying length can be measured and its friction characteristics are different from the document, using it as the measurement target allows calculation of a correction ratio that accounts for the length discrepancy, thus resolving the precision issue while maintaining protection
2Productivity
If imaging is performed while the document is being conveyed, then productivity is improved, but length mismatch occurs between the actual document length and the document image length
Solution Approach 1:
The system implements feedback by measuring the actual conveying length of the protective sheet during the imaging process, calculating a correction ratio based on this measurement, and applying this ratio to correct the document image length. This closed-loop approach maintains imaging efficiency while ensuring length accuracy through continuous measurement and correction
3Productivity
If the conveying speed is increased for higher productivity, then the imaging throughput improves, but the friction difference between protective sheet and document causes greater length mismatch
Solution Approach 1:
The system performs preliminary measurement of the protective sheet's conveying length before final image processing. By calculating the correction ratio in advance based on the protective sheet's measured length, the system prepares the correction factor that will be applied to the document image, ensuring accuracy is maintained even at higher conveying speeds
Data Source
AI summary
An information processing device executes: acquiring a scanned image of a document and a protective sheet that protects the document, the scanned image being obtained by imaging the document and the protective sheet while being conveyed at the same time; acquiring a first length that is a conveying direction length of a predetermined portion of the protective sheet; acquiring a second length that is a conveying direction length of the predetermined portion in the scanned image; and estimating a ratio between a document length, which is a conveying direction length of the document, and a document image length, which is a conveying direction length of the document in the scanned image, based on the first length and the second length.