Sheet Feeding Apparatus Ultrasonic Sensor Double Feeding Detection
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Solution Overview
Problem
Conventional sheet feeding apparatuses may erroneously judge double feeding when a single thick sheet or a carrier sheet comprised of multiple sheets is fed, as they rely solely on changes in physical quantities for judgment.
Innovation Solution
A sheet feeding apparatus with a combination of a sheet feeding mechanism, a sheet sensor to detect physical quantities, a physical-quantity judgment section, an another-sheet judgment section, and a double-feeding judgment section that differentiates between single and multiple sheets based on detection values and presence of additional sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If double feeding is judged based on change of physical quantity (ultrasonic wave attenuation) alone, then double feeding detection capability is improved, but erroneous judgment occurs when single thick sheet or carrier sheet is fed
Solution Approach 1:
A sheet separation determination section is introduced as an intermediary between the physical quantity detection and double feeding judgment. This intermediary section determines whether sheets are properly separated before the double feeding judgment is made, even when physical quantity changes suggest double feeding. This resolves the contradiction by adding a mediating judgment layer that prevents erroneous detection of thick sheets or carrier sheets as double feeding.
2Device complexity
If only physical quantity detection is used for sheet monitoring, then device complexity is reduced, but ability to distinguish single thick sheet from multiple sheets deteriorates
Solution Approach 1:
The detection system is segmented into multiple independent functional sections: a sheet separation determination section that assesses whether sheets are properly separated, and a double feeding judgment section that makes the final determination. This segmentation allows the system to use simple physical quantity detection while adding a separate logical layer for accurate sheet quantity discrimination, resolving the contradiction between simplicity and precision.
3Reliability
If dual judgment system (physical quantity + sheet separation) is implemented, then judgment accuracy is improved, but device complexity increases
Solution Approach 1:
The sheet separation determination and double feeding judgment functions are merged into an integrated control flow within the control unit. Rather than implementing completely separate physical systems, the patent combines multiple judgment criteria (physical quantity changes and sheet separation status) into a unified logical judgment process, achieving high reliability while minimizing the increase in device complexity.
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
Prevents erroneous double feeding judgments by accurately distinguishing between single thick sheets and multiple sheets, improving the accuracy of sheet feeding operations.
Implementation Method 1
The ultrasonic sensor includes an ultrasonic generator and an ultrasonic receiver disposed opposite to each other with a sheet feeding path interposed therebetween. An amount of attenuation of an ultrasonic wave in the sheet is different between feeding of a single sheet between the ultrasonic generator and the ultrasonic receiver and feeding of a plurality of sheets therebetween.
Data Source
AI summary
A sheet feeding apparatus, including: a sheet feeding mechanism; a sheet sensor for detecting, as a detection value, a physical quantity related to a fed sheet; a physical-quantity judgment section for judging whether the detection value falls within a predetermined range; an another-sheet judgment section for judging whether there is another sheet after a sheet to be judged by the physical-quantity judgment section; and a double-feeding judgment section for judging that double feeding has occurred when the physical-quantity judgment section judges that the detection value does not fall within the predetermined range and when the another-sheet judgment section judges that there is another sheet, and judging that the double feeding has not occurred when the physical-quantity judgment section judges that the detection value does not fall within the predetermined range and when the another-sheet judgment section judges that there is no another sheet.