Sheet Conveyance Double-Feed Detection via Adaptive Length Thresholds
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Solution Overview
Problem
Existing sheet conveying apparatuses struggle to accurately determine double-feed states, leading to potential damages such as tearing and folding of sheets, and page dropouts in image reading applications.
Innovation Solution
A sheet conveying apparatus equipped with a double-feed sensor and a controller that determines double-feed occurrence based on the double-feed length, sheet size, and predetermined distances, allowing for accurate detection and prevention of double-feed-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If double-feed detection is performed using a fixed threshold based on detecting points, then detection simplicity is maintained, but measurement precision deteriorates because sheets with labels are falsely detected as double-feed
Solution Approach 1:
The patent applies dynamics by making the detection threshold adaptive rather than fixed. The threshold is dynamically adjusted based on the measured sheet length, allowing the system to distinguish between genuine double-feed cases and sheets with attached labels. This resolves the contradiction by maintaining detection simplicity while improving measurement precision through parameter adaptation.
Solution Approach 2:
The patent changes the detection parameter from a fixed number of detecting points to a dynamic threshold based on sheet length measurements. By calculating the threshold as a proportion of the sheet length (e.g., 50% or less), the system adapts to different sheet sizes and configurations, preventing false detection of labeled sheets while maintaining simple detection logic.
2Measurement precision
If the detection threshold is lowered to avoid false detection of sheets with labels, then measurement precision improves, but double-feed detection reliability deteriorates because complete double-feed cases are missed
Solution Approach 1:
The patent resolves this contradiction by introducing a dynamic threshold parameter based on sheet length proportions rather than using fixed detection point counts. By setting the threshold as a proportion (e.g., 50% or less of sheet length), the system maintains high reliability for detecting complete double-feed cases while preventing false detection of sheets with labels, as the threshold adapts to the actual sheet dimensions.
Solution Approach 2:
The system dynamically adjusts the detection threshold based on measured sheet length, making the detection criterion adaptive to different sheet sizes and configurations. This dynamic approach ensures that genuine double-feed cases are reliably detected while false detections from labeled sheets are prevented, resolving the contradiction between reliability and precision.
3Productivity
If double-feed detection continues without accurate determination, then productivity is maintained, but sheet damages occur due to continued conveyance under double-feed state
Solution Approach 1:
The patent implements feedback by continuously monitoring the double-feed state and using the measured sheet length to dynamically adjust detection thresholds. This feedback mechanism ensures accurate determination of double-feed conditions, allowing the system to stop conveyance when genuine double-feed is detected (preventing sheet damage) while maintaining productivity by avoiding false stops caused by labeled sheets.
Solution Approach 2:
The patent replaces simple mechanical detection (fixed point counting) with a measurement-based system that uses sheet length measurements to determine double-feed status. This substitution enables more accurate detection and control, preventing sheet damage while maintaining productivity through intelligent decision-making based on measured parameters.
Data Source
AI summary
A sheet conveying apparatus includes a tray having a plurality of sheets, a feeder to successively convey sheets stacked on the tray, a controller, and a double-feed sensor to detect double feed when the feeder conveys a plurality of sheets in an overlapping manner. When a double-feed length, which corresponds to a length, in a conveyance direction of the sheet, of a region in which the double feed has been detected by the double-feed sensor, is larger than a predetermined distance, the controller determines that the double feed has occurred. When the double-feed length is smaller than the predetermined distance and a sheet size is smaller than a predetermined size, the controller determines that the double feed has occurred. When the double-feed length is smaller than the predetermined distance and the sheet size is larger than the predetermined size, the controller determines that the double feed has not occurred.