Sheet Conveyance Position Detection via Dual Standby Selection
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Solution Overview
Problem
Conventional sheet medium conveying devices face inaccuracies in detecting position detection marks due to time lags between command and actual standby or restart operations, leading to errors in positioning, especially when the detection point is between the leading and trailing edges of the marks.
Innovation Solution
The implementation of a sheet medium conveying device with a controller that selects between a first and a second standby position, ensuring the detection point is always downstream of the trailing edge of the black mark, thereby avoiding inaccuracies in position detection without reducing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sheet medium is conveyed to a single standby position, then the device structure is simple, but the position detection accuracy deteriorates when the detection point is between the leading and trailing edges of the mark
Solution Approach 1:
The standby position is divided into multiple segments (first standby position and second standby position) along the conveyance direction. The detection point is positioned between these segments, allowing the system to select appropriate standby positions based on mark detection accuracy requirements while maintaining a relatively simple overall device structure.
2Measurement precision
If the conveyance is stopped frequently to ensure accurate mark detection, then the position detection accuracy is improved, but the productivity deteriorates
Solution Approach 1:
The system performs preliminary detection of the sheet medium's position relative to the detection point before conveying to the standby position. Based on this preliminary information, it pre-selects the appropriate standby position (first or second) to ensure accurate mark detection, thereby avoiding unnecessary conveyance stops and maintaining high productivity.
3Loss of information
If the detection point is positioned upstream to detect marks earlier, then the position identification is improved, but the accuracy deteriorates when the mark edges are not fully captured
Solution Approach 1:
The system dynamically adjusts the selection of standby positions based on real-time detection conditions. When marks are detected at the first standby position, the system determines whether the detection is accurate by checking if the detection point is properly positioned relative to the mark edges, and switches to the second standby position if necessary, ensuring both complete mark capture and accurate position identification.
Data Source
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AI summary
A sheet medium conveying device conveys a sheet medium in which position detection marks are provided at regular intervals in a medium conveying direction in which the sheet medium is conveyed. The sheet medium conveying device includes a controller that controls conveyance of the sheet medium. The controller selects one of a first standby position and a second standby position located downstream of the first standby position in the medium conveying direction, and conveys the sheet medium to the selected standby position and puts the sheet medium on standby.