Sheet Conveyance Device Trailing Edge Detection Timing Control
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Solution Overview
Problem
Existing sheet conveyance devices face challenges in reducing intervals between sheets during image reading and forming, as trailing-edge detectors struggle to timely recognize the exit of sheets from the separator, leading to inefficiencies in conveying subsequent sheets.
Innovation Solution
A sheet conveyance device with a trailing-edge detector and a leading-edge detector, along with a controller, is used to accurately detect the length of sheets and initiate sheet feeding at the appropriate timing, ensuring minimal intervals between sheets by precisely determining the exit of the trailing edge of the preceding sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the trailing-edge detector is disposed at a distance from the exit of the separation nip, then the detector can reliably detect the trailing edge of the sheet, but the detection timing is delayed, preventing reduction in intervals between sheets
Solution Approach 1:
The detection function is divided into two separate detectors: a trailing-edge detector positioned close to the separation nip exit for accurate detection, and a leading-edge detector positioned downstream to determine sheet length. This segmentation allows each detector to be optimized for its specific function without compromising the other.
Solution Approach 2:
The system performs preliminary measurement of sheet length by detecting the leading edge position before initiating the sheet feeding process. This preliminary action enables the controller to calculate the precise timing for feeding the subsequent sheet, ensuring minimal intervals while maintaining accurate detection.
2Productivity
If the conveyance velocity is increased to reduce intervals between sheets, then sheet throughput improves, but the complexity of controlling sheet timing and positioning increases
Solution Approach 1:
The controller receives feedback signals from both the trailing-edge detector and leading-edge detector to dynamically adjust the sheet feeding timing. This feedback mechanism enables precise control of conveyance velocity and timing, allowing high throughput while maintaining simple and reliable control logic based on actual sheet position detection.
3Productivity
If multiple sheets enter the separator with their leading-end portions superimposed, then the separator can process sheets in batches, but multifeed errors occur and only the top sheet can be discharged
Solution Approach 1:
The leading-edge detector detects the leading edge of each sheet before it enters the separator, allowing the controller to determine the precise timing for sheet feeding. This preliminary detection prevents multiple sheets from entering the separator simultaneously with superimposed leading ends, ensuring reliable single-sheet separation while maintaining efficient processing.
Data Source
AI summary
A sheet conveyance device includes a loading section, a sheet feeding unit, a separation section disposed downstream in a sheet conveyance direction from the sheet feeding unit, a conveyance member to transport a sheet separated by the separation section, a trailing-edge detector disposed at a first conveyance distance (L1) downstream from a separation position (Ab) and including a rotary follower and a rotation detector, a first leading-edge detector disposed downstream from the trailing-edge detector, and a controller. The trailing-edge detector A detects a sheet length in the sheet conveyance direction. The controller causes the sheet feeding unit to start sheet feeding in response to detection of the leading edge of the sheet by the first leading-edge detector when the detected sheet length equals a predetermined reference length and in other cases in response to detection of the trailing edge of the sheet by the trailing-edge detector.