Sheet Conveyance Device Edge Detection Control
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Solution Overview
Problem
Existing sheet conveyance devices face challenges in reducing intervals between sheets during sequential conveyance due to limitations in positioning detectors, leading to inefficiencies and potential errors in detecting sheet edges, especially with varying sheet sizes.
Innovation Solution
A sheet conveyance device equipped with a sheet length detector, leading-edge detector, and trailing-edge detector, along with a controller that adjusts the feeding of subsequent sheets based on the detected lengths and positions of sheets, ensuring accurate detection and reduced intervals between sheets of different sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the trailing-edge detector is disposed closer to the separation nip to reduce intervals between sheets, then productivity is improved, but the leading end of the subsequent sheet may project downward and face the trailing-edge detector, causing detection errors
Solution Approach 1:
The patent introduces a new spatial dimension by adding the leading-edge detector upstream of the separation nip, working in conjunction with the existing trailing-edge detector downstream. This two-dimensional detection approach (upstream and downstream) allows the system to accurately track sheet positions without requiring the trailing-edge detector to be positioned too close to the separation nip, thereby resolving the contradiction between productivity improvement and detection accuracy.
Solution Approach 2:
The leading-edge detector performs preliminary detection of the subsequent sheet before it reaches the separation nip. By detecting the leading end position in advance, the system can predict when the trailing end of the preceding sheet will pass the detection point, enabling accurate trailing-edge detection even when the detector is positioned optimally for productivity rather than purely for detection accuracy.
2Productivity
If the conveyance velocity at the reading position is increased to reduce intervals between sheets, then productivity is improved, but the velocity difference between separation unit and reading position becomes insufficient
Solution Approach 1:
The patent implements a feedback control system where the controller continuously monitors the positions of both the preceding and subsequent sheets using the leading-edge and trailing-edge detectors. Based on this real-time position feedback, the controller dynamically adjusts the conveyance velocity to maintain optimal intervals between sheets, allowing high throughput while preserving sufficient velocity difference for effective separation.
3Measurement precision
If multiple detectors are added to improve sheet detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The leading-edge detector and trailing-edge detector serve multiple functions within the sheet conveyance system. In addition to detecting sheet edges for position tracking, these detectors enable the controller to monitor sheet length, detect sheet presence, and control the timing of subsequent sheet feeding. This multi-functionality reduces the need for additional specialized detectors, thereby limiting the increase in device complexity while significantly improving measurement precision.
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
The solution enables efficient and accurate sequential sheet conveyance by optimizing the detection and feeding mechanisms, reducing the risk of multifeed and skew, and enhancing productivity across various sheet sizes.
Implementation Method 1
The trailing-edge detector may be a reflection-type or transmission-type photosensor that directs light onto a surface of the original document to detect its presence
Implementation Method 2
The trailing-edge detector may be a reflection-type or transmission-type photosensor that directs light onto a surface of the original document to detect its presence
Implementation Method 3
a leading-edge detector to detect a leading end of the sheet
Implementation Method 4
a leading-edge detector to detect a leading end of the sheet
Data Source
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AI summary
A sheet conveyance device (51) includes a loading section (53), a first conveyance member (80), a separation section (B), a sheet length detector (S4) to detect whether the sheet is longer than a predetermined length slightly longer than a specific sheet size in the sheet conveyance direction, a trailing-edge detector (S3) disposed downstream from the separation section, a leading-edge detector (S1; S2) disposed downstream from the trailing-edge detector a distance smaller than the specific sheet size and from the first conveyance member a distance longer than the specific sheet size, and a controller. When the sheet is equal to or greater than the predetermined length, the controller (100) starts sheet feeding when the trailing-edge detector detects the trailing edge of the sheet, and when the sheet is smaller than that, the controller starts sheet feeding when either the leading-edge detector detects the leading edge of the sheet or the trailing-edge detector detects the trailing edge thereof.