Sheet Feeding Device with Dynamic Pick-up Roller Control
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Solution Overview
Problem
Existing sheet feeding devices in image reading and forming apparatuses face challenges in stabilizing the feeding process, particularly with irregular-sized documents, leading to issues like double feeding and paper jams, due to difficulties in estimating the length of sheets such as receipts or acknowledgments, which can cause the pick-up roller to contact the current sheet before it has passed through the separation nip.
Innovation Solution
A sheet feeding device with a contact and separation mechanism that adjusts its operation based on sheet size information, using two modes: one where the feeding portion is contacted after detecting the trailing end of the current sheet, and another where it is contacted based on the distance fed by the separation conveying portion before detecting the trailing end, to prevent double feeding and improve productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pick-up roller is lowered to feed the subsequent sheet earlier, then productivity is improved, but the risk of contacting the current sheet and causing double feeding or paper jam increases
Solution Approach 1:
The pick-up roller is designed to be movable between a lowered position (for feeding subsequent sheets) and a raised position (for avoiding contact with current sheets). The roller's position dynamically changes based on real-time detection of the current sheet's location, allowing the system to adapt between productivity and reliability requirements
Solution Approach 2:
A detection mechanism continuously monitors the position of the current sheet and provides feedback to the control system. Based on this feedback, the control system determines the appropriate timing to lower the pick-up roller, ensuring that the roller only contacts subsequent sheets when the current sheet has safely passed through the separation nip
2Productivity
If the feeding portion contacts the sheet earlier to improve throughput, then the number of sheets fed per unit time increases, but oblique movement and abnormal feeding occur
Solution Approach 1:
The separation conveying portion performs preliminary separation of the current sheet from the sheet stack before the pick-up roller contacts the subsequent sheet. This preliminary action ensures that the current sheet is fully separated and positioned correctly, preventing oblique movement when the pick-up roller subsequently feeds the next sheet
Solution Approach 2:
The feeding process is divided into distinct segments: separation of the current sheet by the separation conveying portion, detection of the current sheet's position, and feeding of the subsequent sheet by the pick-up roller. This segmentation allows each function to be optimized independently, maintaining feeding alignment while improving throughput
Data Source
AI summary
A sheet feeding device includes a stacking portion, a feeding portion, a contact and separation mechanism, a separation conveying portion, a detecting portion, a size acquiring portion, and a controller. In a first mode, in a case that the detecting portion detects passing of a trailing end of the current sheet after the separating operation, the controller causes the contact and separation mechanism to start a contact operation in which the feeding portion is contacted to a sheet stacked on the stacking portion in order to feed a subsequent sheet. In a second mode, before the detecting portion detects passing of a trailing end of the current sheet after the separating operation, the controller causes the contact and separation mechanism to start, on the basis of a distance in which the current sheet is fed by the separation conveying portion, the contact operation to feed the subsequent sheet.