Roll Sheet Supply Sensing for Reverse Feed Prevention
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Solution Overview
Problem
Existing sheet supply mechanisms in image forming apparatuses face challenges in accurately detecting the front end of a continuous sheet and preventing improper sheet feeding due to reverse setting, leading to inefficiencies and potential damage to the sheet.
Innovation Solution
A sheet supply device equipped with a guide arm, sensor, and control circuitry that monitors the change in detection signal to differentiate between proper and reverse sheet orientations, using threshold values to prevent continued rotation when the sheet is set in the wrong direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spool is rotated continuously to feed the sheet, then the sheet supply speed is improved, but the risk of sheet damage and improper feeding increases when the sheet is reversely set
Solution Approach 1:
The system performs preliminary detection of the sheet front end and orientation status before initiating continuous rotation. The sensor detects the sheet front end position and the control unit determines whether the sheet is properly or reversely set before starting the feeding operation, preventing damage beforehand
Solution Approach 2:
The system continuously monitors the sheet feeding process using sensors that detect the sheet front end position and orientation. Based on this feedback, the control unit adjusts the rotation direction and speed, and stops rotation when reverse setting is detected, ensuring accurate and safe sheet supply
2Measurement precision
If a sensor is used to detect the sheet front end, then the detection accuracy is improved, but the complexity of the device increases
Solution Approach 1:
A sensor acts as an intermediary element between the sheet and the control system. The sensor detects the sheet front end position and orientation by sensing changes in the electromagnetic field or light when the sheet passes, converting physical sheet characteristics into electrical signals that the control unit can process
Solution Approach 2:
The patent replaces complex mechanical detection mechanisms with a sensor-based detection system. Instead of using mechanical switches, levers, or contact-based detection methods, the system uses non-contact sensing to detect the sheet front end and orientation, simplifying the overall device structure while maintaining high detection accuracy
Data Source
AI summary
A sheet supply device includes a supporter, a rotation device, a guide, a support shaft, a biasing member, a sensor, a roller, and control circuitry. The sensor is disposed to protrude from the facing portion toward the roll and biased in a direction to contact the outer peripheral surface of the roll. The sensor outputs a detection signal at a level corresponding to an amount at which the sensor protrudes from the facing portion. The roller is supported by the facing portion, to contact the outer peripheral surface of the roll at a position different from a position of the sensor in a circumferential direction of the roll. The control circuitry controls the rotation device based on a signal change rate that is a change amount of the level of the detection signal per unit time. The control circuitry causes the rotation device to rotate the spool in the winding direction, and stops an operation of the rotation device when the signal change rate based on a change in relative positions between the outer peripheral surface and the sensor without passage of a leading end of the sheet through the position of the sensor does not exceed a predetermined reverse set threshold value.