DC Motor Sheet Feeding Apparatus Overrun Control
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Solution Overview
Problem
Existing sheet feeding apparatuses using inexpensive DC motors experience overrun issues when a small amount of sheets is stacked, leading to jamming and unstable feeding performance, while more expensive stepping motors are required to mitigate this problem.
Innovation Solution
A sheet feeding apparatus with a DC motor-driven sheet stack tray and detection sensors that implement a tentative stop or speed reduction when the uppermost sheet reaches a predetermined height, ensuring accurate positioning and preventing overrun by controlling the motor based on detection sensor feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a DC motor is employed as the power source for the sheet stack tray, then the cost is reduced, but the sheet stack tray causes overrun when a small amount of sheets is stacked, leading to jamming
Solution Approach 1:
The patent employs height detection means to detect the height of the sheet stack tray or the uppermost sheet, and uses this detection signal to vary the current supplied to the DC motor or its rotation. This feedback mechanism allows the system to adjust motor performance based on actual sheet stack conditions, preventing overrun while maintaining cost-effectiveness
Solution Approach 2:
The patent dynamically adjusts the motor current or rotation based on the detected sheet stack height. By varying the current supplied to the DC motor or its rotation according to the detection signal, the system adapts its behavior to different sheet stacking conditions, preventing fixed-speed overrun issues
2Productivity
If the sheet stack tray is elevated and the DC motor is stopped after detecting the uppermost sheet reaches the predetermined height, then the feeding operation is completed, but the uppermost sheet is elevated to a position higher than the predetermined feed position when a small amount of sheets is stacked
Solution Approach 1:
The patent performs preliminary elevation of the sheet stack tray to a position slightly higher than the predetermined feed position, then uses the height detection means to detect when the uppermost sheet reaches the predetermined height. Based on this detection, the system then adjusts the motor current or rotation to achieve precise positioning, preventing the sheet from ending up too high
3Reliability
If the movement of the sheet stack tray is switched up, down, up and down at timings when the detection sensor output is turned off, on, off and on, then the overrun fluctuation is suppressed, but a longer time is required until the sheet stack tray is stopped at the predetermined position
Solution Approach 1:
Instead of switching the movement direction multiple times, the patent changes the motor current parameter dynamically based on the detection signal. By varying the current supplied to the DC motor or its rotation according to the sheet height detection, the system achieves overrun suppression without the time penalty of repeated direction changes
Data Source
AI summary
The sheet feeding apparatus includes a sheet stack tray on which sheets to be fed are stacked, a drive motor for moving up the sheet stack tray, a detection sensor for detecting the position of an uppermost sheet stacked on the sheet stack tray, and a control part for controlling the function of the drive motor, wherein, when the detection sensor detects that the uppermost sheet reaches a predetermined height while the drive motor executes a drive so as to move up the sheet stack tray, the control part tentatively stops or decelerates the drive motor and thereafter drives the drive motor so as to move up the sheet stacked on the sheet stack tray to a feed position.