Sheet Feeding Device Cam Control for Lifting Time-Lag
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Solution Overview
Problem
Existing sheet feeding mechanisms in image forming apparatuses experience performance degradation due to mechanical time-lags in the ON/OFF control of lifting operations, leading to continued lifting after reaching the predetermined height and reduced sheet feeding efficiency.
Innovation Solution
A sheet feeding device with a loading portion, lifting mechanism, cam, detecting unit, and control unit that alternately sets the lifting mechanism to operating and stopped states before the top sheet reaches the predetermined height, ensuring the cam is already rotating by the time the sheet reaches the height, thus minimizing the second time-lag and preventing performance worsening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical cam mechanism is used for ON/OFF control of lifting operation, then the lifting operation can be controlled, but a time-lag occurs causing the lifting operation to continue even after the loading portion reaches the predetermined height
Solution Approach 1:
The control unit rotates the cam to the second rotational position (stopping position) in advance before the loading portion actually reaches the predetermined height. By predicting the arrival time and initiating the cam rotation beforehand, the system compensates for the mechanical time-lag inherent in the cam mechanism, ensuring the lifting operation stops at the correct timing.
Solution Approach 2:
The detecting unit continuously monitors the position of the loading portion and provides real-time feedback to the control unit. This feedback loop enables the control unit to adjust the cam rotation timing dynamically based on the actual position and speed of the loading portion, ensuring precise stopping control despite mechanical delays.
2Device complexity
If the cam is rotated only after detecting the loading portion reaches the predetermined height, then the control response can be simple, but the lifting operation continues longer causing sheet feeding performance to worsen
Solution Approach 1:
Instead of waiting until the loading portion reaches the predetermined height to start rotating the cam, the control unit initiates the cam rotation in advance based on predicted arrival time. This preliminary action reduces the effective time-lag and prevents the lifting operation from continuing too long, thereby maintaining sheet feeding performance without significantly increasing control logic complexity.
3Device complexity
If the cam mechanism is used for control, then the mechanical structure can be simple, but the precision of stopping the lifting operation at the predetermined height is reduced
Solution Approach 1:
The detecting unit provides continuous position feedback of the loading portion to the control unit. This feedback enables the control unit to precisely control the timing of cam rotation, compensating for the inherent imprecision of the mechanical cam mechanism. The system can adjust the cam rotation timing based on real-time position data, achieving high stopping precision while maintaining the simplicity of the mechanical cam structure.
Solution Approach 2:
The patent replaces part of the mechanical control system with an electronic control system. Instead of relying solely on mechanical timing mechanisms, the control unit uses electronic detection and control to precisely time the cam rotation. This substitution of electronic control for mechanical timing improves stopping precision while keeping the mechanical cam structure relatively simple.
Data Source
AI summary
A sheet feeding device includes a loading portion configured to be loaded with a sheet, a lifting mechanism that lifts the loading portion in an operating state and stops the loading portion in an stopped state, a cam configured to be rotated alternately to a first rotational position for setting the lifting mechanism to the operating state and to a second rotational position for setting the lifting mechanism to the stopped state, a detecting unit having a contact portion movable up and down while contacting the sheet on the loading portion, which detects whether the sheet reaches a first height based upon the movement of the contact portion thereof, and a control unit configured to rotate the cam before the detecting unit detects that the sheet reaches the first height and to stop the cam in the second rotational position in response to the detection by the detecting unit.