Registration Roller Control for Backlash-Stable Sheet Timing
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Solution Overview
Problem
Existing image forming apparatuses experience timing delays due to backlash and belt tension changes in the drive train, particularly when starting to convey sheets after a print job, which can lead to variations in leading-edge registration values.
Innovation Solution
A sheet conveyance apparatus with a registration roller pair and a control unit that performs a process of reducing backlash by accelerating and then decelerating the driving motor to a target speed before abutting the sheet against the stopped registration roller pair, ensuring synchronization with the image forming timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the driving motor is started to convey the first sheet after a print job, then the sheet conveyance is initiated, but backlash occurs between gears and belt tension changes causing timing delay
Solution Approach 1:
The control unit performs preliminary actions by rotating the driving motor at a predetermined speed for a predetermined time before the sheet conveyance. This preliminary rotation stabilizes the belt tension and reduces backlash in the transmission mechanism, ensuring that the timing delay is minimized when the actual sheet conveyance begins.
Solution Approach 2:
The control unit changes the rotation speed parameter of the driving motor by rotating it at a predetermined speed before the actual sheet conveyance. This parameter change stabilizes the transmission mechanism's state, reducing variations in backlash and belt tension that would otherwise cause timing delays and registration errors.
2Manufacturing precision
If the driving motor rotates before sheet conveyance to reduce backlash, then the timing is improved, but the speed for which the control is performed is not specified causing inconsistency
Solution Approach 1:
The control unit specifies predetermined values for the rotation speed and rotation time of the driving motor. By defining these parameters in advance, the control mechanism remains relatively simple while achieving consistent reduction of backlash and stabilization of belt tension, improving registration precision without excessive complexity.
3Stability of the object's composition
If the driving motor is stopped after conveying a sheet, then the backlash and belt tension become stable, but variations occur when starting to convey subsequent sheets
Solution Approach 1:
The control unit performs a preliminary rotation of the driving motor before each sheet conveyance. This preliminary action re-stabilizes the backlash and belt tension that may have varied during the stopped period, ensuring consistent timing for each sheet conveyance while maintaining overall productivity.
Data Source
AI summary
A sheet conveyance apparatus includes a registration roller pair, a driving motor, a transmission mechanism, and a control unit. The control unit performs a process of reducing backlash of the transmission mechanism. The control unit obtains, before performing the process of reducing backlash, a target rotation speed of the driving motor at which the sheet is conveyed by the registration roller pair after the process of reducing backlash. In the process of reducing backlash, the control unit accelerates the driving motor to the target rotation speed and subsequently reduces rotation speed of the driving motor from the target rotation speed to stop the driving motor in a same manner as that after the sheet is conveyed by the registration roller pair after the process of reducing backlash, the control unit reduces the rotation speed of the driving motor from the target rotation speed to stop the driving motor.