Sheet Retraction Roller Speed Control for Stapling Accuracy
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Solution Overview
Problem
Conventional post-processing apparatuses face issues with sheet displacement during retraction onto the processing tray due to high downward movement speed of the driving roller, leading to degraded output quality and reduced productivity, especially when stapling is involved.
Innovation Solution
The control portion adjusts the downward movement speed of the driving roller based on the need for stapling and the number of sheets stacked, setting it to a lower speed during stapling to prevent roller bounce and sheet displacement, and adjusts contact pressure accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the downward movement speed of the driving roller is increased to improve productivity, then sheet conveyance efficiency is improved, but sheet displacement and roller bounce occur during retraction leading to degraded output quality
Solution Approach 1:
The patent applies dynamics by making the driving roller's rotation speed variable rather than constant. The control portion dynamically adjusts the rotation speed based on the operational phase: using higher speeds during normal conveyance to maintain productivity, and reducing to lower speeds during retraction operations to prevent roller bounce and sheet displacement. This dynamic speed adjustment resolves the contradiction between productivity and positioning accuracy.
Solution Approach 2:
The patent changes the operational parameter (rotation speed of the driving roller) based on the operational context. During retraction operations, the rotation speed is reduced to a lower value to minimize roller bounce and prevent sheet displacement on the processing tray. During normal conveyance, the higher rotation speed is maintained to ensure productivity. This parameter change strategy effectively resolves the technical contradiction.
2Loss of time
If the driving roller moves downward at high speed to retract sheets quickly, then processing time is reduced, but roller bounce causes sheet displacement and degraded output quality
Solution Approach 1:
The patent implements periodic action by alternating between different rotation speed phases during sheet handling. During normal conveyance, the driving roller operates at high speed. During retraction, it switches to low speed to prevent bounce. This periodic switching of operational modes allows the system to maintain overall efficiency while ensuring quality during critical retraction phases, resolving the contradiction between processing time and output quality.
3Reliability
If the driving roller contacts the sheet with high force to ensure reliable conveyance, then conveyance reliability is improved, but sheet displacement occurs during retraction leading to stacking errors
Solution Approach 1:
The patent applies local quality by differentiating the contact force characteristics during different operational phases. During normal conveyance, higher contact force ensures reliable sheet movement. During retraction, the control portion reduces rotation speed to minimize contact force and prevent roller bounce, thereby avoiding sheet displacement and stacking errors. This localized adjustment of force characteristics resolves the contradiction between conveyance reliability and stacking accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents sheet displacement on the processing tray, maintaining output quality and productivity by minimizing roller bounce and ensuring reliable sheet stacking and discharge.
Implementation Method 1
The driven roller is disposed below the driving roller across the sheet conveyance passage and nips the sheet with the driving roller as the driving roller moves downward
Implementation Method 2
rotates the driving roller backward so as to retract the sheet from its trailing edge onto the processing tray
Data Source
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AI summary
A post-processing apparatus (100) includes a conveyance portion (1), a processing tray (2), a post-processing portion (3), a discharge tray (10), a discharge portion (4), and a control portion (5). The discharge portion (4) includes an arm (40), a driving roller (41), and a driven roller (42). When stacking a sheet (S) on the processing tray (2), the control portion (5) brings the driving roller (41) into contact with the sheet (S). Except when the sheet (S) as the target of post-processing is retracted onto the processing tray (2), the control portion (5) sets the downward movement speed of the driving roller (41) to a normal speed. When the sheet (S) as the target of post-processing is retracted onto the processing tray (2), the control portion (5) sets the downward movement speed of the driving roller (41) to a speed lower than the normal speed.