Rotary Member Pair Synchronization for Sheet Bundle Crease Prevention
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Solution Overview
Problem
Existing sheet processing apparatuses face issues with delayed rotation of the upper bundle discharge roller due to backlashes in the drive transmission unit, leading to sheet distortion and crease generation during the binding process, and insufficient conveyance force causing slippage in thick sheet bundles.
Innovation Solution
A sheet processing apparatus with a rotary member pair that includes a moving portion to separate and then nip the sheet bundle, and a control portion to coordinate the rotation of the rotary member pair, ensuring synchronized rotation in the discharge direction to prevent creases and slippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive transmission unit includes a plurality of gears to transmit rotation from the lower bundle discharge roller to the upper bundle discharge roller, then the upper bundle discharge roller can be rotated in the sheet discharge direction, but backlashes of the drive transmission unit cause a delay in the drive transmission to the upper bundle discharge roller, resulting in sheet distortion and crease generation
Solution Approach 1:
The patent removes the problematic gear transmission unit from the system and replaces it with a direct drive configuration where each bundle discharge roller has its own independent drive source. This extraction of the intermediary transmission mechanism eliminates the backlashes and drive delays that caused sheet distortion and creases, while maintaining the essential function of rotating both rollers in the sheet discharge direction.
Solution Approach 2:
The patent segments the drive system by providing independent drive sources for the lower bundle discharge roller and the upper bundle discharge roller instead of using a single unified gear transmission system. This segmentation allows each roller to be controlled independently, ensuring synchronized rotation without the backlashes inherent in gear transmissions, thereby preventing sheet distortion and crease generation.
2Manufacturing precision
If the press-contact force of the bundle discharge roller pair is reduced to suppress distortion of the upper sheet, then sheet distortion is reduced, but the conveyance force is insufficient for thick sheet bundles, causing slippage and marks on the sheet surface
Solution Approach 1:
The patent implements dynamic control of the bundle discharge roller pair by independently controlling the rotation of the lower and upper rollers. The system dynamically adjusts the rotation timing and speed of each roller based on the sheet bundle characteristics, allowing sufficient press-contact force to be applied without causing sheet distortion. This dynamic control ensures adequate conveyance force for thick sheet bundles while maintaining sheet flatness, preventing both distortion and slippage.
Data Source
AI summary
A sheet processing apparatus includes a sheet conveying portion conveying a sheet to a sheet stacking portion; a regulating portion regulating a position of the sheet on the stacking portion; a rotary member pair having first and second rotary members and conveying the sheet toward the regulating portion through rotation in a first direction, and conveying a bound sheet bundle through rotation in a second direction opposite to the first direction; a moving portion moving the second rotary member to a separation position after the rotary member pair conveys the sheet, and moving the second rotary member to a nipping position before the rotary member pair conveys the sheet bundle; and a control portion controlling to rotate the rotary member pair in the second direction after the second rotary member is moved to the separation position and before the second rotary member is moved to the nipping position.