Sheet Post-Processing Roller Control for Stable Z-Fold Stacking
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Solution Overview
Problem
Existing sheet post-processing apparatuses generate noise and instability in stacking sheets due to deflection and pressing of sheets against rotating conveyance rollers, particularly when handling Z-folded sheets.
Innovation Solution
A sheet post-processing apparatus with a conveyance rollers pair and discharge rollers pair that rotate independently, controlled by a mechanism to manage sheet deflection and separation, allowing controlled deflection and repositioning of Z-folded sheets to prevent pressing against rollers and improve stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the sheet is conveyed through rotating conveyance rollers, then the sheet can be transported to the processing tray, but the sheet deflection causes the upstream end to press against the rotating rollers, generating noise and causing unstable stacking
Solution Approach 1:
The patent applies preliminary action by stopping the conveyance rollers before the upstream end of the sheet passes through, preventing the sheet from pressing against the rotating rollers. This anticipatory stopping action eliminates the cause of noise generation and unstable stacking while maintaining efficient sheet transport.
2Productivity
If the conveyance rollers continue rotating to maintain continuous sheet flow, then productivity is improved, but sheet deflection causes pressing against rollers resulting in noise and stacking instability
Solution Approach 1:
The patent implements periodic action by cyclically stopping and rotating the conveyance rollers based on sheet position detection. This periodic operation ensures sheets are conveyed smoothly without pressing against rollers, maintaining both high productivity through continuous cycling and reliable stacking stability by eliminating harmful pressing actions at appropriate intervals.
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
Suppresses noise generation and enhances the stability of stacked sheets by preventing deflection and pressing against rotating rollers, ensuring smooth conveyance and stacking.
Implementation Method 1
a lower discharge roller and an upper discharge roller which are disposed in the sheet discharge port, rotate independently from each other, and have circumferential surfaces bringing into contact with each other to form a nip area
Implementation Method 2
the sheet is deflected between the first conveyance rollers pair and the second conveyance rollers pair. Then, the tail end of the sheet is pressed against the rotating first conveyance rollers pair owing to the elasticity of the deflection
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A sheet post-processing apparatus (1) includes a processing tray (5), a sheet discharge port (7), a conveyance rollers pair (4), lower and upper discharge rollers (81), (82) and a discharge tray (9). When the sheet having a folded portion is stacked on the processing tray (5) with the folded portion downward, a controller rotates the lower and upper discharge rollers (81), (82) to advance the folded portion to the sheet discharge port (7), stops the lower discharge roller (81) before the folded portion passes the sheet discharge port (7), rotates the conveyance rollers pair (4) and the upper discharge roller (82) so as to convey the rear half portion to the downstream side until the sheet passes the conveyance rollers pair (4) and to form a deflection on the sheet, rotates the lower and upper conveyance rollers (81), (82) and then to stack the sheet on the processing tray (5).