Sheet Alignment Method for Image Forming Apparatus
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Solution Overview
Problem
Conventional sheet alignment mechanisms in post-processing systems face challenges in accurately aligning sheets during stapling and other post-processes, leading to issues like skewing, bending, and rebounding due to the simultaneous action of conveying and widthwise aligning forces, which affects the precision and efficiency of processes like stapling.
Innovation Solution
A method that adjusts the conveying force applied by the sheet transfer device, reducing it when the sheet abuts against the regulating member and increasing it during widthwise alignment, using a sheet feeding rotating member with variable speed or a brake mechanism to ensure precise alignment without skewing or bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet transfer device and widthwise aligning device act simultaneously on the sheet, then the sheet can be conveyed and aligned at the same time, but the sheet may become skewed due to the relationship between sheet centroid position and aligning position
Solution Approach 1:
The patent divides the sheet alignment process into two distinct phases: first conveying the sheet to the aligning position, then performing widthwise alignment. This segmentation separates the conveying function from the aligning function, eliminating the skewing problem that occurs when both actions occur simultaneously. The sheet is first transferred by the sheet transfer device to position the trailing end against the regulating member, and only then does the widthwise aligning device act on the sheet.
Solution Approach 2:
The patent applies preliminary action by first positioning the sheet's trailing end against the regulating member before performing widthwise alignment. This preliminary conveying action establishes a reference position that prevents skewing during the subsequent alignment operation. The sheet transfer device brings the sheet to the aligning position in advance, creating a stable baseline for the widthwise aligning device to work from.
2Productivity
If the sheet transfer device applies strong conveying force to increase processing speed, then productivity improves, but the sheet may rebound or buckle when abutting against the regulating member
Solution Approach 1:
The patent employs periodic action by varying the conveying force in two stages: initially applying strong conveying force to rapidly move the sheet to the aligning position, then reducing the force to a gentle level when the trailing end approaches the regulating member. This periodic variation in force magnitude allows high-speed processing while preventing rebound and buckling during the critical abutting phase.
Solution Approach 2:
The patent changes the parameter of conveying force from high to low during the sheet transfer process. The sheet transfer device adjusts its output force based on the sheet's position relative to the regulating member, maintaining high speed during transit but reducing force during the final approach to prevent mechanical damage to the sheet.
3Reliability
If the sheet conveying speed is reduced to prevent buckling during alignment, then sheet integrity is maintained, but processing time increases
Solution Approach 1:
The patent uses periodic action to vary conveying speed in two distinct phases: high speed during the initial transfer to minimize processing time, and low speed during the final approach to the regulating member to prevent buckling. This time-varying speed profile optimizes both productivity and sheet integrity by applying the appropriate speed at the appropriate moment.
Solution Approach 2:
The patent performs preliminary high-speed conveying to bring the sheet close to the aligning position quickly, then transitions to low-speed precise positioning. This preliminary action at high speed reduces the overall time required while the subsequent low-speed phase ensures sheet integrity during the critical alignment operation.
Data Source
AI summary
A method of a sheet alignment includes carrying a sheet from a sheet discharging port; transferring the sheet on a tray device toward a sheet end regulating device; moving the sheet on the tray device in a width direction orthogonal to the sheet discharging direction for widthwise alignment; and abutting again the sheet on the tray device against the sheet end regulating device while the sheet is in the widthwise alignment. When the sheet on the tray device is transferred toward the sheet end regulating device, the sheet is transferred at a predetermined speed. Before the sheet abuts against the sheet end regulating device, the speed is reduced to provide a conveying force to the sheet without stopping. While the conveying force is continuously applied to the sheet, the sheet is aligned in the width direction to thereby prevent skewing of the sheet relative to the sheet end regulating device.