Sheet Conveyance Device Crease Reduction via Roller Dynamics
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Solution Overview
Problem
Sheet conveyance devices in image forming apparatuses face challenges in reducing creases and out-of-plane deformation when conveying sheets of varying sizes, particularly due to the need for close roller pair distances and higher registration roller speeds, which can lead to crease formation and image quality issues.
Innovation Solution
A sheet conveyance device with a pair of first and second conveyance rollers, registration rollers, and a switching mechanism that controls the conveyance speed and contact state of the rollers to minimize out-of-plane deformation by executing specific conveyance operations that adjust the sheet conveyance speed and roller contact states to reduce crease occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distance between roller pairs is reduced to convey short sheets, then sheet size adaptability is improved, but out-of-plane deformation and crease occurrence increase
Solution Approach 1:
The patent applies dynamics by making the second conveyance rollers switchable between contact and separated states. During skew correction, the second rollers are separated to eliminate constraints that would cause out-of-plane deformation. During normal conveyance, they contact to provide stable support. This dynamic adjustment resolves the contradiction between maintaining close roller spacing for short sheets and preventing sheet deformation.
2Productivity
If the sheet conveyance speed of registration rollers is increased, then productivity is improved, but out-of-plane deformation and crease occurrence increase
Solution Approach 1:
The patent applies preliminary action by performing skew correction before high-speed conveyance. The registration rollers first abut the front end of the sheet to correct skew while the second rollers are separated, minimizing deformation. After correction, the second rollers contact to provide stable support during subsequent high-speed conveyance. This sequence allows high productivity while preventing creases.
3Stability of the object's composition
If the second conveyance rollers remain in contact state during skew correction, then sheet conveyance stability is improved, but out-of-plane deformation increases
Solution Approach 1:
The patent uses dynamics by switching the second conveyance rollers between contact and separated states based on operational requirements. During skew correction, they are separated to allow the sheet to form a loop without constraint, preventing out-of-plane deformation. During normal conveyance, they contact to provide stability. This resolves the contradiction between conveyance stability and sheet flatness.
Data Source
AI summary
A sheet conveyance device capable of reducing occurrence of creases on a sheet includes first conveyance rollers that nip and convey a sheet, second conveyance rollers arranged downstream that convey the sheet, registration rollers arranged further downstream that nip and convey the sheet after correcting skew of the sheet, a switching portion that switches a state of the second conveyance rollers between contact and separated states, and a control unit that controls the rollers and the switching mechanism. The control unit switches between first and second conveyance operations. In both conveyance operations, the registration rollers start rotating to convey the sheet of which the skew has been corrected by the first conveyance rollers and the registration rollers and the second conveyance rollers are in the separated state. In the first conveyance operation, a sheet conveyance speed by the registration rollers is higher than that by the first conveyance rollers, whereas in the second conveyance operation, the sheet conveyance speed by the registration rollers is lower than that by the first conveyance rollers.