Sheet Conveyance Roller Speed Control for Skew Correction
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Solution Overview
Problem
Existing sheet conveying apparatuses often cause sheet twisting and damage during width-direction correction, leading to wrinkles or tears, and require complex mechanisms to avoid these issues.
Innovation Solution
A sheet conveying apparatus with a first and second conveyance roller pair, a width-direction shifting unit, and control units that adjust the circumferential speed of the rollers to correct skew and width-direction position without damaging the sheet, using a simple configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the registration roller pair shifts the sheet in the width direction while being pinched, then the sheet position in the sheet width direction is corrected, but the sheet becomes greatly twisted and may be wrinkled or torn
Solution Approach 1:
The patent applies preliminary action by separating the upstream roller pair from the sheet before the width-direction shifting operation begins. This preliminary separation prevents the sheet from being pinched between rollers during the shifting process, thereby avoiding sheet twisting and damage while still enabling effective width-direction position correction
2Object-affected harmful factors
If a mechanism is added to separate the upstream roller pair from the sheet during width-direction correction, then sheet damage is prevented, but the apparatus becomes complex and cost increases
Solution Approach 1:
The patent applies self-service by utilizing the inherent reciprocating motion of the upstream roller pair during sheet conveyance. The roller pair naturally separates from the sheet during its reciprocating cycle, eliminating the need for additional separation mechanisms. This self-service approach prevents sheet damage while maintaining apparatus simplicity and avoiding cost increases
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
The apparatus effectively corrects skew and width-direction position of sheets without causing twisting or damage, ensuring smooth operation and reducing complexity and costs.
Implementation Method 1
a first conveyance roller pair configured to nip and convey a sheet, a second conveyance roller pair arranged downstream of the first conveyance roller pair and configured to nip and convey the sheet conveyed by the first conveyance roller pair
Implementation Method 2
form a nip portion that comes into contact with a leading edge of the sheet conveyed by the first conveyance roller pair to bend the sheet
Data Source
AI summary
A sheet conveying apparatus includes first and second conveyance roller pairs, a width-direction shifting unit, first and second drive units, and a control unit. The second conveyance roller pair is arranged downstream of the first conveyance roller pair to nip and convey the sheet conveyed by the first conveyance roller pair, and to bend the sheet. The width-direction shifting unit shifts the sheet nipped by the second conveyance roller pair in a width direction by shifting the second conveyance roller pair in the width direction. The control unit controls the first and second drive units so that a circumferential speed of the first conveyance roller pair is made higher than that of the second conveyance roller pair between when the second conveyance roller pair starts conveying the sheet and when the width-direction shifting unit completes shifting the second conveyance roller pair in the width direction.