Sheet Conveyance Skew Correction via Dual Roller Speed Control
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Solution Overview
Problem
Existing sheet conveying techniques struggle to achieve accurate skew correction while maintaining a cost-effective and simple apparatus configuration, as highly accurate sensors increase costs and multi-stage skew correction methods do not significantly improve accuracy.
Innovation Solution
A sheet conveying apparatus with first and second rollers that can rotate independently, featuring a hierarchical arrangement of skew detecting units with varying detection accuracy along the sheet conveying direction, where the most downstream unit has the highest accuracy, and a controller to adjust roller speeds based on detection results to correct skew.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If highly accurate sensors are used to improve skew detection accuracy, then skew correction accuracy is improved, but apparatus cost increases
Solution Approach 1:
The patent divides the skew detection function into multiple detection units positioned at different locations along the sheet conveying path. Each unit detects skew at its specific position, and the control unit synthesizes these multiple detection results to achieve high overall detection accuracy without requiring any single sensor to be highly expensive or accurate.
Solution Approach 2:
The patent transitions from relying on a single high-accuracy sensor to using multiple standard-accuracy sensors arranged in the conveying direction. By adding the dimension of spatial distribution along the convey path, the system achieves accurate skew measurement through positional diversity rather than sensor precision alone.
2Productivity
If multiple sensor pairs are arranged in the sheet conveying direction to perform multi-stage skew correction, then skew correction opportunities are increased, but skew detection accuracy is not improved and apparatus complexity increases
Solution Approach 1:
The control unit continuously receives skew detection signals from multiple detection units positioned at different locations and dynamically adjusts the rotation speeds of the first and second rollers based on this feedback. This closed-loop control enables continuous skew correction throughout the conveying process without requiring complex multi-stage mechanical correction mechanisms.
Solution Approach 2:
The patent employs dynamic speed control of the rollers based on real-time skew detection from multiple units. The roller speeds are continuously adjusted according to the skew amounts detected at different positions, enabling adaptive skew correction that responds to actual sheet conditions rather than following a fixed multi-stage correction sequence.
Data Source
AI summary
To provide a sheet conveying technique that can realize highly accurate skew correction with an inexpensive and simple apparatus configuration. A sheet conveying apparatus includes: first and second rollers that are arranged in positions different from each other in a direction orthogonal to a sheet conveying direction and can be driven to rotate independently from each other; a first skew detecting unit that is arranged on an upstream side or a downstream side of the first and second rollers in the sheet conveying direction and detects skew of a sheet at first skew detection accuracy; and a second skew detecting unit that is arranged further on the downstream side than the first skew detecting unit in the sheet conveying direction and detects skew of the sheet at second skew detection accuracy higher than the first skew detection accuracy. A skew amount of the sheet is determined on the basis of detection results of the respective first and second skew detecting units. To reduce the determined skew amount, the first and second rollers are driven to rotate independently from each other and convey the sheet.