Sheet Deskewing via Differential Roller Drive
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Solution Overview
Problem
Existing sheet lateral registration and deskewing systems for high-speed printing are costly and complex, requiring multiple high-power servo-motors and complex mechanisms to maintain sheet alignment and speed, which increases mass and expense, and can lead to sheet slippage and tearing.
Innovation Solution
A system using a single main drive motor for two sheet feed rolls with a lower power differential drive, enabling active automatic variable deskewing and lateral registration while maintaining continuous sheet movement, reducing total moving mass and cost, and eliminating the need for pivoting nips or dual-axis drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple high-power servo-motors are used for sheet feeding and deskewing, then sheet alignment and speed control are improved, but system cost and mass increase
Solution Approach 1:
The patent combines sheet feeding and deskewing functions into a single integrated mechanism. The sheet feeding mechanism includes a feed roller and an idler roller that work together to both advance the sheet and correct skew, eliminating the need for separate high-power servo-motors for each function. This merging reduces the total number of motors and their associated control systems, thereby reducing system mass while maintaining alignment precision.
Solution Approach 2:
The sheet feeding mechanism is designed to perform multiple functions: advancing the sheet forward, correcting lateral skew, and maintaining constant sheet speed. By making the feed roller and idler roller system multi-functional, the patent eliminates the need for dedicated deskewing motors, reducing overall system mass while achieving precise sheet alignment through the interaction of these rollers.
2Productivity
If high-power servo-motors are used for rapid lateral sheet movement, then lateral registration speed is improved, but system cost and power consumption increase
Solution Approach 1:
The patent merges lateral registration functionality into the sheet feeding mechanism itself. By using the differential rotation of the feed roller and idler roller, the system achieves rapid lateral sheet movement without requiring separate high-power lateral registration motors. This reduces power consumption while maintaining high lateral registration speed capability.
3Manufacturing precision
If complex deskewing mechanisms are used, then deskewing precision is improved, but device complexity increases
Solution Approach 1:
The patent simplifies the deskewing mechanism by merging it with the sheet feeding mechanism. Instead of using complex separate deskewing mechanisms, the system uses the interaction between the feed roller and idler roller to achieve precise deskewing. This reduces device complexity while maintaining deskewing precision through the geometric relationship and differential rotation of the rollers.
4Manufacturing precision
If sheet stoppages are used for registration, then registration accuracy is improved, but productivity decreases
Solution Approach 1:
The patent maintains continuous sheet movement throughout the registration and deskewing process. The feed roller and idler roller system operates continuously without stopping the sheet, achieving accurate registration through controlled differential rotation during motion. This eliminates sheet stoppages and associated delays, maintaining high sheet feeding rates while ensuring registration accuracy.
Data Source
AI summary
A closed loop feedback method that continuously adjusts the lateral and skew position of a sheet includes a first sensor that is used to measure lateral sheet edge position. A second sensor measures the lateral sheet edge position at a certain distance from the first sensor. Sheet skew values can thus be calculated. Lateral and skew controllers provide outputs to lateral and skew actuators, respectively, to adjust the sheet position. A different method of registering sheets laterally and in skew enables active sheet deskew without translating the sheet in the cross-process direction. A sensor carriage position is controlled to find the sheet edge after which deskew control can start. The average value of the carriage position can then be fed in a feedforward manner to move the image location to match the average paper position. This achieves good average lateral registration and active skew control at a reduced cost.