Sheet Feeder Back-Tension Compensation for Accurate Positioning
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Solution Overview
Problem
Conventional sheet feeders experience issues with accurately compensating for the shortage in sheet feed movement due to back tension, leading to suboptimal image recording and reading quality, especially when handling various types of papers with different thicknesses and surface conditions.
Innovation Solution
A sheet feeder system with a pair of feed rollers and a motion controller that applies a back-tension compensation by adjusting the rotational motions to account for the back tension, ensuring accurate sheet feed distance through predetermined and supplementary rotational amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sheet is fed along a curved feed path with a feed path definer, then the sheet can be guided through the device, but friction is generated between the sheet and the feed path definer creating back tension that impedes feed movement
Solution Approach 1:
The system applies preliminary anti-action by calculating the back tension force that will act on the sheet during curved feed path traversal, and pre-compensating for it by rotating the feed rollers by an additional amount beyond the nominal feed distance. This anticipatory compensation prevents the sheet from actually falling short of the target position.
Solution Approach 2:
The system changes the rotation parameter of the feed rollers dynamically. Instead of rotating by a fixed nominal amount, the rollers are rotated by a compensated amount that varies based on sheet properties (thickness, surface condition) and feed path characteristics. This parameter adjustment ensures accurate feed positioning despite varying back tension conditions.
2Productivity
If the sheet supply roller is held in pressing contact with the sheet, then the sheet can be supplied toward the feed path, but the pressing contact force contributes to back tension causing slipping of feed rollers relative to the sheet
Solution Approach 1:
The system adjusts the rotation parameter of the feed rollers to compensate for slipping caused by pressing contact forces. By calculating the expected slip based on sheet properties and roller pressure, the system rotates the rollers by an additional compensated amount to ensure the sheet reaches the correct position despite the slipping.
3Productivity
If the feed rollers are intermittently driven to feed the sheet by a predetermined amount, then the sheet can be fed for image recording, but the actual feed movement is shorter than the predetermined amount due to back tension
Solution Approach 1:
The system changes the rotation parameter of the feed rollers from a fixed predetermined amount to a dynamically compensated amount. The compensation is calculated based on sheet properties (thickness, surface condition), feed path characteristics (curvature), and roller conditions (pressing force). This ensures the actual feed distance matches the intended distance despite back tension effects.
Solution Approach 2:
The system employs feedback by detecting sheet properties (thickness, surface condition) and using this information to adjust the roller rotation amount. The detected sheet characteristics are fed back to the control system, which then calculates the appropriate compensation and adjusts the intermittent rotation of the feed rollers accordingly to achieve accurate positioning.
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 system effectively compensates for the actual feed movement shortage, improving the quality of image recording and reading by ensuring consistent and accurate sheet feeding, even with diverse paper types.
Implementation Method 1
the sheet feed rollers are intermittently driven or rotated, so as to feed the sheet in a sheet feed direction
Implementation Method 2
a back-tension applier disposed in the feed path, and configured to apply a back tension to the sheet that is fed along the feed path
Data Source
AI summary
A sheet feeder including: (a) a pair of feed rollers operable to have a plurality of successive rotational motions, so as to be rotated by a predetermined amount in each one of the successive rotational motions, for thereby causing a sheet nipped between the pair of feed rollers, to be fed along a feed path by a desired distance as a result of the each one of the successive rotational motions; (b) a back-tension applier disposed in the feed path, and configured to apply a back tension to the sheet that is fed along the feed path; and (c) a motion controller configured to control the successive rotational motions of the feed rollers, and to command the feed rollers to be rotated by a compensated amount that includes a supplementary amount in addition to the predetermined amount, in each of at least one of the successive rotational motions. Also disclosed is a process of feeding a sheet, by using the sheet feeder.