Sheet Feeder Pressing Mechanism for Bowed Sheet Restoration
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Solution Overview
Problem
Conventional sheet feeders struggle to reliably convey sheets that are bowed, as the first roller may not sufficiently contact the bottommost sheet, leading to sheet picking errors, and applying a large urging force to restore bowed sheets can result in double-feeds.
Innovation Solution
A sheet feeder design incorporating a pressing mechanism with a cam portion and springs that moves the pressing portion to adjust the force applied to the sheets, ensuring they are restored to their original flat state, allowing reliable contact with the first roller and preventing double-feeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large urging force is applied to restore bowed sheets, then the sheets are restored to their original flat state, but double-feeds occur
Solution Approach 1:
The pressing portion is designed to dynamically adjust its position between a first position (contacting the first roller) and a second position (separated from the first roller), allowing the urging force to be applied only when needed for bowed sheets. This dynamic adjustment prevents excessive force on already flat sheets, eliminating double-feeds while maintaining reliable restoration of bowed sheets.
Solution Approach 2:
The system uses the bowing state of the sheets themselves to trigger the appropriate action. When sheets are bowed, they naturally contact the pressing portion, which then applies urging force through the spring mechanism. Once flattened, the sheets no longer contact the pressing portion, automatically stopping the force application. This self-regulating mechanism prevents over-compression and double-feeds.
2Productivity
If the first roller contacts the bottommost sheet, then sheet conveyance occurs, but bowed sheets are not sufficiently contacted leading to picking errors
Solution Approach 1:
The pressing portion applies urging force to the stacked sheets before they reach the first roller, preliminarily restoring bowed sheets to their flat state. This preliminary action ensures that when the first roller contacts the bottommost sheet, the sheet is already flat and can be reliably picked and conveyed without picking errors.
3Reliability
If the pressing portion faces the first roller, then bowed sheets are restored, but the mechanism complexity increases
Solution Approach 1:
The pressing mechanism is merged with the existing sheet conveyance system. The pressing portion is integrated into the path between the stacked sheets and the first roller, and the spring mechanism is combined with the cam portion that controls the pressing motion. This merging approach achieves reliable sheet restoration without adding a completely separate complex mechanism.
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 design effectively restores bowed sheets to their original flat state, ensuring reliable sheet conveyance and preventing sheet picking errors and double-feeds, while avoiding excessive force on unbowed sheets.
Implementation Method 1
The first spring is configured to urge the pressing portion toward the first roller when the pressing portion is disposed between the first position and the second position
Implementation Method 2
The second spring is configured to urge the pressing portion toward the first roller when the pressing portion is disposed between the second position and the third position
Implementation Method 3
The cam portion is configured to rotate in one direction and in another direction. The cam portion contacts the pressing portion to move the pressing portion from the first position to the second position when the cam portion rotates in the one direction
Data Source
AI summary
A sheet feeder includes: a casing; a first roller; a pressing portion; a first spring; and a second spring. The pressing portion is movable between a first position and a second position via a third position. The pressing portion in the first position faces the first roller within a conveying region defined in the casing. The pressing portion in the second position is separated from the first roller farther than in the first position. The third position is located between the first position and the second position. The first roller is exposed to the conveying region. The first spring urges the pressing portion toward the first roller when the pressing portion is disposed between the first position and the second position. The second spring urges the pressing portion toward the first roller when the pressing portion is disposed between the second position and the third position.