Sheet Feeder Pressing Mechanism for Jam Reduction
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Solution Overview
Problem
Conventional sheet feeders often experience paper jams due to interference between sheets, particularly when thin or low-stiffness paper is conveyed, as the trailing edge of a preceding sheet can hinder the introduction of a succeeding sheet, leading to deformation and jamming.
Innovation Solution
A sheet feeder design that includes a pressing mechanism with a movable pressing portion and a cam portion, which adjusts its position to prevent interference by ensuring a sufficient gap between the pressing rollers and the conveying path, allowing sheets to be conveyed without deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressing portion is positioned close to the first roller to press the sheet firmly, then the sheet separation is improved, but the trailing edge of the preceding sheet interferes with the succeeding sheet causing paper jams
Solution Approach 1:
The pressing portion is made movable along the conveying direction rather than being fixed. It can dynamically adjust its position between a first position (upstream, closer to the first roller) for effective sheet separation and a second position (downstream, farther from the first roller) to avoid interfering with the trailing edge of the preceding sheet. This dynamic positioning resolves the contradiction between needing firm pressing for separation and avoiding paper jams.
Solution Approach 2:
The pressing portion is positioned upstream (in the first position) before the sheet conveyance begins, allowing it to press the sheet firmly against the first roller for proper separation. After the sheet is successfully separated and conveyed, the pressing portion moves downstream to the second position before the trailing edge passes, preventing interference with the succeeding sheet. This preliminary positioning and subsequent adjustment prevents paper jams while maintaining effective separation.
2Productivity
If the pressing portion is positioned upstream to press the sheet against the first roller, then sheet conveyance is effective, but the pressing portion interferes with the trailing edge of the preceding sheet
Solution Approach 1:
The pressing portion transitions from a static component to a dynamic one that can move along the conveying direction. It is positioned upstream (first position) during the sheet pressing and conveyance phase to maintain effective sheet conveyance. After completion, it moves downstream (second position) to clear the path for the trailing edge of the preceding sheet, eliminating interference while preserving conveyance efficiency.
Solution Approach 2:
The pressing portion is preliminarily positioned upstream (first position) to perform the sheet pressing action effectively. After the sheet is conveyed, it moves to the second position downstream, clearing the conveying path before the trailing edge passes. This preliminary upstream positioning ensures effective conveyance, while the subsequent movement prevents interference.
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 reduces the probability of paper jams by maintaining a clear path for sheet conveyance, even with thin or low-stiffness paper, by ensuring the pressing rollers do not apply excessive pressure that could cause curling or interference.
Implementation Method 1
A spring urges the pick arm toward the first roller
Implementation Method 2
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; and a pressing portion. The casing defines therein a conveying region through which a sheet is conveyed in a conveying direction. The first roller has a rotation axis extending in an axial direction crossing the conveying direction and rotatable about the rotation axis. The first roller has a portion exposed to the conveying region. The pressing portion is movable in a direction crossing the conveying region between a first position and a second position. The pressing portion is urged toward the first roller to provide the first position. The pressing portion in the first position has a portion disposed within the conveying region and spaced apart from the first roller by a prescribed distance. The pressing portion in the second position is separated from the first roller farther than in the first position.