Sheet Feeder Controller Timing Shutter and Feed Roller
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Solution Overview
Problem
Conventional sheet feeders face issues with reliable sheet separation and conveyance due to misalignment of stacked sheets, leading to potential double-feeds and increased frictional forces when the separation roller starts rotating before the regulating means releases its restriction.
Innovation Solution
A sheet feeder design incorporating a feed roller, a shutter, and a controller that controls the rotation of the feed roller and the movement of the shutter to ensure the shutter releases its restriction only after the feed roller has started rotating, reducing frictional forces and improving sheet alignment for smooth conveyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the separation roller starts rotating before the regulating means releases its restriction, then the sheet separation process can begin earlier, but the frictional force increases and sheet alignment deteriorates
Solution Approach 1:
The regulating means releases its restriction on the sheet leading edge before the separation roller starts rotating. This preliminary action reduces the frictional force acting on the sheet leading edge during the initial rotation phase, preventing sheet misalignment and improving sheet separation quality.
2Ease of operation
If the regulating means releases restriction early, then sheet conveyance is smoother, but the risk of double-feed increases
Solution Approach 1:
The regulating means releases its restriction slightly before the separation roller starts rotating, ensuring smooth sheet conveyance from the beginning. The controller then precisely controls the separation roller rotation to pick up exactly one sheet, preventing double-feeds while maintaining smooth conveyance throughout the process.
Solution Approach 2:
The controller monitors the sheet conveyance process and adjusts the separation roller rotation timing and speed based on the state of sheet conveyance. This feedback control ensures that the sheet is picked up smoothly after restriction release, maintaining single-sheet feeding reliability while preventing double-feeds.
3Productivity
If the feed roller rotates at high speed continuously, then productivity increases, but sheet alignment and separation quality deteriorate
Solution Approach 1:
The feed roller operates with periodic variation in rotational speed: rotating at a first speed during the first feeding process when the shutter restricts the sheet, then rotating at a second (lower) speed during the second feeding process after the shutter releases. This periodic speed variation maintains sheet alignment precision while achieving overall high productivity.
Data Source
AI summary
A sheet feeder includes: a feed roller; a shutter movable between a restricting position restricting a leading edge of a sheet and a non-restricting position releasing the restriction on the sheet; and a controller configured to control rotation of the feed roller and movement of the shutter. The controller is configured to perform: a first feeding process of controlling the feed roller to rotate at a first rotational speed while the shutter is at the restricting position and of controlling the shutter to move to the non-restricting position from the restricting position no earlier than rotation of the feed roller at the first rotational speed: a reduction process of controlling a rotational speed of the feed roller to be less than the first rotational speed; and a second feeding process of controlling the feed roller to rotate at a second rotational speed.