Sheet Feeding Tray Step Lowering for Jam Prevention
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Solution Overview
Problem
Conventional sheet feeding apparatuses face challenges in reliably positioning the uppermost sheet in a suckable range during initial operations, leading to potential double feeds or jams, especially with thin sheets, due to unstable blowing and subsequent lowering mechanisms.
Innovation Solution
A sheet feeding apparatus with a lifting and lowering tray, an air blowing portion, and a sheet detecting mechanism that controls the tray's movement to ensure the uppermost sheet is accurately positioned within the suckable range by repeating step lowering and stop operations based on detection signals from sheet surface sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the tray is continuously lowered to position the uppermost sheet in the suckable range, then the sheet positioning is achieved, but the blowing operation becomes unstable and the sheet may drop below the suckable range
Solution Approach 1:
The tray is lowered in periodic step movements rather than continuous motion. The controller lowers the tray by a first distance, stops, then lowers by a second distance, and stops again. This periodic action allows the blowing operation to stabilize at each position while progressively moving the uppermost sheet into the suckable range, preventing the sheet from dropping below the range while maintaining blowing stability.
2Productivity
If the tray is lowered rapidly to reduce positioning time, then productivity improves, but the sheet may not be stable enough for reliable feeding
Solution Approach 1:
The controller implements periodic lowering with intermediate stops to allow the sheet to stabilize at each position. This ensures reliable feeding while maintaining reasonable throughput. The step-wise approach with stops ensures the sheet is properly positioned and stable before the next feeding operation begins.
Solution Approach 2:
The sheet detecting mechanism detects the position of the uppermost sheet and provides feedback to the controller. Based on this feedback, the controller adjusts the tray lowering distances and stops accordingly, ensuring the sheet is properly positioned in the suckable range while maintaining stable blowing conditions for reliable feeding.
3Reliability
If the tray is lowered in small steps to maintain blowing stability, then the sheet positioning is stable, but the time required for positioning increases
Solution Approach 1:
The controller uses periodic lowering with varying step sizes. The tray is lowered by a first distance, stopped to stabilize blowing, then lowered by a second distance, and stopped again. This approach maintains blowing stability at each position while minimizing total positioning time through optimized step sizes and strategic stopping points.
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
This solution enables rapid and stable positioning of the uppermost sheet, reducing the likelihood of double feeds and jams by maintaining the sheet in a stable, suckable range, allowing for reliable sheet feeding operations.
Implementation Method 1
an air blowing portion 30 for blowing air to the end of a sheet stack on the tray 12 to blow up several sheets S, as well as to separate them from one another
Implementation Method 2
a suction fan 36 generating a negative pressure for causing the sucking and conveying belt 21 to suck the sheet S
Data Source
AI summary
An air blowing portion blows air to the end of sheets supported by a lifting and lowering tray. The sheets blown up by the air from the air blowing portion are sucked and conveyed by a sucking and conveying portion. The sheets are preliminarily blown up above the suckable rang. Then, the sheets are lowered to the suckable range before a sucking and conveying operation is started. In the above operation, the tray is lifted, and thereafter the tray is lowered until the sheets reach the suckable range while repeating a step operation of performing a lowering operation and a stop operation based on detection of the upper surface of the sheets by a sheet detecting mechanism.