Sheet Feeder Jam Detection via Encoder Measurement
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Solution Overview
Problem
Existing sheet feeders face issues with delayed jam detection due to displacement differences between transport means and sheets, leading to increased drive thresholds and potential sheet damage, especially when displacement is small.
Innovation Solution
A sheet feeder system with a transporter, measurer, and detector in a transport path, including a picking section and a separating section, where a driven roller with an encoder measures and detects the sheet's movement and leading edge, allowing early jam detection by monitoring the sheet's displacement and arrival at a downstream sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive amount threshold for jam detection is increased to account for displacement differences, then false jam detection is reduced, but sheet damage increases due to excessive roller rotation
Solution Approach 1:
A detection roller acts as an intermediary between the drive roller and the sheet. The detection roller rotates in response to sheet movement and provides accurate feedback on actual sheet displacement, independent of the drive roller's rotation. This intermediary measurement system enables precise jam detection without requiring high drive thresholds that would cause sheet damage.
Solution Approach 2:
The patent replaces the mechanical assumption-based jam detection (relying on drive roller rotation calculations) with a sensor-based detection system. The sheet detecting sensor directly measures sheet position and movement, substituting mechanical estimation with direct physical detection, thereby enabling accurate jam detection at lower drive thresholds.
2Reliability
If the drive amount threshold is set high to prevent false detection, then false jam detection decreases, but detection delay increases allowing sheet deflection and wrinkling
Solution Approach 1:
The detection roller serves as an intermediary that directly tracks sheet movement throughout the transport path. By placing detection sensors at multiple locations (including upstream and downstream of the separating section), the system continuously monitors sheet position without delay, enabling early jam detection even with low drive thresholds.
Solution Approach 2:
The patent implements upstream detection by placing a sheet detecting sensor before the separating section. This preliminary detection capability allows the system to identify jams early in the transport process, before significant sheet deflection or wrinkling can occur, enabling timely corrective action.
3Ease of operation
If a friction-based roller transport system is used, then sheet separation is achieved, but displacement difference between roller and sheet causes detection inaccuracy
Solution Approach 1:
The detection roller functions as an intermediary measurement device that independently tracks sheet displacement without relying on drive roller rotation. It directly follows sheet movement through light contact, providing accurate displacement data that reflects actual sheet transport regardless of friction-based slip between the drive roller and sheet.
Solution Approach 2:
The sheet itself serves as the driver for the detection roller through light frictional contact. The detection roller rotates in response to sheet movement, using the sheet's own motion to generate the measurement signal, thereby eliminating the need to rely on drive roller rotation for accurate displacement measurement.
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 early jam detection, reducing sheet damage by accurately determining transport displacement and preventing excessive rotation and wrinkling of sheets, even with varying sheet types and roller wear.
Implementation Method 1
a sheet existing on the top of the pile of sheets of document is picked by virtue of a frictional force generated at a portion thereof which comes into contact with the pick roller
Implementation Method 2
a separating resistance is applied to a sheet even when only a single sheet is transported
Data Source
AI summary
A transporter is adapted to transport a sheet in a transport direction in a transport path that includes a detecting range. A measurer is disposed at an upstream end of the detecting range in the transport direction, and is operable to measure a moving distance of the sheet. A detector is disposed at a downstream end of the detecting range in the transport direction, and is operable to detect a leading end edge of the sheet. A processor is operable to detect a jam in case that the moving distance is longer than a distance of the detecting range in the transport direction while the leading end edge of the sheet is not detected by the detector.