Roll Sheet Feeder Trailing-Edge Detection to Prevent Sheet Jams

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Solution Overview

Problem

Existing sheet feeders face issues with erroneous detection of the trailing edge of roll sheets due to indirect detection methods, leading to potential sheet jams and operational inefficiencies.

Innovation Solution

A sheet feeder design that includes a sensor directly contacting the roll sheet surface to detect level differences at the trailing edge, using a roller positioned differently in the circumferential direction to confirm edge passage, and circuitry to accurately determine the trailing edge based on sensor signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If indirect detection methods (roller contact with sensor or motor current detection) are used to detect the trailing edge, then the device complexity is reduced, but the measurement precision deteriorates leading to erroneous detection

Engineering Contradiction:

Improvedetection system complexityVSAvoidtrailing edge detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces indirect mechanical detection methods (roller contact sensing or motor current monitoring) with direct optical sensing. The sensor directly contacts the roll sheet surface to detect level differences at the trailing edge, providing precise measurement without complex mechanical intermediary systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a sensor as an intermediary element positioned between the roll sheet and the detection system. This sensor directly contacts the roll sheet surface and detects level differences, serving as a mediator that provides accurate trailing edge detection without requiring complex mechanical or electrical analysis of the drive system.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If a single sensor position is used to detect the trailing edge, then the device complexity is reduced, but the reliability deteriorates due to erroneous detection

Engineering Contradiction:

Improvesensor configuration complexityVSAvoidtrailing edge detection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent divides the detection function into multiple sensor positions arranged in the circumferential direction. By detecting level differences at multiple positions and analyzing the sequence of detections, the system reliably identifies the trailing edge while filtering out false signals from surface irregularities.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where the detection results from multiple sensor positions are analyzed collectively. The system uses the sequential detection pattern across different circumferential positions to confirm trailing edge passage, providing feedback that eliminates erroneous detections and ensures reliable operation.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If direct contact detection with sensor is implemented, then the measurement precision is improved, but the device complexity increases due to multiple sensor positions

Engineering Contradiction:

Improvetrailing edge detection accuracyVSAvoidsensor and support structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent designs the support structure to serve multiple functions: it holds the roll sheet, positions the sensors in the circumferential direction, and provides a stable mounting platform. This multi-functional design reduces overall device complexity despite the addition of multiple sensor positions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the sensor positioning function with the roll sheet support structure. The support is designed to inherently provide the correct circumferential positioning for multiple sensors, merging the positioning mechanism into the support structure itself rather than adding separate positioning components.

Inventive Principle:

Principle #5Merging (Combining)

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

Enhances detection accuracy of the roll sheet trailing edge, reducing erroneous detections and preventing sheet jams, while allowing automatic sheet feeding and user notification of roll end exhaustion.

Implementation Method 1

a sensor that is at a first position on the support and contacts a surface of the roll sheet to detect a level difference at a trailing edge of the roll sheet and output a first signal and a second signal

Methodology Applied

Scientific EffectLevel difference detection:

Data Source

PatentUS12600591B2Sheet feeder and image forming apparatus

Publication Date: 2026.04.14 RICOH CO LTD

AI summary

A sheet feeder includes a support to support a roll sheet winding a sheet, a sensor that is at a first position on the support and contacts a surface of the roll sheet to detect a level difference at a trailing edge of the roll sheet and output a first signal and a second signal, a roller that is at a second position different from the first position in a circumferential direction of the roll sheet on the support and contacts the surface of the roll sheet to guide the roll sheet, and circuitry to cause the roll sheet to rotate in a sheet feeding direction to feed the sheet, and detect the trailing edge of the roll sheet based on the first signal output from the sensor, and the second signal output from the sensor.