Document Transport Double-Feed Detection with Cumulative Thresholds

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Solution Overview

Problem

Existing scanners face issues with false detection of double feeding due to varying document thickness, particularly with instant photographs and sheets with attachments, leading to incorrect reading and user inconvenience.

Innovation Solution

A document transport device with a control unit that determines double feeding by setting a theoretical threshold based on transport path and calculating a cumulative value from detection results, considering both document thickness and transport length to accurately detect double feeding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ultrasonic wave attenuation detection is used to detect double feeding, then double feeding detection capability is provided, but false detection increases due to varying document thickness

Engineering Contradiction:

Improvedouble feeding detection accuracyVSAvoiddetection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary detection of document thickness variations using the ultrasonic sensor before making the final double feeding determination. By detecting thickness changes in advance and comparing them against predetermined thresholds, the system can distinguish between actual double feeding and false signals caused by document thickness variations, thereby reducing false detection while maintaining detection accuracy

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control unit continuously monitors the output signal from the ultrasonic sensor and uses feedback to adjust the detection threshold dynamically. When document thickness variations are detected, the system adjusts the threshold accordingly, allowing accurate differentiation between real double feeding events and false signals, thus improving both reliability and measurement precision

Inventive Principle:

Principle #23Feedback

2Speed

If simple threshold-based double feeding detection is used, then detection speed is fast, but false detection occurs with instant photographs and sheets with attachments

Engineering Contradiction:

Improvedetection speedVSAvoiddetection accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The detection threshold is made dynamic rather than fixed. The control unit adjusts the threshold based on real-time analysis of ultrasonic signal patterns and document characteristics. This dynamic adjustment allows the system to maintain fast detection while adapting to different document types such as instant photographs and sheets with attachments, preventing false detection without sacrificing speed

Inventive Principle:

Principle #15Dynamics

3Reliability

If double feeding detection stops reading processing, then incorrect reading is prevented, but user convenience deteriorates due to manual intervention requirements

Engineering Contradiction:

Improvereading accuracyVSAvoiduser convenience

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system automatically determines whether double feeding has occurred and initiates appropriate processing without requiring user intervention. When double feeding is detected, the control unit automatically stops the reading process and notifies the user, eliminating the need for manual checking and improving both reading accuracy and user convenience by making the system self-regulating

Inventive Principle:

Principle #25Self-service

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

Reduces false detection of double feeding, ensuring accurate reading by stabilizing detection through cumulative value calculations and threshold adjustments, minimizing user intervention.

Implementation Method 1

such scanners have an ultrasonic wave transmitter and an ultrasonic wave receiver facing each other having a document therebetween to determine double feeding based on a degree of attenuation of the intensity of ultrasonic waves when documents are fed

Methodology Applied

Scientific EffectUltrasonic wave attenuation: Ultrasound

Data Source

PatentUS20250230008A1Document transport device, document transport method, and document transport control system

Publication Date: 2025.07.17 SEIKO EPSON CORP

AI summary

A theoretical threshold corresponding to a transport path is set, and a control unit acquires a calculation value calculated based on a detection result of double feeding detection unit and a transport length of a document, determines occurrence of double feeding when the calculation value is greater than the theoretical threshold (step S120), and determines non-occurrence of double feeding when the calculation value is smaller than the theoretical threshold. In addition, if a non-detection period for double feeding occurs (step S110), the control unit sets a cumulative value in step S115. As a result, detection of double feeding is ended in a short period while a document is being transported, and in a case that double feeding is no longer detected, determination of double feeding will not be made.