Ultrasonic Double Feed Detection Circuit for Image Scanners
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Solution Overview
Problem
Existing image processing apparatuses, such as scanners and printers, face challenges in accurately distinguishing between true double feeding and defects in the double feed detection sensor, leading to uncertainty in determining the cause of detected double feeding.
Innovation Solution
Incorporating a comparison circuit that compares the level signal of the ultrasonic wave reception with a threshold signal to determine if sheets are double-fed, and using a control unit to assess the possibility of defects in the double feed detection function, thereby differentiating between true double feeding and sensor defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double feed detection sensor using ultrasonic waves is used to detect double feeding, then double feeding can be detected, but it becomes difficult to determine whether the detected double feed is due to true double feed or sensor defects
Solution Approach 1:
The patent divides the detection function into two independent parts: a double feed detection sensor for detecting double feeding events, and a monitoring sensor for monitoring the sensor's own operational status. This segmentation allows the system to distinguish between actual double feed conditions and sensor defects by comparing signals from both independent detection components.
Solution Approach 2:
The patent introduces a monitoring sensor as an intermediary component that indirectly assesses the health status of the double feed detection sensor. This monitoring sensor acts as a mediator between the detection system and the control unit, providing information about sensor defects without directly performing the primary double feed detection function.
2Device complexity
If only a double feed detection sensor is used, then the system remains simple, but the system cannot differentiate between true double feeding and sensor defects
Solution Approach 1:
The monitoring sensor serves multiple functions: it monitors the operational status of the double feed detection sensor, provides defect information to the control unit, and enables differentiation between true double feed and sensor defects. This multi-functionality adds capability without requiring a completely separate monitoring system.
Solution Approach 2:
The patent implements a feedback mechanism where the monitoring sensor continuously provides status information about the double feed detection sensor to the control unit. This feedback loop enables the system to adjust its interpretation of detection signals based on the current health status of the sensor, improving overall measurement precision.
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 allows for accurate determination of whether detected double feeding is due to actual overlap or sensor defects, improving usability by enabling users to identify and address potential issues effectively.
Implementation Method 1
The transmitter transmits an ultrasonic wave to a conveyance path through which a sheet is conveyed
Implementation Method 2
The receiver is provided so as to face the transmitter with the conveyance path in between, and receives the ultrasonic wave transmitted by the transmitter
Implementation Method 3
a slight air layer between the sheets attenuates the ultrasonic wave more than in the case of one sheet
Data Source
AI summary
An image processing apparatus includes a transmitter, a receiver, a comparison circuit, and a control unit. The transmitter transmits an ultrasonic wave to a conveyance path through which a sheet is conveyed. The receiver faces the transmitter with the conveyance path in between, and receives the ultrasonic wave transmitted by the transmitter. The comparison circuit compares a level signal indicating a reception level of the ultrasonic wave received by the receiver with a threshold signal for determining whether or not the sheet is double-fed in the conveyance path, and outputs a comparison result signal according to the comparison result. The control unit determines whether or not there is a possibility of a defect in the double feed detection function of detecting double feed based on the comparison result signal and the level signal.