Ultrasonic Multi-feed Detection with Lookup Table Amplification
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Solution Overview
Problem
Conventional methods for determining multi-feed in sheet conveying devices using ultrasonic waves are prone to false determinations due to device-to-device variations, affecting noise filtering characteristics and operational amplifier stability, leading to reduced accuracy.
Innovation Solution
A sheet conveying device with a sending unit, receiving unit, adjusting unit, and determining unit that adjusts and amplifies ultrasonic wave voltages to accurately determine multi-feed, using preset amplification factors and reference values to minimize device-to-device variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the amplification factor of the amplifier circuit is adjusted to compensate for device-to-device variation in ultrasonic wave attenuation, then the accuracy of multi-feed determination is improved, but the noise filtering characteristics of the amplifier circuit are changed and operational amplifier oscillation occurs
Solution Approach 1:
The patent extracts the amplification function from the amplifier circuit and implements it separately through a look-up table stored in non-volatile memory. The look-up table contains pre-calculated amplification factors for different sheet types, allowing the system to compensate for ultrasonic wave attenuation variations without modifying the amplifier circuit's noise filtering characteristics. This separation eliminates the oscillation problem while maintaining determination accuracy.
Solution Approach 2:
The patent creates a digital copy of the amplification function through the look-up table in non-volatile memory, rather than using an analog amplifier circuit adjustment. The look-up table stores pre-calculated voltage values corresponding to different sheet types, enabling the system to replicate the desired amplification effect without the physical constraints and stability issues of traditional amplifier circuits.
2Measurement precision
If conventional amplifier circuit adjustment is used to compensate for ultrasonic wave variation, then device-to-device variation is reduced, but noise filtering characteristics are degraded and false multi-feed determination occurs
Solution Approach 1:
The patent extracts the amplification function from the amplifier circuit and implements it separately through a look-up table stored in non-volatile memory. The look-up table contains pre-calculated amplification factors for different sheet types, allowing the system to compensate for ultrasonic wave attenuation variations without modifying the amplifier circuit's noise filtering characteristics. This separation eliminates the oscillation problem while maintaining determination accuracy.
Solution Approach 2:
The patent changes the parameter storage method from continuous analog adjustment to discrete digital lookup. By storing pre-calculated voltage values in non-volatile memory for different sheet types, the system can select the appropriate amplification factor without continuously adjusting the amplifier circuit, thereby preserving noise filtering characteristics while achieving accurate compensation.
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 approach enhances the accuracy of multi-feed determination by stabilizing noise filtering characteristics and preventing operational amplifier oscillations, thereby improving the reliability of multi-feed detection.
Implementation Method 1
a receiving unit positioned to face the sending unit across a conveyance path, along which a sheet is conveyed, and configured to receive a first ultrasonic wave, the first ultrasonic wave being an ultrasonic wave sent from the sending unit and passed through the sheet, and output a first voltage corresponding to the first ultrasonic wave
Data Source
AI summary
A sheet conveying device includes: a sending unit configured to send an ultrasonic wave; a receiving unit positioned to face the sending unit across a conveyance path, along which a sheet is conveyed, and configured to receive a first ultrasonic wave, the first ultrasonic wave being an ultrasonic wave sent from the sending unit and passed through the sheet, and output a first voltage corresponding to the first ultrasonic wave; an adjusting unit configured to adjust the first voltage into an adjusted first voltage according to a setting; an amplification unit configured to amplify the adjusted first voltage by a preset amplification factor for multi-feed determination into an amplified first voltage; and a determining unit configured to determine whether or not multi-feed of the sheet has occurred based on the amplified first voltage.