Passive Acoustic Fingerprint Sensing Without Ultrasonic Transmission
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Solution Overview
Problem
Existing biometric authentication technologies, such as those relying on frictional sound or ultrasonic waves, face challenges in providing reliable and cost-effective fingerprint detection, especially with dry fingers, and may leave residue on surfaces.
Innovation Solution
A passive acoustic fingerprint sensor system using a piezoelectric receiver array detects dynamic friction acoustic waves generated by a target object, such as a finger, without the need for a transmitter, allowing for fingerprint authentication and control systems to operate based on these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transmitter is used to transmit ultrasonic waves for fingerprint detection, then detection capability is improved, but power consumption and device cost increase
Solution Approach 1:
The system uses the finger itself as the acoustic source by detecting frictional sounds generated during natural finger movement across the sensor surface. This eliminates the need for an external ultrasonic transmitter, thereby reducing power consumption and device complexity while maintaining fingerprint detection capability through passive acoustic sensing
Solution Approach 2:
Instead of actively transmitting ultrasonic waves to the finger (active mode), the system passively receives acoustic signals generated by the finger's interaction with the sensor surface (passive mode). This inversion of the traditional active ultrasonic approach eliminates the transmitter component and its associated power consumption
2Ease of manufacture
If traditional frictional sound analysis is used, then cost is reduced, but detection reliability with dry fingers deteriorates
Solution Approach 1:
The system changes the acoustic detection parameters by using a piezoelectric receiver array that can detect a broader spectrum of frictional sounds generated during finger movement. This enhanced acoustic sensing capability improves detection reliability with dry fingers while maintaining the passive, low-cost architecture
3Measurement precision
If ultrasonic wave transmission is used, then detection precision is improved, but harmful factors (residue on surfaces) increase
Solution Approach 1:
The system detects acoustic signals generated by the finger's natural movement across the sensor surface without requiring contact between the sensor and finger. This non-contact detection approach eliminates residue deposition on the sensor surface while maintaining fingerprint detection precision through acoustic signal analysis
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 reduces power consumption, lowers costs, enhances security by avoiding residue, and improves reliability, especially with dry fingers, while enabling large-area sensor implementations.
Implementation Method 1
an acoustic receiver system including a piezoelectric receiver array configured for receiving dynamic friction acoustic waves produced via relative motion between an outer surface of the apparatus and a target object
Data Source
Figure 1
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Figure 3A~3E
AI summary
An acoustic receiver system may be configured for receiving dynamic friction acoustic waves produced via relative motion between an outer surface of an apparatus and a target object in contact with the outer surface. A control system may be configured for receiving acoustic signals from the acoustic receiver system. The acoustic signals may correspond to a first instance of the dynamic friction acoustic waves. The control system may be configured for extracting target object features from the first acoustic signals and for performing an authentication process based, at least in part, on the target object features.