Acoustic Sensor Impedance Matching for Fingerprint Scanning
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Solution Overview
Problem
Acoustic sensing through a barrier, such as for fingerprint scanning, faces challenges in maintaining high image quality and resolution due to disturbances and impedance mismatches between the sensor and the barrier, leading to reduced accuracy in detecting fingerprint patterns.
Innovation Solution
Modifying the acoustic sensor and barrier to have matched acoustic impedance properties, adjusting the pillar geometry and material composition, and optimizing signal processing to focus on specific time windows for accurate impedance measurement, allows for improved image quality and resolution by minimizing resonance effects and beam widening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier is placed between the acoustic sensor and the fingerprint pattern, then the sensor is protected from wear and tear and damage, but the image quality and resolution are reduced due to acoustic impedance mismatches and disturbances
Solution Approach 1:
The patent introduces an acoustic matching layer as an intermediary between the sensor and the barrier. This layer has acoustic impedance properties that are intermediate between the sensor and the barrier, serving as a mediator to reduce acoustic impedance mismatch and improve signal transmission while maintaining sensor protection through the barrier.
Solution Approach 2:
The patent modifies the acoustic impedance parameters of the barrier and matching layer to optimize signal transmission. By carefully selecting materials and adjusting the thickness and acoustic properties of the matching layer, the system achieves better acoustic coupling between the sensor and the barrier, reducing distortion and maintaining measurement precision.
2Measurement precision
If the acoustic sensor is modified to improve image quality through barriers, then fingerprint scanning accuracy is enhanced, but the device complexity increases due to additional components and optimization requirements
Solution Approach 1:
The patent applies the local quality principle by creating a matching layer with specific acoustic properties only in the critical interface region between the sensor and barrier. Rather than modifying the entire sensor structure, the solution focuses on optimizing the local acoustic environment at the interface, thereby improving performance without significantly increasing overall device complexity.
3Measurement precision
If signal processing is optimized to focus on specific time windows, then measurement accuracy is improved, but the processing time and computational requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-determining the optimal time windows for signal analysis based on the known acoustic properties of the system. Rather than analyzing the entire signal spectrum, the system pre-identifies the critical time periods when relevant acoustic information is expected to occur, allowing for focused processing that maintains accuracy while reducing computational burden.
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
The solution significantly enhances the accuracy and resolution of fingerprint pattern scanning through barriers by reducing interference and resonance, resulting in high-quality images comparable to direct contact scenarios.
Implementation Method 1
acoustic impedance scanning of an object through a barrier
Implementation Method 2
transmitting acoustic energy towards the finger
Implementation Method 3
each pillar 116 is made from piezo-ceramic material
Implementation Method 4
acoustic energy that it, the sensor 110 transmits, encounters acoustic impedance
Data Source
AI summary
The invention provides embodiments of an apparatus and for improved, higher quality and higher resolution acoustic impedance scanning of an object through a barrier. Such acoustic impedance scanning can be employed to obtain biometric information of a person via fingerprint pattern.