Acoustic Imaging System Architecture for Transparent Displays
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Solution Overview
Problem
Conventional fingerprint sensors in electronic devices are limited by the number of capacitive sensors, physical size, and integration time, and are optically opaque, making it difficult to integrate them into displays and achieving high resolution, especially when incorporating them into optically transparent materials like glass or sapphire.
Innovation Solution
An acoustic imaging system using a distribution of transducers disposed around a transparent substrate, such as a display cover, which generates and receives ultrasonic waves to create images of objects, like fingerprints, through mechanical deformations and impedance mismatches, allowing for high-resolution biometric sensing without obstructing the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive sensors are used for fingerprint sensing, then the sensor can detect fingerprint patterns, but the resolution is limited by the number of capacitive sensors and their physical size
Solution Approach 1:
The patent replaces conventional capacitive sensing with acoustic wave-based sensing. Instead of using multiple capacitive sensors to detect fingerprint patterns, the system uses acoustic waves propagating through the substrate to interact with the fingerprint ridges and valleys, enabling high-resolution imaging with fewer physical sensors.
Solution Approach 2:
The patent transitions from planar capacitive sensor arrays to three-dimensional acoustic wave propagation through the substrate thickness. By utilizing the vertical dimension and acoustic wave interactions, the system achieves high-resolution fingerprint sensing without requiring a dense two-dimensional array of capacitive sensors.
2Adaptability or versatility
If conventional capacitive sensors are used, then fingerprint detection is possible, but the sensors are optically opaque and difficult to incorporate into displays
Solution Approach 1:
The patent replaces optically opaque capacitive sensors with an acoustic sensing mechanism that uses the transparent substrate itself as the sensing medium. The acoustic waves propagate through the transparent substrate, allowing optical transparency to be maintained while enabling fingerprint sensing functionality.
Solution Approach 2:
The patent makes the transparent substrate serve multiple functions: it acts as both the display protective cover and the acoustic waveguide for fingerprint sensing. This eliminates the need for separate opaque sensor components, enabling seamless integration into displays while maintaining optical transparency.
3Measurement precision
If more capacitive sensors are added to improve resolution, then fingerprint image quality improves, but the physical size and integration time requirements increase
Solution Approach 1:
The patent replaces slow capacitive sampling with rapid acoustic wave propagation. Acoustic waves travel through the substrate and interact with the fingerprint pattern at the speed of sound, enabling much faster data acquisition compared to sequential capacitive sensor sampling, thereby reducing integration time while maintaining high image quality.
Solution Approach 2:
The patent enables continuous acoustic wave propagation through the substrate, allowing for continuous fingerprint pattern detection. This continuous action eliminates the need for sequential sampling of individual capacitive sensors, significantly reducing the total integration time required to capture a complete fingerprint image.
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
Enables high-resolution biometric imaging within the display of electronic devices, improving fingerprint recognition capabilities while maintaining transparency and usability, allowing for secure access to sensitive information.
Implementation Method 1
When in the drive mode, a transducer mechanically deforms in response to a drive signal
Implementation Method 2
When in the sense mode, a transducer produces an electrical signal in response to a mechanical deformation
Implementation Method 3
A transducer is mechanically deformed as a result of a mechanical wave such as a surface wave, shear wave, plane wave, or other acoustic wave type that propagates through a top surface and/or through the thickness of the substrate
Implementation Method 4
An acoustic reflection is generated by an acoustic impedance mismatch resulting from an object engaging the top surface of the substrate
Data Source
AI summary
An acoustic imaging system includes multiple transducers disposed to circumscribe a portion of substrate. An acoustic imaging system also includes a controller and an image resolver. The transducers convert electrical signals into mechanical energy and/or mechanical energy into electrical signals. The controller is adapted to apply an electrical signal to the transducers which, in response, induce a mechanical wave, such as a surface wave, into the circumscribed portion. The controller is also adapted to receive electrical signals from the transducers. The image resolver uses the electrical signals received by the controller in order to construct an image of an object in physical contact with the substrate.