Bi-Directional Ultrasonic Fingerprint Sensing With Range-Gate Control
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Solution Overview
Problem
Existing ultrasonic fingerprint sensors are unidirectional, limiting their functionality in devices with flexible orientations where fingerprint scans from multiple surfaces are uncertain.
Innovation Solution
Bi-directional ultrasonic fingerprint sensors with dual sets of piezoelectric transmitter, sensor material, and sensor pixel layers, or range-gate techniques, allowing simultaneous or near-simultaneous scanning from opposite device surfaces using a common controller or acoustic masking layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If unidirectional ultrasonic fingerprint sensors are used, then device structure is simple, but fingerprint scanning is limited to single surface
Solution Approach 1:
The patent implements bi-directional ultrasonic fingerprint sensing by enabling a single sensor system to perform fingerprint scanning from both front and rear surfaces of the device. This is achieved through acoustic masking layers that direct ultrasonic waves in opposite directions and a common controller that manages both scanning operations, allowing one sensor to fulfill multiple scanning functions instead of requiring separate unidirectional sensors for each surface.
Solution Approach 2:
The patent extends the fingerprint scanning capability from a single-dimensional (one-sided) approach to a two-dimensional (both-sided) approach by incorporating acoustic masking layers that enable ultrasonic waves to propagate in opposite directions. This dimensional expansion allows the sensor to capture fingerprints from both the front and rear surfaces of the device, effectively adding another spatial dimension to the scanning capability.
2Adaptability or versatility
If dual ultrasonic fingerprint sensors are used for bi-directional scanning, then fingerprint scanning flexibility is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes a single ultrasonic fingerprint sensor universal by enabling it to scan both front and rear surfaces through the implementation of acoustic masking layers and a bi-directional scanning control method. This eliminates the need for two separate unidirectional sensors, thereby reducing device complexity and cost while maintaining flexible bi-directional scanning capability.
Solution Approach 2:
The patent merges the functionality of two separate unidirectional fingerprint sensors into a single bi-directional sensor system. By combining the front and rear scanning capabilities into one sensor with acoustic masking layers and a unified controller, the system reduces component count, simplifies device structure, and lowers overall system complexity while achieving the same bi-directional scanning flexibility.
3Reliability
If separate controllers are used for dual sensors, then scanning reliability is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal bi-directional controller that manages both front and rear fingerprint scanning operations through a single control unit. This controller implements range-gate techniques and time-multiplexed control to reliably manage ultrasonic wave transmission and reception in both directions, eliminating the need for separate controllers while maintaining scanning reliability through sophisticated control algorithms.
Solution Approach 2:
The patent changes the operational parameters of a single controller to achieve bi-directional scanning reliability. By dynamically adjusting control parameters such as ultrasonic pulse timing, range-gate windows, and signal processing thresholds based on the scanning direction (front or rear), the controller maintains high scanning reliability without requiring duplicate hardware controllers.
4Adaptability or versatility
If acoustic masking layers are added for bi-directional scanning, then scanning versatility is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the acoustic path into distinct regions using acoustic masking layers that are positioned at specific locations within the sensor assembly. These layers create separate acoustic channels for front and rear scanning by blocking ultrasonic waves in unwanted directions. The segmentation of the acoustic field allows a single sensor to achieve bi-directional functionality while maintaining relatively simple manufacturing processes through precise layer positioning.
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 flexible fingerprint scanning in various device orientations, reducing complexity and cost by sharing a common controller and enhancing user interaction flexibility.
Implementation Method 1
the piezoelectric layer is used for both ultrasonic wave generation and ultrasonic wave detection
Implementation Method 2
Ultrasonic fingerprint sensors transmit and receive ultrasonic waves through a finger to obtain a fingerprint scan
Data Source
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AI summary
Apparatuses, systems, and methods are provided for ultrasonic fingerprint sensors that are able to be used to detect fingerprints from opposing sides of an apparatus, e.g., a smartphone with screens on both sides of the housing. Some implementations of such sensors may include, for example, two piezoelectric and sensor pixel layer assemblies coupled to a common controller. Other implementations of such sensors may include, for example, a single piezoelectric and sensor pixel assembly coupled with a controller configured to apply a range-gate delay to obtain fingerprint scans from either opposing side of an apparatus. Yet further implementations of such sensors may include acoustic masking layers to spatially filter ultrasonic waves propagating to either side of an apparatus.