Dual-Piezoelectric Ultrasonic Sensor Structure for Stronger Echo Signals
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Solution Overview
Problem
Existing ultrasonic sensors face challenges in achieving high performance due to increasing diversification of application scenarios, particularly in foldable and flexible screens, where ultrasonic wave penetration and signal integrity are compromised.
Innovation Solution
The ultrasonic sensor employs a dual-piezoelectric layer structure with opposite polarization directions and a half-wavelength phase difference, enhanced by an intermediate electrode layer, to superimpose ultrasonic waves and improve signal strength and reduce crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single piezoelectric layer is used in the ultrasonic sensor, then the device complexity is low, but the loop sensitivity and signal-to-noise ratio are insufficient
Solution Approach 1:
The piezoelectric layer is divided into multiple independent piezoelectric layers (first piezoelectric layer, second piezoelectric layer, etc.), each capable of generating ultrasonic waves. This segmentation allows each layer to contribute to the overall ultrasonic signal, thereby improving loop sensitivity and signal-to-noise ratio while maintaining manageable device complexity through modular design
Solution Approach 2:
Multiple piezoelectric layers are combined in a stacked configuration where they work together to generate and receive ultrasonic waves. The combined output of multiple layers enhances the overall signal strength and sensitivity of the ultrasonic sensor, resolving the contradiction between improved reliability and increased device complexity
2Reliability
If ultrasonic waves are transmitted through thick protective layers or multiple film layers, then the sensor can protect underlying components, but the ultrasonic wave attenuation increases and detection precision deteriorates
Solution Approach 1:
The patent optimizes the thickness parameters of protective layers and film layers to specific ranges that allow ultrasonic waves to pass through with minimal attenuation. By carefully controlling the thickness of each layer, the system maintains both component protection and high detection precision, resolving the contradiction between these two requirements
3Reliability
If the ultrasonic sensor is designed for high sensitivity detection, then the signal-to-noise ratio improves, but the device becomes more susceptible to external interference and harmful factors
Solution Approach 1:
The patent employs signal processing techniques that convert potential harmful effects into beneficial outcomes. For example, by using multiple piezoelectric layers with specific polarization configurations, the system can distinguish between genuine ultrasonic signals and external interference, thereby improving signal-to-noise ratio while maintaining robustness against harmful factors
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 configuration enhances loop sensitivity, increases signal-to-noise ratio, and improves fingerprint recognition capabilities, making it suitable for diverse screen technologies including foldable and flexible screens.
Implementation Method 1
the first piezoelectric layer and the second piezoelectric layer both receive an excitation voltage transmitted by the first ultrasonic transmit signal input port, and therefore, the intermediate electrode layer located between the first piezoelectric layer and the second piezoelectric layer receives an excitation voltage transmitted by the second ultrasonic transmit signal input port. Therefore, directions of electric fields applied to the first piezoelectric layer and the second piezoelectric layer are opposite.
Data Source
AI summary
Embodiments of this application provide an ultrasonic sensor and an operating method thereof, and an electronic device, and relate to the field of sensing detection technologies, to improve performance of the ultrasonic sensor. The ultrasonic sensor includes a substrate, and a circuit layer, a first electrode layer, a first piezoelectric layer, an intermediate electrode layer, a second piezoelectric layer, and a second electrode layer that are sequentially disposed on a same side of the substrate. The circuit layer includes a plurality of pixel circuits spaced from each other, the first electrode layer includes a plurality of electrode blocks spaced from each other, and the plurality of pixel circuits are correspondingly coupled to the plurality of electrode blocks. Polarization directions of the first piezoelectric layer and the second piezoelectric layer are the same.