PMUT Array Layout With Edge Sensors for Low-Noise Echo Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing PMUT designs face issues with noise interference from high voltage switches and inconsistent performance due to varying resonance frequencies and capacitance, which affect the accuracy and reliability of eye movement tracking, especially during fast pursuit.
Innovation Solution
The design incorporates separate transmitter and receiver PMUTs with a central transmitter and peripheral receiver PMUTs arranged in symmetric shapes, featuring cutouts in the dielectric layer to stabilize resonance and smaller receiver PMUTs to enhance sensitivity and stability, eliminating the need for a high voltage switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high voltage switch is used to disconnect the transmitter portion during reception, then potential interference with induced voltages is eliminated, but unwanted noise is introduced
Solution Approach 1:
The patent divides the PMUT array into separate transmitter elements and receiver elements. The transmitter PMUTs are dedicated to generating ultrasonic waves, while the receiver PMUTs are dedicated to detecting reflected waves. This segmentation eliminates the need for a high voltage switch during reception, as the transmitter and receiver portions operate simultaneously without interfering with each other, thus removing the noise source while maintaining signal detection accuracy.
Solution Approach 2:
Each PMUT element in the array can function as both a transmitter and a receiver at different times. The system uses time-division multiplexing where PMUTs alternate between transmitting and receiving modes, allowing the same hardware to serve multiple functions without requiring separate dedicated components for each role.
2Object-affected harmful factors
If separate transmitter and receiver PMUTs are used, then noise interference from high voltage switches is reduced, but device complexity increases
Solution Approach 1:
The patent combines the transmitter and receiver PMUTs into a single integrated array structure on one substrate. Both transmitter and receiver PMUTs share the same membrane, support structure, and fabrication process, merging what could be separate systems into a unified device. This reduces overall system complexity while maintaining the benefits of separate transmit and receive elements.
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 improves the stability and sensitivity of eye movement tracking by reducing noise interference and ensuring consistent performance, allowing for accurate detection of ultrasonic reflections and timely failure detection of transmitter PMUTs.
Implementation Method 1
A PMUT element is formed by a membrane suspended over a cavity carrying a layer of piezoelectric material sandwiched between thin electrode layers. In operation, a voltage is applied across the electrodes, resulting in a lateral strain being induced in the membrane via the piezoelectric effect causing movement of the piezoelectric layer.
Implementation Method 2
the plurality of second piezoelectric stacks are configured to generate sense voltages in response to bending thereof induced by vibration of the membrane by incoming ultrasonic reflections off the target
Implementation Method 3
ultrasonic waves are emitted toward the eye and reflections of the ultrasonic waves off the eye are detected. By measuring the time of flight of those ultrasound waves, distance to parts of the eye can be determined.
Data Source
AI summary
Disclosed herein is an array of ultrasound devices. Each ultrasound device includes a first piezoelectric stack carried by a membrane and forming, together with the membrane, a first piezoelectric micromachined ultrasonic transducer (PMUT), and a plurality of second piezoelectric stacks carried by the membrane and positioned about a periphery thereof, each second piezoelectric stack forming, together with the membrane, a second PMUT. During operation, the first piezoelectric stack is configured to vibrate the membrane in response to application of an alternating voltage to the first piezoelectric stack to thereby generate at least one outgoing ultrasonic pulse toward a target, and during operation, the plurality of second piezoelectric stacks are configured to generate sense voltages in response to bending thereof induced by vibration of the membrane by incoming ultrasonic reflections off the target.