Ultrasonic Transducer Arrays for Gaze Tracking
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Solution Overview
Problem
Designing gaze tracking circuitry for head-mounted devices that accurately tracks user gaze while minimizing power consumption and performance limitations, such as inaccurate measurements, is challenging.
Innovation Solution
The use of an array of ultrasonic transducers with different center frequencies on a common substrate, combined with control circuitry that adjusts phases and amplitudes to steer ultrasonic signals and determine eye position and direction, enhances positioning accuracy over short-range distances by simulating a single transducer with a larger bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single ultrasonic transducer with large bandwidth is used, then positioning accuracy is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides a single large-bandwidth transducer into multiple smaller transducers with different center frequencies arranged in an array. Each transducer has a narrow bandwidth, but collectively they cover a wide frequency range, achieving the positioning accuracy of a large-bandwidth transducer while simplifying individual transducer design and manufacturing.
Solution Approach 2:
The patent combines multiple narrow-bandwidth transducers with different center frequencies into a unified array system. By merging their outputs and using signal processing techniques, the system achieves the functional equivalent of a single large-bandwidth transducer, resolving the contradiction between accuracy and complexity.
2Measurement precision
If continuous ultrasonic signals are used for tracking, then measurement accuracy is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic pulsed ultrasonic signals instead of continuous waves. Transducers emit ultrasonic pulses at specific intervals, and by using multiple transducers with different frequencies, the system maintains accurate gaze tracking while significantly reducing average power consumption compared to continuous signaling.
Solution Approach 2:
The patent uses multiple transducers emitting at different frequencies simultaneously, where each transducer operates at lower power individually. The combined effect provides sufficient signal strength for accurate tracking without requiring any single transducer to operate at high power continuously, thus reducing overall power consumption.
3Reliability
If transducers are spaced farther apart to reduce interference, then signal clarity is improved, but phase disambiguation becomes more difficult
Solution Approach 1:
The patent applies different spatial arrangements to transducers based on their functional roles. Some transducers are placed closer together for phase disambiguation, while others are spaced farther apart to reduce mutual interference. This non-uniform spacing optimizes both signal clarity and phase measurement capability.
Solution Approach 2:
The patent varies the center frequencies of different transducers in the array. By changing the frequency parameter, the system can distinguish between signals from different transducers even when they are closely spaced, enabling phase disambiguation while maintaining signal clarity through frequency separation.
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 approach improves gaze tracking accuracy and reduces power consumption by allowing for shorter ultrasonic signal pulses and independent operation of transducers, effectively resolving the limitations of existing gaze tracking technologies.
Implementation Method 1
Ultrasonic transducers may be used to track the position of an object. For example, eyewear such as a pair of glasses or other head-mounted device may use ultrasonic transducers to track a user's eye position and gaze direction.
Implementation Method 2
The control circuitry may use time delay measurement techniques, phase delay measurement techniques, and/or amplitude measurement techniques to determine a distance and/or direction to the user's eye using the ultrasonic transducer arrays.
Implementation Method 3
The control circuitry may use time delay measurement techniques, phase delay measurement techniques, and/or amplitude measurement techniques to determine a distance and/or direction to the user's eye using the ultrasonic transducer arrays.
Implementation Method 4
The transducer arrays may include piezoelectric micromachined ultrasonic transducers, capacitive micromachined ultrasonic transducers, and/or other suitable type of ultrasonic transducers formed in a common substrate.
Implementation Method 5
The transducer arrays may include piezoelectric micromachined ultrasonic transducers, capacitive micromachined ultrasonic transducers, and/or other suitable type of ultrasonic transducers formed in a common substrate.
Implementation Method 6
Control circuitry may adjust the phases and/or amplitudes of the transducers in the array to steer the ultrasonic signal beam towards the user's eye (and away from direct paths to receiving transducer arrays, if desired)
Implementation Method 7
The transducers may be provided with different center frequencies by forming cavities with different depths, cavities with different diameters, and/or cavities with different surface features.
Data Source
AI summary
Ultrasonic transducers may be used to track the position of an object. For example, eyewear such as a pair of glasses or other head-mounted device may use ultrasonic transducers to track a user's eye position and gaze direction. To increase positioning accuracy over short-range distances, an array of ultrasonic transducers with different center frequencies may be formed on a common substrate. The closely spaced ultrasonic transducers with relatively small individual bandwidths may be used to simulate a single transducer with a larger bandwidth. Control circuitry may adjust the phases of the transducers in the array to steer the ultrasonic signal beam towards the user's eye and/or to receive an ultrasonic signal beam from the direction of the user's eye. The control circuitry may use time delay and/or phase delay measurement techniques to determine a distance and/or direction to the user's eye using the ultrasonic transducer arrays.