Ultrasonic Transducer Q Spoiling via Independent Damping Circuit
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Solution Overview
Problem
Piezoelectric micromachined ultrasonic transducers (pMUTs) with higher quality factors (Q) suffer from reduced axial image resolution and undesired noise in images due to their construction.
Innovation Solution
The implementation of a second electrical circuitry with a switch, resistor, and capacitor configuration that dampens the motion of the diaphragm by shorting ports to a DC voltage when closed, independent from the primary circuitry, allowing for adjustable damping and dynamic behavior modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pMUT construction is used to achieve high transduction efficiency, then electrical to acoustic energy conversion is improved, but quality factor becomes too high causing reduced axial image resolution and increased noise
Solution Approach 1:
The patent introduces an intermediary electrical circuit connected to the pMUT ports that acts as a mediator between the high-Q transducer and the imaging system. This circuit includes resistive and capacitive elements that provide electrical damping to reduce the quality factor, thereby improving axial image resolution while preserving the energy-efficient transduction characteristics of the pMUT construction.
2Use of energy by moving object
If pMUT construction is used to achieve high transduction efficiency, then electrical to acoustic energy conversion is improved, but undesired noise is induced in images
Solution Approach 1:
The electrical circuit serves as an intermediary that filters and dampens the high-Q resonant behavior of the pMUT, converting the harmful oscillations into useful damped responses. The resistive elements dissipate excess energy that would otherwise manifest as noise, while capacitive elements shape the frequency response to eliminate unwanted resonances.
3Measurement precision
If second electrical circuitry with switch is added to dampen diaphragm motion, then quality factor is reduced and image quality improves, but device complexity increases
Solution Approach 1:
The patent employs a dynamic switching mechanism that allows the damping circuit to be activated or deactivated based on operational requirements. The switch enables flexible control over the damping effect, allowing the system to adapt between high-Q and low-Q modes as needed, thereby managing complexity while maintaining image quality improvement capabilities.
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 reduces the Q of pMUTs, thereby improving image quality and reducing noise, with the potential to modify dynamic behavior in various ways, including improved damping and energy efficiency.
Implementation Method 1
a piezoelectric element
Implementation Method 2
a second electrical circuitry connected to two or more of the plurality of electrical ports, the second electrical circuitry comprising a switch, wherein the switch is configured to leave one or more of the plurality of ports floating when open and short the one or more of the plurality of ports to a DC voltage when closed
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
Disclosed herein are ultrasonic transducer systems comprising: an ultrasonic transducer comprising a substrate, a diaphragm, and a piezoelectric element; a first electrical circuitry coupled to the ultrasonic transducer, the first electrical circuitry configured for driving the ultrasonic transducer or detecting motion of the diaphragm; a plurality of electrical ports coupled to the ultrasonic transducer; and a second electrical circuitry connected to two or more of the plurality of electrical ports, the electrical circuitry comprising one or more of: a resistor, a capacitor, a switch, and an amplifier, wherein the second electrical circuitry is independent from the first electrical circuitry, and wherein the second electrical circuitry is configured to dampen the motion of the diaphragm.