Stacked-Membrane Ultrasonic Transducer With Dynamic Electrostatic Drive
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Solution Overview
Problem
Existing ultrasonic transducers face limitations in power and efficiency, particularly in membrane-based designs, with suboptimal force transfer and potential damage from high actuation signals, and there is a need for improved power and efficiency in these devices.
Innovation Solution
A stack of membranes with electrodes is used, where varying electric signals apply electrostatic and piezoelectric forces during vibration cycles to enhance amplitude and power, with phase-controlled vibrations to optimize displacement asymmetry and bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the actuation signal amplitude is increased to increase vibration amplitude, then the vibration amplitude is improved, but the risk of damage to the actuation mechanism increases and the transfer of force becomes suboptimal
Solution Approach 1:
The patent applies dynamic voltage variation during the vibration cycle rather than using a static high voltage. The voltage between membranes is dynamically adjusted to coincide with the vibration phase, providing enhanced force transfer during critical phases while avoiding continuous high-stress conditions that would damage the actuation mechanism.
Solution Approach 2:
The invention implements periodic voltage application synchronized with the vibration cycle. By applying varying voltage at specific phases of the vibration cycle (particularly when membranes are moving apart or at extreme positions), the system achieves enhanced vibration amplitude through resonant reinforcement rather than continuous high-amplitude actuation, thereby reducing cumulative stress on the mechanism.
2Device complexity
If a single membrane is actuated, then the structure is simple, but the power and efficiency are limited
Solution Approach 1:
The patent combines multiple membranes in a stacked configuration with electrostatic coupling between adjacent membranes. This merging of multiple membrane elements allows the system to generate higher ultrasonic power and efficiency compared to a single membrane, while maintaining a relatively compact and integrated structure. The electrostatic interaction between membranes creates a coupled system that amplifies the overall acoustic output.
3Stability of the object's composition
If static voltage is applied between membranes, then the structure is stable, but the vibration amplitude and power are suboptimal
Solution Approach 1:
The patent transitions from static voltage application to dynamic voltage variation. The voltage between membranes is modulated in sync with the vibration cycle, creating time-varying electrostatic forces that reinforce the mechanical vibration. This dynamic approach maintains stable average membrane spacing while achieving peak power enhancement during critical vibration phases, resolving the contradiction between structural stability and power output.
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
The solution enhances vibration amplitude and power in ultrasonic transducers, improving efficiency and bandwidth by dynamically varying electrostatic and piezoelectric forces between membranes, leading to more effective ultrasonic wave transmission and reception.
Implementation Method 1
The first electrode on the first membrane is configured to interact with the second electrode on the second membrane by a varying electrostatic force during the respective vibration cycle depending on the varying voltage
Implementation Method 2
actuation can be effected by a piezoelectric transducer coupled to the membrane. Depending on the electrical signal, the piezoelectric material may expand or contract which can result in vibration of the membrane
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
An ultrasonic transducer (100) comprises a stack of at least two membranes (10,20) attached to a substrate (50). An electric circuit (30) is coupled to the electrodes with a controller configured to apply a first electric signal (S1 1) to a first electrode (11) on the first membrane (10), and a different, second electric signal (S2 1) to a second electrode (21) on the second membrane (20). The first and second electric signals (S1 1,S2 1) are configured to apply a varying voltage (ΔV1,ΔV2) between the first electrode (11) and the second electrode (12) during a respective vibration cycle (T1,T2) of the membranes (10,20). The first electrode (11) on the first membrane (10) is configured to interact with the second electrode (21) on the second membrane (20) by a varying electrostatic force (Fe) during the respective vibration cycle (T1,T2) depending on the varying voltage (ΔV1,ΔV2).