Guided Bulk Wave Transducer Electrodes Without Differential Drive
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Solution Overview
Problem
Existing bulk wave transducers require a differential voltage source for effective acoustic coupling, which is impractical at high temperatures due to the need for midpoint transformers, complicating the electrical supply and limiting their application.
Innovation Solution
The transducer design features interdigitated elementary transducers with distinct lower and upper electrodes, allowing for single potential excitation from a referenced voltage source, eliminating the need for differential voltage sources and simplifying connections, while maintaining high acoustic coupling coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a differential voltage source is used to achieve good acoustic coupling, then acoustic coupling coefficient is improved, but device complexity increases due to the need for center-tapped transformers
Solution Approach 1:
The patent divides the electrode structure into distinct lower and upper electrodes for each elementary transducer, with each electrode being electrically independent. This segmentation allows each transducer element to be excited independently, eliminating the need for complex differential voltage sources and center-tapped transformers while maintaining effective acoustic coupling.
Solution Approach 2:
Instead of using a differential voltage source with respect to a common ground (traditional approach), the patent inverts the approach by using a reference voltage source where each elementary transducer's electrodes are independently connected to the reference potential. This inversion simplifies the electrical supply architecture while achieving the same acoustic coupling effect.
2Reliability
If center-tapped transformers are used to create differential voltage source, then acoustic coupling is improved, but ease of operation deteriorates due to simplified power supply connection
Solution Approach 1:
The patent segments the electrical connection architecture by providing distinct lower and upper electrodes for each elementary transducer, with independent electrical connections. This segmentation eliminates the need for center-tapped transformers, allowing direct connection to simple reference voltage sources and greatly simplifying power supply installation and operation.
Solution Approach 2:
The transducer structure is designed to be self-sufficient by incorporating all necessary electrical connection points (distinct lower and upper electrodes) directly into the transducer assembly. This eliminates the need for external transformer components and complex wiring, making the device easier to install and operate while maintaining effective acoustic coupling.
3Reliability
If midpoint transformers are used for high temperature applications, then acoustic coupling is maintained, but device complexity increases
Solution Approach 1:
The patent applies segmentation by providing electrically independent lower and upper electrodes for each elementary transducer, eliminating the need for midpoint transformers even in high-temperature applications. This segmented architecture maintains acoustic coupling effectiveness while removing temperature-sensitive transformer components, simplifying the overall device structure.
Solution Approach 2:
The patent inverts the traditional approach of using transformers for high-temperature applications by designing a transducer structure that directly accepts reference voltage sources. This inversion eliminates the need for temperature-sensitive transformer components while maintaining acoustic coupling performance in high-temperature environments.
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 design enables efficient acoustic coupling at high temperatures without the need for midpoint transformers, simplifying the electrical supply and expanding the transducer's applicability, including in high-temperature environments.
Implementation Method 1
a rod of piezoelectric material positioned on the lower electrode
Data Source
Figure 1~2d
Figure 3~4d
AI summary
The invention relates to a guided bulk wave transducer, comprising an acoustic substrate plate (10) made of electrically insulating material and a network of synchronous acoustic excitation sources, the network comprising a first comb (20) and a second comb ( 30) each comprising a plurality of elementary transducers (21; 31), the elementary transducers of the first and of the second comb being interdigitated and arranged in a direction (X) of propagation of the guided volume waves, the elementary transducers extending each along a transverse axis (Y). A transducer according to the invention is characterized in that each elementary transducer comprises a lower conductive electrode (22a, 22b, ... 22c; 32a, 32b, ..., 32c) positioned on the substrate, a bar of piezoelectric material ( 24a, 24b, ..., 24c; 34a, 34b, ..., 34c) positioned on the lower electrode and a conductive upper electrode (23a, 23b, ..., 23c; 33a, 33b, ..., 33c) positioned on the bar. Application for example to the production of on-board acoustic transducers without wires and without on-board energy source.