Ultrasonic Transducer Sealed Transmission Path
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Solution Overview
Problem
Ultrasonic transducers face propagation attenuation due to large differences in acoustic impedance between materials, leading to inefficient energy transfer and interference from structural components, which limits the propagation distance and sensitivity.
Innovation Solution
The design incorporates a first and second membrane section with a housing structure that minimizes propagation distance and interference, using a MEMS-based ultrasonic transducer with an acoustic matching plate and annular section to create a sealed ultrasonic transmission path with reduced inner width, allowing for efficient energy transfer and reduced attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an acoustic matching layer is used to reduce acoustic impedance difference, then acoustic energy transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The patent introduces an acoustic matching layer as an intermediary substance between the piezoelectric element and air. This layer has intermediate acoustic impedance values between the high-impedance piezoelectric element and low-impedance air, serving as a mediator to facilitate gradual acoustic energy transfer and reduce reflection at the interface.
Solution Approach 2:
The acoustic matching layer is constructed from composite materials with specifically engineered acoustic impedance properties. By combining materials with different acoustic characteristics, the layer achieves optimal intermediate impedance values that bridge the gap between piezoelectric ceramic and air, maximizing acoustic energy transfer efficiency.
2Stability of the object's composition
If the piezoelectric element is bonded to the top plate of the housing, then structural stability is improved, but membrane deformation is interfered with causing decreased sound pressure
Solution Approach 1:
The patent divides the housing structure into separate functional components: the main housing body provides structural stability, while the top plate is designed as a separate acoustic transmission component. The piezoelectric element is positioned and bonded in a way that separates the structural support function from the acoustic vibration function, allowing the membrane to deform freely for sound generation while the housing maintains stability.
Solution Approach 2:
The top plate and surrounding wall portions are designed with specific local properties optimized for acoustic transmission. These regions have reduced structural rigidity locally to allow membrane deformation and sound pressure generation, while other parts of the housing maintain high structural stability. This local differentiation of mechanical properties resolves the contradiction between overall structural stability and local membrane flexibility.
3Loss of energy
If an ultrasonic transmission path is formed by a surrounding wall portion, then acoustic impedance matching is improved, but propagation distance increases causing increased attenuation
Solution Approach 1:
The patent transitions from a one-dimensional acoustic transmission path through the surrounding wall to a three-dimensional sealed space configuration. By creating a volumetric transmission environment rather than a linear path, the ultrasonic waves can propagate through multiple dimensions, reducing the effective propagation distance and minimizing attenuation while maintaining acoustic impedance matching benefits.
Solution Approach 2:
The ultrasonic transmission path is nested within the sealed space formed by the housing and acoustic matching plate. This nested configuration allows the transmission path to be embedded within the structural components rather than extending through them, reducing the propagation distance while maintaining the acoustic impedance matching function of the surrounding structures.
4Volume of moving object
If the structural body is miniaturized, then device size is reduced, but propagation loss cannot be minimized because inner diameter is larger than membrane diameter
Solution Approach 1:
The patent uses thin film membrane sections that are flexible and can be positioned close to the acoustic matching plate. This thin film construction allows the membrane diameter to be maximized relative to the overall device size, reducing the ratio between inner diameter and membrane diameter. The flexible nature of the thin film enables efficient acoustic coupling and reduces propagation loss even in miniaturized configurations.
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 enhances the efficiency of ultrasonic wave propagation by reducing attenuation and ensuring a large displacement of the membrane section, achieving high energy transfer rates and extended detectable distances.
Implementation Method 1
The piezoelectric element is bonded to an inner surface of a top plate of a bottomed tubular metal housing
Implementation Method 2
an acoustic matching layer having an intermediate acoustic impedance value between acoustic impedance values of the piezoelectric element and air is interposed between the piezoelectric element and air to increase the efficiency of acoustic energy transfer
Implementation Method 3
a first membrane section to perform flexural vibration
Data Source
AI summary
An ultrasonic transducer includes first and second acoustic transducers and a housing with a bottomed tubular shape. The second acoustic transducer includes an annular section supporting a second membrane section and contacting an entire periphery of the second membrane section, and an acoustic matching plate facing the second membrane section and spaced apart from the second membrane section. The acoustic matching plate is connected to a surrounding wall portion defining a sealed space with the housing. An ultrasonic transmission path sandwiched between the first membrane section and the second membrane section is provided in the sealed space. A maximum inner width of the ultrasonic transmission path is smaller than a maximum inner width of the surrounding wall portion.