Ultrasonic Transducer Beam Angle Control via Acoustic Transformer
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Solution Overview
Problem
Existing ultrasonic transducers in gaseous mediums have limited flexibility in producing desired acoustic radiation patterns, with fixed beam angles and sensitivity, particularly when using polarized ceramic materials.
Innovation Solution
A novel acoustic transformer design with adjustable dimensions and a half-wavelength resonant structure, allowing for the creation of various acoustic radiation patterns, including conical and fan-shaped patterns, by modifying the diameter and shape of the acoustic transmission line relative to the ceramic disc, and incorporating a sealed plastic housing for environmental protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the beam angle is fixed by the ceramic disc diameter at resonant frequency, then the transducer structure is simple, but the adaptability to produce different acoustic radiation patterns is limited
Solution Approach 1:
The transducer is divided into functionally independent segments: the ceramic disc (fixed, determines resonant frequency) and the acoustic transmission line (variable, controls beam angle). This segmentation allows each component to be optimized independently - the ceramic for frequency stability and the transmission line for radiation pattern control - thereby achieving multiple functions without proportionally increasing overall complexity.
Solution Approach 2:
The invention introduces dynamic adjustability by making the acoustic transmission line dimensions independent of the ceramic disc dimensions. The transmission line can be designed with variable diameter and length to dynamically control the beam angle and acoustic radiation pattern, transforming a static system into one that can be adapted for different applications while maintaining a relatively simple base structure.
2Shape
If the acoustic transmission line diameter is reduced to increase beam angle, then the beam angle increases, but the sensitivity of the transducer decreases
Solution Approach 1:
The invention utilizes parameter changes in the acoustic transmission line - specifically its diameter and length relative to the ceramic disc - to control the beam angle. By optimizing these dimensional parameters, the system achieves desired radiation patterns while compensating for potential sensitivity losses through proper impedance matching and resonance tuning, rather than simply reducing the transmission line diameter.
Solution Approach 2:
The acoustic transmission line acts as an intermediary element between the ceramic disc and the gaseous medium. It mediates the acoustic energy transfer, transforming the vibration from the ceramic into a controlled radiation pattern in the gas. This intermediary function allows independent optimization of the beam angle without directly compromising the ceramic's sensitivity, as the transmission line can be designed to maintain acoustic impedance matching throughout its length.
3Reliability
If a sealed housing is used to provide environmental protection, then the reliability improves, but the acoustic transmission from the transducer is blocked
Solution Approach 1:
The invention extracts the acoustic transmission function from the housing structure by providing an acoustically transparent window or opening in the sealed housing. This allows the housing to maintain its environmental protection function while the extracted acoustic path enables uninterrupted sound transmission from the transducer to the external medium, effectively separating the protective and transmissive functions.
Solution Approach 2:
The housing incorporates an acoustically transparent window or thin film structure that is impermeable to environmental contaminants but permeable to acoustic waves. This flexible or semi-rigid barrier allows the sealed housing to protect the transducer from environmental factors while simultaneously transmitting acoustic energy, resolving the contradiction between protection and acoustic transmission.
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
Enables the production of transducers with customizable beam angles and improved environmental protection, enhancing sensitivity and temperature stability while maintaining broad frequency response and reduced secondary lobes.
Implementation Method 1
The acoustic transformer material is characterized in that its acoustic impedance is less than the acoustic impedance of the ceramic, but greater than the acoustic impedance of the gaseous medium. The acoustic impedance of a material is its density, ρ, times the velocity of sound, c, in the material.
Implementation Method 2
For optimum performance, the transducer is operated in the vicinity of resonance. This disc could operate in the thickness mode of resonance, but in the preferred embodiment the ceramic disc operates in the radial mode of resonance
Implementation Method 3
In addition, the thickness of the acoustic transformer material is approximately one quarter of a wavelength
Data Source
AI summary
An ultrasonic transducer utilizes an acoustic transmission line to increase the sensitivity of both the transmitting response and the receiving response. The resonant element of the transducer could employ a ceramic disc operating in the radial resonance mode for its transduction means, or it could be a half wavelength resonator utilizing a forward transmission line, a rear transmission line, and a non-resonant ceramic for transduction. The shape of the forward transmission line is designed to generate the desired acoustic radiation pattern at the frequency of resonance, which could be a broad or narrow conical beam or a fan shaped beam. A sealed housing structure is disclosed that contains the forward transmission line that is acoustically disconnected from the rest of the housing. This housing provides improved environmental protection and allows for easy mounting of the transducer without effecting its electroacoustic response characteristics.