The Research And Design Of Electrostatic Ultrasonic Film Transducer

Ultrasound has the characteristics of with strong directivity,good penetrability,easily-focused energy,ultrasound has been widely used in the fields of medical imaging,industrial flaw detection and audio orientation.As the core component of ultrasound system,transducer determines the efficiency of system transduction,output power and other core indicators of the system’s key functions.The widely used piezoelectric ultrasonic nowadays still exists the problem of impedance mismatching with the transmission medium and the working frequency is limited and other issues.And as a new type of ultrasonic transducer,electrostatic thin film transducer has the character of easily-matched impedance,working frequency bandwidth and high sensitivity.Electrostatic thin film transducer can output strong directivity ultrasonic surface array especially in the field of application of audio directional system,which is more conducive to nonlinear self-demodulation of ultrasonic modulated signal in the air.With great advantages over regular audio directional transducer,electrostatic thin film transducer is gradually receiving the attention of researchers domestically and abroad.Chosen the application of electrostatic thin film ultrasonic transducer in the field of audio orientation as research thesis,this paper focuses on the research and design work of electrostatic thin film ultrasonic transducer.Mainly focusing on the theoretical model of the transducer,the structure design of transducer,multi-physics analysis and experimental testing,this paper’s research work mainly includes the following content:Firstly,describing the working principle of the acoustic directionality system based on ultrasonic transducers according to the Helmhotlz nonlinear acoustic theory,Westervelt acoustic parameter array theory and the KZK equation quasi-linear solution theory,and studying the influence of the structure size and resonant frequency of the electrostatic thin film ultrasonic transducer on the transducer frequency response and sound field directivity.Meanwhile,by solving the the elastic mechanics equation to investigate the influence mechanism of the thin film material and the vibration structural system on the frequency response,sensitivity,power and other characteristics of the transducer.Secondly,designing an effective electrostatic film ultrasonic transducer structure aiming at improving the sensitivity and directivity of the electrostatic ultrasonic transducer based on theoretical model to explore the effect of thin layer material,thickness and size on the center amplitude and resonant frequency of the transducer,analyzing transducer acoustic characteristics with the method of multiphysics by finite element simulation software COMSOL,and further verifying the effectiveness of the design structure using ANSYS software.Finally,through finite element simulation and prototyping test of the design results,the designed electrostatic ultrasonic transducer shows the characteristics of good directivity,high sound pressure level,and stable frequency response curve,which meets the application requirements of audio directional systems.pointing characteristics and other results.Comparing the theoretical calculation and simulation results,the performance of the transducer will be verified comprehensively.