Capacitive Ultrasonic Transducers and Imaging Systems

摘要

The principles of ultrasonic ranging system are introduced first. The problems ofthe basic range measurement system are discussed with methods to improve the range precision. In addition the use of the beam pattern of a single transducer is studied. In this thesis a new equivalent circuit for capacitive ultrasonic transducers is introduced. The properties of capacitive ultrasonic transducers were studied in extensive measurement series. The resonant frequency, the bandwidth and sensitivity of ultrasonic transducers were measured and the results were published in many articles. This experimental research combined with theory of capacitive acoustic transducers gave a simple equivalent model for capacitive ultrasonic transducers. The model was used to improve the performance of the transducer array 'Lepakko' and in a simulator that includes ultrasonic transducers, acoustic path and electronic circuits. (Copyright (c) 1996 Valtion Teknillinen Tutkimuskeskus (VTT).)