| 摘要 |
PURPOSE:To measure the change with time in pressure of an object to be measured readily by an ultrasonic wave element wherein two electrodes in which a pair of comb shaped electrodes are interdigitally combined are arranged on a piezoelectric substrate. CONSTITUTION:The ultrasonic wave element 12 has input and output transducers 14 and 15 wherein two electrodes 14' and 15' are separately arranged on the piezoelectric substrate 13. A pair of comb shaped electrodes are interdigitally combined in said electrodes 14' and 15'. A pressure plate 16 is a thin plate which is vibrated in response to the pressure change in the object to be measured and made of a material that reflects the ultrasonic wave. The pressure plate 16 and the ultrasonic wave element 12 are separately held in a container 11, and a space part 18 is filled with liquid. An ultrasonic wave beam radiated from the input transducer 14 at an angle theta is reflected by the pressure plate 16, received by the output transducer 15, and converted into an electric signal. Since the pressure plate 16 is vibrated when the pressure is applied, the transmitting path length of the beam is varied, and the phase variation is generated in the delayed output signal. |
