| 摘要 |
PURPOSE:To measure the sound pressure in liquid by a simple constitution, by providing an interdigital transducer in a container having a sound wave reflecting means. CONSTITUTION:A diaphragm which responds to pressure is provided in the container 10. The interdigital transducer 16 have a piezoelectric substrate 16a and interdigital electrodes 16b and 16c. The container 10 is filled up with the liquid 12. The transducer 16 is arranged so that the electrodes on the surface are contacted with the liquid. When an electric signal is applied to the electrode 16c from an amplifier 24 through a phase shifter 26, the signal is transduced into a sound wave at the electode part. The sound wave is propagated in the liquid 12, reflected by the diaphragm 14,and reaches the electrode 16b. Since the oscillating frequency is modulated by the sound pressure applied to the diaphragm in a frequency modulation mode, the sound pressure can be detected by detecting said signal. |
