| 摘要 |
PROBLEM TO BE SOLVED: To detect a sound pressure that is propagated by the contact with an elastic film. SOLUTION: When an input electric signal is applied to an interdigital electrode 2 for inputting, elastic waves are excited in a piezoelectric substrate 1. The leaked components of the elastic waves are propagated as a longitudinal wave in the liquid of a storage room 6, interdigital by an elastic film 5, and are detected as a first delayed electric signal by an screen type electrode 3 for first output. The non-leaked components of the elastic waves are detected as a second delayed electric signal by an interdigital electrode 4 for second output. If the elastic film 5 detects a sound pressure, difference is generated between the first and second delayed electric signals. The difference is detected by a signal analysis means 7.
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