To detect a pressure level with a simple structure by calculating, when a pressure is applied to at least one of a vibration generating means and a vibration detecting means, the size of the applied pressure based on the output characteristic of the vibration detecting means changed according to a pressure.
A pressure applied to a stacked layer body 13 is one applied to at least one surface of the stacked layer body 13 as indicated by pressures P1 and P2. In a vibration generating means 11, a high polymer piezoelectric body 11c is vibrated according to an oscillation signal generated by a signal generating section 15. Here, the frequency of the oscillation signal is f1. This vibration is propagated to the vibration detecting means 12, and the entire stacked layer body 13 is vibrated having a certain characteristic. In the vibration detecting means 12, a piezoelectric electromotive force is generated according to the vibration. When such an operation causes a pressure to be applied to the stacked layer body 13 composed of the vibration generating means 11 and the vibration detecting means 12, since the size of the applied pressure is calculated based on the output characteristic of the vibration detecting means 12 changed according to an applied pressure, a pressure level is detected with a simple structure.
NAGAI TAKESHI
YAMAMOTO KATSUHIKO
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