| 摘要 |
PURPOSE:To detect pressure which has a wide temperature range and a wide pressure range by providing counter electrodes and three couples of piezoelectric oscillators in an airtight container, connecting an oscillation circuit externally through an electric circuit formed of the counter electrodes and one of the piezoelectric oscillators, and deciding on the frequency of the oscillator. CONSTITUTION:The diaphragm 2 is provided on the top surface of the airtight container 1. The counter electrodes 2a are provided on the reverse surface of the diaphragm 2. The piezoelectric oscillators 3 are provided opposite the electrodes 2a, and oscillation parts 3a, 3b, and 3c are fitted thereto. Then, a pressure difference applied to the diaphragm 2 is converted electrically by the counter electrodes 2a and oscillation part 3a and connected to the external oscillation circuit 7. Then, the electric signal is led to the frequency decision circuit 6 including the oscillation parts 3b and 3c through a buffer 5 to detect variation in frequency and detect the pressure. Then, the plural oscillation parts are provided, so an error caused by variation of temperature charac teristics of a piezoelectric body is eliminated and the pressure is detected with high precision. |
