| 摘要 |
PURPOSE: To add a self-diagnosis function to an accelerometer for measuring the dynamic changes of acceleration such as vibration, impact, etc. CONSTITUTION: A pendulum 1 is formed out of silicon single crystal substrate and is provided with a frame part 2, weight part 3 and beam part 4. An upper stopper 8 and lower stopper 9 are prepared on the upper and lower sides of the pendurum 1 respectively so as to limit the displacement of the part 3. A plurality of piezo resistance elements are formed on the upper face of the part 4, and a bridge circuit is made by connecting them. When a CD voltage is applied to one of opposite corners of the bridge circuit, a voltage generating in the other opposite corners is detected by a detection circuit 22. First and second self test electrodes 8a and 9a are formed on the inner faces of both stoppers respectively. In a self test, a first test voltage, V2 =±Vo+Vosinωt, and second test voltage, V2 =±Vo-Vosinωt are applied, and a ground potential is given to one joint point for supplying power source in the bridge circuit, while a negative DC voltage±E is given to the other joint point thereof, then a bridge output at the time is detected.
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