| 摘要 |
PURPOSE:To always stably detect a driving operation with high accuracy while detection sensitivity does not depend on a temperature by applying a temperature-compensation driving voltage to a piezoelectric vibrator with a temperature-compensation circuit. CONSTITUTION:A temperature-compensation circuit 18 temperature-compensates a driving voltage from a phase shift circuit 12, it generates a temperature- compensation driving voltage, and it applies the temperature-compensation driving voltage to a piezoelectric vibrator. The temperature-compensation driving voltage which is generated by the circuit 18 is obtained in such a way that the driving voltage is temperature-compensated according to a variable portion due to a temperature change in a detection voltage. In this case, the mechanical sharpness of the piezoelectric vibrator is changed accompanying the temperature change. Even when the detection voltage which is output from the piezoelectric vibrator is made variable by the temperature change, the temperature- compensation driving voltage which is generated by compensating the variable portion by using the circuit 18 is applied to the piezoelectric vibrator. Consequently, the detection voltage which is obtained from the piezoelectric vibrator can be kept always definite. |
