| 摘要 |
PURPOSE:To detect the mechanical displacements stable against ambient temp. fluctuations as electric signals, amplify these signals with good stability and transmit the same to the outside. CONSTITUTION:The sensor parts 1 provided with the 1st and 2nd impedance element created between electrodes 11-12 and 12-13 are connected alternately to a variable frequency type oscillator 3 according to the switching periods of switches 21, and 22. In the 1st period, the signal of a frequency f1 corresponding to the capacity of the 1st impedance element is generated from the oscillator 3, and in the 2nd period, the signal of a frequency f2 corresponding to the capacity C2 of the 2nd impedance element is generated from the oscillator 3. In an arithmetic part 4, the duty cycle signal B associating to the frequencies f1, f2 is supplied to an extraction means 5'. In the means 5', the analog signal D of the value proportional to D= [(f1-f2)/(f1+f2)]<1/2> is outputted and the signal propotional to D is outputted from an output part 7. |
