JPS5594139A - Gravimeter - Google Patents

Abstract

PURPOSE: To provide a gravimeter which does not separately require a thermometer by providing a vibrator and drive units for vibrating the vibrator simultaneously or in time division manner and obtaining signals corresponding to the density and temperature from natural vibration frequencies at respective vibration modes.

CONSTITUTION: This gravimeter comprises a tuning fork-type vibrator 1 supported at its both ends, vibration detecting piezo-electric elements 2, 3 for detecting the vibration of the thin portion 101 of the vibrator 1, and drive piezo-electric elements 4, 5 facing oppositely with the elements 2, 3, respectively. The outputs from the elements 2, 3 are applied to charge amplifiers 6, 7, respectively, and multiplied by constant value at coefficient circuits 8, 9, respectively. The outputs from the circuits 8, 9 are processed by an adder 10 and a subtractor 11. The outputs from the adder 10 and the substractor 11 are applied through low pass filters 12, 13 for passing a signal having less than quadratic vibration mode frequency and amplifiers 14, 15 for producing voltage signals having constant amplitude. The outputs from the amplifiers 14, 15 are added by an adder 16. The sum from the adder 16 is applied to the element 4. On the other hand, the outputs from the amplifiers 14, 15 are substated by a substractor 17. The output from the subtractor 17 is applied to the element 5. The output signals Ve, Vf from the amplifiers 14, 15, respectively are also applied to arithmetic circuits 18, 19, respectively. Then, the outputs from the circuits 18, 19 are applied to an arithmetic circuit 20, which thereupon produces a signal output correspond ing to the specific weight. This gravimeter has a simple configuration since it does not require separately a thermometer.

COPYRIGHT: (C)1980,JPO&Japio