RESONANT SCANNING GEOPHONE Russian patent published in 2017 - IPC G01V1/16 

FIELD: physics.

SUBSTANCE: invention can be used to record mechanical oscillations, in particular high-frequency seismic noise (HFSN), by a resonant method in a wide frequency band. The proposed geophone comprises a body and an elastic element in the form of a metal plate. One end of the plate is clamped into the support installed in the body, and on the other, the inertial mass is reinforced in the form of a coil of a durable light material, for example, a carbon fibre reinforced plastic, with a wire wound from it of heavy material, for example, tungsten. The second coil is installed in the cody, configured to rewind the wire between the coils. The rotation on the coils is transmitted by servo drives from two reversible motor generators mounted in the body, connected to a common electrical circuit with the possibility of coordinated switching them from the engine mode to the generator mode and back. Herewith when the first one is in the engine mode (rewinding mode from the second coil to the first coil), the second one is in the generator mode and vice versa. This prevents the wire from sagging when changing the direction of its rewinding. The rewinding of the wire between the coils leads to a change in the inertial mass and, as a consequence, to a change in the resonant frequency of the system. This provides the ability to scan the operating frequency band. The choice of coil and wire materials from light and heavy materials, respectively, is due to the need to expand the change range of the inertial mass and, thus, to expand the scanned bandwidth. Near the support on the elastic plate, there is a flat sensing element in the form of a bimorph piezoelectric transducer of the rectangular shape. The output signal from the converter is fed to both the recorder and the input of the scanning device, enabling the control of the scanning speed. To ensure a linear dependence of the output signal of the converter on the amplitude of mechanical oscillations of the plate and to increase its long-term strength at the point of connection with the support, the elastic plate at the bimorph attachment point is made in the form of an isosceles trapezium, the larger base of which is clamped into the support. The geometric dimensions of the plate are chosen so that the relation (a+b)d=ac is satisfied, where a is the distance from the fastening point of the inertial mass to the smaller base of the trapezium d, b is the height of the trapezium, c is the greater base of the trapezium.

EFFECT: extending the band of recorded frequencies and the accuracy of their identification, ensuring the linearity of the amplitude of the output signal of the converter from the amplitudes of the recorded oscillations, increasing the accuracy of determining the amplitudes.

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