Vibration pickup device

Claim 2

A vibration pickup device to convert the velocity of the vibratory motion of a vibrating body to a corresponding output voltage, said device comprising a mounting base, a casing structure, said casing structure comprising an outer casing structure, which is secured to the mounting base, and an inner casing structure which is concentrically disposed within said outer casing structure and is in spaced relation therewith, a permanent magnet housed in said inner casing structure and effective to create a steady magnetic field, a coil structure, means for sEismically mounting said coil structure in spaced relation with said inner casing structure and in linking relation with said magnetic field, an outer bucking coil secured to said casing structure, an inner bucking coil secured to said casing structure, said bucking coils being in bucking relation with said coil structure and are disposed such that voltage induced in one bucking coil leads the voltage induced in the coil structure and the voltage induced in the other bucking coil lags the voltage induced in the coil structure, said bucking coils minimizing the effect of stray electromagnetic fields on the output voltage of said device.

Claim 3

The device according to claim 1 wherein the inner and outer bucking coils are secured to the inner casing structure.

Claim 4

The device according to claim 1 wherein the mounting means comprises a pair of axially spaced seismic mounting springs.

Claim 5

The device according to claim 1 wherein an alternating current voltage is produced in said coil structure as the steady magnetic field is cut by the coil structure, said voltage being directly proportional to the velocity of vibration of the vibrating body.

Claim 6

The device according to claim 3 wherein the coil structure and the outer and inner bucking coils are electrically connected, so that the error voltage induced in the coil structure by the stray electromagnetic fields also induces error voltage in the outer bucking coil and the inner bucking coil, so that when the error voltage in the bucking coils is subtracted from the total voltage in the coil structure, the voltage output from the coil structure substantially represents the voltage induced in the coil structure from the motion of the vibrating body.

Claim 7

The device described in claim 1 wherein one portion of said coil structure is a wound coil, said coil being electrically connected in series with the inner bucking coil and the outer bucking coil, and the number of turns in the bucking coils being adjusted so that the error voltage induced in said wound coil by stray fields is subtracted from the error voltage in said wound coil so that there is approximately no error voltage in the output of said wound coil.

Claim 8

In a vibration pickup device to convert the velocity of vibrations produced by a vibrating body to a proportional alternating voltage, said device comprising a mounting base, an outer casing secured to said base, an inner casing structure, said inner casing structure being electrically insulated from said base and said outer casing structure, said inner casing structure being magnetically shielded from said base and outer casing, a permanent magnet housed in said inner casing structure and effective to create a steady magnetic field, a pair of axially spaced seismic mounting springs secured on opposite ends of said inner casing structure, a coil structure suspended between said springs in spaced relation with said inner casing structure, said field magnetically linking said coil structure, an outer bucking coil secured to said inner casing structure, an inner bucking coil secured to said inner casing structure, said coil structure being electrically connected in series with said inner bucking coil and said outer bucking coil, one of said bucking coils being wound so that the voltage induced therein leads the voltage induced in said coil structure, the other of said bucking coils being wound so that voltage induced therein lags the voltage induced in said coil structure, and the number of turns in said bucking coils being adjusted so that the voltage induced in said bucking coils is subtracted from the voltage induced in said coil structure so that there is approximately no error voltage in the output of said coil structure.

Claim 9

In a vibration pickup device to convert the velocity of vibrations produced by a vibrating body to a proportional alternating voltage, said device comprising a mounting base, an outer casing secured to said base, an inner casing structure, said inner casing structure being electrically insulated from said base and said outer casing structure, said inner casing structure being magnetically shielded from said base and outer casing, a permanent magnet housed in said inner casing structure and effective to create a steady magnetic field, a pair of axially spaced seismic mounting springs secured on opposite ends of said inner casing structure, a coil structure suspended between said springs in spaced relation with said inner casing structure, said field magnetically linking said coil structure, an outer bucking coil secured to said inner casing structure, an inner bucking coil secured to said inner casing structure, said coil structure being electrically connected in series with said inner bucking coil and said outer bucking coil, one of said bucking coils being wound so that the voltage induced therein leads the voltage induced in said coil structure, the other of said bucking coils being wound so that voltage induced therein lags the voltage induced in said coil structure, and the number of turns in said bucking coils being adjusted so that the voltage induced in said bucking coils is subtracted from the voltage induced in said coil structure so that there is approximately no error voltage in the output of said coil structure.

Claim 10

The device according to claim 11 wherein there is an aperture in said mounting base, and a prod attachment secured to said coil structure, extending through said aperture.

Claim 11

A vibRation pickup device to convert the velocity of the vibratory motion of a vibrating body to a corresponding voltage, said device comprising a mounting base, a casing structure secured to said base, a permanent magnet housed in said structure and effective to create a steady magnetic field, a coil structure, means for seismically mounting said coil structure in spaced relation with said casing structure in linking relation with said magnetic field, an outer bucking coil secured to said casing structure, an inner bucking coil secured to said casing structure, said bucking coils being in bucking relation with said coil structure, said casing structure being comprised of an outer casing structure, which is secured to the mounting base, and an inner casing structure which is concentrically disposed within said outer casing structure, and said inner casing structure being electrically insulated from said outer casing structure.

Claim 12

A vibRation pickup device to convert the velocity of the vibratory motion of a vibrating body to a corresponding voltage, said device comprising a mounting base, a casing structure secured to said base, a permanent magnet housed in said structure and effective to create a steady magnetic field, a coil structure, means for seismically mounting said coil structure in spaced relation with said casing structure in linking relation with said magnetic field, an outer bucking coil secured to said casing structure, an inner bucking coil secured to said casing structure, said bucking coils being in bucking relation with said coil structure, said casing structure being comprised of an outer casing structure, which is secured to the mounting base, and an inner casing structure which is concentrically disposed within said outer casing structure, and said inner casing structure being electrically insulated from said outer casing structure.

Claim 13

A vibration pickup device to convert the velocity of the vibratory motion of a vibrating body to a corresponding voltage, said device comprising a mounting base, a casing structure secured to said base, a permanent magnet housed in said structure and effective to create a steady magnetic field, a coil structure, means for seismically mounting said coil structure in spaced relation with said casing structure in linking relation with said magnetic field, an outer bucking coil secured to said casing structure, an inner bucking coil secured to said casing structure, said bucking coils being in bucking relation with said coil structure, said casing structure being comprised of an outer casing structure, which is secured to the mounting base, and an inner casing structure which is concentrically disposed within said outer casing structure, one portion of said coil structure being a wound coil, said coil being electrically connected in series with the inner bucking coil and the outer bucking coil, one of the bucking coils being wound so that the error voltage induced in that coil by the stray electromagnetic field leads the error voltage induced in said wound coil, the other of said bucking coils being wound so that the error voltage induced in that bucking coil by the stray electromagnetic field lags the error voltage induced in said wound coil, the number of turns in the bucking coils being adjusted so that the error voltage introduced in said wound coil by the stray fields is subtracted from the error voltage in said wound coil so that there is approximately no error voltage in the output of said wound coil, said mounting means being electrically insulated from said inner casing structure, and the inner casing structure being electrically grounded.

Claim 14

A vibration pickup device to convert the velocity of the vibratory motion of a vibrating body to a corresponding voltage, said device comprising a mounting base, a casing structure secured to said base, a permanent magnet housed in said structure and effective to create a steady magnetic field, a coil structure, means for seismically mounting said coil structure in spaced relation with said casing structure in linking relation with said magnetic field, an outer bucking coil secured to said casing structure, an inner bucking coil secured to said casing structure, said bucking coils being in bucking relation with said coil structure, said casing structure being comprised of an outer casing structure, which is secured to the mounting base, and an inner casing structure which is concentrically disposed within said outer casing structure, one portion of said coil structure being a wound coil, said coil being electrically connected in series with the inner bucking coil and the outer bucking coil, one of the bucking coils being wound so that the error voltage induced in that coil by the stray electromagnetic field leads the error voltage induced in said wound coil, the other of said bucking coils being wound so that the error voltage induced in that bucking coil by the stray electromagnetic field lags the error voltage induced in said wound coil, the number of turns in the bucking coils being adjusted so that the error voltage introduced in said wound coil by the stray fields is subtracted from the error voltage in said wound coil so that there is approximately no error voltage in the output of said wound coil, said mounting means being electrically insulated from said inner casing structure, and the inner casing structure being electrically grounded.

Claim 15

A vibration pickup device to convert the velocity of the vibratory motion of a vibrating body to a corresponding voltage, said device comprising a mounting base, a casing structure secured to said base, a permanent magnet housed in said structure and effective to create a steady magnetic field, a coil structure, means for seismically mounting said coil structure in spaced relation with said casing structure in linking relation with said magnetic field, an outer bucking coil secured to said casing structure, an inner bucking coil secured to said casing structure, said bucking coils being in bucking relation with said coil structure, said casing structure being comprised of an outer casing structure, which is secured to the mounting base, and an inner casing structure which is concentrically disposed within said outer casing structure, and said inner casing structure is magnetically shielded from the base by a magnetic shield plate and the outer casing functions as a magnetic shield.

Claim 16

A vibration pickup device to convert the velocity of the vibratory motion of a vibrating body to a corresponding voltage, said device comprising a mounting base, a casing structure secured to said base, a permanent magnet housed in said structure and effective to create a steady magnetic field, a coil structure, means for seismically mounting said coil structure in spaced relation with said casing structure in linking relation with said magnetic field, an outer bucking coil secured to said casing structure, an inner bucking coil secured to said casing structure, said bucking coils being in bucking relation with said coil structure, said casing structure being comprised of an outer casing structure, which is secured to the mounting base, and an inner casing structure which is concentrically disposed within said outer casing structure, and said inner casing structure is magnetically shielded from the base by a magnetic shield plate and the outer casing functions as a magnetic shield.