REMOTELY OPERATED SEISMOMETER

• US 3,713,088 A
• Filed: 08/13/1970
• Issued: 01/23/1973
• Est. Priority Date: 08/13/1970
• Status: Expired due to Term

• Current Assignee: Francis E. Lehner, Wayne F. Miller
• Original Assignee: Francis E. Lehner, Wayne F. Miller
• Inventors: Lehner, Francis E., Miller, Wayne F.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Kinberg, R.
• Application Number:
  US05/063,512
• Time in Patent Office: 894 Days
• Field of Search: 340/17 73/1D,517B,518R,517R,382
• US Class Current: 367/182
• CPC Class Codes: G01V 1/181 Geophones

Abstract

A seismometer suitable for remote operation to measure quake components, comprising a boom mounted for pivoting about a nominally vertical or other axis, the boom carrying a sensing coil and a small iron slug. A pair of calibration coils mounted on opposite sides of the slug can be individually energized to deflect the boom in opposite directions from its static position. The sensing coil outputs resulting from separate energizations of the calibration coils, indicate the precise static position of the boom and therefore, in the case of a boom intended to pivot about a vertical axis, the angle of its nominally vertical axis of pivoting from a true vertical. The sensing coil is flat and is surrounded by a frame of non-conductive material with conductive layers on opposite sides that are electrically connected to the ends of the coil. The frame is supported by a pair of mass members which are insulated from each other but connected to the respective conductive layers on the frame. The mass members are mounted on separate Cardin hinges, and currents generated by the sensing coil are transmitted through the Cardin hinges to output terminals.

Claims

1. A seismometer comprising:

a main frame;

a boom;

means for mounting said boom on said frame to allow pivoting of said boom with respect to said frame about a nominally vertical axis while resiliently urging said boom toward a predetermined pivotal position;

means for sensing the amount of pivoting of said boom; and

first and second calibration means for urging said boom to pivot respectively in first and second opposite directions, irrespective of the position of the boom whereby to enable a measurement of the orientation of the axis of pivoting of said boom with respect to the vertical.

2. A seismometer comprising:

a main frame;

magnet means mounted on said frame;

a flat substantially spiral coil;

a coil frame of electrically insulative material extending about most of the periphery of said coil and supporting it;

a pair of mass members mounted at opposite faces of said coil frame, said mass members constructed of electrically conductive material, electrically insulated from each other, and electrically coupled to different portions of said coil;

a pair of hinges for pivotally coupling said mass members to said main frame so that said coil is positioned adjacent to said magnet means, said hinges constructed of electrically conductive material, electrically insulated from each other, and each electrically coupled to the mass member which it piVotally couples to said main frame; and

a pair of output terminal means coupled to said hinges.

3. The seismometer described in claim 2 wherein:

said coil frame has electrically conductive layers on its opposite faces that are directly connected to different portions of said coil; and

each of said mass members is connected to a different one of said conductive layers, whereby to facilitate construction of the seismometer.

4. A seismometer comprising:

a frame;

magnet means mounted on said frame;

a boom including a sensing coil and a portion of magnetically attractive material spaced from said coil;

means for pivotally mounting said boom on said frame so that said sensing coil is urged toward a predetermined pivotal position where it lies adjacent to said magnet means while said portion of magnetically attractive material is spaced from said magnet means;

first and second calibration coils mounted on opposite sides of said portion of magnetically attractive material for respectively urging said boom to pivot in opposite directions; and

sensing terminal means electrically coupled to said sensing coil.

5. The seismometer described in claim 4 wherein:

said sensing coil and said portion of magnetically attractive material are on diametrically opposite sides of the axis of pivoting of said boom.

6. A seismometer comprising:

a frame;

magnet means mounted on said frame; and

a boom including a coil adjacent to said magnet means, mass means for supporting said coil, and hinge means for pivotally supporting said mass means on said frame, said mass means including a pair of spaced web portions coupling the major portion of said mass means to said hinge means, each web portion having a width and length each at least twice as great as its thickness, said web portions oriented so that imaginary lines normal to their faces are substantially parallel to the axis of pivoting of said mass means on said frame, whereby to protect said hinge means.

7. A seismometer comprising:

a main frame;

a boom;

means for mounting said boom on said frame to allow pivoting of said boom with respect to said frame about a nominally vertical axis while resiliently urging said boom toward a predetermined pivotal position;

said boom having first and second portions on opposite sides of its axis of pivoting, and said second portion including magnetically attractive material;

means for sensing the amount of pivoting of said boom, including a sensing coil mounted on said first portion of said boom, and a magnet mounted on said frame adjacent to said coil to induce currents in it; and

first and second calibration coils mounted on opposite sides of said magnetically attractive material, for urging said boom to pivot in first and second opposite directions, respectively, whereby to isolate the magnetic field produced by said first and second calibration coils from said sensing coil.

8. The seismometer described in claim 7 wherein:

each of said calibration coils has a threadably mounted core of magnetically attractive material for screwing toward and away from said magnetically attractive material, whereby to enable adjustments to be made so that each calibration coil produces the same output from said sensing coil when the axis of pivoting of the boom is precisely vertical with respect to local gravity.

9. A seismometer comprising:

a main frame;

a boom assembly including a coil with first and second ends where electrical connections can be made;

a pair of hinges for pivotally mounting said boom on said frame, each hinge including a pair of crossed resilient members of electrically conductive material having opposite ends fixed to said boom and frame, respectively, said first and second ends of said coil electrically coupled to different ones of said hinges;

a pair of output terminal means mounted on said frame and electrically coupled to different ones of said hinges; and

magneT means mounted on said frame adjacent to said coil for creating a magnetic field in the vicinity of said coil;

said boom including first and second mass members of electrically conductive material electrically connected to different ones of said pair of hinges, said mass members electrically insulated from each other; and

said first and second ends of said coils being electrically coupled to said first and second mass members, respectively, so that each mass member electrically couples a coil end with a hinge.

10. The seismometer described in claim 9 wherein:

each of said mass members has a web region with a width and length each at least twice as great as its thickness, connecting a majority of the mass of the mass member to a hinge, each of said web regions oriented so that an imaginary line normal to the faces of the web region is substantially parallel to the axis of pivoting of said boom, whereby to reduce the possibility of damage to said hinge.