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Vibratory angular rate sensing system

  • US RE33,479 E
  • Filed: 01/22/1988
  • Issued: 12/11/1990
  • Est. Priority Date: 01/23/1984
  • Status: Expired due to Term
First Claim
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1. A vibratory angular rate sensing system comprising:

  • (a) a wafer of crystalline quartz having piezoelectric properties and forming a .[.substantially rectangular.]. mounting .[.frame and having a substantially rectangular central opening.].;

    (b) a .Iadd.fork having a .Iaddend.pair of tines extending at a predetermined acute angle .[.within said opening.]. .Iadd.from an origin and having an axis of symmetry.Iaddend.;

    (c) .Iadd.and .Iaddend.a base interconnecting said tines near their origin;

    (d) .[.a first and a second suspension bridge, each being secured at its ends to.]. .Iadd.bridge means supporting said fork on .Iaddend.said mounting .[.frame.].;

    (e) a .[.pivot.]. .Iadd.torsion member .Iaddend.extending .[.between.]. .Iadd.along .Iaddend.the axis of symmetry of said .[.tines.]. .Iadd.fork .Iaddend.and through said base.[., said pivot.]. .Iadd.and .Iaddend.being secured .[.near both ends by said suspension bridges.]. .Iadd.to said bridge means for forming bridges.Iaddend.;

    (f) a reaction mass secured to said .[.pivot at its end extending beyond the wide opening of said tines.]. .Iadd.torsion member.Iaddend.;

    (g) a pair of masses, each being secured to the free end of one of said tines, said tines having large fundamental and small harmonic thrust components, .[.and.]. said pair of masses being each disposed with the center of mass offset from the axis of the associated tine.[.,.]. whereby the centers of each mass move in arcs having substantially no thrust component;

    (h) means .[.including a first pair of electrodes secured to said tines.]. for driving said .Iadd.fork to cause said .Iaddend.tines .Iadd.to vibrate .Iaddend.substantially at their resonant frequency .[.determined by said pair of masses, said tines and said base.].; and

    (i) .[.a second pair of electrodes secured.]. .Iadd.means coupled .Iaddend.to said .[.pivot.]. .Iadd.torsion member .Iaddend.for picking up an output signal representative of torsion which produces a shear strain resulting in an amplitude variation of .[.the.]. .Iadd.an .Iaddend.electric field.

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