Piezoelectric Transducers and Inertial Sensors using Piezoelectric Transducers
First Claim
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1. A piezoelectric transducer comprising:
- a structure made of piezoelectric material, the structure including;
a set of substantially flat concentric frames having a common top surface and a common bottom surface and characterized by a direction of elongation, the top and the bottom surfaces being substantially parallel to a reference plane, andbridges connecting the frames, the bridges disposed symmetrically about a plane of symmetry of the structure so as to allow the frames to deform in the reference plane; and
a set of at least two top electrodes, disposed on the top surface of the frames, and a set of at least two corresponding bottom electrodes, disposed on the bottom surface of the frames, the sets of top and bottom electrodes being substantially equivalent and positioned opposite to each other, each of corresponding top and bottom electrodes disposed on at least two frames along a path that is symmetric about the plane of symmetry and crosses some of the bridges,wherein the transducer transduces energy, through piezoelectric effect, between electrostatic energy associated with voltage differential between the corresponding top and bottom electrodes and mechanical energy associated with deformation of the frames.
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Abstract
Transducers comprising a frame structure made of piezoelectric material convert energy, through piezoelectric effect, between electrostatic energy associated with voltage differential between the electrodes sandwiching the frame structure and mechanical energy associated with deformation of the frame structure. Inertial sensors such as gyroscopes and accelerators, including inertial sensors comprising ring resonators, utilize said transducers both to generate oscillations of their resonators and to sense the changes in such oscillations produced, in the sensors'"'"' frame of reference, by Coriolis forces appearing due to the movement of the sensors.
42 Citations
36 Claims
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1. A piezoelectric transducer comprising:
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a structure made of piezoelectric material, the structure including; a set of substantially flat concentric frames having a common top surface and a common bottom surface and characterized by a direction of elongation, the top and the bottom surfaces being substantially parallel to a reference plane, and bridges connecting the frames, the bridges disposed symmetrically about a plane of symmetry of the structure so as to allow the frames to deform in the reference plane; and a set of at least two top electrodes, disposed on the top surface of the frames, and a set of at least two corresponding bottom electrodes, disposed on the bottom surface of the frames, the sets of top and bottom electrodes being substantially equivalent and positioned opposite to each other, each of corresponding top and bottom electrodes disposed on at least two frames along a path that is symmetric about the plane of symmetry and crosses some of the bridges, wherein the transducer transduces energy, through piezoelectric effect, between electrostatic energy associated with voltage differential between the corresponding top and bottom electrodes and mechanical energy associated with deformation of the frames. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A motion sensor comprising a body defining a local reference system, the body including:
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a piezoelectric transducer including; a set of substantially flat concentric frames having a common top surface and a common bottom surface and characterized by a direction of elongation, the top and the bottom surfaces being substantially parallel to a reference plane; bridges connecting the frames, the bridges disposed symmetrically about a plane of symmetry of the transducer so as to allow the frames to deform in the reference plane, the bridges and the frames made of piezoelectric material; and a set of at least two top electrodes, disposed on the top surface of the frames, and a set of at least two corresponding bottom electrodes, disposed on the bottom surface of the frames, the sets of top and bottom electrodes being substantially equivalent and positioned opposite to each other, each of corresponding top and bottom electrodes disposed on at least two frames along a path that is symmetric about the plane of symmetry and crosses some of the bridges, wherein the transducer transduces energy, through piezoelectric effect, between electrostatic energy associated with voltage differential between the corresponding top and bottom electrodes and mechanical energy associated with deformation of the frames; and a resonator coupled to the piezoelectric transducer, the resonator characterized by a motion that lies substantially in the reference plane. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method of sensing a movement of an inertial sensor having a body of piezoelectric material, the body characterized by substantially constant thickness defined by two planes and also having a set of top electrodes disposed on a top surface of the body and a corresponding set of bottom electrodes disposed on a bottom surface of the body, the sets of top and bottom electrodes being opposite to one another, the sets of top and bottom electrodes characterized by a pattern, the body defining a local reference system, the method comprising:
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applying alternating voltage differential between top driving electrodes from the top set and corresponding bottom driving electrodes from the bottom set so as to cause reciprocating motion, in the plane, of a portion of the body through piezoelectric effect, wherein such reciprocating motion changes, within the local reference system, upon the movement of the inertial sensor; and sensing, through piezoelectric effect, said changes to the reciprocating motion based on a voltage differential arising between top sensing electrodes from the top set and corresponding bottom sensing electrodes from the bottom set. - View Dependent Claims (28, 29, 30)
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31. A method for modifying an oscillation of a resonator in an inertial sensor, the inertial sensor comprising driving piezoelectric transducers for enabling an oscillation of the resonator and sensing piezoelectric transducers for enabling a detection of a movement of the inertial sensor, the method comprising:
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disposing piezoelectric compensating elements substantially equidistantly among the driving and the sensing piezoelectric transducers, the compensating elements and the resonator forming corresponding capacitors having capacitive gaps; during the oscillation of the resonator, measuring, with the compensating elements, changes in electrostatic charges stored in the capacitors, the changes in charges associated with changes in the capacitive gaps due to the oscillation of the resonator; and modifying the electrostatic charges stored in the capacitors so as to modify the oscillation of the resonator. - View Dependent Claims (32, 33, 34, 35, 36)
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Specification