Piezoelectric Transducers and Inertial Sensors using Piezoelectric Transducers

A motion sensor comprising a body defining a local reference system, the body including:

• 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.

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:

• 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.