Measuring and testing – Speed – velocity – or acceleration – Acceleration determination utilizing inertial element
Patent
1995-11-30
1998-09-01
Williams, Hezron E.
Measuring and testing
Speed, velocity, or acceleration
Acceleration determination utilizing inertial element
G01P 1510
Patent
active
058013091
ABSTRACT:
A first embodiment of an improved microaccelerometer includes a seismic mass, a support wafer, a cover wafer and a beam (or beams) for flexibly mounting a seismic mass between the support and cover wafers. A first oscillator includes a resonant circuit whose capacitance comprises conductive plates on one surface of the seismic mass and a conductive coating on an opposed surface of the support wafer. A second oscillator includes a resonant circuit whose capacitance is comprised of conductive coatings on another surface of the seismic mass and on an opposed surface of the cover wafer. A difference circuit provides an acceleration output that is dependent on a difference in oscillation frequencies between the first and second oscillators, when the accelerometer is subjected to an acceleration event. A second embodiment includes a structure similar to the aforedescribed, however, the second oscillator is replaced by an ac levitation circuit that exerts a single direction restoring force on the seismic mass during an acceleration event. A third embodiment provides ac levitational restoring forces when the seismic mass is subject to acceleration in either of two opposed directions. In the latter embodiment, ac levitating circuits are disposed on opposed surfaces of the support and cover wafers.
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Carr William N.
Cho Dong-Il
Kwok Helen C.
New Jersey Institute of Technology
Princeton University
Williams Hezron E.
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