Piezoresistive accelerometer
First Claim
1. An acceleration transducer comprising:
- a mounting substrate;
a central pedestal support portion coupled to said substrate;
an elastic semiconductor diaphragm portion coupled to and peripherally surrounding said central pedestal support portion and extending generally parallel to said substrate;
a mass ring portion coupled to and peripherally surrounding said diaphragm portion and spaced from said substrate, said mass ring portion being movable in response to acceleration to cause bending movement of said diaphragm portion; and
means coupled to said diaphragm portion for detecting strain induced in said diaphragm portion in response to bending movement of said diaphragm portion for providing an output signal representing acceleration.
1 Assignment
0 Petitions
Accused Products
Abstract
A piezoresistive acceleration sensing transducer is disclosed which enables low cost microcircuit construction of accelerometers. A silicon wafer is etched to form individual acceleration sensing elements each of which includes a mass ring suspended from a diaphragm and mounted to a center pedestal support portion. A plurality of piezoresistive strain gauges are located on the diaphragm about the periphery of the pedestal portion and are positioned to form a circuit for sensing strain produced in the diaphragm by movement of the mass ring in response to acceleration. A pair of temperature sensors are located in a zero-stress area of the diaphragm to compensate for temperature effects. In one embodiment, the gauges are coupled in a bridge circuit to provide a measure of acceleration in one axis only. In another embodiment, the mass ring is modified to locate its center of mass above the plane of the diaphragm so that the mass ring responds to acceleration in three axes. Selected outputs from the strain gauges are then used to provide a measurement of acceleration in each of the three axes.
-
Citations
18 Claims
-
1. An acceleration transducer comprising:
-
a mounting substrate; a central pedestal support portion coupled to said substrate; an elastic semiconductor diaphragm portion coupled to and peripherally surrounding said central pedestal support portion and extending generally parallel to said substrate; a mass ring portion coupled to and peripherally surrounding said diaphragm portion and spaced from said substrate, said mass ring portion being movable in response to acceleration to cause bending movement of said diaphragm portion; and means coupled to said diaphragm portion for detecting strain induced in said diaphragm portion in response to bending movement of said diaphragm portion for providing an output signal representing acceleration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. An acceleration transducer comprising:
-
a substrate having a planar surface; an acceleration-responsive semiconductor means formed from a single piece of semiconductor material and including a rectangular center pedestal support portion rigidly coupled to said substrate and having an elastic, planar diaphragm portion formed as a rectangular ring peripherally extending from said support portion generally parallel to the planar surface of said substrate, and further including a mass ring portion formed as a rectangular ring peripherally extending from said diaphragm portion and spaced from the planar surface of said substrate for movement in response to acceleration, said diaphragm portion having areas adjacent said support portion in which stress is induced in response to bending movement of said diaphragm and further having areas of zero-stress during bending movement; first, second, third and fourth piezoresistive means coupled on said diaphragm portion and located symmetrically about the periphery of said support portion with a radial separation of 90 degrees about the center of said support portion, each of said piezoresistive means being positioned to provide a measure of the strain produced in said diaphragm in response to bending movement caused by movement of said mass ring portion, said first, second, third and fourth piezoresistive means providing outputs representing acceleration; and fifth and sixth piezoresistive means coupled on said diaphragm portion in a zero-stress region for providing an output representing temperature of said semiconductor means. - View Dependent Claims (16, 17, 18)
-
Specification