Integrated force balanced accelerometer
First Claim
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1. An integrated, force balanced accelerometer, comprising:
- capacitance forming means having substantially parallel electrodes;
acceleration sensitive means flexibly mounted between said parallel electrodes in a neutral position;
said acceleration sensitive means formed within a substrate of semiconductor material by forming an opening therein that defines the periphery of said acceleration sensitive means in said substrate to define an inertial mass attached to said substrate by hinge means;
said hinge means, include crossed beam flexure blades formed within said semiconductor substrate;
means for applying a D.C. electrical potential across said parallel electrodes of said capacitance forming means to establish a bias field;
a means for generating A.C. electrical potentials between said acceleration sensitive means and said parallel electrodes, which potential change as said acceleration sensitive means undergoes a displacement from said neutral position; and
electronic means connected between said parallel electrodes of said capacitance forming means and said acceleration sensitive means to close an electrical servo loop therebetween, wherein motion of said acceleration sensitive means causes an output from said electronic means to return said acceleration sensitive means to said neutral position and represent the acceleration of said accelerometer.
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Abstract
An accelerometer fabricated from a semiconductor substrate sandwiched between two non-conductive plates is shown having an inertial mass formed by etching the substrate. The mass is joined to the substrate by hinges having crossed blades to provide flexure in one direction and rigidity in other directions. The fabrication technique permits the integration of accelerometer servo and signal processing circuitry upon the same substrate in which the accelerometer mass is formed.
151 Citations
13 Claims
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1. An integrated, force balanced accelerometer, comprising:
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capacitance forming means having substantially parallel electrodes; acceleration sensitive means flexibly mounted between said parallel electrodes in a neutral position; said acceleration sensitive means formed within a substrate of semiconductor material by forming an opening therein that defines the periphery of said acceleration sensitive means in said substrate to define an inertial mass attached to said substrate by hinge means; said hinge means, include crossed beam flexure blades formed within said semiconductor substrate; means for applying a D.C. electrical potential across said parallel electrodes of said capacitance forming means to establish a bias field; a means for generating A.C. electrical potentials between said acceleration sensitive means and said parallel electrodes, which potential change as said acceleration sensitive means undergoes a displacement from said neutral position; and electronic means connected between said parallel electrodes of said capacitance forming means and said acceleration sensitive means to close an electrical servo loop therebetween, wherein motion of said acceleration sensitive means causes an output from said electronic means to return said acceleration sensitive means to said neutral position and represent the acceleration of said accelerometer. - View Dependent Claims (2, 3, 4, 5)
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6. An accelerometer comprising:
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a first planar substrate of semiconductor material having an opening therein that defines the periphery of an acceleration sensitive mass; said acceleration sensitive mass connected to said semiconductor substrate by a plurality of crossed beam flexure blades formed within said substrate; second and third planar substrates mounted on opposite sides of said first planar substrate each having a conductive surface adjacent said acceleration sensitive mass; means for applying an electrical potential between said acceleration sensitive mass and said conductive surfaces on said second and third substrates. - View Dependent Claims (7, 8, 9, 10, 11)
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12. In an accelerometer having a planar inertial mass formed in a plane of semiconductor material and at least one capacitance forming electrode parallel thereto, wherein the improvement comprises:
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said inertial mass formed by an opening within said semiconductor plane that defines the periphery of said inertial mass; and hinge means joining said semiconductor plane to said inertial mass including a plurality of crossed beam flexure blades formed in said semiconductor material. - View Dependent Claims (13)
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Specification