Accelerometer without proof mass
AssigneeSimon Fraser University
InventorAlbert M. Leung
Life of this patent
Estimating the term…
Abstract
An accelerometer having a substrate with a cavity therein, a heater extending over the cavity, a pair of temperature sensitive elements extending over the cavity equidistant from the heater, and an electrical conductor couplable to an external power source and operative to pass electrical current through the heater so as to develop a symmetrical temperature gradient in the fluid extending outwardly from the heater to the two temperature sensors. The fluid may be a liquid or a gas surrounding the heater and temperature sensors. Applied acceleration disturbs this symmetry and produces a differential temperature between the two temperature sensors proportional to the acceleration.
Claims26
An accelerometer, comprising:
- (a) a substrate having an open space therein;
- (b) a heater extending across said open space;
- (c) a pair of temperature sensitive elements extending across said open space, said temperature sensitive elements being located on opposite sides of said heater;
- and
- (d) an enclosure extending over said open space including said heater and said temperature sensitive elements and enclosing a non-solid heat transfer medium surrounding said heater and said temperature sensitive elements;
- wherein said open space, said heater and said temperature sensitive elements are formed by micromachining.
An accelerometer, comprising:
- a substrate having an open space therein;
- a primary heater extending across said open space;
- a pair of temperature sensitive elements extending across said open space, substantially parallel to and equidistant from said primary heater, one of said pair being located on each side of said primary heater;
- an enclosure extending over said open space, said primary heater, said temperature sensitive elements and a non-solid heat transfer medium surrounding said primary heater and said temperature sensitive elements;
- a conductor connectable to an external source of power and operative to conduct current through said primary heater so as to develop a symmetrical temperature gradient in an air surrounding said primary heater in which air temperature lowers in a direction away from said primary heater;
- and
- a bridge circuit operative to measure the differential resistance of said temperature sensitive elements and relating that to acceleration in a direction transverse to said temperature sensitive elements and along a surface of said substrate;
- and
- wherein said accelerometer is made by micromachining.
An accelerometer, comprising:
- (a) a substrate having an open space therein;
- (b) a heater extending across said open space;
- (c) a first temperature sensitive element extending over said open space and spaced apart from said heater;
- (d) a second temperature sensitive element positioned to sense a temperature signal which when subtracted from a temperature signal of said first temperature sensitive element produces a differential signal proportional to acceleration;
- and
- (e) an enclosure extending over said open space including said heater and said first temperature sensitive element and enclosing a non-solid heat transfer medium surrounding said heater and said first temperature sensitive elements;
- wherein said open space, said heater and said first temperature sensitive element are formed by micromachining.
Dependencies are inferred from the claim text.