Accelerometer

An accelerometer comprising:

• a) a substantially planar substrate having at least two aperture frames disposed therein,
• b) one or more static electrodes plates extending into and over each aperture frame from the edge thereof,
• c) at least one dynamic electrode plate disposed below said one or more static electrode plates associated with each aperture frame, wherein at least one capacitive sensing circuit is defined by the electrical communication between said one or more static electrode plate and said dynamic electrode plates, each dynamic electrode plate comprising:
• i) at least one torsion beam portion that spans the aperture frame to suspend each dynamic electrode plate below said one or more static electrode plates associated with the aperture frame, each torsion beam portion being parallel and disposed in the common plane parallel with the plane of said substrate,
• ii) a proof mass having at least a portion below the upper plane of the substrate and coupled to the at least one dynamic electrode plate,
• iii) each proof mass being laterally offset from the axis of the associated torsion beam portion in the opposite directions from the at least one dynamic electrode plate associated with the other aperture to cancel their respective capacitive charges induced by acceleration in the plane of the substrate and to add the capacitive charges induced by acceleration orthogonal to the plane of the substrate.

A three dimensional accelerometer comprising:

• a) a single support substrate,
• b) three or more apertures defined in said support substrate, wherein said apertures are disposed in a linear array, each aperture being associated with:
• i) one or more static electrodes plates extending into and over said aperture frame from the edge thereof,
• ii) at least one dynamic electrode plate disposed to form capacitive circuit with respect to said one or more static electrodes plates,
• iii) at least one proof mass coupled to and disposed below said dynamic electrode plate such that the COG (center of gravity) is below the plane of the dynamic electrode,
• iv) a least one torsion beam extending from and spanning the aperture to support said one or more dynamic electrode plates,
• v) wherein the acceleration or deceleration of said proof mass rotates said torsion beam one and said at least one more dynamic electrode plate whereby the capacitance of the circuit changes,
• c) wherein the first at least one proof mass associated with the first aperture is suspended from the support structure to permit movement and measure acceleration from the capacitive circuit when the proof mass moves in a first direction in the plane of the substrate,
• d) wherein the second at least one proof mass associated with the second aperture is suspended from the support structure to permit movement and measure acceleration from the capacitive circuit when the proof mass moves in a second direction in the plane of the substrate, the second direction being orthogonal to the first direction,
• e) wherein the third at least one proof mass associated with the third aperture is suspended from the support structure to permit movement and measure acceleration from the capacitive circuit when the proof mass rotates about an axis in the plane of the substrate.

An accelerometer device comprising;

• a) a substantially planar substrate having an aperture frame therein,
• b) one or more static electrodes plates extending into and over said aperture frame from the edge thereof,
• c) at least one dynamic electrode plate disposed to form capacitive circuit with respect to said one or more static electrodes plates,
• d) a proof mass coupled to and disposed below said dynamic electrode plate such that the COG (center of gravity) is below the plane of the dynamic electrode,
• e) at least one torsion beam extending from and spanning the aperture to support said one or more dynamic electrode plates,
• f) wherein the acceleration of said proof mass rotates said torsion beam and said at least one or more dynamic electrode plate whereby the capacitance of the circuit changes, wherein the at least one dynamic electrode plate is disposed below the static electrode plates to have a fixed gap when the torsion beam is in a neutral position and a gap that varies with distance from said torsion beam when said torsion beam rotates, and wherein the proof mass further comprises a second portion laterally offset from the torsion beam axis, the second portion being disposed in substantially the same plane as the static electrode plates.

An accelerometer device comprising;

• a) a substantially planar substrate having an aperture frame therein,
• b) one or more static electrodes plates extending into and over said aperture frame from the edge thereof,
• c) at least one dynamic electrode plate disposed to form capacitive circuit with respect to said one or more static electrodes plates,
• d) a proof mass coupled to and disposed below said dynamic electrode plate such that the COG (center of gravity) is below the plane of the dynamic electrode,
• e) at least one torsion beam extending from and spanning the aperture to support said one or more dynamic electrode plates,
• f) wherein the acceleration of said proof mass rotates said torsion beam and said at least one or more dynamic electrode plate whereby the capacitance of the circuit changes, wherein the at least one dynamic electrode plate is disposed below the static electrode plates to have a fixed gap when the torsion beam is in a neutral position and a gap that varies with distance from said torsion beam when said torsion beam rotates, wherein the torsion beam is connected to the dynamic electrode plate by a layer of silicon oxide having substantially the same thickness as the gap between the static and dynamic electrode plates, and wherein the torsion beam is formed in silicon and has an trench etched therein down to the silicon oxide layer to electrically isolate the dynamic electrode into two portions.

An accelerometer device comprising;

• a) a substantially planar substrate having an aperture frame therein,
• b) one or more static electrodes plates extending into and over said aperture frame from the edge thereof,
• c) at least one dynamic electrode plate disposed to form capacitive circuit with respect to said one or more static electrodes plates,
• d) a proof mass coupled to and disposed below said dynamic electrode plate such that the COG (center of gravity) is below the plane of the dynamic electrode,
• e) at least one torsion beam extending from and spanning the aperture to support said one or more dynamic electrode plates,
• f) wherein the acceleration of said proof mass rotates said torsion beam and said at least one or more dynamic electrode plate whereby the capacitance of the circuit changes, wherein the at least one dynamic electrode plate is disposed below the static electrode plates to have a fixed gap when the torsion beam is in a neutral position and a gap that varies with distance from said torsion beam when said torsion beam rotates, and wherein a portion of at least one of the static and dynamic electrode has a pair of electrically isolated portions adjacent the torsion beam that does not participate in the capacitive circuit.