Internally shock caged serpentine flexure for micro-machined accelerometer
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Accused Products
Abstract
An apparatus and method for sensing accelerations and other forces. The apparatus having a capacitance pick-off force sensor having a proof mass that is suspended relative to a relatively stationary frame by a plurality of serpentine suspension members having internal caging. The device provides easily implemented fabrication modification for trading-off between input range and pick-off sensitivity by altering etching periods of the serpentine suspension members. The input range and pick-off sensitivity can be traded-off by enlarging or reducing the quantity of elongated flexure fingers forming the serpentine suspension member. Different ones of the elongated flexure fingers are optionally formed with different thicknesses, whereby the serpentine suspension member exhibits a spring rate that progressively increases as it is compressed by in-plane motion of the proof mass relative to the relatively stationary frame.
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Citations
28 Claims
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1-8. -8. (canceled)
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9. A micro-machined electromechanical sensor (MEMS) device, comprising:
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a substantially planar proof mass suspended for in-plane motion from a relatively stationary frame by a first pair of spaced-apart resiliently flexible elongated flexure members interconnected at respective first ends with respective second ends interconnected to a first end of the proof mass and the frame and a second pair of the spaced-apart resiliently flexible elongated flexure members interconnected at respective first ends with respective second ends interconnected to a second end of the proof mass and the frame and having a promontory mass formed between the first pair of elongated flexure members; and
one or more comb-type capacitive pickoff sensors formed between the proof mass and the frame and structured for changing capacitance as a function of a movement of the proof mass relative to the frame. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A micro-machined electromechanical sensor (MEMS) device, comprising:
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a silicon substrate having substantially parallel and planar spaced-apart surfaces;
a proof mass formed in the substrate;
a frame formed in the substrate surrounding the proof mass;
a plurality of capacitive pickoff sensors formed between the proof mass and the frame and structured for changing capacitance as a function of an in-plane movement of the proof mass relative to the frame;
a plurality of serpentine flexures formed in balanced configuration between the proof mass and the frame and structured for enabling the in-plane movement of the proof mass relative to the frame; and
a promontory mass formed between the serpentine flexures.
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- 16. (canceled)
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21. A micro-machined electromechanical sensor (MEMS) device having a serpentine flexure, the device comprising:
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a relatively stationary frame formed in a substrate having substantially parallel and planar spaced-apart surfaces;
a moveable proof mass that is formed in the substrate; and
a serpentine flexure suspending the proof mass from the frame, the serpentine flexure comprising;
a plurality of elongated flexure members each formed in the substrate between the spaced-apart surfaces thereof, a relatively short interconnecting member arranged crosswise to the longitudinal axes of the elongated flexure members and interconnecting opposite ends of alternate pairs of the elongated flexure members in a serpentine configuration, and a small mass extending a part of a distance between adjacent elongated flexure members. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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Specification