Reducing offset in accelerometers
First Claim
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1. An accelerometer comprising:
- a substrate;
a mass having an outer periphery, a cavity defining an inner periphery, and a plurality of elongated fingers along a portion of the inner periphery;
mass support structures, positioned within the inner periphery and affixed to the substrate by at least one anchor positioned proximate to the mass'"'"' center of mass, for supporting the mass above the substrate and allowing movement of the mass relative to the substrate along at least one linear axis, and a plurality of elongated sensing fingers for sensing movement of the mass fingers relative to the sensing fingers, the sensing fingers positioned substantially alongside the mass fingers within the inner periphery and affixed to the substrate proximate to the at least one anchor such that mechanical stresses cause the mass fingers and the sensing fingers to move in substantially equal ways.
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Abstract
Accelerometer offset is reduced by forming mass support structures within an inner periphery of the mass, affixing the mass support structures to the substrate by at least one anchor positioned near the mass'"'"' center of mass, and affixing the sensing fingers proximate to the anchor. The mass support structures can be affixed to the substrate using a single anchor or multiple anchors that are positioned close together. The sensing fingers can be affixed to the substrate or to the mass support structures. The mass is typically suspended from within its periphery but toward its outer periphery.
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Citations
16 Claims
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1. An accelerometer comprising:
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a substrate;
a mass having an outer periphery, a cavity defining an inner periphery, and a plurality of elongated fingers along a portion of the inner periphery;
mass support structures, positioned within the inner periphery and affixed to the substrate by at least one anchor positioned proximate to the mass'"'"' center of mass, for supporting the mass above the substrate and allowing movement of the mass relative to the substrate along at least one linear axis, and a plurality of elongated sensing fingers for sensing movement of the mass fingers relative to the sensing fingers, the sensing fingers positioned substantially alongside the mass fingers within the inner periphery and affixed to the substrate proximate to the at least one anchor such that mechanical stresses cause the mass fingers and the sensing fingers to move in substantially equal ways. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for reducing offset in an accelerometer, the method comprising:
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forming a mass having an outer periphery, a cavity defining an inner periphery, and a plurality of elongated finger structures along a portion of the inner periphery;
forming a plurality of mass support structures within the inner periphery of the mass;
forming a plurality of elongated sensing fingers substantially alongside the mass fingers within the inner periphery of the mass for sensing movement of the mass fingers relative to the sensing fingers;
affixing the mass support structures to a substrate by at least one anchor positioned proximate to the mass'"'"' center of mass for supporting the mass above the substrate and allowing movement of the mass relative to the substrate along at least one linear axis; and
affixing the plurality of elongated sensing fingers to the substrate proximate to the at least one anchor such that mechanical stresses cause the mass fingers and the sensing fingers to move in substantially equal ways. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification