Angular accelerometer having balanced inertia mass
First Claim
1. An angular accelerometer comprising:
- a substrate;
a fixed electrode supported on the substrate and including a first plurality of fixed capacitive plates;
a rotational inertia mass suspended over a cavity and including a central opening and a plurality of movable capacitive plates arranged to provide a capacitive coupling with said first plurality of fixed capacitive plates;
a central member fixed to said substrate and located substantially in the central opening of said rotational inertia mass;
a channel formed in said rotational inertia mass;
a signal line extending within the channel formed in the rotational inertia mass;
a plurality of support arms extending between the central member and the rotational inertia mass for supporting the rotational inertia mass relative to the fixed electrode and allowing rotational movement of the rotational inertia mass upon experiencing an angular acceleration about a sensing axis; and
one or more openings formed in the rotational inertia mass so as to balance the rotational inertia mass to compensate for the channel and provide a center of mass substantially centered about the rotational inertia mass.
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Accused Products
Abstract
A balanced angular accelerometer is provided having a substrate, a fixed electrode with a plurality of fixed capacitive plates, and a rotational inertia mass with a central opening and substantially suspended over a cavity and including a plurality of movable capacitive plates arranged to provide a capacitive coupling with the first plurality of fixed capacitive plates. The accelerometer has a central member and an outer member fixed to the substrate. According to one embodiment, a plurality of inner support arms extend between the central member and the inertia mass and a plurality of outer support arms extend between the inertia mass and the outer member to support the mass over the cavity. According to another embodiment, one or more cut out apertures are formed in the inertia mass to compensate for a channel and signal line so as to balance the inertia mass about the center of the inertia mass.
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Citations
28 Claims
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1. An angular accelerometer comprising:
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a substrate;
a fixed electrode supported on the substrate and including a first plurality of fixed capacitive plates;
a rotational inertia mass suspended over a cavity and including a central opening and a plurality of movable capacitive plates arranged to provide a capacitive coupling with said first plurality of fixed capacitive plates;
a central member fixed to said substrate and located substantially in the central opening of said rotational inertia mass;
a channel formed in said rotational inertia mass;
a signal line extending within the channel formed in the rotational inertia mass;
a plurality of support arms extending between the central member and the rotational inertia mass for supporting the rotational inertia mass relative to the fixed electrode and allowing rotational movement of the rotational inertia mass upon experiencing an angular acceleration about a sensing axis; and
one or more openings formed in the rotational inertia mass so as to balance the rotational inertia mass to compensate for the channel and provide a center of mass substantially centered about the rotational inertia mass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An angular accelerometer comprising:
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a substrate;
a first bank of variable capacitors formed of a first plurality of fixed capacitive plates and a first plurality of movable capacitive plates;
a second bank of variable capacitors formed of a second plurality of fixed capacitive plates and a second plurality of movable capacitive plates;
a rotational inertia mass configured as a ring having a central opening and rotatable in response to angular acceleration, wherein the rotational inertia mass is electrically coupled to said first and second plurality of movable capacitive plates and arranged so that said first and second plurality of movable capacitive plates form capacitive couplings with said first and second plurality of fixed capacitive plates;
a central member fixed to said substrate and located substantially in the central opening of said rotational inertia mass;
a channel formed in said rotational inertia mass;
a signal line extending within the channel formed in the rotational inertia mass;
a plurality of support arms extending between the central member and the rotational inertia mass for supporting the rotational inertia mass relative to the fixed electrode and allowing rotational movement of the rotational inertia mass upon experiencing an angular acceleration about a sensing axis; and
one or more openings formed in the rotational inertia mass so as to balance the rotational inertia mass to compensate for the channel and provide a center of mass substantially centered about the rotational inertia mass. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A micromachined angular accelerometer comprising:
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a substrate;
a fixed electrode supported on the substrate and including a first plurality of fixed capacitive plates;
a rotational ring having a central opening and including a plurality of movable capacitive plates at the outer perimeter and arranged to provide a capacitive coupling with the first plurality of fixed capacitive plates, said rotational ring being suspended over a cavity and rotationally movable relative to said fixed electrode;
a central member fixed to said substrate and located substantially in the center of central opening of said rotational ring;
a channel formed in said rotational ring;
a signal line extending within the channel formed in the rotational ring;
a plurality of support arms extending between the central member and the rotational ring for supporting the rotational ring relative to the fixed electrode and allowing rotational movement of the rotational ring upon experiencing an angular acceleration about a sensing axis;
one or more etched openings formed in the rotational ring so as to balance the rotational ring to compensate for the channel and provide a center of mass substantially centered about the rotational ring;
an input electrically coupled to one of the fixed electrodes and the rotational ring for receiving an input signal; and
an output electrically coupled to the other of the fixed electrode and the rotational ring for providing an output signal which varies as a function of change of the capacitive coupling and is indicative of angular acceleration. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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Specification