Spring for a resonance ring of an angular rate sensor
First Claim
1. A motion sensor comprising:
- a substrate;
a hub supported by the substrate;
spring members extending radially from the hub, the spring members being substantially S-shaped with substantially C-shaped first and second portions having different radii of curvature;
a sensing ring supported by the spring members above the substrate so that the sensing ring has an axis of rotation substantially through the hub;
means for inducing vibration in the sensing ring; and
means for sensing angular and radial deflections of the sensing ring.
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Accused Products
Abstract
A motion sensor having a sensing ring and electrodes formed on or in a surface region of a substrate, such as a silicon chip. The sensing ring is supported above the substrate by a number of spring members extending radially from a hub, so that the ring has an axis of rotation through the hub. The electrodes are formed to closely surround the ring, with some of the electrodes being adapted to induce vibration in the ring, while others detect angular and radial deflections of the ring. Finally, the spring members are substantially S-shaped with substantially C-shaped first and second portions having different radii of curvature. Configuring the spring members to have two portions of different radii of curvature substantially produces in the sensing ring the elliptical vibration mode shape of an ideal ring.
39 Citations
18 Claims
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1. A motion sensor comprising:
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a substrate; a hub supported by the substrate; spring members extending radially from the hub, the spring members being substantially S-shaped with substantially C-shaped first and second portions having different radii of curvature; a sensing ring supported by the spring members above the substrate so that the sensing ring has an axis of rotation substantially through the hub; means for inducing vibration in the sensing ring; and means for sensing angular and radial deflections of the sensing ring. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An angular rate sensor comprising:
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a substrate; a hub supported by the substrate; spring members extending radially from the hub, each of the spring members being substantially S-shaped with substantially C-shaped first and second portions having different radii of curvature; an electrically-conductive sensing ring supported above the substrate by the spring members so as to have an axis of rotation through the hub; means for inducing vibration in the sensing ring, the sensing ring having two identical vibration modes of elliptical shape when induced to vibrate by the inducing means; and means for sensing angular and radial deflections of the sensing ring. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A resonance ring gyroscope of an angular rate sensor, the resonance ring gyroscope comprising:
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a substrate; a hub on the substrate; an electrically-conductive sensing ring supported above the substrate and around the hub so as to have an axis of rotation through the hub; spring members extending radially from the hub and connected to the sensing ring for supporting the sensing ring above the substrate, each of the spring members being substantially S-shaped with a substantially C-shaped first portion adjacent the hub and a substantially C-shaped second portion adjacent the sensing ring, the radii of the first portions of the spring members being substantially the same and the radii of the second portions of the spring members being substantially the same, the radius of the first portion of each spring member larger than the radius of the corresponding second portion of the same spring member; tethers between the hub and the spring members and tethers between the spring members and the sensing ring, the tethers being oriented substantially radially relative to the hub; at least four pairs of diametrically-opposed electrode structures located equi-angularly around the sensing ring, each electrode structure comprising; a base member extending radially from the sensing ring, the base member having opposing sides; a first pair of teeth extending perpendicularly from a first side of the base member; a second pair of teeth extending perpendicularly from a second side of the base member opposite the first pair of teeth; a first pair of electrodes interdigitized with the first pair of teeth; and a second pair of electrodes interdigitized with the second pair of teeth; means for sensing capacitive forces between the first pair of electrodes and the first pair of teeth and between the second pair of electrodes and the second pair of teeth of at least two of the electrode structures; and means for applying a voltage to the first and second pair of electrodes of at least one of the electrode structures so as to induce vibration in the sensing ring near a resonant frequency of the sensing ring, the sensing ring having two identical modes of elliptical shape.
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Specification