Micromachined gyroscope

• US 20030172753A1
• Filed: 02/06/2003
• Published: 09/18/2003
• Est. Priority Date: 02/06/2002
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Geen, John A.
• Granted Patent: US 6,877,374 B2
• Time in Patent Office: Days
• US Class Current: 74/5R
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: Y10T 74/12 Gyroscopes

Abstract

A micromachined gyroscope makes use of Coriolis acceleration to-detect and measure rotation rate about a plane normal to the surface of a substrate. Specifically, various resonating structures are suspended within a frame. The resonating structures include phase and anti-phase masses that are mechanically coupled in order to produce a single resonance frequency for the entire resonating system. Rotation of the micromachined gyroscope about the plane produces a rotational force on the frame. The frame is suspended in such a way that its motion is severely restricted in all but the rotational direction. Sensors on all sides of the frame detect the rotational deflection of the frame for measuring the change in direction.

Claims

1. A micromachined gyroscope apparatus comprising:

a frame surrounded on substantially all sides by a plurality of fingers;

a plurality of coriolis detectors positioned between the fingers;

a plurality of accelerometer suspension flexures coupled to the frame for suspending the frame from a substrate, the accelerometer suspension flexures designed so as to restrict translational movement of the frame in the plane of the substrate and to allow rotational movement of the frame in the plane of the substrate; and

a plurality of resonating structures suspended within the frame, the resonating structures mechanically coupled to produce a single resonance frequency and to restrict transfer of inertial forces from the resonating structures to the frame, wherein rotational movement of the micromachined gyroscope structure in the plane of the substrate causes rotation of the frame relative to the substrate in the plane of the substrate and corresponding movement of the fingers relative to the coriolis detectors.

2. The apparatus of claim 1, wherein the resonating structures comprise:

a plurality of levers used to transform the coupled motion of the resonating structures from co-linear motion to parallel motion.

3. The apparatus of claim 2, wherein the levers have pivots defined at the points of attachment to ensure that the attachment point cannot translate with respect to the lever.

4. The apparatus of claim 1, wherein the resonating structures comprise:

a pair of phase masses coupled through a first flexure; and

a pair of antiphase masses coupled through a second flexure.

5. The apparatus of claim 2, wherein the resonating structures comprise:

drive or sensing fingers incorporated into the plurality of levers.

6. The apparatus of claim 4, wherein each mass comprises at least one notch for electronic quadrature suppression.

7. The apparatus of claim 1, wherein the resonating structures comprise:

arrays of fixed drive fingers arranged to be co-linear in the lateral direction, wherein the anchors are laid down in pairs joined to each other at the top ends remote from a substrate so that the tops resist individual twisting at the substrate end, and wherein finger busbars are attached to the top ends by flexible, folded fingers.