MEMS GYROS WITH QUADRATURE REDUCING SPRINGS

• US 20140000367A1
• Filed: 08/23/2013
• Published: 01/02/2014
• Est. Priority Date: 10/25/2010
• Status: Active Grant

• Current Assignee: Rosemount Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rosemount Aerospace, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Potasek, David Patrick, Childress, Marcus Allen, Christenson, John Carl
• Granted Patent: US 9,541,394 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

Spring set configurations that include an advantageous combination of spring geometries are disclosed. Spring elements having curved and straight sections, orientation of spring element anchor points with respect to the common radius, orientation of spring element segments with respect to a specific axis, balance of the length of spring elements about the common radius, and mass balance about the common radius can be used to mitigate unwanted out of plane motion. The spring set provides planar motion while reducing undesired out of plane motion making MEMS devices substantially insensitive to the process-induced etch angle variations of the spring elements. The spring set can be used in a MEMS gyro device which maintains the desired resonant modes and consistently low quadrature error even with process variations in manufacturing causing undesirable etch angles.

Claims

1-25. -25. (canceled)

26. A spring set for a MEMS device comprising:

a) a plurality of springs connecting a first mass to a seconds mass, each spring having a spring element anchored to the first mass at a first anchor point and anchored to the second mass at a second anchor point, wherein the first and second anchor points of each spring element are located on a respective common vector that is oblique with respect to orthogonal axes defined by the first and second masses.

27. A spring set as recited in claim 26, further comprising one or more additional masses each attached to another one of the masses by a respective plurality of springs.

28. A spring set as recited in claim 26, wherein the plurality of springs are arranged with quarter symmetry.

29. A spring set as recited in claim 26, wherein each spring has a mass that is balanced about the respective common vector.

30. A spring set as recited in claim 26, wherein each spring has a length that is balanced about the respective common vector.

31. A spring set for a MEMS device comprising:

a plurality of springs connecting a first mass to a second mass, each spring having a spring element predominantly oriented parallel to a common axis.

32. A spring set as recited in claim 31, wherein each spring element is anchored to the first mass at a first anchor point and anchored to the second mass at a second anchor point, wherein the first and second anchor points of each spring element are located on a respective common vector that is oblique with respect to both the common axis and an orthogonal axis defined by the first and second masses.

33. A spring set for a MEMS device comprising:

a plurality of springs connecting a first mass to a second mass, the first mass defining a plane, each spring including a spring element with a cross-section having an etch angle that is oblique with respect to an axis orthogonal to the plane, wherein the springs impart a characteristic component of motion out of the plane to the second mass that is substantially insensitive to variation in the process induced etch angle of the spring elements.