Structural design for improving the sensitivity of a surface-micromachined vibratory gyroscope

• US 6,293,148 B1
• Filed: 12/02/1999
• Issued: 09/25/2001
• Est. Priority Date: 04/30/1999
• Status: Expired due to Fees

• Current Assignee: Institute of Microelectronics
• Original Assignee: Institute of Microelectronics
• Inventors: Lim, Mong King, Lin, Rong Ming, Wang, Zhe, Sridhar, Uppili
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US09/453,112
• Time in Patent Office: 663 Days
• Field of Search: 73/504.12, 73/504.02, 73/504.14, 73/504.15, 73/504.16, 73/574.32
• US Class Current: 73/504.02
• 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: G01P 15/097 by vibratory elements

Abstract

The present invention is a motion sensor apparatus for use as a general mechanical amplifier, a gyroscope, or other resonant sensor such as an accelerometer. In accordance with the invention, the motion sensor apparatus includes a primary mass and a primary flexure structure. The primary flexure structure supports the primary mass to experience driven motion against a bias of the primary flexure structure. The apparatus further includes a secondary mass which is less massive than the primary mass. A secondary flexure structure interconnects the secondary mass with the primary mass, and supports the secondary mass to experience sensing motion relative to the primary mass against a bias of the secondary flexure structure. The stiffness ratio between the primary and secondary flexure structures is equal to the mass ratio between the primary and secondary masses.

Claims

1. A motion sensor apparatus comprising:

a primary mass;

a primary flexure structure supporting said primary mass to experience driven motion against a bias of said primary flexure structure;

a secondary mass which is less massive than said primary mass; and

a secondary flexure structure which interconnects said secondary mass with said primary mass and which supports said secondary mass to experience sensing motion relative to said primary mass against a bias of said secondary flexure structure;

a stiffness ratio between said primary and secondary flexure structures being equal to a mass ratio between said primary and secondary masses.

2. A motion sensor apparatus as defined in claim 1 wherein said primary and secondary masses and said primary and secondary flexure structures are configured such that said sensing motion of said secondary mass will be significantly greater than a primary motion of said primary mass for a given angular rate input to said apparatus when said primary mass is excited in said driven motion at a resonant frequency of said sensing motion.

3. An apparatus as defined in claim 1 wherein said primary and secondary masses and said primary and secondary flexure structures comprise surface micromachined silicon structures.