Accelerometer

• US 5,591,910 A
• Filed: 06/03/1994
• Issued: 01/07/1997
• Est. Priority Date: 06/03/1994
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Lin, Tsen-Hwang
• Primary Examiner(s): Oda, Christine K.
• Application Number:
  US08/253,799
• Time in Patent Office: 949 Days
• Field of Search: 73/517 R, 73/517 B, 73/514, 73/516 R, 73/514.01, 73/514.32, 73/514.38, 73/514.24, 73/514.16, 200/61.45 R
• US Class Current: 73/514.38
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass
• CPC Class Codes: G01P 2015/0831 the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration

Abstract

A plating of an inertial mass (207) in a micromechanical accelerometer (200) to increase sensitivity to smaller accelerations. The inertial mass (207) may be on a plate (206) suspended by hinges (208) over a sensing electrode (212) to measure displacement of the inertial mass (207) relative to the sensing electrode (212).

Claims

1. An accelerometer, comprising:

(a) a plate suspended over an electrode by a set of hinges, each of said hinges is affixed to a corresponding post extending from a plane including said electrode;

(b) an inertial mass on said plate, said inertial mass characterized as a material plated onto said plate; and

(c) sensing circuitry connected between said hinges and said electrode.

2. The accelerometer of claim 1, wherein:

(a) said electrode is planar; and

(b) said set of hinges is four hinges and said plate is suspended parallel to said electrode.

3. The accelerometer of claim 2, wherein:

(a) said sensing circuitry includes a capacitance detector coupled to said plate and said electrode.

4. The accelerometer of claim 3, wherein:

(a) said inertial mass includes electrolessly plated nickel; and

(b) said plate includes a seed layer for said inertial mass.

5. The accelerometer of claim 1, wherein:

(a) said electrode is centered under said plate; and

(b) said set of hinges is four hinges and said plate is suspended parallel to said electrode.

6. The accelerometer of claim 5, wherein:

(a) said sensing circuitry includes a contact detector coupled to said plate and said electrode.

7. The accelerometer of claim 6, wherein:

(a) said inertial mass includes electrolessly plated nickel; and

(b) said plate includes a seed layer for said inertial mass.

8. The accelerometer of claim 1, wherein:

(a) said set of hinges is two hinges; and

(b) said electrode is under said plate and to one side of a line connecting said two hinges.

9. The accelerometer of claim 8, wherein:

(a) said sensing circuitry includes a contact detector coupled to said plate and said electrode.

10. The accelerometer of claim 9, wherein:

(a) said inertial mass includes electrolessly plated nickel; and

(b) said plate includes a seed layer for said inertial mass.