CAPACITIVE ACCELEROMETER

• US 20100050771A1
• Filed: 12/05/2007
• Published: 03/04/2010
• Est. Priority Date: 12/05/2006
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Jung, Sung-Hae, Choi, Chang-Auck, Je, Chang-Han, Lee, Myung-Lae, Hwang, Gunn
• Granted Patent: US 8,113,054 B2
• Time in Patent Office: Days
• US Class Current: 73/514.320
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

A conventional capacitive accelerometer has a limitation in reducing a distance between a sensing electrode and a reference electrode, and requires a complex process and a separate method of correcting a clearance difference caused by a process error. However, the capacitive accelerometer of the present invention has high sensitivity, can be simply manufactured by maintaining a very narrow distance between a reference electrode and a sensing electrode, and can make it unnecessary to individually correct each manufactured accelerometer by removing or drastically reducing a functional difference due to a process error.

Claims

1. A capacitive accelerometer comprising:

a substrate;

a sensing mass body disposed above and spaced apart from the substrate, and comprising a mass main body, a support spring, and a sensing electrode;

a support part coupling the sensing mass body to the substrate;

a reference electrode disposed adjacent to the sensing electrode and movable farther away from or closer to the sensing electrode;

a driving unit moving the reference electrode; and

a stopper limiting the motion of the reference electrode.

2. The capacitive accelerometer of claim 1, wherein an allowable clearance of the stopper is less than a distance between the sensing electrode and the reference electrode when the driving unit is not driven.

3. The capacitive accelerometer of claim 1, wherein, when the driving unit is driven to move the reference electrode by a maximum distance toward the sensing electrode, a distance between the reference electrode and the sensing electrode ranges from 0.2 to 0.7 mm.

4. The capacitive accelerometer of claim 1, wherein each of the sensing electrode and the reference electrode has a comb shape, and teeth of the sensing electrode and teeth of the reference electrode alternate with each other.

5. The capacitive accelerometer of claim 1, wherein a distance A between the reference electrode and the sensing electrode when the driving unit is not driven is equal to a sum of a distance between B between the reference electrode and the sensing electrode when the driving unit is driven and an allowable clearance C of the stopper.

6. The capacitive accelerometer of claim 1, wherein the driving unit moves the reference electrode by an electrostatic force.

7. The capacitive accelerometer of claim 6, wherein the driving unit comprises a first finger,

the capacitive accelerometer further comprising a reference electrode body comprising a plurality of reference electrodes, a connecting part connecting the plurality of reference electrodes, and a second finger spaced apart from and engaging with the first finger,

wherein an allowable clearance of the stopper is less than a distance between the first finger and the second finger when the driving unit is not driven.

8. The capacitive accelerometer of claim 1, wherein the stopper is connected to the reference electrode by a spring.

9. A capacitive accelerometer comprising:

a substrate;

a reference electrode fixed to the substrate;

a sensing mass body disposed above and spaced apart from the substrate, comprising a sensing electrode disposed adjacent to the reference electrode, a support spring, and a mass main body, and movable farther away from or closer to the reference electrode;

a driving unit capable of moving the sensing mass body; and

a stopper capable of limiting the motion of the sensing mass body caused by the driving unit.

10. The capacitive accelerometer of claim 9, wherein an allowable clearance of the stopper is less than a distance between the sensing electrode and the reference electrode when the driving unit is not driven.

11. The capacitive accelerometer of claim 9, wherein, when the driving unit is driven to move the sensing electrode by a maximum distance toward the reference electrode, a distance between the sensing electrode and the reference electrode ranges from 0.2 to 0.7 mm.

12. The capacitive accelerometer of claim 9, wherein each of the sensing electrode and the reference electrode has a comb shape, and teeth of the sensing electrode and teeth of the reference electrode alternate with each other.

13. The capacitive accelerometer of claim 9, wherein a distance a between the reference electrode and the sensing electrode when the driving unit is not driven is equal to a sum of a distance b between the reference electrode and the sensing electrode when the driving unit is driven and an allowable clearance c of the stopper.

14. The capacitive accelerometer of claim 9, wherein the driving unit moves the sensing mass body using an electrostatic force.

15. The capacitive accelerometer of claim 14, wherein the driving unit comprises a first finger,

wherein the sensing mass body further comprises a second finger extending from the support spring and spaced apart from and engaging with the first finger, wherein an allowable clearance of the stopper is less than a distance between the first finger and the second finger when the driving unit is not driven.

16. A capacitive accelerometer comprising:

a substrate;

a reference electrode disposed above and spaced apart from the substrate;

a sensing electrode disposed above and spaced apart from the substrate;

a driving unit capable of adjusting relative positions of the reference electrode and the sensing electrode; and

a stopper capable of limiting the motion of the driving unit.