Acceleration sensor

• US 20010049961A1
• Filed: 12/29/2000
• Published: 12/13/2001
• Est. Priority Date: 02/18/2000
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited, Fujitsu Media Devices Limited (Fujitsu Limited)
• Original Assignee: Fujitsu Limited, Fujitsu Media Devices Limited (Fujitsu Limited)
• Inventors: Tanaka, Hiroshi, Ishikawa, Hiroshi, Ikata, Osamu
• Application Number:
  US09/750,178
• Publication Number:
  US 20010049961A1
• Time in Patent Office: Days
• US Class Current: 73/514.34
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type

Abstract

An acceleration sensor includes a piezoelectric single-plate having a weight part and a detection part. The piezoelectric single-plate is, for example, an X-cut plate of LiNbO₃.

Claims

1. An acceleration sensor comprising:

a piezoelectric single-plate having a weight part and a detection part.

2. The acceleration sensor as claimed in

claim 1

, further comprising:

a detection electrode provided on a first surface of the piezoelectric single-plate, an electric signal caused by inertia force exerted onto the weight part resulting from acceleration being output via the detection electrode; and

a ground electrode provided on a second surface of the piezoelectric single-plate opposite to the first surface.

3. The acceleration sensor as claimed in

claim 2

, wherein the detection electrode comprises two electrode parts arranged side by side in a direction in which the acceleration is applied to the acceleration sensor.

4. The acceleration sensor as claimed in

claim 2

, wherein the detection electrode comprises two electrode parts arranged side by side in a direction perpendicular to another direction in which the acceleration is applied to the acceleration sensor.

5. The acceleration sensor as claimed in

claim 1

, wherein the piezoelectric single-plate has a supporting position which does not include a center of gravity of the piezoelectric single-plate.

6. The acceleration sensor as claimed in

claim 1

, wherein the piezoelectric single-plate has a supporting position which includes a center of gravity of the piezoelectric single-plate.

7. The acceleration sensor as claimed in

claim 1

, wherein the piezoelectric single-plate has a supporting position with which the detection electrode overlaps.

8. The acceleration sensor as claimed in

claim 1

, wherein the piezoelectric single-plate is an X-cut plate of LiNbO₃.

9. The acceleration sensor as claimed in

claim 2

, further comprising another ground electrode provided on the first surface of the piezoelectric single-plate.

10. The acceleration sensor as claimed in

claim 2

, wherein the ground electrode is thicker than the detection electrode.

11. The acceleration sensor as claimed in

claim 2

, wherein the detection electrode and the ground electrodes have respective densities that are greater than a density of the piezoelectric single-plate.

12. The acceleration sensor as claimed in

claim 9

, further comprising an electrically conductive resin that electrically connects the ground electrode and said another ground electrode.

13. The acceleration sensor as claimed in

claim 9

, further comprising an insulating resin provided in a groove that separates the detection electrode and said another ground electrode from each other.

14. The acceleration sensor as claimed in

claim 2

, further comprising:

a package to which the piezoelectric single-plate is attached;

an electrode terminal provided on the package; and

an electrically conductive adhesive agent which attaches the piezoelectric single-plate to the package and electrically connects the detection electrode and the electrode terminal.

15. The acceleration sensor as claimed in

claim 2

, further comprising:

a package to which the piezoelectric single-plate is attached;

an electrode terminal provided on the package; and

an anisotropic electrically conductive adhesive agent which attaches the piezoelectric single-plate to the package and electrically connects the detection electrode and the electrode terminal.

16. The acceleration sensor as claimed in

claim 2

, further comprising a flexible printed-circuit cable to which the detection electrode and the ground electrode are connected.

17. The acceleration sensor as claimed in

claim 2

, further comprising wires connecting the detection electrode and the ground electrodes to electrode terminals formed on a member by which the piezoelectric single-plate is supported.

18. The acceleration sensor as claimed in

claim 2

, further comprising:

a package which accommodates the piezoelectric single-plate; and

an electrically conductive resin which electrically connects the ground electrode to an electrode terminal provided on the package.

19. The acceleration sensor as claimed in

claim 1

, further comprising:

an electric circuit that processes an electric signal output from the piezoelectric single-plate; and

a package which accommodates the electric circuit and the piezoelectric single-plate.

20. The acceleration sensor as claimed in

claim 19

, wherein the package is provided with a guide base positioning and supporting the piezoelectric single-plate.

21. The acceleration sensor as claimed in

claim 19

, wherein the electric circuit is located below the piezoelectric single-plate.