Acceleration sensor

Patent metadata

Field	Value
Publication number	US-9753057-B2
Application number	US-201414499324-A
Country	US
Kind code	B2
Filing date	Sep 29, 2014
Priority date	Apr 27, 2012
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

An acceleration sensor includes a fixation member, a weight member including a plate with two opposing sides parallel or substantially parallel to an X-direction and two opposing sides parallel to a Y-axis direction in a plan view, the weight member including a cutout extending in a direction about 45° relative to the X and Y axis directions, a vibrating beam linearly extending in the direction about 45° relative to the X and Y axis directions in the plan view, and one end portion is connected to the fixation member and the other end portion is connected to the weight member, the vibrating beam is partly arranged within the cutout and supporting the weight member to be displaceable in a Z-axis direction, a driver disposed on the vibrating beam and vibrating the vibrating beam, and a detector disposed on the vibrating beam and outputting a detection signal that is changed depending on deformation of the vibrating beam.

First claim

What is claimed is:

1. An acceleration sensor comprising:
a fixation member;
a weight member including two opposing sides parallel or substantially parallel to a first direction and two opposing sides parallel or substantially parallel to a second direction perpendicular or substantially perpendicular to the first direction when looked at in a plan view, the weight member including a cutout that extends in a direction of about 45° relative to the first direction and the second direction;
a vibrating beam that linearly extends in the direction of about 45° relative to the first direction and the second direction when looked at in a plan view, and including a first end portion connected to the fixation member and a second end portion connected to the weight member, the vibrating beam being partially arranged within the cutout and supporting the weight member to be displaceable in a third direction that is perpendicular or substantially perpendicular to the first direction and the second direction;
a driver disposed on the vibrating beam and vibrating the vibrating beam; and
a detector disposed on the vibrating beam and configured to output a detection signal that is changed depending on deformation of the vibrating beam.

2. The acceleration sensor according to claim 1 , wherein a connected position between the vibrating beam and the weight member is located near or adjacent to a barycentric position of the weight member.

3. The acceleration sensor according to claim 2 , wherein when a reference size is defined as a lengthwise size of the vibrating beam in a state that the first end portion of the vibrating beam is connected to the fixation member, and that the second end portion of the vibrating beam is connected to the weight member at the barycentric position of the weight member, the lengthwise size of the vibrating beam is not less than about 0.6 times and less than about 1.2 times the reference size.

4. The acceleration sensor according to claim 3 , wherein the lengthwise size of the vibrating beam is not less than about 1.0 times and less than about 1.2 times the reference size.

5. The acceleration sensor according to claim 1 , further comprising a first holding beam and a second holding beam each including a first end portion connected to the fixation member and a second end portion connected to the weight member, the first holding beam and the second holding beam being arranged line-symmetrically with an axis of symmetry defined as an axis extending in the direction of about 45° relative to the first direction and the second direction.

6. The acceleration sensor according to claim 5 , wherein the first holding beam is connected to the weight member at a first edge of an opening of the cutout, and the second holding beam is connected to the weight member at a second edge of the opening of the cutout.

7. The acceleration sensor according to claim 6 , wherein an angle defined by each of the first and second holding beams relative to the vibrating beam is not smaller than about 60° and smaller than about 135°.

8. The acceleration sensor according to claim 5 , wherein each of the first holding beam and the second holding beam is linear shaped.

9. The acceleration sensor according to claim 5 , wherein each of the first holding beam and the second holding beam is L-shaped or substantially L-shaped.

10. The acceleration sensor according to claim 5 , wherein each of the first holding beam and the second holding beam includes at least a pair of partial holding beams.

11. The acceleration sensor according to claim 5 , wherein each of the first holding beam and the second holding beam includes at least three partial holding beams.

12. The acceleration sensor according to claim 5 , wherein each of the first holding beam and the second holding beam includes at least five partial holding beams.

13. The acceleration sensor according to claim 1 , further comprising a first holding beam including a first end portion connected to the fixation member and a second end portion connected to the weight member, the first holding beam including a first partial holding beam disposed to extend in the first direction and a second partial holding beam disposed to extend in the second direction; and
a second holding beam including a first end portion connected to the fixation member and a second end portion connected to the weight member, the second holding beam including a first partial holding beam disposed to extend in the second direction and a second partial holding beam disposed to extend in the first direction.

14. The acceleration sensor according to claim 1 , wherein the fixation member has an external shape that is a rectangular or substantially rectangular frame.

15. The acceleration sensor according to claim 1 , wherein the weight member includes a substantially quadrangular plate.

16. The acceleration sensor according to claim 1 , further comprising a piezoelectric layer and a lower electrode layer are disposed on the vibrating beam only where the driver and the detector are disposed.

17. The acceleration sensor according to claim 1 , further comprising a piezoelectric layer and a lower electrode layer disposed along an entire surface of the vibrating beam.

Assignees

• Murata Manufacturing Co

Inventors

• Hada Takuo
• Fujimoto Katsumi
• Horiuchi Hideya
• Yoneda Toshimaro

Classifications

• G01P15/09 Primary

  by piezoelectric pick-up · CPC title

• G01P2015/0828

  the mass being of the paddle type being suspended at one of its longitudinal ends · CPC title

• G01P15/10 Primary

  by vibratory strings · CPC title

• G01P15/097

  by vibratory elements · CPC title