Vibration gyro element, vibration gyro sensor, electronic device, and method of detecting physical quantity of vibration

• US 8,783,104 B2
• Filed: 03/08/2011
• Issued: 07/22/2014
• Est. Priority Date: 03/19/2010
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Nishizawa, Ryuta
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): Shah, Samir M
• Application Number:
  US13/042,795
• Publication Number:
  US 20110226057A1
• Time in Patent Office: 1,232 Days
• Field of Search: 735/040.2, 735/041.2, 735/033, 735/10
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams

Abstract

A vibration gyro element includes: a base section; a detection arm extending from the base section in a first direction; a joint section disposed at an end portion of the base section; a first drive arm extending from the joint section in a second direction intersecting with the first direction in a plan view; a second drive arm extending from the joint section in a direction opposite to the extending direction of the first drive arm; a first set of drive electrodes provided to the first drive arm; a second set of drive electrodes provided to the second drive arm; and a set of detection electrodes provided to the detection arm, wherein the first drive arm vibrates in a third direction perpendicular to the first direction and the second direction, the second drive arm vibrates in a same direction as the first drive arm.

Claims

1. A vibration gyro element comprising:

a base section;

a detection arm extending from the base section in a first direction;

a joint section disposed at an end portion of the detection arm opposite to another end portion near to the base section;

a first drive arm extending from the joint section in a second direction intersecting with the first direction in a plan view;

a second drive arm extending from the joint section in a direction opposite to the second direction;

a first drive electrode provided to the first drive arm;

a second drive electrode provided to the second drive arm; and

a detection electrode provided to the detection arm,

wherein the first drive arm and the second drive arm vibrate at the same time, in-phase, in a third direction perpendicular to the first direction and the second direction, so as to detect a physical quantity acting around an axis in the first direction.

2. The vibration gyro element according to claim 1, wherein

the detection arm, the first drive arm, and the second drive arm are all made of a same piezoelectric material.

3. The vibration gyro element according to claim 1, wherein

the first drive arm, the second drive arm, and the detection arm each have a pair of principal surfaces opposed to each other and a pair of side surfaces coupling the principal surfaces to each other,

the first drive electrode and the second drive electrode are respectively disposed on at least one of the pair of principal surfaces of the first drive arm and the pair of principal surfaces of the second drive arm, and respectively form first and second interdigital transducer electrodes in which the first and second drive electrodes are arranged in the second direction, and

the detection electrode is disposed on the pair of principal surfaces and the pair of side surfaces of the detention arm in a solid manner.

4. The vibration gyro element according to claim 3, wherein

each of the first and second interdigital transducer electrodes is configured with a plurality of electrodes that are provided in a comb-like pattern, distances between a plurality of two adjacent electrodes are different.

5. The vibration gyro element according to claim 4, wherein

a first distance of the distances between the plurality of two adjacent electrodes located in a vicinity of a tip of either of the first and second drive arms is larger than a second distance of the distances between the plurality of two adjacent electrodes located in a vicinity of the joint section.

6. A vibration gyro sensor comprising:

the vibration gyro element according to claim 1; and

a detection circuit adapted to detect the physical quantity acting around the axis in the first direction based on an electrical signal output from the detection electrode.

7. An electronic device comprising:

a first sensor including the vibration gyro element according to claim 1; and

a second sensor including a detection element adapted to detect a second physical quantity different from the physical quantity detected by the first sensor.

8. A vibration gyro element comprising:

a base section;

a first detection arm extending from the base section in a first direction;

a second detection arm extending from the base section in a direction opposite to the first direction;

a first joint section disposed at an end portion of the first detection arm opposite to the base section;

a second joint section disposed at an end portion of the second detection arm opposite to the base section;

a first drive arm extending from the first joint section in a second direction intersecting with the first direction in a plan view;

a second drive arm extending from the first joint section in a direction opposite to the second direction;

a third drive arm extending from the base section in the second direction;

a fourth drive arm extending from the base section in a direction opposite to the second direction;

a fifth drive arm extending from the second joint section in the second direction; and

a sixth drive arm extending from the second joint section in a direction opposite to the second direction,

wherein the first through sixth drive arms respectively have first through sixth drive electrodes,

the first and second detection arms respectively have first and second detention electrodes,

wherein the first, second, fifth and sixth drive arms vibrate at the same time, in-phase, in a third direction perpendicular to the first direction and the second direction;

the third and fourth drive arms vibrate in a direction opposite to the third direction at the same time so as to detect a physical quantity acting around an axis in the first direction.

9. The vibration gyro element according to claim 8, wherein

the first through sixth drive arms, the first detection arm, and the second detection arm each have a pair of principal surfaces opposed to each other and a pair of side surfaces coupling the principal surfaces to each other,

each of the first through sixth drive electrodes is disposed on at least one of the pair of principal surfaces, and forms an interdigital transducer electrode in which each of the first through sixth drive electrodes is arranged in the second direction, and

the first and second detection electrodes are respectively disposed on the pair of principal surfaces and the pair of side surfaces in a solid manner.

10. A method of detecting a physical quantity of a vibration gyro sensor, the method comprising:

providing a vibration gyro element including a base section, a detection arm extending from the base section in a first direction, a joint section disposed at an end portion of the detection arm opposite to the base section, a first drive arm extending from the joint section in a second direction intersecting with the first direction in a plan view, and a second drive arm extending from the joint section in a direction opposite to the second direction;

vibrating the first drive arm and the second drive arm at the same time, in-phase, in a third direction perpendicular to the first direction and the second direction;

generating a Coriolis force in the first drive arm and the second drive arm in accordance with the physical quantity acting around an axis in the first direction, thereby generating a detection vibration in the second direction in the detection arm; and

detecting the physical quantity based on an electrical signal generated by a migration of a charge due to an electrical field generated by the detection vibration.