Angular velocity sensor having a balanced tuning fork structure and the method of manufacture

• US 5,445,025 A
• Filed: 07/15/1993
• Issued: 08/29/1995
• Est. Priority Date: 02/03/1993
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tamura, Masami, Nishimura, Hitoshi, Terada, Jiro, Takenaka, Hiroshi, Ushihara, Masaharu, Kaino, Kikuo
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US08/092,354
• Time in Patent Office: 775 Days
• Field of Search: 73/505, 73/570, 73/493, 73/1 D, 310/321, 310/329, 310/370
• US Class Current: 73/504.15
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719

Abstract

An angular velocity sensor having a tuning-fork structure comprising a first vibrator including a first actuator and a first detector each attached to a metal plate and joined orthogonally to each other, and a second vibrator including a second actuator and a second detector each attached to another metal plate and joined orthogonally to each other, the two vibrators being coupled by an electrode block to each other in a generally parallel relationship along the axis of detection of the sensor. The first and second detectors have a rectangular plate shape each holding a piezoelectric element. The rectangular plate shape has a lengthwise edge and a widthwise edge where the lengthwise edge parallel to the axis of detection of the sensor and is longer than the width wise edge. At least one of the lengthwise edges of the detectors has a beveled surface formed by removing metal at an angle from the lengthwise edge of the detector to balance the sensor.

Claims

1. An angular velocity sensor comprising:

a first metal plate having a generally rectangular shape, a first lengthwise dimension, and a first metal surface;

a second metal plate having a generally rectangular shape, a second lengthwise dimension, and a second metal surface;

one of said first metal plate and said second metal plate having at least one beveled corner edge, said one beveled corner edge having a lengthwise dimension parallel to an axis of detection of the angular velocity sensor and parallel to said first lengthwise dimension and said second lengthwise dimension;

a first vibrator including a first actuator and a first detector joined orthogonally to each other;

a second vibrator including a second actuator and a second detector joined orthogonally to each other;

an electrode block coupling between the first and second vibrators;

said first and second vibrators arranged parallel to each other along the axis of detection and coupled to each other by said electrode block at the lowermost ends of said actuators forming a tuning-fork structure;

said first actuator and said first detector including first piezoelectric elements bonded to said first metal surface; and

said second actuator and said second detector including second piezoelectric elements bonded to said second metal surface.

2. An angular velocity sensor according to claim 1, wherein each of said actuators and said detectors has disposed thereon a piezoelectric substance sandwiched between two electrodes, at least one of the two electrodes being smaller than the piezoelectric substance and fitting within the outer edges of the piezoelectric substance.

3. An angular velocity sensor according to claim 1, wherein each of the first metal plate and the second metal plate includes a bend of 90 degrees formed by bending the first metal plate and the second metal plate along two slits formed in the metal plate extending from different edges of each of the first metal plate and the second metal plate respectively to a center region of each of the metal plates for forming an intersection arrangement, the two slits of each of the first metal plate and the second metal plate beginning at asymmetrical locations at the edges about a lengthwise center line of each of the first metal plate and the second metal plate and extending to almost the lengthwise center line of each of the first metal plate and the second metal plate.

4. An angular velocity sensor according to claim 1, wherein the first metal plate and the second metal plate each include a widthwise dimension which is shorter than the first and second lengthwise dimension.

5. An angular velocity sensor comprising:

a first vibrator including a first actuator piezoelectric element and a first detector piezoelectric element joined orthogonally to each other;

a second vibrator including a second actuator piezoelectric element and a second detector piezoelectric element joined orthogonally to each other;

said first vibrator and said second vibrator formed by bonding said piezoelectric elements to a generally flat rectangular shaped metal plate having a generally rectangular cross-section, a bend of 90 degrees, and a metal plate lengthwise edge, said metal plate having two slits perpendicular to the center of a long axis on a face of said metal plate, each of said slits beginning on one different edge of a face of said metal plate and extending toward an opposite edge a distance approximately one-half of the width of said metal plate, thus forming an upper and an lower part, said upper and lower parts rotated ninety degrees relative to one another until said upper part and said lower part intersect at a right angle to each other to form the bend; and

an electrode block coupling between the first and second vibrators;

at least one metal plate having a beveled corner edge where the first detector piezoelectric element and the second detector piezoelectric element is bonded, said beveled corner edge having a lengthwise dimension parallel to the axis of detection of the angular velocity sensor and parallel to the metal plate lengthwise edge.

6. An angular velocity sensor according to claim 5, wherein each of said actuator and detector elements has disposed thereon a piezoelectric substance sandwiched between two electrodes, at least one of the two electrodes being smaller than the piezoelectric substance and fitting within the outer edges of the piezoelectric substance.

7. An angular velocity sensor according to claim 6, wherein the metal plate of said first vibrator and the metal plate of said second vibrator each include a widthwise dimension which is shorter than the lengthwise dimension.