US 7,002,284 B2Granted

Thin-film micromechanical resonator, thin-film micromechanical resonator gyro, and navigation system and automobile using the resonator gyro

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsSatoshi Ouchi, Toshiyuki Nozoe, Koji Nomura, Hirofumi Tajika

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Abstract

A thin film micromechanical resonator (resonator) having improved drive efficiency, a resonator gyro having improved sensitivity in detecting an angular velocity, and a navigation system and an automobile using the resonator gyro. The resonator includes a tuning fork structure made of a non-piezoelectric material, and a first electrode and a second electrode disposed respectively at the inner side and the outer side of the tuning fork arm. On the first and second electrodes, a first piezo film and a second piezo film are provided respectively, and a third electrode and a fourth are respectively provided electrode thereon. When an alternating voltage is applied to the third and fourth electrodes at the opposite phases each other, the tuning fork resonates in the direction perpendicular to the center line. The resonator gyro detects, at the sensing section which is formed of another electrodes and another piezo film, the Coriolis force generated in proportion to angular velocity given to the resonator.

Claims32

Dependent claims

A thin film micromechanical resonator gyro comprising

(1) a tuning fork having at least two arms and at least one stem connecting said arms, formed of a non-piezoelectric material;
(2) a drive section including
(a) a first electrode provided on at least one main surface of at least one of said arms in a place inner than a center line of the main surface,
(b) a second electrode provided on said at least one main surface in a place outer than the center line with a separation from said first electrode,
(c) a first piezoelectric thin film provided on said first electrode,
(d) a second piezoelectric thin film provided on said second electrode,
(e) a third electrode provided on said first piezoelectric thin film, and
(f) a fourth electrode provided on said second piezoelectric thin film;
and
(3) a sensing section provided on said at least one main surface of said at least one of arms, wherein
said tuning fork resonates in the direction perpendicular to said center line (X direction) when an alternating voltage is applied to said third and fourth electrodes at opposite phases each other, and
said sensing section detects flexion of said arm due to an angular velocity given thereto, caused in the direction perpendicular to said main surface (Z direction) in proportion to the Coriolis force, as an electrical or optical output, wherein
said sensing section includes a fifth electrode disposed on said at least one main surface with a separation from said first and second electrodes, a third piezoelectric thin film provided on said fifth electrode, an a sixth electrode provided on said third piezoelectric thin film,
wherein
said fifth electrode is disposed in a place further to an end of said arm than said first and second electrodes,
a first lead out electrode is provided between said first and second electrodes with a separation from the electrodes,
said fifth electrode is connected with said first lead out electrode,
at least circumference portions of said first and second electrodes and said first and second piezoelectric thin films, and said first lead out electrode are covered with an insulating layer,
a second lead out electrode is provided between said third and fourth electrodes on said insulating layer with a separation from said third and fourth electrodes,
said sixth electrode is connected with said second lead out electrode, and
said first and second electrodes, said third and fourth electrodes, said fifth and sixth electrodes, said first and second lead out electrodes, said first and second piezoelectric thin films, and said third piezoelectric thin film are disposed substantially symmetric to said center line.

18 more elements

A thin film micromechanical resonator gyro comprising:

1) a tuning fork having at least two arms and at least one stem connecting said arms, formed of a non-piezoelectric material;
2) a drive section including
(a) a first electrode provided on at least one main surface of at least one of said arms in a place inner than a center line of the main surface,
(b) a second electrode provided on said at least one main surface in a place outer than the center line with a separation from said first electrode,
(c) a first piezoelectric thin film provided on said first electrode,
(d) a second piezoelectric thin film provided on said second electrode,
(e) a third electrode provided on said first piezoelectric thin film, and
(f) a fourth electrode provided on said second piezoelectric thin film;
and
(3) a sensing section provided on said at least one main surface of said at least one of arms, wherein
said tuning fork resonates in the direction perpendicular to said center line (X direction) when an alternating voltage is applied to said third and fourth electrodes at opposite phases each other, and
said sensing section detects flexion of said arm due to an angular velocity given thereto, caused in the direction perpendicular to said main surface (Z direction) in proportion to the Coriolis force, as an electrical or optical output, wherein
said sensing section including
i) a fifth electrode provided on said at least one main surface in a place further to an end portion of said arm than said first and second electrodes, with a separation from said first and second electrodes,
ii) a third piezoelectric thin film provided on said fifth electrode, and
iii) a sixth electrode provided on said third piezoelectric thin film;
further comprising a lead section which includes
i) a first lead out electrode provided between said first and second electrodes with a separation from the electrodes, the first lead out electrode being connected with said fifth electrode,
ii) a fourth piezoelectric thin film provided on said first lead out electrode, and
iii) a second lead out electrode provided on said fourth piezoelectric thin film and connected with said sixth electrode, wherein
said sixth electrode detects an electric charge caused by vibration due to flexion of said arm.

18 more elements

A navigation system which includes a thin film micromechanical resonator gyro, said thin film micromechanical resonator gyro comprising:

(1) a tuning fork having at least two arms and at least one stem connecting said arms, formed of a non-piezoelectric material;
(2) a drive section including
(a) a first electrode provided on at least one main surface of at least one of said arms in a place inner than a center line of the main surface,
(b) a second electrode provided on said at least one main surface in a place outer than the center line with a separation from said first electrode,
(c) a first piezoelectric thin film provided on said first electrode,
(d) a second piezoelectric thin film provided on said second electrode,
(e) a third electrode provided on said first piezoelectric thin film, and
(f) a fourth electrode provided on said second piezoelectric thin film;
and
(3) a sensing section provided on said at least one main surface of said at least one of arms, wherein
said tuning fork resonates in the direction perpendicular to said center line (X direction) when an alternating voltage is applied to said third and fourth electrodes at an inverse phase to each other, and
said sensing section detects flexion of said arm due to an angular velocity given thereto, caused in the direction perpendicular to said main surface (Z direction) in proportion to the Coriolis force, as an electrical or optical output, wherein
said sensing section including
i) a fifth electrode provided on said at least one main surface in a place further to an end portion of said arm than said first and second electrodes, with a separation from said first and second electrodes,
ii) a third piezoelectric thin film provided on said fifth electrode, and
iii) a sixth electrode provided on said third piezoelectric thin film;
further comprising a lead section which includes
i) a first lead out electrode provided between said first and second electrodes with a separation from the electrodes, the first lead out electrode being connected with said fifth electrode,
ii) a fourth piezoelectric thin film provided on said first lead out electrode, and
iii) a second lead out electrode provided on said fourth piezoelectric thin film and connected with said sixth electrode, wherein
said sixth electrode detects an electric charge caused by vibration due to flexion of said arm.

18 more elements

An automobile which includes a thin film micromechanical resonator gyro, used as a sensor for detecting one of a yaw rate, a rolling and a pitching, said thin film micromechanical resonator gyro comprising:

(1) a tuning fork having at least two arms and at least one stem connecting said arms, formed of a non-piezoelectric material;
(2) a drive section including
(a) a first electrode provided on at least one main surface of at least one of said arms in a place inner than a center line of the main surface,
(b) a second electrode provided on said at least one main surface in a place outer than the center line with a separation from said first electrode,
(c) a first piezoelectric thin film provided on said first electrode,
(d) a second piezoelectric thin film provided on said second electrode,
(e) a third electrode provided on said first piezoelectric thin film, and
(f) a fourth electrode provided on said second piezoelectric thin film;
and
(3) a sensing section provided on said at least one main surface of said at least one of arms, wherein
said tuning fork resonates in the direction perpendicular to said center line (X direction) when an alternating voltage is applied to said third and fourth electrodes at an inverse phase to each other, and
said sensing section detects flexion of said arm due to an angular velocity given thereto, caused in the direction perpendicular to said main surface (Z direction) in proportion to the Coriolis force, as an electrical or optical output, wherein
said sensing section including
i) a fifth electrode provided on said at least one main surface in a place further to an end portion of said arm than said first and second electrodes, with a separation from said first and second electrodes,
ii) a third piezoelectric thin film provided on said fifth electrode, and
iii) a sixth electrode provided on said third piezoelectric thin film;
further comprising a lead section which includes
i) a first lead out electrode provided between said first and second electrodes with a separation from the electrodes, the first lead out electrode being connected with said fifth electrode,
ii) a fourth piezoelectric thin film provided on said first lead out electrode, and
iii) a second lead out electrode provided on said fourth piezoelectric thin film and connected with said sixth electrode, wherein
said sixth electrode detects an electric charge caused by vibration due to flexion of said arm.

18 more elements

A navigation system using a thin film micromechanical resonator gyro, said thin film micromechanical resonator gyro comprising:

(1) a tuning fork having at least two arms and at least one stem connecting said arms, formed of a non-piezoelectric material;
(2) a drive section including
(a) a first electrode provided on at least one main surface of at least one of said arms in a place inner than a center line of the main surface,
(b) a second electrode provided on said at least one main surface in a place outer than the center line with a separation from said first electrode,
(c) a first piezoelectric thin film provided on said first electrode,
(d) a second piezoelectric thin film provided on said second electrode,
(e) a third electrode provided on said first piezoelectric thin film, and
(f) a fourth electrode provided on said second piezoelectric thin film;
and
(3) a sensing section provided on said at least one main surface of said at least one of arms, wherein
said tuning fork resonates in the direction perpendicular to said center line (X direction) when an alternating voltage is applied to said third and fourth electrodes at an inverse phase to each other, and
said sensing section detects flexion of said arm due to an angular velocity given thereto, caused in the direction perpendicular to said main surface (Z direction) in proportion to the Coriolis force, as an electrical or optical output,
wherein
said sensing section includes a fifth electrode disposed on said at least one main surface with a separation from said first and second electrodes, a third piezoelectric thin film provided on said fifth electrode, and a sixth electrode provided on said third piezoelectric thin film
wherein said fifth electrode is disposed in a place further to an end of said arm than said first and second electrodes,
a first lead out electrode is provided between said first and second electrodes with a separation from the electrodes,
said fifth electrode is connected with said first lead out electrode,
at least circumference portions of said first and second electrodes and said first and second piezoelectric thin films, and said first lead out electrode are covered with an insulating layer,
a second lead out electrode is provided between said third and fourth electrodes on said insulating layer with a separation from said third and fourth electrodes,
said sixth electrode is connected with said second lead out electrode, and
said first and second electrodes, said third and fourth electrodes, said fifth and sixth electrodes, said first and second lead out electrodes, said first and second piezoelectric thin films, and said third piezoelectric thin film are disposed substantially symmetric to said center line.

18 more elements

An automobile using a thin film micromechanical resonator gyro for detecting one of a yaw rate, a rolling and a pitching, said thin film micromechanical resonator gyro comprising

(1) a tuning fork having at least two arms and at least one stem connecting said arms, formed of a non-piezoelectric material;
(2) a drive section including
(a) a first electrode provided on at least one main surface of at least one of said arms in a place inner than a center line of the main surface,
(b) a second electrode provided on said at least one main surface in a place outer than the center line with a separation from said first electrode,
(c) a first piezoelectric thin film provided on said first electrode,
(d) a second piezoelectric thin film provided on said second electrode,
(e) a third electrode provided on said first piezoelectric thin film, and
(f) a fourth electrode provided on said second piezoelectric thin film;
and
(3) a sensing section provided on said at least one main surface of said at least one of arms, wherein
said tuning fork resonates in the direction perpendicular to said center line (X direction) when an alternating voltage is applied to said third and fourth electrodes at an inverse phase to each other, and
said sensing section detects flexion of said arm due to an angular velocity given thereto, caused in the direction perpendicular to said main surface (Z direction) in proportion to the Coriolis force, as an electrical or optical output,
wherein
said sensing section includes a fifth electrode disposed on said at least one main surface with a separation from said first and second electrodes, a third piezoelectric thin film provided on said fifth electrode, and a sixth electrode provided on said third piezoelectric thin film
wherein
said fifth electrode is disposed in a place further to an end of said arm than said first and second electrodes,
a first lead out electrode is provided between said first and second electrodes with a separation from the electrodes,
said fifth electrode is connected with said first lead out electrode,
at least circumference portions of said first and second electrodes and said first and second piezoelectric thin films, and said first lead out electrode are covered with an insulating layer,
a second lead out electrode is provided between said third and fourth electrodes on said insulating layer with a separation from said third and fourth electrodes,
said sixth electrode is connected with said second lead out electrode, and
said first and second electrodes, said third and fourth electrodes, said fifth and sixth electrodes, said first and second lead out electrodes, said first and second piezoelectric thin films, and said third piezoelectric thin film are disposed substantially symmetric to said center line.

19 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/470,669Filed 26 Nov 2002
Priority: JP 2001-36056027 Nov 2001
Published: US 2004/0095046 A120 May 2004
Granted: 21 Feb 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01C 19/5607
Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces: using vibrating tuning forks
H03H 9/21
Constructional features of resonators consisting of piezoelectric or electrostrictive material: crystal tuning forks
H03H 9/2484
Single-Ended Tuning Fork resonators: with two fork tines, e.g. Y-beam cantilever
H03H 2003/0492
Resonance frequency: during the manufacture of a tuning-fork