JPH10206162A - Variation gyro sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize cost and size reductions and stability of measuring of an angular velocity by constituting a vibration gyro sensor by a vibrator of the structure that three bar shaped vibrators parallel to each other are coupled at both ends. SOLUTION: Vibrators of the vibration gyro sensor 21 are obtained by quarrying a crystal row stone to plate states so that length, width and thickness becomes Y-, Z- and X-axis with respect to a crystal axis, processing rectangular holes 2, 3 by photolithography, and forming a left vibrating part 4, a central vibrating part 5 and right vibrating part 6 connected at both ends and parallel to each other. Electrodes of two types of four surface electrodes and front and back electrodes are formed on the parts 4, 5, 6 by depositing or photography, and any one is used as a driving electrode and the other is used as a detecting electrode. The parts 4, 6 are excited in the same direction and the part 5 is excited in an opposite direction by using the driving electrode, and vibration generated by a Coriolis force as the sensor 21 rotates in the Y-axis direction is detected as a voltage proportional to the angular velocity of the vibration by the detecting electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration gyro sensor for detecting an angular velocity.

[0002]

2. Description of the Related Art Conventionally, mechanical rotary gyroscopes have been used as inertial navigation devices for airplanes and ships.
This mechanical rotary gyroscope has stable performance, but on the other hand, the equipment is large and expensive, and it is difficult to incorporate it into small equipment.

In recent years, however, research into miniaturization of gyroscopes has been advanced, and a vibrating body is excited by a piezoelectric ceramic, and a voltage generated by vibration generated by Coriolis force received by rotation of the vibrating body is provided in another vibrating body. A vibrating gyroscope that detects a voltage using a piezoelectric ceramic has been put into practical use, and is being used for a car navigation system, a camera shake prevention device for a video camera, and the like.

A conventional vibration gyro sensor using a piezoelectric ceramic will be described below with reference to the drawings. FIG. 6 is a perspective view showing a conventional rod-shaped vibration gyro sensor, and FIG. 7 is a perspective view showing a conventional tuning-fork type vibration gyro sensor. First, the configuration and operation of the vibrating gyro sensor will be described with reference to FIG.

In FIG. 6A, reference numeral 28 denotes a vibrating body made of metal, 29 denotes a driving electrode made of a piezoelectric ceramic for exciting the vibrating body, and 30 denotes a vibration caused when an angular velocity is given to the vibrating body. It is a detection electrode made of piezoelectric ceramics for detecting the generated voltage. 31 and 32 are nodes of bending vibration (referred to as first vibration) when the vibrating body is driven by the oscillation circuit.
Reference numerals 33 and 34 denote nodes of bending vibration (hereinafter referred to as second vibration) which occur when an angular velocity is applied.

It is assumed that the vibrating body 28 is performing the first vibration as shown in FIG.
Reference numerals 35 and 36 denote displacements of the bending vibration. When the vibrating body 28 is rotated around the z-axis at an angular velocity ω, Coriolis force F acts on the vibrating body in a direction perpendicular to the first vibration. The Coriolis force F is given by the following equation. F = 2 · MV · ω Here, M is the mass of the vibrating body, and V is the speed of vibration.

The second vibration is excited by the Coriolis force. The displacement of the vibration is as shown by 37 and 38 in FIG. The angular velocity can be known by detecting the voltage proportional to the angular velocity ω generated by the second vibration with the detection electrode 30.

Next, a conventional tuning fork shaped vibration gyro sensor will be described with reference to FIG. The vibrating body 39 has a structure in which second arms 42 and 43 are connected to upper portions of tuning fork arms 40 and 41. Reference numeral 44 denotes a driving electrode made of a piezoelectric ceramic, and reference numeral 45 denotes a detection electrode made of a piezoelectric ceramic for detecting an angular velocity voltage generated by the second vibration caused by Coriolis force.

The operation will be described. Due to the drive electrode 44, the arms 40 and 41 generate vibrations displaced right and left as indicated by arrows. By rotating this at angular velocity ω,
The arms 42 and 43 excite a second vibration that is displaced in a direction perpendicular to the arms 40 and 41 as indicated by arrows. By detecting the angular velocity voltage generated by the second vibration with the detection electrode 45, the angular velocity can be known.

[0010]

However, the conventional vibration gyro sensor has the following disadvantages.
That is, since the vibrating bodies shown in FIGS. 6 and 7 are all made of metal, the resonance frequencies of the first and second vibrations are liable to change depending on the temperature. For this reason, the angular velocity voltage fluctuates, and it is difficult to obtain an accurate angular velocity.

A piezoelectric ceramic plate is attached to the vibrator as a drive electrode and a detection electrode. For this reason, manufacturing costs are high. In addition, the angular velocity voltage becomes unstable due to the variation of the piezoelectric ceramic plate and the variation of the attaching position, and there is a problem in the reproducibility of the angular velocity.

In the case of the tuning fork type, it is difficult to mass-produce it with high accuracy due to its complicated structure. In addition, since the vibrator is large, it cannot be mounted on a small electronic device.

There is a report of a tuning fork type vibration gyro sensor using a piezoelectric crystal such as lithium tantalate as a vibrating body. However, since the tuning fork type supports the base, when subjected to shock or vibration, the vibration displacement of the tip of the arm becomes unstable,
This has an adverse effect on the angular velocity detection accuracy.

An object of the present invention is to provide a vibration gyro sensor capable of stably measuring an angular velocity at a small size and at low cost, in order to solve the above-mentioned problems.

[0015]

The gist of the present invention to achieve the above object is to provide a vibrating body in which each vibrating part has three vibrating parts having a bar shape, and these vibrating parts are parallel to each other. At both ends of the vibrating body at the base thereof.

The vibrating body is formed of quartz, and its longitudinal direction, width direction, and thickness direction are the Y axis of the quartz crystal axis, respectively.
It is characterized by the Z axis and the X axis.

The first and second vibrations of the vibrating part are bending vibrations, and the vibration direction is that the two right and left vibrating parts are in the same direction, and one central vibrating part is in the opposite direction to the left and right vibrating parts. It is characterized by the following.

An electrode for driving the vibrating body and an electrode for detecting the angular velocity are formed on each of the three vibrating parts.

An electrode formed on one vibrating portion is divided into two YZ planes and two YZ planes (hereinafter referred to as four-plane electrodes) and two YZ planes in the Y direction ( (Hereinafter referred to as front and back electrodes).

That is, the vibrating gyro sensor according to the present invention has a structure in which three parallel bar-shaped vibrating parts are formed of quartz and are connected to each other at the base of the vibrating body. Each vibrating part is provided with four-sided electrodes and front and back electrodes,
The structure is such that the first and second vibrations or the second and first vibrations are performed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vibration gyro sensor according to an embodiment of the present invention will be described below with reference to the drawings. 1 to 5 show a vibration gyro sensor according to an embodiment of the present invention. FIG. 1 is a perspective view showing a cutting direction in which a vibrating body is cut out from a rough quartz crystal. FIG. FIG. 3 is a perspective view showing a vibration gyro sensor provided with electrodes, FIG. 3 is a view for explaining the principle of the vibration gyro sensor, and FIGS. 4 and 5 are cross-sectional views of the electrode structure.

As shown in FIG. 1, the vibrating body 1 has a plate shape such that the length, width, and thickness are respectively set to the Y, Z, and X axes with respect to the crystal axes X, Y, and Z axes of the quartz crystal. It is cut out. Then, using photolithography technology, the rectangular holes 2,
3 is machined, and three vibrating portions parallel to each other, both ends of which are connected, that is, a left vibrating portion 4, a central vibrating portion 5, and a right vibrating portion 6, are connected and formed by vibrating body bases 7, 8. .

FIG. 2 is a perspective view showing a vibrating gyroscope 21 in which electrodes are provided on the vibrating body 1. The electrodes are left, center,
Two types are formed in each of the three vibrating portions 4, 5, and 6 on the right. The electrodes of the left vibrating part 4 have 9, 10, and 9 '(not shown) and 10' (not shown) on four surfaces, and 11, 12, and 11 '(not shown) divided into two on the front and back surfaces, respectively. ), 12 '
(Not shown). Similarly, the electrodes of the central vibrating part 5 are 13, 14 and 13 ', 14' and 15, 16, 15 'and 16', and the electrodes of the right vibrating part 6 are 17,
18 and 17 ', 18' and 19, 20 and 19 ', 2
0 '.

As these two types of electrodes, a four-sided electrode may be used as a drive electrode and front and back electrodes as detection electrodes, or a four-sided electrode may be used as a detection electrode and front and back electrodes as drive electrodes. The electrodes are formed using a vapor deposition technique or a photolithography technique. The sensor is fixed by applying an adhesive to the bases 7 and 8 and fixing the sensor to the support member.

FIG. 3 is a diagram for explaining the principle of detecting the angular velocity of the vibration gyro sensor 21. Vibrating gyro sensor 2
1 is a four-sided electrode, and the vibrating part is indicated by solid arrows 22 and 2
It vibrates alternately in the directions 3 and 24 and in the directions of solid arrows 22 ', 23' and 24 '. Alternatively, when the front and back electrodes are used, the vibrating portion vibrates in the directions of dashed arrows 25, 26, and 27, and in the directions of dashed arrows 25 ', 26', and 27 '.

It is now assumed that the vibrating gyro sensor 21 uses solid electrodes 22, 23, 2
It is assumed that they are driven in the directions of 4, 22 ', 23', and 24 '. When an angular velocity ω is applied around the Y axis, Coriolis force F acts in the Z axis direction. This force causes the oscillation of the dashed arrow. The angular velocity can be known by detecting the voltage proportional to the angular velocity ω generated by the vibration by the front and back electrodes.

FIG. 4 is a sectional view showing an electrode structure provided on four surfaces of three vibrating portions of the vibrating body 1. In the figure, (+) and (-) indicate the voltage polarity of each electrode at a certain moment, and the state of the electric field at that time is indicated by EX1 to EX6. These electric fields are generated by the electrodes 9, 10, 13, 14, 17, 18
And 9 ', 10', 13 ', 14', 17 ', 18'. Then, along the X axis, the left and right vibrating parts generate vibrations in the same direction, and the central vibrating part generates the vibration in the opposite direction.

FIG. 5 is a cross-sectional view showing an electrode structure divided and provided on the front and back surfaces of three vibrating portions of the vibrating body 1.
Electrodes 11, 12, 15, 16, 19, 20 and 11 ',
Electric fields EX7 to EX12 are generated through 12 ', 15', 16 ', 19', and 20 '. Due to these electric fields, Z
Along the axial direction, the left and right vibrating parts can generate vibrations in the same direction, and the central vibrating part can generate vibrations in the opposite direction.

[0029]

As described above, the vibration gyro sensor according to the present invention has the following significant effects. That is, since there is no need to attach a piezoelectric ceramic as in the conventional case, there is no variation in characteristics. Since it is made of single-crystal quartz, the resonance frequency of vibration due to temperature does not change. In addition, since it can be fixed at both ends, the angular velocity can be detected stably with respect to shock or vibration. Furthermore, since it can be manufactured using the photolithography technology, a small one can be mass-produced at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a cutting direction in which a vibrating body of a vibrating gyro sensor of the present invention is cut out from a rough quartz.

FIG. 2 is a perspective view of a vibration gyro sensor showing an embodiment of the present invention.

FIG. 3 is a diagram illustrating the principle of a vibration gyro sensor according to the present invention.

FIG. 4 is a cross-sectional view of an electrode structure of a vibration gyro sensor showing an embodiment of the present invention.

FIG. 5 is a sectional view of an electrode structure of a vibration gyro sensor according to an embodiment of the present invention.

FIG. 6 is a perspective view showing the principle of a conventional vibration gyro sensor.

FIG. 7 is a perspective view showing a conventional vibration gyro sensor.

[Description of Signs] 1, 28 vibrator 2, 3 rectangular hole of vibrator 4 left vibrator 5 central vibrator 6 right vibrator 7, 8 vibrator base 9, 10, 9 ', 10'13, 14 , 13'14'1
7, 18, 17 ′, 18 ′ Four-sided electrodes 11, 12, 11 ′, 12 ′, 15, 16, 15 ′, 1
6'19, 20, 19 ', 20' Front and back electrodes 21 Vibrating gyro sensor 22, 23, 24, 22 ', 23', 24 ', 25, 2
6, 27, 25 ', 26', 27 'Vibration direction 29, 30, 44, 45 Piezoelectric ceramic electrodes 31, 32, 33, 34 Vibration nodes 35, 36, 37, 38 Vibration displacement 39 Tuning fork vibrator 40 , 41, 42, 43 Tuning fork arm

Claims (5)

[Claims] 1. A vibrating gyro sensor for detecting an angular velocity voltage generated by giving an angular velocity to a vibrating body, wherein the vibrating body includes two rectangular holes parallel to each other and three vibrating parts parallel to each other. A vibration gyro sensor having a structure having 2. The vibrating body is formed of quartz and has a longitudinal direction,
The width direction and the thickness direction are the Y axis and the Z axis of the crystal axis, respectively.
2. The vibration gyro sensor according to claim 1, wherein the axis is an X axis. 3. The vibration direction of the three vibrating parts parallel to each other is such that two right and left vibrating parts are in the same direction, and one central vibrating part is in the opposite direction to the left and right vibrating parts. The vibration gyro sensor according to 1. 4. The vibrating gyro sensor according to claim 1, wherein an electrode for driving the vibrating body and an electrode for detecting the angular velocity are formed on each of the three vibrating parts. 5. An electrode formed on one vibrating portion is formed by being divided into two in the Y direction on two YZ planes, two YZ planes, and two YZ planes. The vibration gyro sensor according to claim 1, wherein