JPH1062176A - Piezoelectric vibrator and piezoelectric vibrating gyro using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator which is used suitably for a gyro and to provide a gyro which uses the piezoelectric vibrator, which is small and low-cost and whose accuracy is high. SOLUTION: In a ring-shaped piezoelectric vibrator 100, an electrode 2 is installed at the inside wall of a flat cylindrical piezoelectric body 1 having a through hole in the central part, and four electrodes in a prescribed width are installed at 90 deg. each on the outer circumference of the outer wall of a cylinder. The counter electrodes as one pair are used for driving electrodes 3a, 3b, and the electrodes as the other pair are used for detecting electrodes 4a, 4b. When AC voltages at the same phase are applied to the driving electrodes 3a, 3b from an AC power supply, the piezoelectric body 1 is vibrated, a rotation angular velocity is given to the piezoelectric body 1 in a state that the piezoelectric body is being vibrated, and Coriolis' force is generated in a direction at right angles to a direction in which the vibration is applied. A voltage which corresponds to the rotation angular velocity is generated in the piezoelectric body 1 due to Coriolis' force, the voltage is detected by the detecting electrodes 4a, 4b, and the angular velocity is found. In the ring-shaped piezoelectric vibrator 100, parts which are not vibrated most are situated in parts faced with the detecting electrodes 4a, 4b on the inner wall of the cylinder, and the electrodes are fixed in the parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of a piezoelectric vibrator, a piezoelectric vibratory gyroscope using the piezoelectric vibrator, and use of the piezoelectric vibratory gyroscope.

[0002]

2. Description of the Related Art In recent years, in the field of video cameras, a camera shake correction function has been introduced to low-cost machines. There are several methods of camera shake correction.Currently, camera shake is detected by an angular velocity sensor, and based on the detection result, a method of controlling the apex angle of a variable prism placed in front of an image pickup lens, an image pickup device The method of controlling the pixel cutout position of the CCD is mainly used. In any method, the angular velocity sensor is an indispensable device.

[0003] In the field of car navigation, a GPS using a satellite is used to further improve the position accuracy.
(Global Positioning System), in addition to detecting position information, detect the speed and angular velocity of the running car,
For example, even in an environment where reception from GPS satellites is not possible, such as in a tunnel or behind a building, a hybrid car navigation system that can obtain accurate position information has become widespread. In this case, an angular velocity sensor is an essential device. ing.

[0004] From the above, with the spread of these electronic devices, it has been required to reduce the size, weight and cost of the angular velocity sensor. Especially in video camera applications, the detection sensitivity and linearity for minute camera shake angular velocities, and in car navigation applications, stability, long-term reliability against environmental changes such as temperature, humidity, vibration, and external magnetic fields. Is required.

Under such circumstances, among the various angular velocity detection methods, a sound piece type piezoelectric vibrating gyroscope, which is relatively easy to reduce in size and cost, has come to be mainly used. The sound piece type piezoelectric vibrating gyroscope is roughly classified into two types. One is a plurality of sheet-like piezoelectric elements such as PZT adhered to a vibrating body such as an elinver, crystal, or PZT, and the other is a surface of a vibrating body such as a PZT. An electrode is directly formed on the substrate. In each case, the vibrating body is vibrated, the piezoelectric body is displaced by Coriolis force generated by the rotation of the vibrating body, and a voltage generated according to the magnitude of the displacement is detected. Each of the vibrators uses a rod-shaped one such as a triangular prism.

For example, FIG. 6 shows an example of a gyro using a vibrating body. FIG. 6A is a perspective view of the gyro, and FIG. 6B is a side view from the arrow A in FIG. FIG. The vibrating body 10 has a triangular prism shape, and the piezoelectric body 11 is in close contact with three side surfaces thereof. However, in order to increase the sensitivity of the gyro, the vibrating body 10 must be fixed so as not to suppress the vibration. Therefore, it is necessary to support at nodes (node points) of vibrations that do not theoretically vibrate. In other words, the support wire 12 is fixed to the support wire 12 at two support points 13 on the ridges which are nodes of the vibrator 10 by spot welding or the like, and the support wire 12 is fixed to the substrate 14 so that the vibrator 10 can vibrate freely. So hold.

However, the fixing method described above has a disadvantage that the fixing position must be determined strictly, and a high level of assembling technique is required, resulting in poor productivity. Further, this fixing method has a problem in reliability such as impact resistance.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to obtain a vibrating body having a shape suitable for use in a gyro, to simplify and firmly support the vibrating body, to achieve good production efficiency, and to reduce the size of the vibrating body. , To provide a low-cost gyro.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a flat cylindrical piezoelectric body having a ground electrode formed on all side surfaces of a cylindrical inner wall and a cylindrical outer wall. A piezoelectric vibrator is formed in which four electrodes having a predetermined width are formed every 90 degrees along the outer periphery of the cylinder, a pair of opposed electrodes are used as voltage application electrodes, and the other pair of opposed electrodes are voltage detection electrodes. I do.

[0010] Further, means for applying the AC voltage of a predetermined frequency to at least the pair of voltage applying electrodes while fixing the piezoelectric vibrator in a state capable of freely vibrating and fixing the piezoelectric vibrator to a fixed member; Means for processing output signals of another pair of voltage detection electrodes to constitute a piezoelectric vibrating gyroscope. For fixing the piezoelectric vibrator to the fixing member, a predetermined portion of a ground electrode provided on the inner wall of the cylinder of the piezoelectric vibrator is fixed to a fixing portion of the fixing member.

The two piezoelectric vibrating gyroscopes described above are integrally formed by arranging the angular velocity detecting axes at right angles to each other to form a two-axis piezoelectric vibrating gyroscope. Further, a three-axis piezoelectric vibrating gyro is formed by integrally arranging the above-mentioned three piezoelectric vibrating gyros with their angular velocity detecting axes arranged at right angles to each other.

Further, a hand touch correction mechanism is constructed using the above-described piezoelectric vibrating gyroscope, and a video camera is manufactured using the hand touch correction mechanism. Further, a car navigation device is configured using the above-described piezoelectric vibrating gyroscope.

According to the present invention, a flat cylindrical piezoelectric vibrator that vibrates in the radial direction can be firmly and reliably supported, and therefore has a high production efficiency, a small size and a low price gyro. Can be configured. In addition, an integrated gyro that detects angular velocity in two-axis or three-axis directions can be easily manufactured. Further, by using this gyro for a camera shake correction device, a car navigation device, or the like, a small, inexpensive gyro can be manufactured. A highly reliable device can be configured.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has proposed a flat, cylindrical (hereinafter simply referred to as "ring") piezoelectric vibrator which vibrates in the radial direction. It has been found that it is highly productive at a low price, and it is easy to integrate it into two or three axes. That is, the present invention
When rotating a vibrating object, a ring-shaped piezoelectric vibrator that vibrates in the radial direction is used in a piezoelectric vibrating gyroscope that is an angular velocity sensor that utilizes the phenomenon that Coriolis force is generated in a direction perpendicular to the vibration direction. By using
The present invention relates to a piezoelectric vibrating gyroscope characterized in that support of a vibrator can be simplified, miniaturization is easy, and productivity is high.

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a vibrator formed of a ring-shaped piezoelectric body (hereinafter, simply referred to as “ring-shaped piezoelectric vibrator”) according to the present invention, and FIG. 2 shows a vibration pattern of the ring-shaped piezoelectric vibrator. FIG. FIG.
FIG. 3 is a diagram showing a circuit configuration example of a gyro using the ring-shaped piezoelectric vibrator. 4A and 4B show a method of supporting the ring-shaped piezoelectric vibrator, wherein FIG. 4A is a perspective view and FIG. 4B is a sectional view. FIG. 5 shows a configuration example of a gyro in which a plurality of ring-shaped piezoelectric vibrators of the present invention are integrated.

As shown in FIG. 1, the ring-shaped piezoelectric vibrator 100 of the present invention has a flat cylindrical piezoelectric body 1 having a hole penetrating in the center, a ground electrode 2 on the inner wall, and a ground electrode 2. Four electrodes having a predetermined width are provided at every 90 degrees on the outer periphery of the cylindrical outer wall. The pair of electrodes facing each other is referred to as drive electrodes 3a and 3b, and the other pair is referred to as detection electrodes 4a and 4b.

The ring-shaped piezoelectric vibrator 100 is manufactured by PZ
A raw material powder of a piezoelectric material such as T is kneaded with a predetermined composition, pressed into a ring, and sintered at 1200 to 1300 ° C. Thereafter, a conductive paste such as silver is baked, electrodes are formed by plating, sputtering, vapor deposition, or the like, and thereafter, polarization is performed to have a piezoelectric effect. Figure 1
Is performed by applying a voltage between the ground electrode 2 and the drive electrodes 3a, 3b and the detection electrodes 4a, 4b in the direction indicated by the arrow. The drive electrodes 3a and 3b are electrodes that apply vibration to the piezoelectric body 1, and the detection electrodes 4a and 4b are electrodes that detect Coriolis force generated when the piezoelectric body 1 rotates. The vibration mode of the piezoelectric body 1 is as shown in FIG.

Next, the operation of the ring-shaped piezoelectric vibrator 100 will be described with reference to FIG. First, the drive electrodes 3a,
When an in-phase AC voltage is applied from AC power supply 5 to 3b,
Electro-mechanical conversion is performed by the piezoelectric effect, and the vibration shown in FIG. 2 is generated. When a rotational angular velocity is given to the ring-shaped piezoelectric vibrator 100, a Coriolis force is generated in a direction perpendicular to the vibration applying direction, and a voltage corresponding to the rotational angular velocity is generated in the piezoelectric element 1 by the Coriolis force. This voltage is detected to determine the angular velocity.

The voltage due to this Coriolis force is applied to the detection electrode 4a.
Since the detection electrode 4b and the detection electrode 4b have opposite phases, by connecting each detection output to two input terminals of an operational amplifier (differential amplifier) 6, a double detection voltage can be obtained. Further, when a voltage is applied to the drive electrodes 3a and 3b, vibrations in the directions of the detection electrodes 4a and 4b also occur. However, the voltages in the directions of the detection electrodes 4a and 4b generated by the vibration are canceled by the operational amplifier 6, so that the error is small. Angular velocity can be detected.

Next, a method of fixing the ring-shaped piezoelectric vibrator 100 will be described with reference to FIG. Since the sensitivity of the vibrating gyroscope greatly depends on the magnitude of the vibration, the vibrator must be supported by a method that does not suppress the vibration. As described above, in the case of a conventional resonator element such as a triangular prism, the vibrator must be supported at the node point. The ring-shaped piezoelectric vibrator 100 can be supported by abutting the mounting portion 8 of the fixing member 7 and fixing it by soldering or the like at a portion facing the electrodes 4a and 4b. .

As described above, the support can be performed without using the conventionally used spot welding, and the welding can be performed reliably and firmly. Therefore, the ring-shaped piezoelectric vibrator 100 of the present invention
The configuration of a gyro in which a plurality of gyros are integrated is also facilitated. FIG.
Is an example thereof. The fixing member 7a having the X-axis mounting portion 8x, the Y-axis mounting portion 8y, and the Z-axis mounting portion 8z corresponding to the X-axis, the Y-axis, and the Z-axis, Correspondingly, the X-axis ring-shaped piezoelectric vibrator 100x, the Y-axis ring-shaped piezoelectric vibrator 100y, and the Z-axis ring-shaped piezoelectric vibrator 1
By fixing 00z, a three-axis integrated gyro can be easily configured. It should be noted that a two-shaft integrated gyro can be formed by excluding one shaft configuration from the above.

Further, it is possible to constitute a camera shake correction device using a piezoelectric vibrating gyroscope having the above-described characteristics, and to use the video camera to perform the camera shake correction effectively. Further, by using the piezoelectric vibrating gyroscope for car navigation, a small, inexpensive and highly reliable device can be constructed.

[0023]

As described above, according to the present invention,
The ring-shaped piezoelectric vibrator that vibrates in the radial direction can easily and firmly support the piezoelectric vibrator, and by using this, it is possible to construct a small, low-cost gyro with good production efficiency. It becomes possible. Further, in order to detect angular velocities in biaxial or triaxial directions, the piezoelectric vibrators are provided in the respective axial directions, so that a gyro having an integrated structure can be easily manufactured.

Further, by using the piezoelectric vibrating gyroscope of the present invention for a camera shake correction device, a car navigation device, and the like, a highly accurate and reliable device can be constructed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a ring-shaped piezoelectric vibrator according to the present invention.

FIG. 2 is a diagram showing a vibration pattern of a ring-shaped piezoelectric vibrator.

FIG. 3 is a diagram showing a circuit configuration example of a gyro using the ring-shaped piezoelectric vibrator according to the present invention.

FIG. 4 shows a method of supporting a ring-shaped piezoelectric vibrator,
(A) is a perspective view thereof, and (b) is a sectional view thereof.

FIG. 5 is a configuration example of a gyro in which a plurality of ring-shaped piezoelectric vibrators of the present invention are integrated.

FIG. 6 is an example of a conventional piezoelectric vibrating gyroscope,
(A) is a perspective view thereof, and (b) is a side view taken along arrow A of (a).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric body, 2 ... Ground electrode, 3a, 3b ... Drive electrode, 4
a, 4b: detection electrodes, 5: AC power supply, 6: operational amplifier,
7, 7a: fixing member, 8: mounting portion, 8x: mounting portion for X axis, 8y: mounting portion for Y axis, 8z: mounting portion for Z axis,
10: vibrating body, 11: piezoelectric body, 12: supporting wire, 13
... supporting point, 14 ... substrate, 100 ... ring-shaped piezoelectric vibrator,
100x ... X-axis ring-shaped piezoelectric vibrator, 100y ... Y-axis ring-shaped piezoelectric vibrator, 100z ... Z-axis ring-shaped piezoelectric vibrator

Claims (8)

[Claims] 1. A flat cylindrical piezoelectric body, wherein a ground electrode is formed on all side surfaces of an inner wall of a cylinder, and four electrodes having a predetermined width are provided on the outer wall of the cylinder every 90 degrees along the outer periphery of the cylinder. A piezoelectric vibrator, wherein a pair of opposing electrodes is formed as a voltage application electrode, and the other pair of opposing electrodes is a voltage detection electrode. 2. The piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrator is allowed to vibrate freely and is fixed to a fixing member, and at least an AC voltage having a predetermined frequency is applied to the pair of voltage applying electrodes. A piezoelectric vibrating gyroscope comprising: means for applying; and means for processing output signals of another pair of voltage detecting electrodes. 3. The fixing of the piezoelectric vibrator to a fixing member,
The piezoelectric vibratory gyroscope according to claim 2, wherein the predetermined portion of the ground electrode provided on the inner wall of the cylinder of the piezoelectric vibrator is fixed to a mounting portion of a fixing member. 4. A two-axis piezoelectric vibratory gyroscope, wherein the two piezoelectric vibratory gyroscopes according to claim 2 are integrally formed by arranging their angular velocity detection axes at right angles to each other. 5. A three-axis piezoelectric vibrating gyroscope according to claim 2, wherein said three piezoelectric vibrating gyroscopes are arranged integrally with their angular velocity detecting axes arranged at right angles to each other. 6. A hand correction mechanism comprising the piezoelectric vibrating gyroscope according to claim 2. Description: 7. A video camera comprising the hand correction mechanism according to claim 6. 8. The method of claim 2 or claim 4 or claim 5.
A car navigation device using the piezoelectric vibrating gyroscope according to the above item.