JP3819339B2 - Columnar vibrator for piezoelectric vibration gyro - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a columnar vibrator for a piezoelectric vibration gyro, in particular, a gyroscope used for a navigation system of an automobile, attitude control, a camera shake prevention device for a camera body type VTR, and the like.
[0002]
[Prior art]
A piezoelectric vibration gyro is an angular velocity sensor that utilizes a dynamic phenomenon in which when an angular velocity is applied to an object having velocity, a Coriolis force is generated in the object itself in a direction perpendicular to the velocity direction.
[0003]
Mechanical vibration (drive vibration) can be excited by applying an electrical signal, and the magnitude of mechanical vibration (detection vibration) in the direction orthogonal to the drive vibration can be detected electrically. When the angular velocity about the axis parallel to the line where the drive vibration surface and the detection vibration surface intersect is given with the drive vibration excited in advance, the detection vibration is caused by the action of the Coriolis force described above. Generated and detected as an output voltage. Since the detected output voltage is proportional to the magnitude and angular velocity of the drive vibration, the magnitude of the angular velocity can be obtained from the magnitude of the output voltage when the magnitude of the drive vibration is constant.
[0004]
Various types of vibrators have been proposed for vibratory gyro vibrators, but columnar sound piece vibrators made of piezoelectric materials are simple in shape and are often used for small and inexpensive vibratory gyros. ing.
[0005]
FIG. 4 is a sectional view showing a conventional columnar vibrator for a vibrating gyroscope. Here, FIG. 4 is described in JP-A-9-126785. In FIG. 2, in the bimorph columnar vibrator composed of the piezoelectric substrates 21 and 22 on which the electrodes 23, 24, 25, and 27 are formed, a protrusion 34 provided on the support member 31 causes a gap between the support member 31 and the electrode 23. A technique for reducing temperature drift by providing a gap and soldering with solder 35 around the protrusion 34 and then fixing the gap with an elastic adhesive 32 to prevent leakage of bending vibration of the bimorph columnar vibrator to the outside. Is disclosed.
[0006]
[Problems to be solved by the invention]
However, the conventional columnar vibrator shown in FIG. 4 requires fine processing of the protrusions 34, and in addition to the connection of solder or the like, a joining process using an elastic adhesive 32 is newly added, which increases productivity. It had problems such as adverse effects. Incidentally, it is known that the temperature drift of the vibrating gyroscope is due to the temperature dependence of the mechanical quality factor Qm and the resonance frequency fr in the bending vibration mode of the vibrator. Therefore, in order to reduce the temperature drift, there is a method of improving the temperature characteristics of the columnar vibrator itself in addition to devising the structure of the vibrating gyroscope.
[0007]
However, while the piezoelectric material such as PZT has an advantage of high electromechanical conversion efficiency, it has a disadvantage that the temperature dependency of Qm and fr is larger than that of a piezoelectric material made of a single crystal such as quartz. It was. In addition, some piezoelectric materials such as PZT type have less temperature dependence depending on the composition, but there are no outstanding ones if both Qm and fr have less temperature dependence.
[0008]
An object of the present invention is to provide a columnar vibrator for a piezoelectric vibration gyro that can reduce temperature drift without increasing the number of components and without impairing productivity by improving the temperature characteristics of the columnar vibrator itself. There is.
[0009]
[Means for Solving the Problems]
The piezoelectric vibrating gyro columnar vibrator of the present invention, the first piezoelectric substrate and the second piezoelectric substrate on which the electrode on the front and back surface is polarized in the thickness direction is formed, superimposed in the direction in which the polarization direction is reversed with each other A columnar vibrator for a piezoelectric vibration gyro in which the electrodes on the unbonded side of the first piezoelectric substrate are divided into two parallel to the longitudinal direction of the first piezoelectric substrate. A columnar vibrator for a piezoelectric vibration gyro made of a piezoelectric material having a composition different from that of the second piezoelectric substrate is used .
[0010]
Further, in the columnar vibrator for piezoelectric vibration gyro of the present invention, the mechanical quality factor Qm in the bending vibration mode of the first piezoelectric substrate and the mechanical quality factor Qm of the second piezoelectric substrate are temperature dependent. different sex, but the on one piezoelectric substrate is lower than 25 ° C. temperature Qm takes the peak, the other piezoelectric substrate with a columnar vibrator piezoelectric vibrating gyro taking peak the Qm at a temperature higher than 25 ° C. is there.
[0011]
In the columnar vibrator for piezoelectric vibration gyro according to the present invention, the resonance frequency fr ₁ in the bending vibration mode of the _first piezoelectric substrate and the resonance frequency fr ₂ of the second piezoelectric substrate are different in temperature dependency. those one piezoelectric substrate resonance frequency fr ₁ at temperatures below 25 ° C. temperature takes a peak, the other piezoelectric substrate with a columnar vibrator piezoelectric vibrating gyro take resonance frequency fr ₂ peaks at temperatures higher than 25 ° C. It is.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A columnar vibrator for a piezoelectric vibration gyro according to an embodiment of the present invention will be described below.
[0013]
FIG. 1 is a cross-sectional view of a columnar vibrator for a piezoelectric vibration gyro according to an embodiment of the present invention. The columnar vibrator for piezoelectric vibration gyro of the present invention reverses the polarization direction of the piezoelectric substrate 1 and the piezoelectric substrate 2 made of piezoelectric materials having different compositions polarized in the thickness direction as indicated by arrows in the figure. In this case, the electrodes 4 and 5 are provided on the surface of the piezoelectric substrate 1, and the drive electrode 3 is provided on the surface of the piezoelectric substrate 2.
[0014]
Incidentally, the polarizable electrode 7 on the joint surface with the piezoelectric substrates 1 and 2 is provided for performing a polarization process, and is not necessary for the function as a vibrator. Drive vibration can be excited by applying an AC voltage between the drive electrode 3 and the detection electrodes 4 and 5, and for the detection vibration in the direction orthogonal thereto, the difference between the voltages generated at the detection electrodes 4 and 5 is measured. Can be detected, and functions as a columnar vibrator for a piezoelectric vibration gyro.
[0015]
2 and 3 show temperature characteristics of the bimorph columnar vibrator. The change curve 11 shows the temperature dependence of the mechanical quality factor Qm and the resonance frequency fr in the bending vibration mode of the bimorph columnar vibrator in which the piezoelectric substrate 2 made of the piezoelectric material A is bonded to the piezoelectric substrate 1 made of the piezoelectric material A. Is. The change curve 12 is for a bimorph columnar vibrator in which a piezoelectric substrate 2 made of the piezoelectric material B is joined to the piezoelectric substrate 1 made of the piezoelectric material B. The change curve 13 is a characteristic of the bimorph columnar vibrator of the present embodiment in which the piezoelectric substrate 1 made of the piezoelectric material A and the piezoelectric substrate 2 made of the piezoelectric material B are joined.
[0016]
As shown in FIGS. 2 and 3, the bimorph columnar vibrator using the single material of the piezoelectric material A has a low temperature dependence of fr, a Qm peak temperature lower than 25 ° C., and a temperature dependence of Qm. large. On the other hand, a bimorph columnar vibrator using a single material of the piezoelectric material B has a large temperature dependence of fr, a peak temperature of Qm higher than 25 ° C., and a small temperature dependence of Qm. On the other hand, in the bimorph columnar vibrator in which the piezoelectric materials A and B are combined, the difference in peak temperatures flattens the temperature dependence curve, and the temperature dependence of Qm is so small that it cannot be obtained with a single material. , Fr is also less temperature dependent than that of the bimorph columnar vibrator using a single material of the piezoelectric material A.
[0017]
In the present embodiment, the case where the piezoelectric materials having different temperatures at which the peak of Qm is different has been described, but the same result is obtained when the piezoelectric materials having different temperatures at which the peak of fr is combined. According to the present invention, the temperature dependence of fr can also be greatly reduced.
[0018]
Since the temperature drift of the vibration gyro depends on the characteristic change accompanying the temperature change of Qm and fr in the flexural vibration mode of the vibrator, the columnar vibrator of the present invention having little temperature dependency of Qm and fr is used for the piezoelectric vibration gyro. It is suitable as a columnar vibrator.
[0019]
【The invention's effect】
According to the columnar vibrator for piezoelectric vibration gyroscope of the present invention, the temperature dependence of both Qm and fr can be reduced at the same time, and the piezoelectric element can reduce temperature drift without increasing the number of components and without impairing productivity. A columnar vibrator for a vibrating gyroscope can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a columnar vibrator for a piezoelectric vibration gyro according to an embodiment of the present invention.
FIG. 2 is a view showing the temperature dependence of Qm of a columnar vibrator for piezoelectric vibration gyro according to the present invention.
FIG. 3 is a view showing the temperature dependence of fr of a columnar vibrator for a piezoelectric vibration gyro according to the present invention.
FIG. 4 is a sectional view showing a conventional columnar vibrator for a vibrating gyroscope.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 Piezoelectric substrate 3 Drive electrode 4, 5 Detection electrode 7 Polarization electrode 11 Change curve 12 (of piezoelectric material A) Change curve 13 (of piezoelectric material B) Change curve 21 (composite of piezoelectric material AB) 21, 22 Piezoelectric substrate 23 Common electrode 24, 25 Drive / detection electrode 27 Electrode 31 Support member 32 Elastic adhesive 34 Projection 35 Solder

Claims (3)

The first piezoelectric substrate and the second piezoelectric substrate having electrodes formed on the front and back surfaces and polarized in the thickness direction are overlapped and bonded to each other so that the polarization directions are reversed, and the first piezoelectric substrate is bonded. In the columnar vibrator for piezoelectric vibration gyro, in which the non-side electrode is divided into two parallel to the longitudinal direction of the first piezoelectric substrate, the first piezoelectric substrate and the second piezoelectric substrate are made of piezoelectric materials having different compositions. comprising a columnar vibrator piezoelectric vibrating gyroscope, and mechanical quality factor Qm in the bending vibration mode of the first piezoelectric substrate, wherein a second piezoelectric substrate mechanical quality factor Qm, different temperature dependence The columnar vibrator for a piezoelectric vibration gyro, wherein one piezoelectric substrate has the peak Qm at a temperature lower than 25 ° C., and the other piezoelectric substrate has the peak Qm at a temperature higher than 25 ° C. The first piezoelectric substrate and the second piezoelectric substrate having electrodes formed on the front and back surfaces and polarized in the thickness direction are overlapped and bonded to each other so that the polarization directions are reversed, and the first piezoelectric substrate is bonded. In the columnar vibrator for piezoelectric vibration gyro, in which the non-side electrode is divided into two parallel to the longitudinal direction of the first piezoelectric substrate, the first piezoelectric substrate and the second piezoelectric substrate are made of piezoelectric materials having different compositions. a piezoelectric vibrating gyroscope for columnar vibrator and a resonance frequency fr ₁ in the bending vibration mode of the first piezoelectric substrate, the second and the resonant frequency fr ₂ of the piezoelectric substrate, different temperature dependence, the one the piezoelectric substrate takes the resonance frequency fr ₁ peak at a temperature lower than 25 ° C., the other piezoelectric substrate columnar vibrating piezoelectric vibrating gyro, characterized by taking the resonant frequency fr ₂ peaks at temperatures higher than 25 ° C. . The resonance frequency fr ₁ in the bending vibration mode of the first piezoelectric substrate according to claim 1 Symbol mounting piezoelectric vibrating gyro columnar vibrator, the second and the resonant frequency fr ₂ of the piezoelectric substrate, different temperature dependence One piezoelectric substrate has a resonance frequency fr ₁ having a peak at a temperature lower than 25 ° C., and the other piezoelectric substrate has a resonance frequency fr ₂ having a peak at a temperature higher than 25 ° C. Vibrator.

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