JPH0642972A - Piezoelectric oscillation gyro and adjusting method of resonance frequency of piezoelectric oscillation gyro - Google Patents

Abstract

PURPOSE:To easily achieve the coincidence of resonance frequencies coincide without exerting an adverse effect on the characteristic of a gyro by a method wherein a groove is formed on the surface of a piezoelectric ceramic body which has been exposed in at least one non-electrode part out of belt-shaped electrodes. CONSTITUTION:Belt-shaped electrodes 11 to 16 are formed in parallel with the axial direction on the outer circumferential face of a piezoelectric ceramic body, and non- electrode parts are formed in their central parts. When the belt-shaped electrodes 11, 13, 15 are used as common grounding electrodes and the belt-shaped electrodes 12, 14, 16 are driven, resonance frequencies are designated as fr1, fr2, fr3. When the resonance frequency fr1 is changed and made to coincide with the resonance frequencies fr2, fr3, a groove is formed in a non-electrode part in the electrode 12 which has a direct relationship to a change in the resonance frequency fr1 and, thereby, only the resonance frequency fr1 is reduced. In the same manner, in order to change only the resonance frequency fr2, a groove is formed in the electrode 14 which has a direct relationship to a change in the resonance frequency fr2 and, thereby, only the resonance frequency fr2 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave of a piezoelectric vibrator, especially in a gyroscope used for posture control of a moving body such as a ship or an automobile and equipment mounted on the moving body and a navigation system of the automobile. A piezoelectric vibrating gyro using vibration.

[0002]

2. Description of the Related Art A vibrating gyroscope is a gyroscope which utilizes a mechanical phenomenon in which a Coriolis force is generated in a direction perpendicular to a vibrating direction when a rotating angular velocity is applied to a vibrating body. Generally, in a composite vibration system configured to excite and detect vibrations in two different directions that are orthogonal to each other, when one of the vibrations is excited and the oscillator is rotated, the action of the Coriolis force described above causes the vibration perpendicular to this vibration. A force acts in the direction, and the other vibration is excited. Since the magnitude of this vibration is proportional to the magnitude of the vibration on the input side and the rotational angular velocity, the magnitude of the rotational angular velocity is changed from the magnitude of the output voltage proportional to the magnitude of this vibration when the input voltage is constant. You can ask.

FIG. 5 is a perspective view showing a structural example of a piezoelectric vibrator 8 used in a piezoelectric vibrating gyro according to Japanese Patent Application No. 2-335987. The piezoelectric vibrator 8 is provided in parallel with the length direction of the piezoelectric ceramic cylinder 9 at a position on the outer peripheral surface of the piezoelectric ceramic cylinder 9 that equally divides the circumference, and the length thereof is the axial length of the piezoelectric ceramic cylinder 9. About 70% of the strip electrode 10. The strip electrode 10 can be easily obtained by directly forming by curved screen printing or by removing unnecessary portions of the electrode formed on the entire surface by plating or the like by photoetching.

The operation of the conventional piezoelectric vibrating gyro will be described below with reference to FIG. 6 when the number of the strip electrodes 10 is six. 6 on the piezoelectric ceramic cylinder 9 (see FIG. 5)
When the individual strip electrodes 11, 12, 13, 14, 15 and 16 are formed, every other strip electrode 11, 1
3 and 15 and 12, 14 and 16 are electrically connected to each other and 2
Polarization is applied to the terminals. The direction of polarization in the cross-sectional direction of the cylinder at this time is as indicated by the dashed arrow.

FIG. 7 is an explanatory diagram of the operating principle of a conventional piezoelectric vibrator. In FIG. 7, the gaps between the strip electrodes are G1, G2, G3, G4, G5 and G6, respectively.
Now, the strip electrodes 11 and 13 sandwiching the strip electrode 12 are connected to form a common ground, and the state of strain and the vibration direction generated in the cross-sectional direction of the piezoelectric ceramic cylinder 9 when an AC voltage is applied to the strip electrode 12 are shown. ing. Gap G1 and G
When the polarities of the applied electric fields are made to be the same with respect to the respective polarization directions of the two parts and an AC voltage for excitation having a frequency substantially equal to the co-frequency of the bending vibration mode of the piezoelectric ceramic cylinder 9 is applied, the piezoelectric ceramic cylinder As indicated by solid arrows in FIG. 9, vibration driving forces are generated in the same direction in the directions of the planes including the center lines of the gaps G1 and G2 and the center axis of the cylinder, and these are combined to form the piezoelectric ceramic cylinder 9 Flexurally vibrates in the direction of the plane including the center line of the strip electrode 12 and the center axis of the cylinder (direction R1). In FIG. 7, the piezoelectric ceramic cylinder 9 is moved to the arrow R by another driving source.
When vibrating in the direction of 1, an output voltage is generated in the strip electrode 12 due to the piezoelectric effect.

FIG. 8 shows a state of strain and a vibration direction generated in the cross-sectional direction of the piezoelectric ceramic cylinder 9 when the strip electrodes 11, 13 and 15 are connected and an alternating voltage of opposite polarity is applied to the strip electrodes 14 and 16. It is shown. As shown in FIG. 8, a vibration driving force in the direction of the plane including the center line of the strip electrode 14 and the center axis of the cylinder (the direction of the solid arrow), and the plane including the center line of the strip electrode 16 and the center axis of the cylinder. Is generated (the direction indicated by the solid line arrow), and these are combined so that the piezoelectric ceramic cylinder 9 is substantially perpendicular to the direction of the surface including the center line of the strip electrode 12 and the center axis of the cylinder (R2). Bending vibration in the direction). In FIG. 8, when the piezoelectric ceramic cylinder 9 is vibrating in the direction of arrow R2 by another drive source,
Due to the piezoelectric effect, voltages of opposite phases are generated in the strip electrodes 14 and 16.

FIG. 9 is an explanatory view of the operating principle of a piezoelectric vibrating gyro configured by using the piezoelectric ceramic cylinder 9 having the above six strip electrodes. In FIG. 9, the strip electrodes 11, 13 and 15 are connected to be a common ground, and an excitation AC voltage is applied to the strip electrode 12. At this time, the frequency of the applied voltage substantially matches the resonance frequency of the bending mode of the piezoelectric ceramic cylinder 9. At this time, the vibration direction of the piezoelectric ceramic cylinder 9 is substantially the direction of the plane including the center line of the strip electrode 12 and the central axis of the piezoelectric ceramic cylinder 9 (R3 direction).

In FIG. 9, when the piezoelectric ceramic cylinder 9 is rotated about the axis of the cylinder, a Coriolis force is generated in a direction perpendicular to the vibration direction, and the piezoelectric ceramic cylinder 9 is rotated.
Vibrate in a direction perpendicular to the direction of the plane including the center line of the strip electrode 12 and the center axis of the piezoelectric ceramic cylinder 9 (R3 direction). Therefore, as described with reference to FIGS. 7 and 8, the strip electrodes 14 and 16 have the same amplitude due to the vibration in the direction of the plane including the center line of the strip electrode 12 and the center axis of the piezoelectric ceramic cylinder 9 (R3 direction). , A voltage in which the same phase voltage and a voltage of the same amplitude and opposite phase due to vibration in the direction perpendicular to the same phase are generated. Therefore, when the strip electrodes 14 and 16 are respectively connected to the input terminals of the differential amplifier 20, the output of the differential amplifier 20 becomes a voltage associated with the vibration component generated by the Coriolis force, and becomes a voltage proportional to the applied rotational angular velocity. .

In the piezoelectric vibrating gyro shown in FIGS. 8 and 9, the strip electrodes 11, 13 and 15 serve as a common ground terminal, and the strip electrodes 12 used as input / output terminals.
It is desirable that the values of the resonance frequencies fr1, fr2, and fr3 when driven from the respective terminals of 14 and 16 match as much as possible.

[0010]

In the conventional piezoelectric vibrating gyroscope described above, bending vibration occurs in the direction of the plane including the center line of the strip electrode used as the drive terminal and the central axis of the piezoelectric ceramic cylinder. In order to adjust the resonance frequency of the flexural vibration in the direction, at least one of the strip electrode used as the drive terminal and the strip electrode (which is the ground electrode) symmetrical to the strip electrode and the central axis of the piezoelectric ceramic cylinder It is necessary to mechanically scrape the central part of one of the strip electrodes. However, when the strip electrode itself is shaved, the electrode area changes, which adversely affects the gyro characteristics in which the capacitance value has changed, so that the central portion of the strip electrode cannot be mechanically shaved.

An object of the present invention is to provide a piezoelectric vibrating gyro which can easily match the resonance frequencies fr1, fr2 and fr3 without adversely affecting the gyro characteristics.

[0012]

According to the present invention, a cylindrical or cylindrical piezoelectric ceramic body and a plurality of strip-shaped electrodes provided on the outer peripheral surface of the piezoelectric ceramic body in parallel to the axial direction are provided. In the piezoelectric vibrating gyro that performs polarization and driving / detection using the strip-shaped electrode, a piezoelectric vibrating gyro is obtained in which the strip-shaped electrode has an electrodeless portion in the central portion.

Further, according to the present invention, there is obtained a piezoelectric vibrating gyro characterized in that a groove is formed on the surface of the piezoelectric ceramic body exposed in at least one electrodeless portion of the strip electrode. .

Further, according to the present invention, there is provided a piezoelectric vibrating gyro characterized in that at least one groove is formed on the surface of the piezoelectric ceramic body exposed in the gap between the plurality of strip electrodes. can get.

According to the present invention, a plurality of strip electrodes are provided on the outer peripheral surface of a cylindrical or cylindrical piezoelectric ceramic body in parallel to the axial direction to form a piezoelectric vibrator, and the plurality of strip electrodes are formed. At least one groove is formed on the surface of the piezoelectric ceramic body exposed in the gap between the electrodes, and the strip-shaped electrode is perpendicular to the direction connecting the groove and the center of the cross section of the piezoelectric ceramic body. There is provided a method of adjusting the resonance frequency of a piezoelectric vibrating gyro, which is characterized in that the resonance frequency seen from the above is kept constant and the resonance frequencies seen from the other strip electrodes are reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a plan view showing the structure of a strip electrode 10 (see FIG. 5) of a piezoelectric vibrating gyroscope of the present invention. On the outer peripheral surface of the cylindrical or cylindrical piezoelectric ceramic body 1, a plurality of strip electrodes 2 are formed as in the conventional case. That is, these strip electrodes 2 are formed on the outer peripheral surface of the piezoelectric ceramic body 1 in parallel with the axial direction and at the center of the length direction of the piezoelectric ceramic body 1. An electrodeless portion 3 is formed in the central portion of these strip electrodes 2, and a groove is provided in the electrodeless portion 3.

FIG. 2 shows changes in each resonance frequency according to changes in the length of the groove provided in the electrodeless portion when the groove is formed in the electrodeless portion of the strip electrode 12 shown in FIG. It is a graph. The resonance frequencies fr1, fr2, and fr3 are the resonance frequencies when the strip electrodes 11, 13, and 15 are used as the common ground electrode and are driven from the strip electrodes 12, 14 and 16, respectively, as described above.

As can be seen from FIG. 2, in the case where an electrodeless portion is formed on the strip electrode 12, a groove is provided in the electrodeless portion, and the axial length of the groove is gradually increased, that is, the groove length is increased. When the axial length is changed in the range of 0 mm to 3 mm, the value of the resonance frequency fr1 decreases most greatly, and the resonance frequencies fr2, f
The amount of change in r3 is very small. This is because the piezoelectric vibrator 8 (see FIG. 5) has a columnar shape, and the six strip electrodes are formed on the outer peripheral surface of the columnar cylinder at substantially equal intervals. The same characteristics as described above are exhibited when the electrodeless portions are formed on the strip electrodes 12 and 14. That is, the resonance frequency fr
When 1 is changed to match the resonance frequencies fr2 and fr3, the electrode 1 having a direct relationship with the change of the resonance frequency fr1
By forming a groove in the second electrodeless portion, only the resonance frequency fr1 is reduced. Similarly, when it is desired to change only the resonance frequency fr2, only the resonance frequency fr2 is reduced by forming a groove in the electrodeless portion of the electrode 14 which is directly related to the change in the resonance frequency fr2.

Further, by providing the strip-shaped electrode 14 and the strip-shaped electrode 16 with an electrodeless portion, forming a groove in the electrodeless portion, and adjusting the length of the groove, respectively, only the resonance frequencies fr2 and fr3 are independently set. It can also be adjusted in a decreasing direction.

Next, a second embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to. FIG. 3 is a sectional view of a piezoelectric vibrator showing another embodiment of the present invention. Strip electrodes 12, 14, 16
Is an electrode for driving or detecting, and the arrows 31, 3
Reference numerals 2 and 33 indicate the vibration directions of the piezoelectric ceramic cylinder when driven from the strip electrodes 12, 14 and 16, respectively.

Grooves 41 are formed in the non-electrode portion between the strip electrodes 11 and 12, the non-electrode portion between the strip electrodes 11 and 16 and the non-electrode portion between the strip electrodes 16 and 15, respectively. , Groove 42, and groove 43 are formed.

FIG. 4 is a graph showing changes in resonance frequency in another embodiment of the present invention. Resonance frequency fr11
Is the resonance frequency in the bending vibration direction (arrow 31) of the piezoelectric vibrator generated when driven from the strip electrode 16, and the resonance frequency fr12 is the bending vibration direction of the piezoelectric vibrator generated when driven from the strip electrode 12 ( The resonance frequency is indicated by the arrow 32), and the resonance frequency fr13 is the resonance frequency in the bending vibration direction (arrow 33) of the piezoelectric vibrator that is generated when driven from the strip electrode 14.

Resonance frequency f with no grooves formed
The values (initial values) of r11, fr12, and fr13 are measured, and this is referred to as measurement 1. Next, the resonance frequency fr1 when the groove 41 is formed between the strip electrodes 11 and 12
1, the value of fr12 and fr13 is measured, and this is measured 2
And

Before the measurement, the initial value of the resonance frequency fr11 and the initial value of the resonance frequency fr12 are different from each other. Here, when the groove 41 is formed between the strip electrodes 11 and 12, The resonance frequency fr11 seen from the strip electrode 16 provided in the direction (arrow 31) perpendicular to the direction connecting the center of the cross section of the piezoelectric ceramics body is kept constant, and the strip electrode 1 as the other drive electrode.
The resonance frequencies fr12 and fr13 seen from 2 and 14 decrease. Therefore, as shown in FIG. 4, the resonance frequency fr11
Of the resonance frequencies fr12 and fr
13 decreases, and as a result, the value of the resonance frequency fr13 is f
It matches the value of r11. Here, the resonance frequency fr12 is reduced by substantially the same amount as the reduction amount of the resonance frequency fr13. This is because the components of the resonance frequencies fr12 and fr13 in the direction connecting the groove 41 and the center of the cross section of the piezoelectric ceramic body are the same.

Next, the resonance frequencies fr11 and fr12 when the groove 42 is formed between the strip electrodes 11 and 16 are formed.
And the value of fr13 are measured, and this is referred to as measurement 3. In this case, the resonance frequency fr12 hardly changes, and the resonance frequencies fr11 and fr13 decrease by substantially the same amount, respectively, as a result of the same principle as the resonance frequency change of the measurement 1 described above. As a result, the resonance frequencies fr11 and fr13 are The value matches the value of fr12. That is, by forming the groove 41 in one place of the electrodeless portion of the piezoelectric vibrator, two resonance frequencies,
That is, the values of fr11 and fr13 can be matched. Further, only by forming the groove 42 in another place, the three resonance frequencies, that is, the values of fr11, fr12, and fr13 can be matched.

Even if two grooves are provided, each resonance frequency fr
When 11, fr12, fr13 do not match each other,
It is also possible to form a groove 43 at another position, that is, between the strip electrodes 15 and 16 so that fr13 is hardly changed and fr11 and fr12 are reduced by substantially the same amount to be matched. Further, since the amount of change in each resonance frequency differs depending on the length and width of the groove, and further, the depth of the groove, the amount of change in each resonance frequency required for matching is determined in advance, and the length, width, and depth are determined. It is desirable to adjust the resonance frequency by changing only one factor as much as possible.

Further, in the case of the present embodiment, two grooves are provided so that the respective resonance frequencies are the same. However, when the respective resonance frequencies are the same from the beginning, naturally it is necessary to provide the grooves. There is no. Furthermore, the resonance frequencies may be the same even with only one groove. In this way, it is necessary to change the number of grooves as appropriate to match the resonance frequencies.

[0028]

According to the present invention, an electrodeless portion is formed on a strip electrode, a groove is formed on the surface of the piezoelectric ceramic body exposed on at least one electrodeless portion, and the length of the groove is adjusted. By doing so, it is possible to independently adjust each resonance frequency without changing the electrostatic capacitance of each strip electrode. That is, by forming an electrodeless portion in the center of a strip electrode having an appropriate area in advance and forming a groove in the electrodeless portion, the resonance frequency can be easily matched without changing the characteristics of the piezoelectric gyro. Therefore, it is possible to obtain a highly accurate piezoelectric vibration gyro.

Further, by forming a groove on the surface of the piezoelectric ceramic body exposed in the gap between the strip-shaped electrodes, the stripe-shaped electrode seen from a direction perpendicular to the direction connecting the groove and the center of the cross section of the piezoelectric ceramic body. Keep the resonance frequency constant,
Since the resonance frequency seen from the other strip electrodes can be reduced, either one of the resonance frequencies can be reduced or any other resonance frequency can be kept constant even if the resonance frequencies are different. The resonance frequencies can be matched with each other without changing the characteristics of the piezoelectric gyro. Therefore, by forming a groove on the surface of the piezoelectric ceramic body exposed in the gap between the strip electrodes, an effect equivalent to forming a groove in the strip electrode portion can be obtained.

[Brief description of drawings]

FIG. 1 is a partial plan view showing an embodiment of a piezoelectric vibration gyro of the present invention.

FIG. 2 is a graph showing changes in resonance frequency in an example of the piezoelectric vibrating gyroscope of the present invention.

FIG. 3 is a sectional view showing another embodiment of the piezoelectric vibrating gyro of the present invention.

FIG. 4 is a graph showing a change in resonance frequency when the piezoelectric vibration gyro shown in FIG. 3 is operated.

FIG. 5 is a perspective view showing a structure of a piezoelectric vibrator used in a conventional piezoelectric vibrating gyro.

FIG. 6 is a diagram for explaining the operation of a conventional piezoelectric vibrating gyro.

FIG. 7 is a diagram for explaining the operation of a conventional piezoelectric vibrating gyro.

FIG. 8 is a diagram for explaining the operation of a conventional piezoelectric vibrating gyro.

FIG. 9 is a diagram for explaining the operation of the conventional piezoelectric vibration gyro.

[Explanation of symbols]

1,9 Piezoelectric ceramics body 2,10,11,12,13,14,15,16 Strip electrode 3 Electrodeless portion 8 Piezoelectric vibrator 41, 42, 43 Groove

Claims (4)

[Claims] 1. A cylindrical or cylindrical piezoelectric ceramic body, and a plurality of strip electrodes provided on the outer peripheral surface of the piezoelectric ceramic body in parallel to the axial direction. Polarization and polarization are performed using the strip electrodes. A piezoelectric vibrating gyro for driving and detecting, wherein the strip-shaped electrode has an electrodeless portion in a central portion. 2. The piezoelectric vibration gyro according to claim 1, wherein a groove is formed on a surface of the piezoelectric ceramic body exposed on at least one electrodeless portion of the strip electrode. gyro. 3. The piezoelectric vibration gyro according to claim 1, wherein at least one groove is formed on the surface of the piezoelectric ceramic body exposed in the gap between the plurality of strip electrodes. Vibrating gyro. 4. A piezoelectric vibrator is formed by providing a plurality of strip electrodes parallel to the axial direction on an outer peripheral surface of a cylindrical or cylindrical piezoelectric ceramic body, and exposed in a gap between the plurality of strip electrodes. In addition, at least one groove is formed on the surface of the piezoelectric ceramic body, and the resonance frequency seen from the strip electrode in the direction perpendicular to the direction connecting the groove and the center of the cross section of the piezoelectric ceramic body is defined by the groove. A method for adjusting the resonance frequency of a piezoelectric vibrating gyro, which is characterized in that the resonance frequency seen from the other strip electrodes is kept constant and reduced.