JP3292934B2 - Piezoelectric vibrating gyroscope and method of adjusting resonance frequency of piezoelectric vibrating gyroscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gyroscope used for attitude control of a moving body itself such as a ship or a car and equipment mounted thereon, a navigation system of a car, etc., and particularly to an ultrasonic wave of a piezoelectric vibrator. The present invention relates to a piezoelectric vibrating gyroscope using vibration.

[0002]

2. Description of the Related Art A vibrating gyroscope is a gyroscope utilizing a mechanical phenomenon that when a rotating angular velocity is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the direction of the vibration. In general, in a composite vibration system configured to be able to excite and detect vibrations in two different directions that are orthogonal to each other, when the vibrator is rotated while one of the vibrations is being excited, the above-mentioned vibration causes a right angle 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 input-side vibration and the rotational angular velocity, when the input voltage is kept constant, the magnitude of the rotational angular velocity is calculated from the magnitude of the output voltage proportional to the magnitude of the vibration. You can ask.

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

Hereinafter, the operation of the conventional piezoelectric vibrating gyroscope will be described with reference to FIG. 6 when the number of band electrodes 10 is six. The piezoelectric ceramic cylinder 9 (see FIG. 5)
When the strip electrodes 11, 12, 13, 14, 15, and 16 are formed, every other strip electrodes 11, 1
3, 15 and 12, 14, 16 are electrically connected to form 2
Polarization processing is performed as a terminal. 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 view of the operation principle of a conventional piezoelectric vibrator. In FIG. 7, the gaps between the strip electrodes are denoted by G1, G2, G3, G4, G5 and G6, respectively.
Now, the state of the strain and the vibration direction generated in the cross-sectional direction of the piezoelectric ceramic cylinder 9 when the strip electrodes 11 and 13 sandwiching the strip electrode 12 are connected to form a common ground and an AC voltage is applied to the strip electrode 12 are shown. ing. Gap G1 and G
When 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 so that the polarity of the electric field to be applied is the same for the polarization directions of the two parts, the piezoelectric ceramic cylinder In each of the piezoelectric ceramic cylinders 9, a vibration driving force is generated in the same direction as the direction including the center line of the gaps G 1 and G 2 and the plane including the central axis of the cylinder as shown by solid arrows. Vibrates flexibly in the direction of the plane (direction of R1) including the center line of the strip electrode 12 and the center axis of the cylinder. In FIG. 7, the piezoelectric ceramic cylinder 9 is pointed by an arrow R by another drive source.
When vibrating in one direction, an output voltage is generated at the strip electrode 12 by the piezoelectric effect.

[0008] FIG. 8 shows the state of strain and the 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 (in 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 (The direction indicated by the solid arrow) is generated, and these are combined, and the piezoelectric ceramic cylinder 9 is substantially perpendicular (R2) to the direction of the plane including the center line of the strip electrode 12 and the center axis of the cylinder. Direction). In FIG. 8, when the piezoelectric ceramic cylinder 9 is vibrating in the direction of arrow R2 by another driving source,
Opposite phase voltages are generated at the strip electrodes 14 and 16 by the piezoelectric effect.

FIG. 9 is an explanatory view of the operation principle of a piezoelectric vibrating gyroscope constituted by using the above-described piezoelectric ceramic cylinder 9 having six strip electrodes. In FIG. 9, the strip electrodes 11, 13 and 15 are connected to form a common ground, and an AC voltage for excitation is applied to the strip electrodes 12. At this time, the frequency of the applied voltage substantially matches the resonance frequency of the piezoelectric ceramic cylinder 9 in the bending mode. The vibration direction of the piezoelectric ceramic cylinder 9 at this time is substantially the direction of the plane (R3 direction) including the center line of the strip-shaped electrode 12 and the central axis of the piezoelectric ceramic cylinder 9.

In FIG. 9, when the piezoelectric ceramic cylinder 9 is rotated about the axis of the cylinder as a rotation axis, a Coriolis force is generated in a direction perpendicular to the vibration direction, and the piezoelectric ceramic cylinder 9 is rotated.
Vibrates in a direction perpendicular to the direction (R3 direction) of the plane including the center line of the strip electrode 12 and the center axis of the piezoelectric ceramic cylinder 9. Accordingly, as described with reference to FIGS. 7 and 8, the band electrodes 14 and 16 have the same amplitude due to vibration in the direction (R3 direction) of the plane including the center line of the band electrode 12 and the center axis of the piezoelectric ceramic cylinder 9. , A voltage is generated by combining a voltage of the same phase and a voltage of the same amplitude and opposite phase due to vibration in a direction perpendicular to the same. 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 gyroscope shown in FIGS. 8 and 9, the strip electrodes 11, 13 and 15 are used as common ground terminals, and the strip electrodes 12, 13 used as input / output terminals are used.
It is desirable that the resonance frequencies fr1, fr2, and fr3 when driven from the terminals 14 and 16, respectively, match as much as possible.

[0010]

In the above-described conventional piezoelectric vibrating gyroscope, the bending vibration occurs in the direction including the center line of the strip-shaped electrode serving as the driving terminal and the center axis of the piezoelectric ceramic cylinder. In order to adjust the resonance frequency of the bending vibration in the direction, at least one of the band-shaped electrode serving as the drive terminal and the band-shaped electrode which is symmetrical with respect to the center axis of the piezoelectric ceramic cylinder and the band-shaped electrode (the ground electrode). It is necessary to mechanically cut the center of one of the strip electrodes. However, if the strip electrode itself is cut, the electrode area changes, which adversely affects the gyro characteristic in which the capacitance value has changed, so that the center of the strip electrode cannot be cut mechanically.

An object of the present invention is to provide a piezoelectric vibrating gyroscope that 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 with the axial direction are provided. In a piezoelectric vibrating gyroscope that performs polarization, driving, and detection using the strip-shaped electrodes, the strip-shaped electrodes have an electrodeless portion at the center thereof, and at least one of the plurality of strip-shaped electrodes has no electrode. By forming a groove on the surface of the piezoelectric ceramic body exposed to the electrode portion, a resonance frequency can be easily adjusted without damaging the strip-shaped electrode, thereby obtaining a piezoelectric vibrating gyroscope.

According to the present invention, there is provided a cylindrical or cylindrical piezoelectric ceramic body, and a plurality of strip electrodes provided on an outer peripheral surface of the piezoelectric ceramic body in parallel with an axial direction. In a piezoelectric vibrating gyroscope that performs polarization and driving / detection using an electrode, the strip-shaped electrode has an electrodeless portion in the center thereof, and is disposed on a surface of the piezoelectric ceramic body exposed in a gap between the plurality of strip-shaped electrodes. By forming at least one groove, a resonance frequency can be easily adjusted without damaging the strip-shaped electrode, thereby obtaining a piezoelectric vibrating gyroscope.

[0014]

Further, according to the present invention, the center portion is
A band-shaped electrode having an electrodeless portion defined by a through hole in a predetermined area
Cylindrical or cylindrical piezoelectric ceramic body with multiple poles
A piezoelectric vibrator is formed on the outer peripheral surface of the piezoelectric ceramic body so as to be parallel to the axial direction, and at least one or more grooves are formed on the surface of the piezoelectric ceramic body exposed in the gap between the plurality of strip electrodes. The groove keeps the resonance frequency viewed from the strip electrode in a direction perpendicular to the direction connecting the groove and the center of the cross section of the piezoelectric ceramic body constant, and reduces the resonance frequency viewed from the other strip electrodes. Resonance frequency
In the number adjustment step, the resonance frequency can be easily adjusted without damaging the strip-shaped electrodes, thereby providing a method of adjusting the resonance frequency of the piezoelectric vibrating gyroscope.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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 band-shaped electrode 10 (see FIG. 5) of a piezoelectric vibrating gyroscope according to the present invention. A plurality of strip-shaped electrodes 2 are formed on the outer peripheral surface of a columnar or cylindrical piezoelectric ceramic body 1 as in the related art. That is, these strip electrodes 2 are formed on the outer peripheral surface of the piezoelectric ceramic body 1 at the center in the length direction of the piezoelectric ceramic body 1 in parallel with the axial direction. An electrodeless portion 3 is formed in the center of each of the strip electrodes 2, and a groove is provided in the electrodeless portion 3.

FIG. 2 shows the change of each resonance frequency according to the change of 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. As described above, the resonance frequencies fr1, fr2, and fr3 are resonance frequencies when the strip electrodes 11, 13, and 15 are used as common ground electrodes and driven from the strip electrodes 12, 14, and 16, respectively.

As can be seen from FIG. 2, a non-electrode portion is formed in the strip-shaped electrode 12, a groove is provided in the non-electrode portion, and the axial length of the groove is gradually increased. When the axial length is changed between 0 mm and 3 mm, the value of the resonance frequency fr1 decreases most greatly, and the resonance frequencies fr2, f2
The amount of change in r3 is very small. This is because the shape of the piezoelectric vibrator 8 (see FIG. 5) is a column, and the six strip electrodes are formed on the outer peripheral surface of the column at substantially equal intervals. Even when the electrodeless portions are formed on the strip electrodes 12 and 14, the same characteristics as described above are exhibited. That is, the resonance frequency fr
1 is changed to match the resonance frequencies fr2 and fr3, the electrode 1 having a direct relationship with the change in the resonance frequency fr1
By forming a groove in the non-electrode portion of No. 2, only the resonance frequency fr1 is reduced. Similarly, when it is desired to change only the resonance frequency fr2, a groove is formed in the non-electrode portion of the electrode 14 which is directly related to the change in the resonance frequency fr2, so that only the resonance frequency fr2 is reduced.

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

Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 3 is a sectional view of a piezoelectric vibrator showing another embodiment of the present invention. Strip electrodes 12, 14, 16
Are electrodes for driving or detecting, and arrows 31 and 3
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 portions between the strip electrodes 11 and 12, the non-electrode portions between the strip electrodes 11 and 16, and the non-electrode portions between the strip electrodes 16 and 15, respectively. , Groove 42 and groove 43 are formed.

FIG. 4 is a graph showing a change 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 ( The resonance frequency fr13 is the resonance frequency in the bending vibration direction (arrow 33) of the piezoelectric vibrator generated when the piezoelectric vibrator is driven from the strip electrode 14.

The resonance frequency f in a state where no groove is 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 electrode 11 and the strip electrode 12
1, the values of fr12 and fr13 were measured and measured.
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, if the groove 41 is formed between the strip electrodes 11 and 12, The resonance frequency fr11 viewed from the strip electrode 16 provided in a direction (arrow 31) perpendicular to the direction connecting the center of the cross section of the piezoelectric ceramic body is kept constant, and the other strip electrodes 1 as drive electrodes are kept constant.
The resonance frequencies fr12 and fr13 viewed from the points 2 and 14 decrease. Therefore, as shown in FIG.
Hardly changes, the resonance frequencies fr12 and fr
13 decreases, and as a result, the value of the resonance frequency fr13 becomes f
It matches the value of r11. Here, the resonance frequency fr12 decreases by the same amount as the decrease in the resonance frequency fr13. This is because the components in the direction connecting the grooves 41 of the resonance frequencies fr12 and fr13 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 electrode 11 and the strip electrode 16 will be described.
And 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 almost the same amount, respectively, based on the same principle as the resonance frequency change principle of the measurement 1, and as a result, the resonance frequencies fr11 and fr13 The value matches the value of fr12. That is, only by forming the groove 41 at one position of the non-electrode portion of the piezoelectric vibrator, two resonance frequencies,
That is, the values of fr11 and fr13 can be matched. Only by forming the groove 42 at another position, the values of the three resonance frequencies, that is, fr11, fr12, and fr13 can be matched.

Even if two grooves are provided, each resonance frequency fr
When 11, fr12 and fr13 do not match each other,
A groove 43 is formed at another point, that is, between the strip electrode 15 and the strip electrode 16, so that fr13 is hardly changed, and fr11 and fr12 can be reduced by almost the same amount and made to coincide. Also, since the amount of change in each resonance frequency varies depending on the length and width of the groove, and furthermore, the depth of the groove, the amount of change in each resonance frequency necessary for matching is determined in advance, and the length, width and depth are determined. It is desirable to change the resonance frequency by changing only one factor as much as possible.

In this embodiment, two grooves are provided to match the respective resonance frequencies. However, if the respective resonance frequencies match from the beginning, the grooves need to be provided as a matter of course. There is no. Further, there may be a case where the resonance frequencies coincide even with only one groove. As described above, it is necessary to change the number of grooves as appropriate to match the respective resonance frequencies.

[0028]

According to the present invention, an electrodeless portion is formed on a strip-shaped electrode, a groove is formed on the surface of the piezoelectric ceramic body exposed to 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 capacitance of each strip electrode. That is, by forming a non-electrode portion in the center of a strip-shaped electrode having an appropriate area in advance and forming a groove in the non-electrode portion, the resonance frequency can be easily matched without changing the characteristics of the piezoelectric gyro. And a highly accurate piezoelectric vibrating gyroscope can be obtained.

Further, by forming a groove on the surface of the piezoelectric ceramic body exposed in the gap between the band-shaped electrodes, the groove is viewed from the band-shaped electrode in a direction perpendicular to the direction connecting the groove and the center of the cross section of the piezoelectric ceramic body. And keep the resonance frequency constant,
Since the resonance frequencies viewed from the other strip electrodes can be reduced, even if the resonance frequencies are different, any one of the resonance frequencies can be appropriately reduced or any other resonance frequency can be kept constant. For example, the resonance frequencies can be matched 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 the drawings]

FIG. 1 is a partial plan view showing an embodiment of a piezoelectric vibrating gyroscope according to the present invention.

FIG. 2 is a graph showing a change in resonance frequency in one embodiment of the piezoelectric vibrating gyroscope according to the present invention.

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

FIG. 4 is a graph showing a change in resonance frequency when the piezoelectric vibrating gyroscope 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 gyroscope.

FIG. 6 is a view for explaining the operation of a conventional piezoelectric vibrating gyroscope.

FIG. 7 is a view for explaining the operation of a conventional piezoelectric vibrating gyroscope.

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

FIG. 9 is a view for explaining the operation of a conventional piezoelectric vibrating gyroscope.

[Explanation of symbols]

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

Continuation of the front page (56) References JP-A-3-150914 (JP, A) JP-A-4-106407 (JP, A) JP-A-4-106408 (JP, A) JP-A-4-331313 (JP) , A) JP-A-4-307322 (JP, A) JP-A-63-67921 (JP, U) US Patent 3520195 (US, A) Tadashi Chino, Piezoelectric vibration gyroscope and direction sensor, Ministry of Education, Culture, Sports, Science and Technology of 1986 Grants-in-Aid (General Research (B)) Research Result Report (Project No. 60460142), Japan (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01C 19/56 G01P 9/04

Claims (3)

(57) [Claims] 1. A piezoelectric ceramic body having a columnar or cylindrical shape and a plurality of strip electrodes provided on an outer peripheral surface of the piezoelectric ceramic body in parallel with an axial direction. In the piezoelectric vibrating gyroscope that performs driving / detection, the band-shaped electrode has an electrodeless portion in the center thereof, and the piezoelectric ceramic body exposed to the electrodeless portion of at least one of the plurality of band-shaped electrodes. A piezoelectric vibrating gyroscope wherein a resonance frequency can be easily adjusted without damaging the strip-shaped electrode by forming a groove on the surface of the piezoelectric vibrating gyroscope. 2. A piezoelectric ceramic body having a columnar or cylindrical shape and a plurality of strip electrodes provided on an outer peripheral surface of the piezoelectric ceramic body in parallel with an axial direction. In a piezoelectric vibrating gyroscope that performs driving and detection, the strip-shaped electrode has an electrodeless portion at a central portion thereof, and at least one groove is formed on a surface of the piezoelectric ceramic body exposed in a gap between the plurality of strip-shaped electrodes. By doing so, the resonance frequency can be easily adjusted without damaging the strip-shaped electrode. 3. A through hole having a predetermined area in the center portion
A plurality of strip-shaped electrodes having an electrodeless part defined by
Shaft on the outer peripheral surface of a piezoelectric or ceramic body
Forming a piezoelectric vibrator provided in parallel with the direction , forming at least one or more grooves on the surface of the piezoelectric ceramic body exposed in the gap between the plurality of strip-shaped electrodes; The resonance frequency viewed 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 kept constant, the resonance frequency viewed from the other strip electrodes is reduced, and the resonance frequency is adjusted by cutting. A resonance frequency adjustment method for a piezoelectric vibrating gyroscope, wherein the resonance frequency can be easily adjusted without damaging the strip-shaped electrode in the step .