JPH04307322A - Piezoelectric vibrating gyro - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric vibrating gyro which has little characteristic irregularity and is easy to assemble. CONSTITUTION:Three band-shaped electrodes 11-13 are formed with an equal distance on the outer peripheral surface of a piezoelectric ceramic cylinder 10 in parallel to the longitudinal direction of the cylinder 10. A connecting electrode 14 is formed to connect the band-shaped electrodes 11, 13. Moreover, there are two band-shaped electrodes 15, 16 formed with the same distance from the central band-shaped electrode 12 between the central band-shaped electrode 12 and the band-shaped electrodes 11, 13 at both sides of the electrode 12. Polarization is carried out between the electrodes 12 and 11, 13. The central band-shaped electrode 12 is turned to be an earth terminal, and the band-shaped electrodes 11, 13 at both sides of the electrode 12 become input terminals, while the band-shaped electrodes 15, 16 are output terminals. When an alternating current of approximately the same frequency as the resonance frequency of the bending vibrating mode of the piezoelectric ceramic cylinder 10 is applied to the input terminals, the differential voltage at the two output terminals is detected.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a piezoelectric vibrating gyroscope, and more specifically to a gyroscope used in an attitude control system for equipment mounted on a moving body such as a ship or an automobile, or a navigation system for an automobile. In particular, the present invention relates to a piezoelectric ceramic vibrating gyroscope having a simple structure using a piezoelectric vibrator made of a single piezoelectric ceramic.

0002

2. Description of the Related Art This type of piezoelectric vibrating gyroscope utilizes a mechanical phenomenon in which when rotational acceleration is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the direction of the vibration.

That is, in a compound vibration system configured to be able to excite vibrations in two different orthogonal directions, when the vibrator is rotated while one vibration is being excited, this vibration is caused by the action of the Coriolis force mentioned above. A force acts in the direction perpendicular to the one, and the other vibration is excited. The magnitude of this vibration is proportional to the magnitude of vibration on the input side and the rotational angular velocity, so
When the input voltage is constant, the magnitude of the rotational angular velocity can be determined from the magnitude of the output voltage that is proportional to the magnitude of this vibration.

FIG. 8 shows an example of a conventional piezoelectric vibrating gyroscope.
A vibrating sound bar 10 configured to vibrate at right angles to the vibration direction of the vibrating sound bars 101, 101' at the tips of the vibrating sound bars 101, 101'.
2,102' is added. Vibration sound pieces 101, 10
1', 102, and 102' are made of metal, electrodes are formed on both sides of each sound piece, and piezoelectric ceramic thin plates 103 to 106 polarized in the thickness direction are bonded to each other.

In this piezoelectric vibrating gyroscope, vibrating vibrating bars 101, 1 including vibrating vibrating bars 102, 102' at the tips are mounted on piezoelectric ceramic thin plates 103, 104 on the input side.
A driving voltage having a frequency equal to the resonance frequency of 01' is applied to excite the vibrating sound bars 101, 101'. At this time, the vibrating sound pieces 102 and 102' are vibrating sound pieces 101 and 101, respectively.
However, the vibrating sound bars 102, 102' themselves do not vibrate in a direction perpendicular to the vibration direction of the vibrating sound bars 101, 101'. However, in this state, when the tuning fork vibrator is rotated around the center of the vibrating sound bars 101, 101', 102, 102' as shown in the figure, the vibration direction of the vibrating sound bars 101, 101' changes due to the action of the Coriolis force. A force acts in the direction perpendicular to the vibrating acoustic bars 102, 102', and as a result, the piezoelectric ceramic thin plates 105, 106 on the output side vibrate.
A voltage proportional to the rotational angular velocity is generated.

FIG. 9 shows another example of a conventional piezoelectric vibrating gyroscope. This piezoelectric vibrating gyroscope has a structure in which piezoelectric ceramic thin plates 108 and 109, which have electrodes formed on both sides and are polarized in the thickness direction, are bonded to adjacent surfaces of a metal prism 107 having a square cross section. . The metal prism 10 is capable of bending vibration in two directions perpendicular to each other at approximately the same resonance frequency, and when a voltage with a frequency equal to this resonance frequency is applied to the piezoelectric ceramic thin plate 108, the piezoelectric ceramic thin plate 108 The joined surfaces undergo bending vibration in the direction of unevenness. In this state, no voltage is generated in the piezoelectric ceramic thin plate 109 of the metal prism 107, but when the metal prism 107 is rotated around its length, due to the Coriolis force,
The metal prism 107 bends and vibrates in a direction in which the surface to which the piezoelectric ceramic thin plate 109 is bonded becomes uneven, and a voltage proportional to the rotational angular velocity is generated in the piezoelectric ceramic 109.

FIG. 10 shows another example of a conventional piezoelectric vibrating gyroscope. In this piezoelectric vibrating gyroscope, electrodes are formed on each of the three surfaces of a triangular metal prism 110 having an equilateral triangular cross section, and electrodes are formed on both surfaces, and a piezoelectric ceramic thin plate 11 is polarized in the thickness direction.
1 to 113 are joined. The metal triangular prism 110 is capable of bending vibration at approximately the same resonant frequency in the direction connecting each side and the opposing apex, and as shown in FIG. When voltages of the same frequency are applied, the surface to which the piezoelectric ceramic thin plates 111 are bonded bends and vibrates in a direction that becomes uneven.

Further, as shown in FIG. 12, when voltages having the same amplitude, the same phase, and a frequency equal to the resonant frequency of the metal triangular prism 110 are applied to two adjacent piezoelectric ceramic thin plates 111 and 112, the piezoelectric ceramic As a result of combining the bending vibration in the direction in which the surface to which the thin plates 111 are bonded is uneven and the bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 112 is bonded is to be uneven, the metal triangular prism 1
10 bends and vibrates in the direction (arrow direction) where the surface to which the remaining piezoelectric ceramic thin plates 113 are bonded becomes uneven.

Furthermore, when voltages having the same amplitude, opposite phase, and a frequency equal to the resonant frequency of the metal triangular prism 110 are applied to two adjacent piezoelectric ceramic thin plates 111 and 112 as shown in FIG. As a result of combining the bending vibration in the direction in which the joined surface becomes uneven, and the bending vibration in the direction in which the joined surface of the piezoelectric ceramic thin plate 112 becomes uneven, the metal triangular prism 110 becomes the surface to which the remaining piezoelectric ceramic thin plate 113 is joined. flexural vibration in the direction parallel to (arrow direction).

On the other hand, when the metal triangular prism 110 is rotated around its longitudinal center in the state shown in FIG. The joined surfaces undergo bending vibration in a direction perpendicular to the direction in which they become uneven. As shown in FIG. 13, the bending vibration of the metal triangular prism 110 in the direction parallel to the piezoelectric ceramic thin plate 113 is caused by the piezoelectric ceramic thin plate 111,
112. Therefore, when the metal triangular prism 110 is flexibly vibrated in a direction parallel to the piezoelectric ceramic thin plate 113, the piezoelectric ceramic thin plates 111, 112 One of the voltages applied to the two will decrease by that amount, and the other will increase by that amount. Therefore, the voltage of the difference between the terminal voltages of the piezoelectric ceramic thin plates 111 and 112 becomes a voltage proportional to the rotational angular velocity of the metal triangular prism 110.

[0011]

[Problems to be Solved by the Invention] However, the conventional piezoelectric vibrating gyroscope described above has a structure in which a metal vibrating piece (or metal prismatic prism, metal triangular prism) and a piezoelectric ceramic thin plate are bonded with an adhesive. However, there is a drawback that the characteristics of the piezoelectric vibrating gyroscope vary due to variations in the bonding position and the adhesive layer.

For example, in the case of the structure using the tuning fork vibrator shown in FIG.
It is necessary to join them at right angles, but the disadvantage is that it is difficult to assemble them accurately.

An object of the present invention is to provide a piezoelectric vibrating gyroscope which does not require the above adhesive structure, has less variation in characteristics, and is easy to assemble.

[0014]

[Means for Solving the Problems] According to the present invention, three strip electrodes are formed on the outer peripheral surface of a piezoelectric ceramic cylinder at equal intervals parallel to the length direction of the piezoelectric ceramic cylinder, and the strip electrodes on both sides are formed at equal intervals. A connection electrode is formed to connect the electrodes, and two strip electrodes are formed at equal distances from the center strip electrode between the center strip electrode and the strip electrodes on both sides. Polarization treatment is performed between the central strip electrode and the center strip electrode is used as a ground terminal,
The band-shaped electrodes on both sides are used as input terminals, the two band-shaped electrodes are used as output terminals, and an AC electrode for excitation having a frequency approximately equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder is applied to the input terminal. Thus, a piezoelectric vibrating gyroscope is obtained, which is characterized in that it detects a differential voltage between the two output terminals.

[0015]

[Operation] The piezoelectric vibrating gyroscope of the present invention has a structure using a piezoelectric vibrator in which electrodes are formed on the outer circumferential surface of a piezoelectric ceramic cylinder, so the structure is simple, and it does not require the adhesive work of conventional piezoelectric vibrating gyroscopes. This eliminates the need for variations in properties due to variations in bonding positions and adhesive layers.

Furthermore, since a piezoelectric ceramic cylinder is used, a vibrator with higher dimensional accuracy can be obtained than in the case of using a conventional vibrating sound piece or a metal prism. In the piezoelectric vibrating gyroscope of the present invention, by constructing the piezoelectric ceramic cylinder or the like from a material with homogeneous material characteristics, the characteristics of two orthogonal vibration modes as described below can be matched with high accuracy.

[0017]

[Embodiment] Fig. 1 shows the main part of a piezoelectric vibrating gyroscope according to an embodiment of the present invention. Three strip electrodes 11 to 1 parallel to the length direction of the piezoelectric ceramic cylinder 10 in approximately two-thirds of the area.
3 are formed at equal intervals.

The strip electrodes 11 and 13 are electrically connected by a connecting electrode 14. Further, two strip electrodes 15 and 16 are formed between the strip electrodes 11 and 12 and between the strip electrodes 12 and 13 at positions at equal distances from the strip electrode 12, respectively. These strip electrodes 15, 16
is formed by direct printing using curved screen printing, or by removing unnecessary portions of electrodes formed over the entire surface by plating or the like using photo-etching.

When the piezoelectric ceramic cylinder 10 described above is polarized by applying a high DC voltage between the central strip electrode 12 and the strip electrodes 11 and 13 on both sides connected to the connecting electrode 14, As shown in Figure 2, piezoelectric ceramic cylinder 1
0 in the cross-sectional direction from the strip electrode 12 to the strip electrode 15,
16, and from the strip electrodes 15 and 16 to the strip electrode 1.
Polarization shown by the broken line occurs in the directions of 1 and 13.

FIG. 3 shows the basic principle of operation of the piezoelectric vibrating gyroscope of the present invention. For convenience of explanation, in the piezoelectric gyroscope of FIG. 3, the connection electrode 14 and Strip electrodes 15 and 16 have been removed. Further, the band-shaped electrode gaps of the piezoelectric ceramic cylinder 10 located between the band-shaped electrodes 11 and 12 and the band-shaped electrodes 12 and 13 are designated as G1 and G2, respectively. In this piezoelectric vibrating gyroscope, when an AC voltage is applied to the band-shaped electrode gap G1, if the direction of the applied electric field generated by this AC voltage is equal to the direction of polarization in the piezoelectric ceramic cylinder 10, it will extend to the band-shaped electrode gap G1. When strain occurs, and on the other hand, when the applied electric field and polarization are in opposite directions, shrinkage strain occurs in the band-shaped electrode gap G1.

Therefore, by applying an excitation AC voltage having a frequency substantially equal to the resonant frequency of the bending vibration mode of the piezoelectric ceramic cylinder 10 to the band-shaped electrode gap G1, the piezoelectric ceramic cylinder 10 is caused to close the band-shaped electrode gap by the piezoelectric transverse effect. It is possible to cause bending vibration in the direction of arrow I, which is substantially along a plane including the center line of portion G1 and the center axis of the piezoelectric ceramic cylinder. Conversely, if the piezoelectric ceramic cylinder 10 is vibrated in the direction of the arrow I by another drive source in FIG. 3, a voltage is generated between the strip electrodes 11 and 12 due to the piezoelectric effect.

FIG. 4 shows the piezoelectric vibrating gyroscope of the embodiment shown in FIGS. 1 and 2 in which the strip electrodes 11 and 13 sandwiching the strip electrode 12 between the connecting electrodes 14 are connected by the connecting electrode 14. The state of distortion and vibration direction generated in the cross-sectional direction of the piezoelectric ceramic cylinder 10 when an excitation AC voltage with a frequency approximately equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder 10 is applied between the electrode 12 and the piezoelectric ceramic cylinder 10 are as follows. FIG.

In FIG. 4, since the polarity of the electric field applied to the direction of polarization of the band-shaped electrode gap G1 and G2 is the same, the piezoelectric ceramic cylinder 10 has the same polarization as described in FIG. As a result, vibration driving forces i and ii are generated in the same direction as the direction substantially along the plane including the center lines of the band-shaped electrode gaps G1 and G2 and the center axis of the piezoelectric ceramic cylinder 10, respectively, and as a result of combining these, As shown in Figure 4,
The piezoelectric ceramic cylinder 10 bends and vibrates in the direction of arrow II, which is substantially along a plane including the center line of the strip electrode 12 and the central axis of the piezoelectric ceramic cylinder 10. Conversely, when the piezoelectric ceramic cylinder 10 is vibrated in the direction of the solid arrow II in FIG. , voltages of the same phase are generated with the strip electrode 12 as a reference.

FIG. 5 shows the strip electrodes 11 and 13 in FIG.
and the strip electrodes 11 and 12, and 11
The state of distortion and the direction of vibration generated in the cross-sectional direction of the piezoelectric ceramic cylinder 10 are shown when the polarity of the AC voltage applied between and 13 is reversed.

That is, in this case, the band-shaped electrode gap G1
Since the polarity of the electric field applied is opposite to the direction of polarization of G1 and G2, the piezoelectric ceramic cylinder 10 has a surface that includes the center line of the strip electrode gap G1 or G2 and the central axis of the piezoelectric ceramic cylinder 10. Vibration driving forces i and iii are generated, one of which is in the opposite direction along , and these are combined as shown in FIG. The piezoelectric ceramic cylinder 10 bends and vibrates in a direction III that is substantially perpendicular to the direction along which the piezoelectric ceramic cylinder 10 passes. Conversely, when the piezoelectric ceramic cylinder 10 is vibrated in the direction of arrow III by another driving source, the piezoelectric effect creates a gap between the strip electrodes 11 and 12 and between the strip electrodes 12 and 13 with respect to the strip electrode 12. Opposite phase voltage is generated.

FIG. 6 is an explanatory diagram of the operating principle of the piezoelectric vibrating gyroscope of the embodiment shown in FIGS. 1 and 2. In this embodiment, the strip electrode 12 is used as a ground terminal,
Furthermore, when an excitation AC voltage having the same amplitude, the same phase, and whose frequency almost matches the resonant frequency of the bending vibration mode of the piezoelectric ceramic cylinder 10 is applied to the strip electrodes 11 and 13, as explained in FIG. , approximately strip-shaped electrode 1
2 and the center axis of the piezoelectric ceramic cylinder 10, and vibration in a direction substantially along the plane including the center line of the strip electrode 12 and the central axis of the piezoelectric ceramic cylinder 10. As a result of the synthesis, the piezoelectric ceramic cylinder 10 vibrates in a direction II along a plane including the center line of the strip electrode 12 and the central axis of the piezoelectric ceramic cylinder 10.

In FIG. 6, the voltage applied to the strip electrodes 11 and 13 for driving is applied to the strip electrodes 15 and 16, respectively. , the capacitance C36 between the strip electrodes 13 and 16, and the capacitance C62 between the strip electrodes 16 and 12. Then, when the piezoelectric ceramic cylinder 10 is rotated about its axis, a Coriolis force is generated in a direction perpendicular to the vibration direction. It also vibrates in the direction II perpendicular to the direction substantially along the plane including the central axis.

Therefore, as explained with reference to FIG. 5, voltages of the same amplitude and opposite phase are generated in the band electrodes 11 and 13 due to this vibration, and at the same time voltages of the same amplitude and opposite phase are generated in the band electrodes 15 and 16 due to this vibration. Voltage is generated. In this case, one of the voltages generated on the strip electrodes 15 and 16 decreases by that amount, and the other increases by that amount, so the strip electrode 15
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 a voltage proportional to the applied rotational angular velocity.

FIG. 7 is an explanatory diagram showing an example of a method of applying an excitation AC voltage having a frequency approximately equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder 10 to its input terminal in the piezoelectric vibrating gyroscope of this embodiment. It is. That is, in this case, the output of the detection strip electrode 15 is connected to the amplifier 22 via the phase circuit 21, and the output of the amplifier 22 is used as the driving voltage for the piezoelectric vibrating gyroscope to drive the strip electrode 11.
and 13, a self-excited oscillation circuit may be constructed. With this configuration, it is possible to automatically track changes in the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder 10 due to changes in ambient temperature, and a stable piezoelectric vibrating gyroscope can be formed.

[0030] In addition to the above-mentioned configuration means, such a self-excited oscillation circuit may be configured such that, for example, the sum of the voltages generated at the strip electrodes 15 and 16 is connected to the amplifier circuit 22 via the phase circuit 21. . Furthermore, a piezoelectric vibrator having two terminals, the strip electrode 12 and the strip electrodes 11 and 13 connected thereto by the connection electrode 14, can be used to construct a piezoelectric self-excited oscillation circuit that is conventionally generally constructed. can.

By the way, in the piezoelectric vibrating gyroscope of the present invention, the three band-shaped electrodes (band-shaped electrodes 11 to 13 in the embodiment) formed on the outer peripheral surface of the piezoelectric ceramic cylinder are as follows:
Approximately 3 in the circumferential direction of the outer peripheral surface of the piezoelectric ceramic cylinder 10
It is preferable to form the area in half the area.

That is, in the piezoelectric vibrating gyroscope of the present invention,
When considering the two regions on both sides of the central band-shaped electrode (band-shaped electrode 12), two bending vibrations occur in directions along a plane that includes approximately the center line of each region and the central axis of the piezoelectric ceramic cylinder 10. The difference between these two bending vibrations is synthesized, and the output voltage accompanying the Coriolis force when the piezoelectric ceramic cylinder 10 is rotated around its axis is detected. There is. Therefore, if each region is widened, vibrations in each direction can be driven or detected with high sensitivity, but if this region is approximately one-third or more of the outer peripheral surface of the piezoelectric ceramic cylinder in the circumferential direction, This is because the angle between the directions of the two bending vibrations is 120° or more, and as a result, the amplitude of the combined vibration is smaller than the vibration amplitude for one drive, as is clear from the law of vector composition. be.

[0033]

[Effects of the Invention] As described above, according to the piezoelectric vibrating gyroscope of the present invention, the structure is simple, and variations in characteristics caused by variations in bonding position and bonding layer can be eliminated. With this configuration, it is possible to obtain a vibrator with higher dimensional accuracy than in the past.

Furthermore, since the drive strip electrode (input terminal) and the detection strip electrode (output terminal) are separated, when voltages of the same phase and amplitude are applied to the drive strip electrode, As a result of being able to connect directly with a conductor without using a resistor voltage divider or a buffer amplifier, there is also the effect that the circuit configuration including the self-excited oscillation circuit becomes simpler.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a piezoelectric vibrating gyroscope according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the direction of polarization in the cross-sectional direction of a piezoelectric ceramic cylinder in the piezoelectric vibrating gyroscope of the example.

FIG. 3 is an explanatory diagram of the operation of the embodiment of the present invention.

FIG. 4 is an explanatory diagram of the operation of the embodiment of the present invention.

FIG. 5 is an explanatory diagram of the operation of the embodiment of the present invention.

FIG. 6 is an explanatory diagram of the operation of the embodiment of the present invention.

FIG. 7 is an explanatory diagram of a piezoelectric vibrating gyroscope according to an embodiment of the present invention including a drive detection circuit.

FIG. 8 is a schematic diagram showing an example of a conventional piezoelectric vibrating gyroscope.

FIG. 9 is a schematic diagram showing another example of a conventional piezoelectric vibrating gyroscope.

FIG. 10 is a schematic diagram showing another example of a conventional piezoelectric vibrating gyroscope.

FIG. 11 is an explanatory diagram of the operation of a conventional piezoelectric vibrating gyroscope.

FIG. 12 is an explanatory diagram of the operation of a conventional piezoelectric vibrating gyroscope.

FIG. 13 is an explanatory diagram of the operation of a conventional piezoelectric vibrating gyroscope.

FIG. 14 is an explanatory diagram of the operation of a conventional piezoelectric vibrating gyroscope.

[Explanation of symbols]

10 Piezoelectric ceramic cylinders 11 to 13 Band-shaped electrode 14 Connection electrodes 15, 16 Band-shaped electrode 20 Differential amplifier 21 Phase circuit 22 Amplifier 101, 101', 102, 102' Vibration sound piece 10
3,104,105,106,108,109 Piezoelectric ceramic thin plate 107 Metal prism 110 Metal triangular prism

Claims (1)

[Claims] 1. Three strip electrodes parallel to the length direction of the piezoelectric ceramic column are formed at equal intervals on the outer peripheral surface of the piezoelectric ceramic column, and a connecting electrode is formed to connect the strip electrodes on both sides, and further Two strip electrodes are formed at equal distances from the center strip electrode between the center strip electrode and the strip electrodes on both sides, and polarization processing is performed between the center strip electrode and the strip electrodes on both sides. In addition, the center band-shaped electrode is used as a ground terminal, the band-shaped electrodes on both sides are used as input terminals, the two band-shaped electrodes are used as output terminals, and the resonant frequency of the bending vibration mode of the piezoelectric ceramic cylinder is set at the input terminal. A piezoelectric vibrating gyroscope characterized in that a differential voltage between the two output terminals is detected by applying an excitation alternating current electrode with a frequency substantially equal to .