JP2557286B2 - Piezoelectric vibration gyro - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses ultrasonic vibration of a piezoelectric vibrator in a gyroscope used in a posture control system of equipment mounted on a moving body such as a ship or an automobile and a navigation system of an automobile. The present invention relates to a so-called piezoelectric vibrating gyro, and particularly to a piezoelectric ceramic vibrating gyro having a simple structure using a piezoelectric ceramic simple substance vibrator.

[0002]

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

Generally, in a composite vibration system configured to be able to excite vibrations in two different directions which are orthogonal to each other, when one of the vibrations is excited and the vibrator is rotated, it is orthogonal to this vibration due to the action of the above-mentioned Coriolis force. Force acts in one 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. 9 is a schematic structural view of a first conventional example of a piezoelectric vibrating gyro, and a vibrating sound piece 10 constituting a tuning fork vibrator.
Vibrating sound piece 10 configured to vibrate at the tip of 1, 101 'at a right angle to the vibration direction of the vibrating sound piece 101, 101'.
2, 102 'are added. Vibrating sound piece 101, 10
Reference numerals 1'and 102, 102 'are made of metal, and electrodes are formed on both sides of each sound piece, and piezoelectric ceramic thin plates 103, 104, 105, 106 polarized in the thickness direction.
Are joined.

Piezoelectric ceramic thin plates 103, 1 on the input side
To 04, a drive voltage having a frequency equal to the resonance frequency of the vibrating sound piece 101, 101 'including the vibrating sound piece 102, 102' at the tip is applied to excite the vibrating sound piece 101, 101 '. At this time, the vibrating sound pieces 102 and 102 'vibrate together with the vibrating sound pieces 1 and 1', respectively.
102 'itself does not vibrate in the direction perpendicular to the vibrating direction of the vibrating sound pieces 101, 101'. However, in this state, the tuning fork vibrator is vibrated as shown in the figure.
When rotated about the center of 2, 102 'as an axis, a force acts in a direction perpendicular to the vibrating direction of the vibrating sound pieces 101, 101' due to the action of Coriolis force to vibrate the vibrating sound pieces 102, 102 '. As a result, the output side piezoelectric ceramic thin plate 1
At 05 and 106, a voltage proportional to the rotational angular velocity is generated.

FIG. 10 is a structural schematic view of a second conventional example of a piezoelectric vibrating gyro. In this piezoelectric vibrating gyro, electrodes are formed on both surfaces and piezoelectric ceramic thin plates 108 and 109 polarized in the thickness direction are joined to adjacent surfaces of a metal prism 107 having a square cross section. The metal prism 107 can flexurally vibrate in two directions perpendicular to each other at substantially the same resonance frequency, and when a voltage having a frequency equal to this resonance frequency is applied to the piezoelectric ceramic thin plate 108, the piezoelectric ceramic thin plate 108 is bonded. Flexural vibration occurs in the direction in which the surface becomes uneven. In this state, the metal prism 1
No voltage is generated on the piezoelectric ceramic thin plate 109 of No. 07, but when the metal prism 107 is rotated about the length direction, the surface of the metal prism 107 to which the piezoelectric ceramic thin plate 109 is bonded becomes uneven due to the action of the Coriolis force. Then, the piezoelectric ceramics 109 generate a voltage proportional to the rotational angular velocity.

FIG. 11 is a schematic view showing a third conventional example of a piezoelectric vibrating gyro. In this piezoelectric vibrating gyro, electrodes are formed on both sides of each of the three surfaces of a metal triangular prism 110 having an equilateral cross section, and the piezoelectric ceramic thin plate 11 is polarized in the thickness direction.
1, 112, 113 are joined. Metal triangular prism 11
0 indicates that bending vibration is possible at almost the same resonance frequency in the direction connecting each side and the facing vertex.
As shown in FIG. 2, when a voltage having a frequency substantially equal to this resonance frequency is applied to one piezoelectric ceramic thin plate 111, the surface to which the piezoelectric ceramic thin plate 111 is bonded is flexed and vibrated in a direction in which it becomes uneven.

Referring to FIG. 13, when a voltage having a frequency equal to the resonance frequency of the metal triangular prism 110 having the same amplitude and the same phase is applied to two adjacent piezoelectric ceramic thin plates 111 and 112, the metal triangular prism 110 causes the piezoelectric ceramic thin plate 1 to move.
The bending vibration in the direction in which the surface to which 11 is joined becomes uneven is combined with the bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 112 is joined becomes uneven, and the surface on which the remaining piezoelectric ceramic thin plate 113 is joined becomes uneven. Flexural vibration occurs in the direction (arrow direction).

As shown in FIG. 14, when a voltage having a frequency equal to the resonance frequency of the metal triangular prism 10 having the same amplitude and the opposite phase is applied to two adjacent piezoelectric ceramic thin plates 111 and 112, the metal triangular prism 110 causes the piezoelectric ceramic thin plate 11 to move.
The bending vibration in the direction in which the surface to which 1 is joined becomes uneven is combined with the bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 112 is joined becomes uneven, and the remaining piezoelectric ceramic thin plate 1
Flexural vibration occurs in the direction (arrow direction) parallel to the surface on which 13 is joined.

When the metal triangular prism 110 is rotated about the center in the lengthwise direction in the state shown in FIG. 13, the surface of the metal triangular prism 110 to which the piezoelectric ceramic thin plate 113 is bonded as shown in FIG. 15 due to the action of Coriolis force. Flexural vibration occurs in a direction perpendicular to the direction of the unevenness. As shown in FIG. 14, since the bending vibration of the metal triangular prism 110 in the direction parallel to the piezoelectric ceramic thin plate 113 is obtained by applying voltages of the same amplitude and opposite phase to the piezoelectric ceramic thin plates 111 and 112, the opposite effect is obtained. Thus, when the metal triangular prism 110 is flexurally vibrated in a direction parallel to the piezoelectric ceramic thin plate 113, one of the voltages applied to the piezoelectric ceramic thin plates 111 and 112 is reduced by that amount and the other voltage is increased 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]

However, in all of the conventional piezoelectric vibrating gyros, the metal sound piece and the piezoelectric ceramic thin plate are joined together by using an adhesive agent, which causes variations in the bonding position or variations in the adhesive layer. Therefore, there is a drawback that the characteristics of the piezoelectric vibration gyro vary.

In the first example using the tuning fork vibrator,
The vibrating sound pieces 101, 101 'and 102, 102' must be joined at a right angle, which is a drawback that it is difficult to assemble them with high precision.

A technical object of the present invention is to obtain a piezoelectric vibrating gyro which has a simple structure, does not require a bonding step, and has a small variation in characteristics.

[0014]

According to the present invention, the outer peripheral surface of a piezoelectric ceramics cylinder is provided in a region of approximately two-thirds of the circumference of the piezoelectric ceramics cylinder parallel to the lengthwise direction of the piezoelectric ceramics cylinder. An odd number of strip electrodes are formed at equal intervals, every other strip electrodes are electrically connected to each other and subjected to polarization treatment as two terminals, and after the polarization treatment, the terminal including the strip electrodes in the central portion is grounded. A pair of strip-shaped electrodes that do not include the strip-shaped electrode in the central portion is electrically separated into two sets centering on the strip-shaped electrode in the central portion to form two input / output terminals. These two input / output terminals Is applied with an AC voltage for excitation having a frequency and a voltage amplitude which are equal to each other and which is approximately equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder, and at the same time, the differential voltage between these two input / output terminals is detected. Piezoelectric vibrating gyroscope is obtained, characterized in that the configuration was.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A piezoelectric vibrating gyroscope according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a main part of a piezoelectric vibrating gyroscope according to an embodiment of the present invention. In FIG. 1, reference numeral 10 indicates a piezoelectric ceramic cylinder used in the piezoelectric vibration gyro of the present invention. On the outer peripheral surface of this piezoelectric ceramic cylinder, an odd number of strip electrodes L parallel to the length direction are formed at equal intervals in a region of approximately two-thirds in the circumferential direction. These strip electrodes can be formed directly by curved surface screen printing, or can be formed by removing unnecessary portions of the electrodes formed on the entire surface by plating or the like by photoetching.

In order to simplify the description, an embodiment will be described in which the piezoelectric ceramic cylinder 10 has five strip electrodes. FIG. 2 shows the piezoelectric ceramic cylinder 10 shown in FIG.
On the outer peripheral surface of the five strip-shaped electrodes 11, 12, 13, 14,
FIG. 5 is an explanatory view showing the polarization direction in the cross-sectional direction of the piezoelectric ceramic cylinder 10 when the electrodes 15 and 15 are connected to each other and polarized, and the polarization direction is indicated by a dotted line. .

FIG. 3 is an explanatory view of the basic principle of the operation principle of the piezoelectric vibrating gyro of the present invention. In FIG. 3, the strip-shaped electrode gap portions of the piezoelectric ceramic cylinder 10 located between the strip-shaped electrodes 11, 12, 13, 14, and 15 are respectively denoted by G1,
Let G2, G3, and G4. Now, when an alternating voltage is applied to the gap G1, elongation strain occurs in the gap G1 when the direction of the applied electric field is equal to the direction of polarization, and when the direction of the applied electric field is opposite to the direction of polarization, the gap is generated. Shrinkage distortion occurs in G1. Therefore, when an AC voltage for excitation having a frequency substantially equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder 10 is applied to the strip electrode gap G1, the piezoelectric ceramic column 10 is substantially aligned with the center line of the strip electrode gap G1 due to the piezoelectric lateral effect. Flexural vibration occurs in the direction of the arrow along the plane including the central axis of the piezoelectric ceramic cylinder. In FIG. 3, when the piezoelectric ceramic cylinder 10 is vibrating in the arrow direction by another drive source, a voltage is generated between the strip electrodes 11-12 by the piezoelectric effect.

FIG. 4 shows that the strip-shaped electrodes 11 and 13 sandwiching the strip-shaped electrode 12 are connected to each other, and when an alternating voltage is applied between the strip-shaped electrodes 11 and 13 and the strip-shaped electrode 12, the piezoelectric ceramic column 10 is cross-sectioned. It is explanatory drawing which shows the state of the generated distortion and the vibration direction. As shown in FIG. 4, the polarities of the applied electric fields are set to be the same with respect to the respective polarization directions of the gap portion G1 portion and the gap portion G2, and are substantially equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder 10. When an alternating voltage for exciting a frequency is applied, the piezoelectric ceramic cylinder 10 is substantially aligned with the central axis of the piezoelectric ceramic cylinder as shown in FIG. 3 by the center lines of the strip electrode gaps G1 and G2 as indicated by solid arrows. A vibration driving force is generated in the same direction as the direction along the plane including the, and these are combined as shown in FIG. 5, so that the piezoelectric ceramic cylinder 10 substantially includes the center line of the strip electrode 12 and the center axis of the piezoelectric ceramic cylinder. Flexural vibration occurs in the direction of the arrow along the surface. In FIG. 4, when the piezoelectric ceramic cylinder 10 is vibrating in the direction of the arrow by another drive source, the strip electrode 12 is formed between the strip electrodes 11 and 12 and between the strip electrodes 12 and 13 by the piezoelectric effect.
In-phase voltage is generated with reference to.

FIG . 6 shows one of the strip electrodes 12 and 14 and the other.
AC voltage V between the other strip electrodes 11, 13, and 15
i is applied, and the other strip electrodes 11, 13, and 15 are connected to each other.
Ground. As a result, the piezoelectric ceramic cylinder 10
Distortion occurs in the directions of solid arrows X'and Y'on the cross section.
It These distortions X'and Y'are combined to create a white arrow.
A bending vibration indicated by R'is generated. On the contrary, apply external force
If this bending vibration is caused by
12 and 14 and the other strip electrodes 11, 13, and 15
AC voltage Vi is generated during the period. AC with reference to FIG.
Between the voltage Vi and the opposite phase Vi ′ is applied between the strip electrode 14 and the ground.
Is shown, and strain Y ″ is generated due to the piezoelectric effect.
To live. In this case, the piezoelectric ceramic cylinder 10 is outlined
Oscillates in the direction of the arrow R ″. Conversely, when external force is applied
If this vibration is caused more, one belt-shaped electric charge will be
An alternating voltage Vi is generated at the pole 12, and the other strip electrode 14
A voltage having a phase opposite to that of the AC voltage Vi is generated in the.

FIG . 8 shows a pressure sensor having the above-mentioned five strip electrodes.
Piezoelectric of the present invention constituted by using the electroceramic cylinder 10
It is an explanatory view for explaining the operating principle of the vibration gyro.
It In the embodiment shown in FIG. 8, a grounded band
Of the strip electrodes 11, 13 and 15 and the strip electrodes 12, 14
The above-mentioned AC voltage Vi is applied between them. This state is shown in Figure 6.
Since it is the same as,
It vibrates in the direction of arrow R '.

In this state, the piezoelectric ceramic cylinder 10 is
Rotate 90 ° in the direction of arrow A around these axes
And Coriolis force is generated in the direction perpendicular to the vibration direction of arrow R '.
The piezoelectric ceramic cylinder 10 is shaken in the direction of arrow C.
Move. In this case, the state shown in FIG.
The poles 12 and 14 have a vibration level in the direction of the arrow C.
The voltage of opposite phase with the level proportional to
Input of the differential amplifier 20 connected to the electrodes 12 and 14.
Input to the output terminal of the differential amplifier 20
The vibration level in the direction of arrow R'generated by the tilting force
Proportional voltage, i.e., a voltage proportional to the applied rotation speed
Pressure is output.

In the above description, the number of strip electrodes 11 to 15 is five.
Although the case where the number of strip electrodes is set to 3 is set to an odd number such as 3 and 7, a piezoelectric vibration gyro having the same principle can be obtained. However, in this case, it is necessary to form these strip electrodes on the outer circumferential surface of the piezoelectric ceramic cylinder 10 in a region of approximately two-thirds in the circumferential direction. This is because, in the piezoelectric vibrating gyroscope of the present invention, when the strip electrode is divided into two sets of strip electrodes on both sides of the strip electrode in the central portion, it is considered that the center line and the piezoelectric of each strip electrode set are equal to each other. The sum of two bending vibrations in the direction along the plane including the central axis of the ceramic cylinder 10 is combined to excite the driving vibration, and the difference between the two bending vibrations is combined to form the piezoelectric ceramic cylinder 10 The output voltage due to the Coriolis force when rotating about the axis is detected, and the vibration amplitude to be driven becomes larger when the area where each set of strip electrodes is formed is larger. If the region forming the is approximately one third or more of the circumferential direction, the angle between the two bending vibration directions for driving becomes 120 ° or more, and the amplitude of the combined vibration is Clear from law As is because smaller than the vibration amplitude of the one drive.

With respect to the number of strip electrodes, the capacitance increases and the impedance decreases as the number increases, which makes it advantageous to handle signals with respect to noise. It is difficult to raise the height, and the applied electric field acts only on the surface layer of the piezoelectric ceramic cylinder 10, which causes demerits such as a decrease in detection sensitivity.

[0024]

As described above, according to the present invention, since the piezoelectric vibrator uses the piezoelectric ceramic unit cylinder,
A vibrator with high dimensional accuracy can be obtained, and by using a material that is homogeneous in terms of material characteristics, it is possible to accurately match the characteristics of two orthogonal vibration modes, the structure is simple, and the adhesive is used. A piezoelectric vibration gyro that does not require variations in characteristics due to variations in the bonding position and the adhesive layer can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a piezoelectric ceramic cylinder 10 used in a piezoelectric vibrating gyroscope according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the piezoelectric ceramic cylinder 10 of FIG. 1 and explaining the direction of polarization in the cross-sectional direction.

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

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

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

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

FIG. 7 is an explanatory diagram for explaining the operation of the present invention.

FIG. 8 is an explanatory diagram for explaining the operation of the present invention.

FIG. 9 is a schematic view showing a first conventional example of a piezoelectric vibrating gyro.

FIG. 10 is a schematic view showing a second conventional example of a conventional piezoelectric vibration gyro.

FIG. 11 is a schematic view showing a third conventional example of a conventional piezoelectric vibration gyro.

FIG. 12 is an explanatory diagram for explaining the operation of the conventional piezoelectric vibration gyro.

FIG. 13 is an explanatory diagram for explaining the operation of the conventional piezoelectric vibration gyro.

FIG. 14 is an explanatory diagram for explaining the operation of the conventional piezoelectric vibration gyro.

FIG. 15 is an explanatory diagram for explaining the operation of the conventional piezoelectric vibration gyro.

[Explanation of symbols]

10 Piezoelectric Ceramics Cylinders 11 to 15 Strip Electrodes (L) 20 Differential Amplifiers 101, 101 ', 102, 102' Metallic Tone Vibrators 103, 104, 105, 106 Piezoelectric Ceramics Thin Plates 107 Metal Rectangular Pillars 108, 109 Piezoelectric Ceramics Thin Plates 110 Metal triangular prism 111, 112, 113 Piezoelectric ceramic thin plate

Front Page Continuation (72) Inventor Riki Masuko 6-7-1, Koriyama, Taichiro-ku, Sendai City, Miyagi Prefecture Tokin Co., Ltd. (56) Reference JP-A-5-79844 (JP, A) JP-A-4-106407 (JP, A) JP-A-2-82164 (JP, A) JP-A-3-130611 (JP, A) JP-A-2-266214 (JP, A)

Claims (1)

(57) [Claims] 1. An odd number of strip electrodes parallel to the length direction of the piezoelectric ceramic cylinder are formed on the outer peripheral surface of the piezoelectric ceramic cylinder at approximately two-thirds of the circumferential direction of the piezoelectric ceramic cylinder at equal intervals. Then, every other one of these strip electrodes is electrically connected to each other and is polarized as two terminals,
After the polarization treatment, the terminal including the central strip electrode is used as the ground electrode, and the group of strip electrodes not including the central strip electrode is electrically separated into two groups with the central strip electrode as the center. These two input / output terminals are applied with an AC voltage for excitation having a phase and a voltage amplitude equal to each other, and a frequency substantially equal to the resonance frequency of the bending vibration mode of the piezoelectric ceramic cylinder. A piezoelectric vibration gyro characterized by being configured to detect a differential voltage between two input / output terminals.