JP3147870B2 - Gyro sensor, driving method and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezo-vibration gyro sensor using ultrasonic vibration of a piezo-electric vibrator, and a method of manufacturing the gyro sensor, which is used for a camera shake correction of an automobile navigation system or a VTR integrated with a camera. About the method. This gyro sensor is a piezoelectric vibrating gyro sensor that has a simple structure and is easily supported by using energy confinement in a parallel electric field excitation type thickness shear vibration mode as a vibration mode of the piezoelectric vibrator.

[0002]

2. Description of the Related Art A piezoelectric vibrating gyro sensor using a piezoelectric vibrator utilizes a mechanical phenomenon that when a rotational angular velocity is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibration direction. Gyro sensor. In general, in a composite vibration system that can excite vibrations in two different directions that are orthogonal to each other, when the vibrator is rotated while one of the vibrations is excited, the force in the direction perpendicular to this vibration is generated by the action of the aforementioned Coriolis force Works, and the other vibration is excited. Since the magnitude of this vibration is proportional to the magnitude and the rotational angular velocity on the input side, for example, if the magnitude of the vibration on the input side is constant, the magnitude of the rotational angular velocity can be obtained from the magnitude of the output voltage. it can.

FIG. 13 is a perspective view showing the structure of a conventional piezoelectric vibration type gyro sensor as described above. This gyro sensor has a metal triangular prism 1 having a triangular cross section.
Electrodes are formed on both sides at substantially the center of the three surfaces of ten, and piezoelectric ceramic thin plates 111, 112, and 113, which are piezoelectric vibrators polarized in the thickness direction, are joined. The metal triangular prism 110 is capable of exciting bending vibration at substantially the same resonance frequency in a direction connecting each side and an apex facing the side. As shown in FIG. 14, when a voltage having a frequency substantially equal to the vibration frequency is applied to one piezoelectric ceramic thin plate 111, the surface to which the piezoelectric ceramic thin plate 111 is joined becomes uneven, as shown in FIG. Bending vibration.

When a voltage having the same amplitude and the same phase and a frequency substantially equal to the resonance frequency of the metal triangular prism 110 is applied to two adjacent piezoelectric ceramic thin plates 111 and 112, as shown in FIG. Is formed by combining bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 111 is bonded becomes uneven and bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 112 is bonded is uneven, and bonding the remaining piezoelectric ceramic thin plate 113 The bent surface vibrates in a direction in which it becomes uneven. In the state shown in FIG.
Metal triangular prism 110 in the length direction (Z-axis direction shown in FIG. 13)
17, the metal triangular prism 110 bends and vibrates in a direction perpendicular to the direction in which the surface to which the piezoelectric ceramic thin plate 113 is bonded becomes uneven as shown in FIG. 17 by the action of the Coriolis force.

On the other hand, when a voltage having the same amplitude and opposite phase and a frequency substantially equal to the resonance frequency of the metal triangular prism 110 is applied to two adjacent piezoelectric ceramic thin plates 111 and 112, as shown in FIG. Is a surface in which the bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 111 is bonded becomes uneven and the bending vibration in the direction in which the surface to which the piezoelectric ceramic thin plate 112 is bonded becomes uneven are combined, and the surface in which the remaining piezoelectric ceramic thin plate 113 is bonded Vibrates in a direction parallel to

[0006] As shown in FIG.
The bending vibration in the direction parallel to the ten piezoelectric ceramic thin plates 113 is obtained by applying voltages of the same amplitude and opposite phases to the piezoelectric ceramic thin plates 111 and 112.
Therefore, the metal triangular prism 110 is connected to the piezoelectric ceramic thin plate 1.
When the bending vibration is performed in a direction parallel to the direction of 13, the opposite effect generates voltages of the same amplitude and opposite phases on the piezoelectric ceramic thin plates 111 and 112. Then, for driving, one of the voltages applied to the piezoelectric ceramic thin plates 111 and 112 decreases correspondingly, and the other increases accordingly. Therefore, the voltage of the difference between the terminal voltages of the piezoelectric ceramic thin plates 111 and 112 is a voltage proportional to the rotational angular velocity of the metal triangular prism 110.

However, the gyro sensor using the triangular prism-shaped piezoelectric element has a drawback that, as shown in FIG. 13, the gyro sensor is generally placed vertically to increase its height because it detects the rotational angular velocity in the Z-axis direction. I have. The piezoelectric vibration type gyro sensor using such a bending vibration mode has a common drawback that the height is increased. Therefore, as shown in FIG. 18, a piezoelectric vibration structure of a parallel electric field excitation thickness shear energy trapping type is used. A gyro sensor has been proposed (Literature: JP-A-5-322580).

The gyro sensor of the piezoelectric vibration type has an energy trapping electrode 121 and an energy trapping electrode 1.
21 ′ are arranged to face each other, and the energy confinement electrode 122 and the energy confinement electrode 122 ′ are arranged to face each other. In this gyro sensor, the energy confinement electrodes 121, 121 'and the energy confinement electrode 12 are formed by confining the vibration energy near the energy confinement electrodes 121, 121' and the energy confinement electrodes 122, 122 '.
The peripheral portions other than 2,122 'hardly vibrate. Therefore, according to this gyro sensor, if only the outer peripheral portion is supported, high stability and high reliability can be realized.

In the gyro sensor, the energy trapping electrode 1 is connected via the drive electrode terminals 123 and 123 '.
When an AC voltage is applied to the electrodes 21 and 121 'at the parallel electric field excitation thickness shear vibration resonance frequency, the thickness slip vibration is excited only in the vicinity of the electrode by Coriolis force. The direction of the displacement at that time depends on the energy trapping electrode 1 that is being excited.
21, 121 ′ coincides with the facing direction, and becomes the x direction. In this state, the energy trapping detection electrode 12
Almost no output voltage is generated between 2,122 '. In this state, when a rotational angular velocity is applied to the gyro sensor around the Z axis (FIG. 18), the vibration direction (x
Direction), a Coriolis force is generated in a direction perpendicular to (i. The direction of the vibration is determined by the energy trapping detection electrodes 122 and 122 ′.
Therefore, a voltage proportional to the rotational angular velocity is generated between the energy trapping detection electrodes 122 and 122 ', and this voltage is detected at the terminal electrodes 124 and 124'.

FIG. 19 is a sectional view taken along the line ee 'of FIG. FIG. 20 shows a cross section ff ′ of FIG. In the case of the gyro sensor, as shown in FIG. 19, the polarization direction is properly defined in the thickness direction. However, with respect to the driving electric field direction, an electric field exists in the portion directly below the energy confinement electrodes 121 and 121 ′ in the thickness direction. I have. The portion where the polarization direction and the electric field direction are orthogonal to each other is only the central portion of the energy confinement electrodes 121 and 121 ′ shown by the gg ′ line portion in FIG. 19, and the electric field direction is determined by conformal mapping using an elliptic function. Can be obtained analytically.

On the other hand, in FIG.
Energy confinement electrodes 122, 1 used for detection
22 shows the central portion of the hh ′, as in FIG.
Only in the part shown by the line, the polarization vector and the electric field vector are orthogonal. Here, the parallel electric field excitation energy is confined by the energy confinement electrodes 121 and 121 ′ and the energy confinement electrode 12
This is so-called ordinary frequency reduction type energy confinement, which is established when the resonance frequency of the inner portion of 2,122 'becomes low. However, because of the above-described state, the polarization vector and the electric field vector are orthogonal to each other only in a very limited part, and it is impossible to achieve complete confinement of the parallel electric field excitation energy. For this reason, the above-mentioned conventional gyro sensor has a disadvantage that the driving and detection sensitivity of the gyro sensor is extremely small.

[0012]

As described above, first, in the conventional piezoelectric vibrating gyroscope shown in FIGS. 13 to 17, since the bending vibration mode of the columnar sound piece is used, the vibrator is not supported. The fixation must be made at the nodes of vibration. However, the nodes of vibration are points or lines that do not have a width or area theoretically.
The gyro characteristics deteriorated. Further, if the diameter of the support wire is reduced to reduce the influence of the support, there is a disadvantage that the durability against external vibrations and shocks deteriorates. Therefore, as described in the literature, an energy trapping type piezoelectric vibration gyro sensor has been proposed to minimize the adverse effect of external support, but as described above, complete energy trapping has not been achieved, and as a gyro, Performance had to be rather low sensitivity.

The present invention has been made to solve the above problems, and has a high sensitivity and a simple structure.
The purpose of the present invention is to provide a piezoelectric vibrating gyro that has little influence on the gyro characteristics due to taking out and supporting / fixing the input / output lead terminals, can be firmly supported, and has excellent vibration and shock resistance characteristics. .

[0014]

A gyro sensor according to the present invention comprises a plurality of laminated electrode-forming substrates made of a plurality of piezoelectric ceramics formed in a sheet shape, each of which has an electrode formed thereon. First and second detection electrodes disposed opposite to each other across a rectangular region at the center of the formation substrate, and opposed to each other across a rectangular region in a direction perpendicular to the direction in which the first and second detection electrodes oppose each other. And a first and a second driving electrode to which a predetermined voltage is applied. A cover made of a sheet-shaped piezoelectric ceramic is formed on the uppermost layer of the plurality of electrode forming substrates stacked. And a lower electrode for polarization and an upper electrode respectively formed in a region corresponding to a rectangular region on the lower surface of the lowermost layer and the surface of the cover of the plurality of laminated electrode forming substrates, and the first and second detection electrodes are provided. Pole The first and second driving electrodes were so are arranged in point symmetry about the rectangular area central portion in the same shape. With such a configuration, the first and second detection electrodes and the first and second drive electrodes allow the polarization vector uniformly polarized in the thickness direction of the laminated structure and the drive and detection electric field vectors. Can be made orthogonal.

Further, the gyro sensor according to the present invention comprises a plurality of laminated electrode forming substrates made of a plurality of piezoelectric ceramics formed in a sheet shape, and each of the electrode forming substrates has a central portion of the electrode forming substrate. A driving electrode disposed at a predetermined distance from the electrode forming substrate and symmetrical with respect to a center line of the electrode forming substrate; and a first driving electrode disposed opposite to the driving electrode.
And a second detection electrode, a cover made of a piezoelectric ceramic formed in a sheet shape is formed on the uppermost layer of the plurality of laminated electrode forming substrates, and the plurality of laminated electrode forming substrates are formed. A lower electrode for polarization and an upper electrode respectively formed in regions corresponding to the back surface of the lowermost layer and the drive electrode on the cover surface and the first and second detection electrodes, respectively. The detection electrodes were arranged in the same shape and symmetrically with respect to the center line.
With this configuration, the polarization vector uniformly polarized in the thickness direction of the laminated structure can be orthogonal to the driving and detection electric field vectors.

Further, according to a method of manufacturing a gyro sensor of the present invention, a first method includes preparing a plurality of electrode-formed substrates formed of a plurality of sheet-shaped piezoelectric ceramics and a cover formed of a sheet-shaped piezoelectric ceramic. A first and a second detection electrode disposed opposite to each other with a rectangular region at the center of the electrode formation substrate on each of the electrode formation substrates, and a direction perpendicular to the direction in which the first and the second detection electrodes are opposed to each other. A second step of forming first and second driving electrodes to which a predetermined voltage is applied, which are disposed opposite to each other with a rectangular area therebetween in a direction, and a plurality of electrode forming substrates on which the respective electrodes are formed are laminated. A third step of covering the uppermost layer of the plurality of electrode-formed substrates, and a fourth step of covering the lowermost layer of the plurality of electrode-formed substrates and a rectangular area on the surface of the cover. At least a fifth step of forming a lower electrode and the upper electrode for each polarization pass,
The first and second detection electrodes and the first and second drive electrodes are arranged in the same shape and point-symmetrically with respect to the center of the rectangular area. As a result, the polarization vector uniformly polarized in the thickness direction of the laminated structure and the driving and detection electric field vectors are formed by the formed first and second detection electrodes and the first and second driving electrodes. Can be made orthogonal.

Further, according to a method of manufacturing a gyro sensor of the present invention, a first method includes preparing a plurality of electrode-formed substrates formed of a plurality of sheet-shaped piezoelectric ceramics and a cover formed of a sheet-shaped piezoelectric ceramic. A driving electrode which is disposed on the electrode forming substrate at a predetermined distance from the center of the electrode forming substrate and is symmetrical with respect to the center line of the electrode forming substrate, and is disposed opposite to the driving electrode. Forming the first and second detection electrodes
A third step of laminating a plurality of electrode forming substrates on which the respective electrodes are formed, a fourth step of covering the uppermost layer of the plurality of laminated electrode forming substrates, and a plurality of laminated electrodes A fifth step of forming a lower electrode and an upper electrode for polarization in a region corresponding to a region between the drive electrode and the first and second detection electrodes on the back surface and the cover surface of the lowermost layer of the formation substrate, respectively. At least, the first and second detection electrodes were arranged in the same shape and symmetrically with respect to the center line. As a result, a polarization vector uniformly polarized in the thickness direction of the laminated structure and an electric field vector for driving and detection can be orthogonalized by each of the formed electrodes.

Further, in the driving method of the gyro sensor according to the present invention, the gyro sensor is constituted by a plurality of laminated electrode forming substrates made of a plurality of piezoelectric ceramics formed in a sheet shape,
Each of the electrode forming substrates has first and second detecting electrodes disposed opposite to each other with a rectangular region at the center of the electrode forming substrate interposed therebetween, and a direction perpendicular to the opposing direction of the first and second detecting electrodes. Are provided with first and second driving electrodes to which a predetermined voltage is applied, opposed to each other across a rectangular area, and are formed in a sheet shape on the uppermost layer of a plurality of laminated electrode forming substrates. A cover made of piezoelectric ceramics is formed, comprising an upper electrode and a lower electrode for polarization formed respectively in a region corresponding to a rectangular region on the back surface and the cover surface of the lowermost layer of a plurality of laminated electrode forming substrates, The first and second detection electrodes may be arranged in a gyro sensor having the same shape and arranged point-symmetrically with respect to a center of a rectangular area.
An AC voltage having a thickness-shear basic resonance frequency was applied to the driving electrode of (1). Thus, the maximum voltage sensitivity characteristic can be obtained by driving at the resonance frequency of the thickness-shear fundamental mode.

Further, in the driving method of the gyro sensor according to the present invention, the gyro sensor is constituted by a plurality of laminated electrode forming substrates made of a plurality of piezoelectric ceramics formed in a sheet shape,
Each of the electrode forming substrates is disposed at a predetermined distance from the center of the electrode forming substrate, and has a driving electrode having a shape symmetrical to the center line of the electrode forming substrate, and is disposed to face the driving electrode. A first and a second detection electrode are provided, and a cover made of a piezoelectric ceramic formed in a sheet shape is formed on an uppermost layer of the plurality of electrode forming substrates stacked,
An upper electrode and a lower electrode for polarization are respectively formed in regions corresponding to rectangular regions on the back surface of the lowermost layer and the surface of the cover of the plurality of stacked electrode forming substrates, and the first and second detection electrodes are the same. In the gyro sensor arranged symmetrically with respect to the center line in the shape of (1), an AC voltage having a thickness-shear basic resonance frequency is applied to the driving electrode.
Thus, the maximum voltage sensitivity characteristic can be obtained by driving at the resonance frequency of the thickness-shear fundamental mode.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 First, a first embodiment of the present invention will be described. FIG. 1 is a perspective view showing a configuration of the gyro sensor according to the first embodiment. This is a parallel electric field excitation thickness shear energy trap type gyro sensor using piezoelectric ceramics. In FIG. 1, the white arrows indicate the polarization direction. The gyro sensor according to the first embodiment is polarized in the thickness direction.

First, the configuration of the gyro sensor will be described. As shown in FIG. 1, the main body 10 of the gyro sensor includes internal electrodes 11 and 20, driving energy confining electrodes 12 and 12 ', and driving lead electrodes 13 and 13' extending therefrom. Are provided with the driving terminal electrodes 14 and 14 'connected to. In addition, the device includes detection energy confinement electrodes 15 and 15 ′, and when a rotational angular velocity Ω is applied around the Z axis in FIG. 1, the thickness shear vibration having a component in the Y axis direction generated by the Coriolis force is provided. To detect. Note that detection terminal electrodes 17, 17 'are connected to these via detection leads 16, 16'.

The green sheets 21 on which these are formed are arranged in multiple layers, and the internal electrodes 11 of each layer composed of the driving terminal electrodes 14 are connected in a bundle to form the driving electric terminals 18. This green sheet 21
Is a piezoelectric ceramic formed on a sheet. Further, the detection electric terminals 19 are formed by connecting the internal electrodes 20 of the respective layers composed of the detection terminal electrodes 17 so as to be bundled. The thickness shear vibration having a vibration energy component in the Y-axis direction caused by the Coriolis force is detected from the detection electric terminal 19. In FIG. 1, each electrode formed on the uppermost green sheet is mainly shown to avoid complexity of the drawing, and the uppermost layer is covered by a green sheet 21 on which no electrode is formed. Have been done. .

In the gyro sensor, as shown in FIG. 2, each of the green sheets 21 has the above-described driving energy trapping electrodes 12, 12 ', the driving lead electrodes 13, and
13 ', drive terminal electrodes 14, 14', detection energy confinement electrodes 15, 15 ', detection leads 16, 1
6 ′, detection terminal electrodes 17 and 17 ′ are respectively formed,
The green sheets 21 can be formed by laminating them by a well-known tape casting method in the same manner as a multilayer ceramic capacitor.

The driving energy confinement electrodes 12 and 12 ′ for each green sheet 21, the driving lead electrodes 13 and
13 ', drive terminal electrodes 14, 14', detection energy confinement electrodes 15, 15 ', detection leads 16, 1
6 ′, the detection terminal electrodes 17, 17 ′ are formed of Ag / P
It may be formed by screen printing using a printing paste in which fine particles of d are dispersed. The electrodes are formed at the same position and in the same shape and size on each green sheet 21. Then, the green sheet 21 on which the electrode is formed is laminated and pressed in the thickness direction.
By sintering at a temperature of 100 ° C. or less, the gyro sensor according to the first embodiment can be manufactured.

The gyro sensor according to the first embodiment is capable of trapping energy of a general frequency reduction type. In order to perform this energy confinement well,
The resonance frequency of the energy confinement part, that is, the energy confinement electrodes 12, 12 ', 15, 15' and the inner part thereof is changed by the energy confinement electrodes 12, 12 ', 1
It is essential that the resonance frequency is set sufficiently lower than the resonance frequency of the outer portion of 5, 15 '.

FIG. 3 shows a state in which polarizing electrodes 22 and 22 'are formed on the surface of the green sheet 21 on the upper surface and the back surface of the main body 10 of the gyro sensor shown in FIG. By using the polarization electrodes 22 and 22 'in this manner, only the energy confined portion can be polarized. After polarization, the energy confinement electrodes 12, 12 ', 1
Due to the 5,15 'mass effect and piezoelectric reaction,
The resonance frequency condition can be easily achieved.

In the formation of the polarizing electrodes 22 and 22 ', warping after sintering with the polarizing electrodes 22 and 22' by the tape casting method or the like is performed by polishing the plane parallel to the thickness direction. For the first time, it is possible to completely eliminate parallel electric field excitation energy and perform good confinement. In FIG. 3, all internal electrodes are omitted for the sake of simplicity. The gyro sensor according to the first embodiment has driving energy confinement electrodes 12, 12 ′, as shown in the cross-sectional view of FIG.
The driving lead electrodes 13, 13 ', the driving terminal electrodes 14,
The layer on which 14 'is formed is laminated. This FIG.
2 shows an aa ′ cross section of FIG. 1.

FIG. 4 also shows a driving electric terminal 18 ′ which is arranged to face the driving electric terminal 18.
In FIG. 4, the vector indicated by a white arrow indicates a polarization vector, and the vector indicated by a horizontal arrow indicates an electric field vector. As is clear from FIG.
In the gyro sensor in which a large number of internal electrodes are provided in piezoelectric ceramics in the first embodiment, the direction of polarization and the direction of the electric field are completely orthogonal to each other, which enables perfect energy confinement.

FIG. 5 shows a cross section bb 'of FIG. FIG. 5 also shows a detection positive terminal 19 ′ that is arranged opposite to the detection electric terminal 19. this is,
It is a terminal electrode for detecting angular velocity. In FIG. 5 as well, the vector indicated by the white arrow indicates the polarization vector, and the vector indicated by the horizontal arrow indicates the electric field vector.
As is apparent from FIG. 5, in the gyro sensor according to the first embodiment in which a large number of internal electrodes are provided in the piezoelectric ceramic, the polarization direction and the direction of the electric field are completely orthogonal to each other.
This enables perfect parallel electric field excitation energy confinement.

By the way, as the gyro sensor having the structure shown in FIG. 1, for example, the outer dimension is 22 m in length.
m, width 22 mm, and thickness 2.0 mm. In addition, length 2
As a piezoelectric ceramic (green sheet) on a large sheet having a size of 2 mm and a width of 22 mm, for example, NEPEC-31 (manufactured by Tokin Co., Ltd.) having excellent temperature characteristics may be used. Using the gyro sensor according to the first embodiment configured as above, the driving thickness-slip resonance frequency is 519 kHz, and the detecting thickness-slip resonance frequency is 523 k.
Hz, a voltage was applied to the driving terminal electrodes 18 and 18 ′, and driving was performed at the thickness-shear fundamental mode resonance frequency.
As shown in FIG. 6A, a vibration displacement parallel to the x-axis was obtained. Then, when rotated at an angular velocity Ω around the Z-axis in FIG. 1, due to Coriolis force, as shown in FIG.
Vibration displacement parallel to the Y axis is obtained, and the detection terminal electrodes 19, 1
Voltage could be detected from 9 '.

FIG. 7 shows the result of this detection. FIG. 7 shows a case where the lock-in amplifier is used for the angular velocity Ω (° / s).
The graph shows the voltage sensitivity characteristics when dB amplification is performed. 80d
It can be seen that practical output voltage characteristics with respect to the angular velocity are obtained in the piezoelectric amplification of about B. In the conventional gyro sensor, the piezoelectric amplification required about 100 dB. Therefore, according to the first embodiment, complete energy confinement was achieved, and as a result, the vibration was high enough to have a negligible peripheral portion. Therefore, a highly stable and highly reliable gyro sensor can be obtained.

Embodiment 2 Hereinafter, a second embodiment of the present invention will be described.
In the second embodiment, as shown in a perspective view of FIG. 8, a driving energy trapping electrode 31 and a lead drawn out therefrom are placed on a piezoelectric ceramic (green sheet) on a sheet constituting a gyro sensor 30. An electrode 32 and a terminal electrode 33 connected to the electrode 32 are formed. Then, on each piezoelectric ceramic layer, an internal electrode 34 having the same shape as the electrodes is formed, respectively, to form a multilayer structure. Further, on the end face of the multilayer structure, a driving electric terminal 35 is formed so as to bundle the terminal electrodes 33 of the internal electrodes 34.

On each piezoelectric ceramic layer, c
The detection energy trapping electrodes 36 and 37 are formed symmetrically with respect to the line c ′ and have the same shape and dimensions. Then, the detection energy trapping type electrodes 36, 37 are connected to the detection energy trapping electrodes 36, 37 via lead electrodes 38, 39, respectively.
Terminal electrodes 40 and 41 are connected. In FIG. 8, thick white arrows indicate the polarization direction, and Ω indicates the angular velocity around the Z axis.

FIG. 9 shows a dd ′ section of the gyro sensor 30. As shown in FIG. 9, on the side surface opposite to the surface on which the driving positive terminal 35 is formed, the angular velocity detecting electric terminals 35 formed so as to bundle the respective terminal electrodes 41 formed on the respective piezoelectric ceramic layers. 'Is provided. In FIG. 9, thick white arrows indicate polarization vectors, and thin arrows indicate electric field vectors. As described above, also in the second embodiment, the polarization vector and the electric field vector are completely orthogonal to each other, and the parallel electric field thickness-shear mode energy confinement is completely achieved.

The gyro sensor according to the second embodiment can be manufactured by the laminated ceramics technology based on the tape casting method, similarly to the first embodiment. That is, as shown in FIG.
In addition, the above-described driving energy trapping electrode 31, lead electrode 32, driving terminal electrode 33, energy trapping electrodes 36 and 37, lead electrodes 38 and 39, and terminal electrode 4
0, 41, respectively, and the green sheets 42
Can be formed by laminating by a well-known tape casting method in the same manner as a multilayer ceramic capacitor. In addition, each electrode may be formed by screen printing using a printing paste in which Ag / Pd particles are dispersed.

With the current accuracy, the stacking deviation of each green sheet (piezoelectric ceramic layer) can be easily suppressed to 50 μm or less. By laminating these green sheets, thermocompression bonding, and then firing at a temperature of 1100 ° C. or lower, the piezoelectric gyro sensor shown in FIG. 8 can be realized. Further, as shown in FIG. 3, the partial electrodes 22 and
22 ′ is formed and polarized in the thickness direction by applying a high DC voltage. As a result, the energy confinement electrodes 31, 3
The complete parallel electric field excitation energy confinement can be achieved by lowering the resonance frequency of the 6, 37 portions and the inner portions of the electrodes from the peripheral portions by the mass effect and the piezoelectric reaction of the electrodes. .

In the gyro sensor according to the second embodiment, similarly to the first embodiment, the gyro sensor shown in FIG.
When the angular velocity Ω about the axis is zero, the thickness shear vibration mode is only in the x direction, and the potential difference between the energy confinement electrode 36 and the energy confinement electrode 37 is zero. However, when an angular velocity Ω around the Z axis is generated, a Coriolis force causes a potential difference between the energy trapping electrode 36 and the energy trapping electrode 37, and this potential difference is proportional to Ω. That is, by connecting the terminal electrodes 40 and 41 to a differential amplifier and amplifying the potential difference, a practical angular velocity sensor can be obtained.

The gyro sensor according to the second embodiment has the same dimensions and dimensions as those of the gyro sensor according to the first embodiment.
That is, it may be formed to have a length of 22 mm, a width of 22 mm, and a thickness of 2.0 mm. In addition, the electrodes may be formed by laminating and sintering by the above-described method, forming electrodes for polarization, and then performing parallel plane polishing to flatten the electrodes for polarization. As for the performance, the same characteristics as the output voltage with respect to the angular velocity Ω shown in FIG. 7 of the first embodiment can be obtained by the amplification of the differential amplifier of 80 dB. Note that the same NEPEC-31 (manufactured by Tokin Co., Ltd.) as in Embodiment 1 was used as the piezoelectric ceramic material used as the green sheet.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described.
In the third embodiment, as shown in FIG. 11A, a gyro sensor manufactured in exactly the same manner as in the first embodiment described above is processed into a convex shape. That is, as shown in the cross-sectional view of FIG. 11B, when the cross section is viewed, it is formed in a state of a convex lens. Note that FIG.
, The same reference numerals as in FIG. 1 are used. However, in the third embodiment, a lead electrode 43 newly formed by a sputtering method or the like and a terminal electrode 44 newly formed by a sputtering method are provided.
These electrodes can also be formed by using, for example, a Cr / Pt / Au vapor deposition method or a plating method.

The processing into the convex shape may be performed by polishing. Here, in the third embodiment, NEPEC-31 (manufactured by Tokin Co., Ltd.) is used as the piezoelectric ceramic sheet, and the substrate on the sheet has a length of 13 m.
m and a width of 13 mm. After laminating the piezoelectric ceramic layers on which the respective electrodes were formed and processing them into a convex shape, the thickest portion was 2.0 mm.
Further, the energy trapping electrode 1 of the third embodiment
The dimensions of 2, 12 ', 15, and 15' are exactly the same as in the first embodiment. FIG. 11B shows a section taken along aa ′ in FIG. 1A.

In the third embodiment, since the outer shape of the gyro sensor is processed into a convex shape, the thickness shear vibration is attenuated more than the normal exponential curve in the portion outside the energy trapping portion. . Therefore, even if a piezoelectric ceramic plate (green sheet) having a small area is used as in the gyro sensor according to the third embodiment, the amplitude of the thickness shear vibration is almost zero in the peripheral portion, and highly stable and reliable support is possible. Was confirmed. The performance of the gyro sensor was almost the same as that shown in FIG. 7 when the detected output voltage was amplified by only 80 dB.

Embodiment 4 Hereinafter, a fourth embodiment of the present invention will be described.
In the fourth embodiment, as shown in FIG. 12A, a gyro sensor manufactured in exactly the same manner as in the above-described second embodiment is processed into a convex shape. That is, as shown in the cross-sectional view of FIG. 12B, when the cross section is viewed, it is formed in a state of a convex lens. FIG.
, The same reference numerals as in FIG. 8 are used.

However, in the fourth embodiment, a lead electrode 45 newly formed by a sputtering method or the like and a terminal electrode 46 also newly formed by a sputtering method are provided. These electrodes can also be formed by using, for example, a Cr / Pt / Au vapor deposition method or a plating method. Further, in FIG. 12A, the angular velocity detecting electric terminals 3 formed so as to bundle the respective terminal electrodes 40 formed on the respective piezoelectric ceramic layers.
5 "is also shown.

The processing into the convex shape is the same as in the third embodiment described above, and may be performed by polishing. Here, also in the fourth embodiment, NEPEC-31 (manufactured by Tokin Co., Ltd.) is used as the piezoelectric ceramic sheet, and the substrate on the sheet has a length of 13 mm and a width of 13 mm.
And After laminating the piezoelectric ceramic layers on which the respective electrodes were formed and processing them into a convex shape, the thickest portion was 2.0 mm. Further, the dimensions of the driving energy confinement electrode 31 and the detection energy confinement electrodes 37 and 38 of the fourth embodiment are exactly the same as those of the second embodiment. FIG. 12B shows a dd ′ section in FIG. 8A.

Also in the fourth embodiment, since it is polished into a convex shape, the thickness-shear vibration is attenuated in a portion outside the energy trapping portion and in the portion outside the energy trapping portion. This is much larger than the exponential curve. Then, the amplitude of the thickness shear vibration became almost zero in the peripheral portion of the gyro sensor, and it was confirmed that highly stable and highly reliable support and fixing were possible. In the performance of the gyro sensor, a practical output signal was obtained when the detection voltage was amplified by only 80 dB, and the performance almost as shown in FIG. 7 was obtained.

[0046]

As described above, according to the present invention, a plurality of electrode-forming substrates formed of a plurality of piezoelectric ceramics formed in a sheet shape are stacked, and each of the electrode-forming substrates is provided with an electrode-forming substrate. The first and second detection electrodes are disposed opposite each other across the rectangular region at the center of the substrate, and the first and second detection electrodes are disposed opposite each other across the rectangular region in a direction perpendicular to the opposing direction of the first and second detection electrodes. A first and a second drive electrode to which a predetermined voltage is applied are provided, and a cover made of a sheet-shaped piezoelectric ceramic is formed on the uppermost layer of the plurality of electrode forming substrates stacked. A lower electrode for polarization and an upper electrode respectively formed in regions corresponding to rectangular regions on the back surface of the lowermost layer and the surface of the cover of the plurality of electrode forming substrates, and the first and second electrodes are provided.
The first and second drive electrodes are arranged in the same shape and point-symmetrically with respect to the center of the rectangular area.

Further, it is composed of a plurality of laminated electrode forming substrates made of a plurality of piezoelectric ceramics formed in a sheet shape, and each of the electrode forming substrates is separated from the center of the electrode forming substrate by a predetermined distance. A plurality of electrodes are provided, including a driving electrode arranged and symmetrical with respect to a center line of the electrode forming substrate, and first and second detection electrodes arranged opposite to the driving electrode. A cover made of a piezoelectric ceramic formed in a sheet shape is formed on the uppermost layer of the formation substrate, and the driving electrodes on the back surface and the cover surface of the lowermost layer of the plurality of electrode formation substrates are stacked. A lower electrode for polarization and an upper electrode respectively formed in a region corresponding to the first and second detection electrodes, wherein the first and second detection electrodes have the same shape and are arranged symmetrically with respect to the center line. Like It was.

With this configuration, the polarization vector uniformly polarized in the thickness direction of the laminated structure can be orthogonal to the driving and detection electric field vectors. As a result, the present invention has a high sensitivity and a simple structure, has little influence on the gyro characteristics by taking out and supporting / fixing the input / output lead terminals, and can firmly support the vibration / shock resistance. It has an excellent effect that a piezoelectric vibrating gyroscope having excellent characteristics can be provided.

Further, according to the present invention, a first step of preparing a plurality of electrode-formed substrates made of a plurality of sheet-shaped piezoelectric ceramics and a cover made of a sheet-shaped piezoelectric ceramics; Each of the first and second detection electrodes is opposed to each other with the rectangular region at the center of the electrode forming substrate therebetween, and the rectangular region is sandwiched in a direction perpendicular to the direction in which the first and second detection electrodes face each other. The first and the second, which are arranged opposite to each other and are applied with a predetermined voltage,
A second step of forming a plurality of electrode forming substrates, a third step of stacking a plurality of electrode forming substrates on which the respective electrodes are formed, and a fourth step of covering a top layer of the stacked plurality of electrode forming substrates. And forming a lower electrode and an upper electrode for polarization in regions corresponding to rectangular regions on the back surface and the cover surface of the lowermost layer of the plurality of electrode forming substrates, respectively.
And the first and second detection electrodes and the first and second drive electrodes are arranged in the same shape and point-symmetrically about the center of the rectangular area.

Further, a first step of preparing a plurality of electrode-formed substrates made of a plurality of sheet-shaped piezoelectric ceramics and a cover made of a sheet-shaped piezoelectric ceramics is provided. A drive electrode arranged at a predetermined distance from the center of the formation substrate and symmetrical with respect to the center line of the electrode formation substrate; and first and second detection electrodes arranged opposite to the drive electrode A second step of forming a plurality of electrode forming substrates on which the respective electrodes are formed, a fourth step of covering the uppermost layer of the plurality of stacked electrode forming substrates, A lower electrode and an upper electrode for polarization are respectively formed in regions corresponding to between the driving electrode and the first and second detection electrodes on the lower surface of the lowermost layer and the cover surface of the plurality of laminated electrode forming substrates. At least with 5 of the step, first
The second detection electrode and the second detection electrode have the same shape and are arranged symmetrically with respect to the center line.

As a result, a polarization vector uniformly polarized in the thickness direction of the laminated structure and an electric field vector for driving and detection can be orthogonalized by each of the formed electrodes. As a result, according to the present invention, the structure is simple with high sensitivity, the influence on the gyro characteristic by taking out and supporting / fixing the lead terminals for input / output is small, and it is possible to support firmly, It is possible to provide a piezoelectric vibrating gyroscope having excellent impact resistance.

According to the present invention, a plurality of electrode-forming substrates are formed by laminating a plurality of piezoelectric ceramics formed in a sheet shape. Each of the electrode-forming substrates has a rectangular area at the center of the electrode-forming substrate. A first and a second detection electrode, which are opposed to each other, and a predetermined voltage, which is opposed to the first and second detection electrodes across a rectangular area in a direction perpendicular to the facing direction of the first and second detection electrodes, are applied. A cover made of a sheet-shaped piezoelectric ceramic is formed on the uppermost layer of the plurality of electrode forming substrates provided with the first and second driving electrodes, and the plurality of stacked electrodes are formed. An upper electrode and a lower electrode for polarization formed on the lower surface of the lowermost layer of the formation substrate and regions corresponding to the rectangular regions on the surface of the cover, respectively, the first and second detection electrodes; Drive In the gyro sensor having the same shape and arranged symmetrically with respect to the center of the rectangular area at the center, an AC voltage having a thickness-slip basic resonance frequency is applied to the first and second driving electrodes. .

Further, it is composed of a plurality of laminated electrode forming substrates made of a plurality of piezoelectric ceramics formed in a sheet shape, and is disposed on each of the electrode forming substrates at a predetermined distance from the center of the electrode forming substrate. And a driving electrode having a shape symmetrical with respect to a center line of the electrode forming substrate, and first and second detection electrodes arranged to face the driving electrode, and forming a plurality of stacked electrode formations. A cover made of a piezoelectric ceramic formed in a sheet shape is formed on the uppermost layer of the substrate, and is formed on the back surface of the lowermost layer of the plurality of electrode-formed substrates stacked and in regions corresponding to rectangular regions on the surface of the cover, respectively. Comprising an upper electrode and a lower electrode for polarization,
In the gyro sensor in which the first and second detection electrodes have the same shape and are arranged line-symmetrically with respect to the center line, an AC voltage having a thickness-shear basic resonance frequency is applied to the drive electrode.

In the gyro sensor driving method according to the present invention, the maximum voltage sensitivity characteristic can be obtained by driving the gyro sensor at the resonance frequency in the thickness-shear fundamental mode. As a result, according to the present invention, the structure is simple with high sensitivity, the influence on the gyro characteristic by taking out and supporting / fixing the lead terminals for input / output is small, and it is possible to support firmly, It is possible to provide a piezoelectric vibrating gyroscope having excellent impact resistance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a gyro sensor according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a method for manufacturing the gyro sensor of FIG.

FIG. 3 is a configuration diagram showing a schematic configuration of a gyro sensor according to the first embodiment.

FIG. 4 is a configuration diagram showing a cross section of the gyro sensor of FIG. 1;

FIG. 5 is a configuration diagram showing a cross section of the gyro sensor of FIG. 1;

FIG. 6 is an explanatory view showing thickness shear vibration on a driving side (a).
FIG. 7B is an explanatory diagram (b) showing thickness-shear vibration on the detection side. .

FIG. 7 is a characteristic diagram showing characteristics of the gyro sensor according to the first embodiment shown in FIGS. 1 and 3;

FIG. 8 is a perspective view illustrating a configuration of a gyro sensor according to a second embodiment of the present invention.

FIG. 9 is a configuration diagram showing a cross section of the gyro sensor of FIG. 8;

FIG. 10 is an explanatory diagram illustrating a method for manufacturing the gyro sensor in FIG.

FIGS. 11A and 11B are a plan view and a sectional view, respectively, showing a configuration of a gyro sensor according to a third embodiment of the present invention.

FIG. 12 is a plan view (a) and a cross-sectional view (b) showing a configuration of a gyro sensor according to a fourth embodiment of the present invention.

FIG. 13 is a perspective view showing a configuration of a conventional gyro sensor.

FIG. 14 is an explanatory diagram illustrating the operation of the gyro sensor in FIG.

FIG. 15 is an explanatory diagram illustrating the operation of the gyro sensor in FIG. 13;

FIG. 16 is an explanatory diagram illustrating the operation of the gyro sensor in FIG.

FIG. 17 is an explanatory diagram illustrating the operation of the gyro sensor in FIG.

FIG. 18 is a perspective view showing the configuration of another conventional gyro sensor.

19 is an explanatory diagram showing a driving state of the gyro sensor of FIG.

20 is an explanatory diagram showing a driving state of the gyro sensor of FIG.

[Explanation of symbols]

Reference numeral 10: body, 11, 20: internal electrode, 12, 12 ': drive energy trapping electrode, 13, 13': drive lead electrode, 14, 14 ': drive terminal electrode, 15, 1
5 ': Energy trapping electrode for detection, 16, 16' ...
Detection lead, 17, 17 '... detection terminal electrode, 18 ...
Driving electric terminals, 19 ... Detection electric terminals.

Continuation of front page (56) References JP-A-5-264281 (JP, A) JP-A-7-332983 (JP, A) JP-A-10-260044 (JP, A) JP-A-11-37760 (JP) , A) JP-A-58-160809 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 19/56 G01P 9/04

Claims (10)

(57) [Claims] 1. An electrode forming substrate comprising a plurality of stacked piezoelectric ceramics formed in a sheet shape, wherein each of the electrode forming substrates sandwiches a rectangular region at the center of the electrode forming substrate. A first and a second detection electrode disposed to face each other, and a predetermined voltage applied across the rectangular region in a direction perpendicular to the direction in which the first and second detection electrodes face each other is applied. A first and a second drive electrode are provided; a cover made of a sheet-shaped piezoelectric ceramic is formed on the uppermost layer of the plurality of laminated electrode forming substrates; A lower electrode for polarization and an upper electrode respectively formed in a region corresponding to the rectangular region on the back surface of the lowermost layer and the surface of the cover of the electrode forming substrate, wherein the first and second detection electrodes or A gyro sensor, wherein the first and second drive electrodes are arranged in the same shape and point-symmetrically with respect to the center of the rectangular area. 2. An electrode forming substrate comprising a plurality of stacked piezoelectric ceramics formed in a sheet shape, wherein each of the electrode forming substrates is separated from a central portion of the electrode forming substrate by a predetermined distance. A driving electrode having a shape symmetrical with respect to a center line of the electrode forming substrate, and first and second detection electrodes disposed so as to face the driving electrode. A cover made of a piezoelectric ceramic formed in a sheet shape is formed on the uppermost layer of the plurality of electrode forming substrates, and the lower surface of the lowermost layer of the stacked plurality of electrode forming substrates and the drive surface of the cover are formed. A lower electrode and an upper electrode for polarization formed respectively in regions corresponding to the electrodes and the first and second detection electrodes, wherein the first and second detection electrodes have the same shape. Previous A gyro sensor which is arranged symmetrically with respect to the center line. 3. The gyro sensor according to claim 1, wherein the laminated structure in which the plurality of electrode forming substrates are laminated is formed such that the thickness in the laminating direction becomes smaller toward the outer periphery of the electrode substrate. A gyro sensor characterized by the following. 4. The gyro sensor according to claim 1, wherein the upper electrode and the lower electrode are formed flat on the surface of the cover and the back surface of the lowermost layer, respectively. Gyro sensor. 5. A first step of preparing a plurality of electrode-formed substrates made of a plurality of piezoelectric ceramics formed in a sheet shape and a cover made of a piezoelectric ceramic formed in a sheet shape; First and second detection electrodes arranged opposite to each other with a rectangular area at the center of the electrode forming substrate interposed therebetween, and the rectangular area sandwiched in a direction perpendicular to the direction in which the first and second detection electrodes are opposed to each other. A second step of forming first and second drive electrodes to which a predetermined voltage is applied, which is disposed opposite to the first electrode, and a third step of stacking a plurality of electrode forming substrates on which the respective electrodes are formed A fourth step of covering the uppermost layer of the plurality of stacked electrode forming substrates with the cover; and a back surface of a lowermost layer of the stacked plurality of electrode forming substrates and the rectangular area of the cover surface. At least a fifth step of forming a lower electrode and an upper electrode for polarization in the region, wherein the first and second detection electrodes and the first and second drive electrodes are the same. A method for manufacturing a gyro sensor, wherein the gyro sensors are arranged in a point-symmetric manner with respect to the center of the rectangular area. 6. A first step of preparing a plurality of electrode forming substrates made of a plurality of piezoelectric ceramics formed in a sheet shape and a cover made of a piezoelectric ceramic formed in a sheet shape; A driving electrode disposed at a predetermined distance from a center portion of the electrode forming substrate and symmetrical with respect to a center line of the electrode forming substrate; and first and second driving electrodes disposed opposite to the driving electrode. A second step of forming a plurality of detection electrodes, a third step of laminating a plurality of electrode formation substrates on which the respective electrodes are formed, and the cover being formed on the uppermost layer of the plurality of electrode formation substrates. A fourth step of covering, and covering the lower surface of the lowermost layer of the stacked plurality of electrode forming substrates and the cover surface with a region corresponding to a position between the driving electrode and the first and second detection electrodes. Yes A fifth step of forming a lower electrode and an upper electrode for polarization, wherein the first and second detection electrodes are arranged in the same shape and symmetrically with respect to the center line. Manufacturing method of sensor. 7. The method for manufacturing a gyro sensor according to claim 5, wherein, after the fourth step, the stacked structure in which the plurality of electrode-formed substrates are stacked is stacked in a direction in which the outer periphery of the electrode substrate is stacked. A method for manufacturing a gyro sensor, wherein the polishing is performed so that the thickness of the gyro sensor is reduced. 8. The method for manufacturing a gyro sensor according to claim 5, wherein the upper electrode and the lower electrode are formed flat on the cover surface and the lower surface of the lowermost layer, respectively. A method for manufacturing a gyro sensor. 9. An electrode forming substrate comprising a plurality of stacked piezoelectric ceramics formed in a sheet shape, wherein each of the electrode forming substrates sandwiches a rectangular region at the center of the electrode forming substrate. A first and a second detection electrode disposed to face each other, and a predetermined voltage applied across the rectangular region in a direction perpendicular to the direction in which the first and second detection electrodes face each other is applied. A first and a second drive electrode are provided; a cover made of a sheet-shaped piezoelectric ceramic is formed on the uppermost layer of the plurality of laminated electrode forming substrates; An upper electrode for polarization and a lower electrode respectively formed in a region corresponding to the rectangular region on the back surface of the lowermost layer and the surface of the cover of the electrode forming substrate, wherein the first and second detection electrodes or A gyro sensor in which the first and second driving electrodes are arranged in the same shape and point-symmetrically with respect to the center of the rectangular area, wherein the first and second driving electrodes have A method for driving a gyro sensor, comprising applying an alternating voltage having a resonance frequency. 10. An electrode forming substrate comprising a plurality of laminated piezoelectric substrates formed of a plurality of piezoelectric ceramics formed in a sheet shape, wherein each of the electrode forming substrates is separated from a central portion of the electrode forming substrate by a predetermined distance. A driving electrode having a shape symmetrical with respect to a center line of the electrode forming substrate, and first and second detection electrodes disposed so as to face the driving electrode. A cover made of a piezoelectric ceramic formed in a sheet shape is formed on the uppermost layer of the plurality of electrode forming substrates, and the lower surface of the lowermost layer of the stacked plurality of electrode forming substrates and the rectangular area of the cover surface are formed. A first electrode and a second electrode, each of which has the same shape and is arranged symmetrically with respect to the center line in the same shape. A driving method of a gyro sensor, wherein an AC voltage having a thickness-shear basic resonance frequency is applied to the driving electrode.