JP2003033055A - Piezoelectric converting element and device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient piezoelectric converting element which can be oscillated in various oscillation modes, and a device such as an actuator or the like using this piezoelectric converting element. SOLUTION: A band-shaped electrode 2 is made at roughly half of the surface of the piezoelectric element using piezoelectric ceramics, and a flat electrode 13 is made at roughly half of the rear, and it is folded in two and is rolled up into a columnar body. The end face of the columnar body is divided into a plurality of regions 16a-16d in circumferential direction, divided terminals A1-A4 are connected to the plural band-shaped electrodes 12 belonging to each divided region, and grounding electrode terminals G are connected to the flat electrode 13. Thus, a piezoelectric converting element which is equipped with the plural band-shaped electrodes 12 in the circumferential direction of the columnar body, that is, a piezoelectric converting element 20 with circumferentially divided electrode is completed. When AC voltage is applied selectively to the divided electrode, elastic oscillation in axial direction shown by an axis I, bending oscillation within a plane X, a plane Y, and a plane Z including the axis I, elliptic oscillation, etc., occur in the element 20, and it is applicable to a piezoelectric oscillation gyro oscillator, an actuator, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric conversion element and an actuator using the same.

[0002]

2. Description of the Related Art An electrode for vibration is formed on a piezoelectric conversion element,
A piezoelectric vibrating gyro oscillator that applies bending voltage or elliptical vibration to a piezoelectric conversion element by applying an AC voltage to this electrode, or an angular velocity detector that detects the rotational angular velocity by applying the bending vibration generated in this oscillator, There is known a piezoelectric vibration actuator that drives a driven body by applying elliptical vibration generated in the vibrator.

For example, in Japanese Unexamined Patent Publication No. 8-43110, a piezoelectric vibrating gyro vibration is formed by forming a plurality of strip-shaped vibrating electrodes along the axial direction on the surface of a piezoelectric transducer having a columnar body made of piezoelectric ceramics. A child element is configured to apply an AC voltage to its electrodes to generate bending vibration in the piezoelectric conversion element, and the Coriolis force generated based on the bending vibration causes the voltage signal generated in the electrode of the piezoelectric conversion element to rotate the object. What detects an angular velocity is disclosed.

A rotor is pressed against such a piezoelectric vibrating gyro oscillator, and the rotor is rotated by elliptic vibration generated by applying an AC voltage to the oscillator, thereby driving the driven body. Eta etc. are known.

[0005]

Since the conventional piezoelectric vibrating gyro oscillator is a simple angular oscillator, it is difficult to generate flexural vibration, and also as a detector for detecting a rotational angular velocity. The signals used from the electrodes used were also weak, and the signal-to-noise ratio (S / N ratio) was poor.

Further, since the piezoelectric transducer used in the piezoelectric vibrating gyroactuator is of a single layer, there is a disadvantage that a high output cannot be obtained.

As a measure for improving the S / N ratio and obtaining a high output, a laminated piezoelectric conversion element in which a plurality of piezoelectric elements constituting a piezoelectric vibrating gyro oscillator are made as thin as possible is laminated. Although it can be solved by using it, on the other hand, since such a laminated piezoelectric conversion element does not easily generate vibration in the bending vibration mode, the laminated piezoelectric conversion element is used as a piezoelectric vibration gyro oscillator. It has been deemed unsuitable to do.

[0008]

The present invention achieves the above object. According to the invention of claim 1, a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material is sandwiched between a plurality of strip electrodes and a full-scale electrode. The piezoelectric conversion element is characterized in that it is laminated and rolled up to form a columnar body or a cylindrical body.

The columnar body or tubular body is divided into at least two or more regions along the circumferential direction thereof, and the plurality of strip electrodes are divided into one of the divided regions. Configured to belong to one.

The end portions of the plurality of strip electrodes are exposed on one end surface of the columnar body or the cylindrical body in the central axis direction,
The end portion of the whole surface electrode is exposed on the end surface in the direction opposite to the end surface on which the plurality of strip electrodes are exposed.

A common power supply terminal for supplying power to the strip electrodes belonging to each of the divided areas is provided in each of the plurality of divided areas, and the power supply terminal is exposed at the end surface of the columnar body or the cylindrical body. It is connected to the end of the strip electrode.

The plurality of strip electrodes are arranged parallel to the axial direction of the columnar body or the cylindrical body.

In addition, the plurality of strip electrodes may be arranged so as to be inclined with respect to the axial direction of the columnar body or the cylindrical body.

Further, the plurality of strip electrodes are divided into at least two or more groups, and the strip electrodes belonging to one group and the strip electrodes belonging to the other group are the columnar body or the tubular body. You may incline and arrange | position at different angles with respect to the axial direction of.

According to an eighth aspect of the present invention, a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material is laminated and wound so as to be sandwiched between a plurality of strip electrodes and a whole surface electrode, and is rolled up to form a columnar body or a cylindrical body. A piezoelectric vibrator using an element, wherein the columnar body or the tubular body is divided into at least two or more regions along its circumferential direction, and the plurality of strip electrodes are divided into the plurality of regions. And applying a voltage selectively between a strip electrode or a strip electrode of the whole region and a full surface electrode, which is configured to belong to one of the divided regions and is excited. The piezoelectric transducer capable of vibrating in a plurality of vibration modes is characterized in that the piezoelectric conversion element generates expansion mode vibration, bending mode vibration, or elliptical mode vibration.

According to a ninth aspect of the present invention, a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material is laminated and wound so as to be sandwiched between a plurality of strip electrodes and a full-scale electrode, and rolled up to form a columnar body or a cylindrical body. A piezoelectric vibrating gyroscope detector using an element, wherein the columnar body or the tubular body is divided into at least two or more regions along the circumferential direction thereof, and the plurality of strip electrodes are divided into the plurality of regions. Excitation by selectively applying a voltage between the strip electrodes or the strip electrodes of the entire region and the whole electrode which are configured to belong to one of the divided regions. By doing so, expansion / contraction mode vibration, bending mode vibration, or elliptical mode vibration is generated in the piezoelectric conversion element, and the signal voltage generated between the strip electrode and the full-scale electrode belonging to the region to which no voltage is applied is piezoelectrically converted. The piezoelectric vibrating gyro detector and detecting as an angular velocity signal applied to the child.

According to a tenth aspect of the invention, the piezoelectric vibrator according to the eighth aspect and a rotating body pressed against the piezoelectric vibrator are provided, and the piezoelectric vibrator vibrates in an elliptical mode to perform the rotation. It is a piezoelectric actuator characterized by rotating a body.

According to an eleventh aspect of the present invention, the piezoelectric vibrator according to the eighth aspect includes a spherical rotor that is pressed against the piezoelectric vibrator and is rotatably supported. The piezoelectric actuator is characterized in that the rotating body is freely rotated by generating elliptical mode vibration.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. First, the piezoelectric conversion element according to the first embodiment and the method for manufacturing the same will be described with reference to FIGS.

1A and 1B are perspective views of a piezoelectric element as a material forming a piezoelectric conversion element. FIG. 1A shows the front surface and FIG. 1B shows the rear surface. Piezoelectric element 11
As the material of PZT (PbZrO ₃ · PbTi
Piezoelectric ceramics whose main component is O ₃ ) is used. This ceramic powder is mixed with a solvent, a dispersant, a binder, a plasticizer, etc., and is made into a uniform flat surface by using a blade or the like and drawn to a constant thickness, for example, 20 to 100 μm. The solvent is evaporated and dried to form a flexible sheet called a green sheet. In the explanation below,
It is called a piezoelectric element.

On the front surface 11a of the piezoelectric element, a plurality of strip-shaped electrodes 12 are formed in a strip shape as shown in FIG. A full-face electrode, that is, a solid electrode (hereinafter, referred to as a solid electrode) 13 is formed in an approximately half region in the longitudinal direction as shown in FIG. At this time, the surface 11a of the piezoelectric element
It is assumed that the plurality of strip-shaped electrodes 12 formed on the back surface and the solid electrode 13 formed on the back surface are formed at positions that do not face each other via the piezoelectric element.

The longitudinal direction of the strip of the strip electrode 12 is made to coincide with the direction parallel to the axial direction of the columnar body or the tubular body when the piezoelectric element is later wound up into the columnar body or the tubular body.

The strip electrode 12 and the solid electrode 13 are formed by pasting a paste electrode material, for example, a platinum (Pt) -based or silver-palladium (Ag-Pd) -based electrode material by means of screen printing or the like with an appropriate resin binder. The shaped electrode material is printed and formed.

At this time, as shown in FIG. 1A, the upper end surface of the strip electrode 12 on the surface 11a of the piezoelectric element is formed so as to be exposed from the upper end surface of the surface 11a of the piezoelectric element. The lower end is formed so as to be located slightly inward from the lower end of the surface 11a. Further, as shown in FIG. 1B, the upper end surface of the solid electrode 13 on the back surface 11b of the piezoelectric element 11 is located slightly inward from the upper end of the back surface 11b of the piezoelectric element, which is opposite to the strip electrode 12. Form and form solid electrode 13
The lower end surface of the back surface is formed so as to be exposed from the lower end surface of the back surface 11b, which is opposite to the strip electrode 12.

Next, as shown in FIG. 2, the surface 11a of the piezoelectric element is placed outside and is folded in two along the longitudinal direction of the strip-shaped electrode 12 at a substantially central bent portion 14 to be overlapped. At this time, when the piezoelectric element 11 is rolled up into a columnar body or a tubular body, the bent portion 14 is formed so that the end of the solid electrode 13 is slightly exposed on the outer peripheral surface of the columnar body or the tubular body. It is preferable that the solid electrode 13 is slightly displaced from the center to one side, and the end portion of the solid electrode 13 is made to protrude from the end portion of the other bent piezoelectric element 11 by the dimension d.

FIG. 3 shows a piezoelectric element 1 folded and folded in two.
1 is a view of an end surface of FIG. 3, FIG. 3A shows a state where an end portion (upper end) of the strip electrode 12 is exposed from one end surface of the piezoelectric element 11, and FIG. It shows a state in which the end portion (lower end) of the electrode 13 is exposed from the other end surface of the piezoelectric element 11.

Next, the two-folded piezoelectric element 11 is rolled up into a columnar body or a cylindrical body with the bent portion 14 inside. Here, an example in which the material is wound into a columnar body will be described.

FIG. 4 is a view of the rolled-up columnar body viewed from the end face in the axial direction. In FIG. 4A, the end (upper end) of the strip electrode 12 is exposed from one end face of the columnar body. 4B shows the state where the end portion (lower end) of the solid electrode 13 is exposed from the other end surface of the columnar body. Further, the circumferential end of the solid electrode 13 is also exposed on the outer peripheral surface of the columnar body.

Next, the end face of the piezoelectric conversion element 15 which is a columnar body is divided into a plurality of regions along the circumferential direction, the divided electrode terminals are connected to the plurality of strip-shaped electrodes 12 belonging to each divided region, and a solid pattern is formed. When a ground electrode terminal is connected to the electrode 13 and firing / polarization processing is performed, the piezoelectric conversion element 15 having a plurality of strip electrodes 12 along the circumferential direction of the columnar body is completed.

FIG. 5 is a perspective view showing a state in which the end face of the piezoelectric conversion element 15 is divided into a plurality of regions along the circumferential direction, and the electrode terminals are connected to the plurality of strip electrodes 12 belonging to the respective divided regions. Is.

FIG. 5A shows an example in which the axial end face of the piezoelectric conversion element 15 wound up in a columnar body is divided into four regions along the circumferential direction. The divided regions 16a, 16b,
Since the end portions of the strip-shaped electrodes 12 belonging to the respective divided regions are exposed in 16c and 16d, the exposed end portions of the strip-shaped electrodes 12 in the respective divided regions are collectively separated by a conductive member indicated by diagonal lines. The figure shows a state in which the ground electrode terminal G is connected to the solid electrodes 13 connected to the terminals A1, A2, A3, and A4 and exposed on the other axial end surface of the piezoelectric conversion element 15.

Further, as shown in FIG. 5B, the divided end portions of the strip-shaped electrodes 12 belonging to the respective divided regions are collectively provided on the side surface of the columnar body through the conductive members shown by the diagonal lines. Since the solid electrodes 13 are connected to the electrode terminals A1, A2, A3, and A4 and are exposed on the side surfaces of the columnar body, they may be connected to the ground electrode terminal G.

The exposed end of the strip-shaped electrode 12 is connected to the divided electrode terminal A.
The conductive members indicated by the above-described diagonal lines for connecting to 1 to A4 can be configured by an appropriate method such as applying the same conductive paste as the electrode material to the divided regions 16a to 16d to connect.

In FIGS. 1 to 5 and other explanations, the thickness of the piezoelectric element 11, the strip electrode 12 and the solid electrode 13 is shown to be extremely thick for the purpose of explaining the structure. Is extremely thin on the order of microns.

In the following description, the piezoelectric conversion element 1 described above is used.
A piezoelectric conversion element having a structure in which the end surface of 5 is divided into a plurality of regions along the circumferential direction, electrode terminals are connected to a plurality of strip electrodes 12 belonging to each divided region, and electrode terminals are connected to a solid electrode 13. That is, the piezoelectric conversion element provided with a plurality of strip-shaped electrodes along the circumferential direction of the columnar body or the cylindrical body is referred to as a circumferential electrode division piezoelectric conversion element, and the reference numeral 20 is used for reference.

Next, various vibration modes that can be generated in the above-mentioned circumferential electrode divided piezoelectric conversion element 20 (hereinafter referred to as element 20) will be described with reference to FIGS. 6 to 10.

FIG. 6 is a diagram for explaining the vibration modes that can be generated in the element 20. By selectively applying an alternating voltage to the divided electrodes of the element 20, stretching vibration in the direction of the central axis indicated by the axis I, an X plane including the axis I, is applied to the element 20.
It is possible to generate bending vibration and elliptical vibration in the Y plane including the axis I and the Z plane orthogonal to the axis I. The voltage applied to each divided electrode terminal and the vibration mode generated will be described below.

FIG. 7 shows divided electrode terminals A1, A2, A3,
In the diagram showing the vibration mode when V = V0 sin ωt is applied between A4 and the ground electrode terminal G, the element 20 undergoes stretching vibration in the direction of the central axis indicated by the axis I.

FIG. 8 shows that V1 = V0 sin ωt between the divided electrode terminal A1 and the ground electrode terminal G, and V3 = V0 sin (ωt−π) between the divided electrode terminal A3 and the ground electrode terminal G.
, V2 between the split electrode terminal A2 and the ground electrode terminal G
= 0, V between the split electrode terminal A4 and the ground electrode terminal G
4 is a diagram showing a vibration mode when 4 = 0 is applied, and FIG.
Bending vibration occurs in the X plane including the axis I.

Among the applied voltages, the applied voltage between the divided electrode terminal A3 and the ground electrode terminal G is V3 = V0
When sin (ωt−π / 2) is set, the element 20 has the axis I
Elliptical vibration occurs in the X plane including the.

FIG. 9 shows that V2 = V0 sin ωt between the divided electrode terminal A2 and the ground electrode terminal G, and V4 = V0 sin (ωt-π) between the divided electrode terminal A4 and the ground electrode terminal G.
, V1 between the split electrode terminal A1 and the ground electrode terminal G
= 0, V between the split electrode terminal A3 and the ground electrode terminal G
3 is a diagram showing a vibration mode when 3 = 0 is applied, and FIG.
Bending vibration occurs in the Y plane including the axis I.

Of the applied voltages, the applied voltage between the divided electrode terminal A4 and the ground electrode terminal G is V4 = V0
When sin (ωt−π / 2) is set, the element 20 has the axis I
Elliptical vibration occurs in the Y plane including the.

In FIG. 10, V1 = V0 sin .omega.t between the divided electrode terminal A1 and the ground electrode terminal G, and V2 = V0 sin (.omega.t-.pi. / Between the divided electrode terminal A2 and the ground electrode terminal G.
2), V3 between the split electrode terminal A3 and the ground electrode terminal G
= V0 sin (ωt−π), a diagram showing a vibration mode when V4 = V0 sin (ωt−3 / 2π) is applied between the divided electrode terminal A4 and the ground electrode terminal G. Circular vibration occurs in the plane.

The piezoelectric conversion element of the first embodiment described above is a piezoelectric conversion element capable of generating stretching vibration, bending vibration, or elliptical vibration in the piezoelectric conversion element. The piezoelectric conversion element of the fourth embodiment is a piezoelectric conversion element that can generate torsional vibration.

The piezoelectric conversion element 60 of the second embodiment will be described. 11 and 12 are diagrams for explaining the piezoelectric element according to the second embodiment. As the piezoelectric element as a material forming the piezoelectric conversion element, piezoelectric ceramics is used as in the case of the first embodiment, and flexible sheet-shaped piezoelectric elements 61 and 63 called green sheets are formed.

On the entire surface of the first piezoelectric element 61 in the winding direction, a full surface electrode, that is, a solid electrode 62 is formed as shown in FIG. 11 (a). Further, as shown in FIG. 11B, when the piezoelectric element is later wound up into a columnar body or a cylindrical body, the surface of the second piezoelectric element 63 has an axis of the columnar body or the cylindrical body. A plurality of strip electrodes 64 having an inclination angle of 45 degrees with respect to the direction are formed.

The strip electrode 64 and the solid electrode 62 are formed by pasting a paste-like electrode material, for example, a platinum (Pt) -based or silver-palladium (Ag-Pd) -based electrode material with a suitable resin binder by means such as screen printing. The shaped electrode material is printed and formed.

The solid electrode 62 is formed by leaving the peripheral portion of the first piezoelectric element 61 slightly as shown in FIG. 11A, and the strip electrode 64 is shown in FIG. 11B. Thus, the lower end surface is formed so as to be exposed at the lower end surface of the piezoelectric element 63, and the upper end is formed so as to be positioned slightly inward from the upper end of the surface of the piezoelectric element 63.

Next, the solid electrode 62 of the first piezoelectric element 61.
The surface on which the strip-shaped electrode 64 of the second piezoelectric element 63 is formed is opposed to the surface on which the electrode is not formed on the back surface of the first piezoelectric element 61. The second piezoelectric element 6 is laminated so that the non-formation surface is on the bottom side.
The back surface of No. 3 is folded in two at the central portion in the longitudinal direction with the electrode-non-formed surface on the inside (in a valley), and then rolled up into a columnar body or a tubular body. FIG. 12 (a) shows the appearance rolled up into a columnar body or a cylindrical body.

Next, an electrode terminal is connected to the strip electrode 64 exposed on the lower end surface of the piezoelectric conversion element 60 rolled up in a columnar or cylindrical body, and a ground electrode terminal is connected to the solid electrode 62 exposed on the outer peripheral surface. Then, after firing and polarization treatment, the piezoelectric conversion element 6 including a plurality of strip electrodes 64 inclined at an inclination angle of 45 degrees with respect to the axial direction along the circumferential direction of the columnar body or the cylindrical body.
0 is completed.

In the piezoelectric conversion element 60 having this structure, since the strip electrodes are inclined with respect to the axial direction of the columnar body or the cylindrical body, by applying a voltage between the electrodes, the structure shown in FIG. Since the state is twisted to the state shown in FIG. 12B, torsional strain vibration can be generated by applying an AC voltage between the electrodes.

In the above structure, the diameter of the columnar body or the cylindrical body is 2 mm, the length is 5 mm, and the thickness of the piezoelectric element sheet is 50 μm.
m, the inclination angle of the strip electrode is 45 degrees, the width of the strip electrode is the same as the width of the portion without the electrode, and the width of the strip electrode and the diameter of the columnar body are 1:40. However, the above-mentioned size is an example, and it is not limited to this, and it is desirable that the width of the strip electrode is wide.

13 and 14 are diagrams for explaining the piezoelectric conversion element 68 according to the third embodiment. The difference from the piezoelectric conversion element of the second embodiment is that in addition to the first piezoelectric element 61 and the second piezoelectric element 63 of the second embodiment, the strip shape of the second piezoelectric element 63 is further added. The point is that a third piezoelectric element 65 having a plurality of strip electrodes inclined in the opposite direction to the electrode 64 is added.

The piezoelectric conversion element 68 according to the third embodiment will be described. Since the piezoelectric element as a material forming the piezoelectric conversion element, the electrode material, and the electrode forming method are the same as those in the second embodiment, the description thereof will be omitted.

On the entire surface of the first piezoelectric element 61 in the winding direction, the solid electrode 6 is formed as shown in FIG.
2 is formed on the surface of the second piezoelectric element 63, as shown in FIG. 13B, when the piezoelectric element is later wound into a columnar body or a cylindrical body, the columnar body or the cylindrical body is formed. A plurality of first strip electrodes 64 having an inclination angle of 45 degrees that are inclined in the first direction with respect to the axial direction of the body are formed. Further, on the surface of the third piezoelectric element 65, as shown in FIG. 13C, a second direction opposite to the first direction with respect to the axial direction of the columnar body or the cylindrical body, That is, a plurality of second strip electrodes 66 having an inclination angle of 45 degrees, which is opposite to the first strip electrode 64 in the inclination direction and is inclined in the second direction with respect to the axial direction, is formed.

The solid electrode 62 is formed by leaving the peripheral portion of the piezoelectric element 61 slightly as shown in FIG.
13B, the strip electrode 64 is formed so that the lower end surface is exposed to the lower end surface of the surface of the piezoelectric element 63, and the upper end is located slightly inward from the upper end of the surface of the piezoelectric element 63. To be formed. In addition, the second strip electrode 66
Is formed so that the lower end is located slightly inward from the lower end of the surface of the piezoelectric element 65 and the upper end surface is exposed to the upper end surface of the surface of the piezoelectric element 65, as shown in FIG. To do.

Next, the formation surface of the solid electrode 62 of the piezoelectric element 61 is set to the uppermost side, and the formation surface of the first strip electrode 64 of the piezoelectric element 63 is opposed to the non-electrode formation surface of the back surface of the piezoelectric element 61, The piezoelectric element 65 is formed on the back surface of the piezoelectric element 63 on which electrodes are not formed.
The surfaces of the second strip-shaped electrodes 66 of the piezoelectric element 6 are opposed to each other.
5 is laminated so that the back surface of the piezoelectric element 65 on which the electrode is not formed is located at the bottom side, and the back surface of the piezoelectric element 65 is folded inward with the non-electrode surface of the back surface of the piezoelectric element 65 being the inside (valley). , Roll up into a columnar body or a cylindrical body. FIG. 14 (a) shows the appearance wound up into a columnar body or a tubular body.

Next, the first strip-shaped electrode 64 exposed on the lower end surface of the piezoelectric conversion element 68, which is a columnar body or a cylindrical body, is first exposed.
Second strip electrode 6 connected to the electrode terminal and exposed at the upper end surface
When the second electrode terminal is connected to 6 and the ground electrode terminal is connected to the solid electrode 62, and firing / polarization treatment is performed, the first direction with respect to the axial direction is along the circumferential direction of the columnar body or the cylindrical body. A first strip electrode 64 inclined at an inclination angle of 45 degrees, and a second strip electrode 66 inclined at an inclination angle of 45 degrees in a second direction with respect to the axial direction. The piezoelectric conversion element 68 including the strip electrodes 64 and 66 of is completed.

Since the piezoelectric conversion element 68 of this structure is provided with two sets of a plurality of strip-shaped electrodes 64 and 66 having different inclination directions with respect to the axial direction of the columnar or cylindrical body,
By selectively applying a voltage between the first strip electrode 64 and the ground electrode or between the second strip electrode 66 and the ground electrode, the state shown in FIG. (B)
It is possible to selectively generate a twist to the state shown in FIG. 14 or a twist in the opposite direction from the state shown in FIG. 14A to the state shown in FIG. 14C, and the twist directions are different. Two types of torsional strain vibration can be generated.

FIG. 15 and FIG. 16 are views for explaining the piezoelectric conversion element 70 of the fourth embodiment. The difference from the piezoelectric conversion element of the second embodiment is that, instead of the second piezoelectric element of the second embodiment, a second piezoelectric provided with two sets of strip electrodes having different inclination directions. The point is that the element 71 is arranged.

The piezoelectric conversion element 70 of the fourth embodiment will be described. Since the piezoelectric element as a material forming the piezoelectric conversion element, the electrode material, and the electrode forming method are the same as those in the second embodiment, the description thereof will be omitted.

On the entire surface of the first piezoelectric element 61 in the winding direction, the solid electrode 6 is formed as shown in FIG.
2 is formed on the surface of the second piezoelectric element 71, when the piezoelectric element is later rolled up into a columnar body or a tubular body as shown in FIG. A plurality of strip electrodes 72 having an inclination angle of 45 degrees inclined in the first direction with respect to the axial direction of the body, and a second electrode 72 opposite to the first direction with respect to the axial direction of the columnar body or the tubular body. Direction, that is, the tilt direction is different from that of the plurality of second band electrodes 73 having a tilt angle of 45 degrees that is tilted in the second direction with respect to the axial direction and is opposite in tilt direction to the first band electrode 72. Two sets of plural strip electrodes 72
And 73 are formed.

The solid electrode 62 is formed by leaving the peripheral portion of the piezoelectric element 61 slightly as shown in FIG.
As shown in FIG. 15B, the strip-shaped electrode 72 is formed so that the upper end surface is exposed to the upper end surface of the surface of the piezoelectric element 71, and the lower end is located slightly inward from the lower end of the surface of the piezoelectric element 71. To be formed. In addition, the second strip electrode 73
Is formed so that the upper end is located slightly inward from the upper end of the surface of the piezoelectric element 65 and the lower end surface is exposed at the lower end surface of the surface of the piezoelectric element 63, as shown in FIG. To do.

Next, the solid electrode 62 of the first piezoelectric element 61.
The surface on which the strip-shaped electrodes 72 and 73 of the second piezoelectric element 71 are opposed to the electrode non-formation surface on the back surface of the first piezoelectric element 61, and the rear surface of the second piezoelectric element 71 Are laminated so that the electrode-non-formed surface of the piezoelectric element 71 is on the lowermost side, and the electrode-non-formed surface of the back surface of the piezoelectric element 71 is inward (troughed) and then folded in two at the central portion, and then the columnar body or the cylindrical shape is formed. Roll up on the body. FIG. 16 (a) shows the appearance rolled up into a columnar body or a tubular body.

Next, the first strip-shaped electrode 72 exposed on the upper end surface of the piezoelectric conversion element 70, which is a columnar body or a cylindrical body, is first exposed.
The second strip electrode 7 connected to the electrode terminal and exposed at the lower end surface
When the second electrode terminal is connected to 3 and the ground electrode terminal is connected to the solid electrode 62 and firing / polarization treatment is performed, two sets of plural strips having different inclination directions are formed along the circumferential direction of the columnar body or the cylindrical body. The piezoelectric conversion element 70 including the electrodes 72 and 73 is completed.

In the piezoelectric conversion element 70 of this structure, the first strip electrode 72 inclined in the first direction with respect to the axial direction of the columnar body or the tubular body, and the axial direction of the columnar body or the tubular body. Since the second strip electrode 73 inclined in the second direction is provided, the voltage is selectively applied between the strip electrode 72 and the ground electrode or between the strip electrode 73 and the ground electrode. As a result, the state shown in FIG. 16A is twisted to the state shown in FIG. 16B, or the state shown in FIG.
It is possible to selectively generate the twist from the state shown in FIG. 6A to the state shown in FIG. 16C, and it is possible to generate two types of torsional strain vibrations having different twisting directions.

Further, in the piezoelectric conversion element 70 having this structure,
Similar to the piezoelectric conversion element 68 of the third embodiment, it is capable of generating two types of torsional strain vibrations having different twisting directions. The number of required electrodes can be reduced and can be further reduced, and the number of manufacturing steps can be reduced and the manufacturing cost can be reduced, but the mechanical output or the electrical output is reduced as the number of strip electrodes is reduced.

Next, various devices to which the above-mentioned piezoelectric conversion element is applied will be described. In the following description, the circumferential electrode divided piezoelectric conversion element 20 described with reference to FIGS.
An apparatus using is described.

FIG. 17 is an external view of a gyro vibrating unit 21 to which the bending vibration generated in the circumferential electrode division piezoelectric conversion element 20 described above is applied, and it functions as an angular velocity detector.

As shown in FIG. 18, the gyro vibrating unit 21 is constructed by fixing nodes 20a and 20b of flexural vibration generated in the circumferential electrode divided piezoelectric conversion element 20 to a support 22.

A voltage V1 = V0 si between the split electrode terminal A1 and the ground electrode terminal G of the gyro vibrating unit 21.
n ωt, when a voltage V3 = V0 sin (ωt-π) is applied between the divided electrode terminal A3 and the ground electrode terminal G for excitation,
Flexural vibration occurs in the element 20 in the X plane including the axis I. When the gyro vibrating unit 21 is rotated in this state, the Coriolis force exerts a force in a direction orthogonal to the bending vibration in the X plane, so that the split electrode terminal A2 and the ground electrode terminal G, and A signal proportional to the magnitude of the angular velocity is generated between the divided electrode terminal A4 and the ground electrode terminal G, and the angular velocity can be detected.

19 and 20 are views for explaining a rotary type actuator 30 to which the elliptic vibration generated in the above-mentioned circumferential electrode division piezoelectric conversion element is applied. FIG. 19 is a perspective view in which the constituent elements of the actuator are disassembled. 20 is a sectional view of the actuator 30. As shown in FIG.

19 and 20, the electrode division piezoelectric conversion element 20 uses a cylindrical body having a hollow central portion. One end surface of the circumferential electrode division piezoelectric conversion element 20 is fixed on the fixing base 31 by means of bonding or the like, and the disk-shaped stator 32 is fixed on the other end surface of the element 20 by means of bonding or the like. The stator 32 is made of ceramics in order to ensure wear resistance and electrical insulation with respect to the divided electrodes exposed on the end faces.

The shaft 35 is passed through the hollow portion at the center of the element 20 and fixed to the fixing base 31 by means such as screwing. A disk-shaped rotor 33 is arranged on the stator 32 so as to be rotatable around a shaft 35, a thrust bearing 34 for supporting an axial load is arranged on the rotor 33, and a spring 36 is arranged above the thrust bearing 34. Deploy.

A nut 37 is attached to the threaded portion near the upper end of the shaft 35.
Is screwed to adjust the amount of tightening of the nut 37, and the thrust bearing 34 is pressed toward the rotor 33 via the spring 36 with an appropriate pressing force, so that the stator 32 and the rotor 3
3 and 3 are brought into frictional contact with an appropriate frictional force.

In the above structure, when an AC voltage is applied between the divided electrode terminal of the electrode-divided piezoelectric conversion element 20 and the ground electrode terminal, the element 20 and the stator 32 fixed to the element are previously subjected to FIG. Since the bending vibration and the elliptic vibration described with reference to FIG. 9 occur, the rotor 33 that is in frictional contact with the stator 32 can be rotated. With this configuration, it is possible to provide an extremely small rotary actuator.

FIG. 21 is a perspective view showing a structure of a multi-degree-of-freedom actuator 40 to which various vibration modes generated in the above-mentioned circumferential electrode division piezoelectric conversion element are applied.

The multi-degree-of-freedom actuator 40 has a fixed base 41.
One end surface of the electrode-divided piezoelectric conversion element 20 is fixed on the above by means such as adhesion, and the hemispherical stator 42 is fixed on the other end surface of the element 20 by means such as adhesion. The stator 42 is made of ceramics in order to ensure wear resistance and electrical insulation with respect to the split electrodes exposed on the end faces.

A spherical body 43 rotatably supported is pressed against the stator 42 by an appropriate pressing force by means such as a spring (not shown) to bring the stator 42 and the spherical body 43 into frictional contact with each other with an appropriate frictional force.

In the above structure, when an AC voltage is applied between the divided electrode terminal of the electrode-divided piezoelectric conversion element 20 and the ground electrode terminal, the element 20 and the stator 42 fixed to the element are previously subjected to the operation shown in FIG. Through as described in FIG.
Since vibrations of various vibration modes are generated, the stator 42
The spherical body 43, which is in frictional contact with, can be driven with multiple degrees of freedom.

FIG. 22 is a monitoring camera 5 to which the multi-degree-of-freedom actuator 40 described above is applied and which freely rotates in three axial directions.
FIG. 23 is a cross-sectional view for explaining the configuration of No. 0, and FIG. 23 is a perspective view showing its appearance.

In the surveillance camera 50, the above-mentioned multi-degree-of-freedom actuator 40 is fixedly arranged inside an outer case 51, and springs 53 and balls 5 arranged at a plurality of places inside the outer case 51.
The spherical body 43 supported by the supporting means consisting of 2 is in frictional contact with the stator 42 of the multi-degree-of-freedom actuator 40 by an appropriate frictional force.

A window 43a is formed in the sphere 43,
A lens device 45 and a CCD sensor 4 are provided inside the sphere 43.
6 is arranged, and the external light incident from the window 43a is CC
An image is formed on the D sensor 46, and an image signal is output to an image processing device (not shown).

According to the above configuration, this surveillance camera 50
Is capable of driving the multi-degree-of-freedom actuator 40 to rotate the sphere 43 in an arbitrary direction to be monitored and forming an image of the external environment on the CCD sensor 46 through the window 43a. Therefore, the entire surveillance camera can be downsized.

In the laminated piezoelectric conversion element according to the embodiment of the present invention described above, the sheet-shaped piezoelectric element having a plurality of strip electrodes is used. However, the sheet having a plurality of strip electrodes is used. It is needless to say that the number of piezoelectric elements is not limited to one, and a plurality of piezoelectric elements can be used in superposition in order to obtain a required mechanical output or a required electrical output. . In addition, the mechanical output or the electrical output can be increased even if the number of layers is increased by winding. As a result, when applied to an actuator, an actuator with large thrust can be easily obtained. Further, when applied to a rotational angular velocity detector, it is possible to obtain an effect such as improving a signal-to-noise ratio (S / N ratio) by a large electric output.

[0086]

As described in detail above, in the laminated piezoelectric conversion element of the present invention, a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material is laminated and wound so as to be sandwiched between a plurality of strip electrodes and a full-scale electrode. It is raised to form a columnar body or a tubular body.

Then, the strip electrodes are arranged in parallel with the axial direction of the columnar body or the tubular body, and the columnar body or the tubular body is divided into at least two or more plural regions in the circumferential direction, and the plurality of strip electrode is arranged. When it is configured to belong to one of the divided regions divided into a plurality of regions, the strip-shaped electrode belonging to a part of the divided region or the strip-shaped electrode of the entire region and the entire surface electrode are selectively By applying a voltage to excite the piezoelectric transducer, various vibration modes such as expansion mode vibration, bending mode vibration, elliptical mode vibration, and torsional vibration mode can be generated.

When a piezoelectric vibrator is constructed by using this piezoelectric conversion element, it becomes easy to generate vibration in the bending vibration mode, and an efficient piezoelectric vibrator can be provided.

Further, even when the piezoelectric vibration gyro detector using this piezoelectric conversion element is used as a rotational angular velocity detector, a detection signal having a good signal-to-noise ratio (S / N ratio) can be obtained.

In addition, since the actuator using this piezoelectric conversion element can be operated in various vibration modes such as expansion mode vibration, bending mode vibration, elliptical mode vibration, or torsional vibration mode, it can be operated on the driven body. It is possible to make an actuator that makes various movements with a simple structure and in a very small size.

As described above, since this piezoelectric conversion element can be operated in various vibration modes, the piezoelectric vibrator,
It can be used for various applications such as piezoelectric vibration gyro detectors and actuators.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a piezoelectric element as a material forming a piezoelectric conversion element according to a first embodiment and electrodes formed on a front surface and a back surface thereof.

FIG. 2 is a perspective view showing a state in which a piezoelectric element having electrodes is folded in two at a substantially central portion.

FIG. 3 is an enlarged view of a two-folded piezoelectric element as seen from an end surface.

FIG. 4 is an enlarged view of a piezoelectric conversion element when the piezoelectric element is rolled up into a columnar body as seen from an end surface.

FIG. 5 is a perspective view showing a state where the end surface of the piezoelectric conversion element is divided along the circumferential direction and terminals are connected to the divided electrodes.

FIG. 6 is a diagram illustrating various vibration modes generated in a circumferential electrode divided piezoelectric conversion element.

FIG. 7 is a diagram for explaining stretching vibration in the central axis I direction of the circumferential electrode division piezoelectric conversion element.

FIG. 8 is a diagram for explaining bending vibration and elliptical vibration in the X plane of the circumferential electrode divided piezoelectric conversion element.

FIG. 9 is a diagram for explaining bending vibration and elliptical vibration in the Y plane of the circumferential electrode divided piezoelectric conversion element.

FIG. 10 is a diagram for explaining circular vibration in the Z plane of the circumferential electrode division piezoelectric conversion element.

FIG. 11 is a perspective view illustrating an element that constitutes the piezoelectric conversion element according to the second embodiment and an electrode formed on the surface thereof.

FIG. 12 is a diagram illustrating torsional strain vibration of the piezoelectric conversion element according to the second embodiment.

FIG. 13 is a perspective view illustrating an element forming a piezoelectric conversion element according to a third embodiment and electrodes formed on the surface thereof.

FIG. 14 is a diagram for explaining torsional strain vibration of the piezoelectric conversion element according to the third embodiment.

FIG. 15 is a perspective view illustrating an element forming a piezoelectric conversion element according to a fourth embodiment and electrodes formed on the surface thereof.

FIG. 16 is a diagram for explaining torsional strain vibration of the piezoelectric conversion element according to the fourth embodiment.

FIG. 17 is a view for explaining the external appearance of a gyro vibrating unit using a circumferential electrode divided piezoelectric conversion element.

FIG. 18 is a diagram illustrating nodes of flexural vibration generated in the gyro vibrating unit shown in FIG. 11.

FIG. 19 is a perspective view in which an actuator to which an elliptical vibration generated in a circumferential electrode division piezoelectric conversion element is applied is disassembled into its constituent elements.

20 is a cross-sectional view of the actuator shown in FIG.

FIG. 21 is a perspective view illustrating a configuration of a multi-degree-of-freedom actuator that applies various vibration modes generated in a circumferential electrode division piezoelectric conversion element.

22 is a cross-sectional view illustrating the configuration of a surveillance camera to which the multi-degree-of-freedom actuator shown in FIG. 21 is applied.

23 is a perspective view showing the outer appearance of the surveillance camera shown in FIG. 22. FIG.

[Explanation of symbols]

11 Piezoelectric element 11a surface of piezoelectric element 11b Back side of piezoelectric element 12 strip electrodes 13 Full surface electrode (solid electrode) 14 Folding section 15 Piezoelectric conversion element 16a, 16b, 16c, 16d divided areas 20 Piezoelectric conversion element with circumferential electrode division 20a, 20b Flexural vibration node 21 Gyro vibration unit 22 Support 30 rotary actuator 31 fixed base 32 stator 33 rotor 34 Thrust bearing 35 axes 36 spring 37 nuts 40 multi-degree-of-freedom actuator 41 fixed base 42 Stator 43 sphere 43a window 45 lens device 46 CCD sensor 50 surveillance cameras 51 outer box 52 balls 53 spring 60, 68, 70 Piezoelectric conversion element 61, 63, 65, 71 Piezoelectric element 62 Full surface electrode (solid electrode) 64, 66, 72, 73 Strip electrodes A1, A2, A3, A4 split electrode terminals G ground electrode terminal

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 41/08 Z

Claims (11)

[Claims] 1. A piezoelectric conversion characterized in that a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material is laminated and wound so as to be sandwiched between a plurality of strip electrodes and a full-scale electrode, and formed into a columnar body or a cylindrical body. element. 2. The columnar body or the tubular body is divided into at least two or more plural regions along the circumferential direction thereof, and the plurality of strip electrodes is one of the divided regions divided into the plural regions. 2. The piezoelectric conversion element according to claim 1, wherein the piezoelectric conversion element is configured to belong to one of the groups. 3. The end portions of the plurality of strip electrodes are exposed on one end surface of the columnar body or the tubular body in the central axis direction, and the end portions of the full surface electrode are the end surfaces on which the plurality of strip electrodes are exposed. Is exposed on the end face in the opposite direction, The piezoelectric conversion element according to claim 1 or 2. 4. A common power supply terminal for supplying power to a strip electrode belonging to each of the plurality of divided areas is provided, and the power supply terminal is exposed at an end surface of the columnar body or the cylindrical body. The piezoelectric conversion element according to claim 2, wherein the piezoelectric conversion element is connected to an end of the strip electrode. 5. The piezoelectric conversion element according to claim 1, wherein the plurality of strip electrodes are arranged parallel to the axial direction of the columnar body or the cylindrical body. 6. The piezoelectric conversion element according to claim 1, wherein the plurality of strip electrodes are arranged so as to be inclined with respect to the axial direction of the columnar body or the cylindrical body. . 7. The plurality of strip electrodes are divided into at least two or more groups, and the strip electrodes belonging to one group and the strip electrodes belonging to the other group are the columnar body or the tubular body. 7. The piezoelectric conversion element according to claim 6, wherein the piezoelectric conversion element is arranged so as to be inclined at different angles with respect to the axial direction. 8. A piezoelectric element using a piezoelectric conversion element formed into a columnar body or a cylindrical body by laminating a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material with a plurality of strip electrodes and a full-face electrode, and winding the laminated piezoelectric element. A vibrator, wherein the columnar body or the tubular body is at least 2 along the circumferential direction.
The plurality of strip electrodes are divided into the plurality of regions, and the plurality of strip electrodes are configured to belong to one of the divided regions divided into the plurality of regions. A plurality of electrodes are characterized in that expansion and contraction mode vibration, bending mode vibration, or elliptical mode vibration is generated in the piezoelectric conversion element by selectively applying a voltage between the strip electrode and the entire surface electrode of the region to excite it. Piezoelectric vibrator that can vibrate in the vibration mode. 9. A piezoelectric element using a piezoelectric conversion element formed into a columnar body or a tubular body by laminating a sheet-shaped piezoelectric element made of a ceramics-based piezoelectric material with a plurality of strip electrodes and a full-face electrode, and laminating the sheet-shaped piezoelectric element. A vibrating gyroscope, wherein the columnar body or the tubular body is at least 2 along the circumferential direction.
The plurality of strip electrodes are divided into the plurality of regions, and the plurality of strip electrodes are configured to belong to one of the divided regions divided into the plurality of regions. By applying a voltage selectively between the strip electrode and the entire surface electrode in the region to excite it, expansion / contraction mode vibration, bending mode vibration, or elliptical mode vibration is generated in the piezoelectric conversion element, and no voltage is applied. A piezoelectric vibrating gyroscope characterized by detecting a signal voltage generated between a strip electrode belonging to a region and a full surface electrode as an angular velocity signal applied to a piezoelectric conversion element. 10. The piezoelectric vibrator according to claim 8,
A piezoelectric actuator, comprising: a rotating body pressed against the piezoelectric vibrator, wherein the rotating body is rotated by generating elliptical mode vibration in the piezoelectric vibrator. 11. A piezoelectric vibrator according to claim 8,
A spherical rotor that is pressed against the piezoelectric vibrator and is rotatably supported, and the piezoelectric vibrator includes bending mode vibration;
A piezoelectric actuator, wherein the rotating body is freely rotated by generating elliptical mode vibration.