JP2961545B2 - Piezoelectric elliptical oscillator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a small motor used for office automation equipment and toys, and more particularly to a piezoelectric elliptical oscillator used for a small ultrasonic motor having a small rotor diameter. It is.

[Prior art] Ultrasonic motors have advantages over conventional electromagnetic motors in that they can obtain high torque at low rotation speed, have a holding force for stopping, and have low electromagnetic noise. It is used for auto focus and power motors of automobiles.

FIG. 14 is a schematic view showing an example of the structure of a piezoelectric elliptical motion oscillator used in a conventional ultrasonic motor, and two adjacent surfaces of a metal prism 60a having a substantially square cross section are shown in FIG.
Electrodes are formed on both sides, and piezoelectric ceramic thin plates 61a and 61b polarized in the thickness direction are bonded. Lead terminals 62a and 62b are pulled out from the surface electrodes of the piezoelectric ceramic thin plates 61a and 61b, and a common ground terminal 63 is formed from the metal prism 60a.
Has been pulled out. Since the cross-sectional shape of the metal prism 60a is substantially square, the metal prism 60a bends and vibrates in a direction perpendicular to each other at substantially the same resonance frequency. Therefore, the lead terminal
When an AC voltage whose frequency is equal to the resonance frequency and whose phase is different (preferably 90 °) is applied to 62a-63 and 62b-63, both ends of the metal prism 60a vibrate in a circular or elliptical manner.

FIG. 15 is a diagram showing an example of the structure of an ultrasonic motor using a prismatic elliptical motion transducer 60 composed of the metal prism 60a shown in FIG. Discs are provided at both ends of this prismatic elliptical oscillator 60.
64a and 64b are mounted, and furthermore, the supporting pin 65 is symmetrically positioned at the node of the vibration of the prism vibrator 60 with respect to the longitudinal midpoint.
a and 65b are formed, and the prism vibrator 60 is stably supported by the support pins 65a and 65b.

Disks 64a and 64b provided at both ends of the prism 60
(Not shown) is in pressure contact with the inner wall of the cavity of the cup-shaped rotary rollers 66a, 66b rotatably supported on a rotary shaft. Therefore, when the end of the prism vibrator 60 vibrates circularly or elliptically, the cup-shaped rotary rollers 66a and 66b are rotated.

[Problems to be Solved by the Invention] In the conventional prismatic elliptical motion transducer shown in FIG. 14, since the transducer is a prism having a square cross section, the resonance frequencies of bending modes in directions perpendicular to each other are precisely set. In order to match, the processing accuracy of the prism must be strictly suppressed. Further, there is a disadvantage that when the piezoelectric ceramic thin plate is bonded to the metal prism, there is a large variation in the bonding state, and the variation in the resonance frequency in the bending mode becomes large. Therefore, a technical problem of the present invention is to provide a piezoelectric elliptical motion vibrator which is not affected by processing accuracy and has a small variation in resonance frequency of a bending mode.

[Means for Solving the Problems] According to the present invention, a first and a second parallel to the longitudinal direction of the piezoelectric ceramic hollow cylinder are provided at positions that divide the circumference of the outer peripheral surface of the piezoelectric ceramic hollow cylinder into four equal parts. , Third and fourth divided electrodes are sequentially applied in the circumferential direction, and the first and third divided electrodes facing each other are electrically connected by a first connection line, and the first and third divided electrodes are opposed to each other. The second and fourth divided electrodes are electrically connected by a second connection line, and a DC voltage is applied so that the first connection line has a positive polarity and the second connection line has a negative polarity. Thereby, the piezoelectric ceramic hollow cylinder is directed along the circumference from the first divided electrode toward the second and fourth divided electrodes, and from the third divided electrode to the second and fourth divided electrodes. Polarized in the direction toward the split electrode, and further 1st and 4th
A first AC voltage having a resonance frequency of the piezoelectric ceramic hollow cylinder and a first phase is applied between the divided electrodes and between the second and third divided electrodes to apply a first AC voltage to the piezoelectric ceramic hollow cylinder. The first bending vibration can be excited, and at the resonance frequency and the first phase of the piezoelectric ceramic hollow cylinder between the first and second divided electrodes adjacent to each other and between the fourth and third divided electrodes. A second alternating voltage having a second phase different from that of the piezoelectric ceramic hollow cylinder to excite a second bending vibration in the piezoelectric ceramic hollow cylinder, and both ends of the piezoelectric ceramic cylinder by the first and second bending vibrations Thus, a piezoelectric elliptical motion vibrator characterized by being capable of exciting elliptical vibration is obtained.

According to the present invention, the first, second, third, and fourth outer peripheral surfaces parallel to the longitudinal direction of the piezoelectric ceramic hollow cylinder are provided at positions that divide the circumference of the outer peripheral surface of the piezoelectric ceramic hollow cylinder into four equal parts. The divided electrodes are sequentially applied along the circumferential direction, and the first, second, third, and fourth outer peripheral surface divided electrodes are respectively disposed on the inner peripheral surface of the hollow column of the piezoelectric ceramics in opposition to the first, second, and fourth outer peripheral surface divided electrodes. Third and fourth inner circumferential surface splitting electrodes are applied, and the first, second, third
And the fourth outer peripheral surface divided electrode and the first, second, third, and fourth inner peripheral surface divided electrodes are first, second, third, and fourth, respectively.
, The first and third connection lines are electrically connected to a first terminal, and the second and fourth connection lines are connected to a second terminal. And a DC voltage is applied between the first and second terminals so that the first terminal has a positive polarity and the second terminal has a negative polarity. From the outer peripheral surface and the inner peripheral surface divided electrode to the second and fourth outer peripheral surfaces and the inner peripheral surface divided electrode, and from the third outer peripheral surface and the inner peripheral surface divided electrode to the second and fourth electrodes. The first and second connection lines and the third and fourth connection lines adjacent to each other are electrically connected to be polarized in the direction toward the divided electrodes on the outer peripheral surface and the inner peripheral surface. A terminal between the third and fourth terminals at the resonance frequency of the piezoelectric ceramic hollow cylinder;
A first AC voltage having a phase of ??? is applied to the piezoelectric ceramic hollow cylinder so that a first bending vibration can be excited. On the other hand, the first and fourth connection lines adjacent to each other and the second and third Are electrically connected to form fifth and sixth terminals, and have a second phase between the fifth and sixth terminals at the resonance frequency of the piezoelectric ceramic hollow cylinder and different from the first phase. By applying a second AC voltage, a second bending vibration can be excited in the piezoelectric ceramic hollow cylinder, and an elliptical vibration can be excited at both ends of the piezoelectric ceramic cylinder by the first and second bending vibrations. Thus, a piezoelectric elliptical motion oscillator is obtained.

According to the present invention, the first, second, third, and fourth outer peripheral surfaces parallel to the longitudinal direction of the piezoelectric ceramic hollow cylinder are provided at positions that divide the circumference of the outer peripheral surface of the piezoelectric ceramic hollow cylinder into four equal parts. The divided electrodes are sequentially applied in the circumferential direction, and the inner peripheral surface of the piezoelectric ceramic hollow cylinder is provided between the first and second outer peripheral surface divided electrodes, between the second and third outer peripheral surface divided electrodes, and the third
The first, second, third, and fourth floating electrodes are respectively provided at positions corresponding to between the first and fourth outer peripheral surface divided electrodes and between the fourth and first outer peripheral surface divided electrodes, and And the third outer peripheral surface division electrode is electrically connected by a first connection line, and the second and fourth outer peripheral surface division electrodes are electrically connected by a second connection line. A DC voltage is applied so that the connection line has a positive polarity and the second connection line has a negative polarity, whereby the first outer peripheral surface divided electrode is extended along the circumference of the piezoelectric ceramic hollow cylinder. The third outer peripheral surface divided electrode passes through the first floating electrode to the second outer peripheral surface divided electrode and from the first outer peripheral surface divided electrode to the fourth outer peripheral surface divided electrode via the fourth floating electrode. From the divided electrode through the second floating electrode to the second outer peripheral surface divided electrode, and The third from the outer peripheral surface divided electrodes
Between the first and fourth outer peripheral surface divided electrodes adjacent to each other, and between the second and third outer peripheral surface divided electrodes. A first alternating voltage having a resonance frequency of the piezoelectric ceramic hollow cylinder and a first phase is applied to the piezoelectric ceramic hollow cylinder so that a first bending vibration can be excited. A second phase having a resonance frequency of the piezoelectric ceramic hollow cylinder and a second phase different from the first phase between the first and second outer peripheral surface divided electrodes and between the fourth and third outer peripheral surface divided electrodes. The second bending vibration can be excited in the piezoelectric ceramic hollow cylinder by applying an AC voltage of, and the elliptical vibration can be excited in both ends of the piezoelectric ceramic cylinder by the first and second bending vibrations. Features The piezoelectric elliptical motion oscillator that is obtained.

According to the present invention, the first, second, third, and fourth outer peripheral surfaces parallel to the longitudinal direction of the piezoelectric ceramic hollow cylinder are provided at positions that divide the circumference of the outer peripheral surface of the piezoelectric ceramic hollow cylinder into four equal parts. The divided electrodes are sequentially applied along the circumferential direction, and the first, second, and third electrodes are formed along the inner peripheral surface of the hollow column of the piezoelectric ceramic.
And the first and fourth outer peripheral surface split electrodes at respective positions facing the split electrode.
Second, third, and fourth inner peripheral surface division electrodes are applied, and the first, second, third, and fourth outer peripheral surface division electrodes are electrically connected by a first connection line. The first, second, third, and fourth inner circumferential surface division electrodes are electrically connected by a second connection line, the first connection line has a positive polarity, and the second connection line has a negative polarity. Apply a DC voltage so as to be polar,
This allows the piezoelectric ceramic hollow cylinder to have the first,
Performing a radial polarization process from the second, third, and fourth inner peripheral surface division electrodes toward the first, second, third, and fourth outer peripheral surface division electrodes, respectively; At a resonance frequency of the piezoelectric ceramic hollow column between the surface divided electrode and the first outer peripheral surface divided electrode and between the third outer peripheral surface divided electrode and the third inner peripheral surface divided electrode, and A first AC voltage having a first phase is applied to excite a first bending vibration in the piezoelectric ceramic hollow cylinder, and the second inner peripheral surface divided electrode and the second outer peripheral surface divided electrode are excited. At the resonance frequency of the piezoelectric ceramic hollow cylinder between the fourth outer peripheral surface divided electrode and the fourth inner peripheral surface divided electrode, and
A second alternating voltage having a second phase different from the phase of the piezoelectric ceramics is applied to excite a second bending vibration in the piezoelectric ceramic hollow column, and the first bending vibration and the second bending vibration A piezoelectric elliptical oscillator is obtained in which elliptical motion can be excited at both ends of a piezoelectric ceramic hollow cylinder.

[Operation] In the present invention, the piezoelectric ceramic hollow cylinder is provided with electrodes at positions where the circumference of the outer peripheral surface is divided into four parts, the inner peripheral surface is further opposed to these electrodes, and between the electrodes. The piezoelectric elliptical motion vibrator is formed by applying electrodes to any of the corresponding positions. A DC voltage is applied to these electrodes to polarize them in the circumferential or radial direction, and the piezoelectric portions are applied to the electrode portions symmetrical with respect to the center in the same direction as the polarization direction and in the opposite direction to the polarization direction. By applying a first AC voltage equal to the resonance frequency of the elliptical motion oscillator to excite vibrations that elongate in the same direction as the polarization direction and contract in the direction opposite to the polarization direction, the axis is changed. The piezoelectric ceramic hollow cylinder generates bending vibration in the plane including the piezoelectric ceramic.

Furthermore, when a second AC voltage having a similar resonance frequency is applied to the electrode portion at a position rotated by 90 ° C. on the peripheral surface of these electrodes, the first bending vibration occurs in a plane including the axis. A similar second bending vibration orthogonal to the second direction is excited. The phases of these two types of first and second AC voltages (preferably 90
Ii) By displacing, the elliptical motion including a circle at both ends of the piezoelectric elliptical motion oscillator can be excited.

Example A piezoelectric elliptical motion oscillator according to a first example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view showing the structure of a piezoelectric elliptical motion oscillator according to a first embodiment of the present invention. The piezoelectric ceramic hollow cylinder 10 is located at a position where the outer peripheral surface of the piezoelectric ceramic hollow cylinder 10 is divided into four equal parts. First, second, parallel along the length direction of
Third and fourth divided electrodes 11, 12, 13, and 14 are sequentially applied.

FIG. 2 shows the piezoelectric ceramic hollow cylinder 1 shown in FIG.
FIG. 2 is a cross-sectional view for explaining the principle of vibration of FIG. 2A. In FIG. 2A, broken arrows indicate first and third divided electrodes.
11 and 13 are electrically connected by a first connection line 15 to be a + terminal, and the second and fourth divided electrodes 12 and 14 are electrically connected by a second connection line 16 to be a-terminal. It shows the direction of polarization when a voltage is applied to perform polarization processing. In this figure, the polarization direction is from the first split electrode 11 to the second split electrode 12 and the fourth split electrode 14 along the circumference of the piezoelectric ceramic hollow cylinder 10, and from the third split electrode 13 to the third split electrode 13. The direction is toward the second divided electrode 12 and the fourth divided electrode 14. FIG. 2 (b) shows a piezoelectric ceramic hollow cylinder 10 which has been polarized as shown in FIG. 2 (a), in which first and second divided electrodes 11, 12 adjacent to each other are electrically connected by a third connection line 17. When a DC voltage is applied as a negative terminal, the positive and negative terminals are electrically connected to each other via a fourth connection line 18 and the other pair of third and fourth divided electrodes 13 and 14 are electrically connected to each other. 3 shows a state of distortion generated in the cross-sectional direction of the ceramic hollow cylinder 10.

In FIG. 2 (b), the electric field is applied in the direction indicated by the solid arrow, so that the polarization direction and the electric field direction are the same between the first and fourth divided electrodes 11 and 14, and Circumferential elongation strain occurs, and the second and third split electrodes 12 and 13
During the period, the direction of the polarization and the direction of the electric field are opposite to each other, and contraction distortion in the circumferential direction occurs. As a result, in FIG. 2B, the piezoelectric ceramic hollow cylinder 10 bends so that the lower side expands in the length direction. When the direction of the applied voltage is reversed, the direction of the bending is also reversed.

FIG. 3 is an explanatory view of a vibration state when an AC voltage is applied to the polarized piezoelectric ceramic hollow cylinder 10 as shown in FIG. 2 (a). In FIG. 3A, the resonance frequency of the bending vibration of the piezoelectric ceramic hollow cylinder 10 is equal to between the first and fourth divided electrodes 11 and 14 and between the second and third divided electrodes 12 and 13, respectively. A first phase having a first phase;
When the alternating voltage is applied, the piezoelectric ceramic hollow cylinder 10 generates a first bending vibration that bends in the direction of the arrow as shown by the two-dot chain line in FIG. 3 (a). In FIG. 3 (a), the first bending of the piezoelectric ceramic hollow cylinder 10 is similarly performed between the first and second divided electrodes 11 and 12 and between the fourth and third divided electrodes 4 and 3, respectively. When a second AC voltage having a second phase equal to the resonance frequency of the vibration is applied, the piezoelectric ceramic hollow cylinder 10 generates a second bending vibration in a direction perpendicular to the direction of the arrow shown in FIG. .

FIG. 4 is a view showing a specific example of an AC voltage application method for the ultrasonic motor according to the first embodiment of the present invention. In this figure, the first AC voltage is divided into an AC of V1sinωt from the terminals 21 and 22 on the secondary side and between terminals 23 and 24 by inputting an AC of V0sinωt to the primary side of the first transformer. The second AC voltage is input to the primary side of the second transformer by inputting an AC of V0cosωt, which is 90 ° in phase with the first AC voltage, to the secondary-side terminal 25 and
It is divided and taken out as an alternating current of V1cosωt from between 26 and between terminals 27 and 28. The signs + and-of the secondary terminals of the first transformer and the signs (+) and (-) of the secondary terminals of the second transformer have the same sign, respectively, indicating that they have the same polarity. Terminals 21 and 25 are connected to the first split electrode, terminals 23 and 26 are connected to the second split electrode, terminals 24 and 28 are connected to the third split electrode, and terminals 22 and 27 are connected to the fourth split electrode, respectively. ing.

Accordingly, by shifting the phases of the first and second bending vibrations in the two directions described above, specifically, the first and second AC drive voltages for exciting the respective bending vibrations are shifted.
And the second phase (FIG. 4),
A circular motion or an elliptical motion as shown by a two-dot chain line in FIG. 3 (b) can be excited at both ends of the piezoelectric ceramic hollow cylinder 10.

Next, a piezoelectric elliptical oscillator according to a second embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 5 is a schematic diagram showing the structure of a piezoelectric elliptical motion oscillator according to a second embodiment of the present invention. 6 (a) and 6 (b) are piezoelectric ceramic hollow cylinders shown in FIG. 5 for explaining the state of occurrence of distortion of the piezoelectric elliptical oscillator.
30 is a cross-sectional view of FIG. 30, (a) is a piezoelectric ceramic hollow cylinder
A connection method for polarization 30 is shown, and (b) shows a connection method for driving the piezoelectric ceramic hollow cylinder 30.

5 and FIGS. 6 (a) and 6 (b), at positions where the outer peripheral surface of the piezoelectric ceramic hollow cylinder 30 is divided into four equal parts, a first and a first cylinders parallel to the longitudinal direction of the piezoelectric ceramic hollow cylinder 30 are arranged.
Second, third, and fourth outer peripheral surface division electrodes 31, 32, 33, and 34 are formed in this order along the peripheral surface, and the first, second, and third electrodes are respectively formed on the inner peripheral surface of the piezoelectric ceramic hollow cylinder 30. 2, the first, second, and third electrodes are located at positions facing the third and fourth outer peripheral surface divided electrodes 31, 32, 33, and 34.
Third and fourth inner peripheral surface division electrodes 31 ', 32', 33 ', and 34' are formed correspondingly.

Referring to FIG. 6 (a), a broken arrow indicates that the first outer peripheral surface divided electrode 31 and the first inner peripheral surface divided electrode 31 'are electrically connected by a first connection line 35a. The second outer peripheral surface divided electrode 32 and the second inner peripheral surface divided electrode 32 'are connected to a second connection line 35b.
Thus, the third outer peripheral surface divided electrode 33 and the third inner peripheral surface divided electrode 3
Reference numeral 3 'denotes a third connection line 35c, and the fourth outer peripheral surface divided electrode 34 and the third inner peripheral surface divided electrode 34' are electrically connected by a fourth connection line 35d. Then, the first connection line 35a and the third connection line 35c are electrically connected to form a first terminal 36a,
And the fourth connection line 35d are electrically connected to form a second terminal 36b. The first terminal 36a is a + terminal, and the second terminal 36b is a second terminal 36b.
Polarization was performed by applying a DC voltage so that 36b became one terminal. The direction of polarization at this time is from the first outer peripheral surface and inner peripheral surface divided electrodes 31 and 31 ′ to the second outer peripheral surface and inner peripheral surface divided electrodes 32 and 32 ′, and the first outer peripheral surface and inner peripheral surface. From the divided electrodes 31 and 31 'to the fourth outer peripheral surface and inner peripheral surface divided electrode 34
And 34 ', and the third outer and inner peripheral surface divided electrodes 33 and 3
3 'to the second outer surface and inner peripheral surface divided electrodes 32 and 32',
And the third outer peripheral surface and inner peripheral surface divided electrodes 33 and 33 'to the fourth outer peripheral surface and inner peripheral surface divided electrodes 34 and 34'.

Referring to FIG. 6 (b), in the piezoelectric ceramic hollow cylinder 30 polarized as shown in FIG. 6 (a), the first connection line 35a and the second connection line 35b adjacent to each other are connected. To form a third terminal 37a, further connect the third connection line 35c and the fourth connection line 35d adjacent to each other to form a fourth terminal 37b, and change the third terminal to a + terminal, This figure shows a state of distortion generated in the cross-sectional direction of the hollow column 30 of the piezoelectric ceramic when a DC voltage is applied with the fourth terminal as one terminal. In FIG. 6B, since the electric field is applied in the direction shown by the solid arrow, the first outer peripheral surface and inner peripheral surface split electrode
31 and 31 ′, a fourth outer peripheral surface and an inner peripheral surface divided electrode 34 and
During the period 34 ', the direction of polarization and the direction of the electric field become the same, and a circumferential elongation distortion occurs, and the second outer peripheral surface and the inner peripheral surface 32 and 32' and the third outer peripheral surface and the inner peripheral surface Between 33 and 33 ', the direction of the polarization and the direction of the electric field are opposite to each other, and a contraction strain in the circumferential direction occurs. As a result, in FIG. 6 (b), the piezoelectric ceramic hollow cylinder 30 is bent such that the lower side expands in the length direction. When the direction of the applied voltage is reversed, the direction of the bending is also reversed.

In FIG. 6, the first and second transformers are connected to terminals 21 and 25 in the same manner as in the first embodiment of the present invention shown in FIG.
Is the first connection line 35a, and the terminals 23 and 26 are the second connection line 35b.
The terminals 24 and 28 are connected to a third connection line 35c, and the terminals 22 and 27 are connected to a fourth connection line 35d, respectively. An AC voltage can be applied.

FIG. 7 is an explanatory diagram of a vibration state when a first AC voltage is applied to the piezoelectric ceramic hollow cylinder 30 subjected to the polarization treatment as in FIG. 6 (a).

In FIG. 7 (a), the first connection line 35a connecting the first outer peripheral surface and inner peripheral surface division electrodes 31 and 31 'and the fourth outer peripheral surface and inner peripheral surface division electrodes 34 and 34' are connected. Between the connected second connection lines 35d, and between the second outer peripheral surface and the inner peripheral surface divided electrode 32.
And 32 ', and a third connecting line connecting the third outer and inner circumferential divided electrodes 33 and 33'.
When a first AC voltage having the same phase as the resonance frequency of the bending vibration of the piezoelectric ceramic hollow cylinder 30 and having the first phase is applied between 35c, the piezoelectric ceramic hollow cylinder 30 is shown by a two-dot chain line in FIG. 7 (a). As described above, the first bending vibration is generated in the direction of arrow 36.

In FIG. 7 (a), a first connection line 35a connecting the first outer peripheral surface and inner peripheral surface divided electrodes 31 and 31 'and a second outer peripheral surface and inner peripheral surface divided electrodes 32 and 32 are similarly connected. ', The fourth connecting line 35d connecting the fourth outer peripheral surface and the inner peripheral surface dividing electrode 34, 34' and the third outer peripheral surface and the inner peripheral surface dividing electrode 33. , 33 'to the third connection line 35c
When a second AC voltage having a second phase equal to the resonance frequency of the bending vibration of the piezoelectric ceramic hollow cylinder 30 and a second phase is applied to the piezoelectric ceramic hollow cylinder 30 in the direction indicated by an arrow 36 in FIG. And a second bending vibration in a direction perpendicular to the second direction is generated.

Accordingly, by shifting the phases of the first and second bending vibrations in the two directions perpendicular to each other as described above, specifically, the first and second AC drive voltages for exciting the respective bending vibrations are provided. By shifting the first and second phases, elliptical motion including circular motion can be excited at both ends of the piezoelectric ceramic hollow cylinder 30 as shown by the two-dot chain line in FIG. 7B. .

Next, a piezoelectric elliptical motion oscillator according to a third embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 8 is a schematic view showing the structure of a piezoelectric elliptical motion oscillator according to a third embodiment of the present invention. 9 (a) and 9 (b) are piezoelectric ceramic hollow cylinders shown in FIG. 8 for explaining the state of occurrence of distortion of the piezoelectric elliptical oscillator.
40 is a cross-sectional view of FIG. 40, (a) is a hollow column of piezoelectric ceramics
A connection method for driving the piezoelectric ceramic hollow cylinder 40 is shown in (b) of FIG.

In FIGS. 8 and 9 (a) and (b), at positions where the outer peripheral surface of the piezoelectric ceramic hollow cylinder 40 is divided into four equal parts, the first and the second are parallel to the longitudinal direction of the piezoelectric ceramic hollow cylinder 40.
Second, third, and fourth outer peripheral surface division electrodes 41, 42, 43, and 44 are formed in order, and first and second outer peripheral surface division electrodes 41, 42 are provided on the inner peripheral surface of the piezoelectric ceramic hollow cylinder 40. , Between the second and third outer peripheral surface divided electrodes 42 and 43, between the third and fourth outer peripheral surface divided electrodes 43 and 44, and between the fourth and first outer peripheral divided electrodes 44 and 41. Positions are provided with first, second, third, and fourth floating electrodes 41 ', 42', 43 ', and 44', respectively.

Referring to FIG. 9 (a), broken arrows indicate that the first and third outer peripheral surface divided electrodes 41 and 43 are electrically connected by a first connection line 45a, and that the second and fourth outer peripheral surfaces are separated. Split electrode 42
And 44 are electrically connected by a second connection line 45b, the first connection line 45a is used as a positive terminal, the second connection line 45b is used as a negative terminal, and a DC voltage is applied to perform polarization processing. The direction of polarization is shown.

In FIG. 9 (a), the piezoelectric ceramic hollow cylinder 40
Indicates the direction from the first outer peripheral surface divided electrode 41 to the second outer peripheral surface divided electrode 42 via the first floating electrode 41 ′, and the first outer peripheral surface divided electrode 41 to the fourth floating electrode 44 ′. Through the second outer peripheral surface divided electrode 43 via the second floating electrode 42 'and the second outer peripheral surface divided electrode 42, and from the third outer peripheral surface divided electrode 43 through the second floating electrode 42'. The polarization is performed in a direction from the third outer peripheral surface divided electrode 43 to the fourth outer peripheral surface divided electrode 44 through the third floating electrode 43 '.

Referring to FIG. 9 (b), in the piezoelectric ceramic hollow cylinder 40 polarized as shown in FIG. 9 (a), the first and second outer peripheral surface divided electrodes 41 and 42 adjacent to each other are connected to the third. The third and fourth outer peripheral surface divided electrodes 43 and 44 which are connected by the connection line 46a and which are adjacent to each other are connected to the fourth connection line 46a.
FIG. 3B shows a state of distortion generated in the cross-sectional direction of the hollow column 40 of the piezoelectric ceramics when a DC voltage is applied with the third connection line connected to the positive terminal and the fourth connection line connected to the negative terminal. In FIG. 9 (b), the electric field is applied in the direction shown by the solid arrow from the first outer peripheral surface divided electrode 41 through the fourth outer peripheral surface divided electrode 44 via the fourth floating electrode 44 '.
Between the first outer peripheral surface divided electrode 41-the fourth floating electrode 44'-the fourth outer peripheral surface divided electrode 44, the direction of polarization and the direction of the electric field are the same, and a circumferential elongation distortion occurs. The direction of polarization and the direction of the electric field are reversed between the third outer peripheral surface divided electrode 43 -the second floating electrode 42 ′ -the second outer peripheral surface divided electrode 42, and contraction distortion in the circumferential direction occurs. . As a result, in FIG. 9B, the piezoelectric ceramic hollow cylinder 40 is bent so that the lower side expands in the length direction. When the direction of the applied voltage is reversed, the direction of the bending is also reversed.

FIG. 10 is an explanatory view of the vibration state when the first and second AC voltages are applied to the polarized piezoelectric ceramic hollow cylinder 40 as shown in FIG. 9 (a). In FIG. 10 (a), the resonance of the bending vibration of the piezoelectric ceramic hollow cylinder 40 is provided between the first and fourth outer peripheral surface divided electrodes 41 and 44 and between the second and third outer peripheral surface divided electrodes 42 and 43. When a first AC voltage having a frequency and a first phase is applied, the piezoelectric ceramic hollow cylinder 40 generates a first bending vibration in the direction of arrow 47 as shown by a two-dot chain line in FIG. 10 (a). I do.

In FIG. 10 (a), similarly, between the first and second outer peripheral surface divided electrodes 41 and 42 and between the fourth and third outer peripheral surface divided electrodes 44 and 43, the piezoelectric ceramic hollow cylinder 21 When a second AC voltage having the same phase as the resonance frequency of the bending vibration and having the second phase is applied, the piezoelectric ceramic hollow cylinder 21 is moved in the second direction perpendicular to the direction of the arrow 47 shown in FIG. Generates bending vibration.

By the AC power supply shown in FIG. 4, the first and second secondary terminals 21 and 25 are connected to the first split electrode, the terminals 23 and 26 are connected to the second split electrode, and the terminals 24 and 28 are connected to the second split electrode. Third split electrode, terminal
22 and 27 are connected to the fourth divided electrode, respectively,
By shifting the phases of the first and second bending vibrations in the two directions perpendicular to each other as described above, specifically, the first and second AC driving voltages of the first and second AC driving voltages for exciting the respective bending vibrations are shifted. By shifting the first and second phases (preferably 90 °), the 10
An elliptical motion including a circle as shown by a two-dot chain line in FIG.

Next, a piezoelectric elliptical oscillator according to a fourth embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 11 shows the structure of a piezoelectric elliptical oscillator according to a fourth embodiment of the present invention. The same structure as that of the piezoelectric elliptical oscillator according to the second embodiment of the present invention shown in FIG. Shows the structure. 12 (a) and 12 (b) are cross-sectional views of the piezoelectric ceramic hollow cylinder 50 of FIG. 11 for explaining the state of occurrence of distortion of the piezoelectric elliptical oscillator, and FIG. 12 (a) is a piezoelectric ceramic hollow cylinder. Shows the connection method for 50 polarizations,
(B) shows a connection method for driving the piezoelectric ceramic hollow cylinder 50.

Referring to FIGS. 11 and 12 (a) and (b), the outer peripheral surface of the piezoelectric ceramic hollow cylinder 50 is divided into four equal parts in a circumferential direction parallel to the length direction of the piezoelectric ceramic hollow cylinder 50. The first, second, third, and fourth outer peripheral surface divided electrodes 51, 52, 53, 54 are formed in this order along the first and second inner peripheral surfaces of the piezoelectric ceramic hollow cylinder 50. ,
The first, second, third and fourth inner peripheral surface divided electrodes 5 are located at positions facing the third and fourth outer peripheral surface divided electrodes 51, 52, 53 and 54.
1 ', 52', 53 ', 54' are provided correspondingly.

Referring to FIG. 12 (b), the dashed arrows indicate the first, second,
The third and fourth outer peripheral surface division electrodes 51, 52, 53 and 54 are connected by a first connection line 55, and the first, second, third and fourth inner peripheral surface division electrodes 51 ', 52 , 53 'and 54' to the second connecting line 56.
And the first connection line 55 has a positive polarity and the second connection line
First and second connection lines 55 and 56 such that 56 has a negative polarity.
DC voltage is applied between the piezoelectric ceramic hollow cylinder
The direction of polarization when the polarization process is performed in the radial direction of the section 50 is shown. The polarization direction is a direction from the corresponding outer peripheral surface divided electrode to the inner peripheral surface divided electrode, and is a direction toward the center of the piezoelectric ceramic hollow cylinder.

Referring to FIG. 12 (b), in the piezoelectric ceramic hollow cylinder 50 polarized as shown in FIG. 12 (a), the first inner cylinders symmetrical to each other with respect to the longitudinal center line of the piezoelectric ceramic hollow cylinder 50. Peripheral surface and third outer peripheral surface divided electrode 51 ′;
53 is connected by a third connection line 58, the first outer peripheral surface and the third inner peripheral surface divided electrodes 51 and 53 'are connected by a fourth connection line 59, and the polarity of the first connection line is This shows a state of distortion generated in the cross-sectional direction of the hollow column 50 of the piezoelectric ceramic when a DC voltage is applied so that the polarity of the + and third connection lines becomes-.

In FIG. 12 (b), since the electric field is applied in the direction shown by the solid line arrow, the polarization direction and the electric field direction are between the first outer peripheral surface divided electrode 51 and the first inner peripheral surface divided electrode 51 '. Are reversed, a contraction strain occurs in the thickness direction, and the polarization direction and the electric field direction are the same between the second outer peripheral surface divided electrode 52 and the second inner peripheral surface divided electrode 52 ′. In this case, elongation strain occurs in the thickness direction. As a result, in FIG. 12 (b), the piezoelectric ceramic hollow cylinder 50 is bent so that the upper side expands in the length direction. When the direction of the applied voltage is reversed, the direction of the bending is also reversed.

FIG. 13 is an explanatory diagram of a vibration state when an AC voltage is applied to the polarized piezoelectric ceramic hollow cylinder 50 as shown in FIG. 12 (a).

In FIG. 13 (a), a third connection line 58 that electrically connects the first inner peripheral surface divided electrode 51 'and the third outer peripheral surface divided electrode 53, and a first outer peripheral surface divided electrode 51 are provided. When a first AC voltage equal to the resonance frequency of the bending vibration of the piezoelectric ceramic hollow cylinder 50 is applied between the third inner peripheral surface divided electrode 53 ′ and the fourth connection line 59 electrically connected thereto, the piezoelectric ceramic hollow The cylinder 50 generates the first bending vibration in the direction of the arrow 57 as shown by the two-dot chain line in FIG.

In FIG. 13 (a), similarly, a fifth connection line (not shown) electrically connecting the second inner peripheral surface divided electrode 52 'and the fourth outer peripheral surface divided electrode 54, Outer surface divided electrode 5
The sixth embodiment in which the 2 ′ and the fourth inner peripheral surface dividing electrode 54 are electrically connected.
Piezoelectric ceramic hollow cylinder between connecting wires (not shown)
When a second AC voltage having a second phase equal to the resonance frequency of the bending vibration of 50 is applied, the piezoelectric ceramic hollow cylinder 50 generates bending vibration in a direction perpendicular to the direction of the arrow shown in FIG. I do.

Therefore, by shifting the phases of the first and second bending vibrations in the two directions perpendicular to each other as described above, specifically, the first AC voltage of the first AC voltage for exciting each bending vibration. By shifting the phase and the second phase of the second AC voltage, the thirteenth
An elliptical motion including a circle as shown by a two-dot chain line in FIG.

FIGS. 12 (b) and 13 (a) show the case where the polarization directions are all the same (radiation direction) in each of the divided electrode pairs. If the directions are opposite (one is toward the center and the other is outside), connect the split electrodes with each split electrode pair,
If the opposing split electrode pairs have two terminals, the strain generated in each split electrode pair portion with respect to the same applied voltage is expanded and contracted, and the same bending vibration as described above is obtained.

[Effects of the Invention] As described above, according to the present invention, the shape of the piezoelectric vibrator is simple, and in particular, the cross section has a ring shape.
High-precision machining is possible, and an elliptical motion oscillator with little variation in resonance frequency in directions perpendicular to each other can be obtained.
In addition, the fact that the cross-section is ring-shaped means that, when an ultrasonic motor as shown in FIG. 14, for example, is formed, the state of contact with the cup-shaped rotary roller is good, and a stable motor can be obtained.

Furthermore, in the piezoelectric elliptical motion oscillator of the present invention, the fourteenth
The conventional piezoelectric motion vibrator shown in the figure uses the adhesive used for bonding the piezoelectric vibrator and the metal prism, but since the present invention is not used, the variation in characteristics due to bonding is smaller than the conventional one. A small number of elliptical oscillators can be obtained, and the effect is practically large.

[Brief description of the drawings]

FIG. 1 is a perspective view of a piezoelectric elliptical oscillator according to a first embodiment of the present invention, and FIGS. 2 (a) and 2 (b) illustrate the state of occurrence of distortion of the piezoelectric elliptical oscillator of FIG. Sectional view to be provided for
3 (a) and 3 (b) are perspective views showing vibration of the piezoelectric elliptical oscillator of FIG. 1, and FIG. 4 is an example of a drive circuit of an ultrasonic motor according to the first embodiment of the present invention. FIG. 5 is a perspective view of a piezoelectric elliptical oscillator according to a second embodiment of the present invention, and FIGS. 6 (a) and (b) show the occurrence of distortion of the piezoelectric elliptical oscillator of FIG. FIG. 7 (a) for explaining the state
7 (b) is a perspective view showing the vibration of the piezoelectric elliptical oscillator of FIG. 5, FIG. 8 is a perspective view of the piezoelectric elliptical oscillator according to the third embodiment of the present invention, FIG. (A) and (b) are cross-sectional views for explaining a state of occurrence of distortion of the piezoelectric elliptical oscillator of FIG. 8, and FIGS. 10 (a) and (b) are diagrams of the piezoelectric elliptical oscillator of FIG. FIG. 11 is a perspective view showing a vibration, FIG. 11 is a perspective view of a piezoelectric elliptical motion vibrator according to a fourth embodiment of the present invention, and FIG.
FIGS. 13A and 13B are cross-sectional views for explaining a state of occurrence of distortion of the piezoelectric elliptical oscillator of FIG. 11, and FIGS. 13A and 13B are piezoelectric elliptical oscillators of FIG. FIG. 14 is a perspective view showing the principle of operation of a piezoelectric elliptical oscillator according to the related art, and FIG. 15 is a perspective view showing the configuration of an ultrasonic motor using the piezoelectric elliptical oscillator according to the related art. FIG. In the figure, 10 is a piezoelectric ceramic hollow cylinder, 12, 13, 14, 15 are divided electrodes, 15, 16, 17, 18 are connection wires, 21, 22, 23, 24, 25, 26, 27,
28 is a terminal, 30 is a piezoelectric ceramic hollow cylinder, 31, 32, 33, 3
4 is an outer peripheral surface divided electrode, 31 ', 32', 33 ', 34' are inner peripheral surface divided electrodes, 35a, 35b, 35c, 35d, 36a, 40 are piezoelectric ceramic hollow cylinders, 41, 42, 43, 44 are Outer peripheral surface split electrode, 41 ', 42', 43 ',
44 'is a floating electrode, 45a, 45b, 46a, 46b are connection lines, 47 is an arrow, 50 is a hollow column of piezoelectric ceramics, 51, 52, 53, 54 are split electrodes, 51', 52 ', 53', 54 ' Is a split electrode, 55,56,58,59
Is a connection line, 57 is an arrow, 60a is a metal prism, 61a and 61b are piezoelectric ceramic thin plates, 62a and 62b are lead terminals, 63 is a ground terminal, 64a and 64b are discs, 65a and 65b are support pins, 66a and 66b. Is a cup-shaped rotating roller.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 41/08 L

Claims (4)

(57) [Claims] The first, second, third and fourth divided electrodes parallel to the longitudinal direction of the hollow column of the piezoelectric ceramic are located at positions where the circumference of the outer peripheral surface of the hollow column of the piezoelectric ceramic is divided into four equal parts. The first and third divisional electrodes facing each other are electrically connected by a first connection line, and the second and fourth divisional electrodes facing each other are connected to each other in the circumferential direction. And a DC voltage is applied so that the first connection line has a positive polarity and the second connection line has a negative polarity, thereby applying a voltage to the piezoelectric ceramic hollow cylinder. Polarized along the circumference in the direction from the first divided electrode to the second and fourth divided electrodes, and in the direction from the third divided electrode to the second and fourth divided electrodes; Between the first and fourth divided electrodes adjacent to each other and And applying a first AC voltage having a resonance frequency of the piezoelectric ceramic hollow cylinder and a first phase between the third divided electrode and a first bending vibration to the piezoelectric ceramic hollow cylinder. A second phase different from the first phase at the resonance frequency of the piezoelectric ceramic hollow cylinder between the first and second divided electrodes adjacent to each other and between the fourth and third divided electrodes. By applying a second AC voltage, a second bending vibration can be excited in the piezoelectric ceramic hollow cylinder, and an elliptical vibration can be excited at both ends of the piezoelectric ceramic cylinder by the first and second bending vibrations. A piezoelectric elliptical motion vibrator characterized in that: 2. A first, second, third and fourth outer circumferential surface division parallel to the length direction of the hollow piezoelectric ceramic cylinder at a position where the circumference of the outer peripheral surface of the hollow cylindrical ceramic ceramic is divided into four equal parts. Electrodes are sequentially applied along the circumferential direction, and the first, second, third, and fourth outer peripheral surface split electrodes are respectively opposed to the inner peripheral surface of the piezoelectric ceramic hollow cylinder, and the first, second, and fourth outer peripheral surface divided electrodes are respectively disposed. 3rd and 4th
Of the first, second, third, and fourth outer peripheral surface division electrodes and the first, second, third, and fourth inner peripheral surface division electrodes.
Are electrically connected to first, second, third, and fourth connection lines, respectively, and further, the first and third connection lines are electrically connected to a first terminal. And the second and fourth
Is electrically connected to the second terminal, and a DC voltage is applied between the first and second terminals such that the first terminal has a positive polarity and the second terminal has a negative polarity. To the direction of the second and fourth outer peripheral surfaces and the inner peripheral surface divided electrodes from the first outer peripheral surface and the inner peripheral surface divided electrodes, and the third outer peripheral surface and the inner peripheral surface. Polarization is performed in the direction from the divided electrode to the divided electrodes on the second and fourth outer peripheral surfaces and the inner peripheral surface, and the first and second connection lines and the third and fourth connection lines adjacent to each other are electrically connected. The third and fourth terminals are connected to each other, and a first AC voltage having a resonance frequency of the piezoelectric ceramic hollow cylinder and a first phase is applied between the third and fourth terminals. A first bending vibration can be excited in a piezoelectric ceramic hollow cylinder, and the first bending vibration And the fourth and fourth connection lines and the second and third connection lines are electrically connected to form fifth and sixth terminals, between the fifth and sixth terminals at the resonance frequency of the piezoelectric ceramic hollow cylinder, And a second phase different from the first phase
A second AC voltage having a phase of: is applied to the piezoelectric ceramic hollow cylinder to excite a second bending vibration, and the first and second bending vibrations cause elliptical vibration to be applied to both ends of the piezoelectric ceramic cylinder. A piezoelectric elliptical oscillator that can be excited. 3. A first, second, third and fourth outer circumferential surface division parallel to the longitudinal direction of the hollow piezoelectric ceramic hollow column at a position which divides the circumference of the outer peripheral surface of the hollow cylindrical piezoelectric ceramic into four equal portions. Electrodes are sequentially applied in the circumferential direction, and the inner peripheral surface of the piezoelectric ceramic hollow cylinder is disposed between the first and second outer peripheral surface divided electrodes,
The first and second positions are respectively located at positions corresponding to between the second and third outer peripheral surface divided electrodes, between the third and fourth outer peripheral surface divided electrodes, and between the fourth and first outer peripheral surface divided electrodes. Applying third and fourth floating electrodes to electrically connect the first and third outer peripheral surface divided electrodes with a first connection line, and to connect the second and fourth outer peripheral surface divided electrodes to each other. A DC voltage is applied such that the first connection line has a positive polarity and the second connection line has a negative polarity. Along the circumference of the cylinder, the first outer peripheral surface divided electrode passes through the first floating electrode to the second outer peripheral surface divided electrode, and from the first outer peripheral surface divided electrode to the fourth floating electrode. Through the fourth
And from the third divided electrode to the second outer peripheral surface divided electrode via the second floating electrode,
And polarized in a direction from the third outer peripheral surface divided electrode to the fourth outer peripheral surface divided electrode via the third floating electrode, and further, between the first and fourth outer peripheral surface divided electrodes adjacent to each other, And applying a first AC voltage having a resonance frequency of the piezoelectric ceramic hollow cylinder and a first phase between the second and third outer peripheral surface divided electrodes to cause a first bending to the piezoelectric ceramic hollow cylinder. Vibration can be excited, and at the resonance frequency of the piezoelectric ceramic hollow cylinder between the first and second outer peripheral surface divided electrodes adjacent to each other and between the fourth and third outer peripheral surface divided electrodes, and Applying a second AC voltage having a second phase different from the first phase;
A second bending vibration being excitable to the piezoelectric ceramic hollow cylinder, and an elliptical vibration being able to be excited at both ends of the piezoelectric ceramic cylinder by the first and second bending vibrations. Child. 4. A first, second, third and fourth outer circumferential surface division parallel to the length direction of the hollow piezoelectric ceramic cylinder at a position where the circumference of the outer peripheral surface of the hollow cylindrical piezoelectric ceramic is divided into four equal parts. Electrodes are sequentially applied along the circumferential direction, and the first and second electrodes are respectively positioned along the inner peripheral surface of the hollow column of the piezoelectric ceramic at positions opposed to the first, second, third, and fourth outer peripheral surface divided electrodes. 2,
Third and fourth inner peripheral surface division electrodes are provided, and the first, second, third and fourth outer peripheral surface division electrodes are electrically connected by a first connection line, and the first and second inner peripheral surface division electrodes are connected to each other. 2, 3rd and 4th
Are electrically connected by a second connection line, and a DC voltage is applied so that the first connection line has a positive polarity and the second connection line has a negative polarity. Thereby, the first, second,
Performing a polarization process in a radial direction from the third and fourth inner peripheral surface division electrodes to the first, second, third and fourth outer peripheral surface division electrodes, respectively, and further performing the first inner peripheral surface division electrode; And the first
At the resonance frequency of the piezoelectric ceramic hollow cylinder and at the first phase between the outer peripheral surface divided electrode and the third outer peripheral surface divided electrode and the third inner peripheral surface divided electrode. (1) applying a first AC voltage to the piezoelectric ceramic hollow cylinder so as to excite the first bending vibration between the second inner peripheral surface divided electrode and the second outer peripheral surface divided electrode; and A second AC voltage having a resonance frequency of the piezoelectric ceramic hollow cylinder and a second phase different from the first phase is applied between the outer peripheral surface divided electrode and the fourth inner peripheral surface divided electrode. A second bending vibration can be excited in the piezoelectric ceramic hollow cylinder, and an elliptical motion can be excited in both ends of the piezoelectric ceramic hollow cylinder by the first bending vibration and the second bending vibration. Piezoelectric elliptical motion oscillator.