JP2585574B2 - Ultrasonic drive using a ring-shaped piezoelectric vibrator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic driving apparatus using a ring-shaped piezoelectric vibrator for driving a driven body by a ring-shaped piezoelectric vibrator.

Conventional technology The currently proposed ultrasonic motor has two sets of electrodes adhered to one side of a ring-shaped piezoelectric ceramic, and the electrodes are arranged so that the standing waves excited by the respective electrode groups are shifted by 90 ° in position. Further, two sets of oscillators having an AC electric field applied to these two sets of electrodes having a 90 ° phase difference in time are connected to each other.

In the conventional ultrasonic motor configured as described above, two standing waves having phases shifted by 90 ° are applied to the surface around the ring-shaped piezoelectric ceramic by applying an AC electric field to each electrode group from two sets of oscillators. Then, a traveling wave in which the two standing waves are combined is generated. Therefore, when the ring-shaped moving body is placed on the comb-shaped vibrating body adhered on the ring-shaped piezoelectric ceramic and the contact is strengthened, the moving body is moved by the traveling wave.

Problems to be Solved by the Invention However, this conventional ultrasonic motor requires a plurality of electrodes and two sets of oscillators for applying an AC electric field to these electrodes, so that the configuration of the electrodes is complicated, The structure of the body is complicated, and there has been a problem that the cost is high.

Means for Solving the Problems The present invention solves the above problems by mounting electrodes on both sides of a ring-shaped piezoelectric element polarized in the thickness direction, and applying an AC voltage from an oscillator to the electrodes. By combining the vibration in the thickness direction and the vibration in the radial direction of the piezoelectric element, a traveling wave toward the center of the inner diameter of the piezoelectric element is continuously generated on both surfaces of the piezoelectric element, and the electrodes of the piezoelectric element It is characterized in that a vibration transmitting substance is mounted thereon, and a driven body is combined with the vibration transmitting substance.

According to the present invention, when an AC voltage is applied to the electrodes provided on both sides of the ring-shaped piezoelectric element, the piezoelectric element travels toward the center of the inner diameter of the piezoelectric element by combining the vibration in the thickness direction and the vibration in the radial direction of the piezoelectric element. Since a wave can be continuously generated on both sides of the piezoelectric element, the continuous traveling wave is extracted by a vibration transmitting substance mounted on the electrode of the piezoelectric element, and a driven body is combined with the vibration transmitting substance. This is for driving the driven body.

Embodiment Before describing an embodiment of the present invention, the principle will be described. First, when a ring-shaped piezoelectric element 1 such as a piezoelectric ceramic shown in FIG. 1 is polarized in a thickness direction and an AC electric field is applied from an oscillator 4 through electrodes 2 and 3 mounted on both surfaces of the ring-shaped piezoelectric element, As shown in FIG. 2, it has been found that the surface displacement moves from the outer periphery to the inner periphery of the piezoelectric element 1 as shown by arrows. This will be described with reference to the cross-sectional view of the piezoelectric element shown in FIG. 3. First, when the piezoelectric element 1 expands in the thickness direction, that is, in the direction of arrow A, the inner diameter does not change and the outer diameter changes This bulge appears as a surface displacement moving in the inner diameter direction, that is, an arrow B. When the piezoelectric element 1 contracts in the thickness direction, that is, in the direction of arrow C, as indicated by the one-dot chain line 5, the piezoelectric element 1
The inner diameter of the piezoelectric element 1 hardly changes and expands in the outer diameter direction while shrinking in the thickness direction, so that a displacement appears in the direction of the arrow D inside the piezoelectric element 1, but this displacement does not appear on the surface at all, and therefore moves in the inner diameter direction. Only the surface displacement (arrow B) occurs on both surfaces of the piezoelectric element 1. In the above description, an AC electric field is applied in the thickness direction of the piezoelectric element 1. However, even when an AC electric field is applied in the inner and outer peripheral directions, a surface displacement that moves in the inner peripheral direction also appears.

Next, a description will be given of an embodiment of the present invention for driving a driven body with a displacement toward the inner periphery of the piezoelectric element 1.

As shown in FIG. 4 (a), a contact 7 is bonded to a part of the ultrasonic vibrator 1, and as shown in FIG. It is composed of a protruding disk. Then, as shown in FIG. 5, the contact 7 of the piezoelectric element 1 is brought into contact with the driven body 8 to apply an AC electric field to the piezoelectric element 1. Here, the positional relationship between the driven body 8 and the contact 9 of the piezoelectric element 1 is based on the movement direction of the displacement of the contact 9 (arrow) and the rotation direction of the driven body 8 (a line passing through the center of the driven body 8). (A direction orthogonal to the direction).

According to this embodiment, the driven body 8 can be driven by such a configuration.

FIG. 6 is a configuration diagram of a driving device according to an embodiment of the present invention using the above principle, in which a ring-shaped piezoelectric element 1 is fixed to a case 10 by a support 11 and is disposed above the piezoelectric element 1 in the thickness direction. A metal or other member contact plate 12 is provided.
When the electrodes 2 and 3 are provided in the thickness direction, the contact plate 12 may be shared with the electrodes 2 or 3. Further, the rotation shaft 9 of the driven body 8 is directed by bearings 14 and 15 provided in the case 10 through the center hole 1c of the ring-shaped piezoelectric element 1 to bring the driven body 8 into contact with the contact plate 12. In order to strengthen the contact between the driven body 8 and the contact plate 12, a roller 16 indicated by a bearing 17 is mounted on the opposite side of the driven body 8 from the contact plate 12 by a spring.
It is configured to press at 18.

In the driving device of the present embodiment configured as described above, when an AC electric field is applied to the piezoelectric element 1 from the oscillator, the driven body 8 rotates according to the above-described principle. Can be.

FIG. 7 is a configuration diagram of a driving device according to another embodiment of the present invention, wherein 1a and 1b are piezoelectric elements, 7a and 7b are contact plates, 8 is a driven body, 9 is a rotating shaft, 10 is a case, 14 , 15 is a bearing, 18
Are springs, and their configurations are substantially the same as those in the above-described embodiment, and therefore description thereof will be omitted.
Is held between the piezoelectric elements 1a and 1b, and the piezoelectric element 1b is pressed by the spring 18 against the driven member 8.

In the driving device of the present embodiment configured as described above,
When the piezoelectric elements 1a and 1b generate the same surface displacement, the driven body 8 can be rotated with twice the strength of the above-described embodiment.

FIG. 8 is a configuration diagram of a driving device according to another embodiment of the present invention, in which a rotating body 19 is brought into contact with a piezoelectric element 1 as a driven body 8, and a surface displacement of the piezoelectric element 1 occurs. The rotating shaft 20 is supported by bearings 21 and 22 so that the rotating body 19 rotates in the opposite direction, and the rotating body is pressed by springs 23 and 24.

Also in the present embodiment configured as described above, the rotating body 19 can be rotated.

FIG. 9 is a block diagram of a driving device according to another embodiment of the present invention, in which a rod 25 is mounted on a contact 7 of a piezoelectric element 1 with a bearing 2.
It is slidably supported in the axial direction by 6, 27 and pressed by springs 28, 29.

In the present embodiment configured as described above, the rod can be driven in the axial direction, and is operated as a linear motor.

Advantageous Effects of the Invention As is apparent from the above description, the present invention drives a driving body by a surface displacement that moves toward a center generated by applying an AC electric field in a thickness direction or a radial direction of a ring-shaped piezoelectric element. In addition, there is an advantage that a drive device that can not only be simple in configuration, easy to manufacture and low in cost but also can take large torque can be provided.

[Brief description of the drawings]

1 is a sectional view of a ring-shaped piezoelectric element, FIG. 2 is a plan view of the ring-shaped piezoelectric element, FIG. 3 is a view for explaining the principle of the driving device of the present invention, and FIG. FIG. 5 is a sectional view of an ultrasonic motor according to an embodiment of the present invention, FIG. 6 is a sectional view of an ultrasonic motor according to another embodiment of the present invention, and FIG. FIG. 9 to FIG. 9 are configuration diagrams of another embodiment of the present invention. 1 ... piezoelectric element, 2, 3 ... electrode, 4 ... oscillator, 5 ...
... rotor, 6 ... wings, 7 ... case, 8 ... support,
9 Contact plate, 10 Rotary shaft, 11 Bearing, 12
... ball, 13 ... leaf spring, 14 ... bearing, 15 ... roller support, 16 ... roller, 17 ... spring.

Claims (2)

(57) [Claims] An electrode is mounted on both sides of a ring-shaped piezoelectric element polarized in a thickness direction, and an AC voltage is applied to the electrode from an oscillator, so that a vibration in the thickness direction and a vibration in a radial direction of the piezoelectric element are generated. By synthesis, a traveling wave toward the center of the inner diameter of the piezoelectric element is continuously generated on both surfaces of the piezoelectric element,
A vibration transmitting substance is mounted on the electrode of the piezoelectric element,
An ultrasonic driving device using a ring-shaped piezoelectric vibrator, wherein a driven body is combined with the vibration transmitting material. 2. An ultrasonic driving apparatus using a ring-shaped piezoelectric vibrator according to claim 1, wherein said vibration transmitting substance is a wear-resistant substance.