JP2607087B2 - Ultrasonic drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic drive device in which electrodes formed on inner and outer surfaces of a cylindrical piezoelectric vibrator are divided by providing a gap.

2. Description of the Related Art In recent years, there has been proposed an ultrasonic motor in which an AC voltage is applied to a piezoelectric vibrator such as a ring-shaped or disk-shaped ceramic piezoelectric body, and a rotating body is pressed against an end face or a side face of the piezoelectric vibrator.

Problems to be Solved by the Invention However, in these conventional ultrasonic motors,
Adjacent parts of the ring-shaped piezoelectric vibrator constitute a number of polarized parts that are polarized in the opposite direction to each other, and AC voltages that are 90 ° out of phase with each other must be applied to each polarized part. However, there is a problem that the configuration becomes complicated.

Similarly, a disk-shaped piezoelectric vibrator is also partially polarized, and electrodes are respectively provided on the polarized portions, and a voltage is applied to generate rotational vibration on the side surface, but the configuration is complicated. There was a problem.

Means for Solving the Problems In order to solve the above problems, the present invention provides a cylindrical ceramic piezoelectric vibrator polarized between an inner surface and an outer surface, and a cylindrical piezoelectric vibrator on the inner and outer surfaces of the piezoelectric vibrator. Are formed by two opposing gaps formed linearly in the axial direction of
An inner electrode and an outer electrode, wherein the inner and outer electrodes are separated from each other at a desired angle, and a part of the divided portion is overlapped on the inner and outer surfaces. And a rotating body combined with an end face or a side face of the piezoelectric vibrator to apply an AC voltage of one frequency to each of the divided electrodes.

According to the present invention, the inner electrode and the outer electrode of the cylindrical piezoelectric vibrator are each separated by two opposing gaps.
And the two opposing gaps are shifted at a desired angle so that a part of the divided part is overlapped on the inner surface and the outer surface, and each of the inner electrode and the outer electrode is divided into one. By applying an AC voltage of one frequency, a rotating vibration that rotates forward or backward is generated on the end face or side face of the piezoelectric vibrator. By combining the rotating body with the portion where the rotating vibration is generated, the rotating body is rotated. Can be rotated.

Embodiment FIG. 1 is a structural view of a stator of an ultrasonic driving apparatus according to an embodiment of the present invention. The inner surface and the outer surface of a piezoelectric vibrator 1 such as a cylindrical ceramic vibrator polarized inward and outward are respectively provided with cylindrical members. Linear gaps 2c, 2d and 3c, 3d formed in the axial direction
The inner electrodes 2a and 2b and the outer electrodes 3a and 3b divided by are provided. Then, the gap 2 between the inner electrodes 2a, 2b and the outer electrodes 3a, 3b
By disposing c, 2d and 3c, 3d at a desired angle from each other, each of the inner electrodes 2a, 2b and the outer electrodes 3a, 3b is configured to partially overlap, and these divided inner electrodes A power source P of one frequency is connected to one of 2a, 2b and the outer electrodes 3a, 3b, for example, the inner electrode 2a and the outer electrode 3a.

In the thus configured stator 4 of the present embodiment, when an AC voltage is applied to the inner electrode 2a and the outer electrode 3, a rotational vibration rotating in one direction is generated as shown by an arrow A in FIG. When an AC voltage is applied to the electrode 2b and the outer electrode 3b, a rotational vibration that rotates in the opposite direction is generated as shown by an arrow B in FIG.

This is because, when considering a diagram in which a half of a cylinder is developed as shown in FIG. 3 (a), for example, when an AC voltage is applied to the inner electrode 2a and the outer electrode 3a, the electrode extends in the direction of arrow DE and the arrow FG Direction. This also causes radial vibration as indicated by arrow F in FIG. 3 (b). Therefore, the piezoelectric vibrator 1 on the side to which the voltage is applied generates radial vibration and the vertical vibration due thereto, but the radial vibration of the piezoelectric vibrator 1 on the side to which no voltage is applied and the vertical vibration due thereto. Since no vibration is generated, it is considered that the generated radial vibration and longitudinal vibration generate rotational vibration such that the higher surface C is wavy. Also, for example, the inner electrode 2b
Similarly, when an AC voltage is applied to the outer electrode 3b, a rotational vibration in the opposite direction is generated so as to undulate.

Therefore, as shown in FIG. 4, when the rotating body 5 is pressed against the end face of the stator 4, the rotating body 5 rotates very well.
Further, even when the rotating body 5 was brought into contact with the side surface, it rotated very well.

Note that, even if the application direction of the AC voltage is reversed and the AC voltage is applied, for example, like the inner electrode 2a and the outer electrode 3b or the outer electrode 3a of the inner electrode 2b, rotational vibrations in the opposite directions are similarly generated. Further, the gaps 2c and 3c and the gaps 2d and 3d are provided to be shifted from each other at a desired angle, but when the gaps are shifted by approximately 45 ° or 90 °, it is possible to maintain a stable state in order to reverse the rotational vibration. The position is not strict and can be set arbitrarily. Further, gaps 2c, 3c and 2d
The 3d may not be displaced at all and may be in a position facing each other, but in that case, it rotates only in one direction.

As a specific configuration, as shown in FIG. 5, the bearing 7 of the case 6 supports the rotating shaft 5a of the rotating body 5 and the thrust bearing 8 smoothes the rotation in the axial direction. The end face of the stator 4 is brought into contact with the
By pressing and tightening the spring washer 9 with the bottom cover 10 of the above, the rotating body 5 is pressed against the stator 4, and an AC voltage is applied to any of the inner electrodes 2a, 2b and the outer electrodes 3a, 3b to the electrodes. , The rotating body 5 can be rotated.

In addition, as shown in FIG.
The rotating shaft 5a of the rotating body 5 is supported by the bearing 7 of the case 6, a support plate 12 is provided between the ball 11 and the inner surface of the case 6, and a contact plate 13 is provided on the stator 4. Are provided and are in contact with the ball 11. By pressing and tightening the spring washer 9 with the bottom cover 10 of the case 6, the ball 11 of the rotating body 5 is pressed against the stator 4, and the AC voltage is applied to the inner electrode 2a and the outer electrodes 3a, 3b.
, The ball 11 rotates in one direction, and by applying the voltage to either the inner electrode 2b or the outer electrodes 3a, 3b, the rotator 5 rotates in the direction. Further, in the stator of this embodiment, the electrodes are provided on the inner surface or the outer surface, and the rotating body can be received on the end face of the hard ceramic piezoelectric body. .

Although the cylindrical piezoelectric vibrator of the above embodiment has a long axial length, this embodiment has been described. However, a piezoelectric vibrator having a short axial length may similarly generate rotational vibration. it can.

FIGS. 7 (a) and 7 (b) are schematic views of another embodiment of the present invention using a short piezoelectric vibrator for moving a lens barrel of a camera. In FIG. 7, a lens barrel 17 having a lens 16 mounted thereon is fitted into a case 15, and a projection 18 provided on the case 15 has a groove 17 provided in an axial direction on the outer surface of the lens barrel 17.
a, 17b, a helical groove 19 is provided on the outer surface of the lens barrel 17, and a case 15 is provided outside the lens barrel 17.
The side surfaces of the piezoelectric vibrator 1 having a short axial length are supported by the projections 20 of the piezoelectric vibrator 1.
And the lid 23 is fitted to the case 15 via the spring washer 22 to press the rotating body 21 in pressure. Further, a projection 24 inserted in the helical groove 19 is provided on the inner surface of the rotating body 21.

In the camera having such a configuration, when the AC voltage is applied to the piezoelectric vibrator 1 as described above, the torque is large. Therefore, the rotating body 21 rotates, and the lens barrel 17 is moved through the helical groove 19. It moves left and right in FIG. 7 (a). Further, since the rotating body 21 is pressed against the piezoelectric vibrator 1 by the spring washer 22, when the AC voltage is cut off,
Since the rotating body 21 reliably stops at that position, there is no need to provide a mechanism for stopping the movement due to inertia unlike a conventional motor.

In the embodiment, the divided electrodes of the inner electrode 2 and the outer electrode 3 are used.
The gaps 2c, 2d, 3c, 3d between 2a, 2b, 3a, 3b are provided parallel to the axial direction of the cylinder, but as shown in FIG. 8, the gaps 2c, 2d,
Even if 3c and 3d are provided to be inclined with respect to the axis, rotational vibration can be generated similarly.

Effect of the Invention As is apparent from the above description, the present invention provides a gap facing the inner electrode and the outer electrode of the cylindrical piezoelectric pair vibrator and divides the gap into two or more, and divides these gaps into desired ones. The inner electrode and the outer electrode, which are shifted by an angle, are configured so that a part of each of the divided inner electrode and the outer electrode overlap with each other. By applying an AC voltage of one frequency to each of the divided electrodes of the inner electrode and the outer electrode, the end face or Rotational vibration that rotates forward or reverse occurs on the side surface.By combining the rotating body with the part where this rotational vibration occurs, the rotating body is combined by the combination of the voltage application directions of the divided electrodes of the inner electrode and the outer electrode. Since the rotation can be made forward and reverse, by combining the rotating body with the portion where this rotational vibration occurs, the combination of the inner electrode, the outer electrode, and the outer electrode in the voltage application direction,
The rotating body can be rotated, and the structure is simple, so that a small ultrasonic motor can be made, and it can be used for various purposes such as driving a camera lens. There are advantages.

[Brief description of the drawings]

FIG. 1 is a structural view of a stator of an ultrasonic driving apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are diagrams for explaining the operating principle of the stator of FIG. 1, and FIG. FIG. 5 is a schematic configuration diagram of an ultrasonic driving device according to an embodiment of the present invention. FIG. 5 and FIG. 6 are specific structural diagrams of the ultrasonic driving device of the present invention. Schematic configuration diagram of the trunk part,
FIG. 8 is a perspective view of a stator of an ultrasonic driving apparatus according to still another embodiment of the present invention. 1 ... piezoelectric vibrator, 2, 3 ... inner electrode and outer electrode, 2
a, 2b, 3a, 3b ... divided electrodes, 2c, 2d, 3c, 3d ... gaps, 4 ... stators, 5 ... rotating bodies.

Claims (4)

(57) [Claims] A cylindrical ceramic piezoelectric vibrator polarized between an inner surface and an outer surface, and two opposing gaps formed on the inner and outer surfaces of the piezoelectric vibrator in a straight line in the axial direction of the cylinder. An inner electrode and an outer electrode, each of which is divided into two, the gap between the inner surface and the outer surface is shifted at a desired angle, and a part of the divided portion is overlapped on the inner surface and the outer surface, and Applying an AC voltage of one frequency to each divided electrode of the outer electrode 1
An ultrasonic drive device comprising: an AC power supply; and a rotating body combined with an end face or a side face of the piezoelectric vibrator. 2. The ultrasonic driving apparatus according to claim 1, wherein a deviation of a linear gap between each of said inner electrode and said outer electrode is 45 °. 3. The ultrasonic driving apparatus according to claim 1, wherein a deviation of a linear gap between each of said inner electrode and said outer electrode is 90 °. 4. The apparatus according to claim 1, wherein the gap between the inner electrode and the outer electrode is inclined with respect to the axis of the cylinder. Ultrasonic drive.