JPS63228979A - Ultrasonic driving gear - Google Patents

Abstract

PURPOSE:To facilitate manufacture and reduce the cost, by providing a part of a ring with a cut-off section to form a ring-formed piezoelectric oscillator, and by applying an AC field in the direction of the thickness to generate a traveling wave. CONSTITUTION:A ring-formed piezoelectric oscillator 4 is provided with a cut-off section 5 formed to cut off a part of the ring with a slight void, and on both the surfaces, electrodes 6-7 are respectively arranged, and polarization is performed in the direction of the thickness. When the AC field of specified frequency is applied to the oscillator 4 from an oscillating unit, then traveling waves in the directions A(B) of arrow heads are generated near the cut-off section. An ultrasonic wave driving gear is composed of said oscillator 4, and the driven unit 11 of a rotary body supporting a rotary shaft 10 on the side surface 9 near the cut-off section 5 with a bearing or the like. Then, the driven unit 11 can be rotated in the forward or reverse direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic drive device that drives a driven body using a ring-shaped piezoelectric vibrator, which is formed by cutting a ring with a minute gap.

Prior Art The currently proposed ultrasonic motor has two sets of electrodes bonded to one side of a circular piezoelectric ceramic, and the electrodes are arranged so that the standing waves excited by each electrode set are shifted by 90''. Furthermore, two sets of oscillators are connected to each other, and the alternating current electric fields applied to these two sets of electrode groups have a temporal phase difference of 90'.

The conventional ultrasonic motor configured in this way generates two standing waves with a phase shift of 90'' on the surface around the annular piezoelectric ceramic by applying an alternating electric field from two sets of oscillators to each electrode group. A traveling wave is generated by combining these two standing waves.Therefore, a toroidal moving body is placed on top of the comb-shaped vibrating body bonded to the toroidal piezoelectric ceramic to make contact. If it is strong, the moving object will be moved by the traveling wave.

However, this conventional ultrasonic motor requires multiple electrodes and two sets of oscillators to apply an alternating electric field to these electrodes, making the electrode configuration difficult. It is complicated, and the structure of the vibrating body is also complicated, resulting in a problem of high cost.

In order to solve the above-mentioned problems, the present invention applies an alternating current electric field in the thickness direction of a ring-shaped piezoelectric vibrator in which a part of the ring is cut with a minute gap. By applying , a traveling wave from the side surface of the piezoelectric vibrator toward the cutting section or a traveling wave from the cutting section toward the side surface is generated in the vicinity of the cutting section of the piezoelectric vibrator. and a driven body is combined in the vicinity of the cut portion of the piezoelectric vibrator.

According to the present invention, an alternating current set at two frequencies is applied in the thickness direction of a ring-shaped piezoelectric vibrator in which a cut portion is provided by cutting a part of the ring-shaped piezoelectric vibrator with a minute gap. When an electric field is applied, 1
At one frequency, a traveling wave that moves from the side and upper and lower surfaces of the piezoelectric vibrator toward the cutting section is generated, and at the other frequency, a traveling wave that moves from the cutting section toward the side and upper and lower surfaces is generated. By combining the driven body near the cut portion of the piezoelectric vibrator, the driven body can be driven.

Figure 1 is a perspective view and a plan view of a ring-shaped piezoelectric vibrator.
is polarized in the thickness direction, and electrodes 2 and 3 are provided on the upper and lower surfaces of the piezoelectric vibrator 1. This piezoelectric vibrator 1
When an alternating current electric field is applied through electrode 2.3 to
As shown by arrow A in b), traveling waves are generated from the outer circumference 1a to the inner circumference 1b on both sides of the ring, and on the side surfaces, as shown in Fig. 1 (
The inventor discovered that a traveling wave moving inward from the electrode 2.3 side is generated as shown by arrow B in a).

However, in this piezoelectric vibrator 1, no traveling waves moving in the circumferential direction are generated on the side and upper and lower surfaces.

FIG. 2 is a plan view and a side view of a piezoelectric vibrator used in the present invention. In FIG. 2(a), a ring-shaped piezoelectric vibrator 4 is cut in a part with a minute gap. In addition, electrodes 6 and 7 are provided on both sides of the piezoelectric vibrator 4, and the piezoelectric vibrator 4 is polarized in the thickness direction.

When an alternating current electric field of a certain predetermined frequency is applied from an oscillator to the piezoelectric vibrator 4 configured in this way through the electrode 6.7, a cut occurs near the cutting portion 5 from the side surface 8.9 of the piezoelectric vibrator 4. A traveling wave as shown by the arrow A' is generated, which travels toward the section 5, and when an AC electric field with a predetermined frequency different from the above frequency is applied to the piezoelectric vibrator 4 via the electrode 6.7, the wave shown by the arrow A' is generated. It was discovered that a traveling wave moving from the cut portion 5 toward the side surface 8.9 was generated as shown in B. Note that, as shown in FIG. 2(b), the cut portion 5 of the piezoelectric vibrator 4
Similarly to arrows A and B in FIG. 2(a), traveling waves shown by arrows C or D are generated on the upper and lower surfaces near the piezoelectric vibrator 4 at respective frequencies. It was discovered that a traveling wave toward the inner periphery of the ring, indicated by arrow A in FIG. 1(b), was generated on the electrode surface 6.7 other than in the vicinity.

Although the principle by which this traveling wave is generated is not very clear, when vibration in the thickness direction occurs in the piezoelectric vibrator 4, an outer vibration that is out of phase with the vibration by 90 degrees is generated. Here, since the piezoelectric vibrator 4 has the cut portion 5, the thickness vibration and the outer shell vibration are intricately related to generate tuning fork-like vibrations, which proceed to the vicinity of the cut portion 5 of the piezoelectric vibrator 4. It is thought that waves are generated.

FIG. 3 is a perspective view of an ultrasonic driving device according to an embodiment of the present invention, in which a rotary shaft 10 is mounted on a side surface 9 near the cutting portion 5 of the piezoelectric vibrator 4 described above, and is mounted on a rotating body supported by a bearing or the like. The driven bodies 11 are combined.

In the ultrasonic drive device of this embodiment configured as described above, the frequency of the alternating current electric field applied to the piezoelectric vibrator 4 is set to two predetermined frequencies.
1 can be rotated forward or reverse.

The ultrasonic driving device of this embodiment has a simple configuration in which an alternating current electric field is applied in the thickness direction of the disc-shaped piezoelectric vibrator 1 from the oscillator, and therefore it is easy to manufacture and can be easily manufactured using a small motor. Even large motors can be easily manufactured.

FIG. 4 is a plan view of an ultrasonic driving device according to another embodiment of the present invention, in which a rod-shaped driven body 11 is engaged with a side surface 9 of a piezoelectric vibrator 4 near a cutting portion 5. Note that this rod-shaped driven body 11 is supported by a bearing or the like so that it can slide in the axial direction.

In the ultrasonic drive device of this embodiment configured in this way, 2
By setting the two frequencies, it is possible to move the rod-shaped driven body 11 to the left and right in the figure, so it can be used as a linear motor. In this embodiment, two or more piezoelectric vibrators 4 may be provided on the rod-shaped driven body 11 depending on the torque for driving the driven body 11.

In this way, in the above embodiment, the ring-shaped piezoelectric vibrator 4
The driven body 11 is driven by a traveling wave generated on the side surface 9 near the cutting section 5 of the piezoelectric vibrator 4. Even if they are combined, the driven body 11 can be driven in the same way. Note that when the driven body 11 is to be engaged with the upper and lower surfaces of the piezoelectric vibrator 4, wear-resistant contact plates may be provided integrally with or separate from the electrode 6 to prevent the electrode from being worn.

Results of the Invention As is clear from the above description, the present invention provides two alternating currents of predetermined frequencies in the thickness direction of a ring-shaped piezoelectric vibrator in which a part of the ring has a cut portion with a minute gap. It has a simple configuration in which the driven body is driven by a traveling wave generated near the cutting part of the piezoelectric vibrator or moving from the side and upper and lower surfaces toward the cutting part by applying an electric field. Not only is it easy to manufacture and can reduce costs, but it can also provide a large amount of torque.
There is also the advantage that an ultrasonic drive device with good performance can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view and a plan view of a ring-shaped piezoelectric vibrator,
2 is a perspective view and a plan view of a ring-shaped piezoelectric vibrator used in the present invention, FIG. 3 is a perspective view of an ultrasonic drive device according to an embodiment of the present invention, and FIG. 4 is a perspective view of another embodiment of the present invention. FIG. 1 is a perspective view of an ultrasonic driving device according to an embodiment. 4... Piezoelectric vibrator, 5... Cutting section, 6.7...
Electrode, 8.9... Side surface, 10... Rotating shaft, 11...
- Driven object.

Claims (3)

[Claims] (1) By applying an alternating current electric field in the thickness direction of a ring-shaped piezoelectric vibrator in which a cut portion with a minute gap is provided in a part of the ring, the piezoelectric vibrator is placed near the cut portion of the piezoelectric vibrator. Generating a traveling wave from a side surface of the body vibrator toward the cutting portion or a traveling wave traveling from the cutting portion toward the side surface,
An ultrasonic driving device characterized in that a driven body is combined in the vicinity of the cutting portion of the piezoelectric vibrator. (2) The ultrasonic driving device according to claim 1, wherein the driven body is driven by a plurality of the piezoelectric vibrators. (3) By setting the frequency of the alternating current electric field to two predetermined frequencies, the traveling wave moves toward the cut section of the piezoelectric vibrator at one frequency and from the cut section toward the side surface at the other frequency. 2. The ultrasonic driving device according to claim 1, wherein the ultrasonic driving device is configured to generate the following.