JPH04125076A - Ultrasonic wave motor - Google Patents

Abstract

PURPOSE:To relatively increase a torque in a small size by inserting a protrusion of a stationary plate to the bore of a rotor, and bringing the plate axially into pressure contact with the rotor through an elastic element by a spring. CONSTITUTION:The end of a twisting vibrator of a longitudinal-twisting composite vibrator 10 is secured by a support 3 including a first bearing 12 so as to be excited by a twisting vibration of 1/4 wavelength. A wear resistant member layer 14 is formed on the end of the vibrator 10, the protrusion 17a of a rotor stationary plate 17 is engaged within a rotor bore 15a through a ringlike rotor 15 and an elastic element 16, and brought into pressure contact therewith by a leaf spring 18. In the case of operation, a shaft 20 which passes through the bearing 12 and a second bearing 19 is rotated integrally with the rotor 15.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a so-called ultrasonic motor using piezoelectric vibration of a piezoelectric vibrator used in OA equipment, cameras, etc. This relates to the structure of a small motor.

(Prior Art) FIG. 6 is a perspective view showing the structure of a conventional vertical-torsional ultrasonic motor, in which a vertical-torsional composite vibrator 103 including a piezoelectric torsional composite vibrator 101 and a piezoelectric longitudinal vibrator 102 is shown. A rotor 105 is rotatably supported at an end by a bearing 104.
are pressed into contact with each other by a spring 106.

FIG. 7 is a perspective view showing the structure of a piezoelectric torsion composite vibrator 101 used in the conventional vertical-torsion type ultrasonic motor shown in FIG. In FIG. 7, four fan-shaped piezoelectric ceramic plates 107 polarized in the direction of the first chord are arranged in a disk or ring shape, as shown by the white arrows, with their end faces aligned so that the direction of polarization is closed. are joined together.

FIGS. 8(a) and 8(b) are explanatory diagrams of the operating principle of the vertical-torsion type ultrasonic motor of FIG. 6.

8(a) and (b) show the torsional vibration displacement ξ at the position along each axis of the longitudinal-torsional compound vibrator, the longitudinal expansion/contraction displacement ξ', and the rotational direction of the rotor 5. . Since the direction of each displacement is shown in FIG. 8, detailed explanation will be omitted.

If the rotation direction indicated by the arrow 108 in FIG. 6 is the forward direction, as shown by the solid line 109 in FIG. 8(a), in the forward direction, the torsional displacement ( As the size of ξ) gradually increases, both ends exhibit torsional displacement in opposite directions. On the other hand, Fig. 8 (
Similarly, in the case of the reverse direction shown by the broken line 110 in a), the torsional displacement (ξ) increases as the center moves from the center to both ends.

It becomes symmetrical with the forward direction.

Furthermore, the expansion/contraction displacement (ξ′) in the direction of arrow 111 shown in FIG.
), as shown by the solid line 112 in FIG. 8(b), expands at one end and contracts at the other end, and its size is maximum at both ends. Conversely, as shown by the broken line 113 in FIG. 8(b), when one end contracts and the other end extends, the displacement (ξ'
) is the size of .

Maximum at both ends.

(Problem to be Solved by the Invention) As shown in FIG. 6, in the conventional rotation conversion mechanism, one end of the rotor 105 is connected to the shaft 114 and the bearing 104
Since the structure is such that the rotor pressure is applied by the spring 106, the state of contact between the rotor surface and the end face of the vibrator is not uniform, causing the rotation to slow down or speed up. Therefore, the technical problem of the present invention is to eliminate one or more of the defects,
The object of the present invention is to provide an ultrasonic motor that is small in size and has relatively large torque.

(Means for Solving the Problems) According to the present invention, there is provided a piezoelectric longitudinal-torsional vibrator which is a piezoelectric ceramic hollow cylinder having a central axis and whose at least one end portion vibrates longitudinally and torsionally; A support member provided at a vibration node portion of the vibrator, and a wear-resistant member layer provided at an end portion of the piezoelectric ceramic hollow cylinder that undergoes longitudinal-torsional vibration.

In an ultrasonic motor comprising a ring-shaped rotor that is rotatably provided around the central axis and has one end surface pressed against the wear-resistant member layer, the fixing member has a protrusion that is inserted into the inner diameter of the rotor. a plate, an elastic body interposed between the fixed plate and the other end face of the rotor opposite to the one end face, and a spring that presses the fixed plate against the other end face of the rotor in the direction of the central axis via the elastic body. An ultrasonic motor characterized by having a member is obtained.

According to the invention, in the ultrasonic motor.

In the piezoelectric longitudinal-torsional vibrator, a first interdigital electrode is provided on a part of the circumferential surface of the piezoelectric ceramic hollow cylinder in one of the circumferential direction and the longitudinal direction.

A vertical vibrator formed by polarization using the first interdigital electrode, and a second intersecting element formed on the remaining part of the outer peripheral surface of the piezoelectric ceramic hollow cylinder in a direction inclined with respect to the central axis direction. An ultrasonic motor characterized in that it has finger electrodes and a torsional vibrator formed by polarization using the second interdigital electrodes.

According to the present invention, there is obtained an ultrasonic motor as described above, wherein the support member is provided at one end of the piezoelectric longitudinal-torsional vibrator.

(Function) In the ultrasonic motor of the present invention, the protrusion of the fixed plate is inserted into the inner diameter surface of the rotor, and an elastic body is interposed.
By pressing this fixing plate against the rotor in the axial direction with a spring, it is brought into uniform contact with the wear-resistant material layer, and the vertical-torsional vibration of the end face of the piezoelectric wire-torsion vibrator is uniformly rotated by the rotor. converted to rotation.

(Example) Below, an ultrasonic motor of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a half-sectional view taken in the axial direction, showing an example of the construction of a vertical-torsion type ultrasonic motor according to the present invention.

In FIG. 1, the end of the torsional vibrator of the longitudinal-torsional composite vibrator 10 is fixed with a support 13 including a first bearing 12 so that torsional vibration can be excited at 174 wavelengths, and the piezoelectric longitudinal vibrator 10 A wear-resistant member layer 14 is formed on the end face of the rotor, and a ring-shaped rotor 15 and an elastic body 16 are sandwiched therebetween.The protrusion 17a of the rotor fixing plate 17 is fitted into the inner diameter 15a of the rotor and is pressed by a leaf spring 18. ing. Therefore, during operation, the shaft 20 passing through the first bearing 12 and the second bearing 19 and the rotor 15 rotate together.

FIG. 2 is a perspective view showing an example of the structure of the longitudinal-torsion composite vibrator 10 used in the ultrasonic motor shown in FIG. In FIG. 2, a first interdigital electrode 31 is arranged perpendicular to the length direction, that is, parallel to the nine circumferential direction, around one end of the outer peripheral surface of the piezoelectric ceramic hollow cylinder 11 formed by press molding.
a and 31b are formed. The electrodes 31a are connected by connecting electrodes (not shown) provided in the length direction, while the electrodes 31b and the connecting electrodes 31b are connected by connecting electrodes 32. These electrodes 31a, 31b.

and 32 are formed by printing a paste containing a conductive material.

When a polarization process is performed using these interdigitated electrodes 31a, 31b, and 32, the polarization direction becomes a direction perpendicular to the length direction of the first interdigitated electrodes. In this state, the first interdigital electrode 3
When an alternating current voltage is applied to 1a, 31b, and 31c, if the polarity of the voltage is the same as the polarity of the voltage during polarization, an elongation strain occurs in the direction of polarization.

If the polarity of the voltage is opposite to the polarity during polarization, shrinkage distortion occurs in the direction of polarization. As a result, the piezoelectric ceramic hollow cylinder 11 expands and contracts in the length direction. Further, a second interdigital electrode 33a is provided on the outer peripheral surface of the other portion of the piezoelectric ceramic hollow cylinder 11 where the first interdigital electrode is provided, and is inclined at 45 degrees with respect to the length direction.

33b is formed. These electrodes 33a.

33b and 32 are formed by printing a paste containing a conductive material onto the piezoelectric ceramic hollow cylinder 11.

Each of the second interdigital electrodes 33a, 33b is a common electrode 33c provided along the circumferential direction.

33-d. In addition, the common electrode 33c
is the same as the lowermost portion of the first interdigital electrode 31a. These electrodes 33g, 33b.

33c and 33d are formed by printing a paste containing a conductive material onto the piezoelectric ceramic hollow cylinder 11.

When polarization processing is performed using the second interdigital electrodes 33m and 33b, the polarization direction is changed from that of the second interdigital electrodes 33a and 33.
The direction is perpendicular to the length direction of b.

When an AC voltage is applied to the second interdigital electrodes 33a and 33b in this state, if the polarity of the voltage is the same as the polarization direction, an elongation strain occurs in the polarization direction.

When the polarity of the voltage is opposite to the direction of polarization, shrinkage distortion occurs in the direction of polarization. When an elongation or contraction strain occurs in the polarization direction, a contraction strain or an expansion strain occurs in the direction perpendicular to the polarization direction.

As a result of the above, torsional displacement occurs in the piezoelectric ceramic hollow cylinder 11.

Note that the first interdigital electrode 31a shown in FIG.

Interdigital electrodes 51a are provided along the length direction shown in FIG. 3(a) instead of 31b.

51b, and every other common electrode 52a.

52b and subjected to polarization using the interdigital electrodes 51a and 52a, as shown in FIG. 3(b). The same effect as the longitudinal-torsional vibrator shown in FIG. 2 can be obtained by constructing either one of the longitudinal vibrators having electrodes on the entire outer surface.

FIG. 4 is a perspective view showing another structural example of the vertical-torsion type ultrasonic motor of the present invention. In fig.

A central vibration node of the vertical-torsional composite vibrator 10' is fixed with a support ring 21, and wear-resistant material layers 22 and 22' are formed on both end surfaces of the piezoelectric wire-torsional vibrator composite vibrator 10'. ,
Ring-shaped rotors 23, 23' and elastic bodies 24, 24'
and a rotor fixing plate 25.25' having a protrusion that can be fitted into the inner diameter of the rotor, and a leaf spring 26.26'.
Press it with.

The piezoelectric wire-torsion composite vibrator, a shaft 27 passing through both the rotors 23 and 23' provided at both ends of the vibrator, and these rotors 23 and 23' rotate together.

In these cases, the state of contact between the rotor surface and the vibrator end surface is constantly and almost uniform because there is a degree of freedom between the vibrating end surface and the rotor surface.

FIG. 5 is a perspective view showing an example of the structure of a vertical-torsion composite vibrator 10' used in the ultrasonic motor of FIG. 4. In FIG. 4, a first pair of interdigital electrodes 31a are arranged parallel to or perpendicular to the length direction around both ends of the outer peripheral surface of the piezoelectric ceramic hollow cylinder 1' formed by press molding technology.
31b, 31a', and 31b' are each formed by printing.

Similar to FIG. 2, the interdigital electrodes 31a and 31b are connected by connecting electrodes 32 provided in the longitudinal direction, and the interdigital electrodes 31a' and 31b' are also connected in the same manner.

They are connected by connection electrodes 32' provided in the length direction.

This first pair of interdigital electrodes 31a, 31b and 31a'
, 31b', the polarization direction is the same as that of the first interdigital electrodes 31a, 31b and 31a', 31.
The direction is perpendicular to the length direction of b'. In this state, the first interdigital electrode pair 31a.

When an AC voltage is applied to 31b, 31a', and 31b', if the polarity of the voltage is the same as the polarity of the voltage at the time of polarization, stretching strain will occur in the direction of polarization, and if the polarity of the voltage is opposite to the polarity at the time of polarization. Shrinkage distortion occurs in the direction of polarization. As a result, the piezoelectric ceramic hollow cylinder 11' expands and contracts in the length direction. Further, second interdigital electrodes 33g and 33b are formed at a portion between the first interdigital electrode pair 31a, 31b and 31a, 31b of the piezoelectric ceramic hollow cylinder 11-, and are inclined at 45 degrees with respect to the length direction. ing.

Second interdigital electrode 33a as in FIG.

Each of the common electrodes 33b is provided along the circumferential direction.
C, 33C', one of the second interdigital electrodes 33a
One end side is a common electrode 33C1, the other side of the second interdigital electrode 3
3b is a common electrode 33C with the other end opposite to the one end.
′.

Note that the common electrodes 33c, 33c' are the same as the central portion of the first interdigital electrodes 31a, 31a'. When polarization processing is performed using the second interdigital electrodes 33g and 33b, the polarization direction becomes a direction perpendicular to the length direction of the second interdigital electrodes 33a and 33b.

When an AC voltage is applied between the second interdigital electrodes 33a and 33b in this state, if the polarity of the voltage is the same as the polarization direction, an elongation strain occurs in the polarization direction.

When the polarity of the voltage is opposite to the direction of polarization, shrinkage distortion occurs in the direction of polarization. When an elongation or contraction strain occurs in the polarization direction, a contraction strain or an expansion strain occurs in the direction perpendicular to the polarization direction.

As a result of the above, torsional displacement occurs in the piezoelectric ceramic hollow cylinder 11'.

Note that this is similar to the piezoelectric wire-torsion vibrator shown in FIG.

The first interdigital electrode 31a shown in FIG.

31b, 31a', and 31b' in FIG. 3(a).

A similar effect can be obtained by using the vertical vibrator shown in (b).

(Effects of the Invention) As explained above, in the ultrasonic motor of the present invention, the shape of the piezoelectric vibrator for generating driving force is simple;
A piezoelectric torsion oscillator is created by using a piezoelectric ceramic hollow cylinder, which can be easily manufactured using a commonly used press molding technique, and by applying electrode printing, which is also a common technique, to the outer peripheral surface of the cylinder. Since a piezoelectric longitudinal vibrator can be obtained, an ultrasonic motor that is easy to manufacture and has less variation in characteristics due to bonding processes and complicated processing processes can be obtained. Furthermore, in the ultrasonic motor of the present invention.

Since the rotor surface and the end surface of the vibrator have a degree of freedom in surface contact, it is possible to obtain a small ultrasonic motor with very little load fluctuation and very little rotational unevenness, and a relatively large torque.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing an example of the structure of the vertical-torsional ultrasonic motor of the present invention, and FIG. 2 shows the structure of a piezoelectric longitudinal-torsional composite vibrator used in the ultrasonic motor of FIG. 1. Figure, 3rd
Figures (a) and (b) are perspective views showing structural examples of another type of longitudinal vibrator used in the ultrasonic motor of the present invention, and Fig. 4 is a perspective view of another type of longitudinal vibrator used in the ultrasonic motor of the present invention. FIG. 5 is a partial sectional view showing a structural example, and FIG. 5 is a perspective view showing a structural example of a piezoelectric longitudinal-torsional composite vibrator used in the ultrasonic motor shown in FIG. 4. FIG. 7 is a perspective view showing an example of the structure of the piezoelectric torsional compound vibrator used in the ultrasonic motor of FIG. 6, and FIGS. 8(a) and (b) are vertical-torsional type ultrasonic FIG. 2 is an explanatory diagram of the operating principle of a sonic motor. In the figure, 12.19 is a bearing, 18, 25° 25' is a spring, 10.10' is a longitudinal-torsional compound vibrator, and 11.11'
is a piezoelectric ceramic hollow cylinder. 13 is a support, 14, 22.22' is a wear-resistant member layer,
15.23.23' is the rotor, 16, 24°24' is the elastic body, 17, 25.25' is the rotor fixing plate, 20.
27 is a shaft, 21 is a support ring. 31.31b, 31a' and 31b' are first interdigital electrodes, and 33a and 33b are second interdigital electrodes. 32.32' are connection electrodes + 33 c, 33 c'
. 33d is a common electrode, and 101 is a piezoelectric torsional composite vibrator. 102 is a piezoelectric longitudinal vibrator, 103 is a longitudinal-torsion composite vibrator,
104 is a bearing, 105 is a rotor, 1o6 is a spring, 10
7 is a piezoelectric ceramic plate, and 114 is a shaft. Figure 2 Figure 3 (a) (b) Figure 4 Figure 5 Figure 6 Figure 7

Claims (3)

[Claims] 1. A piezoelectric vertical-torsional vibrator which is a piezoelectric ceramic hollow cylinder having a central axis and whose at least one end portion undergoes vertical-torsional vibration; and a support member provided at a vibration node of the piezoelectric vertical-torsional vibrator. , a wear-resistant material layer provided at the end of the piezoelectric ceramic hollow cylinder that vibrates vertically and torsionally; and a ring-shaped ring-shaped member rotatably provided around the central axis and having one end surface pressed against the wear-resistant material layer. An ultrasonic motor comprising: a fixed plate having a protrusion inserted into an inner diameter of the rotor; and an elastic body interposed between the fixed plate and the other end surface of the rotor opposite to the one end surface. and a spring member that presses the fixed plate against the other end surface of the rotor in the direction of the central axis via the elastic body. 2. The ultrasonic motor according to claim 1, wherein the piezoelectric longitudinal-torsional vibrator has a first intersection on a part of the circumferential surface of the piezoelectric ceramic hollow cylinder in either the circumferential direction or the longitudinal direction. A longitudinal vibrator formed by applying finger electrodes and polarizing using the first interdigital electrode, and a direction inclined with respect to the central axis direction on the remaining part of the outer peripheral surface of the piezoelectric ceramic hollow cylinder. 1. An ultrasonic motor comprising: a second interdigital electrode; and a torsional vibrator formed by polarization using the second interdigital electrode. 3. The ultrasonic motor according to claim 1 or 2, wherein the support member is provided at one end of the piezoelectric longitudinal-torsional vibrator.