JP3055414B2 - Ultrasonic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator such as an ultrasonic motor utilizing a combined vibration of a piezoelectric element, and more particularly to a structure for holding a vibrator.

[0002]

2. Description of the Related Art FIG. 4 is an exploded perspective view schematically showing the structure of a conventional ultrasonic actuator, FIG. 5 is a plan view showing the structure of a vibrator and a movable rail, and FIG. It is a top view for explanation. In these figures, reference numeral 20 denotes a ring-shaped vibrator made of piezoelectric ceramics which is uniformly polarized in the thickness direction along the entire circumference, has a central hole 20a, and has two pairs of fan-shaped front and back surfaces. Are formed, and another two pairs of electrodes 21c are formed between the electrodes 21a and 21b. 22 is a vibrator 20 corresponding to the electrode 21c
Is a transmission member having a rectangular cross section fixed so as to face the peripheral surface thereof, and is formed of an engineering plastic which is easy to process, has excellent wear resistance, and can obtain a predetermined friction transmission force.

Reference numeral 40 denotes a pair of opposing movable rails which are in contact with the transmission member 22 with a small pressing force, and are supported by a guide mechanism (not shown) so as to be movable in the AB direction. Reference numeral 19 denotes a pair of ring-shaped mats provided with a central hole 19a formed of an elastic member. Reference numeral 35 denotes a base plate in which a screw hole 35a is screwed, and 36 denotes a flange having an outer diameter smaller than the inner diameter of the central holes 20a and 19a, and a flange 36a is formed. A collar member 37, which is slightly smaller than the total thickness of 19 and the vibrator 20, is a screw.

In such a configuration, the lower mat 1
9, the vibrator 20 and the upper mat 19 are sequentially placed on the base 3
5, the collar member 36 is inserted into the central holes 19a and 20a, the screw 37 is inserted into the collar member 36, and screwed into the screw hole 35a. , And between the base 35 and the flange portion 36 a via the mat 19.
At this time, since the height of the collar member 36 up to the flange portion 36a is slightly smaller than the total thickness of the mats 19 and the vibrator 20, the vibrator 20 is elastically deformed by the mats 19. Therefore, the movement in the thickness direction is restricted by the weak pressing force. The electrodes 21a and 21b are connected by high-frequency power supplies 41 and 42, and a high-frequency voltage sin different in time phase difference Φ = 90 ° or −90 ° from each other.
ωt and conωt are applied.

Next, the operation of the ultrasonic actuator having such a configuration will be described. High frequency powers sinωt, co with a phase difference Φ = 90 ° by high frequency power supplies 41, 42
When nωt is applied to each of the electrodes 21 a and 21 b of the vibrator 20, the vibrator 20 expands and contracts, and when the inner diameter / outer diameter has a certain value (0.27), the radial vibration (R, 1) occurs in the radial direction.
And the multi-mode vibration of the non-axisymmetric in-plane vibration (1, 1) occurs simultaneously. As shown in FIG. 6A, the radial vibration
The non-axially symmetric in-plane vibration is a mode that expands and contracts in the radial direction, while the non-axisymmetric in-plane vibration is an in-plane bending vibration mode that expands and contracts along the vertical vibration axis OO in the figure as shown in FIG. When the mode is given to the vibrator 20, the vibrations of both modes are combined, and the electrode 21c, that is, the opposing peripheral surface of the vibrator 20 corresponding to the transmission member 22, is arranged as shown in FIG. , An elliptical motion rotating in opposite directions occurs.
This elliptical operation is performed by the two movable rails 4 via the transmission member 22.
0, 40, and can be taken out as a straight-ahead operation of moving both movable rails 40, 40 in the direction B in the figure. The electrode 21c is a monitoring electrode for correcting a change due to the temperature characteristic of the vibrator 20, and takes out a voltage generated by the vibration from the electrode 21c.
The correction is performed by changing the voltage or frequency supplied from the electrodes 21a and 21b.

[0006]

However, in the conventional ultrasonic actuator described above, the oscillator 20
Is regulated by the entire mat 19 in the thickness direction. Since the vibrator is pressed by the surface contact of the entire mat 19, the vibration of the vibrator 20 is suppressed. Therefore, there is a problem that the movable rail 40 cannot be moved smoothly and sufficiently. .

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an ultrasonic actuator capable of performing a smooth and sufficient operation.

[0008]

To achieve this object, an ultrasonic actuator according to the present invention comprises a ring-shaped vibrator having a central hole, a base plate on which the vibrator is mounted, and A pair of ring-shaped elastic members having a central hole disposed so as to sandwich the thickness direction of the vibrator, and a pair of elastic members attached to the base plate through the vibrator and the central hole of the elastic member. The base plate and a collar member having a flange portion sandwiched therebetween, and supplying a two-phase high-frequency voltage to the vibrator to generate a multi-mode vibration by combining radial vibration and non-axially symmetric in-plane vibration; In the ultrasonic actuator for displacing a member to be actuated in contact with the peripheral surface of the vibrator, the ultrasonic member is protruded from the flange portion of the collar member and the base plate so as to face each other, and presses the elastic member. Providing a projection.

[0009]

According to the present invention, the entire vibrator is not pressed into contact with each other, and the vibration of the vibrator is not suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a main part of an ultrasonic actuator according to the present invention. In the figure, the same components as those of the related art are denoted by the same reference numerals, and detailed description is omitted. In the same figure, reference numeral 35 denotes a base having a polygonal cross section formed of ABS resin, and a screw hole 35a is screwed in the center,
Four pins 35b are integrally provided therearound. 36
Is a collar member formed of polycarbonate resin, and four pins 36b are integrally provided on the lower surface of the flange portion 36a at positions corresponding to the pins 35b. From the height up to the lower surface of the flange portion 36b of the collar member 36, the pin 3
The length obtained by reducing the height of 5b and 36b is formed to be slightly smaller than the length obtained by adding the thickness of the vibrator 20 to the thickness of the pair of mats 19.

In such a configuration, the lower mat 19 is placed on the pin 35b of the base 35, and the vibrator 20 and the upper mat 19 are placed thereon. 19a and 20a, the screw 37 is inserted through the collar member, and the screw hole 35a is inserted.
, Four pairs of pins 35b, 36b from above and below are pressed against the pair of mats 19, 19 sandwiching the vibrator 20 from the front and back by point contact. For this reason, the mats 19, 19, which are elastic members,
The portions pressed by b and 36b are elastically deformed, and the vibrator 20 is held by the elastically deformed portions by point contact. Although not shown, a pair of opposed movable rails 40, 40 are in contact with the transmission member 22 by a weak pressing force as in the above-described related art.

Next, the operation in such a configuration will be described. Similarly to the above-described prior art, the high frequency power supplies sinωt and conωt having the phase difference Φ = 90 ° by the high frequency power supply.
Is applied to each of the electrodes 21a and 21b of the vibrator 20, a multi-mode vibration of a radial vibration (R, 1) and a non-axially symmetric in-plane vibration (1, 1) simultaneously occurs in the vibrator 20, and both these modes occur. Are combined, and an elliptical motion that rotates in opposite directions to each other is generated on the opposing peripheral surfaces of the vibrator 20 corresponding to the transmission member 22. By this elliptical operation, both movable rails 40, 40 (not shown) move.

At this time, four pairs of pins 36b, 35b are pressed from above and below by a point contact with the pair of mats 19, 19 which sandwich the vibrator 20 from the front and back, and the mats 19, which are elastic members, are pressed. In 19, the portion pressed by the pins 36b and 35b is elastically deformed, and the vibrator 20 is held between the elastically deformed portions. Therefore, the vibrator 20 is also held between the mats 19 and 19 by point contact. For this reason, compared with the conventional case where it is pinched by surface contact,
Without suppressing the vibration of the entire vibrator 20, the vibrator 20
The movable rail 4
0 (not shown) and a sufficient amount of movement can be obtained, the number of parts can be significantly reduced, the configuration is simplified, and assembly is facilitated.

FIG. 2 is an exploded perspective view of a main part showing a second embodiment of the present invention. In the second embodiment, instead of the pin 35b and the pin 36b provided in the above-described first embodiment, a pair of mats 19 are integrally provided with projections 19b. That is, a projection 19b projecting upward is provided on the surface of the lower mat 19, and a projection 19b projecting downward is provided on the back surface of the upper mat 19.

With such a configuration, the vibrator 20 is pinched by the point contact of the projections 19b of the mat 19, so that the vibrator 20 has the same operation and effect as the above-described first embodiment, and Since the vibrator 20 is directly pressed by point contact by the 19 projections 19b, reliable point contact is obtained, and smooth movement of the movable rail and a sufficient amount of movement are more reliably obtained.

FIG. 3 is an exploded perspective view of a main part showing a third embodiment of the present invention. The third embodiment differs from the second embodiment in that the direction of the protrusion 19b in the second embodiment is reversed. That is, a projection 19b projecting downward is provided on the back surface of the lower mat 19, and a projection 19b projecting upward is provided on the surface of the upper mat 19, respectively. Even in such a configuration, each protrusion 19
b is a flange portion 3 of the base 35 and the collar member 36.
The vibrator 20 is pinched by the mat 19 by point contact as the mat is elastically deformed by being pressed by 6a.

In the above-described embodiment, an example of the linear type ultrasonic actuator using the movable rail 40 which moves linearly has been described. However, the present invention is not limited to this. It is needless to say that the rotor can be applied to an ultrasonic motor that outputs the rotation of the rotor.

[0018]

As described above, according to the present invention, a ring-shaped vibrator having a central hole, a base plate on which the vibrator is mounted, and a vibrator are arranged so as to sandwich the vibrator in the thickness direction. A pair of ring-shaped elastic members having a central hole, and a flange portion penetrating through the central holes of the vibrator and the elastic member, attached to the base plate, and sandwiching the pair of elastic members with the base plate. A two-phase high-frequency voltage is supplied to the vibrator to generate multi-mode vibration by combining radial vibration and non-axially symmetric in-plane vibration, and the actuated member comes into contact with the vibrator peripheral surface. An ultrasonic actuator for displacing a member, wherein a projection is provided on a flange portion and a base plate of the collar member so as to face each other and presses the elastic member. In as compared to the case which is held,
Since the vibration of the vibrator is not disturbed without suppressing the vibration of the whole vibrator, smooth displacement and sufficient displacement of the operated member can be obtained, and the number of parts can be significantly reduced. The structure is simplified, and the assembly is facilitated.

Further, according to the present invention, a ring-shaped vibrator having a central hole, a base plate on which the vibrator is mounted, and
A pair of ring-shaped elastic members having a central hole disposed so as to sandwich the vibrator in the thickness direction; and a pair of elastic members attached to the base plate through the central holes of the vibrator and the elastic member. A collar member having a flange portion for holding the member with the base, supplying a two-phase high-frequency voltage to the vibrator to generate multi-mode vibration by combining radial vibration and non-axially symmetric in-plane vibration; An ultrasonic actuator for displacing an actuated member abutting on the peripheral surface of the vibrator, wherein a projection is provided in a position corresponding to each of the pair of elastic members in a thickness direction of the elastic member, thereby providing a conventional actuator. As compared with the case where the vibrator is sandwiched by surface contact as described above, the vibration generated in the vibrator is not hindered without suppressing the vibration of the entire vibrator. With position amount is obtained, because the presses directly vibrator in point contact by the projection of the elastic member, reliable point contact is obtained, smooth displacement and sufficient displacement of the actuating member can be obtained more reliably.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of a first embodiment of an ultrasonic actuator according to the present invention.

FIG. 2 is an exploded perspective view of a main part of a second embodiment of the ultrasonic actuator according to the present invention.

FIG. 3 is an exploded perspective view of a main part of a third embodiment of the ultrasonic actuator according to the present invention.

FIG. 4 is an exploded perspective view of a main part of a conventional ultrasonic actuator.

FIG. 5 is a plan view of a main part of a conventional ultrasonic actuator.

6A and 6B are diagrams illustrating the principle of a general ultrasonic actuator. FIG. 6A illustrates radial vibration, FIG. 6B illustrates non-axisymmetric in-plane vibration, and FIG. 6C illustrates vibration obtained by combining both vibrations. It shows.

[Explanation of symbols]

19 ... mat, 19b, 35b, 36b ... pin, 20 ...
Vibrator, 36 ... Color member.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02N 2/00-2/18

Claims (2)

(57) [Claims] 1. A ring-shaped vibrator having a central hole, a base plate on which the vibrator is mounted, and a pair of ring-shaped elastic members having a central hole disposed so as to sandwich the vibrator in the thickness direction. And a collar member having a flange portion that is attached to the base plate through a center hole of the vibrator and the elastic member, and has a flange portion that sandwiches the pair of elastic members with the base plate. An ultrasonic actuator that supplies a two-phase high-frequency voltage to generate a multi-mode vibration by combining radial vibration and non-axially symmetric in-plane vibration, and displaces an actuated member that abuts on the peripheral surface of the vibrator. An ultrasonic actuator, wherein a projection is provided on a flange portion of a member and a base plate so as to be opposed to each other and presses the elastic member. 2. A ring-shaped vibrator having a central hole, a base plate on which the vibrator is mounted, and a pair of ring-shaped elastic members having a central hole disposed so as to sandwich the vibrator in the thickness direction. And a collar member having a flange portion which is attached to the base plate through a central hole of the vibrator and the elastic member and has a flange portion for holding the pair of elastic members with the base. An ultrasonic actuator that supplies a high-frequency voltage of a phase to generate a multi-mode vibration by combining radial vibration and non-axisymmetric in-plane vibration, and displaces an actuated member that abuts on the vibrator peripheral surface. An ultrasonic actuator, wherein projections are provided at positions corresponding to each other on an elastic member in a thickness direction of the elastic member.