JPH06106033B2 - Ultrasonic motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor, and more particularly, to an elastic disk member integrally provided with a piezoelectric element, which has a disk bending mode and a circumferential sway mode. The present invention relates to an ultrasonic motor that generates ultrasonic vibration and extracts a driving force.

[Prior Art] Conventionally, there is an ultrasonic motor of this type that is proposed by the present inventor (Japanese Patent Application No. 61-53664).
This will be described with reference to FIGS. In the figure, a rectangular thickness-mode piezoelectric element (11) and a thickness-thin mode piezoelectric element (12) are integrally coupled with each other with an insulating plate (13) interposed therebetween to form a piezoelectric unit (U). An adapter (14) is fixed to the lower surface of the piezoelectric unit (U), and a mass body (16) is fixed to the upper surface. A rail-shaped relative moving body (15) is in pressure contact with the lower surface of the adapter (14). This pressure contact force is applied to slide members (17) such as ball bearings.
Through the frame member (18). The mass body (16) maintains the balance of movement. The frame member (18)
It is integrated with the mass body (16) and functions as a protrusion preventing guide and with a proper spring property to press the adapter (14) and the relative moving body (15) into pressure contact with each other.

With the above configuration, the piezoelectric unit (U) and the adapter (1
4) The mass body (16) is integrated with each other, and when a high frequency sine wave voltage is applied to the piezoelectric unit (U), the adapter (14) reciprocally vibrates. At this time, the adapter (14) linearly moves relative to each other as if kicking the relative moving body (15). The direction of movement is determined by the polarization of the piezoelectric element and the polarity of the input voltage.

[Problems to be Solved by the Invention]

In the conventional ultrasonic motor as described above, it is difficult to reduce the thickness and it is difficult to reduce the weight.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to obtain an ultrasonic motor that can achieve a reduction in size and weight by sharing a vibration member.

[Means for Solving the Problems]

The ultrasonic motor according to the present invention includes a disc-shaped piezoelectric element that causes a disc bending mode on the outer peripheral edges of both sides and one side of a single disc-shaped member, and a ring-shaped piezoelectric element that causes a thickness stagnation mode in the circumferential direction. A piezoelectric element is attached, and a relative moving body such as a rotor is pressed against an adapter fixed to an annular piezoelectric element.

[Action]

One of the piezoelectric elements attached to both sides of the disk-shaped member has an electrode divided into two parts by an annular groove, and the electrodes of the disk-shaped member are arranged in parallel with the outer peripheral electrode and the piezoelectric element on the other side. When oscillating and vibrating at the frequency of the secondary disk bending mode, a voltage of the same frequency is generated at the electrode on the circular side. This voltage is applied to the stagnation mode piezoelectric element and causes the relative motion body to rotate through the adapter.

〔Example〕

1 and 2 show an embodiment of the present invention. In FIG. 1, a disk-shaped piezoelectric element (3) in which an electrode is divided into two on one outer surface of a disk (1) which is an elastic metal plate. ) Is attached. A disk-shaped piezoelectric element (2) is formed at the center of the inner surface of the disk (1), and a ring-shaped piezoelectric element (4a) (4a) is generated at the outer peripheral edge of the disk (1) to generate a vibration in a wandering mode in the circumferential direction. 4b) and an annular adapter (6) are attached and connected. An insulating plate (5) is inserted between the piezoelectric elements (4a) and (4b). The adapter (6) has a rotor (7) which is a relative moving body.
Is pressed. Through hole (8) in the center of disc (1)
Are formed.

The stagnation mode piezoelectric elements (4a) and (4b) have the roles of clockwise rotation and counterclockwise rotation, respectively, with their polarization directions reversed. As shown in FIG. 2, the piezoelectric element (3) has an electrode divided into an annular shape (3a) and a disk shape (3b) by an annular groove (9). ) Is also included in the same phase. Piezoelectric elements (3), (4a), (4
b) Resonant frequencies are set close to each other.

Next, the operation will be described. The self-excited oscillation power supply oscillates and vibrates in parallel with the electrode (3a) of the piezoelectric element (3) and the piezoelectric element (2) at the frequency of the secondary disk bending mode of the disk (1). Then, a voltage having the same frequency is generated at the electrode (3b). When this voltage is connected and input to the piezoelectric element (4a), the rotor (7) rotates, for example, right. When the above voltage is input to the piezoelectric element (4b), the rotor (7) rotates counterclockwise. That is, the rotation direction of the rotor (7) is switched by changing the voltage generated in the electrode (3b) to the piezoelectric element (4a),
It will be determined depending on which one of (4b) is switched and applied.

In the above operation, since the phases of the piezoelectric elements (4a) and (4b) are delayed (about 20 °) from the phase of the disk (1), an ideal operation state can be obtained and the switching operation can be performed by the drive circuit. Very good results have been obtained in that it can be easily done without adverse effects.

The adapter (6) is an adapter material, and at the same time, serves as a Langevin vibrator at the time of wandering mode vibration. The contact surfaces of the rotor (7) and the adapter (6) do not generate abnormal noise such as squeaking noise during operation, and their materials are selected by a combination of materials with less wear. That is, for the disc (1) and the adapter (6), nickel steel or the like having a thermal expansion coefficient similar to that of the piezoelectric element is suitable, and the rotor (7) or the contact surface material to the rotor (7) side is the above-mentioned material. A material satisfying the above characteristics, for example, a phenol-based or polyimide-based resin mixed with copper powder is suitable.

The rotor (7) is an axial bearing provided on the case side (not shown), and is assembled so that the rotor can be positioned and a pressure contact bias can be applied. By fixing the disc (1) at the node line, that is, at the portion of the annular groove (9), the loss during vibration can be minimized.

In addition to the above, the driving method is (3a + 2) + 4a ... clockwise rotation, (3a + 2) + 4b ... counterclockwise rotation.

It does not matter even if it is a parallel connection operation. In this case, the switch switching circuit becomes a little more complicated than in the above case.

FIG. 3 shows a modification of the stagnation mode piezoelectric element, in which a single annular piezoelectric element (4) is divided into four sections, and the piezoelectric element (4
The role of a) is performed in parallel with (4c) and (4d), and the piezoelectric element (4
The role of b) is performed in parallel with (4e) and (4f), and the same action and effect can be obtained.

Further, in order to further reduce the thickness of the motor, the resonance frequency of the stagnation mode becomes high, but the disc bending mode of the disc (1) also shifts to the higher-order mode accordingly, and becomes the stagnation resonance mode. You can find a concordant point for.

The through hole (8) of the disc (1) is not always necessary.

Further, in order to reduce the overall finished weight of the motor, it is conceivable that the disc (1) is formed of an elastic member made of a light ceramic material (specific gravity ≈3) such as carbon glass.

[Effects of the Invention] As is apparent from the above description, the present invention causes two vibration modes of a disc bending mode and a thickness swaying mode to occur simultaneously, and rotates a relative moving body in any left-right direction via an adapter. Since it is driven, it is possible to achieve thinning and weight reduction, and in addition, there are effects such as a simple structure and easy left / right switching.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view of an embodiment of the present invention, and FIG.
FIG. 3 is a partial plan view of the drawing, FIG. 3 is a partial plan view of another embodiment, FIG. 4 is a front sectional view of a conventional ultrasonic motor, and FIG. 5 is a side view of FIG. (1) ... Disk-shaped elastic member, (2) (3) ... Plate-shaped piezoelectric element, (4a) (4b) ... Ring-shaped piezoelectric element, (6) ... Adapter, (7) ... Relative moving body .

Claims (1)

[Claims] 1. A disk-shaped elastic member, a plate-shaped piezoelectric element that is attached to both surfaces of the elastic member and causes vibration in a disk bending mode, and an outer peripheral edge of one surface of the elastic member. An ultrasonic motor comprising: a ring-shaped piezoelectric element that causes thickness-thickness mode vibrations in the circumferential direction; and an adapter that is fixed to the ring-shaped piezoelectric element and is brought into pressure contact with a relative moving body.