JP2586045B2 - Vibration motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vibration motor that obtains a driving force by vibration generated in an elastic body. An ultrasonic motor is known as such a vibration motor.

(Prior Art) Conventionally, as this type of ultrasonic motor, for example,
No. 59-117473 are known.

In this ultrasonic motor, a stator composed of an elastic body and a piezoelectric body, and a rotor that is in pressure contact with the stator, and a driving circuit generates a traveling wave in the stator,
It is configured to drive the rotor that is brought into pressure contact.

Therefore, in order to reduce the frictional force generated between the holding member that rotatably supports the rotor, a thrust bearing structure in which a bearing is inserted between the rotor and the holding member is adopted.

(Problems to be Solved by the Invention) However, in such a conventional ultrasonic motor, since the rotor is rotatably supported on the holding member by the bearing, the rolling surface on which the bearing rolls is provided. If it is not machined with high accuracy, it will cause drive unevenness, and even if a bearing is used, some mechanical loss is inevitable, and the bearing structure of the rotor will be complicated by the use of the bearing. There was a problem.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and eliminates the need for a bearing structure for a rotor using bearings. An object is to provide a motor.

In order to achieve this object, in the present invention, the first
A relative movement member having a surface, a second surface different from the first surface, an elastic body having front and back surfaces, and an electromechanical transducer bonded to the back surface of the elastic body. A first vibrator in which the surface and the surface of the elastic body are in pressure contact with each other; an elastic body having front and back surfaces; and an electromechanical transducer bonded to the back surface of the elastic body. A second vibrator pressed against the surface, wherein a traveling wave is generated on the surface of the elastic body of the first vibrator, and a standing wave is generated on the surface of the elastic body of the second vibrator. It was done.

(Operation) In the vibration motor of the present invention having such a configuration, by generating a standing wave on one of the vibrators sandwiching the relative motion member, the relative motion member is connected to the vibrator. It is rotatably supported in a state where the frictional force generated between them is reduced. By generating a traveling wave in the other vibrator in this state, the relative motion member can be rotated.

In addition, since two oscillators are provided, one oscillator generates a standing wave and the other oscillator generates a traveling wave, and at the same time, generates an oscillator that generates a standing wave and a traveling wave. By switching, it is possible to easily reverse the relative motion member or switch the rotational speed to drive.

(Embodiment) FIG. 1 is a sectional view showing an embodiment of the structure of the vibration motor according to the present invention.

In FIG. 1, 1 is a case, 2 is a case 1 and a screw 1
A base plate fixed by 0 and 11, a compression coil spring, an elastic body 4 to which a piezoelectric body 5 as an electromechanical transducer is adhered in a case 1, and a relative motion member integrally provided with an output shaft 3a at the center. A rotor 3, an elastic body 6 to which a piezoelectric body 7 is bonded,
Buffer support member 8 that buffers vibration of elastic body 6 and piezoelectric body 7
And the output shaft 3a of the rotor 3 is fitted into a bearing 1a provided in the case 1. The compression coil spring 9 generates a spring force for pressing the elastic body 4 having the piezoelectric body 5 bonded thereto and the elastic body 6 having the piezoelectric body 7 bonded thereto against the rotor 3.

FIG. 2 shows a drive circuit for the piezoelectric bodies 5, 7, elastic bodies 4, 6 and the rotor shown in FIG.

The piezoelectric element 5 is composed of piezoelectric elements 5a and 5b, and the piezoelectric elements 5a and 5b are polarized at a half pitch of the wavelength λ of the vibration wave of the elastic body 4.

The piezoelectric body 5a is connected to one side of the AC power supply 12, and the piezoelectric element 5b is also connected to one side of the AC power supply 12 via the switch 15 and the 90 ° phase shifter 13.

Further, the other pole 5c of the piezoelectric element 5 is connected to the other side of the AC power supply 12.

When the switch 15 is closed in such a driving circuit of the piezoelectric body 5, the frequency signal of the AC power supply 12 is directly applied to the piezoelectric element 5a, and the 90 ° phase shifter 13 has a phase difference of + 90 ° or −90 °. Since the applied frequency signal is applied to the piezoelectric element 5b via the switch 15, a traveling wave is generated in the elastic body 4 by the piezoelectric body 5, and the rotor 3 is driven to rotate.

On the other hand, when the switch 15 is opened, the frequency signal of the AC power supply 12 is applied only to the piezoelectric element 5a, so that a standing wave is generated in the elastic body 4, and the generation of the standing wave causes the elastic body 4 and the rotor 3 to rotate. The rotor 3 is held in a state where the frictional force with the rotor 3 is reduced.

The piezoelectric body 7 and the elastic body 6 have the same structure as the piezoelectric body 5 and the elastic body 4, and the piezoelectric element 7a of the piezoelectric body 7
The piezoelectric element 7b is also connected to one of the AC power supplies 12 via a switch 16 and a 90 ° phase shifter 13,
Further, the other pole portion 7c of the piezoelectric body 7 is connected to the other side of the AC power supply via a resistor 14.

In such a drive circuit of the piezoelectric body 7, a switch
When the valve 16 is closed, a traveling wave is generated in the elastic body 6 by the piezoelectric body 7, and the rotor 3 is driven to rotate. On the other hand, when the switch 16 is opened, the frequency signal of the AC power supply is applied only to the piezoelectric element 7a, so that a standing wave is generated in the elastic body 6 and the frictional force between the elastic body 6 and the rotor 3 is reduced. Thus, the elastic body 6 holds the rotor 3.

Here, the piezoelectric body 5 and the piezoelectric body 7 are connected to the same AC power supply 12, but since the resistor 14 is connected to the piezoelectric body 7 side, the voltage applied to the piezoelectric body 5 and the voltage applied to the piezoelectric body 7 The applied voltage is different and the piezoelectric body 7 having the resistor 14
Side voltage decreases.

 Next, the operation of the embodiment shown in FIGS. 1 and 2 will be described.

Now, the switch 15 on the piezoelectric body 5 side is closed and the piezoelectric body 7 is closed.
If the switch 16 on the side is opened, the piezoelectric element of the piezoelectric body 5
The frequency signal having a phase difference of + 90 ° or -9 ° is applied to the piezoelectric element 5b by the 90 ° phase shifter 13 and the frequency signal is directly applied to the piezoelectric element 5b by the AC power supply 12 to the elastic body 4a.
Generates a traveling wave. When a traveling wave is generated in the elastic body 4 in this manner, one mass point of the elastic body 4 in contact with the rotor 3 performs an elliptic motion, whereby the rotor 3 rotates.

At this time, since the switch 16 is opened in the elastic body 6, a standing wave is generated by application of a frequency signal from the AC power supply 12 to only the piezoelectric element 7a of the piezoelectric body 7, and this standing wave is generated. Thus, a supporting state in which the frictional force between the elastic body 6 and the rotor 3 is reduced is created, and the rotor 3 is driven to rotate with low friction by the traveling wave generated in the elastic body 4.

On the other hand, the magnitude of the elliptical motion of one mass point in the elastic body when a traveling wave is generated in the elastic body by applying a voltage from the AC power supply 12 to the piezoelectric body changes in proportion to the applied voltage. As a result, the rotation speed of the rotor changes in proportion to the magnitude of the elliptical motion.

Therefore, in the driving circuit shown in FIG. 2, when the switch 15 is closed, a traveling wave is generated in the elastic body 4 by the piezoelectric body 5, and when the switch 16 is opened, a standing wave is generated in the elastic body 6 by the piezoelectric body 7. Conversely, when the switch 16 is closed and the switch 15 is opened to generate a standing wave in the elastic body 4 and a traveling wave in the elastic body 6, the rotational speed of the rotor 3 is Since the voltage at which the traveling wave is generated at 6 is reduced by the resistor 14, the rotation speed of the rotor 3 can be switched to a low speed.

That is, one rotor 3 can be driven at two different speeds only by switching the ON / OFF states of the switches 15 and 16.

Also, if the rotor 3 is connected to a drive circuit such that the traveling waves generated in the elastic bodies 4 and 6 are relatively opposite in direction, the rotor 3 can also be rotated forward and backward. In the case of the forward / reverse rotation, the resistor 14 may be eliminated depending on the purpose of use.

FIG. 3 shows another driving circuit according to the present invention, which comprises elastic bodies 4, 6 and piezoelectric bodies.
5 and 7 and the rotor 3 are shown together with a developed perspective view.

In the embodiment shown in FIG. 3, a driving circuit is provided independently for each of the piezoelectric bodies 5 and 7, and the piezoelectric body 5 includes a driving circuit comprising an AC power source 17, a 90 ° phase shifter 18, and a switch 19. The circuit is connected, while the piezoelectric body 7 has an AC power supply 20, 90
駆 動 A drive circuit including the phase shifter 21 and the switch 22 is connected. The frequencies of the AC power supplies 17 and 20 are different from each other.

Here, when a voltage is applied to the piezoelectric body and a traveling wave is generated in the elastic body, one mass point of the elastic body performs an elliptical motion, and the number of times of the elliptical motion within a certain time is determined by the applied voltage. It depends on the frequency, and the rotation speed of the rotor also changes in proportion to the number of elliptical movements.

Therefore, in the embodiment shown in FIG. 3, by switching the switches 19 and 22, a standing wave is generated in one elastic body and a traveling wave is generated in the other elastic body, so that one rotor 3 is connected to the AC power supply 17. And 21 can be driven to rotate at two different speeds.

Further, if a driving circuit is connected so that the traveling directions of traveling waves generated in the elastic bodies 4 and 6 are relatively opposite, the rotor 3
Can be reversed.

In the above-described embodiment, the piezoelectric elements 5 and 7 are formed by forming the piezoelectric elements 5a and 5b and the other pole part 5c, and similarly, the piezoelectric elements 7a and 7b and the other pole part 7c in a ring. However, a high driving torque may be generated by forming the piezoelectric element and the other pole in two or three rows.

(Effects of the Invention) As described above, according to the present invention, a structure in which one relative moving member is sandwiched between two vibrators, a standing wave is generated in one vibrator, and the other vibrator is generated in the other vibrator. Since the traveling wave is generated, the relative motion member can be rotatably supported with low friction without requiring a bearing structure using a bearing, and a vibration motor having a simple structure can be obtained.

In addition, since two vibrators are provided, it is possible to obtain a vibration motor that can easily change the driving speed of the relative motion member and rotate the rotation direction in the forward and reverse directions with a very simple driving circuit.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a vibration motor structure according to the present invention, and FIG. 2 is an explanatory view showing an embodiment of a drive circuit according to the present invention together with a development view of a vibrator and a relative motion member of the vibration motor. FIG. 3 is an explanatory diagram showing another embodiment of the drive circuit of the present invention. 1: Case 2: Base plate 3: Rotor 3a: Output shaft 4, 6: Elastic body 5, 7: Piezoelectric body 5a, 5b, 7a, 7b: Piezoelectric element 5c, 7c: Other pole part 8: Buffer member 9: Compression Coil spring 10, 11: Screw 12, 17, 21: AC power supply 13, 18, 21: 90 ° Phase shifter 14: Resistance 15, 16, 19, 22: Switch

Claims (1)

(57) [Claims] 1. A relative movement member having a first surface, a second surface different from the first surface, an elastic body having front and back surfaces, and an electromechanical transducer bonded to the back surface of the elastic body. A first vibrator in which the first surface of the relative motion member and the surface of the elastic body are pressed against each other, an elastic body having front and back surfaces, and an electromechanical transducer bonded to the back surface of the elastic body; A second vibrator in which a second surface of the relative motion member and a surface of the elastic body are pressed against each other;
A vibration motor, wherein a traveling wave is generated on a surface of the elastic body of the first vibrator, and a standing wave is generated on a surface of the elastic body of the second vibrator.