JPH0295183A - Vibrator actuator - Google Patents

Abstract

PURPOSE:To alter the direction of movement of a moving piece by forming a protrusion at a place, where the working of a component in the direction orthogonal to the direction of vibrations of a vibrator generating standing waves is equalized, installing the moving piece moved brought into contact with the protrusion and changing the phase relationship of the protrusion and standing waves. CONSTITUTION:When voltage is applied to an annular vibrator 1 such as a piezoelectric element disposed while polarity is inverted alternately, the vibrator 1 is shrunk and elongated at every element and vibrated in the direction of thickness. It is determined that the vibrator conducts a linear motion inclined at a fixed angle from the vertical direction (the direction of vibrations) according to a behavior at a point A of the vibrator 1 performing such vibrations. Since there are the same output directions at every half wavelength of standing waves at that time, mechanical protrusions are shaped at the positions. That is, the protrusions are formed it the corresponding each point A and point B of each element of the vibrator 1, and the vibrator is constituted so as to be brought into contact with a moving piece 2 only in the protrusions. Accordingly, the moving piece 2 is shifted in the right direction or the left direction by the standing waves of the vibrator 1, thus extracting a motion in one direction.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a vibrator actuator such as an ultrasonic motor.

<Prior Art> In recent years, actuators using electrostrictive or magnetostrictive vibrators have been put into practical use, and a piezoelectric motor using a piezoelectric element is known as a typical example.

Two methods are known for such a vibrator actuator: a standing wave drive method and a traveling wave drive method.

The standing wave drive method is a method in which a driven body is driven by a standing wave in the thickness direction of the vibrator.

In the traveling wave drive system, a vibrator such as a piezoelectric element is formed in two layers with different phases, and an alternating current with a different phase is applied to the two layers of vibrators to create a standing wave with a different phase between the two layers of vibrators. This method generates a traveling wave and obtains a traveling wave as its composite component.

<Problem to be solved by the invention> However, in the case of the above-mentioned standing wave method, it is difficult to keep track of the thickness, while in the case of the traveling wave method, it is easy to reduce the thickness, but the vibrator It is necessary to configure the oscillator to be 2M, and to apply voltages with different phases to the two-phase vibrator, which requires a two-phase power supply and has the drawback that the circuit configuration is complicated.

<Summary of the Invention> The present invention was made in order to improve the drawbacks of the conventional configuration described above, and an object thereof is to provide a vibrator actuator that can be made thinner and does not require a two-phase power source. It is something.

For the above purpose, the vibrator actuator of the present invention includes a vibrator that generates a standing wave, a protrusion provided at a position where the movement of the component in the direction orthogonal to the vibration direction of the vibrator is the same, and The basic feature is that the movable element moves in contact with a protrusion, and the moving direction of the movable element is changed by changing the phase relationship between the protrusion and the standing wave.

Effect〉 The vibrator that generates a standing wave has a movement component in a direction perpendicular to the vibration direction, and a protrusion is formed in this part, and the protrusion and the moving element are brought into contact to move the moving element. . By changing the phase relationship between the protrusion and the standing wave, the moving direction of the moving element can be changed.

<Example> The present invention will be described in detail below based on examples.

The present invention will be explained in detail with reference to FIGS. 1 to 4.

When a voltage is applied to an annular vibrator 1 such as a piezoelectric element arranged with alternately reversed polarity, the vibrator 1 contracts for each element.
It stretches and vibrates in the thickness direction as shown.

The equation for the vibration of the standing wave in the longitudinal direction (X direction) is expressed as follows.

2 π ξ= s i n (-X) ・s i n ((11
t)λ ----(1'') where ξ is the longitudinal displacement, λ is the wavelength, and ω is the natural frequency.

Also, when the thickness of the ring is T, the displacement in the lateral direction (X direction) is 　　2X It is expressed as

Assume that the movable element 2 is in contact with the right half of the element of the vibrator 1 that vibrates in this manner, and the contact point is designated as A. Looking at the behavior of this point A, it can be seen that -3= As shown in the figure, when moving between points A1 and A2, it performs a linear movement tilted at a predetermined angle from the vertical direction (vibration direction). If the vibration frequency is high enough when moving from A1 to A2, vibrator 1 and mover 2 will separate due to the inertial force acting on mover 2, and mover 2 will have A
The point force does not work.

On the other hand, when moving from A2 to A1, vibrator 1 and mover 2
contact, and the mover 2 receives the force at point A and moves to the upper right in the drawing. Since this upper right movement naturally has a rightward (X-axis direction) component, the mover 2 is moved rightward.

On the other hand, it is clear that the point B on the left half of the element of the vibrator 1 performs an oblique movement having a leftward component in the X-axis direction, contrary to the point A, and similarly, the movable element 2 in contact with this point B moves to the left.

In this way, it can be seen that the direction of the output in the X-axis direction becomes opposite at the nodes and antinodes of the standing wave. Since the same output direction exists for every half wavelength of the standing wave, by providing a mechanical protrusion at this position, it becomes possible to extract motion in one direction.

That is, if a protrusion is formed at each corresponding point A or B of each element of the vibrator 1, and the movable element 2 is configured to come into contact with the movable element 2 only at this protrusion, the movable element 2 can maintain the position of the vibrator 1. Move to the right or left depending on the wave.

An example is shown in FIG. In this example, the vibrator 1 is a combination of a piezoelectric body 10 and a stator 11 made of an elastic body. The piezoelectric body 10 has an annular shape as shown in FIG. 3, and is divided into 2n pieces (n is an integer), and each element is alternately polarized in different directions. With this configuration, by applying a predetermined voltage, the piezoelectric body 10 vibrates and generates a standing wave. A stator 11 made of an elastic body is attached on top of the piezoelectric body 10. As shown in FIG. 2, the stator 11 has an annular shape wider than the piezoelectric body 10, and has a plurality of protrusions 3 formed on its surface. The protrusions 3 are radially arranged protrusions having a rectangular planar shape, and 2n protrusions are formed at equal intervals in the circumferential direction. Each protrusion 3 is configured to be located on one half of each element of the piezoelectric body 1o. That is, in this embodiment, the neutral axis m3 of the protrusion 3 and the neutral axis m3 of the piezoelectric body 10
The piezoelectric body 10 is arranged so as to be shifted by 1/4 of its period.

The rotor 20 is in contact with the protrusion 3 configured in this manner with a predetermined pressure. This rotor 20 naturally contacts only the protrusion 3.

In the above configuration, when an AC voltage set to the resonance frequency of the stator 11 is applied to the piezoelectric body 10, the piezoelectric body 10
Since the polarization direction of each element is different, each element contracts and expands alternately. As a result, a standing wave is generated, and n waves as shown in FIG. 4 are generated on the stator 11. As a result, the protrusion 3 moves including a rightward component in the X-axis direction. The rotor 20 that contacts only this protrusion 3 performs a rightward movement. As a result, rotor 20 rotates.

However, in the above configuration, the moving direction of the rotor 20 is constant and cannot be changed. In the present invention, the direction of movement can be changed, and for this purpose, the position of the protrusion 3 and the phase relationship of the standing wave are configured to be changeable.

The principle will be explained with reference to FIG.

As shown in the figure, the direction of the output of the protrusion 3 differs depending on modes A and B of the standing wave generated in the stator 5. That is, in mode A, the phase relationship between the protrusion 3 and the standing wave is A in FIG.
Since it is the same as the point, an output to the right is generated. On the other hand, in mode B, which has a phase positionally different from mode A by π/2, the phase relationship between the protrusion 3 and the standing wave is the same as that at point B in FIG. 1, so that an output in the left direction is generated.

Therefore, by press-fitting the rotor to the protrusion 3 and selectively generating waves of mode A and mode B in the stator 5, it is possible to obtain an actuator that changes the direction of movement in the forward and reverse directions.

An embodiment of the present invention will be explained with reference to FIGS. 6 to 8.

It would be good if the relationship between the stator 5 and the standing waves could be changed to mode A and mode B as shown above.

Since the resonance phenomenon of the stator 5 is used to generate waves in the stator 5, the polarization of the piezoelectric body 4 bonded to the stator 5 does not need to be in the entire piezoelectric body 4, but only in a part of it. Therefore, by polarizing a part of the piezoelectric body 4 so that mode A waves are formed, and polarizing the remaining part so that mode B waves are formed, it is possible to change the direction of movement.

FIG. 6 shows the polarization configuration of the piezoelectric body 4. In this example, it is divided into two blocks, block A and block B, and each block is polarized alternately in different directions. Now, if the number of waves to be created on the piezoelectric body 4 is n, then the interval between each polarization is 2π/2n (rad).

The stator 5 is polarized so as to be line symmetrical to the line S-S'' passing through the center. On the other hand, the stator 5 has an annular shape wider than the piezoelectric body 4 as shown in FIG. The protrusions 3 are formed at equal intervals.The protrusions 3 are arranged radially and have a ridge shape.

The stator 5 and the piezoelectric body 4 are connected as shown in FIG.
The bonding is done so that the s' line and the neutral axis of the protrusion 3 coincide. According to this configuration, in block A, the relationship between the boundary lines of the polarization regions of the protrusion 3 and the piezoelectric body 4 is the same as the relationship in mode A shown in FIG. Therefore, if an AC voltage is applied only to the block A of the piezoelectric body 4, a wave of mode A is generated, and the protrusion 3
The output is in the right direction, and the rotor 20 in contact with the stator 5 rotates counterclockwise in FIG.

On the other hand, if AC voltage is applied only to block B, mode B
waves are generated, and the rotor 20 rotates clockwise.

At this time, the AC voltage applied may be one phase, instead of the conventional two-phase voltage.
Does not require phase power.

According to the configuration described above, the direction of movement can be easily changed, and only one phase of AC voltage is required.
It is also possible to simplify peripheral circuits. Furthermore, it is possible to make the device thinner than the conventional standing wave method.

Furthermore, the structure is simple because only one layer of piezoelectric material is required.

<Effects of the Invention> As explained above, the vibrator actuator of the present invention has the following effects:
comprising a vibrator that generates a standing wave, a protrusion provided at a position where the movement of a component in a direction perpendicular to the vibration direction of the vibrator is the same, and a mover that moves in contact with the protrusion, Since the moving direction of the mover is changed by changing the phase relationship between the protrusion and the standing wave, the moving direction can be easily changed, the thickness can be reduced, and the two-phase voltage can be changed. No need to apply. Furthermore, there is an advantage that there is no need to use two layers of piezoelectric material.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the basic principle of the present invention, FIG. 2 (A) is a plan view showing the configuration of an example of a vibrator, and (B) is a front view thereof.
FIG. 3 is a plan view of the piezoelectric body, FIG. 4 is an explanatory diagram of the operation, and FIG. 5 is an explanatory diagram of the principle of changing the direction of movement. FIG. 6 is an explanatory diagram of an embodiment of the present invention, and is a plan view of a piezoelectric body, FIG. 7 (A) is a plan view of a stator, (B) is a front view thereof, and FIG. 8 shows an assembled state. (A) is a plan view, and (B) is a front view. 1: Vibrator, 2: Mover, 3: Protrusion, 4: Piezoelectric body, 5:
Stator, lO: piezoelectric body, 11: stator, 20: rotor.

Claims (1)

[Claims] A vibrator that generates a standing wave; a protrusion provided at a position where the movement of the component in a direction perpendicular to the vibration direction of the vibrator is the same; and a protrusion that moves in contact with the protrusion. A vibrator actuator comprising: a movable element, the moving direction of the movable element being changed by changing the phase relationship between the protrusion and the standing wave.