JPH02202378A - Planar ultrasonic actuator - Google Patents

Abstract

PURPOSE:To reduce the thickness of an actuator by producing vertical vibration based on flex vibration of a planar vibration body while producing lateral vibration through a beam vibration body and achieving two dimensional movement of a moving body based on an oval locus at the free end of the beam. CONSTITUTION:An ultrasonic actuator comprises a planar vibration body 101 and vibration beam bodies 102a-102c which are secured to the vibration body 101 at the central sections thereof. The vibration body 101 comprises a piezoelectric body 106 having small electrode and resilient body 107, while the vibration beam body 102 comprises piezoelectric bodies 103a-104a adhered to two adjacent faces having square cross-section and a resilient body 105a. When a moving body contacts with the free end of the vibration beam body 102, it can move in two dimension.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a planar ultrasonic actuator whose driving force is elastic vibration excited by a piezoelectric material such as a piezoelectric ceramic.

2. Description of the Related Art In recent years, ultrasonic actuators such as ultrasonic motors and ultrasonic linear motors have attracted attention, in which elastic vibrations are excited in a vibrating body made of a piezoelectric material such as a piezoelectric ceramic, and this is used as a driving force.

Hereinafter, a conventional ultrasonic actuator will be explained with reference to the drawings.

FIG. 7 is a general view of a toroidal ultrasonic motor, in which a vibrating body 3 is constructed by bonding a toroidal piezoelectric body 2 such as a toroidal piezoelectric ceramic to a toroidal elastic body 1 with slits. A movable body 6 is composed of an abrasive friction material 4 and an elastic body 5.

When the movable body 6 is pressurized and installed on the vibrating body 3 and an AC voltage is applied to the piezoelectric body 2, a traveling wave of bending vibration that advances in the circumferential direction is excited in the vibrating body 3, and the movable body 6 is caused by the traveling wave. Driven and rotated.

FIG. 8 is a general view of an ultrasonic linear motor, in which a vibrating body 11 is constructed by sandwiching and fixing disc expansion piezoelectric bodies 7 and 8 between cylindrical elastic bodies 9 and 10. When an alternating current electric field near the resonant frequency of the vibrating body 11 is applied to the piezoelectric bodies 7 and 8, the vibrating body 11 vibrates in the vertical vibration mode in a longitudinal vibration mode, as shown by the arrow in the figure.

The mechanical impedance seen from the vibration surface of the vibrating body 11 is impedance-converted by the horn 12 and transmitted to the transmission rod 13.
mechanical impedance for flexural vibrations.

The tip of the hoe 712 is acoustically coupled to a portion of the transmission rod 13 near one end. Therefore, the vertical vibration of the vibrating body 11 is efficiently transmitted to the transmission rod 13 by the horn 12, and the transmission rod 13 bends and vibrates. This bending vibration progresses from one end of the transmission rod 13 to the other end.

In a part near the other end of the transmission rod 13, the hole 7 is connected like the one end.
14 tips are acoustically coupled.

A vibrating body 19, which is exactly the same as the vibrating body 11, is constructed by sandwiching and fixing the disk expansion piezoelectric bodies 15 and 16 between cylindrical elastic bodies 17 and 18.

This vibrating body 19 is connected to the horn 14. Therefore, the bending vibration that has progressed from one end of the transmission rod toward the other end is transmitted to the vibrating body 19 by the horn 14 and converted into vertical vibration of the vibrating body 19. Piezoelectric bodies 15 and 1
6 is connected to an impedance-matched load R, and the above-mentioned vertical vibration is consumed by the load R. Therefore, the bending vibration exists only as a traveling wave in the transmission rod 13.

A moving body 20 is driven by the bending vibration traveling through the transmission rod 13, and moves in a direction opposite to the traveling direction of the traveling wave. In the above description, the moving direction of the moving body 20 is assumed to be one direction, but if the driving end is reversed, the moving body 20 also moves in the opposite direction.

FIG. 9 shows the principle by which a traveling elastic wave of deflection drives a moving body. Due to the bending vibration of the vibrating body (or transmission rod) 21, a point (for example, point A) on the surface of the vibrating body 21 draws an elliptical locus in the vertical direction w and the self-imaging direction U. The velocity at the apex of this elliptical trajectory is opposite to the direction of travel of the wave. Vibrating body 21
If the movable body 22 is installed under pressure on the wave, the movable body 22 will come into contact with the vibrating body 21 only near the peak of the wave. Therefore, the movable body 22 is driven in a direction opposite to the direction in which the waves travel due to the frictional force between the vibrating body 21 and the movable body 22 and the speed in the lateral direction of the elliptical trajectory. Further, numeral 23 in the figure is a wear-resistant friction material for efficiently extracting the lateral component of the elliptical locus.

Problems to be Solved by the Invention As described above, in the conventional ultrasonic actuators described above, the movement of the moving body is rotational or linear. If you try to configure a planar ultrasonic actuator in which a moving object moves in any direction on a plane using these ultrasonic actuators, you will need multiple ultrasonic motors or ultrasonic linear motors, and therefore the structure will be complicated. The problem was that the size became larger.

Means for Solving the Problem A piezoelectric body A is adhered to a flat elastic body to form a flat vibrating body, and a voltage is applied to the piezoelectric body A to excite bending vibration in the flat vibrating body. A plurality of beams with a square cross section are fixed in the center near the antinode of the vibration of the pincer vibration, and a plurality of beams are installed two-dimensionally on a flat plate vibrating body, and a piezoelectric material is attached to each of two adjacent rectangular surfaces of the beam. B is glued to form a beam-shaped vibrating body, and a voltage is applied to the piezoelectric body B to excite two bending vibrations perpendicular to each other in the beam-shaped vibrating body, and one free end of the beam-shaped vibrating body is The movable body is placed in pressurized contact and configured to move the movable body in two dimensions.

Vibration in the vertical direction is obtained by the bending vibration of the working flat plate vibrating body,
By obtaining lateral vibration with a beam-shaped vibrating body and exciting two vibrations simultaneously, the free end of the beam draws an elliptical trajectory, and the moving object that is in contact with the free end of the beam moves in two dimensions. This provides a thin planar ultrasonic actuator with a simple structure.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a planar ultrasonic actuator according to an embodiment of the present invention. In the figure, 101 is a flat plate-shaped vibrating body, and a piezoelectric material such as piezoelectric ceramic is pasted on the back surface. 102 aNl 02 b, 102
cl . . . is a beam-shaped vibrating body each having a square cross section and configured by bonding piezoelectric bodies B to two adjacent rectangular surfaces, and the central part is fixed to the flat plate-shaped vibrating body 101. It is installed by doing. 103 al.
l 04 a is a piezoelectric body, and together with the elastic body 105a constitutes the beam-shaped vibrating body 102a. The following piezoelectric body 103b,
104b1 ...... and elastic body 105 bl
The same applies to . . . etc.

Although only seven beam-shaped vibrating bodies are shown in the same figure, in reality, there are two near the antinode of the bending vibration of the flat plate-shaped vibrating body 101.
Arranged at equal intervals in the dimension.

FIG. 2 is a diagram showing the configuration and operation of a flat vibrating body used in a flat ultrasonic actuator. 106 is a piezoelectric material having small electrodes, which are alternately polarized in opposite directions in the thickness direction as shown by the positive and negative signs in the figure. This piezoelectric body 10
6 is bonded to a flat plate-shaped elastic body 107, and constitutes a flat plate-shaped vibrating body 101. During driving, each small electrode of the piezoelectric body 106 is short-circuited, and an alternating current voltage near the resonance frequency of the flat vibrating body is applied. The plate-shaped vibrating body 101 undergoes bending vibration as shown by the vibration displacement distribution in the figure.

As shown in FIG. 1, a plurality of beam-shaped vibrating bodies 102 are two-dimensionally installed near the antinode of this bending vibration.

In the above embodiment, bending vibrations were excited in only one direction of the flat plate vibrating body, but as shown in Figure 3, bending vibrations can also be excited in two orthogonal directions. It is a figure showing composition and operation.

Reference numeral 109 denotes a piezoelectric body having square small electrodes, which are polarized in the thickness direction so that adjacent small electrode portions are in opposite directions, as shown by the positive and negative signs in the figure. This piezoelectric body 10
9 is bonded to a flat plate-shaped elastic body 110, and constitutes a flat plate-shaped vibrating body 108.

During driving, each small electrode of the piezoelectric body 106 is short-circuited, and an alternating current voltage near the resonance frequency of the flat vibrating body is applied.

The flat plate-shaped vibrating body 108 vibrates only at I4 directions perpendicular to each other, as shown by the vibration displacement distribution in the figure. A beam-shaped vibrating body 102 that vibrates in the lateral direction is installed near the antinode of this bending vibration (in the center of the small electrode).

Figure 4 shows the configuration and operation of the beam-shaped vibrator. In the figure, reference numeral 111 is a square bar with a square cross section, and a piezoelectric body 112 and a piezoelectric body 113 are bonded to two adjacent surfaces to form a beam-shaped vibrating body 114. Here, the polarization directions of the piezoelectric bodies bonded within the same plane are the same. The beam-shaped vibrating body 114 is fixed to a flat plate-shaped vibrating body 115 at its center.

When an AC voltage near the resonance frequency of the beam-shaped vibrating body 114 is applied to the piezoelectric body 112, the beam-shaped vibrating body 114 vibrates in a first-order bending vibration mode having a displacement distribution shown in the figure. When an AC voltage near the resonant frequency of the beam-shaped vibrating body 114 is similarly applied to the piezoelectric body 113, the beam-shaped vibrating body 114 generates a bending vibration having a similar displacement distribution in a plane perpendicular to the displacement shown in the figure. do.

FIG. 5 shows the structure and operation of a beam-shaped vibrating body according to another embodiment.

In the figure, 116 is a square bar with a square cross section;
A piezoelectric body 117 and a piezoelectric body 118 are bonded to two adjacent surfaces to form a beam-shaped vibrating body 119. here,
The polarization directions of piezoelectric bodies bonded within the same plane are opposite. The beam-shaped vibrating body 119 has a flat plate-shaped vibrating body 12 at its center.
Fixed to 0. The beam-shaped vibrating body 11 is attached to the piezoelectric body 117.
When an AC voltage near the resonance frequency 9 is applied, the beam-shaped vibrating body 119 vibrates in a high-order pinch vibration mode having a displacement distribution shown in the figure. When an AC voltage near the resonant frequency of the beam-shaped vibrating body 119 is similarly applied to the piezoelectric body 118, the beam-shaped vibrating body 119 generates a bending vibration having a similar displacement distribution in a plane orthogonal to the displacement shown in the figure. do.

FIG. 6 is an explanatory diagram of the operation of the planar ultrasonic actuator when the first-order pinch vibration shown in FIG. 4 is used as a beam-shaped vibrator. The beam-shaped vibrating body 122 is fixed at a position near the antinode of the pinch vibration of the flat plate-shaped vibrating body 121 via its central portion. Then, the beam-shaped vibrating body 122 and the flat plate-shaped vibrating body 1
The resonance frequencies of 21 are adjusted to be almost the same. When an alternating current voltage near the resonance frequency is applied to the piezoelectric body constituting the flat vibrating body 121, the flat vibrating body 121 undergoes a bending vibration that is displaced in the direction of arrow A (vertical direction), causing the beam vibrating body 122 to vibrate. When an alternating current voltage near the resonance frequency is similarly applied to the piezoelectric body, the beam-shaped vibrating body 122 moves as shown by arrow B.
It produces a flexural vibration that causes displacement in the direction (lateral direction). Therefore, if the piezoelectric bodies are simultaneously driven with alternating current voltages that are 90 degrees out of phase with each other, the free end of the beam-shaped vibrating body 122 vibrates in an elliptical locus as shown in the figure. Here, the solid line is the vibration state of the ultrasonic actuator at a certain time, and the dotted line is the vibration state after 1/4 period. Similarly, it is also possible to easily move the free end of the beam-shaped vibrating body 122 by drawing an elliptical locus in a plane orthogonal to the above-mentioned elliptical locus.

Therefore, the beam-shaped vibrating body 12 installed on the flat plate-shaped vibrating body 121
If the movable body 123 is installed so as to be in contact with the free end of the movable body 123, the movable body 123 can be moved in the direction of arrow B. Therefore, in FIG. 1, the beam-shaped vibrating bodies 102 a and 102 bl installed on the flat plate-shaped vibrating body 101
If the movable body is placed in pressure contact with the free end of the movable body, the movable body can be moved in any direction within the plane.

Here, we have explained the operation of the planar ultrasonic actuator when using the first-order bending vibration shown in Figure 4 as a beam-shaped vibrator, but we have explained the operation of the planar ultrasonic actuator when using the first-order bending vibration shown in Figure 5. The operation of the planar ultrasonic actuator is also similar.

Effects of the Invention According to the present invention, a planar ultrasonic actuator with a simple structure and a small thickness can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a planar ultrasonic actuator according to an embodiment of the present invention, and FIGS. 2(a) and (b) are plan views showing the configuration of a planar vibrating body used in the planar ultrasonic actuator. Displacement distribution diagram showing the operation, Figure 3 (a), (b)
and (c) are respectively a plan view showing the configuration of another flat vibrating body, and a displacement distribution diagram showing the vertical and horizontal movements. A plan view showing the configuration and a displacement distribution diagram showing the operation of a beam-shaped vibrating body used in the actuator, and FIGS. 5(a) and (b) respectively show a plan view showing the configuration and operation of another beam-shaped vibrating body. Displacement distribution map, 6th
The figure is an explanatory diagram of the operation of a planar ultrasonic actuator, Fig. 7 is a perspective view of a conventional disk-type ultrasonic motor, Fig. 8 is an overview of a conventional ultrasonic linear motor, and Fig. 9 is an elastic progression of deflection. FIG. 2 is an explanatory diagram showing the principle of how waves drive a moving body. 101... Flat plate type vibrating body, 102... Beam type vibrating body, 103.104... Piezoelectric body, 105... Elastic body, 106... ... Piezoelectric body, 107... Elastic body, 108... Flat vibrating body, 109... Piezoelectric body, 110... Elastic body, 111. ...Elastic body 112, 113... Piezoelectric body, 114... Beam-shaped vibrating body, 115... Flat plate-shaped vibrating body, 116... Elastic body 117, 118... Piezoelectric body, 119... Beam-shaped vibrating body, 120... Flat plate-shaped vibrating body. Name of agent: Patent attorney Shigetaka Kurino and one other person

Claims (3)

[Claims] (1) A piezoelectric body A is adhered to a flat elastic body to form a flat vibrating body, a voltage is applied to the piezoelectric body A to excite bending vibration in the flat vibrating body, and the vibration of the bending vibration is A plurality of beams having a square cross section are arranged two-dimensionally on a flat plate vibrating body by fixing their central portions near the antinode of the beam, and piezoelectric bodies B are bonded to each of two adjacent rectangular surfaces of the beams. A voltage is applied to the piezoelectric body B to excite two bending vibrations perpendicular to each other in the beam-shaped vibrating body, and one free end of the beam-shaped vibrating body is brought into pressure contact. A planar ultrasonic actuator, characterized in that a movable body is installed in a plane, and the movable body is moved two-dimensionally. (2) The planar ultrasonic actuator according to claim 1, wherein the planar ultrasonic actuator excites the bending vibration in only one direction of the planar vibrating body or in two directions. (3) The planar ultrasonic actuator according to claim 1, wherein the beam-shaped vibrating body is excited with either a first-order bending vibration or a higher-order bending vibration.