JPH02202381A - Planar ultrasonic actuator - Google Patents

Abstract

PURPOSE:To simplify the structure and to reduce the thickness of an actuator by securing one end of a beam having square cross section closely to the antinode of flex vibration of a planar vibration body adhered with a piezoelectric body then arranging a plurality of vibration bodies two dimensionally and arranging a moving body at the other free end of a cantilever vibration beam body adhered with a piezoelectric body such that the moving body can move two dimensionally. CONSTITUTION:A plurality of cantilever vibration beam bodies 102a, 102b... having square cross section and adhered with piezoelectric bodies onto two adjacent rectangular faces thereof are arranged, with same two dimensional interval, in the vicinity of the antinode of flex vibration of a planar vibration body 101 applied with piezoelectric bodies, and a moving body is arranged at the free ends of the vibration bodies 102a, 102b.... Vertical vibration is produced through flex vibration of the vibration body 101 while lateral vibration is produced through the vibration bodies 102a, 102b..., where two vibrations are excited simultaneously to describe an elliptical locus at the free end so as to move the moving body two dimensionally. By such arrangement, the structure of actuator is simplified and the thickness thereof can be reduced.

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. 6 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. 7 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 horn 12 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.

At a portion near the other end of the transmission rod 13, the tip of the horn 14 is acoustically coupled, similar to the one end.

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. 8 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 horizontal 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 use these ultrasonic actuators to construct a planar ultrasonic actuator in which a moving object moves in any direction on a plane, you will need multiple ultrasonic motors or ultrasonic linear motors, resulting in a complicated structure. 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 beam with a square cross section is fixed at one end near the antinode of the flexural vibration, and a piezoelectric material B is glued to each of the two adjacent rectangular surfaces of the beam to create a cantilever structure. A beam-shaped vibrating body is configured, and a voltage is applied to the piezoelectric body B to excite two bending vibrations perpendicular to each other in the cantilever-shaped vibrating body, and the other free end of the cantilever-shaped vibrating body is A movable body is placed in pressurized contact with the movable body, and the movable body is configured to move 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 using a cantilever vibrator and exciting two vibrations at the same time, the free end of the beam draws an elliptical trajectory, and the moving object in contact with the free end of the beam is moved in two dimensions. By doing so, a thin planar ultrasonic actuator with a simple structure is provided.

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 a.

102 bll 02 c, . . . are cantilever vibrating bodies each having a square cross section and each having a piezoelectric material adhered to two adjacent rectangular surfaces.

103 a and 104 a are piezoelectric bodies, and the elastic body 1
Together with 05a, the cantilever vibrating body 102a is configured.

The following piezoelectric bodies 103b1104b,...
The same applies to the elastic body 105 bl . . . . Although only seven cantilever vibrators are shown in the figure, they are actually arranged two-dimensionally at equal intervals near the antinode of the bending vibration of the flat plate vibrator.

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, and the small electrodes are alternately polarized in opposite directions in the thickness direction, as shown by the positive and negative signs in the figure. This piezoelectric body 106 is adhered to a flat plate-shaped elastic body to constitute a flat plate-shaped vibrating body 101. During driving, each small electrode of the piezoelectric body 10B 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. The cantilever vibrating body 102 shown in FIG. 1 is installed near the antinode of this bending vibration.

FIG. 3 is a diagram showing the configuration and operation of a cantilever vibrating body used in a planar ultrasonic actuator.

103 and 104 are piezoelectric bodies B polarized in the thickness direction, which are bonded to an elastic body 105 having a square cross section to form a cantilever vibrating body 102. When an AC voltage near the resonant frequency of the cantilever vibrating body 102 is applied to the piezoelectric body 103, the cantilever vibrating body 102 bends and vibrates in the direction of arrow C. When an AC voltage near the resonance frequency of the cantilever vibrating body 102 is applied to the piezoelectric body 104, the cantilever vibrating body 102 bends and vibrates in the direction of the arrow. Also, 1
Reference numeral 08 denotes a screw portion for attachment to the flat plate vibrating body 101.

FIG. 4 is an explanatory diagram of the operation of a planar ultrasonic actuator according to one embodiment of the present invention. The cantilever vibrating body 102 is
Since it is screwed to a position near the antinode of the bending vibration of the flat plate vibrating body 101, it operates reliably as a cantilever beam. The resonant frequencies of the cantilever vibrating body 102 and the flat plate vibrating body 101 are adjusted to be approximately the same. When an AC voltage near the resonant frequency is applied to the piezoelectric material constituting the flat vibrating body 101, the flat vibrating body 101 moves in the direction of arrow F (
When an AC voltage near the resonant frequency is similarly applied to the piezoelectric body constituting the cantilever-shaped vibrating body, the cantilever-shaped vibrating body 102 vibrates in the direction of arrow E (horizontal direction). flexural vibration that causes displacement in the 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 cantilever vibrating body 102 vibrates in an elliptical locus as shown in the figure. The solid line in the figure represents the vibration state at a certain time, and the dotted line represents the vibration state one quarter period later. Similarly, the cantilever vibrating body 1
It is also possible to move the free end of 02 by drawing an elliptical locus in a plane perpendicular to the above-mentioned elliptical locus.

Therefore, if the movable body is installed so as to contact the free end of each of the cantilever vibrating bodies 102a1102b1102c1 installed on the flat plate vibrating body 101, the movable body can move in any direction within the plane. can be moved to.

In the above embodiment, bending vibrations were excited only in one direction of the flat plate vibrating body, but bending vibrations can also be excited in two orthogonal directions as shown in FIG.

FIG. 5 is a diagram showing the configuration and operation of the flat plate vibrating body. 1
09 is a piezoelectric body having square small electrodes, and is 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 109
is bonded to the flat plate-shaped elastic body 110 to constitute a flat plate-shaped vibrating body 111. 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 111 makes bending vibrations perpendicular to each other, as shown by the vibration displacement distribution in the figure. A cantilever vibrating body that vibrates in the transverse direction is installed near the antinode of this bending vibration.

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. A plan view showing the structure of the body and a displacement distribution diagram showing the movement, Part 3
The figures are a perspective view of a cantilever vibrating body used in the planar ultrasonic actuator of the embodiment shown in Fig. 1, FIG.
Figures (a), (b), and (c) are a plan view showing the configuration of another flat vibrating body used in a flat ultrasonic actuator, a displacement distribution diagram showing vertical and horizontal movements, and a sixth figure. Figure 7 is an overview of a conventional disc-type ultrasonic motor, Figure 7 is an overview of a conventional ultrasonic linear motor, and Figure 8 is an explanatory diagram showing the principle of driving a moving body by elastic traveling waves of flexure. It is. 101... Flat plate type vibrating body, 102... Cantilever type vibrating body, 103.104
...Piezoelectric body, 105...Elastic body, 106...Piezoelectric body. 107...Elastic body, 108...Screw part, 109...Piezoelectric body, 110...Elastic body, 111...Flat plate vibration body. Name of agent Patent attorney Shigetaka Awano and 1 other person Figure 42 Figure 4 Figure Cb) 10/乎! Shape exhibition buttai first bad luck

Claims (2)

[Claims] (1) 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, and the antinode of the bending vibration is By fixing one end of a beam with a square cross section in a nearby position, a plurality of beams are arranged two-dimensionally on a flat vibrating body, and a piezoelectric material B is adhered to each of two adjacent rectangular surfaces of the beam to form a piece. A beam-shaped vibrating body is constructed, and a voltage is applied to the piezoelectric body B to excite two bending vibrations perpendicular to each other in the cantilever-shaped vibrating body, and the other end of the cantilever-shaped vibrating body is free. A planar ultrasonic actuator, characterized in that a moving body is installed at an end and the moving body is moved two-dimensionally. (2) A planar type according to claim 1, characterized in that a screw is provided at one end of the cantilever vibrating body, and the cantilever vibrating body is fixed to the flat plate vibrating body via the screw. Ultrasonic actuator.