JPH02228270A - Plane type ultrasonic actuator - Google Patents

Abstract

PURPOSE:To decrease the vibration loss by fixing beam-shaped vibrators near the flexural vibration nodes of plane vibrators and generating transverse vibration of the free ends thereof and at the same time vertical vibration by longitudinal vibration with both the ends free. CONSTITUTION:A plurality of beam-shaped vibrators 102, which are arranged in matrix form, are fixed near the flexural vibration nodes of plane vibrators 101 at the center thereof. The resonance frequency (f) of longitudinal vibration of the vibrators 102 and that of flexural vibration of the vibrators 101 are regulated to approximately the same value. When alternating voltage of frequency of about (f) is applied to piezoelectric bodies which construct the vibrators 101, the tips of the vibrators 102 are displaced transversely by flexural vibration of the vibrators 101. When alternating voltage of frequency of about (f) is applied to piezoelectric bodies which construct the vibrators 102, the vibrators 102 are displaced vertically and vibrates longitudinally. When the piezoelectric bodies are driven by alternating voltage of a 90 deg. difference in phase simultaneously, the free ends of the vibrators 102 vibrate with an ellipsoidal trajectory. A moving body 111 can be moved in an arbitrary direction on a plane if brought in contact with the free ends of the vibrators 102 by pressurization.

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. 5 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. 6 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
8 is connected to an impedance-matched load R, and the above vertical vibration is consumed by the load R. Therefore, the pinch vibration exists in the transmission rod 13 only as a traveling wave.

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. 7 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, a piezoelectric body B is adhered to a beam-shaped elastic body to constitute a beam-shaped vibrating body, and a piezoelectric body A is bonded to the piezoelectric body A. A voltage is applied to excite the bending vibration in two directions of the flat plate-shaped vibrating body, a voltage is applied to the piezoelectric body B to excite longitudinal vibration in the beam-shaped vibrating body, and Either drill a screw hole in the center of the beam-shaped vibrating body and screw the screw configured in the center of the beam-shaped vibrating body into the screw hole, or drill a hole in the vicinity of the bending vibration node of the flat plate-shaped vibrating body and insert it into the center of the beam-shaped vibrating body. By press-fitting the columnar part configured in Vibrations are simultaneously excited to create an elliptical locus at the free end of the beam-shaped vibrating body, a moving body is placed in pressure contact with at least one of the free ends, and the moving body is moved two-dimensionally.

Action Either drill a screw hole at a position near the vibration node of the flexural vibration of the flat plate vibrating body, and screw the screw configured in the center of the beam-shaped vibrator into the screw hole, or By drilling a hole at a position and press-fitting a cylindrical part configured at the center of the beam-shaped vibrating body into the hole, the beam can be fixed at a position near the vibration node of the pinched vibration of the flat plate-shaped vibrating body using a method of fixing the beam with low vibration loss. By installing a shaped vibrating body, obtaining horizontal vibration at the free end of the beam-shaped vibrating body, and obtaining vertical vibration by vertical vibration of both ends of the beam-shaped vibrating body, and exciting the two vibrations at the same time. By making the free end of the beam-shaped vibrating body draw an elliptical locus and moving the moving body in contact with the free end of the beam-shaped vibrating body in two dimensions, a thin planar ultrasonic actuator with a simple structure was created. provide.

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. The plate-shaped vibrating body 101 bends and vibrates in two directions: vertically and horizontally. 102as 102bs 102c
t----・-1i, it is a solitary beam-shaped vibrating body, and a screw hole is bored at a position near the vibration node of the bending vibration of the flat plate-shaped vibrating body 101, and it is configured in the center of the beam-shaped vibrating body 102. By screwing a screw into a screw hole or by drilling a hole at a position near the bending vibration node of the flat plate vibrating body 101 and press-fitting the cylindrical part formed at the center of the beam vibrating body 102 into the hole, It is installed near the bending vibration node of the flat plate vibrating body 101.

Note that although only nine beam-shaped vibrating bodies are shown in the figure, in reality, a plurality of beam-shaped vibrating bodies are installed in a matrix on the flat plate-shaped vibrating body 101.

FIG. 2 is a diagram showing the configuration and operation of a flat vibrating body used in a flat ultrasonic actuator. FIG. 2(a) is a plan view of the flat plate-shaped vibrating body. 103 is a piezoelectric body having small electrodes for driving, and adjacent small electrode portions are alternately polarized in opposite directions in the thickness direction as shown by the positive and negative signs in the figure. This piezoelectric body 103 is adhered to a flat plate-shaped elastic body 104 to constitute a flat plate-shaped vibrating body 101. During driving, each small electrode of the piezoelectric body 103 is short-circuited, and the flat vibrating body 10
An alternating current voltage near the resonance frequency of 1 is applied. The flat plate-shaped vibrating body 101 has vibration displacement distributions (b) and (C) in the figure.
), it causes flexural vibration in two directions within the plane.

In other words, at the time shown in the figure, the places with positive signs in the figure become valleys, and the places with negative signs become mountains, and at the next moment, the places with positive signs vibrate. Places with a sign become mountains, and places with a negative sign make troughs, resulting in flexural vibration.

Positions a1, bl, . . . of the positive and negative boundaries become nodes of bending vibration. As shown in FIG. 1, a plurality of beam-shaped vibrating bodies 102 are two-dimensionally installed in the vicinity of bending vibration nodes by fixing their centers.

Figure 3 shows the configuration and operation of the beam-shaped vibrator. In the same figure (a), 106 is a cylindrical elastic body with a cylindrical part 107 in its center, four side surfaces are made, and a total of four piezoelectric bodies 105 are bonded to each side surface. shaped vibrating body 1
02.

Here, the piezoelectric bodies are polarized in the thickness direction and are all bonded in the same direction. When an AC voltage near the resonance frequency of the longitudinal vibration of the beam-shaped vibrating body 102 is applied to the four piezoelectric bodies 105, the beam-shaped vibrating body 102 vibrates in the longitudinal vibration mode of the transverse effect in the direction of the arrow in the figure. do. FIG. 5B is a displacement distribution diagram of longitudinal vibration. That is, the beam-shaped vibrating body 102 exhibits maximum displacement at both ends, and the vertical vibration becomes zero at the center.

Therefore, the central cylindrical portion 107 is connected to the flat plate-shaped vibrating body 10.
If it is fixed by press-fitting it into a hole provided in the vibration node of No. 1, it is possible to fix it with less loss. Also, here, piezoelectric bodies are bonded to four sides of the elastic body 10B, but
At least if a piezoelectric material is attached to the work surface, longitudinal vibration can be excited in the same way.

FIG. 4 shows the configuration of another beam-shaped vibrating body. In the same figure,
108 is a prismatic elastic body with a threaded part 109 in the center, and a piezoelectric body 11 is attached to each of the four rectangular sides.
0 is adhered to form a beam-shaped vibrating body 102. Here, the piezoelectric bodies are polarized in the thickness direction and are all bonded in the same direction. When an AC voltage near the resonant frequency of the longitudinal vibration of the beam-shaped vibrating body 102 is applied to the four piezoelectric bodies 110, the beam-shaped vibrating body 102 vibrates in the direction of the arrow in the figure in a transverse effect longitudinal vibration mode. . That is, as shown in FIG. 3(b), the beam-shaped vibrating body 102 exhibits maximum displacement at both ends, and the vertical vibration becomes O at its center. Therefore, by screwing the central cylindrical part into the screw hole provided at the vibration node of the flat plate-shaped vibrating body 101, fixing with less loss is possible. Further, here, piezoelectric bodies are bonded to four surfaces of the elastic body 108, but if a piezoelectric body is bonded to at least one surface, longitudinal vibration can be similarly excited.

FIG. 5 is a side view for explaining the operation of the planar ultrasonic actuator. The beam-shaped vibrating body 102 is fixed at its center near the bending vibration part of the flat plate-shaped vibrating body 101 by screwing or press-fitting.

The longitudinal vibration of the beam-shaped vibrating body 102 and the flat plate-shaped vibrating body 10
The resonant frequencies of the bending vibrations of No. 1 are adjusted to be almost the same. When an AC voltage near the resonant frequency is applied to the piezoelectric material constituting the flat plate vibrating body 101, the beam-shaped vibrating body 10
The tip of the plate-shaped vibrating body 101 is laterally displaced by the bending vibration of the plate-shaped vibrating body 101, and when an AC voltage near the resonance frequency is similarly applied to the piezoelectric body constituting the beam-shaped vibrating body 102, the beam-shaped vibrating body 102 moves up and down. It produces longitudinal 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 beam-shaped vibrating body 102 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,
The dotted line is the vibration state after one-quarter cycle. If the operation explained here is assumed to be the operation at the position al in Fig. 2, then by the same operation at the position bl in Fig. 2, the free end of the beam-shaped vibrating body is You can also easily move it by drawing an elliptical trajectory.

Therefore, the beam-shaped vibrating body 10 installed on the flat plate-shaped vibrating body 101
If the movable body 107 is installed so as to be in contact with one free end of the movable body 111, it is possible to move the movable body 111 within a plane. Therefore, in FIG. 1, the beam-shaped vibrating bodies 102 a and 102 bl installed on the flat plate-shaped vibrating body 101
. . . The moving body 111 is moved so as to contact the free end.
If they are placed in pressure contact with each other, the movable body can be moved in any direction within the plane.

Here, we have explained the operation of a planar ultrasonic actuator when using longitudinal vibration with a transverse effect as shown in Figure 3 as a beam-shaped vibrator, but when using longitudinal vibration with a longitudinal effect such as a Langevin vibrator, A similar effect can be obtained.

Effects of the Invention According to the present invention, since the central part of the beam-shaped vibrating body is fixed to the flat plate-shaped vibrating body by press-fitting or screwing, it is possible to achieve fixation with less vibration loss, and also to achieve higher accuracy than body processing. It is easy to release and mass-produce.

In addition, a planar ultrasonic actuator with a simple structure, thin thickness, and high efficiency can be realized.

[Brief explanation of the drawing]

FIG. 1 is an overview diagram of a planar ultrasonic actuator according to an embodiment of the present invention, and FIG.
b) (c) is a displacement distribution diagram showing the operation, Figure 3 (a) is a perspective view showing the configuration of a beam-shaped vibrator used in a planar ultrasonic actuator, and Figure 3 (b) is a displacement distribution diagram showing the operation. figure,
Fig. 4 is a perspective view showing the configuration of another beam-shaped vibrating body used in a planar ultrasonic actuator, Fig. 5 is a side view for explaining the operation of the planar ultrasonic actuator, and Fig. 6 is a toroidal ultrasonic actuator. FIG. 7 is an overview diagram of a sonic motor, FIG. 7 is an overview diagram of an ultrasonic linear motor, and FIG. 8 is an explanatory diagram showing the principle of elastic traveling waves of deflection driving a moving body. 101... Flat plate type vibrating body, 102... Beam type vibrating body, 103... Piezoelectric body, 104... Elastic body, 105...・Piezoelectric body, 10θ...Elastic body, 107... Cylindrical part, 108... Cicada body, 109... Screw part, 110... Piezoelectricity Body, 111...Moving body. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] Piezoelectric body A is adhered to a flat plate elastic body to form a flat plate-shaped vibrating body, piezoelectric body B is adhered to a beam-shaped elastic body to constitute a beam-shaped vibrating body, and a voltage is applied to the piezoelectric body A to produce the above-mentioned Flexural vibrations are excited in two directions of the flat vibrating body, and a voltage is applied to the piezoelectric body B to excite longitudinal vibration in the beam vibrating body, so that the vibration is applied to the piezoelectric body B at a position near the bending vibration node of the flat vibrating body. A plurality of beam-shaped vibrating bodies are arranged two-dimensionally by fixing the vicinity of the central part, and a movable body is installed in pressurized contact with at least one free end of the beam-shaped vibrating body, and the above-mentioned movement is performed. In a planar ultrasonic actuator that moves a body in two dimensions, a screw hole is drilled at a position near the bending vibration node of the flat vibrating body, and a screw configured in the center of the beam vibrating body is screwed into the screw hole. Alternatively, by drilling a hole in the vicinity of the bending vibration node of the flat plate vibrating body and press-fitting a cylindrical part formed in the center of the beam vibrating body into the hole, the beam shape can be applied to the flat plate vibrating body. A planar ultrasonic actuator characterized by a fixed vibrating body.