JPH02202382A - Planar ultrasonic actuator - Google Patents

Abstract

PURPOSE:To achieve two-dimensional movement of a moving body, to simplify the structure and to reduce the thickness of an actuator by arranging a plurality of planar vibration bodies adhered with piezoelectric bodies two-dimensionally then exciting flex vibration and expanding vibration simultaneously and taking out mechanical output from a position close to the antinode of flex vibration. CONSTITUTION:A plurality of planar vibration bodies 101a, 101b are arranged two dimensionally on a base 102. The planer vibration bodies 101a, 101b adhered with piezoelectric bodies such as piezoelectric ceramic produce flex vibration in longitudinal and lateral directions, while simultaneously they produce expanding vibration and make elliptic motion at a position close to the antinode of flex vibration. By such arrangement, a moving body contacting at the position of the elliptic motion can move two-dimensionally and thereby the structure can be simplified and the thickness 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. 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 ho 712 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 disc-shaped piezoelectric bodies 15 and 16 between the 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. 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 is bonded to a flat elastic body to form a flat vibrating body,
A plurality of the flat vibrating bodies are arranged two-dimensionally, a voltage is applied to the piezoelectric body, and bending vibration and spreading vibration are simultaneously excited in the flat vibrating body. The configuration is configured to extract an output from the position.

A piezoelectric body is bonded to a working flat elastic body to form a flat plate vibrating body,
A plurality of the flat vibrating bodies are arranged two-dimensionally, a voltage is applied to the piezoelectric body, and bending vibration and spreading vibration are simultaneously excited in the flat vibrating body. To provide a thin planar ultrasonic actuator with a simple structure by causing a position to make an elliptical movement and moving a moving body in contact with the position making the elliptical movement in two dimensions.

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 same figure, 101a1101
b1 . . . is a flat plate-shaped vibrating body to which a piezoelectric material such as piezoelectric ceramic is attached.

The plate-shaped vibrating body 101 bends and vibrates in two directions, vertically and horizontally, and at the same time vibrates in a spreading manner. The flat plate vibrating body 101 is the base 1
A planar ultrasonic actuator is constructed by two-dimensionally installing a plurality of actuators on the 02.

FIG. 2 is a diagram showing the configuration and operation of the flat vibrating body 101 used in the flat ultrasonic actuator, viewed from the back.

103as bN CN d are piezoelectric bodies polarized in the thickness direction as shown by the positive and negative signs in the figure. This piezoelectric body 103at b1C%d is adhered to a flat plate-shaped elastic body 104, and constitutes a flat plate-shaped vibrating body 101. When the same AC voltage near the resonant frequency of the flat vibrating body 101 is applied to the piezoelectric body 103a1b1C%d, the flat vibrating body 101 has a vibration displacement distribution B in the figure.
It vibrates in the vertical direction as shown in . Furthermore, when an AC voltage of opposite polarity near the resonant frequency of the flat vibrating body 1°1 is applied to the piezoelectric bodies 1゜3a1d and blc, the flat vibrating body 101 oscillates as shown in the figure. Flexural vibration occurs in the lateral direction as shown by displacement distribution A. Therefore,
The two types of flexural vibrations described above can be excited depending on the driving method. Due to this bending vibration, the center portion of the piezoelectric body becomes a vibration antinode and moves up and down.

In the above example, independent piezoelectric bodies 103a1 bl C1d were used, but if electrodes are configured on one piezoelectric body as shown in Figure 2 and polarized in the thickness direction as shown in the figure, no The same is true.

FIG. 3 is a diagram illustrating the structure of the flat vibrating body 101 used in the flat ultrasonic actuator as seen from the front and another operation thereof. In the figure, a piezoelectric body 105 is bonded to one surface of an elastic body 104. Here, the piezoelectric material is polarized in the thickness direction. When an AC voltage near the resonant frequency of the flat vibrating body 101 is applied to the piezoelectric body 105, the flat vibrating body 101 spreads as shown by the dotted line in the figure and vibrates in a vibration mode. In the figure, reference numeral 106 denotes a protrusion for outputting output installed near the antinode of the bending vibration in FIG.

By making the resonant frequencies of the pinching vibration and the spreading vibration almost the same and applying an AC voltage to the piezoelectric bodies 103 and 105 at the same time, the bending vibration and the spreading vibration can be simultaneously excited in the flat vibrating body 101. Therefore, the protrusion 10B vibrates in the vertical direction due to bending vibration, and vibrates in the lateral direction due to spreading vibration.

By manipulating the phase of the voltages applied to the piezoelectric bodies 103 and 106 (for example, by setting the phase difference to +90 degrees or 190 degrees), the tip of the protrusion 106 can be caused to move in an elliptical manner.

As shown in FIG. 4, if the movable body 107 is placed in pressure contact with the tip of the protrusion 106, the movable body 107 will move in the direction of the arrow in the figure due to the elliptical locus of the tip of the protrusion 106. do. It can also be moved in the same way in a direction perpendicular to the plane of the paper.

Effects of the Invention The present invention uses bending vibration and spreading vibration of a flat plate vibrating body. Spread vibration generally has a lower resonant frequency than longitudinal vibration when the dimensions are the same, so the thickness of the flat plate that makes the resonant frequency of bending vibration the same can be made thinner, making it easier to excite pincer vibration. Therefore, it is possible to provide a flat plate type ultrasonic actuator with a simple structure and a small thickness.

[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), (b), and (C) are
A plan view showing the configuration of the flat vibrating body used in the flat ultrasonic actuator, a displacement distribution diagram showing the movement in the vertical and lateral directions, and Figure 3 shows the spreading vibration of the flat vibrating body used in the flat ultrasonic actuator. Fig. 4 is a plan view showing the operation of the planar ultrasonic actuator, Fig. 5 is an overview of the disc-type ultrasonic motor, Fig. 6 is a plan view showing the configuration for exciting the motor, and a displacement distribution diagram showing the operation. The figure is a general view of an ultrasonic linear motor, and FIG. 7 is an explanatory diagram showing the principle by which a traveling elastic wave of deflection drives a moving body. 101... Flat vibrating body, 102... Old base, 103... Piezoelectric body, 104... Elastic body, 105... Piezoelectric body, 106... Protrusion 107... Moving body. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] A flat plate vibrating body is constructed by bonding a piezoelectric body to a flat elastic body.
A plurality of the flat vibrating bodies are two-dimensionally arranged, a voltage is applied to the piezoelectric body, and bending vibration and spreading vibration are simultaneously excited in the flat vibrating body, and each of the flat vibrating bodies is A planar ultrasonic actuator that extracts mechanical output from a position near the antinode of the bending vibration.