JPH01298968A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To provide high efficiency and small size by providing driving piezoelectric elements on both side faces of a disclike base having a through hole for a slider at its center, and exciting it. CONSTITUTION:A base 1 of an elastic material is formed in a disclike state formed with a through hole 1a at its center, and annular platelike piezoelectric elements 3-4 are secured to both side faces of the base 1. A cylindrical slider 2 to be moved is engaged with the hole 1a of the base 1, a cutout 2a parallel to the axis is formed at the slider 2 to provide radial spring characteristic. Thus, the base 1 can simultaneously generate a bending mode and a radial mode of the elements 3-4 for forming a disclike bimorph, and the slider 2 can be axially driven.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic motor, and in particular, to an ultrasonic motor that operates as a uniaxial actuator by applying an ultrasonic signal to a pressure mechanism element. .

[Conventional technology]

Conventionally, this type of ultrasonic linear motor has been proposed by the present inventor (Utility Application No. 61-161013), and this will be explained with reference to FIG. 4. Two driving elements (12a) and (12b) are provided protruding from the negative side of the base (11). In addition, two piezoelectric elements (13a) and (13b) for bending mode are mounted on the base (11), and a drive element (1) is mounted on the base (11).
A piezoelectric element (14) is provided on each side of 2a) and (12b). (15) is the mounting hole, (AI),
(A2), (B1), (B2), and (B) are terminals of connection leads of each piezoelectric element, and (FB) is a feedback terminal.

In the ultrasonic unit configured as described above, when voltage in the ultrasonic range is applied between terminals (1) and (B), the substrate (1
1) and the driver elements (12a) and (12b) are bent as shown by the - dotted chain line, and the driver element (12a) kicks out the slider pressed against the driver element in the direction of the arrow (M). When ○ Narita is applied to the terminals (AI) and (B), the ultrasonic unit bends as shown by the broken line, and the driver (
12b) kicks out the slider in the direction of arrow (M).

When the above voltage is applied to the terminals (A2) and (B), the polarization of the piezoelectric elements (13a) and (13b) is opposite, so the operation is reversed, and the slider is driven in the direction of arrow N. be done.

In this way, the slider, which is the driven body, can be arbitrarily given linear movement in opposite directions.

[Problem to be solved by the invention]

The conventional ultrasonic motor as described above has a drive element (12a)
, (12b), it is necessary to provide the piezoelectric element (14), so the height of the ultrasonic unit becomes large, making it difficult to make it thinner, and there are many places where the piezoelectric element is pasted, which makes manufacturing work difficult. There were problems such as complexity.

This invention is an attempt to solve the above-mentioned problems, and aims to provide an ultrasonic motor that can integrate the drive element and the motor body to make it extremely thin and compact. [Means for Solving the Problems] An ultrasonic motor according to the present invention includes a disc-shaped base made of an elastic body and having a through hole in the center with which a slider engages, and this base. It consists of plate-shaped pressure-transmission elements fixed to both sides of the plate and to which electrical signals in the ultrasonic range are applied.

[Effect]

In this invention, by applying an ultrasonic signal to the piezoelectric element, a complex resonance consisting of a disk bending mode and a radial expansion/contraction mode is generated in the base body.

〔Example〕

Figures 1 and 2 show an embodiment of the present invention, and Figure 1 (
In a) and (b), the base (1) made of an elastic body has a disk shape with a through hole (la) formed in the center,
Annular plate-shaped piezoelectric elements (3) and (4) are disposed on both sides of the base (1).
) are fixed respectively.

The elastic material forming the base body (1) is preferably a material that has low elastic loss during vibration in the ultrasonic range with large amplitude and has a coefficient of thermal expansion comparable to that of a piezoelectric element made of ceramic, such as nickel. Suitable materials include steel and carbon glass.

A cylindrical slider (2), which is a moving object, is attached to the through hole (1a) of the base body (1), and the slider (2) has a cut parallel to the axis as shown in FIG. A notch (2a) is formed to provide springiness in the radial direction.

In addition, the electrodes and connection IJ provided on the piezoelectric elements (3) and (4)
− code is omitted from illustration.

Next, the operation will be explained. The disk-shaped base (1) can simultaneously generate a bending mode and a radial mode by the piezoelectric elements (3) and (4) forming a disk bimorph.

In this embodiment, the piezoelectric element (3) or (4)
The base body (1) is formed in a dimensional relationship such that when an ultrasonic signal is applied to the base body (1), a composite resonance of a second-order disk bending mode and a radial mode occurs. To explain in detail the vibration state and poor operation state at this time, the base body (1) has a piezoelectric element (3),
Alternatively, the cylindrical slider (2) is excited by (4) and is undergoing radial stretching vibration at the same time as the second disk bending mode. ) is repeatedly pressed onto and released from the peripheral wall. on the other hand,
Due to the disk bending mode, the slider (2) is axially swung left and right.

Now, when an electric signal is applied to the piezoelectric element (3) and the slider (2) is clamped, the base body (1) moves as shown in FIG.
), the slider (2) moves to the right in the figure. In the next negative half cycle, the inner periphery of the base body (1) swings to the left at the same time that the clamped state of the slider (2) is released, so that the slider (2) is left in the released position. Then, in the next positive half cycle, the clamping and moving to the right operations are repeated at the signal application period, as before, so the slider (2) rapidly moves to the right.

Next, to move the slider (2) to the opposite left, fix the polarization of the piezoelectric element (4) to the same as that of the piezoelectric element (3), and send the same signal. Just apply it. This is because while the radial phase remains the same, only the phase of the disk secondary bending mode is reversed, so that the slider (2) is inverted.

From the above, the reversal of the moving direction of the slider (2) can be achieved by simply switching the power supply to the piezoelectric elements (3) and (4), which greatly simplifies the drive circuit and improves the operation of the self-exciting circuit. This simplification makes the design easier.

The structure of the slider (2) is that the through hole (la) of the base (1)
It is desirable that the ring be in constant inner contact with the peripheral wall with a constant force, and various structures can be considered for this purpose.

Note that the above embodiment uses the second harmonic in the disk bending mode, but if a large output is required, the diameter of the disk may be increased and combination with the third harmonic, In addition, it is possible to make it compact and have various specifications such as primary bending mode that can be elastically changed depending on the purpose of use.

In addition, in order to further increase the thrust generated in the slider,
It is also conceivable to drive two or three ultrasonic motors having the same characteristics as described above in parallel.

Furthermore, the arrangement of the piezoelectric elements in the third bending mode when the diameter is large is as shown in FIGS. 3(a) and 3(b). (The piezoelectric element is used by dividing only the electrodes by means such as screen printing.)

That is, 3a is a piezoelectric element on the outer periphery of the front surface, 4b is a piezoelectric element on the inner periphery of the front surface, 4a is a piezoelectric element on the outer periphery of the back surface, and 3b is a piezoelectric element on the inner periphery of the back surface. The electrode 6 is divided, and therefore the piezoelectric element can handle both the disk bending mode and the radial mode if the piezoelectric element and the inner circumferential ring element, that is, 3a and 3b1 and 4b and 4a are used in parallel. Vibrations can be generated simultaneously and efficiently.

〔Effect of the invention〕

As is clear from the above description, the present invention provides piezoelectric elements for driving on both sides of a disk-shaped base having a through hole for a slider in the center, and excites the disk bending mode and radial direction. By creating complex resonance with the mode in the base, the slider can be moved in any direction left or right by switching the power supply to the two pressure generating elements, resulting in an extremely simple structure, high efficiency, and small size. This has the effect of providing a function as a single-axis actuator.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the present invention, and Figure 1 (
FIG. 2A is a front view, FIG. 2A is a side sectional view, and FIG. 2 is a cross-sectional view of the slider. FIG. 3 shows another embodiment of the present invention, in which FIG. 3(a) is a front view, FIG. 3(b) is a side sectional view, and FIG. 3(C) is a wiring diagram. FIG. 4 is a side view of a conventional ultrasonic motor. (1)...Base, (1a)...Through hole, (2)...
・Slider, (3) (4)...pressure mechanism element.

Claims (1)

[Claims] It includes a base made of an elastic disc with a through hole formed in the center for engagement of a moving object, and a plurality of piezoelectric elements fixed to both sides of the base to which electrical signals in the ultrasonic range are applied. An ultrasonic motor that generates a composite resonance of a disk bending mode and a radial expansion/contraction mode in the base body.