JPH06106029B2 - Ultrasonic motor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ultrasonic motor, and more particularly to an ultrasonic motor that operates as a uniaxial actuator by applying an ultrasonic signal to a piezoelectric element.

[Conventional technology]

Conventionally, as this kind of ultrasonic linear motor, there is one proposed by the present inventor (Japanese Utility Model Application No. 61-161013), which will be described with reference to FIG. 4 by using elastic members such as iron, aluminum and plastic. On one side of a certain base (11),
Two driver elements (12a) and (12b) are provided in a protruding manner. Further, the base body (11) has two piezoelectric elements (13
a) and (13b), and piezoelectric elements (14) are provided on the respective side surfaces of the driver elements (12a) and (12b). (15) is a mounting hole, (A1), (A2), (B1), (B2), and (B) are terminals of connection leads of each piezoelectric element, and (FB) is a feedback terminal.

In the ultrasonic unit having the above configuration, when a voltage in the ultrasonic region is applied between the terminals (A1) and (B), the base (1
1) and the driver elements (12a) and (12b) are bent as shown by the one-dot chain line, and the slider in which the driver element (12a) is pressed against the driver element is kicked out in the direction of arrow (M). When voltage is applied to the terminals (A1) and (B), the ultrasonic unit bends as shown by the broken line, and the driver (12b) kicks the slider in the direction of arrow (M).

When the above voltage is applied to the terminals (A2) and (B), the operation is reversed because the polarizations of the piezoelectric elements (13a) and (13b) are reversed, and the slider moves in the direction of arrow (N). Be driven to.

In this way, the sliders, which are the driven bodies, can be given arbitrary linear movements in opposite directions.

[Problems to be Solved by the Invention]

The conventional ultrasonic motor as described above has a driver (12a),
Since it is necessary to provide the piezoelectric element (14) also in (12b), it is difficult to make the ultrasonic unit thinner because the height of the ultrasonic unit becomes large, and there are many places where the piezoelectric element is attached, which makes the manufacturing work difficult. There was a problem that it became complicated.

The present invention is intended to solve the above problems, and an object of the present invention is to obtain an ultrasonic motor which can integrate a driver and a motor body into an ultra-thin structure and can be downsized. It is what

[Means for Solving the Problems]

The ultrasonic motor according to the present invention is a disk-shaped base body which is made of an elastic body and has a through hole at the center of which a slider engages, and both sides of the base body are fixed to which an electric signal in the ultrasonic region is applied. And a plate-shaped piezoelectric element.

[Action]

In the present invention, by applying an ultrasonic signal to the piezoelectric element, a composite resonance including a disc bending mode and a radial expansion / contraction mode is generated in the substrate.

〔Example〕

1 and 2 show an embodiment of the present invention. In FIGS. 1 (a) and 1 (b), the base body (1) which is an elastic body is
It has a disk shape with a through hole (1a) formed in the center,
An annular plate-shaped piezoelectric element (3) is provided on both sides of the substrate (1),
(4) are fixed respectively.

As the elastic material forming the base body (1), a material having a small elastic loss during ultrasonic vibration at a large amplitude and having a thermal expansion coefficient similar to that of a piezoelectric element made of ceramic is preferable. Steel and carbon glass are suitable.

A cylindrical slider (2), which is a movable body, is attached to the through hole (1a) of the base body (1), and the slider (2) is
As shown in FIG. 2, a notch (2a) parallel to the axis is formed to give a spring property in the radial direction.

The electrodes and connection leads provided on the piezoelectric elements (3) and (4) are not shown.

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

In this embodiment, the piezoelectric element (3) or (4)
When an ultrasonic signal is applied to the substrate, the substrate (1) is formed in such a dimensional relationship that it causes a composite resonance of the disc bending secondary mode and the radial mode. The vibration mode and operating state at this time will be described in detail. The base body (1) is composed of the piezoelectric element (3),
Alternatively, the cylindrical slider (2) is excited by (4) and simultaneously performs radial stretching vibration at the same time as the secondary disk bending mode. ) Is repeatedly pressed and released to the peripheral wall. On the other hand, due to the disc bending mode, the slider (2) will be swung left and right in the axial direction.

Now, when an electric signal is applied to the piezoelectric element (3) and the slider (2) is clamped, if the base body (1) is swung to the right in FIG. 1 (b), the slider (2) is the same. Move to the right in the figure. In the next negative half cycle,
At the same time that the clamped state of the slider (2) is released, the inner circumference of the base body (1) swings to the left, so that the slider (2) is left in the released position. Then, in the next positive half cycle, as in the previous case, the clamp and rightward movement operations are repeated in the signal application cycle, so that the slider (2)
Moves rapidly to the right.

Next, in order to move the slider (2) to the opposite left side, the piezoelectric element (4) is fixed to the substrate (1) with the same polarization polarity as the piezoelectric element (3), and a similar signal is applied. It may be applied. This is because the phase in the radial direction remains the same and only the phase of the disk secondary bending mode is reversed, so that the reversal of the slider (2) is achieved.

From the above, inversion switching of the moving direction of the slider (2) can be performed by switching the power supply to the piezoelectric elements (3) and (4), so that the drive circuit is extremely simplified and the operation of the self-excited circuit is also performed. The simplification simplifies the design.

Regarding the structure of the slider (2), it is desirable that the slider (2) is always in contact with the peripheral wall of the through hole (1a) of the base body (1) with a constant force, and various structures can be considered for that purpose.

In the above example, the second harmonic is used for the disc bending mode, but when a large output is required, the diameter of the disc is increased and the combination with the third harmonic is used. In addition, the specifications can be flexibly and variously changed according to the purpose of use such as a small size and a primary bending mode.

In order to further increase the thrust generated on the slider,
A means of driving two or three ultrasonic motors having the above-mentioned characteristics in parallel and driving them in parallel is also conceivable.

Further, as to the arrangement of the piezoelectric element in the third bending mode when the diameter is large, the piezoelectric element is independently arranged also in the antinode portion of each vibration as shown in FIGS. 3 (a) and 3 (b). In the example, only the electrodes of the piezoelectric element are divided and used by means such as screen printing.). That is, 3a is a piezoelectric element on the outer surface of the surface, 4b is a piezoelectric element on the inner surface of the surface, 4a is a piezoelectric element on the outer surface of the back surface, 3b is a piezoelectric element on the inner surface of the back surface, and the electrode 6 is divided by the electrode separation groove 7. Therefore, the piezoelectric elements are arranged independently. In addition, all the polarization is performed with the same polarity, and when the outer peripheral piezoelectric element and the inner peripheral piezoelectric element on the front and back surfaces, that is, 3a and 3b, and 4b and 4a are used in parallel when connecting as shown in FIG. 3 (c). It is possible to efficiently generate both the disk bending mode and the radial mode vibration at the same time.

〔The invention's effect〕

As is apparent from the above description, the present invention is provided with piezoelectric elements for driving on both surfaces of a disk-shaped base body having a through hole for a slider in the center thereof for excitation, and the disk bending mode and the radial direction are set. By causing the composite resonance with the mode to occur in the substrate, the slider can be moved in any direction to the left or right by switching the power supply to the two piezoelectric elements, so it is a very simple structure, highly efficient and small uniaxial There is an effect that the function as an actuator can be obtained.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 (a) is a front view, FIG. 1 (b) is a side sectional view, and FIG. 2 is a transverse sectional view of a slider. FIG. 3 shows another embodiment of the present invention, FIG. 3 (a) is a front view, FIG. 3 (b) is a side sectional view, and FIG. 3 (c) is a connection diagram. FIG. 4 is a side view of a conventional ultrasonic motor. (1) ... Base, (1a) ... Through hole, (2) ... Slider,
(3) (4) ... Piezoelectric element.

Claims (1)

[Claims] 1. A base body made of an elastic disk having a through-hole formed in the center for engaging with a body to be moved, and a plurality of base bodies fixed to both sides of the base body to which electric signals in an ultrasonic region are applied. An ultrasonic motor comprising a piezoelectric element, which causes a composite resonance of a disc bending mode and a radial expansion / contraction mode in the base.