JPH05284764A - Ultrasonic actuator using piezoelectric transformer - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic actuator having a small size and a high output by providing a vibrator to be excited by a high frequency voltage generated from a piezoelectric transformer and a moving element frictionally driven by a vibration generated at a vibrator. CONSTITUTION:A high frequency voltage generator 12 generates a high frequency voltage near a mechanical resonance frequency of a stator having a piezoelectric element 15 and a vibrator 16 by a power source 11, the voltage is applied to a primary side 13a of a piezoelectric transformer thereby to generate a high frequency voltage of higher voltage than that on the primary side at a secondary side 13b and to apply it to the element 15. The element 15 is connected to the vibrator 16, and a stator is ultrasonic-vibrated by expansion and contraction. The resonance frequency of the transformer 13 is so set as to substantially coincide with a driving frequency of an ultrasonic actuator 14, and a moving element 17 is brought into pressure contact with the vibrator 16 to be frictionally driven by an ultrasonic vibration generated at the vibrator 16. As a result, an ultrasonic actuator having a simple circuit configuration and high output is obtained and an apparatus can be reduced in size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator device for frictionally driving a moving body by ultrasonic vibration utilizing expansion and contraction of a piezoelectric element.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram of a conventional ultrasonic actuator device. The high frequency voltage generation circuit 12 generates a high frequency voltage close to the mechanical resonance frequency of the stator 18 including the piezoelectric element 15 and the vibrating body 16 by the power supply 11. The high frequency voltage of the high frequency voltage generating circuit 12 is applied to the primary side 53a of the winding transformer 53. Winding transformer 5
On the secondary side 53b of No. 3, a high frequency high frequency voltage corresponding to the ratio of the number of windings on the primary side and the secondary side is generated. Piezoelectric element 15
Is applied with a high-frequency voltage on the secondary side 53b of the winding transformer 53.

The piezoelectric element 15 is bonded to the vibrating body 16. The vibrating body 16 ultrasonically vibrates due to the expansion and contraction movement of the piezoelectric element. The moving body 17 is in contact with the vibrating body 16 at a predetermined pressure. The moving body 17 is frictionally driven by ultrasonic vibrations of standing waves or traveling waves generated in the vibrating body 16. For example, Japanese Patent Application Laid-Open No. 60-176471 discloses such a structure.

[0004]

The conventional ultrasonic actuator has a high driving voltage, and the voltage is insufficient for a battery that is normally used. Further, it is known that when the electric power is constant, the driving efficiency is better when the voltage is increased. Therefore, a booster circuit is required, and the winding transformer is used for boosting.

However, the conventional ultrasonic actuator device using the winding transformer has a problem that the structure of the winding transformer is complicated and large. Further, even if the ultrasonic actuator is downsized, there is a problem that the size of the winding transformer section causes the size of the entire apparatus to increase. Further, the step-up ratio is limited to about several times, and there is a problem that the power source efficiency is lowered when the step-up ratio is increased.

Therefore, an object of the present invention is to obtain a small-sized and high-power ultrasonic actuator by using a piezoelectric transformer in order to solve the conventional problems as described above.

[0007]

In order to solve the above problems, the present invention provides a power supply, a high frequency voltage generating circuit, and a high frequency voltage generated from the high frequency voltage generating circuit on the primary side. A piezoelectric transformer having piezoelectricity that generates a high frequency voltage higher than the primary side on the secondary side; a vibrating body having a piezoelectric element excited by the high frequency voltage generated from the secondary side of the piezoelectric transformer; By using a piezoelectric transformer, a compact, simple, and high-power ultrasonic actuator device is realized, which is composed of a moving body that is pressed against the body and frictionally driven by the vibration generated in the vibrating body.

[0008]

In the ultrasonic actuator device constructed as described above, the high frequency voltage generating circuit is
It generates a high frequency voltage close to the mechanical resonance frequency of a stator composed of a piezoelectric element and a vibrating body. By applying the high frequency voltage generated from the high frequency voltage generation circuit to the primary side of the piezoelectric transformer, a high frequency voltage higher than that of the primary side is generated on the secondary side. A high frequency voltage generated from the secondary side of the piezoelectric transformer is applied to the piezoelectric element. The piezoelectric element is joined to the vibrating body, and the expansion and contraction movement of the piezoelectric element causes the stator to vibrate ultrasonically. The resonance frequency of the piezoelectric transformer is set so as to approximately match the drive frequency of the ultrasonic actuator. The moving body is in pressure contact with the vibrating body, and is frictionally driven by ultrasonic vibrations of standing waves or traveling waves generated in the vibrating body.

As described above, by boosting the ultrasonic actuator by using the piezoelectric transformer having a resonance frequency substantially equal to the resonance frequency of the stator, a compact, simple and high output ultrasonic actuator device can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an ultrasonic actuator device of the present invention. Conventionally, the winding transformer was used as the boosting means, but in the present invention, the piezoelectric transformer 13 utilizing the piezoelectric effect is provided.

A high frequency voltage generating circuit 12 is provided by a power source 11.
Is a stator 18 including a piezoelectric element 15 and a vibrating body 16.
Generates a high frequency voltage close to the mechanical resonance frequency of. By applying the high frequency voltage generated from the high frequency voltage generating circuit 12 to the primary side 13a of the piezoelectric transformer, a high frequency voltage higher than the piezoelectric transformer primary side 13a is generated on the piezoelectric transformer secondary side 13b. The high frequency voltage generated from the secondary side 13b of the piezoelectric transformer is applied to the piezoelectric element 15. The piezoelectric element 15 is joined to the vibrating body 16, and the stretching motion of the piezoelectric element 15 causes the stator 18 to vibrate ultrasonically. Further, the resonance frequency of the piezoelectric transformer 13 is set so as to approximately match the drive frequency of the ultrasonic actuator 14. The moving body 17 is brought into pressure contact with the vibrating body 16 and is frictionally driven by ultrasonic vibrations of a standing wave or a traveling wave generated in the vibrating body 16. A pressure spring (not shown) or the like is used to press the moving body 17 and the vibrating body 16.

2 to 5 are perspective views of the piezoelectric transformer used in the present invention. The piezoelectric transformer 13 shown in FIG. 2 is a rectangular piezoelectric body. The piezoelectric transformer 13 is made of a material such as lead zirconate titanate PZT. The electrode pattern 13c polarized in the thickness direction T is used as the primary side of the piezoelectric transformer, and a high frequency voltage V1 is applied. Next, if the electrode pattern 13d polarized in the longitudinal direction L is set as the secondary side of the piezoelectric transformer, the high frequency voltage V2 is output. At this time, the ratio of the boosted voltage is proportional to the ratio of the lengths of the piezoelectric transformer primary side and the piezoelectric transformer secondary side, that is, the ratio of T and L. Further, the ratio of the currents on the piezoelectric transformer primary side and the piezoelectric transformer secondary side is proportional to the area ratio of the electrode pattern 13c and the electrode pattern 13d.

The piezoelectric transformer 13 shown in FIG. 3 is also composed of a rectangular piezoelectric body. This embodiment is different from the embodiment shown in FIG. 2 in that the electrode pattern 13c is provided in the middle portion in the longitudinal direction L. Thickness direction T
On the other hand, the polarized electrode pattern 13c is used as the primary side of the piezoelectric transformer, and the high frequency voltage V1 is applied. next,
Electrode pattern 13d polarized in the longitudinal direction L
Is the secondary side of the piezoelectric transformer, a high-frequency voltage V2 having a step-up ratio according to L / T is output.

The piezoelectric transformer 13 shown in FIG. 4 is composed of a disk-shaped piezoelectric body. In this embodiment, the piezoelectric transformer 1
It has an electrode pattern 13c smaller than the outer diameter of 3 and is polarized in the thickness direction of the disk. Here, the electrode pattern 13c is the primary side of the piezoelectric transformer, and the high frequency voltage V1
Is applied. Next, assuming that the electrode pattern 13d provided on the outer peripheral side surface is the secondary side of the piezoelectric transformer, the high frequency voltage V
2 is output.

The piezoelectric transformer 13 shown in FIG. 5 is composed of a ring-shaped piezoelectric body. In this embodiment, an electrode pattern 13c is provided on the entire inner side surface of the piezoelectric transformer 13 and is polarized in the outer peripheral direction. Here, the electrode pattern 13
A high frequency voltage V1 is applied with c being the primary side of the piezoelectric transformer. Next, if the electrode pattern 13d is provided on a part of the outer peripheral side surface and the common electrode pattern 13e is provided on the other outer peripheral side surface, the electrode pattern 13d becomes the secondary side of the piezoelectric transformer and the high frequency voltage V2 is output. It

FIG. 6 is a sectional view of the ultrasonic actuator device of the present invention. The central shaft 20 fixed to the fixed base 19.
Then, the vibrating body 16 is fixed. The piezoelectric element 15 is bonded to the lower surface of the vibrating body 16. The piezoelectric element 15 is polarized in a certain shape, and is wired from the electrode pattern of the piezoelectric element 15 to the secondary side of the piezoelectric transformer of the piezoelectric transformer 13.
Further, the primary side of the piezoelectric transformer is wired to the high frequency voltage generating circuit 12. At this time, the piezoelectric transformer 13 is arranged between the vibrating body 16 and the fixed base 19. Since the piezoelectric transformer is configured to be smaller and thinner than the outer diameter of the vibrating body 16, it is possible to reduce the size of the ultrasonic actuator device as a whole.

As mentioned above, it is desirable that the piezoelectric transformer 13 be used in a resonance state. It is a good idea to make the resonance frequency of the piezoelectric transformer approximately match the drive frequency of the stator 18 composed of the vibrating body 16 and the piezoelectric element 15. The moving body 17 contacts the protrusion 16 a of the vibrating body 16. The moving body 17 is incorporated in the central shaft 20 and the bearing 23
It is rotatably supported by. Further, the moving body 17 is brought into pressure contact with the vibrating body 16 by the pressure spring 22.

Although the piezoelectric transformer 13 is arranged between the vibrating body 16 and the fixed base 19 in this embodiment, the present invention aims to reduce the size of the entire ultrasonic actuator device by using the piezoelectric transformer. There is. The piezoelectric transformer may be arranged in a portion other than this. FIG. 7 is a circuit diagram of the ultrasonic actuator device of the present invention. The DC voltage from the power supply 11 such as a battery turns ON / OFF the switching transistor 12b at a frequency close to the resonance frequency of the piezoelectric transformer 13 and the ultrasonic actuator 14 according to the output of the oscillation circuit 12a. The high frequency voltage generated by this is applied to the primary side 13a of the piezoelectric transformer, and the piezoelectric transformer secondary side 1a is produced by the piezoelectric and electrostrictive effects.
The primary side 13 of the piezoelectric transformer is formed on the electrode pattern 13d of 3b.
A high-frequency voltage higher than a is generated. The high frequency voltage generated from the secondary side 13b of the piezoelectric transformer is applied to the piezoelectric element 15. The piezoelectric element 15 is joined to the vibrating body 16, and the expansion and contraction movement of the piezoelectric element 15 causes the stator 18 to ultrasonically vibrate and frictionally drive the moving body 17. In this embodiment, the common electrode pattern 13e of the piezoelectric transformer 13 is used.
Is set to the same potential as the joint surface between the piezoelectric element 15 and the vibrating body 16.

[0019]

As described above, the present invention applies a high frequency voltage higher than the primary side to the secondary side by applying a high frequency voltage generated from the high frequency voltage generating circuit to the power source, the high frequency voltage generating circuit and the primary side. A piezoelectric transformer having piezoelectricity for generating a voltage, a vibrating body having a piezoelectric element excited by a high-frequency voltage generated from a secondary side of the piezoelectric transformer, and a vibrating body that is pressed and contacted with the vibrating body. The following effects are obtained by being configured with the moving body that is frictionally driven by the vibration generated in the.

By making the resonance frequency of the piezoelectric transformer equal to the resonance frequency of the stator composed of the piezoelectric element and the vibrating body, a high output ultrasonic actuator can be realized with a simple circuit structure. By using the piezoelectric transformer as the boosting means, it is possible to reduce the size of the ultrasonic actuator device as a whole.

[Brief description of drawings]

FIG. 1 is a block diagram of an ultrasonic actuator device of the present invention.

FIG. 2 is a first perspective view of a piezoelectric transformer used in the present invention.

FIG. 3 is a second perspective view of the piezoelectric transformer used in the present invention.

FIG. 4 is a third perspective view of the piezoelectric transformer used in the present invention.

FIG. 5 is a perspective view of a piezoelectric transformer used in the present invention.

FIG. 6 is a cross-sectional view of the ultrasonic actuator device of the present invention.

FIG. 7 is a circuit diagram of an ultrasonic actuator device of the present invention.

FIG. 8 is a block diagram of a conventional ultrasonic actuator device.

[Explanation of symbols]

 11 Power Supply 12 High Frequency Voltage Generation Circuit 12a Oscillation Circuit 12b Switching Transistor 13 Piezoelectric Transformer 13a Piezoelectric Transformer Primary Side 13b Piezoelectric Transformer Secondary Side 13c Electrode Pattern (1) 13d Electrode Pattern (2) 13e Electrode Pattern (3) 14 Ultrasonic Actuator 15 Piezoelectric element 16 Vibrating body 17 Moving body 18 Stator 19 Fixing stand 20 Center axis 22 Pressure spring 53 Winding transformer 53a Winding transformer primary side 53b Winding transformer secondary side

Claims (2)

[Claims] 1. An ultrasonic actuator device for frictionally driving a moving body by ultrasonic vibration utilizing expansion and contraction motion of a piezoelectric element, wherein a power source and a high frequency voltage generator that is operated by the power source to generate a predetermined high frequency voltage. A circuit, and a piezoelectric transformer having a piezoelectric property to generate a high-frequency voltage higher than the primary side on the secondary side by applying the high-frequency voltage generated from the high-frequency voltage generating circuit to the primary side, A vibrating body having a piezoelectric element that is excited by a high-frequency voltage generated from the secondary side of the piezoelectric transformer, and being brought into pressure contact with the vibrating body and being frictionally driven by the vibration generated in the vibrating body. An ultrasonic actuator device comprising: a moving body. 2. The ultrasonic actuator device according to claim 1, wherein a drive frequency of the piezoelectric transformer is equal to a drive frequency of a stator including the vibrating body and the piezoelectric element.