JPH0470875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a piezoelectric drive device, such as a reciprocating type or a rotary type, using a piezoelectric element.

[Background technology]

Conventionally, as an ultrasonic motor using piezoelectric elements,
There is one shown in Japanese Patent Publication No. 59-037672.
In this method, a piezoelectric element is attached to a vibrating body to generate longitudinal vibration, and a driving piece with an inclination is formed at the tip of the vibrating body. By contacting the disk, the disk is rotated by frictional force.

However, with this conventional structure, the direction of rotation is determined by the direction of inclination of the drive piece, and the tip of the drive piece is thin, so wear is large due to friction, and there are problems with longevity.

Further, as another conventional example, there is one shown in Japanese Patent Application Laid-Open No. 148682/1982. In this example, the entire vibration of the piezoelectric element is transmitted to the vibrating body, and by vibrating one waveform with a 90° phase shift from the other waveform, a traveling wave is generated on the surface of the vibrating body, and the rotor above it is generated. By making contact, the rotor is rotated by wear.

According to this example, reversal is possible, but it is necessary to always apply energy to the entire vibrator, and moreover, it is necessary to absorb vibrations on the surface of the piezoelectric element opposite to the surface attached to the vibrating body. Therefore, energy loss is large and efficiency is difficult. In addition, in forming a linear motor, unless a measure is taken to circulate the traveling waves, the energy loss is too large to be a problem, and the circulation method is also extremely difficult.

In addition, all of these conventional structures are driven using friction, which poses problems in terms of service life and generation of abrasion powder.

[Objective of the Invention] The present invention aims to provide a piezoelectric drive device that can efficiently obtain mechanical driving force with low power consumption, has no contact points, has a long life, and is capable of stable driving. purpose.

[Disclosure of the invention]

The piezoelectric drive device of the present invention, to be described with reference to the reference numerals in the figures, is a piezoelectric drive device having a vibrator 1, a power supply device 5, and a driven member 6, the vibrator 1 having elasticity. It is formed into either a U-shape or an open-shape shape by using a material, and the cross-sectional shape of the pair of opposing sides 3 is each approximately rectangular, and each has piezoelectric element portions 4 on at least two adjacent sides. The power supply device 5 applies a high frequency voltage to adjacent piezoelectric element portions 4 of each of the opposing sides 3 with a phase difference, thereby causing the maximum amplitude portion of each of the opposing sides 3 to move in a circular or elliptical manner. The driven member 6 faces the opposite side 3 of the vibrator 1 with a constant distance therebetween, and the maximum amplitude part of the opposite side 3 of the vibrator 1 and the driven member 6 One of the facing side 3 and at least a part of the facing part is made of a permanent magnet 7, the other is made of a magnetic material, and either the driven member 6 or the vibrator 1 is movable. .

The piezoelectric element portion may be formed by adhering a piezoelectric element to the vibrator, or may be formed by forming the vibrator from a piezoelectric material and forming electrodes directly on this piezoelectric material. It may be hot.

According to the configuration of the present invention, a high frequency voltage with a phase difference is applied to the piezoelectric element portions provided on two adjacent sides of each opposing side of each vibrating body, so that the maximum amplitude point of each opposing side is a circle or an ellipse. exercise. Either the driven member or the vibrator is driven by a change in the magnetic flux between one of the opposing sides and the driven member, and a mechanical driving force is obtained.

In this case, since each vibrating body is U-shaped or square-shaped, both opposing sides resonate with each other and a large amplitude can be obtained. Therefore, electrical energy can be efficiently converted into mechanical driving force. In addition, since the resonance of the vibrator occurs in a non-vibrating state at the base end where two opposing sides are continuous, by using the base end as a support part, vibration can be prevented by the support. This also results in high efficiency. Furthermore, since there are parts of the vibrator that do not vibrate, either the vibrator or the driven member can be used as a fixed side or as a movable side. Further, since the vibrator has two opposing sides and changes in magnetic flux occur at these parts, there are many driving points, and since there is no contact, there is no wear and stable driving is possible.

Embodiment A first embodiment of the present invention will be described based on FIGS. 1 to 5. This piezoelectric drive device is an example applied to a linear motor, and a vibrator 1 is formed by a vibrating member 2 made of a metal elastic material. That is, this piezoelectric drive device is formed in a U-shape, and each of the pair of opposing sides 3 has a rectangular cross-sectional shape, and a piezoelectric element portion 4 is formed by pasting piezoelectric elements on two adjacent sides of each opposing side 3. A vibrator 1 is formed, and when a predetermined high-frequency voltage is applied to this piezoelectric element part 4, the opposing sides 3 resonate by bending vibration, and the adjacent piezoelectric element parts 4 of each opposing side 3 have a phase difference. A power supply device 5 that applies a high frequency voltage and each one of each opposing side 3 of the vibrator 1
A permanent magnet 7 provided at the tip of the surface and this permanent magnet 7
and a driven member 6 made of a magnetic material that faces each other at a constant interval, and the maximum amplitude point of the opposing side 3 of the vibrator 1 moves in a circular or elliptical manner, whereby the driven member 6 or the vibrator 1 Some are driven by either one of the following.

The vibrating member 2 is made of a constant elastic material such as Erinba, but if accuracy and large amplitude are not required, general steel material, other metals, ceramics, etc. may also be used. If the vibrating member 2 is a magnetic material, the amount of change in magnetic flux will be large and the driving efficiency will be improved. Although the cross-sectional shape of each opposing side 3 of the vibrator 1 is rectangular, each corner may be chamfered to have an octagonal cross-sectional shape, or the corners may be rounded instead of chamfered. In short, the opposing sides 3 only need to have a cross-sectional shape having four sides adjacent to each other at right angles. The base end 2a of the vibrator 1 has a length that does not affect vibration even if it is fixed, and is fixed to a base 21 as shown in FIG. 2. The driven member 6 is supported by guide means (not shown) so as to be movable forward and backward relative to the base 21 in the direction of arrow P in FIG. The driven member 6 is
Point X and point Y, which are the tips of each face on which the permanent magnet 7 of the opposing side 3 is arranged (Fig. 4B)
They are arranged at a constant interval G (Fig. 2).

The power supply device 5 has a high frequency power supply 8 and a 90° phase shifter 9, as shown in FIG _.
~4 ₄ ), apply a voltage as shown in the same figure. The + and - signs in the figure indicate the polarization direction.

Operation Each piezoelectric element portion ₄ on the two opposing sides 3 of the vibrator 1
4 ₄ , when a high frequency voltage is applied and excited by the power supply device 5 of FIG. 5, each opposing side 3 vibrates in the vertical and horizontal directions in accordance with the excitation of the respective piezoelectric element portions 4 ₁ to _{4 4} . At this time, when a voltage whose phase is delayed by 90° than that of the piezoelectric element parts 4 ₁ and 4 ₃ is applied to the piezoelectric element parts 4 ₂ and 4 ₄ , the X
The point Y moves in a circular or elliptical orbit as shown in FIG. 4C. Therefore, when the driven members 6 are arranged on one surface of the permanent magnet 7 on the opposing side 3 at a constant interval G, the driven members 6 move linearly in the direction of the arrow P. The flatness of the elliptical orbits at the X point and Y point can be adjusted by the difference in bending rigidity depending on the bending direction of the opposing sides 3, the magnitude of the voltage applied to each piezoelectric element part 4 ₁ to 4 ₄ , the phase difference, etc.

If a voltage with a phase advanced by 90° is applied to the piezoelectric elements 4 ₂ and 4 ₄ , the piezoelectric elements 4 2 and 4 4 will draw a trajectory opposite to that shown in FIG.

It operates in this way, but since each vibrator 1 is U-shaped, its opposite sides 3 resonate with each other,
Large amplitude can be obtained. Therefore, electrical energy can be efficiently converted into mechanical driving force. Also,
Since the resonance of the vibrator 1 is performed in such a way that the base end 2a where the two opposing sides 3 are continuous is in a non-vibrating state as shown in FIG. 3, by using the base end 2a as a support part, Vibration is not hindered by the support, which also provides high efficiency. Also,
Since there are parts of the vibrator 1 that do not vibrate in this way, either the vibrator 1 or the driven member 6 can be used as a fixed side or a movable side.

In this way, since the vibrator 1 is caused to resonate in a non-contact manner, it can be used with a large amplitude, and since it is driven in a non-contact manner, it is free from wear and has a long life.

In the first embodiment shown in FIGS. 1 to 5, the permanent magnet 7 is provided on the vibrator 1 side and the driven member 6 is made of a magnetic material. A permanent magnet may be used, and the vibrator 1 may be simply made of a magnetic material. Note that the magnetic body includes a permanent magnet, and both the driven member 6 and the vibrator 1 may be made of permanent magnets.

In each of the embodiments described below in FIG. 6, either the driven member or the vibrator may be a permanent magnet. In short, it is only necessary that one of the maximum amplitude portion of the opposing side of the vibrator and at least a portion of the portion of the drive member facing the opposing side be a permanent magnet, and the other be a magnetic material.

FIG. 6 shows an embodiment in which a single U-shaped vibrator 1 is used as a rotating motor. The driven member 16 is formed into a disk shape, and its shaft 18 is connected to the base 1 with a bearing 19.
It is rotatably supported at 7. The vibrator 1 made of a magnetic material is fixed to the vertical side of the base 17 at its base end 2a. The two opposing sides 3 of the vibrator 1 are arranged in parallel with a driven member 16 made of a permanent magnet at a constant interval, and their tips are located at the outer peripheral edge of the driven member 16. The two opposing sides 3 are vibrated so as to move circularly in the same direction, and the driven member 16 is rotated. The rest is the same as the first embodiment.

FIGS. 7 and 8 show two U-shaped oscillators 1 made of magnetic materials arranged in a superimposed manner with an interval between them, and a driven member 6 made of a permanent magnet between the upper and lower oscillators 1. ' are arranged at constant intervals. The upper and lower vibrators 1 are stacked on top of each other at their base ends 2a with a spacer (not shown) interposed therebetween. Note that each vibrating body 2 may be individually attached to a base (not shown) without using a spacer. Each point m, n, p, q on the opposite side 3 of the vibrator 1 is vibrated by the piezoelectric element part 4 as shown in FIG. 8, and the driven member 6'
is driven in a straight line by circular or elliptical motion of each opposing side 3 on both the upper and lower surfaces. In this case, two oscillators 1
Since the motor is driven by the same amount of power, a higher output driving force can be obtained, and the operation is more stable. The rest is the same as the first embodiment. The vibrating members 2 may be integrated with each other at the base end portion 2a' as shown in FIG. 9 to form one vibrator 1'.

Fig. 10 shows an example in which two U-shaped transducers 2 are oriented in opposite directions to form an integrated H-shaped transducer 1''. use That is, a shaft 31 is fixed to the center of a vibrator 1'' made of a magnetic material, the shaft 31 is fixed to a base 37, and a driven member 36 made of a disk-shaped permanent magnet on which a bearing 38 is mounted is fixed to the center of the vibrator 1''. 31 so as to be rotatable, and the tips of the four opposing sides 3 are arranged at a constant interval on the outer peripheral edge of the driven member 36.
Then, each piezoelectric element part 4 provides four opposing sides 3.
The driven member 36 rotates by bending the tips of the two members so that they move circularly in the same direction, thereby forming a rotary motor. The rest is the same as the first embodiment.

FIGS. 12 to 14 show an embodiment using a vibrator 101 consisting of one square-shaped vibrating member 102. FIG. In this example, when the vibration is in the first mode, the center point of the opposite side 103 moves in a circle or an ellipse, and when the driven member 106 is opposed to the plane part with a constant interval, the center point moves in a circular or elliptical manner. Alternatively, the driven member 106 will move due to the elliptical motion. The driving member 106 can be directly supported so as to be movable forward and backward in the direction of arrow Q to form a linear motor, or the driven member 106 can be supported rotatably to form a rotary motor. In this example, the vibration in the first mode is as shown in FIG. 14. 107 is a base. The method of polarizing the piezoelectric element portion 4 is the same as described above. Other compositional effects are the first
This is similar to the embodiment.

FIG. 15 and FIG. 16 show two rectangular-shaped oscillators 101 made of magnetic material arranged in a superposed manner with a spacer 105 in between, and a constant spacing maintained between the oscillators 101 made of permanent magnets. The driven member 106 is arranged so as to be linearly movable in the direction of arrow Q. The piezoelectric element portion 4 is attached to the four opposing sides 103 so as to move as shown in FIG. The rest is the same as the first embodiment.

In each of the above embodiments, the piezoelectric element portion 4 was attached only to two adjacent sides of the opposing sides 3, 103, but the piezoelectric element portion 4 may be attached to the third side or the fourth side. .

FIGS. 17 to 19 each show the vibrator 401
401'' is formed of a piezoelectric material, and an embodiment in which piezoelectric element portions 404 to 404'' are directly formed is shown. As the piezoelectric material, a piezoelectric ceramic such as PZT (lead zirconium titanate porcelain) or a composite piezoelectric material of piezoelectric ceramic and plastic is used.
Although these piezoelectric materials do not have magnetism, they are made of a mixture of plastic and magnetic materials mixed with piezoelectric ceramics, and the vibrators 401 to 40
1'' may have characteristics as a magnetic material.In addition, instead of mixing magnetic materials, each electrode provided on the vibrators 401 to 401'' as described later may be formed of a magnetic material, and the vibrator 401 to 401'' may have an effect as a magnetic material.

In the example shown in FIG. 17, a vibrator 401 is formed by one U-shaped vibrating member 402, and piezoelectric element portions 404 that utilize the longitudinal effect of the first mode are provided on two adjacent sides of opposing sides 403 of a rectangular cross-sectional shape. is directly formed. Each piezoelectric element portion 404 has an opposing side 40
A plurality of electrodes a ₁ , b ₁ perpendicular to the longitudinal direction of 4 are arranged in the longitudinal direction, and every other electrode a ₁ , b ₁
Two electrode sets a and b are formed by connecting them at connection parts a ₂ and b ₂ . That is, the electrodes a ₁ and b ₁ are provided in an interdigital pattern in the lateral direction. Electrode group a in these two sections,
Polarization treatment is performed by applying a DC voltage between b. + and - in the figure indicate the polarity of polarization. When the polarization process is performed in this way and a high frequency voltage is applied by a power supply device similar to the power supply device 5 in FIG. 5, the opposite side 403 undergoes expansion and contraction mainly due to the piezoelectric longitudinal effect of the piezoelectric element portion 404, and performs bending vibration. . Further, if a voltage having a phase difference is applied to the piezoelectric element portions 404 on two adjacent sides of the opposing side 403, the tip of the opposing side 403 performs circular or elliptical motion. Note that each piezoelectric element portion 404 may have only two electrodes a ₁ and b ₁ .

In the example of FIG. 18, two adjacent sides of the opposite side 403'
A piezoelectric element portion 404' utilizing a piezoelectric transverse effect is provided on the surface.
was formed. In this example, electrodes c, d
are arranged in the form of interdigitated fingers in the vertical direction. That is, each piezoelectric element portion 404' forms an interdigital electrode consisting of two or many parallel electrodes c and d along the longitudinal direction of the opposing side 403'. A DC voltage is applied between the electrodes c and d to perform polarization treatment. + and - in the figure indicate the polarity of polarization. If a high frequency voltage is applied between electrodes c and d after polarization treatment in this way, the opposite side 40
3' causes the piezoelectric element portion 404' to expand and contract due to the piezoelectric transverse effect, thereby performing bending vibration. Other structural functions are similar to the embodiment shown in FIG. 17.

The example shown in FIG. 19 is an embodiment in which the vibrator 401'' utilizes the second-order bending mode of one rhombic vibrating member 402'', and each of the two adjacent sides of each opposing side 403'' has a piezoelectric Piezoelectric element section 404″ using transverse effect
Two pieces each were formed. That is, located on both sides of the central part in the longitudinal direction on the opposing sides 403'',
Four electrodes e and f are provided parallel to each other along the longitudinal direction, and a set of two parallel electrodes is formed, and a DC voltage is applied between these two electrodes to perform polarization processing. At this time,
The first set of electrodes e, f and the second set of electrodes e, f are polarized with opposite polarities and a high frequency voltage of the same phase is applied, or the polarization is in the same direction and a high frequency voltage of opposite polarity is applied. do.

The vibrator 401 in FIGS. 17 to 19
401'' and the driven members 6, 36, etc. are combined in the same manner as in each of the above embodiments, a reciprocating type or rotary type piezoelectric drive device is constructed.

Note that, similarly to the examples shown in FIGS. 17 to 19, even when the vibrator is composed of a plurality of vibrating members as in the examples shown in FIGS. 9, 10, and 15, the vibrator is piezoelectric. It is also possible to form the electrode directly by forming the material.

Also, as in the case of pasting, the opposite sides 403 to
Piezoelectric element parts 404~ on 3 or 4 sides of 403''
404'' may also be provided.

In this way, the vibrators 401 to 401'' are made of piezoelectric material such as piezoelectric ceramic.
By directly forming the piezoelectric element portions 404 to 404'' on the 01'', it is possible to omit pasting the piezoelectric elements, and since there is no adhesive layer, the performance can be stabilized. Also,
Unlike those in which piezoelectric elements are pasted, there is no variation in characteristics due to pasting errors, etc., and productivity is improved by reducing man-hours. Furthermore, it is possible to create a piezoelectric drive device that is complex in shape, and is advantageous in terms of cost and performance.

〔Effect of the invention〕

In the piezoelectric drive device of the present invention, since each vibrating body is U-shaped or square-shaped, both opposing sides resonate with each other, and a large amplitude can be obtained. Therefore, electrical energy can be efficiently converted into mechanical driving force. In addition, since the resonance of the vibrator occurs in a non-vibrating state at the base end where two opposing sides are continuous, by using the base end as a support part, vibration can be prevented by the support. This also results in high efficiency. Furthermore, since there are parts of the driven member that do not vibrate, either the vibrator or the driven member can be used as either a fixed side or a movable side.

Furthermore, since the vibrator resonates in a free state without contact with the driven member, a large amplitude can be obtained. Moreover, since it is a non-contact drive, there is no wear, resulting in a long life and stable drive.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a cutaway side view thereof, FIG. 3 is an explanatory diagram of its vibration mode, FIG. Figure B is a front view of the same, Figure 4C is an explanatory diagram of its operation, Figure 5 is a block diagram of the power supply device, and Figures 6A and B are a plan view and a cutaway side view of another embodiment, respectively. Figure, Figure 7A
7B is a plan view of still another embodiment, FIG. A perspective view of a vibrator according to another embodiment, FIGS. 11A and 11B are a broken plan view and a longitudinal side view of the whole, respectively, FIG. 12 is a perspective view of still another embodiment, and FIG. 13 is a broken side view thereof. 14 is an explanatory diagram of the vibration mode, FIG. 15 is a perspective view of a vibrator according to another embodiment, FIG. 16 is a perspective view of the entire vibrator, and FIGS. 17 to 19 are mutually related to each other. FIG. 7 is a perspective view of a vibrator in yet another different embodiment. 1,1',1'',101,401~401''...
Vibrator, 2, 102, 402, 402', 40
2″……Vibration member, 3,103,303,30
3', 303''...opposite side, 4, _{4 1} to 4 ₄ , 40
4,404',404''...Piezoelectric element section, 5...Power supply device, 6,6',16,106,206,30
6... Driven member, 7... Permanent magnet.

Claims (1)

[Scope of Claims] 1. A piezoelectric drive device having a vibrator 1, a power supply device 5, and a driven member 6, wherein the vibrator 1 is made of an elastic material and has a U-shape and a mouth-shape. The power supply device 5 is formed in any shape, and each of the pair of opposing sides 3 has a substantially rectangular cross-sectional shape, and each has a piezoelectric element portion 4 on at least two adjacent sides, and the power supply device 5 By applying a high frequency voltage to adjacent piezoelectric element portions 4 of sides 3 with a phase difference, the maximum amplitude portion of each of the opposing sides 3 is caused to move in a circular or elliptical manner, and the driven member 6 is moved by the vibration. It faces the opposite side 3 of the vibrator 1 with a constant interval, and the maximum amplitude part of the opposite side 3 of the vibrator 1 and at least one of the parts of the driven member 6 facing the opposite side 3 A piezoelectric drive device in which either the driven member 6 or the vibrator 1 is movable. 2. The piezoelectric drive device according to claim 1, wherein the piezoelectric element portion is formed by adhering a piezoelectric element to the vibrator. 3. The piezoelectric drive device according to claim 1, wherein the vibrator is made of piezoelectric ceramic, and the piezoelectric element portion has drive electrodes formed directly on the piezoelectric ceramic. 4. The piezoelectric drive device according to claim 2 or 3, wherein the vibrator includes one vibrating member. 5. The piezoelectric drive device according to claim 2 or 3, wherein the vibrator includes two vibrating members. 6. Claims in which the two vibrators are arranged in a superimposed manner with a predetermined spacing between them, and the driven member faces two pairs of opposing sides of the vibrator with a constant spacing therebetween. The piezoelectric drive device according to item 5. 7. The two vibrators are arranged in an H shape, with each vibrator having a U-shape, and the driven member maintains a constant distance from two pairs of opposing sides of the vibrator. A piezoelectric device according to claim 5, which is opposed to the other. 8. The piezoelectric drive device according to claim 2 or 3, wherein the driven member is formed into a flat plate shape, and either the driven member or the vibrator is linearly driven. 9. The piezoelectric drive device according to claim 2 or 3, wherein the driven member is formed in a disk shape, and either the driven member or the vibrator is rotationally driven. 10. The piezoelectric drive device according to any one of claims 1 to 9, wherein the vibrator is made of a magnetic material. 11. The piezoelectric drive device according to claim 10, wherein the driven member is a permanent magnet.