JPH01264582A - Ultrasonic linear motor - Google Patents

Abstract

PURPOSE:To move a slider smoothly by forming a projection to a contact section with the slider of the top face of an elastic body. CONSTITUTION:A vibrator A is composed of an elastic body 40 shaped to a U shape by an elastic member and piezoelectric elements 41-43 and the like. A projection 46 is formed to the top face of the elastic body 40 in the rectangular direction to the direction of movement of a slider B. Even when the top face of the elastic body 40 as a contact surface with the slider B is polished and flatness is not kept with high accuracy, the slider B is shifted in the right direction or the left direction when the slider B is pressure-welded to the projection 46 under the state of vibrations by a proper pushing means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic linear motor using an electro-mechanical transducer such as a piezoelectric element as a vibration source.

[Conventional technology]

Recently, ultrasonic motors have been in the spotlight as new motors that can replace conventional electromagnetic motors. This ultrasonic motor is not only new in principle, but also has the following advantages over conventional electromagnetic motors.

■ Thin, lightweight, and compact.

■ Low speed and high torque can be obtained without gears.

■ The component configuration is simple and highly reliable.

■ There is no exchange of magnetic influence.

■ There is no backlash and positioning is easy.

In order to take advantage of these advantages, various applied techniques are being researched.

Ultrasonic motors can be broadly divided into annular and linear types. FIG. 11 is a diagram showing a conventional example of a linear type ultrasonic motor. By vibrating the Langevin type piezoelectric vibrator 1 on the left side of the figure and bringing the tip of the horn 2 into contact with the propagation rod 3 made of an elastic body, a bending traveling wave is generated in the propagation rod 3. This bending traveling wave propagates rightward in the propagation rod 3 as shown by the broken line arrow. This traveling wave then excites the Langevin type piezoelectric vibrator 5 via a similar horn 4 attached to the right end of the propagation rod 3. At this time, L in the diagram
and R are appropriately selected and impedance matched to absorb all the energy of this traveling wave. In this way, the traveling wave will always travel steadily from the left to the right.

Now, when the slider 6 is held in pressure contact with the surface of the propagation rod 3 where such a bending traveling wave is generated with a certain pressing force, the slider 6 moves to the right in the figure as shown by the solid line arrow. .

FIG. 12 is a perspective view schematically showing the relationship between the bending traveling wave of the propagation rod 3 and the slider 6. In the figure, 33 is an elastic body corresponding to the propagation rod 3, and 66 is a moving body corresponding to the slider 6. As shown in FIG. 11, the mass point P of the elastic body 33 draws an elliptical locus. Therefore, when the movable body 66 is brought into pressure contact with the elastic body 33 which is drawing this elliptical locus under a predetermined pressure, the movable body 66 is driven in a direction opposite to the traveling direction of the traveling wave.

However, with the ultrasonic linear motor configured as described above, the entire device becomes large, and the traveling wave is transmitted through the propagation rod.
There were problems such as poor efficiency as it was absorbed at the other end and converted into thermal energy.

[Problem to be solved by the invention]

Therefore, the present inventors proposed an ultrasonic linear motor having the following configuration.

FIG. 13 is a configuration diagram of an ultrasonic linear motor already proposed by the present inventors. A is a vibrator, B is a slider, and C is a drive control system.

The vibrator A has plate-shaped piezoelectric elements 11 and 12 fixed to two perpendicular side walls of an elastic body 10 formed into a U-shape using an adhesive or the like.

Note that the piezoelectric element 11 is polarized in the vertical direction in the figure, and the piezoelectric cord 12 is polarized in the horizontal direction. The elastic body 10 is fixed to the base 13 with screws 14. Further, lead wires 15 and 16 are taken out from the electrode surfaces of the piezoelectric elements 11 and 12, and a drive control voltage is applied through these.

That is, the AC signal output from the high frequency power source of the drive control system C is amplified by the power amplifier 18 on the one hand, and then applied to the piezoelectric element 11 . On the other hand, when the switch 19 is set to the a side, a high frequency voltage whose phase is shifted by -900 by the "-90° phase shifter" 31 is applied to the piezoelectric element 12 via the amplifier 20. Then, the mass point on the elastic body lo undergoes elliptical vibration as shown in FIG. 14(a). At this time, if the slider B is pressed against the upper surface of the elastic body 1o,
Move to the right in the diagram. When the switch 19 is set to the b side, the phase is changed to +90° by the "+90° phase shifter" 32.
The shifted high frequency voltage is applied to the piezoelectric element 1 via the amplifier 20.
2.

Then, the mass point on the elastic body 1°0 vibrates elliptically as shown in FIG. 14(b). At this time, when the slider B is pressed against the upper surface of the elastic body 10, the slider B moves to the left in the figure. Note that the drive control system C includes a high frequency power source 17.
By operating the switch 19, the output signal of "-
90° phase shifter" 31 or "+90° phase shifter" 32, but as shown in FIG.
If it is set to the b side, it may be led directly to the amplifier 20, and if it is set to the b side, it may be led to the r180' phase shifter 21.

Using such a drive control system, the piezoelectric elements 11 and 1
When a voltage is applied to oscillator 2, tilted reciprocating vibration is excited in oscillator A.

However, although the ultrasonic linear motor described above is suitable for downsizing the device and improving energy conversion efficiency, it has the following problems.

The amplitude width of the mass point performing elliptical vibration or tilted reciprocating vibration on the top surface of the vibrator A is only about a few p, so in order to move the slider B smoothly, the top surface of the vibrator A must be moved with high precision. It is necessary to polish to improve flatness. In addition, when using a large number of transducers A bent in series, the heights of the transducers A must be precisely matched.
Requires very difficult adjustments.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ultrasonic linear motor that can smoothly move a slider without the need for highly accurate polishing of the upper surface of the vibrator or highly accurate height adjustment between the vibrators. be.

[Means to solve the problem]

Therefore, the present invention has taken the following measures in order to solve the above problems and achieve the objectives. That is, a first piezoelectric element is bonded to the first surface of the elastic body having this letter shape, and this first piezoelectric element is electrically driven to generate a first standing wave,
A second piezoelectric element is bonded to a second surface perpendicular to the first surface, and the second piezoelectric element is electrically driven to generate a second standing wave. An ultrasonic linear motor that generates elliptical vibration or tilted reciprocating vibration on any surface of the U-shaped elastic body by combining existing waves, and presses the slider against the surface that generates this vibration to move the slider linearly. In this case, a protrusion is provided on the surface of the elastic body where the vibration is generated.

[Effect]

By taking the above measures, the following effects are achieved.

By applying voltage to the piezoelectric element attached to the vibrator, the vibrator is excited to vibrate in the vertical and horizontal directions, and by superimposing the vibrations in both directions, the vibrator produces elliptical vibration or tilted reciprocating vibration. Do this. If the slider is pressed and held on the surface of the elastic body on which the protrusions are formed, the flatness of the contact surface with the slider cannot be increased that much.
Furthermore, the slider can be smoothly moved in both left and right directions even if the heights of the vibrators are not precisely matched.

〔Example〕

FIG. 1 is a perspective view showing the structure of a first embodiment of the present invention. Note that the drive circuit is omitted in the figure. A is a vibrator, made of brass or stainless steel.

It is comprised of an elastic body 40 formed in a U-shape from an elastic material with little mechanical loss, such as aluminum, and piezoelectric elements 41, 42, 43, and the like. This vibrator A is fixed to a base (not shown) with screws 44 and 45. A protrusion 46 is formed on the upper surface of the elastic body 40 in a direction perpendicular to the moving direction of the slider B (the direction of the arrow). A piezoelectric element 41 is fixed to the lower surface of the wall provided with the protrusion 46 of the elastic body 40, and piezoelectric elements 42 and 43 are fixed to the outer surfaces of the left and right side walls of the elastic body 40 using an adhesive or the like. These piezoelectric elements are provided with electrode surfaces made of baked Ag or the like. Note that the piezoelectric elements 42 and 43 are not limited to the locations shown in the figure, but may be mounted on the inner surface of the side wall of the elastic body 40, for example.

FIG. 2 is a diagram showing a drive control system for vibrating the vibrator A and driving the slider B. The output signal of the high frequency power supply 51 is amplified by an amplifier 52 on one side, and then
The voltage is applied to the piezoelectric cord 41 (not shown in this figure). On the other hand, a phase shifter 5 that can vary the phase from 0 to 360°
3, the signal is amplified by an amplifier 54, and applied to piezoelectric elements 42 and 43 (not shown in this figure), respectively.

FIGS. 3(a) to 3(C) show piezoelectric elements 41 and 42.43.
It is a figure showing the polarization direction of. When a voltage is applied to the piezoelectric cord 42, it is polarized in the direction of the arrow in FIG. When a voltage is applied to the same figure (e
) is polarized in the direction of the arrow. Such a polarization direction is arbitrarily set in order to excite the vibrator A to a desired vibration.

According to this embodiment prepared as described above, the following effects are achieved. When the voltage amplified by the amplifier 52 is applied to the piezoelectric element 41, the vibrator A becomes as shown in FIG. 4(a).
It vibrates in the operating mode shown in . Further, the output voltage whose phase has been shifted through the phase shifter 53 is amplified by the amplifier 54,
When applied to the piezoelectric elements 42 and 43, the vibrator A vibrates in the operating mode shown in FIG. 4(b). By combining the above two modes, the vibrator A becomes as shown in Fig. 5(a) -
Draw a vibration trajectory as shown in (d). In particular, the protrusion 46 portion vibrates with maximum amplitude. Note that the type of vibration that the protrusion 46 performs is determined by adjusting the phase shifter 53 to change the degree of phase shift. For example, the tilted reciprocating vibration shown in Figure 5(a) is for a phase shift of 0°, the elliptical-10 = circular vibration shown in Figure 5(b) is for a phase shift of 270°, and the elliptical vibration shown in Figure 5(C) is for a phase shift of 270°. The tilted reciprocating vibration shown in is for a phase shift of 180°, and the figure (d)
The elliptic vibration shown in is for a phase shift of 90°.

Therefore, the elastic body 40 which is the contact surface with the slider B
Even if the upper surface is not polished to maintain a highly accurate flatness, if the slider B is brought into pressure contact with the protrusion 46 in the above-mentioned vibrating state using an appropriate suppressing means, the slider B will move to the right or left. Moving. If the protrusion 46 is in the vibrating state shown in FIG. 5(a) or (b), the slider B moves to the left in the figure, and if it is in the vibrating state shown in FIG. 5(c) or (d), Move to the right in the diagram.

In this embodiment, the protrusion 46 formed on the elastic body 40 is shaped like a rectangular parallelepiped, but it may also have a triangular or semicircular cross-sectional shape as shown in FIGS. The same effect can be obtained.

FIG. 7 is a side view showing the configuration of a second embodiment of the present invention. Note that the vibrator A used in this example is the same as the vibrator A used in the T51 example.

A plurality of vibrators A (three in this example) are arranged at predetermined intervals on the base 60 and fixed with screws.

A rotatable roller 61 is disposed above each vibrator A, and is pressed against a protrusion on each vibrator with an appropriate pressing force by a spring member 62. Note that the spring member 62
The mounting is fixed to the board 63. A slider B is inserted between the protrusion 46 and the roller 61. The slider B, which is the driven body, may be, for example, a magnetic card, an optical card, a tape, or the like.

In such a device, if the vibrators A are vibrated using the drive control system shown in FIG. 2 in the same way as in the first embodiment, the heights between the vibrators A can be adjusted without particular precision. Slider B can be smoothly moved to the right or left.

FIG. 8 shows the vibrator A shown in the first embodiment and the second embodiment.
It is a perspective view showing a modification of . The vibrator AA in this modification differs from the vibrator A in that two protrusions 71 and 72 are provided on the upper surface of the U-shaped elastic body 70, and that the vertical vibration is suppressed by the secondary vibration. The point is that it can be done in mode.

That is, the vibrator AA shown in this example has 2 as the first standing wave.
It uses modes of the following orders: A piezoelectric element 73 is fixed to the back side of the elastic body 70.

Further, piezoelectric elements 74 and 75 are fixed to the left and right side walls perpendicular to the surface to which the piezoelectric element 73 is fixed. The vibrator AA is fixed to a base (not shown) with screws 76 and 77.

FIG. 9 is a diagram showing the polarization direction of the piezoelectric element 73. As shown by the arrows in the figure, the polarization state of the piezoelectric element 73 is such that the center portion is polarized downward in the figure and the side portions are polarized upward in the figure. Note that the piezoelectric elements 74 and 75 are polarized in the same manner as in FIGS. 3(a) and 3(c).

The effects when the vibrator AA configured as described above is vibrated using the drive control system shown in FIG. 2 will be described. When a voltage is applied to the piezoelectric element 73, it is polarized as shown by the arrows in FIG. 9, and upward and downward vibrations are excited. As a result, the vibrator AA is as shown in FIG.
The protrusions 71 and 72 vibrate in an upward mode, and the central portion between the protrusions 71 and 72 vibrates in a downward mode. Further, when a voltage is applied to the left and right piezoelectric elements 74 and 75, they vibrate in a mode similar to that shown in FIG. 4(b). Then, when each mode is combined, the fifth
A tilted reciprocating vibration or an elliptical vibration similar to that shown in Figures (a) to (d) is performed.

Therefore, if a slider (not shown) is brought into pressure contact as in the first embodiment, this slider will move in both left and right directions. In this embodiment as well, as in the first embodiment, it is possible to achieve the effect that polishing of the upper surface of the elastic body 70 and highly accurate mutual height adjustment of the vibrating bodies are not particularly required. It is.

Note that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, since the protrusion is provided on the upper surface of the elastic body at the contact portion with the slider, the slider can be moved smoothly without having to polish the entire upper surface of the elastic body to maintain highly accurate flatness. be able to. Furthermore, when a large number of vibrators are used in series, the slider can be moved satisfactorily even if the heights of the vibrators are not precisely matched.

[Brief explanation of the drawing]

1 to 6 are diagrams showing a first embodiment of the present invention,
Figure 1 is a perspective view of the vibrator and slider, Figure 2 is a configuration diagram showing the drive control system, Figures 3 (a) to (C) are diagrams showing the polarization direction of the piezoelectric element, Figure 4 (a) (b) is a diagram showing the operating mode of the vibrator, Figures 5 (a) to (d) are diagrams showing the vibration state of the protrusion, and Figures 6 (a) and (b) are deformations of the cross-sectional shape of the protrusion. FIG. 2 is a schematic diagram illustrating an example. 7 to 10 are diagrams showing a second embodiment of the present invention, FIG. 7 is a configuration diagram, and FIG.
9 is a perspective view showing a modified example of the vibrator, FIG. 9 is a view showing the polarization direction of the piezoelectric element, and FIG. 10 is a view showing the operating mode of the vibrator shown in FIG. 8. Figure 11 is a configuration diagram of a conventional ultrasonic linear motor, Figure 12
The figure shows traveling waves generated in the elastic body of the conventional example. Fig. 13 to Fig. 15 are diagrams showing the prior art of the present invention, Fig. 13 is a configuration diagram of an ultrasonic linear motor, and Fig. 14 (a)
(b) is a diagram showing the vibration state occurring on the vibrator, No. 15
The figure is a configuration diagram of an ultrasonic linear motor. A, AA... vibrator, B... slider, 40°7
0...Elastic body, 46,71.72...Protrusion. Applicant's agent Patent attorney Jun Tsuboi Figure 1 Figure 2 (a) (b) (c)
Figure 3 Figure 4-10 I0

Claims (1)

[Claims] A first piezoelectric element is bonded to a first surface of a U-shaped elastic body, the first piezoelectric element is electrically driven to generate a first standing wave, and the first piezoelectric element is electrically driven to generate a first standing wave. the second orthogonal to
A second piezoelectric element is bonded to the surface of the plane, the second piezoelectric element is electrically driven to generate a second standing wave, and the U-shaped elastic In an ultrasonic linear motor that generates elliptical vibration or tilted reciprocating vibration on any surface of the body and presses a slider against the surface that generates this vibration to move the slider linearly, the surface that generates the vibration of the elastic body. An ultrasonic linear motor characterized in that a protrusion is provided on the ridge.