JPH02223389A - Stepping motor and driving method therefor - Google Patents

Abstract

PURPOSE:To perform fine control of rotary displacement or speed through variation of source voltage or frequency by providing a first longitudinal vibration element for contacting/separating a laminated torsional actuator with/from a fixed member through expansion/contraction and a second longitudinal vibration element which performs expanding/contracting vibration with reverse phase from that of the first longitudinal vibration element. CONSTITUTION:When alternating voltages having same frequency as that of a laminated torsional actuator A and phases matched to and shifted by 180 deg. from the actuator A are applied onto longitudinal vibration piezoelectric elements 8a, 8b, end boards 2a, 2b are clamped alternately to a cylindrical body 9. In stage I, upper end board 2 is clamped, and the lower end board 2 and an output shaft 10 rotate. In stage II, the lower end board 2 is clamped and only the upper end board 2 rotate. The output shaft 10 always rotates in a predetermined direction and the amount of rotation is proportional to the pulse being fed to the laminated torsional actuator A and the longitudinal vibration piezoelectric elements 8a, 8b. Consequently, function as a stepping motor can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stepping motor that utilizes the thickness sliding effect in a piezoelectric material to convert it into rotational force, and a method for driving the same.

[Prior Art] Ultrasonic motors have been developed using piezoelectric elements that utilize a piezoelectric phenomenon in which dielectric materials such as ceramics are displaced when a voltage is applied. What is shown in FIG. 16 is an ultrasonic motor using a torsional vibrator 103 configured by integrating a piezoelectric element 101 that generates longitudinal vibration and a torsional coupler 102. As shown in FIG. 17, the connector 102 is a disc body 107 that fits into a groove 106 with a protrusion 105 formed on the resonator 104 adjacent to the piezoelectric element lO1, and has a groove on the other side of the groove 106. Projection 1 inclined relative to 106
08 is formed, and the protrusion 108 outputs an output that is twisted in the radial direction due to the deflection of the disc body 107 as the resonator 104 expands and contracts in the axial direction. A screw like this,
By bringing the vibrator into pressure contact with the rotor 109 as shown, rotation in only one direction is always transmitted to the rotor 1'09.

[Problems to be Solved by the Invention] However, in the ultrasonic motor configured as described above, since the torsion coupler 102 is configured to convert the expansion and contraction of the resonator 104 into deflection, the Usable. Therefore, although a large amount of displacement can be achieved, it is not suitable for use as a stepping motor that precisely controls extremely small amounts of rotation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stepping motor and a method for driving the same, in which rotational displacement and speed can be precisely controlled by changing the voltage and frequency of a power supply.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a laminated torsional actuator having a pair of cylindrical outer peripheral surfaces that are torsionally displaced relative to each other, and a laminated torsional actuator. A cylindrical fixing member surrounding the stacked torsion actuator with a predetermined gap is provided between the fixing member and one cylindrical outer circumferential surface of the stacked torsional actuator, and the stacked torsion actuator and the fixing member are moved toward and away from each other by expansion and contraction of the fixing member. A first longitudinal vibration element is provided between the fixing member and the other cylindrical outer peripheral surface of the laminated torsional actuator, and vibrates by stretching and contracting in an opposite phase to the first longitudinal vibration element to vibrate the laminated torsion actuator. The stepping motor includes a second longitudinal vibration element that brings an actuator into and out of contact with a fixed member. Preferably, one or both of the first longitudinal vibration element and the second longitudinal vibration element are formed into a cylindrical shape.

Further, the present invention provides a laminated torsional actuator and a facing member adjacent thereto, which are rotatable relative to each other, and connects the laminated torsional actuator and the facing member by expansion and contraction between the laminated torsional actuator and the facing member. A first longitudinal vibration element is provided between the opposing member and a fixed member that is close to the opposing member, and the opposing member and the fixed member are moved toward and away from each other by expanding and contracting vibration in an opposite phase to the first longitudinal vibration element. Second
This is a stepping motor equipped with a vertical vibration element.

It is also preferable that one or both of the first longitudinal vibration element and the second longitudinal vibration element be formed in a cylindrical shape. Furthermore, it is preferable that the laminated torsional actuator and the opposing member are connected to each other so as to be relatively rotatable by a connecting body that regulates the dimensions between the laminated torsional actuator and the opposing member.

Furthermore, it is preferable that the fixing member is constituted by a second laminated torsional actuator that torsionally vibrates in an opposite phase to the laminated torsional actuator.

Further, the present invention provides a laminated torsional actuator and a facing member adjacent thereto, which are rotatable relative to each other, and the laminated torsional actuator and the facing member are connected by expansion and contraction between the laminated torsional actuator and the facing member. A first longitudinal vibration element is provided between the opposing member and a fixed member that is close to the opposing member, and the opposing member and the fixed member are moved toward and away from each other by expanding and contracting vibration in an opposite phase to the first longitudinal vibration element. Using a stepping motor equipped with a second longitudinal vibration element,
L The laminated torsional actuator and the first longitudinal vibration element are vibrated at the resonance frequency of the laminated torsional actuator, and at this time, the second longitudinal vibration element is in a stopped state or the laminated torsion actuator and the opposing member are This is a method of driving a stepping motor characterized by holding the stepping motor in a separated state.

The above-mentioned laminated torsional actuator is a torsional actuator in which flat piezoelectric element pieces are arranged on a plane so that the polarization directions are along the tangents of concentric circles, and electrode plates are provided on both sides of the piezoelectric element pieces to form a torsion element. The torsion elements are arranged in multiple layers. This utilizes the so-called thickness sliding effect, in which when an electric field is applied to a piezoelectric material from a direction perpendicular to the polarization direction, the piezoelectric material slides and deforms in a plane including the polarization direction.

[Operation] In the piezoelectric motor having such a configuration, when a voltage is applied to the torsion element laminated type torsion actuator, the torsion element causes torsional deformation. When the power source is direct current, the balance is reached at a predetermined angle, and this angle is proportional to the voltage.

In the case of alternating current, the torsion element vibrates, but the amplitude is proportional to the voltage and the frequency is proportional to the power supply frequency, so the rotation speed is proportional to the product of voltage and frequency.

This vibration is transmitted to the fixed member by the longitudinal vibration type piezoelectric element, but by expanding and contracting this longitudinal vibration type piezoelectric element at the same frequency as the laminated torsional actuator, the rotation of only one side of the laminated torsional actuator is fixed. The rotational force is transmitted to the member, and the stacked torsion actuator itself rotates due to the reaction, which is output to the outside as a rotational output. This allows rotation in l steps, the number of rotations being proportional to the product of the voltage and frequency of the power supply.

In addition, in a stepping motor in which a facing member is provided close to a stacked torsional actuator, the vibration of the stacked torsional actuator is transmitted to the facing member by a longitudinal vibration type piezoelectric element. By expanding and contracting at the same frequency as the actuator, the rotation of the laminated torsion actuator in only one direction is transmitted to the opposing member, and is output from the opposing member to the outside as a rotational output. This allows rotation in steps of l, and the number of rotations is also proportional to the product of the voltage and frequency of the power supply.

Furthermore, in the stepping motor driving method, by using the laminated torsional actuator in a resonant state, the torsional vibration of the laminated torsional actuator and the longitudinal vibration of the first longitudinal vibration element are combined, and the opposing member is An elliptical traveling wave is generated for driving. Therefore, it becomes possible to drive the stepping motor to rotate continuously at high speed.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

In FIGS. 1 to 3, l is a cylindrical laminated piezoelectric body, and disk-shaped end plates 2 a and 2 b each having a cylindrical outer circumferential surface made of aluminum or the like are arranged at both ends of the laminated piezoelectric body. They are connected by a connecting bolt 3 that passes through the body 1, and press the laminated piezoelectric body 1 with a constant force.

The laminated piezoelectric body 1 has, as shown in FIGS. 2 and 3,
A piezoelectric ceramic layer 5 consisting of a piezoelectric element piece 4 and an electrode plate 6
The piezoelectric element piece 4 has a shape obtained by dividing a disk having a center hole into eight parts. This piezoelectric element piece 4 is made of piezoelectric ceramic such as PZT, and by applying a high voltage from both end faces thereof, it is polarized approximately in the direction of the arrow ``a'' along the circumferential direction shown above, and each piezoelectric element The pieces 4 are arranged so that their polarization directions are the same.

The electrode plate 6 is bonded to both sides of the piezoelectric ceramic layer 5 with a conductive adhesive, and the piezoelectric ceramic layer 5 and the electrode plates 6, 6 constitute a unit of the torsion element 7. In this embodiment, ceramic layers 5 and electrode plates 6 are alternately arranged, and torsion elements 7 are stacked in four layers.

The polarization directions of the adjacent piezoelectric ceramic layers 5 are alternately reversed, and the power supply wiring to the electrode plate 6 is connected every other time, so that the polarization direction of the adjacent piezoelectric ceramic layers 5 is reversed. The direction of the power connection is reversed.

A pair of vertically vibrating piezoelectric elements 8 a, 8 b are protrudingly attached to the outer circumferential surfaces of the end plates 2 a, 2 b of the laminated torsional actuator A configured in this manner at opposing positions, respectively. Vertical vibration piezoelectric element 8a.

8b is adapted to expand and contract in the axial direction by applying an appropriate alternating current. The phases of these expansion and contraction vibrations are 180 degrees different from each other, and one longitudinally vibrating piezoelectric element 8
When a is extended, the other longitudinally vibrating piezoelectric element 8b is contracted. The frequency of this vibration is set to be equal to the frequency of the power supply applied to the laminated torsional actuator A.

A cylindrical body (fixing member) 9 is fixed on the outside of the laminated torsional actuator A and whose inner diameter is set to be approximately equal to the distance between both ends of the longitudinally vibrating piezoelectric element 8a. Further, an output shaft 10 is formed protruding from the center of one end plate 2a, and a bottom plate 1 of the cylindrical body 9 is attached to this output shaft 10.
It is rotatably supported by a bearing (not shown) fixed to 1, with movement in the axial direction restricted.

The ends K 2 a, 2 b are made of aluminum, the piezoelectric element piece 4 is made of ceramic material of PZT, and the electrode plate 6 is made of phosphor bronze.
, 5 ml11, diameter 40111ffiφ, thickness of laminated piezoelectric material 1 7.5 mm, thickness of end plate 2 5I, diameter 60
Regarding the piezoelectric actuator A with IIIlφ, when the power supply voltage is changed in the range of 0 to 500V, 0 to 1000V (7), as shown in FIG.
When the voltage was varied within the range of +500v and -1000 to +1000v, the result was as shown in Fig. 5. Table 1 shows the results of calculating the torsion angle between the end plates 2 a and 2 b and the distortion angle rate of one torsion element 7 based on this amount of displacement.

Table 1 As shown in this graph, the amount of displacement changes almost linearly, although there is a certain amount of hysteresis with respect to changes in the power supply voltage. As shown in the figure and table, this amount of displacement is extremely small relative to the voltage change.

PZT, which is the material of this piezoelectric ceramic, has a thickness slip constant dls of 460X10-''■/V, but by using a flexible material with a large constant (Ls) as a piezoelectric ceramic, the amount of displacement with respect to voltage can be reduced. It is possible to manufacture large actuators.

Next, the operation of the stepping motor configured as described above will be explained.

When an alternating voltage of an appropriate frequency is applied to the laminated torsional actuator A, one end plate 2a torsionally vibrates with respect to the other end plate 2b as shown in FIG. 6(A). Therefore, if an alternating voltage with the same frequency, the same phase, and 180 degrees difference as that of the laminated torsional actuator A is applied to each longitudinally vibrating piezoelectric element 8a, 8b, the end plates 2a, 2
b are alternately clamped to the cylindrical body 9. That is, as shown in FIG. 6(B), in step 1 of FIG. 6(A), the upper end plate 2 is clamped, and the lower end plate 2 and the output shaft 1O are rotated. At stage H, the lower end plate 2 is clamped, and only the upper end plate 2 rotates. The output shaft IO always rotates in a constant direction, and the amount of rotation is proportional to the pulses applied to the laminated torsional actuator A and the longitudinally vibrating piezoelectric element, so it functions as a stepping motor. In this stepping motor, the rotation angle is extremely small considering the characteristics of the laminated torsional actuator A described above, and high torque can be generated. Also, since it is driven via friction, the stopping accuracy is also good. Since the rotation angle per pulse is proportional to the voltage of the applied power supply, the rotation angle can be easily adjusted, and therefore it is suitable as a drive source for small electronic devices.

Second Embodiment FIGS. 7 and 8 show a second embodiment of the present invention, in which the output shaft was attached to the laminated torsional actuator A in the first embodiment described above. In contrast, the output shaft is separate.

That is, the lower end plate 2 of the laminated torsional actuator A
1 is formed with a cylindrical peripheral wall (fixing member) 23 whose height is approximately equal to the height to the upper surface of the upper end plate 22 . The central axis 24 of the laminated torsional actuator A is connected to the end plates 21 and 22.
is inserted through it, and is pressed together with a nut or the like (not shown) to pressurize the laminated piezoelectric layer, and is further extended vertically. The center shaft 24 is provided with a disc-shaped rotor (opposing member) 25 having a diameter approximately equal to the outer diameter of the peripheral wall 23, and spring receivers 26a, 26b are provided at the lower end of the center shaft 24 and the lower surface of the end plate 21. The elastic member (
The rotor 25 is urged downward by a coil spring 26c. On the upper surface of the upper end plate 22, first longitudinally vibrating piezoelectric elements 27 are arranged (three in the example) at equal intervals in the circumferential direction so that the expansion and contraction directions are up and down, and are fixed with adhesive or the like. Further, on the upper surface of the peripheral wall 23, second vertical vibration pressures are applied at positions facing the first vertical vibration piezoelectric elements 27 in the circumferential direction. (
A U element 28 is similarly attached. These longitudinally vibrating piezoelectric elements 27 and 28 are supplied with power at the same frequency as the laminated torsional actuator 8, but with a phase that is 180 degrees different from each other. Further, an output shaft 31 is connected to the upper surface of the rotor 25 via a spacer 29 and a connecting member 30.
is provided.

The operation of the stepping motor of this second embodiment is as follows.
The explanation will be based on the principle diagrams in Figures (a) to 2).

The torsion of the laminated torsional actuator A in the direction of arrow C (see figure (b)) is synchronized with the extension of the first longitudinal vibration element 27, and at this time, the rotor 25 and the end plate 22 are connected. The displacement of the laminated iron reactuator A is transmitted. Stacked torsional actuator A is indicated by arrow D (see figure (d))
When displacing in the opposite direction as in
Since the rotor 7 is contracted and the second longitudinal vibration element 28 is expanded, the rotor 25 is connected to the peripheral wall and is prevented from moving. That is, the rotor 25 transmits torsion in only one direction to the laminated torsional actuator, the displacement of which corresponds to the number of pulses of the power supply. Further, as in the first embodiment, the amplitude of the laminated torsional actuator A is proportional to the voltage of the power supply.

The first longitudinally vibrating piezoelectric element 27 has an alternating voltage of 70V peak-to-peak and a DC bias IOV, and the second longitudinally vibrating piezoelectric element 28 has an alternating voltage of 70V and a DC bias of 80V.
An alternating voltage of V and a DC bias of 40 μm were applied, and an alternating voltage of 400 μm was applied to the laminated torsional actuator A. The vertical vibration piezoelectric elements 2728 are 180 degrees apart, and the laminated torsion actuator 8 and the vertical vibration piezoelectric elements 27.28 are ±9 degrees.
I set it so that it differs by 0 degrees by 4. Further, the pressure of the coil spring 26c was set to 64 kgr. The relationship between the drive power frequency and the rotational speed at this time is shown in FIG. Furthermore, under the same conditions, the frequency is set to lQ Hz, and FIG. 1I shows the change in rotational speed when the voltage of the accounting power supply applied to the laminated torsional actuator is changed.

In this example, compared to the first embodiment described above, the vibrations of the longitudinally vibrating piezoelectric elements 27 and 28 are not restrained, so that the vibration frequency is as high as, for example, the resonance frequency (even if the longitudinally vibrating piezoelectric element Accidents such as damage due to excessive stress acting on the elements 27 and 28 are less likely to occur. Therefore, in addition to being used as a stepping motor, it is possible to drive at the resonant frequency by attaching a resonator to the end plate and increasing the rotation speed. Furthermore, there are advantages such as being able to adjust the pressing force of the coil spring 26c to set more appropriate operating conditions.In other words, the multilayer torsion actuator A is used in a resonant state. By matching the frequency of the first longitudinally vibrating piezoelectric element with this frequency, the torsional vibration of the laminated torsional actuator A and the longitudinal vibration of the first longitudinally vibrating element 27 are combined, and the first An elliptical traveling wave is generated on the upper surface of the longitudinally vibrating piezoelectric element 27. Therefore, the vibration of the second longitudinally vibrating piezoelectric element 28 is stopped or the second longitudinally vibrating piezoelectric element 28 is displaced to a compressed state. This causes the rotor 25 to rotate at high speed.

Third Embodiment A fourth embodiment of the present invention will be described with reference to FIGS. 12 and 13. However, elements common to those of the second embodiment shown in FIG. 7 are given the same reference numerals to simplify their explanation.

The stepping motor of this example differs from the stepping motor of the second example in the shape of the longitudinally vibrating piezoelectric element.

That is, the first longitudinally vibrating piezoelectric element 37 is formed into a cylinder whose outer circumferential surface substantially matches the outer circumferential surface of the upper end of the laminated torsional actuator A, and the second longitudinally vibrating piezoelectric element 38
is formed into a cylindrical shape whose inner circumferential surface substantially matches the inner circumferential surface of the peripheral wall 23 .

In the stepping motor of the third embodiment configured as described above, the rigidity when transmitting torque from the laminated torsional actuator A to the rotor 25 is extremely high compared to the columnar longitudinal vibration piezoelectric element of the second embodiment. . Therefore, the deflection of the first longitudinally vibrating piezoelectric element 37 and the second longitudinally vibrating piezoelectric element 38 with respect to the torque load is extremely small.

According to the stepping motor of the embodiment configured as described above, since the deflection of the first longitudinally vibrating piezoelectric element 37 and the second longitudinally vibrating piezoelectric element 38 is extremely small, the torsional angle of the laminated torsional actuator A is The rotors 25 can be rotated at substantially the same angles, and the rotational speed of the rotors 25 can be improved, and efficiency can be improved.

It goes without saying that each of the longitudinally vibrating piezoelectric elements 37 and 38 described above may be applied to each of the longitudinally vibrating piezoelectric elements 27 and 28 of the second embodiment.

Brush "J" 1 stitch A fourth embodiment of the invention will be described with reference to FIG.

However, elements common to those of the second embodiment shown in FIG. 7 are given the same reference numerals to simplify their explanation.

The stepping motor of this embodiment differs from the stepping motor of the second embodiment in the structure of the connecting portion at the lower end of the central shaft 24.

That is, the lower end portion of the central shaft (connecting body) 24 is connected to the lower surface of the end plate 21 via the second connecting member 36.

The connecting member 36 receives the tensile load of the central shaft 24 and is a thrust bearing 3 that rotatably supports the central shaft 24.
6a and the lower end of the central shaft 24.
The thrust bearing 36a is provided with a fixing groove 36b that transmits the tensile load of the thrust bearing 36a to the thrust bearing 36a. Further, the connecting member 30 connects the upper end of the central shaft 24 to the upper surface of the spacer 29, and receives the tensile load of the central shaft 24.
A thrust bearing 30a rotatably supports the central shaft 24, and a thrust bearing 30a is screwed onto the upper end of the central shaft 24 to support the central shaft 24.
The thrust bearing 36a is provided with a fixing groove 30b that transmits the tensile load of 4 to the thrust bearing 36a.

In the stepping motor of the fourth embodiment configured as described above, the fixing nut 30b and the fixing nut 36
By adjusting the screwing position of b, the dimensions between the lower surface of the rotor 25, the L surface of the end plate 22, and the upper end surface of the peripheral wall 23 are set to predetermined dimensions.

Therefore, according to the stepping motor of this embodiment, the lower surface of the rotor 25, the upper surface of the end plate 22, and the peripheral wall 23
Since the dimension with respect to the upper end surface is maintained at a predetermined dimension, the longitudinally vibrating piezoelectric element 3
7.38 comes into contact with and separates from the lower surface of the rotor 25, and at this time, the pressing force of the longitudinally vibrating piezoelectric elements 37.38 against the rotor 25 becomes approximately constant. For this reason, for example, when the rotor 25 is pressed against the longitudinally vibrating piezoelectric elements 37.38 by the elastic force of the spring, the expansion and contraction of the spring follows the expansion and contraction of each longitudinally vibrating piezoelectric element 37.38 when the frequency is set to high. However, the stepping motor of this embodiment can overcome this drawback.

It goes without saying that the connecting member 36 of this embodiment may be applied to the stepping motors of the second and third embodiments.

Strategy 1 Arashi Bay A fifth embodiment of the present invention will be described with reference to FIG.

However, elements common to those of the second embodiment shown in FIG. 7 are given the same reference numerals to simplify their explanation.

The stepping motor of this embodiment differs from that of the second embodiment in the structure of the peripheral wall (fixing member).

That is, the peripheral wall includes a cylindrical laminated piezoelectric body 41 provided on the outer periphery of the upper surface of the end plate 21, and a cylindrical annular body 42 made of aluminum or the like coaxially connected to the upper end surface of the laminated piezoelectric body 41. The second laminated torsional actuator B is formed such that the position of the upper end surface of this annular body 42 substantially coincides with the position of the upper surface of the end plate 22.

In the stepping motor of the fifth embodiment configured as described above, alternating voltages having a phase difference of 180 degrees are applied to the laminated torsional actuator A and the second laminated torsional actuator B.

When the laminated torsional actuators A and B are twisted in the direction of the arrow E, each longitudinally vibrating piezoelectric element 27, 28 has a
A voltage is applied in the direction of extension, and when it is twisted in the opposite direction of arrow E, a voltage is applied in the direction of contraction. Then, when the laminated torsional actuator A is twisted in the direction of arrow E,
The first longitudinally vibrating piezoelectric element 27 is extended to connect the rotor 25 and the laminated torsional actuator A, and at this time, the second laminated torsional actuator B is connected to the second longitudinally vibrating piezoelectric element 2.
8 is compressed and twisted in the opposite direction of the arrow E while being separated from the rotor 25. Further, when the laminated torsional actuator A is twisted in the opposite direction of the arrow E, the first longitudinally vibrating piezoelectric element 27 is contracted and separated from the rotor 25,
At this time, the second laminated torsional actuator B is twisted in the direction of arrow E with the second longitudinally vibrating piezoelectric element 28 being extended and connected to the rotor 25. That is, rotor 2
5 is rotated by laminated torsional actuators A and B which are alternately twisted in the direction of arrow E.

Therefore, according to the stepping motor of this embodiment, the rotational speed of the rotor 25 can be increased approximately twice as compared to a stepping motor having only one laminated torsional actuator A.

It goes without saying that the peripheral wall 23 of the second, third, or fourth embodiment may be constructed of the second laminated torsional actuator B of this embodiment.

[Effects of the Invention] As described in detail above, the invention of claim 1 includes a laminated torsional actuator having a pair of cylindrical outer circumferential surfaces that are torsionally displaced relative to each other, and a laminated torsional actuator that is separated by a predetermined gap. a cylindrical fixing member that surrounds the stacked torsional actuator with an opening; a first member that is provided between the fixing member and one cylindrical outer peripheral surface of the laminated torsional actuator, and that expands and contracts to move the laminated torsional actuator and the fixing member toward each other; A vertical vibration element is provided between the fixing member and the other cylindrical outer circumferential surface of the laminated torsional actuator, and expands and contracts to vibrate in an opposite phase to the first longitudinal vibration element to connect the laminated torsional actuator and the fixing member. Since it is equipped with a second longitudinal vibration element that connects and separates the actuator, it is possible to easily adjust the rotational speed and control the position by taking advantage of the characteristics of the laminated torsional actuator, making it possible to obtain a high-torque stepping motor. .

Further, in the invention of claim 2, the laminated torsional actuator and the opposing member adjacent thereto are provided so as to be able to rotate freely relative to each other, and the laminated torsion actuator and the opposing member are expanded and contracted between the mutually opposing surfaces of the laminated torsional actuator and the opposing member. A first longitudinal vibration element is provided that brings the torsion actuator and the opposing member into contact with each other, and a fixed member that is close to the opposing member is provided with a first longitudinal vibration element that extends and contracts and vibrates in an opposite phase to the first longitudinal vibration element so that they face each other. By providing a second longitudinal vibration element that brings the member into contact with and away from the fixed member, a high-torque stepping motor with easy rotational speed adjustment and position control that takes advantage of the characteristics of a laminated torsional actuator is obtained. be able to.

Furthermore, in the invention of claim 3, since one or both of the first longitudinal vibration element and the second longitudinal vibration element are formed into a cylindrical shape, the rigidity of each longitudinal vibration element can be improved. Therefore, it is possible to improve the rotation speed and efficiency.

Furthermore, in the invention of claim 4, since the connecting body for regulating the dimension between the laminated torsional actuator and the opposing member is provided, the vibration frequency is approximately constant in the frequency range from low frequency to high frequency. The longitudinal vibration element can be pressed against the opposing member and the laminated torsional actuator by force. Therefore, it is possible to almost prevent the phenomenon that the torque decreases as the frequency increases.

In addition, in the invention of claim 5, the fixed member is provided with a second
Since it is formed with a laminated torsional actuator, when the laminated torsional actuator is twisted in the opposite direction,
The second stacked torsional actuator will be twisted in the positive direction. That is, since the opposing member can also be rotationally driven by the torsional angle of the second laminated torsional actuator, the opposing member can be rotated at approximately twice the speed.

Furthermore, the invention according to claim 6 has the advantage that it is possible to provide a drive motor with high energy efficiency that utilizes resonance vibration, and that the stepping motor can be used at high speed rotation.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a stepping motor according to a first embodiment of the present invention, FIG. 2 is a diagram showing the state of polarization of a piezoelectric element piece, FIG. 3 is a sectional view of FIG. 1, and FIGS. FIG. 5 is a graph showing the relationship between voltage and displacement of the laminated torsional actuator, FIG. 6 is a diagram showing the rotation mechanism, FIG. 7 is a diagram showing the stepping motor of the second embodiment of the present invention, and FIG.
The figure is a cross-sectional view taken along the line ■-■ of Figure 7, Figure 9 is a diagram showing the rotation mechanism, Figure 1O is a graph showing the relationship between drive frequency and rotational angular velocity, and Figure 11 is the applied voltage of the laminated torsional actuator. FIG. 12 is a diagram showing the stepping motor of the third embodiment of the present invention, FIG. 13 is a YY cross-sectional view of FIG. 12, and FIG. 14 is the stepping motor of the third embodiment of the present invention. A diagram showing a stepping motor of Example 4,
FIG. 15 is a diagram showing a stepping motor according to a fifth embodiment of the present invention, and FIGS. 16 and 17 are perspective views of a conventional example. 9... Cylindrical body (fixing member), 23... Peripheral wall (fixing member), 24... Central axis (2! connection member), 25...
... Rotor (opposed member), 36... Second connection member.

Claims (6)

[Claims] (1) A laminated torsional actuator having a pair of cylindrical outer peripheral surfaces that are torsionally displaced relative to each other; a cylindrical fixing member that surrounds the laminated torsional actuator with a predetermined gap;
a first longitudinal vibration element that is provided between the fixed member and one cylindrical outer circumferential surface of the laminated torsional actuator and moves the laminated torsional actuator and the fixed member toward and away from each other by expansion and contraction; a second longitudinal vibration, which is provided between the other cylindrical outer peripheral surface of the laminated torsional actuator and vibrates by stretching and contracting in an opposite phase to the first longitudinal vibrating element to bring the laminated torsional actuator and the fixing member into contact with and away from each other; A stepping motor characterized by comprising: an element. (2) A layered torsional actuator and a facing member adjacent to the layered torsional actuator are provided so as to be rotatable relative to each other, and the layered torsional actuator and the facing member are moved toward and away from each other by expansion and contraction of the layered torsional actuator and the facing member. A second longitudinal vibration element is provided between the opposing member and a fixed member adjacent to the opposing member, and a second longitudinal vibration element is provided between which the opposing member and the fixed member are brought into contact and separated by elastic vibration in an opposite phase to the first longitudinal vibration element. A stepping motor characterized by being provided with a longitudinal vibration element. (3) According to claim 2, either one or both of the first longitudinal vibration element and the second longitudinal vibration element is formed in a cylindrical shape so as to surround the axis of the laminated torsional actuator. stepper motor. (4) Claim 2 or 3, characterized in that the laminated torsional actuator and the opposing member are connected so as to be relatively rotatable by a connecting body that regulates the dimensions between the laminated torsional actuator and the opposing member. The stepping motor described. (5) Claim 2 or 3, characterized in that the fixed member is constituted by a second laminated torsional actuator that torsionally vibrates in an opposite phase to the laminated torsional actuator.
Or the stepping motor described in 4. (6) In the method for driving a stepping motor according to any one of claims 2 to 5, the laminated torsional actuator and the first longitudinal vibration element are vibrated at the resonant frequency of the laminated torsional actuator, and the 1. A method for driving a stepping motor, comprising holding the second vertical vibration element in a stopped state or in a state in which the laminated torsional actuator and the opposing member are separated from each other.