JPH08275558A - Piezoelectric motor - Google Patents

Abstract

PURPOSE: To obtain a piezoelectric motor in which large torque can be generated using a piezoelectric element and the speed control is facilitated while prolonging the service life of the motor. CONSTITUTION: A piezoelectric element A displaceable in the direction of thickness and a piezoelectric element B displaceable in the sliding direction are stacked at a holding part 31 and a drive element 32 is bonded thereon thus constituting a drive section 3. The drive section 3 is pressed against the rotor surface through a resilient pressure mechanism part thus exciting the piezoelectric elements A, B with high frequency voltages of the same frequency having a phase shift. Consequently, the drive piece 32 performs elliptical motion in two planes spreading, respectively, in the direction for pressing the rotor and rotating the rotor. in a section where the drive piece 32 presses the contact face of rotor strongly through the piezoelectric element A, the rotor is driven in the direction for displacing the piezoelectric element B and rotated. Moving direction of the rotor is controlled by inverting the phase of one of two high frequency voltages for exciting the piezoelectric elements A, B and the rotational speed of the rotor is controlled by the magnitude of voltage for exciting the piezoelectric element B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor using a piezoelectric element, and although it is not so fast, it relates to a motor which is small in size, has a large torque, and is required to control a precise rotation angle and position. The present invention relates to a motor that can be used for driving a high-precision rotary indexing table, driving an industrial robot, etc., and can perform precise positioning as a linear motor.

[0002]

2. Description of the Related Art An ultrasonic motor is known as a motor using a piezoelectric element. In this ultrasonic motor, two types of standing waves are generated in an elastic body of a stator by a piezoelectric element, and positional and temporal phase differences of these standing waves are combined into a desired relationship to create a traveling wave, and the traveling wave is generated. The rotor is driven by waves, and the structure is such that the stator and the rotor are pressed so as to make strong contact with each other.

[0003]

In the ultrasonic motor, in order to increase the torque, it is necessary to increase the contact pressure between the stator and the rotor. However, if the stator is strongly pressed against the rotor, the elastic body of the stator cannot vibrate. Therefore, a large torque cannot be generated. Also,
The rotation speed is controlled by controlling the excitation frequency or the phase difference of the excitation signal and changing the generation state of the traveling wave, but the drive circuit is complicated. Further, the driving by the traveling wave has a problem that wear is not negligible and the life of the motor cannot be extended because the contact surface slips.

Further, when an ultrasonic motor is linearly expanded to form a linear motor, vibration is reflected at both ends of the elastic body, and a traveling wave cannot be formed. Therefore, a linear motor using an ultrasonic motor cannot be easily realized.
Therefore, an object of the present invention is to provide a piezoelectric motor that can generate a large torque by using a piezoelectric element, can easily control the speed, and can reduce the wear due to slippage and extend the life of the motor.

[0005]

The piezoelectric motor of the present invention comprises:
Holding for holding a driving piece in contact with the moving part, a first piezoelectric element for controlling contact pressure between the driving piece and the moving part, and a second piezoelectric element for displacing the driving piece in the moving direction of the moving part And a moving part having the same frequency are excited by the drive control means to drive the first and second piezoelectric elements with high-frequency voltages having the same frequency but different phases. The contact pressure between the driving bodies is changed, and the moving portion is moved by the displacement of the second piezoelectric element while the contact pressure is high. In particular, the drive unit is configured by superposing and joining the drive piece, the first piezoelectric element that is displaced in the pressing thickness direction, and the second piezoelectric element that is displaced in the direction orthogonal to the thickness direction.

In addition, the driving portion is provided with piezoelectric elements that are displaced in the thickness direction on the holding portion with a space therebetween, and a driving piece having a protrusion that presses the moving portion to the middle point across the two piezoelectric elements. The drive control means excites the two piezoelectric elements with high-frequency voltages having the same frequency and different phases to displace the two piezoelectric elements with a phase difference. The piezoelectric motor is configured to move the moving part by moving the driving piece while changing the pressure.

Further, in the drive unit, two second piezoelectric elements that are displaced in the thickness direction are arranged at intervals on the holding unit, and a plate is arranged so as to straddle the two second piezoelectric elements. The first piezoelectric element having a driving piece on the upper surface and disposed in the thickness direction is disposed between the two second piezoelectric element units on the plate, and the drive control means controls the two second piezoelectric elements. The piezoelectric element is excited by high frequency voltages having the same frequency and different phases to be displaced with a phase difference, and the first piezoelectric element also has the same frequency, and a moving portion at an intermediate position of the plate on which the second piezoelectric element is arranged. By changing the phase so as to change the displacement of the first piezoelectric element in synchronization with the movement of the direction and exciting with a high frequency voltage, the driving piece is changed while changing the contact pressure of the projection of the driving piece to the moving part. To move the moving part A piezoelectric motor.

Further, the drive section has the first piezoelectric element which is displaced in the thickness direction arranged on the holding section, and the second piezoelectric element which is displaced in the thickness direction is arranged on the first piezoelectric element with a space therebetween. And a drive piece having a protrusion that presses the moving portion to the middle point across the two second piezoelectric elements, and the drive control means controls the two second piezoelectric elements. Are excited by high-frequency voltages having the same frequency and different phases to be displaced with a phase difference, and the first piezoelectric element also has the same frequency, and the second piezoelectric element is disposed at the intermediate position of the plate in the moving portion direction. In synchronism with the movement of the first piezoelectric element, the phase is changed so that the displacement of the first piezoelectric element changes, and excitation is performed with a high-frequency voltage, and the driving piece is moved while changing the contact pressure of the protrusion of the driving piece to the moving portion. Motor that moves the moving part by moving To.

The first piezoelectric element for controlling the contact pressure between the driving part and the moving part is provided between the holding part and the driving part in contact with the moving part. It is assumed that there are provided two second piezoelectric elements which are orthogonal to the pressing direction of the driving piece and the moving portion and are displaced in the directions orthogonal to each other, and the drive control means excites the first piezoelectric element with a high frequency voltage. Further, by selecting the second piezoelectric element and driving the second piezoelectric element with a high frequency voltage having the same frequency as the high frequency voltage but a phase different from that of the high frequency voltage, the contact pressure between the moving portion and the driving piece is changed, and the contact pressure is high during the period. The piezoelectric motor moves the moving part by the displacement of the second piezoelectric element.

The driving piece may be composed of the surface of the piezoelectric element. Further, in the type in which the moving portion is moved by the displacement of the second piezoelectric element, the drive control means is provided with means for changing the amplitude of the high frequency voltage for exciting the second piezoelectric element to control the speed of the moving portion. To do. Further, in a type in which two piezoelectric elements that are displaced in the thickness direction are arranged in parallel and the moving portion is driven by swinging the intermediate point due to the difference in the amount of displacement, they are arranged in parallel in the drive control means. Means for changing the phase of the high-frequency voltage for exciting the piezoelectric element is provided to control the driving speed of the moving unit.

Further, the high frequency voltage generated by the drive control means is set to a high frequency so that an inertial reaction force can be obtained in the first piezoelectric element with respect to the mass of the holding portion.

In order to control the drive direction of the moving part, the drive control means is provided with means for inverting the phase of the high frequency voltage applied to one of the piezoelectric elements. The moving unit may be any of a cylindrical rotor, a disk-shaped rotor, a sphere, and a slider that moves on a plane.

[0013]

When the piezoelectric element that is displaced in the thickness direction is provided in the holding portion and the elastic pressing mechanism portion presses the piezoelectric element against the contact surface of the moving portion in the thickness direction of the piezoelectric element, and an excitation voltage is applied to the piezoelectric element to excite the piezoelectric element. The piezoelectric element expands and contracts in the thickness direction due to the excitation voltage, but when the excitation frequency of this excitation voltage is low, the position of the holding part moves against the elastic force of the elastic pressing mechanism part and contacts the moving part. The pressure does not change so much and becomes a constant value.

However, when the excitation frequency is increased, the reaction force received by the piezoelectric element due to the inertia of the mass of the holding portion increases,
Correspondingly, the change of the contact pressure with the moving part becomes large.
When the excitation frequency is equal to or higher than the resonance frequency determined by the mass of the piezoelectric element, the mass of the holding part, the combined elastic modulus of the piezoelectric element and the elastic pressing mechanism, etc., the contact pressure with the driven body changes greatly. Can be obtained.

Therefore, in the invention described in claims 1, 2, and 6, the piezoelectric element for controlling the contact pressure with the moving portion and the piezoelectric element for driving the moving portion when the contact pressure is large are provided. When the element is excited by a high-frequency excitation voltage, a circular or elliptical motion is generated at the contact point between the moving part and the driving part, and when the contact pressure is large, it moves by moving in the direction orthogonal to the contact pressure of the driving piece of the driving part. Move the department.

According to a third aspect of the present invention, the holding portion is provided with two piezoelectric elements that are displaced in the thickness direction at intervals, and a driving piece having a protrusion is provided between the two piezoelectric elements. Excitation with a high-frequency voltage with a phase difference causes an elliptical motion in the protrusion of the driving piece that comes into contact with the moving part, and a direction (direction of the moving part) orthogonal to the contact pressure of the protrusion when the contact pressure with the moving part is large. The moving part is moved in the moving direction). Further, in the invention described in claims 4 and 5, a piezoelectric element that is further displaced in the thickness direction is provided in order to increase the contact pressure, and the displacement when the piezoelectric element displaces the contact portion when the drive portion drives the moving portion. The pressure is increasing.

Since the moving part is driven while changing the contact pressure by the circle or elliptic motion of the contact point between the driving piece of the driving part and the moving part, the shape of the circle or ellipse, that is, the major axis and the minor axis is changed. By changing the magnitude, when the contact pressure is large, the amount of movement of the drive piece in the moving direction of the moving portion, which is the direction orthogonal to the contact pressure, changes, so that the driving speed of the moving portion can be controlled. Therefore, in the invention according to claims 1, 2, and 6, the speed of the moving portion is controlled by controlling the amplitude of the excitation voltage for exciting the piezoelectric element that is displaced in the moving direction of the moving portion. According to the third and fourth aspects of the present invention, the elliptical shape is changed by controlling the phase of the excitation voltage for exciting the two piezoelectric elements arranged in parallel, and the moving speed of the moving unit is controlled. The speed can also be controlled by changing the frequency of the high frequency voltage of the excitation voltage applied to each piezoelectric element.

Further, in order to change the moving direction of the moving portion, in the invention described in claims 1, 2, 4, 5, 6 the phase of either one of the excitation voltages applied to the first and second piezoelectric elements is set. It suffices to invert the phase. In the invention described in claim 3, the phase of the excitation voltage applied to one of the two piezoelectric elements may be inverted. Since this piezoelectric motor drives the moving portion by the contact pressure between the driving portion and the moving portion, the moving portion only needs to have a surface in contact with the driving portion, and the moving portion has a cylindrical rotor, It may be a rotor on a disk, a sphere, or a slider that moves on a plane.

[0019]

1 is a schematic view of a piezoelectric motor according to an embodiment of the present invention. FIG. 1 (a) is a front view and FIG. 1 (b) is a side view. A cylindrical rotor 2 is fixed to a shaft 1 that is rotatably supported, and a drive unit 3 is pressed against an outer peripheral surface of the rotor 2 by an elastic pressing mechanism unit 4. In this embodiment, the elastic pressing mechanism section 4 is composed of a leaf spring 5 fixed to a base 6. 2 is a schematic view of a piezoelectric motor according to a second embodiment of the present invention, FIG. 2 (a) is a plan view, and FIG.
(B) is a side view. A disc-shaped rotor 2'is fixed to a shaft 1 which is rotatably supported.
The drive unit 3 is pressed by the elastic pressing mechanism unit 4 composed of the leaf spring 5 fixed to the base 6 on the disk surface of the disc.

FIG. 3 is a view showing the structure of the first embodiment of the drive unit 3 used in the piezoelectric motor of each of the above embodiments. A piezoelectric element A that is displaced in the thickness direction and a piezoelectric element B that is displaced in a direction orthogonal to the thickness direction (hereinafter referred to as a slip direction) are stacked and fixed on the holding portion 31, and these two piezoelectric elements A and B are stacked. A driving piece 32 that is in contact with the rotors 2 and 2'of the moving portion driven by the driving portion 3 is fixed to the upper surface. In the example shown in FIG. 3A, the holding unit 31
The piezoelectric element A which is displaced in the thickness direction is fixed on the upper side, the piezoelectric element B which is displaced in the sliding direction is fixed next, and the driving piece 3 is further fixed.
2 shows an example in which the piezoelectric element B is fixed on the piezoelectric element B which is displaced in the sliding direction. In FIG. 3B, the holding portion 31, the piezoelectric element B which is displaced in the sliding direction, the piezoelectric element A which is displaced in the thickness direction, and the driving piece 32 are shown. An example of the drive unit 3 fixed in the order of is shown.

The piezoelectric element A which is displaced in the thickness direction is shown in FIG.
As shown in FIG. 4A, when a voltage is applied to the electrodes 33 and 34, it is displaced in the thickness direction (the thickness is increased or decreased), and the piezoelectric element B displaced in the sliding direction is as shown in FIG.
When a voltage is applied between the electrodes 33 and 34, the upper surface and the lower surface are laterally moved in opposite directions and displaced (displaced in a direction orthogonal to the thickness direction) so as to slide. This piezoelectric element A,
The displacement direction of B is determined by a pretreatment called polarization, and if the polarization direction is reversed, the displacement direction of the piezoelectric element when the applied voltage is increased or decreased will be reversed.

The operation of the drive unit 3 having the structure shown in FIG. 3A will be described. In this case, the piezoelectric element A is polarized so that the thickness increases when a positive voltage is applied to the electrodes 33 and 34, and the thickness decreases when a negative voltage is applied, and the piezoelectric element B is applied with a positive voltage. Then, the upper surface moves to the right and the lower surface moves to the left, and it is assumed that the upper surface is polarized to the left and the lower surface to the right when a negative voltage is applied. Therefore, as shown in FIG. 6A, the excitation voltage VA is applied to the piezoelectric element A which is displaced in the thickness direction.
When a voltage VB having the same frequency as the voltage VA and a phase delayed by 90 degrees is applied to the piezoelectric element B which is displaced in the sliding direction to excite the piezoelectric elements A and B, the driving unit 3 causes The exercise of ~ will be repeated.

That is, since the voltage of 0 V is applied to the piezoelectric element A at the position shown in FIG. 6A, the expansion / contraction of the piezoelectric element A is "0", and the piezoelectric element B has the maximum negative voltage. 5 is applied, the drive portion 3 is deformed as shown in FIG. 5, the vertical direction of the drive piece 32 (the direction of pressing the rotors 2, 2 ') is the intermediate position, and the horizontal direction (sliding direction) is the left end. The position. Further, at the position of FIG. 6A, the piezoelectric element A has the maximum thickness because the maximum positive voltage is applied to the piezoelectric element A, and 0 V is applied to the piezoelectric element B. Is “0”, and the driving piece 32 is at the uppermost position (maximum position in the thickness direction) as shown in FIG. 6A, the voltage applied to the piezoelectric element A is 0V and the voltage applied to the piezoelectric element B is the maximum positive value. Therefore, as shown in FIG. The direction is the middle position and the left-right direction is the right end. In FIG. 6A, since the negative maximum voltage is applied to the piezoelectric element A and 0 V is applied to the piezoelectric element B,
As shown in FIG. 5, the piezoelectric element A has a minimum thickness and the piezoelectric element B has a zero slip, and the driving piece 32 has a minimum vertical direction and an intermediate lateral position.

As described above, when the piezoelectric elements A and B are driven by the excitation voltage of the sinusoidal wave having the same frequency and the phase shifted by 90 degrees, the driving piece 32 moves clockwise as shown in FIG. 7 (a). A rotating circular motion or elliptical motion is performed. Figure 7
Is the movement of the drive piece 32 in the direction of the pressure contact surfaces of the rotors 2 and 2 '(the direction of expansion and contraction of the piezoelectric element A), the Z axis, and the rotation direction of the rotors 2 and 2' (the direction of sliding of the piezoelectric element B in the rotational tangential direction). The X-axis represents the movement locus of the driving piece 32 in the X- and Z-axis planes. If the expansion stroke of the piezoelectric element A and the sliding stroke of the piezoelectric element B are the same, the driving piece 32 is in the X- and Z-axis planes. If the strokes are different, an elliptic motion with the X axis and the Z axis as the major axis or the minor axis is performed.

That is, the piezoelectric element A receives the applied voltage V
A = Ksin ωt (K is amplitude ω is angular velocity t is time), and is displaced in the Z-axis direction in proportion to this voltage VA, and the piezoelectric element B is applied with voltage VB = K'sin (ωt-π /
2) =-K'cosωt causes displacement in the X-axis direction, and assuming that the above-described strokes of the piezoelectric elements A and B excited by the excitation voltages VA and VB are the same, the driving piece 32 has Qsinωt of the Z-axis direction. Performs a simple vibration and -Qc in the X-axis direction.
A circular motion is performed by performing a simple oscillation of osωt. Further, if the amplitude K'of the excitation voltage VB applied to the piezoelectric element B is changed, the amplitude Q of the simple vibration in the X-axis direction changes, and an elliptic motion is performed as shown by broken lines L1 and L2 in FIG. 7 (a). Like

If the voltage VB applied to the piezoelectric element B is inverted by 90 degrees in phase with respect to the voltage VA by inverting the voltage VB shown in FIG. 6A as shown in FIG. As shown in FIG. 7 (b), the driving piece 32 makes a counterclockwise circular motion or an elliptic motion in which the major axis and the minor axis are the X axis and the Z axis. That is, when the voltage VB is inverted,
The positions of and in (a) are replaced with each other, and the elliptic motion becomes reverse rotation, which causes the rotors 2 and 2'to rotate in reverse.
Further, when the voltage VA is reversed, the position of FIG. 7A is reversed and the rotors 2 and 2'can be reversed. In the above description, the structure of the driving unit 3 shown in FIG. 3A has been described, but the driving unit 3 having the structure shown in FIG. 3B is used.
However, the same operation can be performed, and since it is the same as the above-mentioned operation, description thereof will be omitted.

Therefore, the drive unit 3 as described above is pressed against the rotor via the elastic pressing mechanism unit 4 as shown in FIGS. 1 and 2, and the excitation voltages VA and VB are applied to the piezoelectric elements A and B, respectively. When excited, the drive piece 32 of the drive unit 3 makes a circular motion or an elliptic motion as described above. However, when the applied excitation frequency is low, the holding unit 31 moves in correspondence with the displacement of the piezoelectric element A. The elastic pressing mechanism portion 4 is displaced against the leaf spring 5, and the contact pressure of the drive piece 32 on the contact surfaces of the rotors 2 and 2 ′ does not change much. The elastic modulus of the elastic pressing mechanism portion 4 is much smaller than that of the piezoelectric elements A and B.
Moreover, the displacement of expansion and contraction of the piezoelectric element is very small.
For example, the elastic modulus of the elastic pressing mechanism unit 4 is 1,000 N / m.
m, the elastic modulus of the piezoelectric element is 100,000 N / mm, and the expansion / contraction displacement of the piezoelectric element is 1 μm, the change in contact pressure is 1
Only about N. However, as the excitation frequency is increased, the reaction force that the piezoelectric element receives due to the inertia of the mass of the holding portion 31 increases, and the change in the rotor contact pressure correspondingly increases.

Therefore, when the excitation frequency is equal to or higher than the resonance frequency determined by the mass of the piezoelectric element, the mass of the holding portion, the combined elastic modulus of the piezoelectric element and the elastic pressing mechanism, etc., the rotor contact pressure is increased. You can make a big difference. For example, when the mass of the holding unit 31 is 1 g, the resonance frequency is calculated to be about 50 kHz, so the excitation frequency may be set higher than this. At this time, if the piezoelectric element is excited with a voltage such that the displacement without load is 1 μm, the change in the contact pressure is about 100 N in calculation. However, in reality, the elasticity that constitutes the drive unit 3 is not as calculated, and the mass is also distributed and distributed, so the resonance frequency often does not become as calculated. In this case, an impedance analyzer is used to calculate the piezoelectric element. The impedance may be measured to find the resonance point, and excitation may be performed at that frequency or a higher frequency. The maximum contact pressure change can be obtained by utilizing the resonance frequency. The resonance point is easily affected by load fluctuations and temperature fluctuations, and a slightly higher frequency has stable characteristics and is easy to use.

As described above, the excitation frequency of the excitation voltage for exciting the piezoelectric elements A and B is equal to the resonance frequency determined by the mass of the piezoelectric element, the mass of the holding portion, the combined elastic modulus of the piezoelectric element and the elastic pressing mechanism portion, and the like. Alternatively, it is possible to drive the rotors 2 and 2'by exciting the piezoelectric elements A and B at a higher frequency than that. In FIG. 7A, when the drive piece 32 moves in the direction of the rotors 2 and 2'which are moving parts → → (position above the X axis), the contact pressure to the rotors 2 and 2'increases, The rotors 2 and 2'are shown in FIG.
The drive is from left to right in (a). Further, when the driving piece 32 moves from → to → (position below the X axis), the contact pressure on the rotors 2 and 2 ′ becomes low, and the rotors 2 and 2 ′ are not driven.

As described above, since the rotors 2 and 2'are driven by the drive piece 32 of the drive unit 3 when the contact pressure is large, the amplitude of the excitation voltage VB applied to the piezoelectric element B is set to be large. The rotational speed of the rotor can be controlled by controlling and changing the elliptical shape of the movement locus of the driving piece 32 on the X and Z planes. The amplitude of the excitation voltage VB is increased to increase the displacement stroke of the piezoelectric element B, as shown in FIG.
By increasing the movement stroke of X in the X-axis direction,
If an elliptical locus such as the broken line L1 shown in FIG. 7A with the major axis in the X-axis direction is used, the amount of movement in the X-axis direction when the contact pressure on the rotors 2, 2 ′ is large →→ The rotation speed of the rotors 2 and 2'increases. Also, the excitation voltage V
If the amplitude of B is reduced and an elliptical locus with the X-axis as the short axis is set as shown by the broken line L2 in FIG. 7A, the amount of movement in the X-axis direction when the contact pressure is large → → is small. Therefore, the rotation speed of the rotors 2 and 2'will decrease. In this way, by controlling the magnitude (amplitude magnitude) of the excitation voltage VB applied to the piezoelectric element B, the rotational speed of the rotors 2, 2'can be controlled.

In the above embodiment, the excitation voltages for driving the piezoelectric elements A and B are different in phase by 90 degrees, and the driving piece 32 is circularly moved or pressed in the pressing direction (Z) to the rotors 2, 2 '.
Axis) and an example in which an elliptic motion with the rotational tangential direction (X axis) of the rotor being the major axis or the minor axis is performed in the direction orthogonal to this direction has been described. When the phase difference is other than 90 degrees and 180 degrees, the locus of the driving piece 32 makes an elliptic motion inclined on the X and Z planes in which the Z axis and the X axis do not become the long axis or the short axis. In this case, the drive unit 3 may be arranged so that the major axis or the minor axis of the ellipse and the rotational tangential direction at the contact point between the rotor 2 and the drive piece 32 of the rotor 2 or 2'are parallel to each other. FIG. 8 shows a second embodiment of the drive unit 3. In this embodiment, two piezoelectric elements A1 and A2, which are displaced in the thickness direction, are fixed in parallel on the holding portion 31 with a space therebetween, and a protrusion 3 is interposed between these two piezoelectric elements A1 and A2.
The drive piece 32 having the number 3 is fixed.

As shown in FIG. 10, the drive of the drive unit 3 is determined by the same frequency with a phase difference (as described above, the mass of the piezoelectric element, the mass of the holding unit, the combined elastic modulus of the piezoelectric element and the elastic pressing mechanism unit, etc.). The piezoelectric element A is driven by a high frequency excitation voltage having a frequency equal to or higher than the resonance frequency.
1. Exciting A2. In the example shown in FIG. 10, the excitation voltage VA2 applied to the piezoelectric element A2 is a voltage advanced in phase by α with respect to the excitation voltage VA1 applied to the piezoelectric element A1. In the state of FIG. 10, since the voltage applied to the piezoelectric element A1 is "0", the expansion and contraction is "0".
In this state, since the voltage VA2 applied to the piezoelectric element A2 is a positive value, the piezoelectric element A2 expands in accordance with this applied voltage VA2 and becomes the state shown in FIG. In addition, the drive piece 32
Is the direction of pressing the rotor contact surface (upward in FIG. 9) is the Z-axis, and the direction in which the rotors 2, 2'are rotated (pressing direction Z).
The direction perpendicular to the axis is the X axis, and the projection 33 of the drive piece 32 is
In FIG. 11 showing the loci on the X and Z planes of
Occupy the position of.

In the state of FIG. 10, the maximum positive excitation voltage VA1 is applied to the piezoelectric element A1, and the excitation voltage VA2 of about 80% of the maximum positive voltage is applied to the piezoelectric element A2. The drive unit 3 is in the state shown in FIG. 9, and the projection 33 of the drive piece 32 occupies the position projecting in the pressing direction (Z-axis direction) and occupies the position in FIG. In the state of FIG. 10, a voltage of "0" is applied to the piezoelectric element A1 and a negative voltage of about 20% of the maximum voltage is applied to the piezoelectric element A2. In the state shown in FIG. 9, the position of the protrusion 33 of the drive piece 32 becomes the position shown in FIG.

In the state of FIG. 10, the maximum negative excitation voltage VA1 is applied to the piezoelectric element A1 and about 80% of the maximum negative voltage is applied to the piezoelectric element A2. Shows the state of FIG. 9 and the projection 3 of the driving piece 32.
3 has the position shown in FIG. As a result, the protrusion 33 of the driving piece 32 makes a substantially elliptic motion as shown in FIG. 11 in the order of →→→→→, and the one above the X axis in FIG. 11 (first and first in the X and Z planes). During the movement in the two quadrants (between approximately →→), the contact pressure with which the drive unit 3 presses the rotor contact surface increases, drives the rotors 2 and 2 ′, and the contact pressure decreases. During the movement of the lower portion (approximately →→), the operation of only returning without driving the rotors 2 and 2 ′ is performed.

When the rotation directions of the rotors 2 and 2'are changed, the excitation voltages VA1 and VA2 for exciting the piezoelectric elements A1 and A2.
Either one of the above may be inverted. For example, when the excitation voltage VA1 is reversed, the positions of and are reversed in FIG. 11, the protrusion 33 of the drive piece 32 rotates counterclockwise, and the rotors 2 and 2'are reversed. Further, when the excitation voltage VA2 is reversed, the positions of and are reversed in FIG. 11, the projection 33 of the driving piece 32 rotates counterclockwise, and the rotors 2 and 2'are reversed.

The rotation speed of the rotors 2 and 2'is controlled by controlling the phase difference α of the excitation voltage applied to the piezoelectric elements A1 and A2.
Can be controlled by changing. However, the piezoelectric element A
1, when the phase difference α of the excitation voltage applied to A2 is set to "0", the reciprocating stroke of the protrusion 33 of the driving piece 32 in the Z-axis direction (movement in the rotor pressing direction) becomes maximum, and the rotor 2,
Although the change in the contact pressure to 2'becomes the maximum, the reciprocating stroke in the X-axis direction (the direction in which the rotors 2, 2'are rotated) is "0" and the rotor cannot be driven. Further, when the phase difference α is 180 degrees, the reciprocating stroke of the projection 33 of the driving piece 32 in the X-axis direction (the direction in which the rotors 2, 2 ′ are rotated) becomes maximum, but the movement in the Z-axis direction (rotor pressing) is performed. (Movement in the direction) and the change in contact pressure with the rotors 2 and 2 ′ is minimized (the driving piece 32 only swings starting from the intermediate point thereof, and the pressing force increases due to the inclination of the protrusion). In some cases, the pressing force applied to the rotors 2 and 2'is insufficient and driving cannot be performed. Therefore, in this embodiment, the speed is controlled by controlling the phase difference α from a value exceeding 0 to a value less than 180 degrees.

FIG. 12 shows a third embodiment of the drive unit 3,
In the embodiment of the drive unit 3 shown in FIG. 8 described above, one more piezoelectric element that is displaced in the thickness direction in order to increase the contact pressure to the rotors 2 and 2'is added. 12
In the embodiment shown in (a), two piezoelectric elements A1 and A2, which are displaced in the thickness direction, are fixed in parallel on a holding portion 31, and a plate 34 is fixed on these piezoelectric elements A1 and A2. A piezoelectric element A3 that is displaced in the thickness direction is fixed to an intermediate position of the plate 34 (an intermediate position between the piezoelectric elements A1 and A2), and the driving piece 32 is fixed to the piezoelectric element A3. In the embodiment shown in FIG. 12B, the piezoelectric element A3 which is displaced in the thickness direction is fixed on the holding portion 31, and two piezoelectric elements A1 which are displaced in the thickness direction are provided on the piezoelectric element A3.
A2 are fixed in parallel with a space between them, and these piezoelectric elements A
A drive piece 32 having a protrusion 33 in the middle is fixedly attached to 1 and A2.

If there is no piezoelectric element A3, it is the same as the embodiment shown in FIG. 8, and as shown in FIG.
If the excitation voltage of the same frequency is excited with a phase difference α with respect to 2, the driving piece 32 (protrusion 33) will move as shown in FIG. In the third embodiment, a piezoelectric element A3 is further added to drive the driving piece 3
2 (protrusion 33) is further displaced in the contact surface direction of the rotor (Z-axis direction). In FIG. 11, the piezoelectric element A3 is extended so as to extend above the X axis (between approximately →→) and to shorten the piezoelectric element A3 below the X axis (approximately →→). When the excitation voltage is applied, the reciprocating stroke of the drive piece 32 in the rotor pressure contact direction (Z-axis direction) is increased, so that the contact pressure applied when the drive unit rotors 2, 2 ′ are rotated is increased, which is large. Torque can be generated.

Further, the drive unit 3 of the second embodiment shown in FIG.
Then, when the phase difference between the excitation voltages applied to the piezoelectric elements A1 and A2 was set to 180 degrees, the stroke of the drive piece 32 (protrusion 33) in the rotor pressure contact direction (Z-axis direction) was minimized. In the third embodiment shown in FIGS. 12 (a) and 12 (b), since the stroke in the rotor pressure contact direction (Z-axis direction) is generated by the piezoelectric element A3, it is applied to the piezoelectric elements A1 and A2. Excitation voltage phase difference is 180
The rotors 2 and 2'can be driven even in degrees. FIG. 14 shows high frequencies (the mass of the piezoelectric element, the mass of the holding section, the piezoelectric element and the elasticity of the holding section as described above) in the piezoelectric elements A1 to A3 of the driving unit 3 of the third embodiment shown in FIGS. Excitation voltage VA1 with a frequency equal to or higher than the resonance frequency determined by the composite elastic modulus of the pressing mechanism.
This is an example of driving by applying ~ VA3. The excitation voltage VA1 applied to the piezoelectric element A1 has a 90 degree phase delay with respect to the excitation voltage VA3 applied to the piezoelectric element A3, and the excitation voltage VA2 applied to the piezoelectric element A2 is the inverse of the excitation voltage VA1. 180 degrees out of phase. Further, FIG. 13 is a diagram showing a change state of the drive unit 3 shown in FIG. 12A when the piezoelectric elements A1 to A3 are excited by such excitation voltages VA1 to VA3, and FIG. FIG. 7 is a diagram showing a movement locus of the drive piece 32 (protrusion 33) with the Z-axis as a pressure contact direction of the piece 32 to the rotors 2 and 2 ′ and the X-axis as a rotor rotation direction (rotation tangential direction).

In the state shown in FIG. 14, the piezoelectric element A
Since a voltage of "0" is applied to 3, the amount of expansion and contraction is "0", and it takes an intermediate position. Further, since the maximum negative voltage is applied to the piezoelectric element A1, the state is shortened to the maximum, and the piezoelectric element A2 is extended to the maximum because the maximum voltage is applied, resulting in the state shown in FIG.
The drive piece 32 (projection 33) is in the intermediate position in the Z-axis direction and at the left end in the X-axis direction, as shown in FIG. In the state of FIG. 14, the maximum voltage is applied to the piezoelectric element A3, and the piezoelectric element A1
, A2 is applied with a voltage of "0", the piezoelectric element A3 is expanded to the maximum, and the piezoelectric elements A1 and A2 are expanded and contracted to "0".
13 and the state shown in FIG. 13 is reached.
2 (protrusion 33) is the intermediate position in the X-axis direction and the maximum position in the Z-axis direction, which is the position shown in FIG.

In the state shown in FIG. 14, a voltage of 0 is applied to the piezoelectric element A3, and the expansion / contraction amount is at an intermediate position where the expansion / contraction amount is "0". The piezoelectric elements A1 and A2 respectively have the maximum positive voltage and the maximum negative voltage. Is applied, the maximum extension and the maximum reduction are achieved, and the state of FIG.
The position of 3) is the position of FIG. In the state of FIG. 14, the maximum negative voltage is applied to the piezoelectric element A3, and the voltage of "0" is applied to the piezoelectric elements A1 and A2. Therefore, the piezoelectric element A3 is shortened to the maximum. , Piezoelectric elements A1 and A2 are in the middle position with expansion and contraction "0", and drive piece 3
2 (protrusion 33) takes the position shown in FIG. As described above, when the excitation voltages VA1 to VA3 as shown in FIG. 14 are applied to the piezoelectric elements A1 to A3, the driving piece 32 (protrusion 33).
15 makes a circular or substantially elliptical motion that rotates clockwise →→→→→ as shown in FIG. When the driving piece 32 (protrusion 33) moves →→, the contact pressure against the rotors 2 and 2 ′ is large, and when it moves →→→, the contact pressure is low, and the rotors 2 and 2 ′ are driven in the direction from to in FIG. Will be.

Further, if the excitation voltage VA3 is inverted and applied to the piezoelectric element A3 in FIG. 14, the position is replaced with the position in FIG. 15, and the driving piece 32 (protrusion 33).
Rotates counterclockwise on the X and Z planes, and the rotors 2 and 2'can be rotated in opposite directions. Also,
The rotor can also be rotated in reverse by reversing the excitation voltage applied to the piezoelectric elements A1 and A2. That is, in FIG. 14, the excitation voltage VA3 is applied to the piezoelectric element A3,
When the excitation voltage VA2 is applied to the piezoelectric element A1 and the excitation voltage VA1 is applied to the piezoelectric element A2, the positions are replaced with those in FIG. 15, and the driving piece 32 (protrusion 33) rotates counterclockwise in FIG. 2'will be rotated in the opposite direction. Further, in the driving example shown in FIG.
The excitation voltages applied to the piezoelectric elements A1 and A2 are assumed to have a phase difference of 180 degrees. However, if a phase difference other than 180 degrees is taken, the midpoint between the piezoelectric elements A1 and A2 is the second embodiment of the drive section. The elliptic locus of FIG. Therefore, according to this elliptical locus, the rotor 2 of the piezoelectric element A3,
If the piezoelectric element A3 is excited so that the contact pressure on 2'is increased, the contact pressure is further increased. That is, in FIG. 11, the piezoelectric element A3 may be excited so as to extend when it is above the X axis (→→).

FIG. 16 shows an embodiment of the first drive section (FIG. 3).
It is a block diagram of a drive control circuit of (a), (b).
A high-frequency sinusoidal voltage is generated from the oscillator 51, and the voltage obtained by shifting the phase of the signal from the oscillator 51 by the phase shift circuit 52 is used as the excitation voltage VA of the piezoelectric element A.
Further, the voltage from the oscillator 51 is input to the amplification degree control circuit 53, the amplification degree is increased or decreased according to the speed control signal, and output.
The output of the amplification degree control circuit 53 is output to the selection circuit 55, the phase is inverted by the phase inversion circuit 54, and then output to the selection circuit 54. The selection circuit 55 selects a signal whose phase is not inverted or an inverted signal according to the direction selection signal and outputs it as the excitation voltage VB to the piezoelectric element B to excite the piezoelectric element B.

The drive unit 3 is constructed by the drive control circuit as described above.
The rotors 2 and 2 ′ can be driven and rotated by driving the rotors 2 and 2 ′, and the magnitude of the excitation voltage VB applied to the piezoelectric element B by the amplification control circuit is controlled by the speed control signal. Control the rotation speed,
Excitation voltage V applied to the piezoelectric element B by the direction selection signal
The rotation direction of the rotors 2 and 2'can be selected depending on whether or not B is inverted. In the first embodiment of the drive unit 3, when driving is performed with the excitation voltages VA and VB having a 90-degree phase shift as shown in FIG. 6, the phase shift circuit 52 advances the 90-degree phase to advance the excitation voltage. You can use VA.

FIG. 17 shows a second embodiment of the drive unit 3 (FIG. 8).
FIG. 3 is a block diagram of a drive control circuit that drives a drive circuit. Compared with this drive control circuit and the drive control circuit of the first embodiment of the drive section shown in FIG. 16, the amplification control circuit is eliminated and the speed control signal is input to the phase shift circuit 52. The phase shift circuit 52 is configured so that the phase shift amount can be changed by a speed control signal, and the speed control of the rotors 2, 2'is performed by changing the phase shift amount of the phase shift circuit 52. High frequency output from the oscillator 51 (equal to the above-mentioned resonance frequency,
The voltage of higher frequency) is shifted by the amount α according to the speed control signal by the phase shift circuit 52 (delayed by α in the example shown in FIG. 10) and output as the excitation voltage VA1 to the piezoelectric element A1. Then, the piezoelectric element A1 is excited. In addition, the high frequency voltage output from the oscillator 51,
A voltage obtained by inverting the high frequency voltage by the phase inversion circuit 54 is selected by the selection circuit 55 according to the direction selection signal, and is set as the excitation voltage VA2 of the piezoelectric element A2 to excite the piezoelectric element A2. As a result, as described in FIGS. 9 to 11,
The piezoelectric elements A1 and A2 are excited with a phase difference, and the drive piece 33 of the drive unit 3 makes an elliptic motion to rotate the rotors 2 and 2 '.

FIG. 18 is a drive control circuit for driving and controlling the third embodiment of the drive section 3 shown in FIG. 12, in which the selection circuit 55 in FIG. 17 is changed and the phase shift circuit 56.
Is the point that is newly added. The phase of the high-frequency voltage output from the oscillator 51 is shifted by a set amount by the phase shift circuit 52 (advance the phase by 90 degrees in the example of FIG. 14) to obtain the excitation voltage VA3 of the piezoelectric element A3. Further, the output of the oscillator 51 and the output obtained by inverting the phase of the output by the phase inversion circuit 54 are input to the selection circuit 55 ', and in the selection circuit 55', the piezoelectric elements A1 and A2 are switched by the switches which are interlocked with each other by the direction selection signal. As the excitation voltages VA1 and VA2, one is the high frequency voltage itself output from the oscillator 51 and the other is the one inverted by the phase inversion circuit 54, and the excitation voltage of the piezoelectric element A2 is further input to the phase shift circuit 56. Then, the phase is shifted with respect to the excitation voltage of the piezoelectric element A1 corresponding to the speed control signal, and the excitation voltage VA2 of the piezoelectric element A2 is shifted.
And

As a result, the excitation voltage applied to the piezoelectric elements A1 and A2 is selected by the direction selection signal and the rotors 2 and 2 are selected.
The rotation direction of the rotors 2 and 2'is controlled by selecting the rotation direction of the rotation speed control signal ′ and shifting the phases of the excitation voltages VA1 and VA2 by the speed control signal.

In the above-described embodiment, the rotors 2 and 2 on the cylinder are
′, Or the piezoelectric motor constituted by the rotor 2 ′ on the disk, the present invention drives the moving part by contact pressure, so the rotor is not necessarily cylindrical or disk-shaped. It is not limited, and any moving unit can be driven as long as it has a flat surface or a peripheral surface. FIG. 19 shows an embodiment of a piezoelectric spherical motor that drives a spherical surface. A spherical bearing 63 slidably supports a sphere 61 so that the output shaft 62 can be moved. The drive unit 3 of the first to third embodiments described above is used as the drive unit. That is, the tip end (driving piece) of the drive unit 3 is pressed against the spherical surface by the leaf spring 5 of the elastic pressing mechanism unit 4, and the piezoelectric element of the drive unit is driven by the above-described method to rotate the sphere and output shaft thereof. 62 is moved.

FIG. 20 shows an example of a piezoelectric linear motor. FIG. 20 (a) is a front view and FIG. 20 (b) is a side view. On the side surface of the slider 65 slidably held by a guide member 66 such as a cross roller bearing or a linear guide on the slider base 64, the drive unit 3 of the above-described first to third embodiments is elastically pressed. The slider 65 is being pressed by 4 and is driven by the above-mentioned method to move the slider 65 left and right in FIG. 20 (b).

FIG. 21 is a diagram showing a fourth embodiment of the drive section 3. In the first to third embodiments, the moving part is moved in one direction, but in the fourth embodiment, the moving part can be moved in two directions. In the fourth embodiment, the piezoelectric element A which is displaced in the thickness direction is fixed on the holding portion 31, the piezoelectric element B1 which is displaced in the sliding direction is fixed on the piezoelectric element A, and the piezoelectric element B1 is fixed. The piezoelectric element B2, which slides in a direction orthogonal to the sliding direction of the piezoelectric element B, is fixed to the upper portion, and the driving piece 32 is fixed to the uppermost portion. Note that the piezoelectric elements A, B1, and B2 need not be fixed in the order shown in FIG. 21, and as shown in FIG.
Or if it sticks to A, B2 or B1
It may be fixed to 1, A and B2 or may be in another form.
If the direction in which the drive unit 3 presses the moving unit (the direction in which the piezoelectric element A expands and contracts) is the Z-axis direction, and the directions orthogonal to the Z direction and mutually orthogonal are the X-axis direction and the Y-axis direction, the Z-axis is defined. Piezoelectric element A that expands and contracts in the direction and piezoelectric element B1 that slides in the X-axis direction
(Or B2) and the piezoelectric element B2 (or B1) sliding in the Y-axis direction may be simply laminated regardless of the laminating order.

The operation of the two-direction driving section 3 is shown in FIG.
It is based on the same principle as the operation of the drive unit of the first embodiment shown in, except that the moving unit is moved in two directions. That is, the piezoelectric element A is extended to drive the piezoelectric element B1 which is displaced in the sliding direction while the pressing force to the moving portion is increasing, and the moving portion is moved in the sliding direction as compared with the first embodiment. It is the same. Further, when the piezoelectric element B2 is excited, the moving portion can be moved in a direction orthogonal to the moving direction when the piezoelectric element B1 is excited. In this case also, the operation principle is explained in the first embodiment of FIG. It is the same as when I did it. And the piezoelectric element B1,
If B2 is driven at the same time, the moving part can be driven in a direction in which the sliding directions of the piezoelectric elements B1 and B2 in the two sliding directions are combined.

If this two-direction drive unit is used for the spherical surface drive shown in FIG. 19, the sphere 61 can be rotated in any direction. Also, as shown in FIG. 22, if a piezoelectric plane motor is used as a drive unit for a slider that can move in two directions, the slider can be moved in the X and Y planes in the X and Y directions, and in any combined direction. Can be driven. 22A is a plan view of this piezoelectric planar motor, and FIG. 22B is a side view thereof. A pair of guide rails 71 provided on a base 70 are slidably fitted with guides 72, respectively. A pair of shafts 73, 73 is stretched between the guides 72, 72, and the shafts 73, 7
A slider 74 is slidably fitted to the unit 3. Further, the holding portion 31 of the two-way driving unit 3 shown in FIG. 21 is fixed to the leaf spring 75 fixed to the base 70 as the elastic pressing mechanism unit 4, and the driving piece 32 of the driving unit is the lower surface of the slider 74. Has been pressed. And the guide rail 7
The moving direction of the guide 72 moving 1 is the Y-axis, the moving direction of the slider along the shaft 73 is the X-axis, and the sliding directions of the piezoelectric elements B1 and B2 of the drive unit are the X-axis direction and the Y-axis direction.
The drive unit is arranged so as to be parallel to the axial direction.

Then, the piezoelectric element A is excited to drive the piezoelectric element B1.
, B2 can be selectively moved to move the slider 74 in the X-axis direction or the Y-axis direction. If the piezoelectric elements B1 and B2 are simultaneously excited, the piezoelectric element B1 can be moved.
, B2 can be moved in the direction in which the slips are combined. FIG. 23 is a block diagram of the drive control circuit of the bidirectional drive section, in which the selection circuit 55 ″ in the drive control circuit of FIG. 16 is replaced with the selection circuit 55 ″ as shown in the figure. The phase of the high frequency voltage output from 51 is advanced or delayed by 90 degrees and another voltage is set as the excitation voltage VA of the piezoelectric element A. Then, the selection circuit 55 "uses the oscillator 51 as the excitation voltages VB1 and VB2 for the piezoelectric elements B1 and B2. The high-frequency voltage output from the output terminal, the inverted voltage thereof, or the voltage "0" is output according to each direction selection signal. (In FIG. 23, the X-axis direction selection signal, Y
The piezoelectric element B1 drives the moving part (slider 74) in the X-axis direction, and the piezoelectric element B2 outputs Y.
It is assumed that the moving portion (slider 74) is driven in the axial direction).

As a result, the amplitude of the excitation voltage applied to the piezoelectric elements B1 and B2 is increased / decreased by the amplification degree control circuit 53 according to the speed control signal to control the moving speed of the moving part and at the same time in the X and Y directions. Selection circuit 5 according to selection signal
Switch the 5 "switch to change the moving direction of the moving part to the X-axis +,
The moving portion is moved in a direction in which the movements of the − direction, the Y axis + and − directions, and the X axis and the Y axis are combined. The driving piece of the driving unit 3 is easily worn because it comes into contact with the moving unit. Therefore, hard ceramics are usually used to prevent wear. Further, when the driving piece 32 is provided on the piezoelectric element,
When the surface of the piezoelectric element is hard and wear is not a problem, the driving piece 32 may be omitted and the surface of the piezoelectric element may be used as the driving piece.

Further, in the above embodiment, the speed of the moving part is controlled by changing the amplitude of the excitation voltage of the piezoelectric element or the amount of phase shift, but the frequency of the excitation voltage for exciting the piezoelectric element, that is, The speed of the moving unit may be controlled by changing the oscillation frequency of the oscillator 51 in the region above the resonance frequency. Furthermore, in the above-described embodiment, an example in which one driving unit is provided for the moving unit has been described, but a plurality of driving units can be provided for one moving unit to increase torque and thrust. In this case, the same excitation voltage may be used, but two sets of waveforms whose phases are shifted by 180 degrees or three sets of waveforms whose phase are shifted by 120 degrees or nine phases are used.
Exciting the respective drive units with four sets of waveforms shifted by 0 degrees reduces ripples in torque and thrust and enables smoother movement.

[0056]

According to the piezoelectric motor of each invention of the present application, the contact portion between the drive unit and the moving unit driven by the drive unit causes a circular or elliptical motion in the drive unit, and the contact pressure is increased during the period. Since the motor drives the moving portion by moving the contact portion (driving piece) of the driving body in a direction orthogonal to the contact pressure direction, a large torque can be generated. Also, the drive speed of the moving part (rotor) can be controlled by changing the amplitude or phase difference of the high-frequency voltage that excites the piezoelectric element, the speed control can be simplified, and the moving direction of the moving part can be changed only by reversing the exciting voltage. Since it can be changed, the moving direction and speed of the piezoelectric motor can be easily controlled. Further, since the contact part of the driving body moves in the direction opposite to the moving direction of the moving part during the period when the contact pressure between the moving part and the driving part in the circular or elliptic motion is small, the contact pressure becomes small. The wear of the parts is small and the life of the motor can be extended. Furthermore, since it is a motor that moves the moving part by contact pressure, the moving part may have a surface that contacts the driving part,
The rotor may be a cylindrical rotor, a disc rotor, a sphere, or a slider that moves in a plane, and piezoelectric motors of various shapes can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a first embodiment of a drive unit used in the first and second embodiments of the present invention.

FIG. 4 is an explanatory diagram of a piezoelectric element.

FIG. 5 is a diagram illustrating an operating state of the drive unit shown in FIG.

FIG. 6 is an explanatory diagram of an excitation voltage for exciting each piezoelectric element in the drive unit according to the first embodiment.

FIG. 7 is an explanatory diagram illustrating a movement locus of the driving piece at the tip of the driving unit in the first example of the driving unit.

FIG. 8 is a diagram showing a configuration of a second example of a drive unit.

FIG. 9 is an explanatory diagram illustrating an operating state of the second embodiment of the drive section.

FIG. 10 is an explanatory diagram of an excitation voltage for exciting each piezoelectric element in the second example of the drive unit.

FIG. 11 is an explanatory diagram illustrating a movement locus of the drive piece at the tip of the drive unit in the second example of the drive unit.

FIG. 12 is a diagram showing a configuration of a drive unit according to a third embodiment.

FIG. 13 is a diagram illustrating an operating state of the drive unit according to the third embodiment illustrated in FIG.

FIG. 14 is an explanatory diagram of an excitation voltage for exciting each piezoelectric element in the drive unit according to the third embodiment.

FIG. 15 is an explanatory diagram illustrating a movement locus of a driving piece at the tip of the driving unit in the third example of the driving unit.

FIG. 16 is a block diagram of a drive control circuit that drives a first embodiment of the drive unit.

FIG. 17 is a block diagram of a drive control circuit that drives a second embodiment of the drive unit.

FIG. 18 is a block diagram of a drive control circuit that drives a third embodiment of the drive unit.

FIG. 19 is a diagram showing a configuration of an embodiment of a piezoelectric spherical motor for driving a spherical surface of the present invention.

FIG. 20 is a diagram showing a configuration of a piezoelectric linear motor according to an embodiment of the present invention.

FIG. 21 is a diagram showing the configuration of a two-way drive unit according to a fourth embodiment of the drive unit of the present invention.

FIG. 22 is a diagram showing the configuration of an embodiment of the piezoelectric planar motor of the present invention driven by a two-way drive unit.

FIG. 23 is a block diagram of a drive control circuit of a two-way drive unit.

[Explanation of symbols]

 2 Cylindrical rotor 2'Disk-shaped rotor 3 Drive part 4 Elastic pressing mechanism part 5, 75 Leaf spring 6 Base A, A1, A2, A3 Piezoelectric element B, B1, B2 displaced in the thickness direction Piezoelectric element displaced in the sliding direction 31 holding part 32 driving piece 33 protrusion 61 ball 62 output shaft 65, 74 slider 72 guide

Claims (18)

[Claims] 1. A motor for driving a moving part by a frictional force, a driving piece contacting the moving part, a first piezoelectric element for controlling a contact pressure between the driving piece and the moving part, and the driving piece. A driving unit having a holding unit for holding the second piezoelectric element for displacing the moving unit in the moving direction of the moving unit; an elastic pressing mechanism unit for pressing the driving unit against the moving unit; and the first and second piezoelectric elements. A drive control means for exciting with high-frequency voltages having the same frequency and different phases, changing the contact pressure between the moving part and the driving body, and displacing the second piezoelectric element during a period when the contact pressure is high. Piezoelectric motor to move. 2. The drive unit is configured by bonding the drive piece, a first piezoelectric element that is displaced in the pressing thickness direction, and a second piezoelectric element that is displaced in a direction orthogonal to the thickness direction, in an overlapping manner. The piezoelectric motor according to claim 1, wherein 3. In a motor of a type in which a moving portion is driven by frictional force, piezoelectric elements that are displaced in the thickness direction are arranged on a holding portion at intervals, and the moving portion moves to a midpoint across the two piezoelectric elements. A drive section having a drive piece having a protrusion for pressing the elastic section, an elastic pressing mechanism section for pressing the drive section against the moving section, and the two piezoelectric elements are excited by high-frequency voltages having the same frequency but different phases. A piezoelectric motor comprising: a drive control means for displacing a piezoelectric element with a phase difference; and moving the moving piece by moving the driving piece while changing the contact pressure of the projection of the driving piece to the moving portion. 4. In a motor of a type in which a moving portion is driven by frictional force, two second piezoelectric elements which are displaced in the thickness direction are arranged on a holding portion at intervals, and the two second piezoelectric elements are arranged. A drive unit in which a plate is disposed over the plate, and a first piezoelectric element that has a drive piece on the upper surface is disposed between the two second piezoelectric elements on the plate and that is displaced in the thickness direction; And an elastic pressing mechanism that presses the moving part on the moving part and the two second piezoelectric elements are excited by high frequency voltages having the same frequency and different phases to displace with a phase difference, and the first piezoelectric element also has the same frequency. Drive control means for changing the phase so as to change the displacement of the first piezoelectric element in synchronism with the movement of the intermediate position of the plate on which the second piezoelectric element is arranged in the direction of the moving portion, and for exciting with a high frequency voltage. To the moving part by the projection of the driving piece. A piezoelectric motor that moves the moving part by moving the driving piece while changing the contact pressure. 5. In a motor of a type that drives a moving portion by frictional force, a second piezoelectric element that is displaced in the thickness direction is provided on a first piezoelectric element that is disposed on a holding portion and that is displaced in the thickness direction. And a drive unit having a drive piece having a protrusion that presses the moving unit at a midpoint over the two second piezoelectric elements, and an elastic pressing mechanism that presses the driving unit against the moving unit. Section and the two second piezoelectric elements are excited by high frequency voltages having the same frequency and different phases to be displaced with a phase difference, and the first piezoelectric element is also provided with the second piezoelectric element at the same frequency. Drive control means for changing the phase so as to change the displacement of the first piezoelectric element in synchronization with the movement of the intermediate position of the plate in the direction of the moving portion, and exciting the plate with a high frequency voltage. Change the contact pressure to the moving part. A piezoelectric motor that moves the moving part by moving the driving piece while moving. 6. A motor for driving a moving part by a frictional force, a driving piece contacting the moving part, a first piezoelectric element for controlling a contact pressure between the driving piece and the moving part, and the driving piece. A drive part having a holding part for holding two second piezoelectric elements that are displaced in a direction orthogonal to the pressure contact direction of the drive piece and the moving part and in a direction orthogonal to each other, and an elastic pressing force for pressing the driving part against the moving part. And a drive control unit that excites the first piezoelectric element with a high frequency voltage and selects the second piezoelectric element and drives the second piezoelectric element with a high frequency voltage having the same frequency as the high frequency voltage but a different phase. A piezoelectric motor that changes a contact pressure between a drive section and a drive section, and moves a moving section by displacement of the second piezoelectric element while the contact pressure is high. 7. The driving piece is constituted by the surface of the first piezoelectric element or the surface of the second piezoelectric element.
Piezoelectric motor described. 8. The piezoelectric motor according to claim 1, 2 or 6, wherein the drive control means includes means for changing the amplitude of a high frequency voltage for exciting the second piezoelectric element. 9. The piezoelectric motor according to claim 3, wherein the drive control means includes means for changing a phase of a high frequency voltage for exciting the two piezoelectric elements. 10. The drive control means includes the two second
6. The piezoelectric motor according to claim 4, further comprising means for changing a phase of a high frequency voltage for exciting the piezoelectric element. 11. The high frequency voltage generated by the drive control means has a high frequency with which an inertial reaction force is obtained in the first piezoelectric element with respect to the mass of the holding portion. The piezoelectric motor according to item 1. 12. The drive control means comprises means for inverting the phase of at least one of the high frequency voltages for exciting the first and second piezoelectric elements.
The piezoelectric motor according to 5, 6, 7 or 8. 13. The piezoelectric motor according to claim 3, wherein the drive control means includes means for inverting the phase of a high-frequency voltage that excites two piezoelectric elements arranged at the interval. 14. The piezoelectric motor according to claim 1, wherein the drive control means includes an oscillator capable of changing the frequency of the high frequency voltage generated. 15. The piezoelectric motor according to claim 1, wherein the moving portion is a cylindrical rotor. 16. The piezoelectric motor according to claim 1, wherein the moving portion is a disk-shaped rotor. 17. The moving unit is a sphere, and the moving unit is a sphere.
The piezoelectric motor according to item 1 of item 4. 18. The piezoelectric motor according to claim 1, wherein the moving portion is a slider that moves on a plane.