JP2000308374A - Screw rod drive mechanism by ultrasonic-wave vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a vibrator to change phase of voltage to be impressed to a couple of piezoelectric actuators in order to improve the operation efficiency of normal rotation and inverse rotation and eliminate useless operation. SOLUTION: A vibrator 10 to which a voltage actuator is connected and fixed is inserted into a vibrator holder 13 and moreover it is then inserted to a vibrator supporting plate 7 so that the vibrator holder 13 can rotate. The vibrator 10 is provided to a screw rod 8 to elastically operate with a spring 11 in the screw groove, so that the vibrator holder 13 can rotate around the inserting part of the vibrator supporting plate 7. A moving base 6 is moved in the axial direction of the screw rod 8 with rotation thereof, and thereby the vibrator 10 wherein the piezoelectric actuator is connected and fixed to the rotating drive source of the screw rod 8 is provided to the groove of the screw rod, resulting in the elastic operation to give ultrasonic-wave vibration for the rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor driving method, and more particularly, to a method of driving a screw rod by an ultrasonic driver and a driving mechanism thereof.

[0002]

2. Description of the Related Art As a conventional screw rod driving method, a ball screw method is generally used. For example, there is a servo motor driving mechanism as shown in FIG. The basic shape of the ball screw shown here is the same as the screw rod, and is a screw rod used by combining a ball and a ball nut, and is distinguished from the screw rod. In the figure, reference numeral 31 denotes a ball screw servo motor driving mechanism;
Is a ball screw, 33 is a ball screw receiving stand, 34 is a bearing, 35 is a ball nut, 36 is a ball, 37 is a coupling, and 38 is a servomotor.

As is apparent from FIG. 1, the conventional servo motor driving mechanism has a ball screw 32 for inserting a ball 36, and this ball screw 32 is
The ball screw is mounted between the ball screw receiving bases 33 and 33 via the ball screws 4 and 34, and a ball nut having a ball 36 therein is mounted on the ball screw 32. Further, one end of the ball screw 32 is connected to a coupling 37 which is linked to a servo motor 38. That is, the ball nut 3 sealed with the ball 36 is mounted on the ball screw receiving base 33.
5 is set so that the ball screw 32 can rotate, and a servo motor 38 is connected to one end of the ball screw 32 by a coupling 37. And the servo motor 3
By rotating the ball screw 32 forward or backward, the ball screw 32 is rotated to move the ball nut 35 in the axial direction of the ball screw 32.

This conventional mechanism controls the right and left rotation of a servo motor 38 via a coupling 37 by a ball screw 32.
The ball nut 35 is moved in the axial direction of the ball screw 32 via the ball 36 contained in the ball nut 35 by the conduction of the ball nut 35. Since the rails and sliders (not shown) are used to move the work, the ball screws 32 are used so that the load is not applied in the radial direction.

[0005] The ball screw type using such a conventional servo motor driving mechanism has a number of defects or problems as follows. A) In the combination of a ball screw and a ball nut, a minimum gap always occurs, so that an obstacle due to rattling always occurs. Since a ball, a ball nut, a servomotor, and the like are required for smooth rotation, there are many problems in reducing the space and saving energy. C. By using for a long time, the wear between the ball, the ball nut and the ball screw increases, so that the backlash increases and the backlash increases. D. In the ball screw mechanism, a lot of effort is required because there is a contradiction that the rotational wear must be kept close to zero and the backlash must be minimized.

In order to solve the problems of the conventional mechanism,
For example, there is a method of driving a screw rod by ultrasonic vibration developed by the present applicant (Japanese Patent Application No. 10-140655). In this driving method, a vibrator and a piezoelectric actuator are integrated and elastically mounted on a screw rod via a spring, and a constant pressure is applied from the vibrator to the periphery of the screw rod to always give a large friction to the screw rod.
And a screw rod driving method by ultrasonic vibration characterized by applying a clockwise or counterclockwise rotating voltage to either the right side or the left side of the vibrator. This is a driving method in which a micro-voltage is applied to a vibrator that is not electrically conductive to reduce the frictional resistance of the vibrator, and a micro-vibration is applied.The contact pressure between the vibrator and the screw rod is received by a tapered portion to reduce the strength of the contact pressure. A screw rod driving method determined by a compression force of a spring, and a driving method in which a stationary position is stabilized and a frictional resistance is maximized by a contact pressure of a tapered portion when each voltage to the vibrator is OFF. This is a driving method in which even if the friction portion of the vibrator is slightly worn, it is automatically adjusted without any backlash.

[0007] Further, a screw rod is provided in which the vibrator and the piezoelectric actuator are integrated with each other and mounted via a bearing, and a constant pressure is applied from the vibrator to the periphery of the screw rod by a spring to always produce a large friction. The present invention provides a screw rod drive mechanism by ultrasonic vibration characterized by providing a screw rod drive by ultrasonic vibration in which a tip end of the vibrator is elastically provided on a screw rod. In providing the mechanism.

That is, in the processing accuracy using conventionally used ball nuts, balls, ball screws, etc., the finishing is performed with ultra-precision processing accuracy in order to minimize rattling. While a single-axis robot is formed by a combination with a servomotor, in the present invention, since several tips of the vibrator are always pressed against the V-groove of the screw rod, the end of the vibrator can be loose even in a finish with normal machining accuracy. The transducer cradle is always set in a stable state.

More specifically, as shown in FIGS. 6 and 7, the screw rod 22 is
A vibrator pedestal 25 having a piezoelectric actuator 26 attached to the screw rod 22 is fitted between the screw rods 22.
That is, the screw rod 22 is supported between bearings 24, 24 between the screw rod receiving bases 23, 23.
Is mounted, and a vibrator and a piezoelectric actuator 26 are integrally formed on a vibrator pedestal 25 and set with a spring locking tool 29 so as to compress a spring 28. By setting the vibrator in this manner, the vibrator is pressed with a constant pressure around the screw rod 22 so that a large friction is always applied.

[0010]

The improvement of the conventional method of driving a screw rod by ultrasonic vibration as described above has an object to be solved by the present invention.

[0011]

SUMMARY OF THE INVENTION The present invention has been developed to solve the above-mentioned problems, and a constant pressure is applied to the periphery of the screw rod by an ultrasonic vibrator to apply friction to the screw rod. In the method of driving a screw rod by an ultrasonic vibrator to be provided, a piezoelectric actuator is joined to a corner of the vibrator, and two legs are elastically provided in a groove portion opposed to a central shaft portion of the screw rod via a spring, A constant pressure is applied to the periphery of the screw rod from the vibrator to always apply a large friction to the screw rod, and the phase of the voltage applied to the two piezoelectric actuators is changed and set. Another object of the present invention is to provide a screw rod driving method using an ultrasonic vibrator characterized by changing

The present invention also provides a screw rod drive mechanism using an ultrasonic vibrator for applying a constant pressure to the periphery of a screw rod by an ultrasonic vibrator to apply friction to the screw rod. Mounted between the bearing side plates fixed to the bearing and supported on both ends of the screw rod by pairing.Furthermore, the piezoelectric actuator is adhesively fixed to the vibrator and inserted into the vibrator holder. It is to provide a screw rod drive mechanism by an ultrasonic vibrator, wherein the vibrator is mounted on the screw rod in a rotatable state around the insertion portion of the vibrator support plate. In the driving mechanism of the screw rod by the ultrasonic vibrator, the vibrator is driven by a voltage applied to two piezoelectric actuators. Certain forward and reverse action by changing phase to provide a screw rod drive mechanism according to the ultrasonic vibrator to a high efficiency.

That is, the feature of the present invention is that, among the conventional method of driving a screw rod by an ultrasonic vibrator and its driving mechanism, the vibrator changes the phase of the voltage applied to two piezoelectric actuators to correct the vibrator. The aim is to improve the efficiency of the rotation and reverse rotation operations.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention relates to a method of driving a screw rod by an ultrasonic vibrator which applies a constant pressure to the periphery of the screw rod by an ultrasonic vibrator to apply friction to the screw rod. A piezoelectric actuator is joined to the corner of the vibrator, and two feet are elastically provided in the groove so as to face the central shaft of the screw rod, and a constant pressure is applied by the vibrator around the screw rod to always increase the pressure. A screw rod driving method using an ultrasonic vibrator, characterized in that friction is applied to a screw rod, the phase of a voltage applied to two piezoelectric actuators is changed and set, and the rotation of the screw rod is changed by switching the phase. From the above, if the operating efficiency of forward rotation and reverse rotation is increased by changing the phase of the voltage applied to the vibrator to two piezoelectric actuators, It is possible to reduce the waste to.

An embodiment of the present invention is directed to a screw rod driving mechanism using an ultrasonic vibrator for applying a constant pressure to the periphery of the screw rod by an ultrasonic vibrator to apply friction to the screw rod. Attached between the bearing side plates fixed to both ends of the base and supported on both ends of the screw rod by pairing, furthermore, the piezoelectric actuator is bonded and fixed to the vibrator and inserted into the vibrator holder, and the vibrator holder is attached to the vibrator. A screw rod drive mechanism by an ultrasonic vibrator, wherein the vibrator is elastically mounted on the screw rod in a state where the vibrator is mounted on the support plate and rotatable around the insertion portion of the vibrator support plate. In the driving mechanism of the screw rod by the ultrasonic vibrator, two vibrators are applied to the vibrator. Since the forward and reverse action by changing pressure of the phase which is screw rod drive mechanism with ultrasonic transducers that efficiently, working operation also becomes easy with a simple mechanism than conventional drive mechanism.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show a driving mechanism of a screw rod by an ultrasonic transducer according to the present invention. In the figure, 1 is a base, 2 is a bearing side plate, 3 is a rail, 4 is a slider, 5 is a bearing, 6 is a moving table, 7 is a vibrator support plate, 8 is a screw rod, 9 is a piezoelectric actuator, 10 is a vibrator, 11 is a spring, 12 is a spring presser, and 13 is a vibrator holder.

In the screw rod drive mechanism of the present invention, a screw rod 8 is mounted between bearing side plates 2 and 2 fixed to both ends of a base 1, and both ends of the screw rod 8 are supported by bearings 5. On the other hand, the voltage actuator 9 which is bonded and fixed to the vibrator 10 is inserted into the vibrator holder 13, and further inserted and mounted on the vibrator support plate 7 so that the vibrator holder 13 rotates. A vibrator 10 is elastically mounted on a screw rod 8 by a spring 11 in a screw groove so as to be rotatable around the insertion portion of the vibrator support plate 7. The strength is adjusted by the spring retainer 12. That is, the feature of the present invention is that
Is moved in the axial direction of the screw rod 8 by the rotation of the screw rod 8, and a vibrator 10 in which a piezoelectric actuator 9 is bonded and fixed to a rotation drive source of the screw rod 8.
Is elastically provided in the groove of the screw rod 8, and ultrasonic vibration is applied thereto to rotate. In this case, the vibrator 10
Is to change the phase of the voltage applied to the two piezoelectric actuators 9 to improve the forward and reverse operation efficiency and reduce waste.

[0018]

According to the present invention, there is provided a method of driving a screw rod by an ultrasonic vibrator for applying a constant pressure to the periphery of the screw rod by an ultrasonic vibrator to apply friction to the screw rod. The piezoelectric actuator is joined and the two feet are elastically provided in the groove so as to face the central shaft of the screw rod, and a constant pressure is applied from the vibrator around the screw rod to always apply a large friction to the screw rod. A method of driving a screw rod by an ultrasonic vibrator, characterized by changing and setting the phase of a voltage applied and applied to two piezoelectric actuators, and changing the rotation of the screw rod by switching the phase. Ultrasonic vibration that applies a constant pressure to the periphery of the screw rod by an ultrasonic vibrator and applies friction to the screw rod In the screw rod driving mechanism, the screw rod is mounted between bearing side plates fixed to both ends of the base, and both ends of the screw rod are supported by pairing, and the piezoelectric actuator is bonded and fixed to the vibrator and vibrated. The vibrator is mounted on the vibrator support plate while being inserted into the vibrator holder, and the vibrator is elastically mounted on the screw rod in a rotatable state about the insertion portion of the vibrator support plate. And a screw rod drive mechanism by the ultrasonic vibrator. In the screw rod drive mechanism by the ultrasonic vibrator, the vibrator has a forward rotation and a reverse rotation by changing the phase of a voltage applied to two piezoelectric actuators. A voltage to apply two piezoelectric actuators because it is a screw rod drive mechanism with an ultrasonic transducer that makes it highly efficient It is possible to reduce the waste to increase the operating efficiency of the reverse and forward rotation of the vibrator by changing phase.

Since the present invention is a driving mechanism of a screw rod by an ultrasonic vibrator, it has the following effects similar to those of the prior art. A. A minimum gap is always required according to the combination of the ball screw, the ball and the ball nut according to the conventional mechanism, but the mechanism of the present invention does not require the minimum gap. B) According to the conventional mechanism, a ball, a ball nut and a servomotor are required for smooth rotation, but the mechanism of the present invention does not require any smooth rotation. That is, in the mechanism of the present invention, it is sufficient to replace the ball and the ball nut with a block of a piezoelectric actuator and a vibrator, so that a servomotor is not required, and the size and cost of the device can be reduced in a small space. It can also contribute to energy conservation. C. If the conventional mechanism is used for a long time, the play between the ball, the ball nut, and the ball screw causes a large play due to a reduction in wear, and the backlash increases. . Even if it is slightly worn, the V-shaped tip of the vibrator is always pressed against the screw rod by the force of the spring against the groove, so that there is no influence. D. In the conventional ball screw mechanism, there is a contradiction in which the backlash must be minimized by always bringing the rotational friction close to zero, and a great effort is required. Absent. In addition, if there is no appropriate friction between the vibrator and the screw rod, no rotational driving force is generated. E. Further, according to the mechanism of the present invention, it can be used without lubrication, so that it is effective particularly in food, semiconductor, medical, etc. where oil is disliked.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram showing a screw rod ultrasonic drive mechanism of the present invention.

FIG. 2 is a plan view of the driving mechanism of the present invention shown in FIG.

FIG. 3 is a plan view of the drive mechanism of the present invention shown in FIG.

FIG. 4 is a front view of the ultrasonic drive mechanism of the present invention shown in FIG. 1;

FIG. 5 is an explanatory schematic diagram of a transducer contact portion of the present invention shown in FIG. 1;

FIG. 6 is an explanatory schematic diagram showing a conventional screw rod ultrasonic drive mechanism.

FIG. 7 is a side view of the conventional ultrasonic drive mechanism shown in FIG.

FIG. 8 is a principle mechanism diagram showing a conventional ultrasonic motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Base 2 Bearing side plate 3 Rail 4 Slider 5 Bearing 6 Moving table 7 Oscillator support plate 8 Screw rod 9 Piezoelectric actuator 10 Oscillator 11 Spring 12 Spring retainer 13 Oscillator holder 21 Screw rod ultrasonic drive mechanism 22 Screw rod 23 Screw rod Cradle 24 Bearing 25 Transducer Cradle 26 Piezoelectric Actuator 28 Spring 29 Spring Locking Tool 31 Ball Screw Servo Motor Drive Mechanism 32 Ball Screw 33 Ball Screw Cradle 34 Bearing 35 Ball Nut 36 Ball 37 Coupling 38 Servo Motor

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[Procedure amendment]

[Submission Date] January 26, 2000 (2000.1.2
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

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[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

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[0011]

SUMMARY OF THE INVENTION The present invention has been developed to solve the above-mentioned problems, and a constant pressure is applied to the periphery of the screw rod by an ultrasonic vibrator to apply friction to the screw rod. In the method of driving a screw rod by an ultrasonic vibrator to be applied, a constant pressure is applied by the vibrator to always apply a large friction to the screw rod and applied to two piezoelectric actuators to change the phase of the voltage, thereby changing the phase of the screw rod. The present invention provides a method for driving a screw rod by an ultrasonic vibrator, which comprises changing the rotation and further applying the vibrator to two piezoelectric actuators to change the phase of the voltage to enhance the efficiency of forward and reverse rotation. is there.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

Further, according to the present invention, there is provided a screw rod mounted via bearings between bearing side plates fixed to both ends of a base, and a vibrator support plate which is adhered to a vibrator and rotates so as to rotate. A piezoelectric actuator mounted on a vibrator holder, and a vibrator mounted on a screw rod via a spring so as to be rotatable around an insertion portion of the vibrator support plate, and the rotation of the screw rod By moving the moving table in the axial direction of the screw rod, and by vibrating the vibrator having the piezoelectric actuator fixed to the rotation driving source of the screw rod in the groove of the screw rod and applying the ultrasonic vibrator to rotate. It is an object of the present invention to provide a screw rod drive mechanism using an ultrasonic transducer.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

[0014]

An embodiment of the present invention is directed to a method of driving a screw rod by an ultrasonic vibrator which applies a constant pressure to the periphery of the screw rod by an ultrasonic vibrator to apply friction to the screw rod. A constant pressure is applied by a vibrator to always apply a large friction to the screw rod, and is applied to the two piezoelectric actuators to change the phase of the voltage to change the rotation of the screw rod. Further, the vibrator is applied to the two piezoelectric actuators. A screw rod driving method using an ultrasonic vibrator characterized in that the applied voltage changes the phase of the voltage to increase the operation efficiency of forward rotation and reverse rotation. Therefore, the vibrator is applied to two piezoelectric actuators. By changing, the operation efficiency of forward rotation and reverse rotation can be increased, and waste can be reduced.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

Further, according to an embodiment of the present invention, a screw rod mounted via bearings between bearing side plates fixed to both ends of a base, and a vibrator support plate adhered to the vibrator and rotated. A piezoelectric actuator mounted on a vibrator holder via a vibrator mounted on a screw rod via a spring so as to be rotatable around an insertion portion of the vibrator support plate, and the screw The moving table is moved in the axial direction of the screw rod by the rotation of the rod, and a vibrator having a piezoelectric actuator fixed to the rotation driving source of the screw rod is elastically provided in the groove of the screw rod, and an ultrasonic vibrator is applied to rotate. Because it is a screw rod drive mechanism by the ultrasonic transducer characterized by making it a simpler mechanism than the conventional drive mechanism Working operation to be made simple and easy.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

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[0018]

According to the present invention, there is provided a method of driving a screw rod by an ultrasonic vibrator for applying a constant pressure to the periphery of a screw rod by an ultrasonic vibrator to apply friction to the screw rod. To constantly apply large friction to the screw rod and apply it to the two piezoelectric actuators to change the phase of the voltage to change the rotation of the screw rod, and further apply the vibrator to the two piezoelectric actuators to apply voltage to the two piezoelectric actuators. Is a screw rod drive method by an ultrasonic vibrator characterized by changing the phase of the forward rotation and the reverse rotation to increase the operation efficiency, and also through a bearing between the bearing side plates fixed to both ends of the base The screw rod to be mounted and the pressure to be mounted on the vibrator holder via the vibrator support plate so as to adhere to the vibrator and rotate. An actuator, and a vibrator attached to a screw rod via a spring so as to be rotatable around an insertion portion of the vibrator support plate. The ultrasonic vibrator is characterized in that the vibrator in which the piezoelectric actuator is fixed to the rotation drive source of the screw rod is elastically provided in the groove of the screw rod and the ultrasonic vibrator is applied and rotated. Since the screw rod drive mechanism is used, the efficiency of forward and reverse rotations of the vibrator can be increased and waste can be reduced by applying two piezoelectric actuators and changing the phase of the voltage.

[Procedure amendment]

[Submission date] June 29, 2000 (2006.2.
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

[Title of the Invention] Screw rod drive mechanism by ultrasonic vibrator

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

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[Claims]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

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[0012]

SUMMARY OF THE INVENTION The present invention has been developed to solve the above-mentioned problems, and is directed to a screw mounted via a bearing between bearing base plates fixed to both ends of a base. A rod, a piezoelectric actuator that is attached to the vibrator holder via a vibrator support plate so as to adhere to the vibrator and rotate, and a spring that can rotate around the insertion portion of the vibrator support plate. And a vibrator elastically mounted on the screw rod through which the moving table is moved in the axial direction of the screw rod by rotation of the screw rod, and a piezoelectric actuator is fixed to a rotation drive source of the screw rod. Is provided in the groove of the screw rod, and the vibrator whose tip is convex or concave is provided in the screw rod to adjust the voltage level. Give a reverse effect and forward to the vibrator by changing, and to provide a screw rod drive mechanism according to the ultrasonic transducer, characterized in that rotate applying ultrasonic vibration to the vibrator.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Deleted

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Deleted

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

According to an embodiment of the present invention, a screw rod mounted via bearings between bearing side plates fixed to both ends of a base and a vibrator support plate adhered to the vibrator and rotated. A piezoelectric actuator mounted on the vibrator holder through the vibrator, and a vibrator elastically mounted on a screw rod via a spring so as to be rotatable around an insertion portion of the vibrator support plate, wherein the screw The moving table is moved in the axial direction of the screw rod by rotation of the rod, and a vibrator having a piezoelectric actuator fixed to a rotation drive source of the screw rod is elastically provided in a groove of the screw rod, and a tip of the vibrator is further moved. A convex or concave type is elastically mounted on a screw rod to apply forward and reverse rotation to the vibrator by changing the phase of the voltage, and the vibrator Since a screw rod drive mechanism according to the ultrasonic transducer, characterized in that rotate applying ultrasonic vibration, operating the operation also becomes easy with a simple mechanism than conventional drive mechanism.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

[0018]

According to the present invention, a screw rod mounted via bearings between bearing side plates fixed to both ends of a base, and a vibrator support plate which is adhered to the vibrator and rotates so as to rotate. A piezoelectric actuator mounted on a vibrator holder, and a vibrator elastically mounted on a screw rod via a spring so as to be rotatable about an insertion portion of the vibrator support plate. The moving table is moved in the axial direction of the screw rod by the rotation of the screw rod, and a vibrator having a piezoelectric actuator fixed to the rotary driving source of the screw rod is elastically provided in the groove of the screw rod, and the tip end of the vibrator is convex. Type or concave type is mounted on the screw rod to apply forward and reverse rotation to the vibrator by changing the phase of the voltage, and to apply ultrasonic waves to the vibrator. Since the screw rod drive mechanism is driven by an ultrasonic vibrator characterized in that the vibrator is rotated by applying a motion, the efficiency of forward and reverse rotation of the vibrator can be improved by applying two piezoelectric actuators and changing the phase of the voltage. And waste can be reduced.

Claims (3)

[Claims] 1. A method of driving a screw rod by an ultrasonic vibrator which applies a constant pressure to the periphery of a screw rod by an ultrasonic vibrator to apply friction to the screw rod, wherein a piezoelectric actuator is joined to a corner of the vibrator. And two legs are elastically provided in the groove portion so as to face the central shaft portion of the screw rod. A constant pressure is applied to the periphery of the screw rod by a vibrator to always apply a large friction to the screw rod. Wherein the phase of the voltage applied to the piezoelectric actuator is changed and set, and the rotation of the screw rod is changed by switching the phase. 2. A screw rod drive mechanism using an ultrasonic vibrator for applying a constant pressure to the periphery of a screw rod by an ultrasonic vibrator to apply friction to the screw rod, wherein the screw rod is fixed to both ends of a base. Mounting between the bearing side plates and supporting both ends of the screw rod by pairing, further fixing the piezoelectric actuator to the vibrator and inserting it into the vibrator holder, and mounting the vibrator holder on the vibrator support plate, A screw rod driving mechanism using an ultrasonic vibrator, wherein the vibrator is elastically mounted on the screw rod so as to be rotatable about an insertion portion of the vibrator support plate. 3. The driving mechanism of a screw rod by the ultrasonic vibrator according to claim 2, wherein the vibrator makes forward and reverse operations more efficient by changing a phase of a voltage applied to two piezoelectric actuators. Screw rod drive mechanism by ultrasonic vibrator.