JPH07337046A - Ultrasonic motor drive - Google Patents

Abstract

PURPOSE:To realize a stabilized operation while increasing the thrust and speed by controlling one of the frequency of phase of an AC voltage being applied to a plurality of electromagnetic energy conversion elements so that a vector in the direction approaching a driven body makes an acute angle with a speed vector in the drive direction of the driven body. CONSTITUTION:Longitudinal and bending oscillations of a resilient body 11 are detected independently. Based on he detected information, one of the frequency or phase of an AC voltage being applied to a plurality of electromechanical energy conversion elements 12 is controlled so that the a vector in the longitudinal direction of an ultrasonic elliptical oscillation excited in a driver 15 and directed in the direction approaching a driven body makes an acute angle with a speed vector in the tangential direction of the ultrasonic elliptical oscillation and directed in the drive direction of the driven body. This structure stabilizes the operation while increasing the thrust and speed.

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 device.

[0002]

2. Description of the Related Art Generally, in an ultrasonic motor, a driving element in contact with a driven body is elliptically vibrated to generate a driving force. In order to generate such elliptical vibration, it is theoretically possible to combine two vibrations in directions orthogonal to each other, and more specifically, vibrations having the same frequency but different phases are applied in the X-axis direction and the Y-axis direction. Good. Therefore, as long as this condition is satisfied, various modifications can be made to the structure of the ultrasonic motor itself, for example, a structure in which two laminated piezoelectric elements are combined in the orthogonal direction, or a rectangular parallelepiped laminated piezoelectric element for vertical vibration. There is known a structure in which a bending piezoelectric element for lateral vibration is attached to the side surface of the.

Therefore, the present applicant also filed Japanese Patent Application No. 4-321096.
Proposed an ultrasonic transducer having a structure in which a holding elastic body is fixed at three locations on the upper surface of a rectangular parallelepiped elastic body, and two laminated piezoelectric elements are sandwiched and fixed between the holding elastic bodies. There is. This ultrasonic oscillator is designed in such a dimension that the resonance frequencies of the longitudinal vibration and the bending vibration of the elastic body are substantially equal to each other, and applies alternating voltages having different resonance frequencies and different phases to the two laminated piezoelectric elements. Then, elliptical vibration is generated in the driver fixed to the bottom surface of the elastic body, which is a combination of the left and right vibrations due to the longitudinal vibration and the upper and lower vibrations due to the bending vibration. According to this ultrasonic vibrator, since the piezoelectric vertical effect of the piezoelectric element is utilized, the electromechanical conversion efficiency is high and the effect of driving at a low voltage can be obtained.

[0004]

However, the device of the above-mentioned prior application has a problem that the operation is not always stable due to large variations due to individual differences of products. That is, as will be seen in detail from the experimental results described later, even when the resonance frequency of the longitudinal vibration and the resonance frequency of the flexural vibration are exactly matched, the operation is unstable, or the resonance frequency of the longitudinal vibration and the flexural vibration There are some that work well and some that do not work at all even when the resonance frequency is slightly deviated.
The cause was unknown. In addition, the same product also has a problem that the speed and the thrust decrease when the resonance frequency changes due to temperature change.

The present invention has been made in view of the above problems, and provides an ultrasonic motor driving device that can always stably drive an ultrasonic motor regardless of variations in products and changes in use conditions. The purpose is to

[0006]

The inventors of the present invention have found that it is optimal that the ultrasonic elliptical vibration of the driver element is an ellipse having a phase difference of about π / 4 (or about 5π / 4), and a large thrust force and speed. Was obtained and found to work stably.

Therefore, in order to achieve the above object, the ultrasonic motor driving device of the present invention according to claim 1 is provided with an elastic body,
It is composed of a driver fixed to the elastic body and a plurality of electro-mechanical energy conversion elements attached to the elastic body, and the synthetic vibration of longitudinal vibration and bending vibration is excited in the elastic body, In an ultrasonic motor driving device having an ultrasonic transducer that makes an elliptical vibration of a driver ultrasonic wave, a driven body driven by the driver, and a power supply that applies an alternating voltage to the electro-mechanical energy conversion element, First vibration detecting means for detecting only the vertical vibration, second vibration detecting means for detecting only the bending vibration, and the first and second
Based on the information of the vibration detection means, the vector in the long axis direction of the ultrasonic elliptical vibration excited in the driver and the vector in the direction approaching the driven body, and the tangential velocity of the ultrasonic elliptical vibration. At least one of the frequency and the phase of the alternating voltage applied to the plurality of electro-mechanical energy conversion elements is controlled so that the angle formed by the vector and the velocity vector in the direction in which the driven body is driven is an acute angle. And a control means.

An ultrasonic motor drive device according to a second aspect of the present invention includes an elastic body, a driver fixed to the elastic body, and a plurality of electric-mechanical energy conversion elements attached to the elastic body. A driven body in which a composite vibration of longitudinal vibration and bending vibration is excited in the elastic body,
In an ultrasonic motor driving device having a power source for applying an alternating voltage to a mechanical energy conversion element, first vibration detecting means for detecting the longitudinal vibration with the moving direction of the driven body as a positive direction, and the bending vibration. Based on the information of the second vibration detecting means for detecting the direction from the driver to the driven body as a positive direction and the information of the first and second vibration detecting means. The phase difference θ is 0 <θ <+ π / 2 or + π <θ <+ 3π / 2 so that the plurality of electric-electric potentials are in a frequency range lower than the resonance frequency of the longitudinal vibration and higher than the resonance frequency of the bending vibration. A control means for controlling at least one of the frequency and the phase of the alternating voltage applied to the mechanical energy conversion element is provided.

An ultrasonic motor drive device according to a third aspect of the present invention includes an elastic body, a driver fixed to the elastic body, and a plurality of electric-mechanical energy conversion elements attached to the elastic body. An ultrasonic transducer that excites a synthetic vibration of longitudinal vibration and bending vibration in the elastic body to cause ultrasonic elliptical vibration of the driver, a driven body driven by the driver, and In an ultrasonic motor drive device having a power source for applying an alternating voltage to an electro-mechanical energy conversion element, a first vibration detecting means for detecting the longitudinal vibration with the moving direction of a driven body as a positive direction, and the bending. Second vibration detecting means for detecting the vibration as a positive direction from the driver to the driven body, and a resonance frequency of the longitudinal vibration is set higher than a resonance frequency of the bending vibration, and resonance of the longitudinal vibration is set. Below frequency In the frequency range equal to or higher than the resonance frequency of the bending vibration, the phase difference δa of the vibration with respect to the alternating voltage of the longitudinal vibration and the phase difference δb of the vibration with respect to the alternating voltage of the bending vibration are 0 <(δa−δb) <+ π / 2. The phase difference θ of the bending vibration with respect to the longitudinal vibration is θ = π / 4 or θ based on the information of the ultrasonic transducer formed in the shape and the information of the first and second vibration detecting means. = 5π / 4, at least one of the frequency and the phase of the alternating voltage applied to the plurality of electro-mechanical energy conversion elements in the frequency range below the resonance frequency of the longitudinal vibration and above the resonance frequency of the bending vibration. And a control means for controlling the control means for applying the alternating voltage having a phase difference of ± π / 2 to the plurality of electro-mechanical energy conversion elements.

[0010]

In the ultrasonic motor driving device of the present invention having the above-mentioned structure, the ultrasonic elliptical vibration of the driver is controlled by the phase difference π / by controlling the frequency or phase of the alternating voltage applied.
The driving is performed so as to form an ellipse of about 4 (or about 5π / 4). As shown in FIG. 5B, the elliptical vibration at this time draws an ellipse that rises to the right when the phase difference is π / 4 (when the driving direction is rightward: positive), and an ellipse that rises to the left when the phase difference is 5π / 4. Draw (when the driving direction is left: negative). Now, in the former case, it is understood that the driver takes a locus of moving to the right while rising, and descending and returning to the left after passing the right uppermost point. That is,
When the driver rises so as to push up the driven body, the contact pressure with respect to the driven body becomes high, but since the driving is performed rightward in the state of this high contact pressure, a strong driving force can be obtained. Then, when the driver element returns to the left, it descends so as to be separated from the driven body, so no force is exerted, and the driven body is driven to the right by repeating the above.

In claim 1, the above-mentioned upward elliptical vibration is expressed more generally. It is known as a so-called Lissajous figure that the phase difference of the vibrations in the XY directions in the orthogonal coordinate system is π / 4, and it is known as a so-called Lissajous figure, but the vibration components in the ultrasonic transducer are not always orthogonal to each other.
Therefore, the more general expression is claim 1.

In claim 2, an orthogonal coordinate system is assumed, and the phase difference is around π / 4, that is, in the range of 0 to π / 2.

In the third aspect, the phase difference is more limited to π /
4 and added other required conditions.

An embodiment of an ultrasonic motor driving device according to the present invention will be described below with reference to the accompanying drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a perspective view showing an ultrasonic transducer.

The basic elastic body 11 is formed by forming a brass material into a convex shape, and has a width of 30 mm and a depth of 4 mm (excluding the convex portion) and a height H of 6 to 9 mm. Prototyped types. The dimensions of the protrusion are 4mm in width, 2.5mm in height, and 4mm in depth.
Is. 6 from the bottom at the widthwise center of the basic elastic body 11.
A φ2 mm stainless pin 16 is pressed into the mm position.

The laminated piezoelectric element 12 is formed by laminating several tens to several hundreds of electrode-treated piezoelectric elements, and in this embodiment, Tokin Co., Ltd. NLA-2 × 3 × 9 type (dimension 2 mm).
× 3.1 mm × 9 mm) was used. The side surfaces of the laminated piezoelectric element 12 other than both end surfaces are covered with an epoxy resin having a thickness of 0.5 mm. Here, the electrodes to the laminated piezoelectric element 12 on the left side of the figure are referred to as A and GND and are referred to as A phase, and the electrodes to the laminated piezoelectric element 12 on the right side are referred to as B and GND and are referred to as B phase.

The two laminated piezoelectric elements 12 and 12 are arranged so as to sandwich the convex portion of the basic elastic body 11, and the elastic holding members 13 and 13 fixed to the basic elastic body 11 with screws 14 from both sides thereof. (Width 4 mm, height 2.5 mm, depth 4 m
m) is sandwiched between them, and they are fixed while being subjected to a compressive force in the longitudinal direction. Here, both end portions of the laminated piezoelectric element 12, the convex portion of the basic elastic body 11, and the holding elastic body 13 are fixed with an epoxy adhesive. Multilayer piezoelectric element 1
The contact surface between 2 and the basic elastic body 11 is also adhered with an epoxy adhesive.

The driver 15 is made of a grindstone material in which abrasive grains of alumina ceramics are dispersed in resin, and has a width of 3 mm and a thickness of 1 m.
The basic elastic body 11 has a rectangular shape with m and a depth of 4 mm.
It is glued at a position 9 mm from both ends of the bottom of the. This position corresponds to the antinode of the flexural vibration, and the amplitude of the resonant flexural vibration has a maximum value.

Next, the operation of the ultrasonic transducer will be described. According to the computer analysis by the finite element method, the ultrasonic transducer having the above-described dimensions shows a first-order resonance longitudinal vibration as shown in FIG. 2A and a second-order resonance bending as shown in FIG. Vibrations can be excited at almost the same frequency. Its frequency is 5
3 to 56 kHz. Therefore, an alternating voltage having an amplitude of 10 Vp-p at this resonance frequency was applied to the A phase and the B phase. First, when the phases of the A phase and the B phase were made to be the same phase, the primary resonant longitudinal vibration as shown in FIG. 2A was excited. Next, when the phases of the A phase and the B phase were made opposite to each other, the secondary resonant bending vibration as shown in FIG. 2B was excited. Further, when the phases of the A phase and the B phase were shifted by 90 degrees, ultrasonic elliptical vibration was excited near the driver 15.

Next, an ultrasonic linear motor using the above ultrasonic vibrator will be described. FIG. 3 is a front view of the ultrasonic linear motor. As shown in the figure, in this ultrasonic linear motor, the ultrasonic vibrator 10 is used to move the moving member 32, the sliding member holding member 33, and the sliding member 3.
4 is driven left and right on the fixed portion 30 of the cross roller guide.

The ultrasonic transducer 10 has two pins 16
The holding plate 21 is pivotally mounted between the holding plates 21, and the holding plate 21 is screwed to a mounting member 22 with a screw 23, and the mounting member 22 is slidably guided along a shaft 25 by a linear bush 24. The shaft 25 is fixed to a base 27 via a fixing member 26. Therefore, the ultrasonic transducer 10 has a degree of freedom of rotation around the pin 16 and a degree of freedom by vertical movement of the pin 16. A spring 29, whose pressing force can be varied by an adjusting screw 28, is interposed between the fixing member 26 and the mounting member 22.

The fixed portion 30 of the cross roller guide is the base 2
7, a screw 31 is fixed to the cross roller guide 7, and a sliding member 34 made of zirconia ceramics is bonded to a moving portion 32 of the cross roller guide via a sliding member holding portion 33. It is in contact with the child 15, 15.

Next, the operation of this ultrasonic linear motor will be described. As described above, an alternating voltage of 53 to 56 kHz is applied to the A phase and the B phase of the ultrasonic transducer 10 to change the phase difference to 90.
Degrees (or -90 degrees). Then, the ultrasonic transducer 10
The ultrasonic elliptical vibration is excited in the driver 15 of the
2 moves left and right. Therefore, as described above, ten types of ultrasonic transducers having different heights H were prototyped and the motor characteristics were evaluated. The results are shown below.

[0024]

[Table 1]

In Table 1, the motor operation ○ indicates good operation, Δ indicates operation but very unstable, × indicates no operation or almost no thrust and speed obtained even when operating. It means that it was not possible. The driving frequency was higher than the bending vibration resonance frequency and lower than the longitudinal vibration resonance frequency (the unit of the table is kHz). From this result, it became clear that stable operation cannot be achieved unless the bending vibration resonance frequency is lower than the longitudinal vibration resonance frequency.

For the above experimental results, the following experiment was conducted in order to find the cause. As shown in FIG. 4, a piezoelectric element 110 polarized in the thickness direction was bonded to the side surface of the ultrasonic transducer 100 as a vibration detecting element. This piezoelectric element has a width of 10 mm, a height of 3 mm and a thickness of 0.3 mm. The bonding position is directly above the driver. The front surface of the vibrator was bonded so that the polarization directions thereof were the same and connected in series to form a F1 terminal. On the back side of the oscillator, the polarization directions are reversed and F
Two terminals were used. As can be seen from the vibration mode in FIG.
One terminal detects only the longitudinal vibration of the elastic body, and the F2 terminal detects only the bending vibration.

Now, with respect to the ultrasonic transducers of prototype Nos. 0 to 9, longitudinal vibration at the time of voltage application by the F1 and F2 terminals,
Flexural vibration was detected at the same time. The result is shown in FIG. In the figure, the driven body located above is driven in the left-right direction. In addition, positive and negative represent the time of driving in the positive direction and the time of driving in the negative direction.

FIG. 5 (a) shows the vibration shape of the prototype No. 0 vibrator. It can be seen that it is almost a linear reciprocating vibration.
In this case, it does not work, or it works, but there is almost no speed or thrust.

FIG. 5B shows the vibration shapes of the vibrators of prototype numbers 1 to 5. It is an ellipse that rises to the right. In this case, it operates satisfactorily and stably. In particular, the maximum thrust and speed were obtained when the phase difference of bending vibration with respect to longitudinal vibration was + π / 4 (when driving in the positive direction) or 5π / 4 (when driving in the negative direction).

FIG. 5 (c) shows the vibration shape of the vibrator of prototype No. 6. Although a perfect circle is shown in the figure, it is actually a vertically or horizontally long ellipse due to the difference in amplitude between longitudinal vibration and bending vibration. At this time, the operation was unstable. From this, it was found that the operation becomes unstable when the main axis of the ellipse is parallel to the driving direction of the driven body.

FIG. 5D shows the vibration shapes of the vibrators of prototype numbers 7 to 9. Even in this case, it does not work, or it works, but there is almost no speed or thrust.

From the above experimental results, it was found that the motor cannot operate stably unless the elliptic vibration is ascending to the right as shown in FIG. 5 (b).

This means that, considering the Lissajous figure of the XY orthogonal coordinate system, the phase difference is before and after π / 4, that is, in the range of 0 to π / 2. further,
In the cases other than the orthogonal coordinate system, as described in claim 1, a vector in the major axis direction of the elliptical vibration and a vector in the direction approaching the driven body, and a velocity vector in the tangential direction of the ultrasonic elliptical vibration are used. This means that the angle formed by the velocity vector in the direction in which the driven body is driven is an acute angle.

Next, for the prototypes 0-9,
When the relationship between the amplitude and the phase of each vibration mode with respect to the applied voltage was examined by sweeping the frequency, it was as shown in FIG. In the figure, fl is the resonance frequency of longitudinal vibration, and f
b is the resonance frequency of bending vibration.

In the case of the prototype No. 0 vibrator, the vibration mode 1 corresponds to the longitudinal vibration mode, the vibration mode 2 corresponds to the bending vibration, and the phase difference between fl and fb is It was π / 2.

In the case of the vibrators of prototype Nos. 1 to 5, the vibration mode 1 corresponds to the longitudinal vibration mode, and the vibration mode 2 corresponds to the bending vibration, and the position between fl and fb. The phase difference was more than 0 and less than π / 2.

In the case of the vibrator of prototype No. 6, it was the longitudinal vibration mode that corresponded to the vibration mode 1 and the bending vibration that corresponded to the vibration mode 2, but both curves were almost the same. . Therefore, fl and fb were in agreement, and the phase difference was 0.

In the case of the vibrators of prototype numbers 7 to 9, the flexural vibration mode corresponds to the vibration mode 1, the longitudinal vibration corresponds to the vibration mode 2, and the position between fl and fb. The phase difference was 0 or more.

From the above experimental results, as the ultrasonic oscillator, as described in claim 3, the resonance frequency of longitudinal vibration is set higher than the resonance frequency of bending vibration, and the bending vibration is lower than the resonance frequency of longitudinal vibration. The phase difference δa of the vibration with respect to the alternating voltage of the longitudinal vibration in the frequency range above the resonance frequency of
And, the phase difference δb of the bending vibration with respect to the alternating voltage is
It was found that it is preferable to form in a shape of 0 <(δa−δb) <+ π / 2. At this time, stable operation can be obtained by applying to the laminated piezoelectric element an alternating voltage whose phase is ± π / 2 different in the frequency range below the resonance frequency of longitudinal vibration and above the resonance frequency of bending vibration.

However, the above is true when the resonance frequency of the ultrasonic vibrator is constant, and in an actual ultrasonic vibrator, a temperature rise of about 30 ° C. occurs during use, and longitudinal vibration and bending vibration occur. In both cases, the resonance frequency decreases.

Therefore, a driving circuit as shown in FIG.
Input the detection signals from the F1 and F2 terminals to the comparison controller,
Based on the information of these vibration detecting means, the phase difference θ of the bending vibration with respect to the longitudinal vibration is 0 <θ <+ π / 2, or
In the frequency range below the resonance frequency of the longitudinal vibration and above the resonance frequency of the bending vibration so that + π <θ <+ 3π / 2, 2
The frequency and phase of the alternating voltage applied to the two laminated piezoelectric elements were controlled. That is, the comparison controller controls the oscillation frequency of the oscillator, and further controls the phase difference by the phase shifter.
This is amplified and an alternating voltage is applied to the A and B phases.

In the present embodiment, stable thrust and speed were obtained by the above control even when the temperature of the ultrasonic transducer changed and the resonance frequency shifted. Although two laminated piezoelectric elements are used in this embodiment, the invention can be applied to the case where three or more electromechanical transducers are used.

[0043]

Second Embodiment Next, a second embodiment of the present invention will be described. Figure 8
FIG. 3 is a block diagram showing a drive circuit of this embodiment. The configurations and operations of the ultrasonic oscillator and the linear motor are the same as in the first embodiment. In this example, the phase difference of the alternating voltage applied to the A phase and B phase of the ultrasonic transducer was fixed to ± π / 2. Then, the comparison controller controlled only the frequency. That is,
In the comparison controller of FIG. 8, the phase difference θ of the bending vibration with respect to the longitudinal vibration is θ = π /, based on the information of F1 and F2.
4 or θ = 5π / 4, a signal for controlling the frequency of the alternating voltage applied to the two laminated piezoelectric elements in the frequency range below the resonance frequency of the longitudinal vibration and above the resonance frequency of the flexural vibration. Output to oscillator.

In the present embodiment, stable thrust and speed were obtained by the above control even when the temperature of the ultrasonic transducer changed and the resonance frequency shifted. Note that this embodiment has an advantage over the first embodiment in that the circuit configuration is simpler.

The present invention is not limited to the above-mentioned embodiment, and ultrasonic elliptical vibration was obtained by synthesizing longitudinal vibration and bending vibration in the above-mentioned embodiment. For example, torsional vibration, sliding vibration, respiration The same can be achieved by combining vibration and spread vibration. Further, although the linear type ultrasonic motor is applied in the above-described embodiment, if the moving body is a rotating body, it can be applied to a rotating type ultrasonic motor.

[0046]

As described above, according to the ultrasonic motor driving device of the present invention, stable thrust and speed can be obtained even when the temperature of the ultrasonic transducer changes and the resonance frequency shifts. .

[Brief description of drawings]

FIG. 1 is a perspective view showing an ultrasonic transducer according to the present invention.

FIG. 2 is a diagram illustrating a vibration mode of the ultrasonic transducer of FIG.

FIG. 3 is a front view showing an ultrasonic linear motor according to the present invention.

FIG. 4 is a front view and a rear view showing an ultrasonic transducer according to the present invention.

FIG. 5 is a diagram for explaining the operation of the present invention.

FIG. 6 is a diagram illustrating the operation of the present invention.

FIG. 7 is a block diagram showing a drive circuit of the ultrasonic motor drive device according to the first embodiment of the present invention.

FIG. 8 is a block diagram showing a drive circuit of an ultrasonic motor drive device according to a second embodiment of the present invention.

[Explanation of symbols]

 10 Ultrasonic Transducer 11 Basic Elastic Body 12 Multilayer Piezoelectric Element 13 Holding Elastic Member 15 Driver 16 Pin 21 Holding Plate 24 Linear Bushing 25 Shaft 27 Base 28 Adjusting Screw 29 Spring 30 Cross Roller Guide Fixing Part 32 Cross Roller Guide Moving part 34 Sliding member

Claims (3)

[Claims] 1. An elastic body, a driver fixed to the elastic body, and a plurality of electro-mechanical energy conversion elements attached to the elastic body, wherein the elastic body is subjected to longitudinal vibration and bending vibration. An ultrasonic transducer that excites the synthetic vibration of the element to cause an ultrasonic elliptical vibration of the driver, a driven body that is driven by the driver, and a power supply that applies an alternating voltage to the electromechanical energy conversion element. In the ultrasonic motor drive device including: a first vibration detecting means for detecting only the longitudinal vibration, a second vibration detecting means for detecting only the bending vibration, and a first vibration detecting means for the first and second vibration detecting means. Based on the information
The driven body is driven by a vector in the long axis direction of the ultrasonic elliptical vibration excited in the driver and a vector in the direction approaching the driven body, and by a tangential velocity vector of the ultrasonic elliptical vibration. A comparison controller that controls at least one of the frequency and the phase of the alternating voltage applied to the plurality of electro-mechanical energy conversion elements so that the angle formed by the velocity vector in the direction of rotation becomes an acute angle. Characteristic ultrasonic motor drive device. 2. An elastic body, a driver fixed to the elastic body, and a plurality of electro-mechanical energy conversion elements attached to the elastic body, wherein the elastic body is subjected to longitudinal vibration and bending vibration. An ultrasonic transducer that excites the synthetic vibration of the element to cause ultrasonic elliptical vibration of the driver, a driven body that is driven by the driver, and a power supply that applies an alternating voltage to the electromechanical energy conversion element. In the ultrasonic motor driving device having: a first vibration detecting means for detecting the vertical vibration with the moving direction of the driven body as a positive direction, and the bending vibration in the direction from the driver to the driven body. Based on the information of the second vibration detecting means for detecting the positive direction and the first and second vibration detecting means,
The phase difference θ of the bending vibration with respect to the longitudinal vibration is 0 <θ <+ π / 2 or + π <θ <+ 3π / 2 so that the frequency is equal to or lower than the resonance frequency of the longitudinal vibration and equal to or higher than the resonance frequency of the bending vibration. And a control means for controlling at least one of the frequency and the phase of the alternating voltage applied to the plurality of electro-mechanical energy conversion elements within the range. 3. An elastic body, a driver fixed to the elastic body, and a plurality of electro-mechanical energy conversion elements attached to the elastic body, wherein the elastic body is subjected to longitudinal vibration and bending vibration. An ultrasonic transducer that excites the synthetic vibration of the element to cause ultrasonic elliptical vibration of the driver, a driven body that is driven by the driver, and a power supply that applies an alternating voltage to the electromechanical energy conversion element. In the ultrasonic motor drive device having: a first vibration detecting means for detecting the vertical vibration with the moving direction of the driven body as a positive direction, and the bending vibration in a positive direction from the driver to the driven body. A second vibration detecting means for detecting the direction, and a resonance frequency of the longitudinal vibration is set higher than a resonance frequency of the bending vibration, and in a frequency range below the resonance frequency of the longitudinal vibration and above the resonance frequency of the bending vibration. , An ultrasonic transducer formed in a shape such that a phase difference δa of vibrations with respect to an alternating voltage of longitudinal vibrations and a phase difference δb of vibrations with respect to an alternating voltage of bending vibrations are 0 <(δa−δb) <+ π / 2. And based on the information of the first and second vibration detection means,
The phase difference θ of the bending vibration with respect to the longitudinal vibration is θ = π / 4 or θ = 5π / 4 in a frequency range below the resonance frequency of the longitudinal vibration and above the resonance frequency of the bending vibration. A control means for controlling at least one of the frequency and the phase of the alternating voltage applied to the plurality of electro-mechanical energy conversion elements, wherein the plurality of electro-mechanical energy conversion elements have a phase of ± π / An ultrasonic motor drive device characterized in that two different alternating voltages are applied.