JP2006352989A - Drive unit of ultrasonic motor, its method and ultrasonic motor system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive unit of an ultrasonic motor that can control the speed of the ultrasonic motor with accuracy, its method, and an ultrasonic motor system. <P>SOLUTION: The drive unit of the ultrasonic motor drives the ultrasonic motor 1, by individually feeding two-phase AC voltages of prescribed drive frequencies to a plurality of ultrasonic vibrators 10a, 10b and 10c possessed by the ultrasonic motor 1. The speed of the ultrasonic motor is controlled, by individually controlling phase differences of the two-phase AC voltages fed to the ultrasonic vibrators 10a, 10b and 10c. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic motor driving apparatus, method and system thereof.

In recent years, ultrasonic motors have attracted attention as new motors that replace electromagnetic motors. This ultrasonic motor has the following advantages over conventional electromagnetic motors.
(1) High torque can be obtained without gears.
(2) There is holding power when electricity is OFF.
(3) High resolution.
(4) Rich in silence.

As a method for driving such an ultrasonic motor, for example, there is a method disclosed in Japanese Patent Application Laid-Open No. 11-233502 (Patent Document 1). In this patent document 1, in an ultrasonic motor provided with three ultrasonic transducers (vibration actuators), a drive circuit is individually provided for each ultrasonic transducer, and the ultrasonic vibration corresponding to each drive circuit is provided. A technique is disclosed in which a driving force in the same direction is generated in all ultrasonic transducers by supplying a two-phase alternating voltage with a phase difference of 90 ° to the child, thereby obtaining the driving force.
Japanese Patent Application Laid-Open No. 11-235062 (page 4, FIGS. 5 and 9)

  In the conventional ultrasonic motor as described above, the speed control is generally performed by changing the amplitude of the alternating voltage, that is, the voltage value. However, between the voltage of the alternating signal and the speed (rotation speed) of the ultrasonic motor, for example, as shown in FIG. 13, in a region (region where the voltage is between V0 and V1), And the speed changes rapidly. For this reason, the speed fluctuates greatly with respect to a slight voltage displacement, and there is a problem that speed control cannot be performed with high accuracy.

  The present invention has been made in view of the above-described circumstances, and an ultrasonic wave capable of accurately controlling the speed of an ultrasonic motor by controlling the phase difference of an alternating voltage supplied to each ultrasonic vibrator. An object of the present invention is to provide a motor driving apparatus and method, and an ultrasonic motor system.

In order to achieve the above object, the present invention provides the following means.
The present invention provides an ultrasonic motor that drives the ultrasonic motor by individually supplying a two-phase alternating voltage having a predetermined driving frequency to each of the plurality of ultrasonic vibrators included in the ultrasonic motor. In the drive device, an ultrasonic motor drive device that controls the speed of the ultrasonic motor by individually controlling the phase difference between the two-phase alternating voltages supplied to the ultrasonic transducers.

  According to the present invention, the vibration mode generated at the output end of each ultrasonic transducer can be changed by individually controlling the phase difference between the two-phase alternating voltages supplied to each ultrasonic transducer included in the ultrasonic motor. To control the speed of the ultrasonic motor. In this case, the relationship between the phase difference of the alternating voltage and the speed (rotation speed) has a gentle gradient characteristic as shown in FIG. The problem of changing can be solved, speed control with high accuracy can be realized, and stable speed control can be realized. Furthermore, by controlling each ultrasonic transducer individually, it becomes possible to perform finer speed control by the combination of the phase differences.

  The present invention provides a driving apparatus for an ultrasonic motor that drives the ultrasonic motor by supplying a two-phase alternating voltage having a predetermined driving frequency to each of a plurality of ultrasonic vibrators included in the ultrasonic motor. The ultrasonic motor for controlling the speed of the ultrasonic motor by supplying the same two-phase alternating voltage to each of the plurality of ultrasonic vibrators and controlling the phase difference between the alternating voltages A driving apparatus is provided.

  According to the present invention, each ultrasonic vibrator provided in the ultrasonic motor is supplied with the same two-phase alternating signal, and the phase difference between the two-phase alternating voltages is controlled, so that each ultrasonic vibration is controlled. The vibration mode generated at the output end of the child changes, and the speed of the ultrasonic motor is controlled. In this case, the relationship between the phase difference of the alternating voltage and the speed (rotation speed) has a gentle gradient characteristic as shown in FIG. The problem of changing can be solved, speed control with high accuracy can be realized, and stable speed control can be realized. Furthermore, since the same signal is supplied to each ultrasonic transducer, the configuration of the drive device can be simplified and the control can be simplified.

  The present invention provides an ultrasonic motor that drives the ultrasonic motor by individually supplying a two-phase alternating voltage having a predetermined driving frequency to each of the plurality of ultrasonic vibrators included in the ultrasonic motor. In the driving method, an ultrasonic motor driving method for controlling the speed of the ultrasonic motor by individually controlling the phase difference between the two-phase alternating voltages supplied to the ultrasonic transducers is provided.

  The present invention provides an ultrasonic motor driving method for driving the ultrasonic motor by supplying a two-phase alternating voltage having a predetermined driving frequency to each of a plurality of ultrasonic transducers included in the ultrasonic motor. The ultrasonic motor for controlling the speed of the ultrasonic motor by supplying the same two-phase alternating voltage to each of the plurality of ultrasonic vibrators and controlling the phase difference between the alternating voltages A driving method is provided.

  The present invention provides an ultrasonic motor including a plurality of ultrasonic vibrators, and separately supplying a two-phase alternating voltage having a predetermined driving frequency to each of the ultrasonic vibrators. And a driving device that controls the speed of the ultrasonic motor by individually controlling a phase difference between the two-phase alternating voltages supplied to the ultrasonic transducers. A sonic motor system is provided.

  The present invention drives an ultrasonic motor by supplying an ultrasonic motor having a plurality of ultrasonic vibrators and a two-phase alternating voltage having a predetermined driving frequency to each of the ultrasonic vibrators. The driving device supplies the same two-phase alternating voltage to each of the plurality of ultrasonic transducers, and controls the phase difference of the alternating voltage to thereby control the supersonic wave. An ultrasonic motor system for controlling the speed of a sonic motor is provided.

  According to the present invention, there is an effect that the speed control of the ultrasonic motor can be performed with high accuracy.

Hereinafter, an ultrasonic motor driving apparatus and driving method, and an ultrasonic motor system according to embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the ultrasonic motor according to the present invention includes three ultrasonic transducers 10a to 10c and one driven body 50 driven by the three ultrasonic transducers 10a to 10c. Configured. In addition, the ultrasonic motor system according to the present embodiment includes the ultrasonic motor and a drive device (see FIG. 7) that drives the ultrasonic motor.

  As shown in FIGS. 2 to 4, for example, the ultrasonic transducer 10a is formed by laminating a plurality of rectangular plate-shaped piezoelectric ceramic sheets 7 provided with sheet-like internal electrodes 8 on one side surface. A rectangular parallelepiped piezoelectric laminate 9 and two frictional contacts 12 bonded to two output ends formed on one side surface in the width direction of the piezoelectric laminate 9 are provided.

  The piezoelectric ceramic sheet 7 shown in the figure has an internal electrode 8 on almost the entire surface. Two internal electrodes 8 are arranged at a predetermined insulation distance in the length direction of the piezoelectric ceramic sheet 7. Each internal electrode 8 is disposed with a predetermined gap from the periphery of the piezoelectric ceramic sheet 7, and a part thereof extends to the periphery of the piezoelectric ceramic sheet 7.

  The piezoelectric ceramic sheet 7 shown in FIG. 3 includes an internal electrode 8 in substantially half of the width direction. Two internal electrodes 8 are arranged at a predetermined insulation distance in the length direction of the piezoelectric ceramic sheet 7. Each internal electrode 8 is disposed with a predetermined gap from the periphery of the piezoelectric ceramic sheet 7, and a part thereof extends to the periphery of the piezoelectric ceramic sheet 7.

  The piezoelectric ceramic sheet 7 provided with these internal electrodes 8 has a rectangular parallelepiped by alternately stacking a plurality of large internal electrodes 8 shown in FIG. 3 and small internal electrodes 8 shown in FIG. A piezoelectric laminate 9 is formed.

  A total of four external electrodes 11 are provided, two at each end face in the length direction of the piezoelectric laminate 9. All the internal electrodes 8 arranged at the same position of the same kind of piezoelectric ceramic sheet 7 are connected to each external electrode 11. Thereby, the internal electrodes 8 arranged at the same position of the same kind of piezoelectric ceramic sheet 7 are set to the same potential. Note that a wiring (not shown) is connected to the external electrode 11. The wiring may be any wiring as long as it is flexible, such as a lead wire or a flexible substrate.

Next, the operation of the piezoelectric laminate 9 will be described.
Two external electrodes 11 formed at one end in the longitudinal direction of the piezoelectric laminate 9 are A phase (A +, A−), and two external electrodes 11 formed at the other end are B phase (B +, B−). To do. When an alternating voltage having the same phase and corresponding to the resonance frequency is applied to the A phase and the B phase, the primary longitudinal vibration as shown in FIG. 5 is excited. Further, when an alternating voltage corresponding to the resonance frequency is applied to the A phase and the B phase in opposite phases, a secondary bending vibration as shown in FIG. 6 is excited. 5 and 6 are diagrams showing computer analysis results by the finite element method.

  When primary longitudinal vibration is generated in the piezoelectric laminate 9, the friction vibrator 10 is displaced in the length direction of the piezoelectric laminate 9 (X direction shown in FIG. 5). On the other hand, when a secondary bending vibration is generated in the piezoelectric laminate 9, the friction contact 12 is displaced in the width direction of the piezoelectric laminate 9 (Z direction shown in FIG. 6).

Therefore, by applying an alternating voltage corresponding to the resonance frequency whose phase is shifted by 90 ° to the A phase and the B phase of the ultrasonic vibrator, the primary longitudinal vibration and the secondary bending vibration are generated simultaneously. As shown by an arrow C in FIG. 2, a substantially elliptic vibration in a clockwise direction or a counterclockwise direction is generated at the position of the friction contact 12.
1 is applied to the ultrasonic transducers 10b and 10c shown in FIG. 1 by applying an alternating voltage similar to that of the ultrasonic transducer 10a described above, so that a predetermined substantially elliptical shape is provided at the position of the friction contactor 12 included in each of the ultrasonic transducers 10b and 10c. Vibration will occur.

  Since the friction contact 12 and the upper surface of the driven body 50 respectively provided in each of the ultrasonic transducers 10a to 10c are pressed in close contact with each other, when the friction contact 12 is moved approximately elliptically, The upper surface of the driven body 50 is pressed by the frictional contact in the tangential direction of the substantially elliptical motion by the frictional force generated in the above. And in each ultrasonic transducer | vibrator 10a, 10b, 10c, the pressing operation by friction is alternately repeated by the two friction contacts 12, and each friction contact 12 and the upper surface of the to-be-driven body 50 are made. The driven body 50 is moved relative to the ultrasonic transducers 10a to 10c while the close contact and separation are repeated intermittently.

As described above, the ultrasonic motor according to the present embodiment relatively moves the driven body 50 by the vibration generated at the position of the friction contact 12 of each of the ultrasonic transducers 10a to 10c. Therefore, if the vibration state of each friction contact 12 provided in the ultrasonic transducers 10a to 10c is changed, the pressing operation due to friction between the friction contact 12 and the upper surface of the driven body is changed, and the driven body of the driven body is changed. It is possible to change the moving speed, in this embodiment, the rotational speed.
As described above, the drive device according to the present embodiment, which will be described later, controls the rotational speed of the driven body by individually controlling the phase difference of the alternating voltage supplied to the ultrasonic transducers 10a, 10b, and 10c. It is.

Hereinafter, an ultrasonic motor driving apparatus for driving the ultrasonic motor 1 as described above will be described with reference to the drawings. FIG. 7 is a block diagram showing a schematic configuration of the ultrasonic motor driving apparatus according to the present embodiment.
As shown in FIG. 7, the driving device for the ultrasonic motor is provided corresponding to each of the driving units 20 a to 20 c provided corresponding to each of the ultrasonic transducers 10 a to 10 c and corresponding to each driving unit 20 a to 20 c. The transmitters 21a to 21c and the controller 22 for controlling the transmitters 21a to 21c are provided.

In order to drive the ultrasonic motor 1 at a desired speed (number of revolutions), the control unit 22 applies an alternating voltage having a phase difference corresponding to the speed (number of revolutions) to each of the ultrasonic transducers 10a to 10c. As described above, the transmitters 21a to 21c are controlled.
The driving units 20a to 20c generate a source signal having a predetermined frequency with a phase difference based on the control of the control unit 22, and output the source signal to the corresponding driving units 20a to 20c. Here, the predetermined frequency is set to the resonance frequency of the ultrasonic transducers 10a, 10b, and 10c, for example. The drive units 20a to 20c step up and down the source signal supplied from the oscillation units 21a to 21c to an optimum voltage that can drive the ultrasonic transducers 10a to 10c, and apply them to the ultrasonic transducers 10a, 10b, and 10c. .

  As described above, since the phase difference of the alternating voltage applied to each ultrasonic transducer 10a to 10c is individually controlled by the control unit 22, the friction contactor 12 provided in each ultrasonic transducer 10a to 10c is provided with It is possible to generate vibrations corresponding to the phase difference of the alternating voltage. Thereby, since the friction state between the friction contact 12 and the upper surface of the driven body 50 changes, the ultrasonic motor 1 can be driven at a desired speed accordingly. Furthermore, by controlling each of the ultrasonic transducers 10a to 10c individually, the speed control of the ultrasonic motor 1 can be performed more finely than when the same alternating signal is applied to each of the ultrasonic transducers 10a to 10c. Can be done.

Next, the relationship between the above-described alternating voltage phase difference and the speed of the ultrasonic motor will be described in detail.
First, in the present embodiment, modes A to H as shown in FIG. 8 are assumed as combinations of alternating voltage phase differences applied to the ultrasonic transducers 10a to 10c.
For example, mode A is a mode in which an alternating voltage with a phase difference of 90 ° is applied to all the ultrasonic transducers 10a to 10c. Further, for example, in modes B to F, an alternating voltage with a phase difference of 90 ° is applied to the ultrasonic transducers 10b and 10c, and an alternating voltage with a phase difference other than 90 ° is applied to the ultrasonic transducer 10a. Is a mode in which is applied. For example, an alternating signal having a phase difference of 0 ° in mode B, 180 ° in mode C, a phase difference of 10 ° to 80 ° in mode D, and a phase difference of 100 ° to 170 ° in mode E is applied. To do. In mode F, the AC voltage is not applied and the OFF state is set.
In modes G to K, an alternating voltage having a phase difference of 90 ° is applied to the ultrasonic transducer 10c, the ultrasonic transducer 10b is turned off, and the ultrasonic transducer 10a is switched to the modes B to F described above. In this mode, an alternating signal having a corresponding phase difference is applied. The mode L is a mode in which the driving of the ultrasonic motor 1 is stopped by turning off all the ultrasonic transducers 10a to 10c.

Next, an example of the speed of the ultrasonic motor when the ultrasonic transducers 10a to 10c are driven in each mode as described above will be described.
For example, as shown in FIG. 9, when the rotational speed (speed) when driven in the above-described mode A is 54.5 rpm, the rotational speed is 37.5 rpm in mode C, and the rotational speed is 10 in mode B. It became 2 rpm. Although not shown in FIG. 8, for example, when an alternating voltage having a phase difference of 90 ° is applied to the ultrasonic transducer 10c and an alternating voltage having a phase difference of 180 ° is applied to the ultrasonic transducers 10a and 10c. (Hereinafter, this mode is referred to as “mode M”.), The rotational speed was 6.8 rpm.

  Further, in the modes D and E in FIG. 8, when the phase difference of the alternating voltage of the ultrasonic transducer 10a is changed from 0 ° to 180 °, for example, the speed characteristic of the ultrasonic motor as shown in FIG. 10 is obtained. It was. As shown in FIG. 10, the rotational speed rises by drawing a gentle arc from a phase difference of 0 ° to about 80 °, and the rotational speed is constant from a phase difference of about 80 ° to about 140 °. The rotation speed gradually decreases from 140 ° to 180 °.

  As described above, by changing the phase difference of the alternating voltage applied to each of the ultrasonic transducers 10a to 10c, the speed (the number of rotations) of the ultrasonic motor 1 can be controlled to a desired value.

  As described above, according to the ultrasonic motor driving apparatus and driving method and the ultrasonic motor system according to the present embodiment, the ultrasonic motors 10a, 10b, and 10c included in the ultrasonic motor 1 are provided. By individually controlling the phase difference between the two-phase alternating signals supplied in this manner, the vibration mode generated in the friction contact 12 provided in each of the ultrasonic transducers 10a to 10c is changed, and the speed of the ultrasonic motor 1 is changed. Since it is changed, stable speed control of the ultrasonic motor 1 is possible, and speed control with high accuracy can be realized. Further, by controlling the alternating signals of the three ultrasonic transducers 10a to 10c individually, speed control can be performed more finely.

In FIG. 11, the speed rising characteristics of the ultrasonic motor 1 when the alternating signals of mode A, mode B, mode C, and mode M are applied to the ultrasonic transducers 10 a to 10 c of the ultrasonic motor 1, respectively. Indicates. Further, in FIG. 12, the speed fall characteristics of the ultrasonic motor when the alternating signals of mode A, mode B, mode C, and mode M are applied to the ultrasonic transducers 10 a to 10 c of the ultrasonic motor 1, respectively. Indicates.
As shown in FIG. 11 and FIG. 12, it can be seen that the rising and falling characteristics of the speed differ depending on each mode. Accordingly, it is possible to realize driving of the ultrasonic motor 1 having desired rising characteristics and falling characteristics by gradually changing the driving mode at the start of driving or at the end of driving.

  In the above-described embodiment, the control unit 22 may be configured by hardware, or the above control may be realized by processing by software. In this case, the control unit 22 includes, for example, a CPU (Central Processing Unit), a HDD (Hard Disc Drive), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. A series of processes for realizing the various functions described above is recorded in a ROM or the like in the form of a program, and the CPU reads the program into the RAM or the like and executes information processing / arithmetic processing. Assume that the above-described functions are realized.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
First, the drive mode shown in FIG. 8 is an example, and the ultrasonic transducer may be driven in another drive mode.
2ndly, although the said embodiment demonstrated the ultrasonic motor provided with three ultrasonic transducer | vibrators, it does not specifically limit about the installation number of an ultrasonic transducer | vibrator. Even if the number of installed ultrasonic transducers increases or decreases, a drive mode corresponding to the number is assumed (see FIG. 8), and an ultrasonic mode when an alternating voltage is applied to the ultrasonic transducer in each assumed drive mode. And the phase difference of the alternating signal applied to each ultrasonic transducer may be controlled based on this velocity characteristic.
Third, in the above-described embodiment, the case where each of the plurality of ultrasonic transducers is individually driven has been described as an example. However, the same alternating signal is applied to each ultrasonic transducer. Also good. By doing in this way, it becomes possible to make the transmission parts 21a thru | or 21c and the drive parts 20a thru | or 20c which were shown in FIG. As a result, the configuration of the driving device can be simplified and the control can be simplified.

It is a figure showing the whole ultrasonic motor composition concerning one embodiment of the present invention. It is a perspective view which shows the ultrasonic transducer | vibrator of the ultrasonic motor of FIG. It is a perspective view which shows the piezoelectric ceramic sheet which comprises the piezoelectric laminated body of FIG. It is a perspective view which shows the piezoelectric ceramic sheet which comprises the piezoelectric laminated body of FIG. It is a figure which shows a mode that the piezoelectric laminated body of FIG. 2 vibrates in the primary longitudinal vibration mode by computer analysis. It is a figure which shows a mode that the piezoelectric laminated body of FIG. 2 vibrates in a secondary bending vibration mode by computer analysis. 1 is a block diagram showing a schematic configuration of an ultrasonic motor drive device according to an embodiment of the present invention. It is a figure which shows an example of the drive mode of the alternating voltage applied to an ultrasonic transducer | vibrator. It is the figure which showed an example of the rotation speed (speed) of the ultrasonic motor at the time of driving an ultrasonic transducer | vibrator by mode A, mode C, mode B, and mode M. When an alternating voltage having a phase difference of 90 ° is supplied to two ultrasonic transducers and the phase difference of the alternating voltage supplied to the other ultrasonic transducer is changed from 0 ° to 180 °, the ultrasonic motor It is the figure which showed an example of the rotation speed (speed). It is a figure which shows the starting characteristic of the speed of an ultrasonic motor at the time of driving an ultrasonic transducer by mode A, mode C, mode B, and mode M. It is a figure which shows the fall characteristic of the speed of an ultrasonic motor at the time of driving an ultrasonic transducer by mode A, mode C, mode B, and mode M. It is a figure which shows the relationship between the voltage value of an alternating voltage, and the speed of an ultrasonic motor.

Explanation of symbols

10a to 10c Ultrasonic vibrator 12 Friction contact 50 Driven body 20a to 20c Drive unit 21a to 21c Transmitter 22 Control unit

Claims (6)

In the ultrasonic motor driving apparatus that drives the ultrasonic motor by individually supplying a two-phase alternating voltage having a predetermined driving frequency to each of the plurality of ultrasonic vibrators included in the ultrasonic motor,
An ultrasonic motor drive device that controls the speed of the ultrasonic motor by individually controlling the phase difference between the two-phase alternating voltages supplied to the ultrasonic transducers. In the ultrasonic motor driving apparatus that drives the ultrasonic motor by supplying a two-phase alternating voltage having a predetermined driving frequency to each of the plurality of ultrasonic vibrators included in the ultrasonic motor,
Driving the ultrasonic motor that controls the speed of the ultrasonic motor by supplying the same two-phase alternating voltage to each of the plurality of ultrasonic vibrators and controlling the phase difference between the alternating voltages apparatus. In the driving method of the ultrasonic motor for driving the ultrasonic motor by individually supplying a two-phase alternating voltage of a predetermined driving frequency to each of the plurality of ultrasonic vibrators included in the ultrasonic motor,
An ultrasonic motor driving method for controlling a speed of the ultrasonic motor by individually controlling a phase difference between the two-phase alternating voltages supplied to the ultrasonic vibrators. In the ultrasonic motor driving method for driving the ultrasonic motor by supplying a two-phase alternating voltage having a predetermined driving frequency to each of the plurality of ultrasonic vibrators included in the ultrasonic motor,
Driving the ultrasonic motor that controls the speed of the ultrasonic motor by supplying the same two-phase alternating voltage to each of the plurality of ultrasonic vibrators and controlling the phase difference of the alternating voltage Method. An ultrasonic motor comprising a plurality of ultrasonic transducers;
A driving device for driving the ultrasonic motor by individually supplying a two-phase alternating voltage having a predetermined driving frequency to each of the ultrasonic vibrators;
The ultrasonic motor system that controls the speed of the ultrasonic motor by individually controlling a phase difference between the two-phase alternating voltages supplied to the ultrasonic transducers. An ultrasonic motor comprising a plurality of ultrasonic transducers;
A drive device for driving the ultrasonic motor by supplying a two-phase alternating voltage of a predetermined drive frequency to each of the ultrasonic transducers;
The drive device supplies the same two-phase alternating voltage to each of the plurality of ultrasonic vibrators, and controls the speed of the ultrasonic motor by controlling the phase difference between the alternating voltages. Ultrasonic motor system.

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