JP2020054152A - Control method of piezoelectric driving device, piezoelectric driving device, robot, and printer - Google Patents

Abstract

To provide a control method of a piezoelectric driving device with excellent driving performance, a piezoelectric driving device, a robot, and a printer.SOLUTION: A control method of a piezoelectric driving device has a driving piezoelectric element, a vibrator vibrating by applying a driving signal to the driving piezoelectric element, a driven portion moving by vibration of the vibrator, a driving signal generation section generating a pulse signal on the basis of a target Duty and generating a driving signal on the basis of the pulse signal. According to a difference between the target Duty and Duty of the pulse signal, voltage supplied to the driving signal generation section is changed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control method for a piezoelectric driving device, a piezoelectric driving device, a robot, and a printer.

  The ultrasonic motor system described in Patent Literature 1 includes an ultrasonic oscillator, a driven body driven by the ultrasonic oscillator, and a driving device that applies a drive voltage to the ultrasonic oscillator. The drive device includes a signal generation circuit that outputs a pulse signal, and a drive circuit that generates a drive signal having a waveform close to a sine wave from the pulse signal output from the signal generation circuit, and is output from the drive circuit. The applied drive signal is applied to the ultrasonic transducer.

  Also, the ultrasonic motor system adjusts the amplitude of the drive signal by changing the duty of the pulse signal output from the signal generation circuit within a range of 0% to 50%, and controls the drive speed of the driven body. . Specifically, the driven body is decelerated by changing the duty of the pulse signal to the 0% side, and conversely, the driven body is accelerated by changing the duty to the 50% side.

  Also, when decelerating the driven body, the ultrasonic motor system changes the duty of the pulse signal to the 0% side, and changes the frequency of the drive signal to the resonance frequency side of the ultrasonic vibrator. When the driving body is accelerated, the duty of the pulse signal is changed to the 50% side, and the frequency of the driving signal is changed to the side away from the resonance frequency of the ultrasonic transducer.

JP 2010-183816 A

  However, in the case of a configuration like the ultrasonic motor system disclosed in Patent Document 1, since the ultrasonic transducer is driven by the drive signal generated from the pulse signal, the drive of the ultrasonic transducer may be unstable at a low speed. .

A method of controlling a piezoelectric driving device according to the present invention includes a driving body that includes a driving piezoelectric element and vibrates by applying a driving signal to the driving piezoelectric element.
A driven part that is moved by the vibration of the vibrating body,
A drive signal generation unit that generates a pulse signal based on the target duty, and generates a drive signal based on the pulse signal, comprising:
The magnitude of the voltage supplied to the drive signal generator may be changed according to the difference between the target duty and the duty of the pulse signal.

It is a top view showing the piezoelectric motor concerning a 1st embodiment of the present invention. It is a top view showing a piezoelectric actuator. FIG. 3 is a sectional view taken along line AA in FIG. 2. FIG. 3 is a sectional view taken along line BB in FIG. 2. FIG. 3 is a sectional view taken along line CC in FIG. 2. It is DD sectional drawing in FIG. FIG. 4 is a diagram illustrating a drive signal. FIG. 3 is a plan view showing a driving state of a piezoelectric motor. FIG. 3 is a plan view showing a driving state of a piezoelectric motor. It is a block diagram showing a control device. FIG. 4 is a diagram for explaining the duty of a pulse signal. FIG. 3 is a circuit diagram illustrating a first drive circuit. It is a figure showing a problem when Duty is too small. 4 is a flowchart illustrating a control method by the control device. 4 is a graph showing a control method by the control device. 5 is a graph showing a relationship between the duty of a pulse signal and the amplitude of a drive signal. It is a flowchart which shows the control method by the control apparatus with which the piezoelectric motor which concerns on 2nd Embodiment of this invention is provided. 4 is a graph showing a control method by the control device. It is a graph which shows the control method by the control apparatus with which the piezoelectric motor concerning a 3rd embodiment of the present invention is provided. It is a graph which shows the control method by the control apparatus with which the piezoelectric motor concerning a 3rd embodiment of the present invention is provided. It is a graph which shows the control method by the control apparatus with which the piezoelectric motor concerning a 3rd embodiment of the present invention is provided. It is a graph which shows the control method by the control apparatus with which the piezoelectric motor concerning a 3rd embodiment of the present invention is provided. It is a perspective view showing the robot concerning a 4th embodiment of the present invention. FIG. 13 is a schematic diagram illustrating an overall configuration of a printer according to a fifth embodiment of the present invention.

  Hereinafter, a control method of a piezoelectric driving device, a piezoelectric driving device, a robot and a printer according to the present invention will be described in detail based on embodiments shown in the accompanying drawings.

<First embodiment>
FIG. 1 is a plan view showing a piezoelectric motor according to the first embodiment of the present invention. FIG. 2 is a plan view showing the piezoelectric actuator. FIG. 3 is a sectional view taken along line AA in FIG. FIG. 4 is a sectional view taken along line BB in FIG. FIG. 5 is a sectional view taken along line CC in FIG. FIG. 6 is a sectional view taken along line DD in FIG. FIG. 7 is a diagram illustrating a drive signal. 8 and 9 are plan views each showing a driving state of the piezoelectric motor. FIG. 10 is a block diagram illustrating the control device. FIG. 11 is a diagram for describing the duty (duty) of the pulse signal. FIG. 12 is a circuit diagram showing the first drive circuit. FIG. 13 is a diagram illustrating a problem when the duty is too small. FIG. 14 is a flowchart illustrating a control method by the control device. FIG. 15 is a graph showing a control method by the control device.

  In the following, for convenience of explanation, three axes orthogonal to each other are referred to as an X axis, a Y axis, and a Z axis, a direction along the X axis is an X axis direction, a direction along the Y axis is a Y axis direction (first direction), The direction along the Z axis is also referred to as the Z axis direction (second direction). Further, the arrow side of each axis is also referred to as “plus side”, and the side opposite to the arrow is also referred to as “minus side”. Further, the plus side in the X-axis direction is also referred to as “upper” or “upper side”, and the minus side in the X-axis direction is also referred to as “lower” or “lower side”.

  The piezoelectric motor 1 shown in FIG. 1 is a piezoelectric driving device, and is in the form of a disk, and is in contact with a rotor 2 as a driven portion rotatable around its central axis O, and an outer peripheral surface 21 of the rotor 2, and And a driving unit 3 that rotates around the central axis O. The drive unit 3 includes a piezoelectric actuator 4, an urging member 5 for urging the piezoelectric actuator 4 toward the rotor 2, and a control device 7 for controlling the driving of the piezoelectric actuator 4. In such a piezoelectric motor 1, when the piezoelectric actuator 4 bends and vibrates, the vibration is transmitted to the rotor 2, and the rotor 2 rotates around the central axis O.

  The configuration of the piezoelectric motor 1 is not limited to the configuration shown in FIG. For example, a plurality of driving units 3 may be arranged along the circumferential direction of the rotor 2, and the rotor 2 may be rotated by driving the plurality of driving units 3. In addition, the drive unit 3 may be in contact with the main surface 22 of the rotor 2 instead of the outer peripheral surface 21 of the rotor 2. Further, the driven portion is not limited to a rotating body such as the rotor 2, and may be, for example, a slider that moves linearly.

  Further, in the present embodiment, the encoder 9 is provided in the rotor 2, and the behavior of the rotor 2, particularly, the rotation amount and the angular velocity can be detected by the encoder 9. The encoder 9 is not particularly limited, and may be, for example, an incremental encoder that detects the amount of rotation of the rotor 2 when the rotor 2 rotates, or regardless of whether or not the rotor 2 rotates, from the origin of the rotor 2. An absolute encoder that detects an absolute position may be used.

  The encoder 9 of the present embodiment has a scale 91 fixed to the upper surface of the rotor 2 and an optical element 92 provided above the scale 91. The scale 91 has a disk shape, and a pattern (not shown) is provided on an upper surface thereof. On the other hand, the optical element 92 includes a light emitting element 921 that irradiates light toward the pattern of the scale 91 and an image sensor 922 that captures an image of the pattern of the scale 91. In the encoder 9 having such a configuration, the amount of rotation, the driving speed, the absolute position, and the like of the rotor 2 can be detected by performing template matching on the image of the pattern acquired by the imaging element 922. However, the configuration of the encoder 9 is not limited to the above configuration. For example, a configuration including a light receiving element that receives reflected light or transmitted light from the scale 91 may be used instead of the imaging element 922.

  As shown in FIG. 2, the piezoelectric actuator 4 is connected to the vibrating body 41, a supporting section 42 supporting the vibrating body 41, a connecting section 43 connecting the vibrating body 41 and the supporting section 42, and connected to the vibrating body 41. And a projection 44 for transmitting the vibration of the vibrating body 41 to the rotor 2.

  The vibrating body 41 has a plate shape that extends in the YZ plane including the Y axis and the Z axis with the X axis direction as the thickness direction, and is bent in the Z axis direction while expanding and contracting in the Y axis direction. Bending vibration. Further, the vibrating body 41 has a longitudinal shape having a longitudinal direction in the Y-axis direction, which is a direction of expansion and contraction, in a plan view from the X-axis direction. However, the shape of the vibrating body 41 is not particularly limited as long as the function can be exhibited.

  As shown in FIG. 2, the vibrating body 41 includes driving piezoelectric elements 6A to 6E for bending and vibrating the vibrating body 41, and detecting piezoelectric elements 6F for detecting vibration of the vibrating body 41. 6G.

  The piezoelectric element 6C is arranged at the center of the vibrating body 41 along the Y-axis direction, which is the longitudinal direction of the vibrating body 41. With respect to the piezoelectric element 6C, the piezoelectric elements 6A and 6B are arranged along the longitudinal direction of the vibrating body 41 on the plus side in the Z-axis direction of the vibrating body 41, and the piezoelectric elements 6D and 6E vibrate on the minus side in the Z-axis direction. They are arranged side by side in the longitudinal direction of the body 41. Each of the piezoelectric elements 6A to 6E expands and contracts in the Y-axis direction, which is the longitudinal direction of the vibrating body 41, by being energized. The piezoelectric elements 6A and 6E are electrically connected to each other, and the piezoelectric elements 6B and 6D are electrically connected to each other.

  As will be described later, drive signals V1, V2, V3 (alternating voltages) having the same frequency but different phases are applied to the piezoelectric element 6C, the piezoelectric elements 6A, 6E, and the piezoelectric elements 6B, 6D, and these expand and contract. By shifting the timing, the vibrating body 41 can be bent and vibrated in an S-shape in the plane.

  The piezoelectric element 6F is located on the Y axis direction plus side of the piezoelectric element 6C, and the piezoelectric element 6G is located on the Y axis direction minus side of the piezoelectric element 6C. Further, the piezoelectric elements 6F and 6G are electrically connected to each other. These piezoelectric elements 6F and 6G receive an external force corresponding to the vibration of the vibrating body 41 accompanying the driving of the piezoelectric elements 6A to 6E, and output a signal corresponding to the received external force. Therefore, the vibration state of the vibrating body 41 can be detected based on the signals output from the piezoelectric elements 6F and 6G.

  The connecting portion 43 connects a portion serving as a node of the bending vibration of the vibrating body 41, specifically, a center portion in the Y-axis direction and the supporting portion 42. In addition, the connection portion 43 has a first connection portion 431 located on the minus side in the Z-axis direction with respect to the vibrating body 41 and a second connection portion 432 located on the plus side in the Z-axis direction. However, the configuration of the connection unit 43 is not particularly limited.

  As shown in FIGS. 3 to 6, the vibrating body 41, the supporting portion 42, and the connecting portion 43 have a configuration in which two piezoelectric element units 60 are attached to each other so as to face each other. Each of the piezoelectric element units 60 includes a substrate 61, driving piezoelectric elements 60A, 60B, 60C, 60D, and 60E, and detecting piezoelectric elements 60F and 60G, and piezoelectric elements 60A to 60G arranged on the substrate 61. And a covering protective layer 63.

  The piezoelectric elements 60A to 60G include a first electrode 601 disposed on the substrate 61, a piezoelectric body 602 disposed on the first electrode 601, and a second electrode 603 disposed on the piezoelectric body 602, respectively. Having. The first electrode 601 is provided commonly to the piezoelectric elements 60A to 60G. On the other hand, the piezoelectric body 602 and the second electrode 603 are individually provided for the piezoelectric elements 60A to 60G, respectively.

  The two piezoelectric element units 60 are joined via an adhesive 69 with the surfaces on which the piezoelectric elements 60A to 60G are arranged facing each other. In addition, the first electrodes 601 of each piezoelectric element unit 60 are electrically connected to each other via a wiring (not shown) or the like. Further, the second electrodes 603 of the piezoelectric elements 60A of the respective piezoelectric element units 60 are electrically connected to each other via wiring (not shown), and the two piezoelectric elements 60A constitute a piezoelectric element 6A. The same applies to the other piezoelectric elements 60B to 60G. Two piezoelectric elements 60B constitute a piezoelectric element 6B, two piezoelectric elements 60C constitute a piezoelectric element 6C, and two piezoelectric elements 60D constitute a piezoelectric element 6D. The two piezoelectric elements 60E constitute a piezoelectric element 6E, the two piezoelectric elements 60F constitute a piezoelectric element 6F, and the two piezoelectric elements 60G constitute a piezoelectric element 6G.

  The constituent material of the piezoelectric body 602 is not particularly limited, and for example, lead zirconate titanate (PZT), barium titanate, lead titanate, potassium niobate, lithium niobate, lithium tantalate, sodium tungstate, sodium oxide, Piezoelectric ceramics such as zinc, barium strontium titanate (BST), strontium bismuth tantalate (SBT), lead metaniobate, and lead scandium niobate can be used. Further, as the piezoelectric body 602, polyvinylidene fluoride, quartz, or the like may be used in addition to the piezoelectric ceramics described above.

  The method for forming the piezoelectric body 602 is not particularly limited, and the piezoelectric body 602 may be formed from a bulk material, or may be formed using a sol-gel method or a sputtering method. In the present embodiment, the piezoelectric body 602 is formed using a sol-gel method. Thus, for example, a piezoelectric body 602 that is thinner than when formed from a bulk material is obtained, and the driving unit 3 can be made thinner.

  The protrusion 44 is provided at the tip of the vibrating body 41 and protrudes from the vibrating body 41 to the plus side in the Y-axis direction. The tip of the projection 44 is in contact with the outer peripheral surface 21 of the rotor 2. Therefore, the vibration of the vibrating body 41 is transmitted to the rotor 2 via the protrusion 44.

  For example, when the drive signal V1 shown in FIG. 7 is applied to the piezoelectric elements 6A and 6E, the drive signal V2 is applied to the piezoelectric element 6C, and the drive signal V3 is applied to the piezoelectric elements 6B and 6D, as shown in FIG. The vibrating body 41 bends and vibrates in the S-shape in the Z-axis direction while expanding and contracting in the Y-axis direction, and these vibrations are combined, so that the tip of the convex portion 44 has a counterclockwise elliptical orbit as indicated by an arrow A1. Make an elliptical motion (rotational motion). The rotor 2 is sent out by such an elliptical motion of the convex portion 44, and the rotor 2 rotates clockwise as indicated by an arrow B1. Further, in response to such vibration of the vibrating body 41, the pickup voltage Vpu is output from the piezoelectric elements 6F and 6G.

  When the drive signals V1 and V3 are switched, that is, when the drive signal V1 is applied to the piezoelectric elements 6B and 6D, the drive signal V2 is applied to the piezoelectric element 6C, and the drive signal V3 is applied to the piezoelectric elements 6A and 6E. As shown in FIG. 9, the vibrating body 41 bends and vibrates in the S-shape in the Z-axis direction while expanding and contracting in the Y-axis direction, and these vibrations are combined, and the convex portion 44 is turned clockwise as indicated by an arrow A2. Elliptical motion. The rotor 2 is sent out by such an elliptical motion of the convex portion 44, and the rotor 2 rotates counterclockwise as indicated by an arrow B2. Further, in response to such vibration of the vibrating body 41, the pickup voltage Vpu is output from the piezoelectric elements 6F and 6G.

  As described above, the expansion and contraction of the piezoelectric elements 6A, 6B, 6D, and 6E causes the convex portion 44 to bend and vibrate in the Z-axis direction, thereby sending the rotor 2 in the direction of the arrow B1 or the arrow B2. Therefore, by controlling the amplitudes of the drive signals V1 and V3 applied to the piezoelectric elements 6A, 6B, 6D and 6E and controlling the amplitude of the protrusions 44 in the Z-axis direction, the drive speed (angular velocity) of the rotor 2 is reduced. Can be controlled. Specifically, if the amplitudes of the drive signals V1 and V3 are increased, the amplitude of the protrusions 44 in the Z-axis direction is increased and the drive speed of the rotor 2 is increased. Conversely, the amplitudes of the drive signals V1 and V3 are reduced. If the size is reduced, the amplitude of the protrusion 44 in the Z-axis direction is reduced, and the driving speed of the rotor 2 is reduced.

  In the present invention, the pattern of the drive signal applied to the piezoelectric elements 6A to 6E is not particularly limited as long as the rotor 2 can be rotated in at least one direction. Further, the voltage applied to the piezoelectric elements 6A to 6E may be, for example, a DC voltage intermittently applied instead of the drive signal.

  The control device 7 controls the drive of the drive unit 3 by applying drive signals V1, V2, and V3, which are alternating voltages, to the piezoelectric elements 6A to 6E. In the following, for convenience of description, a case where the rotor 2 is rotated in the direction of arrow B1 as illustrated in FIG. 8 will be described as a representative. As shown in FIG. 9, the case where the rotor 2 is rotated in the direction of the arrow B2 is the same as the case where the rotor 2 is rotated in the direction of the arrow B1, and a description thereof will be omitted.

  As shown in FIG. 10, the control device 7 generates drive signals V1, V2, and V3, and applies the generated drive signals V1, V2, and V3 to the corresponding piezoelectric elements 6A, 6B, 6C, 6D, and 6E. It has a control unit 70.

  The voltage control unit 70 includes a first voltage control unit 71 that applies drive signals V1 and V3 to the piezoelectric elements 6A, 6B, 6D, and 6E that bends and vibrates the vibrating body 41 in the Z-axis direction. A second voltage control unit 78 that applies a drive signal V2 to the piezoelectric element 6C that causes the piezoelectric device 6C to expand and contract and a frequency control unit 79 that controls the frequencies of the drive signals V1, V2, and V3. The voltage control unit 70 controls the drive speed of the rotor 2 by changing the amplitudes of the drive signals V1 and V3 so that the rotor 2 is at the target position at each time. Accordingly, the displacement of the rotor 2 with respect to the target position at each time can be suppressed, and the piezoelectric motor 1 having excellent driving characteristics can be obtained.

  As shown in FIG. 10, the first voltage control unit 71 includes a position command control unit 711, a position control unit 712, a speed control unit 713, a first drive signal generation unit 72 that generates a drive signal V1, and a drive A second drive signal generation unit 73 that generates the signal V3.

  The first drive signal generation unit 72 includes a first drive voltage control unit 721, a first PWM waveform generation unit 722, a first drive circuit 723, a first voltage command control unit 724, and a first voltage supply unit 725. And Similarly, the second drive signal generation unit 73 includes a second drive voltage control unit 731, a second PWM waveform generation unit 732, a second drive circuit 733, a second voltage command control unit 734, and a second voltage supply unit. 735. The first voltage control unit 71 controls the drive signals V1 and V3 so that the position of the rotor 2 becomes the target position at each time by feeding back the signal output from the encoder 9. Note that the above “PWM” is an abbreviation for “Pulse Width Modulation”.

  The position command control unit 711 generates and outputs a position command Ma indicating a target position of the rotor 2 based on a command from a host computer (not shown), for example. The position control unit 712 performs P control for performing proportional control for adjusting a proportional gain with respect to a deviation between the position command Ma and the current position of the rotor 2 detected by the encoder 9, and a position based on the position command Ma is obtained. A speed command Mb indicating the target speed of the rotor 2 is generated. The speed control unit 713 adjusts a proportional gain for a deviation between the speed command Mb generated by the position control unit 712 and the current drive speed of the rotor 2 detected by the encoder 9, and an integral control for adjusting an integral gain. And a PI control that performs the control, and generates a voltage command Mc indicating a target drive voltage that is a drive speed based on the speed command Mb.

  The first drive voltage control unit 721 performs a proportional control for adjusting a proportional gain with respect to a deviation between the voltage command Mc and the drive signal V1 generated by the first drive circuit 723, and an integral control for adjusting an integral gain. The PI control to be performed is performed, and the duty command Md1 indicating the target duty which becomes the voltage (amplitude) based on the voltage command Mc is generated. The first PWM waveform generator 722 has a duty based on the duty command Md1 and generates a pulse signal Pd1 having a frequency based on the frequency command Mg generated by the frequency controller 79. Then, the first drive circuit 723 generates a drive signal V1 from the pulse signal Pd1.

  Here, the duty of the pulse signal Pd1 is a ratio of L and H of the pulse width, as shown in FIG. 11, and can be changed in a range of 0% to 50%. As the duty of the pulse signal Pd1 approaches 0%, the amplitude (voltage) of the drive signal V1 generated by the first drive circuit 723 decreases, and conversely, as the duty of the pulse signal Pd1 approaches 50%, the first The amplitude (voltage) of the drive signal V1 generated by the drive circuit 723 increases. Therefore, as the duty of the pulse signal Pd1 approaches 0%, the driving speed of the rotor 2 decreases, and conversely, as the duty of the pulse signal Pd1 approaches 50%, the driving speed of the rotor 2 increases.

  Here, when the duty of the pulse signal Pd1 decreases, the waveform of the drive signal V1 generated by the first drive circuit 723 breaks from a sine wave. In particular, in a region where the duty of the pulse signal Pd1 is close to 0%, the problem becomes significant. One reason for this will be briefly described. As shown in FIG. 12, the first drive circuit 723 has, for example, two switching elements 723a and 723b composed of MOSFETs and the like, and an LC resonance circuit 723c including a coil L and a capacitor C. Then, the inverted pulse signal Pd1 is input to the switching elements 723a and 723b. When the pulse signal Pd1 is at H, the switching elements 723a and 723b are turned on. When the pulse signal Pd1 is at L, the switching elements 723a and 723b are turned off. Becomes

  When the duty of the pulse signal Pd1 is close to 0%, the waveform of the pulse signal Pd1 is indicated by a dashed line as shown in FIG. 13 depending on the wiring resistance between the first PWM waveform generator 722 and the first drive circuit 723. There is a case where the voltage value at the time of H collapses from the ideal rectangular wave (without rising) and cannot cross the voltage threshold SH for switching ON / OFF of the switching elements 723a and 723b. When such waveform collapse occurs, the switching elements 723a and 723b cannot be turned on / off at an appropriate timing. As a result, the waveform of the pulse signal Pd1 further collapses from a sine wave, and the above-described problem becomes more prominent. It becomes something.

  Therefore, the first PWM waveform generator 722 is set with the duty lower limit DL, and the first PWM waveform generator 722 outputs a pulse signal having a duty less than the duty lower limit DL irrespective of the target duty indicated in the duty command Md1. Do not generate Pd1. Specifically, if the target duty is equal to or greater than the duty lower limit DL, the first PWM waveform generator 722 generates a pulse signal Pd1 having a duty equal to the target duty. On the other hand, if the target duty is less than the duty lower limit DL, the first PWM waveform generator 722 generates a pulse signal Pd1 having a duty equal to the duty lower limit DL. As described above, since the first PWM waveform generation unit 722 does not generate the pulse signal Pd1 having a duty less than the duty lower limit DL, the generation of the pulse signal Pd1 having a duty close to 0% is suppressed, and the above-described problem, that is, the pulse signal Pd1 is suppressed. Waveform collapse of Pd1 can be effectively suppressed.

  The duty lower limit DL is not particularly limited, but may be, for example, 10%. Thereby, the above-mentioned effect becomes more remarkable. In the above description, when the target Duty is less than the Duty lower limit DL, the first PWM waveform generator 722 generates the pulse signal Pd1 of Duty equal to the Duty lower limit DL, but is not limited thereto, and the first PWM is not limited to this. The waveform generation unit 722 may generate the duty pulse signal Pd1 that is larger than the duty lower limit DL, for example, the duty pulse signal Pd1 of about 11% to 15% when the duty lower limit DL is 10%.

  As described above, since the amplitude of the drive signal V1 changes according to the Duty of the pulse signal Pd1, the target Duty is smaller than the Duty lower limit DL, and the first PWM waveform generation unit 722 generates the Duty pulse signal Pd1 larger than the target Duty. When it is generated, the amplitude of the drive signal V1 becomes larger than the target value. Therefore, the first drive signal generation unit 72 includes a first voltage command control unit 724 and a first voltage supply unit 725 in order to correct the deviation of the amplitude of the drive signal V1. In the first drive signal generation unit 72, the amplitude of the drive signal V1 is changed by changing the magnitude of the voltage supplied to the first drive circuit 723 by the first voltage command control unit 724 and the first voltage supply unit 725. Correct the deviation from the target value. Here, the “target value” means the amplitude of the drive signal V1 generated from the pulse signal Pd1 having the same Duty as the target Duty.

  The first voltage command control unit 724 generates a supply voltage command Me1 indicating a target voltage at which the amplitude of the drive signal V1 reaches a target value, based on a difference ΔD between the target duty indicated by the duty command Md1 and the duty of the pulse signal Pd1. Generate. The first voltage supply unit 725 controls the magnitude of the voltage supplied to the first drive circuit 723 based on the supply voltage command Me1. The first voltage supply unit 725, for example, as shown in FIG. 12, supplies a power supply 725a that supplies a power supply voltage VDD that is a fixed voltage and a power supply voltage VDD supplied from the power supply 725a based on a supply voltage command Me1. A DC / DC converter 725b that converts the voltage to a voltage value.

  For example, when the target duty is equal to or greater than the duty lower limit DL and the duty of the pulse signal Pd1 is equal to the target duty, that is, when ΔD = 0, the first voltage supply unit 725 sends the reference voltage V ′ to the first drive circuit 723. Supply. The reference voltage V 'means that the various commands described above are generated based on this voltage. On the other hand, when the target duty is smaller than the duty lower limit DL and the duty of the pulse signal Pd1 is larger than the target duty, that is, when ΔD ≠ 0, the first voltage supply unit 725 sets the target voltage lower than the reference voltage V ′. The voltage V ″ is supplied to the first drive circuit 723. The voltage V ″ decreases as the difference ΔD increases.

  In summary, as shown in FIGS. 14 and 15, when the target duty is equal to or more than the duty lower limit value DL, the voltage supplied to the first drive circuit 723 is fixed, and the pulse signal Pd1 of the duty equal to the target duty is output. The amplitude of the drive signal V1 is controlled by generating and changing the duty of the pulse signal Pd1. On the other hand, when the target Duty is less than the Duty lower limit DL, a pulse signal Pd1 of Duty equal to the Duty lower limit is generated, and the amplitude of the drive signal V1 is changed by changing the voltage supplied to the first drive circuit 723. Control.

  According to such a driving method, it is possible to effectively suppress the waveform collapse of the pulse signal Pd1 due to the decrease in the duty of the pulse signal Pd1. Further, a deviation in amplitude due to a difference ΔD between the target duty and the duty of the pulse signal Pd1 can be corrected by the magnitude of the voltage supplied to the first drive circuit 723. Therefore, the deviation of the amplitude of the drive signal V1 from the target value can be effectively suppressed. Therefore, the displacement of the rotor 2 with respect to the target position at each time can be suppressed, and the piezoelectric motor 1 having excellent driving characteristics can be obtained.

  Further, by combining the control of the duty of the pulse signal Pd1 with the control of the voltage supplied to the first drive circuit 723, compared with the conventional case where the amplitude of the drive signal V1 is controlled only by the duty of the pulse signal Pd1. , A driving signal V1 having a smaller amplitude can be obtained. Therefore, the controllable minimum value of the amplitude of the drive signal V1 increases, and the dynamic range of the amplitude of the drive signal V1 increases. Therefore, the piezoelectric motor 1 has more excellent driving characteristics.

  The second drive signal generator 73 has the same configuration as the first drive signal generator 72. Therefore, the second drive signal generation unit 73 will be briefly described below. The second drive voltage control unit 731 performs PI control based on the voltage command Mc and the drive signal V3 generated by the second drive circuit 733, and the amplitude (voltage) of the drive signal V3 becomes a voltage based on the voltage command Mc. A duty command Md2 indicating the target duty is generated. The second PWM waveform generator 732 generates a pulse signal Pd2 having a target duty and having a frequency based on the frequency command Mg generated by the frequency controller 79. The duty lower limit DL is set in the second PWM waveform generator 732, and the second PWM waveform generator 732 does not generate the pulse signal Pd2 having the duty less than the duty lower limit DL regardless of the target duty. Then, the second drive circuit 733 generates a drive signal V3 based on the pulse signal Pd2.

  The second voltage command control unit 734 generates a supply voltage command Me2 indicating a target voltage at which the amplitude of the drive signal V3 becomes a target value, based on the difference ΔD between the target duty and the duty of the pulse signal Pd2. The second voltage supply unit 735 controls the magnitude of the voltage supplied to the second drive circuit 733 based on the supply voltage command Me2. This makes it possible to effectively suppress the deviation of the amplitude of the drive signal V3 from the target value. Further, the dynamic range of the amplitude of the drive signal V3 is widened. Therefore, the piezoelectric motor 1 has more excellent driving characteristics.

  As shown in FIG. 10, the second voltage control unit 78 has a PU voltage control unit 781 and a third drive signal generation unit 77 that generates a drive signal V2 applied to the piezoelectric element 6C. The third drive signal generation unit 77 includes a third drive voltage control unit 771, a third PWM waveform generation unit 772, a third drive circuit 773, a third voltage command control unit 774, and a third voltage supply unit 775. And The second voltage control unit 78 controls the drive signal V2 so that the pickup voltage Vpu becomes a target value by feeding back the pickup voltage Vpu output from the piezoelectric elements 6F and 6G. By maintaining the pickup voltage Vpu at the target value, the vibrating body 41 vibrates stably in the Y-axis direction, so that the piezoelectric motor 1 can be driven stably.

  The PU voltage control unit 781 receives an amplitude command that is a target amplitude value of the pickup voltage Vpu from a host computer (not shown) and the pickup voltage Vpu output from the piezoelectric elements 6F and 6G. PU voltage control section 781 performs PI control for performing a proportional control for adjusting a proportional gain with respect to a deviation between the amplitude command and pickup voltage Vpu and an integral control for adjusting an integral gain. A voltage command Mf is generated so as to have an amplitude based on.

  The third drive signal generator 77 has the same configuration as the first and second drive signal generators 72 and 73. Therefore, the third drive signal generator 77 will be briefly described below. The third drive voltage control unit 771 performs proportional control for adjusting a proportional gain with respect to a deviation between the voltage command Mf and the drive signal V2 generated by the third drive circuit 773, and integral control for adjusting an integral gain. The PI control is performed, and the duty command Md3 indicating the target duty at which the amplitude (voltage) of the drive signal V2 becomes the voltage based on the voltage command Mf is generated.

  The third PWM waveform generator 772 generates a pulse signal Pd3 having a target duty and having a frequency based on the frequency command Mg generated by the frequency controller 79. The duty lower limit DL is set in the third PWM waveform generator 772, and the third PWM waveform generator 772 does not generate the pulse signal Pd3 having the duty less than the duty lower limit DL regardless of the target duty. Then, the third drive circuit 773 generates a drive signal V2 based on the pulse signal Pd3.

  The third voltage command control unit 774 generates a supply voltage command Me3 indicating a target voltage at which the amplitude of the drive signal V2 becomes a target value, based on the difference ΔD between the target duty and the duty of the pulse signal Pd3. The third voltage supply unit 775 controls the magnitude of the voltage supplied to the third drive circuit 773 based on the supply voltage command Me3. Thereby, the deviation of the amplitude of the drive signal V2 from the target value can be effectively suppressed. Further, the dynamic range of the amplitude of the drive signal V2 is widened. Therefore, the piezoelectric motor 1 has more excellent driving characteristics.

  The drive signal V2 generated by the third drive circuit 773 and the pickup voltage Vpu output from the piezoelectric elements 6F and 6G are input to the frequency control unit 79. The frequency control unit 79 obtains a phase difference between the drive signal V2 and the pickup voltage Vpu, and adjusts a proportional gain for a deviation between a preset target phase difference and an actual phase difference, and an integral gain. Is performed, and a frequency command Mg is generated such that the actual phase difference becomes a phase difference based on the target phase difference. The frequency command Mg generated by the frequency control unit 79 is transmitted to the first PWM waveform generation unit 722, the second PWM waveform generation unit 732, and the third PWM waveform generation unit 772, and the first PWM waveform generation unit 722 and the second PWM waveform generation The unit 732 and the third PWM waveform generation unit 772 generate drive signals V1 to V3 having a frequency based on the frequency command Mg.

  The piezoelectric motor 1 as the piezoelectric driving device has been described above. As described above, the control method of such a piezoelectric driving device includes the piezoelectric elements 6A to 6E, which are driving piezoelectric elements, and vibrates by applying the driving signals V1 to V3 to the piezoelectric elements 6A to 6E. 41, a rotor 2 as a driven part that is moved by the vibration of the vibrating body 41, generates pulse signals Pd1 to Pd3 based on the target Duty, and generates drive signals V1 to V3 based on the pulse signals Pd1 to Pd3. This is a method for controlling the piezoelectric motor 1 having first, second, and third drive circuits 723, 733, and 773 as drive signal generation units, wherein the difference ΔD between the target Duty and the duty of the pulse signals Pd1 to Pd3 is calculated. The magnitude of the voltage supplied to the first, second, and third driving circuits 723, 733, and 773 is changed accordingly.

  As described above, by changing the magnitude of the voltage supplied to the first, second, and third drive circuits 723, 733, and 773 in accordance with the difference ΔD, it is possible to prevent the duty of the pulse signals Pd1 to Pd3 from becoming too small. While suppressing, it is possible to effectively suppress the deviation of the amplitude of the drive signals V1 to V3 from the target value. Therefore, the piezoelectric motor 1 has excellent driving characteristics.

  Further, as described above, when the target Duty is less than the preset Duty lower limit DL, the pulse signals Pd1 to Pd3 having the Duty equal to the Duty lower limit DL are generated, and the first, second, and third driving are performed. The voltage supplied to the circuits 723, 733, and 773 is reduced. As described above, by reducing the voltage supplied to the first, second, and third drive circuits 723, 733, and 773, the deviation of the amplitude of the drive signals V1 to V3 from the target value due to the difference ΔD is corrected. be able to.

  Further, as described above, when the target Duty is larger than the Duty upper limit DH that is set in advance, the pulse signals Pd1 to Pd3 having the Duty equal to the Duty upper limit DH are generated, and the first, second, and third driving are performed. The voltage supplied to the circuits 723, 733, and 773 is increased. As described above, by increasing the voltage supplied to the first, second, and third drive circuits 723, 733, and 773, the deviation of the amplitude of the drive signals V1 to V3 from the target value due to the difference ΔD is corrected. be able to.

  Further, as described above, the piezoelectric motor 1 includes the piezoelectric elements 6A to 6E that are driving piezoelectric elements, and includes a vibrating body 41 that vibrates by applying drive signals V1 to V3 to the piezoelectric elements 6A to 6E, It has a rotor 2 as a driven part that is moved by the vibration of the body 41, and a voltage controller 70 that applies drive signals V1 to V3 to the piezoelectric elements 6A to 6E. Further, the voltage control unit 70 includes first, second, and third PWM waveforms as pulse signal generation units that generate pulse signals Pd1 to Pd3 based on the target duty included in the duty commands Md1 to Md3 that are input commands. First, second, and third drive circuits 723, 733, and 773 as drive signal generators that generate drive signals V1 to V3 based on pulse signals Pd1 to Pd3; , Second, and third drive circuits 723, 733, and 773 as first, second, and third voltage supply units 725, 735, and 775. In addition, the first, second, and third PWM waveform generation units 722, 732, and 772 generate pulse signals Pd1 to Pd3 having a duty lower limit DL and having a duty equal to or greater than the duty lower limit DL. Further, the first, second, and third voltage supply units 725, 735, and 775 provide the first, second, and third drive circuits 723 and 733 according to the difference ΔD between the target duty and the duty of the pulse signals Pd1 to Pd3. , 773 are changed.

  According to such a configuration, it is possible to prevent the duty of the pulse signals Pd1 to Pd3 from becoming too small, and thus it is possible to effectively suppress the waveform collapse of the drive signals V1 to V3. Further, by changing the magnitude of the voltage supplied to the first, second, and third drive circuits 723, 733, and 773 in accordance with the difference ΔD, the deviation of the amplitude of the drive signals V1 to V3 from the target value can be effectively reduced. Can be suppressed. Therefore, the piezoelectric motor 1 has excellent driving characteristics. Further, by combining the control of the duty of the pulse signals Pd1 to Pd3 and the control of the voltage supplied to the first to third drive circuits 723, 733, 773, only the duty of the pulse signals Pd1 to Pd3 is different from the conventional case. As compared with the case where the amplitudes of the drive signals V1 to V3 are controlled, the variable range of the amplitude of the drive signals V1 to V3, that is, the variable range of the drive speed of the rotor 2 is widened, and the piezoelectric motor 1 has more excellent drive characteristics.

  In the present embodiment, the duty control and the voltage control of the pulse signal as described above are performed for each of the drive signals V1 to V3. However, the present invention is not limited to this, and at least one of the drive signals V1 to V3 is used. It is sufficient that the above-described control is performed. In this case, for example, the above-described control may be performed on the driving signals V1 and V3, and the above-described control may not be performed on the driving signal V2. The drive signal V2 is a signal for causing the vibrating body 41 to vibrate in the Y-axis direction, and is not a signal for causing the vibrating body 41 to bend and vibrate like the drive signals V1 and V3. This is because it is difficult to contribute to the driving speed.

  Also, as described above, when the target duty is less than the duty lower limit DL, the first, second, and third PWM waveform generators 722, 732, and 772 output the pulse signals Pd1 to Pd1 having the duty equal to the duty lower limit DL. The Pd3 is generated, and the first, second, and third voltage supply units 725, 735, 775 reduce the voltage supplied to the first, second, and third drive circuits 723, 733, 773. Thus, the duty of the pulse signals Pd1 to Pd3 can be prevented from becoming too small, so that the waveform collapse of the drive signals V1 to V3 can be effectively suppressed. Further, it is possible to correct a deviation of the amplitude of the drive signals V1 to V3 from the target value due to the difference ΔD.

  Further, as described above, the piezoelectric motor 1 has the protrusion 44 connected to the vibrator 41 and in contact with the rotor 2. When the direction in which the vibrating body 41 and the convex portion 44 are arranged is the Y-axis direction as the first direction, the magnitude of the voltage supplied to the first and second drive circuits 723 and 733 is changed, so that the Y direction is changed. The magnitude of the vibration that bends and vibrates in the Z-axis direction as a second direction orthogonal to the axial direction is changed. Thereby, the bending vibration of the vibrating body 41 in the Z-axis direction can be accurately controlled, and the deviation of the rotor 2 from the target position can be accurately suppressed.

  Further, as described above, by changing the magnitude of the voltage supplied to the third drive circuit 773, the magnitude of the vibration that expands and contracts in the first direction is changed. Thereby, the expansion and contraction vibration of the vibrating body 41 in the Y-axis direction can be accurately controlled, and the rotor 2 can be driven smoothly.

<Second embodiment>
FIG. 16 is a graph showing the relationship between the duty of the pulse signal and the amplitude of the drive signal. FIG. 17 is a flowchart illustrating a control method by the control device provided in the piezoelectric motor according to the second embodiment of the present invention. FIG. 18 is a graph showing a control method by the control device.

  The piezoelectric motor 1 according to the present embodiment is the same as the piezoelectric motor 1 according to the above-described first embodiment except that the control method by the first, second, and third drive signal generation units 72, 73, and 77 is different. . In the following description, the piezoelectric motor 1 of the second embodiment will be described focusing on the differences from the first embodiment described above, and the description of the same items will be omitted. Since the control methods by the first, second, and third drive signal generation units 72, 73, and 77 are the same as each other, the first drive signal generation unit 72 will be described below as a representative, Description of the third drive signal generators 73 and 77 is omitted.

  In the first PWM waveform generation unit 722, the Duty upper limit DH is set together with the above-described Duty lower limit DL. Then, the first PWM waveform generation unit 722 does not generate the pulse signal Pd1 having the duty less than the duty lower limit DL and the pulse signal Pd1 having the duty exceeding the duty upper limit DH regardless of the duty command Md1. That is, the first PWM waveform generator 722 generates the pulse signal Pd1 having a duty within the range from the duty lower limit DL to the duty upper limit.

  The reason for setting the duty lower limit value DL in the pulse signal Pd1 is the same as that in the first embodiment described above, and thus the description thereof will be omitted. Hereinafter, the reason for setting the duty upper limit value DH in the pulse signal Pd1 will be described. I do.

  FIG. 16 shows the relationship between the duty of the pulse signal Pd1 and the amplitude of the drive signal V1. As can be seen from the figure, the relationship between the duty of the pulse signal Pd1 and the amplitude of the drive signal V1 is not linear, and in a region where the duty is around 50%, the duty ratio of the pulse signal Pd1 with respect to the variation of the duty increases as the duty increases. The amount of change in amplitude is small. Therefore, the dynamic range of the amplitude of the drive signal V1 is reduced.

  Therefore, the first PWM waveform generating section 722 is provided with a duty upper limit value DH, and when it is desired to obtain a drive signal V1 exceeding the amplitude generated by the pulse signal Pd1 having the duty upper limit value DH, the duty of the pulse signal Pd1 is further increased. Instead, the voltage supplied from the first voltage supply unit 725 to the first drive circuit 723 is increased. Thus, the deviation of the amplitude caused by the difference ΔD between the target duty and the duty of the pulse signal Pd1 can be corrected by the magnitude of the voltage supplied to the first drive circuit 723. Furthermore, the maximum value of the controllable amplitude of the drive signal V1 becomes larger than when the duty of the pulse signal Pd1 is increased to increase the amplitude of the drive signal V1. That is, the dynamic range of the amplitude of the drive signal V1 is widened. The details will be described below.

  If the target duty indicated by the duty command Md1 is equal to or smaller than the duty upper limit DH, the first PWM waveform generation unit 722 generates a pulse signal Pd1 having a duty equal to the target duty. On the other hand, if the target duty exceeds the duty upper limit DH, the first PWM waveform generator 722 generates a pulse signal Pd1 having a duty equal to the duty upper limit DH. The duty upper limit DH is not particularly limited, but may be, for example, 40%. As described above, in the present embodiment, when the target duty exceeds the duty upper limit value DH, the first PWM waveform generation unit 722 generates the pulse signal Pd1 having a duty equal to the duty upper limit value DH. For example, the first PWM waveform generation unit 722 may determine that the pulse signal Pd1 having a duty lower than the duty upper limit DH, for example, if the duty upper limit DH is 40%, a duty of about 35% to 39%. The pulse signal Pd1 may be generated.

  When the target duty exceeds the duty upper limit value DH and the first PWM waveform generator 722 generates the pulse signal Pd1 having a duty smaller than the target duty, the amplitude of the drive signal V1 generated by the first drive circuit 723 becomes equal to the target value. To become smaller. Therefore, the first drive signal generation unit 72 includes a first voltage command control unit 724 and a first voltage supply unit 725 in order to correct the deviation of the amplitude of the drive signal V1 from the target value.

  The first voltage command control unit 724 determines the target at which the amplitude of the drive signal V1 becomes the target value, based on the difference ΔD between the target duty indicated by the duty command Md1 and the duty of the pulse signal Pd1 generated by the first PWM waveform generation unit 722. A supply voltage command Me1 indicating a voltage is generated. The first voltage supply unit 725 controls the magnitude of the voltage supplied to the first drive circuit 723 based on the supply voltage command Me1. Specifically, when the target duty exceeds the duty upper limit value DH and the pulse signal Pd1 having a duty smaller than the target duty is generated, that is, when ΔD ≠ 0, the first voltage supply unit 725 sets the reference voltage V Is supplied to the first drive circuit 723. The voltage V "increases as the difference ΔD increases.

  In summary, as shown in FIGS. 17 and 18, when the target duty is equal to or more than the duty lower limit value DL and equal to or less than the upper limit value DH, the voltage supplied to the first drive circuit 723 is fixed and equal to the target duty. A duty pulse signal Pd1 is generated, and the amplitude of the drive signal V1 is controlled by changing the duty of the pulse signal Pd1. On the other hand, when the target Duty is less than the Duty lower limit DL, a pulse signal Pd1 of Duty equal to the Duty lower limit is generated, and the amplitude of the drive signal V1 is changed by changing the voltage supplied to the first drive circuit 723. Control. When the target duty exceeds the duty upper limit DH, a pulse signal Pd1 having a duty equal to the duty upper limit is generated, and the voltage supplied to the first drive circuit 723 is changed to change the amplitude of the drive signal V1. Control.

  As described above, in the present embodiment, the first PWM waveform generator 722 is provided with the duty upper limit value DH, and the drive signal V1 having an amplitude larger than the amplitude of the drive signal V1 generated by the pulse signal Pd1 having the duty upper limit value DH. If desired, the drive signal V1 having the target amplitude can be generated by increasing the voltage supplied to the first drive circuit 723. Furthermore, when the duty of the pulse signal Pd1 is increased to increase the amplitude of the drive signal V1, the duty near 50%, that is, the duty of the area where the amplitude change of the pulse signal Pd1 is small with respect to the duty change, must be used. However, there is a possibility that a drive signal V1 having a sufficiently large amplitude may not be obtained. However, according to the method of increasing the voltage supplied to the first drive circuit 723, such a problem does not occur, and a sufficiently large drive signal V1 can be obtained. A drive signal V1 having an amplitude of the same can be obtained. Therefore, the controllable maximum value of the amplitude of the drive signal V1 increases, and the dynamic range of the amplitude of the drive signal V1 increases.

  As described above, when the target duty becomes larger than the previously set duty upper limit value DH, the first, second, and third PWM waveform generators 722, 732, and 772 output a pulse signal having a duty equal to the duty upper limit value DH. Pd1 to Pd3 are generated, and the first, second, and third voltage supply units 725, 735, and 775 increase the voltage supplied to the first, second, and third drive circuits 723, 733, and 773. Thus, it is possible to suppress the duty of the pulse signals Pd1 to Pd3 from becoming too large. Further, it is possible to correct a deviation of the amplitude of the drive signals V1 to V3 from the target value due to the difference ΔD.

  According to the third embodiment as described above, the same effects as in the first embodiment can be exhibited.

<Third embodiment>
FIGS. 19 and 21 are graphs showing a control method by the control device provided in the piezoelectric motor according to the third embodiment of the present invention. FIGS. 20 and 22 are graphs showing a control method by the control device provided in the piezoelectric motor according to the third embodiment of the present invention.

  The piezoelectric motor 1 according to the present embodiment is the same as the piezoelectric motor 1 according to the above-described second embodiment except that the control method by the first, second, and third drive signal generation units 72, 73, and 77 is different. . In the following description, the piezoelectric motor 1 of the third embodiment will be described focusing on the differences from the first embodiment described above, and the description of the same items will be omitted. Since the control methods by the first, second, and third drive signal generation units 72, 73, and 77 are the same as each other, the first drive signal generation unit 72 will be described below as a representative, Description of the third drive signal generators 73 and 77 is omitted.

  For example, as shown in FIG. 19, when the target Duty changes near the Duty lower limit DL and moves up and down over the Duty lower limit DL, the target Duty is equal to or larger than the Duty lower limit DL and the duty of the pulse signal Pd1 is changed. Frequently switches between a state T1 in which the amplitude of the drive signal V1 is controlled and a state T2 in which the target Duty is less than the duty lower limit DL and the amplitude of the drive signal V1 is controlled by the voltage supplied to the first drive circuit 723. . As described above, when the states T1 and T2 are frequently switched, the amplitude control of the drive signal V1 is accurately performed, for example, the voltage supplied from the first voltage supply unit 725 to the first drive circuit 723 becomes unstable. May not be possible.

  Therefore, in the first PWM waveform generation unit 722 of the present embodiment, the duty lower limit DL has hysteresis to suppress frequent switching between the states T1 and T2. Hereinafter, this will be described in detail. As shown in FIG. 20, the first PWM waveform generator 722 is provided with a first duty lower limit DL1 and a second duty lower limit DL2 which is larger than the first duty lower limit DL1. Then, after the target duty becomes less than the first duty lower limit DL1 and the state is switched from the state T1 to the state T2, the states T1 and T2 are switched based on the second duty lower limit DL2. In other words, even if the target duty is equal to or greater than the first duty lower limit DL1, if the target duty is not equal to or greater than the second duty lower limit DL2, the state T2 is maintained. If the target duty is equal to or greater than the second duty lower limit DL2, the state T2 To state T1. When the target duty is equal to or more than the second duty lower limit DL2 and the state is switched from the state T2 to the state T1, the states T1 and T2 are switched again based on the first duty lower limit DL1.

  In this manner, the state Duty lower limit DL is provided with hysteresis, and the first duty lower limit DL1 for switching from the state T1 to the state T2 and the second duty lower limit DL2 for switching from the state T2 to the state T1 are set. , T2 can be prevented from frequently switching. Therefore, the voltage supplied from the first voltage supply unit 725 to the first drive circuit 723 is stabilized, and the amplitude control of the drive signal V1 can be accurately performed.

  Although the duty lower limit DL has been described above, the same applies to the duty upper limit DH. That is, for example, as shown in FIG. 21, when the target duty changes near the duty upper limit DH and moves up and down over the duty upper limit DH, the target duty is equal to or less than the duty upper limit DH, and the pulse signal Pd1 The state T1 in which the amplitude of the drive signal V1 is controlled by the duty of the period T1 and the state T3 in which the target duty exceeds the duty upper limit value DH and the amplitude of the drive signal V1 is controlled by the voltage supplied to the first drive circuit 723 frequently occur. Switch. As described above, when the states T1 and T3 are frequently switched, the amplitude control of the drive signal V1 is accurately performed, for example, the voltage supplied from the first voltage supply unit 725 to the first drive circuit 723 becomes unstable. May not be possible.

  Therefore, in the first PWM waveform generation unit 722 of the present embodiment, the duty upper limit value DH has hysteresis to suppress frequent switching between the states T1 and T3. Hereinafter, this will be described in detail. As shown in FIG. 22, the first PWM waveform generator 722 is provided with a first duty upper limit value DH1 and a second duty upper limit value DH2 which is smaller than the first duty upper limit value DH1. Then, after the target duty exceeds the first duty upper limit DH1 and the state is switched from the state T1 to the state T3, the states T1 and T3 are switched based on the second duty upper limit DH2. In other words, even if the target duty is equal to or less than the first duty upper limit DH1, if the target duty is not equal to or less than the second duty upper limit DH2, the state T3 is maintained. If the target duty becomes equal to or less than the second duty upper limit DH2, the state T3 To state T1. When the target duty becomes equal to or less than the second duty upper limit DH2 and the state is switched from the state T3 to the state T1, the states T1 and T3 are switched again based on the first duty upper limit DH1.

  In this way, by giving the hysteresis to the duty upper limit DH and setting the first duty upper limit DH1 for switching from the state T1 to the state T3 and the second duty upper limit DH2 for switching from the state T3 to the state T1, the state T1 is set. , T3 can be prevented from frequently switching. Therefore, the voltage supplied from the first voltage supply unit 725 to the first drive circuit 723 is stabilized, and the amplitude control of the drive signal V1 can be accurately performed.

  According to the third embodiment as described above, the same effects as in the first embodiment can be exhibited.

<Fourth embodiment>
FIG. 23 is a perspective view showing a robot according to the fourth embodiment of the present invention.

  The robot 1000 shown in FIG. 23 can perform operations such as feeding, removing, transporting, and assembling precision equipment and components constituting the same. The robot 1000 is a six-axis robot, and includes a base 1010 fixed to a floor or a ceiling, an arm 1020 rotatably connected to the base 1010, an arm 1030 rotatably connected to the arm 1020, and an arm 1030. Arm 1040 rotatably connected to arm 10, arm 1050 rotatably connected to arm 1040, arm 1060 rotatably connected to arm 1050, and arm 1060 rotatably connected to arm 1060. An arm 1070 and a control device 1080 for controlling the driving of the arms 1020, 1030, 1040, 1050, 1060, and 1070 are provided.

  Further, the arm 1070 is provided with a hand connection unit, and an end effector 1090 corresponding to a task to be executed by the robot 1000 is mounted on the hand connection unit. A piezoelectric motor 1 is mounted on all or a part of the joints, and the arms 1020, 1030, 1040, 1050, 1060, and 1070 are rotated by driving the piezoelectric motor 1. Note that the piezoelectric motor 1 may be mounted on the end effector 1090 and used for driving the end effector 1090.

  The control device 1080 is configured by a computer, and has, for example, a processor (CPU), a memory, an I / F (interface), and the like. Then, the processor controls the driving of each unit of the robot 1000 by executing a predetermined program (code sequence) stored in the memory. The program may be downloaded from an external server via an I / F. Further, all or a part of the configuration of the control device 1080 may be provided outside the robot 1000 and connected via a communication network such as a LAN (local area network).

  Such a robot 1000 includes the piezoelectric motor 1 as described above. That is, the robot 1000 includes the piezoelectric elements 6A to 6E that are driving piezoelectric elements, and the vibrating body 41 vibrates by applying the driving signals V1 to V3 to the piezoelectric elements 6A to 6E, and moves by the vibration of the vibrating body 41. And a voltage controller 70 that applies drive signals V1 to V3 to the piezoelectric elements 6A to 6E. Further, the voltage control unit 70 includes first, second, and third PWM waveforms as pulse signal generation units that generate pulse signals Pd1 to Pd3 based on the target duty included in the duty commands Md1 to Md3 that are input commands. First, second, and third drive circuits 723, 733, and 773 as drive signal generators that generate drive signals V1 to V3 based on pulse signals Pd1 to Pd3; , Second, and third drive circuits 723, 733, and 773 as first, second, and third voltage supply units 725, 735, and 775. In addition, the first, second, and third PWM waveform generation units 722, 732, and 772 generate pulse signals Pd1 to Pd3 having a duty lower limit DL and having a duty equal to or greater than the duty lower limit DL. Further, the first, second, and third voltage supply units 725, 735, and 775 provide the first, second, and third drive circuits 723 and 733 according to the difference ΔD between the target duty and the duty of the pulse signals Pd1 to Pd3. , 773 are changed. Therefore, the robot 1000 has excellent driving characteristics.

<Fifth embodiment>
FIG. 24 is a schematic diagram showing the overall configuration of the printer according to the fifth embodiment of the present invention.

  The printer 3000 illustrated in FIG. 24 includes an apparatus main body 3010, a printing mechanism 3020, a paper feeding mechanism 3030, and a control device 3040 provided inside the apparatus main body 3010. Further, the apparatus main body 3010 is provided with a tray 3011 on which the recording paper P is set, a discharge port 3012 for discharging the recording paper P, and an operation panel 3013 such as a liquid crystal display.

  The printing mechanism 3020 includes a head unit 3021, a carriage motor 3022, and a reciprocating mechanism 3023 that reciprocates the head unit 3021 by the driving force of the carriage motor 3022. The head unit 3021 includes a head 3021a that is an ink jet recording head, an ink cartridge 3021b that supplies ink to the head 3021a, and a carriage 3021c on which the head 3021a and the ink cartridge 3021b are mounted.

  The reciprocating mechanism 3023 has a carriage guide shaft 3023a that supports the carriage 3021c so as to be able to reciprocate, and a timing belt 3023b that moves the carriage 3021c on the carriage guide shaft 3023a by the driving force of the carriage motor 3022. The paper feed mechanism 3030 includes a driven roller 3031 and a driving roller 3032 that are in pressure contact with each other, and the piezoelectric motor 1 that drives the driving roller 3032.

  In such a printer 3000, the paper feed mechanism 3030 intermittently feeds the recording paper P one by one to the vicinity of the lower part of the head unit 3021. At this time, the head unit 3021 reciprocates in a direction substantially orthogonal to the feeding direction of the recording paper P, and printing on the recording paper P is performed.

  The control device 3040 is configured by a computer, and has, for example, a processor (CPU), a memory, an I / F (interface), and the like. Then, the processor controls the driving of each unit of the printer 3000 by executing a predetermined program (code sequence) stored in the memory. Such control is executed, for example, based on print data input from a host computer such as a personal computer via an I / F. The program may be downloaded from an external server via an I / F. Further, all or a part of the configuration of the control device 3040 may be provided outside the printer 3000 and connected via a communication network such as a LAN (local area network).

  Such a printer 3000 includes the piezoelectric motor 1 as described above. That is, the printer 3000 includes the piezoelectric elements 6A to 6E that are driving piezoelectric elements, and the vibrating body 41 vibrates by applying the driving signals V1 to V3 to the piezoelectric elements 6A to 6E, and moves due to the vibration of the vibrating body 41. And a voltage controller 70 that applies drive signals V1 to V3 to the piezoelectric elements 6A to 6E. Further, the voltage control unit 70 includes first, second, and third PWM waveforms as pulse signal generation units that generate pulse signals Pd1 to Pd3 based on the target duty included in the duty commands Md1 to Md3 that are input commands. First, second, and third drive circuits 723, 733, and 773 as drive signal generators that generate drive signals V1 to V3 based on pulse signals Pd1 to Pd3; , Second, and third drive circuits 723, 733, and 773 as first, second, and third voltage supply units 725, 735, and 775. In addition, the first, second, and third PWM waveform generation units 722, 732, and 772 generate pulse signals Pd1 to Pd3 having a duty lower limit DL and having a duty equal to or greater than the duty lower limit DL. Further, the first, second, and third voltage supply units 725, 735, and 775 provide the first, second, and third drive circuits 723 and 733 according to the difference ΔD between the target duty and the duty of the pulse signals Pd1 to Pd3. , 773 are changed. Therefore, the printer 3000 has excellent driving characteristics.

  In the present embodiment, the piezoelectric motor 1 drives the driving roller 3032 for feeding paper. However, for example, the carriage 3021c may be driven.

  As described above, the control method of the piezoelectric driving device, the piezoelectric driving device, the robot and the printer according to the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each unit is the same. Can be replaced with any configuration having the function of Further, other arbitrary components may be added to the present invention. Further, the embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Piezoelectric motor, 2 ... Rotor, 21 ... Outer peripheral surface, 22 ... Main surface, 3 ... Drive part, 4 ... Piezoelectric actuator, 41 ... Vibration body, 42 ... Support part, 43 ... Connection part, 431 ... First connection part , 432: second connecting portion, 44: convex portion, 5: urging member, 6A to 6G: piezoelectric element, 60: piezoelectric element unit, 60A to 60G: piezoelectric element, 601: first electrode, 602: piezoelectric body, 603: second electrode, 61: substrate, 63: protective layer, 69: adhesive, 7: control device, 70: voltage controller, 71: first voltage controller, 711: position command controller, 712: position control Unit, 713: speed control unit, 72: first drive signal generation unit, 721: first drive voltage control unit, 722: first PWM waveform generation unit, 723: first drive circuit, 723a: switching element, 723b: switching element , 723c ... LC resonance 724: first voltage command control unit, 725: first voltage supply unit, 725a: power supply, 725b: DC / DC converter, 73: second drive signal generation unit, 731: second drive voltage control unit, 732 ... 2nd PWM waveform generation section, 733: second drive circuit, 734: second voltage command control section, 735: second voltage supply section, 77: third drive signal generation section, 771: third drive voltage control section, 772 ... Third PWM waveform generation unit, 773: third drive circuit, 774: third voltage command control unit, 775: third voltage supply unit, 78: second voltage control unit, 781: PU voltage control unit, 79: frequency control unit , 9 ... Encoder, 91 ... Scale, 92 ... Optical element, 921 ... Light emitting element, 922 ... Imaging element, 1000 ... Robot, 1010 ... Base, 1020-1070 ... Arm, 1080 ... Control device, 10 0: End effector, 3000: Printer, 3010: Device body, 3011: Tray, 3012: Discharge port, 3013: Operation panel, 3020: Printing mechanism, 3021: Head unit, 3021a: Head, 3021b: Ink cartridge, 3021c ... Carriage, 3022 Carriage motor, 3023 Reciprocating mechanism, 3023a Carriage guide shaft, 3023b Timing belt, 3030 Paper feed mechanism, 3031 Driven roller, 3032 Drive roller, 3040 Control device, A1, A2, B1 , B2: Arrow, C: Capacitor, DH: Duty upper limit, DH1: First duty upper limit, DH2: Second duty upper limit, DL: Duty lower limit, DL1: First duty lower limit, DL2: Second duty lower limit, L ... coils, Ma ... Position command, Mb ... Speed command, Mc ... Voltage command, Md1-Md3 ... Duty command, Me1-Me3 ... Supply voltage command, Mf ... Voltage command, Mg ... Frequency command, O ... Center axis, P ... Recording paper, Pd1 Pd3: pulse signal, SH: voltage threshold, T1 to T3: state, V ': reference voltage, V ": voltage, V1 to V3: drive signal, VDD: power supply voltage, Vpu: pickup voltage

Claims (10)

A vibrating body that includes a driving piezoelectric element and vibrates by applying a driving signal to the driving piezoelectric element;
A driven part that is moved by the vibration of the vibrating body,
A drive signal generation unit that generates a pulse signal based on the target duty, and generates a drive signal based on the pulse signal, comprising:
A method of controlling a piezoelectric driving device, comprising: changing a magnitude of a voltage to be supplied to the drive signal generation unit according to a difference between the target duty and a duty of the pulse signal.   2. The pulse signal having a duty equal to the duty lower limit when the target duty is less than a duty lower limit previously set, and the voltage supplied to the drive signal generator is reduced. 3. A method for controlling a piezoelectric driving device.   3. The pulse signal according to claim 2, wherein when the target duty is greater than a duty upper limit that has been set in advance, the pulse signal having the duty equal to the duty upper limit is generated, and a voltage supplied to the drive signal generator is increased. A method for controlling a piezoelectric driving device. A vibrating body that includes a driving piezoelectric element and vibrates by applying a driving signal to the driving piezoelectric element;
A driven part that is moved by the vibration of the vibrating body,
A voltage control unit that applies a driving voltage to the driving piezoelectric element,
A voltage signal generator configured to generate a pulse signal based on a target duty included in the input command;
A drive signal generation unit that generates the drive signal based on the pulse signal;
A voltage supply unit that supplies a voltage to the drive signal generation unit,
The pulse signal generation unit stores a duty lower limit value, and generates the pulse signal having a duty equal to or greater than the duty lower limit value,
The piezoelectric drive device according to claim 1, wherein the voltage supply unit changes a magnitude of a voltage supplied to the drive signal generation unit according to a difference between the target duty and a duty of the pulse signal. When the target duty is less than the duty lower limit,
The pulse signal generation unit generates the pulse signal having a Duty equal to the Duty lower limit,
The piezoelectric drive device according to claim 4, wherein the voltage supply unit reduces a voltage supplied to the drive signal generation unit. When the target Duty is larger than the Duty upper limit value which has in advance,
The pulse signal generation unit generates the pulse signal having a Duty equal to the Duty upper limit,
The piezoelectric drive device according to claim 4, wherein the voltage supply unit increases a voltage supplied to the drive signal generation unit. A protrusion connected to the vibrator and in contact with the driven part;
When the direction in which the vibrating body and the convex portion are arranged is the first direction, by changing the magnitude of the voltage supplied to the drive signal generation unit, the bending vibration is performed in the second direction orthogonal to the first direction. The piezoelectric drive device according to claim 4, wherein the magnitude of the generated vibration is changed.   The piezoelectric drive device according to claim 7, wherein the magnitude of the vibration that expands and contracts in the first direction is changed by changing the magnitude of the voltage supplied to the drive signal generation unit. A vibrating body that includes a driving piezoelectric element and vibrates by applying a driving signal to the driving piezoelectric element;
A driven part that is moved by the vibration of the vibrating body,
A voltage control unit that applies a driving voltage to the driving piezoelectric element,
A voltage signal generator configured to generate a pulse signal based on a target duty included in the input command;
A drive signal generation unit that generates the drive signal based on the pulse signal;
A voltage supply unit that supplies a voltage to the drive signal generation unit,
The pulse signal generation unit has a duty lower limit, and generates the pulse signal having a duty equal to or greater than the duty lower limit,
The voltage supply unit changes a magnitude of a voltage supplied to the drive signal generation unit according to a difference between the target duty and a duty of the pulse signal. A vibrating body that includes a driving piezoelectric element and vibrates by applying a driving signal to the driving piezoelectric element;
A driven part that is moved by the vibration of the vibrating body,
A voltage control unit that applies a drive voltage to the driving piezoelectric element,
A voltage signal generator configured to generate a pulse signal based on a target duty included in the input command;
A drive signal generation unit that generates the drive signal based on the pulse signal;
A voltage supply unit that supplies a voltage to the drive signal generation unit,
The pulse signal generation unit has a duty lower limit, and generates the pulse signal having a duty equal to or greater than the duty lower limit,
The printer, wherein the voltage supply unit changes the magnitude of a voltage supplied to the drive signal generation unit according to a difference between the target duty and the duty of the pulse signal.

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