WO1999063653A1 - Technique de detection de position et appareil correspondant, moteur a ultrasons et technique de commande de ce moteur - Google Patents

Technique de detection de position et appareil correspondant, moteur a ultrasons et technique de commande de ce moteur Download PDF

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Publication number
WO1999063653A1
WO1999063653A1 PCT/JP1999/002851 JP9902851W WO9963653A1 WO 1999063653 A1 WO1999063653 A1 WO 1999063653A1 JP 9902851 W JP9902851 W JP 9902851W WO 9963653 A1 WO9963653 A1 WO 9963653A1
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WIPO (PCT)
Prior art keywords
vibration
signal
members
wave
phase
Prior art date
Application number
PCT/JP1999/002851
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English (en)
Japanese (ja)
Inventor
Yoshiyo Wada
Makoto Masuda
Original Assignee
Star Micronics Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP10149586A external-priority patent/JPH11341844A/ja
Priority claimed from JP10246260A external-priority patent/JP2000078864A/ja
Priority claimed from JP10246269A external-priority patent/JP2000078865A/ja
Application filed by Star Micronics Co., Ltd. filed Critical Star Micronics Co., Ltd.
Publication of WO1999063653A1 publication Critical patent/WO1999063653A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
    • H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
    • H02N2/14—Drive circuits; Control arrangements or methods
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
    • H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
    • H02N2/16—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors using travelling waves, i.e. Rayleigh surface waves
    • H02N2/163—Motors with ring stator

Definitions

  • Position detecting device position detecting method, ultrasonic motor and ultrasonic motor driving method
  • the present invention relates to a position detecting device, a position detecting method, an ultrasonic motor, and a driving method of an ultrasonic motor.
  • a resistance division type low encoder As a conventional position detection device, a resistance division type low encoder is known.
  • the resistance-divided rotary encoder is provided with a resistor on one of two circular members arranged coaxially, and a brush on the other, in contact with the resistor.
  • the resistance division ratio of the resistor by the brush changes according to the rotation angle of the member. By measuring the voltage between both ends of the divided resistance area, one member rotates. The angle can be determined.
  • the optical rotary encoder includes a plurality of slits provided on one member to which light from a light source is irradiated, and a photodetector arranged at a position sandwiching the illuminated area of the slit with the light source.
  • the rotation angle of the slit member with respect to the member provided with the photodetector can be obtained by counting the number of pulse output signals from the photodetector.
  • a conventional ultrasonic motor includes a stator and a moving member which are arranged to face each other in a pressure contact state.
  • a motor is known in which a drive signal is supplied only to the stator and ultrasonically vibrated, and the mover rotates in response to the vibration. More specifically, a traveling wave is generated on the stator surface by the supply of the driving signal, and the moving element is rotated by the frictional force between the traveling wave of the stator and the moving element. Disclosure of the invention
  • the inventor of the present application has provided a vibrator for each of the moving element and the stator, and when both of the vibrating elements are vibrated by applying a drive signal to the vibrating element, the moving element and the stator are both disposed on the opposing surfaces.
  • An ultrasonic motor that generates ultrasonic vibrations and moves the moving element in accordance with the vibrations was devised.
  • vibration waves are generated by ultrasonic waves on the moving member and the stator and on the opposing surfaces thereof, and when these are pressed into contact with each other, the vibration waveforms are combined to form the moving member and the stationary member.
  • the relative movement between the children is regulated.
  • the movable member moves relative to the stator.
  • the valleys of the vibration waveform of the moving element that should match with the peak of the vibration waveform of the stator are not always located.
  • the moving element moves so that they match. Moving or slipping occurs, resulting in loss of driving force.
  • the relative positions of the two are unknown and are often out of alignment.
  • the mover moves so that the valley of the mover meets the peak of the stator.
  • the position regulating force due to the coupling between the vibration waveforms in other words, the combined force of the frictional force and the biasing force between the stator and the mover mainly based on the vibration amplitude, for example, the driving force that exceeds this during high-speed rotation Is added, the position of the peak of the vibration waveform of the stator and the position of the valley of the vibration waveform of the movable element are displaced by slippage.
  • This position detection device is composed of a part of the ultrasonic motor. That is, it functions as a position detection device that detects the relative position between the stator and the moving element by detecting the other vibration of the vibrator when only one of the vibrators in the ultrasonic motor is actively vibrated. Let it. In addition, it is preferable to adjust the phase difference of the vibration between the vibrators so that the vibration waveforms of the vibrators when both vibrators are actively vibrated according to the detected value.
  • both the stator and the mover that are opposed to each other are vibrated in the pressed state, and the mover moves in response to the vibration. In this case, the driving force of the mover is increased.
  • the relative position between the stator and the moving element is detected by detecting the other vibration of the vibrator when only one of the vibrators is actively vibrated. For example, if the oscillator on the stator side is one of the above, the stator (moving wave or standing wave) is transmitted to the moving element because the stator and the moving element are opposed to each other in a pressed state. Also, the vibration (traveling wave or standing wave) having substantially the same phase is generated in the mover. Since the vibration of the vibrator on the stator side is actively generated, the position of the vibration wave can be specified from the coordinate system of the stator.
  • the position of the vibration wave viewed from the coordinate system of the moving element is determined by, for example, providing a means for outputting a different signal to the moving element according to the position of the vibration wave.
  • it can be specified. That is, the position of the vibration wave viewed from the coordinate system of the stator is specified, and the position of the vibration wave viewed from the coordinate system of the stator can also be specified.
  • the relative position between the stator and the mover is the relative position in these coordinate systems.
  • the respective vibration waves have substantially the same phase, that is, since the vibration wave positions are the same, the relative rotational position between the coordinate systems can be obtained.
  • the oscillator on the moving element side may be one of the above.
  • the step of adjusting the phase difference of the vibration between the vibrators so that the vibration waveforms of the vibrators when both vibrators are actively vibrated according to the detected value is combined.
  • the displacement between the vibration waveforms of the stator and the movable element can be suppressed.
  • the accuracy of the relative position detection value deteriorates. Therefore, in the driving method of the ultrasonic motor according to the present invention, the step of stopping the other vibration of the vibrator when only one of the vibrators is actively vibrated, even if the time is short. It is desirable to further provide.
  • the position detecting device includes two members disposed so as to be able to transmit the vibration from one side to the other, and a standing wave along the position detecting direction.
  • Vibration means for vibrating one of the members so as to generate detection means for outputting a signal corresponding to the other vibration of the member, and comparison means for comparing the output signal with a predetermined reference signal.
  • the predetermined reference signal is preferably a drive signal for vibrating the vibrating means, but may be, for example, an output signal of a quartz crystal which is an oscillation source for generating the drive signal.
  • the ultrasonic motor having such a position detecting function supplies a driving signal so that a traveling wave is generated on at least one of the opposed surfaces of the stator and the movable member which are arranged opposite to each other in a press-contact state, and vibrates.
  • a drive signal is supplied to both the stator and the mover, vibration waves from both the stator and the mover are combined, so that the driving force can be increased.
  • Vibration can be generated using a mechanical vibration mechanism, and vibration can be generated using an electromagnetic vibration mechanism such as a speaker, but industrial use is relatively easy.
  • the step of vibrating one of the members includes a step of applying a drive signal to a piezoelectric vibrator provided on one of the members, and the step of detecting detects the output signal and the drive signal from the piezoelectric element provided on the other of the members. It is preferable to include a step of comparing. In this case, when a drive signal is applied to a piezoelectric vibrator provided on one of the members, the piezoelectric vibrator vibrates, so that one member vibrates.
  • the moving element of the ultrasonic motor functions as a slider when performing linear motion, and functions as a mouth when performing rotary motion.
  • various methods can be considered for generating the above-mentioned vibration, and it is possible to generate vibration using a mechanical vibration mechanism, and to generate vibration using an electromagnetic vibration mechanism such as a speaker. Is also possible.
  • the stopping step is performed at least once each time the movable element moves by one wavelength.
  • FIG. 1 is a configuration diagram showing a position detecting device (ultrasonic wave) according to an embodiment.
  • FIG. 2 is a longitudinal sectional view of the position detecting device main body (ultrasonic motor main body) 1 in which the position detecting device main body (ultrasonic motor main body) 1 is cut by a plane passing through the axis center thereof.
  • FIG. 3 is a partially exploded perspective view showing a main part of the position detecting device main body (ultrasonic motor main body) 1.
  • Fig. 4 is a plan view of the station 5 when five wavelengths of standing waves (indicated by two-dot chain lines) are generated.
  • FIG. 5 is an evening timing chart of two-phase drive signals Vs and Vc having a 90 ° phase difference.
  • 9 is a graph showing a combined displacement D of displacements D s and D c at 8 T / 8.
  • Fig. 9A is a development view showing the stage side oscillator 5 V in an expanded state.
  • Fig. 9B is the oscillator 5 V when a sin wave is applied only to the sin side electrode groups S1 to S4 (SS).
  • Fig. 9C is a graph showing the circumferential position and displacement of the transducer 5V when cos waves are applied only to the cos-side electrode groups C1 to C4 (CC).
  • FIG. 9D is a developed view showing the rotor side piezoelectric element 6 V in an expanded manner.
  • FIG. 10A is a graph showing drive signals Vs, Vc
  • FIG. 10B is a feedback signal Vfbs
  • FIG. 10C is a graph showing piezoelectric voltage signals for detection Vs ′, Vc ′, Vfbs.
  • FIG. 11 is a graph showing the phase relationship of vibration in the same format as in FIG.
  • FIG. 12 is a system configuration diagram showing a system configuration of the position detecting device.
  • FIG. 13 is a system configuration diagram showing a system configuration of another position detecting device.
  • FIG. 14 is a system configuration diagram showing a system configuration of still another position detection device.
  • FIG. 15 is a graph showing the relationship between the relative rotational position of the position detecting device shown in FIG. 14 and the phase difference ⁇ .
  • FIG. 16 is a system configuration diagram showing a system configuration of an ultrasonic motor including the position detection device shown in FIG.
  • FIG. 17 is a cross-sectional view taken along the circumferential direction of the contact portion between the stay and the mouth when the rotational displacement wave is babbling.
  • FIG. 18 is a system configuration diagram showing a system configuration in the control device 2.
  • FIG. 19 is a circuit diagram showing an example of a specific circuit of the phase shift circuit 2c "and the mixer circuit MX.
  • FIG. 20 is a system configuration diagram of a displacement lock drive type ultrasonic motor equipped with the position detecting device shown in FIG.
  • FIG. 21 is a plan view of a vibrator according to a modification.
  • FIG. 22 is an explanatory diagram showing a relative positional relationship between the mouth and the stay.
  • FIG. 23 is a diagram for explaining the relationship between the relative position and the synthesized signal.
  • FIG. 24 is a system configuration diagram of a control device 2 according to another embodiment. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 is a configuration diagram showing a position detection device according to the present embodiment.
  • the position detection device detects the position between the stay 5 and the mouth 6 by applying a drive signal for detecting the rotational position, and detects the rotation of the mouth 6 by applying the drive signal for the rotation. Also functions as a sound wave.
  • This position detecting device is composed of a position detecting device main body 1 composed of a mechanical drive mechanism, and a control device 2 for controlling the driving of the position detecting device main body 1.
  • the position detecting device main body 1 includes a cylindrical housing 3S that forms a side wall, circular lid members 3U and 3L that hermetically seal the upper and lower openings of the nozzle 3S, and lid members 3U and 3L. And a rotation shaft 4 penetrating through the central openings of both sides, and is driven and controlled by the controller 2.
  • FIG. 2 is a longitudinal sectional view (I-I arrow sectional view) of the position detecting device main body 1 taken along a plane passing through the center of the axis thereof.
  • One night 6 is opposed to the rotation axis 4 so as to be coaxial.
  • the stay 5 is fixed to the lower lid member 3L by bolts B inserted from the outer surface side of the lower lid member 3 so as to be immovable with respect to the housing 3S.
  • the rotating shaft 4 is fixed to an inner race of a ball bearing 9 U, 9 L in which an outer race is fixed to an inner surface of a central opening of the lid member 3 U, 3 L, and a ball bearing 9 U, 9 L Is rotatably supported by the housing 3S.
  • the rotor 6 is fixed to a rotary shaft 4 rotatable with respect to the housing 3S via a substantially annular base 7 and a counter panel 8 so as to be rotatable with respect to the housing 3S. Therefore, when the rotating shaft 4 is rotated relative to the housing 3S, the mouth 6 fixed thereto is rotated relative to the stay 5.
  • the position detection device uses ultrasonic vibration for position detection.
  • the stay 5 is vibrated, and the vibration and the vibration generated by the rotor 6 due to the transmission of the vibration are detected.
  • Compare and detect relative position When the vibration of the stay 5 is transmitted to the mouth 6, the mouth 6 also vibrates. By comparing the respective vibrations, it is possible to detect the relative position between the stay 5 and the mouth 6.
  • the vibration of the stay 5 is transmitted to the rotor 6, and the rotor 6 also generates substantially the same phase vibration. Since the vibration of Station 5 is actively generated, the relative position of the vibration wave with respect to the position of Station 5 can be specified. Although the vibration of the rotor 6 is generated passively, the relative position of the rotor 6 with respect to the vibration wave of the rotor 6 is, for example, a means for outputting a different signal according to the position of the vibration wave is provided at the mouth 6. It can be specified by using such a method. The vibration of stay 5 and rotor 6 are almost the same. It is a phase, and therefore, since the stay 5 is fixed, the relative position with respect to the rotor 6 can be obtained. In other words, by comparing the vibration waves / position relations of the station 5 and the station 6 taking into account the condition that the vibration waves are substantially in phase, the station 5 and the station 6 are compared. Can be determined. This position detection is performed by the control device 2.
  • the stay 5 vibrates the metal elastic body 5e by the piezoelectric vibrator 5v. That is, the stay 5 includes an annular vibrator 5 V made of a ceramic piezoelectric element and an annular elastic body 5 e made of a metal with the vibrator 5 V adhered to the outer periphery of the back surface. .
  • a thin annular intermediate part 5 m is located between the outer peripheral part 5 o of the elastic body which is a direct vibration part and the inner peripheral part 5 i, and the intermediate part 5 m vibrates the outer peripheral part 5 o. This facilitates the vibration and suppresses the transmission of vibration between the inner peripheral portion 5i and the outer peripheral portion 5o. Since the thick inner peripheral portion 5i of the elastic body 5e is located far from the main vibration part of the elastic body, this is fixed to the lower lid member 3L with the bolt B, and the elastic body 5e is attached to the housing. To be immobile.
  • the mouth 6 has the same structure as the stay 5 and has an annular piezoelectric element 6 V composed of a ceramic piezoelectric element and a circle composed of a metal having the piezoelectric element 6 V adhered to the outer periphery of the upper surface. It has an annular elastic body 6e.
  • the thick inner peripheral portion 6i of the elastic body 6e is fixed to the rotating shaft 4 as described above, and the elastic body 6e is formed between the outer peripheral portion 60 and the inner peripheral portion 6i in an annular thin intermediate portion. It has 6m.
  • the pedestal 7 fixed to the rotor 6 is rotated by a disc spring 8 whose inner edge is fixed to the rotating shaft 4 so that the rotational displacement wave of the stay 5 is efficiently transmitted to the mouth 6. It is urged to the side, and the opposing surface of the mouth 6 is pressed against the opposing surface of the stay 5.
  • the stay side elastic body 5e has a narrow annular convex portion 5p on the upper surface of the outer peripheral portion 5o so as to suppress the interference of vibration between the stay portion 5 and the row portion 6,
  • the evening side elastic body 6e has a narrow annular convex portion 6p on the outer peripheral portion 6o on the back surface.
  • the friction buffering member 10 is an annular sheet made of a resin material or the like, and prevents mutual interference between the convex portions 5p and 6p to normally generate a rotational displacement wave in both of them, and a metal-to-metal connection. Direct contact is avoided to prevent generation of abnormal noise, and furthermore, the durability of these press-contact portions 5p and 6p is improved.
  • a space with a thickness of several mm is formed between the inner circumference 5i and the middle 5m of the stay and the inner circumference 6i and the middle 6m of the rotor.
  • a signal extraction mechanism 11 for extracting a signal from the element 6 V is arranged.
  • the signal extraction mechanism 11 may be one that uses a single-ended transformer or the like, but here it is assumed that a brush and a slip ring are used for simplicity.
  • the signal extraction mechanism 11 includes brushes 11 a, 1 lb, and 11 c, each of which is formed by bending a part of three annular conductive rings concentrically arranged on the rotating shaft 4 toward the rotor 5.
  • Slip rings 11A, 11B, 11C concentrically arranged on the rotating shaft 4 so that the tips of the brushes 11a, lib, and 11c contact each other.
  • the base ends of the brushes 11a, lib, 11c are fixed to the stay 5 and the slip rings 11A, 11B, 11C are fixed to the rotor 6. Therefore, even when the mouth 6 is rotated, the tips of the brushes lla, 11b, 11c and the slip rings 11A, 1IB, 11C are always in contact with each other.
  • the vibrator 5 V connected to the conductive wire is configured such that a rotational displacement wave is formed on the surface facing the elastic body 5 e by applying a two-phase drive signal, preferably a sinusoidal signal and a cos wave signal.
  • the piezoelectric element 6 V is configured to output a two-phase detection signal via a conductive wire by transmitting the rotational displacement wave of the vibrator 5 V.
  • the oscillator 5v, the piezoelectric element 6V, and the elastic bodies 5e and 6e will be described in detail.
  • FIG. 3 is a partially exploded perspective view showing a main part of the position detecting device main body 1.
  • the ring-shaped stay-side vibrator 5 V is composed of a ring-shaped piezoelectric ceramic plate CM and four first electrode groups S 1 to S 4 formed on one surface of the piezoelectric ceramic plate CM.
  • the first electrode group S1 to S34 and the second electrode group ⁇ 1 to C4 are arranged so that the oscillator 5V can generate five standing waves in the entire circumferential direction by applying a sine wave signal to each of them. In addition, they are arranged every 36 ° (person / 2) in mechanical angle.
  • the feedback electrode FB is located between the electrode S 1 of the first electrode group and the electrode C 1 of the second electrode group, has a circumferential length of 18 ° (person / 4) in mechanical angle, and has a ceramic plate. This part of the CM is polarized in the thickness direction.
  • the electrode S4 of the first electrode group and the electrode C4 of the second electrode group are separated by 54 ° (3 persons / 4) in mechanical angle.
  • the first electrode group S1 to S4 and the second electrode group C1 to C4 of the ceramic plate CM are polarized such that the polarization directions in the thickness direction are opposite to each other in the adjacent regions (see + _ in the drawing). Is being processed.
  • an electrode SS facing the entire formation region of the first electrode groups S1 to S4 on one surface of the piezoelectric ceramic plate CM, and a second electrode group C1 to C2.
  • the electrode CC facing the entire formation area of C4 and the feedback electrode FB Opposing feedback electrodes FB, are formed.
  • the structure of the piezoelectric element 6 V on the mouth side is the same as the structure of the transducer 5 V on the stay side, and therefore, the description is omitted here.
  • the vibrator 5 V and the piezoelectric element 6 V each have one surface, that is, a surface on which the first electrode groups S 1 to S 4, the second electrode groups C 1 to C 4, and the feedback electrode FB are formed.
  • the elastic body 5e, 6e is adhered to the elastic body 5e, 6e via a conductive adhesive or an insulating adhesive with a thickness capable of making electrical contact so as to contact the surface opposite to the opposing surface of 5e, 6e. You. Therefore, the ultrasonic vibration, which is the rotational displacement wave of the transducer 5 V, is directly transmitted to the elastic body 5 e, and the ultrasonic vibration, which is the rotational displacement wave of the elastic body 6 e generated by the transmission, is directly transmitted to the piezoelectric element 6 V. Is transmitted.
  • the elastic members 5 e and 6 e are connected to the ground, so that the first electrode groups S 1 to S 4, the second electrode groups C 1 to C 4, and the feedback electrode FB are e, 6 e are connected to ground.
  • Two-phase drive signals having a 90 ° phase difference are applied to the electrode S S and the electrode C C on the side of the stay 5 so that the vibrator 5 V generates a rotational displacement wave.
  • the driving signal described above is supplied from the control device 2 to the electrode SS and the electrode CC of the stay side vibrator 5 V, and the vibrator 5 V vibrates according to the supply.
  • the piezoelectric voltage which is a feedback signal output from the feedback electrode FB 'in response to this vibration
  • the signal is input to the control device 2.
  • the control device 2 changes the oscillation frequency based on the input feedback signal so that the phase difference between this signal and a reference signal generated in the control device 2 becomes constant. Controls the drive signal supplied to the transducer 5 V.
  • Figure 4 shows the station 5 or mouth-night 6 when a standing wave of five wavelengths (indicated by the two-dot chain line) is generated.
  • the standing wave indicated by the two-dot chain line indicates the amplitude in the radial direction.
  • the circumferential amplitude generated by the first electrode groups S1 to S4 is shown in the radial direction.
  • the arc part swelling outside the circumference indicated by the two-dot chain line indicates an upward bulge (mountain), and the arc part entering the circumference indicates a subsidence (valley) downward.
  • the traveling wave as a rotational displacement wave is generated by the superposition of two standing waves generated by the application of each of the two-phase drive signals having a 90 ° phase difference.o
  • FIG. 5 is a timing chart of the two-phase drive signals Vs and Vc having a 90 ° phase difference.
  • the horizontal axis represents time t, and the vertical axis represents the signal level V.
  • the sine wave is denoted by Vs
  • the c0s wave is denoted by Vc.
  • the drive signals Vs and Vc are given by the following (Equation 1).
  • Vs s i ⁇ t
  • 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H, and 6I are the time t2 0 T / 8, 2 T / 8, 3 ⁇ / of the drive signals Vs and Vc.
  • Circumferential position on the electrodes SI and S2 of the transducer 5 ⁇ generated at 8, 4 ⁇ / 8, 5 ⁇ / 8, 6 ⁇ / 8, 7 ⁇ / 8, 8T / 8 (/ 8 is the period).
  • Wave length / 2 (phase 7 ⁇ ). Therefore, assuming that the maximum amplitude of the displacement in the thickness direction is ⁇ , the displacements in the thickness direction at position X, D s (x) and D c (x), are approximately as follows when the vibration waveform is a sine wave as shown in the figure. Given by (Equation 2).
  • D (X) K-[s i n0 ( ⁇ ) ⁇ s i nwt—cos ⁇ ( ⁇ ) ⁇ c ⁇ s ⁇ t]
  • the drive signal is composed of two-phase drive signals Vs and Vc having a phase difference of 90 degrees.
  • the two-phase drive signals Vs and Vc are applied to at least the electrodes S 1 (SS) and C 1 (CC) of the piezoelectric vibrator arranged at a distance of 1/4 wavelength of the vibration generated in the piezoelectric vibrator 5 V Is done.
  • the piezoelectric element 6v includes a piezoelectric material CM and at least two electrode pairs S 1 / SS and S 2 / SS sandwiching at least two regions in which the polarization directions of the piezoelectric material CM are different from each other so as to output an output signal.
  • the displacement Ds at 8, 6, T / 8, 7T / 8, and 8T / 8 is plotted on the horizontal axis (shown by the solid line), and the displacement Dc having a phase difference of 7 ⁇ / 2 is plotted on the vertical axis (shown by the dotted line).
  • the resultant displacement D exhibits a so-called circular motion trajectory having the same displacement amount and a different phase only, and a traveling wave as a rotational displacement wave is generated on the opposing surface of the stay 5.
  • the piezoelectric element 6 V is distorted in response to the vibration, and the piezoelectric voltage signal generated by the piezoelectric effect due to the distortion is, as shown in FIGS. And the brush lla, 11b, and input to the control device 2.
  • the piezoelectric voltage signal for detection output from the electrode FB on the rotor 6 side in response to this vibration is input to the control device 2 via the brush 11c.
  • This piezoelectric voltage signal can be used for maintaining the frequency difference and the phase difference of the vibration in the same manner as described above.
  • the piezoelectric element When a voltage of a certain magnitude is applied to the piezoelectric element, the piezoelectric element is distorted, but when the piezoelectric element is distorted similarly, a voltage of the same magnitude is output.
  • a rotational displacement wave is generated in the vibrator 5 V
  • the elastic body 5 e is distorted as described above and a rotational displacement wave is generated on the surface, but the rotational displacement wave is transmitted to the opposing elastic body 6 e.
  • the elastic body 6e is distorted in accordance with the distortion of the rotational displacement wave.
  • the piezoelectric elements 5v and 6v are facing upside down, so a positive voltage is applied to this part of the piezoelectric element 5V while a similar part is kept facing.
  • FIGS. 9A, 9B, 9C, and 9D are diagrams for explaining the principle of detecting the relative position from the piezoelectric voltage signal.
  • Fig. 9A is a developed view showing the stage-side vibrator 5 V in a developed state
  • Fig. 9B is the vibration when a sinusoidal wave is applied only to the sinusoidal electrode groups S1 to S4 (SS).
  • Fig. 9C shows the circumferential position of the transducer 5 V when the c0s wave is applied only to the cos-side electrode groups C1 to C4 (CC). It is a graph which shows displacement. Note that the solid lines in FIGS.
  • FIG. 9B and 9C indicate the displacement generated by the vibration of the part to be actually excited, and the dotted lines indicate the displacement generated by the propagation of the vibration.
  • FIG. FIG. 5 is a developed view showing the developed piezoelectric element 6 V in the case.
  • the rotational displacement wave formed by the displacement D and (X) of the piezoelectric element 6 V given by (Equation 4) is a traveling wave. Therefore, this traveling wave applies a standing wave generated by applying a sine wave of a predetermined phase to the electrode groups S1 to S4 of the piezoelectric element 6V and a cos wave of a predetermined phase to the electrode groups C1 to C4. This is the same as the wave generated by superimposing the standing wave generated by the operation.
  • the electrode groups S 1 to S 4 and C 1 to C 4 respectively generate a sine wave of a predetermined phase according to the distortion according to the displacement D and (X) of the piezoelectric element 6 V.
  • a detection piezoelectric voltage signal and a sine wave detection piezoelectric voltage signal having a phase difference of 90 ° from the detection piezoelectric voltage signal are output.
  • Displacements Ds ( ⁇ ) ′ and D c ( ⁇ ) ′ of the piezoelectric element 6 V due to the standing wave are given by the following (Equation 5).
  • D s (x), — K sin (2 ⁇ / ⁇ )-si ⁇ t
  • V s, sin ( ⁇ t + ⁇ ) was applied to the electrodes C 1 to C 4 of the mouth side piezoelectric element 6 v
  • Vc, cos (wt + ⁇ ) was applied to the electrodes S 1 to S 4
  • the displacements D s ( ⁇ ) ′ and D c (X) ′ in the case are given by (Equation 7) below.
  • FIG. 10A is a graph showing the drive signals Vs and Vc in this case
  • FIG. 10B is a graph showing the feedback signal Vfbs
  • FIG. 10C is a graph showing the piezoelectric voltage signals for detection Vs ′, Vc ′ and Vfbs ′.
  • the detection piezoelectric voltage signals Vs', Vc ', and Vf bs' correspond to the electrode CC (C1 to C4), electrode SS (S1 to S4), and electrodes FB and (FB) of the piezoelectric element 6 V, respectively.
  • phase difference ⁇ occurs between the drive signal and the detection piezoelectric voltage signal depending on the relative position between the stay 5 and the mouth 6. Therefore, by measuring this phase difference ⁇ , the relative position within one oscillation wavelength between the stay 5 and the rotor 6 can be obtained.
  • FIG. 11 is a graph showing the phase relationship of vibration in the same format as in FIG.
  • the displacements of the electrode groups S 1 to 34 on the stay side and the electrode groups ⁇ 1 to C 4 have a phase difference of human / 4, and the polarities are the polarities of the vector S v and the vector C v in the figure. Therefore, by applying the drive signals V s and V c as shown in Fig. 5, the displacement peak point draws a circular motion trajectory as shown by the arrow P. As shown in Fig. 9B and Fig.
  • the layout relationship of the feedback electrode FB of the feedback electrode FB on the 5th side to the electrode groups S1 to S4 and the electrode groups C1 to C4 is Taking the central axis, the vector Fv of the displacement position of the feedback electrode FB is advanced by 22 ° with respect to the vector Sv and is delayed by 45 ° with respect to the vector Cv. Assuming that the mouth 6 is displaced by 1/2 with respect to the stay 6, the displacement position vector F v ′ of the mouth-side feedback electrode FB is 180 ° with respect to the vector F v. Running late.
  • the displacements of the electrode groups C1 to C4 on the mouth side and the electrode groups S1 to S4 have a phase difference of / 4, and the displacement of the vectors Sv and Cv in the figure Polarity.
  • the relative position within one oscillation wavelength between the stay 5 and the rotor 6 can be obtained from the phase difference ⁇ between the drive signal and the piezoelectric voltage signal for detection.
  • FIG. 12 is a system configuration diagram showing a system configuration of the position detection device.
  • the arrows between the piezoelectric elements 5 v and 6 V indicate that the piezoelectric elements 5 v and 6 V can change their arrangement positions with respect to each other.
  • the drive signal V s is obtained by amplifying the clock pulse signal output from the oscillation circuit 2 a by the amplification circuit 2 b.
  • the driving signal Vc is generated by shifting the phase of the clock pulse signal by 90 degrees by the phase shift circuit 2c and amplifying the shifted signal by the amplifier circuit 2d.
  • the amplifier circuits 2b and 2d also have a function of blocking high-frequency components.
  • the feedback signal from the feedback electrode FB ' is fed back to the oscillation circuit 2a, which preferably includes a voltage-controlled oscillator, and is controlled so that the output frequency of the oscillation circuit 2a matches the resonance frequency of the step 5.
  • the rotational displacement wave generated on the surface of the stationary oscillator 5 V is transmitted to the mouth-side piezoelectric element 6 V.
  • V c ' cos ( ⁇ t + ⁇ )
  • V fbs' 2 sin ( ⁇ + ⁇ + 7 ⁇ / 4) is output.
  • the waveform shaping circuits 2 e, 2 f, 2 g composed of limiter circuits or comparators convert the detection piezoelectric voltage signals Vs ′, Vc ′, Vf bs ′ into square waves and output them.
  • phase of each converted square wave is compared with the drive signal in the state of the square wave by the phase detection circuits 2h, 2i, 2j, and the phase difference from the phase detection circuits 2h, 2i, 2j is obtained.
  • a voltage signal corresponding to ⁇ , that is, the relative position is output.
  • the phase difference ⁇ can be obtained from the outputs Vs, Vc, and Vf bs 'from any of the electrodes CC, SS, and FB' on the mouth and the mouth. Since the order of signal shift changes, the direction of rotation can be specified by processing these three signals.
  • the arithmetic circuit 2k receives three outputs Vs, Vc ', and Vfbs', determines the input signal from the matrix as described above, and outputs information including the relative position and the rotation direction.
  • an electromagnetic motor such a matrix method is used to process the resolver output
  • the pulse encoder is used for digital processing of pulse output, and the arithmetic circuit 2k may be configured using these general methods.
  • the piezoelectric element 6 V includes a piezoelectric material CM and at least three electrode pairs S 1 / SS, C 1 / CC, and FB / FB ′ sandwiching three regions of the piezoelectric material CM so as to output the output signal. These electrode pairs are provided at positions where the phases of vibration of the piezoelectric material CM are different from each other.
  • the arithmetic circuit 2 k can also calculate and output the amount of movement of the rotor 5 by integrating the periodic change amount of the phase difference ⁇ .
  • three kinds of signals are output from the piezoelectric element 6 V. However, two kinds of signals may be output.
  • FIG. 13 is a system configuration diagram showing a system configuration of such a position detecting device.
  • An electrode SS and an electrode CC are provided in the piezoelectric element 6 V, and the piezoelectric output from these is provided as in FIG.
  • a signal corresponding to the phase difference ⁇ of the voltage signal with respect to the drive signal is input to the arithmetic circuit 2k.
  • the arithmetic circuit 2k calculates the average value of the phase difference ⁇ indicated by each signal, calculates the relative position from the relationship between the phase difference ⁇ and the relative position, and integrates the periodic change amount of the phase difference ⁇ . And calculate the amount of movement of the mouth 5 for output.
  • two types of signals are output from the piezoelectric element 6 V, but this may be one type.
  • FIG. 14 is a system configuration diagram showing a system configuration of such a position detecting device.
  • the piezoelectric element 6 V is provided with an electrode FB.
  • the piezoelectric element 6V has a piezoelectric material CM and an electrode pair FB / FB 'sandwiching at least one region of the piezoelectric material CM so as to output an output signal.
  • FIG. 14 is a system configuration diagram showing a system configuration of such a position detecting device.
  • the piezoelectric element 6 V is provided with an electrode FB.
  • the piezoelectric element 6V has a piezoelectric material CM and an electrode pair FB / FB 'sandwiching at least one region of the piezoelectric material CM so as to output an output
  • a signal corresponding to the phase difference ⁇ with respect to the drive signal of the detection piezoelectric voltage signal output from the electrode FB is input to the arithmetic circuit 2k.
  • the arithmetic circuit 2k calculates the relative position from the relationship between the phase difference ⁇ and the relative position, or integrates the periodic variation of the phase difference ⁇ to move the rotor 5. Calculate the amount and output.
  • An experimental machine was prototyped for the position detection device shown in Fig. 14, and its characteristics were evaluated.
  • FIG. 15 is a graph showing the characteristics (dashed line) of the position detection device shown in FIG.
  • the horizontal axis shows the relative rotational position between the stay and the rotor (one wavelength of vibration is assumed to be 360 degrees), and the vertical axis shows the phase difference ⁇ between the drive signal and the piezoelectric voltage signal for detection.
  • the frequency of the drive signal is 48.000 kHz and the amplitude is 19 V, and the rotor 6 does not rotate due to the rotational displacement wave formed by the drive signal having such an amplitude.
  • the relationship between the relative rotational position and the phase difference ⁇ is almost linear, the measurement error including the reading error during measurement is ⁇ 0.5 °, and the SN ratio of the detection piezoelectric signal V fbs, is It is 80 dB or more, and this device can be fully used as a portable encoder.
  • the equivalent capacitance on the input side of V c, is 400 OpF. If the phase of the drive signal shifts, the graph moves in parallel and the detection angle changes.
  • the position detection method using the position detection device uses ultrasonic vibration for position detection, and uses a stationary stay and a rotor elastic body 5 e, 6 e opposed to each other.
  • a position detecting method for detecting a relative position between e and e wherein a step of vibrating the stay side elastic body 5 e; and a step of vibrating the rotor side elastic body 6 e by transmitting the vibration. Comparing and detecting the relative position.
  • the vibration of the stay-side elastic body 5e is transmitted to the rotor-side elastic body 6e, the rotor-side elastic body 6e also vibrates. By comparing the respective vibrations as described above, the relative position between these members 5 e and 6 e can be detected.
  • the step of vibrating the stay-side elastic body 5e includes causing the stay-side elastic body 5e to vibrate so as to generate a traveling wave as a rotational displacement wave along the position detection direction X.
  • the vibration is performed using the piezoelectric vibrator which can be industrially used relatively easily. That is, in the vibration step of the stay side elastic body 5e, a drive signal is applied to the piezoelectric vibrator 5V provided in the stay side elastic body 5e, By vibrating the moving element 5v, the stay side elastic body 5e is vibrated.
  • Various methods are conceivable for generating vibration. It is possible to generate vibration using a mechanical vibration mechanism, and it is also possible to generate vibration using an electromagnetic vibration mechanism such as a speaker.
  • the magnitude of the drive signal is set so that the rotor-side elastic body 6 e is not displaced along the position detection direction X due to the vibration of the stay-side elastic body 5 e.
  • This set value is, for example, 19 V as the magnitude of the amplitude of the drive signal.
  • the comparing step includes the output signal V s, (V c ′, V fbs) from the piezoelectric element 6 V provided on the low-side elastic body 6 e, and the driving signal A step of comparing with V s (V c) was included.
  • the drive signal V s and the output signal V s ′ indicate the vibration wave / positional relationship of the stay side elastic body 5 e and the mouth side elastic body 6 e, respectively.
  • the comparing step includes a step of detecting a phase difference ⁇ between the drive signal Vs and the output signal Vs'.
  • the phase difference ⁇ indicates a relative position between the stay side elastic body 5 e and the row side elastic body 6 e in consideration of the condition that the vibration waves have the same phase.
  • the stay-side elastic body 5e and the row-side elastic body 6e are arranged so that one of the vibrations is transmitted to the other via the solid, but these transmit gas when the vibration is transmitted. It may be arranged via In this case, since there is no friction between the stay side elastic body 5 e and the rotor side elastic body 6 e, it is possible to eliminate the load at the time of moving the row side elastic body 6 e.
  • the position detecting device includes: a stay-side elastic body 5 e and a rotor-side elastic body 6 e that are arranged to face each other so that vibration can be transmitted from one side to the other; A vibrator (vibration means) 5v for vibrating the body 5e, a piezoelectric element (vibration detection means) 6v for outputting a signal corresponding to the vibration of the low-side elastic body 6e, and output signals Vs ', Vc' , Vf bs ′ and a predetermined reference signal Vs.
  • the vibrator 5 V causes the stay-side elastic body 5 e to vibrate, and the piezoelectric element 6 V outputs a signal corresponding to the vibration generated in the row-side elastic body 6 e due to the transmission of the vibration.
  • the predetermined reference signal Vs is a drive signal for oscillating the vibrator 5 V, but may be, for example, an output signal of a crystal clock that is an oscillation source that generates the drive signal.
  • the piezoelectric vibrator 5 V and the piezoelectric element 6 V are respectively adhered to the stay side elastic body 5 e and the mouth side elastic body 6 e. Therefore, the vibration of the piezoelectric vibrator 5 V is directly transmitted to the stay-side elastic body 5 e corresponding to the drive signals Vs and Vc, and the vibration of the mouth-side elastic body 6 e is output signal Vs ′. , Vc ′, Vf bs, and are directly taken out of the piezoelectric element 6v.
  • the phase detection device of the above embodiment can be applied to an ultrasonic motor. That is, the two members 5 e and 6 e of the phase detection device shown in FIGS. 1 and 2 are arranged so as to relatively move in response to vibration when the drive signal is large, so that intentionally. By increasing the level of the drive signal, it functions as an ultrasonic motor having a function of detecting the rotational position of the rotor 6. In this ultrasonic mode, it is most efficient if the natural frequencies of the station 5 and the row 6 are substantially the same.
  • the ultrasonic motor according to the present embodiment generates rotational displacement waves in the circumferential direction of the opposing contact surfaces of both the stage 5 and the rotary unit 6, and the rotational displacement waves combine to generate a rotational displacement wave. Is locked, and the mouth 6 is rotated by rotating each rotation displacement wave relatively.
  • the rotational displacement wave is a wave of physical displacement composed of the physical deformation of the facing surfaces of the stays 5 and 6 and the facing surfaces of both the stays 5 and the mouth 6
  • the relative movement between the rotational displacement waves of the stay 5 and the mouth 6 is regulated.
  • Rotational displacement waves are generated on the opposing surfaces of both the stay 5 and the mouth 6 and the relative movement between the rotational displacement waves is regulated, and one rotational displacement wave as the ultrasonic wave surface is applied to the other. When it is moved, it moves relative to stay 5.
  • FIG. 16 is a system configuration diagram showing a system configuration of an ultrasonic motor including the position detection device shown in FIG.
  • a two-phase drive signal is applied to its electrodes S S and C C so that the piezoelectric element 6 V on the mouth side can vibrate similarly to the vibrator 5 V on the stay side.
  • the configuration of the oscillation circuit 2 a ′ for driving the low-side oscillator 6 V, the amplification circuit 2 b 2 d, and the phase shift circuit 2 c is equivalent to the oscillation for driving the low-side oscillator 5 v.
  • Circuit 2a, amplifier circuits 2b and 2d and phase shift circuit 2c are the same, but amplifier circuit 2d and the output are inverted by 180 ° and applied to electrode CC. This can be realized, for example, by inverting the polarity of the amplifier 2d 'output transformer.
  • the oscillation circuits 2a and 2a ' can be controlled by the control circuit 2z based on the detected phase, but this will be described later.
  • VD1 for example, Of 20 V or more
  • FIG. 17 is a sectional view taken along the circumferential direction of the stay / mouth / mouth contact portion when such a rotational displacement wave is combined.
  • the oscillation circuit 2a When the frequency and the phase of 2a 'are the same, the rotor 6 stops because the rotational displacement wave rotates in the same direction at the same speed. That is, the rotational displacement wave A generated at the convex portion 5 p of the stay side elastic body 5 e and the rotational displacement wave B generated at the convex portion 6 p of the rotor side elastic body 6 ⁇ are combined as if the gears meshed. Locking action occurs, but the mouth stops 6 because it rotates in the same phase.
  • the oscillation circuit 2 a ′ was used as the source of the drive signal for the mouth 6. However, since strict frequency management is actually required, the oscillation circuit 2 A drive signal on the rotor side is generated by adding + ⁇ f or ⁇ f to the signal based on the signal a.
  • the rotation direction is determined by the phase relationship between the displacement waves A and B.
  • the direction of rotation is determined by the relationship between the traveling direction of the displacement wave and the phase difference, and is not determined only by the traveling direction of the displacement wave. This point is significantly different from the conventional traveling wave type ultrasonic motor.
  • the rotation speed of the rotor 6 is increased or decreased.
  • the drive potential of the amplifier circuits 2 b and 2 d is set to a sufficiently small value VD 2 (for example, a voltage amplitude of 19 V or less) by controlling the switch SW 1.
  • VD 2 for example, a voltage amplitude of 19 V or less
  • VD2 is set to, for example, 1/10 or less of VD1.
  • the drive potential of the amplifier circuits 2 b ′, 2 d is set to 0 V by controlling the switch SW 2, and the detection voltage signals V s ′, V c ′ are only at the relative positions. Output in response.
  • the relative position detected in this way can be used for rotation control of the mouth 6. For example, immediately before turning on the power at the motor, the relative position of the rotor 6 to the stay 5 is unknown, so if the relative position is detected before the motor is started, the combined position of the rotational displacement wave is started. Can be set at any time.
  • the two members 5 and 6 of the phase detection device are arranged so as to relatively move in accordance with the vibration, and the two members 5 and 6 Each is configured as a stator and a movable element.
  • the movable element functions as a slider when performing linear motion, and functions as a mouth when performing rotary motion.
  • the position detecting device can detect the relative rotational position between the stay 5 and the low speed 6, but when the position detecting device functions as an ultrasonic motor, the position In the evening 5, a drive signal for rotational drive was supplied.
  • a drive signal for rotational drive is supplied to the stay 5
  • a traveling wave as an ultrasonic vibration wave traveling in a circumferential direction is generated on the surface thereof, and the traveling wave 6 in the pressed state is interposed therebetween. It rotates by frictional force.
  • the vibration wave has an amplitude in the thickness direction of the stay 5 and functions as a rotational displacement wave traveling in the circumferential direction.
  • position detection can be performed by using a standing wave instead of a traveling wave. The details are described below.
  • the standing wave vibration of mouth 6 is passively generated in response to the standing wave of stay 5; however, the position of the vibration wave viewed from the coordinate system of law 6 depends, for example, on the position of the vibration wave.
  • the mechanical configuration for generating a standing wave for position detection and a rotational displacement wave for rotational driving on the surface of the stay 5 is the same as that described with reference to FIGS.
  • an ultrasonic vibration wave that is, a standing wave
  • a standing wave is formed on the surface of the stay night side 5.
  • the relative position to evening 5 can be detected.
  • the standing wave of the rotor-side metal elastic body 6e generated by the transmission of the standing wave of the stay 5 is detected by the piezoelectric element 6V provided in the rotor.
  • the power supply to the stay side vibrator 5 V was directly connected to the vibrator 5 V from outside the lower lid member 3 L. This is performed via a conductive wire.
  • the vibrator 5 V connected to this conductive wire is fixed on the surface facing the elastic body 5 e by applying a single-phase drive signal for position detection, preferably a sinusoidal signal or a cos wave signal. It is configured such that a wave is formed. example For example, if only one of Vs and Vc is applied to the transducer 5v, a standing wave can be generated.
  • the circumferential length of one electrode shown in FIG. 4, for example, the electrode S1 is set to be half of the wavelength of one oscillation, so that the circumferential length of one electrode, for example, electrode S1, is 5 times.
  • a stationary wave of a plurality of wavelengths that is fixed throughout the entire direction is generated in step 5. If the phase within one wavelength of the standing wave is assumed to be 360 degrees, a wave of five wavelengths is generated around one circumference of the elastic bodies 5 e and 6 e in this example.
  • the drive signal Vs in the timing chart shown in FIG. 5 is a sine wave.
  • a specific point for example, the center point s i of S1
  • the point s2 separated from the specific point s1 by 1/2 is oscillated in the opposite phase to the vibration of the specific point because the polarization direction is opposite. Therefore, as shown in FIG. 4, the application of the single-phase drive signal Vs causes the circumferential length to be an integral multiple of the wavelength, so that a standing wave is generated on the vibrator 5 V and the elastic body 5 e. appear.
  • the driving signal may be a cos wave as long as it generates a standing wave, and if the driving signal does not change the phase of the vibration of the vibrator 5 V due to the application of the driving signal. This may be applied to any electrode of the oscillator 5 V.
  • the amplitude of the standing wave generated in this way is proportional to the amplitude of the drive signal, but its phase is fixed. That is, the position of the standing wave with respect to the coordinate system of stay 5 is specified in advance.
  • the vibrator 5V is attached to the elastic body 5e, and the vibration formed by the two generates a standing wave having the same phase as that of the standing wave on the surface of the stay 5.
  • the application of the drive signal for position detection causes a standing wave to be generated on stage 5 and the same phase on row 6 as viewed from the coordinate system of stage 5 A standing wave is generated.
  • a rotational displacement wave is generated on the stage 6 by applying a drive signal for rotational drive.
  • the piezoelectric element When a voltage of a certain magnitude is applied to the piezoelectric element, the piezoelectric element is distorted, but when the piezoelectric element is distorted similarly, a voltage of the same magnitude is output.
  • a standing wave is generated in the elastic body 5 e by the vibration of the vibrator 5 V, the elastic body 5 e is distorted as described above, and a standing wave is generated on the surface. Since the elastic body 6e is transmitted to the body 6e, the elastic body 6e is distorted in accordance with the distortion of the standing wave, and the piezoelectric element 6V outputs piezoelectric voltage signals Vs', Vc, Vfbs, corresponding to the distortion.
  • the piezoelectric voltage signals Vs', Vc ', and Vf bs' are respectively applied to the electrodes CC (C1 to C4), the electrodes SS (S1 to S4), and the electrodes FB, ( FB) output voltage.
  • the piezoelectric voltage signals Vs ′, Vc, and Vfbs, output from the piezoelectric element 6 V for example, when the area of the individual output electrodes is very small, the amplitude of the output voltage is determined by the position on the station 5 side. Therefore, the relative position between steps 5 and 6 can be detected from each of them.
  • position detection using the two signals Vs' and Vc will be described.
  • the piezoelectric element 6v outputs Vs 'and Vc' according to the distortion, similarly to the vibrator 5V.
  • the stationary electrode S1 shown in FIG. If the driving signal is only Vs when the mouth side electrode C1 shown in 9C overlaps, following the example of Fig. 5, the piezoelectric voltage signal Vs' is equal to this, and the sinusoidal voltage signal And In this case, the amplitude of Vc 'generated during the generation of the traveling wave becomes zero because the charges generated in one electrode cancel each other.
  • Vc ' is a sine wave voltage signal having zero amplitude.
  • this relative position is set to Vs 'or Vc', as in the case where the electrode area is very small. It is also possible to detect based on. In this case, the detection accuracy (resolution) decreases. Considering the detection accuracy, it is desirable to detect the relative position by calculating the ratio using Vs' and Vc.
  • the relative position is detected by appropriately adjusting the phases of Vs 'and Vc' and mixing them in consideration of the detection accuracy and the saturation amount.
  • the amplitudes of Vs 'and Vc' differ depending on the relative position, they have the same phase because they originate from the same standing wave.
  • the phase difference between the phase of the original sine function and the phase difference of the composite function given by the sum of the sine function and cosine function that differ only in the amplitude indicates the relationship between the amplitudes. Therefore, by setting a phase difference of 90 degrees to one of the sine waves Vs 'and Vc, and mixing them, the amplitude relationship, that is, the position relative to the phase of the reference signal Vs' based on the relative position is obtained. It can be output as a phase difference.
  • the reference signal Vs may be Vs.
  • FIG. 18 is a system configuration diagram showing a system configuration in the control device 2.
  • the arrows between the piezoelectric elements 5v and 6V indicate that the arrangement positions of the piezoelectric elements 5v and 6V are mutually variable.
  • the drive signal Vs is generated by amplifying the clock pulse signal output from the oscillation circuit 2a by the amplification circuit 2b.
  • the amplifier circuit 2b also has a function of blocking high-frequency components.
  • the amplitude of the drive signal Vs applied to the oscillator 5 V is set to, for example, 75 V.
  • the feedback signal from the feedback electrode FB is fed back to the oscillation circuit 2a, which preferably includes a phase comparator, LPF, and a voltage controlled oscillator, and the output frequency of the oscillation circuit 2a matches the resonance frequency of the station 5. Is controlled as follows.
  • a waveform shaping circuit 2g composed of a limiter circuit including an amplifier circuit or a comparator if necessary, and output as a square wave.
  • a variable that changes with position, ⁇ indicates angular frequency, and ⁇ indicates phase.
  • the mixing levels may be adjusted based on this level.
  • the mixing level is set so that the maximum level of each signal is equal. It should be noted that the level adjustment is desirably performed in consideration of the loss caused by the phase shift circuit 2c "so that the result is equal, in other words, so that accurate relative position detection can be performed.
  • phase of the converted square wave is compared with the driving signal (phase of Vs) in the state of the square wave by the phase detection circuit 2 j, and the phase detection circuit 2 j outputs the phase difference ⁇ , that is, according to the relative position.
  • a voltage signal is output and input to the arithmetic circuit 2k.
  • the arithmetic circuit 2 k calculates the relative position from the phase difference ⁇ , And the amount of movement of the rotor 5 is calculated and output.
  • the conventional ultrasonic motor includes a stay and a rotor which are arranged opposite to each other in a pressure contact state, supplies a drive signal only to the stay and ultrasonically vibrates the drive signal, and responds to the vibration.
  • the rotor is rotating. More specifically, the supply of the drive signal causes the traveling wave as the above-described rotational displacement wave to be generated on the surface of the stay, and the frictional force between the traveling wave of the stay and the mouth causes a low force to be generated. It is spinning.
  • a rotational displacement wave is used.
  • a sinusoidal drive signal V s is applied to the electrode SS and a cos wave drive signal Vc is applied to the electrode CC
  • the vibrator 5 V vibrates, generating a rotational displacement wave on its surface, and responding to the rotational displacement wave.
  • the rotor 6 rotates.
  • the switch SW is turned on to apply the cos-wave drive signal Vc to the electrode CC, and the phase of the clock pulse signal from the oscillation circuit 2a is shifted 90 degrees by the phase shift circuit 2c, and then amplified.
  • the signal is amplified by the circuit 2d to generate the signal Vc.
  • the presence or absence of the supply of the signal Vc may be controlled by, for example, adjusting the drive voltage of the amplifier circuit 2d while the switch SW is always in the ON state.
  • the relative position detected as described above can be used for rotation control of the rotor 6. For example, immediately before turning on the power at the motor, the relative position of the mouth 6 and the station 5 is unknown, so if the relative position is detected before the motor starts, the combined position of the rotational displacement wave
  • the process can be performed according to the position of the mouth as needed, for example, by adjusting to the time of startup. Also, it can be used for measurement when setting set conditions before motor operation.
  • Fig. 19 is a circuit diagram showing an example of the simplest specific circuit of the phase shift circuit 2c "and the mixer circuit MX.
  • the phase shift circuit 2c may be connected in three stages with a phase difference of 30 degrees to provide a phase difference of 90 degrees, or an amplifier may be used as the mixer circuit MX. You may use what you have.
  • the position detection device shown in Fig. 18 uses a rotational displacement wave to lock the displacement. It can function as a PT lap type ultrasonic module.
  • the drive method of the displacement lock drive method is a type of drive method different from the drive method of a normal ultrasonic motor, and generates a rotational displacement wave not only in the stay but also in the mouth.
  • these two rotational displacement waves are combined with each other by pressing them, the relative movement between the stay and the mouth is regulated.
  • one of the rotational displacement waves is rotated with respect to the other in a state where the relative movement of both is regulated in this way, the rotator rotates relative to the stayer.
  • the displacement lock drive method is different from the conventional drive method based on the frictional force between each point in the minute area of the stay and low contact surfaces, and is based on the combination of the rotational displacement waves that function as the ultrasonic surface.
  • the driving force is large, and the control accuracy of the moving amount can be improved.
  • the ultrasonic motor can be driven with the maximum displacement from the stopped state to the maximum speed range by adjusting the relative speed between the rotational displacement waves. This is fundamentally different from the drive method in which the amount of displacement required for friction must be reduced due to low-speed rotation.
  • the driving force is larger than that of the conventional method, particularly in a low speed range.
  • FIG. 20 is a system configuration diagram of a displacement lock drive type ultrasonic motor equipped with the position detecting device shown in FIG.
  • a two-phase drive signal is applied to its electrode SS and electrode CC so that the piezoelectric element 6 V on the low side can vibrate similarly to the transducer 5 V on the stay side.
  • the configuration of the oscillation circuit 2 a ′, the amplifier circuits 2 b ′, 2 d ′, and the phase shift circuit 2 c ′ for driving the mouth-side oscillator 6 V drives the stage-side oscillator 5 V.
  • Circuit 2a, amplifying circuits 2b, 2d and phase shift circuit 2c, and the phase shift direction of phase shift circuit 2c ' is the rotational displacement wave of stay 5 and rotor 6. Are set to rotate in the same direction.
  • VD 1 for example, a voltage of 20 V or more
  • the drive potential of the amplifier circuits 2d, 2b ', 2d is set to a sufficiently small value VD2 (preferably 0V) by controlling the switch SW1 (off state).
  • VD2 preferably 0V
  • a standing wave is generated on the station 5 and the detection voltage signal Vs ', Vc' is output only in accordance with the relative position.
  • the signals Vs' and Vc are provided with a phase difference of 90 degrees by the phase shift circuit 2c ", are combined by the mixer circuit MX, and are then shifted with respect to the drive signal Vs through the waveform shaping circuit 2g.
  • the square wave signal is output as a square wave signal having a phase difference.
  • This square wave signal is phase-detected together with the drive signal Vs in a square wave state through a gate circuit G that allows the input signal to pass when the relative position is detected (SW1 off state).
  • the circuit 2j After being input to the circuit 2j and being compared in phase, it is input to the arithmetic circuit 2k and subjected to signal processing in the same manner as in the device shown in Fig. 18.
  • the oscillation circuit 2a , 2 a 'controlled by control circuit 2 z Based on the detected phase, the oscillation circuit 2a , 2 a 'controlled by control circuit 2 z However, this will be described later.
  • a position detection device using a transducer 5 V as shown in FIG.
  • the vibrator 5 V divides its circumference into 10 equal parts, and the polarization directions of the equally divided individual regions are alternately different as shown in the figure.
  • the drive signal Vs for generating a standing wave can be given to all of the electrodes S1 to S8. In this case, it functions only as a rotation position detection device that can drive efficiently, not as a motor.
  • the position detection method is a position detection method for detecting a relative position between two members 5 e and 6 e that are arranged opposite to each other, and is arranged along the position detection direction. Vibrating one of the members 5e so that a standing wave is generated, and detecting the relative position by comparing the vibration with the vibration generated on the other member 6e by transmission of the vibration. Is provided.
  • the position detecting device includes two members 5 e and 6 e opposed to each other so that vibration can be transmitted from one side to another, and a standing wave is generated along the position detecting direction x.
  • the predetermined reference signal is preferably a drive signal for vibrating the vibration means, but may be, for example, an output signal of a crystal clock which is an oscillation source for generating the drive signal.
  • the ultrasonic motor having such a position detecting function is provided with drive signals V s and V so that a rotational displacement wave is generated on at least one of the opposed surfaces of the stator 5 and the mover 6 which are opposed to each other in the pressed state.
  • An ultrasonic motor in which c is supplied and vibrated so that the moving element 6 moves in accordance with the vibration, and a predetermined signal that generates a standing wave on the facing surface is supplied to the stator 5 and the moving element. 6 to detect the vibration of the other of the stator 5 and the movable element 6 and output a signal corresponding to the relative position between the stator 5 and the movable element 6.
  • the standing wave D has a displacement in the thickness direction with respect to the circumferential length X, and the standing wave side oscillator 5 V that generates the standing wave D has It is assumed that the piezoelectric element 6 V on the mouth side is shifted.
  • the deviation amount is 0, / 8, 2 inputs / 8, 2 ⁇ / 8, 3 inputs / 8, 4 inputs / 8, 5 people / 8, 6 people / 8, 7 inputs / 8, 8 inputs / Let us consider the case where it is at position 8.
  • FIG. 23 shows the relative position (0, E / 8, 2E / 8, 2E / 8, 3 people / 8, 4E / 8, 5E / 8, 6E / 8, 7E / 8, 8 ⁇
  • FIG. 8 is an explanatory diagram for explaining the relationship between / 8) and the synthesized signal Vm.
  • the generated potentials of the rotor-side output signals Vs', Vc, and the polarities are indicated by vectors a 'and b', respectively, with their polarities being 10 on the right and 1 on the left.
  • Fig. 23 (b) is a diagram showing the vector of the composite signal of a and b 'when the vector b, shown in Fig.
  • Fig. 23 (a) is advanced 90 degrees
  • Fig. 23 (c) is It is a graph which shows the waveform of the synthetic signal when the vector b 'is advanced 90 degrees.
  • the detection level (potential) changes according to the relative position, but the phase relationship (polarity) is + or only in one direction.
  • the other vibration of the stay 5 and the mouth 6 is used as the position detection target source directly, so that the relative position between the stay 5 and the mouth 6 can be obtained.
  • a corresponding signal can be output, and these relative positions can be detected.
  • the conventional single-purpose encoder is not required, so that the ultrasonic motor can be downsized. It becomes possible.
  • the ultrasonic wave according to the present embodiment Although a rotary encoder is not particularly necessary in the present embodiment, it may be provided separately according to the circuit configuration.
  • the valley of the vibration waveform of the row 6 which is supposed to coincide with the peak of the vibration waveform of the step 5 is not always located at the peak of the vibration waveform.
  • the mouth 6 may be moved so that these may be combined, or a slip state may occur, resulting in a loss of driving force.
  • the relative positions of the two do not often coincide with the phase of the drive signal. He moved to the mountain at night 5 as if he was babbling.
  • the ultrasonic motor (A) after detecting the relative position between the stays 5 and 6 and (B) the transducers 5 v and 6 Phase difference between the vibrations of the transducers 5 v and 6 V so that the vibration waveforms A and B of the transducers 5 V and 6 v when both V are actively vibrated, in other words, the drive signal Adjust the phase difference, that is, the frequency difference.
  • the detected relative position can be used for setting the set condition before the motor is operated.
  • the oscillation circuits 2a and 2a ' are controlled by the control circuit 2z, and the control circuit 2z receives a command from an external host device or the like and performs predetermined rotation of the ultrasonic motor. Control is performed so that a predetermined frequency difference is given to the oscillation circuits 2a and 2a so as to perform the movement.
  • the phase detection circuit 2j outputs a phase difference ⁇ , ie, a voltage signal corresponding to the relative position. Is output and input to the arithmetic circuit 2k.
  • the arithmetic circuit 2k calculates a relative position from the phase difference ⁇ , or integrates a periodic change amount thereof to calculate and output a moving amount of the rotor 5. This signal is sent to an external host device or the like via the control circuit 2z, and becomes information on the relative rotational position and the amount of rotation. In the detection method of the present example, detection is performed within one oscillation wavelength.
  • SW1 is momentarily turned off every one-fifth of a turn to detect the position, correct the drive signal if necessary, or It is possible to perform control such as detecting that the vehicle has moved to a location.
  • the ultrasonic motor When the ultrasonic motor is driven by the displacement lock drive method, as described above, the switch SW 1 is turned on, and the transducers 5 V and 6 V of the star 5 and the mouth 6 are connected to the electrode SS and the electrode CC. Then, a two-phase drive signal is applied to rotate the rotor 6. More specifically, the ultrasonic motor includes a control circuit 2z to which a phase difference signal (indicating a relative position) output from the phase detection circuit 2j is input. The control circuit 2 z adjusts the phase difference between the vibrations of the vibrators 5 V and 6 V so that the vibration waveforms A and B are combined according to the relative position between the input stay 5 and the mouth 6 I do.
  • a phase difference signal indicating a relative position
  • the control circuit 2 z controls the phase difference between the drive signals to one oscillator circuit 2 a ′. Adjust with. The phase difference between the two drive signals may be adjusted by controlling the other oscillation circuit 2a.
  • the driving signal output from the oscillation circuit 2a ' since the driving signal output from the oscillation circuit 2a 'is actually generated from the driving signal output from the oscillation circuit 2a, it may be adjusted. That is, the phase of the drive signal output from one oscillation circuit 2a is changed to the other. It is shifted by the relative position. For example, when generating a drive signal to be applied to the oscillators 5 v and 6 V by dividing the clock pulse output from the oscillation circuit 2 a, one pulse is thinned out or added from this clock pulse. By dividing the frequency, the phase of the frequency-divided signal can be shifted by one pulse.
  • any one of the phases is adjusted according to the relative position to reduce the loss of driving force transmission.
  • FIG. 24 is a system configuration diagram showing a system configuration in the control device 2.
  • switches SW1 and SW2 are provided.
  • a two-phase drive signal is supplied to both the station 5 and the rotor 6 via the electrodes SS and CC.
  • switch SW1 is connected to potential VD2, and switch SW2 is connected to ground potential.
  • VD2 the oscillation of the mouth 6 stops, and the driving signal Vs of the sin wave is given to the electrode SS on the staying side, and the driving signal Vc of the cos wave is given to the electrode CC.
  • Waves are generated.
  • the amplitude of the rotational displacement wave is larger than a predetermined value, the rotor 6 rotates according to the rotational displacement wave.
  • the amplitude is set to be equal to or smaller than the predetermined value.
  • Rouyuu 6 will not be rotated. That is, at the time of measurement of the relative position, sufficiently small value VD 2 (e.g. not more than the voltage amplitude 19 V p _ p by controlling the amplifier circuit 2 b, 2 d switches SW1 driving potential of the mouth - evening 6 VD 2 is set to, for example, 1/10 or less of VD 1.
  • the rotational displacement wave generated on the surface of the station 5 is transmitted to the mouth-side piezoelectric element 6 V, and Fig.
  • Vf bs only the piezoelectric signal Vf bs, is extracted from the electrode FB '.
  • other signals may be extracted as needed. That is, for example, only two signals Vs ′, Vc, may be extracted and processed in the same manner as Vf bs ′.
  • the rotational direction can be obtained together with the relative position.
  • the relative position and rotation are determined based on the matrix as described above. Outputs information including turning direction.
  • the waveform shaping circuit 2 g including a limiter circuit or a comparator converts the detection piezoelectric voltage signal Vfbs ′ into a square wave and outputs it. Note that a gate circuit may be provided at the subsequent stage of the wave forming circuit 2g as in FIG.
  • the phase of each converted square wave is compared with the drive signal in a square wave state by the phase detection circuit 2j, and the phase detection circuit 2j outputs a phase difference ⁇ , that is, a voltage signal corresponding to the relative position. And input to the arithmetic circuit 2k.
  • the arithmetic circuit 2k calculates a relative position from the phase difference ⁇ , or integrates a periodic change amount thereof to calculate and output a moving amount of the rotor 5. As described above, this signal is sent to an external host device and used for rotation control.
  • the above-mentioned matrix method is used for resolver output processing in electromagnetic mode and digital processing for pulse output in optical encoders and magnetic pulse encoders. In the case of obtaining the included information, the arithmetic circuit 2 k may be configured using these general methods.
  • the ultrasonic motor includes a control circuit 2 z to which a phase difference signal (indicating a relative position) output from the phase detection circuit 2 j is input.
  • the control circuit 2 z adjusts the phase difference between the vibrations of the vibrators 5 v and 6 V so that the vibration waveforms A and B are combined according to the relative position between the input stay 5 and the rotor 6.
  • the control circuit 2 z controls the phase difference between the drive signals, for example, to control one of the oscillation circuits 2 a ′. Adjust accordingly. Note that the adjustment of the phase difference between the drive signals is the same as that described with reference to FIG. 20, and a description thereof will not be repeated.
  • the vibration of the mouth and mouth 6 is intermittently stopped for a very short time when the mouth and mouth 6 rotate, and after detecting the relative position at the stop, any one of the phases is compared. It is to be adjusted according to the position.
  • the ultrasonic motor supplies a drive signal to the low-side vibrator 6 V during low-speed rotation 6 times, and stops the supply intermittently.
  • a gate circuit G1 that passes a signal from the phase detector 2j indicating a phase difference ⁇ (relative position) to the hold circuit H1 when a drive signal of the gate circuit Gl is not supplied;
  • the circuit includes a timing generation circuit T1 for generating the timings of these circuits Gl, G2, H1, and a control circuit 2z to which a signal indicating a relative position passing through the gate circuit G2 is input.
  • the control circuit 2 z adjusts the vibration of the oscillators 5 v and 6 V so that the vibration waveforms A and B are combined according to the relative position between the input stay 5 and the mouth 6. Adjust the phase difference.
  • a configuration in which the intermittent stop is not performed that is, a configuration in which the circuits Gl, T1, G2, and H1 are omitted can be adopted.
  • This ultrasonic motor is an ultrasonic motor in which a driving signal is supplied to both the stator 5 and the movable element 6 which are arranged in a pressure contact state and vibrated, and the movable element 6 moves in accordance with the vibration. , The vibration of one of the stator 5 and the mover 6 is detected by the other, A signal corresponding to the relative position between the slaves 6 is output. There is a fixed relationship between the drive signal supplied to one of the stator 5 and the mover 6 and one position, and a fixed relationship between the detection signal output from the other and the other position. . In the above embodiment, since these relations are phase relations, electrical post-processing can be easily performed and the device configuration can be simplified.
  • the relative position is detected and used. Therefore, not only the rotational position is detected, but also the vibration of the stator and the moving element is performed. The displacement between the waveforms can be suppressed, and unintended movement such as when the power is turned on can be prevented.
  • the present invention can be used for an ultrasonic motor having a position detection function.

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  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)

Abstract

Cette invention a trait à un moteur à ultrasons dans lequel un élément fixe (5) pourvu d'un vibrateur (5v) est à l'opposé d'un élément mobile (6) pourvu d'un vibrateur (6v), cet élément mobile étant mis en mouvement par les vibrations des vibrateurs. On détermine la position relative entre l'élément fixe (5) et l'élément mobile (6) par la détection des vibrations produites par l'un des vibrateurs lorsque seul l'autre vibrateur est activement mis à vibrer. On ajuste la différence de phase des vibrations entre les deux vibrateurs de manière que les formes d'onde de vibration puissent coïncider en phase lorsque les deux vibrateurs sont activement mis à vibrer conformément à la position relative déterminée. Il en découle que les formes d'onde de l'élément fixe (5) et de l'élément mobile (6) ne risque pas de s'écarter les unes des autres.
PCT/JP1999/002851 1998-05-29 1999-05-28 Technique de detection de position et appareil correspondant, moteur a ultrasons et technique de commande de ce moteur WO1999063653A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP10/149586 1998-05-29
JP10149586A JPH11341844A (ja) 1998-05-29 1998-05-29 位置検出方法並びに装置及びこれを用いた超音波モータ
JP10/246269 1998-08-31
JP10246260A JP2000078864A (ja) 1998-08-31 1998-08-31 位置検出方法並びに装置及び超音波モータ
JP10/246260 1998-08-31
JP10246269A JP2000078865A (ja) 1998-08-31 1998-08-31 超音波モータの駆動方法

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WO1999063653A1 true WO1999063653A1 (fr) 1999-12-09

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63253882A (ja) * 1987-04-10 1988-10-20 Citizen Watch Co Ltd 進行波ステツプモ−タ
JPH023196U (fr) * 1988-06-20 1990-01-10
JPH0236774A (ja) * 1988-07-22 1990-02-06 Nec Corp 振動波モータ
JPH0471371A (ja) * 1990-07-11 1992-03-05 Sony Corp 超音波モータ
JPH04193080A (ja) * 1990-11-27 1992-07-13 Nikon Corp 超音波モータ
JPH04281375A (ja) * 1991-03-08 1992-10-06 Nikon Corp 振動モータの駆動装置
JPH0576188A (ja) * 1991-09-11 1993-03-26 Nec Corp 振動波モータ装置

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63253882A (ja) * 1987-04-10 1988-10-20 Citizen Watch Co Ltd 進行波ステツプモ−タ
JPH023196U (fr) * 1988-06-20 1990-01-10
JPH0236774A (ja) * 1988-07-22 1990-02-06 Nec Corp 振動波モータ
JPH0471371A (ja) * 1990-07-11 1992-03-05 Sony Corp 超音波モータ
JPH04193080A (ja) * 1990-11-27 1992-07-13 Nikon Corp 超音波モータ
JPH04281375A (ja) * 1991-03-08 1992-10-06 Nikon Corp 振動モータの駆動装置
JPH0576188A (ja) * 1991-09-11 1993-03-26 Nec Corp 振動波モータ装置

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