WO2023188516A1 - Dispositif de commande pour commander un dispositif de vibration et procédé de commande de dispositif de vibration - Google Patents

Dispositif de commande pour commander un dispositif de vibration et procédé de commande de dispositif de vibration Download PDF

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Publication number
WO2023188516A1
WO2023188516A1 PCT/JP2022/042060 JP2022042060W WO2023188516A1 WO 2023188516 A1 WO2023188516 A1 WO 2023188516A1 JP 2022042060 W JP2022042060 W JP 2022042060W WO 2023188516 A1 WO2023188516 A1 WO 2023188516A1
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Prior art keywords
frequency
piezoelectric element
control device
impedance
changing
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PCT/JP2022/042060
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English (en)
Japanese (ja)
Inventor
崇彰 森
政明 ▲高▼田
宣孝 岸
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株式会社村田製作所
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Publication of WO2023188516A1 publication Critical patent/WO2023188516A1/fr

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    • 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
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/20—Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators

Definitions

  • the present disclosure relates to a control device for controlling a vibration device and a method for controlling the vibration device.
  • Patent Document 1 discloses a piezoelectric motor drive circuit that controls and drives the piezoelectric element so that the alternating current flowing through the piezoelectric element remains approximately constant even if the resonant frequency characteristics of the piezoelectric element vary due to changes in ambient temperature, etc. .
  • an object of the present disclosure is to provide a control device for controlling a vibration device and a method for controlling the vibration device, which can appropriately control the drive frequency for driving a piezoelectric element.
  • a method includes: A method for controlling a vibration device including a piezoelectric element using a control device, the method comprising: changing the voltage waveform applied to the piezoelectric element; Measuring a value related to impedance of the piezoelectric element; determining a driving frequency for driving the piezoelectric element based on the measured value regarding the impedance of the piezoelectric element; including.
  • a control device includes: A control device for controlling a vibration device including a piezoelectric element, a processor that transmits a drive signal for driving the piezoelectric element; a memory storing instructions to be executed by the processor; Equipped with The said instruction is changing the voltage waveform applied to the piezoelectric element; Measuring a value related to impedance of the piezoelectric element; determining a driving frequency for driving the piezoelectric element based on the measured value regarding the impedance of the piezoelectric element; including.
  • vibration device control device and vibration device control method it is possible to appropriately control the drive frequency for driving the piezoelectric element.
  • FIG. 1 is a perspective view for explaining the configuration of an imaging unit according to Embodiment 1.
  • FIG. 1 is a schematic cross-sectional view showing a cross-sectional configuration of an imaging unit according to Embodiment 1.
  • FIG. 1 is a schematic cross-sectional view showing a cross-sectional configuration of a vibrating device according to Embodiment 1.
  • FIG. 2 is an exploded perspective view showing each component of the vibration device according to the first embodiment.
  • FIG. 2 is a block diagram for explaining the configuration of a control device that controls the vibration device according to the first embodiment.
  • FIG. 3 is an operation mode transition diagram for explaining the operation of the control device that controls the vibration device according to the first embodiment. 3 is a flowchart for explaining the operation of the control device that controls the vibration device according to the first embodiment.
  • FIG. 7 is a flowchart for explaining the operation of the control device that controls the vibration device according to Modification 1 of Embodiment 1.
  • FIG. 7 is a flowchart for explaining the operation of a control device that controls a vibration device according to a second modification of the first embodiment.
  • 7 is a flowchart for explaining the operation of the control device that controls the vibration device according to the second embodiment.
  • FIG. 10 An example of a plurality of clocks included in a drive signal whose clock widths have been changed in the method of controlling the vibration device by a control device according to the second embodiment is shown.
  • 10 shows the relationship between the frequency of a drive signal and the resonant frequency in a graph showing the relationship between the resonant frequency and impedance of a piezoelectric element.
  • 7 is a flowchart for explaining the operation of a control device that controls a vibration device according to Modification 1 of Embodiment 2.
  • FIG. An example of a plurality of clocks included in a drive signal whose clock widths have been changed in a method of controlling a vibration device using a control device according to Modification 2 of Embodiment 2 is shown.
  • An imaging unit is provided at the front or rear of a vehicle, and images captured by the imaging unit are used to control safety devices and perform automatic driving control. Since such an imaging unit is often installed outside the vehicle, foreign matter such as raindrops, mud, and dust may adhere to a transparent body such as a lens or protective glass that covers the outside. If foreign matter adheres to the transparent body, the foreign matter will be reflected in the image captured by the imaging unit, making it impossible to obtain a clear image.
  • a vibration device that vibrates a transparent body to remove foreign substances.
  • Such a vibration device uses a piezoelectric element to vibrate a transparent body, but the resonance frequency of the piezoelectric element is affected by various factors such as heat generated by the piezoelectric element and foreign matter attached to the transparent body. Varies depending on factors. Therefore, unless the driving frequency for driving the piezoelectric element is appropriately controlled, the transparent body cannot be efficiently vibrated.
  • a control device that searches for the resonance frequency of the piezoelectric element.
  • one possible method for improving the resonant frequency search performance is to increase the performance of the processor of the control device.
  • increasing the performance of the processor in the control device causes problems such as increased manufacturing cost and increased mounting area of the processor.
  • a method includes: A method for controlling a vibration device including a piezoelectric element using a control device, the method comprising: changing the voltage waveform applied to the piezoelectric element; Measuring a value related to impedance of the piezoelectric element; determining a driving frequency for driving the piezoelectric element based on the measured value regarding the impedance of the piezoelectric element; including.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled. Furthermore, manufacturing costs can be reduced.
  • the step of changing the voltage waveform may include changing an effective voltage of the voltage waveform.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the step of changing the voltage waveform may include changing the amplitude of the voltage waveform.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the step of changing the voltage waveform may include increasing the amplitude of the voltage waveform.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the step of changing the voltage waveform may include decreasing the amplitude of the voltage waveform.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the method further includes changing the frequency of a drive signal that drives the piezoelectric element.
  • the step of measuring the impedance value may include measuring the impedance value while the frequency is changing.
  • the drive frequency for driving the piezoelectric element can be controlled more appropriately.
  • the step of changing the voltage waveform is performed. may be done.
  • the drive frequency for driving the piezoelectric element can be controlled more appropriately.
  • the impedance-related value is an impedance value
  • the step of determining the driving frequency includes: determining whether the value related to the impedance is less than or equal to a predetermined threshold; determining a frequency of a drive signal for driving the piezoelectric element as the drive frequency when it is determined that the value related to the impedance is less than or equal to a predetermined threshold; It may have.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • a control device includes: A control device for controlling a vibration device including a piezoelectric element, a processor that transmits a drive signal for driving the piezoelectric element; a memory storing instructions to be executed by the processor; and the said instruction comprises: changing the voltage waveform applied to the piezoelectric element; Measuring a value related to impedance of the piezoelectric element; The method includes the step of determining a driving frequency for driving the piezoelectric element based on the measured value regarding the impedance of the piezoelectric element.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled. Furthermore, manufacturing costs can be reduced.
  • the step of changing the voltage waveform may change an effective voltage of the voltage waveform.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the step of changing the voltage waveform may change the amplitude of the voltage waveform.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the step of changing the voltage waveform may increase the amplitude of the voltage waveform.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the step of changing the voltage waveform may reduce the amplitude of the voltage waveform.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the instruction further includes the step of changing the frequency of the drive signal.
  • the step of measuring the impedance value may include measuring the impedance value while the frequency is changing.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • the step of determining the drive frequency if the drive frequency cannot be determined based on the value related to the impedance measured while the frequency is changing, the step of changing the voltage waveform is performed. May be executed.
  • the drive frequency for driving the piezoelectric element can be controlled more appropriately.
  • the value related to impedance is an impedance value
  • the step of determining the driving frequency includes: determining whether the value related to the impedance is less than or equal to a predetermined threshold; determining the frequency of the drive signal as the drive frequency when it is determined that the value related to the impedance is less than or equal to a predetermined threshold; It may have.
  • the drive frequency for driving the piezoelectric element can be appropriately controlled.
  • first, second, etc. are used for descriptive purposes only and are not to be understood as expressing or implying relative importance or ranking of technical features. Shouldn't. Features defined as “first” and “second” are expressly or implied to include one or more such features.
  • FIG. 1 is a perspective view for explaining the configuration of an imaging unit according to the first embodiment.
  • FIG. 2 is a schematic cross-sectional view showing the cross-sectional configuration of the imaging unit according to the first embodiment.
  • FIG. 3 is a schematic cross-sectional view showing the cross-sectional configuration of the vibration device according to the first embodiment.
  • FIG. 4 is an exploded perspective view showing each component of the vibration device according to the first embodiment.
  • the imaging unit 100 includes a housing 1, a vibration device 10, and an imaging device 5.
  • the housing 1 includes an imaging device 5.
  • the housing 1 exposes a part of the vibration device 10.
  • the material of the housing 1 is, for example, resin.
  • the vibration device 10 includes a transparent body 2, a vibrating body 12 that vibrates the transparent body 2, and a retainer 13 that supports the transparent body 2 at its outer periphery. As shown in FIG. 1, in the vibrating device 10, a portion of the transparent body 2, the retainer 13, and the vibrating body 12 are exposed through a hole provided in the housing 1. The vibration device 10 vibrates the transparent body 2 to remove foreign matter attached to the transparent body 2 .
  • the transparent body 2 is placed in front of the imaging device 5.
  • the vibration device 10 removes foreign matter attached to the transparent body 2.
  • the light-transmitting body 2 has a light-transmitting property that allows energy rays or light having a wavelength detected by the imaging device 5 to pass therethrough.
  • the light-transmitting body 2 may be a lens having light-condensing properties.
  • the vibrating body 12 vibrates the transparent body 2 to remove attached foreign matter.
  • the vibrating body 12 has a cylindrical shape.
  • the vibrating body 12 is provided with, for example, a hollow circular piezoelectric element 14 on a surface opposite to the surface in contact with the transparent body 2, that is, an annular piezoelectric element 14.
  • a wiring 15 having a hollow circular, ie, ring-shaped electrode is provided on the opposite surface of the surface that is in contact with the vibrating body 12.
  • the position of the piezoelectric element 14 provided on the vibrating body 12 is not limited to the position shown in FIG. 3.
  • the retainer 13 is connected to the vibrating body 12.
  • the retainer 13 and the vibrating body 12 are each threaded, and the retainer 13 and the vibrating body 12 are connected by fitting the respective threaded parts.
  • the material of the retainer 13 may be, for example, not only metal such as stainless steel, aluminum, iron, titanium, and duralumin, but also plastic.
  • the vibrating device 10 may further include a configuration for discharging a cleaning liquid (cleaning body) onto the transparent body 2 to remove attached foreign matter.
  • a cleaning nozzle 3 shown in FIG. 1 that discharges a cleaning liquid onto the transparent body 2 discharges the cleaning liquid onto the transparent body 2 to remove attached foreign matter.
  • the imaging device 5 images an object to be imaged outside the vibration device 10 through the transparent body 2 of the vibration device 10.
  • the imaging device 5 includes, for example, an optical element, an image sensor, a sensor component, and the like.
  • FIG. 5 is a block diagram for explaining the configuration of a control device that controls the vibration device according to the first embodiment.
  • the control device 50 includes a processor 20, a piezoelectric drive section 30, an impedance detection section 70, and a power supply circuit 80.
  • the processor 20 is a control unit that processes the imaging signal from the imaging device 5 and supplies a control signal to the piezoelectric drive unit 30.
  • the processor 20 includes a CPU (Central Processing Unit) as a control center, a ROM (Read Only Memory) that stores programs and control data for the CPU to operate, and a RAM (Random Access Memory) that functions as a work area for the CPU. y ), input/output interfaces, etc. are provided to maintain signal integrity with peripheral devices.
  • the processor 20 also includes a microcomputer, an MPU (Micro-Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), and an FPGA (Field Pr. grammable Gate Array) or ASIC (Application Specific Integrated Circuit).
  • MPU Micro-Processing Unit
  • GPU Graphics Processing Unit
  • DSP Digital Signal Processor
  • FPGA Field Pr. grammable Gate Array
  • ASIC Application Specific Integrated Circuit
  • the piezoelectric drive unit 30 generates a drive signal according to the drive voltage and frequency for driving the piezoelectric element 14 based on the control signal from the processor 20.
  • the piezoelectric element 14 is applied with a drive signal generated by the piezoelectric drive unit 30 and vibrates.
  • the vibration of the piezoelectric element 14 causes the vibrating body 12 and the transparent body 2 to vibrate, thereby removing foreign matter.
  • Examples of materials forming the piezoelectric element 14 include barium titanate (BaTiO 3 ), lead zirconate titanate (PZT: PbTiO 3 ⁇ PbZrO 3 ), lead titanate (PbTiO 3 ), and lead metaniobate (PbNb 2 ) .
  • piezoelectric ceramics such as O 6 ), bismuth titanate (Bi 4 Ti 3 O 12 ), and (K,Na)NbO 3 , or appropriate piezoelectric single crystals such as LiTaO 3 and LiNbO 3 can be used.
  • the impedance detection unit 70 monitors the value related to the impedance of the piezoelectric drive unit 30 when the piezoelectric element 14 is vibrated.
  • the value related to impedance is, for example, current, impedance, etc.
  • the power supply circuit 80 outputs an alternating current signal.
  • the effective voltage of the power supply circuit 80 is, for example, 0V or more and 70V or less.
  • the piezoelectric drive section 30 and the impedance detection section 70 can be realized by, for example, an electronic circuit.
  • the functions of the piezoelectric drive section 30 and the impedance detection section 70 may be configured only by hardware, or may be realized by a combination of hardware and software.
  • the piezoelectric drive unit 30 and the impedance detection unit 70 may realize predetermined functions by reading data and programs stored in a storage unit such as a memory and performing various calculation processes.
  • FIG. 6 is an operation mode transition diagram for explaining the operation of the control device that controls the vibration device according to the first embodiment.
  • FIG. 7 is a flowchart for explaining the operation of the control device that controls the vibration device according to the first embodiment.
  • the control device 50 drives the piezoelectric element 14 in a search mode and a drive mode.
  • the piezoelectric element 14 is vibrated in order to determine the resonance frequency fc of the piezoelectric element 14.
  • the piezoelectric element 14 is vibrated to remove foreign matter attached to the surface of the transparent body 2 by vibrating the vibrating body 12 at the resonance frequency fc determined in the search mode.
  • Search mode and drive mode are performed alternately. The detailed steps of the search mode will be explained below.
  • the search mode in the first embodiment includes a first search step and a second search step.
  • the resonance frequency fc of the piezoelectric element 14 is searched for by sweeping the frequency fr of the drive signal between fmin and fmax. Sweeping means changing the frequency fr in stages as time passes. For example, the frequency fr may be increased by ⁇ f every time ⁇ t passes.
  • fmin is the minimum value of the frequency fr of the drive signal
  • fmax is the maximum value of the frequency fr of the drive signal.
  • the second search step is performed when the resonant frequency fc cannot be found in the first search step.
  • the resonance frequency fc is searched for by changing the drive voltage Vpp applied to the piezoelectric element 14.
  • the control device 50 sets the drive voltage Vpp of the drive signal that drives the piezoelectric element 14 to the voltage V1 (step S1), and sets the number of updates Nv of the drive voltage Vpp to 1 (step S2).
  • the drive voltage Vpp is, for example, an alternating current voltage.
  • the effective voltage of the voltage V1 is, for example, 0V or more and 70V or less.
  • the control device 50 sets the frequency fr of the drive signal to the frequency fmin (step S3).
  • the frequency fmin is, for example, 20 kHz or more and 1 MHz or less.
  • control device 50 applies the drive signal having the drive voltage Vpp set in step S1 and the frequency fr set in step S3 to the piezoelectric element 14 (step S4).
  • control device 50 measures the impedance value Z of the piezoelectric element 14 at the frequency fr of the drive signal (step S5).
  • control device 50 determines whether the measured impedance value Z is less than or equal to a predetermined threshold value Zth (step S6).
  • the threshold value Zth is, for example, greater than 0 ⁇ and less than or equal to 1 k ⁇ .
  • FIG. 8 shows the relationship between the resonance frequency fc of the piezoelectric element 14 and the impedance Z when the drive voltage Vpp is constant.
  • the horizontal axis represents frequency [kHz]
  • the vertical axis represents impedance [ ⁇ ].
  • the frequency where the impedance rapidly changes is the resonant frequency fc of the piezoelectric element 14.
  • the measured impedance value Z of the piezoelectric element 14 is equal to or lower than the threshold value Zth.
  • the control device 50 determines the frequency fr of the drive signal as the resonance frequency fc of the piezoelectric element 14 (step S7).
  • the control device 50 operates in a drive mode in which the piezoelectric element 14 is vibrated at the resonance frequency fc to remove foreign matter attached to the transparent body 2 (step S8). Specifically, the control device 50 determines the resonance frequency fc of the piezoelectric element 14 as the driving frequency, and drives the piezoelectric element 14 at the determined driving frequency. In the drive mode, in conjunction with the vibration of the piezoelectric element 14, cleaning liquid may be ejected from the cleaning nozzle 3 shown in FIG. 1 to remove foreign matter attached to the transparent body 2.
  • step S6 If it is determined in step S6 that the measured impedance value Z is not equal to or less than the threshold value Zth, the control device 50 updates the frequency fr of the drive signal to fr+ ⁇ f (step S9).
  • ⁇ f is, for example, 1 Hz or more and 1 kHz or less.
  • control device 50 determines whether the frequency fr of the drive signal exceeds the frequency fmax (step S10).
  • the frequency fmax is, for example, 1 MHz or less.
  • step S10 If it is determined in step S10 that the frequency fr of the drive signal does not exceed the frequency fmax, the process returns to step S4.
  • steps S1 to S10 are the first search steps. If it is determined in step S10 that the frequency fr of the drive signal exceeds the frequency fmax, the following second search step is performed.
  • step S10 If it is determined in step S10 that the frequency fr of the drive signal exceeds the frequency fmax, the control device 50 changes the voltage waveform of the drive voltage Vpp.
  • the voltage waveform of the drive signal applied to the piezoelectric element 14 changes.
  • the effective voltage of the voltage waveform changes.
  • the amplitude of the voltage waveform changes.
  • the amplitude of the voltage waveform increases.
  • the amplitude of the voltage waveform decreases.
  • the drive voltage Vpp is updated to Vpp+ ⁇ V (step S11).
  • ⁇ V may be a positive value or a negative value. That is, the amplitude of the voltage waveform applied to the piezoelectric element 14 increases or decreases.
  • the absolute value of ⁇ V is, for example, greater than 0V and less than or equal to 70V.
  • control device 50 updates the number of updates Nv of the drive voltage Vpp to Nv+1 (step S12).
  • control device 50 determines whether the number of updates Nv updated in step S12 exceeds the maximum number of updates Nvmax (step S13).
  • the maximum number of updates Nvmax may be a predetermined number of times. Nvmax is, for example, 1 to 10 times.
  • step S13 If it is determined in step S13 that the number of updates Nv exceeds Nvmax, the control device 50 detects an error (ERROR) (step S14) and ends the operation in the search mode (step S15).
  • ERPOR error
  • step S13 If it is determined in step S13 that the number of updates Nv does not exceed Nvmax, the process returns to step S3.
  • FIG. 9A shows an example of a change in the resonant frequency fc of the piezoelectric element 14 when the effective voltage is changed in steps of 10 from 10V to 50V.
  • the resonance frequency fc of the piezoelectric element 14 decreases as the effective voltage increases.
  • the horizontal axis represents frequency [kHz]
  • the vertical axis represents impedance [ ⁇ ].
  • the graph shown in FIG. 9B shows how the resonance frequency changes when the effective voltage is changed from Vpp1 to Vpp3.
  • the frequency f1 in FIG. 9B is an example of the frequency fr of the drive signal where fmin ⁇ f1 ⁇ fmax. From the graph of FIG. 9B, when the effective voltages are Vpp1 and Vpp2, the impedance value Z is larger than the threshold value Zth with the drive signal of frequency f1 or frequency f1+ ⁇ f, and the resonant frequency fc cannot be searched.
  • the effective voltage is Vpp3
  • a frequency at which the impedance value Z becomes equal to or less than the threshold value Zth can be searched for using the drive signal of the frequency f1. That is, by changing the drive voltage Vpp by Vpp + ⁇ V in step S11 and further performing the steps after step S3, the resonance frequency fc of the piezoelectric element 14 is made to match the frequency fr of the drive signal, or is made to match the frequency fr of the drive signal. You can get close.
  • the search performance for the resonant frequency fc of the piezoelectric element 14 can be improved. Further, the above control method can improve the resonant frequency search performance without changing the performance of the processor 20, and can reduce manufacturing costs.
  • FIG. 10 is a flowchart for explaining the operation of the control device that controls the vibration device according to this modification.
  • control device 50 sets the frequency fr of the drive signal to f0 (step S101).
  • f0 is, for example, an arbitrary resonance frequency searched in the preceding search mode.
  • control device 50 sets the drive voltage Vpp to V1 (step S102), and sets the number of updates Nv of the drive voltage Vpp to 1 (step S103).
  • control device 50 applies a drive signal having the frequency fr set in step S101 and the drive voltage Vpp set in step S102 to the piezoelectric element 14 (step S104).
  • control device 50 measures the impedance value Z of the piezoelectric element 14 at the frequency fr of the drive signal (step S105).
  • control device 50 determines whether the measured impedance value is less than or equal to a predetermined threshold Zth (step S106).
  • control device 50 determines the frequency fr of the drive signal as the resonance frequency fc of the piezoelectric element 14 (step S107).
  • the control device 50 operates in a drive mode that vibrates the piezoelectric element 14 at the resonance frequency fc to remove foreign matter attached to the transparent body 2 (step S108). Specifically, the control device 50 determines the resonance frequency fc of the piezoelectric element 14 as the driving frequency, and drives the piezoelectric element 14 at the determined driving frequency. In the drive mode, in conjunction with the vibration of the piezoelectric element 14, cleaning liquid may be ejected from the cleaning nozzle 3 shown in FIG. 1 to remove foreign matter attached to the transparent body 2.
  • step S106 If it is determined in step S106 that the impedance value Z exceeds the predetermined threshold Zth, the control device 50 updates the drive voltage Vpp to Vpp+ ⁇ V (step S109).
  • control device 50 updates the number of updates Nv of the drive voltage Vpp to Nv+1 (step S110).
  • control device 50 determines whether the number of updates Nv updated in step S110 exceeds the maximum number of updates Nvmax (step S111).
  • step S111 If it is determined in step S111 that the number of updates Nv exceeds Nvmax, the control device 50 detects an error (ERROR) (step S112) and ends the operation in the search mode (step S113).
  • ERPOR error
  • step S111 If it is determined in step S111 that the number of updates Nv does not exceed Nvmax, the process returns to step S104.
  • the above control method can improve the search performance for the resonant frequency fc of the piezoelectric element 14. Further, the above control method can simplify the control steps and shorten the frequency search time.
  • control device 50 detects the impedance value Z of the piezoelectric element 14, but the control device 50 may detect the current value I of the piezoelectric element 14.
  • the current value is the reciprocal of impedance
  • the control device 50 detects the current value I of the piezoelectric element 14
  • the current value I is measured in step S5 of the above control method, and the current value I is determined to be a predetermined value in step S6. It is determined whether or not it is larger than a threshold value Ith.
  • FIG. 11 shows a flowchart for explaining the operation of the control device that controls the vibration device according to this modification.
  • steps S1 to S4 of the first embodiment shown in FIG. 7 are performed.
  • control device 50 measures the current value I of the piezoelectric element 14 (step S5A).
  • control device 50 determines whether the current value I measured in step S5A is larger than a predetermined threshold value Ith (step S6A).
  • step S6A if it is determined that the current value I is larger than the predetermined threshold value Ith, step S7 and step S8 of the first embodiment shown in FIG. 7 are performed.
  • step S6A If it is determined in step S6A that the current value I is not larger than the predetermined threshold value Ith, step S9 and step S15 of the first embodiment shown in FIG. 7 are performed.
  • the above control method can improve the resonant frequency search performance. Further, in the above control method, the measurement value for determining the resonance frequency fc of the piezoelectric element 14 is the current value I of the piezoelectric element 14, and therefore measurement is easy.
  • Embodiment 2 differs from Embodiment 1 in the method of searching for the resonance number frequency in search mode.
  • the search mode in the second embodiment includes a first search step and a third search step.
  • the first search step differs from the first embodiment in that the frequency fr of the drive signal is swept between fmin and fmax to search for the resonance frequency fc of the piezoelectric element 14.
  • the third search step is performed when the resonance frequency fc of the piezoelectric element 14 cannot be found in the first search step.
  • the third search step searches for the resonant frequency fc of the piezoelectric element 14 by changing the clock widths of some clocks among the plurality of clocks included in the drive signal.
  • the clock width may be changed by changing the duty ratio.
  • FIG. 12 is a flowchart for explaining the operation of the control device that controls the vibration device according to the second embodiment. With reference to FIG. 12, a method of controlling the vibration device according to the second embodiment will be described.
  • control device 50 sets the drive voltage Vpp to Vdr (step S201).
  • the effective voltage of the voltage Vdr is, for example, 0V or more and 70V or less.
  • the control device 50 sets the clock width a of the plurality of clocks included in the drive signal to amin (step S202), and sets the number of updates Nc of the clock width a to 1 (step S203).
  • amin is the minimum value of the clock width a, and is, for example, a preset value. amin is, for example, 1 usec (1 MHz) or more and 50 usec (20 kHz) or less.
  • fr the frequency fr of the drive signal depends on the clock width
  • control device 50 applies a drive signal having the drive voltage Vpp set in step S201 and the frequency fr set in step S202 to the piezoelectric element 14 (step S204).
  • control device 50 measures the impedance value Z of the piezoelectric element 14 at the frequency fr of the drive signal (step S205).
  • the control device 50 determines whether the measured impedance value Z is less than or equal to a predetermined threshold value Zth (step S206).
  • control device 50 determines the frequency fr of the drive signal as the resonance frequency fc of the piezoelectric element 14 (step S207).
  • step S207 the control device 50 operates in a drive mode in which the piezoelectric element 14 is vibrated at the resonance frequency fc determined in step S207 to remove foreign matter attached to the transparent body 2 (step S208).
  • the drive mode in conjunction with the vibration of the piezoelectric element 14, cleaning liquid may be ejected from the cleaning nozzle 3 shown in FIG. 1 to remove foreign matter attached to the transparent body 2.
  • ⁇ a is, for example, 1 Hz or more and 1 kHz or less.
  • control device 50 updates the number of updates Nc of the clock width a to Nc+1 (step S210).
  • control device 50 determines whether the number of updates Nc updated in step S210 exceeds a predetermined threshold Ncth1 (step S211).
  • Ncth1 is, for example, 1 or more times and 10 times or less.
  • step S211 If it is determined in step S211 that the number of updates Nc does not exceed Ncth1, the process returns to step S203.
  • steps S201 to S211 are the first search steps in this embodiment, and when it is determined in step S211 that the number of updates Nc exceeds Ncth1, the frequency fr of the drive signal has reached fmax. . Therefore, in the first search step, the frequency fr of the drive signal is swept from fmin to fmax. That is, in the first search step, the clock width changes from amin to amax. If it is determined in step S211 that the number of updates Nc exceeds Ncth1, the following third search step is performed.
  • step S211 If it is determined in step S211 that the number of updates Nc exceeds Ncth1, the control device 50 changes the clock widths so that the clock widths of some clocks among the plurality of clocks are different from the clock widths of other clocks.
  • Step S212 some clocks are referred to as a plurality of first clocks, and the remaining clocks are referred to as a plurality of second clocks, and the clock width of the plurality of first clocks is maintained at amax, and the clock width of the plurality of second clocks is maintained at amax. Change to a1.
  • the clock width a1 is, for example, a value less than 1 time the clock width amax, preferably a value of 0.5 times or more and less than 1 time, and more preferably a value of 0.99 times or more and less than 1 time. That is, the control device 50 sets the clock widths of some clocks among the plurality of clocks to a value less than 1 times the clock width of other clocks, preferably to a value 0.5 times or more and less than 1 times, and further Preferably, the value is changed to 0.99 times or more and less than 1 times. Further, the width a1 is, for example, amax ⁇ a, and ⁇ a is, for example, the same as ⁇ a in step S209.
  • the width of the plurality of second clocks among the plurality of clocks is less than one time the width of the plurality of first clocks, but the invention is not limited to this.
  • the clock width may be greater than one time the plurality of first clock widths.
  • the plurality of second clock widths are greater than one time and less than or equal to 1.5 times the plurality of first clock widths, preferably greater than one time and less than or equal to 1.01 times.
  • step S212 the control device 50 changes the clock width of 0.1% or more and 99.9% or less of the plurality of clocks included in the drive signal, for example.
  • FIG. 13 shows an example of a plurality of clocks included in a drive signal, the clock width of which has been changed. As shown in FIG. 13, the control device 50 changes the clock width of 1/2 (50%) of the clocks included in the drive signal to the width amax, and changes the clock width of the remaining 1/2 (50%) The clock width of the clock is changed to width a1.
  • step S212 the control device 50 periodically changes the clock widths of the plurality of clocks, for example.
  • some clocks are located periodically in multiple clocks.
  • some clocks are equally spaced among multiple clocks.
  • the control device 50 periodically changes the clock widths of the plurality of clocks so that among the plurality of clocks included in the drive signal, a clock with a width amax and a clock with a width a1 are alternately included. .
  • control device 50 updates the number of updates Nc of the clock width a to Nc+1 (step S213).
  • control device 50 measures the impedance value Z of the piezoelectric element 14 at the frequency fr(a(amax, a1)) of the drive signal (step S214).
  • control device 50 determines whether the impedance value Z measured in step S214 is less than or equal to a predetermined threshold value Zth (step S215).
  • control device 50 determines the frequency fr of the drive signal as the resonance frequency fc of the piezoelectric element 14 (step S216).
  • the control device 50 operates in a drive mode in which the piezoelectric element 14 is vibrated at the resonance frequency fc determined in step S216 to remove foreign matter attached to the transparent body 2 (step S217). Specifically, the control device 50 determines the resonance frequency fc of the piezoelectric element 14 as the driving frequency, and drives the piezoelectric element 14 at the determined driving frequency. In the drive mode, in conjunction with the vibration of the piezoelectric element 14, cleaning liquid may be ejected from the cleaning nozzle 3 shown in FIG. 1 to remove foreign matter attached to the transparent body 2.
  • step S215 If it is determined in step S215 that the measured impedance value Z is not equal to or less than the threshold value Zth, the control device 50 updates the clock width to a ⁇ a of the plurality of clocks included in the drive signal (step S218). As a result, the frequency fr of the drive signal is updated to fr(a ⁇ a). Updating to clock width a ⁇ a means, for example, decreasing both clock width amax and clock width a1 by ⁇ a. ⁇ a is, for example, the same as ⁇ a in step S209.
  • control device 50 updates the number of updates Nc of the clock width a to Nc+1 (step S219).
  • control device 50 determines whether the number of updates Nc updated in step S219 exceeds the threshold value Ncth2 (step S220).
  • Ncth2 is, for example, 1 or more times and 10 times or less.
  • step S220 If it is determined in step S220 that the number of updates Nc does not exceed Ncth2, the process returns to step S214.
  • step S220 If it is determined in step S220 that the number of updates Nc exceeds Ncth2, the control device 50 detects an error (ERROR) and ends the operation in the search mode (step S221).
  • ERPOR error
  • the frequency fr of the drive signal becomes a frequency fr that depends on the two or more clock widths.
  • the frequency fr of the drive signal is expressed by the following equation 1.
  • the drive signal The frequency fr is expressed by the following equation 2.
  • FIG. 14 shows the relationship between the frequency of the drive signal and the resonance frequency in a graph showing the relationship between the resonance frequency and impedance of the piezoelectric element.
  • the horizontal axis represents frequency [kHz] and the vertical axis represents impedance [ ⁇ ].
  • the resonance frequency fc of the piezoelectric element 14 exists between f(amax) and f(amax ⁇ a).
  • the frequency fr of the drive signal is f(amax) or f(amax ⁇ a)
  • the measured impedance Z is larger than the threshold value Zth. Therefore, it cannot be searched in the first search step.
  • Equation 2 by performing the third search step, the frequency fr(a(amax, amax- ⁇ a)) with a value between fr(amax) and fr(amax- ⁇ a) can be found.
  • a driving signal having the following characteristics can be emitted. Thereby, it is possible to search for the resonance frequency fc existing between fr(amax) and fr(amax- ⁇ a), which could not be searched in the first search step.
  • the frequency resolution can be improved regardless of the performance of the processor 20.
  • the drive frequency of the piezoelectric element 14 can be appropriately controlled. Specifically, since the search performance for the resonance frequency fc of the piezoelectric element 14 can be improved, the drive frequency of the piezoelectric element 14 can be determined appropriately. Furthermore, since it is not necessary to use the expensive processor 20, an increase in manufacturing costs can be suppressed.
  • FIG. 15 is a flowchart for explaining the operation of the control device that controls the vibration device according to this modification.
  • control device 50 sets the drive voltage Vpp to Vdr (step S301).
  • the control device 50 sets clock widths such that the clock widths of some of the plurality of clocks are different from the clock widths of other clocks (step S302).
  • the clock width of 50% of the clocks included in the drive signal is set to the width amax
  • the clock width of the remaining 50% of the clocks is set to the width a1.
  • the width a1 is, for example, amax ⁇ a
  • ⁇ a is, for example, the same as ⁇ a in step S209 of the second embodiment.
  • the frequency fr of the drive signal is set to fr(a(amax, a1)).
  • step S302 the method in which the control device 50 makes the clock widths of some clocks different from the clock widths of other clocks among the plurality of clocks is the method of changing the clock width in step S212 of the second embodiment. A similar method can be adopted.
  • control device 50 sets the number of updates Nc of the clock width a to 1 (step S303).
  • control device 50 applies a drive signal having the drive voltage Vpp set in step S301 and the frequency fr(a(amax, a1)) set in step S302 to the piezoelectric element 14 (step S304).
  • control device 50 measures the impedance value Z of the piezoelectric element 14 at the frequency fr(a(amax, a1)) of the drive signal (step S305).
  • control device 50 determines whether the impedance value Z measured in step S305 is less than or equal to a predetermined threshold value Zth (step S306).
  • the control device 50 determines the frequency fr of the drive signal to be the resonance frequency fc of the piezoelectric element 14 (step S307).
  • the control device 50 operates in a drive mode in which the piezoelectric element 14 is vibrated at the resonance frequency fc determined in step S407 to remove foreign matter attached to the transparent body 2 (step S308).
  • the cleaning liquid may be ejected from the cleaning nozzle 3 in conjunction with the vibration of the piezoelectric element 14 to remove foreign matter attached to the transparent body 2 .
  • step S306 If it is determined in step S306 that the measured impedance value Z is not equal to or less than the threshold value Zth, the control device 50 updates the clock width a ⁇ a of the plurality of clocks included in the drive signal (step S309). As a result, the frequency fr of the drive signal is updated to fr(a ⁇ a). Updating to clock width a ⁇ a means, for example, decreasing both clock width amax and clock width a1 by ⁇ a. ⁇ a is, for example, the same as ⁇ a in step S209 of the second embodiment.
  • control device 50 updates the number of updates Nc of the clock width a to Nc+1 (step S310).
  • control device 50 determines whether the number of updates Nc updated in step S410 exceeds zNcmax (step S311).
  • the maximum number of updates Ncmax may be a preset number of updates. Ncmax is, for example, 1 or more times and 10 times or less.
  • step S311 If it is determined in step S311 that the number of updates Nc does not exceed Ncmax, the process returns to step S305.
  • step S311 If it is determined in step S311 that the number of updates Nc exceeds Ncmax, the control device 50 detects an error (ERROR) (step S312) and ends the operation in the search mode (step S313).
  • ERPOR error
  • the above control method can improve the search performance for the resonant frequency fc of the piezoelectric element 14. Moreover, the above control method can simplify control and shorten frequency search time.
  • step S212 the control device 50 maintains the clock width of 1/2 (50%) of the plurality of clocks included in the drive signal at the width amax, and maintains the clock width of the remaining 1/2 (50%) clocks at the width amax.
  • the clock width of the /2 (50%) clock is changed to width a1.
  • the method by which the processor 20 changes the clock widths such that the clock widths of some of the plurality of clocks are different from the clock widths of the other clocks is not limited to this.
  • the control device 50 maintains the clock width of 2/3 of the clocks included in the drive signal at the width amax, and maintains the clock width of the remaining 1/3 of the clocks at the width amax. It may be changed to a1.
  • a clock having a clock width a1 is issued, for example, once every three times.
  • the frequency fr of the drive signal is expressed by the following equation 3.
  • a drive signal that includes clocks with a width amax at a ratio of 2/3 and clocks with a clock width a1 at a ratio of 1/3, and a drive signal that includes clocks with a width amax and clocks with a width a1 at the same ratio.
  • a drive signal having a frequency fr different from that of the drive signal can be generated.
  • control device 50 determines the resonant frequency of the piezoelectric element 14 and uses the determined resonant frequency as the drive frequency for driving the piezoelectric element 14, but the control device 50 is not limited to this.
  • the control device 50 may determine the drive frequency based on a change in the value related to the impedance of the piezoelectric element 14 without determining the resonance frequency of the piezoelectric element 14.
  • the control method for controlling a vibration device and the control device for a vibration device according to the present disclosure can be applied to a vibration device used in a vehicle-mounted camera used outdoors, a surveillance camera, or a light sensor such as LiDAR.
  • Housing 2 Transparent body 3 Cleaning nozzle 5 Imaging device 10 Vibrating device 12 Vibrating body 13 Retainer 14 Piezoelectric element 15 Wiring 20 Processor 30 Piezoelectric drive section 50 Control device 70 Impedance detection section 80 Power supply circuit 100 Imaging unit

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  • Apparatuses For Generation Of Mechanical Vibrations (AREA)

Abstract

La présente invention concerne un procédé qui est un procédé pour commander un dispositif de vibration comprenant un élément piézoélectrique par un dispositif de commande, le procédé comprenant : une étape consistant à modifier une forme d'onde de tension appliquée à l'élément piézoélectrique ; une étape consistant à mesurer une valeur concernant une impédance de l'élément piézoélectrique ; et une étape consistant à déterminer une fréquence d'entraînement pour entraîner l'élément piézoélectrique sur la base de la valeur mesurée concernant l'impédance de l'élément piézoélectrique.
PCT/JP2022/042060 2022-03-31 2022-11-11 Dispositif de commande pour commander un dispositif de vibration et procédé de commande de dispositif de vibration WO2023188516A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003174784A (ja) * 2001-12-06 2003-06-20 Asmo Co Ltd 超音波モータの制御装置、及び超音波モータの制御方法
WO2020217600A1 (fr) * 2019-04-26 2020-10-29 株式会社村田製作所 Dispositif de nettoyage, unité d'imagerie à dispositif de nettoyage, et procédé de nettoyage
JP2021100308A (ja) * 2019-12-20 2021-07-01 セイコーエプソン株式会社 圧電駆動装置の制御方法、圧電駆動装置、および、ロボット

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003174784A (ja) * 2001-12-06 2003-06-20 Asmo Co Ltd 超音波モータの制御装置、及び超音波モータの制御方法
WO2020217600A1 (fr) * 2019-04-26 2020-10-29 株式会社村田製作所 Dispositif de nettoyage, unité d'imagerie à dispositif de nettoyage, et procédé de nettoyage
JP2021100308A (ja) * 2019-12-20 2021-07-01 セイコーエプソン株式会社 圧電駆動装置の制御方法、圧電駆動装置、および、ロボット

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