WO2023188516A1 - Control device for controlling vibration device and method for controlling vibration device - Google Patents

Control device for controlling vibration device and method for controlling vibration device 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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French (fr)
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/en

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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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Abstract

A method according to the present disclosure is a method for controlling a vibration device including a piezoelectric element by a control device, the method including: a step for changing a waveform of voltage applied to the piezoelectric element; a step for measuring a value regarding an impedance of the piezoelectric element; and a step for determining a driving frequency for driving the piezoelectric element on the basis of the measured value regarding the impedance of the piezoelectric element.

Description

振動装置を制御する制御装置及び振動装置を制御する方法Control device for controlling a vibration device and method for controlling a vibration device
　本開示は、振動装置を制御する制御装置及び振動装置を制御する方法に関する。 The present disclosure relates to a control device for controlling a vibration device and a method for controlling the vibration device.
　振動装置等に設けられた圧電素子の共振周波数は、様々な要因によって変化する。特許文献１には、周囲温度等の変動によって、圧電素子の共振周波数特性が変動したとしても、圧電素子に流れる交流電流が略一定になるように制御駆動する圧電モーター駆動回路が開示されている。 The resonant frequency of a piezoelectric element provided in a vibrating device etc. changes depending on various factors. 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. .
特開平８－１２６３５７号公報Japanese Patent Application Publication No. 8-126357
　近年、圧電素子を備える振動装置において、圧電素子を駆動する駆動周波数を適切に制御することが求められている。 In recent years, in vibrating devices equipped with piezoelectric elements, it has been required to appropriately control the driving frequency for driving the piezoelectric elements.
　そこで、本開示は、圧電素子を駆動する駆動周波数を適切に制御することができる振動装置を制御する制御装置及び振動装置を制御する方法を提供することを目的とする。 Therefore, 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.
　本開示に係る一態様の方法は、
　圧電素子を備えた振動装置を制御装置によって制御する方法であって、
　前記圧電素子に印加する電圧波形を変化させるステップと、
　前記圧電素子のインピーダンスに関する値を測定するステップと、
　測定された前記圧電素子の前記インピーダンスに関する値に基づいて、前記圧電素子を駆動する駆動周波数を決定するステップと、
を含む。 A method according to one aspect of the present disclosure 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.
　本開示に係る一態様の制御装置は、
　圧電素子を備える振動装置を制御する制御装置であって、
　前記圧電素子を駆動するための駆動信号を送信するプロセッサと、
　前記プロセッサにより実行される命令を記憶したメモリと、
を備え、
　前記命令は、
　　前記圧電素子に印加する電圧波形を変化させるステップと、
　　前記圧電素子のインピーダンスに関する値を測定するステップと、
　　測定された前記圧電素子の前記インピーダンスに関する値に基づいて、前記圧電素子を駆動する駆動周波数を決定するステップと、
を含む。 A control device according to one aspect of the present disclosure 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.
　本開示に係る振動装置の制御装置及び振動装置の制御方法によれば、圧電素子を駆動する駆動周波数を適切に制御することができる。 According to the vibration device control device and vibration device control method according to the present disclosure, it is possible to appropriately control the drive frequency for driving the piezoelectric element.
実施の形態１に係る撮像ユニットの構成を説明するための斜視図である。1 is a perspective view for explaining the configuration of an imaging unit according to Embodiment 1. FIG. 実施の形態１に係る撮像ユニットの断面構成を示す概略断面図である。1 is a schematic cross-sectional view showing a cross-sectional configuration of an imaging unit according to Embodiment 1. FIG. 実施の形態１に係る振動装置の断面構成を示す概略断面図である。1 is a schematic cross-sectional view showing a cross-sectional configuration of a vibrating device according to Embodiment 1. FIG. 実施の形態１に係る振動装置の各構成部材を示す分解斜視図である。FIG. 2 is an exploded perspective view showing each component of the vibration device according to the first embodiment. 実施の形態１に係る振動装置を制御する制御装置の構成を説明するためのブロック図である。FIG. 2 is a block diagram for explaining the configuration of a control device that controls the vibration device according to the first embodiment. 実施の形態１に係る振動装置を制御する制御装置の動作を説明するための動作モードの遷移図である。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. 実施の形態１に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。3 is a flowchart for explaining the operation of the control device that controls the vibration device according to the first embodiment. 実効電圧が一定のときの圧電素子の共振周波数とインピーダンスとの関係を示す。The relationship between the resonant frequency and impedance of a piezoelectric element when the effective voltage is constant is shown. 実効電圧が変化したときの圧電素子の共振周波数とインピーダンスとの関係を示す。The relationship between the resonant frequency and impedance of a piezoelectric element when the effective voltage changes is shown. 実効電圧が変化したときの圧電素子の共振周波数とインピーダンスとの関係を示す。The relationship between the resonant frequency and impedance of a piezoelectric element when the effective voltage changes is shown. 実施の形態１の変形例１に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。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. 実施の形態１の変形例２に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。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. 実施の形態２に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。7 is a flowchart for explaining the operation of the control device that controls the vibration device according to the second embodiment. 実施の形態２に係る振動装置を制御装置によって制御する方法において、クロック幅が変更された、駆動信号に含まれる複数のクロックの一例を示す。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. 圧電素子の共振周波数とインピーダンスとの関係を示すグラフにおける、駆動信号の周波数と共振周波数との関係を示す。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. 実施の形態２の変形例１に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。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. 実施の形態２の変形例２に係る振動装置を制御装置によって制御する方法において、クロック幅が変更された、駆動信号に含まれる複数のクロックの一例を示す。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.
（本開示に至った経緯）
　車両の前部や後部に撮像ユニットを設けて、当該撮像ユニットで撮像した画像を利用して安全装置を制御したり、自動運転制御を行ったりしている。このような撮像ユニットは、車外に設けられることが多いため、外部を覆うレンズや保護ガラスなどの透光体に雨滴、泥、塵埃等の異物が付着することがある。透光体に異物が付着すると、当該撮像ユニットで撮像した画像に付着した異物が映り込み、鮮明な画像が得られなくなる。 (The circumstances that led to this disclosure)
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.
　そこで、透光体を振動させて異物を除去する振動装置が開発されている。このような振動装置は、例えば、圧電素子を利用して透光体を振動させているが、圧電素子の共振周波数は、圧電素子が発する熱や、透光体に付着した異物等、様々な要因によって変化する。このため、圧電素子を駆動する駆動周波数を適切に制御しないと、透光体を効率良く振動させることができない。 Therefore, a vibration device has been developed 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.
　例えば、圧電素子を駆動する駆動周波数を制御するために、圧電素子の共振周波数を探索する制御装置が開発されている。圧電素子の共振周波数の探索性能が高くなるほど、圧電素子の駆動周波数を適切に制御することができる。例えば、共振周波数の探索性能を向上させる方法の１つとして、制御装置のプロセッサの性能を高くする方法が考えられる。しかしながら、制御装置のプロセッサの性能を高くすると、製造コストが高くなることや、プロセッサの実装面積が大きくなるという問題がある。 For example, in order to control the drive frequency for driving the piezoelectric element, a control device has been developed that searches for the resonance frequency of the piezoelectric element. The higher the resonant frequency search performance of the piezoelectric element, the more appropriately the drive frequency of the piezoelectric element can be controlled. For example, one possible method for improving the resonant frequency search performance is to increase the performance of the processor of the control device. However, increasing the performance of the processor in the control device causes problems such as increased manufacturing cost and increased mounting area of the processor.
　そこで、本発明者は、これらの課題を解決するために鋭意検討し、本開示に至った。 Therefore, the present inventor conducted extensive studies to solve these problems, and came up with the present disclosure.
　本開示に係る一態様の方法は、
　圧電素子を備えた振動装置を制御装置によって制御する方法であって、
　前記圧電素子に印加する電圧波形を変化させるステップと、
　前記圧電素子のインピーダンスに関する値を測定するステップと、
　測定された前記圧電素子の前記インピーダンスに関する値に基づいて、前記圧電素子を駆動する駆動周波数を決定するステップと、
を含む。 A method according to one aspect of the present disclosure 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.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。また、製造コストを抑えることができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled. Furthermore, manufacturing costs can be reduced.
　前記方法において、前記電圧波形を変化させるステップが、前記電圧波形の実効電圧を変化させることを有してもよい。 In the method, the step of changing the voltage waveform may include changing an effective voltage of the voltage waveform.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　前記方法において、前記電圧波形を変化させるステップが、前記電圧波形の振幅を変化させること、を有してもよい。 In the method, the step of changing the voltage waveform may include changing the amplitude of the voltage waveform.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　前記方法において、前記電圧波形を変化させるステップが、前記電圧波形の振幅を増加させることを有してもよい。 In the method, the step of changing the voltage waveform may include increasing the amplitude of the voltage waveform.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　前記方法において、前記電圧波形を変化させるステップが、前記電圧波形の振幅を減少させることを有してもよい。 In the method, the step of changing the voltage waveform may include decreasing the amplitude of the voltage waveform.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　前記方法は、前記圧電素子を駆動する駆動信号の周波数を変化させるステップ、を更に含み、
　前記インピーダンスに関する値を測定するステップは、前記周波数が変化している間、前記インピーダンスに関する値を測定すること、を有してもよい。 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.
　このような構成により、圧電素子を駆動する駆動周波数をより適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be controlled more appropriately.
　前記方法において、前記駆動周波数を決定するステップにおいて、前記周波数が変化している間に測定した前記インピーダンスに関する値に基づいて前記駆動周波数を決定できなかった場合、前記電圧波形を変化させるステップが実行されてもよい。 In the method, in the step of determining the driving frequency, if the driving 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 done.
　このような構成により、圧電素子を駆動する駆動周波数をより適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be controlled more appropriately.
　前記方法において、前記インピーダンスに関する値は、インピーダンス値であり、
　前記駆動周波数を決定するステップは、
　　前記インピーダンスに関する値が所定の閾値以下であるか否か判定することと、
　　前記インピーダンスに関する値が所定の閾値以下であると判定したときの前記圧電素子を駆動する駆動信号の周波数を前記駆動周波数として決定することと、
を有してもよい。 In the method, 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.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　本開示に係る一態様の制御装置は、
　圧電素子を備える振動装置を制御する制御装置であって、
　前記圧電素子を駆動するための駆動信号を送信するプロセッサと、
　前記プロセッサにより実行される命令を記憶したメモリと、
を備え、　前記命令は、
　　前記圧電素子に印加する電圧波形を変化させるステップと、
　　前記圧電素子のインピーダンスに関する値を測定するステップと、
　　測定された前記圧電素子の前記インピーダンスに関する値に基づいて、前記圧電素子を駆動する駆動周波数を決定するステップと、を含む。 A control device according to one aspect of the present disclosure 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.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。また、製造コストを抑えることができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled. Furthermore, manufacturing costs can be reduced.
　前記制御装置において、前記電圧波形を変化させるステップが、前記電圧波形の実効電圧を変化させてもよい。 In the control device, the step of changing the voltage waveform may change an effective voltage of the voltage waveform.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　前記制御装置において、前記電圧波形を変化させるステップが、前記電圧波形の振幅を変化させてもよい。 In the control device, the step of changing the voltage waveform may change the amplitude of the voltage waveform.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　前記制御装置において、前記電圧波形を変化させるステップが、前記電圧波形の振幅を増加させてもよい。 In the control device, the step of changing the voltage waveform may increase the amplitude of the voltage waveform.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　前記制御装置において、前記電圧波形を変化させるステップが、前記電圧波形の振幅を減少させてもよい。 In the control device, the step of changing the voltage waveform may reduce the amplitude of the voltage waveform.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　前記制御装置において、前記命令は、前記駆動信号の周波数を変化させるステップ、を更に含み、
　前記インピーダンスに関する値を測定するステップは、前記周波数が変化している間、前記インピーダンスに関する値を測定すること、を有してもよい。 In the control device, 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.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　　前記制御装置において、前記駆動周波数を決定するステップにおいて、前記周波数が変化している間に測定した前記インピーダンスに関する値に基づいて前記駆動周波数を決定できなかった場合、前記電圧波形を変化させるステップが実行されてもよい。 In the control device, in 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.
　このような構成により、圧電素子を駆動する駆動周波数をより適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be controlled more appropriately.
　　前記制御装置において、前記インピーダンスに関する値は、インピーダンス値であり、
　前記駆動周波数を決定するステップは、
　　前記インピーダンスに関する値が所定の閾値以下であるか否か判定することと、
　　前記インピーダンスに関する値が所定の閾値以下であると判定したときの前記駆動信号の周波数を前記駆動周波数として決定することと、
を有してもよい。 In the control device, 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.
　このような構成により、圧電素子を駆動する駆動周波数を適切に制御することができる。 With such a configuration, the drive frequency for driving the piezoelectric element can be appropriately controlled.
　以下、本開示の実施の形態について、添付の図面を参照しながら説明する。また、各図においては、説明を容易なものとするため、各要素を誇張して示している。 Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, in each figure, each element is exaggerated for ease of explanation.
　本明細書において、「第１」、「第２」などの用語は、説明のためだけに用いられるものであり、相対的な重要性または技術的特徴の順位を明示または暗示するものとして理解されるべきではない。「第１」と「第２」と限定されている特徴は、１つまたはさらに多くの当該特徴を含むことを明示または暗示するものである。 As used herein, terms such as "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.
（実施の形態１）
＜振動装置の全体構造＞
　以下に、本実施の形態１に係る振動装置を備える撮像ユニットについて図面を参照しながら説明する。図１は、実施の形態１に係る撮像ユニットの構成を説明するための斜視図である。図２は、実施の形態１に係る撮像ユニットの断面構成を示す概略断面図である。図３は、実施の形態１に係る振動装置の断面構成を示す概略断面図である。図４は、実施の形態１に係る振動装置の各構成部材を示す分解斜視図である。 (Embodiment 1)
<Overall structure of the vibration device>
An imaging unit including a vibration device according to the first embodiment will be described below with reference to the drawings. 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.
　図１及び図２に示すように、撮像ユニット１００は、筐体１と、振動装置１０と、撮像装置５と、を備える。 As shown in FIGS. 1 and 2, the imaging unit 100 includes a housing 1, a vibration device 10, and an imaging device 5.
　図１及び図２に示すように、筐体１は、撮像装置５を内包する。筐体１は、振動装置１０の一部を露出させる。筐体１の材料は、例えば樹脂である。 As shown in FIGS. 1 and 2, 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.
　図３及び図４に示すように、振動装置１０は、透光体２と、透光体２を振動させる振動体１２と、透光体２の外周縁で支持するリテーナー１３と、を備える。図１に示すように、振動装置１０において、透光体２、リテーナー１３及び振動体１２の一部は、筐体１に設けられた孔から露出している。振動装置１０は、透光体２を振動させることにより、透光体２に付着した異物を除去する。 As shown in FIGS. 3 and 4, 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 .
　透光体２は、撮像装置５の前面に配置される。振動装置１０は、透光体２に付着した異物を除去する。透光体２は、撮像装置５が検出する波長のエネルギー線又は光が透過する透光性を有する。また、透光体２は、集光性を有するレンズであってもよい。 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. Moreover, the light-transmitting body 2 may be a lens having light-condensing properties.
　振動体１２は、透光体２を振動させて付着した異物を除去する。図４に示すように、振動体１２は、筒形状を有する。振動体１２には、例えば、透光体２と接する面の反対側の面に中空円状、即ち、環状の圧電素子１４が設けられている。さらに、圧電素子１４においては、振動体１２と接する面の反対側の面に中空円状、即ち環状の電極を有する配線１５が設けられている。当該配線１５に電圧を印加して圧電素子１４を筒状体の振動体１２の貫通方向に振動させることにより、振動体１２を介して透光体２を振動体１２の貫通方向に振動させることができる。 The vibrating body 12 vibrates the transparent body 2 to remove attached foreign matter. As shown in FIG. 4, 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. Furthermore, in the 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. By applying a voltage to the wiring 15 and vibrating the piezoelectric element 14 in the penetrating direction of the cylindrical vibrating body 12, the transparent body 2 can be vibrated in the penetrating direction of the vibrating body 12 via the vibrating body 12. I can do it.
　なお、振動体１２に設ける圧電素子１４の位置は、図３に示す位置に限定されるものではない。 Note that the position of the piezoelectric element 14 provided on the vibrating body 12 is not limited to the position shown in FIG. 3.
　リテーナー１３は、振動体１２と接続されている。リテーナー１３と振動体１２とはそれぞれねじ切り加工がされており、リテーナー１３と振動体１２とはそれぞれのねじ切り加工部分が嵌合して接続されている。リテーナー１３の材料は、例えば、ステンレス、アルミニウム、鉄、チタン、ジュラルミン等の金属だけでなく、プラスチックであってもよい。 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.
　振動装置１０はさらに、透光体２に洗浄液（洗浄体）を吐出して付着した異物を除去する構成をさらに有していてもよい。例えば、図１に示す、透光体２に洗浄液を吐出する洗浄ノズル３は、透光体２に洗浄液を吐出して付着した異物を除去する。 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. For example, 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.
　撮像装置５は、振動装置１０の透光体２を通して、振動装置１０の外部の撮像対象物の撮像を行う。撮像装置５は、例えば、光学素子、撮像素子、センサ部品等を内蔵する。 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.
　次に、振動装置１０を制御する制御装置５０の構成について図を用いて説明する。図５は、本実施の形態１に係る振動装置を制御する制御装置の構成を説明するためのブロック図である。 Next, the configuration of the control device 50 that controls the vibration device 10 will be explained using the drawings. FIG. 5 is a block diagram for explaining the configuration of a control device that controls the vibration device according to the first embodiment.
　制御装置５０は、プロセッサ２０、圧電駆動部３０、インピーダンス検出部７０、および電源回路８０を含んでいる。プロセッサ２０は、撮像装置５からの撮像信号を処理するとともに、圧電駆動部３０に対して制御信号を供給する制御部である。 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.
　プロセッサ２０は、制御中枢としてのＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）、ＣＰＵが動作するためのプログラムや制御データ等を記憶しているＲＯＭ（Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）、ＣＰＵのワークエリアとして機能するＲＡＭ（Ｒａｎｄｏｍ　Ａｃｃｅｓｓ　Ｍｅｍｏｒｙ）、周辺機器との信号の整合性を保つための入出力インターフェイス等を設けてある。プロセッサ２０はまた、マイコン、ＭＰＵ（Ｍｉｃｒｏ－Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）、ＧＰＵ（Ｇｒａｐｈｉｃｓ　Ｐｒｏｃｅｓｓｏｎｇ　Ｕｎｉｔ）、ＤＳＰ（Ｄｉｇｉｔａｌ　Ｓｉｇｎａｌ　Ｐｒｏｃｅｓｓｏｒ）、ＦＰＧＡ（Ｆｉｅｌｄ　Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｔｅ　Ａｒｒａｙ）、ＡＳＩＣ（Ａｐｐｌｉｃａｔｉｏｎ　Ｓｐｅｃｉｆｉｃ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）であってもよい。 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).
　圧電駆動部３０は、プロセッサ２０からの制御信号により、圧電素子１４を駆動する駆動電圧、周波数に応じた駆動信号を生成する。 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.
　圧電素子１４は、圧電駆動部３０によって生成された駆動信号が印加され振動する。圧電素子１４の振動により、振動体１２および透光体２が振動し異物が除去される。圧電素子１４を形成する材料としては、例えば、チタン酸バリウム（ＢａＴｉＯ３）、チタン酸・ジルコン酸鉛（ＰＺＴ：ＰｂＴｉＯ３・ＰｂＺｒＯ３）、チタン酸鉛（ＰｂＴｉＯ３）、メタニオブ酸鉛（ＰｂＮｂ２Ｏ６）、チタン酸ビスマス（Ｂｉ４Ｔｉ３Ｏ１２）、（Ｋ，Ｎａ）ＮｂＯ３などの適宜の圧電セラミックス、またはＬｉＴａＯ３、ＬｉＮｂＯ３などの適宜の圧電単結晶などを用いることができる。 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 ) . Appropriate 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.
　インピーダンス検出部７０は、圧電素子１４を振動させている場合に、圧電駆動部３０のインピーダンスに関する値をモニタしている。インピーダンスに関する値とは、例えば、電流、インピーダンス等である。 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.
　電源回路８０は、交流電流の信号を出力する。電源回路８０の実効電圧は、例えば、０Ｖ以上７０Ｖ以下である。 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.
　圧電駆動部３０及びインピーダンス検出部７０は、例えば、電子回路で実現可能である。圧電駆動部３０及びインピーダンス検出部７０の機能は、ハードウェアのみで構成してもよいし、ハードウェアとソフトウェアとを組み合わせることにより実現してもよい。圧電駆動部３０及びインピーダンス検出部７０は、メモリなどの記憶部に格納されたデータやプログラムを読み出して種々の演算処理を行うことで、所定の機能を実現してもよい。 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.
　次に、制御装置５０の動作について遷移図およびフローチャートに基づいて説明する。図６は、実施の形態１に係る振動装置を制御する制御装置の動作を説明するための動作モードの遷移図である。図７は、実施の形態１に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。 Next, the operation of the control device 50 will be explained based on a transition diagram and a flowchart. 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.
　図６に示すように、制御装置５０は、サーチモードと駆動モードとで圧電素子１４を駆動する。サーチモードは、圧電素子１４の共振周波数ｆｃを決定するために圧電素子１４を振動させる。駆動モードは、サーチモードで決定した共振周波数ｆｃで振動体１２を振動させて透光体２の表面に付着した異物を除去するために圧電素子１４を振動させる。サーチモードと駆動モードとは交互に実施される。以下に、サーチモードの詳細なステップを説明する。 As shown in FIG. 6, the control device 50 drives the piezoelectric element 14 in a search mode and a drive mode. In the search mode, the piezoelectric element 14 is vibrated in order to determine the resonance frequency fc of the piezoelectric element 14. In the drive mode, 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.
　実施の形態１におけるサーチモードは、第１サーチステップと第２サーチステップとを含む。第１サーチステップは、駆動信号の周波数ｆｒをｆｍｉｎからｆｍａｘの間でスイープさせて圧電素子１４の共振周波数ｆｃを探索する。スイープとは、時間経過に伴い、周波数ｆｒを段階的に変化させることである。例えば、時間Δｔ経過毎に周波数ｆｒをΔｆ増加させることである。また、ｆｍｉｎは、駆動信号の周波数ｆｒの最小値であり、ｆｍａｘは、駆動信号の周波数ｆｒの最大値である。第２サーチステップは、第１サーチステップで共振周波数ｆｃを探索できなかった場合に実施される。第２サーチステップは、圧電素子１４に印加する駆動電圧Ｖｐｐを変化させることで共振周波数ｆｃを探索する。 The search mode in the first embodiment includes a first search step and a second search step. In the first 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 Δf every time Δt passes. Furthermore, fmin is the minimum value of the frequency fr of the drive signal, and 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. In the second search step, the resonance frequency fc is searched for by changing the drive voltage Vpp applied to the piezoelectric element 14.
　まず、制御装置５０は、圧電素子１４を駆動する駆動信号の駆動電圧Ｖｐｐを電圧Ｖ１に設定し（ステップＳ１）、駆動電圧Ｖｐｐの更新回数Ｎｖを１に設定する（ステップＳ２）。駆動電圧Ｖｐｐは、例えば交流電圧である。電圧Ｖ１の実効電圧は、例えば、０Ｖ以上７０Ｖ以下である。 First, 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.
　次に、制御装置５０は、駆動信号の周波数ｆｒを周波数ｆｍｉｎに設定する（ステップＳ３）。周波数ｆｍｉｎは、例えば、２０ｋＨｚ以上１ＭＨｚ以下である。 Next, 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.
　次に、制御装置５０は、ステップＳ１で設定した駆動電圧Ｖｐｐ、及びステップＳ３で設定した周波数ｆｒの駆動信号を圧電素子１４に印加する（ステップＳ４）。 Next, the 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).
　次に、制御装置５０は、駆動信号の周波数ｆｒにおける圧電素子１４のインピーダンス値Ｚを測定する（ステップＳ５）。 Next, the control device 50 measures the impedance value Z of the piezoelectric element 14 at the frequency fr of the drive signal (step S5).
　次に、制御装置５０は、測定したインピーダンス値Ｚが所定の閾値Ｚｔｈ以下であるか否か判定する（ステップＳ６）。閾値Ｚｔｈは、例えば、０Ωより大きく、１ｋΩ以下である。 Next, the 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 0Ω and less than or equal to 1 kΩ.
　ここで、図８を参照して、圧電素子１４のインピーダンスと共振周波数との関係を説明する。図８は、駆動電圧Ｖｐｐが一定のときの圧電素子１４の共振周波数ｆｃとインピーダンスＺとの関係を示す。図８では、横軸を周波数［ｋＨｚ］、縦軸をインピーダンス［Ω］としている。図８に示すグラフでは、インピーダンスが急激に変化している箇所の周波数が圧電素子１４の共振周波数ｆｃである。そのため、駆動信号の周波数ｆｒが圧電素子１４の共振周波数ｆｃと一致、又は圧電素子１４の共振周波数ｆｃに近いとき、測定される圧電素子１４のインピーダンス値Ｚは、閾値Ｚｔｈ以下である。 Here, with reference to FIG. 8, the relationship between the impedance of the piezoelectric element 14 and the resonant frequency will be explained. 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. In FIG. 8, the horizontal axis represents frequency [kHz], and the vertical axis represents impedance [Ω]. In the graph shown in FIG. 8, the frequency where the impedance rapidly changes is the resonant frequency fc of the piezoelectric element 14. Therefore, when the frequency fr of the drive signal matches the resonant frequency fc of the piezoelectric element 14 or is close to 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.
　従って、ステップＳ５で測定したインピーダンス値Ｚが閾値Ｚｔｈ以下であると判定した場合、制御装置５０は、駆動信号の周波数ｆｒを圧電素子１４の共振周波数ｆｃとして決定する（ステップＳ７）。 Therefore, if it is determined that the impedance value Z measured in step S5 is equal to or less 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).
　ステップＳ５の次に、制御装置５０は、共振周波数ｆｃで圧電素子１４を振動させて透光体２に付着した異物を除去する駆動モードで動作する（ステップＳ８）。具体的には、制御装置５０は、圧電素子１４の共振周波数ｆｃを駆動周波数として決定し、決定した駆動周波数で圧電素子１４を駆動する。駆動モードでは、圧電素子１４の振動とあわせて、図１に示す洗浄ノズル３から洗浄液を吐出して透光体２に付着した異物を除去してもよい。 After step S5, 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.
　ステップＳ６において、測定したインピーダンス値Ｚが閾値Ｚｔｈ以下でないと判定した場合、制御装置５０は、駆動信号の周波数ｆｒをｆｒ＋Δｆに更新する（ステップＳ９）。Δｆは、例えば、１Ｈｚ以上１ｋＨｚ以下である。 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+Δf (step S9). Δf is, for example, 1 Hz or more and 1 kHz or less.
　次に、制御装置５０は、駆動信号の周波数ｆｒが周波数ｆｍａｘを超えているか否かを判定する（ステップＳ１０）。周波数ｆｍａｘは、例えば、１ＭＨｚ以下である。 Next, the 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.
　ステップＳ１０で、駆動信号の周波数ｆｒが周波数ｆｍａｘを超えていないと判定した場合、ステップＳ４に戻る。 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.
　上記のステップＳ１からステップＳ１０までが第１サーチステップである。ステップＳ１０で、駆動信号の周波数ｆｒが周波数ｆｍａｘを超えていると判定した場合、以下の第２サーチステップが実施される。 The above 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.
　ステップＳ１０で、駆動信号の周波数ｆｒが周波数ｆｍａｘを超えていると判定した場合、制御装置５０は、駆動電圧Ｖｐｐの電圧波形を変化させる。これにより、圧電素子１４に印加する駆動信号の電圧波形が変化する。例えば、電圧波形の実効電圧が変化する。例えば、電圧波形の振幅が変化する。また、例えば、電圧波形の振幅が増加する。また、例えば、電圧波形の振幅が減少する。具体的には、駆動電圧ＶｐｐをＶｐｐ＋ΔＶに更新する（ステップＳ１１）。ΔＶは、正の値であってもよいし、負の値であってもよい。すなわち、圧電素子１４に印加する電圧波形の振幅が増加、又は減少する。ΔＶの絶対値は、例えば０Ｖより大きく７０Ｖ以下である。 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. As a result, the voltage waveform of the drive signal applied to the piezoelectric element 14 changes. For example, the effective voltage of the voltage waveform changes. For example, the amplitude of the voltage waveform changes. Also, for example, the amplitude of the voltage waveform increases. Also, for example, the amplitude of the voltage waveform decreases. Specifically, the drive voltage Vpp is updated to Vpp+ΔV (step S11). ΔV 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 ΔV is, for example, greater than 0V and less than or equal to 70V.
　次に、制御装置５０は、駆動電圧Ｖｐｐの更新回数ＮｖをＮｖ＋１に更新する（ステップＳ１２）。 Next, the control device 50 updates the number of updates Nv of the drive voltage Vpp to Nv+1 (step S12).
　次に、制御装置５０は、ステップＳ１２で更新した更新回数Ｎｖが最大更新回数Ｎｖｍａｘを超えているか否かを判定する（ステップＳ１３）。最大更新回数Ｎｖｍａｘは、予め決定された回数であってもよい。Ｎｖｍａｘ、例えば、１回以上１０回以下である。 Next, the 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.
　ステップＳ１３で更新回数ＮｖがＮｖｍａｘを超えていると判定した場合、制御装置５０は、エラー（ＥＲＲＯＲ）を検出し（ステップＳ１４）、サーチモードでの動作を終了する（ステップＳ１５）。 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).
　ステップＳ１３で更新回数ＮｖがＮｖｍａｘを超えていないと判定した場合、ステップＳ３に戻る。 If it is determined in step S13 that the number of updates Nv does not exceed Nvmax, the process returns to step S3.
　ここで、図９Ａ及び図９Ｂを参照して、駆動電圧Ｖｐｐの実効電圧が変化したときの圧電素子１４の共振周波数とインピーダンスとの関係を説明する。図９Ａでは、横軸を実効電圧［Ｖ］、縦軸を共振周波数［Ｈｚ］としている。図９Ａは、実効電圧を１０Ｖから５０Ｖまで１０ずつに変化させたときの圧電素子１４の共振周波数ｆｃの変化の一例である。図９Ａに示すグラフから分かるように、実効電圧が大きくなるに従って圧電素子１４の共振周波数ｆｃは減少する。図９Ｂでは、横軸を周波数［ｋＨｚ］、縦軸をインピーダンス［Ω］としている。図９Ｂに示すグラフでは、実効電圧をＶｐｐ１からＶｐｐ３まで変化させた場合の共振周波数の変化の様子が図示されている。図９Ｂに示される実効電圧では、Ｖｐｐ１＞Ｖｐｐ２＞Ｖｐｐ３となっている。図９Ｂの周波数ｆ１は、ｆｍｉｎ≦ｆ１≦ｆｍａｘである駆動信号の周波数ｆｒの一例である。図９Ｂのグラフより、実効電圧がＶｐｐ１及びＶｐｐ２の場合、周波数ｆ１や周波数ｆ１＋Δｆの駆動信号では、インピーダンス値Ｚが閾値Ｚｔｈより大きく、共振周波数ｆｃを探索できない。しかしながら、実効電圧がＶｐｐ３の場合、周波数ｆ１の駆動信号により、インピーダンス値Ｚが閾値Ｚｔｈ以下になる周波数を探索できる。すなわち、ステップＳ１１で駆動電圧ＶｐｐをＶｐｐ＋ΔＶ変化させて、さらにステップＳ３以降のステップを実施することで、圧電素子１４の共振周波数ｆｃを駆動信号の周波数ｆｒと一致させる、又は駆動信号の周波数ｆｒに近づけることができる。 Here, the relationship between the resonance frequency and impedance of the piezoelectric element 14 when the effective voltage of the drive voltage Vpp changes will be described with reference to FIGS. 9A and 9B. In FIG. 9A, the horizontal axis is the effective voltage [V], and the vertical axis is the resonance frequency [Hz]. 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. As can be seen from the graph shown in FIG. 9A, the resonance frequency fc of the piezoelectric element 14 decreases as the effective voltage increases. In FIG. 9B, the horizontal axis represents frequency [kHz], and the vertical axis represents impedance [Ω]. The graph shown in FIG. 9B shows how the resonance frequency changes when the effective voltage is changed from Vpp1 to Vpp3. In the effective voltage shown in FIG. 9B, Vpp1>Vpp2>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+Δf, and the resonant frequency fc cannot be searched. However, when 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 + ΔV 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.
　したがって、上記の制御方法の第２サーチステップを実施することにより、圧電素子１４の共振周波数ｆｃの探索性能を向上させることができる。また、上記の制御方法は、プロセッサ２０の性能を変更することなく共振周波数の探索性能を向上させることができ、製造コストを抑えることができる。 Therefore, by implementing the second search step of the above control method, 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.
（実施の形態１の変形例１）
　実施の形態１では、第１サーチステップを実施した後に第２サーチステップを実施しているが、第１サーチステップは省略することができる。図１０を参照して、本変形例における撮像ユニット１００の振動装置１０の動作を説明する。図１０は、本変形例に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。 (Modification 1 of Embodiment 1)
In the first embodiment, the second search step is performed after the first search step, but the first search step can be omitted. Referring to FIG. 10, the operation of the vibration device 10 of the imaging unit 100 in this modification will be described. FIG. 10 is a flowchart for explaining the operation of the control device that controls the vibration device according to this modification.
　まず、制御装置５０は、駆動信号の周波数ｆｒをｆ０に設定する（ステップＳ１０１）。ｆ０は、例えば、先行するサーチモードで探索した任意の共振周波数である。 First, the 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.
　次に、制御装置５０は、駆動電圧ＶｐｐをＶ１に設定し（ステップＳ１０２）、駆動電圧Ｖｐｐの更新回数Ｎｖを１に設定する（ステップＳ１０３）。 Next, the 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).
　次に、制御装置５０は、ステップＳ１０１で設定した周波数ｆｒ、ステップＳ１０２で設定した駆動電圧Ｖｐｐの駆動信号を圧電素子１４に印加する（ステップＳ１０４）。 Next, the 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).
　次に、制御装置５０は、駆動信号の周波数ｆｒにおける圧電素子１４のインピーダンス値Ｚを測定する（ステップＳ１０５）。 Next, the control device 50 measures the impedance value Z of the piezoelectric element 14 at the frequency fr of the drive signal (step S105).
　次に、制御装置５０は、測定したインピーダンス値が所定の閾値Ｚｔｈ以下であるか否か判定する（ステップＳ１０６）。 Next, the control device 50 determines whether the measured impedance value is less than or equal to a predetermined threshold Zth (step S106).
　ステップＳ１０６で測定したインピーダンス値Ｚが所定の閾値Ｚｔｈ以下であると判定した場合、制御装置５０は、駆動信号の周波数ｆｒを圧電素子１４の共振周波数ｆｃとして決定する（ステップＳ１０７）。 If it is determined that the impedance value Z measured in step S106 is less than or equal to the predetermined 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 S107).
　ステップＳ１０７の次に、制御装置５０は、共振周波数ｆｃで圧電素子１４を振動させて透光体２に付着した異物を除去する駆動モードで動作する（ステップＳ１０８）。具体的には、制御装置５０は、圧電素子１４の共振周波数ｆｃを駆動周波数として決定し、決定した駆動周波数で圧電素子１４を駆動する。駆動モードでは、圧電素子１４の振動とあわせて、図１に示す洗浄ノズル３から洗浄液を吐出して透光体２に付着した異物を除去してもよい。 After 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.
　ステップＳ１０６で、インピーダンス値Ｚが所定の閾値Ｚｔｈを超えていると判定した場合、制御装置５０は、駆動電圧ＶｐｐをＶｐｐ＋ΔＶに更新する（ステップＳ１０９）。 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+ΔV (step S109).
　次に、制御装置５０は、駆動電圧Ｖｐｐの更新回数ＮｖをＮｖ＋１に更新する（ステップＳ１１０）。 Next, the control device 50 updates the number of updates Nv of the drive voltage Vpp to Nv+1 (step S110).
　次に、制御装置５０は、ステップＳ１１０で更新した更新回数Ｎｖが最大更新回数Ｎｖｍａｘを超えているか否かを判定する（ステップＳ１１１）。 Next, the control device 50 determines whether the number of updates Nv updated in step S110 exceeds the maximum number of updates Nvmax (step S111).
　ステップＳ１１１で更新回数ＮｖがＮｖｍａｘを超えていると判定した場合、制御装置５０は、エラー（ＥＲＲＯＲ）を検出し（ステップＳ１１２）、サーチモードでの動作を終了する（ステップＳ１１３）。 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).
　ステップＳ１１１で更新回数ＮｖがＮｖｍａｘを超えていないと判定した場合、ステップＳ１０４に戻る。 If it is determined in step S111 that the number of updates Nv does not exceed Nvmax, the process returns to step S104.
［効果］
　上記の制御方法に、圧電素子１４の共振周波数ｆｃの探索性能を向上させることができる。また、上記の制御方法は、制御ステップを簡易なものにでき、周波数探索の時間を短縮することができる。 [effect]
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.
（実施の形態１の変形例２）
　上記の制御方法では、制御装置５０は、圧電素子１４のインピーダンス値Ｚを検出しているが、制御装置５０は、圧電素子１４の電流値Ｉを検出してもよい。 (Modification 2 of Embodiment 1)
In the above control method, the 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.
　電流値はインピーダンスの逆数であるため、制御装置５０が圧電素子１４の電流値Ｉを検出する場合、上記の制御方法のステップＳ５で電流値Ｉを測定し、ステップＳ６で電流値Ｉが所定の閾値Ｉｔｈより大きいか否かを判定する。 Since the current value is the reciprocal of impedance, when 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.
　図１１に、本変形例に係る振動装置を制御する制御装置の動作を説明するためのフローチャートを示す。 FIG. 11 shows a flowchart for explaining the operation of the control device that controls the vibration device according to this modification.
　まず、図７に示す実施の形態１のステップＳ１からステップＳ４を実施する。 First, steps S1 to S4 of the first embodiment shown in FIG. 7 are performed.
　次に、制御装置５０によって、圧電素子１４の電流値Ｉを測定する（ステップＳ５Ａ）。 Next, the control device 50 measures the current value I of the piezoelectric element 14 (step S5A).
　次に、制御装置５０は、ステップＳ５Ａで測定した電流値Ｉが所定の閾値Ｉｔｈより大きいか否かを判定する（ステップＳ６Ａ）。 Next, the control device 50 determines whether the current value I measured in step S5A is larger than a predetermined threshold value Ith (step S6A).
　ステップＳ６Ａにおいて、電流値Ｉが所定の閾値Ｉｔｈより大きいと判定した場合、図７に示す実施の形態１のステップＳ７及びステップＳ８を実施する。 In 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.
　ステップＳ６Ａにおいて、電流値Ｉが所定の閾値Ｉｔｈより大きくないと判定した場合、図７に示す実施の形態１のステップＳ９及びステップＳ１５を実施する。 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.
［効果］
　上記の制御方法に、共振周波数の探索性能を向上させることができる。また、上記の制御方法は、圧電素子１４の共振周波数ｆｃを決定するための測定値が圧電素子１４の電流値Ｉであるため、測定が容易である。 [effect]
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.
（実施の形態２）
　実施の形態２は、サーチモードで共振数周波数を探索する方法が実施の形態１と異なる。実施の形態２におけるサーチモードは、第１サーチステップと第３サーチステップとを含む。第１サーチステップは、駆動信号の周波数ｆｒをｆｍｉｎからｆｍａｘの間でスイープさせて圧電素子１４の共振周波数ｆｃを探索する点で、実施の形態１と異なる。第３サーチステップは、第１サーチステップで圧電素子１４の共振周波数ｆｃを探索できなかった場合に実施される。第３サーチステップは、駆動信号に含まれる複数のクロックのうちいくつかのクロックのクロック幅を変更することで圧電素子１４の共振周波数ｆｃを探索する。ここで、クロック幅を変更することは、デューティ比を変更して行ってもよい。 (Embodiment 2)
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. Here, the clock width may be changed by changing the duty ratio.
　図１２は、実施の形態２に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。図１２を参照して、実施の形態２における振動装置の制御方法を説明する。 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.
　まず、制御装置５０は、駆動電圧ＶｐｐをＶｄｒに設定する（ステップＳ２０１）。電圧Ｖｄｒの実効電圧は、例えば、０Ｖ以上７０Ｖ以下である。 First, the 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.
　次に、制御装置５０は、駆動信号に含まれる複数のクロックのクロック幅ａをａｍｉｎに設定し（ステップＳ２０２）、クロック幅ａの更新回数Ｎｃを１に設定する（ステップＳ２０３）。ａｍｉｎは、クロック幅ａの最小値であり、例えば、予め設定された値である。ａｍｉｎは、例えば、１ｕｓｅｃ（１ＭＨｚ）以上５０ｕｓｅｃ（２０ｋＨｚ）以下である。ここで、駆動信号の周波数ｆｒはクロック幅に依拠するため、クロック幅ａを設定すると、駆動信号の周波数ｆｒはｆｒ（ａ）に設定される。また、複数のクロックのクロック幅が単一の幅ａである場合、ｆｒ＝ｆｒ（ａ）＝ａである。そのため、クロック幅ａをａｍｉｎに設定すると、周波数ｆｒはｆｒ（ａ）＝ａｍｉｎ＝ｆｍｉｎに設定される。 Next, 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. Here, since the frequency fr of the drive signal depends on the clock width, when the clock width a is set, the frequency fr of the drive signal is set to fr(a). Furthermore, when the clock widths of a plurality of clocks are a single width a, fr=fr(a)=a. Therefore, when the clock width a is set to amin, the frequency fr is set to fr(a)=amin=fmin.
　次に、制御装置５０は、ステップＳ２０１で設定した駆動電圧Ｖｐｐ、ステップＳ２０２で設定した周波数ｆｒの駆動信号を圧電素子１４に印加する（ステップＳ２０４）。 Next, the 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).
　次に、制御装置５０は、駆動信号の周波数ｆｒにおける圧電素子１４のインピーダンス値Ｚを測定する（ステップＳ２０５）。 Next, the control device 50 measures the impedance value Z of the piezoelectric element 14 at the frequency fr of the drive signal (step S205).
　制御装置５０は、測定したインピーダンス値Ｚが所定の閾値Ｚｔｈ以下であるか否か判定する（ステップＳ２０６）。 The control device 50 determines whether the measured impedance value Z is less than or equal to a predetermined threshold value Zth (step S206).
　ステップＳ２０６において測定したインピーダンス値Ｚが閾値Ｚｔｈ以下であると判定した場合、制御装置５０は、駆動信号の周波数ｆｒを圧電素子１４の共振周波数ｆｃとして決定する（ステップＳ２０７）。 If it is determined that the impedance value Z measured in step S206 is equal to or less 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 S207).
　ステップＳ２０７の次に、制御装置５０は、ステップＳ２０７で決定した共振周波数ｆｃで圧電素子１４を振動させて透光体２に付着した異物を除去する駆動モードで動作する（ステップＳ２０８）。駆動モードでは、圧電素子１４の振動とあわせて、図１に示す洗浄ノズル３から洗浄液を吐出して透光体２に付着した異物を除去してもよい。 Next to 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). 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.
　ステップＳ２０６において測定したインピーダンス値Ｚが閾値Ｚｔｈ以下でないと判定した場合、制御装置５０は、駆動信号に含まれる複数のクロックのクロック幅ａをａ＋Δａに更新する（ステップＳ２０９）。これにより、駆動信号の周波数ｆｒはｆｒ（ａ＋Δａ）＝ａ＋Δａに更新される。Δａは、例えば、１Ｈｚ以上１ｋＨｚ以下である。 If it is determined that the impedance value Z measured in step S206 is not equal to or less than the threshold value Zth, the control device 50 updates the clock width a of the plurality of clocks included in the drive signal to a+Δa (step S209). Thereby, the frequency fr of the drive signal is updated to fr(a+Δa)=a+Δa. Δa is, for example, 1 Hz or more and 1 kHz or less.
　次に、制御装置５０は、クロック幅ａの更新回数ＮｃをＮｃ＋１に更新する（ステップＳ２１０）。 Next, the control device 50 updates the number of updates Nc of the clock width a to Nc+1 (step S210).
　次に、制御装置５０は、ステップＳ２１０で更新した更新回数Ｎｃが所定の閾値Ｎｃｔｈ１を超えているか否かを判定する（ステップＳ２１１）。Ｎｃｔｈ１は、例えば、１回以上１０回以下である。 Next, the 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.
　ステップＳ２１１で更新回数ＮｃがＮｃｔｈ１を超えていないと判定した場合、ステップＳ２０３に戻る。 If it is determined in step S211 that the number of updates Nc does not exceed Ncth1, the process returns to step S203.
　上記のステップＳ２０１からステップＳ２１１までが本実施の形態における第１サーチステップであり、ステップＳ２１１で更新回数ＮｃがＮｃｔｈ１を超えていると判定するとき、駆動信号の周波数ｆｒはｆｍａｘに到達している。したがって、第１サーチステップにおいて、駆動信号の周波数ｆｒがｆｍｉｎからｆｍａｘまでスイープされる。すなわち、第１サーチステップにおいて、クロック幅はａｍｉｎからａｍａｘまで変化する。ステップＳ２１１で、更新回数ＮｃがＮｃｔｈ１を超えていると判定した場合、以下の第３サーチステップが実施される。 The above 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.
　ステップＳ２１１において更新回数ＮｃがＮｃｔｈ１を超えていると判定した場合、制御装置５０は、複数のクロックのうちいくつかのクロックのクロック幅と他のクロックのクロック幅とが異なるようにクロック幅を変更する（ステップＳ２１２）。言い換えると、いくつかのクロックを複数の第１クロック、残りのクロックを複数の第２クロック、と称し、複数の第１クロックのクロック幅をａｍａｘに維持し、複数の第２クロックのクロック幅をａ１に変更する。クロック幅ａ１は、例えば、クロック幅ａｍａｘの１倍未満の値であり、好ましくは０．５倍以上１倍未満の値であり、さらに好ましくは０．９９倍以上１倍未満の値である。すなわち、制御装置５０は、複数のクロックのうち、いくつかのクロックのクロック幅を他のクロックのクロック幅の１倍未満の値に、好ましくは０．５倍以上１倍未満の値に、さらに好ましくは０．９９倍以上１倍未満の値に変更する。また、幅ａ１は、例えばａｍａｘ－Δａであり、Δａは、例えばステップＳ２０９のΔａと同一である。クロック幅ａの変更に伴い、駆動信号の周波数ｆｒは、ｆｒ（ａ（ａｍａｘ、ａ１））に変更される。なお、本実施形態では、複数のクロックのうち複数の第２クロック幅を複数の第１クロック幅の１倍未満としているが、これに限定するものではなく、複数のクロックのうち複数の第２クロック幅を複数の第１クロック幅の１倍より大きくしてもよい。この場合、例えば、複数の第２クロック幅は複数の第１クロック幅の１倍より大きく、１．５倍以下の値であり、好ましくは、１倍より大きく、１．０１倍以下である。 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). In other words, 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−Δa, and Δa is, for example, the same as Δa in step S209. As the clock width a changes, the frequency fr of the drive signal is changed to fr(a(amax, a1)). Note that in this embodiment, 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. In this case, for example, 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.
　また、ステップＳ２１２において、制御装置５０は、例えば、駆動信号に含まれる複数のクロックのうち０．１％以上９９．９％以下のクロックのクロック幅を変更する。図１３を参照して具体例を説明する。図１３は、クロック幅が変更された、駆動信号に含まれる複数のクロックの一例を示す。図１３に示すように、制御装置５０は、駆動信号に含まれる複数のクロックのうち１／２（５０％）のクロックのクロック幅を幅ａｍａｘに変更し、残りの１／２（５０％）のクロックのクロック幅を幅ａ１に変更する。 Furthermore, in 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. A specific example will be explained with reference to FIG. 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.
　また、ステップＳ２１２において、制御装置５０は、例えば、複数のクロックのクロック幅を周期的に変更する。これにより、いくつかのクロックは、複数のクロックにおいて周期的に位置する。例えば、いくつかのクロックは、複数のクロックにおいて等間隔に位置する。具体的には、制御装置５０は、駆動信号に含まれる複数のクロックのうち幅ａｍａｘのクロックと幅ａ１のクロックとが交互に含まれるように、複数のクロックのクロック幅を周期的に変更する。 Furthermore, in step S212, the control device 50 periodically changes the clock widths of the plurality of clocks, for example. Thereby, some clocks are located periodically in multiple clocks. For example, some clocks are equally spaced among multiple clocks. Specifically, 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. .
　次に、制御装置５０は、クロック幅ａの更新回数ＮｃをＮｃ＋１に更新する（ステップＳ２１３）。 Next, the control device 50 updates the number of updates Nc of the clock width a to Nc+1 (step S213).
　次に、制御装置５０は、駆動信号の周波数ｆｒ（ａ（ａｍａｘ、ａ１））における圧電素子１４のインピーダンス値Ｚを測定する（ステップＳ２１４）。 Next, the 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).
　次に、制御装置５０は、ステップＳ２１４で測定したインピーダンス値Ｚが所定の閾値Ｚｔｈ以下であるか否か判定する（ステップＳ２１５）。 Next, the 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).
　ステップＳ２１５で測定したインピーダンス値Ｚが所定の閾値Ｚｔｈ以下であると判定した場合、制御装置５０は、駆動信号の周波数ｆｒを圧電素子１４の共振周波数ｆｃとして決定する（ステップＳ２１６）。 If it is determined that the impedance value Z measured in step S215 is equal to or less than the predetermined 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 S216).
　ステップＳ２１６の次に、制御装置５０は、ステップＳ２１６で決定した共振周波数ｆｃで圧電素子１４を振動させて透光体２に付着した異物を除去する駆動モードで動作する（ステップＳ２１７）。具体的には、制御装置５０は、圧電素子１４の共振周波数ｆｃを駆動周波数として決定し、決定した駆動周波数で圧電素子１４を駆動する。駆動モードでは、圧電素子１４の振動とあわせて、図１に示す洗浄ノズル３から洗浄液を吐出して透光体２に付着した異物を除去してもよい。 After 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.
　ステップＳ２１５において、測定したインピーダンス値Ｚが閾値Ｚｔｈ以下でないと判定した場合、制御装置５０は、駆動信号に含まれる複数のクロックのクロック幅ａ－Δａに更新する（ステップＳ２１８）。これにより、駆動信号の周波数ｆｒがｆｒ（ａ－Δａ）に更新される。クロック幅ａ－Δａに更新するとは、例えば、クロック幅ａｍａｘ及びクロック幅ａ１を共にΔａ減少させることを意味する。Δａは、例えばステップＳ２０９のΔａと同一である。 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−Δa 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−Δa). Updating to clock width a−Δa means, for example, decreasing both clock width amax and clock width a1 by Δa. Δa is, for example, the same as Δa in step S209.
　次に、制御装置５０は、クロック幅ａの更新回数ＮｃをＮｃ＋１に更新する（ステップＳ２１９）。 Next, the control device 50 updates the number of updates Nc of the clock width a to Nc+1 (step S219).
　次に、制御装置５０は、ステップＳ２１９で更新した更新回数Ｎｃが閾値Ｎｃｔｈ２を超えているか否かを判定する（ステップＳ２２０）。Ｎｃｔｈ２は、例えば、１回以上１０回以下である。 Next, the 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.
　ステップＳ２２０で更新回数ＮｃがＮｃｔｈ２を超えていないと判定した場合、ステップＳ２１４に戻る。 If it is determined in step S220 that the number of updates Nc does not exceed Ncth2, the process returns to step S214.
　ステップＳ２２０で更新回数ＮｃがＮｃｔｈ２を超えていると判定した場合、制御装置５０は、エラー（ＥＲＲＯＲ）を検出し、サーチモードでの動作を終了する（ステップＳ２２１）。 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).
　駆動信号に含まれる複数のクロックが２以上のクロック幅を含むと、駆動信号の周波数ｆｒは、該２以上のクロック幅に依拠する周波数ｆｒとなる。例えば、駆動信号に含まれる複数のクロックがクロック幅Ａ１のクロックをＮ１％の割合で含み、クロック幅Ａ２のクロックをＮ２％（Ｎ２＝１００－Ｎ１）の割合で含む場合、駆動信号の周波数ｆｒは、以下の式１で表される。 When the plurality of clocks included in the drive signal include two or more clock widths, the frequency fr of the drive signal becomes a frequency fr that depends on the two or more clock widths. For example, if a plurality of clocks included in a drive signal include clocks with a clock width A1 at a rate of N1% and clocks with a clock width A2 at a rate of N2% (N2 = 100 - N1), the frequency fr of the drive signal is expressed by the following equation 1.
（式１）
ｆｒ＝ｆｒ（ａ（Ａ１、Ａ２））
　　＝Ｎ１／１００×Ａ１＋Ｎ２／１００×Ａ２
　　＝Ｎ１／１００×ｆｒ（Ａ１）＋Ｎ２／１００×ｆｒ（Ａ２） (Formula 1)
fr=fr(a(A1, A2))
=N1/100×A1+N2/100×A2
=N1/100×fr(A1)+N2/100×fr(A2)
　具体的には、例えば、駆動信号に含まれる複数のクロックが、クロック幅ａｍａｘのクロックを５０％の割合で含み、クロック幅ａ１＝ａｍａｘ－Δａのクロックを５０％の割合で含む場合、駆動信号の周波数ｆｒは、以下の式２で表される。 Specifically, for example, if the plurality of clocks included in the drive signal include clocks with a clock width amax at a rate of 50% and clocks with a clock width a1 = amax - Δa at a rate of 50%, the drive signal The frequency fr is expressed by the following equation 2.
（式２）
ｆｒ＝ｆｒ（ａ（ａｍａｘ、ａ１））
　　＝ｆｒ（ａ（ａｍａｘ、ａｍａｘ－Δａ））
　　＝５０／１００×ａｍａｘ＋５０／１００×（ａｍａｘ－Δａ）
　　＝１／２×ａｍａｘ＋１／２×（ａｍａｘ－Δａ）
　　＝１／２×ｆｒ（ａｍａｘ）＋１／２×ｆｒ（ａｍａｘ－Δａ） (Formula 2)
fr=fr(a(amax, a1))
= fr(a(amax, amax-Δa))
=50/100×amax+50/100×(amax−Δa)
=1/2×amax+1/2×(amax−Δa)
=1/2×fr(amax)+1/2×fr(amax−Δa)
　従って、第３サーチステップを実施することにより、ｆｒ（ａｍａｘ）とｆｒ（ａｍａｘ－Δａ）との間の値の周波数ｆｒを有する駆動信号を発出することができる。 Therefore, by performing the third search step, it is possible to generate a drive signal having a frequency fr between fr(amax) and fr(amax-Δa).
　ここで図１４を参照する。図１４は、圧電素子の共振周波数とインピーダンスとの関係を示すグラフにおける、駆動信号の周波数と共振周波数との関係を示す。図１４に示すグラフは、横軸を周波数［ｋＨｚ］、縦軸をインピーダンス［Ω］としている。図１４に示す例では、圧電素子１４の共振周波数ｆｃがｆ（ａｍａｘ）とｆ（ａｍａｘ－Δａ）の間に存在する。また、駆動信号の周波数ｆｒがｆ（ａｍａｘ）又はｆ（ａｍａｘ－Δａ）のとき、測定されるインピーダンスＺが閾値Ｚｔｈより大きい。したがって、第１サーチステップでは探索できない。しかしながら、式２に示したように、第３サーチステップを実施することにより、ｆｒ（ａｍａｘ）とｆｒ（ａｍａｘ－Δａ）との間の値の周波数ｆｒ（ａ（ａｍａｘ、ａｍａｘ‐Δａ））を有する駆動信号を発出することができる。これにより、第１サーチステップでは探索できなかったｆｒ（ａｍａｘ）とｆｒ（ａｍａｘ－Δａ）との間に存在する共振周波数ｆｃを探索することができる。 Refer now to FIG. 14. 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. In the graph shown in FIG. 14, the horizontal axis represents frequency [kHz] and the vertical axis represents impedance [Ω]. In the example shown in FIG. 14, the resonance frequency fc of the piezoelectric element 14 exists between f(amax) and f(amax−Δa). Further, when the frequency fr of the drive signal is f(amax) or f(amax−Δa), the measured impedance Z is larger than the threshold value Zth. Therefore, it cannot be searched in the first search step. However, as shown in Equation 2, by performing the third search step, the frequency fr(a(amax, amax-Δa)) with a value between fr(amax) and fr(amax-Δa) 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-Δa), which could not be searched in the first search step.
［効果］
　したがって、上記の制御方法の第３サーチステップにより、プロセッサ２０の性能に依らずに、周波数分解能を向上させることができる。これにより、圧電素子１４の駆動周波数を適切に制御できる。具体的には、圧電素子１４の共振周波数ｆｃの探索性能を向上させることができるため、圧電素子１４の駆動周波数を適切に決定できる。また、高価なプロセッサ２０を用いなくてもよいため、製造コストの増大を抑制することができる。 [effect]
Therefore, by the third search step of the above control method, the frequency resolution can be improved regardless of the performance of the processor 20. Thereby, 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.
（実施の形態２の変形例１）
　実施の形態２の制御方法では、第１サーチステップを実施した後に第３サーチステップを実施しているが、第１サーチステップは省略することができる。図１５を参照して、本変形例における撮像ユニット１００の振動装置１０の動作を説明する。図１５は、本変形例に係る振動装置を制御する制御装置の動作を説明するためのフローチャートである。 (Modification 1 of Embodiment 2)
In the control method of the second embodiment, the third search step is performed after the first search step, but the first search step can be omitted. Referring to FIG. 15, the operation of the vibration device 10 of the imaging unit 100 in this modification will be described. FIG. 15 is a flowchart for explaining the operation of the control device that controls the vibration device according to this modification.
　まず、制御装置５０は、駆動電圧ＶｐｐをＶｄｒに設定する（ステップＳ３０１）。 First, the control device 50 sets the drive voltage Vpp to Vdr (step S301).
　次に、制御装置５０は、複数のクロックのうちいくつかのクロックのクロック幅が他のクロックのクロック幅と異なるようにクロック幅を設定する（ステップＳ３０２）。例えば、駆動信号に含まれる複数のクロックのうち５０％のクロックのクロック幅を幅ａｍａｘに設定し、残りの５０％のクロックのクロック幅を幅ａ１に設定する。幅ａ１は、例えばａｍａｘ－Δａであり、Δａは、例えば、実施の形態２のステップＳ２０９のΔａと同一である。クロック幅の変更に伴い、駆動信号の周波数ｆｒは、ｆｒ（ａ（ａｍａｘ、ａ１））に設定される。 Next, 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). For example, the clock width of 50% of the clocks included in the drive signal is set to the width amax, and the clock width of the remaining 50% of the clocks is set to the width a1. The width a1 is, for example, amax−Δa, and Δa is, for example, the same as Δa in step S209 of the second embodiment. As the clock width changes, the frequency fr of the drive signal is set to fr(a(amax, a1)).
　また、ステップＳ３０２において、制御装置５０が、複数のクロックのうちいくつかのクロックのクロック幅と他のクロックのクロック幅とを異ならせる方法は、実施の形態２のステップＳ２１２におけるクロック幅を変更方法と同様の方法を採用できる。 Furthermore, in 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.
　次に、制御装置５０は、クロック幅ａの更新回数Ｎｃを１に設定する（ステップＳ３０３）。 Next, the control device 50 sets the number of updates Nc of the clock width a to 1 (step S303).
　次に、制御装置５０は、ステップＳ３０１で設定した駆動電圧Ｖｐｐ、ステップＳ３０２で設定した周波数ｆｒ（ａ（ａｍａｘ、ａ１））の駆動信号を圧電素子１４に印加する（ステップＳ３０４）。 Next, the 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).
　次に、制御装置５０は、駆動信号の周波数ｆｒ（ａ（ａｍａｘ、ａ１））における圧電素子１４のインピーダンス値Ｚを測定する（ステップＳ３０５）。 Next, the 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).
　次に、制御装置５０は、ステップＳ３０５で測定したインピーダンス値Ｚが所定の閾値Ｚｔｈ以下であるか否か判定する（ステップＳ３０６）。 Next, the 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).
　ステップＳ３０５で測定したインピーダンス値Ｚが閾値Ｚｔｈ以下であると判定した場合、制御装置５０は、駆動信号の周波数ｆｒを圧電素子１４の共振周波数ｆｃと決定する（ステップＳ３０７）。 If it is determined that the impedance value Z measured in step S305 is equal to or less than the threshold value Zth, 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).
　ステップＳ３０７の次に、制御装置５０は、ステップＳ４０７で決定した共振周波数ｆｃで圧電素子１４を振動させて透光体２に付着した異物を除去する駆動モードで動作する（ステップＳ３０８）。駆動モードでは、圧電素子１４の振動とあわせて、洗浄ノズル３から洗浄液を吐出して透光体２に付着した異物を除去してもよい。 After 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). In the drive mode, 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 .
　ステップＳ３０６において、測定したインピーダンス値Ｚが閾値Ｚｔｈ以下でないと判定した場合、制御装置５０は、駆動信号に含まれる複数のクロックのクロック幅ａ－Δａに更新する（ステップＳ３０９）。これにより、駆動信号の周波数ｆｒがｆｒ（ａ－Δａ）に更新される。クロック幅ａ－Δａに更新するとは、例えば、クロック幅ａｍａｘ及びクロック幅ａ１を共にΔａ減少させることを意味する。Δａは、例えば、実施の形態２のステップＳ２０９におけるΔａと同一である。 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−Δa 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−Δa). Updating to clock width a−Δa means, for example, decreasing both clock width amax and clock width a1 by Δa. Δa is, for example, the same as Δa in step S209 of the second embodiment.
　次に、制御装置５０は、クロック幅ａの更新回数ＮｃをＮｃ＋１に更新する（ステップＳ３１０）。 Next, the control device 50 updates the number of updates Nc of the clock width a to Nc+1 (step S310).
　次に、制御装置５０は、ステップＳ４１０で更新した更新回数ＮｃがｚＮｃｍａｘを超えているか否かを判定する（ステップＳ３１１）。最大更新回数Ｎｃｍａｘは、予め設定された更新回数であってもよい。Ｎｃｍａｘは、例えば、１回以上１０回以下である。 Next, the 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.
　ステップＳ３１１で更新回数ＮｃがＮｃｍａｘを超えていないと判定した場合、ステップＳ３０５に戻る。 If it is determined in step S311 that the number of updates Nc does not exceed Ncmax, the process returns to step S305.
　ステップＳ３１１で更新回数ＮｃがＮｃｍａｘを超えていると判定した場合、制御装置５０は、エラー（ＥＲＲＯＲ）を検出し（ステップＳ３１２）、サーチモードでの動作を終了する（ステップＳ３１３）。 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).
［効果］
　上記の制御方法に、圧電素子１４の共振周波数ｆｃの探索性能を向上させることができる。また、上記の制御方法は、制御を簡易なものにでき、周波数探索の時間を短縮することができる。 [effect]
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.
（実施の形態２の変形例２）
　実施の形態２の制御方法では、ステップＳ２１２において、制御装置５０は、駆動信号に含まれる複数のクロックのうち１／２（５０％）のクロックのクロック幅を幅ａｍａｘに維持し、残りの１／２（５０％）のクロックのクロック幅を幅ａ１に変更している。しかしながら、プロセッサ２０が、複数のクロックのうちいくつかのクロックのクロック幅と他のクロックのクロック幅とが異なるようにクロック幅を変更する方法はこれに限定されるものではない。 (Modification 2 of Embodiment 2)
In the control method of the second embodiment, in 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. However, 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.
　制御装置５０は、例えば図１６に示すように、駆動信号に含まれる複数のクロックのうち２／３のクロックのクロック幅を幅ａｍａｘに維持し、残りの１／３のクロックのクロック幅を幅ａ１に変更してもよい。この場合、クロック幅ａ１のクロックは、例えば、３回に１回の周期で発出される。また、この場合、駆動信号の周波数ｆｒは、以下の式３で表される。 For example, as shown in FIG. 16, 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. In this case, a clock having a clock width a1 is issued, for example, once every three times. Further, in this case, the frequency fr of the drive signal is expressed by the following equation 3.
（式３）
ｆｒ＝ｆｒ（ａ（ａｍａｘ、ａ１））
　　＝ｆｒ（ａ（ａｍａｘ、ａｍａｘ－Δａ））
　　＝２／３×ａｍａｘ＋１／３×（ａｍａｘ－Δａ）
　　＝２／３×ｆｒ（ａｍａｘ）＋１／３×ｆｒ（ａｍａｘ－Δａ） (Formula 3)
fr=fr(a(amax, a1))
= fr(a(amax, amax-Δa))
=2/3×amax+1/3×(amax−Δa)
=2/3×fr(amax)+1/3×fr(amax−Δa)
　すなわち、幅ａｍａｘのクロックを２／３の割合で含み、クロック幅ａ１のクロックを１／３の割合で含む駆動信号と、幅ａｍａｘのクロックと幅ａ１のクロックとを同じ割合で含んでいる駆動信号とは異なる周波数ｆｒを有する駆動信号を発出できる。 That is, 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.
［効果］
　上記より、駆動信号に含まれる複数のクロックのクロック幅の変更方法に応じて、種々の周波数ｆｒを有する駆動信号を発出することが可能になる。これにより、圧電素子１４の駆動周波数を適切に制御できる。具体的には、所望の周波数の駆動信号を発出することができ、共振周波数ｆｃの探索性能を向上させることができるため、圧電素子１４の駆動周波数を適切に決定できる。 [effect]
From the above, it becomes possible to issue drive signals having various frequencies fr depending on the method of changing the clock widths of the plurality of clocks included in the drive signal. Thereby, the drive frequency of the piezoelectric element 14 can be appropriately controlled. Specifically, since a drive signal of a desired frequency can be emitted and the search performance for the resonance frequency fc can be improved, the drive frequency of the piezoelectric element 14 can be determined appropriately.
　なお、上記実施形態では、制御装置５０は、圧電素子１４の共振周波数を決定し、決定した共振周波数を、圧電素子１４を駆動する駆動周波数とする例について説明したが、これに限定されない。例えば、制御装置５０は、圧電素子１４の共振周波数を決定せず、圧電素子１４のインピーダンスに関する値の変化に基づいて駆動周波数を決定してもよい。 Note that in the above embodiment, an example has been described in which the 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. For example, 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.
　本開示の振動装置を制御する制御方法および振動装置の制御装置は、屋外で使用する車載カメラ、監視カメラ、またはＬｉＤＡＲ等の光センサに利用される振動装置に適用できる。 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.
１　筐体
２　透光体
３　洗浄ノズル
５　撮像装置
１０　振動装置
１２　振動体
１３　リテーナー
１４　圧電素子
１５　配線
２０　プロセッサ
３０　圧電駆動部
５０　制御装置
７０　インピーダンス検出部
８０　電源回路
１００　撮像ユニット 1 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

Claims (16)

  1. 　圧電素子を備えた振動装置を制御装置によって制御する方法であって、
    　前記圧電素子に印加する電圧波形を変化させるステップと、
    　前記圧電素子のインピーダンスに関する値を測定するステップと、
    　測定された前記圧電素子の前記インピーダンスに関する値に基づいて、前記圧電素子を駆動する駆動周波数を決定するステップと、
    を含む、
    方法。     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,
    Method.
  2. 　前記電圧波形を変化させるステップが、前記電圧波形の実効電圧を変化させることを有する、
    請求項１に記載の方法。     The step of changing the voltage waveform includes changing an effective voltage of the voltage waveform.
    The method according to claim 1.
  3. 　前記電圧波形を変化させるステップが、前記電圧波形の振幅を変化させること、を有する、
    請求項１又は２に記載の方法。     The step of changing the voltage waveform includes changing the amplitude of the voltage waveform.
    The method according to claim 1 or 2.
  4. 　前記電圧波形を変化させるステップが、前記電圧波形の振幅を増加させることを有する、
    請求項３に記載の方法。     changing the voltage waveform comprises increasing the amplitude of the voltage waveform;
    The method according to claim 3.
  5. 　前記電圧波形を変化させるステップが、前記電圧波形の振幅を減少させることを有する、
    請求項３に記載の方法。     changing the voltage waveform comprises decreasing the amplitude of the voltage waveform;
    The method according to claim 3.
  6. 　前記圧電素子を駆動する駆動信号の周波数を変化させるステップ、を更に含み、
    　前記インピーダンスに関する値を測定するステップは、前記周波数が変化している間、前記インピーダンスに関する値を測定すること、を有する、
    請求項１から５のいずれか１項に記載の方法。     further comprising the step of changing the frequency of a drive signal that drives the piezoelectric element,
    The step of measuring the impedance value includes measuring the impedance value while the frequency is changing.
    A method according to any one of claims 1 to 5.
  7. 　前記駆動周波数を決定するステップにおいて、前記周波数が変化している間に測定した前記インピーダンスに関する値に基づいて前記駆動周波数を決定できなかった場合、前記電圧波形を変化させるステップが実行される、
    請求項６に記載の方法。     In the step of determining the driving frequency, if the driving 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.
    The method according to claim 6.
  8. 　前記インピーダンスに関する値は、インピーダンス値であり、
    　前記駆動周波数を決定するステップは、
    　　前記インピーダンスに関する値が所定の閾値以下であるか否か判定することと、
    　　前記インピーダンスに関する値が所定の閾値以下であると判定した場合、前記圧電素子を駆動する駆動信号の周波数を前記駆動周波数として決定することと、
    を有する、
    請求項１から７のいずれか１項に記載の方法。     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;
    If it is determined that 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;
    has,
    8. A method according to any one of claims 1 to 7.
  9. 　圧電素子を備える振動装置を制御する制御装置であって、
    　前記圧電素子を駆動するための駆動信号を送信するプロセッサと、
    　前記プロセッサにより実行される命令を記憶したメモリと、
    を備え、
    　前記命令は、
    　　前記圧電素子に印加する電圧波形を変化させるステップと、
    　　前記圧電素子のインピーダンスに関する値を測定するステップと、
    　　測定された前記圧電素子の前記インピーダンスに関する値に基づいて、前記圧電素子を駆動する駆動周波数を決定するステップと、
    を含む、
    制御装置。     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,
    Control device.
  10. 　前記電圧波形を変化させるステップが、前記電圧波形の実効電圧を変化させることを有する、
    請求項９に記載の制御装置。     The step of changing the voltage waveform includes changing an effective voltage of the voltage waveform.
    The control device according to claim 9.
  11. 　前記電圧波形を変化させるステップが、前記電圧波形の振幅を変化させること、を有する、
    請求項９又は１０に記載の制御装置。     The step of changing the voltage waveform includes changing the amplitude of the voltage waveform.
    The control device according to claim 9 or 10.
  12. 　前記電圧波形を変化させるステップが、前記電圧波形の振幅を増加させることを有する、
    請求項１１に記載の制御装置。     changing the voltage waveform comprises increasing the amplitude of the voltage waveform;
    The control device according to claim 11.
  13. 　前記電圧波形を変化させるステップが、前記電圧波形の振幅を減少させることを有する、
    請求項１１に記載の制御装置。     changing the voltage waveform comprises decreasing the amplitude of the voltage waveform;
    The control device according to claim 11.
  14. 　前記駆動信号の周波数を変化させるステップ、を更に含み、
    　前記インピーダンスに関する値を測定するステップは、前記周波数が変化している間、前記インピーダンスに関する値を測定すること、を有する、
    請求項９から１３のいずれか１項に記載の制御装置。     further comprising the step of changing the frequency of the drive signal,
    The step of measuring the impedance value includes measuring the impedance value while the frequency is changing.
    The control device according to any one of claims 9 to 13.
  15. 　前記駆動周波数を決定するステップにおいて、前記周波数が変化している間に測定した前記インピーダンスに関する値に基づいて前記駆動周波数を決定できなかった場合、前記電圧波形を変化させるステップが実行される、
    請求項１４に記載の制御装置。     In the step of determining the driving frequency, if the driving 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.
    The control device according to claim 14.
  16. 　前記インピーダンスに関する値は、インピーダンス値であり、
    　前記駆動周波数を決定するステップは、
    　　前記インピーダンスに関する値が所定の閾値以下であるか否か判定することと、
    　　前記インピーダンスに関する値が所定の閾値以下であると判定したときの前記駆動信号の周波数を前記駆動周波数として決定することと、
    を有する、
    請求項９から１５のいずれか１項に記載の制御装置。     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;
    has,
    The control device according to any one of claims 9 to 15.
PCT/JP2022/042060 2022-03-31 2022-11-11 Control device for controlling vibration device and method for controlling vibration device WO2023188516A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003174784A (en) * 2001-12-06 2003-06-20 Asmo Co Ltd Controller for ultrasonic motor, and method of controlling the same
WO2020217600A1 (en) * 2019-04-26 2020-10-29 株式会社村田製作所 Cleaning device, imaging unit with cleaning device, and cleaning method
JP2021100308A (en) * 2019-12-20 2021-07-01 セイコーエプソン株式会社 Method for controlling piezoelectric driving device, piezoelectric driving device, and robot

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003174784A (en) * 2001-12-06 2003-06-20 Asmo Co Ltd Controller for ultrasonic motor, and method of controlling the same
WO2020217600A1 (en) * 2019-04-26 2020-10-29 株式会社村田製作所 Cleaning device, imaging unit with cleaning device, and cleaning method
JP2021100308A (en) * 2019-12-20 2021-07-01 セイコーエプソン株式会社 Method for controlling piezoelectric driving device, piezoelectric driving device, and robot

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