WO2021256370A1 - Drive method, drive circuit, and displacement drive device - Google Patents

Drive method, drive circuit, and displacement drive device Download PDF

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Publication number
WO2021256370A1
WO2021256370A1 PCT/JP2021/022113 JP2021022113W WO2021256370A1 WO 2021256370 A1 WO2021256370 A1 WO 2021256370A1 JP 2021022113 W JP2021022113 W JP 2021022113W WO 2021256370 A1 WO2021256370 A1 WO 2021256370A1
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Prior art keywords
drive
voltage
positive electrode
displacement
negative electrode
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PCT/JP2021/022113
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French (fr)
Japanese (ja)
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隆幸 後藤
亮 伊藤
和宗 橘
寛之 清水
純明 岸本
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太陽誘電株式会社
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Publication of WO2021256370A1 publication Critical patent/WO2021256370A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • 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
    • 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
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • 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
    • H10N30/80—Constructional details

Definitions

  • the present invention relates to a method for driving a dielectric element, a drive circuit, and a displacement drive device.
  • piezoelectric actuators are used as vibration devices for generating tactile sensations.
  • Piezoelectric actuators are attracting particular attention as next-generation tactile module components because they have a high response speed, a wide range of drive frequencies that can be handled, and can express a variety of tactile sensations (for example, Patent Document 1).
  • the drive amplitude of the piezoelectric actuator is smaller than that of the electromagnetic type, and in order to increase the drive amplitude, it is necessary to increase the drive voltage of the piezoelectric element.
  • bipolar (bipolar) drive there is a limitation of the coercive electric field, and there is a problem of depolarization when the drive voltage amplitude is made larger than the coercive electric field.
  • unipolar drive in the polarization direction although it is not affected by the coercive electric field, there is a problem that reliability is impaired when the drive voltage amplitude is excessively increased, and the displacement becomes smaller depending on the number of drives. There was a problem.
  • PZT lead zirconate titanate
  • the lead-free piezoelectric material requires a regulated substance such as Bi or Sb or an expensive material such as Li, Ta or Nb, which poses a problem in terms of cost.
  • an object of the present invention is to provide a drive method, a drive circuit, and a displacement drive device capable of maximizing the displacement amount of the dielectric element within a range that does not impair the reliability. be.
  • the driving method is applied between the positive electrode and the negative voltage of the dielectric element in which the positive voltage and the negative voltage face each other via ceramics exhibiting an electric field-induced strain.
  • a drive voltage waveform having a predetermined drive frequency wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is a voltage between 0 V and the breakdown voltage of the ceramics at the drive frequency.
  • the second drive maximum voltage, which is the other peak voltage of the drive voltage waveform is a voltage between 0.1 times and 0.8 times the coercive electric field of the ceramics in a polarity opposite to the first drive maximum voltage.
  • the drive voltage waveform is applied between the positive electrode and the negative voltage.
  • the drive voltage amplitude can be increased by oscillating a voltage within a range that does not exceed the coercive electric field even in the opposite type to the main drive side, and the variation characteristics due to the imprint effect are reduced. Can be prevented. Therefore, the displacement amount of the dielectric element can be maximized without impairing the drive stability and the drive reliability. Further, in this driving method, ceramics that exhibit electric field-induced strain can be used as the material of the dielectric element, and it is not necessary to use a material having high piezoelectricity and high ferroelectricity, so that the environmental load and the cost load are reduced. It is possible to do.
  • the ceramics may have a coercive electric field of less than 1 kV / mm or a Curie temperature of less than 300 ° C.
  • the drive voltage waveform may be a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave, or a burst wave thereof.
  • the drive circuit according to one embodiment of the present invention is applied between the positive electrode and the negative voltage of the dielectric element in which the positive voltage and the negative voltage face each other via ceramics exhibiting an electric field-induced strain.
  • a drive voltage waveform having a predetermined drive frequency wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is a voltage between 0 V and the breakdown voltage of the ceramics at the drive frequency.
  • the second drive maximum voltage which is the other peak voltage of the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the ceramics in a polarity opposite to the first drive maximum voltage.
  • the drive voltage waveform is generated and applied between the positive electrode and the negative voltage.
  • the ceramics may have a coercive electric field of less than 1 kV / mm or a Curie temperature of less than 300 ° C.
  • the displacement drive device includes a dielectric element, a drive object, and a drive circuit.
  • the positive electrode and the negative electrode face each other via ceramics that exhibit electric field-induced strain.
  • the dielectric element is bonded to the driving object.
  • the drive circuit is a drive voltage waveform that is applied between the positive and negative electrodes and has a predetermined drive frequency, and the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is 0 V.
  • the voltage during the breakdown voltage of the ceramics at the drive frequency, and the second drive maximum voltage, which is the other peak voltage of the drive voltage waveform has the polarity opposite to that of the first drive maximum voltage of the ceramics.
  • a drive voltage waveform which is a voltage between 0.1 and 0.8 times the coercive voltage, is generated and applied between the positive and negative electrodes.
  • the ceramics may have a coercive electric field of less than 1 kV / mm or a Curie temperature of less than 300 ° C.
  • the dielectric element and the driving object may form an actuator.
  • the driving method is applied between the positive electrode and the negative voltage of a piezoelectric element in which the positive electrode and the negative voltage face each other via a piezoelectric material made of a piezoelectric material, and is predetermined.
  • a drive voltage waveform having a drive frequency wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is a voltage between 0 V and the breakdown voltage of the piezoelectric body at the drive frequency.
  • the second drive maximum voltage which is the other peak voltage of the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the piezoelectric material in a polarity opposite to the first drive maximum voltage.
  • the drive voltage waveform is applied between the positive electrode and the negative electrode.
  • the drive voltage waveform may be a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave, or a burst wave thereof.
  • the drive circuit according to one embodiment of the present invention is applied between the positive voltage and the negative voltage of the piezoelectric element in which the positive voltage and the negative voltage face each other via a piezoelectric material made of a piezoelectric material, and is predetermined.
  • a drive voltage waveform having a drive frequency wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is a voltage between 0 V and the breakdown voltage of the piezoelectric body at the drive frequency.
  • the second drive maximum voltage, which is the other peak voltage of the drive voltage waveform is a voltage between 0.1 times and 0.8 times the coercive electric field of the piezoelectric material in a polarity opposite to the first drive maximum voltage.
  • the drive voltage waveform is generated and applied between the positive electrode and the negative voltage.
  • the displacement drive device includes a piezoelectric element, a vibrating body, and a drive circuit.
  • the piezoelectric element the positive electrode and the negative electrode face each other via a piezoelectric body made of a piezoelectric material.
  • the piezoelectric element is joined to the vibrating body.
  • the drive circuit is a drive voltage waveform that is applied between the positive and negative electrodes and has a predetermined drive frequency, and the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is 0 V.
  • the second drive maximum voltage which is the voltage between the breakdown voltage of the piezoelectric body at the drive frequency and is the other peak voltage of the drive voltage waveform, has the same polarity as the first drive maximum voltage.
  • a drive voltage waveform which is a voltage between 0.1 and 0.8 times the coercive voltage of the material, is generated and applied between the positive and negative electrodes.
  • the piezoelectric element and the vibrating body constitute a piezoelectric actuator, and the vibrating body may generate a tactile sensation in the vibrating body.
  • the displacement drive device includes a vibration generator.
  • FIG. 1 is a schematic diagram of a displacement drive device 100 according to the present embodiment.
  • the displacement drive device 100 includes a piezoelectric actuator 101 and a drive circuit 102.
  • the piezoelectric actuator 101 is a unimorph type piezoelectric actuator composed of a vibrating body 103 and a piezoelectric element 104.
  • the vibrating body 103 presents a tactile sensation to the user who touches the vibrating body 103.
  • the vibrating body 103 can be a plate-shaped member made of a metal, glass, resin material, or the like, and is, for example, a liquid crystal panel, a housing of an electronic device, or the like.
  • the shape and size of the vibrating body 103 are not particularly limited.
  • the piezoelectric element 104 is joined to the vibrating body 103 to generate vibration.
  • FIG. 2 is a cross-sectional view of the piezoelectric element 104.
  • the piezoelectric element 104 includes a piezoelectric body 111, a positive electrode 112, and a negative electrode 113.
  • the piezoelectric material 111 is made of a piezoelectric material such as PZT (lead zirconate titanate).
  • the positive electrode 112 includes a positive electrode internal electrode 114 and a positive electrode external electrode 115.
  • the positive electrode internal electrode 114 is made of a conductive material, and a plurality of layers are provided in the piezoelectric material 111.
  • the positive electrode external electrode 115 is made of a conductive material, is formed on the surface of the piezoelectric material 111, and is connected to the positive electrode internal electrode 114.
  • the negative electrode 113 includes a negative electrode internal electrode 116 and a negative electrode external electrode 117.
  • the negative electrode internal electrode 116 is made of a conductive material, and a plurality of layers are provided in the piezoelectric material 111.
  • the negative electrode external electrode 117 is made of a conductive material, is formed on the surface of the piezoelectric material 111, and is connected to the negative electrode internal electrode 116.
  • the positive electrode internal electrodes 114 and the negative electrode internal electrodes 116 are alternately arranged and face each other via the piezoelectric material 111.
  • the positive electrode external electrode 115 and the negative electrode external electrode 117 are provided apart from each other on the front surface and the back surface of the piezoelectric element 104.
  • a positive electrode wiring 105 is connected to the positive electrode external electrode 115, and the positive electrode external electrode 115 functions as a positive electrode terminal.
  • the negative electrode wiring 106 is connected to the negative electrode external electrode 117, and the negative electrode external electrode 117 functions as a negative electrode terminal.
  • the piezoelectric element 104 when a voltage is applied between the positive electrode 112 and the negative electrode 113, the piezoelectric body 111 is deformed due to the inverse piezoelectric effect, and vibration occurs.
  • the piezoelectric element 104 may have a laminated structure in which a positive electrode 112 and a negative electrode 113 are alternately laminated via a piezoelectric material 111, or may have another structure.
  • the piezoelectric element 104 can be joined to the vibrating body 103 with a resin or the like. Further, two or more piezoelectric elements 104 may be joined to the vibrating body 103.
  • the drive circuit 102 is connected to the piezoelectric element 104 via the positive electrode wiring 105 and the negative electrode wiring 106, and supplies a drive signal to the piezoelectric element 104. Specifically, the drive circuit 102 generates a drive voltage waveform described later and supplies it between the positive electrode 112 and the negative electrode 113.
  • the displacement drive device 100 has the above configuration.
  • the displacement drive device 100 can be mounted on various electronic devices such as smartphones and tactile function devices.
  • the drive voltage waveform generated by the drive circuit 102 will be described.
  • the drive voltage waveform generated by the drive circuit 102 is a voltage in which the first drive maximum voltage, which is one of the peak voltages, is between 0 V and the breakdown voltage (dielectric breakdown voltage) of the piezoelectric material 111 at the drive frequency.
  • the second drive maximum voltage which is the other peak voltage of the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the piezoelectric material in the polarity opposite to the first drive maximum voltage. ..
  • FIG. 3 is a drive voltage waveform generated by the drive circuit 102. As shown in FIG. 3, in this drive voltage waveform, one peak voltage and the other peak voltage have opposite polarities, the positive peak voltage is the first drive maximum voltage Vp +, and the negative peak voltage is the second. The maximum drive voltage is Vp-.
  • the breakdown voltage of the piezoelectric material 111 at the frequency (drive frequency) of the drive voltage waveform is defined as the breakdown voltage BV
  • the breakdown voltage BV on the plus side is defined as BV + as shown in FIG.
  • the coercive electric field of the piezoelectric material constituting the piezoelectric body 111 is defined as the coercive electric field Ec.
  • the positive field Ec is defined as the negative field Ec +
  • the negative field Ec is defined as the negative field Ec-.
  • the drive voltage waveform generated by the drive circuit 102 is a voltage in which the first drive maximum voltage Vp + is larger than 0 V and the breakdown voltage is less than BV +. Further, the second drive maximum voltage Vp-is 0.8 times or more and 0.1 times or less the coercive electric field Ec-. That is, the first drive maximum voltage Vp + and the second drive maximum voltage Vp- satisfy the following (Equation 1) and (Equation 2).
  • Vp +> Ec + is suitable for increasing the displacement amount of the piezoelectric element 104.
  • FIG. 3 shows a drive voltage waveform in which the polarization direction is on the plus side (> 0V), the polarization direction may be on the minus side ( ⁇ 0V).
  • FIG. 4 is a drive voltage waveform generated by the drive circuit 102 in which the polarization direction is on the minus side.
  • the negative peak voltage is the first drive maximum voltage Vp-
  • the positive peak voltage is set.
  • the second drive maximum voltage is Vp +.
  • the breakdown voltage BV on the negative side is defined as BV ⁇ .
  • the positive field Ec is defined as the negative field Ec +
  • the negative field Ec is defined as the negative field Ec-.
  • the first drive maximum voltage Vp- is larger than the breakdown voltage BV- and is less than 0V.
  • the second drive maximum voltage Vp + is 0.1 times or more and 0.8 times or less the coercive electric field Ec +. That is, the first drive maximum voltage Vp- and the second drive maximum voltage Vp + satisfy the following (Equation 3) and (Equation 4).
  • Vp- ⁇ Ec- is suitable for increasing the displacement amount of the piezoelectric element 104.
  • the drive circuit 102 generates the drive voltage waveform shown in FIG. 3 or 4, and supplies the drive voltage waveform between the positive electrode 112 and the negative electrode 113 via the positive electrode wiring 105 and the negative electrode wiring 106.
  • the drive voltage waveform generated by the drive circuit 102 is not limited to the sine wave as shown in FIGS. 3 and 4, and may be any one in which the first drive maximum voltage and the second drive maximum voltage satisfy the above conditions.
  • the drive voltage waveform generated by the drive circuit 102 may be a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave, or a burst wave thereof.
  • FIG. 5 is a graph showing a driving voltage waveform of bipolar driving, which is a conventional driving voltage waveform.
  • FIG. 6 is a graph showing a drive voltage waveform of unipolar drive, which is a conventional drive voltage waveform.
  • the entire drive voltage waveform is on the plus side of 0V, but the whole may be on the minus side of 0V.
  • the dielectric constant at the time of driving decreases due to the imprint effect by continuing to drive with a voltage biased to the plus side or the minus side, and the displacement characteristic deteriorates by continuing to drive. ..
  • the drive voltage waveform (see FIGS. 3 and 4) generated by the drive circuit 102 according to the present embodiment oscillates a voltage within a range not exceeding the coercive electric field Ec even in the opposite type to the main drive side.
  • This makes it possible to increase the drive voltage amplitude Vp-p and prevent deterioration of the variable characteristics due to the imprint effect. Therefore, the displacement amount of the piezoelectric element 104 can be maximized without impairing the drive stability and the drive reliability.
  • the second drive maximum voltage Vp is preferably a voltage between 0.1 times and 0.8 times the coercive electric field Ec, but the second drive maximum voltage Vp is 0.1 of the coercive electric field Ec. If it is smaller than twice, the imprint effect will occur as in the case of unipolar drive. Further, when the second drive maximum voltage Vp exceeds 0.8 times the coercive electric field Ec, depolarization and deterioration of the insulating property occur. Therefore, the second drive maximum voltage Vp is preferably a voltage between 0.1 times and 0.8 times the coercive electric field Ec.
  • the displacement drive device includes a vibration generator.
  • FIG. 7 is a schematic view of the displacement drive device 200 according to the present embodiment.
  • the displacement drive device 200 includes an actuator 201 and a drive circuit 202.
  • the actuator 201 is a unimorph type piezoelectric actuator composed of a drive object 203 and a dielectric element 204.
  • the drive object 203 is, for example, a diaphragm, and presents a tactile sensation to a user who touches the drive object 203.
  • the drive object 203 can be a plate-shaped member made of a metal, glass, resin material, or the like, and is, for example, a liquid crystal panel, a housing of an electronic device, or the like.
  • the shape and size of the drive object 203 are not particularly limited.
  • the dielectric element 204 is joined to the drive target object 203 to drive the drive target object 203.
  • the dielectric element 204 can generate vibration in, for example, the driven object 203.
  • FIG. 8 is a cross-sectional view of the dielectric element 204.
  • the dielectric element 204 includes a dielectric 211, a positive electrode 212, and a negative electrode 213.
  • the dielectric 211 is made of a dielectric material, specifically ceramics that exhibit electric field-induced strain.
  • the ceramics may have a coercive electric field Ec of less than 1 kV / mm or a Curie temperature Tc of less than 300 ° C. as long as they are accompanied by the development of electric field-induced strain.
  • Examples of such a material include BT (BaTIO 3 ) (see Examples).
  • the dielectric material constituting the dielectric 211 is preferably a ferroelectric material, but may be a material close to a normal dielectric as long as it is a material accompanied by the development of electric field-induced strain.
  • the positive electrode 212 includes a positive electrode internal electrode 214 and a positive electrode external electrode 215.
  • the positive electrode internal electrode 214 is made of a conductive material, and a plurality of layers are provided in the dielectric 211.
  • the positive electrode external electrode 215 is made of a conductive material, is formed on the surface of the dielectric 211, and is connected to the positive electrode internal electrode 214.
  • the negative electrode 213 includes a negative electrode internal electrode 216 and a negative electrode external electrode 217.
  • the negative electrode internal electrode 216 is made of a conductive material, and a plurality of layers are provided in the dielectric 211.
  • the negative electrode external electrode 217 is made of a conductive material, is formed on the surface of the dielectric 211, and is connected to the negative electrode internal electrode 216.
  • the positive electrode internal electrode 214 and the negative electrode internal electrode 216 are alternately arranged and face each other via the dielectric 211.
  • the positive electrode external electrode 215 and the negative electrode external electrode 217 are provided apart from each other on the front surface and the back surface of the dielectric element 204.
  • the positive electrode wiring 205 is connected to the positive electrode external electrode 215, and the positive electrode external electrode 215 functions as a positive electrode terminal.
  • the negative electrode wiring 206 is connected to the negative electrode external electrode 217, and the negative electrode external electrode 217 functions as a negative electrode terminal.
  • the dielectric element 204 when a voltage is applied between the positive electrode 212 and the negative electrode 213, the dielectric 211 is deformed due to the electric field-induced strain.
  • the dielectric element 204 may have a laminated structure in which a positive electrode 212 and a negative electrode 213 are alternately laminated via a dielectric 211, or may have another structure. ..
  • the dielectric element 204 may be joined to the drive object 203 by a resin or the like. Further, two or more dielectric elements 204 may be joined to the driving object 203.
  • the drive circuit 202 is connected to the piezoelectric element 204 via the positive electrode wiring 205 and the negative electrode wiring 206, and supplies a drive signal to the piezoelectric element 204. Specifically, the drive circuit 202 generates a drive voltage waveform described later and supplies it between the positive electrode 212 and the negative electrode 213.
  • the displacement drive device 200 has the above configuration.
  • the displacement drive device 200 can be mounted on various electronic devices such as smartphones and tactile function devices.
  • the drive voltage waveform generated by the drive circuit 202 will be described.
  • the drive voltage waveform generated by the drive circuit 202 can be the same as in the first embodiment. That is, the drive voltage waveform generated by the drive circuit 202 satisfies the above (Equation 1) and (Equation 2) when the polarization direction is the plus side (> 0V) (see FIG. 3), and the polarization direction is the minus side ( ⁇ 0V). In the case of, it is possible to satisfy the above (Equation 3) and (Equation 4) (see FIG. 4).
  • the drive circuit 202 generates the drive voltage waveform shown in FIG. 3 or 4, and supplies the drive voltage waveform between the positive electrode 212 and the negative electrode 213 via the positive electrode wiring 205 and the negative electrode wiring 206.
  • the drive voltage waveform generated by the drive circuit 202 is not limited to the sine wave as shown in FIGS. 3 and 4, and the first drive maximum voltage and the second drive maximum voltage may satisfy the above conditions.
  • the drive voltage waveform generated by the drive circuit 202 may be a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave, or a burst wave thereof.
  • the drive circuit 202 In the displacement drive device 200, the drive circuit 202 generates the drive voltage waveform (see FIGS. 3 and 4) as described above and supplies it to the dielectric element 204. Similar to the first embodiment, the drive voltage amplitude Vp-p can be increased and imprinted by applying a voltage in a range not exceeding the coercive electric field Ec in the opposite type to the main drive side. It is possible to prevent the deterioration of the variable characteristics due to the effect. Therefore, the displacement amount of the piezoelectric element 204 can be maximized without impairing the drive stability and the drive reliability.
  • the conditions of the dielectric material forming the dielectric 211 can be expanded by using the drive voltage waveform (see FIGS. 3 and 4) as described above.
  • the dielectric material generally required for the piezoelectric actuator it is necessary to use a material having a Curie temperature Tc of 300 ° C. or higher, a coercive electric field Ec of 1 kV / mm, and reflow resistance and bipolar drive performance.
  • FIG. 9 shows an example of a PE hysteresis loop of a dielectric material generally required for a piezoelectric actuator, in which the horizontal axis is an electric field (P) and the vertical axis is polarization (E).
  • the material in the displacement drive device 200, by using the drive voltage waveform as described above, if the material is accompanied by the occurrence of electric field-induced strain, ceramics having a coercive electric field Ec of less than 1 kV / mm or a Curie temperature Tc of less than 300 ° C. can be used. It can be used as a material for the dielectric 211. Further, the material of the dielectric 211 does not require high ferroelectricity as shown in FIG. FIG. 10 is an example of a PE hysteresis loop of the dielectric material constituting the dielectric 211, in which the horizontal axis is the electric field (P) and the vertical axis is the polarization (E).
  • the dielectric material of a commonly used piezoelectric actuator requires polarization processing by DC polarization.
  • polarization processing a difference in the degree of polarization, that is, a difference in the degree of rotation of the polarization phase is likely to occur, the displacement characteristics are likely to vary, and a polarization device having a complicated mechanism for making the degree of polarization uniform is required.
  • the burden on costs is also great.
  • the polarization treatment becomes unnecessary by using the ceramics accompanied by the development of the electric field-induced strain as the material of the dielectric 211. This is because the electrolysis-induced strain develops regardless of the presence or absence of polarization.
  • the piezoelectric element 204 may also be prepolarized for performance inspection or the like.
  • a material that does not have high piezoelectricity or high ferroelectricity can be used as the material of the dielectric 211, and the environment is higher than that of the dielectric material generally required for the piezoelectric actuator. It is possible to select a dielectric material with a low load and cost load. Further, since the dielectric element 204 does not require a polarization treatment, a complicated and effective polarization device and a polarization treatment step are not required, and it is possible to improve the production tact and suppress the production equipment cost. Further, since the inspection for confirming the degree of polarization is not required, the inspection process can be reduced.
  • the unimorph type piezoelectric actuator 101 (see FIG. 1) according to the first embodiment was manufactured.
  • the vibrating body 103 is a plate made of stainless steel, and has a length of 40 mm, a width of 15 mm, and a thickness of 0.3 mm.
  • the piezoelectric element 104 had a length of 30 mm, a width of 15 mm, and a thickness of 0.3 mm, and was bonded to the vibrating body 103 with a resin adhesive.
  • the coercive electric field Ec of the piezoelectric material constituting the piezoelectric body 111 was 1.1 kV / mm, and the breakdown voltage of the piezoelectric element 104 was 9.5 kV / mm.
  • FIG. 11 is a schematic diagram showing a displacement measurement method of the piezoelectric actuator.
  • the fixing portion 302 and the fixing portion 303 are provided on the fixed substrate 301, and both ends of the vibrating body 103 are fixed to the fixing portion 302 and the fixing portion 303, respectively.
  • the free length of the vibrating body 103 is shown as the free length L.
  • the bending displacement of the central portion (1 / 2L) of the vibrometer 103 was measured by a laser Doppler vibrometer (LDV) 304.
  • LUV laser Doppler vibrometer
  • [Table 1] is a table showing the measurement results.
  • the drive waveform is a sine wave, the drive frequency is 100 Hz, the first drive maximum voltage Vp +: 3.5 kV / mm, the second drive maximum voltage Vp-: ⁇ 0.8 kV / mm, Vp-p: 4. It was set to 3 kV / mm.
  • the first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm).
  • the second drive maximum voltage Vp- is a voltage between 0.1 times and 0.8 times the coercive electric field Ec-( ⁇ 1.1 kV / mm).
  • the displacement measurement result by the laser Doppler vibrometer 304 was 26.5 ⁇ m. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was -1%, and very high characteristic stability was obtained. As described above, in Example 1, both the displacement amount and the characteristic stability were good.
  • the drive waveform is a sine wave
  • the drive frequency is 100 Hz
  • the first drive maximum voltage Vp + 5 kV / mm
  • the second drive maximum voltage Vp- ⁇ 0.8 kV / mm
  • Vp-p 5.8 kV /. It was set to mm.
  • the first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm).
  • the second drive maximum voltage Vp- is a voltage between 0.1 times and 0.8 times the coercive electric field Ec-( ⁇ 1.1 kV / mm).
  • the displacement measurement result by the laser Doppler vibrometer 304 was 32.8 ⁇ m. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was -2%, and high characteristic stability was obtained. As described above, in Example 2, both the displacement amount and the characteristic stability were good.
  • the drive waveform is a sine wave, the drive frequency is 100 Hz, the first drive maximum voltage Vp +: 8 kV / mm, the second drive maximum voltage Vp-: ⁇ 0.8 kV / mm, Vp-p: 8.8 kV /. It was set to mm.
  • the first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm).
  • the second drive maximum voltage Vp- is a voltage between 0.1 times and 0.8 times the coercive electric field Ec-( ⁇ 1.1 kV / mm).
  • the displacement measurement result by the laser Doppler vibrometer 304 was 45.4 ⁇ m. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was -4%, and high characteristic stability was obtained. As described above, in Example 3, both the displacement amount and the characteristic stability were good.
  • the drive waveform is a sine wave and the drive frequency is 100 Hz.
  • the first drive maximum voltage Vp + 3.5 kV / mm
  • the second drive maximum voltage Vp- 0 kV / mm
  • Vp-p 3.5 kV / mm.
  • the first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm).
  • the second drive maximum voltage Vp- is not a voltage between 0.1 times and 0.8 times the coercive electric field Ec-( ⁇ 1.1 kV / mm), but a voltage larger than 0.1 times.
  • the displacement measurement result by the laser Doppler vibrometer 304 was 23.1 ⁇ m. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was ⁇ 7%, and the characteristic stability was low. As described above, in Comparative Example 1, although the displacement amount was good, the characteristic stability was insufficient.
  • the drive waveform is a sine wave and the drive frequency is 100 Hz.
  • the first drive maximum voltage Vp + 1 kV / mm
  • the second drive maximum voltage Vp- -1 kV / mm
  • Vp-p 2 kV / mm.
  • the first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm).
  • the second drive maximum voltage Vp- is not a voltage between 0.1 times and 0.8 times the coercive electric field Ec-( ⁇ 1.1 kV / mm), but a voltage smaller than 0.8 times.
  • the displacement measurement result by the laser Doppler vibrometer 304 was 16.8 ⁇ m. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was 0%, and high characteristic stability was obtained. As described above, in Comparative Example 2, although the characteristic stability was good, the displacement amount was insufficient.
  • the drive waveform is a sine wave and the drive frequency is 100 Hz.
  • the first drive maximum voltage Vp + 8 kV / mm
  • the second drive maximum voltage Vp- 0 kV / mm
  • Vp-p 8 kV / mm.
  • the first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm).
  • the second drive maximum voltage Vp- is not a voltage between 0.1 times and 0.8 times the coercive electric field Ec-( ⁇ 1.1 kV / mm), but a voltage larger than 0.1 times.
  • the displacement measurement result by the laser Doppler vibrometer 304 was 41.3 ⁇ m. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was -12%, and the characteristic stability was low. As described above, in Comparative Example 3, although the displacement amount was good, the characteristic stability was insufficient.
  • the drive waveform is a sine wave and the drive frequency is 100 Hz.
  • the first drive maximum voltage Vp + 10 kV / mm
  • the second drive maximum voltage Vp- 0 kV / mm
  • Vp-p 10 kV / mm.
  • the first drive maximum voltage Vp + is not a voltage between 0 V and the breakdown voltage (9.5 kV / mm), but a voltage larger than the breakdown voltage.
  • the second drive maximum voltage Vp- is not a voltage between 0.1 times and 0.8 times the coercive electric field Ec-( ⁇ 1.1 kV / mm), but a voltage larger than 0.1 times.
  • the dielectric element 204 (see FIG. 8) according to the second embodiment was manufactured.
  • the dielectric element 204 is formed by alternately laminating 10 layers of a positive electrode internal electrode 214 and a negative electrode internal electrode 216 of a dielectric having a thickness of 26 ⁇ m per layer, and has a 3216 shape.
  • a dielectric element 204 made of various dielectric materials was produced, and the dielectric element 204 was driven by the above-mentioned drive voltage waveform (drive voltage -2 V to + 104 V, drive frequency 10 Hz, see FIG. 3).
  • drive voltage -2 V to + 104 V drive frequency 10 Hz, see FIG. 3
  • a laser Doppler vibrometer a laser was irradiated from above the dielectric element 204 (Z direction, see FIG.
  • the “material” in the above [Table 2] is a dielectric material constituting the dielectric 211 of the dielectric element 204 in each embodiment.
  • the following [Table 3] is a table showing the composition of BT1 according to Examples 4 and 5 and the composition of BT2 according to Example 6.
  • the following [Table 4] is a table showing the composition of LNKN1 according to Example 7.
  • the composition of PZT1 according to Example 8 is PZT-PZN (Pb (Zr 1/2 Ti 1/2 ) O 3- Pb (Zn 1/3 Nb 2/3 ) O 3 ).
  • the dielectric element 204 according to Examples 4, 7 and 8 was polarized at 25 ° C., 3.5 kV / mm, and 15 min, and displacement was measured. On the other hand, the displacement of the dielectric element 204 according to Examples 5 and 6 was measured in a non-polarized state.
  • both LNKN1 according to Example 7 and PZT1 according to Example 8 are materials having a Curie temperature Tc of 300 ° C. or higher and a coercive electric field Ec of 1 kV / mm or higher.
  • the displacement amount d33 * was 190 pm / V
  • the displacement amount d33 * was 450 pm / V.
  • BT1 and BT2 according to Example 4-6 are materials having a Curie temperature Tc of less than 300 ° C. and a coercive electric field Ec of less than 1 kV / mm.
  • the displacement amount d33 * was 370 pm / V
  • the displacement amount d33 * was 390 pm / V. Therefore, even if the material has a Curie temperature Tc of less than 300 ° C. and a coercive electric field Ec of less than 1 kV / mm, the displacement is comparable to that of a material having a Curie temperature Tc of 300 ° C. or more and a coercive electric field Ec of 1 kV / mm or more. The amount was obtained.
  • Example 4-6 even if the dielectric element 204 is in the unpolarized state, the same amount of displacement as in the polarized state can be obtained. Therefore, the dielectric element 204 does not require a polarization process.

Abstract

[Problem] To provide a drive method, a drive circuit, and a displacement drive device with which it is possible to maximize the amount of displacement of a dielectric element within a range that does not compromise reliability. [Solution] The drive method according to the present technology involves applying, between a positive electrode and a negative electrode of a dielectric element in which the positive electrode and the negative electrode face each other across a ceramic that exhibits electric-field-induced strain, a drive voltage waveform that has a prescribed drive frequency and that is applied between the positive electrode and the negative electrode, the drive voltage waveform being one in which: a first drive maximum voltage, which is one peak voltage in the drive voltage waveform, is a voltage between 0 V and the breakdown voltage of the ceramic in the drive frequency; and a second drive maximum voltage, which is another peak voltage in the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the ceramic at the polarity opposite that of the first drive maximum voltage.

Description

駆動方法、駆動回路及び変位駆動装置Drive method, drive circuit and displacement drive device
　本発明は、誘電体素子の駆動方法、駆動回路及び変位駆動装置に関する。 The present invention relates to a method for driving a dielectric element, a drive circuit, and a displacement drive device.
　電装用タッチパネルに代表される触覚技術を用いたパネル等において、パネル上にあたかもボタンがあるように感じる技術や、運転中にパネルを目視することなく触覚によりボタンの位置を把握できる技術が注目を集めている。 In panels that use tactile technology such as touch panels for electrical equipment, attention is focused on technology that makes the panel feel as if there is a button on the panel, and technology that allows the position of the button to be grasped by tactile sensation without visually observing the panel while driving. I'm collecting.
　これらの技術において触覚を発生させるための振動デバイスには、電磁式の偏心モータやＬＲＡ（Linear Resonant Actuator）、圧電アクチュエータ等が用いられている。圧電アクチュエータは応答速度が速い特性から、対応可能な駆動周波数が広く、多彩な触覚を表現できることから、次世代の触覚用モジュール部品として特に注目を集めている（例えば、特許文献１）。 In these technologies, electromagnetic eccentric motors, LRAs (Linear Resonant Actuators), piezoelectric actuators, etc. are used as vibration devices for generating tactile sensations. Piezoelectric actuators are attracting particular attention as next-generation tactile module components because they have a high response speed, a wide range of drive frequencies that can be handled, and can express a variety of tactile sensations (for example, Patent Document 1).
特開２００１－１９７７６２号公報Japanese Unexamined Patent Publication No. 2001-197762
　従来、圧電アクチュエータの駆動振幅は電磁式に比べて小さく、駆動振幅を大きくするためには圧電素子の駆動電圧を大きくする必要であった。しかしながら、バイポーラ（双極性）駆動では抗電界の制約があり、駆動電圧振幅を抗電界以上に大きくした場合、脱分極する問題があった。また、分極方向へのユニポーラ（単極性）駆動では、抗電界の影響を受けないものの、駆動電圧振幅を過剰に上げた場合に信頼性を損ねるという問題や、駆動回数に応じて変位が小さくなるという問題があった。 Conventionally, the drive amplitude of the piezoelectric actuator is smaller than that of the electromagnetic type, and in order to increase the drive amplitude, it is necessary to increase the drive voltage of the piezoelectric element. However, in bipolar (bipolar) drive, there is a limitation of the coercive electric field, and there is a problem of depolarization when the drive voltage amplitude is made larger than the coercive electric field. In addition, in unipolar drive in the polarization direction, although it is not affected by the coercive electric field, there is a problem that reliability is impaired when the drive voltage amplitude is excessively increased, and the displacement becomes smaller depending on the number of drives. There was a problem.
　さらに、圧電材料として代表的なＰＺＴ（チタン酸ジルコン酸鉛）は圧電特性が高い一方で、環境への配慮から鉛を含まない非鉛への置き換えも検討されている。環境面において懸案される。一方、鉛を含まない圧電材料はＢｉやＳｂ等の規制物質やＬｉ、Ｔａ又はＮｂ等の高価な材料を必要とし、コスト面が問題となる。 Furthermore, while PZT (lead zirconate titanate), which is a typical piezoelectric material, has high piezoelectric characteristics, replacement with lead-free lead-free is being considered in consideration of the environment. It is an environmental concern. On the other hand, the lead-free piezoelectric material requires a regulated substance such as Bi or Sb or an expensive material such as Li, Ta or Nb, which poses a problem in terms of cost.
　以上のような事情に鑑み、本発明の目的は、誘電体素子の変位量を、信頼性を損ねない範囲で最大化することが可能な駆動方法、駆動回路及び変位駆動装置を提供することにある。 In view of the above circumstances, an object of the present invention is to provide a drive method, a drive circuit, and a displacement drive device capable of maximizing the displacement amount of the dielectric element within a range that does not impair the reliability. be.
　上記目的を達成するため、本発明の一形態に係る駆動方法は、電界誘起歪を発現するセラミックスを介して正極と負極が対向する誘電体素子の、上記正極と上記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、上記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと上記駆動周波数における上記セラミックスのブレークダウン電圧の間の電圧であり、上記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、上記第１駆動最大電圧と反対の極性において上記セラミックスの抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を上記正極と上記負極の間に印加する。 In order to achieve the above object, the driving method according to one embodiment of the present invention is applied between the positive electrode and the negative voltage of the dielectric element in which the positive voltage and the negative voltage face each other via ceramics exhibiting an electric field-induced strain. A drive voltage waveform having a predetermined drive frequency, wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is a voltage between 0 V and the breakdown voltage of the ceramics at the drive frequency. The second drive maximum voltage, which is the other peak voltage of the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the ceramics in a polarity opposite to the first drive maximum voltage. The drive voltage waveform is applied between the positive electrode and the negative voltage.
　この駆動方法によれば、主に駆動する側とは反対型にも抗電界を超えない範囲で電圧を振ることによって、駆動電圧振幅を大きくすることができ、かつインプリント効果による変特性の低下を防止することが可能となる。したがって、駆動安定性や駆動信頼性を損ねずに、誘電体素子の変位量を最大化することができる。また、この駆動方法では、誘電体素子の材料として電界誘起歪を発現するセラミックス用いることができ、高い圧電性や高い強誘電性を有する材料を用いる必要がないため、環境負荷やコスト負荷を低減することが可能である。 According to this drive method, the drive voltage amplitude can be increased by oscillating a voltage within a range that does not exceed the coercive electric field even in the opposite type to the main drive side, and the variation characteristics due to the imprint effect are reduced. Can be prevented. Therefore, the displacement amount of the dielectric element can be maximized without impairing the drive stability and the drive reliability. Further, in this driving method, ceramics that exhibit electric field-induced strain can be used as the material of the dielectric element, and it is not necessary to use a material having high piezoelectricity and high ferroelectricity, so that the environmental load and the cost load are reduced. It is possible to do.
　上記セラミックスは、抗電界が１ｋＶ／ｍｍ未満又はキュリー温度が３００℃未満であってもよい。 The ceramics may have a coercive electric field of less than 1 kV / mm or a Curie temperature of less than 300 ° C.
　駆動電圧波形は、正弦波、三角波、ハーバーサイン波、ガウシアン波又はこれらのバースト波であってもよい。 The drive voltage waveform may be a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave, or a burst wave thereof.
　上記目的を達成するため、本発明の一形態に係る駆動回路は、電界誘起歪を発現するセラミックスを介して正極と負極が対向する誘電体素子の、上記正極と上記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、上記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと上記駆動周波数における上記セラミックスのブレークダウン電圧の間の電圧であり、上記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、上記第１駆動最大電圧と反対の極性において上記セラミックスの抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を生成し、上記正極と上記負極の間に印加する。 In order to achieve the above object, the drive circuit according to one embodiment of the present invention is applied between the positive electrode and the negative voltage of the dielectric element in which the positive voltage and the negative voltage face each other via ceramics exhibiting an electric field-induced strain. A drive voltage waveform having a predetermined drive frequency, wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is a voltage between 0 V and the breakdown voltage of the ceramics at the drive frequency. The second drive maximum voltage, which is the other peak voltage of the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the ceramics in a polarity opposite to the first drive maximum voltage. The drive voltage waveform is generated and applied between the positive electrode and the negative voltage.
　上記セラミックスは、抗電界が１ｋＶ／ｍｍ未満又はキュリー温度が３００℃未満であってもよい。 The ceramics may have a coercive electric field of less than 1 kV / mm or a Curie temperature of less than 300 ° C.
　上記目的を達成するため、本発明の一形態に係る変位駆動装置は、誘電体素子と、駆動対象物と、駆動回路とを具備する。
　上記誘電体素子は、電界誘起歪を発現するセラミックスを介して正極と負極が対向する。
　上記駆動対象物は、上記誘電体素子が接合されている。
　上記駆動回路は、上記正極と上記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、上記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと上記駆動周波数における上記セラミックスのブレークダウン電圧の間の電圧であり、上記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、上記第１駆動最大電圧と反対の極性において上記セラミックスの抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を生成し、上記正極と上記負極の間に印加する。 In order to achieve the above object, the displacement drive device according to one embodiment of the present invention includes a dielectric element, a drive object, and a drive circuit.
In the dielectric element, the positive electrode and the negative electrode face each other via ceramics that exhibit electric field-induced strain.
The dielectric element is bonded to the driving object.
The drive circuit is a drive voltage waveform that is applied between the positive and negative electrodes and has a predetermined drive frequency, and the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is 0 V. The voltage during the breakdown voltage of the ceramics at the drive frequency, and the second drive maximum voltage, which is the other peak voltage of the drive voltage waveform, has the polarity opposite to that of the first drive maximum voltage of the ceramics. A drive voltage waveform, which is a voltage between 0.1 and 0.8 times the coercive voltage, is generated and applied between the positive and negative electrodes.
　上記セラミックスは、抗電界が１ｋＶ／ｍｍ未満又はキュリー温度が３００℃未満であってもよい。 The ceramics may have a coercive electric field of less than 1 kV / mm or a Curie temperature of less than 300 ° C.
　上記誘電体素子及び上記駆動対象物はアクチュエータを構成してもよい。 The dielectric element and the driving object may form an actuator.
　上記目的を達成するため、本発明の一形態に係る駆動方法は、圧電材料からなる圧電体を介して正極と負極が対向する圧電素子の、上記正極と上記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、上記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと上記駆動周波数における上記圧電体のブレークダウン電圧の間の電圧であり、上記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、上記第１駆動最大電圧と反対の極性において上記圧電材料の抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を上記正極と上記負極の間に印加する。 In order to achieve the above object, the driving method according to one embodiment of the present invention is applied between the positive electrode and the negative voltage of a piezoelectric element in which the positive electrode and the negative voltage face each other via a piezoelectric material made of a piezoelectric material, and is predetermined. A drive voltage waveform having a drive frequency, wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is a voltage between 0 V and the breakdown voltage of the piezoelectric body at the drive frequency. The second drive maximum voltage, which is the other peak voltage of the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the piezoelectric material in a polarity opposite to the first drive maximum voltage. The drive voltage waveform is applied between the positive electrode and the negative electrode.
　駆動電圧波形は、正弦波、三角波、ハーバーサイン波、ガウシアン波又はこれらのバースト波であってもよい。 The drive voltage waveform may be a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave, or a burst wave thereof.
　上記目的を達成するため、本発明の一形態に係る駆動回路は、圧電材料からなる圧電体を介して正極と負極が対向する圧電素子の、上記正極と上記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、上記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと上記駆動周波数における上記圧電体のブレークダウン電圧の間の電圧であり、上記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、上記第１駆動最大電圧と反対の極性において上記圧電材料の抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を生成し、上記正極と上記負極の間に印加する。 In order to achieve the above object, the drive circuit according to one embodiment of the present invention is applied between the positive voltage and the negative voltage of the piezoelectric element in which the positive voltage and the negative voltage face each other via a piezoelectric material made of a piezoelectric material, and is predetermined. A drive voltage waveform having a drive frequency, wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is a voltage between 0 V and the breakdown voltage of the piezoelectric body at the drive frequency. The second drive maximum voltage, which is the other peak voltage of the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the piezoelectric material in a polarity opposite to the first drive maximum voltage. The drive voltage waveform is generated and applied between the positive electrode and the negative voltage.
　上記目的を達成するため、本発明の一形態に係る変位駆動装置は、圧電素子と、振動体と、駆動回路とを具備する。
　上記圧電素子は、圧電材料からなる圧電体を介して正極と負極が対向する。
　上記振動体は、上記圧電素子が接合されている。
　上記駆動回路は、上記正極と上記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、上記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと上記駆動周波数における上記圧電体のブレークダウン電圧の間の電圧であり、上記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、上記第１駆動最大電圧と反対の極性において上記圧電材料の抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を生成し、上記正極と上記負極の間に印加する。 In order to achieve the above object, the displacement drive device according to one embodiment of the present invention includes a piezoelectric element, a vibrating body, and a drive circuit.
In the piezoelectric element, the positive electrode and the negative electrode face each other via a piezoelectric body made of a piezoelectric material.
The piezoelectric element is joined to the vibrating body.
The drive circuit is a drive voltage waveform that is applied between the positive and negative electrodes and has a predetermined drive frequency, and the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is 0 V. The second drive maximum voltage, which is the voltage between the breakdown voltage of the piezoelectric body at the drive frequency and is the other peak voltage of the drive voltage waveform, has the same polarity as the first drive maximum voltage. A drive voltage waveform, which is a voltage between 0.1 and 0.8 times the coercive voltage of the material, is generated and applied between the positive and negative electrodes.
　上記圧電素子及び上記振動体は圧電アクチュエータを構成し、上記振動体の振動により、上記振動体に触覚を発生させてもよい。 The piezoelectric element and the vibrating body constitute a piezoelectric actuator, and the vibrating body may generate a tactile sensation in the vibrating body.
　以上のように本発明によれば、誘電体素子の変位量を、信頼性を損ねない範囲で最大化することが可能な駆動方法、駆動回路及び変位駆動装置を提供することができる。 As described above, according to the present invention, it is possible to provide a drive method, a drive circuit, and a displacement drive device capable of maximizing the displacement amount of the dielectric element within a range that does not impair the reliability.
本発明の第１の実施形態に係る変位駆動装置の模式図である。It is a schematic diagram of the displacement drive device which concerns on 1st Embodiment of this invention. 上記変位駆動装置が備える圧電素子の断面図である。It is sectional drawing of the piezoelectric element provided in the said displacement drive device. 上記変位駆動装置が備える駆動回路が生成する駆動電圧波形であIt is a drive voltage waveform generated by the drive circuit provided in the displacement drive device. 上記変位駆動装置が備える駆動回路が生成する駆動電圧波形である。It is a drive voltage waveform generated by the drive circuit provided in the displacement drive device. 従来の圧電素子の動電圧波形であるバイポーラ駆動の駆動電圧波形である。It is a driving voltage waveform of bipolar drive which is a dynamic voltage waveform of a conventional piezoelectric element. 従来の圧電素子の動電圧波形であるユニポーラ駆動の駆動電圧波形である。It is a drive voltage waveform of unipolar drive which is a dynamic voltage waveform of a conventional piezoelectric element. 本発明の第２の実施形態に係る変位駆動装置の模式図である。It is a schematic diagram of the displacement drive device which concerns on 2nd Embodiment of this invention. 上記変位駆動装置が備える誘電体素子の断面図である。It is sectional drawing of the dielectric element provided in the said displacement drive device. 圧電アクチュエータに一般的に必要とされる誘電材料のＰ－Ｅヒステリシスループの例である。This is an example of a PE hysteresis loop of a dielectric material generally required for a piezoelectric actuator. 上記誘電体素子を構成する誘電材料のＰ－Ｅヒステリシスループの例である。This is an example of a PE hysteresis loop of a dielectric material constituting the dielectric element. 本発明の実施例及び比較例に係る圧電アクチュエータの変位計測方法の模式図である。It is a schematic diagram of the displacement measurement method of the piezoelectric actuator which concerns on Example and comparative example of this invention.
　（第１の実施形態）
　本発明の第１の実施形態に係る変位駆動装置について説明する。変位駆動装置は振動発生装置を含む。 (First Embodiment)
The displacement drive device according to the first embodiment of the present invention will be described. The displacement drive device includes a vibration generator.
　［変位駆動装置の構成］
　図１は本実施形態に係る変位駆動装置１００の模式図である。同図に示すように、変位駆動装置１００は、圧電アクチュエータ１０１及び駆動回路１０２を備える。圧電アクチュエータ１０１は振動体１０３と圧電素子１０４から構成されたユニモルフ型圧電アクチュエータである。 [Displacement drive device configuration]
FIG. 1 is a schematic diagram of a displacement drive device 100 according to the present embodiment. As shown in the figure, the displacement drive device 100 includes a piezoelectric actuator 101 and a drive circuit 102. The piezoelectric actuator 101 is a unimorph type piezoelectric actuator composed of a vibrating body 103 and a piezoelectric element 104.
　振動体１０３は、振動体１０３に触れるユーザに触覚を提示する。振動体１０３は金属、ガラス又は樹脂材料等からなる板状の部材とすることができ、例えば、液晶パネルや電子機器の筐体等である。振動体１０３の形状やサイズは特に限定されない。 The vibrating body 103 presents a tactile sensation to the user who touches the vibrating body 103. The vibrating body 103 can be a plate-shaped member made of a metal, glass, resin material, or the like, and is, for example, a liquid crystal panel, a housing of an electronic device, or the like. The shape and size of the vibrating body 103 are not particularly limited.
　圧電素子１０４は、振動体１０３に接合され、振動を発生させる。図２は圧電素子１０４の断面図である。同図に示すように圧電素子１０４は、圧電体１１１、正極１１２及び負極１１３を備える。圧電体１１１はＰＺＴ（チタン酸ジルコン酸鉛）等の圧電材料からなる。 The piezoelectric element 104 is joined to the vibrating body 103 to generate vibration. FIG. 2 is a cross-sectional view of the piezoelectric element 104. As shown in the figure, the piezoelectric element 104 includes a piezoelectric body 111, a positive electrode 112, and a negative electrode 113. The piezoelectric material 111 is made of a piezoelectric material such as PZT (lead zirconate titanate).
　正極１１２は、正極内部電極１１４及び正極外部電極１１５を備える。正極内部電極１１４は導電性材料からなり、圧電体１１１中に複数層が設けられている。正極外部電極１１５は導電性材料からなり、圧電体１１１の表面に形成され、正極内部電極１１４と接続されている。 The positive electrode 112 includes a positive electrode internal electrode 114 and a positive electrode external electrode 115. The positive electrode internal electrode 114 is made of a conductive material, and a plurality of layers are provided in the piezoelectric material 111. The positive electrode external electrode 115 is made of a conductive material, is formed on the surface of the piezoelectric material 111, and is connected to the positive electrode internal electrode 114.
　負極１１３は、負極内部電極１１６及び負極外部電極１１７を備える。負極内部電極１１６は導電性材料からなり、圧電体１１１中に複数層が設けられている。負極外部電極１１７は導電性材料からなり、圧電体１１１の表面に形成され、負極内部電極１１６と接続されている。 The negative electrode 113 includes a negative electrode internal electrode 116 and a negative electrode external electrode 117. The negative electrode internal electrode 116 is made of a conductive material, and a plurality of layers are provided in the piezoelectric material 111. The negative electrode external electrode 117 is made of a conductive material, is formed on the surface of the piezoelectric material 111, and is connected to the negative electrode internal electrode 116.
　図２に示すように、正極内部電極１１４と負極内部電極１１６は交互に配置され、圧電体１１１を介して対向する。正極外部電極１１５及び負極外部電極１１７は圧電素子１０４の表面及び裏面において離間して設けられている。図１に示すように正極外部電極１１５には正極配線１０５が接続され、正極外部電極１１５は正極端子として機能する。負極外部電極１１７には負極配線１０６が接続され、負極外部電極１１７は負極端子として機能する。 As shown in FIG. 2, the positive electrode internal electrodes 114 and the negative electrode internal electrodes 116 are alternately arranged and face each other via the piezoelectric material 111. The positive electrode external electrode 115 and the negative electrode external electrode 117 are provided apart from each other on the front surface and the back surface of the piezoelectric element 104. As shown in FIG. 1, a positive electrode wiring 105 is connected to the positive electrode external electrode 115, and the positive electrode external electrode 115 functions as a positive electrode terminal. The negative electrode wiring 106 is connected to the negative electrode external electrode 117, and the negative electrode external electrode 117 functions as a negative electrode terminal.
　圧電素子１０４では、正極１１２と負極１１３の間に電圧を印加すると、逆圧電効果により圧電体１１１に変形が生じ、振動が発生する。圧電素子１０４は図２に示すように、正極１１２と負極１１３を圧電体１１１を介して交互に積層した積層構造を有するものであってもよく、他の構造を有するものであってもよい。圧電素子１０４は樹脂等によって振動体１０３に接合されたものとすることができる。また、圧電素子１０４は２つ以上が振動体１０３に接合されてもよい。 In the piezoelectric element 104, when a voltage is applied between the positive electrode 112 and the negative electrode 113, the piezoelectric body 111 is deformed due to the inverse piezoelectric effect, and vibration occurs. As shown in FIG. 2, the piezoelectric element 104 may have a laminated structure in which a positive electrode 112 and a negative electrode 113 are alternately laminated via a piezoelectric material 111, or may have another structure. The piezoelectric element 104 can be joined to the vibrating body 103 with a resin or the like. Further, two or more piezoelectric elements 104 may be joined to the vibrating body 103.
　駆動回路１０２は、正極配線１０５及び負極配線１０６を介して圧電素子１０４と接続され、圧電素子１０４に駆動信号を供給する。具体的には駆動回路１０２は、後述する駆動電圧波形を生成し、正極１１２と負極１１３の間に供給する。 The drive circuit 102 is connected to the piezoelectric element 104 via the positive electrode wiring 105 and the negative electrode wiring 106, and supplies a drive signal to the piezoelectric element 104. Specifically, the drive circuit 102 generates a drive voltage waveform described later and supplies it between the positive electrode 112 and the negative electrode 113.
　変位駆動装置１００は以上のような構成を有する。変位駆動装置１００は、スマートフォンや触覚機能デバイス等の各種電子機器に搭載することが可能である。 The displacement drive device 100 has the above configuration. The displacement drive device 100 can be mounted on various electronic devices such as smartphones and tactile function devices.
　［駆動電圧波形について］
　駆動回路１０２が生成する駆動電圧波形について説明する。駆動回路１０２が生成する駆動電圧波形は、一方のピーク電圧である第１駆動最大電圧が、０Ｖと駆動周波数における圧電体１１１のブレークダウン電圧（絶縁破壊電圧）の間の電圧である。また駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、第１駆動最大電圧と反対の極性において圧電材料の抗電界の０．１倍と０．８倍の間の電圧である。 [About drive voltage waveform]
The drive voltage waveform generated by the drive circuit 102 will be described. The drive voltage waveform generated by the drive circuit 102 is a voltage in which the first drive maximum voltage, which is one of the peak voltages, is between 0 V and the breakdown voltage (dielectric breakdown voltage) of the piezoelectric material 111 at the drive frequency. Further, the second drive maximum voltage, which is the other peak voltage of the drive voltage waveform, is a voltage between 0.1 times and 0.8 times the coercive electric field of the piezoelectric material in the polarity opposite to the first drive maximum voltage. ..
　図３は、駆動回路１０２が生成する駆動電圧波形である。図３に示すようにこの駆動電圧波形において一方のピーク電圧と他方のピーク電圧は極性が反対であり、プラス側のピーク電圧を第１駆動最大電圧Ｖｐ+とし、マイナス側のピーク電圧を第２駆動最大電圧Ｖｐ-とする。 FIG. 3 is a drive voltage waveform generated by the drive circuit 102. As shown in FIG. 3, in this drive voltage waveform, one peak voltage and the other peak voltage have opposite polarities, the positive peak voltage is the first drive maximum voltage Vp +, and the negative peak voltage is the second. The maximum drive voltage is Vp-.
　また、駆動電圧波形の周波数（駆動周波数）における圧電体１１１のブレークダウン電圧をブレークダウン電圧ＢＶとし、図３に示すようにプラス側のブレークダウン電圧ＢＶをＢＶ+とする。さらに、圧電体１１１を構成する圧電材料の抗電界を抗電界Ｅｃとする。図３に示すようにプラス側の抗電界Ｅｃを抗電界Ｅｃ+とし、マイナス側の抗電界Ｅｃを抗電界Ｅｃ-とする。 Further, the breakdown voltage of the piezoelectric material 111 at the frequency (drive frequency) of the drive voltage waveform is defined as the breakdown voltage BV, and the breakdown voltage BV on the plus side is defined as BV + as shown in FIG. Further, the coercive electric field of the piezoelectric material constituting the piezoelectric body 111 is defined as the coercive electric field Ec. As shown in FIG. 3, the positive field Ec is defined as the negative field Ec +, and the negative field Ec is defined as the negative field Ec-.
　駆動回路１０２が生成する駆動電圧波形は、第１駆動最大電圧Ｖｐ+が０Ｖより大きく、ブレークダウン電圧ＢＶ+未満の電圧である。さらに、第２駆動最大電圧Ｖｐ-が抗電界Ｅｃ-の０．８倍以上０．１倍以下である。即ち、第１駆動最大電圧Ｖｐ+と第２駆動最大電圧Ｖｐ-は以下の（式１）及び（式２）を満たす。 The drive voltage waveform generated by the drive circuit 102 is a voltage in which the first drive maximum voltage Vp + is larger than 0 V and the breakdown voltage is less than BV +. Further, the second drive maximum voltage Vp-is 0.8 times or more and 0.1 times or less the coercive electric field Ec-. That is, the first drive maximum voltage Vp + and the second drive maximum voltage Vp- satisfy the following (Equation 1) and (Equation 2).
　０Ｖ＜Ｖｐ+＜ＢＶ+　　　　　　　　　　（式１）
　０．８Ｅｃ-≦Ｖｐ-≦０．１Ｅｃ-　　　（式２） 0V <Vp + <BV + (Equation 1)
0.8Ec-≤Vp-≤0.1Ec- (Equation 2)
　なお、圧電素子１０４の変位量を大きくするためにはＶｐ+＞Ｅｃ+が好適である。 In addition, Vp +> Ec + is suitable for increasing the displacement amount of the piezoelectric element 104.
　また、図３は分極方向がプラス側（＞０Ｖ）の駆動電圧波形であるが、分極方向はマイナス側（＜０Ｖ）であってもよい。図４は、駆動回路１０２が生成する、分極方向がマイナス側である駆動電圧波形である。 Further, although FIG. 3 shows a drive voltage waveform in which the polarization direction is on the plus side (> 0V), the polarization direction may be on the minus side (<0V). FIG. 4 is a drive voltage waveform generated by the drive circuit 102 in which the polarization direction is on the minus side.
　図４に示すように、この駆動電圧波形においても一方のピーク電圧と他方のピーク電圧は極性が反対であり、マイナス側のピーク電圧を第１駆動最大電圧Ｖｐ-とし、プラス側のピーク電圧を第２駆動最大電圧Ｖｐ+とする。また、図４に示すようにマイナス側のブレークダウン電圧ＢＶをＢＶ-とする。図４に示すようにプラス側の抗電界Ｅｃを抗電界Ｅｃ+とし、マイナス側の抗電界Ｅｃを抗電界Ｅｃ-とする。 As shown in FIG. 4, in this drive voltage waveform, the polarities of one peak voltage and the other peak voltage are opposite to each other, the negative peak voltage is the first drive maximum voltage Vp-, and the positive peak voltage is set. The second drive maximum voltage is Vp +. Further, as shown in FIG. 4, the breakdown voltage BV on the negative side is defined as BV−. As shown in FIG. 4, the positive field Ec is defined as the negative field Ec +, and the negative field Ec is defined as the negative field Ec-.
　駆動回路１０２が生成する駆動電圧波形は、第１駆動最大電圧Ｖｐ-がブレークダウン電圧ＢＶ-より大きく、０Ｖ未満である。さらに、第２駆動最大電圧Ｖｐ+が抗電界Ｅｃ+の０．１倍以上０．８倍以下である。即ち、第１駆動最大電圧Ｖｐ-と第２駆動最大電圧Ｖｐ+は以下の（式３）及び（式４）を満たす。 In the drive voltage waveform generated by the drive circuit 102, the first drive maximum voltage Vp-is larger than the breakdown voltage BV- and is less than 0V. Further, the second drive maximum voltage Vp + is 0.1 times or more and 0.8 times or less the coercive electric field Ec +. That is, the first drive maximum voltage Vp- and the second drive maximum voltage Vp + satisfy the following (Equation 3) and (Equation 4).
　ＢＶ-＜Ｖｐ-＜０Ｖ　　　　　　　　　（式３）
　０．１Ｅｃ+≦Ｖｐ+≦０．8Ｅｃ+　　　（式４） BV- <Vp- <0V (Equation 3)
0.1Ec + ≤Vp + ≤0.8Ec + (Equation 4)
　なお、圧電素子１０４の変位量を大きくするためにはＶｐ-＜Ｅｃ-が好適である。 In addition, Vp- <Ec- is suitable for increasing the displacement amount of the piezoelectric element 104.
　駆動回路１０２は、図３又は図４に示す駆動電圧波形を生成し、正極配線１０５及び負極配線１０６を介して正極１１２と負極１１３の間にその駆動電圧波形を供給する。なお、駆動回路１０２が生成する駆動電圧波形は図３及び図４に示すような正弦波に限られず、第１駆動最大電圧及び第２駆動最大電圧が上記条件を満たすものであればよい。具体的には駆動回路１０２が生成する駆動電圧波形は、正弦波、三角波、ハーバーサイン波、ガウシアン波又はこれらのバースト波であってもよい。 The drive circuit 102 generates the drive voltage waveform shown in FIG. 3 or 4, and supplies the drive voltage waveform between the positive electrode 112 and the negative electrode 113 via the positive electrode wiring 105 and the negative electrode wiring 106. The drive voltage waveform generated by the drive circuit 102 is not limited to the sine wave as shown in FIGS. 3 and 4, and may be any one in which the first drive maximum voltage and the second drive maximum voltage satisfy the above conditions. Specifically, the drive voltage waveform generated by the drive circuit 102 may be a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave, or a burst wave thereof.
　［変位駆動装置による効果］
　駆動回路１０２が生成する駆動電圧波形について、従来の駆動電圧波形との比較の上で説明する。図５は、従来の駆動電圧波形であるバイポーラ駆動の駆動電圧波形を示すグラフである。同図に示すように、バイポーラ駆動においては｜Ｖｐ+｜＝｜Ｖｐ-｜であり、脱分極を防止するため｜Ｅｃ｜＞｜Ｖｐ｜とする必要がある。このため、圧電材料の抗電界Ｅｃが小さいと駆動電圧振幅Ｖｐ-ｐを大きくできず、圧電アクチュエータの変位を大きくすることができない。 [Effect of displacement drive]
The drive voltage waveform generated by the drive circuit 102 will be described after being compared with a conventional drive voltage waveform. FIG. 5 is a graph showing a driving voltage waveform of bipolar driving, which is a conventional driving voltage waveform. As shown in the figure, in bipolar drive, it is | Vp + | = | Vp- |, and it is necessary to set | Ec |> | Vp | in order to prevent depolarization. Therefore, if the coercive electric field Ec of the piezoelectric material is small, the drive voltage amplitude Vp-p cannot be increased, and the displacement of the piezoelectric actuator cannot be increased.
　また図６は、従来の駆動電圧波形であるユニポーラ駆動の駆動電圧波形を示すグラフである。図６では駆動電圧波形は全体が０Ｖよりプラス側であるが、全体が０Ｖよりマイナス側であってもよい。同図に示すように、ユニポーラ駆動においてはプラス側又はマイナス側に偏った電圧により駆動し続けることにより、インプリント効果により駆動時の誘電率が低下し、駆動し続けることにより変位特性が低下する。 Further, FIG. 6 is a graph showing a drive voltage waveform of unipolar drive, which is a conventional drive voltage waveform. In FIG. 6, the entire drive voltage waveform is on the plus side of 0V, but the whole may be on the minus side of 0V. As shown in the figure, in the unipolar drive, the dielectric constant at the time of driving decreases due to the imprint effect by continuing to drive with a voltage biased to the plus side or the minus side, and the displacement characteristic deteriorates by continuing to drive. ..
　これに対し、本実施形態に係る駆動回路１０２が生成する駆動電圧波形（図３及び図４参照）は、主に駆動する側とは反対型にも抗電界Ｅｃを超えない範囲で電圧を振ることによって、駆動電圧振幅Ｖｐ-ｐを大きくすることができ、かつインプリント効果による変特性の低下を防止することが可能となる。したがって、駆動安定性や駆動信頼性を損ねずに、圧電素子１０４の変位量を最大化することができる。 On the other hand, the drive voltage waveform (see FIGS. 3 and 4) generated by the drive circuit 102 according to the present embodiment oscillates a voltage within a range not exceeding the coercive electric field Ec even in the opposite type to the main drive side. This makes it possible to increase the drive voltage amplitude Vp-p and prevent deterioration of the variable characteristics due to the imprint effect. Therefore, the displacement amount of the piezoelectric element 104 can be maximized without impairing the drive stability and the drive reliability.
　なお、上記のように第２駆動最大電圧Ｖｐは抗電界Ｅｃの０．１倍と０．８倍の間の電圧が好適であるが、第２駆動最大電圧Ｖｐが抗電界Ｅｃの０．１倍より小さいと、ユニポーラ駆動と同様にインプリント効果が発生する。また、第２駆動最大電圧Ｖｐが抗電界Ｅｃの０．８倍を超えると脱分極や絶縁性の低下が生じる。したがって、第２駆動最大電圧Ｖｐは抗電界Ｅｃの０．１倍と０．８倍の間の電圧が好適である。 As described above, the second drive maximum voltage Vp is preferably a voltage between 0.1 times and 0.8 times the coercive electric field Ec, but the second drive maximum voltage Vp is 0.1 of the coercive electric field Ec. If it is smaller than twice, the imprint effect will occur as in the case of unipolar drive. Further, when the second drive maximum voltage Vp exceeds 0.8 times the coercive electric field Ec, depolarization and deterioration of the insulating property occur. Therefore, the second drive maximum voltage Vp is preferably a voltage between 0.1 times and 0.8 times the coercive electric field Ec.
　（第２の実施形態）
　本発明の第２の実施形態に係る変位駆動装置について説明する。変位駆動装置は振動発生装置を含む。 (Second embodiment)
The displacement drive device according to the second embodiment of the present invention will be described. The displacement drive device includes a vibration generator.
　［変位駆動装置の構成］
　図７は本実施形態に係る変位駆動装置２００の模式図である。同図に示すように、変位駆動装置２００は、アクチュエータ２０１及び駆動回路２０２を備える。アクチュエータ２０１は駆動対象物２０３と誘電体素子２０４から構成されたユニモルフ型圧電アクチュエータである。 [Displacement drive device configuration]
FIG. 7 is a schematic view of the displacement drive device 200 according to the present embodiment. As shown in the figure, the displacement drive device 200 includes an actuator 201 and a drive circuit 202. The actuator 201 is a unimorph type piezoelectric actuator composed of a drive object 203 and a dielectric element 204.
　駆動対象物２０３は、例えば振動板であり、駆動対象物２０３に触れるユーザに触覚を提示する。駆動対象物２０３は金属、ガラス又は樹脂材料等からなる板状の部材とすることができ、例えば、液晶パネルや電子機器の筐体等である。駆動対象物２０３の形状やサイズは特に限定されない。 The drive object 203 is, for example, a diaphragm, and presents a tactile sensation to a user who touches the drive object 203. The drive object 203 can be a plate-shaped member made of a metal, glass, resin material, or the like, and is, for example, a liquid crystal panel, a housing of an electronic device, or the like. The shape and size of the drive object 203 are not particularly limited.
　誘電体素子２０４は、駆動対象物２０３に接合され、駆動対象物２０３を駆動する。誘電体素子２０４は、例えば駆動対象物２０３に振動を発生させることができる。図８は誘電体素子２０４の断面図である。同図に示すように誘電体素子２０４は、誘電体２１１、正極２１２及び負極２１３を備える。誘電体２１１は誘電材料からなり、具体的には電界誘起歪を発現するセラミックスからなる。 The dielectric element 204 is joined to the drive target object 203 to drive the drive target object 203. The dielectric element 204 can generate vibration in, for example, the driven object 203. FIG. 8 is a cross-sectional view of the dielectric element 204. As shown in the figure, the dielectric element 204 includes a dielectric 211, a positive electrode 212, and a negative electrode 213. The dielectric 211 is made of a dielectric material, specifically ceramics that exhibit electric field-induced strain.
　このセラミックスは、電界誘起歪の発現を伴うものであれば、抗電界Ｅｃが１ｋＶ／ｍｍ未満又はキュリー温度Ｔｃが３００℃未満のものであってもよい。このような材料としてはＢＴ（ＢａＴｉＯ３）が挙げられる（実施例参照）。また誘電体２１１を構成する誘電材料は強誘電体が好適であるが、電界誘起歪の発現を伴う材料であれば常誘電体に近い材料であってもよい。 The ceramics may have a coercive electric field Ec of less than 1 kV / mm or a Curie temperature Tc of less than 300 ° C. as long as they are accompanied by the development of electric field-induced strain. Examples of such a material include BT (BaTIO 3 ) (see Examples). The dielectric material constituting the dielectric 211 is preferably a ferroelectric material, but may be a material close to a normal dielectric as long as it is a material accompanied by the development of electric field-induced strain.
　正極２１２は、正極内部電極２１４及び正極外部電極２１５を備える。正極内部電極２１４は導電性材料からなり、誘電体２１１中に複数層が設けられている。正極外部電極２１５は導電性材料からなり、誘電体２１１の表面に形成され、正極内部電極２１４と接続されている。 The positive electrode 212 includes a positive electrode internal electrode 214 and a positive electrode external electrode 215. The positive electrode internal electrode 214 is made of a conductive material, and a plurality of layers are provided in the dielectric 211. The positive electrode external electrode 215 is made of a conductive material, is formed on the surface of the dielectric 211, and is connected to the positive electrode internal electrode 214.
　負極２１３は、負極内部電極２１６及び負極外部電極２１７を備える。負極内部電極２１６は導電性材料からなり、誘電体２１１中に複数層が設けられている。負極外部電極２１７は導電性材料からなり、誘電体２１１の表面に形成され、負極内部電極２１６と接続されている。 The negative electrode 213 includes a negative electrode internal electrode 216 and a negative electrode external electrode 217. The negative electrode internal electrode 216 is made of a conductive material, and a plurality of layers are provided in the dielectric 211. The negative electrode external electrode 217 is made of a conductive material, is formed on the surface of the dielectric 211, and is connected to the negative electrode internal electrode 216.
　図８に示すように、正極内部電極２１４と負極内部電極２１６は交互に配置され、誘電体２１１を介して対向する。正極外部電極２１５及び負極外部電極２１７は誘電体素子２０４の表面及び裏面において離間して設けられている。図７に示すように正極外部電極２１５には正極配線２０５が接続され、正極外部電極２１５は正極端子として機能する。負極外部電極２１７には負極配線２０６が接続され、負極外部電極２１７は負極端子として機能する。 As shown in FIG. 8, the positive electrode internal electrode 214 and the negative electrode internal electrode 216 are alternately arranged and face each other via the dielectric 211. The positive electrode external electrode 215 and the negative electrode external electrode 217 are provided apart from each other on the front surface and the back surface of the dielectric element 204. As shown in FIG. 7, the positive electrode wiring 205 is connected to the positive electrode external electrode 215, and the positive electrode external electrode 215 functions as a positive electrode terminal. The negative electrode wiring 206 is connected to the negative electrode external electrode 217, and the negative electrode external electrode 217 functions as a negative electrode terminal.
　誘電体素子２０４では、正極２１２と負極２１３の間に電圧を印加すると、電界誘起歪により誘電体２１１に変形が生じる。誘電体素子２０４は図８に示すように、正極２１２と負極２１３を誘電体２１１を介して交互に積層した積層構造を有するものであってもよく、他の構造を有するものであってもよい。誘電体素子２０４は樹脂等によって駆動対象物２０３に接合されたものとすることができる。また、誘電体素子２０４は２つ以上が駆動対象物２０３に接合されてもよい。 In the dielectric element 204, when a voltage is applied between the positive electrode 212 and the negative electrode 213, the dielectric 211 is deformed due to the electric field-induced strain. As shown in FIG. 8, the dielectric element 204 may have a laminated structure in which a positive electrode 212 and a negative electrode 213 are alternately laminated via a dielectric 211, or may have another structure. .. The dielectric element 204 may be joined to the drive object 203 by a resin or the like. Further, two or more dielectric elements 204 may be joined to the driving object 203.
　駆動回路２０２は、正極配線２０５及び負極配線２０６を介して圧電素子２０４と接続され、圧電素子２０４に駆動信号を供給する。具体的には駆動回路２０２は、後述する駆動電圧波形を生成し、正極２１２と負極２１３の間に供給する。 The drive circuit 202 is connected to the piezoelectric element 204 via the positive electrode wiring 205 and the negative electrode wiring 206, and supplies a drive signal to the piezoelectric element 204. Specifically, the drive circuit 202 generates a drive voltage waveform described later and supplies it between the positive electrode 212 and the negative electrode 213.
　変位駆動装置２００は以上のような構成を有する。変位駆動装置２００は、スマートフォンや触覚機能デバイス等の各種電子機器に搭載することが可能である。 The displacement drive device 200 has the above configuration. The displacement drive device 200 can be mounted on various electronic devices such as smartphones and tactile function devices.
　［駆動電圧波形について］
　駆動回路２０２が生成する駆動電圧波形について説明する。駆動回路２０２が生成する駆動電圧波形は第１の実施形態と同様とすることができる。即ち駆動回路２０２が生成する駆動電圧波形は、分極方向がプラス側（＞０Ｖ）の場合上記（式１）及び（式２）を満たし（図３参照）、分極方向がマイナス側（＜０Ｖ）の場合、上記（式３）及び（式４）を満たす（図４参照）ものとすることができる。 [About drive voltage waveform]
The drive voltage waveform generated by the drive circuit 202 will be described. The drive voltage waveform generated by the drive circuit 202 can be the same as in the first embodiment. That is, the drive voltage waveform generated by the drive circuit 202 satisfies the above (Equation 1) and (Equation 2) when the polarization direction is the plus side (> 0V) (see FIG. 3), and the polarization direction is the minus side (<0V). In the case of, it is possible to satisfy the above (Equation 3) and (Equation 4) (see FIG. 4).
　駆動回路２０２は、図３又は図４に示す駆動電圧波形を生成し、正極配線２０５及び負極配線２０６を介して正極２１２と負極２１３の間にその駆動電圧波形を供給する。なお、駆動回路２０２が生成する駆動電圧波形は図３及び図４に示すような正弦波に限られず、第１駆動最大電圧及び第２駆動最大電圧が上記条件を満たすものであればよい。具体的には駆動回路２０２が生成する駆動電圧波形は、正弦波、三角波、ハーバーサイン波、ガウシアン波又はこれらのバースト波であってもよい。 The drive circuit 202 generates the drive voltage waveform shown in FIG. 3 or 4, and supplies the drive voltage waveform between the positive electrode 212 and the negative electrode 213 via the positive electrode wiring 205 and the negative electrode wiring 206. The drive voltage waveform generated by the drive circuit 202 is not limited to the sine wave as shown in FIGS. 3 and 4, and the first drive maximum voltage and the second drive maximum voltage may satisfy the above conditions. Specifically, the drive voltage waveform generated by the drive circuit 202 may be a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave, or a burst wave thereof.
　［変位駆動装置による効果］
　変位駆動装置２００では、上記のような駆動電圧波形（図３及び図４参照）を駆動回路２０２が生成し、誘電体素子２０４に供給する。第１の実施形態と同様に、主に駆動する側とは反対型にも抗電界Ｅｃを超えない範囲で電圧を振ることによって、駆動電圧振幅Ｖｐ-ｐを大きくすることができ、かつインプリント効果による変特性の低下を防止することが可能となる。したがって、駆動安定性や駆動信頼性を損ねずに、圧電素子２０４の変位量を最大化することができる。 [Effect of displacement drive]
In the displacement drive device 200, the drive circuit 202 generates the drive voltage waveform (see FIGS. 3 and 4) as described above and supplies it to the dielectric element 204. Similar to the first embodiment, the drive voltage amplitude Vp-p can be increased and imprinted by applying a voltage in a range not exceeding the coercive electric field Ec in the opposite type to the main drive side. It is possible to prevent the deterioration of the variable characteristics due to the effect. Therefore, the displacement amount of the piezoelectric element 204 can be maximized without impairing the drive stability and the drive reliability.
　また、変位駆動装置２００では、上記のような駆動電圧波形（図３及び図４参照）を用いることにより、誘電体２１１を形成する誘電材料の条件を広げることができる。圧電アクチュエータに一般的に必要とされる誘電材料としては、キュリー温度Ｔｃが３００℃以上かつ抗電界Ｅｃが１ｋＶ／ｍｍであり、耐リフロー性と耐バイポーラ駆動性能を有する材料を用いる必要がある。図９は、圧電アクチュエータに一般的に必要とされる誘電材料のＰ－Ｅヒステリシスループの例であり、横軸は電界（Ｐ）、縦軸は分極（Ｅ）である。 Further, in the displacement drive device 200, the conditions of the dielectric material forming the dielectric 211 can be expanded by using the drive voltage waveform (see FIGS. 3 and 4) as described above. As the dielectric material generally required for the piezoelectric actuator, it is necessary to use a material having a Curie temperature Tc of 300 ° C. or higher, a coercive electric field Ec of 1 kV / mm, and reflow resistance and bipolar drive performance. FIG. 9 shows an example of a PE hysteresis loop of a dielectric material generally required for a piezoelectric actuator, in which the horizontal axis is an electric field (P) and the vertical axis is polarization (E).
　しかしながら変位駆動装置２００では、上記のような駆動電圧波形を用いることにより、電界誘起歪の発現を伴う材料であれば、抗電界Ｅｃが１ｋＶ／ｍｍ未満又はキュリー温度Ｔｃが３００℃未満のセラミックスを誘電体２１１の材料として用いることが可能となる。また、誘電体２１１の材料は図９に示すような高い強誘電性を必要としない。図１０は、誘電体２１１を構成する誘電材料のＰ－Ｅヒステリシスループの例であり、横軸は電界（Ｐ）、縦軸は分極（Ｅ）である。 However, in the displacement drive device 200, by using the drive voltage waveform as described above, if the material is accompanied by the occurrence of electric field-induced strain, ceramics having a coercive electric field Ec of less than 1 kV / mm or a Curie temperature Tc of less than 300 ° C. can be used. It can be used as a material for the dielectric 211. Further, the material of the dielectric 211 does not require high ferroelectricity as shown in FIG. FIG. 10 is an example of a PE hysteresis loop of the dielectric material constituting the dielectric 211, in which the horizontal axis is the electric field (P) and the vertical axis is the polarization (E).
　一般的に用いられる圧電アクチュエータの誘電材料では、ＤＣ分極による分極処理が必要である。この分極処理では、分極度合いの違い、即ち分極位相の回転度数による差異が生じやすく、変位特性にばらつきが生じやすく、分極度合いを揃えるための複雑な機構を有す分極装置が必要であり、工程コストへの負担も大きい。これに対し、変位駆動装置２００では、誘電体２１１の材料として電界誘起歪の発現を伴うセラミックスを用いることにより、分極処理が不要となる。電解誘起歪は分極の有無に関係なく発現するためである。 The dielectric material of a commonly used piezoelectric actuator requires polarization processing by DC polarization. In this polarization processing, a difference in the degree of polarization, that is, a difference in the degree of rotation of the polarization phase is likely to occur, the displacement characteristics are likely to vary, and a polarization device having a complicated mechanism for making the degree of polarization uniform is required. The burden on costs is also great. On the other hand, in the displacement drive device 200, the polarization treatment becomes unnecessary by using the ceramics accompanied by the development of the electric field-induced strain as the material of the dielectric 211. This is because the electrolysis-induced strain develops regardless of the presence or absence of polarization.
　このように、誘電体２１１の材料として電界誘起歪の発現を伴うセラミックスを用いると、未分極であることを前提とするため、抗電界Ｅｃが高い必要がない。また、脱分極の概念もないため、製造工程で高温に晒されてもなんら問題なく、キュリー温度Ｔｃが３００℃未満であっても問題がない。なお、圧電素子２０４においても性能検査等のために予備分極を実施してもよい。 As described above, when ceramics with the development of electric field-induced strain are used as the material of the dielectric 211, it is assumed that they are unpolarized, so that the coercive electric field Ec does not need to be high. Further, since there is no concept of depolarization, there is no problem even if it is exposed to a high temperature in the manufacturing process, and there is no problem even if the Curie temperature Tc is less than 300 ° C. The piezoelectric element 204 may also be prepolarized for performance inspection or the like.
　以上のように、変位駆動装置２００では、誘電体２１１の材料として高い圧電性や高い強誘電性を有しない材料を用いることができ、圧電アクチュエータに一般的に必要とされる誘電材料よりも環境負荷やコスト負荷が少ない誘電材料を選択することが可能である。さらに、誘電体素子２０４は分極処理を必要としないため、複雑で効果な分極装置や分極処理工程が不要となり、生産タクトの向上や生産設備コストの抑制が可能である。また、分極度合いを確認するための検査も必要としないため、検査工程の削減も可能である。 As described above, in the displacement drive device 200, a material that does not have high piezoelectricity or high ferroelectricity can be used as the material of the dielectric 211, and the environment is higher than that of the dielectric material generally required for the piezoelectric actuator. It is possible to select a dielectric material with a low load and cost load. Further, since the dielectric element 204 does not require a polarization treatment, a complicated and effective polarization device and a polarization treatment step are not required, and it is possible to improve the production tact and suppress the production equipment cost. Further, since the inspection for confirming the degree of polarization is not required, the inspection process can be reduced.
　上記第１の実施形態に係るユニモルフ型圧電アクチュエータ１０１（図１参照）を作製した。振動体１０３はステンレスからなる板であり、長さ４０ｍｍ、幅１５ｍｍ、厚み０．３ｍｍである。圧電素子１０４は長さ３０ｍｍ、幅１５ｍｍ、厚み０．３ｍｍとし、振動体１０３に樹脂接着剤により接合した。圧電体１１１を構成する圧電材料の抗電界Ｅｃは１．１ｋＶ／ｍｍであり、圧電素子１０４のブレークダウン電圧は９．５ｋＶ／ｍｍであった。 The unimorph type piezoelectric actuator 101 (see FIG. 1) according to the first embodiment was manufactured. The vibrating body 103 is a plate made of stainless steel, and has a length of 40 mm, a width of 15 mm, and a thickness of 0.3 mm. The piezoelectric element 104 had a length of 30 mm, a width of 15 mm, and a thickness of 0.3 mm, and was bonded to the vibrating body 103 with a resin adhesive. The coercive electric field Ec of the piezoelectric material constituting the piezoelectric body 111 was 1.1 kV / mm, and the breakdown voltage of the piezoelectric element 104 was 9.5 kV / mm.
　図１１は、圧電アクチュエータの変位計測方法を示す模式図である。同図に示すように、固定基板３０１上に固定部３０２及び固定部３０３を設け、振動体１０３の両端を固定部３０２及び固定部３０３にそれぞれ固定した。振動体１０３の自由長を自由長Ｌとして示す。レーザードップラー振動計（ＬＤＶ）３０４により、振動体１０３の中央部（１／２Ｌ）のベンディング変位を計測した。下記の［表１］は測定結果を示す表である。 FIG. 11 is a schematic diagram showing a displacement measurement method of the piezoelectric actuator. As shown in the figure, the fixing portion 302 and the fixing portion 303 are provided on the fixed substrate 301, and both ends of the vibrating body 103 are fixed to the fixing portion 302 and the fixing portion 303, respectively. The free length of the vibrating body 103 is shown as the free length L. The bending displacement of the central portion (1 / 2L) of the vibrometer 103 was measured by a laser Doppler vibrometer (LDV) 304. The following [Table 1] is a table showing the measurement results.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１では駆動波形は正弦波、駆動周波数:１００Ｈｚ、第１駆動最大電圧Ｖｐ+：３．５ｋＶ／ｍｍ、第２駆動最大電圧Ｖｐ-：－０．８ｋＶ／ｍｍ、Ｖｐ-ｐ：４．３ｋＶ／ｍｍとした。第１駆動最大電圧Ｖｐ+は０Ｖとブレークダウン電圧（９．５ｋＶ／ｍｍ）の間の電圧である。第２駆動最大電圧Ｖｐ-は抗電界Ｅｃ-(－１．１ｋＶ／ｍｍ)の０．１倍と０．８倍の間の電圧である。 In Example 1, the drive waveform is a sine wave, the drive frequency is 100 Hz, the first drive maximum voltage Vp +: 3.5 kV / mm, the second drive maximum voltage Vp-: −0.8 kV / mm, Vp-p: 4. It was set to 3 kV / mm. The first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm). The second drive maximum voltage Vp-is a voltage between 0.1 times and 0.8 times the coercive electric field Ec-(−1.1 kV / mm).
　レーザードップラー振動計３０４による変位計測結果は２６．５μｍであった。また、４０℃９０％ＲＨの高湿度下において２０Ｍサイクルの連続駆動の後、変位を計測すると、変位低下率は－１％であり、非常に高い特性安定性が得られた。このように、実施例１では、変位量と特性安定性は共に良好であった。 The displacement measurement result by the laser Doppler vibrometer 304 was 26.5 μm. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was -1%, and very high characteristic stability was obtained. As described above, in Example 1, both the displacement amount and the characteristic stability were good.
　実施例２では駆動波形は正弦波、駆動周波数:１００Ｈｚ、第１駆動最大電圧Ｖｐ+：５ｋＶ／ｍｍ、第２駆動最大電圧Ｖｐ-：－０．８ｋＶ／ｍｍ、Ｖｐ-ｐ：５．８ｋＶ／ｍｍとした。第１駆動最大電圧Ｖｐ+は０Ｖとブレークダウン電圧（９．５ｋＶ／ｍｍ）の間の電圧である。第２駆動最大電圧Ｖｐ-は抗電界Ｅｃ-(－１．１ｋＶ／ｍｍ)の０．１倍と０．８倍の間の電圧である。 In the second embodiment, the drive waveform is a sine wave, the drive frequency is 100 Hz, the first drive maximum voltage Vp +: 5 kV / mm, the second drive maximum voltage Vp-: −0.8 kV / mm, Vp-p: 5.8 kV /. It was set to mm. The first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm). The second drive maximum voltage Vp-is a voltage between 0.1 times and 0.8 times the coercive electric field Ec-(−1.1 kV / mm).
　レーザードップラー振動計３０４による変位計測結果は３２．８μｍであった。また、４０℃９０％ＲＨの高湿度下において２０Ｍサイクルの連続駆動の後、変位を計測すると、変位低下率は－２％であり、高い特性安定性が得られた。このように、実施例２では、変位量と特性安定性は共に良好であった。 The displacement measurement result by the laser Doppler vibrometer 304 was 32.8 μm. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was -2%, and high characteristic stability was obtained. As described above, in Example 2, both the displacement amount and the characteristic stability were good.
　実施例３では駆動波形は正弦波、駆動周波数:１００Ｈｚ、第１駆動最大電圧Ｖｐ+：８ｋＶ／ｍｍ、第２駆動最大電圧Ｖｐ-：－０．８ｋＶ／ｍｍ、Ｖｐ-ｐ：８．８ｋＶ／ｍｍとした。第１駆動最大電圧Ｖｐ+は０Ｖとブレークダウン電圧（９．５ｋＶ／ｍｍ）の間の電圧である。第２駆動最大電圧Ｖｐ-は抗電界Ｅｃ-(－１．１ｋＶ／ｍｍ)の０．１倍と０．８倍の間の電圧である。 In Example 3, the drive waveform is a sine wave, the drive frequency is 100 Hz, the first drive maximum voltage Vp +: 8 kV / mm, the second drive maximum voltage Vp-: −0.8 kV / mm, Vp-p: 8.8 kV /. It was set to mm. The first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm). The second drive maximum voltage Vp-is a voltage between 0.1 times and 0.8 times the coercive electric field Ec-(−1.1 kV / mm).
　レーザードップラー振動計３０４による変位計測結果は４５．４μｍであった。また、４０℃９０％ＲＨの高湿度下において２０Ｍサイクルの連続駆動の後、変位を計測すると、変位低下率は－４％であり、高い特性安定性が得られた。このように、実施例３では、変位量と特性安定性は共に良好であった。 The displacement measurement result by the laser Doppler vibrometer 304 was 45.4 μm. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was -4%, and high characteristic stability was obtained. As described above, in Example 3, both the displacement amount and the characteristic stability were good.
　比較例１では駆動波形は正弦波、駆動周波数:１００Ｈｚである。第１駆動最大電圧Ｖｐ+：３．５ｋＶ／ｍｍ、第２駆動最大電圧Ｖｐ-：０ｋＶ／ｍｍ、Ｖｐ-ｐ：３．５ｋＶ／ｍｍとした。第１駆動最大電圧Ｖｐ+は０Ｖとブレークダウン電圧（９．５ｋＶ／ｍｍ）の間の電圧である。第２駆動最大電圧Ｖｐ-は抗電界Ｅｃ-(－１．１ｋＶ／ｍｍ)の０．１倍と０．８倍の間の電圧ではなく、０．１倍より大きい電圧である。 In Comparative Example 1, the drive waveform is a sine wave and the drive frequency is 100 Hz. The first drive maximum voltage Vp +: 3.5 kV / mm, the second drive maximum voltage Vp-: 0 kV / mm, and Vp-p: 3.5 kV / mm. The first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm). The second drive maximum voltage Vp-is not a voltage between 0.1 times and 0.8 times the coercive electric field Ec-(−1.1 kV / mm), but a voltage larger than 0.1 times.
　レーザードップラー振動計３０４による変位計測結果は２３．１μｍであった。また、４０℃９０％ＲＨの高湿度下において２０Ｍサイクルの連続駆動の後、変位を計測すると、変位低下率は－７％であり、特性安定性は低いものとなった。このように、比較例１では、変位量は良好であったものの、特性安定性は不十分であった。 The displacement measurement result by the laser Doppler vibrometer 304 was 23.1 μm. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was −7%, and the characteristic stability was low. As described above, in Comparative Example 1, although the displacement amount was good, the characteristic stability was insufficient.
　比較例２では駆動波形は正弦波、駆動周波数:１００Ｈｚである。第１駆動最大電圧Ｖｐ+：１ｋＶ／ｍｍ、第２駆動最大電圧Ｖｐ-：－１ｋＶ／ｍｍ、Ｖｐ-ｐ：２ｋＶ／ｍｍとした。第１駆動最大電圧Ｖｐ+は０Ｖとブレークダウン電圧（９．５ｋＶ／ｍｍ）の間の電圧である。第２駆動最大電圧Ｖｐ-は抗電界Ｅｃ-(－１．１ｋＶ／ｍｍ)の０．１倍と０．８倍の間の電圧ではなく、０．８倍より小さい電圧である。 In Comparative Example 2, the drive waveform is a sine wave and the drive frequency is 100 Hz. The first drive maximum voltage Vp +: 1 kV / mm, the second drive maximum voltage Vp-: -1 kV / mm, and Vp-p: 2 kV / mm. The first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm). The second drive maximum voltage Vp-is not a voltage between 0.1 times and 0.8 times the coercive electric field Ec-(−1.1 kV / mm), but a voltage smaller than 0.8 times.
　レーザードップラー振動計３０４による変位計測結果は１６．８μｍであった。また、４０℃９０％ＲＨの高湿度下において２０Ｍサイクルの連続駆動の後、変位を計測すると、変位低下率は０％であり、高い特性安定性が得られた。このように、比較例２では、特性安定性は良好であったものの、変位量は不十分であった。 The displacement measurement result by the laser Doppler vibrometer 304 was 16.8 μm. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was 0%, and high characteristic stability was obtained. As described above, in Comparative Example 2, although the characteristic stability was good, the displacement amount was insufficient.
　比較例３では駆動波形は正弦波、駆動周波数:１００Ｈｚである。第１駆動最大電圧Ｖｐ+：８ｋＶ／ｍｍ、第２駆動最大電圧Ｖｐ-：０ｋＶ／ｍｍ、Ｖｐ-ｐ：８ｋＶ／ｍｍとした。第１駆動最大電圧Ｖｐ+は０Ｖとブレークダウン電圧（９．５ｋＶ／ｍｍ）の間の電圧である。第２駆動最大電圧Ｖｐ-は抗電界Ｅｃ-(－１．１ｋＶ／ｍｍ)の０．１倍と０．８倍の間の電圧ではなく、０．１倍より大きい電圧である。 In Comparative Example 3, the drive waveform is a sine wave and the drive frequency is 100 Hz. The first drive maximum voltage Vp +: 8 kV / mm, the second drive maximum voltage Vp-: 0 kV / mm, and Vp-p: 8 kV / mm. The first drive maximum voltage Vp + is a voltage between 0 V and the breakdown voltage (9.5 kV / mm). The second drive maximum voltage Vp-is not a voltage between 0.1 times and 0.8 times the coercive electric field Ec-(−1.1 kV / mm), but a voltage larger than 0.1 times.
　レーザードップラー振動計３０４による変位計測結果は４１．３μｍであった。また、４０℃９０％ＲＨの高湿度下において２０Ｍサイクルの連続駆動の後、変位を計測すると、変位低下率は－１２％であり、特性安定性は低いものとなった。このように、比較例３では、変位量は良好であったものの、特性安定性は不十分であった。 The displacement measurement result by the laser Doppler vibrometer 304 was 41.3 μm. Further, when the displacement was measured after continuous driving for 20 M cycles under high humidity of 40 ° C. and 90% RH, the displacement reduction rate was -12%, and the characteristic stability was low. As described above, in Comparative Example 3, although the displacement amount was good, the characteristic stability was insufficient.
　比較例４では駆動波形は正弦波、駆動周波数:１００Ｈｚである。第１駆動最大電圧Ｖｐ+：１０ｋＶ／ｍｍ、第２駆動最大電圧Ｖｐ-：０ｋＶ／ｍｍ、Ｖｐ-ｐ：１０ｋＶ／ｍｍとした。第１駆動最大電圧Ｖｐ+は０Ｖとブレークダウン電圧（９．５ｋＶ／ｍｍ）の間の電圧ではなく、ブレークダウン電圧より大きい電圧である。第２駆動最大電圧Ｖｐ-は抗電界Ｅｃ-(－１．１ｋＶ／ｍｍ)の０．１倍と０．８倍の間の電圧ではなく、０．１倍より大きい電圧である。 In Comparative Example 4, the drive waveform is a sine wave and the drive frequency is 100 Hz. The first drive maximum voltage Vp +: 10 kV / mm, the second drive maximum voltage Vp-: 0 kV / mm, and Vp-p: 10 kV / mm. The first drive maximum voltage Vp + is not a voltage between 0 V and the breakdown voltage (9.5 kV / mm), but a voltage larger than the breakdown voltage. The second drive maximum voltage Vp-is not a voltage between 0.1 times and 0.8 times the coercive electric field Ec-(−1.1 kV / mm), but a voltage larger than 0.1 times.
　比較例４では圧電体１１１においてブレークダウンが生じ、レーザードップラー振動計３０４によって変位が計測されなかった。 In Comparative Example 4, a breakdown occurred in the piezoelectric material 111, and the displacement was not measured by the laser Doppler vibrometer 304.
　以上のように実施例１乃至３では変位量と特性安定性の両方が良好となる結果が得られた。一方、比較例１乃至４では、変位量と特性安定性の両方が良好となる結果は得られなかった。したがって、第１駆動最大電圧を０Ｖとブレークダウン電圧の間の電圧とし、第２駆動最大電圧を抗電界の０．１倍と０．８倍の間の電圧とすることにより、変位量と特性安定性が共に優れる変位駆動装置を実現することが可能である。 As described above, in Examples 1 to 3, both the displacement amount and the characteristic stability were good. On the other hand, in Comparative Examples 1 to 4, the result that both the displacement amount and the characteristic stability were good could not be obtained. Therefore, by setting the first drive maximum voltage to a voltage between 0 V and the breakdown voltage and the second drive maximum voltage to a voltage between 0.1 times and 0.8 times the coercive electric field, the displacement amount and characteristics are set. It is possible to realize a displacement drive device with excellent stability.
　上記第２の実施形態に係る誘電体素子２０４（図８参照）を作製した。誘電体素子２０４は１層あたり２６μｍの誘電体を、正極内部電極２１４及び負極内部電極２１６を交互に１０層積層したものであり、３２１６形状を有する。各種の誘電材料からなる誘電体素子２０４を作製し、上記駆動電圧波形（駆動電圧－２Ｖ～＋１０４Ｖ、駆動周波数１０Ｈｚ、図３参照）によって誘電体素子２０４を駆動した。レーザードップラー振動計を用いて、誘電体素子２０４上方（Ｚ方向、図８参照）からレーザーを照射し、誘電体素子２０４の厚み方向（Ｚ方向）における伸縮の変位量を計測した。さらに、分極方向への変位量／電界強度／層数を変位量ｄ３３＊として算出した。下記の［表２］は誘電体素子２０４の構成及び測定結果を示す表である。 The dielectric element 204 (see FIG. 8) according to the second embodiment was manufactured. The dielectric element 204 is formed by alternately laminating 10 layers of a positive electrode internal electrode 214 and a negative electrode internal electrode 216 of a dielectric having a thickness of 26 μm per layer, and has a 3216 shape. A dielectric element 204 made of various dielectric materials was produced, and the dielectric element 204 was driven by the above-mentioned drive voltage waveform (drive voltage -2 V to + 104 V, drive frequency 10 Hz, see FIG. 3). Using a laser Doppler vibrometer, a laser was irradiated from above the dielectric element 204 (Z direction, see FIG. 8), and the amount of expansion and contraction displacement of the dielectric element 204 in the thickness direction (Z direction) was measured. Further, the displacement amount in the polarization direction / electric field strength / number of layers was calculated as the displacement amount d33 *. The following [Table 2] is a table showing the configuration and measurement results of the dielectric element 204.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　上記［表２］における「材料」は各実施例における誘電体素子２０４の誘電体２１１を構成する誘電材料である。下記の［表３］は、実施例４及び５に係るＢＴ１の組成と実施例６に係るＢＴ２の組成を示す表である。下記の［表４］は、実施例７に係るＬＮＫＮ１の組成を示す表である。実施例８に係るＰＺＴ１の組成は、ＰＺＴ－ＰＺＮ（Ｐｂ（Ｚｒ１／２Ｔｉ１／２）Ｏ３－Ｐｂ（Ｚｎ１／３Ｎｂ２／３）Ｏ３）である。 The “material” in the above [Table 2] is a dielectric material constituting the dielectric 211 of the dielectric element 204 in each embodiment. The following [Table 3] is a table showing the composition of BT1 according to Examples 4 and 5 and the composition of BT2 according to Example 6. The following [Table 4] is a table showing the composition of LNKN1 according to Example 7. The composition of PZT1 according to Example 8 is PZT-PZN (Pb (Zr 1/2 Ti 1/2 ) O 3- Pb (Zn 1/3 Nb 2/3 ) O 3 ).
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　実施例４、７及び８に係る誘電体素子２０４は２５℃、３．５ｋＶ／ｍｍ、１５ｍｉｎの条件で分極し、変位計測を実施した。一方、実施例５及び６に係る誘電体素子２０４は未分極の状態で変位計測を実施した。 The dielectric element 204 according to Examples 4, 7 and 8 was polarized at 25 ° C., 3.5 kV / mm, and 15 min, and displacement was measured. On the other hand, the displacement of the dielectric element 204 according to Examples 5 and 6 was measured in a non-polarized state.
　上記［表２］に示すように、実施例７に係るＬＮＫＮ１及び実施例８に係るＰＺＴ１は共にキュリー温度Ｔｃが３００℃以上、抗電界Ｅｃが１ｋＶ／ｍｍ以上の材料である。実施例７では変位量ｄ３３＊は１９０ｐｍ／Ｖであり、実施例８では変位量ｄ３３＊は４５０ｐｍ／Ｖであった。 As shown in [Table 2] above, both LNKN1 according to Example 7 and PZT1 according to Example 8 are materials having a Curie temperature Tc of 300 ° C. or higher and a coercive electric field Ec of 1 kV / mm or higher. In Example 7, the displacement amount d33 * was 190 pm / V, and in Example 8, the displacement amount d33 * was 450 pm / V.
　一方、実施例４－６に係るＢＴ１及びＢＴ２は、キュリー温度Ｔｃが３００℃未満、抗電界Ｅｃが１ｋＶ／ｍｍ未満の材料である。実施例４及び５では変位量ｄ３３＊が３７０ｐｍ／Ｖ、実施例６では変位量ｄ３３＊が３９０ｐｍ／Ｖであった。したがって、キュリー温度Ｔｃが３００℃未満、抗電界Ｅｃが１ｋＶ／ｍｍ未満の材料であってもキュリー温度Ｔｃが３００℃以上、抗電界Ｅｃが１ｋＶ／ｍｍ以上の材料と比較して遜色のない変位量が得られた。 On the other hand, BT1 and BT2 according to Example 4-6 are materials having a Curie temperature Tc of less than 300 ° C. and a coercive electric field Ec of less than 1 kV / mm. In Examples 4 and 5, the displacement amount d33 * was 370 pm / V, and in Example 6, the displacement amount d33 * was 390 pm / V. Therefore, even if the material has a Curie temperature Tc of less than 300 ° C. and a coercive electric field Ec of less than 1 kV / mm, the displacement is comparable to that of a material having a Curie temperature Tc of 300 ° C. or more and a coercive electric field Ec of 1 kV / mm or more. The amount was obtained.
　また、実施例４－６から、誘電体素子２０４は未分極の状態であっても、分極した状態と同程度の変位量が得られた。したがって、誘電体素子２０４は分極処理を必要としないものである。 Further, from Example 4-6, even if the dielectric element 204 is in the unpolarized state, the same amount of displacement as in the polarized state can be obtained. Therefore, the dielectric element 204 does not require a polarization process.
　１００、２００…変位駆動装置
　１０１…圧電アクチュエータ
　１０２、２０２…駆動回路
　１０３、２０３…駆動対象物
　１０４…圧電素子
　１０５、２０５…正極配線
　１０６、２０６…負極配線
　１１１…圧電体
　１１２、２１２…正極
　１１３、２１３…負極
　１１４、２１４…正極内部電極
　１１５、２１５…正極外部電極
　１１６、２１６…負極内部電極
　１１７、２１７…負極外部電極
　２０１…アクチュエータ
　２０４…誘電体素子
　２１１…誘電体 100, 200 ... displacement drive device 101 ... piezoelectric actuator 102, 202 ... drive circuit 103, 203 ... drive object 104 ... piezoelectric element 105, 205 ... positive electrode wiring 106, 206 ... negative electrode wiring 111 ... piezoelectric body 112, 212 ... positive electrode 113 , 213 ... Negative electrode 114, 214 ... Positive electrode internal electrode 115, 215 ... Positive electrode external electrode 116, 216 ... Negative electrode internal electrode 117, 217 ... Negative electrode external electrode 201 ... Actuator 204 ... Dielectric element 211 ... Dioxide

Claims (13)

  1. 　電界誘起歪を発現するセラミックスを介して正極と負極が対向する誘電体素子の、前記正極と前記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、前記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと前記駆動周波数における前記セラミックスのブレークダウン電圧の間の電圧であり、前記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、前記第１駆動最大電圧と反対の極性において前記セラミックスの抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を前記正極と前記負極の間に印加する
    　駆動方法。     A drive voltage waveform applied between the positive electrode and the negative electrode of a dielectric element having a positive electrode and a negative electrode facing each other via ceramics exhibiting an electric field-induced strain and having a predetermined drive frequency, which is a drive voltage waveform of the drive voltage waveform. The first drive maximum voltage, which is the peak voltage of one of them, is the voltage between 0 V and the breakdown voltage of the ceramics at the drive frequency, and the second drive maximum voltage, which is the peak voltage of the other of the drive voltage waveforms. However, a driving method in which a driving voltage waveform, which is a voltage between 0.1 times and 0.8 times the coercive electric field of the ceramics at a polarity opposite to the first driving maximum voltage, is applied between the positive electrode and the negative electrode. ..
  2. 　請求項１に記載の駆動方法であって、
    　前記セラミックスは、抗電界が１ｋＶ／ｍｍ未満又はキュリー温度が３００℃未満である
    　駆動方法。     The driving method according to claim 1.
    The ceramic is a driving method in which the coercive electric field is less than 1 kV / mm or the Curie temperature is less than 300 ° C.
  3. 　請求項１又は２に記載の駆動方法であって、
    　駆動電圧波形は、正弦波、三角波、ハーバーサイン波、ガウシアン波又はこれらのバースト波である
    　駆動方法。     The driving method according to claim 1 or 2.
    The drive voltage waveform is a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave or a burst wave thereof.
  4. 　電界誘起歪を発現するセラミックスを介して正極と負極が対向する誘電体素子の、前記正極と前記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、前記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと前記駆動周波数における前記セラミックスのブレークダウン電圧の間の電圧であり、前記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、前記第１駆動最大電圧と反対の極性において前記セラミックスの抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を生成し、前記正極と前記負極の間に印加する
    　駆動回路。     A drive voltage waveform applied between the positive electrode and the negative electrode of a dielectric element having a positive electrode and a negative electrode facing each other via ceramics exhibiting an electric field-induced strain and having a predetermined drive frequency, which is a drive voltage waveform of the drive voltage waveform. The first drive maximum voltage, which is the peak voltage of one of them, is the voltage between 0 V and the breakdown voltage of the ceramics at the drive frequency, and the second drive maximum voltage, which is the peak voltage of the other of the drive voltage waveforms. Generates a drive voltage waveform that is a voltage between 0.1 times and 0.8 times the coercive voltage of the ceramics at a polarity opposite to the first drive maximum voltage, and is applied between the positive electrode and the negative voltage. Drive circuit.
  5. 　請求項４に記載の駆動回路であって、
    　前記セラミックスは、抗電界が１ｋＶ／ｍｍ未満又はキュリー温度が３００℃未満である
    　駆動回路。     The drive circuit according to claim 4.
    The ceramic is a drive circuit having a coercive electric field of less than 1 kV / mm or a Curie temperature of less than 300 ° C.
  6. 　電界誘起歪を発現するセラミックスを介して正極と負極が対向する誘電体素子と、
    　前記誘電体素子が接合された駆動対象物と、
    　前記正極と前記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、前記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと前記駆動周波数における前記セラミックスのブレークダウン電圧の間の電圧であり、前記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、前記第１駆動最大電圧と反対の極性において前記セラミックスの抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を生成し、前記正極と前記負極の間に印加する駆動回路と
    　を具備する変位駆動装置。     A dielectric element in which the positive electrode and the negative electrode face each other via ceramics that exhibit electric field-induced strain,
    The driving object to which the dielectric element is bonded and the driving object
    A drive voltage waveform applied between the positive electrode and the negative electrode and having a predetermined drive frequency, wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is 0 V and the drive frequency. The second drive maximum voltage, which is the voltage between the breakdown voltage of the ceramics and is the other peak voltage of the drive voltage waveform, has a polarity opposite to the first drive maximum voltage, and the coercive voltage of the ceramics is 0. A displacement drive device comprising a drive circuit that generates a drive voltage waveform that is a voltage between 1 and 0.8 times and applies it between the positive and negative electrodes.
  7. 　請求項６に記載の変位駆動装置であって、
    　前記セラミックスは、抗電界が１ｋＶ／ｍｍ未満又はキュリー温度が３００℃未満である
    　変位駆動装置。     The displacement drive device according to claim 6.
    The ceramic is a displacement drive device having a coercive electric field of less than 1 kV / mm or a Curie temperature of less than 300 ° C.
  8. 　請求項６又は７に記載の変位駆動装置であって、
    　前記誘電体素子及び前記駆動対象物はアクチュエータを構成する
    　変位駆動装置。     The displacement drive device according to claim 6 or 7.
    The dielectric element and the driving object are displacement driving devices that constitute an actuator.
  9. 　圧電材料からなる圧電体を介して正極と負極が対向する圧電素子の、前記正極と前記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、前記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと前記駆動周波数における前記圧電体のブレークダウン電圧の間の電圧であり、前記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、前記第１駆動最大電圧と反対の極性において前記圧電材料の抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を前記正極と前記負極の間に印加する
    　駆動方法。     A drive voltage waveform applied between the positive electrode and the negative electrode of a piezoelectric element having a positive electrode and a negative electrode facing each other via a piezoelectric material made of a piezoelectric material and having a predetermined drive frequency, which is one of the drive voltage waveforms. The first drive maximum voltage, which is the peak voltage of, is the voltage between 0 V and the breakdown voltage of the piezoelectric body at the drive frequency, and the second drive maximum voltage, which is the other peak voltage of the drive voltage waveform, is A driving method in which a driving voltage waveform, which is a voltage between 0.1 times and 0.8 times the coercive electric field of the piezoelectric material at a polarity opposite to the first driving maximum voltage, is applied between the positive electrode and the negative electrode. ..
  10. 　請求項９に記載の駆動方法であって、
    　駆動電圧波形は、正弦波、三角波、ハーバーサイン波、ガウシアン波又はこれらのバースト波である     The driving method according to claim 9.
    The drive voltage waveform is a sine wave, a triangular wave, a harbor sine wave, a Gaussian wave or a burst wave thereof.
  11. 　圧電材料からなる圧電体を介して正極と負極が対向する圧電素子の、前記正極と前記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、前記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと前記駆動周波数における前記圧電体のブレークダウン電圧の間の電圧であり、前記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、前記第１駆動最大電圧と反対の極性において前記圧電材料の抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を生成し、前記正極と前記負極の間に印加する
    　駆動回路。     A drive voltage waveform applied between the positive electrode and the negative electrode of a piezoelectric element having a positive electrode and a negative electrode facing each other via a piezoelectric material made of a piezoelectric material and having a predetermined drive frequency, which is one of the drive voltage waveforms. The first drive maximum voltage, which is the peak voltage of, is the voltage between 0 V and the breakdown voltage of the piezoelectric body at the drive frequency, and the second drive maximum voltage, which is the other peak voltage of the drive voltage waveform, is Generates a drive voltage waveform that is a voltage between 0.1 times and 0.8 times the coercive voltage of the piezoelectric material at a polarity opposite to the first drive maximum voltage, and applies it between the positive electrode and the negative voltage. Drive circuit.
  12. 　圧電材料からなる圧電体を介して正極と負極が対向する圧電素子と、
    　前記圧電素子が接合された振動体と、
    　前記正極と前記負極の間に印加され、所定の駆動周波数を有する駆動電圧波形であって、前記駆動電圧波形のうち一方のピーク電圧である第１駆動最大電圧が、０Ｖと前記駆動周波数における前記圧電体のブレークダウン電圧の間の電圧であり、前記駆動電圧波形のうち他方のピーク電圧である第２駆動最大電圧が、前記第１駆動最大電圧と反対の極性において前記圧電材料の抗電界の０．１倍と０．８倍の間の電圧である駆動電圧波形を生成し、前記正極と前記負極の間に印加する駆動回路と
    　を具備する変位駆動装置。     A piezoelectric element in which the positive electrode and the negative electrode face each other via a piezoelectric body made of a piezoelectric material,
    The vibrating body to which the piezoelectric element is bonded and
    A drive voltage waveform applied between the positive electrode and the negative electrode and having a predetermined drive frequency, wherein the first drive maximum voltage, which is the peak voltage of one of the drive voltage waveforms, is 0 V and the drive frequency. The second drive maximum voltage, which is the voltage between the breakdown voltages of the piezoelectric material and is the other peak voltage of the drive voltage waveform, has the coercive force of the piezoelectric material in a polarity opposite to the first drive maximum voltage. A displacement drive device including a drive circuit that generates a drive voltage waveform having a voltage between 0.1 times and 0.8 times and applies it between the positive electrode and the negative voltage.
  13. 　請求項１２に記載の変位駆動装置であって、
    　前記圧電素子及び前記振動体は圧電アクチュエータを構成し、前記振動体の振動により、前記振動体に触覚を発生させる
    　変位駆動装置。     The displacement drive device according to claim 12.
    The piezoelectric element and the vibrating body constitute a piezoelectric actuator, and a displacement drive device that generates a tactile sensation in the vibrating body by the vibration of the vibrating body.
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WO2023139928A1 (en) * 2022-01-18 2023-07-27 太陽誘電株式会社 Tactile sense generation device, tactile sense generation system, and method for driving tactile sense generation device

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JP2014172314A (en) * 2013-03-11 2014-09-22 Ricoh Co Ltd Droplet discharge head, voltage control method, and image formation device
JP2017157586A (en) * 2016-02-29 2017-09-07 セイコーエプソン株式会社 Method of manufacturing piezoelectric device

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JP2014172314A (en) * 2013-03-11 2014-09-22 Ricoh Co Ltd Droplet discharge head, voltage control method, and image formation device
JP2017157586A (en) * 2016-02-29 2017-09-07 セイコーエプソン株式会社 Method of manufacturing piezoelectric device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023139928A1 (en) * 2022-01-18 2023-07-27 太陽誘電株式会社 Tactile sense generation device, tactile sense generation system, and method for driving tactile sense generation device

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