WO2014174730A1 - Dispositif de génération d'ultrasons - Google Patents

Dispositif de génération d'ultrasons Download PDF

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Publication number
WO2014174730A1
WO2014174730A1 PCT/JP2013/085195 JP2013085195W WO2014174730A1 WO 2014174730 A1 WO2014174730 A1 WO 2014174730A1 JP 2013085195 W JP2013085195 W JP 2013085195W WO 2014174730 A1 WO2014174730 A1 WO 2014174730A1
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WO
WIPO (PCT)
Prior art keywords
frequency
ultrasonic generator
resonance
peak
ultrasonic
Prior art date
Application number
PCT/JP2013/085195
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English (en)
Japanese (ja)
Inventor
山本　浩誠
Original Assignee
株式会社村田製作所
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Application filed by 株式会社村田製作所 filed Critical 株式会社村田製作所
Priority to JP2015513491A priority Critical patent/JP6107940B2/ja
Publication of WO2014174730A1 publication Critical patent/WO2014174730A1/fr

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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
    • B06B1/0607—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 using multiple elements
    • B06B1/0611—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 using multiple elements in a pile
    • B06B1/0614—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 using multiple elements in a pile for generating several frequencies
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K9/00—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers
    • G10K9/12—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated
    • G10K9/122—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated using piezoelectric driving means
    • G10K9/125—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated using piezoelectric driving means with a plurality of active elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/521—Constructional features

Definitions

  • the present invention relates to an ultrasonic generator capable of outputting high sound pressure ultrasonic waves in a wide frequency band, and more specifically, an ultrasonic generator including first and second vibrators is housed in a housing.
  • the present invention relates to an ultrasonic generator.
  • Patent Document 1 discloses an example of this type of ultrasonic generator.
  • an ultrasonic wave generating element is housed in a housing.
  • the ultrasonic wave generating element has a spacer provided with one of a groove or a through hole in the center.
  • a flat plate-like first piezoelectric vibrator is joined to one main surface of the spacer.
  • a flat plate-like second piezoelectric vibrator is joined to the other main surface of the spacer.
  • the first piezoelectric vibrator and the second piezoelectric vibrator are driven so as to vibrate in mutually opposite phases. Thereby, ultrasonic waves are generated.
  • the generated ultrasonic wave propagates along the main surfaces of the first and second piezoelectric vibrators and is output from a sound wave emitting hole provided in the housing.
  • ultrasonic waves are generated by vibrations of the first and second piezoelectric vibrators. Also, it is said that the ultrasonic wave generated by the vibration of the first piezoelectric vibrator and the ultrasonic wave generated by the vibration of the second piezoelectric vibrator are combined to emit an ultrasonic wave with a high sound pressure. Yes.
  • An object of the present invention is to provide an ultrasonic generator capable of outputting ultrasonic waves having high sound pressure in a wide frequency band and having flat frequency characteristics of sound pressure and phase characteristics in a wide frequency band. It is in.
  • the ultrasonic generator according to the present invention includes an ultrasonic generator and a housing.
  • the ultrasonic wave generating element includes a frame, a first vibrator, and a second vibrator.
  • the said frame has the 1st and 2nd main surface which opposes, and one side is provided in the said 1st and 2nd main surface among a groove
  • the first vibrator is bonded to the first main surface of the frame.
  • the second vibrator is bonded to the second main surface of the frame.
  • the housing houses the ultrasonic wave generating element and has a sound wave emitting hole.
  • the sound wave generated by the vibration of the first vibrator and the second vibrator is configured to resonate with the sound wave discharge hole as an open end.
  • a third peak due to resonance existing on a higher frequency side than the second peak, and a valley where the sound pressure is lowest is between the second peak and the third peak.
  • the second frequency region is included in the first frequency region.
  • an acoustic path through which ultrasonic waves propagate in a direction along the main surface of the ultrasonic generator is formed in the casing.
  • the acoustic path faces the first or second vibrator and the main surface of the first and second vibrators. It is formed by the space comprised between the housing parts.
  • the acoustic paths are respectively formed on both main surfaces of the ultrasonic generator.
  • the ultrasonic generator is operated in a buckling tuning fork vibration mode in which the first vibrator and the second vibrator vibrate in opposite phases. Generate sound waves.
  • the ultrasonic generator according to the present invention it is possible to output ultrasonic waves having a high sound pressure in a wide frequency band, and to achieve a flat sound pressure frequency characteristic and a flat phase frequency characteristic in a wide frequency band. Obtainable. Therefore, for example, when the ultrasonic generator according to the present invention is used for detecting distance by a pulse compression technique using modulation such as chirp waves, it is possible to obtain high detection accuracy.
  • FIG. 1 is a front sectional view of an ultrasonic generator according to an embodiment of the present invention.
  • FIG. 2 is a perspective view showing an appearance of the ultrasonic generator according to the embodiment of the present invention.
  • FIG. 3 is a schematic exploded perspective view of an ultrasonic wave generation element provided in the ultrasonic wave generation device according to the embodiment of the present invention.
  • FIG. 4 is a schematic exploded perspective view of an ultrasonic generator according to an embodiment of the present invention.
  • FIG. 5A and FIG. 5B are schematic cross-sectional front sectional views showing a driving state of the ultrasonic generator according to the embodiment of the present invention.
  • FIG. 6 is a diagram illustrating frequency characteristics of sound pressure of acoustic resonance in the ultrasonic generator according to the embodiment of the present invention.
  • FIG. 7 is a diagram illustrating the frequency characteristics of the amplitude of the first piezoelectric vibrator included in the ultrasonic generator according to the embodiment of the present invention.
  • FIG. 8 is a diagram showing frequency characteristics of sound pressure in the ultrasonic generator according to one embodiment of the present invention.
  • FIG. 9 is a diagram showing the frequency characteristics of the phase in the ultrasonic generator according to one embodiment of the present invention.
  • FIG. 1 is a front sectional view of an ultrasonic generator 1 according to this embodiment.
  • FIG. 2 is a perspective view showing an appearance of the ultrasonic generator 1 according to the present embodiment.
  • FIG. 1 shows a cross section taken along line II shown in FIG.
  • the ultrasonic generator 1 has a housing 13 including a substrate 11 and a cap 12. A cap 12 having an opening opened downward is fixed on a flat substrate 11. Thereby, the housing 13 is configured.
  • the ultrasonic wave generating element 14 is accommodated in a space surrounded by the substrate 11 and the cap 12, that is, in the housing 13.
  • the top plate portion of the cap 12 is provided with a plurality of sound wave emission holes 12a to 12d.
  • the sound wave emission holes 12a and 12c are shown.
  • FIG. 3 is a schematic exploded perspective view of the ultrasonic generator 14 provided in the ultrasonic generator 1 according to the present embodiment.
  • the ultrasonic wave generation element 14 has a spacer 15. This spacer corresponds to the frame in the present invention.
  • the spacer 15 is made of an appropriate rigid material such as ceramics or synthetic resin.
  • An opening 15a made of a through hole is provided in the center of the spacer 15, an opening 15a made of a through hole is provided.
  • a first piezoelectric vibrator 17 that is a bimorph piezoelectric vibrator is bonded to the first main surface of the spacer 15 via an adhesive 16.
  • the adhesive 16 has an opening 16a.
  • the adhesive 16 is applied to the upper surface of the spacer 15 in a region excluding the opening 15a. In the first piezoelectric vibrator 17, a portion that is not bonded to the spacer 15, that is, a portion that faces the opening 15 a becomes an excitation portion.
  • a second piezoelectric vibrator 19 that is a bimorph piezoelectric vibrator is bonded to the second main surface of the spacer 15 via an adhesive 18.
  • the adhesive 18 has an opening 18a.
  • the adhesive 18 is applied to the lower surface of the spacer 15 in a region excluding the opening 15a.
  • a portion that is not joined to the spacer 15, that is, a portion that faces the opening 15 a becomes an excitation portion.
  • the spacer 15 is provided with an opening 15a made of a through hole.
  • an opening made of a recess that is, a groove may be provided on both sides in the central region of the spacer 15.
  • the first and second piezoelectric vibrators 17 and 19 are portions where the central region vibrates due to the piezoelectric effect. Accordingly, recesses may be provided on both surfaces of the spacer 15 so as not to prevent this vibration.
  • a vent hole may be provided by a missing portion extending from a part of the periphery of the opening 15 a to the outer periphery of the spacer 15.
  • the first piezoelectric vibrator 17 has a piezoelectric plate 17a.
  • the piezoelectric plate 17a has a square shape in plan view.
  • the piezoelectric plate 17a includes two piezoelectric layers made of piezoelectric ceramics such as lead zirconate titanate-based piezoelectric ceramics, and an internal excitation electrode 17c disposed between the two piezoelectric layers.
  • a first excitation electrode 17b is provided in the center of the upper surface of the piezoelectric plate 17a.
  • the first excitation electrode 17b is provided so as to overlap with the internal excitation electrode 17c via the upper piezoelectric layer.
  • a second excitation electrode 17d is provided at the center of the lower surface of the piezoelectric plate 17a.
  • the second excitation electrode 17d is provided so as to overlap with the internal excitation electrode 17c via the lower piezoelectric layer.
  • the first and second excitation electrodes 17b and 17d are made of a metal such as Ag or Pd or an alloy thereof.
  • the first excitation electrode 17b is connected to extraction electrodes 17b1 and 17b2 extending toward two adjacent corners on the upper surface of the piezoelectric plate 17a.
  • the second excitation electrode 17d is connected to an extraction electrode (not shown) extending toward two adjacent corner portions on the lower surface of the piezoelectric plate 17a.
  • the piezoelectric layer is made of a lead zirconate titanate ceramic, but is not limited thereto.
  • it may be made of a piezoelectric material of lead-free piezoelectric ceramics such as potassium sodium niobate and alkaline niobate ceramics.
  • the piezoelectric layer between the first excitation electrode 17b and the internal excitation electrode 17c and the piezoelectric layer between the internal excitation electrode 17c and the second excitation electrode 17d are polarized in the same direction in the thickness direction.
  • the first excitation electrode 17b is electrically connected to the first terminal electrode 21 through the extraction electrodes 17b1 and 17b2.
  • the second excitation electrode 17d is electrically connected to the first terminal electrode 21 through a lead electrode (not shown).
  • the first terminal electrode 21 is provided on one side surface of the ultrasonic wave generation element 14.
  • a second terminal electrode 22 is provided on the side surface of the ultrasonic generator 14 that faces the side surface on which the first terminal electrode 21 is provided.
  • the internal excitation electrode 17c is electrically connected to the second terminal electrode 22 via a lead electrode (not shown) connected to the internal excitation electrode 17c. Accordingly, by applying an alternating electric field between the first terminal electrode 21 and the second terminal electrode 22, the first piezoelectric vibrator 17 vibrates and generates an ultrasonic wave.
  • the second piezoelectric vibrator 19 is configured in the same manner as the first piezoelectric vibrator 17. However, the second piezoelectric vibrator 19 is configured to vibrate in a reverse phase with respect to the first piezoelectric vibrator 17.
  • the second piezoelectric vibrator 19 has a piezoelectric layer that is polarized in a direction opposite to the piezoelectric layer of the first piezoelectric vibrator 17 in the thickness direction. And are configured to vibrate in reverse phase.
  • the first and second excitation electrodes are electrically connected to the first terminal electrode 21 via an extraction electrode (not shown), and the internal excitation electrode is extracted. It is electrically connected to the second terminal electrode 22 via an electrode (not shown).
  • the second piezoelectric vibrator 19 when an alternating electric field is applied between the first terminal electrode 21 and the second terminal electrode 22, the second piezoelectric vibrator 19 also vibrates and generates ultrasonic waves. Due to the vibrations of the first and second piezoelectric vibrators 17 and 19, ultrasonic waves are generated above and below the ultrasonic wave generation element 14.
  • the ultrasonic wave generated by the ultrasonic generator 14 propagates in the direction indicated by the dashed arrow, and the ultrasonic generator 1 of the ultrasonic generator 1 passes through the sound wave emitting holes 12a to 12d. Released upwards.
  • FIG. 4 is an exploded perspective view of the ultrasonic generator 1 according to the present embodiment.
  • the ultrasonic generating element 14 having a structure in which the first and second piezoelectric vibrators 17 and 19 are bonded to the upper and lower sides of the spacer 15 via the adhesives 16 and 18 includes the substrate 11 and the cap 12. Housed in the housing 13.
  • the ultrasonic wave generating element 14 is fixed on the substrate 11 via a plurality of support members 23.
  • the plurality of support members 23 are mechanically joined and electrically connected to the plurality of electrode lands provided on the substrate 11.
  • the ultrasonic wave generating element 14 is mechanically joined to and electrically connected to the plurality of electrode lands via the plurality of support members 23.
  • the connection member 23 is made of a metal material, and the connection member 23 and the ultrasonic wave generating element 14 are joined by a conductive adhesive, solder, or the like (not shown).
  • the connection member 23 may be made of an adhesive material such as an epoxy resin conductive adhesive.
  • the plurality of support members 23 have a certain thickness, a space is formed between the lower surface of the ultrasonic wave generation element 14, that is, the lower surface of the second piezoelectric vibrator 19, and the upper surface of the substrate 11. For this reason, the vibration of the second piezoelectric vibrator 19 is not easily prevented by the housing 13.
  • a space is formed between the upper surface of the ultrasonic wave generation element 14, that is, the upper surface of the first piezoelectric vibrator 17, and the inner surface of the top plate portion of the cap 12. Therefore, it is difficult for the housing 13 to prevent the vibration of the first piezoelectric vibrator 17.
  • ultrasonic waves generated by the vibrations of the first and second piezoelectric vibrators 17 and 19 are synthesized.
  • acoustic resonance occurs in the form of tube resonance in the ultrasonic generator 1. That is, acoustic resonance occurs with the sound wave emission holes 12a to 12d as open ends.
  • the ultrasonic generator 1 can emit ultrasonic waves with higher sound pressure from the sound wave discharge holes 12a to 12d toward the upper side of the ultrasonic generator 1.
  • the sound wave emission holes 12a to 12d are provided at positions that become the open ends of tube resonance, which will be described later in the explanation of operation.
  • FIGS. 5A and 5B are schematic cross-sectional front sectional views showing a driving state of the ultrasonic generator 1 according to this embodiment.
  • the first and second piezoelectric vibrators 17 and 19 are displaced as shown in FIG. It vibrates so as to repeat the displacement state shown in FIG.
  • the ultrasonic wave generating element 14 vibrates in the buckling tuning fork vibration mode and generates ultrasonic waves. In this case, as shown in FIGS.
  • the excitation part becomes an antinode of vibration, and the portion fixed to the spacer 15 is vibrated. It becomes a clause.
  • the driving state the state in which the center of vibration of the first piezoelectric vibrator 17 is close to the inner surface of the top plate portion of the cap 12 and the separated state are repeated alternately. Therefore, the generated ultrasonic wave is compressed, and as indicated by an arrow B, the ultrasonic wave propagates outward from the center of the vibration antinode, that is, the center of the excitation unit.
  • the ultrasonic waves propagating in the directions indicated by the arrows B and C in FIG. 1 are propagated to the sound wave emitting holes 12a to 12d in a state where the phases are aligned, and from above the sound wave emitting holes 12a to 12d to above the ultrasonic wave generating apparatus 1. Will be released.
  • a first acoustic path is configured by a space between the upper surface of the ultrasonic generator 14 and the inner surface of the top plate portion of the cap 12.
  • a second acoustic path is configured by a space between the lower surface of the ultrasonic wave generation element 14 and the upper surface of the substrate 11.
  • ultrasonic waves propagating in the direction along the principal surfaces of the piezoelectric vibrators 17 and 19 are synthesized, and the sound wave emission holes 12a, Released from 12c.
  • the distance from the center of the vibration antinodes of the first and second piezoelectric vibrators 17 and 19, that is, the center of the excitation unit to the sound wave emission holes 12a to 12d is ⁇ / when the wavelength of the generated ultrasonic wave is ⁇ . It is set to 4.
  • the ultrasonic wave propagating as indicated by an arrow C propagates upward from the second acoustic path on the lower surface side of the ultrasonic wave generating element 14 to the side of the ultrasonic wave generating element 14 as shown in FIG. . Accordingly, the distance from the center of the antinode of the vibration of the first piezoelectric vibrator 17 to the sound wave emitting holes 12a to 12d is different from the distance from the center of the antinode of the vibration of the second piezoelectric vibrator 19 to the sound wave emitting holes 12a to 12d.
  • the thickness of the ultrasonic wave generating element 14 can be made so small that it can be ignored with respect to the wavelength.
  • the frequency of the ultrasonic wave generated by the ultrasonic generator 1 is 60 kHz
  • the wavelength is 5.7 mm.
  • the thickness of the ultrasonic wave generating element 14 is about 200 to 400 ⁇ m. Therefore, the difference between the distance from the center of vibration of the first piezoelectric vibrator 17 to the sound wave emission holes 12a to 12d and the distance from the center of vibration of the second piezoelectric vibrator 19 to the sound wave emission holes 12a to 12d. Is about 200 to 400 ⁇ m, that is, about 0.03 ⁇ to 0.07 ⁇ .
  • FIG. 6 is a diagram showing the frequency characteristics of the sound pressure of the acoustic resonance in the ultrasonic generator according to this embodiment.
  • the frequency characteristic of the sound pressure of acoustic resonance there are a peak on the relatively low frequency side indicated by the arrow D and a peak on the relatively high frequency side indicated by the arrow E.
  • the peak on the relatively low frequency side indicated by the arrow D corresponds to the second peak in the present invention.
  • the peak on the relatively high frequency side indicated by the arrow E corresponds to the third peak in the present invention.
  • the sound pressure peak of resonance indicated by the arrow D is a resonance mode mainly including resonance generated between the second piezoelectric vibrator 19 and the sound wave emission holes 12a to 12d by the vibration of the second piezoelectric vibrator 19. is there.
  • the resonance sound pressure peak indicated by the arrow D appears on the lower frequency side than the resonance sound pressure peak indicated by the arrow E because the acoustic path length is long.
  • the sound pressure peak of resonance indicated by an arrow E is a resonance mode mainly including resonance generated between the first piezoelectric vibrator 17 and the sound wave emission holes 12a to 12d by the vibration of the first piezoelectric vibrator 17. is there.
  • the sound pressure peak of resonance indicated by arrow E appears on the higher frequency side than the sound pressure peak of resonance indicated by arrow D because the acoustic path length is short. As shown in FIG. 6, there is a valley where the sound pressure is lowest between the resonance sound pressure peak indicated by arrow D and the resonance sound pressure peak indicated by arrow E. In FIG. 6, the valley is indicated by an arrow F.
  • the frequency characteristics of the sound pressure of acoustic resonance can be adjusted by adjusting the positions and sizes of the sound wave emission holes 12a to 12d.
  • the sound pressure peak of resonance on the relatively low frequency side indicated by the arrow D is configured to be located at 40 kHz.
  • the sound pressure peak of resonance on the relatively high frequency side indicated by arrow E is configured to be located at 62 kHz.
  • a valley indicated by an arrow F is located at 52 kHz.
  • FIG. 7 is a diagram showing the frequency characteristics of the amplitude of the first piezoelectric vibrator 17.
  • the frequency characteristic of the amplitude of the second piezoelectric vibrator 19 is the same as the frequency characteristic of the amplitude of the first piezoelectric vibrator 17.
  • the frequency characteristic of the amplitude of the first piezoelectric vibrator 17 there is an amplitude peak indicated by an arrow G.
  • the amplitude peak indicated by the arrow G corresponds to the first peak in the present invention. This peak is due to resonance of the first piezoelectric vibrator 17. For this reason, the frequency of the peak of the amplitude indicated by the arrow G matches the resonance frequency of the first piezoelectric vibrator 17.
  • the peak frequency of the amplitude indicated by the arrow G that is, the resonance frequency of the first piezoelectric vibrator 17 is 40 kHz.
  • the resonance frequency of the second piezoelectric vibrator 19 is also 40 kHz.
  • the feature of this embodiment is that the amplitude indicated by the arrow G in FIG. 7 due to the resonance of the first and second piezoelectric vibrators 17 and 19 in the frequency characteristics of the amplitudes of the first and second piezoelectric vibrators 17 and 19.
  • the first frequency region Y which is a region located on the higher frequency side from the peak, and the arrow in FIG. 6 from the valley indicated by the arrow F in FIG. 6 in the frequency characteristics of the sound pressure of the acoustic resonance. That is, at least a part of the second frequency region X, which is a frequency region between the resonance sound pressure peaks indicated by E, is configured to overlap.
  • the first piezoelectric vibrator 17 increases as the frequency increases.
  • the change in amplitude due to this frequency gradually becomes gentle.
  • the frequency is The higher the sound pressure, the higher the sound pressure of acoustic resonance. That is, in the second frequency region, which is the frequency region X from the valley indicated by the arrow F to the resonance sound pressure peak indicated by the arrow E, the frequency characteristic of the sound pressure of acoustic resonance increases to the right.
  • the first frequency region Y is at least partially overlapped with the second frequency region X, it is possible to output an ultrasonic wave having a high sound pressure in a wide frequency band and a flat sound in the wide frequency band.
  • a frequency characteristic of pressure and a frequency characteristic of flat phase can be obtained.
  • FIG. 8 is a diagram showing frequency characteristics of sound pressure in the ultrasonic generator 1 according to this embodiment.
  • FIG. 9 is a diagram showing the frequency characteristics of the phase in the ultrasonic generator 1 according to the present embodiment.
  • FIG. 8 is a diagram showing the frequency characteristics of sound pressure (dB) when the resonance phenomenon caused by the piezoelectric vibrator and the acoustic resonance phenomenon occur simultaneously.
  • the sound pressure in the frequency region of 50 kHz to 70 kHz is smaller than the frequency region in the vicinity of 40 kHz, but the sound pressure is flat in the frequency band of about 20 kHz.
  • Frequency characteristics are obtained. This is because, in the frequency range of 50 kHz to 70 kHz, the first and second piezoelectric vibrators 17 and 19 have a slight amplitude because they are located away from the resonance frequencies of the first and second piezoelectric vibrators 17 and 19. This is because the sound pressure is increased to some extent due to the resonance sound pressure peak indicated by arrow E in FIG.
  • the amplitude of the first and second piezoelectric vibrators 17 and 19 is slightly small, so that the piezoelectric ceramic coercive electric field of the piezoelectric layer constituting the first and second piezoelectric vibrators 17 and 19 is reduced.
  • a high sound pressure can be obtained without applying cracks to the piezoelectric layer by applying a driving voltage that does not exceed.
  • the phase of the amplitude of the first and second piezoelectric vibrators 17 and 19 changes by 180 degrees in a narrow frequency band near the resonance frequency due to resonance.
  • the sound pressure phase of acoustic resonance changes by 180 degrees in a relatively wide frequency band near the frequency of acoustic resonance due to acoustic resonance.
  • the sound pressure peak of resonance on the relatively low frequency side indicated by the arrow D is 40 kHz
  • the resonance frequency of the first and second piezoelectric vibrators 17 and 19 is 40 kHz. Yes. For this reason, as shown in FIG.
  • the resonance frequency of the first and second piezoelectric vibrators 17 and 19 and the position of the sound pressure peak of the resonance on the relative low frequency side indicated by the arrow D are away from each other.
  • the frequency characteristic of the phase is almost flat.
  • both the frequency characteristics of the sound pressure and the frequency characteristics of the phase are substantially flat in the frequency region of 52 kHz or higher. For this reason, when the ultrasonic generator 1 of the present embodiment is used for the purpose of detecting a distance by a pulse compression technique using a modulation such as a chirp wave, high detection accuracy can be obtained.
  • the first and second frequency regions Y and X are desirably arranged so that the entire second frequency region X, which is a relatively narrow frequency region, is included in the first frequency region Y.
  • the entire second frequency region X overlaps the first frequency region Y.
  • a part of the second frequency region X may overlap the first frequency region Y.
  • the positional relationship between the first frequency region and the second frequency region is the resonance sound pressure peak indicated by arrows D and E by adjusting the positions and sizes of the sound wave emission holes 12a to 12d.
  • the first and second piezoelectric vibrations can be obtained by changing the thickness and vibration length of the piezoelectric layer constituting the first and second piezoelectric vibrators 17 and 19 and the piezoelectric constant of the piezoelectric ceramic constituting the piezoelectric layer.
  • the frequency position of the resonance frequency of the children 17 and 19 can be easily set.
  • the first and second piezoelectric vibrators 17 and 19 which are bimorph piezoelectric vibrators are used.
  • the first and second vibrators are The present invention is not limited to the bimorph type piezoelectric vibrator.
  • Other piezoelectric vibrators such as a unimorph type piezoelectric vibrator may be used.
  • not only the piezoelectric vibrator but also other electroacoustic transducers may be used.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

L'invention concerne un dispositif de génération d'ultrasons qui est capable de produire des ultrasons ayant une pression acoustique élevée sur une bande de fréquences large, les caractéristiques de pression acoustique et de phase/fréquence étant plates sur une bande de fréquences large. Elle concerne un dispositif de génération d'ultrasons (1) dans lequel un élément de génération d'ultrasons (14) est logé à l'intérieur d'un boîtier (13) qui possède des trous d'émission d'ondes acoustiques (12a, 12c). Ledit élément de génération d'ultrasons (14) possède une entretoise (15), un premier transducteur (17) lié à une première surface principale de ladite entretoise (15), et un deuxième transducteur lié à une deuxième surface principale. Ce dispositif de génération d'ultrasons (1) est conçu de telle façon que : les ondes acoustiques générées par la vibration des premier et deuxième transducteurs (17, 19) résonnent, les trous d'émission d'ondes acoustiques (12a, 12c) agissant comme extrémités ouvertes dans ladite résonance ; les caractéristiques amplitude/fréquence des premier et deuxième transducteurs (17, 19) présentent une crête due à ladite résonance ; et une première région de fréquences qui s'étend depuis ladite crête sur son côté hautes fréquences recouvre une deuxième région de fréquences entre une vallée dans les caractéristiques de fréquence de pression acoustique de la résonance mentionnée ci-dessus et une crête de résonance haute fréquence de ces caractéristiques.
PCT/JP2013/085195 2013-04-25 2013-12-27 Dispositif de génération d'ultrasons WO2014174730A1 (fr)

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
WO2023095829A1 (fr) * 2021-11-26 2023-06-01 株式会社村田製作所 Transducteur ultrasonore
JP7405016B2 (ja) 2020-06-23 2023-12-26 トヨタ紡織株式会社 遮音装置

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Publication number Priority date Publication date Assignee Title
WO2013051400A1 (fr) * 2011-10-03 2013-04-11 株式会社村田製作所 Dispositif de génération d'ondes ultrasonores

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Publication number Priority date Publication date Assignee Title
JPH0446798U (fr) * 1990-08-28 1992-04-21

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
WO2013051400A1 (fr) * 2011-10-03 2013-04-11 株式会社村田製作所 Dispositif de génération d'ondes ultrasonores

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7405016B2 (ja) 2020-06-23 2023-12-26 トヨタ紡織株式会社 遮音装置
WO2023095829A1 (fr) * 2021-11-26 2023-06-01 株式会社村田製作所 Transducteur ultrasonore

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