Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JP2007088680 PROBLEM TO BE SOLVED: To provide an electrostatic ultrasonic transducer ensuring the electrical safety without the conductive part being exposed on the surface. SOLUTION: A first fixed electrode 10A in which a plurality of through holes 14 are formed, a second fixed electrode 10B in which a plurality of through holes 14 paired with the first fixed electrode are formed, and the pair A vibrating membrane 12 having a conductive layer 121 sandwiched between the fixed electrodes and a DC bias voltage applied to the conductive layer by a DC bias power supply 16, a pair of fixed electrodes, and a holding member for holding the vibrating membrane. An electrostatic ultrasonic transducer in which an alternating current signal is applied by the signal source 16 between the pair of fixed electrodes, wherein a base material of the first and second fixed electrodes is the non-conductor 10; A conductive film 20 is formed on the surface of the non-conductive material to be the counter electrode unit 21 facing the vibrating film, and the step 17 of the counter electrode unit is formed of an insulator. [Selected figure] Figure 1 Electrostatic ultrasonic transducer and method of manufacturing the same [0001] The present invention relates to an electrostatic ultrasonic transducer generating constant high sound pressure over a wide frequency band and an ultrasonic speaker using the same. [0002] Conventional ultrasonic transducers are mostly resonant type using piezoelectric ceramic. 04-05-2019 1 Here, the configuration of a conventional ultrasonic transducer is shown in FIG. Conventional ultrasonic transducers are mostly resonant type using piezoelectric ceramic as a vibrating element. The ultrasonic transducer shown in FIG. 6 uses piezoelectric ceramic as a vibrating element to perform both conversion from an electrical signal to ultrasonic waves and conversion from ultrasonic waves to electrical signals (transmission and reception of ultrasonic waves). The bimorph type ultrasonic transducer shown in FIG. 6 is composed of two piezoelectric ceramics 61 and 62, a cone 63, a case 64, leads 65 and 66, and a screen 67. [0003] The piezoelectric ceramics 61 and 62 are bonded to each other, and the lead 65 and the lead 66 are connected to the surface opposite to the bonding surface, respectively. Since the resonance type ultrasonic transducer utilizes the resonance phenomenon of piezoelectric ceramic, the transmission and reception characteristics of the ultrasonic wave become good in a relatively narrow frequency band around the resonance frequency. [0004] Unlike the resonant ultrasonic transducer shown in FIG. 6 described above, the electrostatic ultrasonic transducer is conventionally known as a broadband oscillation type ultrasonic transducer capable of generating high sound pressure over a high frequency band. This electrostatic ultrasonic transducer is called a pull type because it works only in the direction in which the vibrating membrane is attracted to the fixed electrode. FIG. 7 shows a specific configuration of the broadband oscillation type ultrasonic transducer (Pull type). [0005] The ultrasonic transducer of the electrostatic type shown in FIG. 7 uses a dielectric 131 (insulator) such as PET (poly-ethylene-terephthalate resin) having a thickness of about 3 to 10 μm as a vibrator. For the dielectric 131, the upper electrode 132 formed as a metal foil such as aluminum is integrally formed on the upper surface thereof by a process such as evaporation, and the lower electrode 133 formed of brass is the lower surface of the dielectric 131 It is provided to contact the part. The lower electrode 133 is connected to the lead 152 and fixed to a base plate 135 made of Bakelite or the like. 04-05-2019 2 [0006] Further, a lead 153 is connected to the upper electrode 132, and the lead 153 is connected to a DC bias power supply 150. A DC bias voltage for attracting the upper electrode of about 50 to 150 V is constantly applied to the upper electrode 132 by the DC bias power supply 150 so that the upper electrode 132 is attracted to the lower electrode 133 side. 151 is a signal source. [0007] The dielectric 131 and the upper electrode 132 and the base plate 135 are crimped by the case 130 together with the metal rings 136, 137 and 138 and the mesh 139. On the surface of the lower electrode 133 on the side of the dielectric 131, a plurality of microgrooves of approximately several tens to several hundreds of μm having an uneven shape are formed. Since this minute groove serves as an air gap between the lower electrode 133 and the dielectric 131, the distribution of capacitance between the upper electrode 132 and the lower electrode 133 changes minutely. [0008] The random minute grooves are formed by manually roughening the surface of the lower electrode 133 with a file. In the electrostatic ultrasonic transducer, the frequency characteristics of the ultrasonic transducer shown in FIG. 7 are as shown by a curve Q1 in FIG. 8 by thus forming an infinite number of capacitors having different sizes and depths of air gaps. It is broadband. [0009] In the ultrasonic transducer configured as described above, a rectangular wave signal (50 to 150 Vp-p) is applied between the upper electrode 12 and the lower electrode 133 in a state where a DC bias voltage is applied to the upper electrode 132. There is. Incidentally, as shown by a curve Q2 in FIG. 8, the frequency characteristic of the resonance type ultrasonic transducer has a center frequency (resonance frequency of the piezoelectric ceramic) of, for example, 40 kHz and 04-05-2019 3 ± 5 kHz with respect to the center frequency which is the maximum sound pressure. At a frequency of -30 dB relative to the maximum sound pressure. On the other hand, the frequency characteristic of the broadband oscillation type ultrasonic transducer of the above configuration is flat from 40 kHz to 100 kHz, and is about ± 6 dB at 100 kHz as compared to the maximum sound pressure (see Patent Documents 1 and 2) . Japanese Patent Laid-Open No. 2000-50387 Japanese Patent Laid-Open No. 2000-50392 [0010] As described above, unlike the resonant ultrasonic transducer shown in FIG. 6, the electrostatic ultrasonic transducer shown in FIG. 7 can generate relatively high sound pressure over a wide frequency band conventionally. It is known as a broadband ultrasound transducer (Pull type). However, as shown in FIG. 8, the sound pressure is lower at 120 dB or less for the electrostatic ultrasonic transducer compared to 130 dB or more for the resonant ultrasonic transducer as shown in FIG. The sound pressure was slightly short to use it. [0011] Here, the ultrasonic speaker will be described. An ultrasonic wave is modulated by an audio signal of a signal source by AM-modulating a signal in an ultrasonic frequency band called a carrier wave with an audio signal (a signal in an audible frequency band) and driving an ultrasonic transducer with this modulation signal. The sound waves of the state are emitted into the air, and the non-linearity of the air causes the original audio signal to self-reproduce in the air. [0012] That is, since the sound wave is a compressional wave propagating through air as a medium, in the process of propagation of the modulated ultrasonic wave, dense and sparse portions of air become prominent, and the dense portion has a high speed of sound and is sparse. As the speed of sound is slowed, the modulation wave itself is distorted, so that the waveform is separated into the carrier wave (ultrasonic wave) and the audio wave (original audio signal), and we human beings the audible sound below 20 kHz (original audio signal) The principle is that you can hear only, and is generally called parametric array effect. [0013] 04-05-2019 4 Although ultrasonic sound pressure of 120 dB or more is necessary for the above-mentioned parametric effect to fully appear, it is difficult to achieve this value with electrostatic ultrasonic transducers, and ceramic piezoelectric elements such as PZT and PVDF, etc. are exclusively used. Polymer piezoelectric elements have been used as ultrasound transmitters. However, since the piezoelectric element has a sharp resonance point regardless of the material and is driven at the resonance frequency and put into practical use as an ultrasonic speaker, the frequency range where high sound pressure can be secured is extremely narrow. That is, it can be said that it is a narrow band. [0014] Generally, the maximum audio frequency band of human beings is said to be 20 Hz to 20 kHz, and has a band of about 20 kHz. That is, in the ultrasonic speaker, it is impossible to faithfully demodulate the original audio signal unless a high sound pressure is secured over the 20 kHz frequency band in the ultrasonic region. It will be easily understood that it is difficult to faithfully reproduce (demodulate) this wide band of 20 kHz at the very bottom of a conventional resonance type ultrasonic speaker using a piezoelectric element. [0015] In fact, in the ultrasonic speaker using the conventional ultrasonic transducer of the resonance type, (1) the band is narrow and the reproduction sound quality is bad, (2) if the AM modulation degree is too large, the demodulation sound is distorted by at most 0.5 (3) When the input voltage is increased (when the volume is raised), the vibration of the piezoelectric element becomes unstable and the sound is broken. When the voltage is further increased, the piezoelectric elements themselves are easily broken. (4) It is difficult to achieve array formation, upsizing, downsizing, and thus cost increase. [0016] On the other hand, the ultrasonic speaker using the electrostatic ultrasonic transducer (Pull type) 04-05-2019 5 shown in FIG. 8 can almost solve the problems of the above-mentioned prior art, but it can cover a wide band but the demodulation sound is sufficient. There was a problem that the absolute sound pressure was insufficient to achieve a good volume. Further, in the Pull-type ultrasonic transducer, electrostatic force acts only in a direction to attract only to the fixed electrode side, which corresponds to a vibrating film (corresponding to the upper electrode 132 in FIG. 7). When used in an ultrasonic speaker, there is a problem that the vibration of the vibrating membrane directly generates an audible sound, since the symmetry of the vibration of (a) is not maintained. [0017] In contrast, we have already proposed ultrasound transducers that can generate acoustic signals at sound pressure levels high enough to obtain parametric array effects over a wide frequency band. The configuration of this ultrasonic transducer is shown in FIG. In FIG. 9, the ultrasonic transducer is sandwiched between a pair of fixed electrodes 10A and 10B using a base material in which a through hole 14 is formed at a position facing the vibrating film 12 having the conductive layer 121 as a conductive material. In the state where the DC bias voltage is applied by the DC power supply 16, the AC signals 18A and 18B are applied by the signal source 18 to the pair of fixed electrodes. Reference numeral 120 denotes an insulating film for forming the vibrating film 12, and 17 denotes a part of the pair of fixed electrodes 10A and 10B, and has a function of holding the vibrating film 12 and electrostatic force between the vibrating film 13 and Is a counter electrode forming body having a function of forming a counter electrode portion 19 which is a portion on which [0018] This ultrasonic transducer is called a Push-Pull type ultrasonic transducer, and the vibrating membrane sandwiched by a pair of fixed electrodes has the same electrostatic attraction and electrostatic repulsion in the direction according to the polarity of the AC signal. In order to receive in the direction and simultaneously, the vibration of the vibrating membrane can not only be made large enough to obtain the parametric array effect, but also the symmetry of the vibration is secured, so that it can be compared to the conventional Pull type ultrasonic transducer. High sound pressure can be generated over a wide frequency band. [0019] By the way, in such a Push-Pull type electrostatic ultrasonic transducer, the base material of the fixed electrode is a conductive material, and the conductive part is largely exposed on the surface, so that it is in an extremely dangerous state. It was necessary to fit in a case with a safety 04-05-2019 6 net. [0020] The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an electrostatic ultrasonic transducer ensuring the electrical safety without the conductive portion being exposed on the surface, and a method of manufacturing the same. I assume. [0021] In order to achieve the above object, in the electrostatic ultrasonic transducer according to the present invention, a first fixed electrode in which a plurality of through holes are formed, and a plurality of through holes paired with the first fixed electrode are formed. A second fixed electrode, a conductive film sandwiched between the pair of fixed electrodes, and a vibrating film to which a DC bias voltage is applied to the conductive layer, a pair of fixed electrodes, and a holding film for holding the vibrating film A member, and an electrostatic ultrasonic transducer to which an alternating current signal is applied between the pair of fixed electrodes, wherein the base material of the first and second fixed electrodes is a non-conductive material, and the vibration is A conductive film is formed on the surface of the non-conductive material to be a counter electrode portion facing the film, and a step portion of the counter electrode portion is formed of an insulator. [0022] In the electrostatic ultrasonic transducer of the present invention having the above configuration, a plurality of through holes are formed at positions facing the first fixed electrode and the second fixed electrode, and a DC bias voltage is applied to the conductive layer of the diaphragm. Since an AC signal which is a drive signal is applied to the pair of fixed electrodes consisting of the first and second fixed electrodes in the applied state, the vibrating film sandwiched between the pair of fixed electrodes has the polarity of the AC signal. In the direction according to, electrostatic attraction force and electrostatic repulsion force are simultaneously received in the same direction. Therefore, not only the vibration of the vibrating membrane can be made sufficiently large to obtain a parametric effect, but also the symmetry of the vibration is ensured, so that high sound pressure can be generated over a wide frequency band. 04-05-2019 7 Furthermore, a base material of the first and second fixed electrodes is a non-conductive material, and a conductive film is formed on the non-conductive surface to be a counter electrode portion facing the vibrating film, and the counter electrode portion Since the step portion is formed of an insulator, it is possible to realize an electrostatic ultrasonic transducer that secures the electrical safety without the conductive portion being exposed on the surface of the transducer. [0023] In the method of manufacturing an electrostatic ultrasonic transducer according to the present invention, a first fixed electrode having a plurality of through holes formed therein, and a plurality of through holes forming a pair with the first fixed electrode are formed. A vibrating film to which a fixed electrode and a pair of fixed electrodes are sandwiched and having a conductive layer, and a DC bias voltage is applied to the conductive layer, and a holding member holding the pair of fixed electrodes and the vibrating film A method of manufacturing an electrostatic ultrasonic transducer, wherein an alternating current signal is applied between the pair of fixed electrodes, wherein the first and second fixed electrodes have the plurality of holes in a non-conductive material. A first step of forming a through hole by sandblasting or etching, a second step of removing the mask member after the through hole is formed, and Non-conductive material with through holes After the third step of forming a metal thin film of a predetermined thickness on the surface, and laminating a nonconductive photosensitive resist material on the non-conductor on which the metal thin film is formed, the above-mentioned on the upper surface of the photosensitive resist A mask member for masking the through hole and a region facing the region in the vicinity of the through hole is placed on the upper surface of the photosensitive resist, and a fourth step of exposing and exposing the mask member is removed and developed. The method is characterized in that the metal thin film is manufactured by the fifth step of forming a counter electrode forming body on a non-conductor formed on the surface. [0024] In the method of manufacturing an electrostatic ultrasonic transducer according to the present invention having the above configuration, the first and second fixed electrodes forming a pair cover a mask member in which a pattern of the plurality of holes is formed in a nonconductive material. A first step of forming a through hole by sandblasting or etching, a second step of peeling the mask member after the through hole is formed, and a nonconductive material in which the through hole is formed After the third step of forming a metal thin film of a predetermined thickness on one side, and laminating a nonconductive photosensitive resist material on the nonconductor on which the metal thin film is formed, the above-mentioned on the upper surface of the photosensitive resist A mask member for masking the through hole and a region facing the region in the vicinity of the through hole is placed on the upper surface of the 04-05-2019 8 photosensitive resist, and a fourth step of exposing and exposing the mask member is removed and developed. , Said Genus thin film is fabricated by a fifth step of forming a counter electrode formed body on non-conductive formed on the surface. [0025] According to the manufacturing method of the electrostatic ultrasonic transducer of the present invention having the above configuration, not only the vibration of the vibrating film can be made sufficiently large to obtain the parametric effect, but also the symmetry of the vibration is secured. Thus, there is provided an electrostatic ultrasonic transducer capable of generating high sound pressure over a wide frequency band. Further, according to the manufacturing method of the electrostatic ultrasonic transducer of the present invention having the above configuration, the base material of the fixed electrode is made non-conductive, the counter electrode portion is formed of a metal deposition film, and the step portion of the counter electrode portion Since the (counter electrode forming body) is formed of an insulator, the conductive portion (voltage marking portion) of the fixed electrode is not exposed to the surface, which is extremely safe electrically. [0026] In the method of manufacturing an electrostatic ultrasonic transducer according to the present invention, a first fixed electrode having a plurality of through holes formed therein, and a plurality of through holes forming a pair with the first fixed electrode are formed. A vibrating film to which a fixed electrode and a pair of fixed electrodes are sandwiched and having a conductive layer, and a DC bias voltage is applied to the conductive layer, and a holding member holding the pair of fixed electrodes and the vibrating film A method of manufacturing an electrostatic ultrasonic transducer having an AC signal applied between the pair of fixed electrodes, wherein the first and second fixed electrodes pass through the plurality of nonconductive members. A first step of covering a mask member having a pattern of holes formed thereon and forming a through hole by sandblasting or etching; and a second step of peeling the mask member after the through hole is formed; Non-conductive in which the through hole is formed A third step of forming a metal thin film having a predetermined film thickness on one side of the metal layer, a through hole on the nonconductive layer on which the metal thin film is formed, and a mask member for masking a region near the through hole. A squeegee is formed by setting a counter electrode forming material for forming an insulating counter electrode forming body which is a stepped portion of a counter electrode portion which is placed on the surface and which faces the vibrating film on the non-conductor surface. In the fourth step of 04-05-2019 9 moving to apply the counter electrode forming material to a portion of the non-conductor surface which is not masked by the mask member, and in the fourth step, the mask after the application of the counter electrode forming material is completed And a fifth step of removing the member and drying the counter electrode forming body formed on the non-conductive material. [0027] In the method of manufacturing an electrostatic ultrasonic transducer according to the present invention having the above configuration, the first and second fixed electrodes forming a pair are mask members in which a pattern of the plurality of through holes is formed in a non-conductive material. A first step of coating and forming a through hole by sandblasting or etching, a second step of peeling the mask member after the through hole is formed, and a non-conductive material in which the through hole is formed A third step of forming a metal thin film having a predetermined film thickness on one side of the metal layer, a through hole on the nonconductive layer on which the metal thin film is formed, and a mask member for masking a region near the through hole. A squeegee is formed by setting a counter electrode forming material for forming an insulating counter electrode forming body which is a stepped portion of a counter electrode portion which is placed on the surface and which faces the vibrating film on the non-conductor surface. Move the counter electrode type Removing the mask member after the application of the counter electrode forming material is completed in the fourth step of applying the material on the portion of the non-conductive surface that is not masked by the mask member, and in the fourth step; It manufactures by the 5th process of drying the counter electrode formation body formed on the conductor. [0028] According to the manufacturing method of the electrostatic ultrasonic transducer of the present invention having the above configuration, not only the vibration of the vibrating film can be made sufficiently large to obtain the parametric effect, but also the symmetry of the vibration is secured. Thus, there is provided an electrostatic ultrasonic transducer capable of generating high sound pressure over a wide frequency band. Further, according to the manufacturing method of the electrostatic ultrasonic transducer of the present invention having the above configuration, the base material of the fixed electrode is made non-conductive, the counter electrode portion is formed of a metal deposition film, and the step portion of the counter electrode portion Since the (counter electrode forming body) is formed of an insulator, the conductive portion (voltage marking portion) of the fixed electrode is not exposed to the surface, which is extremely safe electrically. 04-05-2019 10 Furthermore, according to the manufacturing method of the electrostatic ultrasonic transducer of the present invention having the above configuration, when using glass as a base material of the fixed electrode, the screen printing method does not need to apply a large stress to the glass. There is an effect that the risk of breaking the fixed electrode is cut with very little. [0029] In the method of manufacturing an electrostatic ultrasonic transducer according to the present invention, a first fixed electrode having a plurality of through holes formed therein, and a plurality of through holes forming a pair with the first fixed electrode are formed. A vibrating film to which a fixed electrode and a pair of fixed electrodes are sandwiched and having a conductive layer, and a DC bias voltage is applied to the conductive layer, and a holding member holding the pair of fixed electrodes and the vibrating film A method of manufacturing an electrostatic ultrasonic transducer, wherein an alternating current signal is applied between the pair of fixed electrodes, wherein the first and second fixed electrodes are based on a nonconductive material, A through hole is formed in advance with a predetermined diameter and pitch, and a conductive layer is formed on both of its both surfaces, and an outer peripheral portion of the through hole is formed on one surface of the printed board coated with the resist over the entire surface of the conductive layer. For stripping the resist at Mask for forming a first step of applying a resist for a resist, and a pattern for masking a region other than the region facing the outer peripheral portion of the through hole on the resist for peeling of a printed substrate on which the resist for peeling is applied A second step of coating a member on the peeling resist and performing exposure and development; and a third step of peeling the resist in a portion not masked with the peeling resist by the resist peeling treatment; After the completion of the third step, it is characterized in that it is manufactured by the fourth step of removing the remaining peeling resist. [0030] In the method of manufacturing an electrostatic ultrasonic transducer according to the present invention having the above configuration, the first and second fixed electrodes forming a pair have non-conductive materials as a base material, and through holes with a predetermined diameter and pitch in advance. A peeling layer for peeling off the resist at the outer peripheral portion of the through hole on one side of a printed substrate which is formed, the conductive layer is formed on the entire surface, and the entire surface of the conductive layer is coated with the resist A mask member having a first step of applying a resist, and a pattern for masking a region other than the region facing the outer peripheral portion of the through hole on the peeling resist of the printed substrate on which the peeling resist is applied A second step of coating on the resist for stripping and performing exposure and development processing, and the 04-05-2019 11 above-mentioned portion of the portion not masked with the resist for stripping by resist stripping processing. A third step of peeling off the resist, after the end third step, is manufactured by a fourth step of removing the peeling the remaining resist. [0031] According to the manufacturing method of the electrostatic ultrasonic transducer of the present invention having the above configuration, not only the vibration of the vibrating film can be made sufficiently large to obtain the parametric effect, but also the symmetry of the vibration is secured. Thus, there is provided an electrostatic ultrasonic transducer capable of generating high sound pressure over a wide frequency band. Further, according to the manufacturing method of the electrostatic ultrasonic transducer of the present invention having the above configuration, the base material of the fixed electrode is made non-conductive, the counter electrode portion is formed of a metal deposition film, and the step portion of the counter electrode portion Since the (counter electrode forming body) is formed of an insulator, the conductive portion (voltage marking portion) of the fixed electrode is not exposed to the surface, which is extremely safe electrically. Furthermore, according to the manufacturing method of the electrostatic ultrasonic transducer of the present invention having the above configuration, since the printed circuit board to which the conductive layer (copper foil) and the resist processing are applied in advance is used, the number of manufacturing steps is small. And the manufacturing cost can be reduced. [0032] The ultrasonic speaker according to the present invention generates and outputs the electrostatic ultrasonic transducer according to claim 1, a signal source for generating a signal wave of an audio frequency band, and a carrier wave of an ultrasonic frequency band. Carrier wave supply means, and modulation means for modulating the carrier wave with a signal wave of audio frequency band outputted from the signal source, and the electrostatic ultrasonic transducer comprises the first and second fixed elements. It is characterized in that it is driven by a modulation signal outputted from the modulation means applied between the electrode and the conductive layer of the vibrating membrane. [0033] 04-05-2019 12 In the ultrasonic speaker according to the present invention having the above configuration, a signal wave in the audible frequency band is generated by the signal source, and a carrier wave in the ultrasonic frequency band is generated and output by the carrier wave supply means. Further, the carrier wave is modulated by the signal wave in the audio frequency band outputted from the signal source by the modulation means, and the modulation signal outputted from the modulation means is the electrode layer of the first and second fixed electrodes and the diaphragm. And is applied and driven. [0034] Since the ultrasonic speaker according to the present invention is configured using the electrostatic ultrasonic transducer having the above configuration, it is possible to generate an acoustic signal at a sound pressure level high enough to obtain a parametric array effect over a wide frequency band. A sound wave speaker can be realized. Furthermore, since the electrostatic ultrasonic transducer of the above configuration is used, that is, in the electrostatic ultrasonic transducer, the base material of the first and second fixed electrodes forming a pair is a nonconductive body, and the vibrating film is A conductive film is formed on the surface of the non-conductive material to be the opposing electrode portion facing the electrode, and the step portion of the opposing electrode portion is formed of an insulator, so that the conductive portion is not exposed to the surface of the transducer Ultrasonic speaker with high target safety can be realized. [0035] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The configuration of an electrostatic ultrasonic transducer according to an embodiment of the present invention is shown in FIG. 04-05-2019 13 1 (A) shows the configuration of the electrostatic ultrasonic transducer, and FIG. 1 (B) is a view of only one fixed electrode of the electrostatic ultrasonic transducer viewed from the vibrating film side, and FIG. 1 (C) is The top view which fractured a part of electrostatic type ultrasonic transducer is shown. In FIG. 1, an electrostatic ultrasonic transducer 1 according to an embodiment of the present invention is held between a pair of fixed electrodes 10A and 10B and a pair of fixed electrodes, and a vibrating film 12 having a conductive layer 121 and a pair of fixed electrodes. It has electrodes 10A and 10B and a member (not shown) for holding the vibrating membrane 12. [0036] Further, the pair of fixed electrodes 10A and 10B have the same number and a plurality of through holes 14 at positions facing each other with the vibrating film 12 interposed therebetween. In the pair of fixed electrodes 10A and 10B, the base material is the nonconductive 10, and the conductive film 20 is formed on the surface of the nonconductive 10 serving as the opposite electrode facing the vibrating film 12, and the opposite electrode A counter electrode forming body 17 to be a step portion of is formed of an insulator (for example, any of a liquid solder resist, a photosensitive coating material, a nonconductive paint, an electrodeposition material and the like). [0037] The vibrating film 12 is formed of an insulating film (insulator) 120 and has a conductive layer 121 formed of a conductive material. That is, in order to secure insulation with the conductive film 20 provided on the fixed electrodes 10A and 10B, the vibrating film 12 has a metal deposition layer (conductive layer) 121 serving as an electrode portion at the central portion, and both surfaces thereof. A sandwich structure is formed by covering the film with an insulating film 120 such as a polymer film excellent in insulation resistance. [0038] The conductive layer 121 in the vibrating film 12 may be either single polarity (positive or negative) by the DC bias power supply 16. The DC bias voltage is applied to the conductive film 20 of the fixed electrode 10A and the fixed electrode 10B superimposed on the DC bias voltage 04-05-2019 14 and the phase inversion of each other output from the signal source 18 is performed. The alternating current signals 18A and 18B are applied to the conductive layer 121. [0039] The insulating film (insulator) 120 of the vibrating membrane 12 is a polymer material (poly ethylene terephthalate (PET), poly ester, poly ethylene naphthalate (PEN), aramid, poly phenylene) excellent in insulation resistance. -It is formed of sulfide (PPS) or the like. [0040] Reference numeral 17 denotes a part of the pair of fixed electrodes 10A and 10B, which has a function of sandwiching the vibrating film 12 and an opposing electrode portion (conductive film 20 which is a portion where electrostatic force acts between the vibrating film 13). It is a counter electrode forming body having a function of forming the exposed portion 21), and a stepped hole is formed by the through hole 14 of the fixed electrode 10A or 10B and the counter electrode forming body 19. A capacitor is formed in the counter electrode portion 21 and the conductive layer 121 of the fixed electrode 10A, and the counter electrode portion 21 and the electrode layer 121 of the fixed electrode 10B, respectively. [0041] Here, the non-conductor 10, which is the base material of the fixed electrodes 10A and 10B, is glass, glass epoxy, ceramics or the like, through holes 14 are provided in this, and an insulating material is used to make the counter electrode larger in diameter than the through holes. By forming the forming portion 17, it is possible to form the doughnut-shaped counter electrode portion 21 (FIG. 1 (B)). Further, it is also possible to form the doughnut-shaped counter electrode portion 21 by peeling the resist in a predetermined region from a printed circuit board (a singlesided board or a double-sided board) in which the through holes 14 are provided in advance. [0042] 04-05-2019 15 In the above-described configuration, the ultrasonic transducers 1 are mutually output from the signal source 18 to the conductive layer 121 of the vibrating membrane 12 by the DC bias power supply 16 to a DC bias voltage of a single polarity (positive in this embodiment). The phaseinverted alternating current signals 18A and 18B are applied in a superimposed state. On the other hand, alternating current signals 18A and 18B which are mutually phase-inverted from the signal source 18 are applied to the pair of fixed electrodes 10A and 10B. [0043] As a result, in the positive half cycle of the alternating current signal 18A output from the signal source 18, a positive voltage is applied to the fixed electrode 10A. Electrostatic repulsion acts and the surface portion is pulled downward in FIG. At this time, the alternating current signal 18B has a negative cycle, and a negative voltage is applied to the opposite fixed electrode 10B, so that an electrostatic attraction force acts on the back surface portion of the vibrating film 12, and the back surface The part is pulled further downward in FIG. [0044] Therefore, the film portion of the vibrating film 12 which is not held by the pair of fixed electrodes 10A and 10B simultaneously receives electrostatic repulsion and electrostatic repulsion in the same direction. Similarly, for the negative half cycle of the alternating current signal output from the signal source 18, the electrostatic attraction force is applied to the surface portion of the vibrating film 12 in FIG. The electrostatic repulsive force acts on the upper side and the upper side, and the film portion of the vibrating film 12 not sandwiched by the pair of fixed electrodes 10A and 10B receives the electrostatic repulsive force and the electrostatic attractive force simultaneously and in the same direction. In this manner, the direction in which the electrostatic force acts alternately changes while the diaphragm 12 simultaneously and in the same direction receives electrostatic repulsion and electrostatic attraction in accordance with the change in polarity of the AC signal, so that the large film Vibration, ie an acoustic signal at a sound pressure level sufficient to obtain a parametric array effect, can be generated. [0045] According to the electrostatic ultrasonic transducer according to the embodiment of the present invention, the base material of the first and second fixed electrodes is a non-conductive material, and the non-conductive surface serving as an opposing electrode portion facing the vibrating film Since the conductive film is formed and the step portion of the counter electrode portion is 04-05-2019 16 formed of an insulator, an electrostatic ultrasonic transducer is realized which secures the electrical safety without the conductive portion being exposed on the surface of the transducer. be able to. [0046] As described above, the ultrasonic transducer 1 according to the embodiment of the present invention is called a push-pull type because the vibrating membrane 12 vibrates by receiving a force from the pair of fixed electrodes 10A and 10B. The ultrasonic transducer 1 according to the embodiment of the present invention has a wide band and high sound pressure at the same time compared with the conventional ultrasonic transducer (Pull type) of which only the electrostatic attraction acts on the vibrating film. Have the ability to meet. [0047] The frequency characteristics of the ultrasonic transducer according to the embodiment of the present invention are shown in FIG. In the figure, the curve Q3 is the frequency characteristic of the inducer according to the present embodiment. As is clear from the figure, it can be seen that high sound pressure levels can be obtained over a wider frequency band as compared to the frequency characteristics of the conventional broadband electrostatic ultrasonic transducer. Specifically, it can be seen that a sound pressure level of 120 dB or more at which a parametric effect can be obtained in a frequency band of 20 kHz to 120 kHz can be obtained. [0048] In the electrostatic ultrasonic transducer 1 according to the embodiment of the present invention, the vibration film 12 of the thin film sandwiched between the pair of fixed electrodes 10A and 10B receives both the electrostatic attraction force and the electrostatic repulsion force. Not only generation but also symmetry of vibration is ensured, so high sound pressure can be generated over a wide band. [0049] 04-05-2019 17 Next, an example of the manufacturing process of the fixed electrode in the Push-Pull type electrostatic ultrasonic transducer according to the embodiment of the present invention will be described with reference to FIG. The fixed electrodes in conventional electrostatic ultrasonic transducers are manufactured by covering a metal plate, which is a conductive material, with a mask material to form through holes by etching, and laminating and bonding these by diffusion bonding or thermocompression bonding. . On the other hand, in the manufacturing process of the fixed electrode made of the non-conductive material in the electrostatic ultrasonic transducer according to the embodiment of the present invention, the glass plate 200 is used as the non-conductive material instead of the metal plate (FIG. 2 (a)) ). [0050] A sand blast method or an etching method is applied to this glass plate 200 to process through holes. The sandblasting method will be described as an example. A plurality of mask members 202 having through-hole patterns formed of a resist material for sandblasting are coated on a nonconductive glass plate 200, and a plurality of abrasives are applied to the glass plate 200 by air blasting or shot blasting. The through holes 204 are formed (first step: FIG. 2 (b)). After the through holes 204 are formed, the mask member 202 formed of a resist material for sandblasting is peeled off to obtain the base member of the fixed electrode composed of the nonconductive body 200 having the through holes 204 (second step) : FIG.2 (c). [0051] A metal (for example, aluminum, nickel, copper or the like) is vacuum deposited on one side of the base member to form a metal thin film 206 having a predetermined film thickness to be a counter electrode (third step: FIG. 2D). Thus, on the glass plate 200 in which the through holes 204 and the metal thin film 206 are formed, in the next step, a step (counter electrode forming body) constituting the counter electrode portion is formed. In this process, a resist material or coating material that can form a permanent structure and is nonconductive is used. Resist materials considered to be effective are photosensitive films for packaging and photosensitive polyimide films used for printed circuit boards. 04-05-2019 18 [0052] After laminating the resist film 208 and the metal thin film 206 having the through holes 204 on the surface of the glass plate 200, the resist film 208 is covered with the mask material 210 for forming the counter electrode portion and exposed. And by performing development, only a counter electrode surface is exposed and a nonelectroconductive layer is formed in the other part (the 4th, 5th processes: FIG.2 (e), (f)). The fixed electrode produced in this manner is electrically very safe without the voltage application part being exposed on the surface. [0053] Further, although the above description (content of FIG. 2) is the case where the photolithography method is applied to the resist film, a method of applying the screen printing method to the liquid resist is also effective. For example, a mask material used as a solder resist for packages generally used in printed circuit boards or a resist for sand blasting is simply applied by screen printing with a uniform thickness using a plate for forming a counter electrode portion. Is possible. [0054] Next, another example of the manufacturing process of the fixed electrode in the Push-Pull type electrostatic ultrasonic transducer according to the embodiment of the present invention will be described with reference to FIG. A manufacturing process of a non-conductive fixed electrode in the case of using the screen printing method will be described based on FIG. The process of producing the intermediate of the fixed electrode consisting of the non-conductive body (glass plate) 200 in which the through hole 204 and the metal thin film 206 are formed is exactly the same as the example shown in FIG. And the redundant description is omitted (first to third steps: FIGS. 3 (a) to 3 (d)). [0055] A through hole on a glass plate 200 as a nonconductive body in which a metal thin film 206 is formed and a mask member 208 which is a screen plate for masking a region near the through hole is formed on the surface of the glass plate 200 on which the metal thin film 206 is formed. 04-05-2019 19 And a counter electrode forming material 210 for forming an insulating counter electrode forming body which is a step portion of the counter electrode portion facing the vibrating film on the surface of the glass plate 200. Next, the squeegee 212 is moved to apply the counter electrode forming material 210 to a portion of the surface of the glass plate 200 on which the metal thin film 206 is formed, which is not masked by the mask member 208 (fourth step: FIG. 3E). . [0056] The counter electrode forming material considered to be effective can be permanently configured as a counter electrode forming body and is non-conductive, for example, as a liquid solder resist for a package generally used for a circuit board or a resist for sand blasting It is a masking ink etc. used. In particular, since the solder resist for flexible printed circuit boards is relatively soft (hardness of pencil is about HB), it has excellent adhesion strength to glass, various metals and resin materials, and sandwiching the vibrating film made of polymer film Very effective in sex. [0057] Subsequently, when the mask member (screen plate) 208 is removed after the application of the counter electrode forming material 210 is completed, the counter electrode forming body 214 which is a nonconductive layer remains in the other part except the counter electrode portion. Next, a desired fixed electrode is completed by drying the counter electrode forming body 214 formed on the glass plate 200 (fifth step: FIG. 3F). As mentioned above, in these manufacturing methods mentioned above, the amount of level ¦ step differences of the counter electrode formation body 214 which can be formed can be selected comparatively freely in the range of 5 micrometers-40 micrometers, and flatness is very good with 10% or less of thickness. [0058] When photolithography is applied to the resist film, there is a risk that the glass plate may be damaged when laminating the resist film, but since the screen printing method does not need to apply a large stress to the glass, the damage is caused. It is advantageous in that the risk of doing so can be extremely reduced. [0059] 04-05-2019 20 Moreover, when using glass epoxy or ceramics instead of a metal plate, a base member is produced using the shaping ¦ molding die for shape ¦ molding as a plate with a through-hole of a predetermined ¦ prescribed hole diameter, One side of this base member A metal (eg, aluminum, nickel, copper, etc.) is vacuum deposited to form a metal thin film to be a counter electrode. Thereafter, as described based on FIG. 3, the desired fixed electrode is finished using the screen printing method. [0060] Furthermore, the fixed material can be manufactured by peeling the resist material of a predetermined place with respect to the universal printed circuit board to which the copper foil and the resist process were given beforehand, and forming a counter electrode part. Still another example of the manufacturing process of the fixed electrode in the Push-Pull type electrostatic ultrasonic transducer according to the embodiment of the present invention will be described with reference to FIG. [0061] The manufacturing process of the fixed electrode using a printed circuit board is demonstrated based on FIG. In the figure, through holes 310 are provided in advance in a printed circuit board 30 using Bakelite or glass epoxy material as the non-conductor 300 as a predetermined diameter and pitch (preferably in a honeycomb arrangement). A conductive layer 301 is formed of copper foil on the entire surface of the printed board 30, and the entire surface of the conductive layer 301 is covered with a resist (synthetic resin film) 302 (FIG. 4 (a)) (FIG. The above is the configuration of a general printed circuit board). [0062] Here, the thickness of the conductive layer (copper foil) 301 is not particularly specified, and may be 35 μm or 70 μm which is generally used in a power supply system. On the other hand, the thickness of the resist (synthetic resin film) 302 is preferably about 5 to 10 μm which is effective as the thickness of the counter electrode portion and which can be realized by a screen 04-05-2019 21 printing method generally used as a resist processing method. A peeling resist 303 for peeling the resist 302 on the outer peripheral portion of the through hole is applied to one surface of the printed board 30 (first step: FIG. 4B). [0063] Next, the mask member 304 on which the pattern for masking the area other than the area facing the outer peripheral part of the through hole 310 on the peeling resist 303 of the printed substrate 30 on which the peeling resist 303 is applied is formed is the peeling resist 303 When the film is coated and exposed and developed, the peeling resist 303 remains in the area other than the area to be peeled. (Second step: FIG. 4 (b), (c)). Peel off the resist 302 in a portion not masked with the peeling resist 303 by the resist peeling treatment (third step: FIG. 4D) [0064] After completion of the third step, the remaining peeling resist 303 is removed. When the peeling resist is removed, the resist 302 which has not been peeled remains as the opposite electrode forming body 305, and the fixed electrode using the printed circuit board as a base is completed. (Fourth step: FIG. 4 (e)). The fixed electrode formed in this manner is electrically very sensitive because the resist (synthetic resin film) 302 is still formed on the entire back surface exposed to the outside (the surface not subjected to the resist peeling process). It's safe. As described above, according to the method of manufacturing the electrostatic ultrasonic transducer according to the embodiment of the present invention, the base material of the fixed electrode is formed of a non-conductive material, and the conductive processing is performed only on necessary portions. The site to which the high voltage is applied is not exposed to the surface, and an electrically very safe electrostatic ultrasonic transducer is obtained. [0065] Next, the configuration of the ultrasonic speaker according to the embodiment of the present invention is shown in FIG. The ultrasonic speaker according to the present embodiment uses the electrostatic ultrasonic transducer (FIG. 1) according to the above-described embodiment of the present invention as an ultrasonic transducer 55. 04-05-2019 22 [0066] In FIG. 5, the ultrasonic speaker according to the present embodiment includes an audio frequency wave oscillation source (signal source) 51 for generating a signal wave in the audio wave frequency band, and a carrier wave for generating and outputting a carrier wave in the ultrasonic frequency band. A wave oscillation source (carrier wave supply means) 52, a modulator (modulation means) 53, a power amplifier 54, and an ultrasonic transducer 55 are provided. The modulator 53 modulates the carrier wave output from the carrier wave oscillation source 52 with the signal wave in the audio wave frequency band output from the audio frequency wave oscillation source 51, and supplies it to the ultrasonic transducer 55 via the power amplifier 54. Do. [0067] In the above configuration, the carrier wave in the ultrasonic frequency band output from the carrier wave oscillation source 52 is modulated by the modulator 53 by the signal wave output from the audio frequency wave oscillation source 51, and the modulation signal amplified by the power amplifier 54 is used. The ultrasonic transducer 55 is driven. As a result, the modulated signal is converted to a sound wave of a finite amplitude level by the ultrasonic transducer 55, and this sound wave is emitted into the medium (in air) and the sound noise in the original audio frequency band by the nonlinear effect of the medium (air). Is self-regenerating. [0068] That is, since the sound wave is a compression wave propagating through the air as a medium, in the process of propagation of the modulated ultrasonic waves, the dense part and the sparse part of the air appear prominently. As the speed of sound is slowed, the modulation wave itself is distorted, so that the waveform is separated into the carrier wave (ultrasonic frequency band), and the signal wave (sound signal) in the audible wave frequency band is reproduced. [0069] As described above, when high sound pressure broadband is secured, it can be used as a speaker in various applications. 04-05-2019 23 Ultrasonic waves are highly attenuated in the air and decay in proportion to the square of their frequency. Therefore, when the carrier frequency (ultrasound) is low, it is possible to provide an ultrasonic speaker having a low attenuation and having a beam shape that allows sound to reach far. Conversely, if the carrier frequency is high, the attenuation is severe, so that the parametric array effect does not occur sufficiently, and it is possible to provide an ultrasonic speaker in which the sound spreads. These are very effective functions because the same ultrasonic speaker can be used according to the application. [0070] In addition, dogs that often live with humans as pets can listen to sounds up to 40 kHz and cats up to 100 kHz, so if you use a carrier frequency higher than that, there is no effect on pets. It also has an advantage. In any case, being available at various frequencies brings many benefits. [0071] The ultrasonic speaker according to the embodiment of the present invention can generate an acoustic signal with a sound pressure level high enough to obtain a parametric array effect over a wide frequency band. Further, since the ultrasonic speaker is configured using the electrostatic ultrasonic transducer having the above configuration, that is, the base material of the first and second fixed electrodes forming a pair is made to be a non-conductive material, and it is opposed to the diaphragm A conductive film is formed on the non-conductive surface which is to be the electrode portion, and the step portion of the counter electrode portion is formed of an insulator, so that the electrical safety without the conductive portion being exposed on the surface of the transducer It is possible to realize the secured ultrasonic speaker. [0072] The electrostatic ultrasonic transducer according to the embodiment of the present invention can be used for various sensors, for example, a distance measuring sensor, and as described above, a sound source for a directional speaker or an ideal impulse. It can be used as a signal source or the like. [0073] 04-05-2019 24 FIG. 1 shows a configuration of an electrostatic ultrasonic transducer according to an embodiment of the present invention. FIG. 7 is a process chart showing an example of a manufacturing process of a fixed electrode in a Push-Pull type electrostatic ultrasonic transducer according to an embodiment of the present invention. FIG. 8 is a process chart showing another example of the manufacturing process of the fixed electrode in the Push-Pull type electrostatic ultrasonic transducer according to the embodiment of the present invention. FIG. 8 is a process chart showing still another example of the manufacturing process of the fixed electrode in the Push-Pull type electrostatic ultrasonic transducer according to the embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of an ultrasonic speaker according to an embodiment of the present invention. The figure which shows the structure of the conventional resonance type ultrasonic transducer. FIG. 8 is a diagram showing a specific configuration of a conventional electrostatic broadband ultrasonic transducer. The figure which showed the frequency characteristic of the electrostatic ultrasonic transducer which concerns on embodiment of this invention with the frequency characteristic of the conventional ultrasonic transducer. The figure which shows the structure of a Push-Pull type electrostatic-type ultrasonic transducer. Explanation of sign [0074] DESCRIPTION OF SYMBOLS 1 ... electrostatic-type ultrasonic transducer, 10A, 10B ... fixed electrode, 12 ... vibrating membrane, 14 ... through hole, 16 ... DC bias power supply, 17 ... counter electrode formation body (step part) 18 ... signal source, 51 ... audio Frequency wave oscillation source 52 Carrier wave oscillation source 53 Modulator 54 Power amplifier 55 Ultrasonic transducer 120 Insulating film 121 Conducting layer. 04-05-2019 25
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