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 JP2009118093 In a pull-type electrostatic transducer, electrostatic force can be efficiently transmitted to a vibrating membrane to increase the amplitude of the vibrating membrane, and sound pressure can be further increased by using a resonance tube. , Provide an electrostatic transducer. A vibrating membrane having a vibrating electrode layer is disposed on one side of the vibrating membrane, and a voltage applied between the vibrating membrane and the vibrating membrane is applied to one side of the vibrating membrane. And an electrode for applying an electrostatic attraction force, wherein the electrode is configured such that the electrostatic attraction force acts on a central portion of the vibrating portion of the vibrating membrane, and a sound wave generated from the vibrating membrane And a resonant tube structure that acts as a resonant tube. [Selected figure] Figure 1 Electrostatic transducer and ultrasonic speaker [0001] The present invention relates to an electrostatic transducer and an ultrasonic speaker capable of increasing the sound pressure of a sound wave to be output by efficiently transmitting electrostatic force to a vibrating film to increase the amplitude of vibration. [0002] As an electrostatic transducer used for an ultrasonic speaker etc., there is an electrostatic transducer called a pull type. 04-05-2019 1 In addition, the electrostatic transducer which radiates ¦ emits the sound wave of ultrasonic frequency is also called an electrostatic ultrasonic transducer. [0003] FIG. 18 is a view showing a configuration example of a conventional pull-type electrostatic ultrasonic transducer (see, for example, Patent Document 1). The electrostatic ultrasonic transducer 101 shown in FIG. 18 includes an upper electrode 110 including a vibrating film 102 formed of an insulator and a conductive film 103 formed on the vibrating film 102, and a vibrating film 102 of the upper electrode 110. The lower electrode 120 is provided with a plurality of concavities and convexities on the surface opposite to the DC bias power supply 130, and an AC signal source 131. [0004] A constant DC bias voltage is always applied between the upper electrode 110 and the lower electrode 120 by the DC bias power supply 130 capable of voltage adjustment, and the convex portion A of the lower electrode 120 is generated by the electrostatic force generated by this electric field. The upper electrode 110 is adsorbed on the upper electrode 110, and except for the cavity B formed between the upper electrode 110 and the lower electrode 120, the upper electrode 110 is in close contact. In this state, an alternating current signal is superimposed on the DC bias voltage and applied between the upper electrode 110 and the lower electrode 120, thereby facing the electrode portion of the upper electrode 110 and the lower electrode 120 (the vibrating portion of the diaphragm 102). An electrostatic force acts on the surface 121, and the vibrating membrane 102 is driven by an alternating current signal and vibrates by the electrostatic attraction force and the elastic restoring force. [0005] As described above, the electrostatic ultrasonic transducer 101 shown in FIG. 18 is called a pull type electrostatic ultrasonic transducer because the vibrating membrane 102 receives an electrostatic attraction force from one direction. The advantage of this pull-type electrostatic ultrasonic transducer is that the aperture area is large and the sound pressure can be easily obtained. 04-05-2019 2 [0006] In the above-described electrostatic ultrasonic transducer 101, it is generally necessary to increase the amplitude of the vibrating film 102 in order to increase the sound pressure. However, in the conventional pull-type electrostatic ultrasonic transducer, as shown in FIG. 19A, the electrostatic force acting between the lower electrode 120 and the vibrating membrane 102 is the end of the vibrating portion of the vibrating membrane 102. The electrostatic force is generated only in the unit. Therefore, compared to the configuration in which the electrostatic force is generated at the central portion of the vibrating portion of the vibrating film 102 as shown in FIG. 19B, the vibrating film 102 is efficiently vibrated and thus no force is applied. It was For this reason, there is a problem that the electrostatic force can not be efficiently transmitted to the vibrating film 102 to increase the amplitude. [0007] FIG. 20 is a view showing another configuration example of a pull-type electrostatic ultrasonic transducer (see, for example, Patent Document 2). In the pull-type electrostatic ultrasonic transducer 201 shown in FIG. 20, the upper electrode 210 composed of the vibrating film 202 formed of an insulator and the conductive film 203 formed on the vibrating film, and the vibrating film 202 The lower electrode 220 has a plurality of concavities and convexities formed on the opposite surface, the upper electrode and the lower electrode are in close contact with each other, and an alternating current signal is applied between the upper electrode and the lower electrode. There is. In addition, a resonance pipe unit 240 having a plurality of vent holes 242 forming a both-end opening pipe resonating at a desired frequency on the plate member 241 is fixed on the surface of the upper electrode 210. [0008] In this electrostatic ultrasonic transducer 201, the resonance pipe unit 240 is used to increase the sound pressure. However, since the lower electrode 220 is merely uneven, even if the vibrating film 202 vibrates. By the fact that the air does not escape from the lower electrode 220 side, the air resistance when the vibrating membrane 202 vibrates becomes large. Conversely, when the unevenness is simply a through hole, the electrostatic force generated between the lower electrode and the upper electrode is only at the end of the through hole, and like the 04-05-2019 3 electrostatic ultrasonic transducer 101 shown in FIG. Electrostatic force can not be efficiently applied to the central portion of the membrane. Therefore, sufficient sound pressure could not be obtained. JP, 2005-117103, A JP, 2005-223820, A [0009] In an electrostatic transducer, it is generally necessary to increase the amplitude of the vibrating film in order to increase the sound pressure. However, in the conventional pull-type electrostatic transducer, the electrostatic force can not be efficiently applied to the central portion of the vibrating portion of the vibrating membrane, and a force is applied to efficiently vibrate the vibrating membrane. There was no configuration. For this reason, there has been a problem that the electrostatic force can not be efficiently transmitted to the vibrating membrane to increase the amplitude of the vibrating membrane. [0010] The present invention has been made to solve such a problem, and an object thereof is to effectively transmit an electrostatic force to a vibrating membrane to increase the amplitude of the vibrating membrane in a pull-type electrostatic transducer. It is an object of the present invention to provide an electrostatic transducer and an ultrasonic speaker which can further increase sound pressure by using a resonance tube. [0011] The present invention has been made to solve the above problems, and the electrostatic transducer according to the present invention has a vibrating membrane having a vibrating electrode layer, a plurality of through holes, and a space between the vibrating membrane and the vibrating membrane. An electrode that exerts an electrostatic attraction force on one surface side of the vibrating film by an applied voltage, and a vibrating unit disposed between the electrode and the vibrating film to divide the vibrating film into a plurality of vibrating portions A dividing member, wherein the electrode is configured to exert an electrostatic attraction force on a central portion of a vibrating portion of the vibrating membrane, and as a resonance tube for sound waves generated from the vibrating membrane Characterized in that it comprises a working resonance tube structure. In the electrostatic transducer according to the present invention having the above configuration, 04-05-2019 4 the vibration film having the vibration electrode layer is disposed on one side of the vibration film, and the vibration is generated by a voltage applied between the vibration film and the vibration film. And an electrode for applying an electrostatic attraction force to one surface side of the membrane, wherein the electrode is configured such that the electrostatic attraction force acts on a central portion of the vibrating portion of the vibrating membrane. It has a resonance tube structure which acts as a resonance tube with respect to the sound wave generated from the said vibrating film, It is characterized by the above-mentioned. As a result, the electrostatic force is generated at the central portion of the vibrating portion of the vibrating membrane, and a force for efficiently vibrating the vibrating membrane can be applied. Moreover, the sound pressure of the radiated sound wave can be increased by the resonance tube action. Therefore, it is possible to realize an electrostatic transducer that can obtain high efficiency and high sound pressure. [0012] Further, in the electrostatic transducer according to the present invention, a DC bias power supply is applied to the vibrating electrode layer, and a carrier wave of an ultrasonic frequency band is modulated with a signal wave of an audible frequency band between the vibrating electrode layer and the electrode portion. And the electrostatic transducer is an electrostatic ultrasonic transducer that emits ultrasonic waves. In the electrostatic transducer of the present invention configured as described above, the electrostatic transducer according to the present invention is used as an electrostatic ultrasonic transducer, and a modulated wave in which a carrier wave in the ultrasonic frequency band is modulated by a signal wave in the audio frequency band Thus, in the electrostatic ultrasonic transducer, the vibrating membrane can be efficiently vibrated, and the sound pressure of the radiated sound wave can be increased by the resonance tube action. [0013] In the electrostatic transducer according to the present invention, an electrostatic force is generated by a voltage applied between a vibrating membrane having a vibrating electrode layer, a plurality of through holes and the vibrating membrane adjacent to the through holes. And a vibrating portion dividing member disposed between the electrode and the vibrating membrane to divide the vibrating membrane into a plurality of vibrating portions, and in the plurality of vibrating portions, the vibrating portion The electrode portion is located at a position opposite to the central portion, and has a plurality of through holes on the surface of the vibrating film opposite to the electrode side to act as a resonance tube for sound waves generated from the 04-05-2019 5 vibrating portion And a resonant tube member is disposed. In the electrostatic transducer of the present invention configured as described above, the vibrating membrane and the electrode are disposed so as to sandwich the vibrating portion dividing member (for example, the epoxy resin layer). Then, when the vibrating membrane is attracted to the electrode by electrostatic force, there is an electrode portion that generates an electrostatic force with respect to the central portion of the vibrating portion of the vibrating membrane. In addition, on the side opposite to the electrode side of the vibrating membrane, a resonance tube member having a through hole that acts as a resonance tube for the sound wave generated from the vibrating portion of the vibrating membrane is disposed. As a result, an electrostatic force is generated at the central portion of the vibrating portion in which the vibrating membrane vibrates, and a force for efficiently vibrating the vibrating membrane can be applied. Moreover, the sound pressure of the radiated sound wave can be increased by the resonance tube action. Therefore, it is possible to realize an electrostatic transducer that can obtain high efficiency and high sound pressure. [0014] Further, in the electrostatic transducer according to the present invention, a DC bias power supply is applied to the vibrating electrode layer, and a carrier wave of an ultrasonic frequency band is modulated with a signal wave of an audible frequency band between the vibrating electrode layer and the electrode portion. And the electrostatic transducer is an electrostatic ultrasonic transducer that emits ultrasonic waves. In the electrostatic transducer of the present invention configured as described above, the electrostatic transducer according to the present invention is used as an electrostatic ultrasonic transducer, and a modulated wave in which a carrier wave in the ultrasonic frequency band is modulated by a signal wave in the audio frequency band Thus, in the electrostatic ultrasonic transducer, the vibrating membrane can be efficiently vibrated, and the sound pressure of the radiated sound wave can be increased by the resonance tube action. [0015] In the electrostatic transducer according to the present invention, an electrostatic force is generated by a voltage applied between a vibrating membrane having a vibrating electrode layer, a plurality of through holes and the vibrating membrane adjacent to the through holes. And a vibrating portion dividing member disposed between the electrode and the vibrating membrane to divide the vibrating membrane into a plurality of vibrating portions, and in the plurality of vibrating portions, the vibrating portion The electrode portion is located at a position facing the central portion, and resonance is generated for the sound wave generated from the vibrating 04-05-2019 6 portion on the surface of the electrode opposite to the vibrating membrane side and passing through the through hole of the electrode. It is characterized in that a resonance pipe member having a plurality of through holes acting as a pipe is disposed. In the electrostatic transducer of the present invention configured as described above, the vibrating membrane and the electrode are disposed so as to sandwich the vibrating portion dividing member (for example, the epoxy resin layer). Then, when the vibrating membrane is attracted to the electrode by electrostatic force, there is an electrode portion that generates an electrostatic force with respect to the central portion of the vibrating portion of the vibrating membrane. Further, on the side opposite to the vibrating membrane side of the electrode, a resonance tube member having a through hole acting as a resonance tube for the sound wave generated from the vibrating portion of the vibrating membrane is disposed. As a result, an electrostatic force is generated at the central portion of the vibrating portion in which the vibrating membrane vibrates, and a force for efficiently vibrating the vibrating membrane can be applied. Moreover, the sound pressure of the radiated sound wave can be increased by the resonance tube action. Therefore, it is possible to realize an electrostatic transducer that can obtain high efficiency and high sound pressure. [0016] Further, in the electrostatic transducer according to the present invention, a DC bias power supply is applied to the vibrating electrode layer, and a carrier wave of an ultrasonic frequency band is modulated with a signal wave of an audible frequency band between the vibrating electrode layer and the electrode portion. And the electrostatic transducer is an electrostatic ultrasonic transducer that emits ultrasonic waves. In the electrostatic transducer of the present invention configured as described above, the electrostatic transducer according to the present invention is used as an electrostatic ultrasonic transducer, and a modulated wave in which a carrier wave in the ultrasonic frequency band is modulated by a signal wave in the audio frequency band Thus, in the electrostatic ultrasonic transducer, the vibrating membrane can be efficiently vibrated, and the sound pressure of the radiated sound wave can be increased by the resonance tube action. [0017] In the electrostatic transducer according to the present invention, an electrostatic force is generated by a voltage applied between a vibrating membrane having a vibrating electrode layer, a plurality of through holes and the vibrating membrane adjacent to the through holes. And a vibrating portion dividing member disposed between the electrode and the vibrating membrane to divide the vibrating membrane into a plurality of vibrating portions, and in the plurality of 04-05-2019 7 vibrating portions, the vibrating portion The electrode portion is located at a position facing the central portion, and the through hole portion of the electrode is configured to act as a resonance tube. In the electrostatic transducer of the present invention configured as described above, the vibrating membrane and the electrode are disposed so as to sandwich the vibrating portion dividing member (for example, the epoxy resin layer). Then, when the vibrating membrane is attracted to the electrode by electrostatic force, there is an electrode portion that generates electrostatic force with respect to the central portion of the vibrating portion of the vibrating membrane. In addition, the through hole portion of the electrode acts as a resonance tube. As a result, an electrostatic force is generated at the central portion of the vibrating portion in which the vibrating membrane vibrates, and a force for efficiently vibrating the vibrating membrane can be applied. Further, the sound pressure of the radiated sound wave can be increased by the resonance tube action by the through hole of the electrode. Therefore, it is possible to realize an electrostatic transducer that can obtain high efficiency and high sound pressure. [0018] Further, in the electrostatic transducer according to the present invention, a DC bias power supply is applied to the vibrating electrode layer, and a carrier wave of an ultrasonic frequency band is modulated with a signal wave of an audible frequency band between the vibrating electrode layer and the electrode portion. And the electrostatic transducer is an electrostatic ultrasonic transducer that emits ultrasonic waves. In the electrostatic transducer of the present invention configured as described above, the electrostatic transducer according to the present invention is used as an electrostatic ultrasonic transducer, and a modulated wave in which a carrier wave in the ultrasonic frequency band is modulated by a signal wave in the audio frequency band Thus, in the electrostatic ultrasonic transducer, the vibrating membrane can be efficiently vibrated, and the sound pressure of the radiated sound wave can be increased by the resonance tube action. [0019] In the electrostatic transducer according to the present invention, an electrostatic force is generated by a voltage applied between a vibrating membrane having a vibrating electrode layer, a plurality of through holes and the vibrating membrane adjacent to the through holes. And a vibrating portion dividing member disposed between the electrode and the vibrating membrane to divide the vibrating membrane into a plurality of vibrating portions, and in the plurality of vibrating portions, the vibrating portion The electrode portion is located at a position opposite to the central portion, and has a plurality of through holes on the surface of the vibrating film 04-05-2019 8 opposite to the electrode side to act as a resonance tube for sound waves generated from the vibrating portion A first resonance pipe member is disposed, and further, as a resonance pipe for a sound wave generated from the vibrating portion on the surface of the electrode opposite to the vibrating membrane side and passing through the through hole of the electrode A plurality of acting through holes Resonance tube member is arranged in that, characterized by. In the electrostatic transducer of the present invention configured as described above, the vibrating membrane and the electrode are disposed so as to sandwich the vibrating portion dividing member (for example, the epoxy resin layer). Then, when the vibrating membrane is attracted to the electrode by electrostatic force, there is an electrode portion that generates electrostatic force with respect to the central portion of the vibrating portion of the vibrating membrane. In addition, the first resonance tube member having a through hole that acts as a resonance tube for the sound wave generated from the vibrating portion of the vibrating membrane is disposed on the opposite surface side to the electrode side of the vibrating membrane. Furthermore, a second resonance tube member having a through hole acting as a resonance tube for the sound wave generated from the vibrating portion of the vibrating membrane is disposed on the side opposite to the vibrating membrane side of the electrode. As a result, an electrostatic force is generated at the central portion of the vibrating portion in which the vibrating membrane vibrates, and a force for efficiently vibrating the vibrating membrane can be applied. Also, due to the resonance tube action, the sound pressure of the sound waves output from both sides of the electrostatic transducer is increased. Therefore, it is possible to realize an electrostatic transducer that can obtain high efficiency and high sound pressure. [0020] Further, in the electrostatic transducer according to the present invention, a DC bias power supply is applied to the vibrating electrode layer, and a carrier wave of an ultrasonic frequency band is modulated with a signal wave of an audible frequency band between the vibrating electrode layer and the electrode portion. And the electrostatic transducer is an electrostatic ultrasonic transducer that emits ultrasonic waves. In the electrostatic transducer of the present invention configured as described above, the electrostatic transducer according to the present invention is used as an electrostatic ultrasonic transducer, and a modulated wave in which a carrier wave in the ultrasonic frequency band is modulated by a signal wave in the audio frequency band Thus, in the electrostatic ultrasonic transducer, the vibrating membrane can be efficiently vibrated, and the sound pressure of the radiated sound wave can be increased by the resonance tube action. [0021] 04-05-2019 9 In the electrostatic transducer according to the present invention, an electrostatic force is generated by a voltage applied between a vibrating membrane having a vibrating electrode layer, a plurality of through holes and the vibrating membrane adjacent to the through holes. And a vibrating portion dividing member disposed between the electrode and the vibrating membrane to divide the vibrating membrane into a plurality of vibrating portions, and in the plurality of vibrating portions, the vibrating portion The electrode portion is located at a position opposite to the central portion, and has a plurality of through holes on the surface of the vibrating film opposite to the electrode side to act as a resonance tube for sound waves generated from the vibrating portion A resonance pipe member is disposed, and the through hole portion of the electrode is configured to act as a resonance pipe. In the electrostatic transducer of the present invention configured as described above, the vibrating membrane and the electrode are disposed so as to sandwich the vibrating portion dividing member (for example, the epoxy resin layer). Then, when the vibrating membrane is attracted to the electrode by electrostatic force, there is an electrode portion that generates electrostatic force with respect to the central portion of the vibrating portion of the vibrating membrane. Further, on the side opposite to the electrode side of the vibrating membrane, a resonance tube member having a plurality of through holes acting as a resonance tube for the sound wave generated from the vibrating portion of the vibrating membrane is disposed. Furthermore, the through hole of the electrode acts as a resonance tube. As a result, an electrostatic force is generated at the central portion of the vibrating portion in which the vibrating membrane vibrates, and a force for efficiently vibrating the vibrating membrane can be applied. Also, due to the resonance tube action, the sound pressure of the sound waves output from both sides of the electrostatic transducer is increased. Therefore, it is possible to realize an electrostatic transducer that can obtain high efficiency and high sound pressure. [0022] Further, in the electrostatic transducer according to the present invention, a DC bias power supply is applied to the vibrating electrode layer, and a carrier wave of an ultrasonic frequency band is modulated with a signal wave of an audible frequency band between the vibrating electrode layer and the electrode portion. And the electrostatic transducer is an electrostatic ultrasonic transducer that emits ultrasonic waves. In the electrostatic transducer of the present invention configured as described above, the electrostatic transducer according to the present invention is used as an electrostatic ultrasonic transducer, and a modulated wave in which a carrier wave in the ultrasonic frequency band is modulated by a signal wave in the audio frequency band Thus, in the electrostatic ultrasonic transducer, the vibrating membrane can be efficiently vibrated, and the sound pressure of the radiated sound wave can be increased by the resonance tube action. 04-05-2019 10 [0023] Further, in the ultrasonic speaker according to the present invention, a carrier wave of an ultrasonic frequency band is modulated by a signal wave output from a signal source generating an audio frequency band signal wave, and an electrostatic transducer is driven by the modulated wave. An ultrasonic speaker that reproduces signal sound in an audible frequency band, wherein the electrostatic transducer has a vibrating membrane having a vibrating electrode layer, a plurality of through holes, and is applied between the vibrating membrane An electrode that exerts an electrostatic attractive force on one surface side of the vibrating membrane by the voltage applied, and a vibrating portion division which is disposed between the electrode and the vibrating membrane and divides the vibrating membrane into a plurality of vibrating portions A member, and the electrode is configured such that an electrostatic attraction force acts on a central portion of a vibrating portion of the vibrating membrane, and a resonance tube for sound waves generated from the vibrating membrane age Providing the resonance tube structure which acts, characterized by. In the ultrasonic speaker according to the present invention having the above configuration, the carrier wave (carrier wave) of the ultrasonic frequency band is modulated by the signal wave of the audio frequency band, and the ultrasonic speaker drives the electrostatic transducer by the modulated wave. While using a pull-type electrostatic transducer that applies an electrostatic force from one surface side to the film, an electrode structure that electrostatically attracts the central portion of the vibrating portion of the vibrating film, and a sound wave generated from the vibrating film An electrostatic transducer is used which comprises a resonant tube structure which acts as a resonant tube. Thereby, in the ultrasonic speaker, high sound pressure can be obtained with high efficiency. Therefore, it is possible to realize an ultrasonic speaker capable of generating an acoustic signal with a sound pressure level high enough to obtain a parametric array effect. [0024] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. [0025] [Explanation of Basic Concept of Electrostatic Transducer of the Present Invention] FIG. 1 is a view for explaining the basic concept of the electrostatic transducer of the present invention. [0026] 04-05-2019 11 FIG. 1A shows a state of application of electrostatic force to the vibrating film 31 in a conventional pull-type electrostatic transducer. As shown in FIG. 1A, in the conventional pull-type electrostatic transducer, the electrostatic force f is applied only to the end of the vibrating membrane 31, and the vibrating membrane 31 is vibrated with high efficiency. It was difficult. [0027] On the other hand, FIG. 1B shows a state of application of electrostatic force to the vibrating film 31 in the pull-type electrostatic transducer of the present invention. As shown in FIG. 1B, in the electrostatic transducer according to the present invention, the electrode portion 14 of the electrode 11 is disposed at the central portion of the diaphragm 31, and the electrostatic force f is applied to the central portion of the diaphragm 31. Is configured as. As a result, the electrostatic force is efficiently transmitted to the vibrating film 31, the amplitude of the vibrating film 31 is increased, and the sound pressure is improved. [0028] Further, the through hole 22 of the resonance tube member 21 is disposed to the vibrating membrane 31, and the through hole 22 acts as a resonance tube, and the sound pressure of the sound wave (for example, ultrasonic wave) emitted from the vibrating membrane 31 It is configured to be increased further. [0029] First Embodiment FIG. 2 is a view showing a configuration of an electrode of an electrostatic transducer according to a first embodiment of the present invention. In addition, FIG. 2 shows a part of electrode for description. 04-05-2019 12 [0030] As shown in FIG. 2A, in the electrostatic transducer according to the present invention, a plurality of through holes are provided in a conductive material of a thin plate metal (for example, aluminum alloy, stainless steel, etc.) as the electrode 11. In the example shown in FIG. 2, four through holes 12a, 12b, 12c and 12d are arranged on concentric circles R (circle R of center X shown in FIG. 2C). In addition, when naming four through-holes 12a, 12b, 12c, 12d generically, it calls "the through-hole part 12" (the same also in drawing). [0031] A plurality of through holes 12 are arranged on the electrode 11 (for example, arranged in a honeycomb shape). Then, as shown in FIG. 2 (B), an epoxy insulating layer is applied on one surface side of the electrode 11 (the side facing the vibrating film 31). In this case, the epoxy insulating layer is applied so as to provide a circular electrode portion (exposed surface not covered with the epoxy insulating layer) 14 including the four through holes 12a, 12b, 12c and 12d. For example, an epoxy insulating layer is pattern-printed on the surface of the electrode 11 (the side facing the vibrating film 31) in the same manner as resist printing on a printed circuit board. This becomes the vibrating portion dividing member 13, which is disposed between the electrode 11 and the vibrating membrane 31 and serves to divide the vibrating membrane 31 into a plurality of vibrating portions (vibrating portions). [0032] Therefore, as shown in FIG. 2C, on one surface of the electrode 11, four through holes 12a, 12b, 12c, 12d, an electrode portion 14 including these through holes, and a vibrating portion division, A member 13 (epoxy insulating layer) 13 is formed. As described above, in the electrode 11, the electrode surface (electrostatic force generating surface) for generating electrostatic force is located at the central portion of the electrode portion 14, and the through hole 12 is provided in the periphery thereof. [0033] 04-05-2019 13 FIG. 3 is a view showing the configuration of a resonance tube 21 of the electrostatic transducer according to the first embodiment of the present invention. In addition, FIG. 2 shows a part of resonance pipe member 21 for description. [0034] As shown in FIG. 3, the through holes 22 a, 22 b, and 22 c are formed as a resonance pipe in a resin (for example, acrylic, super engineering plastic, etc.) as the resonance pipe member 21. For example, it can be produced by drilling or injection molding of a resin. The diameter of each through hole to be the resonance tube is sized to include the four through holes 12 on the electrode portion 14 shown in FIG. [0035] FIG. 3B is a view showing the configuration of the vibrating film 31. As shown in FIG. The vibrating film 31 is formed by sandwiching the vibrating electrode layer 31A, which is a conductive layer, with the dielectric film (insulating layer) 31B. The vibrating electrode layer 31A is formed of, for example, an aluminum thin film by sputter deposition. [0036] FIG. 4 is a view for explaining the configuration of the electrostatic transducer according to the first embodiment of the present invention. [0037] As shown in FIG. 4, in the electrostatic transducer according to the present invention, the resonance tube 21 is moved in the direction of arrow A, the electrode 11 is moved in the direction of arrow B, and the electrode 11 and the resonance tube 21 sandwich the diaphragm 31. In the same way. In this case, the vibrating membrane 31 is held so that the position of the circular electrode portion 14 including the through hole 12 of the electrode 11 and the position of the through hole 22 of the resonance pipe member 21 coincide with each other. Therefore, the centers of the 04-05-2019 14 four through holes of the electrode 11 (see the center X of FIG. 2C) and the center of the through hole 22 of the resonance pipe member 21 coincide or substantially coincide with each other with the diaphragm 31 interposed therebetween. It will be. [0038] FIG. 5 is a view showing the cross-sectional shape of the electrostatic transducer according to the first embodiment of the present invention, and is a cross-sectional view passing through the center of the circular portion of the epoxy insulating layer (in FIG. 2 (B) Sectional view in the XX ′ direction). [0039] As shown in FIG. 5A, in the electrostatic transducer 1, the vibrating film 31 and the electrode 11 are disposed so as to sandwich the vibrating portion dividing member 13 (epoxy resin layer) 13. At this time, the circular portion (refer to FIG. 2B) of the vibration portion dividing member 13 and the through hole (resonance pipe) 22 of the resonance pipe member 21 are disposed to face each other. Thus, a cavity a is provided between the electrode 11 and the vibrating membrane 31. The portion of the vibrating film 31 facing the hollow portion a (the portion not pressed by the vibrating portion dividing member 13) is the vibrating portion of the vibrating film 31. [0040] The vibrating film 31 is formed by sandwiching the vibrating electrode layer 31A, which is a conductive layer, with the insulating dielectric film 31B. With such a configuration, the vibrating membrane 31 and the electrode portion 14 of the electrode 11 face each other via the hollow portion a, and between the vibrating electrode layer 31A of the vibrating membrane 31 and the electrode portion 14 of the electrode 11 Electrostatic force acts. [0041] FIG. 5 (B) is a figure for demonstrating the application method of the voltage in the electrostatic transducer of this invention. As shown in FIG. 5B, a DC bias voltage is applied to the vibrating 04-05-2019 15 electrode layer 31A of the vibrating film 31 by the DC bias power supply 32. An AC signal (AC drive voltage) from an AC signal source 33 is applied between the vibrating electrode layer 31A of the diaphragm 31 and the electrode 11 in a superimposed manner on the DC bias voltage. However, the method of applying the voltage is not limited to this, and an alternation can be made, such as applying an alternating current signal (AC drive voltage) to the vibrating film 31 and applying a direct current bias voltage to the electrode 11. [0042] The alternating current signal output from the alternating current signal source 33 may be a signal in the audible frequency band, and is a signal of a modulated wave obtained by modulating the carrier wave in the ultrasonic frequency band with a signal wave in the audible frequency band It is also good. When the signal applied to the electrostatic transducer 1 is a signal in the ultrasonic frequency band, the electrostatic transducer 1 emits an acoustic wave in the ultrasonic frequency band, and is also called an electrostatic ultrasonic transducer. [0043] FIG. 6 is a diagram for explaining the vibration state of the vibrating membrane 31 of the electrostatic transducer. By the voltage application method shown in FIG. 5B, as shown in FIG. 6A, the vibrating film 31 is attracted toward the electrode 11 by electrostatic force. Then, the electrostatic force changes (strong or weak) due to the change of the voltage of the AC signal, and the vibrating membrane 31 vibrates due to the balance between the elastic restoring force of the vibrating membrane 31 and the electrostatic force. [0044] At this time, since the vibrating film 31 is attracted to the electrode 11 side, the vibrating film 31 sticks to the vibrating portion dividing member 13. Therefore, since the vibrating membrane 31 hardly vibrates in this portion, the vibrating membrane 31 is divided into a plurality of vibrating portions (vibrating portions). Specifically, the vibrating portion (vibrating portion) of the vibrating film 31 has the same shape as the circular portion (see FIG. 2B) of the vibrating portion dividing member (epoxy insulating layer) 13. Therefore, the electrode portion 14 is positioned at a position facing the central portion of the vibrating portion (vibration portion). Therefore, it is possible to apply a force for vibrating the vibrating membrane 31 more efficiently than exerting 04-05-2019 16 an electrostatic force at the end of the vibrating section as in the conventional pull-type electrostatic transducer. Therefore, the amplitude also increases, and the sound pressure can be increased. [0045] Further, sound waves generated by the vibration of the vibrating film 31 pass through the through holes 22 of the resonance tube member 21. At this time, the through hole 22 acts as a resonance tube. That is, when it is desired to generate an acoustic wave mainly at 50 kHz (ultrasonic wave), the wavelength of the sound is determined as the velocity of the sound about 340 m / sec. Therefore, for example, when the thickness of the resonance tube member 21, that is, the length of the through hole 22 is about 1/4 (about 1.5 mm) of the wavelength, the through hole 22 acts as a resonance tube, and the sound pressure is reduced. Increase. The length of the through hole is not limited to about 1⁄4 of the wavelength, and when the wavelength length is λ as the resonance condition, (on / 4) · n, where n is a positive odd number It is also good. Also, the reason for setting the wavelength to be about 1/4 is because the length is slightly changed from 1⁄4 of the wavelength due to the open end correction of the resonance tube. In addition, the conditions of resonance are disclosed by Unexamined-Japanese-Patent No. 200768148 grade ¦ etc.,. [0046] In addition to forming the electrode portion 14, the through hole 12 of the electrode 11 has an effect of reducing the air resistance of the vibrating film 31 when air is released from the through hole 12. [0047] According to the above configuration, as shown in FIG. 6B, the sound wave emitted from the vibrating membrane 31 passes through the through hole (resonance tube) 22 and is emitted to the front surface of the electrostatic transducer. [0048] As described above, in the configuration of the electrostatic transducer according to the present invention, when the vibrating membrane 31 is attracted to the electrode 11, there is an electrode portion that generates an electrostatic force corresponding to the central portion of the vibrating 04-05-2019 17 portion of the vibrating membrane 31. For this reason, a force can be applied to the vibrating membrane 31 to vibrate efficiently as compared with the conventional configuration. Further, by forming the resonance pipe by the through hole 22 of the resonance pipe member 21, the sound pressure can be further increased. Therefore, the electrostatic force can be efficiently transmitted to the vibrating film 31 to increase the amplitude of the vibrating film 31, and an electrostatic transducer with high efficiency and high sound pressure output can be realized. [0049] Second Embodiment In the first embodiment, an example of the electrostatic transducer constituted by sandwiching the vibrating film 31 between the resonance tube member 21 and the electrode 11 has been described. In the second embodiment, an example in which the resonance pipe member 21 is disposed on the side of the electrode 11 will be described. [0050] FIG. 7 is a view showing the configuration of the electrostatic transducer according to the second embodiment of the present invention, and is a cross-sectional view passing through the center of the circular portion of the epoxy insulating layer (X in FIG. 2 (B) Cross section in the -X 'direction). The electrode 11 is the same as that shown in FIG. 2, and the resonance pipe member 21 is the same as that shown in FIG. 3, and the description thereof will be omitted. [0051] In the electrostatic transducer 1A shown in FIG. 7, the vibrating membrane 31 and the electrode 11 are disposed so as to sandwich the vibrating portion dividing member (epoxy resin layer) 13 therebetween. [0052] 04-05-2019 18 Then, the resonance pipe member 21 is disposed on the surface of the electrode 11 opposite to the vibrating membrane 31 side. At this time, the circular part (circular part where the epoxy insulating layer is not applied) of the vibration part dividing member 13 and the through hole (resonance pipe) 22 of the resonance pipe member 21 correspond to each other with the electrode 11 interposed therebetween. Placed in position. [0053] FIG. 7B is a view showing a method of applying a voltage to the electrostatic transducer according to the second embodiment of the present invention. As shown in FIG. 7B, a DC bias voltage is applied to the vibrating film 31 by the DC bias power supply 32, and an AC signal (AC drive voltage) is applied to the electrode 11 by the AC signal source 33. However, the method of applying the voltage is not limited to this, and an alternation can be made, such as applying an alternating current signal (AC drive voltage) to the vibrating film 31 and applying a direct current bias to the electrode 11. [0054] The alternating current signal output from the alternating current signal source 33 may be a signal in the audible frequency band, and is a signal of a modulated wave obtained by modulating the carrier wave in the ultrasonic frequency band with a signal wave in the audible frequency band It is also good. When the signal applied to the electrostatic transducer 1A is a signal in the ultrasonic frequency band, the electrostatic transducer 1A is also referred to as an electrostatic ultrasonic transducer because it emits sound waves in the ultrasonic frequency band. [0055] FIG. 8 is a view for explaining the vibration state of the vibrating membrane 31 of the electrostatic transducer shown in FIG. By the voltage application method shown in FIG. 7B, as shown in FIG. 8A, the vibrating film 31 is attracted toward the electrode 11 by electrostatic force. 04-05-2019 19 Then, the electrostatic force changes (strong or weak) due to the change of the voltage of the AC signal, and the vibrating membrane 31 vibrates due to the balance between the elastic restoring force of the vibrating membrane 31 and the electrostatic force. [0056] At this time, since the vibrating film 31 is attracted to the electrode 11 side, the vibrating film 31 is stuck to the vibrating portion dividing member (epoxy insulating layer) 13. Therefore, since the vibrating membrane 31 hardly vibrates in this portion, the vibrating membrane 31 is divided into a plurality of vibrating portions (vibrating portions). Specifically, the vibrating portion (vibration portion) has the same shape as the circular portion of the vibrating portion division member 13. Therefore, the electrode portion 14 is positioned at a position facing the central portion of the vibrating portion (vibration portion). Therefore, a force can be applied to the vibrating membrane more efficiently than by applying an electrostatic force at the end of the vibrating portion (vibrating portion) as in the conventional pull-type electrostatic transducer. Therefore, the amplitude also increases, and the sound pressure can be increased. [0057] Further, sound waves generated by the vibration of the vibrating membrane 31 pass through the portion of the through hole 12 of the electrode 11 and pass through the through hole 22 of the resonance pipe member 21. At this time, the through hole 22 acts as a resonance tube. That is, when it is desired to generate an acoustic wave mainly at 50 kHz (ultrasound), the wavelength of the sound is determined as the velocity of the sound about 340 m / sec. Therefore, for example, when the thickness of the resonance tube member 21, that is, the length of the through hole 22 is about 1/4 (about 1.5 mm) of the wavelength, the through hole 22 acts as a resonance tube, and the sound pressure is reduced. Increase. The length of the through hole 22 is not limited to about 1⁄4 of the wavelength, and (in / 4) · n, where n is a positive odd number assuming that the wavelength is a resonance condition. It is also good. The reason for setting the wavelength to be about 1⁄4 is that the correction of the open end of the resonance tube causes the length to slightly change more than 1⁄4 of the wavelength and the resonance frequency to change by the thickness of the electrode. This results in an electrostatic transducer with high efficiency and high sound pressure output. In addition, the conditions of resonance are disclosed by Unexamined-Japanese-Patent No. 2007-68148 etc. FIG. [0058] 04-05-2019 20 In addition to forming the electrode portion 14, the through hole 12 of the electrode 11 has an effect of reducing the air resistance of the vibrating film 31 when air is released from the through hole 12. [0059] Thus, in the configuration of the electrostatic transducer shown in FIG. 7, when the vibrating membrane 31 is attracted to the electrode 11, there is an electrode portion that generates an electrostatic force corresponding to the central portion of the vibrating portion of the vibrating membrane 31. Therefore, a force can be applied to the vibrating membrane 31 to vibrate efficiently as compared with the conventional configuration. Further, by forming the resonance pipe by the through hole 22 of the resonance pipe member 21, the sound pressure can be further increased. Therefore, the electrostatic force can be efficiently transmitted to the vibrating film 31 to increase the amplitude of the vibrating film 31, and an electrostatic transducer with high efficiency and high sound pressure output can be realized. [0060] Third Embodiment In the first and second embodiments, the example in which the resonance tube is formed by the through hole 22 of the resonance tube member 21 has been described. Can be formed. In the third embodiment of the present invention, an example in which a resonance tube is formed in an electrode will be described. [0061] FIG. 9 is a view showing a configuration of an electrode 11A in an electrostatic transducer according to a third embodiment of the present invention. FIG. 9 shows a part of the electrode for the purpose of explanation. [0062] 04-05-2019 21 As shown in FIG. 9, as the electrode 11A, a through hole 12A is formed in a conductive material of metal (for example, aluminum alloy, stainless steel, etc.). As a method of forming the through holes 12A, there is a method of laminating or drilling metal edged thin plates. The electrode 11A shown in FIG. 9 is characterized in that the thickness t is larger than that of the electrode 11 shown in FIG. 2 (the thickness is required to form a resonance tube). [0063] Then, an epoxy insulating layer (for example, a resist film) is applied on the electrode 11A so as to include four holes (12Aa, 12Ab, 12Ac, 12Ad). This is the vibrating portion dividing member 13A, which is disposed between the electrode 11A and the vibrating film 31 and serves to divide the vibrating film 31 into a plurality of vibrating portions (vibrating portions). The vibrating membrane 31 has the same configuration as the vibrating membrane used in the first embodiment and the second embodiment (see FIG. 3B). [0064] FIG. 10 is a view showing the configuration of the electrostatic transducer according to the third embodiment of the present invention, and is a cross-sectional view passing through the center of the circular portion of the vibrating portion division member 13A. As shown in FIG. 10, in the electrostatic transducer 1B, the vibrating membrane 31 and the electrode 11A are disposed so as to sandwich the vibrating section dividing member 13A. [0065] FIG. 10B is a diagram showing a method of applying a voltage to the electrostatic transducer according to the third embodiment of the present invention. As shown in FIG. 10 (B). A DC bias voltage is applied to the vibrating film 31 by the DC bias power supply 32, and an AC signal (AC drive voltage) is applied to the electrode 11A by the AC signal source 33. However, the method of applying the voltage is not limited to this, and a change such as applying an AC signal (AC drive voltage) to the vibrating film 31 and applying a DC bias voltage to the electrode 11A is possible. 04-05-2019 22 [0066] The alternating current signal output from the alternating current signal source 33 may be a signal in the audible frequency band, and is a signal of a modulated wave obtained by modulating the carrier wave in the ultrasonic frequency band with a signal wave in the audible frequency band It is also good. When the signal applied to the electrostatic transducer 1 is a signal in the ultrasonic frequency band, the electrostatic transducer 1 emits an acoustic wave in the ultrasonic frequency band, and is also called an electrostatic ultrasonic transducer. [0067] FIG. 11 is a diagram for explaining the vibration state of the vibrating membrane 31 of the electrostatic transducer shown in FIG. By the voltage application method shown in FIG. 10B, as shown in FIG. 11, the vibrating film 31 is attracted toward the electrode 11A by electrostatic force. Then, the electrostatic force changes (strong or weak) due to the change in voltage of the AC signal (AC drive voltage), and the diaphragm 31 vibrates due to the balance between the elastic restoring force of the diaphragm 31 and the electrostatic force. [0068] At this time, since the vibrating film 31 is attracted to the electrode 11A side, the vibrating film 31 sticks to the vibrating portion dividing member 13A. Therefore, since the vibrating membrane 31 hardly vibrates in this portion, the vibrating membrane 31 is divided into a plurality of vibrating portions (vibrating portions). Specifically, the vibrating portion (vibrating portion) has the same shape as the circular portion of the vibrating portion dividing member (epoxy insulating layer) 13A. Therefore, the electrode portion 14A is located at a position facing the central portion of the vibrating portion (vibration portion). For this reason, it is possible to apply a force to the vibrating membrane to vibrate efficiently, rather than exerting an electrostatic force at the end of the vibrating portion (vibrating portion). Therefore, the amplitude also increases, and the sound pressure can be increased. [0069] Further, sound waves generated by the vibration of the vibrating membrane 31 pass through the 04-05-2019 23 through hole 12A of the electrode 11A. At this time, the portion of the through hole 12A acts as a resonance pipe. That is, when it is desired to generate a sound wave mainly at 50 kHz (ultrasonic wave), the sound wavelength is determined as the sound velocity of about 340 m / sec, so for example, the thickness of the resonance tube member 21, that is When the wavelength is about 1⁄4 (about 1.5 mm), the through hole 12A acts as a resonance tube to increase the sound pressure. Incidentally, the length of the through hole 12A is not limited to about 1/4 of the wavelength, and when the wavelength length is λ as the resonance condition, (in / 4) · n, where n is a positive odd number It is good also as ". Also, the reason for setting the wavelength to be about 1/4 is because the length is slightly changed from 1⁄4 of the wavelength due to the open end correction of the resonance tube. This results in an electrostatic transducer with high efficiency and high sound quality. In addition, the conditions of resonance are disclosed by Unexamined-Japanese-Patent No. 2007-68148 etc. FIG. [0070] In addition, as a structure of an electrode, it can change into the structure shown to the electrode 11B shown in FIG. In the electrostatic transducer 1C shown in FIG. 12, the electrode 11B is made of a resin (for example, acrylic, super engineering plastic, etc.) 23. Then, the through holes 25 are formed in the resin 23 by drilling or injection molding of the resin, and the conductive paste 24 is applied to the surface of the resin 23. Thereby, the weight of the electrostatic transducer can be reduced. [0071] Fourth Embodiment FIG. 13 is a diagram showing a configuration of an electrostatic transducer according to a fourth embodiment of the present invention. The electrostatic transducer 1D shown in FIG. 13 is an example in which the resonance pipe member 21 is disposed on both surfaces of the vibrating membrane 31 and the electrode 11. Thereby, the sound pressure can be increased for the sound waves generated from both sides of the vibrating film 31 and can be used. [0072] Fifth Embodiment FIG. 14 is a diagram showing a configuration of an electrostatic transducer according to a fifth embodiment of the present invention. The electrostatic transducer 1E shown 04-05-2019 24 in FIG. 14 is an example in which the resonance tube member 21 is disposed on the surface side of the vibrating membrane 31 in the electrostatic transducer 1B of the third embodiment shown in FIG. Thereby, the sound pressure can be increased for the sound waves generated from both sides of the vibrating film 31 and can be used. [0073] Sixth Embodiment From the above-described first embodiment, the shapes of the electrodes and the through holes in the fifth embodiment are not limited to the shapes shown in FIGS. 2 and 9. For example, the shape shown in FIG. 15 (A) or FIG. 15 (B) may be used. [0074] The electrode 11C shown in FIG. 15A is obtained by increasing the number of through holes 12C in the electrode portion 14C. The electrode 11D shown in FIG. 15B is provided with a through hole 12D so that the electrode portion 14D has a cross shape. [0075] Seventh Embodiment Next, an electrostatic transducer provided with an acoustic reflector according to a seventh embodiment of the present invention will be described. FIG. 16 is a view showing the configuration of an electrostatic transducer provided with an acoustic reflection plate. [0076] The configuration of the electrostatic transducer having the acoustic reflector shown in FIG. 16 is the same as that of the electrostatic transducer according to the first embodiment except that the acoustic reflectors 51 and 52 are provided on the back of the electrostatic transducer. It is identical to the configuration of 1 (see FIG. 5). In FIG. 16, only a part of the electrostatic transducer 1 is shown because of easy viewing of the drawing. 04-05-2019 25 [0077] The electrostatic transducer provided with the acoustic reflectors 51 and 52 exerts a remarkable effect particularly when driven by a modulation signal obtained by modulating a carrier wave in the ultrasonic frequency band with a signal in the audio frequency band. is there. Therefore, in the following description, the electrostatic transducer 1 is described as being used as an electrostatic ultrasonic transducer. [0078] In FIG. 16, the acoustic reflectors 51 and 52 are configured so that the ultrasonic waves emitted from the through holes 12 of the electrodes 11 of the electrostatic transducer 1 are all emitted to the front of the electrostatic transducer in the same length path. Is located in [0079] That is, one end of the acoustic reflection plate is located at the center position M of the back surface of the electrostatic transducer, and the acoustic reflector is disposed at an angle of 45 ° to both sides of the back surface of the electrostatic transducer with respect to the center position M At an angle perpendicular to the ends of the pair of first reflecting plates 51, 51 of a length corresponding to the ends X1, X2 of the electrostatic transducer and the pair of first reflecting plates 51, 51 A pair of second reflecting plates 52, 52 are respectively connected in the outward direction of the first reflecting plate and have a length equal to the length of the first reflecting plate. [0080] In the above configuration, the first reflecting plates 51, 51 are disposed at an angle of 45 ° with respect to both sides of the center position M of the back surface of the electrostatic transducer, to the point where the end thereof coincides with the end of the electrostatic transducer The length of the The ultrasonic waves emitted from the back of the electrostatic transducer by the first reflecting plate 51 are horizontally reflected. 04-05-2019 26 [0081] Next, by connecting the second reflectors 52, 52 connected at an angle perpendicular to the first reflectors 51, 51 to the outside of the first reflectors 51, 51, the ultrasonic waves are electrostatically Emitted to the front of the mold transducer. It is necessary that the second reflector length be equal to the first reflector length. The important thing here is that the ultrasonic waves emitted from the back of the electrostatic transducer all have the same length of path. The fact that the path lengths are the same means that the phases of the ultrasonic waves emitted from the back are all in phase. [0082] Also, as shown in FIG. 16, the acoustic wave can be geometrically handled because the emitted acoustic wave is an ultrasonic wave and has extremely strong directivity. Another point that needs to be mentioned is the time difference between the ultrasound emitted from the front of the electrostatic transducer and the ultrasound reflected from the back and emitted to the front. [0083] Assuming that the transducer is circular and the radius is r, the ultrasonic waves emitted from a point separated from the center position M of the transducer by a distance from the center position M to the transducer front face are approximately 2r, ie, equal to the diameter of the transducer . Of course, the distance a must satisfy the following equation. 0≦a≦r …… (1) [0084] Now, assuming that the diameter of the transducer is about 10 cm and the speed of sound is 340 m / sec, the time difference between the ultrasonic wave emitted from the front and the ultrasonic wave emitted from the back to reach the front is about 0.29 msec. There is no problem because it is a time difference that human beings can not perceive. That is, ultrasonic waves emitted from the front and back of the transducer can be used effectively. 04-05-2019 27 [0085] Eighth Embodiment Next, an ultrasonic speaker according to an eighth embodiment of the present invention will be described. FIG. 17 is a view showing the configuration of an ultrasonic speaker using the electrostatic transducer of the present invention. [0086] The ultrasonic speaker according to the present embodiment is the above-described electrostatic transducer (the electrostatic transducer according to the first to seventh embodiments) of the present invention, which generates a sound wave in an ultrasonic frequency band. Used as an electrostatic ultrasonic transducer. [0087] Since this electrostatic ultrasonic transducer has an electrode portion for generating an electrostatic force corresponding to the central portion of the vibrating portion of the vibrating membrane 31, the force is more efficiently vibrated in the vibrating membrane 31 compared to the conventional configuration. Can be added. Further, by forming the resonance pipe by the through hole 22 of the resonance pipe member 21, the sound pressure can be further increased. [0088] In FIG. 17, the ultrasonic speaker includes an audio frequency wave oscillation source 61 that generates a signal wave in the audio wave frequency band, and a carrier wave oscillation source 62 that generates and outputs a carrier wave (carrier wave) in the ultrasonic frequency band. A modulator 63, a power amplifier 64, and an electrostatic ultrasonic transducer 65 are included. The modulator 63 modulates the carrier wave output from the carrier wave oscillation source 62 with the signal wave in the audio wave frequency band output from the audio frequency wave oscillation source 61, and the electrostatic ultrasonic transducer via the power amplifier 64. Supply to 65. 04-05-2019 28 [0089] In the above configuration, the carrier wave in the ultrasonic frequency band output from the carrier wave oscillation source 62 is modulated by the modulator 63 by the signal wave output from the audio frequency wave oscillation source 61, and the modulation signal amplified by the power amplifier 64 The electrostatic ultrasonic transducer 65 is driven. As a result, the modulated signal is converted to a sound wave of finite amplitude level by the electrostatic ultrasonic transducer 65, and this sound wave is emitted into the medium (in air) and the original audio frequency band by the nonlinear effect of the medium (air). Signal sound is selfreproduced. [0090] 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. [0091] 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. [0092] 04-05-2019 29 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. [0093] As described above, in the ultrasonic speaker according to the present invention, the electrostatic transducer according to the present invention is used, and electrostatic force can be efficiently transmitted to the vibrating membrane to increase the amplitude of the vibrating membrane. Further, since the output sound pressure can be further increased by the resonance pipe, the sound signal can be reproduced with a sufficient sound pressure level and a wide band characteristic. In particular, in an ultrasonic speaker, an acoustic signal can be reproduced so as to be emitted from a virtual sound source formed in the vicinity of a sound wave reflection surface such as a screen with a sufficient sound pressure level and a wide band characteristic. Therefore, control of the reproduction range can be easily performed. [0094] As described above, in the electrostatic transducer according to the present invention, the electrode portion is positioned at a position opposed to the central portion of the vibrating portion (vibration portion). Therefore, an electrostatic force is generated at the central portion of the vibrating portion where the vibrating membrane vibrates. For this reason, compared with the structure which an electrostatic force produces only at the edge part of the vibration part which a diaphragm vibrates when the same electrostatic force arises, the force for vibrating a diaphragm efficiently can be applied. Further, according to the configuration of the present invention, the through hole or the through hole portion acting as a resonance pipe is provided. Thus, the resonance tube action can increase the sound pressure of the radiated sound wave. Therefore, according to the present invention, a configuration that generates both of the effects described above can be realized, so that an electrostatic transducer that can obtain high efficiency and high sound pressure, an ultrasonic speaker including the same, and the like can be realized. [0095] The electrostatic transducer according to the present invention can be used not only for ultrasonic speakers but also for sensors such as distance sensors. 04-05-2019 30 [0096] Although the embodiments of the present invention have been described above, the electrostatic transducer and the ultrasonic speaker according to the present invention are not limited to the above illustrated examples, and various modifications may be made within the scope of the present invention. Of course, changes can be made. [0097] Explanatory drawing of the basic concept of the electrostatic transducer of this invention. BRIEF DESCRIPTION OF THE DRAWINGS The block diagram of the electrode of the electrostatic transducer which concerns on 1st Embodiment. The block diagram of the resonance tube member of an electrostatic transducer. Explanatory drawing of a structure of the electrostatic transducer concerning 1st Embodiment. FIG. 1 is a cross-sectional view of an electrostatic transducer according to a first embodiment. Explanatory drawing of the vibration state of the vibrating film of the electrostatic transducer shown in FIG. The block diagram of the electrostatic transducer which concerns on 2nd Embodiment. Explanatory drawing of the vibration state of the vibrating film of the electrostatic transducer shown in FIG. The block diagram of the electrode of the electrostatic transducer which concerns on 3rd Embodiment. The block diagram of the electrostatic transducer which concerns on 3rd Embodiment. FIG. 11 is an explanatory view of a vibration state of a vibrating membrane of the electrostatic transducer shown in FIG. 10. The figure which shows the other structure of the electrode of an electrostatic type transducer. The block diagram of the electrostatic transducer concerning 4th Embodiment. The block diagram of the electrostatic transducer concerning 5th Embodiment. The figure which shows the example of the other shape of an electrode part and a through-hole part. The figure which shows the structure of an electrostatic transducer provided with an acoustic reflection board. The figure which shows the structure of the ultrasonic speaker of this invention. The figure which shows the structural example of the conventional pull type electrostatic ultrasonic transducer. Explanatory drawing of the problem of the conventional pull type electrostatic ultrasonic transducer. FIG. 8 is a view showing another configuration example of a conventional pull-type electrostatic ultrasonic transducer. Explanation of sign 04-05-2019 31 [0098] 1, 1A, 1B, 1C, 1D, 1E: electrostatic transducers, 11, 11A, 11B, 11C, 11D, electrodes 12, 12, 12A, 12C, 12D, through holes 13, 13A ... Vibrating part dividing member, 14, 14A, 14C, 14D ... Electrode part, 21 ... Resonance tube member, 22 ... Through hole, 23 ... Resin, 24 ... Conductive paste, 25 · · · Through hole, 31 · · · vibrating film, 31 A · · · vibrating electrode layer, 31 B · · · dielectric film, 32 · · · DC bias power supply, 33 · · · · · · 51, 52 · · · · · · Acoustic reflection plate, 61 ··· Audio frequency wave oscillation source, 62 · · · Carrier wave oscillation source, 63 · · · · · · · · · · · · · · · · · · · · · · · · · Power amplifier, 65 · · · electrostatic ultrasonic transducer 04-05-2019 32
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