JP2019080091A - Capacitive sound wave generator and capacitive speaker - Google Patents

Abstract

To provide a capacitive sound wave generator and a capacitive speaker into which dust, water, moisture, and the like, are difficult to enter, and which can restrain power consumption while improving sound quality.SOLUTION: A tabular fixed electrode 11 has an open hole 11a penetrating the thickness. Tabular or membrane vibrator 12 and vibration electrode 13 are placed, respectively, on one and the other front sides, and provided movably in the thickness direction for the fixed electrode 11. A connection member 14 is connecting the membrane vibrator 12 and the vibration electrode 13 through the open hole 11a of the fixed electrode 11, so that the membrane vibrator 12 and the vibration electrode 13 move in the same direction. Audio signal input means 16 is provided to be able to apply a voltage to the fixed electrode 11, the vibrator 12 and the vibration electrode 13 so that the vibrator 12 moves by electrostatic attraction between the fixed electrode 11 and the vibrator 12, and the vibration electrode 13 moves by electrostatic attraction between the fixed electrode 11 and the vibration electrode 13.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a capacitive sound wave generator and a capacitive speaker.

  Among the sound wave generating devices, dynamic speakers (electrodynamic speakers) utilizing electromagnetic force are often used as speakers for outputting sound waves in the audible range (see, for example, Non-Patent Document 1). Since a dynamic speaker has a coil attached to a diaphragm, the diaphragm is heavy, and when outputting a sound wave, it is necessary to vibrate the diaphragm with a strong force. At this time, since the inertia force of the diaphragm at the time of vibration becomes large, there is a problem that a shift occurs between the input electric signal and the vibration of the diaphragm. In particular, in the case of a small-sized speaker such as an earphone, there is a problem that the displacement between the electric signal and the vibration is further increased because the inertial force of the diaphragm becomes relatively large.

  Then, in order to solve such a problem, a capacitive speaker (electrostatic speaker) is used (for example, refer to patent documents 1-5). In the capacitive speaker, as shown in FIG. 8, two fixed electrodes 52 are disposed so as to sandwich the diaphragm 51. In this capacitive speaker, for example, as shown in FIGS. 9A and 9B, the diaphragm 51 is charged positively or negatively, and each fixed electrode 52 is charged with electricity of the opposite polarity to the diaphragm 51. By sending a signal and charging it, the electrostatic attraction force acting between the diaphragm 51 and each fixed electrode 52 is used to vibrate the diaphragm 51 to output a sound wave. In the capacitive speaker, a coil or the like is not attached to the diaphragm 51, and the diaphragm 51 can be vibrated in accordance with an electrical signal. It also has the advantages of a simple structure and lower power consumption compared to dynamic speakers.

Iman Shahosseini, et al., “Electromagnetic MEMS microspeakers for portable electronic devices”, Microsystem Technologies, June 2013, Volume 19, Issue 6, p. 879-886

U.S. Pat. No. 6,842,964 European Patent Application Publication No. 2410768 European Patent Application Publication No. 2464142 European Patent Application Publication No. 2582156 Patent No. 3281887

  However, as shown in FIGS. 8 and 9, the conventional capacitive type speakers as described in Patent Documents 1 to 5 have the respective fixed electrodes in order to transmit the sound waves generated by the vibration of the diaphragm 51 to the outside. It is necessary to make one or a plurality of holes 52a in 52, and dust, water, moisture, etc. easily enter between the diaphragm 51 and each fixed electrode 52 from the hole 52a, and the diaphragm 51 or each fixed electrode 52 is electrostatically There is a problem that it adheres to When dust, moisture or the like adheres to the diaphragm 51 or each fixed electrode 52, the diaphragm 51 and each fixed electrode 52 short-circuit and discharge occurs, causing damage to the diaphragm 51 or a hole in the diaphragm 51. It may cause damage or damage.

  In addition, since the surface area of each fixed electrode 52 is reduced by the holes 52 a and the acting electrostatic force is reduced, it is necessary to increase the voltage applied to the diaphragm 51 and each fixed electrode 52 in order to compensate for it. There was also a problem that it would increase. In addition, when the sound wave from the diaphragm 51 passes through the holes 52a of the fixed electrodes 52, for example, the frequency of the sound waves is affected by the size and shape of the holes 52a of the fixed electrodes 52, and the waveform of the sound waves is disturbed. As a result, there is also a problem that the sound quality is degraded.

  The present invention has been made in view of such problems, and it is difficult for dust, water, moisture and the like to enter the inside, power consumption can be suppressed, and a capacitance type sound wave generator capable of enhancing sound quality. And providing a capacitive speaker.

  In order to achieve the above object, a capacitance-type acoustic wave generator according to the present invention is a plate-like fixed electrode having one or more through holes provided through a thickness, and a plate-like device. Or a vibrator formed in a film shape and disposed on one surface side of the fixed electrode so as to face the fixed electrode, and at least a central portion of the fixed electrode being movable in a thickness direction The plate-like or film-like form is disposed on the other surface side of the fixed electrode so as to face the fixed electrode, and at least a central portion is provided movably in the thickness direction with respect to the fixed electrode. A connecting member in which the vibrating body and the vibrating electrode are connected through at least one of the through holes of the fixed electrode so that the vibrating electrode and the vibrating body and the vibrating electrode move in the same direction; Between the fixed electrode and the vibrator Capable of applying a voltage to the fixed electrode, the vibrator and the vibrating electrode so that the vibrator is moved by electrostatic attraction and the vibrating electrode is moved by electrostatic attraction between the fixed electrode and the vibrating electrode And audio signal input means provided in the device.

  The capacitance type sound wave generator according to the present invention can output sound waves according to the following principle. That is, as in the example shown in FIG. 1, the vibrator 12 and the vibrating electrode 13 are disposed so as to sandwich the fixed electrode 11 as in the example shown in FIG. A connecting member 14 connects the vibrating body 12 and the vibrating electrode 13 through 11 a. In the capacitance type sound wave generator according to the present invention, for example, as shown in FIG. 2A, a voltage is applied to the fixed electrode 11 by an audio signal input unit to negatively charge the fixed electrode 11. In this state, a voltage is applied to the vibrating body 12 to send an electric signal of the opposite polarity to the fixed electrode 11 to the vibrating body 12 to charge it positively, so that static electricity is generated between the vibrating body 12 and the fixed electrode 11. The vibrating body 12 can be moved to the fixed electrode 11 side by applying an attractive force. Similarly, as shown in FIG. 2 (b), a voltage is applied to the vibrating electrode 13 to send an electric signal of the opposite polarity to the fixed electrode 11 to the vibrating electrode 13 to charge it positively, thereby causing vibration. Electrostatic attraction can be applied between the electrode 13 and the fixed electrode 11 to move the vibrating electrode 13 to the fixed electrode 11 side. At this time, since the vibrating body 12 and the vibrating electrode 13 move in the same direction via the connection member 14, the vibrating body 12 can be moved to the opposite side to the fixed electrode 11. For this reason, by applying a voltage to the vibrating body 12 and the vibrating electrode 13 according to the audio signal by the audio signal input means, the vibrating body 12 can be vibrated and a sound wave can be output.

  The capacitance-type sound wave generator according to the present invention is not limited to the embodiment shown in FIG. 2, but for example, the fixed electrode 11 may be positively charged and the vibrator 12 and the vibrating electrode 13 may be negatively charged. . Also in this case, the vibrator 12 can be similarly vibrated, and a sound wave can be output.

  In the capacitance type sound wave generator according to the present invention, any voltage may be applied to the fixed electrode, the vibrating body and the vibrating electrode by the audio signal input means as long as the vibrating body can be vibrated in accordance with the audio signal. For example, the audio signal input means applies a positive or negative bias voltage to the fixed electrode, converts the audio signal into an analog signal based on the bias voltage, and converts the polarity of the analog signal It may be configured to generate an inverted inverted signal and apply the analog signal and the inverted signal to the vibrating body and the vibrating electrode, or the vibrating electrode and the vibrating body, respectively. In this case, the same voltage as that applied to the diaphragm 51, one fixed electrode 52 and the other fixed electrode 52 of the conventional capacitive speaker as shown in FIGS. 8 and 9 can be applied. .

  In the electrostatic capacitance type sound wave generator according to the present invention, the vibrator and the vibrating electrode are disposed so as to sandwich the fixed electrode, and it is not necessary to provide a hole in the outer vibrating body and the vibrating electrode. Dust, water, moisture, and the like are less likely to enter between the fixed electrode and the vibrator or the vibrating electrode, as compared to the conventional capacitive speaker in which the electrode is provided with a hole. For this reason, adhesion of dust and the like to the vibrator, the vibrating electrode, and the fixed electrode can be suppressed, and the occurrence of discharge can be prevented, and the life of the vibrator can be extended.

  In the capacitance type sound wave generator according to the present invention, the through hole provided in the fixed electrode is used only for passing the connection member, so the ratio to the surface area of the fixed electrode is smaller than the hole through which the sound wave passes. It can be very small. For this reason, even if there is a through hole, the reduction in electrostatic attraction due to the through hole is small, and power consumption can be suppressed as compared with the conventional capacitance type speaker in which the influence by the holes of each fixed electrode is large. . Moreover, when there are a plurality of through holes, the connection member may be passed through all the through holes or may be passed through a part of the through holes. The space between the through hole through which the connecting member is passed and the gap between the connecting member and the through hole through which the connecting member is not passed is the space on the vibrating body side of the fixed electrode and the vibrating electrode when the vibrating body or the vibrating electrode vibrates. It can be used to ventilate the side space.

  In the electrostatic capacitance type sound wave generator according to the present invention, since the vibrator is disposed outside the fixed electrode, the sound wave output from the vibrator is propagated to the outside without disturbing the waveform due to interference. The sound quality can be improved.

  In the electrostatic capacitance type sound wave generator according to the present invention, a support is provided so as to fix the fixed electrode at its peripheral portion and to support at least one of the vibrator and the vibrating electrode at its peripheral portion. You may have a part. In this case, both the vibrating body and the vibrating electrode may be supported by the support portion, but since the vibrating body and the vibrating electrode are connected by the connection member, only one of the vibrating body and the vibrating electrode is supported It may be supported by a part.

  In the electrostatic capacitance type sound wave generator according to the present invention, the vibrator and the vibrating electrode may have any configuration as long as at least a central portion is movably provided in the thickness direction. The vibrator and the vibrating electrode may be the same material or configuration as each other, or may be different materials or configurations. For example, the vibrating body and the vibrating electrode are made of a thin and flexible film of material such as Parylene, polyethylene (PE), metallic glass, etc., and the peripheral portion thereof is fixed to the frame-shaped support portion. It may be The film preferably has a thickness of 50 μm or less, particularly preferably 20 μm or less. Further, the Young's modulus is preferably 80 GPa or less, and particularly preferably 50 GPa or less.

  The vibrating body and the vibrating electrode have a central portion made of a hard plate made of silicon or ceramic, a metal made of Al, Cu, Ni, etc., and a peripheral portion made of a flexible thin material, and the peripheral portion May be fixed to the frame-like support. The size of the central portion is preferably 100 μm or less in diameter. The whole of the vibrator and the vibrating electrode is made of a hard plate made of silicon, ceramic, Al, Cu, Ni, or other metal, and the peripheral portion thereof is fixed to the frame-like support by a plate spring or the like. It may be The plate spring or the like may be made of the same material as the vibrating body or the vibrating electrode, or may be made of a different material.

  The vibrator and the vibrating electrode are preferably made of a low resistance material such as a conductor so that electricity can be passed when voltage is applied by the audio signal input means, but at least the conductor layer is formed on the surface on the fixed electrode side. It may consist of a coated insulator. The conductor layer is made of, for example, carbon, metal, silicon doped with impurities, or the like.

  The fixed electrode is preferably made of a hard plate made of silicon, a ceramic, or a metal such as Al, Cu, or Ni. The number of connection members may be one, and may be plural depending on the number of through holes. Preferably, the connecting member has a portion at least partially electrically isolated. The insulated part is preferably made of a polymer such as epoxy resin or benzocyclobutene, or a ceramic, and the like, and the resistance value is preferably 1 MΩ or more.

  The capacitance type acoustic wave generator according to the present invention may be used for any application as long as it is an application that generates an acoustic wave. In addition, the "sound wave" in this specification includes not only elastic waves of frequencies in the audible range but also elastic waves of frequencies other than the audible range. The capacitance-type sound wave generator according to the present invention has, for example, a capacitance-type speaker configured to be capable of generating sound waves in the audible range by vibration of a vibrating body by audio signal input means, or a frequency higher than the audible range. The ultrasonic wave generator may be configured as an ultrasonic wave generator capable of generating an ultrasonic wave, or an ultra low frequency sound generator configured to be able to generate an ultra low frequency wave having a frequency lower than that of the audible range. The audible range varies depending on the person, but is approximately 20 Hz to 20 kHz.

  According to the present invention, it is possible to provide an electrostatic capacitance type sound wave generator and an electrostatic capacitance type speaker that can suppress dust, water, moisture, etc. from entering the inside, can suppress power consumption, and can improve sound quality. it can.

It is explanatory drawing which shows the principle which outputs a sound wave of the electrostatic capacitance type sound generator based on this invention. The principle of outputting a sound wave of the capacitance type sound wave generator according to the present invention is shown (a) when electrostatic attraction is applied between the vibrator and the fixed electrode, (b) the vibration electrode and the fixed electrode And an electrostatic attractive force acting between them. BRIEF DESCRIPTION OF THE DRAWINGS It is a circuit diagram which shows the electrostatic capacitance type sound wave generator of embodiment of this invention. It is sectional drawing which shows the audio | voice generation part of the electrostatic capacitance type sound wave generator of embodiment of this invention. It is sectional drawing which shows the manufacturing method of the audio | voice generation | occurrence | production part of the sound wave generator of an electrostatic capacitance type | mold shown in FIG. It is sectional drawing which shows the modification to which a vibrating body consists of a thin film of the electrostatic capacitance type sound wave generator of embodiment of this invention. It is sectional drawing which shows the manufacturing method of the audio | voice generation | occurrence | production part of the sound wave generator of an electrostatic capacitance type | mold shown in FIG. It is explanatory drawing which shows the principle which outputs a sound wave of the conventional capacitive speaker. The principle of outputting a sound wave of a conventional capacitive speaker (a) When electrostatic attraction is applied between a diaphragm and one fixed electrode, (b) the diaphragm and the other fixed electrode Is an explanatory view when electrostatic attraction is applied between

Hereinafter, embodiments of the present invention will be described based on the drawings.
3 to 7 show a capacitive acoustic wave generator according to the embodiment of the present invention.
As shown in FIG. 3 and FIG. 4, the electrostatic capacitance type sound wave generator 10 has a fixed electrode 11, a vibrating body 12, a vibrating electrode 13, a connection member 14, a support portion 15 and an audio signal input means 16. ing.

  As shown in FIG. 3 and FIG. 4, the fixed electrode 11 has a disk shape, and has a through hole 11 a provided at the center through the thickness. The fixed electrode 11 has a terminal 11 b at its end. The vibrating body 12 has a diameter smaller than that of the fixed electrode 11 and has a thin disc shape. The vibrating body 12 is disposed on one surface side of the fixed electrode 11 so as to face the fixed electrode 11. The vibrating electrode 13 has a disk shape having the same diameter and thickness as the vibrating body 12. The vibrating electrode 13 is disposed on the other surface side of the fixed electrode 11 so as to face the fixed electrode 11. The connecting member 14 has an elongated rod-like shape, and connects the vibrating body 12 and the vibrating electrode 13 through the through hole 11 a of the fixed electrode 11. Both ends of the connecting member 14 are fixed to the central portion of the vibrating body 12 and the central portion of the vibrating electrode 13 respectively.

  As shown in FIG. 4, the support portion 15 includes a first frame 21 provided to surround the vibrating body 12, and a second frame 22 provided to surround the vibrating electrode 13. And a fixing member 23 for fixing the fixed electrode 11. The first frame 21 and the second frame 22 are arranged to sandwich the fixed electrode 11 therebetween. The first frame 21 is provided with a plurality of leaf springs 24 along the inner peripheral edge, and supports the vibrating body 12 by fixing the inner end of each leaf spring 24 to the peripheral edge of the vibrating body 12 ing. The first frame 21 has a terminal 25 at its end. The second frame 22 is provided with a plurality of leaf springs 26 along the inner peripheral edge, and supports the vibrating electrode 13 by fixing the inner end of each leaf spring 26 to the peripheral edge of the vibrating electrode 13. ing. The second frame 22 has a terminal 27 at its end. The fixing member 23 is provided between the first frame 21 and one surface of the fixed electrode 11 so as to fix the fixed electrode 11 between the first frame 21 and the second frame 22, and A plurality of each are provided between the second frame 22 and the other surface of the fixed electrode 11. The fixing member 23 is fixed to the peripheral portion of the fixed electrode 11.

  As a result, the vibrating body 12 can vibrate in the thickness direction with respect to the fixed electrode 11 through the plate springs 24. In addition, the vibrating electrode 13 can vibrate in the thickness direction with respect to the fixed electrode 11 through the plate springs 26. The vibrating body 12 and the vibrating electrode 13 move in the same direction by the connection member 14 and vibrate at the same time.

  In the example shown in FIG. 4, the fixed electrode 11, the vibrator 12 and the vibrating electrode 13 are made of low-resistance conductive silicon. The connecting member 14 has a central portion 14a made of conductive silicon, and both end portions 14b connected to the vibrating body 12 and the vibrating electrode 13 are made of insulating epoxy resin SU-8. In addition, the first frame 21 is formed between the low resistance conductive silicon with the insulating layer 42 of silicon oxide interposed therebetween. The second frame 22 is made of low resistance conductive silicon. The fixing member 23 is made of insulating epoxy resin SU-8. The terminal 11b of the fixed electrode 11, the terminal 25 of the first frame 21, and the terminal 27 of the second frame 22 are made of a conductive Ti / Au layer.

  As shown in FIG. 3, the audio signal input unit 16 has a bias generation unit 31 and a voltage conversion unit 32. The bias generation unit 31 generates positive and negative bias voltages, and supplies the positive bias voltage to the fixed electrode 11 through the terminal 11 b of the fixed electrode 11. Further, the bias generation unit 31 supplies a negative bias voltage to the voltage conversion unit 32. The voltage conversion unit 32 receives an audio signal from the audio input terminal 32a, and the audio signal is set to a positive voltage or a bias potential higher than the bias potential based on the negative bias voltage supplied from the bias generation unit 31. It is adapted to convert to a low negative voltage analog signal. The voltage conversion unit 32 supplies the converted analog signal to the vibrating body 12 through the terminal 25 of the first frame 21, and an inverted signal obtained by inverting the polarity of the analog signal is output from the second frame 22. It is supplied to the vibrating electrode 13 through the terminal 27. Accordingly, the electrostatic capacitance type sound wave generator 10 vibrates using electrostatic attraction acting between the vibrating body 12 and the fixed electrode 11 and between the vibrating electrode 13 and the fixed electrode 11 according to the principle shown in FIG. The body 12 is vibrated to generate sound waves.

  The sound generating portion of the capacitive sound wave generator 10 shown in FIG. 4 can be manufactured, for example, according to the method shown in FIG. That is, first, as shown in FIG. 5A, a base silicon layer 41 with a thickness of 400 μm, an insulating layer 42 made of silicon oxide with a thickness of 5 μm provided on the top surface, and a thickness provided on the top surface On an SOI (Silicon on Insulator) substrate consisting of a 20 .mu.m-thick silicon active layer 43, a part of the silicon active layer 43 is etched away in a slit-like manner to the insulating layer 42 by photolithography and dry etching. A circular vibrator 12 and a first frame 21 surrounding the periphery are formed. At this time, a plurality of beam-like portions connecting the vibrating body 12 and the first frame 21 are left without being etched away, and a plate spring 24 (for example, 100 μm wide and 100 μm long) is formed. Further, a Ti / Au bi-layer film (Ti 0.3 μm / Au 1 μm) is formed on the surface of the silicon active layer 43 as a terminal 25 of the first frame 21 by sputtering. Here, the base silicon layer 41 and the silicon active layer 43 are made of low resistance (for example, 0.02 Ωcm) conductive silicon in order to use as an electrode that generates electrostatic attraction.

  Next, as shown in FIG. 5B, a photosensitive epoxy resin (SU-8) layer having a thickness of 100 μm is formed on the surface of the silicon active layer 43 by spin coating, and the first photolithographic process is performed. In the frame 21 and the central portion of the vibrating body 12, SU-8 is left in a cylindrical shape (diameter 100 μm), and the fixing member 23 and the end 14b of the connecting member 14 are formed. As shown in FIG. 5 (c), SU-8 (fixing member 23 and connecting member) in which a low resistance (resistivity 0.02 Ωcm) silicon substrate 44 with a thickness of 200 μm for the fixed electrode 11 is formed in FIG. 5 (b) A Ti / Au two-layer film (Ti 0.3 μm / Au 1 μm) is formed on the surface of the silicon substrate 44 as the terminal 11 b of the fixed electrode 11 while adhering to the end face of the end portion 14 b) of FIG. As shown in FIG. 5D, a circular slit with an inner diameter of 120 μm and a width of 20 μm is formed by photolithography dry etching at a position corresponding to SU-8 (the end 14b of the connection member 14) in the central part of the vibrator 12. A central portion 14a of the connecting member 14 is formed inside the circular slit.

  As shown in FIG. 5E, the low resistance (resistivity 0.02 Ωcm) silicon substrate 45 with a thickness of 400 μm is etched away in a slit shape to a depth of 20 μm by photolithography and dry etching to a diameter of 1000 μm. A circular vibrating electrode 13 and a second frame 22 surrounding the periphery thereof are formed. At this time, a plurality of beam-like portions connecting the vibrating electrode 13 and the second frame 22 are left without being etched away, and a plate spring 26 (for example, 100 μm wide and 100 μm long) is formed. Further, a Ti / Au double-layer film (Ti 0.3 μm / Au 1 μm) is formed on the surface of the silicon substrate 45 opposite to the vibrating electrode 13 as a terminal 27 of the second frame 22 by sputtering.

  As shown in FIG. 5F, a photosensitive epoxy resin (SU-8) layer having a thickness of 100 μm is formed by spin coating on the surface on the side of the vibrating electrode 13 in FIG. Thus, SU-8 is left in a cylindrical shape (with a diameter of 100 μm) in the second frame 22 and in the central portion of the vibrating electrode 13 to form the end 14 b of the fixing member 23 and the connecting member 14. The central portion 14a of the fixed electrode 11 and the connecting member 14 formed in FIG. 5D is adhered to the end face of the SU-8 (the fixing member 23 and the end 14b of the connecting member 14). At this time, SU-8 (the end 14b of the connection member 14) at the central portion of the vibrating electrode 13 is disposed inside the central slit 14a of the central portion of the fixed electrode 11 (the central portion 14a of the connection member 14). Bonding forms a connecting member 14 consisting of a central portion 14a and opposite ends 14b.

  As shown in FIG. 5G, the surface of the silicon substrate 45 on the opposite side to the vibrating electrode 13 is formed by photolithography and dry etching using a part of the second frame 22, the vibrating electrode 13 and the flat spring 26. In the range including the vibrating electrode 13 and the plate spring 26, the etching is removed to the depth etched in FIG. 5 (e). Finally, as shown in FIG. 5H, the base silicon layer 41 is formed by photolithography and dry etching in a range including the vibrating body 12 and the leaf spring 24 with a part of the first frame 21 remaining. Then, the insulating layer 42 is etched away, and the insulating layer 42 on the vibrating body 12 and the flat spring 24 is removed. Thus, the sound generating portion of the capacitive acoustic wave generator 10 shown in FIG. 4 can be manufactured.

  Since the vibrator 12 and the vibrating electrode 13 are disposed so as to sandwich the fixed electrode 11 in the electrostatic capacitance type sound wave generator 10, it is not necessary to provide a hole in the outer vibrating body 12 and the vibrating electrode 13, so Dust, water, moisture and the like are less likely to enter between the fixed electrode 11 and the vibrating body 12 or the vibrating electrode 13 as compared with the conventional capacitance type speaker in which each fixed electrode is provided with a hole. For this reason, it is possible to suppress the adhesion of dust and the like to the vibrating body 12, the vibrating electrode 13, and the fixed electrode 11, and to prevent the occurrence of the discharge, it is possible to extend the life of the vibrating body 12. For example, the life of the vibrator 12 can be extended to 3 to 5 times or more of the life of the diaphragm of the conventional capacitive speaker.

  In the capacitance type sound wave generator 10, the through hole 11a provided in the fixed electrode 11 is used only for passing the connection member 14, so the ratio to the surface area of the fixed electrode 11 compared to the hole through which the sound wave passes. Can be very small. For this reason, even if the through hole 11a exists, the sound pressure of the sound wave generated by the vibrating body 12 is hardly reduced, and the power consumption is higher than that of the conventional capacitance type speaker having a large influence by the holes of each fixed electrode. Can be suppressed.

  Since the vibrator 12 is disposed outside the fixed electrode 11, the acoustic wave generator 10 of the capacitance type propagates the sound wave output from the vibrator 12 to the outside without the waveform being disturbed by interference. The sound quality can be improved. The capacitance-type sound wave generator 10 is particularly effective when used as a small capacitance-type speaker, for example, as an intelligent speaker, a computer speaker, a portable terminal speaker, or a hearing aid speaker Can. In the example shown in FIGS. 4 and 5, the drive voltage is about 200V to 600V.

  In the electrostatic capacitance type sound wave generator 10 shown in FIGS. 4 and 5, since the vibrating body 12 and the vibrating electrode 13 have the same configuration, even if the vibrating body 12 and the vibrating electrode 13 are interchanged. Good. In addition, since the vibrator 12 and the vibrating electrode 13 are connected by the connection member 14 in the electrostatic capacitance type sound wave generator 10, only one of the vibrator 12 and the vibrating electrode 13 is supported by the support portion 15. It may be done.

  Further, as shown in FIG. 6, in the electrostatic capacitance type sound wave generator 10, the vibrating body 12 and / or the vibrating electrode 13 may be made of a thin film. Even in this case, the vibrator 12 can be vibrated in accordance with the principles of FIGS. 1 and 2, and a sound wave can be output. In the example shown in FIG. 6, the vibrating body 12 is formed of a thin film, and the vibrating electrode 13 has a plate shape. The thin film preferably has a thickness of 1 to 50 μm and a diameter of 5 mm or less.

  The voice generation part shown in FIG. 6 can be manufactured, for example, according to the method shown in FIGS. 5 (a) to 5 (d) and FIG. That is, after the arrangement of the vibrating body 12 and the vibrating electrode 13 is reversed and the steps of FIGS. 5A to 5D are performed, as shown in FIG. 7A, a low resistance (resistivity of 400 μm) is obtained. A thin film layer 46 (oscillator 12) made of Parylene is formed on the surface of a 0.02 Ωcm silicon substrate 45. Further, a Ti / Au double-layer film (Ti 0.3 μm / Au 1 μm) is formed on the surface of the silicon substrate 44 opposite to the thin film layer 46 as a terminal 27 of the second frame 22 by sputtering.

  As shown in FIG. 7B, a 100 μm thick photosensitive epoxy resin (SU-8) layer is formed on the surface of the thin film layer 46 by spin coating, and the periphery of the thin film layer 46 is formed by photolithography. The SU-8 is left in a cylindrical shape (diameter 100 μm) at the center portion and the center portion, and the fixing member 23 and the end 14 b of the connecting member 14 are formed. The central portion 14a of the fixed electrode 11 and the connecting member 14 formed in FIG. 5D is adhered to the end face of the SU-8 (the fixing member 23 and the end 14b of the connecting member 14). At this time, SU-8 (the end 14b of the connection member 14) at the central portion of the thin film layer 46 is disposed inside the central slit 14a of the central portion of the fixed electrode 11 (the central portion 14a of the connection member 14). Bonding forms a connecting member 14 consisting of a central portion 14a and opposite ends 14b.

  As shown in FIG. 7C, the silicon substrate 45 is etched away by photolithography and dry etching, leaving the peripheral portion of the thin film layer 46. Finally, the base silicon layer 41 is etched away to the insulating layer 42 by photolithography and dry etching in a range including the vibrating electrode 13 and the leaf spring 24 with a part of the first frame 21 remaining. The insulating layer 42 on the vibrating electrode 13 and the plate spring 24 is removed. Thereby, the sound generation part of the electrostatic capacitance type sound wave generator 10 shown in FIG. 6 can be manufactured.

DESCRIPTION OF SYMBOLS 10 Capacitance type sound wave generator 11 fixed electrode 11a through hole 11b terminal 12 vibrator 13 vibrating electrode 14 connection member 15 support part 21 1st frame 22 2nd frame 23 fixing member 24 and 26 leaf spring 25 , 27 terminals 16 audio signal input means 31 bias generator 32 voltage converter 32a audio input terminal

41 base silicon layer 42 insulating layer 43 silicon active layer 44 silicon substrate 45 silicon substrate 46 thin film layer

51 diaphragm 52 fixed electrode

Claims (4)

A fixed electrode having a plate shape and having one or more through holes provided through the thickness;
Vibration having a plate shape or a film shape and disposed on one surface side of the fixed electrode so as to face the fixed electrode, at least a central portion of the fixed electrode being movable in a thickness direction Body,
Vibration having a plate shape or a film shape and disposed on the other surface side of the fixed electrode so as to face the fixed electrode, wherein at least a central portion of the fixed electrode is movable in a thickness direction An electrode,
A connecting member connecting the vibrating body and the vibrating electrode through at least one of the through holes of the fixed electrode so that the vibrating body and the vibrating electrode move in the same direction;
The fixed electrode such that the vibrating body is moved by electrostatic attraction between the fixed electrode and the vibrator, and the vibrating electrode is moved by electrostatic attraction between the fixed electrode and the vibrating electrode. A vibrator and an audio signal input means provided so as to be able to apply a voltage to the vibrating electrode;
An electrostatic capacitance type sound wave generator characterized by having.   The stationary electrode according to claim 1, further comprising: a support portion fixed to the peripheral edge portion of the fixed electrode and supporting at least one of the vibrating body and the vibrating electrode on the peripheral edge portion. Capacitance type sound generator.   The audio signal input means applies a positive or negative bias voltage to the fixed electrode, converts the audio signal into an analog signal based on the bias voltage, and generates an inverted signal in which the polarity of the analog signal is inverted. 3. The capacitance type according to claim 1, wherein the analog signal and the inversion signal are respectively applied to the vibrator and the vibrating electrode, or the vibrating electrode and the vibrator. Sound generator. A capacitive sound wave generator according to any one of claims 1 to 3, which is configured to be capable of generating a sound wave in an audible range by the vibration of the vibrator by the sound signal input means. Characteristic capacitive speaker.