JP5760878B2 - Electrostatic acoustic transducer - Google Patents

Description

  The present invention relates to an electrostatic electroacoustic transducer.

An electrostatic loudspeaker disclosed in Patent Document 1 includes two planar electrodes (electrodes) facing each other with a gap therebetween, and a film-like diaphragm having conductivity disposed between the two planar electrodes. When a predetermined bias voltage is applied to the diaphragm and the voltage applied to the planar electrode is changed, the electrostatic force that acts on the diaphragm changes, and thereby the diaphragm Is displaced. If the applied voltage is changed according to the input acoustic signal, the diaphragm repeats displacement accordingly, and sound waves according to the acoustic signal are generated from both surfaces of the diaphragm. Then, the generated sound wave is radiated to the outside through the through hole formed in the planar electrode.
In Patent Document 2, a first speaker element configured by sandwiching a diaphragm (vibrating body) between a pair of fixed electrodes and one fixed electrode of the first speaker element are arranged to face each other. A speaker device is disclosed that includes a second speaker element configured with a diaphragm sandwiched between the fixed electrode. A voltage having a polarity opposite to that applied to the diaphragm of the first speaker element is applied to the diaphragm of the second speaker element. Further, the fixed electrode positioned between the diaphragm of the first speaker element and the diaphragm of the second speaker element is driven with a polarity opposite to that of the drive signal supplied to the fixed electrode facing the fixed electrode. A signal is supplied. In this speaker device, a large sound pressure can be obtained because the diaphragm of the first speaker element and the diaphragm of the second speaker element vibrate in the same phase.

JP 2007-318554 A Japanese Patent Laid-Open No. 06-209499

In the configurations described in Patent Document 1 and Patent Document 2, sound waves generated from the diaphragm facing the electrode are radiated to the outside of the electrostatic speaker through a through hole provided in the electrode. Therefore, when the aperture ratio of the electrode is small, compared with the case where the aperture ratio of the electrode is large, the sound wave generated from the diaphragm facing the planar electrode passes through the through hole and goes to the outside of the electrostatic speaker. There is a problem that the sound pressure of the sound wave emitted to the outside of the electrostatic speaker becomes small because the sound is less likely to be emitted.
The configuration of the electrostatic speaker can also be used as the configuration of the electrostatic microphone. In this case, sound (sound) is converted into an acoustic signal (electrical signal) by sound waves generated outside passing through a through-hole provided in the electrode and vibrating the diaphragm. Therefore, when the aperture ratio of the electrode is small, compared to the case where the aperture ratio of the electrode is large, an externally generated sound wave is less likely to pass through the through hole, and the acoustic signal converted by the electrostatic microphone is small. There is a problem that the sensitivity of the electrostatic microphone is lowered.

  In order to solve the above-described problems, the present invention provides an electrostatic electroacoustic transducer that, when used as an electrostatic speaker, easily emits sound generated by a vibrating body to the outside. When used as a microphone, an object is to facilitate conversion of sound generated externally into an acoustic signal.

In order to solve the above-described problem, the present invention provides a first vibrating body having conductivity, a pair of electrodes having a through-hole and facing each other across the first vibrating body, and having conductivity, A pair of second vibrators opposed to the first vibrator with the pair of electrodes interposed therebetween, wherein the pair of second vibrators are electrically connected to a ground of a drive circuit that supplies a signal to the pair of electrodes. a vibrating body, respectively between the pair of electrodes and the first vibrator, the pair of on one surface side of the first vibrator of the pair of electrodes on the surface side of the first vibrator Between one of the second vibrators and between the other of the pair of electrodes on the back side of the first vibrator and the other of the pair of second vibrators on the back side of the first vibrator. located between the elastic, insulating and and an elastic member having air permeability, wherein the first vibrator, the pair Electrodes and the elastic member to provide an electrostatic type electro-acoustic transducer, characterized in that disposed in the closed space formed by fixing the edges of the pair of second vibrator each other.

In the present invention, as viewed from the first vibrating body, a second elastic member having elasticity, insulation and air permeability, a second electrode having a through hole, and a third elastic member having elasticity, insulation and air permeability And a vibrating portion laminated in the order of the third vibrating body having conductivity, and the vibrating portion is located inside the elastic member between each of the first vibrating body and the pair of electrodes. One or more layers may be stacked and the number of the vibrating parts on the front surface side of the first vibrating body may be the same as the number of the vibrating parts on the back surface side of the first vibrating body. .

  According to the present invention, in an electrostatic electroacoustic transducer, when used as an electrostatic speaker, sound generated by a vibrating body is easily radiated to the outside, and is used as an electrostatic microphone. In this case, sound generated outside is easily converted into an acoustic signal.

1 is an external view of an electrostatic speaker according to a first embodiment. FIG. 2 is a cross-sectional view of the electrostatic speaker of FIG. 1 taken along line AA. It is an external view of an electrode. It is the figure which showed the electrical structure of the electrostatic speaker. It is a figure for demonstrating operation | movement of an electrostatic speaker. It is the figure which showed the electrical structure of the electrostatic speaker which concerns on 2nd Embodiment. It is a figure for demonstrating operation | movement of the electrostatic speaker which concerns on 2nd Embodiment. It is the figure which showed the electrical structure of the electrostatic speaker which concerns on 3rd Embodiment. It is an external view of the electrostatic speaker which concerns on a modification. It is the figure which expanded a part of upper surface of the electrostatic speaker which concerns on a modification. It is the figure which showed the front and side of the clip which concerns on a modification. It is the figure which showed the state which pinched | interposed the electrostatic speaker with the clip which concerns on a modification. It is an external view of the electrostatic speaker which concerns on a modification. It is the figure which showed the electrical structure of the electrostatic microphone which concerns on a modification.

[First Embodiment]
In the present embodiment, an example in which an electrostatic electroacoustic transducer is applied as an electrostatic speaker that converts an acoustic signal (electric signal) into sound (sound) will be described. FIG. 1 is an external view of the electrostatic speaker 1 according to the first embodiment, and FIG. 2 is a cross-sectional view of the electrostatic speaker 1 of FIG. FIG. 3 is an external view of the electrode 31. In these drawings, directions are shown by orthogonal X-axis, Y-axis, and Z-axis. When the electrostatic speaker 1 is viewed from the front, the left-right direction is the X-axis direction, the depth direction is the Y-axis direction, The vertical direction is the Z-axis direction. Also, in the figure, “•” in “◯” means an arrow heading from the back of the drawing to the front. Further, in the figure, “x” in “◯” means an arrow pointing backward from the front of the drawing. Note that the “front” here indicates the direction of the surface for the sake of convenience, and does not indicate the direction of the front when the electrostatic speaker 1 is arranged. The electrostatic loudspeaker 1 may be arranged in any direction as necessary. In addition, the dimensions of each component in the drawing are different from the actual dimensions so that the shape of the component can be easily understood.

(Configuration of each part of the electrostatic speaker 1)
The configuration of each part constituting the electrostatic speaker 1 will be described.
The electrostatic speaker 1 includes a vibrating body 11, elastic members 21U and 21L, electrodes 31U and 31L, elastic members 22U and 22L, vibrating bodies 12U and 12L, and surface members 40U and 40L. In the present embodiment, the elastic members 21U and 21L have the same configuration, and the electrodes 31U and 31L have the same configuration. The elastic members 22U and 22L have the same configuration, and the vibrating bodies 12U and 12L have the same configuration. Moreover, the structure of the surface members 40U and 40L is the same. For this reason, when there is no particular need to distinguish between the members, the description of the symbols “U” and “L” is omitted.

The vibrating body 11 and the vibrating body 12 are based on a synthetic resin film having insulating properties and flexibility such as PET (polyethylene terephthalate) or PP (polypropylene), and a conductive metal is used for the film. The conductive film is formed by vapor deposition. The vibrating body 11 and the vibrating body 12 have a rectangular shape when viewed from the Z-axis direction, and the dimensions in the X-axis direction and the dimension in the Y-axis direction are the same. Moreover, it is preferable that the dimension of the vibrating body 11 and the vibrating body 12 in the Z-axis direction is about 12 μm. In the following description, the surface in the Z-axis positive direction of the vibrating body 11 is referred to as the front surface, and the surface in the Z-axis negative direction is referred to as the back surface.

  The elastic member 21 and the elastic member 22 are non-woven fabrics, and can pass air and sound (sound) without conducting electricity. The elastic member 21 and the elastic member 22 have elasticity, and are deformed when a force is applied from the outside, and return to the original shape when the force applied from the outside is removed. The elastic member 21 and the elastic member 22 have a rectangular shape when viewed from the Z-axis direction. The dimension in the X-axis direction is the same as the dimension in the X-axis direction of the vibrating body 11, and the dimension in the Y-axis direction is This is the same as the dimension of the vibrating body 11 in the Y-axis direction.

  The electrode 31 is so-called punching metal, and has a higher rigidity (higher Young's modulus) than the vibrating body 11 and the vibrating body 12, and a plurality of through holes 311 penetrating from the front surface to the back surface of the conductive metal plate are formed. Has been. The electrode 31 has a rectangular shape when viewed from the Z-axis direction, the dimension in the X-axis direction is the same as the dimension in the X-axis direction of the vibrating body 11, and the dimension in the Y-axis direction is Y of the vibrating body 11. It is the same as the axial dimension. The number of through holes 311 formed in the electrode 31 is not limited to the number shown in FIG.

  The surface member 40 is a woven cloth, has insulating properties and flexibility, and allows passage of air and sound. The surface member 40 has a rectangular shape when viewed from the Z-axis direction. The dimension in the X-axis direction is the same as the dimension in the X-axis direction of the vibrating body 11, and the dimension in the Y-axis direction is the same as that of the vibrating body 11. It is the same as the dimension in the Y-axis direction. Further, the surface member 40 is preferably one that allows easy passage of sound and air as compared with the electrode 31.

(Structure of electrostatic speaker 1)
Next, the structure of the electrostatic speaker 1 will be described.
The vibrating body 11 is disposed between the lower surface of the elastic member 21U and the upper surface of the elastic member 21L. The vibrating body 11 is coated with an adhesive with a width of several millimeters inward from the X-axis direction edge and the Y-axis direction edge, and is fixed to the elastic member 21U and the elastic member 21L, and the adhesive is applied. The inside of the portion is not fixed to the elastic member 21U and the elastic member 21L.

  The electrode 31U is coated with an adhesive with a width of several millimeters inward from the X-axis direction edge and the Y-axis direction edge, and is fixed to the upper surface of the elastic member 21U. The elastic member 21U is not fixed. The electrode 31L is fixed to the lower surface of the elastic member 21L by applying an adhesive with a width of several mm inward from the X-axis direction edge and the Y-axis direction edge. The elastic member 21L is not fixed.

  The elastic member 22U is coated with an adhesive with a width of several millimeters inward from the edge in the X-axis direction and the edge in the Y-axis direction, and is fixed to the upper surface of the electrode 31U. The electrode 31U is not fixed to the electrode 31U. The elastic member 22L is fixed to the lower surface of the electrode 31L by applying an adhesive with a width of several millimeters inwardly from the X-axis direction edge and the Y-axis direction edge, and the inner side of the portion where the adhesive is applied The electrode 31U is not fixed to the electrode 31U.

  The vibrating body 12U is coated with an adhesive with a width of several millimeters inward from an edge in the X-axis direction and an edge in the Y-axis direction, and is fixed to the upper surface of the elastic member 22U. Is not fixed to the elastic member 22U. The vibrating body 12L is coated with an adhesive with a width of several millimeters inward from the X-axis direction edge and the Y-axis direction edge, and is fixed to the lower surface of the elastic member 22L. Is not fixed to the elastic member 22L. The surface of the vibrating body 12U on which the conductive film is formed is in contact with the elastic member 22U, and the surface of the vibrating body 12L on which the conductive film is formed is in contact with the elastic member 22L.

  The surface member 40U is coated with an adhesive with a width of several millimeters inward from the edge in the X-axis direction and the edge in the Y-axis direction, and is fixed to the upper surface of the vibrating body 12U. Is not fixed to the vibrating body 12U. The surface member 40L is coated with an adhesive with a width of several millimeters inward from the X-axis direction edge and the Y-axis direction edge and fixed to the lower surface of the vibrating body 12L. Is not fixed to the vibrating body 12L.

(Electrical configuration of the electrostatic speaker 1)
Next, the electrical configuration of the electrostatic speaker 1 will be described.
FIG. 4 is a diagram showing an electrical configuration of the electrostatic speaker 1.
A driving unit 100 is connected to the electrostatic speaker 1. The drive unit 100 includes a transformer 110, an amplifier 120, a bias power supply 131, and a bias power supply 132.
An acoustic signal (electric signal) representing sound is input to the amplifier 120 from the outside. The amplifier 120 is an amplification circuit that amplifies an input acoustic signal and outputs the amplified acoustic signal. The amplifier 120 includes terminals TA1 and TA2 that output acoustic signals. Terminal TA1 is connected to terminal T1 on the input side of transformer 110 via resistor R1. The terminal TA2 is connected to the other terminal T2 on the input side of the transformer 110 via the resistor R2.

  The output-side terminal T4 of the transformer 110 is connected to the electrode 31U, and the other terminal T5 on the output side of the transformer 110 is connected to the electrode 31L. One end of the bias power supply 131 is connected to the ground GND, which is the reference potential of the drive unit 100, and the other end of the bias power supply 131 is connected to the terminal T3 at the midpoint of the transformer 110 via the resistor R3. That is, the bias power supply 131 applies a bias voltage (for example, 350 V) to the terminal T3 at the midpoint of the transformer 110. One end of the bias power source 132 is connected to the ground GND, which is the reference potential of the driving unit 100, and the other end of the bias power source 132 is connected to the conductive film of the vibrator 11 via the resistor R4. In other words, the bias power supply 132 applies a bias voltage (for example, 700 V) with respect to the potential of the ground GND to the conductive film of the vibrator 11. The conductive film of the vibrating body 12U and the conductive film of the vibrating body 12L are electrically connected and connected to the ground GND. In this configuration, the potential of the vibrating body 11 is higher than the potentials of the electrodes 31U and 31L, and the potentials of the electrodes 31U and 31L are higher than the potentials of the vibrating bodies 12U and 12L, respectively. That is, the electric potential of the vibrating body 11 arranged on the innermost side of the electrostatic speaker 1 is the highest, and the electric potential of each electrode and each vibrating body becomes lower as it is arranged on the outer side (the front surface side or the back surface side). The potentials of the vibrators 12U and 12L arranged in the above become the potential of the ground GND.

(Operation of electrostatic speaker 1)
When an acoustic signal is input to the amplifier 120, the input acoustic signal is amplified and supplied to the input side of the transformer 110. The acoustic signal boosted by the transformer 110 is supplied to the electrode 31U and the electrode 31L, whereby the electrostatic speaker 1 operates as a push-pull electrostatic speaker. Note that the polarity of the voltage applied to the electrode 31U is an inversion of the polarity of the voltage applied to the electrode 31L, and the absolute value of the voltage applied to the electrode 31U is the absolute value of the voltage applied to the electrode 31L. The same value as

For example, when the acoustic signal boosted by the transformer 110 is supplied to the electrode 31U and the electrode 31L, the voltage applied to the electrode 31U increases from 350V to 400V, and the voltage applied to the electrode 31L increases from 350V to 300V. The operation of the electrostatic loudspeaker 1 in the case of a decrease will be described with reference to FIG.
In this case, since the potential difference between the vibrating body 12U and the electrode 31U is increased, the electrostatic attractive force between the vibrating body 12U and the electrode 31U is increased, and the vibrating body 12U is attracted toward the electrode 31U and is indicated by the arrow F1. Displace in the direction. Further, the potential difference between the electrode 31U and the vibrating body 11 is reduced and the electrostatic attractive force between the electrode 31U and the vibrating body 11 is weakened, while the potential difference between the electrode 31L and the vibrating body 11 is increased and the electrode is increased. Since the electrostatic attractive force between 31L and the vibrating body 11 is increased, the vibrating body 11 is attracted toward the electrode 31L having the increased electrostatic attractive force and displaced in the direction of the arrow F2 in the same direction as the arrow F1. In addition, since the potential difference between the electrode 31L and the vibrating body 12L is reduced, the electrostatic attractive force between the vibrating body 12L and the electrode 31L is weakened, and the vibrating body 12L moves away from the electrode 31L and has an arrow in the same direction as the arrow F1. Displacement in the direction of F3.

Next, for example, when the acoustic signal boosted by the transformer 110 is supplied to the electrode 31U and the electrode 31L, the voltage applied to the electrode 31U is reduced from 350V to 300V, and the voltage applied to the electrode 31L is reduced. The operation of the electrostatic speaker 1 when it is increased from 350 V to 400 V will be described with reference to FIG.
In this case, since the potential difference between the vibrating body 12U and the electrode 31U becomes small, the electrostatic attractive force between the vibrating body 12U and the electrode 31U is weakened, and the vibrating body 12U moves away from the electrode 31U in the direction of the arrow F4. To do. Further, the potential difference between the electrode 31U and the vibrating body 11 is increased and the electrostatic attractive force between the electrode 31U and the vibrating body 11 is increased, while the potential difference between the electrode 31L and the vibrating body 11 is decreased and the electrode is increased. Since the electrostatic attractive force between 31L and the vibrating body 11 is weakened, the vibrating body 11 is attracted toward the electrode 31U having an increased electrostatic attractive force and displaced in the direction of the arrow F5 in the same direction as the arrow F4. Further, since the potential difference between the electrode 31L and the vibrating body 12L is increased, the electrostatic attractive force between the vibrating body 12L and the electrode 31L is increased, and the vibrating body 12L is attracted toward the electrode 31L and is the same as the arrow F4. It is displaced in the direction of the direction arrow F6.

  As described above, the vibration body 11, the vibration body 12 </ b> U, and the vibration body 12 </ b> L change in the displacement direction according to the acoustic signal to generate vibration, and the sound wave according to the vibration state (frequency, amplitude, phase) Generated from the body. Since the vibrating body 11, the vibrating body 12U, and the vibrating body 12L are displaced in the same direction, sound waves having the same phase are generated from the vibrating bodies. That is, the sound waves generated from the vibrating bodies do not cancel each other, and the sound waves generated from the vibrating bodies are added and increased. Further, the vibrating body 12U and the vibrating body 12L are arranged outside the electrode 31 so that the generated sound wave is efficiently radiated to the outside of the electrostatic speaker 1 without being blocked by the electrode 31. Can do. Therefore, the electrostatic speaker 1 is located outside the electrostatic speaker 1 as compared with the conventional electrostatic speakers disclosed in Patent Document 1 and Patent Document 2 in which electrodes are arranged outside the vibrating body. Sound is easily radiated, and the sound pressure outside the electrostatic speaker 1 increases.

  The electrostatic speaker 1 of the present embodiment has a result that the sound pressure is increased by about 3 dB as compared with a conventional electrostatic speaker in which a vibrating body is not disposed outside the electrodes. Further, the frequency band in which the sound pressure increases is about 200 Hz to 10000 Hz, which is useful because it belongs to a frequency band in which a person can feel as sound. Note that the degree to which the sound pressure increases may be adjusted by varying the voltage applied to each electrode or by varying the number of vibrators and electrodes.

  In the present embodiment, the vibrating body 11 and the vibrating body 12 are formed so as to be relatively less rigid than the electrode 31. Therefore, when the potential difference between the electrode 31 and the vibrating body 12 changes, the vibrating body 12 is displaced rather than the electrode 31 being displaced. Further, when the potential difference between the electrode 31 and the vibrating body 11 changes, the vibrating body 11 is displaced instead of the electrode 31 being displaced. In addition, since the air located inside the elastic member 21 and the elastic member 22 can move through the through-hole 311 formed in the electrode 31, the vibrating body 11 and the vibrating body 12 are free from being subjected to air resistance. Can be displaced.

Further, according to the present embodiment, the vibrating body 11 and the electrode 31 (hereinafter referred to as a conductive portion) through which a current flows are covered with the vibrating body 12 connected to the ground GND. In this configuration, the electrostatic speaker 1 is less likely to be touched by the human body, and thus the possibility of electric current flowing from the conductive portion to the human body is reduced.
In addition, according to the present embodiment, since the vibrating body 11 and the vibrating body 12 are fixed only on a part of the region in contact with the adjacent member, the entire region is in contact with the adjacent member. It is easy to displace compared to the case where it is fixed.

[Second Embodiment]
In the first embodiment, sound waves are generated by vibrating the vibrating body 11, the vibrating body 12U, and the vibrating body 12L according to the voltages applied to the electrode 31U and the electrode 31L. Is not limited to this. FIG. 6 is a diagram showing an electrical configuration of the electrostatic speaker 1a according to the second embodiment of the present invention. In FIG. 6, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

(Structure of electrostatic speaker 1a)
In addition to the configuration of the electrostatic speaker 1, the electrostatic speaker 1a includes vibrating bodies 13U and 13L, elastic members 23U, 23L, 24U and 24L, and electrodes 32U and 32L. The configurations of the vibrating bodies 13U and 13L are the same as the configurations of the vibrating bodies 11, 12U, and 12L described above. The configurations of the elastic members 23U, 23L, 24U, 24L are the same as the configurations of the elastic members 21U, 21L, 22U, 22L described above. The configuration of the electrodes 32U and 32L is the same as the configuration of the electrodes 31U and 31L described above. The electrostatic speaker 1a includes a surface member 40L, a vibrating body 13L, an elastic member 24L, an electrode 32L, an elastic member 23L, a vibrating body 12L, an elastic member 22L, an electrode 31L, an elastic member 21L, a vibrating body 11, an elastic member 21U, and an electrode. 31U, elastic member 22U, vibrating body 12U, elastic member 23U, electrode 32U, elastic member 24U, vibrating body 13U, and surface member 40U are laminated in this order. That is, the electrostatic speaker 1 a has the configuration of the electrostatic speaker 1, and is located outside the vibrating body 12 </ b> U on the surface side of the vibrating body 11 and outside the vibrating body 12 </ b> L on the back side of the vibrating body 11. The elastic member 23, the electrode 32, the elastic member 24, and the vibrating body 13 are stacked. The laminated elastic member 23, electrode 32, elastic member 24, and vibrating body 13 are collectively referred to as a vibrating portion 50. The electrostatic loudspeaker 1a includes one unit if the number of vibrating units 50 arranged on the front side of the vibrating body 11 and the number of vibrating units 50 arranged on the back side of the vibrating unit 11 are the same. The above vibration parts 50 may be laminated and disposed. Each of the laminated members is coated with an adhesive with a width of several millimeters inward from the X-axis direction edge and the Y-axis direction edge, and is fixed between adjacent members, and the adhesive is applied. The inside of the part is not fixed.

(Electrical configuration of the electrostatic speaker 1a)
Next, the electrical configuration of the electrostatic speaker 1a will be described.
A drive unit 100a is connected to the electrostatic speaker 1a. The drive unit 100a includes a transformer 111, an amplifier 120, a bias power source 131, a bias power source 132, a bias power source 133, and a bias power source 134.

The transformer 111 has two windings T6 and T7 on the secondary side.
One terminal T61 of the winding T6 is connected to the electrode 31U, and the other terminal T62 is connected to the electrode 31L. One end of a bias power supply 131 is connected to a terminal T63 at the middle point of the winding T6 via a resistor R3, and a predetermined bias voltage (for example, 600 V) is applied. The other end of the bias power supply 131 is connected to the ground GND, which is the reference potential of the drive unit 100a.
Further, one terminal T71 of the winding T7 is connected to the electrode 32U, and the other terminal T72 is connected to the electrode 32L. One end of a bias power supply 134 is connected to a middle terminal T73 of the winding T7 through a resistor R6, and a predetermined bias voltage (for example, 200 V) is applied. Note that the other end of the bias power supply 134 is connected to the ground GND.

One end of the bias power source 132 is connected to the conductive film of the vibrating body 11, and the other end of the bias power source 132 is connected to the ground GND via the resistor R4. The bias power supply 132 applies a bias voltage (for example, 800 V) based on the potential of the ground GND to the conductive film of the vibrator 11. One end of the bias power supply 133 is connected to the conductive film of the vibrator 12U and the conductive film of the vibrator 12L via the resistor R5, and the other end of the bias power supply 133 is connected to the ground GND. The bias power supply 133 applies a bias voltage (for example, 400 V) based on the potential of the ground GND to the conductive film of the vibrator 12U and the conductive film of the vibrator 12L. The conductive film of the vibrating body 13U and the conductive film of the vibrating body 13L are electrically connected and are connected to the ground GND.
In this configuration, the potential of the vibrating body 11 is higher than the potentials of the electrodes 31U and 31L, the potential of the electrodes 31U and 31L is higher than the potential of the vibrating bodies 12U and 12L, and the potentials of the vibrating bodies 12U and 12L are The potential of the electrodes 32U and 32L is higher than the potential of the vibrating bodies 13U and 13L. That is, the potential of the vibrating body 11 arranged on the innermost side of the electrostatic speaker 1a is the highest, and the potential of each electrode and each vibrating body becomes lower as it is arranged on the outer side, and the vibrating body 13U arranged on the outermost side. , 13L becomes the potential of the ground GND.

(Operation of electrostatic speaker 1a)
When an acoustic signal is input to the amplifier 120, the input acoustic signal is amplified and supplied to the input side of the transformer 111. Then, the acoustic signal boosted by the transformer 111 is supplied to the electrodes 31U and 31L and the electrodes 32U and 32L, whereby the electrostatic speaker 1a operates as a push-pull electrostatic speaker.

For example, when the acoustic signal boosted by the transformer 111 is supplied to the electrodes 31U and 31L and the electrodes 32U and 32L, the voltage applied to the electrode 32U increases from 200V to 225V, and the voltage applied to the electrode 32L. 7 shows the operation of the electrostatic speaker 1a when the voltage applied to the electrode 31U increases from 600V to 625V and the voltage applied to the electrode 31L decreases from 600V to 575V. A description will be given using (a).
In this case, when the electrostatic attractive force between the electrode 32U and the vibrating body 13U is increased, the vibrating body 13U is displaced in the direction of the arrow F7. Further, the electrostatic attractive force between the electrode 32U and the vibrating body 12U is weakened, and the electrostatic attractive force between the electrode 31U and the vibrating body 12U is increased, so that the vibrating body 12U is in the direction of the arrow F8 in the same direction as the arrow F7. It is displaced to. Further, the electrostatic attractive force between the electrode 31U and the vibrating body 11 is weakened, and the electrostatic attractive force between the electrode 31L and the vibrating body 11 is increased, so that the vibrating body 11 is in the direction indicated by the arrow F9 in the same direction as the arrow F7. It is displaced to. Further, the electrostatic attractive force between the electrode 31L and the vibrating body 12L is weakened, and the electrostatic attractive force between the electrode 32L and the vibrating body 12L is increased, so that the vibrating body 12L is in the direction of the arrow F10 in the same direction as the arrow F7. It is displaced to. Further, the electrostatic attraction between the electrode 32L and the vibrating body 13L is weakened, so that the vibrating body 13L is displaced in the direction of the arrow F11 in the same direction as the arrow F7.

Next, for example, the acoustic signal boosted by the transformer 111 is supplied to the electrodes 31U and 31L and the electrodes 32U and 32L, whereby the voltage applied to the electrode 32U is reduced from 200V to 175V and applied to the electrode 32L. When the voltage applied to the electrode 31U increases from 200V to 225V, the voltage applied to the electrode 31U decreases from 600V to 575V, and the voltage applied to the electrode 31L increases from 600V to 625V, the electrostatic speaker 1a Will be described with reference to FIG.
In this case, the electrostatic attraction between the electrode 32U and the vibrating body 13U is weakened, whereby the vibrating body 13U is displaced in the direction of the arrow F12. Further, the electrostatic attractive force between the electrode 32U and the vibrating body 12U is increased, and the electrostatic attractive force between the electrode 31U and the vibrating body 12U is weakened, so that the vibrating body 12U is in the direction indicated by the arrow F13 in the same direction as the arrow F12. It is displaced to. Further, the electrostatic attractive force between the electrode 31U and the vibrating body 11 is increased, and the electrostatic attractive force between the electrode 31L and the vibrating body 11 is weakened, so that the vibrating body 11 is in the direction indicated by the arrow F14 in the same direction as the arrow F12. It is displaced to. Further, the electrostatic attractive force between the electrode 31L and the vibrating body 12L is increased, and the electrostatic attractive force between the electrode 32L and the vibrating body 12L is weakened, so that the vibrating body 12L is in the direction of the arrow F15 in the same direction as the arrow F12. It is displaced to. Further, as the electrostatic attractive force between the electrode 32L and the vibrating body 13L increases, the vibrating body 13L is displaced in the direction of the arrow F16 in the same direction as the arrow F12.
As described above, the vibration body 11, the vibration bodies 12U and 12L, and the vibration bodies 13U and 13L change according to the acoustic signal to generate vibration, and sound waves according to the vibration state (frequency, amplitude, and phase) are respectively vibrated. Generated from the body.

  According to the second embodiment, the electrostatic speaker 1 a has a larger number of vibrating bodies and electrodes than the configuration of the electrostatic speaker 1. Therefore, the electrostatic speaker 1 a can generate sound waves from vibration bodies provided more than the electrostatic speaker 1.

[Third Embodiment]
FIG. 8 is a diagram showing an electrical configuration of the electrostatic speaker 1b according to the third embodiment of the present invention. The electrostatic speaker 1b has the same configuration as the electrostatic speaker 1a, but the voltage applied to the vibrating body is different from the voltage applied to the electrode. Therefore, in FIG. 8, the same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, the electrostatic speaker 1 b has the configuration of the electrostatic speaker 1, and the vibration on the outer side of the vibrating body 12 </ b> U on the surface side of the vibrating body 11 and on the back side of the vibrating body 11. The vibrating part 50 is disposed outside the body 12L. In addition, the electrostatic speaker 1b has one or more if the number of the vibration parts 50 arranged on the front surface side of the vibration body 11 and the number of vibration parts arranged on the back surface side of the vibration body 11 are the same. The vibrating portions 50 may be stacked and arranged.

  In the present embodiment, one end of a bias power supply 131 is connected to a middle terminal T63 of the winding T6 via a resistor R3, and a predetermined bias voltage (for example, 350 V) is applied. In addition, one end of a bias power source 134 is connected to a middle terminal T73 of the winding T7 through a resistor R6, and a predetermined bias voltage (for example, −350 V) is applied.

One end of the bias power source 132 is connected to the conductive film of the vibrating body 11, and the other end of the bias power source 132 is connected to the ground GND via the resistor R4. The bias power supply 132 applies a bias voltage (for example, 700 V) based on the potential of the ground GND to the conductive film of the vibrator 11.
One end of the bias power supply 133 is connected to the conductive film of the vibrator 13U and the conductive film of the vibrator 13L via the resistor R5, and the other end of the bias power supply 133 is connected to the ground GND. The bias power supply 133 applies a predetermined bias voltage (for example, −700 V) to the conductive film of the vibrating body 13U and the conductive film of the vibrating body 13L. The conductive film of the vibrating body 12U and the conductive film of the vibrating body 12L are electrically connected and connected to the ground GND.

  Also in this configuration, the potential of the vibrating body 11 is higher than the potentials of the electrodes 31U and 31L, the potential of the electrodes 31U and 31L is higher than the potential of the vibrating bodies 12U and 12L, and the potentials of the vibrating bodies 12U and 12L are The potential of the electrodes 32U and 32L is higher than the potential of the vibrating bodies 13U and 13L. The electrostatic speaker 1b operates as a push-pull electrostatic speaker when a voltage having a polarity corresponding to an acoustic signal is applied to the electrode 31 and the electrode 32.

[Modification]
The above-described embodiment is merely an example of the implementation of the present invention. The present invention can also be implemented in a mode in which the following modifications are applied to the above-described embodiments. In addition, the modification shown below may be implemented combining each suitably as needed.

(Modification 1)
In the embodiment described above, the dimension in the X-axis direction and the dimension in the Y-axis direction of each member are the same, but the dimension may be different for each member. For example, in the vibrating body constituting the electrostatic speaker 1, the X-axis direction dimension and the Y-axis direction dimension of the outermost vibrating body 12 may be longer than other members. When the dimension in the X-axis direction and the dimension in the Y-axis direction of the vibrating body 12 are longer than those of other members, the edge of the vibrating body 12U and the edge of the vibrating body 12L are fixed to each other, and the vibrating body 12U and the vibrating body 12L The vibrating body 11, the elastic members 21, 22 and the electrode 31 may be arranged in a space sealed between them. Further, by connecting the vibrating body 12 to the ground GND, which is a reference potential, each member through which current flows is sealed and grounded, so that the possibility of electric shock to the human body can be reduced. Further, the vibrating body 12U and the vibrating body 12L have the same direction of displacement according to the acoustic signal. Therefore, the air located in the sealed space between the vibrating body 12U and the vibrating body 12L is not compressed or extended.
For example, the dimension of the surface member 40 in the X-axis direction and the dimension in the Y-axis direction may be longer than those of other members. As described above, when the dimension in the X-axis direction and the dimension in the Y-axis direction of the surface member 40 are longer than those of the other members, the edge of the surface member 40U and the edge of the surface member 40L are fixed to each other. You may make it a vibrating body, an elastic member, and an electrode be located in the sealed space between 40L. According to this configuration, since the portion through which the current flows is covered with the surface member 40 having insulation properties, it is possible to reduce the possibility that the human body will receive an electric shock.

(Modification 2)
In the above-described embodiment, each member is bonded to other members by applying an adhesive to the edge portion, but the portion to which the adhesive is applied is not limited to the edge portion of the member. For example, an adhesive may be applied to each member in a lattice shape and bonded to other members. In addition, each member may be adhered to another member by regularly providing each member with a region where the adhesive is applied in a dot shape, such as a matrix. Further, the method of preventing the members from being displaced in the electrostatic speaker 1 is not limited to the method of fixing with an adhesive, and for example, a method of fixing the members with a double-sided tape may be used.

(Modification 3)
The vibrating body is not limited to one in which a conductive metal is vapor-deposited on one surface of the film, and may be one in which a conductive metal is vapor-deposited on both surfaces of the film. Moreover, the vibrating body is not limited to PET or PP, and may be one obtained by vapor-depositing a conductive metal on another synthetic resin film.

(Modification 4)
The elastic member 21 and the elastic member 22 are not limited to non-woven fabrics, and may be any member that does not conduct electricity and allows air and sound to pass therethrough. A woven fabric, a woven fabric, or a synthetic resin made into a sponge.

(Modification 5)
The shape of each member constituting the electrostatic speaker 1 is not limited to a rectangular shape when viewed from the Z-axis direction, and may be other shapes such as a polygon, a circle, and an ellipse.

(Modification 6)
The surface member may be any member that can pass air and sound. For example, the surface member may be one in which heat is applied to the batting and compressed, or one in which a synthetic resin is spongy. The surface member may have an image such as a character, a picture, or a photograph formed on the surface. The electrostatic speaker configured as described above can emit sound waves related to the image printed on the surface of the surface member from the surface of the surface member.
Further, the electrostatic speaker is not limited to the configuration provided with the surface member, and may not include the surface member.

(Modification 7)
The electrode is not limited to punching metal. For example, the electrode has a configuration in which a conductive film is formed on a substrate in which an insulating material (for example, glass or phenolic resin) is formed in a plate shape, and a through-hole penetrating from the front surface to the back surface is formed. Also good. The electrode may have a structure in which a metal film is deposited on a synthetic resin film having insulation and flexibility such as PET or PP, and a through-hole penetrating from the front surface to the back surface is formed. In addition, the electrode may have a configuration in which a cloth woven with conductive yarn is formed into a rectangular shape. In the case where the electrode has flexibility, the electrode has higher rigidity (larger Young's modulus) than the vibrating body so that the electrode is not displaced by the electrostatic force acting between the electrode and the vibrating body. Just do it.

(Modification 8)
When an acoustic signal is not supplied to each electrode, the electrostatic speaker is configured such that the potential difference between the adjacent vibrating body and the electrode is constant in any case, but is limited to this configuration. Is not to be done. For example, the bias power supply may apply the bias voltage so that the potential difference between some adjacent vibrators and electrodes is different from the potential difference between other adjacent vibrators and electrodes.

(Modification 9)
In the second embodiment and the third embodiment, in addition to the configuration of the electrostatic speaker 1, the outer side of the vibrating body 12U on the surface side of the vibrating body 11 and the vibrating body 12L on the back side of the vibrating body 11. One vibrating part was disposed on the outside. However, the configuration of the electrostatic speaker is not limited to this as long as the number of vibrating portions on the front surface side of the vibrating body 11 and the number of vibrating portions on the back surface side of the vibrating body 11 are the same. . In other words, one or more vibration units may be stacked and disposed outside the vibrating body 12U on the surface side of the vibrating body 11 and outside the vibrating body 12L on the back surface side of the vibrating body 11.

(Modification 10)
Each member constituting the electrostatic speaker may be provided with a notch for connection with the drive unit. FIG. 9 is an external view of an electrostatic speaker 1c according to a modification. The electrostatic speaker 1c has the same configuration as the electrostatic speaker 1, but the shape of each member is different. This modification will be described only with respect to differences from the electrostatic speaker 1.

  The electrostatic speaker 1c includes a surface member 40Lc, a vibrating body 12Lc, an elastic member 22Lc, an electrode 31Lc, an elastic member 21Lc, a vibrating body 11c, an elastic member 21Uc, an electrode 31Uc, an elastic member 22Uc, a vibrating body 12Uc, and a surface member 40Uc. It is laminated and configured. The surface member 40Lc and the vibrating body 12Lc have a rectangular shape when viewed from the Z-axis direction, and are not provided with a notch. On the other hand, the elastic member 22Lc, the electrode 31Lc, the elastic member 21Lc, the vibrating body 11c, the elastic member 21Uc, the electrode 31Uc, the elastic member 22Uc, the vibrating body 12Uc, and the surface member 40Uc have a certain width in the depth direction by cutting a part of the rectangle. Recessed notch is provided.

The position of the notch of the electrode 31Lc in the left-right direction is the same position as the notch of the elastic member 22Lc. Further, the length in the left-right direction of the notch of the electrode 31Lc is the same as the length in the left-right direction of the notch of the elastic member 22Lc.
The length in the left-right direction of the notch of the vibrating body 11c is longer than the length in the left-right direction of the notch of the electrode 31Lc. The position of the cutout of the elastic member 21Lc in the left-right direction is the same position as the cutout of the vibrating body 11c. Further, the length of the cutout of the elastic member 21Lc in the left-right direction is the same as the length of the cutout of the vibrating body 11c in the left-right direction.
Further, the length of the notch of the electrode 31Uc in the left-right direction is longer than the length of the notch of the vibrating body 11c in the left-right direction. The position of the cutout of the elastic member 21Uc in the left-right direction is the same position as the cutout of the electrode 31Uc. The length of the cutout of the elastic member 21Uc in the left-right direction is the same as the length of the cutout of the electrode 31Uc in the left-right direction.
The length in the left-right direction of the notch of the vibrating body 12Uc is longer than the length in the left-right direction of the notch of the electrode 31Uc. The position of the cutout of the elastic member 22Uc in the left-right direction is the same position as the cutout of the vibrating body 12Uc. Further, the length of the cutout of the elastic member 22Uc in the left-right direction is the same as the length of the cutout of the vibrating body 12Uc in the left-right direction.
Further, the length of the cutout of the surface member 40Uc in the left-right direction is longer than the length of the cutout of the vibrating body 12Uc in the left-right direction.

FIG. 10 is an enlarged view of a part of the upper surface of the electrostatic speaker 1c.
The cutout of the electrode 31Lc and the cutout of the elastic member 22Lc are shorter in the left-right direction than the cutout of the vibrating body 11c and the elastic member 21Lc, and the cutout region of the vibrating body 11c and the elastic member 21Lc is viewed from above. Located in.
Further, the cutout of the vibrating body 11c and the cutout of the elastic member 21Lc are shorter in the left-right direction than the cutout of the electrode 31Uc and the elastic member 21Uc, and when viewed from above, the cutout of the electrode 31Uc and the elastic member 21Uc Located in the area.
Further, the cutout of the electrode 31Uc and the cutout of the elastic member 21Uc are shorter in the left-right direction than the cutout of the vibrating body 12Uc and the elastic member 22Uc, and when viewed from above, the cutout of the vibrating body 12Uc and the elastic member 22Uc. Is located in the area.
The cutouts of the vibrating body 12Uc and the elastic member 22Uc are shorter in the left-right direction than the cutout of the surface member 40Uc, and are located in the cutout region of the surface member 40Uc when viewed from above.

The electrostatic speaker 1 c is connected to the drive unit 100 by a clip 200.
FIG. 11A is a view showing the front surface of the clip 200, and FIG. 11B is a view showing the side surface of the clip 200. The clip 200 has rectangular and plate-shaped electrodes 201 to 205 and a spring 210. The clip 200 has a plate-shaped plastic plate portion 220A to which the electrodes 201 to 205 are fixed, and a plate-shaped plastic plate portion 220B facing the plate portion 220A. The electrode 201 is connected to the ground GND of the drive unit 100 via a lead wire (not shown). The electrode 202 is connected to a terminal T5 on the output side of the transformer 110 via a lead wire (not shown). The electrode 203 is connected to a bias power source 132 via a lead wire (not shown). The electrode 204 is connected to a terminal T4 on the output side of the transformer 110 via a lead wire (not shown). The electrode 205 is connected to the ground GND of the drive unit 100 via a lead wire (not shown).

FIG. 12 is a diagram showing a state in which the electrostatic speaker 1 c is sandwiched between the clips 200.
By sandwiching the notch portion of the electrostatic speaker 1c with the clip 200, the electrode 201 and the vibrating body 12Lc, the electrode 202 and the electrode 31Lc, the electrode 203 and the vibrating body 11c, the electrode 204 and the electrode 31Uc, and the electrode 205 and the vibrating body 12Uc are obtained. Each will come into contact. The acoustic signal output from the terminal T5 is supplied to the electrode 31Lc via the electrode 202, and the acoustic signal output from the terminal T4 is supplied to the electrode 31Uc via the electrode 204. Further, a bias voltage supplied from the bias power source 132 is applied to the vibrating body 11 c via the electrode 203. The vibrating body 12Uc is connected to the ground GND via the electrode 205, and the vibrating body 12Lc is connected to the ground GND via the electrode 201.

  In this modification, simply by sandwiching the electrostatic speaker 1c with the clip 200, the electrostatic speaker 1c and the drive unit 100 can be connected, and a voltage corresponding to an acoustic signal can be applied to each electrode. Further, if the clip 200 is detached from the electrostatic speaker 1c, the electrostatic speaker 1c and the driving unit 100 can be separated, so that the electrostatic speaker 1c can be easily carried.

(Modification 11)
The electrostatic speaker and the drive unit are connected by sandwiching the electrostatic speaker with a clip having an electrode, but the configuration for connecting the electrostatic speaker and the drive unit is not limited to this.
FIG. 13 is an external view of an electrostatic speaker 1d according to a modification.
The electrostatic speaker 1d includes a surface member 40Ld, a vibrating body 12Ld, an elastic member 22Ld, an electrode 31Ld, an elastic member 21Ld, a vibrating body 11d, an elastic member 21Ud, an electrode 31Ud, an elastic member 22Ud, a vibrating body 12Ud, and a surface member 40Ud. It is laminated and configured. The electrode 31d is a plate-like member having conductivity, has higher rigidity than the vibrating body 11d and the vibrating body 12d (high Young's modulus), and lower rigidity than electrodes 201d to 205d described later (small Young's modulus). ). Further, the electrode 31d is formed with a plurality of through holes penetrating from the front surface to the back surface. The vibrating body 12Ld and the vibrating body 12Ud are provided with one notch that is partly removed and recessed with a constant width in the depth direction. The electrode 31Ld, the vibrating body 11d, and the electrode 31Ud have two notches. The notches are provided at regular intervals. Note that the surface member 40Ld, the elastic member 22Ld, the elastic member 21Ld, the elastic member 21Ud, the elastic member 22Ud, and the surface member 40Ud are not electrically conductive and are not connected to the drive unit, and thus are notched. It may or may not be provided.

  The electrostatic speaker 1 d is connected to the drive unit 100 by a clip 200. As illustrated in FIG. 13, the clip 200 is provided with electrodes 201 d to 205 d having a needle shape. The electrode 201d is connected to the ground GND of the drive unit 100 via a lead wire (not shown). The electrode 202d is connected to a terminal T5 on the output side of the transformer 110 via a lead wire (not shown). The electrode 203d is connected to the bias power source 132 through a lead wire (not shown). The electrode 204d is connected to a terminal T4 on the output side of the transformer 110 via a lead wire (not shown). The electrode 205d is connected to the ground GND of the drive unit 100 via a lead wire (not shown).

  In the electrostatic speaker 1d, the positions of the notches provided in the vibrating body 12Ld, the electrode 31Ld, the vibrating body 11d, the electrode 31Ud, and the vibrating body 12Ud are different from each other. More specifically, although there is a vibrating body 12Ld at the point P1, the electrode 31Ld, the vibrating body 11d, the electrode 31Ud, and the vibrating body 12Ud are absent due to the notch. Further, although the electrode 31Ld is present at the point P2, the vibrating body 12Ld, the vibrating body 11d, the electrode 31Ud, and the vibrating body 12Ud are absent due to the notch. Further, at the point P3, although the vibrating body 11d is present, the vibrating body 12Ld, the electrode 31Ld, the electrode 31Ud, and the vibrating body 12Ud are absent due to the notch. In addition, although the electrode 31Ud is present at the point P4, the vibrating body 12Ld, the electrode 31Ld, the vibrating body 11d, and the vibrating body 12Ud are absent due to the notch. Further, although there is a vibrating body 12Ud at the point P5, the vibrating body 12Ld, the electrode 31Ld, the vibrating body 11d, and the electrode 31Ud are absent due to the notch. By sandwiching the cut-out portion of the electrostatic speaker 1d thus configured with the clip 200, the electrode 201d is stuck at the point P1 shown in FIG. 13, the electrode 202d is stuck at the point P2, and the electrode 203d is placed at the point P3. The electrode 204d is pierced at the point P4, and the electrode 205d is pierced at the point P5.

In this case, the electrode 201d contacts only the vibrating body 12Ld among the members having conductivity, and does not contact other members having conductivity. For this reason, only the vibrating body 12Ld is connected to the ground GND via the electrode 201d. Further, the electrode 202d contacts only the electrode 31Ld among the conductive members, and does not contact other conductive members. For this reason, only the electrode 31Ld is supplied with the acoustic signal output from the terminal T5 via the electrode 202d. The electrode 203d contacts only the vibrating body 11d among the conductive members, and does not contact other conductive members. For this reason, only the vibrating body 11d is applied with the bias voltage supplied from the bias power supply 132 via the electrode 203d. The electrode 204d contacts only the electrode 31Ud among the conductive members, and does not contact other conductive members. For this reason, only the electrode 31Ud is supplied with the acoustic signal output from the terminal T4 via the electrode 204d. In addition, the electrode 205d contacts only the vibrating body 12Ud among the members having conductivity, and does not contact other members having conductivity. For this reason, only the vibrating body 12Ud is connected to the ground GND via the electrode 205d.
Thus, also in this modification, the acoustic signal from the drive unit 100 can be supplied to the electrostatic speaker 1d simply by sandwiching the electrostatic speaker 1d with the clip 200.

(Modification 12)
In the embodiment and the modification described above, an example in which the electrostatic electroacoustic transducer is applied to an electrostatic speaker that converts an acoustic signal (electric signal) into sound (sound) has been described. The electroacoustic transducer may be applied to an electrostatic microphone that converts sound (sound) into an acoustic signal (electric signal). FIG. 14 is a diagram showing an electrical configuration of an electrostatic microphone 1M according to this modification. In the configuration shown in FIG. 14, the electrostatic microphone 1M has the same configuration as the electrostatic speaker 1 shown in FIG. The drive unit 100M is connected to the electrostatic microphone 1M. The drive unit 100M has the same configuration as the drive unit 100 of FIG. 4 described above, but the transformation ratio of the transformer 110 and the resistance values of the resistors R1 to R4 may be adjusted as appropriate and are input to and output from the amplifier 120. The direction of the acoustic signal is opposite to that in FIG.

  When a sound is generated outside, the vibrating bodies 12U, 12L, and 11 are vibrated as shown in FIGS. 5A and 5B, and the vibration body and the electrode are in response to the vibration. Since the distance between them changes, the capacitance between the vibrating body and the electrode changes. Since the electrode 31U and the electrode 31L are connected to the bias power supply 131 via the resistor R3, it is assumed that the electric charge remains constant even if the capacitance changes.

Here, the operation of the electrostatic microphone 1M when the vibrating bodies 12U, 12L, and 11 vibrate as shown in FIG. 5A will be described.
First, when the distance between the vibrating body 12U and the electrode 31U is shortened, the capacitance between the vibrating body 12U and the electrode 31U is increased, and the distance between the vibrating body 11 and the electrode 31U is increased. Thereby, the electrostatic capacitance between the vibrating body 11 and the electrode 31U becomes small. Here, since the vibrating body 12U and the vibrating body 11 are connected to the ground GND, the potential difference between the vibrating body 12U and the electrode 31U is reduced, and the potential difference between the vibrating body 11 and the electrode 31U is reduced. So that the potential of the electrode 31U changes.
Similarly, when the distance between the vibrating body 11 and the electrode 31L is shortened, the capacitance between the vibrating body 11 and the electrode 31L is increased, and the distance between the vibrating body 12L and the electrode 31L is increased. As a result, the capacitance between the vibrating body 12L and the electrode 31L is reduced. Here, since the vibrating body 12L and the vibrating body 11 are connected to the ground GND, the potential difference between the vibrating body 11L and the electrode 31L is reduced, and the potential difference between the vibrating body 12L and the electrode 31L is reduced. So that the potential of the electrode 31L changes.

Next, the operation of the electrostatic microphone 1M when the vibrating bodies 12U, 12L, and 11 vibrate as shown in FIG. 5B will be described.
First, as the distance between the vibrating body 12U and the electrode 31U increases, the capacitance between the vibrating body 12U and the electrode 31U decreases, and the distance between the vibrating body 11 and the electrode 31U decreases. Thereby, the electrostatic capacitance between the vibrating body 11 and the electrode 31U increases. Here, since the vibrating body 12U and the vibrating body 11 are connected to the ground GND, the potential difference between the vibrating body 12U and the electrode 31U is increased, and the potential difference between the vibrating body 11 and the electrode 31U is increased. Therefore, the potential of the electrode 31U changes.
Similarly, by increasing the distance between the vibrating body 11 and the electrode 31L, the capacitance between the vibrating body 11 and the electrode 31L decreases, and the distance between the vibrating body 12L and the electrode 31L decreases. As a result, the capacitance between the vibrating body 12L and the electrode 31L increases. Here, since the vibrating body 12L and the vibrating body 11 are connected to the ground GND, the potential difference between the vibrating body 11 and the electrode 31L is increased, and the potential difference between the electrode 31L and the vibrating body 12L is increased. The potential of the electrode 31L changes so that becomes smaller.

  As described above, as a result of the operation of the electrostatic microphone 1M, a change in the potential of the electrode 31U and the electrode 31L is a voltage output proportional to the displacement of vibration, that is, an acoustic signal via the terminal T4 and the terminal T5. 110 will be supplied. Then, the transformer 110 transforms this acoustic signal and inputs it to the amplifier 120. The amplifier 120 amplifies this acoustic signal and outputs it to a speaker or a computer (not shown).

  Thus, in the electrostatic microphone 1M, the sound generated outside vibrates the vibrating bodies 12U and 12L directly without being blocked by the electrodes 31U and 31L. Therefore, in the electrostatic microphone 1M, the vibrating bodies 12U and 12L are more likely to vibrate as compared with the configuration in which the electrodes are disposed outside the vibrating body, so that sound generated outside is converted into an acoustic signal. It becomes easy.

  In the modification 12, the electrostatic microphone 1M supplies an acoustic signal to the transformer 110 of the driving unit 100M. However, the electrostatic microphone 1M may supply an acoustic signal other than the transformer 110. For example, when the impedance of the transformer 110 is low, the frequency characteristic at a low frequency may deteriorate due to the influence of the load capacity of the electrostatic microphone 1M. In such a case, the electrostatic microphone 1M may suppress a decrease in frequency characteristics at a low frequency by supplying an acoustic signal to the amplifier 120 having a higher impedance than the transformer 110.

DESCRIPTION OF SYMBOLS 1 ... Electrostatic speaker (electrostatic electroacoustic transducer), 11 ... Vibration body, 21 ... Elastic member, 31 ... Electrode, 311 ... Through-hole, 22 ... Elastic member, 12 ... Vibration body, 40 ... Surface member DESCRIPTION OF SYMBOLS 50 ... Vibration part, 100 ... Drive part, 110 ... Transformer, 120 ... Amplifier, 131 ... Bias power supply, 132 ... Bias power supply, 1M ... Electrostatic microphone (electrostatic electroacoustic transducer), 100M ... Drive Part

Claims (2)

A first vibrating body having conductivity;
A pair of electrodes having through-holes and facing each other with the first vibrating body interposed therebetween;
A pair of second vibrating bodies having conductivity and facing the first vibrating body with the pair of electrodes interposed therebetween, and electrically connected to a ground of a drive circuit that supplies a signal to the pair of electrodes A pair of connected second vibrators;
One of the pair of electrodes on the surface side of the first vibrating body and the pair of second vibrating bodies on the surface side of the first vibrating body, respectively, between the first vibrating body and the pair of electrodes. Between the other of the pair of electrodes on the back side of the first vibrating body and the other of the pair of second vibrating bodies on the back side of the first vibrating body. An elastic member having elasticity, insulation and breathability ,
The first vibrating body, the pair of electrodes, and the elastic member are disposed in a sealed space formed by fixing edges of the pair of second vibrating bodies to each other.
An electrostatic electroacoustic transducer characterized by As viewed from the first vibrating body, the second elastic member having elasticity, insulation and breathability, the second electrode having a through hole, the third elastic member having elasticity, insulation and breathability, and conductivity. Having a vibrating section laminated in the order of the third vibrating body having,
One or more of the vibration parts are disposed inside the elastic member between the first vibrating body and the pair of electrodes, respectively, and are arranged in layers.
2. The electrostatic device according to claim 1, wherein the number of the vibration parts on the front surface side of the first vibration body is the same as the number of the vibration parts on the back surface side of the first vibration body. Type electroacoustic transducer.

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