JP2006148612A - Acoustic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve handling performance by improving moisture proof performance. <P>SOLUTION: An electrostatic speaker 10 is provided with a vibrating film 11, a pair of fixed pole layers 12, 12 laminated at positions sandwiching the vibrating film 11 from both surface sides, and a pair of porous layers 13, 13 provided on the respective fixed pole layers 12, 12 at the opposite side from the vibrating film 11. A water repelling layer 20 is provided outside the porous layer 13. The water-repelling layer 20 prevents water from infiltrating toward the vibrating film 11 side and inhibits the water from reaching the fixed pole layer 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an acoustic device, and more particularly to an acoustic device capable of improving moisture resistance.

Conventionally, an acoustic device such as an electrostatic speaker has been known, and this acoustic device has a sheet-like vibrating membrane, and a pair of conductive fixed electrode layers disposed on both sides of the vibrating membrane, And a porous layer that is laminated on the outside of each fixed electrode layer and maintains the fixed form of the fixed electrode layer. The fixed electrode layer and the porous layer are made of a material that allows air to pass through, such as a nonwoven fabric, and are configured to transmit reproduced sound caused by vibration of the vibrating membrane (see Patent Document 1).
JP-T-2002-513263

However, in such an acoustic device, if left in a place where the humidity is relatively high, there is an inconvenience that the capacitance decreases and the reproduced sound pressure decreases.
This is because the fiber bond of the nonwoven fabric is broken by containing moisture, and it becomes difficult to conduct electricity to the fixed electrode layer, the effective area of the electrode is reduced, or the fixed electrode layer is oxidized by contact with water, and the function as an electrode is achieved. It is presumed to be insufficient.
This causes inconveniences such as managing the humidity so as to be kept relatively low, and imposes a heavy burden on handling, and makes it impossible to avoid a decrease in sound pressure in a place where humidity management cannot be performed.

[Object of invention]
The present invention has been devised by paying attention to such inconveniences, and an object of the present invention is to provide an acoustic device capable of improving moisture resistance and improving handling.

In order to achieve the above object, the present invention provides an acoustic device including a vibrating membrane and a conductive fixed pole layer laminated so as to include a gap between the vibrating membrane.
A configuration in which a water repellent layer is provided on the side of the fixed pole layer opposite to the vibration film is employed.

In addition, the present invention provides a vibration film and a pair of conductive fixed electrodes that are disposed at positions sandwiching the vibration film from both sides and are laminated so as to include a gap portion between the vibration film and the vibration film. In the acoustic device including a layer and a porous layer provided on the opposite side of the vibrating membrane in each fixed pole layer,
A configuration in which a water repellent layer is provided on the porous layer side of the fixed electrode layer can also be adopted.

  In the present invention, a configuration is adopted in which the water repellent layer is provided on at least one surface of the porous layer and / or in the middle in the thickness direction.

The water repellent layer may be formed by applying a predetermined water repellent material.

  Further, a configuration in which a water catching layer is provided outside the water repellent layer, and the water catching layer absorbs water vapor and converts it into water molecules is also preferably adopted.

  According to the present invention, even when the humidity is relatively high, the water-repellent layer can suppress moisture and moisture in the air from reaching the fixed electrode layer, and can maintain the capacitance stably and reproduce the reproduced sound. It is possible to prevent the pressure from decreasing. Thereby, it is possible to improve the handleability, relax the restriction of the installation space, and spread it in various usage scenes such as stores and transportation facilities.

  Moreover, when a water repellent layer is provided in the thickness direction intermediate part of a porous layer, the said water repellent layer can be concealed from the outer side, and a secular change etc. can be avoided. On the other hand, when it is provided on the outer surface side of the porous layer, a water repellent layer can be easily formed on a generally distributed acoustic device, and the entire porous layer can be protected from moisture and the like to improve moisture resistance. Become.

  Furthermore, when the water repellent layer is formed by applying a water repellent material, the water repellent effect can be obtained easily and quickly by using, for example, a spray.

  In addition, when a water catching layer is provided outside the water repellent layer, water vapor absorbed by the water catching layer becomes water molecules, making it difficult for water vapor to reach the water repellent layer, and that water permeates through the water repellent layer. It can be avoided better.

  In this specification and claims, unless otherwise specified, “inner” is used as the side closer to the diaphragm, while “outer” is used as the opposite side.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a sectional view of the electrostatic speaker according to the present embodiment, and FIG. 2 shows an exploded view thereof. In these drawings, an electrostatic speaker 10 as an acoustic device includes a vibration film 11, a pair of fixed electrode layers 12 and 12 stacked at positions sandwiching the vibration film 11 from both sides, and each fixed electrode layer 12, 12 includes a pair of porous layers 13 and 13 provided on the opposite side of the vibrating membrane 11.

  The vibration film 11 includes a metal film 11A having conductivity such as aluminum and a pair of chargeable insulating films 11B and 11B laminated on both surfaces of the metal film 11A. A control electrode A for inputting an electrical signal corresponding to sound generated from the electrostatic speaker 10 is connected to the metal film 11A. The insulating film 11B is made of, for example, polypropylene resin, polymethylpentene, or cyclic olefin copolymer in addition to PET resin.

  The fixed pole layers 12 and 12 and the porous layers 13 and 13 have a vertically symmetrical structure in FIG. Accordingly, in the following description, the upper fixed pole layer 12 and the porous layer 13 in the figure will be described, and the lower layers 12 and 13 in the figure will be assigned the same reference numerals and description thereof will be omitted.

  The fixed electrode layer 12 is made of a non-woven fabric having conductivity. Specifically, the fixed electrode layer 12 is made by impregnating a non-woven fabric with a metal material such as aluminum or sputtering or evaporating a metal material on the inner surface. The said nonwoven fabric can be comprised using a cellulose, glass fiber, a mineral fiber, and a metal fiber, or can also be comprised by sintering a plastic or metal powder.

  The fixed pole layer 12 is formed in a shape in which a plurality of irregularities are continuous in a cross-sectional view. In other words, the fixed pole layer 12 is provided at predetermined intervals along the left-right direction, and is positioned between a plurality of recessed portions 12A formed to be recessed upward and adjacent recessed portions 12A, and PET. The shape includes a bonded portion 12B that is bonded to the vibration film 11 via an adhesive layer 16 such as a system. The recess portion 12 </ b> A forms a gap portion 17 between the vibration film 11 and the vibration film 11 can vibrate within the gap portion 17. The fixed electrode layer 12 is connected to a fixed electrode E for applying a predetermined bias voltage to the fixed electrode layer 12.

  The porous layer 13 is laminated on the fixed electrode layer 12 via a polyamide-based adhesive layer 18 and the intermediate layer 13A, the adhesive layer 13B, and the outer layer are sequentially laminated from the adhesive layer 18 toward the outside. It consists of layer 13C. 13 A of intermediate | middle layers are compression-molded so that the area | region corresponding to the said to-be-adhered part 12B may protrude. The intermediate layer 13 </ b> A and the outer layer 13 </ b> C are configured using a non-woven fabric, and give a fixed shape to the fixed electrode layer 12 while transmitting sound generated by vibration of the vibration film 11.

A water repellent layer 20 is provided on the outer surface of the outer layer 13 </ b> C in the porous layer 13. The water repellent layer 20 is made of a material that transmits sound from the vibration film 11 while preventing water from penetrating inward (vibration film 11 side).
Examples of the water repellent layer 20 include application of a water repellent material through spraying or the like. Examples of the water repellent material include polymer materials such as fluororesin and silicon resin.
Moreover, as the water repellent layer 20, a nonwoven fabric in which the water repellent material is bonded to the surface of each single fiber can be exemplified. The single fibers are those in which a fluororesin is bonded to the surface of each fiber in a raised state, and each fiber is a natural fiber such as wood fiber, cotton, wool, hemp, chemical fiber, semi-synthetic fiber, etc. Or, a combination of these may be used. The fluororesin used includes polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (PFEP), and ethylene-tetrafluoroethylene. Examples thereof include a copolymer (PETFE), an ethylene-chlorotrifluoroethylene copolymer (PECTFE), and polychlorotrifluoroethylene (PCTFE).
Furthermore, the water-repellent layer 20 may be formed by forming a fluororesin into a film having a porous structure having a large number of holes that allow air to pass therethrough.

  In the above configuration, a predetermined bias voltage is applied to the fixed electrode E and an electric signal is applied to the control electrode A via a predetermined control device (not shown), so that the vibration film 11 vibrates in the gap portion 17. To do. Due to this vibration, sound is generated, and the sound is transmitted through the fixed electrode layer 12, the porous layer 13, and the water repellent layer 20 and emitted.

  Next, in order to confirm the effect according to the present invention, the following examples are shown together with comparative examples.

[Example]
In the embodiment, the water repellent layer 20 is formed by applying a water repellent material containing perfluoroalkyl acrylate to the outer surface side of the porous layer 13 using the electrostatic speaker 10 shown in FIG. Formed.
The electrostatic speaker 10 was left to stand at 40 ° C. and a humidity of 90% for 24 hours, and then was subjected to moisture resistance leaving at room temperature for 24 hours.

[Comparative example]
In contrast to the example, an electrostatic speaker without the water repellent layer 20 was used, and other conditions were the same.

Capacitance was measured for each of the electrostatic speakers of the example and the comparative example. The timing for measuring the capacitance was in an unused state and after being left with no moisture. The results are shown in Table 2 and FIG.
In addition, acoustic characteristics were measured in an anechoic chamber for each of the electrostatic speakers of the example and the comparative example. The timing for measuring the acoustic characteristics was in an unused state and after being left with no moisture. The results are shown in FIGS.

As is clear from these charts, when compared with the unused state and after being left with no moisture, in the example, both the capacitance and the reproduction sound pressure are hardly changed, whereas in the comparative example, the capacitance and Both playback sound pressures are decreasing. Accordingly, it is understood that the structure of the example can avoid the decrease in the capacitance and the reproduction sound pressure even under the condition of high sound and high humidity as compared with the comparative example, and the moisture resistance performance is improved.
Note that conditions other than those described above, for example, even if the material of the metal film 11A is made of a metal other than aluminum, or the porous layer 13 is made of only one layer of the intermediate layer 13A, It is expected that equivalent results will be obtained.

Although the best configuration, method and the like for carrying out the present invention have been disclosed in the above description, the present invention is not limited to this.
That is, although the present invention has been particularly shown and described with respect to particular embodiments, it is to be understood that the invention has been shown to have the form described above without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of position, orientation, and other detailed configurations.
Therefore, the description limited to the shape disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description in the name of the member excluding a part or all of the limitation is included in the present invention.

  As long as the electrostatic speaker 10 can reproduce sound by the vibration film 11 and can exhibit the moisture resistance as described above, various design changes can be made. For example, the porous layer 13 may be omitted and the water-repellent layer 20 may be provided outside the fixed pole layer 12 with respect to the structure of the above embodiment, or one of the fixed pole layers 12 may be omitted. Further, the water repellent layer 20 may be provided between the layers 13 </ b> A to 13 </ b> C forming the porous layer 13, or between the porous layer 13 and the fixed electrode layer 12.

  Further, as shown in FIG. 6, a configuration in which a water capturing layer 22 is further provided outside the water repellent layer 20 is also conceivable. At this time, the water catching layer 22 is made of a material such as a porous material such as activated carbon or silica gel which can absorb water vapor and change the water vapor into water molecules therein. According to this, not only water vapor becomes difficult to touch the water repellent layer 20 directly, but also the water that has been trapped dries over time and the water repellent layer 20 is substantially restored to the initial state. It becomes possible to obtain a water repellent effect better.

  Furthermore, in the above embodiment, the acoustic apparatus is the electrostatic speaker 10, but an electrostatic microphone that measures a signal corresponding to the vibration of the vibration film 11 via the control electrode A may be used.

1 is a schematic cross-sectional view of an electrostatic speaker according to an embodiment. The exploded view of FIG. (A) is a diagram which shows the measurement result of the electrostatic capacitance of an Example, (B) is a diagram which shows the measurement result of the electrostatic capacitance of a comparative example. The diagram which shows the measurement result of the acoustic characteristic by an Example. The diagram which shows the measurement result of the acoustic characteristic by a comparative example. Sectional drawing similar to FIG. 1 of the electrostatic speaker which concerns on a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Electrostatic speaker (acoustic device), 11 ... Vibration membrane, 12 ... Fixed pole layer, 13 ... Porous layer, 17 ... Gap part, 20 ... Water-repellent layer, 22 ... Water catching layer

Claims (5)

In an acoustic device including a vibrating membrane and a conductive fixed pole layer laminated so as to include a gap between the vibrating membrane,
An acoustic device, wherein a water repellent layer is provided on a side of the fixed pole layer opposite to the vibration film. A vibration film, a pair of conductive fixed electrode layers disposed at positions sandwiching the vibration film from both sides, and laminated so as to include a gap between the vibration film, and each fixed electrode In the acoustic device including the porous layer provided on the opposite side of the vibrating membrane in the layer,
An acoustic device comprising a water repellent layer on the porous layer side of the fixed electrode layer.   The acoustic device according to claim 2, wherein the water-repellent layer is provided on at least one surface of the porous layer and / or an intermediate portion in the thickness direction.   4. The acoustic device according to claim 1, wherein the water repellent layer is formed by applying a predetermined water repellent material.   The acoustic device according to any one of claims 1 to 4, wherein a water catching layer is provided outside the water repellent layer, and the water catching layer absorbs water vapor and converts it into water molecules.

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