JP5227891B2 - Condenser headphone unit - Google Patents

Description

  The present invention relates to a condenser headphone unit, and more particularly to a technique for reducing the occurrence of an unequal electric field on a fixed pole surface and suppressing the occurrence of spark discharge.

  The capacitor headphone includes a capacitor headphone unit as an electrostatic acoustic transducer in which a diaphragm and a fixed electrode plate are disposed to face each other with a spacer interposed therebetween. In the condenser headphone unit, the diaphragm is driven by electrostatic attraction and repulsion generated between the diaphragm and the fixed plate. A sound pressure of about 100 dBSPL can be obtained when the voltage applied to the fixed plate is about 100 Vrms (effective value).

  Usually, a metal plate having a large number of sound holes (ventilation holes) is used for the fixed electrode plate, but it may be composed of a circuit board (copper-clad laminate).

  In a condenser headphone unit, in order to maintain the sound output level stability, it is important to keep the surface of the fixed plate flat and keep the distance from the diaphragm uniform. Since a high voltage is applied to the electrode plate, a spark discharge is generated particularly at the edge portion which is the opening end portion of the sound hole, and the diaphragm may be burned by the heat.

  This burnout phenomenon tends to occur more frequently when a diaphragm formed by forming a metal vapor deposition film on one side of a resin film is used as the diaphragm.

  Considering this point, in the invention described in Patent Document 1, the diaphragm is a polymer film having a thickness of about 1.2 μm, such as PET (polyethylene terephthalate) or PPS (polyphenylene sulfide), and at least one of them is used. A conductive film made of a surfactant is formed on this surface (the surface facing the fixed electrode plate), and an insulating film is further formed on the conductive film.

  According to this, although the spark discharge induced on the diaphragm side can be reduced, the spark discharge still occurs due to the concentration of the electric field at the edge portion which is the opening end portion of the sound hole on the fixed plate side.

  Even if an insulating film is formed on the surface of the fixed electrode plate, it is not possible to prevent electric field concentration at the edge portion that is the opening end of the sound hole. In addition, since the insulating film on the diaphragm side is about 0.1 μm thick, in a situation where condensation occurs in a high humidity environment, a polarization voltage (about 400 V) is generated between the conductive film of the diaphragm and the fixed electrode. Leakage current occurs, which causes noise.

JP 2006-41567 A

  Accordingly, an object of the present invention is to reduce an unequal electric field on a fixed pole surface in a capacitor headphone unit, to make it difficult for spark discharge to occur, and to limit discharge current even in a situation where spark discharge is likely to occur. This is to prevent spark discharge.

  In order to solve the above-described problems, the present invention provides a diaphragm having a predetermined tension on a support ring, and a fixed member having a large number of holes for allowing sound to pass through the spacer member to face the diaphragm. In the capacitor headphone unit including the electrode plate, the fixed electrode plate includes at least an opening end portion of the hole, and short fibers are electrostatically implanted from the inner surface of the hole to the surface side facing the diaphragm. A pile layer is formed.

  In the present invention, it is preferable that a surfactant is applied to the pile layer. Moreover, you may form the said pile layer with an electroconductive fiber. In any case, an insulating film may be provided on the pile layer.

  According to the present invention, a pile layer in which short fibers such as nylon and rayon are electrostatically flocked from the inner surface of the hole to the surface facing the diaphragm so as to cover the opening end of the sound hole of the fixed electrode plate. By forming, R (roundness) due to short fibers is attached to the opening end of the sound hole, and the electric field is less likely to concentrate.

  In addition, since the pile layer has an appropriate electrical resistance, the pile layer including the R portion acts as a fixed pole surface, and the pile layer acts as a current limiting resistor even in a situation where spark discharge is likely to occur. Generation of spark discharge is suppressed. Moreover, by forming an insulating film on the pile layer, the occurrence of spark discharge can be suppressed more effectively.

The typical sectional view showing the capacitor headphone unit concerning the embodiment of the present invention. The front view which shows the fixed electrode plate in the said capacitor | condenser headphone unit. The expanded sectional view which shows the principal part of the said capacitor headphone unit.

  Next, an embodiment of the present invention will be described with reference to FIG. 1 to FIG. 3, but this embodiment does not limit the present invention.

  As shown in FIG. 1, the condenser headphone unit 1 is provided with a diaphragm 10 and a fixed electrode plate 20 facing each other. The diaphragm 10 has a predetermined tension by a metal support ring 11. In a stretched state, the fixed electrode plate 20 is opposed to the fixed electrode plate 20 through an electrically insulating spacer ring 30.

  Although not shown in detail, the diaphragm 10 is made of a polymer film having a thickness of about 1.2 μm such as PET (polyethylene terephthalate) or PPS (polyphenylene sulfide), as described in Patent Document 1, A diaphragm in which a conductive film made of a surfactant and an insulating film made of an insulating solvent are formed in a laminated form is preferably used, but a diaphragm in which a metal vapor deposition film is formed on a thin film substrate made of a resin film is used. May be.

  In this embodiment, the fixed electrode plate 20 is composed of a disk-shaped printed circuit board 21 as shown in FIG. Referring also to FIG. 3, the printed circuit board 21 is a single-sided copper-clad laminate, and a fixed electrode portion 210 made of copper foil is formed at the central portion facing the diaphragm 10. The fixed electrode portion 210 has a large number of sound holes (holes through which sound passes) 211.

  In this embodiment, the peripheral electrode portion 220 is formed in an annular shape around the fixed electrode portion 210 via the electrical insulating region 230. As an example, the peripheral electrode unit 220 may be connected to, for example, a support ring of the diaphragm 10 through a conduction unit (not shown) and used as an extraction electrode of the diaphragm 10.

  According to the present invention, as shown in FIG. 3, the fixed electrode plate 20 includes an inner surface 211 a of the sound hole 211 and a substantially right-angled edge portion 211 b that is an opening end of the sound hole 211 and extends from the surface of the fixed electrode part 210. A pile layer 40 is formed.

  The pile layer 40 is formed by electrostatically flocking the short fibers 41 through a conductive adhesive (not shown). As an example, nylon fiber 1.7 decix (length 0.5 mm) is preferably used for the short fiber 41.

  According to electrostatic flocking, the short fibers 41 are planted in a substantially upright state with respect to the flocked surface, and therefore, the flocked flocked portion 211b of the sound hole 211 has a flocking as shown in FIG. R (roundness) is attached by the short fibers 41, and the electric field is difficult to concentrate.

  In addition, since more short fibers 41 adhere to the portion where the electric field strength is increased (the edge portion 211b) during electrostatic flocking according to the electric field strength, the electric field is less likely to be concentrated on the edge portion 211b. .

After electrostatic flocking, the electrical resistance value of the pile layer 40 made of the short fibers 41 is preferably adjusted. For example, the surface resistance of the pile layer 40 is adjusted to 10 ⁸ to 10 ⁹ Ω by applying a surfactant-based antistatic agent “Colcoat 200 (trade name)” manufactured by Colcoat.

In addition, as the short fiber 41, for example, a conductive fiber “Dolly Maron” (resistance value 10 ² to 10 ⁷ Ω) manufactured by Nissen may be used from the beginning.

  Thereafter, in order to make it difficult for the discharge current that causes spark discharge to flow, for example, “Fluorobarrier FP-1054 (trade name)” manufactured by ING Co., Ltd. is applied to the pile layer 40. An insulating film having a thickness of 1 μm or less is formed.

  In the capacitor headphone unit 1 according to the above embodiment, the fixed electrode plate 20 is disposed only on one side of the diaphragm 10, but the push-pull type capacitor headphone in which the fixed electrode plate 20 is disposed on both sides of the diaphragm 10. Units are also included in the present invention.

DESCRIPTION OF SYMBOLS 10 Diaphragm 11 Support ring 20 Fixed pole plate 21 Printed circuit board 210 Fixed electrode part 211 Sound hole 211a Inner surface 211b Opening edge part (edge part)
30 Spacer ring 40 Pile layer 41 Short fiber (pile)

Claims (4)

In a condenser headphone unit comprising: a diaphragm stretched on a support ring with a predetermined tension; and a fixed plate having a large number of holes for allowing sound to pass through the spacer member and facing the diaphragm. ,
The fixed electrode plate includes at least an opening end portion of the hole, and a pile layer in which short fibers are electrostatically implanted is formed from an inner surface of the hole to a surface facing the diaphragm. Condenser headphone unit.   The capacitor headphone unit according to claim 1, wherein the pile layer is coated with a surfactant for preventing static electricity.   2. The condenser headphone unit according to claim 1, wherein the pile layer is formed of a conductive fiber.   The capacitor headphone unit according to any one of claims 1 to 3, wherein the pile layer is provided with an insulating film.

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