JP4248467B2 - Narrow directivity condenser microphone - Google Patents

Description

  The present invention relates to a narrow directional condenser microphone that can suppress the generation of noise by making it difficult for hum noise and high-frequency current to enter.

  In a conventional narrow directional condenser microphone, a unidirectional microphone having a front acoustic terminal and a rear acoustic terminal is used, one end of an acoustic tube is fitted to the front acoustic terminal, and the rear acoustic terminal is placed in a free sound field. By positioning it, narrow directivity can be obtained.

  However, in such a conventional example, the sound wave introduction port of the front acoustic terminal becomes the tip of the acoustic tube, and the distance between the front acoustic terminal and the rear acoustic terminal in the low range becomes long. When the sound source is near, the proximity effect that distorts the bass is increased.

For this reason, as described in Patent Document 1 below, a plurality of rear sound wave inlets leading to a free sound field are provided in an acoustic tube located in the vicinity of the rear acoustic terminal, and the outer peripheral surface of the microphone unit and the inner portion of the acoustic tube are provided. The applicant of the present invention has already proposed a narrow directional condenser microphone in which a gap for communicating the rear acoustic terminal and the front acoustic terminal is provided between the peripheral surface and the above-mentioned drawbacks are eliminated.
Japanese Patent No. 2562295

  By the way, in the case of the narrow directivity condenser microphone disclosed in Patent Document 1, since it is necessary to provide a gap for communicating the rear acoustic terminal and the front acoustic terminal, the electrical connection between the acoustic tube and the microphone unit is required. There is a possibility that the necessary electrostatic shielding effect cannot be ensured due to imperfect contact state.

  5 is a side view of an external appearance example on the acoustic tube side incorporating a conventional microphone unit, FIG. 6 is a longitudinal sectional view of FIG. 5, and FIG. 7 is an enlarged view of a circular surrounding portion in FIG. FIG. 8 is an explanatory diagram in a state where the acoustic tube and the microphone unit are separated from each other.

  According to these figures, the inner peripheral surface 2 near the base end of the acoustic tube 1 having a substantially cylindrical shape with an appropriate length and having the acoustic resistance hole 1a has an outer diameter slightly smaller than the inner diameter. A stepped portion 3 is formed to support the cylindrical microphone unit 5 via the peripheral edge portion of the front acoustic terminal 6, and the rear acoustic wave introduction of the acoustic tube 1 is performed under the state of being supported by the stepped portion 3. A microphone unit 5 is accommodated in a base end portion 4 near the mouth 8 with a gap s interposed between the microphone unit 5 and the inner peripheral surface 2.

  Moreover, the microphone unit 5 in the acoustic tube 1 has an adhesive 9 supplied between the peripheral edge portion of the rear acoustic terminal 7 and the inner peripheral surface 2 so as to block the gap s as is apparent from FIG. The position is fixed to the acoustic tube 1 side via

  However, the acoustic tube 1 and the microphone unit 5 in the illustrated example are barely electrically connected between the step portion 3 in the acoustic tube 1 and the peripheral portion of the front acoustic terminal 6 of the microphone unit 1. Since it is in an extremely unstable state where a shielding effect can be obtained, there is a disadvantage that hum noise or high-frequency current enters and noise is easily generated.

  An object of the present invention is to provide a narrow directional condenser microphone capable of effectively suppressing the generation of noise by making it difficult to enter hum noise and high-frequency current in view of the above-described problems of the prior art.

  The present invention has been made in order to achieve the above object, and is an acoustic device that accommodates a microphone unit having a front acoustic terminal and a rear acoustic terminal with a gap interposed between the microphone unit and an inner peripheral surface thereof. In the narrow directivity condenser microphone having at least a tube, the microphone unit has a gap in the gap with respect to a step portion formed by expanding an inner diameter of a portion located on the proximal end side of the acoustic tube. The most important feature is that the front acoustic terminal is supported and fixed on the acoustic tube side together with the conductive interposing material covering the peripheral surface portion on the front acoustic terminal side.

  The conductive interposing material in the present invention is formed of an elastic metal material having a bottomed cylindrical shape with a taper whose diameter is slightly reduced toward the bottom facing the front acoustic terminal. Is preferred. Further, the rear acoustic terminal side of the microphone unit can be fixed to a corresponding portion on the inner peripheral surface side of the acoustic tube including the gap via an adhesive.

  According to the first aspect of the present invention, the microphone unit can be reliably fixed in position by supporting the front acoustic terminal side with the stepped portion in the acoustic tube together with the conductive interposing material filling the gap. Therefore, it is possible to suppress the hum noise and high frequency current from entering and to exhibit stable quality and performance with less noise.

  According to the second aspect of the present invention, since the conductive interstitial material made of a bottomed cylindrical elastic metal material can be easily disposed so as to fill the corresponding portion of the gap in the acoustic tube, the microphone The position of the unit and the acoustic tube can be fixed under a state where the unit and the acoustic tube are more reliably electrically connected.

  Furthermore, according to the invention which concerns on Claim 3, the said back acoustic terminal side in a microphone unit can be reliably fixed to the acoustic tube side via an adhesive agent.

  1 is a side view of an external appearance example on the acoustic tube side according to the present invention, FIG. 2 is a longitudinal sectional view of FIG. 1, FIG. 3 is an enlarged view of a circular surrounding portion in FIG. 2, and FIG. Explanatory drawing in the state which mutually separated the acoustic tube, the microphone unit, and the conductive interposing material is shown.

  According to these drawings, the narrow directional condenser microphone according to the present invention is provided between the unidirectional microphone unit 11 and the inner peripheral surface 26 of the microphone unit 11 as shown in FIG. The acoustic tube 21 is housed with a gap s interposed therebetween, and the conductive interposing material 31 disposed between the two through the gap.

  Among these, the microphone unit 1 is provided with a front acoustic terminal 12 on one side surface and a rear acoustic terminal 13 on the other side surface, and the whole is electrically conductive such as aluminum having a thin, substantially cylindrical shape. It is formed as a capacitor type housed in a case made of a metal material.

  The acoustic tube 21 having a substantially cylindrical shape is formed by using a conductive metal tube material such as an aluminum tube material having an appropriate length and a diameter determined by the relationship with the microphone unit 11, and is close to the distal end portion 22. A plurality of acoustic resistance holes 23 to which an acoustic resistance material (not shown) is affixed are disposed on the peripheral surface. Reference numeral 29 in the figure denotes a female thread portion for screwing and coupling to a grip side (not shown).

  Further, the base end portion 24 side of the acoustic tube 21 is formed with a step portion 25 formed at the boundary by making the inner diameter slightly larger than the inner diameter of other portions including the distal end portion 22. Yes. In this case, the inner diameter of the acoustic tube 21 on the base end portion 24 side is formed to be slightly larger than the outer diameter of the microphone unit 11, and when the microphone unit 11 is stored, the outer circumferential surface 14 and the acoustic tube 21 are acoustically separated. A gap s of an appropriate size can be secured between the inner peripheral surface 26 of the tube 21.

  For this reason, the microphone unit 11 is accommodated in the base end portion 24 in a state where the front acoustic terminal 12 side is supported with respect to the step portion 25 formed on the inner peripheral surface 26 of the acoustic tube 21. In addition, a rear acoustic wave introduction port 27 is formed on the proximal end 24 side of the acoustic tube 21 in the vicinity of a portion where the rear acoustic terminal 13 is located when the microphone unit 11 is housed. The sound resistance material which does not do is stuck.

  On the other hand, the conductive intercalating material 31 has a shape that can cover the peripheral surface portion (excluding the rear acoustic terminal 13 side) of the microphone unit 11 on the front acoustic terminal 12 side, for example, the front acoustic terminal 12 side as in the illustrated example. The peripheral wall 33 is formed of an elastic metal material having a bottomed cylindrical shape with a taper that is slightly reduced in diameter toward the bottom 32 facing the surface. In this case, as the elastic metal material, for example, a stainless steel wire or a brass wire, which is rich in conductivity and resilience, can be preferably used. 31 can be formed. Note that the conductive intercalation material 31 may be any material as long as it is formed in a substantially bowl shape that can cover the peripheral surface portion including the front acoustic terminal 12 in the microphone unit 11 with shape restoration. In addition to the structure, for example, an emboss structure can be added.

  The microphone unit 11, the acoustic tube 21, and the conductive interposing material 31 having the above-described configuration are assembled as follows. That is, as shown in FIG. 4, the front acoustic terminal 12 side of the microphone unit 11 faces the opening 34 side of the conductive intervention material 31, and the front acoustic terminal 12 is connected to the conductive intervention material 31. It is sent to the contact position with the bottom 32.

  After combining the microphone unit 11 and the conductive interposing material 31 in this way, the microphone unit 11 is placed in the base end portion 24 with the bottom 32 of the conductive interposing material 31 facing the base end opening 28 of the acoustic tube 21. Send it back together.

  In this case, since the inner diameter where the base end portion 24 of the acoustic tube 21 is located is slightly larger than the outer diameter of the microphone unit 11, a gap s is secured between the two. .

  Since the gap s can be used as a housing space for the peripheral wall portion 33 that is a corresponding portion of the conductive interposing material 31 that covers the microphone unit 11, the conductive interposing material 31 can be smoothly returned to the microphone unit 11. It can be fed into the base end 24.

  At this time, the conductive interposing material 31 covering the microphone unit 11 is stably abutted and supported together with the front acoustic terminal 12 side on the stepped portion 25 in the base end portion 24 of the acoustic tube 21 via the bottom portion 32. It will be.

  Further, the peripheral wall 33 side of the conductive intercalation material 31 is disposed so as to be press-fitted into the gap s, so that the microphone unit 11 is also stably positioned within the base end 24 of the acoustic tube 21. Will be able to. Note that the rear acoustic terminal 13 side of the microphone unit 11 is fixed to a corresponding portion on the inner peripheral surface 26 side of the acoustic tube 21 including the gap s through an appropriate adhesive such as a rubber adhesive (not shown). Therefore, it can be attached more stably.

  For this reason, the microphone unit 11 supports the front acoustic terminal 12 side on the stepped portion 25 in the acoustic tube 11 together with the conductive interposing material 31 that is densely arranged so that the peripheral wall portion 33 fills the gap s. The position can be reliably fixed to the acoustic tube 11 side.

  In addition, the conductive intercalation material 31 made of a bottomed cylindrical elastic metal material can be easily inserted into the corresponding part of the space s in the acoustic tube 11 by simply pushing it together with the microphone unit 11. Can be arranged.

  Therefore, in the narrow directivity condenser microphone according to the present invention, the microphone unit 11 and the acoustic tube 21 can be electrically connected in a more reliable and stable state. It is possible to effectively prevent entry and to exhibit stable quality and performance with less noise.

  The above is the description of the present invention based on the illustrated example, and the specific configuration is not limited thereto. For example, the conductive interposing material 31 may be formed with the bottom portion 32 excluding a portion supported by being in contact with the stepped portion 25 as a notch. Further, the conductive intercalation material 31 can be divided into a plurality of parts, for example, divided into two parts as required. Further, the peripheral wall portion 33 of the conductive interposing material 31 can be formed by shortening its length as compared to the illustrated example or by providing a length that reaches the rear acoustic terminal 13 side of the microphone unit 11. .

The side view which illustrates the external appearance by the side of the acoustic tube in this invention. The longitudinal cross-sectional view of FIG. FIG. 3 is an enlarged detail view of a circular go region in FIG. 2. Explanatory drawing shown in the state which isolate | separated the acoustic tube, the microphone unit, and the electroconductive intervention material mutually. The side view which shows the external appearance by the side of the acoustic tube in a prior art example. The longitudinal cross-sectional view of FIG. FIG. 7 is an enlarged detailed view of a circular go region in FIG. 6. An explanatory view showing a state where an acoustic tube and a microphone unit are separated from each other.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Microphone unit 12 Front acoustic terminal 13 Back acoustic terminal 14 Outer peripheral surface 21 Acoustic tube 22 Tip end 23 Acoustic resistance hole 24 Base end part 25 Step part 26 Inner peripheral surface 27 Rear sound wave inlet 28 Base end opening 29 Female screw part 31 Conductivity Intervention material 32 bottom 33 peripheral wall 34 opening s gap

Claims (3)

In a narrow directional condenser microphone having at least a microphone unit having a front acoustic terminal and a rear acoustic terminal, and an acoustic tube for housing the microphone unit with an air gap interposed between the microphone unit and the inner peripheral surface thereof,
The microphone unit covers the peripheral surface portion on the front acoustic terminal side located in the gap with respect to the step portion formed by expanding the inner diameter of the portion located on the proximal end side of the acoustic tube. A narrow directional condenser microphone characterized in that the front acoustic terminal is supported together with a conductive intercalation material and is fixed to the acoustic tube side.   2. The conductive interposing material is formed of an elastic metal material having a bottomed cylindrical shape with a taper in which a peripheral wall portion is slightly reduced in diameter toward a bottom portion facing the front acoustic terminal side. Narrow directional condenser microphone as described in 1. The narrow directional capacitor according to claim 1 or 2, wherein the rear acoustic terminal side of the microphone unit is fixed to a corresponding portion on the inner peripheral surface side of the acoustic tube including the gap through an adhesive. Microphone.

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