JP4512445B2 - Variable directivity condenser microphone - Google Patents

Description

  The present invention relates to a variable directional condenser microphone including a pair of capacitor elements, and more particularly, to a variable directional condenser microphone having an opening for pressure equalization that reduces a pressure difference between an external air pressure and a unit. .

  As shown in FIG. 5, the variable directivity condenser microphone includes a pair of capacitor elements 10L and 10R as a basic configuration. Since the capacitor elements 10L and 10R have the same configuration, only the left capacitor element 10L will be described here, and the reference numerals of the corresponding components of the right capacitor element 10R will be described in parentheses.

  In this example, the capacitor element 10L (10R) has a plurality of acoustic terminal holes 12aL (12aR) and vibrations formed in a substantially lid shape having a signal extraction electrode rod 12bL (12bR) at the center. A plate holder 12L (12R) is provided, and a diaphragm 11L (11R) is stretched with a predetermined tension inside the diaphragm holder 12L (12R). In addition, the polymer film which has a metal vapor deposition film is used for the diaphragm 11L (11R).

  A fixed pole 13L (13R) is disposed opposite to the diaphragm 11L (11R) via an electrically insulating spacer ring (not shown). Although only one is shown in FIG. 5, the fixed pole 13L (13R) has a large number of sound communication holes 13aL (13aR). The fixed pole 13L (13R) is supported by a disk-shaped electrode support 14L (14R) having a large sound communication hole 14aL (14aR) at the center, and the electrode support 14L (14R) and the diaphragm holder 12L (12R). Are fastened and fixed by a fastening ring 15L (15R).

  The capacitor elements 10L and 10R configured as described above are combined back to back. That is, the acoustic resistance material 21 made of, for example, a felt material is disposed between the sound communication holes 14aL and 14aR of the electrode supports 14L and 14R, and the gasket material 22 is disposed around the acoustic resistance material 21 so that the electrode supports 14L and 14R are connected to each other. These are assembled by connecting them with a coupler ring 23 facing each other.

  In this variable directivity condenser microphone, a part of the sound pressure applied to one diaphragm is transmitted to the back side of the other diaphragm via the sound communication holes 13aL, 13aR, 14aL, 14aR and the acoustic resistance material 21. In addition, by changing the polarization voltage relative to each of the fixed poles 13L and 13R, the directivity can be appropriately selected from, for example, unidirectionality, omnidirectionality, and bidirectionality.

  By the way, since the diaphragms 11L and 11R are made of a polymer film and do not allow air to pass through, the inside of the unit is almost sealed. Therefore, the diaphragms 11L and 11R may be displaced due to a pressure difference between the outside air pressure and the inside of the unit, resulting in a decrease in sensitivity. In order to solve this point, in Patent Document 1, fine holes are formed in the diaphragm so as to relieve the pressure difference between the external pressure and the inside of the unit. These fine holes are called pressure equivalent openings.

JP-A-9-84195

  Conventionally, spark discharge and needle stick are applied to form a pressure equivalent opening in the diaphragm. However, since the directivity frequency response deteriorates when a sound wave in the sound range to be collected passes through the pressure equivalent opening, the pressure equivalent opening is formed so that only a sufficiently low frequency passes through the collected sound wave. It must be.

  Therefore, a highly skilled technique is required for drilling the pressure equivalent opening, and productivity cannot be improved as expected. In addition, since the perforation failure of the diaphragm cannot be repaired, there is a problem in terms of yield.

  Therefore, the present invention enables a pressure equivalent opening to be formed in a mass-productive manner with high dimensional accuracy in a variable directional condenser microphone having a pressure equivalent opening that relieves a pressure difference between the outside air pressure and the inside of the unit. It is in.

In order to solve the above-mentioned problem, the invention according to claim 1 is configured such that a diaphragm stretched on a diaphragm holder and a fixed pole having a plurality of sound communication holes are opposed to each other via an electrically insulating spacer ring. In a variable directional condenser microphone comprising a pair of capacitor elements arranged in a combination, the capacitor elements being combined with the fixed poles facing each other with a support substrate interposed therebetween, the fixed poles are interposed via the spacer ring. And a copper foil pattern is formed on one surface of the printed wiring board facing the diaphragm and facing the diaphragm, and on the one surface of the printed wiring board, A dummy electrode made of a copper foil pattern having a notch-shaped opening for pressure equivalence in part is formed in a portion in contact with the spacer ring around the fixed pole. And which is characterized in that the space between the diaphragm and the fixed pole is in communication with the outside air through the openings for the pressure equivalent.

According to a second aspect of the invention, in the above claim 1, said printed circuit and tongue is continuously provided on a portion of the substrate, the electrode terminal portions of the fixed electrode above the tongue through between the pressure equivalent opening It is characterized by being pulled out to a piece .

  According to the first aspect of the present invention, since the pressure equivalent opening is formed on the printed wiring board by the copper foil pattern, the dimensional accuracy (dimension reproducibility) is good and the quality is uniform. The pressure equivalent opening can be mass-produced.

  Further, according to the invention described in claim 2, since the electrode terminal part of the fixed pole is drawn out between the pressure equivalent openings, a signal lead part such as an electrode rod can be made unnecessary. Further cost reduction can be achieved.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited to this. FIG. 1 is a front view showing an example of a variable directivity condenser microphone according to the present invention, FIG. 2 is a sectional view showing an exploded internal structure thereof, FIG. 3 is a plan view showing a fixed pole, and FIG. 4 is a main part of the present invention. It is a typical perspective view which extracts and shows.

  First, referring to FIGS. 1 and 2, the variable directivity condenser microphone includes a pair of left and right capacitor elements 100L and 100R. In this example, one capacitor element 100L is provided on the left support surface of the support substrate 200. The other capacitor element 100 </ b> R is disposed on the right support surface of the support substrate 200. An element storage recess 210 is formed on each support surface of the support substrate 200. This support substrate 200 corresponds to the electrode supports 14L and 14R in the conventional example of FIG.

  Capacitor elements 100L and 100R have the same configuration, and both include a diaphragm 110, a diaphragm ring 120 as a diaphragm holder, an electrically insulating spacer ring 130, a fixed electrode 140, and a cover plate 150.

  For example, a polymer film having a metal vapor deposition film may be used for the vibration plate 110. The diaphragm 110 is stretched on the diaphragm ring 120 via a suitable adhesive in a state where a predetermined tension is applied. The diaphragm 110 is disposed in the element housing recess 210 of the support substrate 200 in a state of facing the fixed pole 140 through the spacer ring 130, and the cover plate 150 is covered thereon.

  A number of sound communication holes 141 are formed in the fixed pole 140. Each element storage recess 210 of the support substrate 200 is partitioned by a thin partition wall 220 to form a predetermined volume of acoustic space between them, and the partition wall 220 has a space between the capacitor elements 100L and 100R. Is formed with a sound communication hole 221. A plurality of acoustic terminal holes 151 are formed in the cover plate 150.

  The cover plate 150 includes four fixing flanges 152 for the support substrate 200 in this example, and the capacitor elements 100L and 100R are respectively screwed into the element storage recesses 210 of the support substrate 200 by screwing the fixing flanges 152 to the support substrate 200. It is arranged in a substantially sealed state inside. The diaphragm ring 120 and the cover plate 150 may be integrated, and these correspond to the diaphragm holders 12L and 12R in the conventional example of FIG.

  As shown in FIG. 3, in the present invention, the fixed electrode 140 is formed by a copper foil pattern on one side of a printed wiring board 160 made of a copper-clad laminate, and the sound communication hole 141 is a through hole for the printed wiring board 160. It has been drilled.

  Referring also to FIG. 4, the printed wiring board 160 has a dummy electrode 142 made of a copper foil pattern in a portion that is in contact with the spacer ring 130 around the fixed pole 140 and has a notch in a part thereof, and is substantially annular. Is formed. This notch is used as a pressure equivalent opening 143 that reduces the pressure difference between the external air pressure and the inside of the unit.

  The volume of the pressure equivalent opening 143 is determined by the thickness of the copper foil pattern and the notch width, but the thickness of the copper foil pattern can be arbitrarily set when the copper foil is plated, and the notch width is extremely high. Since patterning can be performed with high accuracy, it is possible to obtain a pressure-equivalent opening 143 with good dimensional reproducibility and uniform quality.

  Further, since the pressure equivalent opening 143 is formed in a part of the dummy electrode 142, a tongue piece 161 is connected to a part of the printed wiring board 160, and the pressure equivalent opening 143 is provided between the tongue piece 161. The electrode terminal portion 144 of the fixed pole 140 can be pulled out through the through hole.

  As shown in FIGS. 1 and 2, the tongue piece 161 is disposed in a groove 211 that continues to the element storage recess 210. Therefore, in order to take out signals from the capacitor elements 100L and 100R, it is only necessary to solder a lead wire (not shown) to the electrode terminal portion 144. Signal lead parts such as the signal lead electrode rods 12aL and 12aR in the conventional example of FIG. It can be unnecessary.

The front view which shows an example of the variable directivity condenser microphone by this invention. FIG. 3 is an exploded sectional view showing an internal structure of the variable directivity condenser microphone. The top view which shows an example of the fixed pole with which this invention is provided. The typical perspective view which extracts and shows the principal part of this invention. Sectional drawing which shows the conventional variable directivity condenser microphone.

Explanation of symbols

100L, 100R Capacitor element 110 Diaphragm 120 Diaphragm ring 130 Spacer ring 140 Fixed electrode 142 Dummy electrode 143 Pressure equivalent opening 144 Electrode terminal part 150 Cover plate 160 Printed wiring board 161 Tongue piece 200 Support board 210 Element storage recess

Claims (2)

Each of the capacitor elements includes a pair of capacitor elements formed by opposingly arranging a diaphragm stretched on a diaphragm holder and a fixed pole having a plurality of sound communication holes via an electrically insulating spacer ring. In a variable directional condenser microphone that is a combination of these fixed electrodes facing each other with a support substrate in between,
The fixed pole is formed as a copper foil pattern on one surface of the printed wiring board that faces the diaphragm via the spacer ring and faces the diaphragm, and the printed wiring board. On the one surface, a dummy electrode made of a copper foil pattern having a notch-shaped pressure equivalent opening in part is formed at a portion in contact with the spacer ring around the fixed pole , A variable directional condenser microphone, characterized in that a space between the diaphragm and the fixed pole communicates with outside air through the pressure equivalent opening . The tongue piece is continuously provided in a part of the printed wiring board, and the electrode terminal portion of the fixed electrode is drawn out to the tongue piece through the pressure equivalent opening. The variable directional condenser microphone described.

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