JP5586519B2 - Condenser microphone unit - Google Patents

Description

  The present invention relates to a condenser microphone unit in which partial deposition is applied to a film material of a diaphragm in order to reduce loss due to stray capacitance that does not contribute to electroacoustic conversion.

  The condenser microphone unit includes a capacitor element in which a vibration plate that vibrates by sound waves and a fixed electrode (back electrode) are opposed to each other through an air layer having a predetermined interval, and the distance between the vibration plate and the fixed electrode changes. An audio signal is obtained by taking out a change in the capacitor (capacitance) as a change in voltage.

That is, the diaphragm is formed by depositing a metal film on a resin film material by vapor deposition or the like, and based on a capacitance between the metal film of the diaphragm and the metal fixed electrode facing the diaphragm. An audio signal can be obtained.
In this case, the diaphragm is generally attached to a ring-shaped diaphragm holder, and is arranged so as to face the fixed electrode through a ring-shaped spacer, and a microphone unit is assembled. Thereby, the diaphragm is configured to face the fixed electrode through an air layer corresponding to the thickness of the spacer formed in a ring shape (Patent Document 1).

JP 2009-71650 A

By the way, since the periphery of the diaphragm is attached to a ring-shaped diaphragm holder, the amplitude of the vicinity of the outer periphery of the diaphragm near the diaphragm holder is mechanically limited even when receiving sound waves. Can not get enough vibration action.
That is, there exists an effective capacitance that changes due to the displacement of the diaphragm, and an invalid capacitance (floating capacitance) that does not change the capacitance because sufficient vibration action cannot be obtained even when a sound wave is received. Become.

FIG. 5 shows an equivalent circuit in the case where the above-described effective capacitance and ineffective capacitance exist, and an output based on a change in capacitance consisting of the fixed electrode and the metal film of the diaphragm is shown in S. In this case, an effective capacitance Cb is connected in series to the output S, and an invalid capacitance (floating capacitance) Cs is connected in parallel to the series connection of the output S and the effective capacitance Cb. It becomes.
Therefore, the sound output level Sout by the microphone unit affected by each capacitance described above can be expressed as Sout = S × (Cs / Cb + Cs).

  That is, if the values of the effective capacitance Cb and the invalid capacitance Cs are the same, for example, the sound output level Sout by the microphone unit is half of the original output S, and the microphone sensitivity is inevitably lowered to half. Will do. Therefore, in this type of condenser microphone, it is desirable to make the above-described invalid capacitance (floating capacitance) as small as possible.

6 and 7 show an example of a conventional condenser microphone unit designed so that the above-mentioned invalid capacitance (stray capacitance) becomes as small as possible.
6A to 6F show members constituting the microphone unit. FIGS. 7A and 7B are assembled as a microphone unit by superimposing the members shown in FIG. This shows the state.

6A is a front view showing an assembly of the diaphragm holder 1 formed in a ring shape and the diaphragm 2 attached to the diaphragm holder 1 and partially deposited with a metal layer 2c on the front surface. It is. FIG. 4B is a cross-sectional view of the assembly of the diaphragm holder 1 and the diaphragm 2 shown in FIG.
(C) is the front view which showed the spacer 3 formed in the ring shape, (D) is the front view which showed the center spacer 4 arrange | positioned in the center part of the said spacer 3. FIG. Further, (E) is a front view showing the fixed electrode 5 formed of a metal material such as brass, and (F) is a cross-sectional view of the fixed electrode 5 shown in (E) cut at the central portion thereof. FIG.

  FIGS. 7A and 7B show a state in which the members shown in FIG. 6 are overlaid and assembled as a microphone unit as described above, and FIG. 7A is a front view of the unit. ) Is a cross-sectional view of the unit cut at the center.

  As shown in FIG. 7, when assembling as a microphone unit, first, the above-described fixed electrode 5 is used as a base. As described above, the fixed electrode 5 is formed of a metal material such as brass, and a columnar insulator is embedded in the central portion thereof to form an insulating portion 5a. The fixed electrode 5 has a plurality of through holes (sound holes) 5d penetrating in the plane direction at appropriate positions.

  A center spacer 4 is placed so as to overlap the insulating portion 5 a at the center of the fixed electrode 5, and a ring-shaped spacer 3 is overlapped along the outer peripheral edge of the fixed electrode 5. Further, the diaphragm holder 1 having the diaphragm 2 attached on the ring-shaped spacer 3 is overlaid.

  In this state, the screw 7 is connected to the insulating portion 5a of the fixed electrode 5 through the central hole 2a formed in the diaphragm 2 and the central hole 4a formed in the center spacer 4 as shown in FIG. Screwed. In this case, a conductive washer 8 and a lug plate 9 are disposed on the front surface of the diaphragm 2 and fastened together with the screws 7.

Further, along the peripheral edge of the fixed electrode 5 through the peripheral holes 1b formed at equal intervals in the peripheral direction in the peripheral edge of the diaphragm holder 1 and the peripheral holes 3b formed in the peripheral edge of the spacer 3. Screws 11 are screwed into the formed screw holes 5b, respectively, and the microphone unit is assembled.
The lug plate 9 described above functions as a lead terminal for the metal layer 2c partially deposited on the diaphragm 2.

  By the way, a metal layer 2c is formed on the front surface of the diaphragm 2 by partial vapor deposition as shown in FIGS. In this example, in the vicinity of the outer periphery of the diaphragm 2 near the ring-shaped diaphragm holder 1, the metal layer 2c is formed in a region concentrically with the diaphragm holder 1 while avoiding the formation of the metal layer 2c. It is filmed.

According to the partial vapor deposition of the metal layer 2c described above, the vicinity of the outer peripheral portion of the vibration plate 2 near the vibration plate holder 1 that cannot obtain a sufficient vibration action even when receiving a sound wave is formed without forming the metal layer 2c. The electric capacity is not formed.
According to this, since the degree of formation of the above-described invalid capacitance (stray capacitance) can be reduced, loss due to stray capacitance that does not contribute to electroacoustic conversion can be reduced.

By the way, according to the microphone unit shown in FIGS. 6 and 7, the lug plate 9 as the lead-out terminal of the metal layer 2 c partially vapor-deposited on the diaphragm 2 is attached by the screw 7 when the unit is assembled.
The lug plate 9 and the washer 8 rotate in the tightening direction of the screw 7 along with the tightening operation of the screw 7 at the time of attachment, and stress is applied to the vibration plate 2 in the rotational direction. .

  For this reason, individual differences occur in the tension of the diaphragm 2, and sometimes radial wrinkles are generated in the diaphragm 2 around the tightening portion of the screw 7, based on the tightening operation of the screw 7. In addition, there is a problem that the diaphragm is damaged.

  The present invention has been made paying attention to the above-described problems. When the extraction electrode is attached to the diaphragm in which a metal layer is partially formed, individual differences are caused in the tension of the diaphragm. It is an object of the present invention to provide a condenser microphone unit that does not interfere with the above.

  The condenser microphone unit according to the present invention, which has been made in order to solve the above-described problems, is arranged so that a peripheral portion thereof is opposed to the diaphragm supported by the diaphragm holder with a predetermined interval through a spacer. A capacitor microphone unit, wherein the diaphragm is formed of a resin film, and a metal layer is formed on a surface opposite to the surface facing the fixed electrode, The layer is formed in a region including the central portion of the resin film as long as it does not reach the diaphragm holder, and a magnet is embedded in a part of the fixed electrode, and is attracted to the magnet and is attached to the diaphragm. And a lead terminal that is electrically connected to the metal layer.

  In this case, in one preferable embodiment, the diaphragm holder is configured in a ring shape, and the metal layer is formed on the resin film in a region concentric with the diaphragm holder inside the diaphragm holder. Is done.

On the other hand, it is preferable that the lead-out terminal is mounted on the metal layer of the diaphragm using an adhesive while being attracted to the magnet.
In addition, the lead terminal preferably includes a flat plate portion attracted by the magnet and a terminal contact portion established in a vertical direction with respect to the flat plate portion.

  In one preferred embodiment of the magnet embedded in the fixed electrode, the magnet is composed of a rod-shaped magnet main body having a magnetic pole formed in the longitudinal direction and a bottomed cylindrical crucible yoke, and one of the magnet main bodies The magnetic pole is configured to be in contact with the inner bottom surface of the pot type yoke.

According to the microphone unit having the above-described configuration, the lead terminal from the metal layer formed on the diaphragm is attached to the metal layer by being attracted to the magnet embedded in a part of the fixed electrode. In an electrically conductive state.
Therefore, it is possible to eliminate the problems in the conventional microphone unit in which the lead terminal is fixed to the metal layer of the diaphragm by screwing, causing individual differences in the tension of the diaphragm or obstructing the diaphragm. A condenser microphone unit that is not provided can be provided.

It is the block diagram which decomposed | disassembled and showed each member of the capacitor | condenser microphone unit concerning this invention. It is the front view and sectional drawing which show the state assembled as a microphone unit by superimposing each member shown in FIG. FIG. 3 is an enlarged sectional view showing a part of the microphone unit shown in FIG. 2. It is the schematic diagram which showed the structural example of the magnet part which can be used suitably in the microphone unit shown in FIG. It is an equivalent circuit explaining the degree of loss when invalid capacitance exists. It is the block diagram which decomposed | disassembled and showed each member of the conventional microphone unit. It is the front view and sectional drawing of the conventional microphone unit assembled by superimposing each member shown in FIG.

Hereinafter, a condenser microphone unit according to the present invention will be described with reference to FIG. 1 and FIG. In FIGS. 1 and 2, parts that perform the same functions as those shown in FIGS. 6 and 7 described above are denoted by the same reference numerals, and therefore detailed description thereof will be omitted as appropriate.
The features of the microphone unit according to the present invention shown in FIGS. 1 and 2 are that a magnet is embedded in a part of the fixed electrode, and a drawer that is attracted to the magnet and is electrically connected to the metal layer of the diaphragm. The terminal is provided.

  A diaphragm 2 made of a resin film is attached to the diaphragm holder 1 in the microphone unit. In this embodiment, the diaphragm holder 1 is configured in a ring shape as shown in FIGS. 1A and 2, and is concentric with the diaphragm holder inside the ring-shaped diaphragm holder. In the inner region, a metal layer 2 c is formed on the diaphragm 2.

  That is, the metal layer 2c is formed by vapor deposition in a region including the central portion of the resin film within a range not reaching the diaphragm holder 1, and the vicinity of the outer peripheral portion of the diaphragm 2 near the diaphragm holder 1 is In this configuration, the metal layer 2c is not formed.

  Due to the partial vapor deposition of the metal layer 2c described above, the above-described reactive capacitance (floating capacitance) is present in the vicinity of the outer peripheral portion of the diaphragm 2 close to the diaphragm holder 1 that cannot obtain sufficient vibration action even when receiving sound waves. It is devised not to be formed. Thereby, the loss of the audio signal due to the generation of the stray capacitance described above can be reduced.

In addition, in this microphone unit, as shown in a part of the fixed electrode 5, that is, as shown in FIGS. 1 (F) and 2 (B), a magnet 13 is placed in an insulating part 5a formed at the center of the fixed electrode 5. Is buried.
Further, as shown in FIG. 2, a lead terminal 14 formed of an iron alloy or the like is disposed on the metal layer 2 c of the diaphragm 2 facing the magnet 13. It is attracted to the magnet 13 and mounted on the metal layer 2c of the vibration plate 2 so as to be electrically connected to the metal layer 2c.

A more detailed configuration of the magnet 13 and the lead terminal 14 is shown in an enlarged manner in FIG. The magnets 13 shown in FIG. 3 are magnetized at both ends in the longitudinal direction, and for example, the N pole at one end thereof is embedded in the insulating portion 5a so as to face the diaphragm 2 side. ing.
On the other hand, the lead terminal 14 formed of an iron alloy or the like includes a flat plate portion 14a formed in a disc shape and a rod-shaped terminal contact portion 14b established in a vertical direction with respect to the flat plate portion. Yes.

By placing the flat plate portion 14a of the lead-out terminal 14 at a substantially central portion of the diaphragm 2, the flat plate portion 14a is disposed through the diaphragm 2 and the center spacer 4 on which the metal layer 2c is deposited. It is attracted to the magnet 13 side. As a result, the lead terminal 14 is electrically connected to the metal layer 2c.
Accordingly, the potential in the metal layer 2c formed on the diaphragm 2 can be drawn using the terminal contact portion 14b formed in the vertical direction on the flat plate portion 14a of the lead terminal 14.

In addition, it is desirable to employ a configuration in which the above-described lead terminal 14 is mounted on the metal layer 2c of the diaphragm 2 with an adhesive. In this case, the adhesive is applied in a state where the lead terminal 14 is placed on the metal layer 2 c of the diaphragm 2 and is attracted by the magnet 13.
That is, as shown in FIG. 3, the lead terminal 14 can be attached in a stable state by applying and solidifying the adhesive 15 around the flat plate portion 14a.

  As the above-described adhesive 15, for example, hot melt can be suitably used. Since this adhesive can be easily solidified by heat irradiation after coating, it is easy to handle and can contribute to the improvement of productivity in this type of condenser microphone unit.

In the embodiment shown in FIGS. 1 to 3, the magnets 13 magnetized at both ends in the longitudinal direction are embedded in the insulating part 5 a formed at the center of the fixed electrode 5. Instead of this configuration, the configuration shown in FIG. 4 can be adopted.
That is, the configuration of the magnet 13 shown in FIG. 4 includes a rod-shaped magnet main body 13a having a magnetic pole in the longitudinal direction and a bottomed cylindrical crucible yoke 13b.

And one magnetic pole of the said magnet main body 13a is comprised in the state which contacted the center part of the inner bottom face of the said crucible type yoke 13b.
According to this configuration, the crucible yoke 13 b acts to effectively form a closed magnetic circuit with the lead terminal 14.

  According to the condenser microphone unit according to the present invention described above, the magnet is embedded in a part of the fixed electrode, and the lead-out terminal that is attracted to the magnet and is electrically connected to the metal layer of the diaphragm is provided. Therefore, it is possible to eliminate the problems in the microphone unit having a structure in which the lead terminal is fixed on the metal layer of the diaphragm by the conventional screw fastening, as described in the column of the effect of the invention described above. An effect can be obtained.

DESCRIPTION OF SYMBOLS 1 Diaphragm holder 2 Diaphragm 2a Center hole 2c Metal layer 3 Spacer 3b Perimeter hole 4 Center spacer 4a Center hole 5 Fixed electrode 5a Insulation part 5b Perimeter screw hole 5d Communication hole (sound hole)
7 screw 8 washer 9 lug plate 11 screw 13 magnet 13a magnet body 13b pot type yoke 14 electrode terminal 14a flat plate portion 14b terminal contact portion

Claims (5)

A diaphragm having a peripheral edge supported by a diaphragm holder, and a fixed electrode arranged to face the diaphragm with a predetermined interval through a spacer, and the diaphragm is formed of a resin film. And a condenser microphone unit in which a metal layer is formed on the surface opposite to the surface facing the fixed electrode,
The metal layer is formed in a region including a central portion of a resin film within a range not reaching the diaphragm holder, and a magnet is embedded in a part of the fixed electrode, and is attracted to the magnet and is vibrated. A condenser microphone unit comprising a lead terminal electrically connected to a metal layer of a plate.   The diaphragm holder is configured in a ring shape, and the metal layer is formed on the resin film in a region concentric with the diaphragm holder inside the diaphragm holder. 1. A condenser microphone unit described in 1.   2. The condenser microphone unit according to claim 1, wherein the lead-out terminal is mounted on the metal layer of the diaphragm with an adhesive while being attracted to the magnet.   The said extraction terminal is comprised from the flat plate part attracted | sucked by the said magnet, and the terminal contact part established in the perpendicular direction with respect to the said flat plate part, The Claim 1 or Claim 3 characterized by the above-mentioned. Condenser microphone unit.   The magnet embedded in the fixed electrode is composed of a rod-shaped magnet main body having a magnetic pole formed in the longitudinal direction and a bottomed cylindrical crucible yoke, and one magnetic pole of the magnet main body is formed of the crucible yoke. 5. The condenser microphone unit according to claim 1, wherein the condenser microphone unit is configured to be in contact with an inner bottom surface. 6.

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