JPH0432875Y2 - - Google Patents
Info
- Publication number
- JPH0432875Y2 JPH0432875Y2 JP7940187U JP7940187U JPH0432875Y2 JP H0432875 Y2 JPH0432875 Y2 JP H0432875Y2 JP 7940187 U JP7940187 U JP 7940187U JP 7940187 U JP7940187 U JP 7940187U JP H0432875 Y2 JPH0432875 Y2 JP H0432875Y2
- Authority
- JP
- Japan
- Prior art keywords
- acoustic
- diaphragm
- cylindrical casing
- condenser microphone
- fixed pole
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000012212 insulator Substances 0.000 claims description 14
- 238000006243 chemical reaction Methods 0.000 claims description 10
- 239000012528 membrane Substances 0.000 description 20
- 230000010363 phase shift Effects 0.000 description 11
- 230000035945 sensitivity Effects 0.000 description 5
- 230000002093 peripheral effect Effects 0.000 description 4
- 238000004891 communication Methods 0.000 description 3
- 125000006850 spacer group Chemical group 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
Landscapes
- Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
- Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
Description
【考案の詳細な説明】
＜産業上の利用分野＞
この考案は、指向性をよくするとともに高感度
化を実現させたコンデンサマイクロホンユニツト
に関するものである。[Detailed description of the invention] <Industrial field of application> This invention relates to a condenser microphone unit that has improved directivity and achieved high sensitivity.
＜従来の技術＞
第４図は従来のコンデンサマイクロホンユニツ
トの断面図であり、１は導電性（金属製）の筒状
筐体で、その前面に所定の大きさの開口１aが設
けられている。この開口１aの背面側に、前記開
口１aとほぼ等しい孔２aを有する導電性のリング
２を配設し、このリング２の周縁部の背面に当接
させて導電性の振動膜３を配設し、この振動膜３
の背面に、その周縁部にリング状のスペーサ４を
介在させて、振動膜３との間に所定の空隙が生じ
るように絶縁体５で保持された導電性の固定極６
が配設されている。この導電性の固定極６および
絶縁体５には前記振動膜３の背面の空隙に連通す
る空気漏れ孔（音響回路）６a，５aが設けられて
おり、さらに、絶縁体５に設けられた空気漏れ孔
５aの背面に音響抵抗体７が配設され、この音響
抵抗体７の背面側と筒状筐体１の背面内側１bに
取り付けられたプリント基板８との間の空間に、
プリント基板８に一端が取り付けられて配設され
たインピーダンス変換用IC９の他端を前記導電
性の固定極６に接続している。また、筒状筐体１
の側面に振動膜３の背面に加わる音圧を得るため
の孔１cが設けられている。<Prior art> Fig. 4 is a sectional view of a conventional condenser microphone unit, in which 1 is a conductive (metallic) cylindrical casing, and an opening 1a of a predetermined size is provided in the front surface of the cylindrical casing. There is. A conductive ring 2 having a hole 2 a almost equal to the opening 1 a is disposed on the back side of the opening 1 a , and a conductive vibrating membrane 3 is placed in contact with the back surface of the peripheral edge of the ring 2. This vibrating membrane 3
A conductive fixed pole 6 is held by an insulator 5 on the back surface of the diaphragm 3, with a ring-shaped spacer 4 interposed around its periphery, and a predetermined gap is created between the pole and the vibrating membrane 3.
is installed. The conductive fixed pole 6 and the insulator 5 are provided with air leak holes (acoustic circuits) 6 a and 5 a that communicate with the gap on the back side of the vibrating membrane 3 . An acoustic resistor 7 is disposed on the back side of the air leak hole 5a , and an acoustic resistor 7 is provided in the space between the back side of the acoustic resistor 7 and the printed circuit board 8 attached to the inner back side 1b of the cylindrical housing 1. ,
The other end of an impedance converting IC 9 whose one end is attached to the printed circuit board 8 is connected to the conductive fixed pole 6. In addition, the cylindrical housing 1
A hole 1c for obtaining sound pressure applied to the back surface of the diaphragm 3 is provided on the side surface of the diaphragm 3.
第５図は従来のコンデンサマイクロホンユニツ
トの他の例であり、筒状筐体１の背面内側に固定
されたプリント基板８に、振動膜３の背面に加わ
る音圧を得るための孔８aが設けられた点が前記
第４図に示すコンデンサマイクロホンユニツトと
相違する。 FIG. 5 shows another example of a conventional condenser microphone unit, in which a printed circuit board 8 fixed to the inside of the back surface of the cylindrical housing 1 has a hole 8 a for obtaining sound pressure applied to the back surface of the diaphragm 3. This is different from the condenser microphone unit shown in FIG. 4 in the following points.
第６図は前記第４図および第５図に示すような
コンデンサマイクロホンユニツトの音響等価回路
であり、前記第４図および第５図に示す符号と対
応させて説明すると、Ｐ１は振動膜３の前面に加
わる音圧、Ｐ２は振動膜３の背面に加わる音圧、
CO，MO，ROは振動系の呈する等価インピーダ
ンス、Ｃ１は前記導電性の固定極６の背面側の空
間（音響回路）の等価容量、Ｒ１は前記音響抵抗
体７の等価抵抗、Ｃ２は前記音響抵抗体７とプリ
ント基板８との間のインピーダンス変換用IC９
などの電気部品が収納されている空間（音響回
路）の等価容量、Ｍ２は前記振動膜３の背面音圧
を得るための孔１c，８aの呈する等価質量であ
り、前記Ｃ１，Ｒ１，Ｃ２，Ｍ２で形成される点
線で囲んだ回路が指向性に影響を与える音響移相
回路である。 FIG. 6 shows an acoustic equivalent circuit of the condenser microphone unit as shown in FIGS. The sound pressure applied to the front side, P2 is the sound pressure applied to the back side of the diaphragm 3,
CO, MO, RO are the equivalent impedances exhibited by the vibration system, C1 is the equivalent capacitance of the space (acoustic circuit) on the back side of the conductive fixed pole 6, R1 is the equivalent resistance of the acoustic resistor 7, and C2 is the acoustic IC9 for impedance conversion between resistor 7 and printed circuit board 8
M2 is the equivalent capacity of the space (acoustic circuit) in which electrical components such as are housed, M2 is the equivalent mass exhibited by the holes 1 c and 8 a for obtaining the backside sound pressure of the diaphragm 3, and C1, R1, The circuit formed by C2 and M2 and surrounded by a dotted line is an acoustic phase shift circuit that affects directivity.
また、その他の従来技術として、実公昭52−
23004号公報、実公昭52−52581号公報に記載のよ
うなコンデンサマイクロホンがあるが、これらの
コンデンサマイクロホンも音圧方向に直交するよ
うに振動板が配設されている。 In addition, as other conventional technology,
There are capacitor microphones such as those described in Japanese Utility Model Publication No. 23004 and Japanese Utility Model Publication No. 52-52581, and these capacitor microphones also have a diaphragm arranged so as to be orthogonal to the sound pressure direction.
さらにまた、他の従来技術として、実開昭55−
159698号公報に記載のようなコンデンサマイクロ
ホンがあり、このコンデンサマイクロホンは音圧
方向に平行に振動板が配設されているが、この振
動板の背面の空間内（音響回路）にアンプ用IC
が配設されている。 Furthermore, as another conventional technology,
There is a condenser microphone as described in Publication No. 159698. This condenser microphone has a diaphragm arranged parallel to the sound pressure direction, but an amplifier IC is installed in the space (acoustic circuit) behind this diaphragm.
is installed.
＜考案が解決しようとする問題点＞
コンデンサマイクロホンにおいては、音響→電
気変換器の出力端子からのインピーダンス変換回
路までの距離が長いと、感度の低下、誘導雑音や
振動雑音の発生などのトラブルが生じるため、最
近ではインピーダンス変換用ICを金属製のマイ
クロホンユニツトの筐体内に内蔵する傾向であ
る。<Problems that the invention aims to solve> In condenser microphones, if the distance from the output terminal of the acoustic to electrical converter to the impedance conversion circuit is long, problems such as decreased sensitivity and generation of induced noise and vibration noise may occur. Therefore, there is a recent trend to embed an impedance conversion IC inside the metal microphone unit housing.
しかし、従来の振動膜と固定極が筒状筐体内に
音圧方向と直交するように配設された構造では、
第４図、第５図に示されているようにインピーダ
ンス変換用IC９が第６図に示すように音響移相
回路１０を形成する音響回路内に取り付けられて
いるので、その音響回路の容積が比較的大きくな
り、また、筒状筐体１あるいはプリント基板８に
設けられれた振動膜３の背面の音圧を導入するた
めの孔１c，８aの呈する等価質量の影響も無視で
きなくなつている。 However, in the conventional structure in which the diaphragm and fixed pole are arranged perpendicular to the sound pressure direction within the cylindrical housing,
As shown in FIGS. 4 and 5, the impedance conversion IC 9 is installed in the acoustic circuit forming the acoustic phase shift circuit 10 as shown in FIG. In addition, the effect of the equivalent mass exhibited by the holes 1 c and 8 a for introducing sound pressure from the back of the diaphragm 3 provided on the cylindrical housing 1 or the printed circuit board 8 cannot be ignored. ing.
本来、所定の指向性を得るための前記音響移相
送回路１０は、前記固定極６の背面側の空間の等
価容量Ｃ１と前記音響抵抗体７の等価抵抗Ｒ１で
構成されなければならないが、第４図、第５図に
示すような従来の構造できは、前記インピーダン
ス変換用IC９などの電気部品が収納されている
空間の等価容量Ｃ２、前記振動膜３の背面音圧を
得るための孔１c，８aの呈する等価質量Ｍ２が影
響しており、理想的な音響移相回路が得にくい。 Originally, the acoustic phase shift transmission circuit 10 for obtaining a predetermined directivity must be composed of the equivalent capacitance C1 of the space on the back side of the fixed pole 6 and the equivalent resistance R1 of the acoustic resistor 7. The conventional structure as shown in FIG. 4 and FIG. This is affected by the equivalent mass M2 exhibited by 1 c and 8 a , making it difficult to obtain an ideal acoustic phase shift circuit.
また、コンデンサマイクロホンの指向性の調整
は、一般に音響移相回路１０を形成する前記音響
抵抗体７の等価抵抗Ｒ１の値を調整して行うが、
第４図、第５図に示すような従来のコンデンサマ
イクロホンユニツトの構造では、この音響抵抗体
が筒状筐体１の奥に設置されており、組立後の調
整はきわめて困難である。 Further, the directivity of the condenser microphone is generally adjusted by adjusting the value of the equivalent resistance R1 of the acoustic resistor 7 forming the acoustic phase shift circuit 10.
In the structure of a conventional condenser microphone unit as shown in FIGS. 4 and 5, this acoustic resistor is installed deep inside the cylindrical housing 1, making adjustment after assembly extremely difficult.
また、従来のコンデンサマイクロホンユニツト
の構造では、振動膜３と固定極６とが筒状筐体１
内に音圧方向と直交するように配設されており、
そのため、振動膜３と固定極６の有効面積は、筒
状筐体１の口径によつて制限を受け、従つて、そ
の口径が小さい場合は、マイクロホンの感度を高
く設計することはきわめて困難である。 Furthermore, in the structure of the conventional condenser microphone unit, the diaphragm 3 and the fixed pole 6 are attached to the cylindrical housing 1.
is arranged perpendicular to the sound pressure direction within the
Therefore, the effective area of the diaphragm 3 and the fixed pole 6 is limited by the diameter of the cylindrical housing 1. Therefore, if the diameter is small, it is extremely difficult to design a microphone with high sensitivity. be.
また、指向性のコンデンサマイクロホンユニツ
トにおいては、周波数の低域限界は振動膜のスチ
フネスの大きさによつて決定されるが、その振動
膜のスチフネスは振動膜の面積と関係があり、振
動膜の面積が小さいほどスチフネスは大きくな
り、周波数の抵抗限界は高くなる、などの問題点
がある。 In addition, in a directional condenser microphone unit, the low frequency limit is determined by the stiffness of the diaphragm, but the stiffness of the diaphragm is related to the area of the diaphragm. There are problems such as the smaller the area, the greater the stiffness, and the higher the frequency resistance limit.
＜問題点を解決するための手段＞
この考案は、前記のような問題点を解決するた
め、筒状筐体内に絶縁体に保持された振動膜と固
定極とを僅かな間隙を置いて相対向させて筒状筐
体の長手方向にほぼ平行に配設し、前記振動膜の
前方から筒状筐体の長手方向の前面に連通する所
定の形状に設計された音響回路、および振動膜の
後方から筒状筐体の外壁の近傍に配設した音響抵
抗体に連通する音響回路を設け、インピーダンス
変換用ICを前記音響回路と分離独立した箇所に
収納したことを特徴とするコンデンサマイクロホ
ンユニツトを提供するものである。<Means for solving the problem> In order to solve the above-mentioned problems, this invention is based on a structure in which the oscillating membrane, which is held by an insulator in a cylindrical housing, and the fixed pole are placed relative to each other with a small gap. an acoustic circuit designed to have a predetermined shape and arranged substantially parallel to the longitudinal direction of the cylindrical casing, and communicating from the front of the diaphragm to the front surface of the cylindrical casing in the longitudinal direction; A condenser microphone unit characterized in that an acoustic circuit is provided that communicates with an acoustic resistor arranged near the outer wall of a cylindrical casing from the rear, and an impedance conversion IC is housed in a separate and independent location from the acoustic circuit. This is what we provide.
＜作用＞
前記のように、振動膜と固定極は筒状筐体内に
長手方向（軸方向）にほぼ平行に配設されている
ため、筒状筐体の径方向の振動膜と固定極の一辺
の長さは筒状筐体の口径によつて決まるのでそれ
程大きくすることはできないが、筒状筐体の長手
方向（軸方向）の他辺の長さは、筒状筐体の口径
に関係なく自由に設定できるので、筒状筐体が小
口径でも振動膜の有効面積を大きく設計すること
が可能となり、そのために感度が高く、しかも、
周波数の抵域限界の低い、小径で指向性のよいコ
ンデンサマイクロホンユニツトを得ることができ
る。しかも、振動膜と固定極を筒状筐体内の長手
方向に配設し、音圧の方向と平行しているにもか
かわらず、筒状筐体の前面から振動膜の前面に連
通する音響回路を所定の形状に設計することによ
り、このコンデンサマイクロホンユニツトの指向
軸は、振動膜や固定極が音圧の方向と直交するよ
うに配設されている通常のコンデンサマイクロホ
ンとまつたく同じになり、従来のコンデンサマイ
クロホンと何等変わることなく使用することがで
きる。<Function> As mentioned above, since the diaphragm and the fixed pole are arranged almost parallel to each other in the longitudinal direction (axial direction) within the cylindrical casing, the diaphragm and the fixed pole are arranged in the radial direction of the cylindrical casing. The length of one side is determined by the diameter of the cylindrical housing, so it cannot be made that large, but the length of the other side in the longitudinal direction (axial direction) of the cylindrical housing depends on the diameter of the cylindrical housing. Since it can be set freely regardless of the diameter, it is possible to design a large effective area of the diaphragm even if the diameter of the cylindrical housing is small, resulting in high sensitivity.
It is possible to obtain a small-diameter condenser microphone unit with a low frequency resistance limit, a small diameter, and good directivity. Moreover, the diaphragm and the fixed pole are arranged in the longitudinal direction of the cylindrical casing, and even though they are parallel to the direction of sound pressure, the acoustic circuit communicates from the front of the cylindrical casing to the front of the diaphragm. By designing the condenser microphone unit into a predetermined shape, the directivity axis of this condenser microphone unit is exactly the same as that of a normal condenser microphone in which the diaphragm and fixed pole are arranged perpendicular to the direction of sound pressure. It can be used just like a conventional condenser microphone.
また、インピーダンス変換用ICは前記音響回
路すなわち音響移相回路を形成する空間とは分離
独立した箇所に収納されているので、理想的な音
響移相回路が容易に実現できる。 Furthermore, since the impedance conversion IC is housed in a location separate and independent from the space forming the acoustic circuit, that is, the acoustic phase shift circuit, an ideal acoustic phase shift circuit can be easily realized.
また、前記音響抵抗体が筒状筐体の外壁の近傍
に配設されているので、組立後にこの音響抵抗体
と外気とを連通する連通孔の大きさを調整するな
どによつて、容易に指向性の調整が可能となる。 Furthermore, since the acoustic resistor is disposed near the outer wall of the cylindrical casing, it can be easily adjusted by adjusting the size of the communication hole that communicates the acoustic resistor with the outside air after assembly. Directivity can be adjusted.
＜実施例＞
第１図はこの考案のコンデンサマイクロホンユ
ニツトの断面図であり、１１は導電性（金属性）
の筒状筐体で、その前面に所定の大きさの開口１
１aが設けられており、この筒状筐体１１内に、
分割された絶縁体１２，１２’に保持されて振動
膜１３と固定極１４とが僅かな間隙を置いて相対
向させて筒状筐体１１の長手方向すなわち音圧方
向にほぼ平行に配設されている。この具体的な配
設手段を説明すると、前記分割された一方の絶縁
体１２には、できるだけスムースに音波を振動膜
１３に導き、しかもその音波の導入孔の空間の容
積がなるべく小さくなるように、前記筒状筐体１
１の前面の開口１１aと対向する孔端の断面積が
最も大きく、振動膜１３に接近するに従い次第に
孔の断面積が小さくなるように設計した音波導入
孔（音響回路）１２aが設けられている。何故な
らば、この音波導入孔１２aの形状は、振動膜１
３に加わる音圧に大きな影響を及ぼし、音波導入
孔１２aの形状によつて定まる共振周波数より高
い周波数では振動膜１３に加わる音圧は急速に減
衰する。従つて、音波導入孔１２aは等価質量や
等価容量の値ができるだけ小さくなるような形状
に設計し、これによつて生じる共振周波数が周波
数帯域より高い周波数になるようにする必要があ
る。この音波導入孔１２aの背面に前記振動膜１
３の有効面積とほぼ等しい孔１５aを有する導電
性のリング１５を前記導電性の筒状筐体１１に電
気的に接触させて配設し、このリング１５の周縁
部の背面に当接させて前記導電性の振動膜１３を
配設し、この振動膜１３の背面に、その周縁部に
絶縁性のリング状のスペーサ１６を介在させて、
振動膜１３と前記分割された他方の絶縁体１２’
で保持された前記導電性の固定極１４との間に所
定の空隙が形成されるように配設されている。こ
の導電性の固定極１４には前記振動膜１３の背面
の空隙と連通する空気漏れ孔（音響回路）１４a
が設けられており、さらに、この固定極１４の背
面と絶縁体１２’との間には筒状筐体１１の後面
方向に連通する空間（音響回路）１７が設けら
れ、この空間１７の筒状筐体１１の後面に連通す
る側の端に音響抵抗体１８が配設され、この音響
抵抗体１８の後面および前記絶縁体１２，１２’
の後面に当接させてプリント基板１９が筒状筐体
１１の後面周縁部にかしめ止めなどによつて取り
付けられており、このプリント基板１９には前記
音響抵抗体１８に連通する孔１９aが設けられて
いる。<Example> Figure 1 is a cross-sectional view of the condenser microphone unit of this invention, where 11 is a conductive (metallic)
It is a cylindrical case with an opening 1 of a predetermined size on the front side.
1 a is provided, and inside this cylindrical housing 11,
The vibrating membrane 13 and the fixed pole 14 are held by the divided insulators 12 and 12' and are arranged substantially parallel to the longitudinal direction of the cylindrical casing 11, that is, the sound pressure direction, facing each other with a slight gap. has been done. To explain this specific arrangement means, one of the divided insulators 12 is arranged so that the sound waves can be guided to the vibrating membrane 13 as smoothly as possible, and the volume of the space of the sound wave introduction hole can be made as small as possible. , the cylindrical housing 1
A sound wave introduction hole (acoustic circuit) 12a is provided in the front surface of the sound wave introduction hole (acoustic circuit) 12a, which is designed such that the cross-sectional area of the hole end facing the opening 11a is the largest, and the cross-sectional area of the hole gradually becomes smaller as it approaches the vibrating membrane 13 . ing. This is because the shape of the sound wave introduction hole 12a is different from that of the vibration membrane 1.
At frequencies higher than the resonance frequency determined by the shape of the sound wave introduction hole 12a , the sound pressure applied to the vibrating membrane 13 is rapidly attenuated. Therefore, it is necessary to design the sound wave introducing hole 12a in a shape that minimizes the equivalent mass and equivalent capacitance values so that the resulting resonance frequency is higher than the frequency band. The vibration membrane 1 is provided on the back side of this sound wave introducing hole 12a .
A conductive ring 15 having a hole 15a approximately equal to the effective area of 3 is disposed in electrical contact with the conductive cylindrical casing 11, and is brought into contact with the back surface of the peripheral edge of the ring 15. The conductive vibrating membrane 13 is disposed on the back side of the vibrating membrane 13, and an insulating ring-shaped spacer 16 is interposed at the peripheral edge of the vibrating membrane 13.
Vibrating membrane 13 and the other divided insulator 12'
A predetermined gap is formed between the conductive fixed pole 14 and the conductive fixed pole 14 held by the conductive fixed pole 14 . This conductive fixed pole 14 has an air leak hole (acoustic circuit) 14a that communicates with the gap on the back surface of the vibrating membrane 13.
Furthermore, a space (acoustic circuit) 17 communicating with the rear surface of the cylindrical housing 11 is provided between the back surface of the fixed pole 14 and the insulator 12'. An acoustic resistor 18 is disposed at the end of the side communicating with the rear surface of the shaped housing 11, and the rear surface of the acoustic resistor 18 and the insulators 12, 12'
A printed circuit board 19 is attached to the peripheral edge of the rear surface of the cylindrical casing 11 by caulking or the like so as to be in contact with the rear surface, and this printed circuit board 19 has a hole 19 a communicating with the acoustic resistor 18 . It is provided.
また、前記空間１７と分離独立した前記分割さ
れた他方の絶縁体１２’と筒状筐体１１で囲まれ
た空間２０に、前記プリント基板１９に一端が接
続されて配設されたインピーダンス変換用IC２
１の他端を前記導電性の固定極１４に接続して、
この考案のコンデンサマイクロホンユニツトが構
成されている。 Further, an impedance conversion device is provided in a space 20 surrounded by the other divided insulator 12' and the cylindrical casing 11, which is separate and independent from the space 17, and whose one end is connected to the printed circuit board 19. IC2
1 is connected to the conductive fixed pole 14,
A condenser microphone unit of this invention is constructed.
第２図はこの考案のコンデンサマイクロホンユ
ニツトの音響等価回路であり、第１図に示した符
号と対応させて説明すると、Ｐ１は振動膜１３の
前面に加わる音圧、Ｐ２は振動膜１３の背面に加
わる音圧、Mhは前記音波導入孔１２aの呈する等
価質量、Chは前記振動膜１３の前面の空間の等
価容量、CO，MO，ROは振動系の呈する等価イ
ンピーダンス、Ｃ１は前記固定極１４と分割され
た他方の絶縁体１２’との間の空間１７の等価容
量、Ｒ１は前記音響抵抗体１８の等価抵抗であ
り、この等価容量Ｃ１と等価抵抗Ｒ１とによつて
音響移相回路２２が形成されている。ここにおい
て、前記等価質量Mh、等価容量Chは所定の形状
に設計された音響回路によつて実用周波数帯には
影響を及ぼさない値とすることができる。 FIG. 2 shows the acoustic equivalent circuit of the condenser microphone unit of this invention, and to explain it in correspondence with the symbols shown in FIG. Mh is the equivalent mass of the sound wave introduction hole 12a , Ch is the equivalent capacity of the space in front of the vibrating membrane 13, CO, MO, RO are the equivalent impedances of the vibration system, C1 is the fixed pole The equivalent capacitance R1 of the space 17 between the insulator 14 and the other divided insulator 12' is the equivalent resistance of the acoustic resistor 18, and this equivalent capacitance C1 and equivalent resistance R1 form an acoustic phase shift circuit. 22 is formed. Here, the equivalent mass Mh and equivalent capacitance Ch can be set to values that do not affect the practical frequency band by the acoustic circuit designed in a predetermined shape.
第３図はこの考案のコンデンサマイクロホンユ
ニツトの出力電圧の指向周波数特性を実測したも
のを図示したものである。 FIG. 3 shows the actually measured directional frequency characteristics of the output voltage of the condenser microphone unit of this invention.
＜考案の効果＞
この考案は、以上説明したように、筒状筐体内
に絶縁体に保持された振動膜と固定極とを僅かな
間隙を置いて相対向させて筒状筐体の長手方向に
ほぼ平行に配設し、前記振動膜の前方から筒状筐
体の長手方向の前面に連通する所定の形状に設計
された音響回路、および振動膜の後方から筒状筐
体の外壁の近傍に配設した音響抵抗体に連通する
音響回路を設け、インピーダンス変換用ICを前
記音響回路と分離独立した箇所に収納したことを
特徴とするコンデンサマイクロホンユニツトを提
供したので、振動膜と固定極は筒状筐体内に長手
方向（軸方向）にほぼ平行に配設されているた
め、筒状筐体の径方向の振動膜と固定極の一辺の
長さは筒状筐体の口径によつて決まるのでそれ程
大きくすることはできないが、筒状筐体の長手方
向（軸方向）の他辺の長さは、筒状筐体の口径に
関係なく自由に設定できるので、筒状筐体が小口
径でも振動膜の有効面積を大きく設計することが
可能となり、そのために感度が高く、しかも、周
波数の抵域限界が低く、かつ、振動膜を筒状筐体
の長手方向に平行に配設したにもかかわらず筒状
筐体の長手方向に指向軸が一致した、小径（小
型）で指向性のよいコンデンサマイクロホンユニ
ツトを得ることができる。<Effects of the invention> As explained above, this invention is based on the fact that the vibrating membrane and the fixed pole, which are held by an insulator inside the cylindrical casing, are opposed to each other with a slight gap between them in the longitudinal direction of the cylindrical casing. an acoustic circuit designed in a predetermined shape that is arranged approximately parallel to the diaphragm and communicates from the front of the diaphragm to the front surface in the longitudinal direction of the cylindrical casing, and from the rear of the diaphragm near the outer wall of the cylindrical casing. We have provided a condenser microphone unit characterized in that an acoustic circuit is provided that communicates with an acoustic resistor disposed in Since they are arranged almost parallel to the longitudinal direction (axial direction) within the cylindrical housing, the length of one side of the radial vibration membrane and fixed pole of the cylindrical housing depends on the diameter of the cylindrical housing. However, since the length of the other longitudinal (axial) side of the cylindrical casing can be freely set regardless of the diameter of the cylindrical casing, it is possible to make the cylindrical casing smaller. It is possible to design the effective area of the diaphragm to be large regardless of the diameter, resulting in high sensitivity and a low frequency limit.The diaphragm is arranged parallel to the longitudinal direction of the cylindrical housing. Nevertheless, it is possible to obtain a condenser microphone unit with a small diameter (compact size) and good directivity, the directivity axis of which coincides with the longitudinal direction of the cylindrical casing.
また、インピーダンス変換用ICは前記音響回
路すなわち音響移相回路を形成する空間とは分離
独立した箇所に収納されているので、理想的な音
響移相回路が容易に実現できる。 Furthermore, since the impedance conversion IC is housed in a location separate and independent from the space forming the acoustic circuit, that is, the acoustic phase shift circuit, an ideal acoustic phase shift circuit can be easily realized.
また、前記音響抵抗体が筒状筐体の外壁の近傍
に配設されているので、組立後にこの音響抵抗体
と外気とを連通する連通孔の大きさを調整するな
どによつて、容易に指向性の調整が可能となる。 Furthermore, since the acoustic resistor is disposed near the outer wall of the cylindrical casing, it can be easily adjusted by adjusting the size of the communication hole that communicates the acoustic resistor with the outside air after assembly. Directivity can be adjusted.
第１図はこの考案のコンデンサマイクロホンユ
ニツトの断面図、第２図その音響等価回路、第３
図はその出力電圧の指向周波数特性を実測したも
のを図示したものである。第４図、第５図は従来
のコンデンサマイクロホンユニツトの断面図、第
６図はその音響等価回路である。
１１……筒状筐体、１１a……開口、１２，１
２’……絶縁体、１２a……音波導入孔、１３…
…振動膜、１４……固定極、１４a……空気漏れ
孔、１５……リング、１５a……孔、１６……ス
ペーサ、１７……固定極の背面の空間、１８……
音響抵抗体、１９……プリント基板、１９a……
連通孔、２０……空間、２１……インピーダンス
変換用IC、２２……音響移相回路。
Figure 1 is a sectional view of the condenser microphone unit of this invention, Figure 2 is its acoustic equivalent circuit, and Figure 3 is a cross-sectional view of the condenser microphone unit of this invention.
The figure shows the actually measured directional frequency characteristics of the output voltage. 4 and 5 are cross-sectional views of a conventional condenser microphone unit, and FIG. 6 is its acoustic equivalent circuit. 11...Cylindrical housing, 11 a ...Opening, 12,1
2'...Insulator, 12 a ...Sound wave introduction hole, 13...
... Vibration membrane, 14 ... Fixed pole, 14 a ... Air leak hole, 15 ... Ring, 15 a ... Hole, 16 ... Spacer, 17 ... Space on the back of fixed pole, 18 ...
Acoustic resistor, 19... Printed circuit board, 19 a ...
Communication hole, 20... Space, 21... Impedance conversion IC, 22... Acoustic phase shift circuit.
Claims (1)
極とを僅かな間隙を置いて相対向させて筒状筐体
の長手方向にほぼ平行に配設し、前記振動膜の前
方から筒状筐体の長手方向の前面に連通する所定
の形状に設計された音響回路、および振動膜の後
方から筒状筐体の外壁の近傍に配設した音響抵抗
体に連通する音響回路を設け、インピーダンス変
換用ICを前記音響回路と分離独立した箇所に収
納したことを特徴とするコンデンサマイクロホン
ユニツト。 A diaphragm held by an insulator in a cylindrical casing and a fixed pole are arranged substantially parallel to the longitudinal direction of the cylindrical casing, facing each other with a slight gap, and the diaphragm is inserted from the front of the diaphragm. An acoustic circuit designed in a predetermined shape that communicates with the front surface in the longitudinal direction of the cylindrical casing, and an acoustic circuit that communicates from the rear of the diaphragm to an acoustic resistor disposed near the outer wall of the cylindrical casing, A condenser microphone unit characterized in that an impedance conversion IC is housed in a location separate and independent from the acoustic circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7940187U JPH0432875Y2 (en) | 1987-05-26 | 1987-05-26 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7940187U JPH0432875Y2 (en) | 1987-05-26 | 1987-05-26 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63187500U JPS63187500U (en) | 1988-11-30 |
| JPH0432875Y2 true JPH0432875Y2 (en) | 1992-08-06 |
Family
ID=30929225
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7940187U Expired JPH0432875Y2 (en) | 1987-05-26 | 1987-05-26 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0432875Y2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006203468A (en) * | 2005-01-19 | 2006-08-03 | Nippon Denon Kk | Drip-proof type unidirectional microphone unit |
| JP4642541B2 (en) * | 2005-05-06 | 2011-03-02 | 株式会社オーディオテクニカ | Microphone |
-
1987
- 1987-05-26 JP JP7940187U patent/JPH0432875Y2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63187500U (en) | 1988-11-30 |
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