A 3-pin type output connector for a condenser microphone includes a grounding first pin and second and third pins for signals, provided on a connector base made of an electric insulator. Each pin contains a chip type inductor element that inhibits a high-frequency current, and includes a pin main body provided on the connector base, a cylindrical chip holder made of an electric insulator and having one end attached to an end of the pin main body located inside the microphone case, and a metal cap that covers the other end of the chip holder so as to be electrically insulated from the pin main body. The chip type inductor element is placed in the chip holder, and the pin main body and the cap are electrically connected via the chip type inductor element.
A microphone unit of a condenser microphone has a very high impedance and thus contains an impedance converter such as an FET (Field Effect Transistor) or a vacuum tube. Normally, a phantom power source is used for the condenser microphone. Amicrophone sound signal is output via a balanced shield cable for the phantom power source.
The operation described below is conventionally used as a method for preventing an electromagnetic wave from entering the microphone through the output connector 10. A condenser is connected between the grounding first pin E and the hot-sidesecond pin SH and between the grounding first pin E and the cold-side third pin SC; the condensers operate to short high frequencies. Further, the hot-side second pin SH and the cold-side third pin SC are connected to the microphone case such as theconnector housing cylinder 20 via an inductor that inhibits the entry of high frequencies.
The above conventional technique can inhibit the entry of normal broadcasting electric waves, for example, electromagnetic waves of HF, VHF, or UHF without any problems. However, the recent prevalence of cellular phones and the like hasincreased the opportunities to use an electromagnetic wave of a higher frequency near the microphone.
The three pins E, SH, and SC of the output connector 10 are located directly inside the microphone case. Consequently, a high-frequency current may enter the microphone case through these pins, the high-frequency current resulting from anintense electromagnetic wave radiated by a cellular phone or the like. The high-frequency current then reaches an electronic circuit including an impedance circuit, by radiation or propagation to generate noise.
In particular, noise is made when a high-frequency current coming from the hot-side second pin SH or cold-side third pin SC is electrostatically coupled to the electronic circuit. In other cases, noise is made when high-frequency magnetic fieldsgenerated by a high frequency current flowing through the microphone case are magnetically coupled.
It is thus an object of the present invention to prevent a high-frequency current from entering a microphone case via a pin penetratingly provided on an output connector; the high-frequency current results from an electromagnetic wave radiated bya cellular phone.
To accomplish this object, the present invention provides an output connector of a 3-pin type in which three pins, a grounding first pin and second and third pins for signals are penetratingly provided on a connector base comprising an electricinsulator, the first pin being installed at an end of a conductive microphone case of a condenser microphone so as to electrically connect to the microphone case, wherein each of the pins contains a chip type inductor element that inhibits ahigh-frequency current.
According to the present invention, each pin contains the chip type inductor element that inhibits a high-frequency current as a choke coil. This reliably prevents the high-frequency current from entering the microphone case via the pin. It isthus possible to effectively suppress the generation of noise resulting from an electromagnetic wave.
In a more preferable aspect, each of the pins comprises a pin main body penetratingly provided on the connector base, a cylindrical chip holder comprising an electric insulator and having one end attached to an end of the pin main body which islocated inside the microphone case, and a metal cap that covers the other end of the chip holder so as to be electrically insulated from the pin main body, the chip type inductor element is placed in the chip holder, and the pin main body and the cap areelectrically connected via the chip type inductor element.
Further, an elastic conductive material is placed between one terminal portion of the chip type inductor element and the pin main body and between the other terminal portion of the chip inductor element and the cap. Thus, even if an externalstress is applied to the pin, particularly its cap side, the chip type inductor element can be protected from the external stress. Further, a reliable electric connection state can be established.
Moreover, a metal net is used as the conductive material. This makes it possible to reduce the resistance value of the connected part. Furthermore, the metal net can be easily obtained and machined and is inexpensive. This minimizes anincrease in costs associated with the containment of the chip type inductor element in the pin.
An output connector for a condenser microphone, and more specifically, to a technique for preventing an electromagnetic wave of a high frequency generated by, for example, a cellular phone from entering amicrophone case through an output connector.
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