| 摘要 |
PURPOSE:To reject the magnetic distortion due to eddy current and inductive skin current produced in the magnetic circuit, by forming the conductive resin film on the surface of the metal member, constituting the magnetic circuit of microphone such as electromagnetic type. CONSTITUTION:On the surface of the member constituting the magnetic circuit such as magnet 1C, center magnetic pole 2C, yoke 3C, magnetic pole disc 4C and sheet metal 10C, the conductive resin material including carbon or aluminum powder is coated, and the film is formed by enclosing the surrounding. With the film formed, the electric resistance is high and none of eddy current and induction skin current is produced on the film surface coated. But, at the inner wall of the film layer in contact with the metal member is low in resistance since it is contacted with the electric resistance of the metal member in parallel, the eddy current and inductive skin current produced on the surface of metal can easily be shorted to increase the sound quality. |
