Dynamisches Mikrophon

摘要

1,055,747. Telephone instruments; diaphragms. ELECTRO-VOICE Inc. Oct. 1, 1963 [Oct. 1, 1962], No. 38658/63. Heading H4J. A transducer comprises a ferromagnetic plate having a cylindrical opening, a non - magnetic member mounted on the plate and consisting of two interconnected portions, a first portion on one side of the plate having an orifice coaxial with the opening in the plate and a second portion on the opposite side of the plate forming a rim extending about the opening, a ferromagnetic member abutting the orifice in the first non-magnetic portion and having a cylindrical portion disposed coaxially within the opening in the ferromagnetic plate, a diaphragm fitted within the rim of the second portion of the non-magnetic member, and a cylindrical voice coil mounted on the diaphragm and disposed within the space between the ferromagnetic plate and the cylindrical portion of the ferromagnetic member. In a microphone as shown, Figs. 2 and 3, a cylindrical permanent magnet 16 is fitted into a ribbed central orifice in a non-magnetic disc 32, which carries a ferromagnetic disc 22 and is integral with a non-magnetic ring 34 on the other side of the ferromagnetic disc 22, the two non-magnetic portions 32, 34 being joined by means of pillars 36 passing through apertures 30 in the magnetic disc 22 or by means of a cylindrical flange encircling the disc 22, Fig. 8 (not shown). The flat peripheral portion 54 of a diaphragm 10, which has a central dome 58 surrounded by flutes 56 tangential to a circle concentric with the diaphragm, fits within the ring 34 and is cemented to the magnetic disc 22. An indentation 26 in the periphery of the magnetic disc 22 is filled by a projection 62 of the non-magnetic disc 32, and a groove 64 permits the passage of leads from terminal lugs 20 to apertures 60 in the diaphragm 10 and thence to the voice coil 14 which moves in the gap 52 between the magnetic disc 22 and the permanent magnet 16. A U-shaped yoke 48, 50 completes the magnetic circuit. A receiver, Figs. 9-11 (not shown), uses a diaphragm with radial flutes and a ring magnet connected by a ferromagnetic back plate to a hollow cylindrical central polepiece having a closure member of cloth to provide acoustic damping.