| 摘要 |
486,514. Loud-speakers. COMPAGNIE NATIONALE ELECTRO-L.L. Sept. 3, 1936, Nos. 24165 and 24166. Void. Convention dates, Sept. 3, 1935 and Aug. 24, 1936. [Class 40 (iv)] In a moving-coil loud-speaker comprising a cone 5 attached to a support for the coil 4, a centring device 6, made of thin sheet metal and preferably that known under the Registered Trade Mark " Duralumin," is supported by a screw 7 engaged in a stud 8 threaded into the centre polepiece 1. The member 6 has a serrated rim to facilitate its attachment to the cone and is formed with three spiral slots each extending over 120‹ and mutually spaced by an angle of 120‹. The device 6 is resiliently supported on the screw 7 by small discs 10 of fibre or of the substance known under the Registered Trade Mark " Bakelite ". In an alternative arrangement, Figs. 3, 4, a thin disc 6 of metal extending across the inner end of the cone 5 is formed with parallel slots 6a. The disc 6 acts to reproduce the high-frequency sounds, and the portion of the cone 5 between the member 6 and the coil former is preferably stiffened. The inner end of the air-gap communicates with a closed chamber formed by a cap 11 secured to the pole-plate 2. Dimensions of the cone, centring device, and of the spiral slots are given in the Specification. |
