GB400119A - Improvements in and relating to moving coil loud speakers - Google Patents

Abstract

400,119. Loud-speakers. ROTHERMEL, R. A., 1, Willesden Lane, London. May 3, 1933, No. 12956. [Class 40 (iv).] A moving-coil loud-speaker comprises an inner core b carried by a magnetic member h and projecting into the recessed part a<1> of a core a carried by the magnetic chassis g, the magnetic circuit being completed through the members g, h. The cone e carrying the moving coil d is attached to the steel ring i which is secured either to the chassis g or bar h before assembly of the whole. The magnet may either be a permanent or an electromagnet, and if the latter, the energizing coil f is arranged around the core a so as to extend to, or nearly to, the end of the recessed part of the core and surround practically the whole of the coil d. In order to prevent any possible magnetic short circuit a plate l of non-magnetic material may be interposed between the cores a, b and this plate may be recessed to receive the core b and thereby serve as a centring and aligning means. Alternatively, the core b may be formed with a heavily copper-plated flange integral therewith or secured thereto, the flange also serving automatically to centre the core b If desired, both cores may be provided or finished with a copper &c. plate. The whole of the loud-speaker is automatically centred and rigidly assembled by a screw bolt m passing through both cores. The coil d may be centred by a corrugated disc connected by members k to the chassis g.