GB338068A - Improvements in and relating to driving systems for electromagnetic loud speakers - Google Patents

Abstract

338,068. Ideal Werke Akt.-Ges. fiir Drahtlose Telephonie. Nov. 25, 1929, [Convention date]. Magnetic instruments. - An electromagnetic driving unit for loud-speakers comprises an armature j, of the shape shown in Fig. 6, torsionally mounted on flat springs i having two limbs o, o<1> which diverge towards the clamping strips k with respect to the rotary axis x-x of the armature, the limbs being provided, preferably near their clamped ends, with recesses r or with interposed small plates of resilient material. The parts are so dimensioned and arranged that up to a large amplitude of the armature the elastic restoring force increases to the same extent as the magnetic attracting force but beyond this it increases so rapidly that even with a very heavy load on the armature and a narrow magnetic air gap, the armature will not strike against the magnet poles. The magnet system may be of the two-pole, double-acting or single acting types or as shown may comprise four laminated poleshoes b secured by screws c to projections d on a base plate e and abutting against the ends of a large horseshoe magnet a carried by the base plate. The base plate also carries a resiliently yielding support h which can be adjusted by a screw (not shown) to centre the armature in the air gaps and on which the cross bars s of the springs i are clamped by strips k and screws m. The rod n connects the armature with. a diaphragm.