GB293131A - Improvements in or relating to electrically-operated sound transmitting, reproducing, or recording devices - Google Patents

Abstract

293,131. Trouton, M., and Wireless Music, Ltd. April 1, 1927. Magnetic instruments. -In a telephone or like instrument in which an armature or reed moves about a real or virtual axis, the armature and co-operating pole are so constructed and arranged that that portion of the armature nearest the axis would touch the pole surface before, or approximately simultaneously with, the portion furthest from said axis. In one instrument described, the axis about which the magnet pole is adjusted lies between the pole and the support for the armature or reed. In the reed instrument shown in Figs. 1, 2, the reed n, shown in dotted lines, is supported on the flat upper surface c of a pillar a provided with lugs e on which is pivotally mounted the magnet system, comprising a U- shaped permanent magnet f with laminated polepieces g surrounded by coils h and separated by an a,ir-gap k above which the reed is arranged. The magnet system is adjustable by a screw l about the axis o, which is slightly below the reed support and at a distance from the pole determined by formulµ given in the Specification. In a modification, the correct angular relation between the reed and pole for one amplitude of vibration may be given during manufacture and a translational adjustment provided. In a further modification, a vibratory member projects at right angles from a cross-bar, clamped at its ends, the part of the vibratory member nearer the cross-bar being stiffened by webs, the remainder, which is relatively flexible, constituting the armature. The torsion of the cross-bar provides the requisite restoring force. The magnet system is pivoted for adjustment purposes about an axis, which may be coincident with the axis of rotation of the armature or at substantially the same distance from the nearer edge of the pole surface as the axis of rotation of the armature. The Provisional Specification also describes an instrument in which separate means are provided for adjusting the magnet system and the inclination of the need. The U-shaped magnet carries a cylindrical guide member which moves in bearings integral with the base piece. Other modifications are suggested in the Provisional Specification.