GB838159A - Improvements relating to electro-acoustic í¡í¡ - Google Patents

Abstract

838,159. Sound-receiving and transmitting devices. SIEMENS EDISON SWAN Ltd. Nov. 19, 1958 [Dec. 6, 1957], No. 38062/57. Class 40 (4). In a transducer of the balanced ring armature type the outer periphery of the armature 7 is disposed between two annular washer-like members 4, 5 secured in position between the outer annular portions 1 of the transducer magnetic structure, and the radial width of each of the members 4, 5 is significantly greater than that of the outer annular portions 1. The embodiment shown is intended to function as a transmitter and to this end its resonant frequency is lowered, to render it less sensitive to noise frequencies above the signal frequencies, by reducing the stiffness of the moving system. This is effected by the insertion of the spacing annulus 3 between the members 4 and 5 so that the armature 7 is located in position solely by the magnetic influence of the magnetic structure. The members 4 and 5 are of magnetic material and their large radial width compared with that of the ring magnets 1 provides, in effect, an increased radial width for the ends of the ring magnets 1 adjacent the armature 7 so that a greater tolerance for the diameter of the armature 7 and for that of the spacing annulus 3 is allowed. In the embodiment described with reference to Fig. 2 (not shown), which is designed to function as a receiver, the resonant frequency is raised to widen the range of frequencies over which it is sensitive by increasing the stiffness of the moving system. The spacing annulus 3 is omitted and the armature 7 is clamped between the members 4 and 5. Specification 705,330 is referred to.