GB1442468A - Loudspeakers - Google Patents

Abstract

1442468 Moulding loud-speakers SONY CORP 27 June 1974 [2 July 1973 24 Nov 1973] 28609/74 Heading B5A [Also in Division H4] The outer peripheral suspension 20 (Fig. 1) and/or the centring suspension 28 of a moving coil loud-speaker are/is formed in a two part mould 23, 26 (Fig. 5). The suspension 20, 28 is made from carbon fibres mixed into an elastic material such as synthetic rubber (e.g. nitryl butadiene rubber, styrene butadiene rubber or isobutyl-isoprene rubber) natural rubber or synthetic resin (e.g. soft foamed polyurethane). The carbon fibres are arranged radially in the moulded suspension. In manufacture of the suspension 20, oversize carbon fibres, together with a different material (e.g. stearic acid, sulphur or carbon black) are mixed with styrene butadiene rubber in a mill where the carbon fibres are reduced to desired size (e.g. length 0À3 to 0À8 mm.) The mixture 22 is put at the centre of mould 23, 26 which defines an annular groove 24 corresponding to the suspension 20. Mould part 26 is pressed down and the mixture 22 is spread out radially to fill the annular groove 24 whereupon the mixture is vulcanized at a temperature above 140‹ C. A somewhat similar arrangement is used for making the suspension 28.