GB459884A - Improved magnetic sound record carrier - Google Patents

Abstract

459,884. Magnetic sound-records. ALLGEMEINE ELEKTRICITATS-GES., 2, Friedrich Karl Ufer, Berlin, and I. G. FARBENINDUSTRIE AKT.-GES., Ludwigshafen, both in Germany. July 17, 1935, No. 20391. Convention date, July 18, 1934. [Class 40 (ii)] A magnetic sound-record carrier consists of a support bearing a single layer of ferro-magnetic particles which are substantially completely insulated from one another by an insulating film and all lie at the same distance from the smooth surface of the support. The magnetic material may be iron powder produced from iron carbonyl and mixed with an insulating material in the form of a highly viscous organic colloid so that each individual particle is coated with an insulating layer. The insulating material may be celluloid or acetyl cellulose, cellulose ether, polyvinylic or polyacrylic compounds, natural or artificial rubber or the like. The mixture is applied to a metal or other band, and, after the mass has solidified, the support may be replaced by a paper carrier or a film. To ensure that the magnetic particles do not remain spaced from the support, the layer may be passed through a magnetic field, or it may be softened temporarily to such an extent that the individual particles gravitate to the support, such action being assisted, if desired, by the action of a shaking magnet which imparts mechanical vibrations to the support. As shown in the drawing, the viscous material is fed on to an endless rotating metal band 3 from a container 1 and may be distributed thereon by a scraper 4, a permanent magnet 5 which draws the particles on to the band, or a heating arrangement 6 in combination with a shaking magnet 7. The rate at which the mass is fed from the container to the band-and the rate of movement of the band are so adjusted that a single layer of particles is provided on the band. The band is carried through a drying oven 8 to harden the mass, and a strong support in the form of a paper band or film is applied or placed underneath the magnetizable layer. A film is applied to the magnetic band from a funnel 9, and with the magnetic band is lifted by a blade 10 from the support 3, being wound, after solidifying under the action of heat or a stream of gas, on to a drum 11. The iron particles may be all of the same size, for example 10 to 15 Á, and have similar magnetic properties. Specification 418,096 is referred to.