Magnetic data record in plate form - has two thin magnetic films and thick intermediate layer of non-magnetic material

摘要

The disc type magnetic data record carrier consists of a carrier material (S), a magnetic film (1) for the pick-up of servo information, a non-magnetic intermediate film (Z) and a second magnetic film (2) for the pick-up of data-information. The carrier material (S) is typically provided on both sides with foils. The film strength of each magnetic film is typically 0.06 to 0.6 um and the non-magnetic film has a film strength of 10 to 30 times that of the weaker films. The ratio of the coercive force between the first and second metal magnetic films is between 0.5 and 2.0. The surface of the second magnetic film is provided with a protective film.