JPS56148734A - Magnetic disc - Google Patents

Abstract

PURPOSE:To make high-density recording possible with a simple device by setting plural pieces of information signal areas and servo signal areas alternately on the track circumference of a disc substrate surface, and forming magnetic films of a stripe shape or the like in the servo signal areas. CONSTITUTION:While a magnetic film is uniformly formed in the information signal areas 2 on a disc substrate 1, magnetic film corresponding to mutually different frequencies f1, f2 are formed in a strip shape alternately to f1, f2, f1, f2... from the outside toward the inside in the servo signal areas 3. A servo mechanism is so constituted that the center of the magnetic head travels at the boundaries of the areas f1 and f2. Namely, if such a disc is revolved at a constant rotating speed, and the magnetic head is fed onto the disc surface, the two signals of f1, f2 are induced intermittently from the magnetic head, whereby tracking control is accomplished well. Hence, with such constitution, the high-density recording of a narrow tracking width is accomplished with the simple constitution.