MAGNETIC CARD AND RECORDING AND REPRODUCING METHOD THEREOF

• Main Authors: KISHIMOTO MIKIO, ASADA SEIICHI
• Format: Patent
• Language: English
• Published: 19.08.1991
• Subjects: ADHESIVES; CHEMICAL PAINT OR INK REMOVERS; CHEMISTRY; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; CORRECTING FLUIDS; DYES; FILLING PASTES; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; INKS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; PHYSICS; POLISHES; USE OF MATERIALS THEREFOR; WOODSTAINS

PURPOSE:To assure the stable holding of recording information and the recording at a higher density by providing a magnetic layer consisting of hexagonal ferrite as a magnetic material on a substrate and specifying the surface roughness of the magnetic layer to <=0.015 mum center line average height. CONSTITUTION:The hexagonal ferrite has a high coercive force and can stably maintain the recording information against external magnetic fields. In addition, this ferrite has the extremely large Kerr rotating angle of reflected light and contributes largely to the improvement in reproduced output. The surface roughness thereof is specified to <=0.015 mum center line average height. Namely, the quantity of the reflected light from the surface of the magnetic layer is insufficient and the Kerr rotating angle decreases if the surface roughness larger than this value is adopted. A decrease in the reproduced output is then resulted. The Kerr rotating angle of the reflected light is increased in this way and the high reproduced output is expected.