DISK, PRODUCTION OF DISK AND DISK RECORDING AND REPRODUCING DEVICE

摘要

PROBLEM TO BE SOLVED: To execute recording with a method excellent in mass productivity without the possibility of an accidental erasure by forming reproduction-only tracks inclusive of the rotating speed conditions of a disk in a position preceding to recording and reproducing tracks consisting of guide grooves, on a plastic disk substrate, then forming recording films allowing rerecording on the surface of the recording and reproducing tracks and the reproduction-only tracks. SOLUTION: The information reading-out start part on the innermost side of a magneto-optical disk is provided with an already recorded part 7 where the information signals relating to the recording and reproduction conditions are recorded. The information including the information on the rotation speed conditions of the disk is recorded in this already recorded part 7. For this purpose, pits 8 of raggedness and the guide grooves 4a for recording tracks are simultaneously formed on the surface of the plastic substrate 4 and perpendicularly magnetized films 5 are formed by vapor disposition or sputtering on the surfaces of the pits 8 and the guide grooves 4a and are provided thereon with protective layers 6 consisting of dielectric substances. The conditions of the rotating speed are read prior to the recording and reproduction operation and the rotating speed is regulated.