| 摘要 |
PURPOSE:To set a tracking line without decreasing the area of a data storage area by providing recessed and projecting parts onto a data recording face alternately, using the recessed and projecting parts as data tracks and using the boundary between the recessed and projecting parts as tracking lines. CONSTITUTION:The titled recording medium is constituted by providing the recessed part 3a and the projecting part 3b alternately in parallel to a recording area 2 provided on the major face of a card type base 1 as the data storage area. The substance information optically is provided as layers to the storage area 2. The recessed part 3a and the projecting part 3b are constituted with a step being 1- several tens microns to the upper face of the storage area 2 and it is preferred to form the boundary E between the recessed part 3a and the projecting part 3b as sharp as possible. The the tracking is attained by radiating a tracking light beam to the boundary E between the recessed part 3a and the projecting part 3b, detecting the luminous quantity change of the reflected light so as to detect the tracking error. |
