| 摘要 |
PURPOSE:To obtain an optical disk capable of preventing incorrect copy by making the disk so that a protecting code can not be read-out from a signal recorded on the disk. CONSTITUTION:In a track 1 arranged like a spiral state at a prescribed pitch Q, coded digital data are formed in the peripheral direction of the spiral at a prescribed interval P1AB as information pits 1A, 1B having a prescribed width in the radial direction of the spiral and lengths corresponding to digital data in the peripheral direction of the spiral. In the optical disk, information pits 1A, 1B are formed by changing the width of the information pits symmetrically to the center line of the track 1 with a maximum amplitude smaller than the pitch Q of the tracks in accordance with a modulation signal modulating the data. |
