| 摘要 |
PROBLEM TO BE SOLVED: To improve efficiency of a mastering process and to stabilize reading of second information at the time of reproduction, in a disk type recording medium in which the second information (copyright protecting information) is superimposed on first information and recorded. SOLUTION: Recording of the first information is performed by forming a pit string by irradiating an original disk with a first laser beam, while the second information as well as the first information is multiplex-recorded by converging the second laser beam and irradiating a position deviated in the direction of a radius of the original disk of the pit string with it. Thereby, an electroacoustic optical element (light deflector) for recording the second information by wobble of pits conventionally is not required, an exposing time for the original disk is shortened and manufacturing efficiency is improved. Also, at the time of reproduction, reading of such the second information is stabilized by discriminating the value based on a result in which a signal recorded based on the second laser beam is read a plurality of times and integrated. COPYRIGHT: (C)2005,JPO&NCIPI
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