| 摘要 |
PURPOSE:To record additionally information surely with high density by two optical beams, by using a deflector and track grooves where the number of sectors are increased discontinuously from the inside circumference of a disc toward the outside circumference to record information. CONSTITUTION:A recording optical beam 8 and a reproducing optical beam 9 are formed, and they are made incident on the same converging object lens 5 and are so controlled that two beam spots 8 and 9 are an integer-fold length of a desired track interval apart from each other in the radius direction on a disc 10, and the reproducing optical beam spot 9 is so tracked that it is placed in the center of a reference track 11<0> where data are already recorded, and a deflector 4 is used to read data successively at equal pitch by the recording beam 8. Further, the number of sectors per one round is increased discontinuously from the inside circumference of the disc toward the outside circumference with respect to the reference track 11<0> to record data with higher density. |
