| 摘要 |
PURPOSE:To read information easily and surely by providing a guide groove for tracking information to be read optically along the information groove to be read optically in the disc-shaped recoroding medium provided with the information groove above. CONSTITUTION:Guide grooves 2 and 4 are provided for information grooves 3 and 5 formed on disc-shaped recording medium 1 (the center is indicated by number 6), and information grooves 3 and 5 are tracked by guide grooves 2 and 4 respectively. |
