| 摘要 |
PURPOSE:To permit detection of an off-track of an erasing light beam and mis-erasing by the off-track by providing mark signals which can discriminate that a sector discriminator, data field and erasing light beam exist in adjacent tracks. CONSTITUTION:The mark signals M1, M2, etc., capable of discriminating that the sector discriminator ID, the data field DF to record data and the erasing light beam exist in the adjacent tracks are provided to the sector format of an optical disk. An address reproduction circuit 1 reads an address from the ID of a reproduction signal 100 for recording and reproducing light beams and outputs an address detection signal 103, etc. The signal 103 is then applied to an M1 gate generating circuit 2 and an M2 gate generating circuit 3. The circuits 2, 3 generate an M1 gate signal 104 and an M2 gate signal 105. The signals 104 and 105 detect that the erasing input beam exists in even or odd number tracks by separating the signals M1, M2 of a reproduction signal 101 for the erasing light beam with time. The detection of the off-track of the erasing light beam and the prevention of the mis-erasing are thereby attained. |
