| 摘要 |
PURPOSE:To satisfactorily execute the recording and reproducing of the optical recording medium of a different track pitch with a same optical information recording and reproducing device by controlling the optical spot diameter of a recording and reproducing surface on the basis of the type of the track pitch of the using recording medium. CONSTITUTION:The track pitch of a recording medium 1 to be detected by a track pitch identifier detecting circuit 17 is supplied to a logic control circuit 19. On the other hand, a reflected light from a recording and reproducing surface 2 is detected by a detecting system 7 and a focus dislocating signal 8 and a tracking error signal 9 are outputted. The focus dislocating signal 8 is supplied through an adding circuit 15 to comparators 21 and 22. A control circuit 19, to which the outputs of the comparators 21 and 22 are given, outputs a control signal 26 to turn on a switch 11. Thus, an automatic focus control system to include an automatic focus control circuit 16 goes to an operating condition and the focus position of an optical spot is controlled so that the focus dislocating signal 8 can be zero and the position of the recording and reproducing surface 2 can be followed. |
