| 摘要 |
PURPOSE:To reduce the processing time of a defective sector by measuring the light quantity of a luminous flux which passed through a recording medium so as to detect a defective sector on an optical information recording medium due to dust and flaw. CONSTITUTION:An optical information recording and reproducing device consists of a drive controller and a disk drive, the light beams from an optical head 22 are irradiated onto an optical disk 29, the magnetization direction of the type of material of the disk 29 is changed by a magnetic field of the bias magnetic field coil 27 to record information. In reproducing the recording, a continuous light beams with a low energy are irradiated to read the difference from the type of material thereby reproducing the information. A reflected luminous quantity supervisory circuit 40 having an optical detector, an adder and a comparator is provided between an automatic tracking AT/automatic focus AF circuit 24 and a motor drive circuit connected to the head 22 of the drive side. Then the luminous quantity of the luminous flux via the disk 29 is measured by the circuit 40 to discriminate a defective sector due to dust and flaw thereby reducing the processing time of the defective sector.
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