| 摘要 |
PURPOSE:To discriminate optical disks whose reflection factors are different from each other, by detecting whether a detected value is higher or lower than a set value, and discriminating the optical disk, based on said detection. CONSTITUTION:When an optical disk 1 is loaded, it is rotated at a prescribed linear velocity, and also, the convergent light of laser of a prescribed output is radiated to the optical disk 1 through an objective lens L2, and the reflected laser light which is reflected erroneously by a track and a pit is detected by a detector 4. Subsequently, it is compared with a reference voltage outputted from a reference voltage source 6b by a comparator 6c through an adder circuit 5 and an amplifier 6a, and when the detecting signal has become higher than the reference voltage, a rectangular wave corresponding to its signal waveform is outputted. In accordance with whether this rectangular wave signal exists or not, whether the optical disk is an additional type or a reproduction exclusive type is discriminated.
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