| 摘要 |
PURPOSE:To form a shape of a recording pit to a shape being nearly a true circle or an ellipse by setting a preheating period for irradiating a laser beam to an extent that it is not recorded in an unrecorded period between recording pulses. CONSTITUTION:A recording signal 1a is supplied to a pulse generating circuit 2 and an MMV circuit 3. The pulse generating circuit 2 supplies an output signal 9b corresponding to a recording signal 1 to an adder circuit 4. The MMV circuit 3 synchronizes with a fall of the recording signal 1, and supplies an output signal of a pulse width T to a switching circuit 5. Also, to the switching circuit 5, an output signal 11d from a constant-voltage circuit 8 is supplied. The switching circuit 5 sets an output signal 12 to OV, only when an output signal 10 is in a section of 'H', and in other time, an output signal 11 is outputted (e) as it is. Accordingly, to the adding circuit 4, an output signal 9b and an output signal (e) are supplied, and when both the signals are added, an output signal 13 as shown by (f) is obtained.
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