PURPOSE: To improve the quality of a reproduced information signal by preventing the duty ratio of pulses of the reproduced information signal from varying owing to a lengthwise increase in the size of pits formed on an optical disk.
CONSTITUTION: The modulated pulse signal A of the information signal from an information signal source is supplied to a rising edge detecting circuit 2 and a falling edge detecting circuit 3 to generate a rising edge pulse B and a falli9ng edge pulse C. The rising edge pulse B is delayed by a specific quantity through a delay circuit 4 to set an SR-FF6 and the falls edge pulse C is delayed by a specific quantity through a delay circuit 5 to reset the SR-FF6. Here, the delay quantity of the delay circuit 4 is made larger than the delay quantity of the delay circuit 5 to make the pulse width D of the modulated pulse signal outputted by the SR-FF6 shorter than that of the modulated pulse signal A; and their delay quantities are properly set to obtain pitch length on the optical disk corresponding to the pulse width of the modulated pulse signal A.
GOTO NORIO
TOKUJIYUKU NOBUHIRO
KONISHI KATSUO
