| 摘要 |
PROBLEM TO BE SOLVED: To record data while preventing fluctuation in the irradiation time of laser light. SOLUTION: A controller 11 generates a clock signal RCK synchronized with a record data WD and a modulation data MD. In synchronism with the data MD, a phase comparator section 12, an oscillator section 13 and a frequency divider section 14 generate a signal LCK having a period equal to 1/Kb (Kb is an integer larger than 1) of the data interval of a data having shortest data length and having a constant duty ratio and then generates pattern signals SE1, SE2, SE3 based on the data MD and the signal LCK. Based on signals PCD1-PCD3 from a microcomputer 60, signal holding sections 21, 22, 23 generate a reference signal which is delivered to which sections 31, 32, 33. Furthermore, the switch sections 31, 32, 33 are controlled by the signals SE1, SE2, SE3 and a laser diode 45 is driven based on a signal RLM added with a selected reference signal thus controlling laser power. Since the signal LCK has a constant duty ratio, fluctuation in the irradiation time of laser light can be prevented. |
