| 摘要 |
PROBLEM TO BE SOLVED: To improve recording density and a transfer rate of recorded and reproduced data. SOLUTION: In a subtraction circuit 16, a voltage across both ends of a resistance R1 is detected. This detected voltage is proportional to the current flowing to a laser element 10. The laser device 10 is driven with a constant current by other parts except a differentiating circuit 20, and an operational amplifier 18 controls a transistor 14 so that a driving pulse Pt becomes equal to the voltage generated by the flow of the driving current (i) through the resistor R1. A differentiation signal S3 of the driving pulse by the differentiating circuit 20 is added to the output S1 of the constant-current driving circuit at this time, and this summed signal S2 is applied to the base of the transistor 14. Consequently, the rise and fall of the laser element 10 driving current (i) is accelerated. |
