| 摘要 |
PURPOSE:To improve a reproduced signal to noise ratio by monitoring, reproducing the adjacent tracks of recording tracks by a light beam to detect a crosstalk and making recording at the adequate power so as to suppress the crosstalk. CONSTITUTION:A photodiode 7 detects a recording beam A when the bit length of the recording bit 20 of a reproducing beam B protrudes from the recording width of the recording track 19 and the beam A begins to be included in the beam B. The detection signal E inputted from a laser driving circuit 12 in this stage contains also the signal of the beam A in the detection signal G of the photodiode 7 amplified by an amplifier 9 and therefore an AND circuit 10 turns on at the same timing as the timing of the signal E. A gate circuit 11 inputs the output signal from the photodiode 7 to the circuit 12. The circuit 12 decreases the power of the laser A until the above-mentioned output signal is no more produced. The crosstalk in the stage of reproduction is thus decreased by about 6dB. |
