| 摘要 |
PROBLEM TO BE SOLVED: To obtain optimum recording conditions and to enable stable and high density recording and reproducing by performing trial write in a duty detection system suitable for the characteristic of a phase transition type optical disk. SOLUTION: A reproducing signal 10 is pulsed by a binarizer 201, and a duty shift of this binary signal is converted into a voltage level by an integrator 202, and is fed back to a slice level of the binarizer 201 via an LPF 203. Thus, the slice level V2 is controlled to make 50% of the duty of the signal 10. On the other hand, upper and lower envelopes are detected from the signal 10 by detectors 211 and 212, and these are added up by an adder 213, and then the added envelope is halved by an attenuator 214 to detect an envelope average level V1. A difference between the levels V1 and V2 is obtained by a subtractor 221. Then, optimum power is obtained by an A/D converter 230 provided for the purpose of digitalizing a trial write signal to be subjected to averaging processing by a CPU at the time of packaging drive for trial write in the duty detection system, and hence uniform recording marks are formed to stably record and reproduce information in high density. |
