| 摘要 |
PURPOSE:To record a signal with each proper recording beam power for every disc to be used to obtain a proper reproduced signal by finding out a beam power value maximizing reference wave reproducing voltage and minimizing secondary higher harmonics distortion reproducing voltage and using the beam power value as proper recording beam power. CONSTITUTION:The operation is set to a recording mode and laser light rays having different beam power values are successively irradiated from a power variable laser generator 15 and recorded at different positions on a disc 6 respectively while increasing the beam power value gradually until the value reaches a prescribed value. Subsequently, the operation is switched to a reproducing mode and reproduced laser light obtained from the disc 6 is converted into signal current corresponding to the size of a pit by an information signal reproducer 16. Reference wave voltage e1 and secondary higher harmonics distortion voltage e2 are extracted from band filters 181, 182 respectively through an amplifier 17 and A/D-converted and the digital values are supplied to a memory and an operator 22. Then, the beam power value minimizing the voltage e2 during the period that the voltage e1 is maximum is found out. The beam power value is converted into an analog value by a D/A converter 23 and the analog value is supplied to the power-variable laser generator 15. Thus, data can be recorded with the optimum recording beam power to the disc to be used. |
