| 摘要 |
PURPOSE:To improve the reading margin in the stage of reproduction by forming the waveform of recording power at the large power level in the front edge thereof and the small power level except the front edge thereby decreasing the deviation in the duty ratio which arises with the medium characteristic, the relative speed of the medium and recording head and focusing conditions at the low average power level. CONSTITUTION:The light power to be emitted from a semiconductor laser diode 8 is proportional to the driving current (d) to be supplied and therefore the 1st power level corresponding to the electric current I1 and the 2nd power level corresponding to the current (I1+I2) exist as the power level. The light is eventually irradiated on a storage medium 7 at the large 2nd power level during the time T1 at the front end of a pit and at the small 1st power level except the front edge in the stage of forming the pit. The pit is thus formed at the large power level at the front edge thereof which is particularly of a problem at the boundary between the presence and absence of the pit and therefore the deviation in the duty ratio aristing from the influence of the medium characteristic, focusing conditions, etc. is improved. |
