| 摘要 |
PURPOSE:To correctly control the emitting light quantity so as to obtain an optimal reproducing power in a data area capable of recording/reproducing information even when a returned light beam from a recording medium to a semiconductor laser exists. CONSTITUTION:The control means for the output of a semiconductor laser of an optical information reproducing device reads the target value of emitting light quantity out of a ROM 7 or a RAM 15 by means of a CPU 5, sends a corresponding instruction value to a DAC(1) 9, supplies a driving current to a semiconductor laser 1 through a V-I converter 11, detects the emitting light quantity of the semiconductor laser 1 by means of a light detecting means 4 and controls the emitting light quantity of the semiconductor laser 1 so that the error between the detected value of the output of an A/D converter 6 and a target emitting light quantity becomes zero. A target emitting light quantity Rp on the area B of a track capable of recording/reproducing is stored in the ROM 7 and a value obtained by measuring the emitting light quantity on a track area A for exclusive reproducing use, while making a supplied current to the semiconductor laser 1 the same value, and being a different value from Rp is stored in the RAM 15 as a target emitting light quantity RP' on the track area A. |
