| 摘要 |
PURPOSE:To accurately perform a recording or a reproducing by providing a driving power source control means for controlling an output of a laser driving power source with an output from a laser output detecting means and an output from a transmitted laser beam detecting means. CONSTITUTION:An output of a semiconductor laser 21 is detected by the laser output detecting means 22, and at the same time, light intensity of a laser beam via an objective lens 26 is detected by the transmitted laser beam detecting means 33. Then, a bit of control information is outputted by the driving power source control means (voltage computer circuit) 40 in receiving a value detected by the laser output detecting means 22 ad a value detected by the transmitted laser beam detecting means 33, and the output of the laser driving power source 41 is controlled with this control information so as to keep the output of the semiconductor laser 21 at a fixed value. Consequently, even when the objective lens 26 is contaminated with dust, etc., the light intensity required for recording or reproducing information on an optical information recording medium 30 is kept constant. By this method, the information recording or reproducing can securely be performed. |
