| 摘要 |
PURPOSE:To suppress the heat of a current driving circuit and to attain the long service life and the stable operation of a semiconductor laser by varying the amplitude of a high frequency AC current to be superimposed on a DC current corresponding to the detection of an error due to the increment of a noise when reproducing information. CONSTITUTION:The semiconductor laser 12 in an optical pickup 11 is lit by permitting the DC current from a DC current driving circuit 13 and an AC current with high frequency from a high frequency current driving circuit 15 to flow after being superimposed. The light of the laser 12 is converged on an objective lens in an optical system 16, and an optical disk is irradiated with the light, and reflected light is detected with a photodetector, then, information is reproduced. An error detection circuit 18 detects the error quantity of a reproducing signal from a reproducing signal processing circuit 17, and controls the quantity of superposition of the AC current of the circuit 15 so as to set the number of errors (the generated number of noises in the laser 12) less than a constant value via a D/A converter 20, thereby, the heat of the circuit 15 is suppressed without attaching a specific temperature control means. |
