| 摘要 |
PURPOSE:To prevent noise from being recorded on a disc in the idle state, where information is not recorded neither reproduced, to extend the life of a semiconductor laser by setting the power of the output light of the semiconductor laser to a lower level in the idle state in comparison with that at the recording time and the reproducing time. CONSTITUTION:In the idle state where signals are not recorded neither reproduced, gate circuits 21 and 24 are opened, and a current corresponding to the potential of an output Vi from a setting circuit 23 of power for idle state is supplied to a semiconductor laser 2. When signals are reproduced, the circuit 24 is closed, and the circuit 21 is opened, and a current corresponding to the potential obtained by adding the output Vi to an output VR from a setting circuit 17 of power for reproducing by an adder 19 is supplied to the laser. When signals are recorded, circuits 21 and 24 are closed, and a current corresponding to the potential obtained by adding outputs Vi and VR to an output VW from a setting circuit 18 of power for recording by the adder 19 is recorded digitally in accordance with the intensity of the signal applied from a terminal A. Thus, noise in he idle state is not recorded to extend the life of the laser. |
