| 摘要 |
PURPOSE:To attain stable operation of a laser diode by allowing the laser diode to emit light intermittently for operation so that an average output comes to a prescribed value at the time of reproducing the information. CONSTITUTION:At the time of reproducing the information, a laser diode LD is allowed to emit light intermittently for operation by a switching transistor TR so that an average output comes to a prescribed value. That is, at the time of recording and at the time of reproducing, there is a difference of 30 folds as for a necessary output, therefore, when a peak output is set to an output of the extent of about 1/several of an output required at the time of recording, the duty is operated intermittently being selected suitably, an average output comes to an output required at the time of reproducing. In such a way, information can be reproduced without damaging the recording information of the surface of an optical card, and also, since the laser diode LD executes a stable operation, generation of noise to be caused by an unstable operation is prevented. |
