| 摘要 |
PURPOSE:To facilitate the easy positioning of a photodetector so that two light spots are arrayed on a straight line on an optical disk and at the same time confirming completely that both light spots are set on the same track, by putting the 1st light spot on a specific track having the information different from other peripheral tracks on the disk and controlling the irradiating position of the 2nd light spot so that the reproduction signal produced by the 2nd light spot and sent from the specific track has the maximum level. CONSTITUTION:The 1st light spot 25 is put on a specific track 102 having the information different from other peripheral tracks on an optical disk 5 by the timing decided in a power supply application mode, a system resetting mode, etc. In this case, the bias voltage of a control circuit is controlled together with the actuator driving voltage that actuates the 2nd light spot 26 so that the reproduction signal produced by the spot 26 and sent from the track 102 has the maximum level. While an actuator 35 is driven by the actuator driving voltage supplied in the said timing mode with the timings other than said ones. Thus both spots 25 and 26 are irradiated on the same track with high stability. |
