| 摘要 |
PURPOSE: To finely adjust a read spot position for a track to be read by extracting a low frequency signal processed to a control signal in an electronic circuit processing a signal supplied from a laser diode and supplying it to an electric machine means. CONSTITUTION: This device is constituted so that an electronic control circuit connected to a periodical electric signal source 24 is provided, and a read beam is made be moved periodically in the direction crossing the track direction, and an amplitude of its movement is made smaller than a read beam size, and the frequency of the movement is made smaller than a mean frequency that the read beam is modulated. Further, the signal S supplied from a semiconductor diode laser 6 is processed by electronic detection circuits 25, 9, 26, 27 and the control signal Sr is led out by a low band filter 26 to be supplied to the electric machine means. Thus, the hourly averaged position of the read spot is fine adjusted for the position of the track to be read. |
