| 摘要 |
PURPOSE:To simplify the constitution and to make small the size, by making unnecessary mechanical movement device in radial direction, through optoelectronical track selection. CONSTITUTION:Three information tracks 9 are formed concentrically on a memory disc 3, and they are contained in a mirror cylinder 6 together with a motor 4, lens 2, semiconductor laser 1 and photodetector 5 to constitute a compact memory device. The light of semiconductor lasers 1-1-1-3 is modulated respectively with the information of tracks 9-1-9-3 and it is fed back to the light emission section of the original semiconductor laser. The change in this feedback is detected with photodetectors 5-1-5-3, and the selection of the information track 9 can be made by only selecting the output terminal of the corresponding photodetector 5 to the track 9 to be desired for readout with the switch 7, and the optical movement device in radial direction for track selection is made unnecessary. |
