| 摘要 |
<p>1448239 Optical playback of disc records MCA DISCO-VISION Inc 23 Oct 1973 [24 Oct 1972] 49385/73 Heading G5R A disc record is played back by reflection of a beam of radiation provided by a head which can be moved over the disc, the path of the beam relative to the head being adjustable. As shown, an optical playback head 14 is carried on a pivoted arm 16 to swing across a rotating disc record 20 and is supported at least partly by a air-bearing shoe 50. A laser beam from the head is modulated and reflected by the record 20 back along the same path, which includes at least two reflections between two mirrors 54 and 56, until it is diverted by a beam-splitter (30), Fig. 2 (not shown), to a detector (40). A track-following servo system, Fig. 4 or 5 (not shown), adjusts the pivoted mirror 54. As the head 14 moves towards the centre of the record 20, the air bearing becomes weaker and the head is increasingly supported mechanically, under the control of a cam-and-follower assembly (132), Fig. 7 (not shown), connected to a cable 130.</p> |
