| 摘要 |
1489757 Optical playback apparatus PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 14 Oct 1974 [17 Oct 1973] 12625/77 Divided out of 1489756 Heading G5R [Also in Division G3] The disclosure is included in that in parent Specification but the claims relate to apparatus for playback of a record of the type claimed in that application, the playback apparatus having a source giving a read beam of optical radiation, and a detector for converting the read beam modulated by the information on the record into an electrical signal, the detector output being connected to a high-pass filter and to a low-pass filter for the formation of a high-frequency signal component from which the information signal is derived, and for the formation of a low-frequency signal component from which a low-frequency tracking control signal is derived by phase sensitive detection using a reference signal derived from the record. |
