| 摘要 |
<p>1530812 Optical playback of recorded television signals PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 30 Sept 1975 [3 Oct 1974] 27107/78 Divided out of 1530811 Heading G5R A television record of the type described in Specification 1,530,811, in which the spatial frequency detectable areas along a track represents a first carrier wave frequency-modulated with luminance information while lateral undulation of the track represents further carrier waves modulated with other information, is played back by apparatus comprising a radiation source and an objective system supplying radiation via the record to four photo-electric detectors 15, 16, 17, 18 disposed in the effective exit pupil of the objective system and in four different quadrants of an imaginary x-y coordinate system having its origin at the centre of the exit pupil and its x-axis in the track direction, means 22, 23 for adding the outputs of the detectors in the first and fourth quadrants and in the second and third quadrants respectively and means 25 for deriving the sum or difference of these two addition signals to yield the first carrier wave signal St, means 20, 21 for forming a first resultant signal from the outputs of the detectors in the first and second quadrants and a second resultant signal from the outputs of the detectors in the third and fourth quadrants, these resultant signals being either both the sums or both the differences of the outputs of the relevant detectors, and means 24 for deriving the difference between the first and second resultant signals and hence the further carrier wave signals Sr.</p> |
