Showing papers by "Dolby Laboratories published in 1980"

Apparatus for scanning variable area optical sound tracks by parallel processing discrete photosensor outputs

Abstract: Apparatus for scanning variable area optical sound tracks wherein a plurality of discrete photo sensors examine small fractional portions of the sound track width. Selection of the number of sensors in relation to photographic grain dimensions results in converting annoying quantizing noise to more tolerable random noise while using a practical number of sensors. Electronic processing of the sensors' outputs reduces impulse noise from dirt and scratches.

Scanning system for reproducing side-by-side optical sound tracks

Abstract: Side-by-side variable area sound tracks are scanned laterally to derive a first signal containing width-modulated pulses which can be demodulated to audio. In order to eliminate the effect of noise on the clear areas of the tracks, the portions of the first signal corresponding to the different tracks are gated to separate bistable circuits whereas each said pulse is initiated by a black-to-clear transition sensed in the scanning but is not terminated until reference instants of time at which it is certain that the clear-to-black transition has been reached.