U.S. Philips Corporation

Kees Teer

Peter J Janssen

Frederik Leonard Sangster

Laurentius Antonius De Bot

A system comprising a playback unit and an associated long-playing record on which sound information is recorded in a time division multiplex code on several tracks. Upon reproduction the same track is scanned n times with the aid of a beam of light before this beam of light is directed to the next track. With the aid of a sampling gate the pulses comprising the sound information in time division multiplex code and associated with a first sound channel are sampled with the aid of said sampling gate while during a second revolution pulses from a second sound channel etc. are sampled. In order to operate this sampling gate in synchronism with the scanning of said pulses the playback unit comprises first synchronizing means responding to pulses also comprising the sound information. Furthermore, at the commencement of each track, starting pulses are provided to which second synchronizing means respond. The output signals thereof control the first synchronizing means and a pivoting mirror reflecting the beam of light which after the record has made n revolutions with one and the same track being scanned is pivoted so that the beam of light is directed to the next track to be scanned. In another embodiment the pulses comprising the sound information are distributed in m groups of pulses 1 to n over a track and each group is preceded by a group pulse to which third synchronizing means respond. The output signals of these third synchronizing means control the first synchronizing means.

Playback unit for a long-playing record of a time division multiplexed

A semiconductor pick-up arrangement in which the picked up information is transported through a series of shift elements to an output. Since each information passes another number of shift elements in which the passage of a signal per switching operation is non-ideal, there is a place or time-dependent signal degradation. To obtain a uniform signal degradation the information is applied to an analog shift register of a forward and backward shifting type in which the signal degradation per switching operation at the shift register has been reduced by approximately 50% of that at the series.

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Eindhoven, Netherlands

Kees Teer