Playback unit for a long-playing record of a time division multiplexed audio signal
US4022986A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1974 |
| Grant date | May 10, 1977 |
| Priority date | — |
| Expiry date | Apr 29, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B27/30
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
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. I…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.