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Media > Video > TeD part 1

1970 June 24

The quest for home video
TeD video disc
Page 1: Early development

TeD inventors
Source: Decca Record Company July 1970, Terra Media Archives

Initially known simply as 'the video disc' or the Teldec television disc, TeD was first announced at a press conference in Berlin on 24 June 1970. It was developed by a joint team from two German companies, consumer electronics manufacturer AEG-Telefunken and record company Teldec (itself a joint subsidiary of AEG-Telefunken and Britain's Decca Record Company). The engineers responsible are shown above (l to r): Dr Gerhard Dickopp (AEG-Telefunken), Hans Joachim Klemp and Horst Redlich (both Teldec) and Eduard Schüller (AEG-Telefunken).

Source: Decca Record Company July 1970, Terra Media Archives

Programme information was stored in the form of ridges in the surface of a thin, flexible PVC foil disc, which was claimed to be sufficiently robust to withstand 1,000 playing. The main technological breakthrough was the vertical recording method that reduced the track pitch (the distance between tracks on each revolution) to 0.007mm, and increased the rotational speed to 1,500 rpm, making it possible to record 130-150 'grooves' per millimetre, compared with the typical 10-13 grooves on an audio disc. This increased the available bandwidth from around 15 kHz to 3 MHz. The tracks were read by a 'pressure pick-up', which translated the surface of the ridges via a piezo-electric crystal into an electrical signal.
    Tracking was controlled not by the pick-up resting within the walls of a groove but by a mechanical coupling on which the pick-up mounting is supported (a principle used in 1907 by the Spirograph film projector).

Source: Decca Record Company July 1970, Terra Media Archives

There was no turntable. The rotation of the disc at 1,500 rpm created a thin cushion of air between the disc and a fixed plate. Vertical movement of the disc was kept to within 0.05mm. Eight-inch discs could store five minutes of programming, 12-inch discs about 12 minutes. In 1970 basic players were expected to cost around £50, a de luxe version with autochanger about £100.

Page 2: Moving to the market.
Chronomedia 1970
  The quest for home video index

Page created 24 June 2000 (30th anniversary of the original press conference)