Optical disk (storage medium)

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Storage medium
Image plate
Bilplatte2.jpg
Structure of an image plate
General
capacity 10 min (picture + sound)
size 21 cm (diameter)
origin
idea 1970

An optical disk is a series of storage technologies in which video data and mostly also sound are recorded on a rotating disk.

First developments

In 1927 the Scottish inventor and television pioneer John Logie Baird developed the first electromechanical television system ("Televisor") that could record and display images with a resolution of only 30 lines using a Nipkow disk . Baird managed to record this television signal on vinyl, but it was not possible to reproduce it from the vinyl at the time. It was only in the 1980s that the British engineer Don F. McLean succeeded in restoring signals from these records with the help of computer technology and making them visible again.

TED image plate

Image record player TP1005 from Telefunken from diagonally above / front
Photo record player TP1005 from above

The first better known video disc was presented in June 1970 in Great Britain and the Federal Republic of Germany together with a suitable player (video disc player). The presentation in the Federal Republic took place in the AEG high-rise in West Berlin in front of representatives of the press. A recording by the singer Manuela with her song Alles und much more was shown . The system worked according to the TED system (abbreviation for " TE levision D isc"), which had been developed by a company consortium consisting of AEG-Telefunken , Teldec and Decca within five years. At this point in time only black and white images could be reproduced, but series models with color display were announced for 1972.

The only reader for TED image disks on the German market, the TP1005 from Telefunken, was finally presented in 1973 at the Berlin radio exhibition and went on sale in early 1975. The device was 46 cm wide, 16 cm high and 31 cm deep and had a weight of approx. 14 kg due to its steel housing, which earned it the nickname “flat safe”.

Disadvantages of the TED system were, in addition to the high prices, the high sensitivity of the plates and the short playing time. The TED system disappeared from the market in Germany after less than two years.

technology

The TED picture plate has a diameter of 21 cm, consists of a thin, flexible plastic film in a protective cover made of cardboard and offers space for around ten minutes of picture and sound. It is scanned mechanically with a diamond needle and, when played, floats on an air cushion on which it rotates 45 times faster (1500 revolutions per minute) than a conventional, analog record. Two PAL half-images recorded using the CAV method are recorded per revolution .

plates

TED plates were produced in Germany by the companies Decca , Institute for Modern Teaching Methods (under the brand name "TELE-Med"), Teldec -Intertel, Telefunken , Ullstein AV , UFA -ATB and Videophon . The overall program encompassed the areas of "popular knowledge" (hobby, science, culture, countries and cities, health and fitness), "entertainment" (music, fiction, cartoon, sport), "children and youth program" and "training / advanced training" (Language courses, job, medical training).

Examples of TED panels:

  • Germany triple (first audiovisual book in the world, contained eight optical discs)
  • Sunken Cities - Living Gods (Documentary about the South American Maya peoples)
  • Exotic animal lexicon (animal lexicon in 26 episodes, two image plates contained one episode)
  • Speed ​​Racer (the first anime to be broadcast on German television)

Video disk

From 1970 the main factory of the Deutsche Grammophon Gesellschaft (later PolyGram) in Hanover was working on the development of the video image plate. With this video disc, a new optical system ("laser vision") working with laser beam scanning was presented. The format of the records corresponded to the long-play record and was produced on a redesigned record tandem press.

Laser disc

With the Laserdisc , Philips presented a further development of the TED system in 1980 , which works purely optically with laser beam scanning. It is not to be confused with a digital process. However, it offers the best picture quality of an analog medium. The stored data are located under a smooth protective layer as tiny elongated depressions ( pits ) in a thin metal film on the plastic carrier (plate) and are arranged along a spiral track. Up to 54,000 still images or 34 minutes of moving images, but also a mixture of the two, could be stored on an image plate with a diameter of 30 cm. This laser disc is probably the best-known analog optical disc.

Today the laser disc is practically insignificant. In many respects, however, it is regarded as the predecessor of the Compact Disc or the later CD-ROM, which was introduced in 1982 and initially only designed for sound recording .

Examples of films on LaserDisc:

and music:

present

Optical disk formats still in use today are mainly:

HDTV- compatible formats:

  • CD-ROMs with stored movie files with modern compression, e.g. B. DivX or H.264 , depending on the material, can also save HD films in the order of up to an hour. If a PC is used as a playback device, more demanding codings such as B. the Hi10P profile possible.
  • the HD DVD ,
  • the Blu-ray Disc , as well
  • the HD-VMD as a still little-known variant.

The term “image plate” is rather uncommon for today's formats.

literature

  • Joachim Polzer: Video disc TED image disc . Dissertation, Academy of Performing Arts in Prague, Prague 2010 (German, abstract in English and Czech).

Web links

Individual proof

  1. ↑ “From the plate to the tube. TV programs from the micro-groove - sensational new development presented in Berlin ”. Schwäbische Zeitung of June 25, 1970, p. 5

See also