Iconoscope

from Wikipedia, the free encyclopedia

The iconoscope (from ancient Greek εἰκών eikon “image” and ancient Greek σκοπεῖν skopein “to look at”, “to look”) is an image pickup tube that was patented by Vladimir Zworykin in 1923, but was first built in 1926 by Philo T. Farnsworth . The electronic scanning method of the iconoscope replaced the mechanical scanning method of the Nipkow disk (see also mechanical television ).

history

Historical classification

  • Vladimir Zworykin (English spelling of his name) applied for a patent in the United States on December 29, 1923, which was granted on December 20, 1938 with US Patent No. 2,141,059.
  • Similarities with Philo Farnsworth's probe tube led to a lengthy patent dispute.
  • This was the basis for the development of modern image converters.
  • The iconoscope was the first electronic basis that made it possible to transmit recordings directly in daylight.
  • With the iconoscope technology, the 441-line standard was officially established in 1937.
  • Together with the Braun tube in the television receiver (the actual television tube , also known as the kinescope ), the iconoscope replaced mechanical television .
  • The GDR made reparation payments to the Soviet Union using Ikonoskop technology .
  • The iconoscope technology of television cameras was replaced by the orthicon technology.

Olympic Games 1936

Walter Bruch behind the "Olympic Cannon"

The iconoscope was also known as the image catcher in Germany and was the camera that was used for historic television broadcasting at the 1936 Berlin Olympic Games . This camera was developed by Emil Mechau at Telefunken and operated by Walter Bruch, among others, during the Summer Games, where it was known as the "television cannon" at the time. The Ikonoskop was the world's first mobile television camera . It had an image resolution of 180 lines and 25 frames / s, the lens had a focal length of 1.60 m , a weight of 45 kg and a total length of 2.20 m.

functionality

Image from Zworykin's “Television System” patent application

Small grains of photosensitive material (e.g. potassium hydride ) are separated by an insulator layer on a metal foil (e.g. aluminum , see Fig. 34–36). Each of these grains forms a small plate capacitor with the metal foil . If an image is projected onto the light-sensitive side with the help of lenses (see Fig. 37), the grains emit electrons depending on the brightness of the individual image point, which induces negative charges point by point on the metal foil .

The metal foil is located in a Braun tube (see Fig. 27, but also 25/26 and 28–30), in which it is scanned line by line by an electron beam. The electrons are repelled by the induced charge at the bright image points, but at the dark points they contribute to a current that flows from the aluminum plate to the transmitter.

This basic structure was slightly modified up to the commercial development. Among other things, it was not the metal foil that was scanned, but the light-sensitive side.

Zworykin compared the mosaic of photosensitive grains with the realities in the human eye.

Web links

Individual evidence

  1. ↑ a b Vladimir Zworykin: Television System. United States Patent Office, accessed May 21, 2009 .
  2. ^ "Augsburger Allgemeine" of December 29, 2008, section Das Datum
  3. ↑ H.-T. Schmidt: OSW studio technology. Retrieved May 21, 2009 .
  4. ↑ Fernsehmuseum1- You are in the area: Walter Bruch. Retrieved May 5, 2020 .
  5. ↑ Vladimir Zworykin, The Iconoscope - A Modern Version of the Electric Eye , Proceedings of the Institute of Radio Engineers, Jan. 1934.