Iconoscope

This was the first fully electronic system to replace earlier cameras, which used special spotlights or spinning disks to capture light from a single very brightly lit spot.

[1][2] A research group at Westinghouse Electronic Company headed by Zworykin presented the iconoscope to the general public in a press conference in June 1933,[3] and two detailed technical papers were published in September and October of the same year.

[4][5] The German company Telefunken bought the rights from RCA and built the superikonoskop camera[6] used for the historical TV transmission at the 1936 Summer Olympics in Berlin.

[10][11] The main image forming element in the iconoscope was a mica plate with a pattern of photosensitive granules deposited on the front using an electrically insulating glue.

The system is first charged up by scanning the plate with an electron gun similar to one in a conventional television cathode ray display tube.

Additionally, the time needed for the electrons to reach the upper portions of the screen was longer than the lower areas, which were closer to the gun.

It based on a new, hithero unknown physical phenomenon which was discovered and patented by physicist Kálmán Tihanyi in Hungary in 1926, however the new pehonmenon became widely understood and recognised only from around 1930.

Tihanyi's Radioskop patent was recognized as a Document of Universal Significance by the UNESCO, thus became part of the Memory of the World Programme on September 4, 2001.

In July 1925, Zworykin submitted a patent application for a "Television System" that includes a charge storage plate constructed of a thin layer of isolating material (aluminum oxide) sandwiched between a screen (300 mesh) and a colloidal deposit of photoelectric material (potassium hydride) consisting of isolated globules.

[2] However the quality of the transmitted image failed to impress to H P Davis, the general manager of Westinghouse, and Zworykin was asked to work on something useful.

[23] As head of television development at Radio Corporation of America (RCA), Zworykin submitted a patent application in November 1931, and it was issued in 1935.

[24] Meanwhile, in 1933, Philo Farnsworth had also applied for a patent for a device that used a charge storage plate and a low-velocity electron scanning beam.

[26][27] The iconoscope was presented to the general public in a press conference in June 1933,[3] and two detailed technical papers were published in September and October of the same year.

Zworykin holding the iconoscope tube, in a 1950 magazine article
A graphic from Kálmán Tihanyi's "Radioskop" patent from 1926 (part of the UNESCO's Memory of the World Programme ) [ 12 ]
Zworykin's patent diagram of a UV-microscope 1931. [ 13 ] The apparatus is similar to the iconoscope. The image entered through the series of lenses at upper right, and hit the photoelectric cells on the image plate at left. The cathode ray at the right swept the image plate, charging it, and the photoelectric cells emitted an electric charge in variance with the amount of light hitting them. The resulting image signal was carried out the left side of the tube and amplified.
Diagram of iconoscope
Two iconoscope tubes. The type 1849 (top) was the common tube used in studio television cameras. The camera's lens focused the image through the tube's transparent "window" (right) and onto the dark rectangular "target" surface visible inside. The type 1847 (bottom) was a smaller version.
Iconoscope and mosaic from a TV camera, circa 1955.
Iconoscope television cameras at NBC in 1937. Eddie Albert and Grace Brandt reprised their radio show, The Honeymooners-Grace and Eddie Show for television.