The image dissector was an early all-electronic television camera tube invented by Philo Farnsworth. Philo Taylor Farnsworth ( August 19, 1906 – March 11, 1971) was an American inventor
Most experimental television systems in the 1920s and 1930s made use of an electromechanical system, usually a Nipkow disk combined with a single photoelectric cell for scanning an image and creating an electrical output. Mechanical television was a Television system that used mechanical or Electromechanical devices to capture and display images A Nipkow disk (sometimes Anglicized as Nipkov disk also known as scanning disk, is a mechanical geometrically operating Image scanning device invented by A similar device operating in reverse was used to project the image onto the picture screen.
In 1922, Philo Farnsworth, a teenage farmboy in Idaho, discovered that one could use a cathode ray tube to generate an electrical television signal without the need for a mechanical scanning device. The image dissector focused an image onto a layer of caesium oxide, which emitted electrons proportional to the intensity of the light. Only a small portion of the electron stream passed through an aperture to the electron collecting plate, representing a single point of the television image. Electromagnets were used to focus and deflect the electrons so that the total image was sequentially scanned.
Farnsworth's Image Dissector was successfully demonstrated and patent applications were made in 1927. This was the first successful demonstration of a fully electronic television system. Farnsworth continued making improvements to his system, and by 1929, image clarity and number of lines of resolution exceeded the achievements of the mechanical television systems.
The Image Dissector is not very efficient because the bulk of the electrons produced do not pass through the aperture and are discarded. Very bright lighting is required for it to be used as a television camera.
The Iconoscope invented by Vladimir Zworykin improved on Farnsworth's invention by combining the photosensitive material at each point with a capacitor so that all the electrons were captured. The Iconoscope was the name given to an early television camera tube in which a beam of high-velocity Electrons scans a photoemissive Mosaic. Vladimir Kozmich Zworykin (Владимир Козьмич Зворыкин ( July 30, 1889 - July 29, 1982) was a Russian-American A separate beam of electrons was then used to scan over the image surface, resulting in an electrical current proportional to the quantity of stored electrons at each point.
The Farnsworth Image Dissector was commercially produced for applications where very bright lighting existed, such as monitoring the interior of industrial furnaces.
Farnsworth also earned income from the production of the Iconoscope television cameras, because Zworykin's device was based on several patents that Farnsworth owned.