For the image generation it was necessary to develop a similar tube in the transmistter, denominated as an image converter or camera tube. It was described by the first time by G. Holst in the later twenties. However, the photo- cathode camera tubes have been developed from the
(a) Schematical of the iconoscope, showing the disposal its structural elements.
Iconoscope, a Greek word meaning: eikon = image, and skopein = observation, invented in 1930 by Y.K.Zworykin. Originally, this was a trade name copyrighted by RCA. (a)
Basically the Iconoscope is an optical electrical device. (b) In this way, through an optical system the black and white image is focused on to a mica plate. One side of this plate has a mosaic of tiny globules of photosensitized material especially treated for high photoelectric emission. An electron gun and associated bean deflecting system are mounted in the neck of the Iconoscope. The electron beam is made to sweep regularly the mica plate in a zigzag pattern originating the process as known as scanning. (c) The scanning is started by the flow of current through the set of horizontal and vertical deflecting coils and in this way originating the variable raster.
For instance, in the Brazilian television system, there are 625 lines in each picture, which is repeated 25 times per second.
(b) Illustration of the iconoscope originally invented by Vladimir Kosma Zworykin.
Differente quantities of electrons leave the beam in the bright or dark parts of the image, so varying the current in an electric circuit connected to the electron gun in sympathy with the variation in light and shade. Finally, the varying electric current or signal, from the camera is amplified and modulated by the transmitter. (d)
Since the invention of the Iconoscope, many were the types of television cameras launched in the market. Among them are:

- The Emitron, improved in England by J.D.McGee. (f) Even so, in the photoconductive television camera family other interesting types are:

- The Vidicon, similar to the Orthicon, but in place of target plate coated with a photo emissive elements it was replaced by a thin film made with Antimony Sulphied, which becomes conductive under the influence of light.

- In the Plumbicon, another type of television camera, where for the photo emissive layer, it was used a chemically modified Lead Oxide. (g)

(d) The Dr. Vladimir Kosma Zworykin with its invention the iconoscope. Photo archive RCA
During the WWII, the RCA in the USA, made many researches to develop a
(c) Ilustração do processo   de varredura  da imagem em ziguezague.
camera tube for operation at low light intensities for military applications purpose. The result was the Image Orthicon a, low inertia, and highly sensitive camera with good definition, circa 100 lux for studios takes.
In this way it became the standard camera tube for black and white television either for studio as well as for reporting applications. In 1970, W.S Boyle and G.E. Smith working for Bell Laboratories, USA, developed a new type of semiconductor storage device, named CCD or charge-coupled device. (n) As an electrical optical device, the CCD has a principle basic completely different when compared with the aforementioned thermionic television cameras using photosensitize material for the detection of electrons. In the CCD cameras, the electron detection is made by storing the charges, which are proportionally absorbed in small wells or discret elements displayed on a CHIP, known as PIXELS, which is an acronym for PICTURE ELEMENT.
Nowadays the CCD is used for the manufacturing of the modern television cameras for home, industrial or scientific applications. (o)
e) Mechanical scanning equipment, used at RCA-NBC experimental television station in 1928. Photo RCA
Dr. V.K. Zworykin, inventor of the iconoscope, shown with a new type of picture tube launched in the market by RCA circa 1945 under the tradename of "Image Orthicon". This new type of picutre tube was developed by Drs. Albert Rose, Paul K. Weimer and Harold B. Law of the RCA research staff originally based in the improved cathode-ray tube technology used for the manufacturing of RADAR, LORAN, SONAR and some typef of RADIO DIRECTION FINDERS during the WWII.
RCA archives

(f) Schematical of the collector of image, called of Super Emitron launched in the market circa 1937, that when compared with the iconoscope was distinguished for the disposal of the photoelectric screen, that was separate of the bulkhead or mosaic. In it:

1- Photoelectric screen
2 - Accelerator
3- mosaic
4 - Focus coil
5 - Cathodic rays beeans
6 - Cathode


(o) Illustration of a TV camera with CCD detector
(l) Antique type of television camera.
Radio News
(h) Diagram of the Image Orthicon.
(i) The Image Orthicon manufactured by the American company RCA circa 1950 (j) The television camera tube type XQ 1029R made by the American company Amperex circa 1960 (m) The television camera circa 1949. Radio News