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      Vladimir Kosma Zworykin
                 1889-1982
Camera tubes
The electronic eye
                              The first page
Farnsworth Image dissector [9]
Iconoscope [9]
Super Emitron [9]
Image Orthicon [9]
Vidicon [9]
Orthicon [9]
Super Emitron  1936 [2]
Early Philips Iconoscope 1935 [2]
Nickname "the bedpan"
RCA 3" Image Orthicon 5820
The huge 4,5" EEV 9224 Image Orthicon with in front a 2/3" Vidicon tube.
This EEV 9224 was the successor of the RCA5820.
  RCA's Rose, Law and Weimer managed in 1945
  to produce the first usable Image Orthicon.
  The biggest difficulty was to make the grid with
  1600 holes per square mm, this was important
  for the image resolution of the tube.
  Also the glass target plate with a thickness of
  0,005 mm was not easy to fabricate in those
  days. The normal working temperature of the
  tube was about 30 degrees Celsius and was 
  stabilised with a heater and fan.
Philips Iconoscope tube 1930 [13]
The first Philips Iconoscope tube early 1930's.
To the right the complete experimental camera
for 180 TV lines displayed in the Philips laboratory.
  The 3" 5820 workhorse tube of the
  1950's and 1960's, used in the
  RCA TK-11 AND TK-30 camera.
Electron Multiplier section
This Electron  Multiplier section from this RCA tube is an improved version of the one from the image dissector tube of Philo Farnsworth.
Camera tube schematic diagrams
Zworykin 1949
With an 5826 tube.
    Philo Taylor Farnsworth
            1906-1971
An overview of the camera tube history
 In the early days of television, moving picture transmission was only possible by mechanical transmitters and 
 receivers. The development of the CRT which could be used as an electronic replacement of the mechanical 
 receiver forced the researchers to produce an electronic eye to replace the mechanical flying spot principle from 
 Manfred von Ardenne which was more or less successfully used for the transmission of film in the beginning with 
 30 and later with 180 scanlines.
 Campbell Swinton described this all electronic television  system in Nature June 1908, info can be found at the site 
 of Bairdtelevision.
 Several inventors clamed to have the first ideas for single or double sided target camera pickup tubes, the 
 Hungarian engineer Kolomon Tihanyi  claimed the invention of the Iconoscope storage principle, which later was 
 used by Zworykin. 
 There was a patent of Kolomon Tihanyi's 1926 Application úRadioskop but the British one was never 
 granted. Several other people inbetween 1924 and 1931 claimed to file the first pickup tube patents like Francois
 Charles Pierre Henrouteau (1928) George J.Blake and Henry D.Spooner (1924),  Riccardo Brunni(Photoscope 
 1928) and S.I. Kataev ( Iconoscope 1931)
  The first patent (not granted) for the Iconoscope of  Zworykin (RCA) dates from 1923 based on his early ideas from 
 1919, the American Philo Taylor Farnsworth however claimed he had his first ideas of his Image dissector tube in 
 1922 when he, at an age of 14, made a drawing of his TV pickup tube on the blackboard of his school.

 Farnsworth patented his all electronic TV system on Jan 7, 1927. By Sept 7, 1927 he was able to send a single 
 horizontal line of light on the face of a CRT. The dissector tube however, became never a successful television 
 pickup device and was mainly used to scan film and dia-positives, this was the result of a lack of sensitivity, it was 
 in fact a cold cathode tube.
 TV broadcast was not easy with the dissector tube because of the enormous amount of light needed for an 
 acceptable picture, despite all he managed to transmit  from  August 25 1934 for ten day's live electronic television, 
 he was the first ever. Kenjiro Takayanagi made the first camera tube for Japan and presented his all electronic TV 
 system also in 1936. The next year German Nazi TV started regular broadcasting in Berlin using their first 
 Iconoscope cameras at the Olympic Games in 1936.
 Farnsworth's Image dissector and his TV display tube the "oscillite" a low pressure gas filled CRT, were no match 
 for the mighty RCA (David Sarnoff). This was the beginning of the all electronic TV age, it was a race of patents 
 which RCA eventually won. RCA didn't wanted to pay royalties but would only buy the dissector patent of Farnsworth 
 for use of the multiplier section in the future development of the Image Orthicon. With this arrangement ended the 
 great struggle between Farnsworth and RCA.

 The first Iconoscope tubes that Zworykin developed for RCA were about 1000 times more sensitive than the 
 Farnsworth Image dissector which had no storage capacity,  the Iconoscope tubes used the "gathering effect" to 
 collect electrons coming from the photo cathode to the mica target. But only 5-10% effectivity was reached, another 
 disadvantage of the Iconoscope tube was shadow forming, due to the irregular form of the electron cloud in front of 
 the target. This could be seen as dark spots on the receiving image on the upper left and bottom left of the picture.

 The successor of the Iconoscope was the Super Emitron, patented in May 1934 by Hans G. Lubszinski and Sydney 
 Rodda of EMI  England, the patent later went to RCA due to an earlier conception date. The image of the Super  
 Emitron was not formed by the photo-emission to the target plate itself, but by photo-electrons which came free by 
 the illumination of a Photo Cathode in front of the target. This tube was much more efficient than the standard 
 Iconoscope tube.
 Even more progress was made with the Riesel-Iconoscope. In the Riesel tube there was a second photo sensitive 
 Cathode in the form of a ring nearby the target. From this Cathode a constant flow of slow electrons was dripping to 
 the target. (rieseln = dripping) This became a new shadow compensation to overcome the the old problem. The 
 Riesel Iconoscope  tube was only used on the mainland of Europe and had a 10 times higher sensitivity than the 
 regular Iconoscope tube.

 Harley Ambrose Iams and Alberts Rose (RCA) developed in 1938 the Orthicon tube, although it was theoretically a 
 simpler design than the Iconoscope, building this tube was much more difficult. This Orthicon tube was used for 
 the first NBC/RCA TV broadcasting in NewYork June 1940.
 It took another five years to build a new and better one, the Image Orthicon. It used the Electron Multiplier section 
 like the Image Dissector tube which was developed by Philo Tayler Farnsworth. Development of the first 3" Image 
 orthicon started in 1944 with the LM5 for the use in guided missiles followed by the smaller MIMO (miniature image 
 orthicon). This was a great advance for the postwar TV industry, RCA presented the fist public demonstration Oct 
 25 1945, the production was extended for a short time with the building of the huge 4,5" Image orthicon which was 
 even more sensitive but much larger than the former ones and also more expensive. Image Orthicons were valued 
 and insured for 500-1000 pounds at the BBC in 1950, in those days a lot of money !
 To overcome this, the Vidicon tube was eventually developed in 1950, there was no need to be superior to the 
 Image orthicon, but to produce camera tubes in a more economic way. Vidicon tubes were used until 1970 when 
 the first solid state CCD camera came on the market. Even today the Vidicon and Vidicon-like tubes are still used in 
 the industrial, medical and military environment.

[13]
The electron gun on the above is the same as the one on the picture. Probably all that is left today of this early 1935 Philips camera tube.
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This is an RCA 1846 Iconoscope used during WWII in the first missile guidance system.