Video camera tube

[3] A cathode-ray tube was successfully demonstrated as a displaying device by the German Professor Max Dieckmann in 1906; his experimental results were published by the journal Scientific American in 1909.

They had attempted to generate an electrical signal by projecting an image onto a selenium-coated metal plate that was simultaneously scanned by a cathode ray beam.

[17][1] Among the first to design such a device were German inventors Max Dieckmann and Rudolf Hell,[12][18] who had titled their 1925 patent application Lichtelektrische Bildzerlegerröhre für Fernseher (Photoelectric Image Dissector Tube for Television).

[38] This is among the first patents to propose the use of a "low-velocity" scanning beam and RCA had to buy it in order to sell image orthicon tubes to the general public.

[17][1] The image dissector has no "charge storage" characteristic; the vast majority of electrons emitted by the photocathode are excluded by the scanning aperture,[18] and thus wasted rather than being stored on a photo-sensitive target.

[44][45] After Hungarian engineer Kálmán Tihanyi studied Maxwell's equations, he discovered a new hitherto unknown physical phenomenon, which led to a break-through in the development of electronic imaging devices.

In 1924, while employed by the Westinghouse Electric Corporation in Pittsburgh, Pennsylvania, Russian-born American engineer Vladimir Zworykin presented a project for a totally electronic television system to the company's general manager.

[56] The iconoscope was presented to the general public at a press conference in June 1933,[57] and two detailed technical papers were published in September and October of the same year.

[63][64] The EMI team under the supervision of Isaac Shoenberg analyzed how the Emitron (or iconoscope) produces an electronic signal and concluded that its real efficiency was only about 5% of the theoretical maximum.

[65] It was used for an outside broadcast by the BBC, for the first time, on Armistice Day 1937, when the general public could watch in a television set how the King laid a wreath at the Cenotaph.

This tube is essentially identical to the super-Emitron, but the target is constructed of a thin layer of isolating material placed on top of a conductive base, the mosaic of metallic granules is missing.

[66][67][68] The image iconoscope is essentially identical to the super-Emitron, but the target is constructed of a thin layer of isolating material placed on top of a conductive base, the mosaic of metallic granules is missing.

[71] The original iconoscope was very noisy[63] due to the secondary electrons released from the photoelectric mosaic of the charge storage plate when the scanning beam swept it across.

[41][82] Henroteau was among the first inventors to propose in 1929 the use of low-velocity electrons for stabilizing the potential of a charge storage plate,[83] but Lubszynski and the EMI team were the first engineers in transmitting a clear and well focused image with such a tube.

[18] The first fully functional low-velocity scanning beam tube, the CPS Emitron, was invented and demonstrated by the EMI team under the supervision of Sir Isaac Shoenberg.

[77][85] The EMI team kept working on these devices, and Lubszynski discovered in 1936 that a clear image could be produced if the trajectory of the low-velocity scanning beam was nearly perpendicular (orthogonal) to the charge storage plate in a neighborhood of it.

[75][76] On the other side of the Atlantic, the RCA team led by Albert Rose began working in 1935 on a low-velocity scanning beam device they came to dub the orthicon.

[41][81][90] The orthicon's performance was similar to that of the image iconoscope,[91] but it was also unstable under sudden flashes of bright light, producing "the appearance of a large drop of water evaporating slowly over part of the scene".

[62] A combination of the image dissector and the orthicon technologies, it replaced the iconoscope in the United States, which required a great deal of light to work adequately.

[95][failed verification] An image orthicon camera can take television pictures by candlelight because of the more ordered light-sensitive area and the presence of an electron multiplier at the base of the tube, which operated as a high-efficiency amplifier.

However, it tends to flare in bright light, causing a dark halo to be seen around the object; this anomaly was referred to as blooming in the broadcast industry when image orthicon tubes were in operation.

Thanks to the axial magnetic field of the focusing coil, this deflection is not in a straight line, thus when the electrons reach the target they do so perpendicularly avoiding a sideways component.

So many may be ejected that the corresponding point on the collection mesh can no longer soak them up, and thus they fall back to nearby spots on the target instead, much as water splashes in a ring when a rock is thrown into it.

[108][109] The vidicon is a storage-type camera tube in which a charge-density pattern is formed by the imaged scene radiation on a photoconductive surface which is then scanned by a beam of low-velocity electrons.

All vidicon and similar tubes are prone to image lag, better known as ghosting, smearing, burn-in, comet tails, luma trails and luminance blooming.

They have excellent resolution compared to image orthicons, but lack the artificially sharp edges of IO tubes, which cause some of the viewing audience to perceive them as softer.

They were smaller, had lower noise, higher sensitivity and resolution, had less image lag than Vidicons,[107] and were a defining factor in the development of color TV cameras.

[146][147][148][145] Saticons were made for the Sony HDVS system, used to produce early analog high-definition television using multiple sub-Nyquist sampling encoding (MUSE).

The technique would not work with the baseline vidicon tube because it suffered from the limitation that as the target was fundamentally an insulator, the constant low light level built up a charge which would manifest itself as a form of fogging.

While CCDs were tested for this application, as of 1993 broadcasters still found them inadequate due to issues achieving the necessary high resolution without compromising image quality with undesirable side-effects.