Eidofor

Eidofor color television projector

Eidophor ( born Eidophor ) is a light-valve video projector suitable for receiving television images on movie theater screens. The name is composed of the Greek words ειδω and φορέας , meaning "image" and "carrier". The technology is based on the deformation of a viscous fluid surface by an electron beam commuting it. The resulting microscopic irregularities are converted into an image by special slit optics.

Principle of Operation

The technology was developed in 1939 at the Higher Technical School of Zurich , under the direction of Fritz Fischer ^[1] . The first valid sample was made in 1943, and American patent No. 2 391 451 was obtained on December 25, 1945 ^[2] . In the post-war years, Paramount Pictures and XX Century Fox cinema companies experimented with Eidofor type projectors, trying to create a network of “television cinemas” into which films are broadcast centrally on high-definition television channels . Along with the creation of widescreen cinema systems, this step was another way to reduce losses due to the outflow of viewers from cinemas associated with the broadcasting ^[3] . However, due to the FCC's refusal to allocate frequencies for film distributors , the project failed.

In projectors of the Eidofor system, the light flux is generated not by a phosphor , as in picture tubes , but by a powerful light source, the brightness of which is modulated by a special cathode ray tube . A layer of conductive oil deposited on a hemispherical mirror target inside this tube is illuminated through the narrow slits of another flat reflector with a powerful carbon arc or xenon lamp ^[4] . The reflector is in the focus of the spherical target in such a way that the light passing through its slits returns to the opaque reflective stripes and then back to the lamp. Therefore, without exposure to the liquid of the electron beam, the light does not reach the screen due to the extinction of the optical system. When a video signal appears, the target receives a proportional static charge from the beam, which leads to deformation of the oil surface and a change in the direction of reflection. The stronger the electron beam current , the greater the static charge of the corresponding point of the target, the more distorting the surface of the liquid and deflecting the light ^[5] .

The deviation of the rays by the distorted surface of the oil allows them, thanks to the Schlieren effect , to hit the screen. As a result, a contrast image is created on the latter, the brightness of which depends only on the power of the lighting system. Therefore, the luminous flux of Eidofor projectors is approximately 80 times higher than the same parameter for the best video projectors with high brightness picture tubes ^[1] . The viscosity of an oil bearing the same name as the whole technology is selected in such a way that the shape of its surface is maintained for the duration of the entire television field ^[6] . To obtain a color image, the color television system with sequential transmission of color fields developed by CBS ^[7] was used at first. However, due to the short operation of such a standard, after the adoption of the NTSC system, Eidofor projectors began to be built on the basis of three identical tubes. Each of them forms its own partial color-divided image, which is projected by a separate lens through the corresponding filter ^[8] . Projectors of this type can reproduce the image on screens up to 50 square meters with a sharpness of up to 1000 lines ^[6] .

Application

NASA Space Center Control Panel Operated by Eidofor Projector

Eidofor systems have been in operation for several decades, but have remained extremely cumbersome and difficult to maintain. Each of the cathode-ray tubes required constant pumping of air, and to maintain the viscosity of the oil at the right level, the temperature of the units was controlled by a special cooling system ^[1] . Therefore, the use of projectors was limited to special areas, for example, in cinemas and concert venues. American analogue “ Talaria “ General Electric’s production was installed at NASA's Space Center ^[9] . The request to the United States to sell such a projector for installation in the Soviet MCC was refused, because the incorporated technical principles were considered as dual-use technology ^[10] . Therefore, in the USSR, the Moscow Research Television Institute (MNITI) specifically for equipping the MCC developed a similar system called "Ariston" ^[9] . Serial production of these projectors for institutions was established at the Lviv Television Plant ^[11] .

Currently, the system is considered obsolete and has given way to DLP projectors , also based on the light-valve principle, but more compact and easy to maintain. Modern digital film projectors use semiconductor micromirror arrays, and provide a luminous flux of comparable or higher power, filling large screens with high-quality images.

Notes

↑ ¹ ² ³ Peter F. Yanczer. The Eidophor Television System . Early Television Museum. Date of treatment January 1, 2016.
↑ Fischer Friedrich Ernst. Process and appliance for projecting television pictures . U.S. Patent 2,391,451 (December 25, 1945). Date of treatment January 1, 2016.
↑ Film History, 2003 , p. 32.
↑ Dzhakonia, 2002 , p. 151.
↑ Dzhakonia, 2002 , p. 152.
↑ ¹ ² Dzhakonia, 2002 , p. 153.
↑ Eidophor (1946 ) . Early Television Museum. Date of treatment January 1, 2016.
↑ Technique of Film and Television, 1971 , p. 6.
↑ ¹ ² Science and Life, 2005 , p. 49.
↑ Igor OSIPCHUK. Nikolai Osaulenko, the developer of a health-friendly television set: “a nail is the basis of many of my inventions, for one of which I was awarded the USSR State Prize in the field of science and technology” (Russian) . “Facts” (June 9, 2004). Date of treatment December 31, 2016.
↑ Everything you need to know about front projectors (Russian) . "Hifinews." Date of treatment December 30, 2016.

Literature

V.E. Dzhakonia. 7. 5. Systems of a large television screen // Television. - M .: “Hotline - Telecom”, 2002. - S. 148-155. - 640 s. - ISBN 5-93517-070-1 .

S.I. Kataev, V.N. Ulyanov, A.S. Khudyakov, N.A. Gerasimov. Pairing Eidofor with a color television system (Russian) // " Cinema and Television Technology ": journal. - 1971. - No. 11 . - S. 6-13 . - ISSN 0040-2249 .

V. Samsonov. The history of the MCC: work, joy, ordeal (Russian) // " Science and Life ": journal. - 2005. - No. 8 . - S. 48-54 . - ISSN 0028-1263 .

Kira Kitsopanidou. The Widescreen Revolution and 20th Century-Fox's Eidophor in the 1950s // Film History: collection. - 2003 .-- January ( no. 15 ). - P. 32-56 . - ISSN 0892-2160 .

Links

Larry J. Hornbeck. From cathode rays to digital micromirrors . Technical Journal (September 1998). Date of treatment January 2, 2017.

[dis-1] ¹ ² ³ Peter F. Yanczer. The Eidophor Television System . Early Television Museum. Date of treatment January 1, 2016.

[2] Fischer Friedrich Ernst. Process and appliance for projecting television pictures . U.S. Patent 2,391,451 (December 25, 1945). Date of treatment January 1, 2016.

[_c722fb6638851fe1-3] Film History, 2003 , p. 32.

[_ad1d0b1cbe0d937f-4] Dzhakonia, 2002 , p. 151.

[_ad1d0b1cbe0d937c-5] Dzhakonia, 2002 , p. 152.

[field-6] ¹ ² Dzhakonia, 2002 , p. 153.

[7] Eidophor (1946 ) . Early Television Museum. Date of treatment January 1, 2016.

[_48ac170e41dd9b7a-8] Technique of Film and Television, 1971 , p. 6.

[mniti-9] ¹ ² Science and Life, 2005 , p. 49.

[10] Igor OSIPCHUK. Nikolai Osaulenko, the developer of a health-friendly television set: “a nail is the basis of many of my inventions, for one of which I was awarded the USSR State Prize in the field of science and technology” (Russian) . “Facts” (June 9, 2004). Date of treatment December 31, 2016.

[11] Everything you need to know about front projectors (Russian) . "Hifinews." Date of treatment December 30, 2016.