A sectional view of an image orthicon is shown in the below figure. It has three main sections: image section, scanning section and electron. Image orthicon definition, a camera tube, more sensitive than the orthicon, in which an electron image generated by a photocathode is focused on one side of a. The image orthicon (10) was developed during World War II to solve some of the problems of its predecessors in the camera-tube family. These included.
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For instance, a 6. The iconoscope was presented to the general public at a press conference in June and two detailed technical papers were published in September and October of the same year. Early Television Foundation and Museum.
The scene image is projected onto an efficient continuous-film semitransparent photocathode that transforms the scene light into a light-emitted electron image, the latter is then accelerated and focused via electromagnetic fields towards a target specially prepared for the emission of secondary electrons. In AprilFarnsworth submitted a patent application also entitled Image Dissectorbut which actually detailed a CRT -type camera tube. Canera a magnetically focused camera tube there are electrostatically focused vidiconsthe vertical deflection coils are above and below the tube, instead of being on both sides of it.
The target is nearly at ground potential with a small positive charge, thus when the electrons reach the target at low speed they are absorbed without ejecting more electrons. The electron gun structure produces a beam of electrons that is accelerated towards the target. Compared to Saticons, Plumbicons have much higher resistance to burn-in, and comet and trailing artifacts from bright lights in the shot.
Farnsworth applied for a patent for his Television System that included a device for “the conversion and dissecting of light”.
Retrieved March 14, The remaining electrons are then deflected back into the anode,   captured by a special grid   or deflected back into an electron multiplier.
First Voyage into the PDS”. It also has a logarithmic light sensitivity curve similar to the human eye. This tube makes use of the high photoemissive sensitivity obtainable from photocathodes, image multiplication iamge the target caused by secondary emission and an electron multiplier. The original iconoscope was noisy, had a high ratio of interference to signal, and ultimately gave disappointing results, especially when compared to the high orthicoj mechanical scanning systems then becoming available.
Successive stages of the electron multiplier are arranged symmetrically around and back of the first stage. A switch-over to solid-state image sensors rendered much of that equipment imae the investments behind it obsolete and required new equipment optimized to work well with solid-state sensors, just as the old equipment was optimized for tube-sourced video.
The method of extracting the color is similar however. The Institute of Electrical Engineers. This necessitated an additional electrode buried in the target to detect where the scanning electron beam was relative to the stripe filter.
Image Orthicon Camera Tubes
The secondary emission at the imagf produces a pattern of positive charges corresponding point by point with the caamera distribution of the original scene and the thinness of the target allows this charge pattern to be reproduced immediately on its reverse side, i. In JanuaryAmerican inventor and television pioneer Philo T. Therefore secondary electrons are attracted to the dynodes at progressively higher positive potentials; five stages of multiplication are used.
Only one tube was used in the camera, instead of a tube for each color, as was standard for color cameras used in television broadcasting. Originally developed by Toshiba in as chalniconPasecon is a registered trademark of Heimann GmbH from Campbell-Swinton inhe found that a longitudinal magnetic field generated by an axial coil can focus an electron beam.
This adds negative charge to the positive charge until the region being scanned reaches some threshold negative charge, at which point the scanning electrons are reflected by the negative potential rather than absorbed in this process the target recovers the electrons needed for the next scan. Disk rotation was synchronized with vertical scanning so that each vertical scan in sequence was for a different primary color.
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This is maintained at about volts more positive with respect to the photocathode, and the resultant electric field gives the desired acceleration and motion to the emitted electrons towards it. European Patent Office, Patent No. This is maintained at a potential a few volts positive with respect to the wall coating. Hence, for highlights in the scene, the grid of the first video amplifier valve swings in the positive direction.
Each disk consisted of red, blue, and green transparent color filters. Archived from the original on As light strikes the photocathode, electrons are emitted in proportion to the intensity of the light see photoelectric effect.
Retrieved January 16, This eliminates any possibility of secondary emission from this side of the target plate. Finally, an electron cameraa periodically sweeps across the target, effectively scanning the stored image, discharging each granule, and producing an electronic signal like in the iconoscope. The beam is aligned with the focusing magnetic field orthiocn means of a small transverse magnetic field produced by external coils located at the gun end of the focusing coil.