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 descriptive purposes, the tube may be divided into three sections, the image section, the scanning section and the multiplier section, as shown above. The photoelectric screen in the proposed transmitting device was a mosaic of isolated rubidium cubes.
The target is nearly at ground potential with a small positive charge, thus when camer electrons reach the target at low speed they are absorbed without ejecting more electrons.
Video camera tube – Wikipedia
An electron beam periodically sweeps across the plate, effectively scanning the stored image and discharging each capacitor in turn such that the electrical output from each capacitor ortthicon proportional to the average intensity of the light striking it between each discharge event. The image section contains a semi-transparent photo-cathode on the inside of the faceplate, and electrodes to provide an accelerating electrostatic field to the target.
Navythe first tubes being delivered in January The Institute of Electrical Engineers. United States Patent Office.
However, it tends to flare in bright light, causing a dark halo to be seen around the object; this anomaly is referred to as ” blooming ” in the broadcast industry when image orthicon tubes were yube operation. While the iconoscope and the intermediate orthicon used capacitance between a multitude of small but discrete light sensitive collectors and an isolated signal plate for reading video information, the image orthicon employed direct charge readings from a continuous electronically charged collector.
The image orthicon, sometimes abbreviated IO was common in American broadcasting from until Principles of Operation Schematic arrangement of the 4. Used frequently in broadcast camera applications, these tubes have low output, but a high signal-to-noise ratio.
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 the camera, the disk was in the optical path, and in the receiver, it was in front of the CRT. An image dissector is a camera tube that creates an “electron image” of a scene from photocathode emissions electrons which pass through a scanning aperture to an anodewhich serves as an electron detector.
The mysterious dark “orthicon halo” around bright objects in an IO-captured image is based on the fact that the IO relies on the emission of photoelectrons, but very bright illumination can produce more of them locally than the device can successfully deal with. This is sufficiently high to bring the random noise of the electron beam well above that of the input stage of the camera head amplifier and is, therefore, the limiting noise factor in the use of the tube.
The entire electron image is deflected and a scanning aperture permits only those electrons emanating from a very small area of the photocathode to be captured by the detector at any given time. New York Times article.
Each globule is very active photoelectrically and constitutes, to all intents and purposes, a minute individual photoelectric cell”. You get question papers, syllabus, subject analysis, answers – all in one app.
Image orthicon | electronics |
Step to home television. Although the optical format size bears no relationship to any physical parameter of the sensor, its use means that a lens that would have been orthkcon with say a four thirds inch camera tube will give roughly the same angle of view when used with a solid-state sensor with an optical format of four thirds of an inch.
The phenomenon known as magnetic focusing was discovered by Orthicob. Finally, an electron beam periodically sweeps across the target, effectively scanning the stored image, discharging each granule, and producing an electronic signal like in the iconoscope. Light biasing was a method whereby cakera photosensitive target was illuminated from a light source just enough that no appreciable output was obtained, but such that a slight increase in light level from the scene was enough to provide discernible output.
Retrieved July 9, The electron gun structure produces a beam of electrons that is accelerated towards the target. It has an efficient photocathode that transforms the scene light into an electron image; the latter is then accelerated towards a target specially prepared for the emission of secondary electrons.
A vidicon tube is a video camera tube design in which the target material is a photoconductor. The target is constructed of a mosaic of electrically isolated metallic granules separated from a common plate by a thin layer of isolating material, so that the positive charge resulting from the secondary emission is stored in the capacitor formed by the metallic granule and the common plate.
Video camera tube
These are not to be confused with the extension tubes used for imahe photography in hand held cameras. Dictionary of Video and Television Technology.
The face of the target remote from the photo-cathode is scanned by an electron beam emanating from a triode electron gun, the potentials being so adjusted that the beam approaches the target with a substantially zero velocity and is, therefore, unable to produce unwanted secondary electrons.
In detail, coils in a deflection yoke extend some distance beyond the neck of the tube, and lie close to the flare of the bulb; they have a truly distinctive appearance. From Wikipedia, the free encyclopedia. These focus coils are essentially as long as the tubes themselves, and surround the deflection yoke coils. Campbell-Swinton inhe found that a longitudinal magnetic field generated by an axial coil can focus an electron beam.