If the focusing is not achieved properly, the results tend to be poor.Coating phosphors of different compounds can produce different colored pictures.But the basic problem of graphics is not to produce a picture of a predetermined color, but to produce color pictures, with the color characteristics chosen at run time.The basic principle behind colored displays is that combining the 3 basic colors Red, Blue and Green, can produce every color.
By choosing different ratios of these three colors we can produce different colors millions of them in-fact. We also have basic phosphors, which can produce these basic colors. So, one should have a technology to combine them in different combinations. There are two popular techniques for producing color displays with a CRT are: Well be covering the following topics in this tutorial: Beam Penetration method The Shadow Mask method. Download discography aviciiBeam Penetration method This CRT is similar to the simple CRT, but it makes use of multi coloured phosphorus of number of layers. It can produce a maximum of 4 to 5 colours The organization is something like this The red, green and blue phosphorus are coated in layers one behind the other. If a low speed beam strikes the CRT, only the red colored phosphorus is activated, a slightly accelerated beam would activate both red and green (because it can penetrate deeper) and a much more activated one would add the blue component also. However, a limited range of colors can be conveniently produced using the concept. This works, again, on the principle of combining the basic colors Red, green and Blue in suitable proportions to get a combination of colors, but its principle is much more sophisticated and stable. Each pixel point on the screen is also made up of 3 types of phosphors to produce red, blue and green colors. Just before the phosphor screen is a metal screen, called a shadow mask. This plate has holes placed strategically, so that when the beams from the three electron guns are focused on a particular pixel, they get focused on particular color producing pixel only i.e. If for convenience sake we can call the electronic beams as red, blue and green beams (though in practice the colors are produced by the phosphors, and until the beams hit the phosphor dots, they produce no colors), the metal holes focus the red beam onto the red color producing phosphor, blue beam on the blue producing one etc. When focused on to a different pixel, the red beam again focuses on to the red phosphor and so on. Now, unlike the beam penetration CRTs where the acceleration of the electron beam was being monitored, we now manipulate the intensity of the 3 beams simultaneously. Apple usb to ethernetIf the red beam is made more intense, we get more of red color in the final combination etc. Since fine-tuning of the beam intensities is comparatively simple, we can get much more combination of colors than the beam penetration case. In fact, one can have a matrix of combinations to produce a wide variety of colors. The shadow mask CRT, though better than the beam penetration CRT in performance, is not without its disadvantages. Since three beams are to be focused, the role of the Shadow mask becomes critical.
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