The technology for these displays is much different than that for CRTs. Notebook computers typically use liquid crystal display. The heart of the CRO is a cathode-ray tube. The most common specification for CRT displays is known as SVGA (Super Video Graphics Array). Its reliability, stability, and ease of operation make it suitable as a general purpose laboratory instrument. In computer systems, there are several display modes, or sets of specifications according to which the CRT operates. The CRT thus produces three overlapping images: one in red (R), one in green (G), and one in blue (B). These devices have three electron guns, one for the primary color red, one for the primary color green, and one for the primary color blue. However, virtually all CRTs today render color images. This is typical of a monochrome, or single-color, CRT. The illustration shows only one electron gun. But the scanning takes place at such a rapid rate that your eye sees a constant image over the entire screen. experiments, cathode rays were not a significant phenomenon, but they probably were in Schusters experi- ments. As viewed from the front of the CRT, the spot moves in a pattern similar to the way your eyes move when you read a single-column page of text. This causes the spot to race across the screen from right to left, and from top to bottom, in a sequence of horizontal lines called the raster. Although both the cathode and the anode contribute in the vacuum arc evolution, the role of the cathode is more crucial, since the processes developing at the cathode surface initiate the breakdown and maintain constant radiance from the cathode surface throughout the whole arc process, driving the arc in a stable manner. To produce an image on the screen, complex signals are applied to the deflecting coils, and also to the apparatus that controls the intensity of the electron beam. A modification of Crookes tube evolved into the first. The electron beam produces a tiny, bright visible spot when it strikes the phosphor-coated screen. I was inspired by the historical and modern significance of the cathode ray. There are two sets of deflecting coils: horizontal and vertical.(In the illustration, only one set of coils is shown for simplicity.) The intensity of the beam can be varied. Deflecting coils produce an extremely low frequency electromagnetic field that allows for constant adjustment of the direction of the electron beam. The electron gun generates an arrow beam of electrons. The CRT in a computer display is similar to the "picture tube" in a television receiver.Ī cathode-ray tube consists of several basic components, as illustrated below. Most desktop computer displays make use of CRTs. He determined the fluorescence was caused by invisible rays originating from the Crookes tube he was using to study cathode rays (later recognized as.
A cathode-ray tube (CRT) is a specialized vacuum tube in which images are produced when an electron beam strikes a phosphorescent surface.
0 kommentar(er)
