Visual display

To obtain an engaging multimedia, a personal computer should be able to display clear and colorful images. The monitor reproduces any color images by combining three primary colors of red, blue and green. Three electron guns in the back of the screen fire thin beams of electrons. The image on the screen consists of thousands of tiny dots called pixels. Each pixel, in turn, consists of a group of points in the direction of the electron beam on they light up red, blue or green. Changing the intensity of the beam can be obtained in different colors. The more pixels on the screen, the clearer the image.
As each volley of electrons lasts only a moment, to maintain the image on the monitor must be replaced by new electrons. Refresh rate (image refresh) measured the rate of replacement of cadres, which in turn depends on the speed of the horizontal sweep (replacement of horizontal lines). At a sufficiently high resolution (e.g. 1280x1024 pixels) most of the modern 17-inch monitors with cathode-ray tube normally run with a refresh rate of 86 Hz, i.e. a frame (screen image) per second is updated 86 times.