How is the CRT

Somehow imperceptibly the time has come when the TVs and monitors based on cathode-ray technology have almost completely disappeared from the shelves of stores. Recall, these are the same cumbersome devices that occupied almost half of the computer table. This is now their thickness rarely exceeds 10 cm, and that only with the inclusion of lamp illumination. It's no wonder that many have safely forgotten what a CRT monitor is. And in vain! At least because by some parameters it is ahead of even the most modern liquid crystal analogs.

How CRT monitors are arranged

First of all, we will give an explanation of the abbreviation. So, by the term "CRT" is meant an electron beam or, as we indicated earlier, a cathode tube (from English CRT - Cathode Ray-Tube). As a rule, with the word "tube", most people represent a cylinder with the ends of which do not have walls. Speaking of what a CRT monitor is, it should be mentioned that in this case such a representation is erroneous. Because the shape of the tube in it is far from cylindrical and expands to a plane with one of the sides. This surface is the front glass part, the same one on which the images are formed. The inner side of this site is covered with a special substance - a phosphor. Its unique property is that, if a stream of charged particles hits it, their kinetic energy is naturally transformed into a luminescence. Thus, the CRT monitor is an instrument in which the beams of electron beams draw a picture on the inside of the screen. A person sees it, thanks to the luminescence of the phosphor.

On the other side of the flask there is a block of electrodes, called guns. They create a stream of particles.

In other words, the CRT monitor consists of a glass tube, gun electrodes and a control circuit.

Principle of operation

As you know, mixing in a certain ratio of the three primary colors: green, red and blue - you can get everything else, including shades. In color monitors, the entire inner surface of the screen consists of points, conditionally grouped into triads (blocks of 3 pieces). Each of them can shine with one of the primary colors. Electrodes are also three, each of which highlights "their" points. In a certain order, lighting and passing them on the screen, it is possible to form a color picture. By the way, in devices of a black and white image the gun is only one.

To control the flow of particles, the electromagnetic deflection is used, and the initial direction of their motion is created due to the potential difference.

Since it is technically difficult to ensure accuracy of the beam hit on its point, a special solution is used - the mask. Relatively speaking, this is a perforated grid between the screen and guns. There are different types of masks. In part, they are responsible for the features of the mapping (clarity, the shape of pixel points).

Since after the impact of the particle, the phosphor emission diminishes very rapidly, it is necessary to constantly recreate the picture. Both static and dynamic. Therefore, the rays draw an image dozens of times per second. This is the famous Hertz cadres. The higher the frequency, the less noticeable the flickering.

Currently, the repair of CRT monitors for subsequent use as part of a computer system is inexpedient, since modern LCD technology is more promising. An exception is specific use.