CRT-monitor: description, basic elements of the device

A CRT monitor is a device based on a cathode-ray tube. This technology was developed back in 1897 by a German scientist F. Brown. Initially, it was created as a specialized tool designed to measure alternating current (an oscilloscope).

CRT-monitor and its construction

The main element of such a device is a kinescope. It consists of a glass hermetic tube, from which air is removed (that is, a vacuum within it). One end of the tube is flat and wide - this screen, and the other - long and narrow - is the neck. The front side of the tube from the inside is covered with a phosphor composition (based on yttrium and erbium). The next element of the CRT monitor is an electron gun, from which an electron stream emerges under the action of an electrostatic field , so that an image appears on the screen. Elementary particles pass through the metal lattice and fall on the inner side of the glass screen, covered with phosphor points of different colors. A special deflection system ensures a consistent beam hit on the screen field. Deviation systems are of two types: saddle and toroidal. The system consists of inductors placed at the mouth of the kinescope.

The next element defining the CRT monitor is the frame and line scan unit. This node is the main source of interference in the operating frequency range. The power consumed by these nodes is one of the major factors to consider when designing a CRT monitor. The next element of the design is the intensity modulator, which, together with the accelerating system, operates on the principle of potential difference. Due to these nodes, the electrons acquire energy, part of which is consumed by the luminescence of the phosphor.

RGB technology

Usually a color CRT monitor contains 3 electronic guns, and a monochrome one. These cannons correspond to the main colors: green, red and blue. Their combinations are capable of creating an infinite number of shades and colors. To control cathode-ray tubes requires control electronics, which determines the quality of the monitor. It is the difference in the quality of electronics created by different manufacturers, is the criterion determining the difference between CRT-monitors, despite the fact that the cathode-ray tube in them is the same. So, each of the guns emits a flux that affects the phosphor points of different colors. An electronic beam of the same color should only affect the elements of its color. To achieve this particular beam action, use a special mask, the structure of which depends on the type of kinescope.

Repair of CRT-monitors

The main malfunctions of CRT-devices are a violation of the power supply unit performance. Most often this is due to voltage fluctuations in the electrical network. If the power supply fails, then the accompanying breakdown of other modules, for example, color rendering violation, image distortion, also occur. In addition to power surges, the causes of failure of monitors are often mechanical damages (impacts), exposure to sources of electromagnetic radiation, dustiness of the monitor, overheating, aging of elements. Violation of the temperature regime can lead to the failure of the processing board of video signals and the formation system. Violation of the performance of horizontal scanning is due to a breakdown in high-voltage circuits and TDKS. One of the reasons for this phenomenon is dustiness.