The principle of operation of the LCD monitor: quality control

Sometimes it becomes necessary to understand how a liquid crystal monitor works. Such devices are distinguished by their functionality and the principle of operation from other models of screens.

LCD monitor: principle of operation

Liquid crystal monitors or LCDs, short for liquid crystal display, are made from cyanophenyl. This substance has anisotropic properties. It can reside simultaneously in a liquid state and in crystalline form. The principle of operation of liquid crystal displays is based on such a physical phenomenon as the polarization of the light flux. That is, crystals can pass only that light flux where the electromagnetic induction vector is parallel to the optical plane of the polaroid. The remaining particles of the light spectrum they do not pass through themselves. Crystals of cyanophenyl are a kind of filter that passes through itself only a certain kind of spectrum of light for a stream corresponding to certain parameters, for another spectrum of the stream, the polaroid will remain opaque and will not skip particles.

Due to the ability of liquid crystal molecules to change their position in space, depending on forces of exposure to electromagnetic fields, it became possible to control the angle of refraction of light and change it polarization. It is in this way that the image appears on the screen.

Multiplexer screen

The multiplexer screen has a device called a multiplexer. This device provides the transmission of incoming digital transmission in the right direction. It has several inputs through which a signal is supplied and one output to which this signal is directed. The multiplexer can share the stream in a variety of ways:

• according to frequency characteristics - data on flows arrive simultaneously and do not mix with each other, but they have different frequencies;
• streams are sent at different times - between pauses, small pauses are made and the device reads data for the time until another stream arrives at it;
• encoding - each incoming stream is encoded and, together with others, is sent to the device.

The multiplexer can record images from any video source, allows you to view recordings that were made in advance, and can also transmit video in real time. On such screens, you can view several channels at the same time, allows you to take a freeze frame and enlarge the image of the desired fragment, makes it possible to sequentially switch the video between different objects, and also on such a screen there is a built-in calendar and clock.

Color monitors

To get a color picture on a good quality LCD screen, you need to make sure that the light comes from the back of the screen. To get a color image, three colors are used: red, blue and green. A filter is installed in the LCD monitor that does not pass all other spectra of the light flux. The combination of these colors in each pixel of the monitor allows us to display the color image we need. To improve its quality, modern technologies are used, such as: IPS and TFT. IPS is a design capable of delivering excellent image quality.

Reference! When controlling a pixel on the monitor in this case, it gives a large viewing angle, but the time required for the response is a little longer here than in TFT. TFT is short for Thin Film Transistor, which means thin-film transistor. It can control every pixel of the monitor.

Passive matrix

Passive matrices have a large capacitance of electrical voltage. Therefore, instantly process and display the desired picture, as well as update it, it can be a little slower. Briefly, this kind of matrix is ​​obtained when layers of vertical and horizontal stripes are combined. Electricity first flows into a vertical strip, and then into a horizontal strip, then the necessary coordinates are indicated. When the strips intersect, the crystals change their structural properties. And on the monitor, in the place that corresponds to these coordinates, a dot is formed. Depending on the current strength, the strips conduct a stream of light to one degree or another, and the color spectrum polarizes in color displays. The principle of such a matrix is ​​used in STN technology. This is short for Super Twisted Nematic.

Its main principle is that the data for a picture is formed sequentially, namely line by line, by applying voltage to individual cells of the screen, while it makes them opaque.

Quality Control LCD Monitors

All LCD screens are tested according to TCO standards. All tests are conducted at a distance of 30 cm from the front of the monitor and around it in a radius of 50 cm. They are also checked for other parameters, namely: ease of use, its impact on the environment environmental radiation of magnetic and electric fields, fire safety level, ability energy saving. Also, all LCD monitors are tested for heavy metals.