Operating principle of LCD monitor

Sometimes it becomes necessary to understand how an LCD monitor works. Such devices differ in their functionality and operating principle from other screen models.

LCD monitor: operating principle

Liquid crystal displays, or LCDs, short for liquid crystal display, are made from cyanophenyl. This substance has anisotropic properties. It can be in both liquid and crystalline form at the same time. The operating principle of liquid crystal displays is based on such a physical phenomenon as the polarization of light flow. That is, crystals can transmit only that light flux where the electromagnetic induction vector is located parallel to the optical plane of the polaroid. They do not transmit other particles of the light spectrum through themselves. Cyanophenyl crystals are a kind of filter that passes through only a certain type of light flux spectrum corresponding to certain parameters; for another flux spectrum, the polaroid will remain opaque and will not allow this particle flux to pass through.

Thanks to the ability of liquid crystal molecules to change their location in space depending on the strength of the influence of electromagnetic fields, it became possible to control the angle of refraction of light and change its polarization. This is how the image appears on the screen.

Multiplexer screen

A multiplex screen has a device called a multiplexer. This device ensures that the incoming digital transmission is sent in the desired direction. It has several inputs through which a signal is supplied and one output to which this signal is sent. A multiplexer can split a stream in a variety of ways:

• according to frequency characteristics - data on streams arrive simultaneously and do not mix with each other, but they have different frequencies;
• streams are sent at different times - short pauses are made between data sendings and the device reads the data for the time until another stream arrives to 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 simultaneously, allows you to take a freeze frame and enlarge the image of the desired fragment, makes it possible to sequentially switch video recording between different objects, and also on such a screen there is a built-in calendar and clock.

Color monitors

To obtain a color picture on a good quality LCD screen, you need to ensure that the light comes from the back of the screen. To obtain a color image, three colors are used: red, blue and green. The LCD monitor has a filter installed that does not transmit 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 on the screen. To improve its quality, modern technologies are used, such as IPS and TFT.IPS is a development that can provide excellent image quality.

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

Passive matrix

Passive matrices have a large electrical voltage capacity. Therefore, it can instantly process and display the desired image, and also update it a little slower. This type of matrix, in short, is obtained when layers of vertical and horizontal stripes are combined. Electricity is first supplied to the vertical strip, and then to the horizontal strip, then the required coordinates are indicated. When the stripes intersect with each other, the crystals change their structural properties. And on the monitor, in a place that corresponds to these coordinates, a point is formed. Depending on the current strength, the strips conduct the light flow to one degree or another, and in color displays the light spectrum is polarized. 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 the picture is generated sequentially, namely line by line, by applying voltage to individual cells of the screen, while it makes them opaque.

Quality control of LCD monitors

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