What is an LCD? In short and clear, this is a liquid crystal screen. Simple devices that have such equipment can work either with a black and white image, or with 2-5 colors. Currently, the described screens are used to display graphical or textual information. They are installed in computers, laptops, TVs, phones, cameras, tablets. Most electronic devices currently work with just such a screen. One of the popular varieties of this technology is the active matrix liquid crystal display.
History
Liquid crystals were first discovered in 1888. This was done by the Austrian Reinitzer. In 1927, the Russian physicist Frederiks discovered the crossing, which was named after him. At the moment, it is widely used in the creation of liquid crystal displays. In 1970, RCA introduced the first screen of this type. It immediately began to be used in watches, calculators and other devices.
A little later, a matrix display was created that worked with a black and white image. ColorThe LCD screen appeared in 1987. Its creator is Sharp. The diagonal of this device was 3 inches. Feedback on this type of LCD screen has been positive.
Device
When looking at LCD screens, it is necessary to mention the design of the technology.
This device consists of an LCD matrix, light sources that directly provide the backlight itself. There is a plastic case framed by a metal frame. It is necessary to give rigidity. Contact harnesses are also used, which are wires.
LCD pixels consist of two transparent type electrodes. A layer of molecules is placed between them, and there are also two polarizing filters. Their planes are perpendicular. One nuance should be noted. It lies in the fact that if there were no liquid crystals between the above filters, then the light passing through one of them would be blocked immediately by the second one.
The surface of the electrodes, which is in contact with liquid crystals, is covered with a special sheath. Due to this, the molecules move in the same direction. As mentioned above, they are mostly perpendicular. In the absence of tension, all molecules have a helical structure. Due to this, the light is refracted and passes through the second filter without loss. Now anyone should understand that this is an LCD in terms of physics.
Benefits
When compared with electron beam devices, thenthe liquid crystal display wins here. It is small in size and weight. LCD devices do not flicker, they have no problems with focusing, as well as with the convergence of rays, there are no interference that arise from magnetic fields, there are no problems with the picture geometry and its clarity. You can attach the LCD display on the brackets to the wall. It is very easy to do this. In this case, the picture will not lose its qualities.
How much the LCD monitor consumes depends entirely on the image settings, the model of the device itself, as well as the characteristics of the signal. Therefore, this figure can either coincide with the consumption of the same beam devices and plasma screens, or be much lower. At the moment, it is known that the energy consumption of LCD monitors will be determined by the power of the installed lamps that provide backlight.
It should also be said about small-sized LCD displays. What is it, how do they differ? Most of these devices do not have a backlight. These screens are used in calculators, watches. Such devices have a completely low power consumption, so they can work autonomously for up to several years.
Flaws
However, these devices have disadvantages. Unfortunately, many shortcomings are difficult to fix.
When compared with electron beam technology, a clear image on the LCD can only be obtained at native resolution. To achieve a good characterization of other pictures, you will have to use interpolation.
LCD monitors haveaverage contrast, as well as poor black depth. If you want to increase the first indicator, then you need to increase the brightness, which does not always provide comfortable viewing. This problem is noticeable in Sony LCD devices.
The frame rate of LCDs is much slower compared to Plasma or CRT. At the moment, Overdrive technology has been developed, but it does not solve the speed problem.
There are also some nuances with viewing angles. They are completely dependent on contrast. Electron-beam technology has no such trouble. LCD monitors are not protected from mechanical damage, the matrix is not covered with glass, so if you press hard, you can deform the crystals.
Backlight
Explaining what it is - LCD, it should be said about this characteristic. The crystals themselves do not glow. Therefore, in order for the image to become visible, it is necessary to have a light source. It can be external or internal.
The sun's rays should be used as the first. The second option uses an artificial source.
As a rule, lamps with built-in illumination are installed behind all layers of liquid crystals, due to which they shine through. There is also a side illumination, which is used in watches. LCD TVs (which is the answer above) do not use this type of design.
As far as ambient light is concerned, as a rule, black-and-white displays of watches and mobile phones work in the presence of such a source. Behind the layer with pixels is a special matte reflective surface. It allows you to beat off sunlight or radiation from lamps. Thanks to this, such devices can be used in the dark, as manufacturers build in side lighting.
Additional information
There are displays that combine an external source and additionally built-in lamps. Previously, some watches that had a monochrome type LCD screen used a special small incandescent lamp. However, due to the fact that it consumes too much energy, this solution is not profitable. Such devices are no longer used in televisions, as they generate a large amount of heat. Because of this, liquid crystals are destroyed and burn out.
At the beginning of 2010, LCD-TVs became widespread (what is it, we discussed above), which had LED backlighting. Such displays should not be confused with truly real LED screens, where each pixel glows on its own, being an LED.
