What is this 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 described screens are used to display graphic or text information. They are installed in computers, laptops, televisions, telephones, cameras, tablets. Most electronic devices currently work with just such a screen. One of the popular varieties of this technique is an active matrix liquid crystal display.
History
Liquid crystals were first discovered in 1888. Did it the Austrian Reinitzer. In 1927, the Russian physicist Fredericks discovered the transition, 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 its kind. It immediately began to be used in watches, calculators and other devices.
A bit later, a matrix display was created that worked with a black and white image. A color LCD screen appeared in 1987. Its creator is Sharp. The diagonal of this device was 3 inches. Reviews of this type of LCD screen were positive.
Device
When considering LCD screens, it is necessary to mention the design of the technology.
This device consists of an LCD matrix, light sources that provide the backlight itself. There is a plastic case framed by a metal frame. It is necessary to give rigidity. Contact harnesses, which are wires, are also used.
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.
The surface of the electrodes, which is in contact with liquid crystals, is coated with a special shell. Due to this, the molecules move in one direction. As mentioned above, they are mainly located perpendicularly. In the absence of voltage, 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
Compared with cathode-ray devices, the liquid crystal display wins here. It has a small size and weight. LCD devices do not flicker, they have no problems with focusing, and also with converging rays, there are no interferences that arise from magnetic fields, there are no problems with the geometry of the picture and its clarity. You can attach the LCD display on the brackets to the wall. It is very easy to do. At the same time, 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, and also on the characteristics of the signal supply. Therefore, this indicator can both coincide with the consumption of the same radiation devices and plasma screens, and can be much lower. At the moment, it is known that the power consumption of LCD monitors will be determined by the power of the installed lamps that provide illumination.
It is also necessary to say 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 are characterized by completely low power consumption, so they can work up to several years autonomously.
disadvantages
However, these devices have disadvantages. Unfortunately, many shortcomings are difficult to fix.
Compared with the electron beam technique, a clear image on the LCD can be obtained only with standard resolution. To achieve a good characterization of other pictures, you will have to use interpolation.
LCD monitors have medium contrast, as well as poor black depth. If you want to increase the first indicator, then you need to make more brightness, which does not always provide a comfortable viewing. This problem is noticeable on Sony's LCD devices.
LCD frame rates are much slower when compared to plasma or cathode-ray displays. Overdrive technology is currently developed, but it does not solve the speed problem.
With viewing angles there are also some nuances. 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 when pressed hard, crystals can be deformed.
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.
As the first should use the sun's rays. In the second embodiment, an artificial source is used.
As a rule, lamps with built-in illumination are installed behind all layers of liquid crystals, due to which they are transmitted through through. There is also a side light, which is used in the watch. On LCD TVs (which is the answer above) this type of design does not apply.
As for external lighting, as a rule, black-and-white displays of watches and mobile phones work with such a source. Behind the pixel layer is a special matte reflective surface. It allows you to beat off sunlight or radiation from lamps. Thanks to this, you can use such devices in the dark, as manufacturers integrate side lighting.
Additional Information
There are displays in which an external source and optionally integrated lamps are combined. Earlier, in some watches where a monochrome LCD screen was installed, a special small incandescent lamp was used. However, due to the fact that it consumes too much energy, such a solution is not profitable. Such devices are no longer used in televisions, as they emit a large amount of heat. Because of this, liquid crystals are destroyed and burn out.
In early 2010, LCD TVs (what it is, we reviewed above), which had LED backlighting , became common . Such displays should not be confused with truly real LED screens, where each pixel glows independently, being an LED.