TV Purchase Guide – Display Technology : LCD


TV Purchase Guide – Display Technology : LCD

In the previous article we explained what CRT displays are and how they work.

As we have mentioned, one of the factors of purchasing a television is choosing the right kind of display technology. For a reminder, we will take a look at the major display technologies as follows:

  • CRT
  • LCD (LED is a derivative of LCDs as LED backlit LCD)
  • Plasma
  • OLED

In this article we will explain more about LCDs.

LCD Displays

First of all we should know that LCD stands for Liquid-Crystal display that the name gives you some idea about how do LCDs work.

It should be noted that these types of displays are among the most popular ones in the world and there are some reasons for this popularity that we will tell them later.

LCDs produce pictures by using liquid-filled crystals. The reason is the characteristic of liquid crystals that they can generate pictures by being placed between backlight and the display screen. This means that in a LCD display, existence of a backlight is necessary.

In General the LCD itself does not produce light but their light-modulating characteristic make it possible to produce colorful or in monochrome pictures.

The applications of their usage are so vast from smart phones to Televisions. The reason is that their screen sizes can vary from a tiny watch display to big TV screens.

It can be said that LCDs are a technology between CRT and OLEDs. That is, almost in most of the applications they have been used instead of CRTs and then OLEDs are now more in trend and they are being used instead of LCDs. But, it should mentioned that as OLEDs uses phosphorous, they suffer from screen burning that this is a benefit in LCD that they experience this issue rarely.

To know more about how does LCDs work we should explain the process of polarization. Light in space can move in any directions and it is called unpolarized light, but when filters would be used, we can produce polarized light.

This is one of the part of a LCD displays that the first filter is used for polarization. A second filter is also being used perpendicular to the first filter, therefore the light cannot pass through the second filter. This is the step that we use liquid-crystal that can rotate the polarized light when an electric field being applied. It can be said that by using two light filters, the liquid-filled crystals work like a switch that they can turn on or turn off the display being shown. And this can be done by applying an electric filed to this part to make it work. 

In order to produce a colorful picture, color filters should be used as the second filter to produce Red, Green and Blue. It means that by applying various amount of voltage to each pixels, it can produce a colorful pixel with its levels.

Till now, we have a general idea about how these LCD display works and as we will explain later about LEDs, it is worth mentioning again that one the benefits in LCDs is that they do not suffer from screen burning. Screen burning happens in OLED display and rarely in LCD. It will happen when a picture without any movement displayed for a long time. This is the reason that in most of the televisions and computers, by default there is an optioned called screen saver. Screen saver shows a picture of an animation that moves all around the display to prevent the LCD from burning effect.

Another benefits of LCDs is that they are much thinner and more compatible than CRT displays which make it possible to use these displays in various applications.

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