LCD (Liquid Crystal Display)

LCD is a flat panel display technology that is commonly used in TVs and computer monitors. At the same time, it is also used for screens, in mobile devices, such as laptop , tablet, and smartphone.

The full form of the LCD is ” Liquid Crystal Display .” LCD displays look exactly like bulky CRT monitors, but the way they operate is quite different in comparison. Instead of firing electrons into a glass screen, an LCD has a backlight that provides light individual pixels that are arranged in a rectangular grid.

Each pixel has a red, green, and blue RGB sub-pixel that can be turned on or off. When all the sub-pixels of a pixel are turned off, then it appears black.

While all sub-pixels are turned on 100%, then it appears White (White). In this, hundreds of combinations of colors can be made by adjusting the red, green, and blue light of individual levels.

How does LCD work?

The backlight of this liquid crystal display provides an even light source from behind the screen. This makes the light polarized, meaning only half the light shines through the liquid crystal layer.

The liquid crystals are made from one part solid, part liquid substance which can be “twisted” by applying electrical voltage. They block polarized light when they are turned off, but they also reflect red, green, or blue light when activated.

Each LCD screen has a matrix of pixels that displays the image on the screen. The same LCDs have passive-matrix screens, which are controlled by individual pixels, for which a charge is sent into their row and column.

Since only a limited number of electrical charges can be sent per second, passive-matrix screens are more familiar to look blurry when images are moved quickly to the screen. Modern LCDs typically use active-matrix technology, which consists of film transistors, or TFTs.

These transistors include capacitors that enable individual pixels to “actively” retain their charge. This is the reason that active-matrix LCDs are more efficient and also look more responsive as compared to passive-matrix displays.

The backlight of an LCD is either a traditional bulb or an LED light. An “LED display” is simply an LCD screen with an LED backlight. It is completely different from an OLED display, which lights up individual LEDs for each pixel.

When liquid crystals block most of the light from the LCD’s backlight when they are switched off, some light still shines through it (which makes it noticeable in a dark room). So OLEDs typically have darker black levels than LCDs.

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