LCD vs LED vs OLED: What does it really mean & what differs them?

By on January 22, 2018

When device manufacturers throw around so many similar terms for their displays, it’s hard to parse just what’s what. LED? OLED? AMOLED? What the heck are those?

If that’s what goes through your head too, here’s a bit of a primer for these different types of displays.

The LCD that started it all
In old CRT monitors and televisions, a cathode ray tube illuminated a photosensitive filter in patterns of flashes so quick that it would appear to us as a lit up image. Though modern day LCDs work on the same principle, the technology is different. Here there’s a liquid crystal display (LCD) that controls where the light hits your screen. These panels are two sheets of polarizing material with a liquid crystal solution sandwiched in between, so when an electric current passes through the crystals align to either allow the light or block it. The signal received here, instead of being analog, is comprised of binary ones and zeroes. A pixel with a value of zero means it’s off (or black), while a value of one means the on state. The LCD reads the digital signal and converts it into an on/off pattern for all the pixels on screen. By shining the primary colours in this way, each pixel can be controlled individually, making for a much sharper picture than in CRT TVs.

This is where the term “refresh rate” matters to you. The number of frames your display shows you each second is the frame rate. Traditionally, the optimal rate is about 60 fps (frames per second) but many displays go as high as 120. The higher that number, the smoother the feed is to your eyes.

The LED and OLED that followed
Another interesting to note here is that an LED (light-emitting diode) display is technically an LCD display, it’s just a specific kind. They both have a liquid crystal panel, the difference comes in when you consider the light being used to illuminate them. Older LCD TVs used something called Cold Cathode Flourescent Lamps (CCFL) to light up the display. LED televisions instead use an array of LEDs, because they’re not only brighter but also more power-efficient.

Then of course is an even later development, the OLED display. OLED stands for Organic Light Emitting Diode. Here, instead of being backlight by sets of LEDs, each pixel is instead made of a material that lights up when hit with electricity. This way, instead of having a constant light and a panel to either allow or block it, only each pixel that needs to be “on” will light up. This means an OLED is capable of a “perfect black” picture, with no light emitted. Because of that, while and LED display can be as bright or even brighter than the more modern OLED, the later will always win on contrast ratio.

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