The Different Display Technologies in the world explained, CRT vs Plasma vs LCD vs OLED

CRT

I would like to start by stating here clearly that there are no LED tvs, yes, that 45 inch screen you bought with LED written all over it is actually an LCD screen. Currently, there are four main display technologies in use in the world, the famous CRT (Cathode Ray Tube), Plasma, LCD and OLED (Notice there’s no LED display technology. Do not confuse OLED and LED, the first is a true display technology in use while the latter is simply a back-lighting option in LCD screens)

CRT is the oldest of the display technologies which uses a Cathode Ray to illuminate a fluorescent screen. Basically, a cathode ray (fast moving electrons) is made to move very fast both vertically and horizontally at the same time, hitting a screen that illuminates (when hit by electrons) at such a rate that it creates a moving picture. The “kisogo”(you would think the entire English language would have a definite name for the back of your head but No!) you see on your CRT screens is made of the cathode, the deflecting coils and the required space (vacuum) needed to adequately accelerate and deflect the electrons towards the screen covered by a fluorescent material.

Plasma

Plasma display technology has also been around for quite some time. Many manufacturers have decided to focus on LCD mainly to create displays that use less power and are a bit thinner. However, Plasma display technology offers many advantages to both CRT and LED including; higher refresh rates, better colour reproduction, wider viewing angles etc. Plasma display technology utilizes the glowing properties of some gases when excited by an electric current. Essentially, a current is passed through a gas that lights up individual Red, Green and Blue phosphors in such a way that it creates a picture on the screen. To create an image, the video information (in form of an electric current from the camera) is passed through the gas to recreate the picture.

Therefore, plasma offers thinner displays compared to CRT. The two major disadvantages associated with Plasma are power consumption and a phenomena known as “burn in”. However, advancements in technology have made it possible to create more power efficient plasma screens which are also less prone to “burn in.”

LCD

LCD, which is the most common display technology uses liquid crystals (funny right, liquid crystals?? I didn’t like chemistry that much either but apparently I missed a class or two) RGB (Red Green and Blue ones) which block light to some extent when electricity is passed through them. In this case, the liquid crystals actually block light when electricity is passed through them, unlike the gases used in plasma.

Therefore, in order for us to see the picture created on the screen, we need a back-light that will light up the picture. This is where LED LCD tvs come in. The old LCD tvs use Cathode tubes for the backlight whereas the so called LED tvs use LEDs for the backlight. The reason why the LED tvs are so thin is because cathode tubes used for lighting are a bit bulkier than the LEDs. I won’t talk about the quality of light from LEDs and that from cathode tubes and why LEDs are replacing cathode tubes in tv technology, but one of the major reasons for this is power saving. LEDs are more power efficient and burn brighter and for longer producing less heat than Cathode tubes. This translates to a TV that uses less power, can be made brighter and lasts longer than its Cathode back-lit counterpart.

OLED

Lastly we have OLED display technology which is quickly picking up. OLED (Organic Light Emitting Diode) as the acronym suggests uses an organic material that emits light when excited by electricity. OLED display technology can be described as an all in one display system with all of the advantages of the previous display technologies and very few disadvantages. Unlike LCD which requires a backlight, OLED screens provide their own lighting. To create colour, different types of organic films (RGB) are placed along the entire length of the screen. The higher the current applied to the organic material, the brighter it illuminates creating a picture on the screen. Therefore, to create a black scene, simply no current is directed towards the dark areas (this information is contained in the video signal from the camera).

OLED screens can be made very thin (thinner than the thinnest LCD LED screen you have seen) but on the flipside, cost a lot more. The thinness of OLED makes them easy to fold and unfold without compromising their physical properties making possible the production of foldable phone displays as well as curved OLED tvs.