Understanding LED televisions


Imperfect LEDs

The role of the screen's LCD matrix is to let through more or less of the light emitted by the backlighting. The colours are obtained on each pixel simply by applying a red, green or blue filter which will convert the backlighting's white light. The constitution of this "white" has a direct influence on the colour quality on screen. Conventional screens use white LEDs for this. These white LEDs do not produce perfect chromatic quality. In fact, a white LED is actually a blue LED to which a layer of phosphorus is added and which will convert part of this blue light into partially green and red light. This mix is far from perfect. In particular, there is a strong representation of blue, which often produces colours which are quite cold on the screen. To solve this problem, television manufacturers had the idea of using quantum dots in place of phosphorus.


How does it work?

Quantum dots are not as new as that. We have Bell Laboratories to thank for them, who developed them in 1982! They are nano-crystals, between 2 and 10 nanometres, whose property is to re-emit the light they receive by modifying its colour. The colour produced depends in particular on their size, to go from blue to red or from blue to green. Manufacturers therefore had the idea of replacing imperfect white LEDs with blue LEDs on which a film of quantum dots was placed, completing the backlighting colour spectrum for a perfect white and ultimately richer colours.


Which advantages?

Using quantum dots was a real revolution in the little world of televisions. Quantum dots are much more effective than the phosphorus used before. We get more brightness with the same level of electrical consumption, which is vital if we want to enjoy future HDR content. The latest product in the range, TCL's Xclusive.X1 television is equipped with quantum dot backlighting to produce a very broad colour spectrum. It also benefits from Ultra HD Premium certification, which demands a colour gamut which covers 90% of the DCI-P3 standard which is currently applied in the cinema industry in the United States. It even achieves 96% of this spectrum.

Over and beyond the technology, what result does the viewer see? Colours are more natural and better nuanced, especially when there are strong contrasts. Quite simply, you see the colours that were actually filmed and the result that the director wanted.