Well, while we’ve explained many of these different technologies throughout the pages and posts of 4K.com, we think it’s maybe worth giving a bit of robust clarification in a single concise post where OLED, QLED, LCD/LED and their details are all laid out clearly.
Let’s start with the most widely known, affordable and common type of TV panel, LCD/LED. This is also where VA and IPS panel subtypes come into the picture. These two display panel technologies will shortly be covered more robustly in another post.
LCD/LED 4K TV
In basic terms, LED/LCD display technology works by delivering light from LED backlight arrays of different types to an LCD panel in which RGB (Red Green Blue) pixels are integrated. The light passing through the pixels produces brightness and color in an LCD/LED TV while technologies such as local dimming (by which select areas of the LED backlight array can be shut off, check out our guide on this here) and light blocking filters in the pixels themselves create dark areas on a TV display. Not all 4K TVs have local dimming capacity and even the majority which do only offer the technology to a very limited, imprecise degree. Thus, the black levels in LCD/LED TVs are generally far from perfect, even though they have gotten much better than before in newer 4K TV models of this kind.
QLED 4K TV
QLED technology is two different things right now. On the one hand, it’s the potential future of 4K TV display due to certain developmental elements which promise to almost completely rework how 4K TV displays work. On the other hand, the QLED display type that we see actually on the market in the 4K TVs (from Samsung only for now) of 2017 is almost identical to LCD/LED TV display but with some moderate modifications for increased color performance and viewing angles. In other words, QLED, as it’s available now, mostly consists of a marketing name attached to what are in fact LCD/LED TVs of the same kind that has been available for a while.
OLED 4K TV
The way in which OLED works is largely responsible for such high performance metrics: Unlike LCD/LED TVs, OLED televisions have no backlight at all. Instead, each pixel on an OLED panel contains a tiny organic light emitting diode that lights up or completely turns off into full darkness depending on whether current is being run through it or not. As a result, OLED 4K TVs are capable of delivering perfect local dimming right down to the single-pixel level of precision (in a 4K TV this effectively means 8.29 million local dimming zones ) and due to the total black they can create by deactivating pixels, OLED TVs also deliver perfect, infinite contrast.