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Mini-LED vs QLED TV: How one technology is improving the other

Amid all of the alphabet soup of TV terms like OLED, HDMI, ARC, HDR, and QLED, you can now add another to the list: Mini-LED. While not a household term just yet, it has the potential to significantly reshape the TV landscape by offering much better brightness and contrast without the need for expensive and exotic display technologies like microLED.

If that kind of sounds like what QLED technology is supposed to do, you’ve definitely been doing your homework. QLED and mini-LED are actually complementary to each other, and together they might finally prove that OLED isn’t the only way to get the world’s best picture quality. Here’s the full story on mini-LED and QLED TV.

LEDs: Consider the size

Radiative Sky Cooling LED.
UCLA Samueli School of Engineering

There are two primary kinds of TV displays at the moment: Self-emissive displays like OLED and microLED — in which each individual pixel pumps out its own brightness and color — and backlit displays like LED and QLED TVs, which require a separate backlight to provide a light source, while an LCD matrix and color filters take care of color and controlling how much brightness comes through.

LED TVs and QLED TVs (which are essentially a subset of LED TVs) use LEDs as their backlights. But not all TVs using this technology are created equal. Inexpensive LED TVs may use only a few LEDs arranged around the outside edges — thus the term “edge-lit” TVs — while the most expensive sets use hundreds of LEDs arranged in a grid-like pattern, sub-divided into individually controlled zones. These are known as full-array local dimming (or FALD for short). The general rule here is that the more LEDs you can pack into a backlight, the brighter it will get and the more control you’ll have over that brightness in very specific areas of the TV’s image.

In a perfect world, you’d have one LED for every pixel in an LCD matrix, but right now, that’s impossible. There’s a physical limit to the number of regular LEDs you can squeeze into a given space, which is determined by the size of the LEDs themselves. The bigger they are, the fewer you can use.

Mini-LED: A big leap in getting small

A grid of LED lights.

This size-based constraint on the number of possible LEDs is what makes mini-LED technology so exciting. It breaks through the previous size barrier by introducing LEDs that are much smaller than any that have been used so far. We’re talking about being able to fit thousands of LEDs in a space that once could support only hundreds.

A 4K TV has just over 8 million pixels, so mini-LEDs are still significantly bigger than an individual pixel, but that’s OK: Mini-LEDs are so much smaller than standard LEDs that you can still see a big difference.

It’s all about the light (and the dark)

High-contrast image of the sun.

As we said earlier, more LEDs lead to better brightness — beneficial for HDR as well as making the picture visible in bright rooms — but it also leads to better darkness too.

To achieve a deep, dark black in a specific portion of the screen on a backlit TV — the kind you expect when looking at space scenes — you need to shut off the backlight in that portion entirely. But even with FALD, if there’s a big difference between the brightest part of the screen and the darkest, it can lead to blooming — an effect that makes it look like light is leaking from the bright portion into the darker portion.

With mini-LEDs, local dimming becomes far more effective because it increases the number of dimmable zones while decreasing their size, making it easier to isolate dark areas from light ones. This not only makes the darker portions of the screen darker, but the contrast created makes the lighter portions seem even brighter.

So far, we haven’t seen a mini-LED TV that gets as perfectly black (and without any blooming) as OLED, but that gap between backlit TVs and emissive displays such as OLED TVs is smaller than it has ever been.

Where does QLED fit into all of this?

TCL 8-Series 4K QLED Roku TV.

QLED, or quantum dot LED, uses nano-particles that have a special property: When light shines on them, they can emit their own light, specifically tuned to a certain color. When red and green quantum dots are layered on top of a blue LED backlight, it creates a much fuller-spectrum white light than can be achieved using white LEDs. This pure white light, in turn, helps the TV’s color filter perform more efficiently and accurately. Top-of-the-line QLED TVs can offer image quality that comes very close to OLED. Their brightness and vivid colors can be bolder than OLED, but they still can’t match OLED’s perfect blacks.

If you power a QLED TV with a mini-LED backlight, you can preserve all of the brightness and punch of a traditional QLED screen, but you also get highly granular control over local-dimming zones. In theory, it’s the ingredient that QLED has been lacking in its competition with OLED.

Are there any other benefits to mini-LED?

Mini-LED TVs are, in every other respect, the same as standard QLED TVs, so the same benefits apply to both: Screen sizes can be bigger, and prices can be lower than OLED TVs (for now, anyway). As the technology matures, we can expect to see mini-LED play a big role in improving image quality while driving down the price of both LED and QLED TVs. There will also be gains in power efficiency, as a large group of smaller LEDs can achieve the same brightness as larger LEDs, yet they need less energy to do so. Since OLED TVs have traditionally used less power than QLED TVs, this is yet another way that mini-LEDs help QLED TVs whittle away at OLED’s advantages.

Who makes mini-LED TVs?

TCL Vidrian Mini-LED.

TCL started the mini-LED TV movement when it released the first mini-LED TV — the 8-Series Roku TV — in 2019. Since then, TCL has released the 2020/2021 4K 6-Series with mini-LED technology, and we anticipate the release of its first 8K mini-LED models soon. At CES 2021, the company also indicated that it would produce a mini-LED TV based on its ultra-thin OD-Zero technology, but so far, that doesn’t appear to be on the table as a 2021 model.

TCL is no longer the sole mini-LED player. Samsung’s 2021 Neo QLED models — in both 4K and 8K resolutions — use the technology, as does LG’s 2021 4K and 8K QNED models. That leaves Sony, Hisense, and Vizio as the three major TV makers that have not announced any mini-LED models, but you can be sure that each of them is working on a mini-LED strategy for 2022.

Mini-LEDs aren’t just for TVs. Apple recently released its first iPad that uses the new backlight, and it’s widely expected that the next MacBook Pro will use it, too. If we assume that Apple is now a believer in mini-LED, we’ll probably see it show up in the next refresh of the company’s iMac line of desktops.

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