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: Why size matters
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 light source, while an LCD matrix and color filters take care of color and controlling how much brightness comes through.
As their names suggest, LED and QLED TVs use LEDs as their backlights. Inexpensive models 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 behind the LCD matrix. 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 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
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 held only hundreds.
A 4K TV has just over eight 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, you can still see a big difference.
It’s all about the light (and the dark)
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, somewhat oddly, leads to better darkness too.
To achieve a deep, dark black on a backlit TV — the kind you expect when looking at space scenes, you need to shut off the backlight entirely. If you have hundreds of LEDs to work with, you can control which zones of the screen are dark, which is known as Full Array Local Dimming (FALD). 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, FALD 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. So far, we haven’t seen a mini-LED TV that gets quite as perfectly black (and without any blooming) as OLED, but that gap is smaller than it has ever been.
Where does QLED fit into all of this?
QLED, or quantum dot LED, uses nano-particles that have a special property: When light shines on them, they emit their own light. When these quantum dots are placed strategically between the backlight and the LCD matrix, it improves brightness and color. Top of the line QLED TVs now possess an image quality that comes very close to OLED. Their brightness and vivid colors are 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 mini-LED’s 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: Screen sizes can be bigger and prices can be lower than the equivalent OLED TV. As the technology matures, we can expect to see mini-LED play a big role in driving up image quality while driving down the price of both LED and QLED TVs. There may also be gains in power-efficiency, as many smaller LEDs can achieve the same brightness as fewer larger LEDs yet they need less energy to do so.
Who makes mini-LED TVs?
At the moment, only TCL makes mini-LED TVs. It released its first mini-LED TV — the 8-Series Roku TV — in 2019. We were impressed by it but weren’t fully convinced that it was an OLED-killer. Its next mini-LED TV will be the 2020 6-Series. The 2019 6-Series is already our vote for the best value in a 4K TV and we’re excited to see how it improves yet again with mini-LED.
These mini-LED TCL models might just be the company’s warm-up act. TCL announced its latest version of mini-LED at CES 2020, which it calls Vidrian Mini-LED. Though we haven’t seen a TV that uses it, TCL claims that Vidrian Mini-LED displays will produce “unrivaled levels of sharp contrast, brilliant luminance, and highly stable long-life performance.”
Is that hyperbole, or the real deal? We can’t say for sure, but we do know that Sony, LG, and Samsung are all working on mini-LEDs too, so we expect that it won’t be much longer before it becomes the primary way LCD-based TVs are backlit.