Everything You Need to Know About Mini LEDs

With Apple becoming the latest company to adopt Mini LEDs for their screens, everything points in the direction that these could be the future of display tech

Adwitiya Pal
May 7 · 5 min read

You’ve heard of LCDs, LEDs and OLEDs. Almost every electronic device with a screen uses one of these to display information to you. For a long time now, they have consolidated themselves as the usual suspects when it comes to powering a screen. However, the display world looks set for a shake-up with the introduction of Mini LEDs in the arena.

On March 20, Apple launched two new iPad Pro models in their Spring Keynote event. The larger of those models, with a 12.9” screen boasts a new display with Mini LEDs, instead of the LED displays used in previous generations and this year’s smaller sized model. But what exactly are Mini LEDs?

Well, they are exactly what they sound like. Mini LEDs are required to be less than 0.2 mm in diameter, almost a fifth the size of what a conventional LED measures. However, new Mini LEDs being developed today can be smaller than a tenth of a millimetre.

But before understanding how Mini LEDs work and why are they important, it’s essential to understand how modern display technologies work.

The chunky, blocky television sets you saw in your grandparents’ house were powered by ‘Cathode Ray Tubes’. They were replaced by the modern and thin LCDs, or Liquid Crystal Displays in the late 2000s. But it’s not just televisions where LCD is used. Remember, the old Nokia handsets with a dull, cloudy display? Believe it or not, those were LCDs! Even most calculators today use simple LCDs too.

What separates the vintage monochromatic look from the sleek panels you’re more familiar with is the presence of a backlight. These displays have a source of light, usually fluorescent, in the rear end that shines through the liquid crystals. The crystals, which are nothing but organic molecules, have an overlay of red, green and blue filters, dividing them into sub-pixels. Using a thin-film transistor (TFT), the current flow can be controlled which allows the intensity of each sub-pixel to be adjusted to make up the desired colour for the entire pixel.

But the problem with normal LCDs is that since the entire display is powered using a common source, the screen can never achieve true blacks as the backlight has to remain on all the time. So when a part of the screen should be black, it appears as kind of a dull, dark grey. In addition, fluorescent lamps are not really great when it comes to maintaining colour accuracy.

In come the LED displays, which is more of a misnomer since they use the same technology as their liquid crystal counterparts, only swapping the fluorescent backlight for light-emitting diodes, or LEDs. These LEDs are located either on the edges of the screen, or as is the case with most devices today, have an entire array of LEDs lighting up the back of the LCD.

LEDs are lighter, consume less energy and are much more colour accurate than the previous LCDs. With the full-array LEDs, the problem of lacking true blacks is also solved to some extent. The LED grid is divided into zones which can be controlled to decrease their brightness as low as possible. This feature called ‘zone dimming’ helps in achieving truer blacks. However, there still persists an issue of blooming, which usually occurs when the light from brighter zones bleeds over into surrounding parts that are supposed to be dark, creating a halo effect.

Halo or blooming effect, with and without local dimming

With OLEDs, or ‘Organic LED’ displays, this concern has been efficiently negated. Instead of using a backlight with a liquid crystal filter, they use LEDs with an organic film that glows when a voltage is applied, and can be made to be extremely thin, small and flexible. So, the pixels are self-illuminating and can be turned on or off individually. The results are the truest of blacks with a great contrast ratio, wider viewing angles and added smoothness of image.

For some time, OLEDs appeared to be the future of display technologies going forward. However, they aren’t without their frailties. There have been numerous cases of screen burn-ins in smartphones and tablets, raising questions on their longevity. OLEDs also aren’t able to achieve as high brightness levels as LEDs. However, their biggest limitation is that they are still terribly difficult to produce. The industry has quietly suffered setbacks in production and manufacturing, leading to a low supply rate and high prices.

Mini LEDs aim to change this. They use the same principles as full-array RGB LEDs, but the difference in size goes a long way in eminently improving the display quality. Being much smaller, the number of LEDs that can now be fit in the same screen increases by a huge margin. This means that manufacturers can divide the display into thousands of zones, which would have been impossible without the Mini LEDs. Apple’s new iPad Pro, in fact, has over 10,000 Mini LEDs (the previous model had only 72) and is divided into 2,500 local dimming zones.

More local dimming zones resolves the issue of blooming prevalent in standard LEDs, since the individual grid sizes are so small, they can be controlled with such a precision that eliminates any bleeding of light from the brighter parts of the screen and improves the overall richness of the blacks. Mini LEDs can also reach higher peak brightness than OLED screens, all while maintaining a wide colour gamut and a sharp contrast ratio. This is particularly great for viewing HDR, or high-dynamic range content.

As forays into this technology have only recently started yielding consumer products, there aren’t a whole lot of options to choose from. At this year’s CES, which has all but turned into a Met Gala for stunning display innovations, TCL, Samsung and LG showcased their TVs powered by Mini LEDs. One important thing to note though, is that they are rumoured to be priced lower in comparison to when OLED TVs first came out, and by the time that they are available in mass markets — estimated to be next year — expect them to be priced aggressively against the current OLED competitors.

This isn’t to say that Mini LEDs are solely the future of display technologies. With breakthroughs in Micro LED (a radically different technology than Mini LED) and Samsung’s QLED TVs hitting the market, things are going to get heated up in the sector. Apple’s endorsement of the technology, however, is a powerful statement. There are also reports that the new 16-inch MacBook Pro is set to feature Mini LED screens. With increased competition on the horizon, one thing’s for certain: Mini LEDs are destined to get better and cheaper, and could soon become a common sight in electronics.

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