What is microLED

MicroLED (aka micro-LED, mLED, µLED) is the newest and most anticipated development in the field of displays, which is tipped to be the “killers” of OLED and quantum dots. There is very little official information on microLED, and it has to be collected literally bit by bit.

There are many different definitions of microLED (micro light-emitting diode), and the simplest one sounds like “technology of microscopic inorganic self-luminous LEDs.” The list of interested parties speaks about its potential. Even giants like Apple and Facebook have acquired microLED startups to use on their future devices.

We hasten to upset those who are already rubbing their hands in anticipation. According to the latest news, we will not see the first serial microLED displays until 2023 in some smartwatches. The appearance of TVs and monitors on the mass market should not be expected earlier than 2026 – and this is according to the most optimistic forecasts that were made even before the COVID-19 pandemic. Of course, the most impatient will be able to buy an exclusive microLED-TV even tomorrow, if they are not confused by the price of hundreds of thousands or even millions of dollars.

The technology was discovered about 20 years ago by a group of scientists from Texas Tech University. The main problem that could not be solved was the lack of diode control. Finally, in 2011, they created the first actively controlled self-emitting microLED display with a resolution of 640 x 480 pixels, which was able to show moving images.

In 2012, Japan’s Sony showed off the first working prototype of a microLED TV called the Crystal LED. It had Full-HD resolution and contained six million LEDs. Already this model has surpassed conventional LCD TVs in contrast, color gamut and response speed.

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Since that time, more than a hundred companies have joined the race for microLED: Samsung, LG, Konka, Facebook (InfiniLED), Apple (LuxVue) and many others. In 2017, Sony unveiled its new vision of microLED – CLEDIS (Crystal LED Integrated Structure). The company claimed it could offer no worse contrast than OLED at over 1,000 nits.

The technology made a big splash in 2018 at CES when Samsung unveiled its The Wall series TVs. Unlike commercial CLEDIS, the first civilian Samsung models were promised to us in 2019, then in 2020, but things are still there. The 75-inch microLED TV, on which the company is focusing its efforts, has again been postponed indefinitely. Reportedly, the Korean tech giant has faced a number of financial and manufacturing challenges and hasn’t even begun mass production of microLED matrices to date.

The microLED array is a collection of miniature color self-emitting inorganic LEDs on a substrate. The size of diodes, as a rule, does not exceed a few microns.

As with other types of sensors, thin film transistors (TFTs) are used to drive each pixel. MicroLED has no additional illumination: each subpixel glows by itself. The matrix structure is very similar to OLED , but instead of organic material, it uses inorganic gallium nitride (GaN). Also, unlike modern television OLEDs with initially white subpixels, in microLED, a pixel is immediately recruited from three color LEDs, and therefore additional color filters are not required.
The key difficulty of the technology is the microscopic size of diodes, which should be one hundred times smaller than conventional ones.
A unique feature of microLED televisions is their modular design. The display can be customized to almost any shape, aspect ratio and even size.

The resolution can be 2K, 4K, 8K and 16K, and the pixel density is independent of the screen size. In this case, the boundaries between the modules are not visible, since the thickness of the frames is no more than the inter-pixel distance. For the same reason, there are no external frames.

At CES 2020, Samsung’s latest panel was put together in front of astonished viewers. In the new generation of The Wall, the articulation of modules does not even require cables – the blocks are connected according to the principle of a constructor and are connected automatically, and the TV processor builds an image based on the number of segments.

Due to the love of manufacturers for consoles mini-, micro- and nano-, which they want to emphasize the features of their technology, microLED is periodically confused with Mini-LED . The latter is just a special kind of backlighting, which consists of conventional smaller LEDs and has an increased number of local dimming zones.

Technology advantages
It is difficult to objectively talk about the advantages of microLED, which has not yet entered mass production. We can only compile the potential benefits that technology developers tell us about.

Brightness. According to the specifications, the brightness of microLED panels has already surpassed the 1000 nits bar. This allows you to realize all the possibilities of HDR technologyand comfortably watch such a TV in a bright room.
Depth of color. The ten-bit matrix provides high-quality image transmission without sharp color transitions.
Infinite contrast and perfect blacks are realized by completely individually turning off any pixel (similar to OLED ).

Viewing angle. Thanks to the small number of layers, the microLED has maximum viewing angles without loss or inversion.
Color gamut. Already, this parameter reaches 140% sRGB and 85% Rec. 2020. The latter figure is planned to be increased to 100% by applying quantum dot technology (QNED) to the microLED.
High energy efficiency. It would seem that a characteristic that is not fundamental for TVs becomes relevant when it comes to the huge diagonals that are typical for microLEDs.
No burnout . MicroLED is the main hope of users who don’t buy OLED TVs for this very reason. According to experts, gallium nitride used in microLED is not subject to fading. Whether this is so, we will not know for a long time.
The modular design makes it possible to assemble a home theater of any diagonal (up to 292 inches and even more) and, finally, forget about projectors.
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Known disadvantages of microLED
Pixel density is not the strongest point of the microLED yet. The problem lies in the block design – at the current ppi, the frames around the modules are equal in thickness to the distance between the pixels (so that a seam does not form on the screen). Accordingly, the higher the ppi, the more difficult it will be to implement it.
Thickness. Here is an image of one of the SONY ZRD-2 (CLEDIS) blocks. As you can see, it is difficult to call it thin.
Therefore, this beauty …

Complex production. The main problem with microLED TVs is the transfer and fixing of millions of LEDs on the substrate. To create, for example, a 4K matrix, it is necessary to install and correctly configure 25 million inorganic LEDs with the same dimensions and brightness, which is a very difficult task for mass production. Hence the next disadvantage of modern microLEDs.
High price. One of the once-stated advantages of microLEDs is the lower (compared to OLED) production costs. Structurally, a microLED matrix is ​​simpler than OLED, and gallium nitride LEDs are cheaper than organic ones and are less susceptible to fading. However, as mentioned above, some technological and production barriers have arisen, and therefore the price of modern microLEDs tends to infinity.
Market offers
Samsung has announced several commercial and civilian microLED TV designs. For home use, the company plans to sell TVs with screen sizes of 75, 88, 93 and 110 inches. In addition to the possible sizes and an incredible peak brightness of 5000 nits, it was not possible to find detailed technical specifications on the manufacturer’s official website.

In mid-2020, LG unveiled its 163-inch MAGNIT LSAB009 model , which was the company’s engineers’ answer to Samsung’s The Wall. Among the known characteristics, we note small modules measuring 150 × 168.8 mm with a resolution of 160 × 180 pixels, a peak brightness of 1200 nits and a wireless connection of the blocks. The declared service life is 100,000 hours.

Neither Samsung nor LG have announced the prices for their devices yet (although according to rumors, one The Wall module costs about $ 22,000, but this is not certain ). But Sony did it. The CLEDIS Energy Efficient LED Display is a 403 x 453 mm (320 x 360 dots) multi-block assembly. For FHD resolution, 18 such modules are required, 4K – 72 modules, 8K – 288 modules, 16K – 576 modules. Now the most interesting thing is that the price of one block is $ 10,000. We suggest equipping yourself with a calculator and calculating how much such a microLED panel will cost for an impatient and wealthy user. And do not forget that one or more ZRCT-100 / ZRCT-200 controllers are additionally required for operation.