🍠 ⛄️ 🆙 LED Display Technology: Micro-LED vs. Mini LED 🐗 💈 🛃

Initially, the task was to figure out what Micro LED is, as well as Mini LED in the field of LED screens for indoor use. Because there is confusion in this market due to the use of the words “micro, mini, nano” for screens created using different technologies. Customers, in turn, thoughtlessly repeat these notorious "micro", "mini" and "nano" in the race for the "coolest" screen, not realizing that these consoles are nothing more than a marketing ploy.

Progress on that and progress to go by leaps and bounds. The screen should be brighter, the colors richer, consume less, heat less, and so on - scientists and engineers are working to improve strong technical features - in every technical detail.

And where there is progress, there is marketing, which uses all kinds of marketing tools to advertise what marketers do not understand. Recognition in the market, sales are important, and technology is the second thing.

LED screens

They are divided into internal and external screens. For fixed installation and rental. All new technologies allow us to improve the technical features of LED screens in terms of power, mounts, new boards, as well as the step and size of the LED itself or, in another way, a pixel.

Pixel pitch or pitch is the distance in millimeters between two adjacent centers of the LEDs. Each year, a kind of technological mini-breakthrough occurs, when a company represents a record-less pixel pitch. By shortening the distance, the dimensions of the LED itself are also reduced.

LED Technology

DIP - The Direct In-line Package. This technology is used for external screens, where a separate LED is used for each color. The pixel pitch is greater than or equal to 6 mm.

SMD - Surface Mounted Device. This type of 3-in-1 technology is conventionally a technology for the production of LED screens. It is used for internal screens and for external ones, - an LED, in the case of which three RGB LEDs with a certain step are already installed.

DIP technology of color separation into three different cases allows to obtain high color saturation and provides ease of installation. On the other hand, in SMD 3 in 1, the overall colors, due to the use of RGB in one case, are more uniform. This is the standard technology used in high-quality LED screens. Surface mount technology is also used for outdoor screens.

COB - Chip-On-Board. This technology is used for internal screens by growing an LED, also consisting of three-color LEDs located directly on the board.

SMD 3 in 1

Nearly all indoor screens use surface mount technology. To create LED screens, it is required that each LED, a pixel, can emit red, blue, green colors - therefore, in each small LED there is 3xLED, respectively, and the technology is called SMD 3in1.

Simple and proven technology. First, crystals are grown on sapphire substrates, then LEDs are created. After - manufacturers of LED walls acquire LEDs and, through SMD technology, create LED modules from which video walls are assembled.

The process has been worked out, it is simple both in installation and in maintenance - that is, a non-working LED is removed and a new one is soldered. There are nuances that not all LEDs shine the same, so when buying a screen, LEDs of the same batch are purchased. There are also differences in the metal used in the conductors - if gold, then the quality is higher, in fact, like the cost of the LEDs themselves and the finished screen. When commissioning, there is no difference, only after a period of time you can see the differences.

Since the LEDs are soldered to the board - with high-quality cleaning of rooms, when wiping the screen with a rag, small LEDs come off their seats. And after a while - the picture becomes not so pleasant to the eye. However, these are already operational problems - after all, you can limit the circle of people with access to the screen.

The problems began after the companies crossed the distance between LEDs less than 1mm. Since, in addition to the distance, the LED also decreases, firstly, the soldering complexity has increased, and secondly, the LEDs themselves have become poorly held in their seats.

Therefore, we decided to assemble each SMD 3in1 LED into a group of 4 LEDs and then solder in groups.

IMD 4 in 1

IMD - Integrated Mounted Device. Surface Mount Technology IMD 4in1 represents not one SMD 3in1 LED, but 4 such LEDs in one group. After, due to the increased area, the groups are soldered to the main seat. Currently, 4in1 groups are mainly represented on the market, however, 9in1 and 16in1 are expected to appear soon.

At the same time, the steps of the pixels became smaller, the LEDs themselves also became smaller, and the ease of installation remained. Today, there are prototypes of screens with a pitch of 0.5 mm and 0.6 mm, made using this technology. They were presented at the ISE2020 exhibition.

Also, to protect the LEDs at such pixel steps, GOB and AOB technologies are used to fill both the LEDs completely and only the “legs”.

COB - Chip-on-board

An example is shown in the picture on the left: on the left is a COB technology LED screen, where each pixel does not have a housing, on the right is IMD4in1 technology.

An alternative technology for creating crystals and LEDs is to grow them directly on the board itself. The technology has been known for a long time, but has recently become widespread - for mounting LEDs on a board with very small pixel steps.

The chip also consists of three RGB LEDs. According to technology, the crystal can be turned upside down, soldering is not required, since the crystal is grown on a circuit board. Accordingly, in the future, manufacturers plan to completely abandon soldering for a small pixel pitch, removing the existing shortcomings of SMD technology.

After growing LEDs - manufacturers of LED screens using this technology - fill the modules or cabinets with LEDs with a special optically transparent compound or gel to protect the LEDs.

The screen becomes smooth, similar to the screen of LCD panels. From the immediately following advantages - there is a protection of the LED curtain from mechanical damage, for example, when cleaning. It is clear that the compound does not provide protection against mechanical stress.

Compared to conventional SMD surface mount technology, COB allows you to increase the density of LEDs in the same area. As a result, even greater uniformity of pixelation for the user is achieved.

Each stage of technology development tries to eliminate the shortcomings of the previous ones. For example, COB technology is designed to, on the one hand, protect LEDs from damage, especially when it comes to very small LEDs, simplify the way of arranging ultra-small LEDs on the board, and further reduce heat generation and power consumption, but the primary thing is the ability to use small pixels no problem soldering.

Compared to DIP and SMD technology, COB LED displays have significant advantages.

Less depth. Due to the possibility of using a thinner board, manufacturers can reduce the thickness of the overall structure. Accordingly, the overall weight of the screen will decrease. The gain in the thickness of the construct, the ability not to strengthen some types of walls, as well as the final cost.
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DIP 100-110 ;
SMD – 120-140 ;
COB – 170 .
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Micro-LED & COB

If literally - then a micro LED. An expression that is used where the dimensions of the LEDs are less than a millimeter. Speaking about the LED sphere - this is Chip-on-Board technology. It turns out that this is a cool marketing move - it sounds cool, micro LED.

Now the facts - who and what is called micro-LEDs. Technology IMD 4in1 and COB - different manufacturing companies called Micro-LED.

For example, from those companies that I know, Leyard Planar presented at the ISE 2020 exhibition a beautiful screen with a pitch of 0.6 mm using 4D1 SMD technology. They call this technology microLED.

Since 2012, Sony has been presenting screens based on COB technology, which is called CLEDIS - Crystal LED Integrated Structure or shortly Crystal LED. The largest screen with a pitch of 1.25mm and dimensions of 19.2x5.4 meters and a resolution of 16K (15360x4320) remains the leader today. Sony calls Crystal LED technology microLED.

For several years now, Samsung has presented the top The Wall screen with a 0.84mm pitch, built on the basis of COB technology (flip-chip RGB LED), also called microLED.

Unilumin at the same exhibition presented a piece of the screen with a pitch of 0.5 mm using IMD4in1 technology. True, they are not called micro-ice; instead, the prefix “nano” appears.

Konka has released a microLED LED panel with a maximum diagonal of 236 ”.

Unlike the above companies, the Chinese manufacturer Absen last year, at the InfoComm China 2019 exhibition, using 4in1 technology, called it mini-LED (we will return to this technology later). The pixel pitch was 0.9mm. A strategically cool solution, subjective, because it shares 4in1 technology and COB. But this is just not the established marketing. Representatives of the company openly stated that this was an advertising move.

Micro-LED & OLED

Emission or “self-emission” is the only thing that combines these technologies. Similar! However, completely different in production technology.

Micro LED is a technology for creating LED paintings, which means building video walls without restricting the diagonal and the ability to assemble non-standard screen shapes. Sony has always been the leader with its 63x17-foot screen, which translates to 783 ”. It is followed by Samsung with the 292 ”presented today, as well as the claimed 583” screen. While OLED technology today has a maximum diagonal of 88 ”.

On the other hand, micro LED technology has not reached the capabilities that OLED can show. For example, coming close enough to the video wall, a person can distinguish individual pixels, due to the insufficiently close / small distance between the individual LEDs. Why the screen will not look as uniform as it is achieved with OLED technology.

It is worth noting that Samsung focused its efforts on capturing the TV market on the development of a 75 ”screen based on micro LED, although there is no information about the technical components. There is no talk of selling.

In other words, the OLED and micro LED pixels have different sizes for different screen sizes. Perhaps in the future, micro LED technology will make it possible to arrange pixels closer to each other, creating competition for OLED. Today, a 75 ”OLED screen will have a resolution much higher than the screen of the same diagonal using micro LED technology.

Probably, looking ahead a lot, we can assume that when Samsung starts to use Micro Quantum Dot LED, a technology with quantum dots instead of conventional LEDs, video wall technologies will revolutionize the pixel density.

Mini-LED & QLED

In fact, there is mini LED technology. And this is not IMD 4in1, these are reduced LEDs to provide LCD backlighting.

There is a statement that this is a kind of transitional technology between LCD and Micro LED - however, it is difficult for me to judge, because the creation technologies are completely different.

In order to answer the question “why”, it is necessary to understand the difference that OLED and QLED technology differ in that OLED stands for organic light-emitting diode, which does not require LED backlighting, as it is implemented in LCD and QLED technology. QLED, although it uses a quantum light emitting diode or in another way nanoparticles called quantum dots, requires backlighting.

At the end of 2019, TCL began selling the first QLED mini-LED TVs. This means that tiny LEDs are used for LED backlighting, which can accommodate not hundreds, but tens of thousands. We gain control over a large number of points. Accordingly, to achieve black color, part of the LEDs is turned off, and the deep black color is realized by means of a simple technology, the cost of which, with the constant development of the technology, should be much lower than the OLED panel.

Result

Summing up, we get that LED screens that use the so-called micro LED technology are not or not always. The micro LED technology applies specifically to the size of the LED, and not to the pixel pitch. That is, in other words - the technology for manufacturing an LED screen with a pixel pitch of 0.9 mm, but with a physical size LED used less than 50 μm - will be called micro LED.

Manufacturers very rarely indicate the dimensions of the LED itself - therefore it is rather difficult to determine whether the LEDs used are microLED or not.

LED Display Technology: Micro-LED vs. Mini LED