If you are a “fruit fan” and have some “screen control”, the word “mini led” should not be unfamiliar. Last year, in Apple’s iPad pro and MacBook Pro, the “mini LED screen” was highlighted. In fact, apple is not the first person to eat crabs. Manufacturers such as Samsung, LG and Dell also launched their own mini LED products around 2020, covering TV, display, car display and notebook.

What exactly is a mini led? Why can it become the “fragrant pastry” in the hands of many businesses? Before clarifying these issues, let’s briefly review the development of display technology.

Once Kings

The earliest display technology was called cathode-ray picture tube technology (CRT), which was invented by Karl Ferdinand Braun, a German physicist. The picture tube based on CRT technology also became the most important component in black-and-white and color TV sets.

Although such TVs have entered museums from the living rooms of every family, in fact, the life cycle of CRT technology is very long. It was not until the 1980s and 1990s that CRT technology was gradually replaced by the second-generation display technology – liquid crystal (LCD) and plasma (PDP).

Due to the difference in imaging principle and manufacturing process, LCD was mainly used for small screen at first, while PDP was mainly used for large-size and high-end display market with 40 inches and above (PDP screen performed well, but the price was expensive). Therefore, for a long time, LCD and PDP technologies were once equal in the industry. Next, the rapid development of semiconductor technology has made it possible for LCD technology to be used in large-size screens (increased yield and reduced cost). Since then, LCD has become the mainstream of the display market around 2007. On the other hand, with Panasonic, which has always adhered to plasma technology, shutting down plasma TV at the end of march2014, PDP also officially withdrew from the historical stage.

The “King” in the field of technology is usually temporary. After the golden age of LCD lasted for about 20 years, a revolutionary display technology – organic light emitting diode (OLED) technology can’t wait to rise again.

Who leads the display technology in the new era?

OLED looks like an O in front of LED, but it is actually a completely different thing. It is a sandwich like film composed of indium tin oxide, power cathode and metal cathode, not a lamp bead like LED. OLED is characterized by its self illumination property. Unlike LCD, which requires light source, OLED consumes less energy. This has also enabled OLEDs to shine brightly in the smart phone field of “one grid of electricity and one inch of gold”. With the production cost reduced to the same level as LCD, OLEDs have also entered emerging markets such as VR.

Of course, OLEDs are not perfect. On the one hand, in large-scale applications, although OLED has improved in display vision, cost reduction has not been achieved, which also hinders its further expansion in the market; On the other hand, due to the limitations of light-emitting materials and dimming principle, OLED brightness is limited, and there is still a large gap between the maximum brightness and led, so the gray performance has been not very good. In addition, OLEDs are made of organic materials, which are prone to aging. If the same pattern is displayed for a long time, the pixels in this area will experience irreversible light decay, which is often referred to as “screen burning”.

In the face of the strong attack of OLED, the LCD industry also has to deal with it. This is the mini led we mentioned at the beginning.

The intuitive explanation for the mini LED is that the size of the smaller LED is usually less than 100 microns. It is a combination of LCD display and a new LED backlight technology. Mini led uses large-scale led beads as backlight. Through the control of tens of thousands of LED beads, it can accurately control the brightness of the display area, so as to improve the contrast and peak brightness of the picture and retain more picture details. However, mini LED is the continuation of LCD display after all. Even though it can achieve more fine zoning control, there will still be halos on the dark screen, and the current cost is still high.

Just as people are talking about the merits of OLED and mini led, a new term has emerged – micro led. From the name, it looks like an upgraded version of mini led, but it is actually closer to OLED. This technology can be seen as a combination of mini led and OLED.

Micro LED is to transfer the LED backlight to the circuit substrate in batches after it is thin-film, miniaturized and arrayed, and then add the protective layer and electrode to make the display screen after it is packaged. Each LED unit can be used as a light-emitting display pixel, which can be addressed and driven independently, saving power and fast response. In other words, the essence of micro LED is to make the “lamp beads” on the mini led smaller and denser, and then use the whole “LED panel” directly as a self luminous display panel. Therefore, it not only inherits the lamp bead array form of mini led, but also has the self luminous characteristics of OLED.

Although the appearance of micro LED is a bright spot, there are still many technical bottlenecks on the road of commercial use. For example, how to make LED particles with smaller units? How can these micron level LEDs be transferred to the substrate, bonded and circuit driven? How to reduce the cost?

Therefore, from the perspective of the current market, the commercialization of micro led still has a way to go. In the next few years, mini led and OLED will face each other.

According to the data forecast of cinno research, after the mini LED backlight is launched in 2020, large-scale mass production can be realized in 2021. The shipment of backlight chips will reach 890000 wafers. It is expected that this number will increase to 6.26 million by 2025, and the annual shipment of mini LED backlight modules will reach about 170million. The TV and display markets are taking the lead, the notebook and flat panel markets also have great potential, and the vehicle market will also become an important market in the later stage of mini led.

OLED is still the mainstream of smart phone displays. According to omdia’s data, OLED displays will account for 40% of smart phone displays in 2021, and OLED shipments are also growing in the large-scale market.

epilogue

At present, it seems that the topic of which is better or worse between OLED and mini LED will continue to be verified in the market. As a potential competitor, micro LED can really enter the market, and it is expected to break the rivalry between the two. After all, as a large number of users, what we really need is that the products can constantly push through the old to bring forth the new, and bring better use experience and cost performance. Only when new people come in from time to time to “disrupt the situation”, can the industry not fall into a backwater, so as to maintain its vitality.

Reviewed by: Pengjing

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