04-06-2021 | | By Robin Mitchell
Royole recently demonstrated a flexible display using micro-LEDs. What are micro-LEDs, what are the specifications of the demonstrated display, and could micro LEDs be the dominant display technology of the future?
There are many to choose from when it comes to display technologies, and all have their own advantages and disadvantages. The most common technology for computer screens by far is TFT which stands for Thin-Film-Transistor and utilizes a liquid crystal display (LCD) to block or allow light to travel through colour filters. LED displays are available for larger screens, and while these provide superior optical and energy properties, they are also very expensive and large. OLED displays are those that use organic chemicals to produce light, and these are becoming common in smaller devices and TVs alike.
However, new emerging technology could see these display technologies faced with real competition, and this technology is called micro-LED. Essentially, a micro-LED display uses extremely small and compact LEDs and has the same benefits found in standard LED displays. High contracts ratios are possible as LEDs can be entirely turned on, the lack of colour filters provides exceptional colour clarity, and the use of LEDs creates a very energy-efficient display. Unlike LED pixels, micro-LED pixels are much smaller, and as such can be used in smaller displays (such as smartphones), or provide greater resolution for large displays (such as 8K and up).
Recently, Royole (who research and develop human interfaces and displays) recently announced the development of a prototype flexible and stretchable display that uses micro-LEDs. The display, which has a screen size of 2.7”, has a resolution of 96 x 60 pixels providing a pixel density of up to 120ppi.
While this may not seem impressive, the display can be easily warped and stretched into shapes, around objects, and heavily manipulated with no performance loss. Furthermore, the display can be made far more transparent than current transparent OLED displays (transparency up to 70% compared to OLED 40%).
The flexibility of the display comes from the use of smaller pixels (i.e. micro-LEDs), as this allows for more stretchable material and conductors to sit in-between pixels. Thus, a typical flexible OLED has a higher aperture ratio than the new micro-LED display, and therefore allows the new display to be folded and stretched with no damage to the display. The display shows how cloth-like the new display is as it easily wraps around objects pushing through it.
Micro-LEDs clearly demonstrate that they have great potential, and if they can be manufactured reliably in mass, then all other display technologies face real competition. Firstly, micro-LEDs have better display characteristics than LCDs, providing greater brightness, faster response, and better contrast. Secondly, micro-LEDs can be used in flexible displays as shown by Royole with their latest prototype. Thirdly, their ability to be transparent also makes them ideal for transparent displays compared to other technologies on the market.
Of course, these displays need to improve their DPI to become usable as current micro-LEDs are far too pixelated, and the distance between pixels is too great (clearly visible to the naked eye). However, if this challenge is solved, then such displays could easily be integrated into wearable technology for use as a comfortable wearable display that is not bulky or heavy.
Another aspect of micro-LEDs that may make them the dominant technology in the future is their energy consumption. The world is moving towards improving energy efficiency (some have avoided even bitcoin due to its energy requirements), and consumers of the future may want efficient devices. LEDs provide the best balance of quality to energy consumption of all display technologies, and micro-LEDs are the only practical LED technology for user displays.