Sep 5, 2017: Micro LEDs are slowly, but steadily making its position in the display industry, particularly for wearable and mobile devices. They range in size from 1 to 10 microns, and less than a millimeter apart.
Micro-LED displays are brighter and more energy efficient than OLEDs and LCDs. Although the technology has immense potential, designers face challenges while designing micro-LEDs into small, portable displays like smart watches, where space is limited. Some key challenges can be overcome with Luminit’s 100° Micro-LED Diffuser (MLD).
Closing screen door without losing resolution
Micro-LEDs are also discrete light sources like standard LEDs. However, as micro-LEDs are smaller than a pixel, diffusion becomes more critical due to screen door effect, or fine black lines that appear between the pixels. From close, the screen door effect is quite noticeable.
Screen door effect on LEDs
If a diffuser film is added, it can eliminate the screen door effect. This diffuser material should be mounted very close to the micro-LEDs just to avoid internal reflection. If you want the diffuser to be effective, there should be enough distance between the film and the micro-LEDs so that the light can spread out before the diffuser and after the diffuser. If the screen door is 10 microns wide, then a 10-micron gap is needed. As standard bulk diffusers use a scattering pattern with high back scatter, some light will get lost. As a result, eliminating the screen door effect will impact on the resolution, brightness, and efficiency.
What can be done
Luminit diffuser MLD is based on the principle of surface scatter instead of volume or random scatter. The high transmission LSD structures are non-scattering and utilize light that would otherwise get wasted. Luminit LSDs have higher transmission efficiency (~92%) than conventional diffusers as the surface relief scatter is more efficient. Light hits the diffuser once, resulting in no loss of light or display resolution as internal reflection is eliminated.
How to create wide beam angle
Designers design displays with widest viewing angle. But, wearable technologies and portable devices like smart watches, tablets, etc, are viewed from close and from any angle.
Here Luminit’s MLD is the best solution. It incorporates 100° angle FWHM—the widest beam spread available on the market and the closest to a lambertian pattern possible. Even the tiniest point of light will be spread for more uniform coverage. Luminit’s MLD also help designers to build thinner displays.
How Luminit’s micro-LED diffuser work?
MLD works on the same principle as Luminit’s Light Shaping Diffusers (LSDs). Invisible to the naked eye are holographically recorded LSD microstructures embedded on polyester or polycarbonate film. When applied to a light source, the film conceals and controls the output of an LED light source and spreads the light depending on the angle of distribution (e.g., 100° circular).