Luminit’s 100° Micro LED Diffuser for Wearable and Portable Displays

Submitted on Fri, 07/28/2017 - 16:12

Micro LEDs (mLEDs) are gaining attention in the display industry, particularly for wearable and mobile devices. Ranging in size from 1 to 10 microns and spaced less than a millimeter apart, micro-LED displays are astonishingly bright and more energy efficient than LCDs and OLEDs. While the technology is promising, engineers face challenges when designing mLEDs into small, portable displays such as smart watches where space is limited and resolution is critical. Some key challenges, however, are being overcome with Luminit’s 100° Micro LED Diffuser (MLD).

 

Challenge: Closing the Screen Door without Losing Resolution

Like standard LEDs, micro LEDs are discrete light sources that require diffusion. However, because mLEDs are smaller than a pixel, diffusion is even more critical due to what’s known as the screen door effect, or fine black lines that appear between the pixels. If you’re 10 or 20 feet away from the display, you’ll likely not notice the lines; however, less than a foot away (e.g., glancing at a smart watch or tablet), the screen door effect can be quite noticeable.

screen door effect on LEDs
The screen door effect can be noticeable on smaller displays where viewing is up close.

Adding a diffuser film can eliminate the screen door effect, but the diffuser material must be mounted extremely close to the mLEDs in order to avoid internal reflection. For a diffuser to be effective, however, there needs to be enough distance between the film and the LEDs in order for the light to spread out before the diffuser and after the diffuser. If the screen door is 10 microns wide, you’ll need a 10-micron gap. Because standard bulk diffusers use a random scattering pattern with high back scatter, there will be some light loss; therefore, eliminating the screen door effect will come at the expense of resolution, brightness, and efficiency.

Solution: 100° Micro LED Diffuser

Like all Luminit diffusers, MLD is based on the principle of surface scatter instead of volume or random scatter.  The high transmission LSD structures are non-scattering in nature and utilize light that would otherwise be wasted. Luminit LSDs have a much higher transmission efficiency (~92%) than conventional diffusers because surface relief scatter is much more efficient. The light hits the diffuser once, resulting in no significant loss of light or display resolution because internal reflection is eliminated.

Challenge: Creating the Widest Possible Beam Angle

Engineers design most displays with the widest viewing angle possible. However, unlike most fixed displays, wearable technologies and portable devices such tablets and smart watches are viewed up close and at virtually any angle.

Solution: 100° Micro LED Diffuser

MLD incorporates a 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 optimally spread for more even and uniform coverage.  Luminit’s MLD also enables designers to build thinner profile displays, which is another critical factor in hand-held or wearable displays where product designers and engineers covet even 10 microns worth of space.

How Does 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).

light diffuser profiles
LSD surface relief structures manipulate light by changing the direction of its energy. The steeper the structure, the higher the beam angle.

Luminit offers the widest selection of elliptical and circular diffusion angles in seamless rolls, mini rolls, injection molded, custom cut and volumetric formats.

For more information about our Micro LED Diffuser, contact sales@luminitco.com