In contrast to transmissive LCD, reflective LCDs (RLCD) can be viewed without any internal light source, if there is enough ambient light available. This means power consumption can be greatly reduced. However, for the reflective LCD to be used in dark ambience, a front light unit (FLU) is needed.
A clear advantage of an LCD over EPD is the high refresh rate and wider color gamut. However, there is a fundamental difference between the RLCD and EPD in their optical reflection behaviors; EPD is paper-like (diffuse), whereas RLCD is a mix of mirror- and diffuse-like reflection (semi-specular) properties. This sets stricter angular requirements for the illumination of an RLCD. Unlike for EPD, shallow light incidence is not usable for illuminating an RLCD, since the reflection pattern would fall outside the viewing cone of the display, which is rather narrow.
Nanocomp microstructures allow for steep enough illumination angle from the F/L, ensuring that the light reflected off the display will meet the useful viewing cone of the display. The peak illumination angle can be further adjusted to support the specific optical characteristics of the display in question, such as luminance and contrast ratio related qualities, as well as the intended viewing directions. Here, it should be noted that the bonding method of microstructure surface to other layers of the display stack will affect the achievable light extraction angles (air bonding vs. adhesive bonding). Nanocomp multilayer refractive index (RI)-tuned solutions can bring an additional advantage here.
The above-mentioned two reflective display technologies are clearly the mainstream, but there are many other variants and implementations out there which deserve to be watched. Overall, there is a favorable trend in reflective display technology due to their low power and reputation as eye-friendly products. The main applications lie in digital readers, wearables, tablets of all kinds, digital signage, and even smart phones.