Available technologies can be divided into two principal types – direct emissive, and modulated. The former category includes OLED and micro-LED, whilst the latter describes technologies such as Liquid Crystal on Silicon (LCoS) and Digital Light Processing (DLP MEMS). Modulated displays generally incorporate three bespoke components:
- External light source
- Combiner optics
- Pattern generator
In this case the light is first directed to the external pattern generator. The image is then formed by either switching on or off each pixel in the array. For this type of non-emissive system, light must always be incident on every pixel. Consequently if only 15% of the pixels are typically on (e.g. to form standard images on video and HMDs) then 85% of the incident light is wasted. This is an undesirable trait for any portable application where battery life is paramount.
Direct emissive technologies such as OLED or micro-LEDs avoid this problem. The three components required in the modulated approach are combined into a single light emitting array. Thus, there is no “dumping” of unwanted light.
Whilst OLED displays share this advantage with micro-LEDs, they are limited in brightness and experience short device life-times when run in higher brightness conditions. Micro-LEDs have been demonstrated operating with at least thirty times the brightness of an OLED display. For this reason, mLED’s microLED technology delivers a unique, elegantly simple, ultra-high brightness solution.