Pixtronix PerfectLight has an energy efficient prototype that uses thousands of very little LED lights controlled by microelectro-mechanical system (MEMS). PerfectLight uses one-fourth the energy of a an Liquid Crystal Display. PerfectLight prototypes consumed less than 50 milliwatts for the backlighting of a smartphone display while a LCD uses about 200 milliwatts.
The image is created with thousands of digitally controlled, MEMS, shutters that open and close over each pixel opening, allowing light from the red, green and blue LEDs to pass through.
Qualcomm's technology uses natural light and MEMs in mirasol. The light for the pixels is provided by ambient light. To create an image, reflective optical structures in the MEMS (which they call IMOD), selectively reflect red, green or blue light to create an image.
The Interferometric Modulator (IMOD ) element is a simple MEMS (micro-electro-mechanical system) device that is composed of two conductive plates. One is a thin film stack on a glass substrate, the other is a reflective membrane suspended over the substrate. There is a gap between the two that is filled with air.
The IMOD element has two stable states. When no voltage is applied, the plates are separated, and light hitting the substrate is reflected as shown above. When a small voltage is applied, the plates are pulled together by electrostatic attraction and the light is absorbed, turning the element black. This is the fundamental building block from which Qualcomm mirasol displays are made.