Ulrich Barnhoefer, Moon-Jung Kim, and Mattan Erez A Low Power, Passively Cooled 2000 cd/m2Hybrid LED-LCD Display

In this paper, we describe a hybrid LED-LCD screen that delivers the same image peak-brightness at 1/2 to 1/20th the power consumption per unit LCD screen area compared to conventional designs. Our architecture is based on an adaptive, spatially controlled LED backlight and a unique algorithm that decomposes the displayed image into LED and LCD components in order to minimize power consumption. In addition to the efficiency gained over current displays, our implementation is also suited for high dynamic range applications, achieving a peak brightness of 2000 cd/m² with a 20,000:1 contrast ratio. We introduce, for the first time, implementation details of a spatially adaptive LED-LCD display and describe a novel thermal and electrical design. Our display is comprised of a standard FR4 PCB populated with an array of individually controlled high brightness LEDs, their associated control electronics mounted, and a LCD panel. The use of standard PCB (no metal core) is made possible by carefully designing efficient driver electronics (76% efficiency), introducing thermal channels to a large integrated heat sink implemented as part of the PCB, and employing power-reducing decomposition algorithms. Our prototype is completely passively air cooled, silent, and light