Design and implementaion of an energy-efficient full-color large-area LED display system

Abstract

Red-green-blue (RGB) light-emitting-diode (LED) is more capable to vary its color in real time, less energy-consuming and more durable than the conventional light source, and thereby has gained increasing popularity in various applications. One of the promising applications of RGB LED is the full-color large-area LED display system. Large-scale LED video displays market has competitive advantages, since few technologies are capable to deliver large size at high contrast and durability. Due to the higher power consumption of the full-color large-area LED display, maximizing the power efficiency has become a major design objective of this type of display system. This thesis demonstrates how the multi-level pulse-width modulation (MPWM) driving method can be implemented on a full-color large-area LED display system through a low-cost modification of the existing hardware configuration. This method uses multiple LED driver modules that are linked in parallel to transfer a MPWM current to individual LED pixels. For a three-level driving scheme, the criterion for selecting the mid-level current in order to maximize the luminous efficacy gain is derived mathematically. The algorithms of video signal conversion, which are designed to derive the sub-video signals from the original high-definition multimedia interface (HDMI) or digital visual interface (DVI) video signals for activating multiple LED driver modules, are also discussed.