Ultra-Thin LED Backlight System with Tandem Light Guides for Large LCD-TVs

We developed an ultra-thin RGB-LED backlight (BL) system for 52"and 65" LCD-TVs. It is constructed by combining the structures of the direct-lighting and edge-lighting systems. The system can be used to control luminance both spatially and temporally with pulse-width-modulation-driven RGB-LEDs so that it can easily support local dimming techniques of an LCD-TV, which provides a high-quality image and have low power consumption. We describe how we improved the optical design of the tandem light guide (TLG) and thus make a 10-mm thick BL. We also introduce how to correct device-to-device variations and temperature characteristics of RGBLEDs. Furthermore, we show how to estimate the optical properties of BLs in terms of the requirements for local dimming techniques. We found that a BL system Using TLGs has a higher contrast ratio between controllable and segmented blocks than conventional ones. This leads to our system being more suitable for local dimming techniques.