Thermal Characteristics of LED Light Source in Flat Panel Display Backlight System

Light Emitting Diode (LED) begins to be applied as backlight system in a flat panel display because of local dimming function, wide color gamut, longer lifetime and environmental-friendly feature. The performance of LED device is strongly dependent on the operating temperature, however, the operation beyond temperature limit could cause the luminosity decrease, wavelength shift and lifetime decrease including failure of electrode soldering in the package. Therefore, the thermal management in a LED backlight system is crucial to guarantee the image quality and the reliability of the display. However, narrow volume of flat panel displays cause low convective heat transfer showing non-uniform temperature distribution over the panel. It deteriorates the image quality that the inherent temperature difference over the flat panel display backlight system. The objective of present study aimed to investigate the effect of LED alignment in a direct-illuminating type backlight system. It is discussed thermal characteristics of backlights in flat panel with LED light source and evaluated performance of the heat spreading system to ensure the reliability of LED backlight system.