Masking LED hot spots in a thin direct lit backlight unit using semitransparent and perforated masks

As the demand for thin displays with more features accelerates, the need for backlight systems to become thinner and capable of multiple features increases. Direct lit concepts supporting 2-D dimming provide higher contrast ratios. However masking led hot spots with thinner backlight thicknesses is yet a significant design challenge. Efficient light coupling and recycling mechanisms in combination with relatively high optical efficiencies are key parameters in overall system design. We demonstrate an optimal masking design of the led hot spot for a thin light guide plate in the direct lit architecture. The overall concept system is simulated and prototyped. The resultant performance is discussed.