Novel technologies for ultra-slim LED direct-lit lighting devices

Summary form only given. Direct-lit LED flat lighting devices have brought more attentions due to their 2D local dimming features for power saving in large size LCD TV applications. However, how to reduce the device thickness while still maintaining a high brightness and uniformity becomes a challenge. In this paper, advanced LED flat lighting technologies in recent development will be reviewed and a break-through in direct-lit LED lighting panel having an ultra-slim format will be introduced. The effects of device thickness on the brightness of light emitting surface of a LED direct-lit flat lighting device will be presented, which have led to a direction for enhancing luminance of ultra-thin lighting devices toward flexible lighting applications. Different LED direct-lit lighting devices were used for investigating the effects of device thickness on the device brightness. The test results showed that the luminance of a light emitting surface of the LED lighting devices increased with decreasing the distance between the light source and the light emitting surface, which implied that the brightness of a flat lighting device may be enhanced by decreasing the device thickness. This finding may lead us to a different approach for building an ultra-thin lighting device toward flexible lighting applications.