White-light emission from near UV InGaN-GaN LED chip precoated with blue/green/red phosphors

Phosphor-converted light-emitting diodes (LEDs) were fabricated by precoating blue/green/red phosphors onto near ultraviolate (n-UV) LED chips prior to package into LED lamps. With a 20-mA injection current, it was found that the color temperature T-c was around 5900 K and the color-rendering index R-a was around 75 for the n-UV+blue/green/red white LED lamps. It was also found that no changes in color temperature T-c and color-rendering index R-a could be observed when we increased the injection from 20 to 60 mA. These results indicate that such n-UV+blue/green/red white LEDs are much more optically stable than the conventional blue+yellow LEDs.