Toshiba, Toyoda Gosei Develop White LED Using UV-LED
Toshiba Corp and Toyoda Gosei Co, Ltd have developed a white light-emitting diode (LED) using a 380nm GaN ultraviolet (UV) LED as the light source. Sample shipments start in April 2001, as light sources in automotive equipment and liquid crystal display (LCD) backlights.
The UV-LED active layer is thought to be an In x Ga 1-x N/GaN multi-quantum well on a sapphire substrate. It includes phosphors in the three primary colors, red (R), green (G) and blue (B), which enhances color reproduction when used as an LCD backlight. Conventional white LEDs, combining GaN blue LED and yttrium-aluminum- garnet (YAG) phosphors, create white light by mixing the blue LED light with the yellow phosphor light, which diminishes color reproduction because of the minimal red content.
The emission efficiency of the new device is still low (4.5 to 5.0 lm/W), compared with the blue LED-YAG white LED from Nichia Chemical Industries Co, Ltd, which has an efficiency of 15 lm/W. Toshiba and Toyoda hope to boost the emission efficiency of the UV-LED and conversion efficiency of the phosphors to achieve 10 lm/W by the fall of 2001.
(April 2001 Issue, Nikkei Electronics Asia) |
