Japan's National Institute of Materials Science (NIMS) announced that it successfully prototyped a white LED composed of red and green phosphors and a blue LED chip.
B
y arbitrarily changing the ratio of red, green and blue components, a light source can be designed in accordance with the color characteristics, etc required for a color filter. Used for an LCD panel backlight source, the white LED exhibited a color gamut of 91% of NTSC in the simulation.
"β-sialon" green phosphor (left) and CaAlSiN3 red phosphor (right)
Thus, the latest white LED has a higher color reproducibility than that of the existing LED using YAG phosphors (72%), according to NIMS.
The new white LED is a combination of a blue LED chip and modifications of CaAlSiN3 red phosphor and "β-sialon" green phosphor, which were developed by NIMS thus far. The light emitted by the blue LED with a wavelength of 460nm is converted into 650nm red light by the red phosphor and into 540nm green light by the green phosphor.
As a result, the latest LED can generate three primary colors of red, green and blue.
Thus far, many of the white LED backlights used a combination of a blue LED chip and a yellow phosphor. For example, Sony Corp proposed a backlight that emits light by using single-color LEDs of red, green and blue. But this backlight has an issue in that three different kinds of LED drive circuits are required.
The research results will be presented at the 55th Meeting of the Japan Society of Applied Physics, which runs from March 27, 2008, at Nihon University.
