Rewind the clock 30 years to 1993, red, orange, and yellow-green LEDs were readily mass produced and available in the market. However, although blue LEDs utilizing different substrate materials were available in the market, production quantities were very limited. In fact, these blue LEDs were not as bright as the red and yellow-green LEDs. Therefore, because of the brightness difference between these 3 colors, balance could not be achieved between the three primary colors (red, blue, yellow) necessary to reproduce any color, including white. Various manufacturers and resear…