Improve LED color rendering

At present, white LEDs generally use blue LEDs and yellow yttrium aluminum garnet (YAG) phosphors excited by blue light to synthesize white light. Because its luminescence spectrum only contains blue and yellow spectra, it has the problems of high color temperature and low color rendering index, which does not meet the requirements of ordinary lighting. The sensitivity of human eyes to color difference is much higher than that to light intensity. For illumination, the color rendering of the light source is often more important than luminous efficiency. Therefore, adding an appropriate amount of red phosphor and maintaining high luminous efficiency is an important topic in LED white lighting.