For white LEDs to be used for general lighting, they should have appropriate white color and good color rendering performance for illuminated objects. Color rendering, as well as energy efficiency (efficacy), have been the two most important criteria for traditional light sources for general lighting. Color rendering is determined solely from the spectrum of the source. Thus, the spectra of white LEDs need to be designed to meet requirements in both aspects. An advantage of LEDs is that they are available in almost any wavelength in the visible region, and the spectrum design of white LEDs may be more flexible than for traditional discharge lamps where the available spectra depend on available phosphors and emissions from gas. The evaluation method for color rendering of light sources is well established by the CIE (Commission Internationale de I'eclarage = International Commission on Illumination), and the color rendering index is widely used in lighting industry for many years. The white LED spectra can be optimized using this index as well as for the source efficacy. In this section, some fundamentals of the CIE colorimetry system including the color rendering index is described, and some designs of white LEDs (three-chip type) are demonstrated.
Solid State Light Emitting Diodes for General Illumination
October 26-27, 2000
Optoelectronics Industry Development Association. Report
color, color rendering, colorimetry, efficacy, LED, luminous efficacy, white LED
Color Issues of White LEDs, Solid State Light Emitting Diodes for General Illumination
(Accessed June 1, 2023)