Tokyo, Japan--A white-light LED spotlight introduced in Japan this week by Ushio achieves a color-rendering index as high as 97 (100 is perfect) by combining violet-emitting LED chips with red, green, and blue phosphors. This is in contrast to the industry-conventional combination of a blue LED chip and yellow phosphor, which many complain produces a low-quality white light.
The Ushio spotlight is designed to directly replace tungsten-halogen spotlights, and thus has a warm-white cast; it is termed a "Natural Light LED." (The Natural Light LED was actually developed by CCS of Kyoto, Japan.) The spotlight's color temperature is 4,000K; Ushio will soon introduce a model with color temperature of 5,000K. For the same brightness as a tungsten-halogen lamp, the Ushio device uses 1/9 the power and lasts ten times as long (a rated life of 20,000 hours).
Range of color tests
One way of testing the color quality of a white-light LED is to see how well it renders the color of various standardized color swatches, termed R1 to R15. (For example, R1 is "light grayish red," while R4 is "moderate yellowish green.") Many manufacturers use only R1 to R8 as a test, but Ushio used the whole range, up to R15, for testing. The spotlight should render colors as if objects are lit by afternoon sun.
Source: Tech-On
