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.
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