KEYWORDS: Light emitting diodes, LED lighting, Light sources and illumination, Endoscopes, RGB color model, Luminescence, Radium, Near ultraviolet, Blue light emitting diodes, Mouth
We have for the first time developed warm white LEDs lighting using a combination of near ultraviolet LED and three-band (red,
green and blue) white phosphors. This LED has the average color-rendering index Ra=96. Moreover, special color-rendering index R9
(red) and R15 (face color of Japanese) are estimated to be 95 and 97, respectively. We will describe the results of evaluation on the
medical lighting applications such as operation, treatment and endoscope experiments, application to the LED fashions and application
to the Japanese antique art (ink painting) lighting.
The near-ultraviolet (nUV) white LED approach is analogous to three-color fluorescent lamp technology, which is based on the conversion of nUV radiation to visible light via the photoluminescence process in phosphor materials. The nUV light is not included in the white light generation from nUV-based white LED devices. This technology can thus provide a higher quality of white light than the blue and YAG method. A typical device demonstrates white luminescence with Tc=3,700 K, Ra > 93, K > 40 lm/W and chromaticity (x, y) = (0.39, 0.39), respectively. The orange, yellow, green and blue OYGB) or orange, yellow, red, green and blue (OYRGB) device shows a luminescence spectrum broader than of an RGB white LED and a better color rendering index. Such superior luminous characteristics could be useful for the application of several kinds of endoscope. We have shown the excellent pictures of digestive organs in a stomach of a dog due to the strong green component and high Ra.
KEYWORDS: Light emitting diodes, LED lighting, Lamps, Light sources and illumination, Solar cells, Sensors, Light sources, Light, Photovoltaics, Control systems
We describe the lighting characteristics and systems of the power energy-saving type street lamp which consists of white light-emitting diodes (LEDs), and a solar-cell and battery system. The prototype street lamp has been constructed by two LED light sources, each of which includes a total of 700 units of 10 cd-class white LEDs. The white LED lighting system is mainly divided into three components which are the control, the electric-power supply and LED lighting divisions. The illuminance is normally 80 lx. When a person approaches within 2 m near the lamp, the body sensor catches the situation. The illuminance then increases to about 660 lx, which is about 50 times brighter than that of a white incandescent lamp. The color rendering index is estimated to be 85 which is similar to that of three color fluorescent tube. The illuminance distribution can be analyzed by our recently developed 'multi sources of LED light' theory.
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