1. Visible light spectrum and the relationship between the white LED. The weeks of public, visible spectrum wavelength range of 380nm ~ 760nm, is the human eye can be felt by seven-color light - red, orange, yellow, green, green, blue, purple, but that seven kinds of colors of light are each a of a monochromatic light. For example, hair red LED peak wavelength of 565nm. In the visible light spectrum is not white light, because white 10 Inch electronic photo frame light is not monochromatic, but rather a compound synthesized by a variety of monochromatic light, monochromatic light as the sun alone from seven kinds of synthetic white light, while the color TV in the white Light is also from the three primary colors yellow, green, blue synthesis. Thus, to make white light LED, and its spectral characteristics should include the entire visible spectrum. But to create this kind of performance of LED, in the present process conditions is impossible. According to one study of visible light, human eyes can see the white, take at least two kinds of optical mixing, namely, two-wavelength light (blue light + yellow light) or a three-wavelength light (blue light + green light + red light) model . These two modes of white light, we need a blue light, so the intake of white blue light has become a key technology manufacturers that the current major LED manufacturing company pursuing the "Blu-ray technology." The current international control of the "Blu-ray technology" only a few vendors, so the promotion of white LED applications, particularly in high-brightness white LED in China to promote there is a process.
2. Process structure of white LED and white light sources. For general lighting, in the process structure, the white LED are two methods commonly used form, the first is the use of "Blu-ray technology" with the formation of white phosphor; the second is a variety of monochromatic light hybrid approach. Both methods have been successfully produce white light devices. The first method produces white light system shown in Figure 1, the figure LEDGaM chip to emit blue light (?p = 465nm), it YAG (yttrium aluminum garnet) phosphor package together, when the phosphor after excitation by blue light yellow light, resulting in the formation of white blue and yellow mixed (constituting the structure of LED as shown in Figure 2). The second method uses a different shade of the chip package together, through a mixture of colored light to produce white.
3. The new white LED illumination light source application. In order to illustrate the characteristics of white LED, first take a look at the lighting currently used light source conditions. Incandescent and halogen, the optical efficiency of 12 ~ 24 lm / W; fluorescent and HID lamps light efficiency of 50 ~ 120 lumens / watt. Pairs of white LED: In 1998, white LED light efficiency is only 5 lumens / W, by 1999 had reached 15 lm / W, this indicator with the general household incandescent similar, and in 2000, the white LED light effect has reached 25 lm / W, similar to the indicators and halogen. Companies have predicted that by 2005, LED light 12.1 Inch lcd frame efficiency up to 50 lm / W, 2015, when, LED light efficiency is expected to reach 150 ~ 200 lumens / watt. At that time the work of white LED current can be Daan Pei-level. This shows that development of a writer with white LED light source, will become possible reality.
General lighting incandescent and halogen Although inexpensive, but the luminous efficiency is low (thermal effect of light power in vain), and short life span, maintenance workload, but with the white LED for illumination, not only the high luminous efficiency, and life expectancy long (more than 10,000 hours continuous working time), almost no maintenance. At present, the German company Hella has developed the use of white LED reading light aircraft; Australian capital Canberra, has been a street lamp with a white LED for lighting; China's Urban Traffic Management white LED lights are also used to replace the earlier order in light traffic. Can be expected in the near future, white LED will enter the home to replace the existing lighting.
LED light source with the use of low-voltage power supply, consuming less applicability, high stability, response time is short, environmental pollution, such as the advantages of multi-color 7 Inch digital frame light-emitting, although more expensive than the existing lighting equipment expensive, is still considered that it will Inevitably, existing lighting devices.