The advent of the blue LED, phosphor and using a combination of a blue LED, white LED can easily be obtained, which is one of the most mature industry white light package. At present, white LED has become an illumination source, and general household lighting has become a reality. At present, the traditional white light high-power product uses a blue light wafer to excite a single yellow phosphor, which has the disadvantage of poor color rendering; in order to improve color rendering, a red phosphor is usually added to the yellow phosphor to increase the red component in the spectrum, and the disadvantage is that Since the conversion efficiency of the red phosphor is low, the overall white light emission efficiency is lowered. Lehman Optoelectronics has been committed to the development of technologies that increase color rendering index, luminous efficiency and control color temperature.
I. Technology concept
In order to improve the color rendering of white light high-power products and achieve high overall luminous efficiency, we use a high-power blue light chip, a medium-power red light chip and a low-power yellow light chip integrated package and use phosphor The white light LED with high luminous flux and high color rendering is obtained by the excitation method. The package structure is as follows:
Figure 1 White LED package structure
As shown in Figure 1 above, a high-power blue light, a medium-power yellow light, and a low-power red light are respectively fixed on the horizontal high-power substrate. The three wafers respectively adopt three current loops, and then the surface is encapsulated with fluorescent glue, and the blue light wafer is excited by the fluorescent glue. The positive white light with a color temperature of about 6000K can realize the white color temperature adjustment by controlling the current of the yellow light wafer; the white light index can be adjusted by controlling the current of the red light wafer.
Second, the analysis of technical principles
The traditional white light spectrum consists of blue and yellow light spectrum, as shown in Figure 2:
figure 2
In order to improve the color rendering index of white light products, the current method of adding red phosphor in the yellow phosphor is generally used in the industry, and its spectrum is shown in Figure 3:
image 3
Since the red phosphor material is mostly nitride or silicate, its excitation efficiency tends to be low and its aging attenuation is large.
The red light wafer is used to enhance the index. The red light itself has no effect on the yellow phosphor and does not involve the excitation efficiency problem. Therefore, the significant increase of the index can be achieved and the luminous efficiency and aging attenuation of the product are not lost. 4 shows:
Figure 4
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