Lighting use LED products have to solve technical problems

8 Jun

Lighting in need of W white led strip products to power level realized industrialization, must solve technical problems are as follows:
(1) powder coating quantity control. LED chip + phosphor processing adopts the glue method, usually is mixed with glue and phosphor after the distributor on the chip. In the operating process, because of the carrier adhesive viscosity is dynamic parameters, greater than the carrier and the proportion of phosphor glue to produce precipitation and distributor precision the influence of factors, the process of phosphor coating quantity uniformity of the control has difficulty, led to the inhomogeneity of the white light color.
(2) chip photoelectric parameters between cooperation. The characteristics of the semiconductor technology, decided the same materials the same wafer chips may exist between optical parameters (such as the wavelength, the light intensity) and electrical parameters (such as the forward voltage) of the differences. RGB three colors chips are this, for the white light chromaticity parameters influence. This is the key to solve the industrialization must be one of the technologies.
(3) Color light controls parameters. Different USES of products, the color white Flexible LED Strip Lights to coordinate, color temperature, color rendering, light power (or light intensity) of light and space distribution and so different demand. The control of the above parameters involved in product structure and technology methods, materials and so on various factors. In the industrialized production, to the above factors control, application for compliance with requirements and the sex good product is very important.
White LED the purpose of the research is to achieve high efficiency, high power, the long life devices. The technical problems are: to lower the defect density, and improve the ohm contact and electric field uniformity and increase the rate, reduce the temperature rise out, etc. In the study of the major measures taken are: the lateral growth, matching substrates, packaging technology improvement, etc.
At present, in the substrate, chip technology and white LED chip extension of the device in such aspects as production technology has made great progress. In the sapphire, because it does not match the substrate, so take a lateral extension technology, and to make performance made bigger improvement. At present the research progress of chip result is:
(1) the substrate based on sapphire blue, green, violet and uv LED for best performance at present is to take lateral growth in technology based on made, purpose is to reduce the dislocation density, blue, violet device outside of quantum efficiency is about 40%, but the green, uv device is about 15%, respectively from the target is two to six times. Based on the chip in the white light of the improved performance depends on the phosphor and packaging technology improvement.
(2) in the silicon carbide because the device has more small dislocation density, based on the substrate of each color LED performance is still better than sapphire substrates of lateral growth LED performance, but because the substrate is your 7 to 10 times Sapphire, the performance optimization research work for relatively less.
(3) respectively with silicon carbide and alumina and GaN and sapphire as substrate do during the light contrast experiment shows that their ultraviolet light characteristics, the difference between the order of magnitude, with that of the substrate based on low defect density LED may get the best luminous property (including lumens efficiency and single pipe to generate data).
To realize efficient white LED lighting system of practical, semiconductor lighting the main contents include:
(1) study to use UV-LED AIN, GaN etc of the center for the semiconductor compound emitting mechanism.
(2) to improve blue, UV-LED the extension of growth technique.
(3) are the development of homogeneous extension board.
(4) the development of efficient RGB phosphors white high density led system and practical.
White LED lighting goal is the development direction of: in lighting colour temperature area, realize the specular highlights, high photosynthetic efficiency, high show color index and low cost and the uniform color white LED. In recent years, the industry began to adopt a large number of white LED alternative CCFL LCD back lighting and EL as the (background lighting abbreviation). Compared with CCFL, EL, white LED has the following advantages:
(1) can make more vivid color LCD, with white light of LED back lighting NTSC levels reached 130%, and CCFL is only 70%
(2) are the expansion of the levels that the LCD image more saturated, more vivid color; Can make the LCD thinner thickness, in 18 inches (1 inch = 2.54cm) LCD modules, white LED back lighting thickness for four to nm. CCFL is 8-l2mm.
(3) life is long, can reach 50000 h.
(4) The accord with environmental protection requirement, white LED contains no mercury.
(3) compared with EL lighting. White LED back lighting won’t produce interference.
Lighting source a basic requirement, is to adapt to the eyes of the people need, and the eyes of characteristics to match demand. Now there are two ways: one is through the blackbody radiation, 2 it is through the different colored light synthesis.
According to the principle of incandescent lamp made blackbody radiation, because the color temperature can’t too high, most of the energy into the infrared radiation, and make the luminous efficiency is reduced, different colored light synthesis BaiGuangYou different synthesis method, can be two, three or more kinds of colored light synthesis white light, the color kind of use, and it is the pixel high, but lower lumen efficiency, this and for the synthesis of white light the quality requirements of the relevant. Generally speaking, with RGB three colored light synthesis BaiGuangKe at the same time satisfy the luminous efficiency, show color index, color temperature requirements, etc. The theoretical analysis shows that if the color temperature for 6500 K, show color index greater than 90, only when the three colors respectively for 455 nm wavelength, 530 nm and 610 nm, white light lumens of synthesis of the highest efficiency, can reach 300 lm/W.

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