Application of high power white LED in lighting field

For power white LED light source, light emitting efficiency, single light flux, high reliability, color Gao Xian and cost determines its competitiveness in the lighting market. How can be prepared with high luminous efficiency, high color white LED color, is a prerequisite for widespread use in general illumination in LED, the preparation of white LED methods can be divided into three types: red, green and blue (RGB) white light blue chip and multi chip combination, fluorescent powder the synthesis of white light, white light MOCVA direct growth of multi active regions.

Several technical comparison, in addition to white light LED technology is at the stage of research and exploration of the growth of MOVCA multi area outside. Although the RGB LED has the advantages of high luminous efficiency and good color rendering, the performance of the three kinds of chips is different, which results in the color drift due to the influence of the driving current or temperature. Because of the application of blue chip and phosphor in the field of lighting, how to improve the luminous efficiency and color rendering index is the focus of this paper. LED.

Preparation and, improve the luminous efficiency of phosphor with selection is the key

Light source luminous efficiency is to convert energy consumption for visual ability. The main ways to improve the luminous efficiency of the general power white LED are: 1> improve the luminous efficiency of the chip. 2> effectively extracts the light from the wafer. 3> will be extracted out of the optical LED tube in vitro. 4> will be low LED thermal resistance. 5> enhances the excitation efficiency of phosphor. After a lot of experiments, it is proved that under the condition of the same packaging conditions, the flux of fluorescent powder has the difference of 10%--20%. Here we first understand the fluorescent powder, luminous principle, and then discuss the selection and preparation of phosphors.

, 1 fluorescent powder from the main lattice (hostlattice 'H) and the activation center (activator' coA), sometimes there are auxiliary activators or sensitizer. The main lattice: the role of energy transfer during excitation. For example: Y3AI5O12:Ce3+ in Y3AI5O12. Activation center: Ce3+ can be activated in the main lattice such as: Y3AI5O12:Ce3+.

The principle of light emitting phosphor: power GaN based blue chip as the pump source to excite the phosphor, the excited electrons in the form of direct light back to the electronic ground state.

Reasonable choice of phosphor particle size and density, regular shape, brightness, excitation wavelength of LED luminous efficiency and color has great influence; relationship between light efficiency and wavelength is only two wavelength compound into white light under the condition of 450nm and 580nm can obtain the most efficient. Select the three wavelength wavelength of 450nm, 540nm and 610nm when the highest efficiency of large particles, the luminous efficiency will be good shading, rapid sedimentation, not easy to package; good luminous efficiency is still moderate particles will sink, easy package; nano particles are not easy to settlement, easy package, but low luminous efficiency.

Control, two white LED light color in the lighting

Color is the degree of light source is the true color objects of the. The light of the sun and the halogen lamp are continuous spectrum, in the visible light wavelength (380-780nm) range, including red, orange, yellow, green, green, blue, purple and other color and color rendering index was set at Ra100.

Daylight as a standard light source, compared with the above several kinds of artificial light: halogen lamps have a continuous spectrum, showing color is relatively good, the rest of the two kinds of light of the continuous spectrum is not good, the energy distribution is not balanced poor color rendering. In order to improve the color rendering of the white light source synthesized by the blue light excitation phosphor sent by the LED, the spectrum of the white light source must be adjusted so that it can be continuous and balanced in the visible light. To improve the color rendering method we through lots of experiments for several 6500K color temperature, color rendering index >80 to do, need to choose the appropriate fluorescent powder and excitation wavelength; in blue LED luminescence excitation YAG phosphors emit yellow green light on + red phosphor in the red spectrum in the original lack of compensation,. Color can improve the light sources; preferably YAG fluorescent powder, complementary source spectrum with the emission spectra of different phosphors, color can also improve this kind of light source.

Summary

LED occupies a space for one person in the field of lighting, which has unique advantages in the decorative lighting and focus lighting, atmosphere etc.. In the future application, we should grasp the advantages of LED, reasonable application of LED, and further explore the application of LED in general lighting by further study of key technologies. As far as the visual function is concerned, the luminous flux, luminous efficiency and color rendering of LED need to be further improved. To this end, Lehman photoelectric is willing to work with peers, LED scientific research units to make the LED light source suitable for habitat health, comfortable light environment to make a positive role.