Research Of High Performance Solid White Light Source

Semiconductor lighting as a new generation of green lighting in 21 st Century, it has the advantages of energy saving, environmental protection, high stability, long life, has been widely used in indicator light, display, decoration, back light source,general lighting and other fields. With the improvement of life quality, people pursuit of light quality is not only the photoelectric conversion efficiency, in many applications, it requires not only the temperature of the light is adjustable, and have a high color rendering index. Light source has an important influence to person’s circadian regularity. and the color rendering index reflects the ability to restore the true color of the object.Light declining existed both LED and other light sourcing, what’s more, light declining have bad influence on the luminous flux and the color temperature of light source, especially on the use of high quality light source.LED light source is not applicable to any occasion, for example in the projection display,high brightness back light application, Laser Diode is more suitable because LD have a serial advantages of high brightness, low optical propagation, long service life and stable performance.In this paper, I study the tunable color temperature white LED Light Source with high color rendering index; LED light attenuation characteristics was studied, and puts forward a design scheme of the color temperature stability of the system for four-color mixed white LED light source; Study the high color rendering index laser white light source. The main work is as follows:1. Using the matlab program, design the tunable color temperature white LED Light Source with high color rendering index theory calculation simulation software interface,makes the calculation simulation procedures simple and clear, for tunable color temperature white LED Light Source with high color rendering index of the experimental study laid the foundation.In the experiment, the warm white light, which was obtained by blue LED die exciting green and orange phosphor, and red, green, blue LED light were mixed. Byrespectively controlling the duty ratio of the PWM signals, the drive currents and luminous flux of each LED can be adjusted. A mixed white light source with ultra-high color rendering index has been realized for the first time, whose color temperature can be tunable within the range 2700 k to 6500 k, Ra is between 95 to 98, all special CRIs(R1 to R15) are more than 90,and luminous efficiency of radiation(LER) is between 286 to 286 lm/W.The consistency of experimental measurements and theoretical simulation are very well.2. For the LED light attenuation problem, the experiment first study the effect of attenuation of single chip and PC type LED optical properties, which provide the experiment basis for the study of four-color mixed white LED color temperature stability; secondly the four-color mixed white light LED light source is studied, the red, green, blue three kinds of light source light attenuation effect on white light source color temperature, respectively, the study found that three red, green and blue light source the light failure on the influence of the mixed white light source color temperature is linear relationship; Finally, proposed a closed-loop control color temperature stabilization system based on TCS3414 color sensor.3. Firstly, studied the effect of powder-rubber ratio and the thickness of the phosphor excited fluorescence optical. Secondly, studied contrast of the photoelectric conversion efficiency of the green LED and blue LD excite green phosphor, and found that in large current, LD excite green phosphor is more efficient and better thermal stability. Finally, in the high color rendering index of the experimental study of the laser white light, by blue LD excite the green and red phosphor of light mixing, mixing light using a color wheel mixed light and direct light mixing.Among them, in the color wheel mixed light green and red powder-rubber ratio which are 1:3 and 1:5, respectively, because in this ratio they have highest efficient. By comparing the color wheel mixed and direct mixed of the experimental results, found that the color wheel mixed photoelectric conversion efficiency and general color rendering index is better than direct mixed, this is because when phosphor is direct mixed, secondary excitation phenomenon exist in phosphors.