With the rapid development of LED technology, the lighting effect of LED lamp belt in the atmosphere lamp has been unable to meet the needs of the modern market, and the COB lamp belt has gradually entered the public field of vision due to its advantages of high light uniformity, low junction temperature and large luminous Angle. In this paper, the stability, light uniformity, junction temperature and other performance of the two kinds of lamp belt under different color temperature and different power were analyzed by setting contrast experiment. It was found that LED lamp belt had uniform light and poor heat dissipation effect due to chip distribution characteristics, and it would accumulate a lot of heat and appear color shift phenomenon when continuously lit. The COB lamp belt can not only maximize the heat dissipation performance of the substrate, but also achieve more uniform light distribution by the way of multi-chip arrangement. The relationship between the thermal performance and chip spacing is analyzed by optimizing the design, which plays a guiding role in the actual production of the lamp belt
The quality of tea is relative with its concentration. In this paper, we present a method to identify the concentration of tea based on Tyndall effect. The tea is illuminated by 3-watt LED light sources with the main wavelength in ultraviolet and visible bands. The intensities of transmitted light are detected using the distributed photometer and the images of light distribution are captured by CCD camera at vertical direction to observe the Tyndall effect. The intensities and images for different light sources are compared. The experimental results show that there exist Tyndall phenomenon in tea. In addition, the Tyndall effect becomes weaker as the tea concentration increases when the tea is illuminated by the LED light sources with the main wavelength in the ultraviolet band. The method presented in this paper should be helpful for rapid identification of the tea quality
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