The Design Method Of Secondary Light Distribution For LED Lighting System

As following increasing requirements of lighting qualities and energy savings for the most common people, semi-conductor light source, as the fourth generation electric light source, has attracted widespread attentions because of its advantages, such as high luminous efficiency, long life-span, energy saving, tunable color temperature and environmental protection. However, it exhibits different illuminant characteristics and illuminant patterns with other solid lighting sources, and cannot be directly applied to existing conventional lighting systems. Therefore, we need to design light distribution on LED light sources and reconstruct lighting systems which can effectively modulated the light distribution curve of LED to meet the demands of all kinds of lighting applications. Light distribution design on LED play an important role on its popularity in the lighting field and providing high lighting quality.. In consideration of the imaging theory and the freedom-surface design principle, we discuss and perform the research on the light distribution design for LED used in lighting systems. In the light distribution design of optical systems, the free surface has a strong ability to control large light angle and distribute light intensity simultaneously, which improves the flexibility of space layout and simplify the structure of lamps, and increase the quality of lightings. It is very suitable for light distribution design based on LED lighting systems. This research has both theoretical values and a certain practical significances. In this work, we carry on the secondary light distribution designs and simulations for the reflectors of automotive headlight lamps requiring a special light distribution and lens of desk lamps requiring uniform illuminations, respectively.In this paper, we first discuss the evolution and development of electric light sources and the application of the LED light source in the daily lighting, elucidating the importance of light distribution in lighting systems. Then, the related photometric parameters of LED light source and several mainstream light distribution patterns for lighting systems based on LED are provided. We also introduce the computer programming, the modelings and simulation-analysis software used in this paper.Then, we introduce developments and contents of non-imaging optics theory and expound designing thoughts of the light distributions for LED lighting systems based on freedom-surface theory. At the same time, according to the freedom-surface principle, we design freedom-surface reflectors of automotive lamps and lens of desk lamps. Furthermore, exploratory studies on the method of uniform illumination based on the freedom-surface design by solving differential equations are carried on. With the aid of the computer software, we are able to conduct simulations and varifications and obtain expected results.Finally, we summarize the main research issues of this project and provide improvement opinions on the exposed problems along with the next work. Future research trend of the LED used in lighting systems are briefly described in the end.