Semiconductor Lighting Laboratory, Shenzhen Graduate School, Tsinghua University, Shenzhen 518055, China)
State Key Laboratory of Integrated Optoelectronics, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China)
Dongguan Qinshang Semiconductor Lighting Technology Research Institute
Abstract: Since white LEDs have many significant advantages, there are many advantages to applying them to alternative lighting sources in public urban lighting facilities. However, in order to truly give full play to the advantages of semiconductor light sources, the design of secondary optical systems is crucial. This paper introduces a unique secondary optical system for urban road lighting. It can better meet the relevant standards of urban road lighting, and can be flexibly applied to different road conditions.
Keywords: semiconductor lighting; power LED; secondary optical design
1 Introduction <br> Public city lighting has a large share in the lighting market. According to statistics, urban public lighting accounts for 30% of China's lighting power consumption, about 43.9 billion kwh, calculated at an average electricity price of 0.65 yuan/kwh. The annual expenditure is 28.5 billion yuan. At present, high-pressure sodium lamps are widely used in urban public lighting, especially on main roads, and high-pressure sodium lamps can provide luminous efficiency of more than 100 lm/W. But its own shortcomings are also obvious:
The spectral composition of the light source is yellowish and the color rendering index is extremely low;
The life of the luminaire is short and the replacement work is large;
Inconvenient to adjust the power of the lamp;
With the rapid development of solid state physics in the 1990s and the breakthrough discovery of new semiconductor materials, LED technology has made rapid progress in the past 10 years. The appearance of white LEDs is characterized by its unique low voltage drive, small size, light weight, good color rendering, good dimming performance, long life (up to 20,000 hours), vibration resistance, damage resistance, and environmental protection requirements. So that the semiconductor light source will become an ideal energy-saving light source for urban road lighting. Its remarkable advantages are: high luminous efficiency.
At present, the commercial white LED light efficiency has reached 90-100lm/W, and it is expected to reach 150lm/W or more in 2 years. This is not the upper limit of LED light efficiency. Experts from all countries have set the goal of light efficiency at 200lm/W. about.
long life.
The ideal goal is 100,000 hours, and the current commercial white LED life can reach 50,000 hours, which is 10 to 20 times longer than the traditional light source. When the city road lighting source is made, the light source can be replaced for 10 years, which greatly saves daily maintenance costs. It is convenient to adjust the power of the lamp intelligently; the secondary optical system can be added to make maximum use of the light energy of the LED to meet the specific illumination and light intensity distribution of various applications. In recent years, conventional fossil fuels have become increasingly tense. The prices of conventional energy such as oil and coal have been rising, and the international oil prices have reached historical highs, causing the situation of energy supply to become more severe. Due to these significant advantages of LED and the maturity of white LED technology, it is of great significance to develop an efficient, long-life, green and environmentally friendly semiconductor light source urban road lighting system.