Mankind has entered the age of brightness since Thomas Edison invented carbon-filament incandescent lamp in 1879. When we look back on the history of lighting, new light sources emerged in an endless stream, for example, fluorescent lamp, mercury lamp, high/low-voltage sodium lamp, metal halide lamp, compact fluorescent lamp, high-frequency energy-saving fluorescent lamp, microwave lamp and so on. But since the day carbon filament incandescent lamp was invented, the flaws have never been neglected by people, such as: when tungsten filament is heated, it costs too much energy. It is very fragile for lamp bulb and very easy to get an electric shock. Fluorescent lamp consumes less energy than incandescent lamp, it is very bad for eyesight and the mercury in the tube is very bad for the human body and environment. LED is a product that brings the revolution of illumination technology. It transforms electrical power into visible light. Compared with traditional lighting technology, the biggest difference is its structure and material. It has upper electrode and lower electrode where the conductor material and luminous material are in between. Furthermore, the color of light would change according to different situations.
LED is one of the solid cold light sources. It is not only much smaller, lighter and firmer, but also has lower voltage and longer serving time. Though according to the traditional definition of light effect, it seems that the effect of LED is not so good. LED’s efficiency can reach 80%-90% in the visible light area, meanwhile, it is only 10%-20% for the incandescent lamp with the same light effect. Furthermore, one single LED’s consumption is usually from 0.05w to 1w. A group of LED could be made into different kinds of shapes to meet various requirements.
As a new green product, LED is the inevitable trend of future development. It will be the age of LED illumination for 21 century.