The purpose of led tunnel light fixtures is to ensure that the vehicle is comfortable and safe to cross the tunnel, so the basic requirement of the road tunnel illumination is to provide the suitable illumination according to the external environment to satisfy the human eye adaptation curve.
The International Lighting Society (CIE) defines tunnel illumination as a close segment, the entrance section, the middle section, the exit section four illumination sections, in which the tunnel entrance illumination divides into the threshold section, the Transition section, the Threshold section is in order to eliminate “the black hole” the phenomenon, lets the driver be able to identify the obstacle in the hole (standard high 20cm).
In order to avoid the strong change between the threshold section illumination and the tunnel interior illumination, the illumination of the transition section is set up, and the level of lighting in the tunnel is decreased gradually to achieve the basic illumination brightness in the tunnel.
The lighting dimming control of led tunnel light is to meet the illumination demand of different brightness environment and traffic environment, and realize the smooth transition of illumination brightness in every section of the tunnel, so as to meet the requirement of illumination brightness of tunnel, ensure driving safety and save energy.
At present, the use of lamps in highway tunnels mainly include: fluorescent lamps, high-pressure sodium lamps, metal halide lamps, LED lamps and so on. Fluorescent lamps enable stepless dimming, but its light efficiency is low, the dimming is easy to produce high harmonics, the power grid caused interference; high-pressure sodium lamp, metal halide lamps dimming amplitude is very small, generally not in the stepless dimming system application; With the development of science and technology, LED lights began to enter the field of LED tunnel lights, The emergence of a tunnel illumination system using LED light stepless dimming control has made the road tunnel lighting quality and energy saving a big step forward. This paper aims to study the problems and solutions of LED light stepless dimming control system.