Brightness Adjusting for LED Changing Message Sign

Because the changing range of environmental brightness is wide, brightness of LED CMS(Changing Message Sign) should be adjusted according to the changes of environmental brightness in order to guarantee that the displayed information could be clear under different lumina. This paper will discuss brightness adjusting design for LED CMS from three different angles: visual characteristics of eyes, the relationship between luminescence brightness and environmental brightness and the ways of brightness adjusting, and give final testing results.