After years of research and trial LED display experts claimed: LED display brightness control, there are two main methods, a method is the use of the human eye's visual inertia, pulse width modulation method used to achieve gray-scale control, and now almost all The LED displays are used in pulse width modulation to control the levels of gray, and the other is by changing the current flowing through LED. Now widely used because of the computer screen content provided by pulse width modulation method to achieve gray-scale control methods used by most manufacturers, the cyclical changes in optical pulse width (ie duty cycle), as long as the light of the repeated cycle of short enough (that is, a sufficiently high refresh rate), the human eye is less than a luminous sense of pixel in the jitter. And by changing the LED current flows through the LED display brightness to change the method, the general LED tube to allow continuous current at about 20 MAs, in addition to the phenomenon of red LED are saturated, the other LED brightness and the flow is basically proportional to the current , method is simple but not easy to control, it is not very widely used!！