LED display brightness control are two methods commonly ：


     There are two control LED brightness method. One is to change the current flowing through the LED, the general LED tube to allow continuous current of 20 mA or so, in addition to the red LED saturation phenomenon, the other LED brightness is basically proportional to the current flowing through; Another way is to use human visual inertia with a pulse-width modulation method to achieve gray-scale control, which is cyclical changes in pulse width (ie duty cycle), as long as the repeated cycle of light short enough (ie, refresh rate is high enough), human eye is not feel light-emitting pixels in the jitter. As the pulse-width modulation is more suitable for digital control, so widely used to provide the LED display computer today, almost all of the LED screens are based on pulse-width modulation to control the gray level.

LED control system is usually the master box, scan board and display control device has three major components. Master box from the computer's graphics card to get a colored screen pixel brightness data, and then re-allocated to a number of blocks of scan plates, each scan LED screen on the board responsible for controlling a number of rows (columns), and each row (column) on the LED display control signal is used for serial transmission. There are two kinds of display control signals in a serial transmission method: one is scanned on-board central control point of each pixel grayscale, scanning panels will come from the control box of each line of pixel brightness value decomposition (ie, pulse-width modulation), and then the opening of the line of LED signal to pulse form (light of one, does not shine as 0) by line of serial transmitted to the appropriate LED on the control of whether they light up. Devices used in this way less, but the large amount of serial transmission of data, because in a repeating cycle of light, each pixel in the 16-level gray-scale required under 16 pulses required under the 256 level gray-scale 256 pulses, due to the device operating frequency restrictions, the general can only do 16-level grayscale LED screen.

Another method is to scan the contents of the plate serial transmission is not a switch signal for each LED but the brightness of an 8-bit binary value. Each LED has its own pulse width modulator to control the light time. Thus, in a repeating cycle of light, each pixel point in the 16-level gray-scale require only four pulses, 256 level gray-scale only eight the next pulse, greatly reduced the frequency of serial transmission. LED gray in this decentralized control approach can easily achieve the 256-level grayscale control