led screen gray level can also be called led display brightness. gray level, also known as half-tone, is mainly used to transmit pictures. there are 16, 32 and 64 levels respectively. it uses matrix processing to process the led modules pixels of files into 16, 32 and 64 levels to make the transmitted pictures clearer. whether it is monochrome, bichrome or trichrome screen, to display images or animation, it is necessary to adjust the gray level of each led light-emitting pixel. the degree of fine adjustment is what we usually call gray level.
there are two methods to control the gray level of led: one is to change the current flowing through, the other is pulse width modulation. 1. change the current flowing through the led. generally, the continuous working current of the led tube is about 20 ma. except for the saturation of the red led, the gray level of other leds is basically proportional to the current flowing through it. another method is to use the visual inertia of the human eye and realize the gray level control by pulse width modulation, that is, to periodically change the pulse width (i.e. duty cycle), as long as the red led is saturated. this cycle of repeated lighting is short enough (i.e., the refresh frequency is high enough) that the human eye does not feel the fluorescent pixels shaking. because pulse width modulation is more suitable for digital control, almost all led screens use pulse width modulation to control the gray level today, which is widely used to provide led display content. the control system of led is usually composed of three parts: the main control box, the scanning board and the display and control device.
the main control box obtains the brightness data of each color of a screen pixel from the display card of the computer, and then redistributes it to several scanning boards. each scanning board is responsible for controlling several rows (columns) on the led screen, and the display signal of the led on each row (columns) is transmitted in a serial way.