What exactly is the relationship between the LED display gray scale and brightness
The grayscale of LED display can also be called LED display brightness. Gray scale level is also known as the middle tone (Half-tone), mainly used for transmitting pictures, respectively, there are 16 levels, 32 levels, 64 levels of three ways, it uses the matrix processing method to deal with the pixels of the document into 16, 32, 64 levels of hierarchy, so as to make the transmission of the picture more clear. Whether it is a single-color, two-color, three-color screen, to display images or animation are required to constitute the pixel of each LED electronic display light-emitting grayscale adjustment, the fine degree of its adjustment is what we usually call the gray level.
There are two ways to control the LED display grayscale: one is to change the flow of current, a pulse width modulation.1. Change the current flowing through the LED electronic display. General LED lamp allows continuous operation current in 20 mA or so, in addition to the red LED saturation phenomenon, the other LED grayscale is basically proportional to the current flowing through; another method is to use the human eye's visual inertia, pulse width modulation method to achieve grayscale control, that is, periodically change the width of the light pulse (i.e., duty cycle), as long as this repetition of the cycle of illumination is short enough (i.e., refresh frequency is sufficiently High enough), the human eye does not feel the light-emitting pixel in the jitter. Because pulse width modulation is more suitable for digital control, so in the universal use of microcomputer to provide LED display content today, almost all of the LED electronic display is to use pulse width modulation to control the gray level. LED electronic display control system usually consists of the main control box, scanning boards and display control device is composed of three major parts.
The main control box from the computer's display card to obtain a screen pixel color brightness data, and then redistributed to a number of scanning board, each scanning board is responsible for controlling a number of rows (columns) on the LED electronic display, and each row (columns) on the LED lamps on the display control signals are transmitted in a serial manner.
Currently there are two serial transmission of display control signals:
1. One is the scanning board centralized control of the pixel point gray scale, scanning board will come from the control box of the rows of pixel gray scale value decomposition (i.e., pulse width modulation), and then the rows of LED lamp beads to open the signal in the form of pulses (light up for 1, not light up for 0) by line with the serial transmission to the corresponding LED electronic display, to control whether it is lighted. This way to use less devices, but the amount of data transmitted serially is larger, because in a repeated light cycle, each pixel in 16 levels of grayscale needs 16 pulses, in 256 levels of grayscale needs 256 pulses, due to the device operating frequency limitations, the general can only make the LED electronic display screen to do 16 levels of grayscale.
2. One is pulse width modulation. Scanning board serial transmission is not the content of each LED switch signal but an 8-bit binary gray value. Each LED display has its own pulse width modulator to control the lighting time. In this way, in a repeated lighting cycle, each pixel point in 16 levels of gray only 4 pulses, 256 levels of gray only 8 pulses, greatly reducing the serial transmission frequency. With this method of decentralized control of LED electronic display gray scale can be easily realized 256 levels of gray scale control.
