The hottest global glass network recommends six ke

Global glass recommends six key technologies of LED display screen

since the 1980s, various media publicity has been widely developed, and the number of exposed information displays in public places is increasing. People have higher and higher requirements for the color and brightness of the display system. Secondly, some display systems set up outdoors have been affected by the natural environment for a long time, which is a test for their service life. The LED electronic display screen has good pixels. No matter day or night, sunny or rainy days, the LED display screen can let the audience see the display content and meet people's needs for the display system

1. Image acquisition technology

the principle of LED electronic display screen displaying images is mainly to convert digital signals into image signals and present them through the light-emitting system. The traditional method is to use video capture card and VGA card to realize the display function. The function of the video capture card is mainly to collect video and assist in buying and selling frequency images through the online platform, and obtain the index addresses of line frequency, field frequency and pixel points with the help of VGA. The way to obtain digital signals is mainly by copying the color lookup table. Generally, software can be used for real-time replication or hardware theft, which is more efficient than hardware theft. However, the traditional method has the compatibility problem with VGA, which leads to edge blur, poor image quality and other adverse conditions, and finally causes the image quality of electronic display to be damaged

based on this, industry experts have developed a special video card jmc-led. The principle of this card is to use a 64 bit graphics accelerator based on PCI bus to promote the integration of VGA and video functions, and realize the superposition effect of video data and VGA data. The previous compatibility problems have been effectively solved. Secondly, the full screen mode is adopted in the resolution acquisition to ensure the optimization of the full angle of the video image, the edge part is no longer blurred, and the image can be arbitrarily scaled and moved to meet different playback requirements. Finally, it can realize the effective separation of red, green and blue, and meet the requirements of true color playback of electronic display screen

2. Color reproduction of real image

led full-color display screen is similar to TV in visual performance principle. Through the effective combination of red, green and blue colors, different colors of the image can be restored and reproduced. The purity of red, green and blue will directly affect the reproduction of image color. It should be noted that the image reproduction is not a random combination of red, green and blue, but requires a certain premise

firstly, the ratio of light intensity of red, green and blue should be close to 3:6:1; Secondly, compared with the other two colors, people will be visually sensitive to red, so red needs to be evenly distributed in the display space; Third, because people's vision responds to the different nonlinear curves of the light intensities of red, green and blue, it is necessary to correct the light emitted from the TV by white light with different light intensities. Fourth, different people have different color resolution abilities under different circumstances, so we must find out the objective indicators of color reproduction, which are generally as follows:

(1) the wavelengths of the three primary colors of red, green and blue: 660nm, 525nm,

(2) it is better to use a four tube unit with white light (more than four tubes can also be used, mainly depending on the light intensity

(3) the grayscale of the three primary colors is 256 levels

(4) LED pixels must be processed by nonlinear correction

the light distribution control system of three colors of red, green and blue can be realized by hardware system or corresponding playback system software

3. Special reality drive circuit

classifies several ways of current pixel tubes, mainly including: (1) scanning drive; (2) DC drive; (3) Constant current source drive. Different scanning methods are adopted for different screens. For the indoor dot matrix block screen, the scanning mode is mainly used. For the outdoor pixel tube screen, in order to ensure the stability and clarity of its image, the DC drive mode must be used to add a constant current to the scanning device

in the early stage, led mainly used the low-voltage signal serial parallel conversion mode, which has many shortcomings, such as many solder joints, high production cost, insufficient reliability and so on. These shortcomings have limited the development of LED electronic display in a certain period of time. In order to solve the above shortcomings of LED electronic display screen, a company in the United States developed a special integrated circuit, referred to as ASIC. This kind of integrated circuit can realize series parallel conversion and current drive. This integrated circuit has the following characteristics: the parallel output driving ability is large, the driving current is as high as 200mA, and the LED can be driven immediately on this basis; The tolerance of current and voltage is large, and the range is wide. Generally, it can be flexibly selected between V; The series parallel output current is large, and the current inflow and output are greater than 4mA; The data processing speed is faster, which is suitable for the realization of the current multi gray color LED display driving function

4. Brightness control d/t conversion technology

led electronic display screen is composed of many independently formed small shrinkage pixels through arrangement and combination. Based on the feature that pixels are separated from each other, the LED electronic display screen luminous control driving mode can only be carried out in the form of digital signals. When a pixel emits light, its light-emitting state is mainly controlled by the controller and driven independently. When the video needs to be presented in a color way, it means that the brightness and color of each pixel need to be effectively controlled, and it is required to complete the scanning operation synchronously within the specified time

some large LED electronic displays are composed of tens of thousands of pixels, which greatly increases the complexity in the process of color control, so higher requirements are put forward for data transmission. It is unrealistic to set d/a for each pixel in the actual control process, so we must find a scheme that can effectively control the complex pixel system

based on the analysis of the visual principle, the average brightness of a pixel depends mainly on its light/off ratio. For this point, if the light/off ratio is effectively adjusted first, the brightness can be effectively controlled. Applying this principle to LED electronic display screen means transforming digital signals into time signals, that is, the mutual conversion between d/a

5. Data reconstruction and storage technology

there are two main ways to organize the current memory group, one is the combined pixel method, that is, all pixel points on the screen are stored in a single memory, and the other is the bit plane method, that is, all pixel points on the screen are stored in different memory. The direct function of multiple uses of storage is to realize the reading of multiple pixel information at one time. See the following two organization methods. The median plane method of the above two storage structures has more advantages, and the effect is better when improving the display effect of LED screen. Through the data reconstruction circuit to realize the conversion of RGB data, the same weight bits with different pixels are organically combined and placed in the adjacent storage structure

6. ISP Technology in logic circuit design

the control circuit of traditional LED electronic display screen is mainly designed by conventional digital circuit, and its control is generally controlled by digital circuit combination. After the completion of the circuit design, the traditional technology first carries out the circuit board manufacturing process, and then starts to install relevant components and debug the effect. When the logic function of the circuit board cannot meet the actual demand, it needs to be remade until it meets the use effect. It can be seen that the traditional design method and the skin process we use on the substrate are also becoming more and more complex, which not only has a certain contingency in the effect, but also has a long design cycle, which affects the effective deployment of various processes. When components fail, it is difficult to maintain and the cost is high. Since the 1980s, various media publicity has been widely developed, and the number of information displays exposed in public places is increasing. People have higher and higher requirements for the color and brightness of the display system. Secondly, some display systems set up outdoors have been affected by the natural environment for a long time, which is a test for their service life. The LED electronic display screen has good pixels. No matter day or night, sunny or rainy days, the LED display screen can let the audience see the display content and meet people's needs for the display system

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