A Brief Discussion on Six Key Technologies of Full Color LED Display Screen Manufacturers
A Brief Discussion on Six Key Technologies of Full Color LED Display Screen Manufacturers
LED electronic display screens can enable viewers to see the displayed content clearly, regardless of day, night, sunny or rainy days, meeting people's needs for display systems. A good LED display screen requires excellent performance in both design and performance. How to choose a suitable LED display screen requires understanding and considering the following six key technologies:
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 luminous system. The traditional approach is to use a video capture card combined with a VGA card to achieve display functionality. The main function of a video capture card is to capture video images and obtain the index addresses of line frequency, field frequency, and pixel points using VGA. The main way to obtain digital signals is by copying color lookup tables. Generally, software can be used for real-time replication or hardware theft, which is more effective. However, traditional methods have compatibility issues with VGA, resulting in poor image quality and blurry edges, ultimately resulting in damage to the image quality of electronic displays.
Based on this, the industry has developed a dedicated video card JMC-LED. The principle of this card is to use a 64 bit graphics accelerator based on the PCI bus to promote the integration of VGA and video functions, and to achieve a superposition effect between video data and VGA data. The compatibility issues that previously existed have been effectively resolved. Secondly, in terms of resolution acquisition, a full screen approach is adopted to ensure full angle optimization of the video image, no longer blurring the edges, and the image can be arbitrarily scaled and moved to meet different playback requirements. It can effectively separate the three colors of red, green, and blue, meeting the requirements for true color playback on electronic displays.
2. Realistic image color reproduction
The principle of full color LED electronic display screens in visual performance is similar to that of televisions, which effectively combine red, green, and blue colors to achieve different color reproduction of images. The purity of the three colors, red, green, and blue, directly affects the reproduction of image colors. It should be noted that image reproduction is not a random combination of red, green, and blue colors, but requires certain prerequisites.
Firstly, the ratio of light intensity between red, green, and blue colors should be close to 3:6:1; Secondly, compared to the other two colors, people have a certain degree of visual sensitivity to red, so it is necessary to evenly distribute red in the display space; Thirdly, due to the different nonlinear curve responses of people's vision to the light intensities of red, green, and blue colors, it is necessary to correct the white light with different intensities for the light emitted inside the television. The fourth is that different individuals have differences in their ability to distinguish colors under different circumstances, so it is necessary to identify objective indicators for color reproduction, generally as follows:
(1) The wavelengths of the three primary colors of red, green, and blue: 660nm, 525nm, and 470nm;
(2) It is better to use a 4-tube unit with white light (more than 4 tubes are also acceptable, mainly depending on the light intensity);
(3) The grayscale of the three primary colors is 256 levels;
(4) Nonlinear correction must be used to process LED pixels.
The light distribution control system for the three colors of red, green, and blue can be implemented by hardware systems or matched with corresponding playback system software.
3. Dedicated Reality Driver Circuit
The main methods for classifying current pixel tubes are: (1) scanning drive; (2) DC drive; (3) Constant current source drive. The scanning methods used for screens with different needs vary. For indoor dot matrix block screens, scanning is mainly used. For outdoor pixel tube screens, to ensure the stability and clarity of their images, DC drive must be used to add a constant current to the scanning device.
In the early days, LED mainly used low-voltage signal series to parallel conversion, which had shortcomings such as many solder joints, high production costs, and insufficient reliability. These shortcomings limited the development of LED electronic displays for a certain period of time. To address the above shortcomings of LED display screens, a company in the United States has developed a specialized integrated circuit, abbreviated as ASIC. This type of integrated circuit can achieve series to parallel conversion and current driving in one. The integrated circuit has the following characteristics: high parallel output driving ability, with a driving current of up to 200MA, on which the LED can be immediately driven; Large current and voltage tolerance, wide range, generally flexible selection between 5-15V; The series-parallel output current is relatively large, with current inflow and output exceeding 4MA; The data processing speed is faster, suitable for achieving the driving function of the current multi gray color LED display screen.
4. Brightness control D/T conversion technology
LED electronic display screens are composed of numerous independent pixel points arranged and combined. Based on the characteristic of pixel separation, the LED display screen's emission control driving mode can only be expanded through digital signal form. When a pixel emits light, its emitting state is mainly controlled by the controller and independently driven. When a video needs to be presented in a color manner, it means that the brightness and color of each pixel need to be effectively controlled, and the scanning operation needs to be completed synchronously within the specified time.
Some large LED electronic displays are composed of tens of thousands of pixel points, and their complexity greatly increases during color control, thus placing higher demands on data transmission. It is unrealistic to set D/A for each pixel in the actual control process, so it is necessary to find a solution that can effectively control complex pixel systems.
Analyzing the principle of vision, people's average brightness of pixel points mainly depends on their light/off ratio. If the light/off ratio is effectively adjusted for this point, effective control of brightness can be achieved. Applying this principle to LED electronic displays means transforming digital signals into time signals, i.e. the mutual conversion between D/A.
5. Data reconstruction and storage technology
There are two main ways to organize memory groups currently. One is the combination pixel method, which means that all pixel points on the screen are stored in a single storage body, and the other is the bit plane method, which means that all pixel points on the screen are stored in different storage bodies. The direct effect of multiple uses of storage is to achieve the reading of multiple pixel information at once, as shown in the two organizational methods. Among the above two storage structures, the bit plane method has more advantages and is more effective in improving the display effect of LED screens. By using a data reconstruction circuit to convert RGB data, the same weight bits with different pixels are organically combined and placed in adjacent storage structures.
6. ISP Technology in Logic Circuit Design
The traditional LED electronic display screen control circuit is mainly designed using conventional digital circuits, and its control is generally achieved through a combination of digital circuits. Traditional technology starts the circuit board production process after the circuit design section is completed, and after the production is completed, relevant components are installed and the effect is debugged. When the logic function of the circuit board cannot meet the actual needs, it needs to be remade until it meets the usage effect. It can be seen that traditional design methods not only have a certain degree of contingency in terms of effectiveness, but also have a long design cycle, which affects the effective implementation of various processes. When components fail, maintenance is difficult and the cost is high.
On this basis, System Programmable Technology (ISP) has emerged, allowing users to have the ability to repeatedly modify their own design goals and components such as systems or circuit boards, enabling designers to transform hardware programs into software programs. Digital systems have taken on a new look based on system programmable technology. With the introduction and use of system programmable technology, not only does it shorten the design cycle, but it also fundamentally expands the use of components, simplifies on-site maintenance, and simplifies the implementation of target device functions. An important feature of system programmable technology is that when using system software to input logic, it is not necessary to consider whether the selected device has an impact. During input, components can be randomly selected, and even virtual components can be selected. After input is completed, adaptation can be carried out.
LED display screens have been widely distributed around the world and are closely connected to people's lives. In order to improve the luminous effect of LED electronic display screens and promote the scientific development of this technology, it is necessary to conduct in-depth research on the various drawbacks of traditional technology and introduce new technologies in a targeted manner to promote the excellent performance of LED electronic display screens and bring more convenience to people's lives and production. Based on understanding the requirements, conduct in-depth analysis and assessment of several key technologies, select the best technical solution, and obtain the best LED display effect.
LED electronic display screens can enable viewers to see the displayed content clearly, regardless of day, night, sunny or rainy days, meeting people's needs for display systems. A good LED display screen requires excellent performance in both design and performance. How to choose a suitable LED display screen requires understanding and considering the following six key technologies:
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 luminous system. The traditional approach is to use a video capture card combined with a VGA card to achieve display functionality. The main function of a video capture card is to capture video images and obtain the index addresses of line frequency, field frequency, and pixel points using VGA. The main way to obtain digital signals is by copying color lookup tables. Generally, software can be used for real-time replication or hardware theft, which is more effective. However, traditional methods have compatibility issues with VGA, resulting in poor image quality and blurry edges, ultimately resulting in damage to the image quality of electronic displays.
Based on this, the industry has developed a dedicated video card JMC-LED. The principle of this card is to use a 64 bit graphics accelerator based on the PCI bus to promote the integration of VGA and video functions, and to achieve a superposition effect between video data and VGA data. The compatibility issues that previously existed have been effectively resolved. Secondly, in terms of resolution acquisition, a full screen approach is adopted to ensure full angle optimization of the video image, no longer blurring the edges, and the image can be arbitrarily scaled and moved to meet different playback requirements. It can effectively separate the three colors of red, green, and blue, meeting the requirements for true color playback on electronic displays.
2. Realistic image color reproduction
The principle of full color LED electronic display screens in visual performance is similar to that of televisions, which effectively combine red, green, and blue colors to achieve different color reproduction of images. The purity of the three colors, red, green, and blue, directly affects the reproduction of image colors. It should be noted that image reproduction is not a random combination of red, green, and blue colors, but requires certain prerequisites.
Firstly, the ratio of light intensity between red, green, and blue colors should be close to 3:6:1; Secondly, compared to the other two colors, people have a certain degree of visual sensitivity to red, so it is necessary to evenly distribute red in the display space; Thirdly, due to the different nonlinear curve responses of people's vision to the light intensities of red, green, and blue colors, it is necessary to correct the white light with different intensities for the light emitted inside the television. The fourth is that different individuals have differences in their ability to distinguish colors under different circumstances, so it is necessary to identify objective indicators for color reproduction, generally as follows:
(1) The wavelengths of the three primary colors of red, green, and blue: 660nm, 525nm, and 470nm;
(2) It is better to use a 4-tube unit with white light (more than 4 tubes are also acceptable, mainly depending on the light intensity);
(3) The grayscale of the three primary colors is 256 levels;
(4) Nonlinear correction must be used to process LED pixels.
The light distribution control system for the three colors of red, green, and blue can be implemented by hardware systems or matched with corresponding playback system software.
3. Dedicated Reality Driver Circuit
The main methods for classifying current pixel tubes are: (1) scanning drive; (2) DC drive; (3) Constant current source drive. The scanning methods used for screens with different needs vary. For indoor dot matrix block screens, scanning is mainly used. For outdoor pixel tube screens, to ensure the stability and clarity of their images, DC drive must be used to add a constant current to the scanning device.
In the early days, LED mainly used low-voltage signal series to parallel conversion, which had shortcomings such as many solder joints, high production costs, and insufficient reliability. These shortcomings limited the development of LED electronic displays for a certain period of time. To address the above shortcomings of LED display screens, a company in the United States has developed a specialized integrated circuit, abbreviated as ASIC. This type of integrated circuit can achieve series to parallel conversion and current driving in one. The integrated circuit has the following characteristics: high parallel output driving ability, with a driving current of up to 200MA, on which the LED can be immediately driven; Large current and voltage tolerance, wide range, generally flexible selection between 5-15V; The series-parallel output current is relatively large, with current inflow and output exceeding 4MA; The data processing speed is faster, suitable for achieving the driving function of the current multi gray color LED display screen.
4. Brightness control D/T conversion technology
LED electronic display screens are composed of numerous independent pixel points arranged and combined. Based on the characteristic of pixel separation, the LED display screen's emission control driving mode can only be expanded through digital signal form. When a pixel emits light, its emitting state is mainly controlled by the controller and independently driven. When a video needs to be presented in a color manner, it means that the brightness and color of each pixel need to be effectively controlled, and the scanning operation needs to be completed synchronously within the specified time.
Some large LED electronic displays are composed of tens of thousands of pixel points, and their complexity greatly increases during color control, thus placing higher demands on data transmission. It is unrealistic to set D/A for each pixel in the actual control process, so it is necessary to find a solution that can effectively control complex pixel systems.
Analyzing the principle of vision, people's average brightness of pixel points mainly depends on their light/off ratio. If the light/off ratio is effectively adjusted for this point, effective control of brightness can be achieved. Applying this principle to LED electronic displays means transforming digital signals into time signals, i.e. the mutual conversion between D/A.
5. Data reconstruction and storage technology
There are two main ways to organize memory groups currently. One is the combination pixel method, which means that all pixel points on the screen are stored in a single storage body, and the other is the bit plane method, which means that all pixel points on the screen are stored in different storage bodies. The direct effect of multiple uses of storage is to achieve the reading of multiple pixel information at once, as shown in the two organizational methods. Among the above two storage structures, the bit plane method has more advantages and is more effective in improving the display effect of LED screens. By using a data reconstruction circuit to convert RGB data, the same weight bits with different pixels are organically combined and placed in adjacent storage structures.
6. ISP Technology in Logic Circuit Design
The traditional LED electronic display screen control circuit is mainly designed using conventional digital circuits, and its control is generally achieved through a combination of digital circuits. Traditional technology starts the circuit board production process after the circuit design section is completed, and after the production is completed, relevant components are installed and the effect is debugged. When the logic function of the circuit board cannot meet the actual needs, it needs to be remade until it meets the usage effect. It can be seen that traditional design methods not only have a certain degree of contingency in terms of effectiveness, but also have a long design cycle, which affects the effective implementation of various processes. When components fail, maintenance is difficult and the cost is high.
On this basis, System Programmable Technology (ISP) has emerged, allowing users to have the ability to repeatedly modify their own design goals and components such as systems or circuit boards, enabling designers to transform hardware programs into software programs. Digital systems have taken on a new look based on system programmable technology. With the introduction and use of system programmable technology, not only does it shorten the design cycle, but it also fundamentally expands the use of components, simplifies on-site maintenance, and simplifies the implementation of target device functions. An important feature of system programmable technology is that when using system software to input logic, it is not necessary to consider whether the selected device has an impact. During input, components can be randomly selected, and even virtual components can be selected. After input is completed, adaptation can be carried out.
LED display screens have been widely distributed around the world and are closely connected to people's lives. In order to improve the luminous effect of LED electronic display screens and promote the scientific development of this technology, it is necessary to conduct in-depth research on the various drawbacks of traditional technology and introduce new technologies in a targeted manner to promote the excellent performance of LED electronic display screens and bring more convenience to people's lives and production. Based on understanding the requirements, conduct in-depth analysis and assessment of several key technologies, select the best technical solution, and obtain the best LED display effect.