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How to Realize The LED Display Control System

LED display control system (LED Display Control System), also known as LED display controller, LED display control card. It is the core component of the LED display, and it is mainly responsible for receiving the picture and video display information from the computer serial port or DVI interface, putting it into the frame memory, and generating the serial display data that the LED display can recognize according to the partition drive mode. And scan control timing.

Through the analysis of the dot matrix module and control circuit, determine the component composition of the LED display; through the analysis of the single-chip microcomputer and the intelligent control module, determine the composition structure and scanning drive mode of the LED display to realize the display of the LED display.

How to realize the AL LED display control system

According to the application of the LED display control system, the system structure and work flow of the LED graphic display are designed. Among them, the software system and the wireless transmission control hardware main system use serial communication to complete the program download and realize the transmission of text information.

1 Overall analysis of the LED display control system

LED display system composition LED graphic display system consists of software control system, wireless transmission system, equipment main controller, LED display dot matrix, power supply and other parts. The basic structure is as follows:

How to realize the AL LED display control system

System working process: The main tasks completed by the software control system are graphic editing, font extraction and storage, image preview and file transmission; the wireless transmission system mainly completes the transmission of file information from the PC to the LED display, and the LED dot matrix in the hardware control system is mainly The task is to complete the information display through current control, and drive the LED dot matrix through the control of the scanning drive mode of the single-chip microcomputer to realize the drive of the device and finally realize the received graphic display function.

2 Analysis and design of computer software modules

The software module is divided into an editing part and a control communication part. The editing part realizes the editing function of graphic files, and the communication part completes the transmission of files to the SCM storage module through RS-232C serial communication. The communication part will be introduced in detail in Chapter 3. The system design adopts the Windows operating system, and the text editing window is opened. The pixels in the client area are the same as those of the actual LED dot matrix display. The functions are similar to Word document editing tools, including editing module, drawing module, text editing module, and color control. Module, display effect loading module, preview module, information download module.

2.1 Edit module

1) In addition to Windows self-generated cut and paste, copy, and paste functions, the system has added undo and repeat functions.

first. Select the undo function to realize the step-by-step cancellation function of the previous editing work. Then, select the repeat function to realize the last operation command of the previous editing work.

2) Drawing: Graphic drawing functions including straight lines, rectangles, ellipses, circles, etc.

3) Text editing: including editing of various fonts, fonts, font sizes, effects, and colors, and according to the special purpose of the application, adding the editing of the text at the specified location.

First, select the text function, and the font selection box will pop up, and you can select various fonts for editing. After that, call up the specific text position editing dialog box, enter the text and the abscissa and ordinate of the required display position.

4) Color control module: Due to the specific characteristics of the application field, three colors of red, green and yellow are mainly used to realize color control.

2.2 Adding effect module: By adding display effect and single-screen transmission of multi-screen files in the transmission communication, the function of the control system is improved.

1) Normal effect, static display of information on the screen.

2) Scrolling effect, which can realize scrolling display of information from left to right, which can be interspersed with static information.

3) Single-screen information transmission, which realizes the preservation of the edited information to be transmitted.

4) Multi-screen information transmission, which realizes that the edited and saved single-screen information is merged and saved into one file, which greatly reduces the cumbersomeness when transferring files.

2.3 Image preview module: Realize the preview function of font information before file transfer, which can preview any form of font information saved before transfer, and it is directly integrated into the toolbar file open function key button.

1) Display effect, through the preview before file transfer, you can adjust the sequence of static and scrolling display effects.

2) Display time, display the time interval between the information displayed on different screens. The software module structure diagram is as follows:

How to realize the AL LED display control system

3 LED display control technology

With the development and use of the fifth-generation "array-type" control system, the birth of this generation of control system has improved Yuanheng Optoelectronics' technical advantages in screen control, and further improved the display signal processing technology. After adopting the "array type" control system.

First of all, the frame change frequency of the display screen can be increased from the current 60Hz to above 120Hz, which is far greater than the resolution ability of human eyes, so that there is no stroboscopic and water ripple phenomenon when people are watching, and the quality of the display is improved.

Secondly, the gray level of the three primary colors of red, green, and blue of the display can be increased from the current 256 to 1024, making the colors more vivid, the color reproducibility better, and the displayed images more realistic.

Finally, the LDVS signal is used for transmission, which maximizes the avoidance of signal loss, synchronizes the display content of the entire display, and improves the consistency of the display. There is no color difference color block on the entire display.

3.1 Energy-saving and consumption-reducing technology

Due to the use of an array control system, it can effectively reduce the loss of display brightness caused by the control system used to generate grayscale. According to comparison calculations, the system loss of the traditional "centralized control system" is between 30% and 40% , The system loss of the "array control system" is between 8% and 10%. The reduction of the control system loss is beneficial to increase the brightness of the display, or under the same brightness conditions, reduce the current of the display to achieve The effect of energy saving and consumption reduction. Centralized control system, due to the large control range, in order to maintain a certain refresh rate, it has to reduce the number of scans and reduce the brightness to form grayscale; due to the small control range of the array control system, the scan times can be greatly increased, and the brightness loss will follow Become smaller. The scanning times of the array system can reach more than 136 fields, while the centralized system can reach 42 fields at most.

According to the principle of brightness loss, the calculation table is compared as follows: A 200 square meter outdoor full-color display with 3906 dots/square meter specification, if a drive current of 20mA is used, the theoretical maximum brightness can reach 15000cd/m2, if it is to reach 6000cd/m2 According to the 30% system loss, the display drive current is 11.4mA/pixel, and the maximum power supply current is 607A; if the “array control system” is adopted, it will reach 6000cd/ The maximum actual brightness of m2, according to the system loss of 10%, the display drive current is 8.89mA/pixel, the maximum current is 474A, and the energy saving rate reaches 21.9%. According to the average power consumption is 40% of the maximum power consumption, every day Based on the 10-hour use time and 300 days a year, the annual power consumption of the "centralized control system" is 160,248 kWh. The use of "array control system" consumes 125136 kWh of electricity every year, saving about 35,112 yuan/year (calculated at 1.0 yuan per kWh)

How to realize the AL LED display control system

3.2 Single point detection technology

In order to improve the reliability of the screen and increase the convenience of maintenance, Yuanheng Optoelectronics has developed a single-point detection technology for the display. Usually, the LED pixels are inspected by visual inspection before leaving the factory (that is, whether the human eye sees whether it emits light according to the debugging procedure). When viewing the LED pixels for a long time, it is inevitable that there will be some visual fatigue, missed judgments or misjudgments, and its work efficiency Not too high. Now our company uses the single-point detection function of the screen, just run the corresponding program, you can judge the working state of the pixel, and then repair it, which greatly improves the reliability of the screen. At the same time, with the continuous development of LED display technology, super large LED screens have emerged in the market. This type of screen is generally installed at a higher position and viewing distance is longer, which brings inconvenience to the detection work of the display screen. The judgment of each pixel can only be based on human judgment. After using the single-point detection function, maintenance personnel can easily find the coordinates of the fault point and quickly replace it.

How to realize the AL LED display control system

3.3 Single-point brightness and chromaticity correction technology

The uniformity of brightness and chromaticity of LED display screens has always been a major problem that plagues the industry. It is generally believed that the uneven brightness of LEDs can be corrected by a single point to improve the uniformity of brightness, while the unevenness of chromaticity cannot be corrected. It can only be improved by subdividing and filtering the LED color coordinates. As people’s requirements for LED displays are getting higher and higher, only subdividing and filtering the color coordinates of LEDs can no longer satisfy people’s critical gaze. Comprehensive correction of the display is achievable to improve the chromaticity uniformity. of. First of all, the brightness and chromaticity at a certain level are inconsistent due to the difference of the LEDs (for example: using the same current to light two green LEDs in the same production batch, the brightness may vary by 30%, and the wavelength may be There will be a change of 10-15nm). Secondly, after using for a period of time, the blue LED becomes the darkest and the red is the smallest, but the biggest problem is that the LED becomes darker differently after a period of time. Therefore, even if the consistency of the LED screen is perfect in the factory, as the LED becomes darker, the consistency will be lost. After three years of continuous use, the inconsistency of the LED screen will be significantly discovered. To this end, Yuanheng Optoelectronics uses the world's advanced monochrome brightness and chroma correction technology (also known as: brightness and chroma signature technology) to solve the problem of color inconsistency caused by inconsistent attenuation of different color LEDs .

In terms of display technology, LCD is a display screen composed of liquid crystals, and LED is a display screen composed of light-emitting diodes. Each pixel unit in an LED digital display is a light-emitting diode, and a monochrome LED display is generally a red light-emitting diode.

4 summary

In recent years, the domestic LED display technology has been further developed. my country's LED display has occupied 80% of the global market. However, it is not my country that leads the development of the display. To this end, LED manufacturers in the industry, such as Radisson Optoelectronics, will actively develop and upgrade LED technology. The overall design of the software control system of the LED display screen determines the system's work flow and completes the system software control function. According to the specific equipment communication requirements, the serial communication technology is adopted, and the communication between the control system and the hardware equipment is realized by introducing the port communication and the related knowledge of the serial communication protocol, and the text information transmission function of the LED display screen is realized. The technical control of the LED display screen is an important guarantee for determining the quality of the product.