Guide to LED Display Control System

At present, led display has become a symbol of modern, international city, which can be used to play text information, animated advertising, video images, 3D virtual reality, in advertising, sports, transportation, finance, communications, business, broadcast and other industries are widely used.

LED display is several display units (led module, led screen panel or unit cabinet) can be combined and spliced to form the screen, plus a set of appropriate controllers (main control card or control system), so a variety of specifications of the display board or unit cabinet with different controllers can be composed of many kinds of led display, used to meet the different use of the environment and demand.

As an essential component of the led video display, the control system accounts for 5-10% of the cost of the entire system of led display accessories, and it determines the merits of the screen display color, whether it can achieve a variety of colorful video effects, so we need to study it.

1. What Is LED Display Control System?

LED display control system, also known as led display controller, led display control card, led video processor. It is the core component of the led display, mainly responsible for receiving the screen and video display information from the computer serial port, network port or DVI interface, placed in the frame memory, according to the partition drive mode to generate the serial display data and scan control timing that the led display can identify.

2. Classification of Control System

• 1). According to the Display Mode:

A. Graphic Display System

Generally, just display graphics, text led video wall called graphics screen. The main feature of the graphic screen is that the led dot matrix of the light-emitting devices only light or off, and the intensity cannot be controlled, that is, this type of screen no gray level control, also name pixel led display controller/pixel led player.

B. Image Display System

Image display is relative to the graphic display, refers to those with gray level of the display, it shows a more vivid and realistic picture, the main feature of the image screen is the use of limited gray level and color modulation to display the color and gray scale requirements of the image is not high.

C. Video Display System

Can receive video signals and controller display motion, clear, full-color image of the led display is called video display.

• 2). According to the Control Mode:

A. Communication Display System

Communication display is an asynchronous display, asynchronous mode refers to the led screen body itself has the ability to store and automatically play, edit the text on the PC and no grayscale pictures and other display information or characters of the area code, picture number, etc. and a variety of control commands through the serial port or other network interface into the led screen controller, call the various data information stored in advance in the controller, according to the requirements of the instructions received into the display needs to be processed into the dot matrix data, released to the display.

These screens generally do not have multi-level grayscale display capabilities, mainly for displaying text and simple graphics information, can be multi-screen network. This method must require a box controller with CPU to process the information.

B. Real-time Mapping Screen System

Real-time mapping screen is a synchronous display, the basic function is to achieve real-time mapping of led display computer screen content, including the display of video images with the support of multimedia cards. The data from the host graphics card features port or video card on the graphics card processing to display data out, and then do some processing of these data to the led display. This approach can be used without a CPU controller, or even just make a hardware card can be achieved.

The 256-level gray led display system can make the led display complete synchronization with the computer display, and make it achieve high performance display effect. 256-level gray led display control by multimedia card, video wall controller, long line driver, receiving card and display unit.

Video controller from the standard display interface of the multimedia card to get the digital display signal, it will be converted to the signal format required by the display, it can also get the control signal from the standard interface of the computer, the user through the computer software to complete the control of the led wall display adjustment and make the display can adapt to different specifications multimedia card, with a high degree of compatibility.

• 3). According to the Communication Method:

A. Wired Communication Method

This is a communication method that uses physical media such as cables and optical fibers as a medium. It is believed that the wired communication based on public network will be more widely used in the future. The use of Internet for data transmission is also one of the main methods used in this system.

B. Wireless Communication Method

In the communication distance between the led screen controller and the monitoring center through radio waves to send information from the monitoring center. This way saves the system investment, shortens the construction cycle, and reduces the possibility of system theft. This way of communication is like cell phone short message from using GSM, GPRS or CDMA network for transmission, but also the use of broadcast towers, using FM or AM way to transmit and receive signals.

• 4). According to the Signal Access Method:

A. Asynchronous Control

LED display asynchronous control system is mainly used to display a variety of text, symbols and graphics or animation based.

B. Synchronous Control (Later will focus on Description)

LED display synchronous control system, mainly used for real-time display of video, graphics, notices, etc., mainly for indoor or outdoor full-color large screen display.

C. Wireless control hd led player: generally applied to many monochrome or small size full-color display, like cab, bus display, with GSM control, GPRS control, GPS control.

3. Asynchronous Control System

Asynchronous control system, also known as offline control system, or offline card, is mainly used to display a variety of text, symbols and graphics or animation. The screen display information is edited by the computer and pre-set into the frame memory of the led display through RS232/485 serial port and network port, and then displayed and played screen by screen, cyclically, in a colorful and varied display.

 •  1). Main features: simple operation, low led controller price, wide range of use.

 •  2). Display content: Graphic asynchronous control system can only display digital clock, text, special characters, support analog clock display, countdown, pictures, tables, and animation display. With functions such as timer on/off, temperature control, humidity control, etc.

 •  3). Communication mode: The control system is sent by serial port, network port, USB port, as well as the increasingly popular cell phone WIFI send.

Networking cluster: Wireless led control card can well meet the needs of the market of unified management and cluster sending by customers. For example, the community publicity led wall screen, car screen, government projects, mobile, telecommunications, bank door screen, bulk installation, easy to manage, to achieve a state of no maintenance, is the user’s best a choice.

 •  4). Sub-regional control: can be sub-regional control of the display screen content, and the contents of the computer monitor is not synchronized. First on the computer after editing, and then sent to the control card, when the control card and then display. So, even if the computer is turned off, the led display can also be displayed, but the amount of information played will be somewhat limited, because the control card storage capacity has a certain range. It is suitable for the real-time requirements are not high in the place.

 •  5) Readback function: single and double color led display control system generally have readback function, that is, if you open the corresponding led controller software, read back the control card parameters, you can enter different text content in the corresponding editing interface, editing is completed click send, you can replace the original text content played.

 •  6). Scope of use: mainly used in single and double-color display, because most of the single and double-color led display playback content for the walking word file, such as many store fronts display walking word, and the conference logo display walking word, and so on, this kind of playback content file is relatively small, mostly a few K, up to 1-2M, the required memory is relatively small, so the single and double-color led display control system is mostly asynchronous box/card.

 •  7). The advantages of asynchronous control: embedded chip performance is rapidly improving, asynchronous system growth accelerated, set program acceptance, storage, compilation, and other functions in one, the application is more flexible, a variety of functions, buy more, help differentiated marketing.

 •  8). Disadvantages of asynchronous control: customer awareness of the asynchronous system needs to be improved with a limited range of load program display effect is slightly inferior to the synchronous system.

 •  9). Brand introduction: the single and double color control system is more popular with the following manufacturers: Huidu, Listen, Onbon, Zhonghang, LongGreat and other control systems.

A. Xixun (http://sysolution.net/) and sheenled (http://www.sheenled.cn/), which are mainly WIFI features offline full color led display card, qualifications are relatively early.

B. Huidu (http://www.huidu.cn/index.php?lang=en), more offline use of small color screen, Southeast Asian market with more.

C. Listen (http://en.listenvision.cn/), is also a rising star, before making a single-color small screen card, and now the color, and sports control system, Southeast Asia market more.

D. Onbon (http://www.onbonbx.com/index_en.html) single-color pc led controller board compared to the most stable, the price is relatively high.

E. lytec and LuMen, two old single-color dual-color led screen controller card, a lot of government-designated.

F. LongGreat (http://www.led595.com/), more used in Taiwan.

G. Zhengzhou Zhonghang(www.zhonghangled.com), the price is more favorable, China and Southeast Asia with a lot.

 •  10). Asynchronous playback system can also be used for small area full color led display, used to play circular notices, video ads, promotional pictures, promotional videos, the text, pictures, or videos to be played and other content sent to the asynchronous memory card for cyclic playback, mostly used in small exhibition halls, street advertising screen, door screen, traffic guide screen, light pole screen and other scenes.

 •  11). With the advancement of 4G technology maturity, the combination of asynchronous playback system loaded with 4G module is also very popular in the application scenarios that require remote sending control, such as traffic guide screens and street side column screens. The more popular led video player of async media player system are TB series of Novsatar(TB30/TB50/TB60), C series of Huidu, C series(C3 Player) ultra media player of Colorlight etc.

4. Synchronization Control System

LED display synchronization controller, mainly used for indoor or outdoor full-color large screen display for real-time display of video, graphics, notices, etc. LED display synchronous control system-controlled display is basically equivalent to the computer monitor, it is at least 60 frames / second update rate point corresponding to the computer monitor in real time mapping images, usually with multi-grayscale color display capabilities, can achieve the effect of multimedia publicity and advertising.

Synchronous controller is generally used for full-color display, so also called full-color control system, full-color led display screen playback content is mostly pictures, videos, PPT and other data relatively large files, according to the demand for playback, we generally use synchronous playback system.

Its main function is to synchronize with the computer monitor to display the playback content, that is, what is played on the computer, what is played on the led display, the led display and the computer monitor is completely synchronized with the content of the display, at present, the main use of network cable as the medium of data transmission.

 •  1). Main features: real-time, expressive, more complex operation, high led card price, and the content on the computer monitor is fully synchronized display, so that if the computer is turned off, then the led display is not displayed, so the playing time will be somewhat limited.

This kind of system, mainly used for real-time requirements are relatively high in the place. A set of led display synchronization control system generally consists of a sending card, receiving card, and DVI graphics card.

 •  2). The advantages of synchronous control: with the computer system, superior performance, suitable for fixed location, display effect requirements of high places. Many years of development system maturity, perfect function, support for live video and other ways. With a large range of load, display effect is good, suitable for traditional large screen project.　　

 •  3). The disadvantages of synchronous control: dependence on computer systems, playing sites have restrictions on the function of homogenization is serious, the market competition is fierce traditional project market saturation, growth is weak.

 •  4). Brand: generally, in the computer display settings set to “copy mode” (or a few multi-screen synchronous playback requirements “extended mode”). Synchronous playback system is more popular brands are the following: Novastar, Colorlight, Linsn, Mooncell, ZDEC and so on, which is a high market share in the large screen applications in the stage is Novastar processor and Colorlight led controller.

A. Novastar: Xi’an, China, Europe, and the United States export customers generally specified used, the effect is perfect, there are many service providers all over the world, the website is: http://www.novastar-led.com/product.php

B. Linsn: Shenzhen, China, the old brand of screen card suppliers, a few years ago, a high profile, accounting for at least 60% of full-color technical control systems market, but at any time the rise of Novastar, the market share has declined, but Still in the domestic market enjoy a high terminal designated position, the website is: http://www.linsn.com/

C. Colorlight: Beijing, China, is also a led screen controller solution provider that started almost at the same time as Novastar, and has a lot of domestic use, such as 3D video player(Z6 Pro super controller), especially in the northern region. The website is http://www.lednets.com/ index.html

D. In addition there Mooncell (special custom shaped screen with more, the site is: http://en.mooncell.com.cn/), ZDEC (http://www.zdec.com/en/), Dbstar (http://en.ledall.com/)

• 5). Video Processor Brand:

LED display screens have a widely chosen led video processor. They are required for TV relay centers, exhibitions, meetings, large-scale stage and theatre etc.

A. Xi’an Novastar: The most popular video wall processor on the international market today, and have technical services on many continents and in more than 150 countries, main video processor products: Novastar vx4s/vx6s/vx1000/vx16s, website is: http://www.novastar-led.com

B. Shenzhen VDwall; the main processor suppliers, the market occupies a larger export volume is also large, the site is: http://en.vdwall.cn/

C. Shenzhen Speedleder (http://www.jstron.com/)

D. Shenzhen Magnimage (http://www.magnimage.com/),can do a large monitor

E. Beijing Kystar (http://www.kystar.com.cn/en/)

F. Beijing Shiruxun (http://en.shiruixun.com/)

G. Xiamen RGBlink (http://www.rgblink.net/en/)

• 6). Control System Composition

LED video display system is composed of control software/wireless transmission system, equipment main controller (sending card, sending box, video processor, Wifi receiving module), receiving system (receiving card), monitoring equipment, long-distance transmission fiber optic system and other parts.

Sending card/box is to display the content to be displayed on the VGA monitor according to the specific format and certain broadcast order required by the led display; on the other hand, the screen displayed on the VGA monitor is sent to the control board through the collecting card, which is the interface card between the VGA for display card and the led screen.

The receiver card is to receive the video signal (control signal and data signal) transmitted from the transmitter card, and the data in the video signal will be separated by bit plane and stored in external cache by partition, and then read out by partition and transmitted to the display driver screen.

• 7). System Working Process

Software control system mainly completes the task of graphic editing, word pattern extraction and preservation, image preview and file transfer; signal transmission system mainly completes the file information transfer from PC to led display, hardware control system led dot matrix main task is to complete the information display through current control, through the control of the microcontroller scanning drive mode to the led dot matrix ranks drive, realize the device drive and The final realization of the received graphic display function.

A. The signal source can be a video camera, laptop, desktop computer, DVD, and other video output devices.

B. The signal through the video processor, converted into DVI signal, through the DVI line connected to the transmitter card.

C. The control room distance from the display is greater than 100M, the use of fiber optic conversion card, using fiber optic cable communication.

D. Each display case has 1 receiving, receiving card between the use of network cable for connection and communication.

E. As the display is T-shaped appearance, the system transmission adopts the communication method from bottom up.

F. The display can play a variety of content, you can switch the input source.

G. The use of cameras can play real-time video signals to the top of the display, can also be linked to the digital set-top box, play TV content.

H. You can use the playback led card software to play the pre-processed video picture information on the computer.

• 8). System Advantageous Features

Compared with traditional display equipment, this huge future demand makes large screen display technology the focus of attention:

A. LED display is an epoch-making product with rich colors, varied display methods (graphics, text, 3D video, 2D animation, TV screen, etc.), high brightness and long life, which is an information dissemination facility.

B. LED display is a high technology product integrating optoelectronics, microelectronics, computer technology and information processing technology, which can be used to display text and computer screen synchronized graphics. It is a widely used display system in the world with its unique advantages such as large screen, super vision, flexible and changeable display.

C. LED screen wall is widely used in finance and securities, bank rates, commercial advertising, culture, and entertainment, etc. It has huge social benefits and lucrative economic benefits.

5. Precautions When Using the Control Card

 •  1). The card should be kept in a dry and relatively stable environment. Excessive temperature, humidity, and dusty environment are extremely detrimental to the card.

 •  2). In the case of no power failure, it is strictly prohibited to plug and unplug the serial port, so as not to damage the computer serial port and the control led card serial port due to improper operation.

 •  3). When the system is working with power, it is strictly prohibited to adjust the input voltage of the control card, so as not to damage the computer serial port and the control card serial port due to improper adjustment and high voltage. The normal operating voltage of the control card is 5 V. When adjusting the power supply voltage, the control card should be removed and slowly adjusted with a multimeter.

 •  4). Strictly prohibit the grounding end of the control card and the display frame short connection, otherwise the display frame once gathered static electricity, it is easy to damage the computer serial port and control card serial port, resulting in unstable communication, static electricity will seriously burn the control card and the display unit on the screen body.

Therefore, in the outdoor screen or communication distance, it is recommended that users must use the serial port isolator to avoid damage to the computer serial port and control card serial port due to ground loops, surges, induction lightning strikes, hot plugging and other harsh environments.

 •  5). Must ensure the correct connection between the control card and the computer serial port to avoid damage to the control card serial port and the computer serial port due to incorrect input signal.

 •  6). Do not connect the control card to the unit board. To try to lead directly to the switching power supply, the unit board in the process of working voltage and its unstable. It will cause the control card fast and slow, serious communication or program run away need to be repaired, especially the U disk control card, in the case of unstable voltage may not be able to read the disk or read the disk error.

 •  7). Indoor, unit led display board should not be connected to the whole screen debugging, many indoor full colors, and then not debugged state directly connected to the control card power, there may be a large area burned behind the unit board line scan driver chip. Debugging, please only connect a unit board debugging, debugging finished unplugging power, and then connect the control card.

6. Common Problem Solutions

Full color led display control card in the use of common problems are generally divided into: display problems, communication problems, functional requirements, the solution to the trilogy: press the test button (to measure the power supply and the connection of the line), serial communication, then point the led panel display software in the switch (to measure the port and communication line), disconnect the power and so all the light beads off and then power on (initialization).

 •  1). Control card is normal, why the display does not show or brightness abnormal?

A: When the led control card/led control box is connected to the display driver, the default is 16 scanning, if there is no display, please check whether the data polarity and OE polarity settings in the control led software download are correct; if the brightness is abnormal, one line is particularly bright, indicating that the OE settings are reversed, please set the OE correctly.

 •  2). Why can’t the display show normally after the information is loaded?

A: Check whether the scan output selected in “full color led display control card setting” is correct.

 •  3). After sending successfully, the display shows splash screen, garbled code, regular movement (cannot see the word)?

A: Typical scanning mode selection error, semi-outdoor, outdoor general 4 sweep, indoor 16 sweep, 32 sweep; set the screen reference to change after saving and send successfully can be.

 •  4). After sending successfully, the display appears horizontal bright line, every few lines of the kind of light 1 line.

A: The direction of the line is reversed, press the test button (control card comes with), this situation is generally not switched, the connection led display and control card end of the reverse connected on it.

7. Adoption of LED Control Technology

• 1). Energy Saving and Consumption Reduction

The use of array control system, so it can effectively reduce the control system for generating grayscale caused by the loss of display brightness, according to comparative calculations, the traditional “centralized control system” system loss between 30% to 40%, “array control system” system loss between 8% to 10%, the reduction of control system loss is conducive to improving the brightness of the display, or in the same brightness conditions required to reduce the current of the display, so as to achieve the effect of energy saving and consumption reduction.

• 2). Single Point Detection

To improve the reliability of the screen and increase the convenience of maintenance, the display single-point detection technology was developed. Usually led display factory inspection of led pixels is through visual inspection (i.e., the human eye to see whether it is glowing according to the debugging procedure), in a long time to watch the led pixels, there is inevitably a certain amount of visual fatigue, missed or misjudged, and its efficiency is not high.

Using the screen single point detection function, just run the corresponding program, you can determine the working status of the pixel, to repair, greatly improving the reliability of the screen. At the same time, with the continuous development of led display technology, super large led screen emerged in the market.

Such screens are generally installed in a high position, the viewing distance is far, for the detection of the display work inconvenience. The judgment of each pixel can often only be based on human judgment, in the use of single-point detection function, maintenance personnel can easily find the coordinates of the failure point, quick replacement.

• 3). Brightness and Chromaticity Correction

LED video panel brightness and chromaticity uniformity has been a major problem plaguing the industry, it is generally believed that the led brightness unevenness can be single-point correction to improve the brightness uniformity, while chromaticity unevenness is not correctable, only through the led color coordinates for subdivision and screening to improve.

As people’s demand for led display is getting higher and higher, only subdivision and screening of led color coordinates can no longer meet people’s discerning eyes, and comprehensive correction processing of the display to improve the chromaticity uniformity is achievable.

A. Due to the difference of leds themselves lead to a certain level of brightness and chromaticity is not consistent (for example: using the same current to light up the same production batch of two green leds, the brightness may have a 30% change, the wavelength may have 10-15nm change).

B. After a period of use blue leds dim the most and red the least, but the biggest problem is that after a period leds dim differently. Therefore, even if the led screen is perfectly consistent in the factory, the consistency will be lost as the led dims, and the inconsistency of the led screen will be significantly found after three years of non-stop use.

For this reason, the world’s most advanced monochrome luminance and chromaticity correction technology (also called: luminance and chromaticity signature technology) is used to solve the problem of inconsistent color rendering due to inconsistent attenuation of different color light-emitting diodes.

C. The point-by-point correction system is a comprehensive set of novastar led wall software and hardware systems that can measure and correct each pixel on the led display, and this system can correct the luminance and chromaticity for each pixel of the whole screen to achieve consistent performance characteristics.