Process Analysis of LED Video Processor Processing the Display Effect of LED Display Screen

Video processor is the witness and landmark equipment for the birth, growth and maturity of full-color LED display. Today, led special video processing equipment is also gradually maturing in this process. The quality of LED video processor directly affects the display effect of LED display.In general, LED video processor is a special video processor for LED. The task it needs to complete, in short, is to convert the image signal from the outside (such as Blu ray DVD, computer, HD playback box, etc.) into the signal acceptable to the LED display screen. In this process, the LED video processor generally needs to complete the following processing processes:1 Resolution specification conversion: Generally speaking, the signal resolution provided by image signal sources (such as Blu ray DVD, computer, HD playback box, etc.) has fixed specifications (refer to VESA, ITU, SMPTE and other standards), while the modular splicing display of LED display makes its resolution almost arbitrary. The video processor converts various signal resolutions into the actual physical display resolution of LED display screen.

Process Analysis of LED Video Processor Processing the Display Effect of LED Display Screen 1

2 Color space conversion: the color gamut of LED display is very wide, while the color space of most image signals is relatively small (such as NTSC). In order to make the LED display have excellent image display effect, color space conversion must be carried out.3 Bit depth improvement: at present, the gray level of LED display has been increased to 16 bits and 17 bits, but most of the input signal sources are only 8 bits. Therefore, following the arrival of the era of high-definition display, the application of 10 bit or even 12 bit processing technology in video processor has become a general trend.4 Zoom: in the process of resolution specification conversion, the image needs to be scaled. Whether the resolution is increased or decreased, the complete image can be displayed on the screen.

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Common Faults and Troubleshooting of LED Display Screen
Common Faults and Troubleshooting of LED Display Screen
Unit board fault:A. The whole board is not bright1. Check whether the power supply is connected to the signal line.2. Check whether the test card can identify the interface. If the red light of the test card flashes, it will not be identified. Check whether the lamp board is connected with the power supply and ground of the test card, or there is a short circuit between the signal and ground of the lamp board interface, so that the interface cannot be identified. (smart test card)3. Detect whether 74hc245 has faulty welding or short circuit, and whether the corresponding enable (EN) signal input and output pin on 245 has faulty welding or short circuit to other lines.Note: mainly check the power supply and enable (EN) signal.B. During oblique scanning, regular interlaced lines are not lit, and the display screen overlaps1. Check whether there is broken wire, faulty welding or short circuit between a, B, C and D signal input ports and 245.2. Check whether there is open circuit, faulty welding or short circuit between output terminals a, B, C and d corresponding to 245 and 138.3. Detect whether there is a short circuit between signals a, B, C and D or whether a signal is short circuited to ground.Note: it mainly detects ABCD line signal.C. When fully lit, one or more lines are not lit1. Detect whether the line between 138 and 4953 is open circuit, faulty welding or short circuit.D. During line scanning, two or more lines (generally multiple of 2, regular) are lit at the same time1. Check whether there is a short circuit between signals a, B, C and D.2. Check whether the 4953 output terminal is short circuited with other output terminals.E. Single or multiple points (irregular) do not light up when fully lit1. Find the control pin corresponding to the module and measure whether it is short circuited to the line.2. Replace the module or single lamp.F. When fully lit, one or more columns are not lit1. Find the pin controlling this column on the module and test whether it is connected to the output of the drive IC (74HC595 / TB62726,,).G. There is single point or single column highlight, or whole row highlight, and it is not controlled1. Check whether the column is short circuited to power and ground.2. Check whether the line is short circuited to the positive pole of the power supply.3. Replace its drive IC.H. The display is confused, but the signal output to the next board is normal1. Detect whether the STB latch output terminal corresponding to 245 is connected with the latch terminal of the drive IC or whether the signal is short circuited to other lines.1. The display is confused and the output is abnormal1. Detect whether the clock CLK latch STB signal is short circuited.2. Detect whether the clock CLK of 245 has input and output.3. Check whether the clock signal is short circuited to other lines.Note: it mainly detects clock and latch signals.J. Display out of color1. Detect whether the data terminal of the color of 245 has input and output.2. Detect whether the data signal of this color is short circuited to other lines.3. Check whether there is open circuit, short circuit and faulty soldering at the cascade data port between the driving IC of this color.Note: it is easy to find the problem by using the voltage detection method to detect whether the voltage of the data port is different from the normal one and determine the fault area.K. There is a problem with the output1. Check whether the line from the output interface to the signal output IC is connected or short circuited.2. Check whether the clock latch signal of the output port is normal.3. Check whether the cascade output data port between the last drive IC is connected with the data port of the output interface or short circuited.4. Whether the output signals are short circuited to each other or to the ground.5. Check whether the output cable is in good condition.Full screen fault:The whole screen does not light up (black screen)1. Check whether the power supply is powered on.2. Check whether the communication line is connected and whether there is a wrong connection. (step by step screen)3. The synchronization screen detects whether the communication green light of the sending card and the receiving card flashes.4. Whether the computer monitor is protected, or whether the display area is black or pure blue. (step by step screen)The whole unit board is not lit (black screen)1. If several consecutive boards are not lit in the transverse direction, check whether the cable connection between the normal unit board and the abnormal unit board is connected; Or whether the chip 245 is normal.2. If several consecutive boards are not lit in the longitudinal direction, check whether the power supply of this column is normal.The unit board does not light up1. Check whether the line pin is connected with the 4953 output pin.2. Check whether 138 is normal.3. Check if 4953 is hot or burnt.4. Check 4953 for high level.5. Check whether the 138 and 4953 control pins are connected.Unit board does not light up1. Check whether 595 is normal.2. Check whether the corresponding pins of the upper and lower modules are connected.3. Check whether the 595 output pin is connected to the module pin.Unit board lack of color1. Check whether 245 R.G data is output.2. Check whether the normal 595 output pin and the abnormal 595 input pin are connected.
How Does QFN Package Solve the Heat Dissipation Problem of LED Display Screen
How Does QFN Package Solve the Heat Dissipation Problem of LED Display Screen
QFN package (quad flat no leads) - QFN is the name specified by Japan Electronic Machinery Industry Association (JEDEC).Four side pinless flat package, one of the surface mount packages, is a new surface mount chip packaging technology with pad at the bottom, small size, small volume and plastic as sealing material. Because QFN package does not have gull wing lead like traditional SOIC package, and the conductive path between internal pin and pad is short, self inductance? S number and package body? How long does it last? Therefore, it can provide excellent electrical performance, and because there is no gull wing lead, it can reduce the so-called antenna effect and reduce the overall electromagnetic interference (EMC / EMI). In addition, it also provides excellent heat dissipation through the exposed lead frame pad, which has a direct heat dissipation channel to release the heat of the chip in the package. Usually, the heat dissipation pad is directly welded on the circuit board, and the heat dissipation via in the PCB helps to diffuse the power consumption of the multi harrier into the copper grounding plate, so as to absorb the heat of the multi harrier; It can also achieve better land sharing effect. At present, QFN package has been widely used in general mobile phones and laptops, but it is about to flourish in LED display.Comparison of heat dissipation, size and volume between QFN and SOPGenerally, the size of SOP used is 104 mm2 (8x13x1.9mm), while the relative size of QFN is only 16mm2 (4x4x0.9mm), which is only 6 7 times the size of SOP; It has greater flexibility in the design of some small spacing display screens.Thermal resistance Ja) the coefficient is SOP = 59 / W, QFN = 39 / W, that is, the temperature from the chip node to the surface at the power of one watt. The following is the calculation formula of thermal resistance commonly used in the industry:TJ= ja*PDTaTJ= jc*PDTc Ja= jc* caSymbols and units used in the formula TJ C: node (chip) temperature Tc C: actual temperature Ta C: ambient temperature PD W: power supply voltage JA ( C / W): heat transfer impedance from actual to external surface JC ( C / W): heat transfer impedance from node to actual Ca ( C / W): heat transfer impedance from actual to external surfaceIn other words, if the same return temperature and power consumption, the node temperature on the chip will be different due to different packages. For example: if the ambient temperature is 85 C and the power consumption of the chip is 0.5W, the temperatures of SOP and QFN are as follows:Design of lamp drive in oneDue to the two characteristics of small volume and good heat dissipation of QFN, in the past, the specifications below pitch 16mm of outdoor display screen will choose the design of lamp drive separation because of the limitation of PCB board size routing and heat dissipation; That is, the LED light board and the driver chip board are placed on two to three different PCB boards respectively, and then connected with each other through connectors and cables. Although this design can solve the heat dissipation problem, the inductive effect generated through the connectors and wires may greatly reduce the color resolution of the display screen, and the inductive effect will also increase the chance of electromagnetic interference. When using QFN design; Because of its small size and no heat dissipation problem, the chip can be placed in the gap of the LED lamp. Therefore, it does not need to use more PCB boards and transmission lines. It is simpler in design and its cost can be reduced. Similarly, if the QFN design is used for the indoor display screen, the heat dissipation problem can also be greatly improved.
Factors Affecting the Price of LED Display Screen
Factors Affecting the Price of LED Display Screen
How much is a square meter of full-color LED display in Zhengzhou, Henan Province? For customers who intend to buy LED screens, in addition to caring about product quality, price is also a crucial factor. However, the price of LED display screen is related to many factors. To understand the price more clearly, please look down:How much is a square meter of full-color LED display screen in Zhengzhou, Henan Province? It is closely related to the basic configuration of LED screen, including LED beads, chips, box materials, and even related to the processing technology, direct insertion or surface paste. Generally, die cast aluminum LED box is more durable than sheet metal box, but the price is also higher.At present, the most widely used outdoor P10 full-color display screen has a price range of 3000-5000 yuan / square meter. Due to the changes of market conditions, this is for reference only. The quotation of each LED display manufacturer will be different, and the quality and performance will be different. There are also cheaper ones, lower than 2000, but cheap products are generally not cost-effective, the quality is not guaranteed, the probability of problems is high, and after-sales is difficult. Hengyuan optoelectronics reminds you that the purchase price of LED display screen is not the only factor, which should be measured by comprehensively considering the regularity of the manufacturer, product use and environment.The factors affecting the price of LED display project are as follows:1. LED screen size: for example, if the customer customizes an outdoor LED display with a length of 10 meters and a width of 6 meters in lianchengfa, the salesperson will select P8 or P10 according to the size provided by the customer and give the specific scheme and price.2. Raw materials: including different types of LED lamp beads, lamp boards and boxes3. Control system: there are two common types: Nova and yangbang.4. Supporting equipment: computer, lightning arrester, sound, power amplifier, distribution cabinet and air conditioner, etc.5. Steel structure materials and installation: such as common wall mounted and column installation. The construction prices of the two are different. Others include the selection of frame structure materials.LED display engineering price = screen price * screen area control system cost frame structure cost transportation and installation cost distribution system cost, including power line, data line steel frame and civil engineering cost taxThe above is the information about how much a square meter of full-color LED display screen is. Only by clarifying the LED screen area, model and installation mode, the quotation obtained can have practical significance. Therefore, if you encounter an easily quoted LED display manufacturer, you generally can't believe it.Zhengzhou Hengyuan Optoelectronics (Zhengzhou Hengyuan display equipment Co., Ltd.) was established in 2007 and is the general distributor of lyade LED electronic display screen in Henan. Liyade Henan Branch, after more than ten years of development, the company headquarters has established a large spot warehouse in Zhengzhou Zhongli advertising market, and built Zhengdong center in Zhengdong New Area, with Flagship Exhibition Hall, office area, etc. It also has branches in Hohhot, Lanzhou, Xining, Yinchuan, Lhasa, Shandong and other cities. The company is mainly engaged in LED display screen, and its agent brands include: liad (the market value of LED display screen ranks first in the industry), Shanghai yangbang control card, Xi'an Nova control card, Changzhou Chuanglian power supply, hy full-color power supply, distribution cabinet, video processor and other LED display screen peripheral supporting products. Channel products, indoor, outdoor, small spacing 1.8, 1.5, 1.2, all-in-one conference machines are available.
Analysis of System Composition and Architecture of LED Display Screen
Analysis of System Composition and Architecture of LED Display Screen
As a high-tech product, LED display has attracted great attention. The intelligent full-color display, which is controlled by computer and integrates light and electricity, has been applied in a wide range of fields. The pixel points adopt LED light-emitting diodes, and many light-emitting diodes are arranged in a dot matrix to form an LED array and then an LED screen. Through different LED driving modes, images with different effects can be obtained. Therefore, the advantages and disadvantages of LED driver chip play an important role in the display quality of LED display screen. LED driver chips can be divided into general chips and special chips.General purpose chips are generally used for low-end products of LED display screens, such as indoor single and dual color screens. The most commonly used general chip is 74HC595, which has the functions of 8-bit latch, serial shift register and three state output. Each channel can output 35mA non constant current at most.Because LED is a current characteristic device, that is, on the premise of saturated conduction, its brightness changes with the change of current, not with the change of voltage at both ends. The biggest feature of the special chip is to provide constant current source output, ensure the stable driving of LED and eliminate the flicker of LED. With the characteristics of high output current and constant current, it is suitable for occasions requiring high current and high image quality, such as outdoor full-color screen, indoor full-color screen, etc.LED driver chip series products for LED display smt5026.smt5026 has built-in CMOS shift register and latch function, which can convert serial input data into parallel output data format.Part II: system architecture of LED display screen(1) Display unitThis is the main part of the LED display screen, which is composed of luminous materials and driving circuits. The indoor screen is the unit display board of various specifications, and the outdoor screen is the unit box.(2) Main controllerThe function is to buffer, transform and reorganize the input RGB digital video signal, and generate various control signals.(3) Switching power supplyThe purpose is to change 220V AC into various DC to supply various circuits.(4) Transmission cableThe display data and various control signals generated by the main controller are transmitted to the screen body by twisted pair cable.(5) Scan controllerThe function of the circuit board is to buffer data and generate various scanning signals and duty cycle gray control signals.(6) Special display card and multimedia card (video card)In addition to the basic functions of the computer display card, the LED full-color display card also outputs digital RGB signals, line, field, blanking and other signals to the main controller. In addition to the above functions, the multimedia card can also change the input analog video signal into digital RGB signal (i.e. video acquisition).(7) Other signal sources and their external devices
Aventk UV Color Changing Black Glue 1098 Can Effectively Solve the Reflection Problem of OLED Displa
Aventk UV Color Changing Black Glue 1098 Can Effectively Solve the Reflection Problem of OLED Displa
Reflective problem of OLED display The core of OLED is a transparent organic semiconductor polymer, which can be made into a thin film and emit light by applying an electric field on both sides. Because the structure of OLED panel is very simple in theory, very thin products can be made. At present, the thickness of OLED display screen in mass production is only 0.95mm. Although OLED display is a self luminous product, after removing the backlight, there should be no problem of backlight leakage in theory. However, in terms of actual products, due to the existence of MF coating, there is still a problem of reflection around the edges of the display screen, as shown in the following figure:Therefore, how to solve the reflective problem of OLED display has become a concern of many manufacturers. In this regard, aventk has also studied and tested for many times, and finally determined that aventk 1098 series UV color changing black glue can solve this problem. Aventk UV color changing black glue 1098 can solve the problem. In solving the reflection problem of OLED display screen, most of them used UV black glue before. However, UV black glue needs to take into account UV light irradiation, so the blackness cannot be too deep, otherwise UV light cannot irradiate the cured glue. However, if UV glue black is not enough, it can not achieve good light blocking effect.To solve this problem, aventk 1098 series UV color changing black glue can be solved. Aventk UV color changing black glue contains aventk's exclusive NYX technology. NYX technology is aventk's unique UV light dyeing technology, which perfectly combines UV light with glue dyeing. It is a transparent color before UV curing and can well absorb UV light. After UV curing, it becomes black (or other colors). It not only meets the high efficiency of UV light curing, but also quickly completes the dyeing of glue. Put aventk UV color changing black glue is applied around the OLED display screen and between the screen and pol, which can greatly reduce the problem of reflection. fqj
LED Display Screen Enterprises to Enter the Field of 'price' -Information Industry News
LED Display Screen Enterprises to Enter the Field of 'price' -Information Industry News
Explore what your device can do and how to use it. Always On Display allows you to view the clock, battery and missed phone call/message notifications when the screen is turned off. The Always On Display screen uses less power and also utilizes the proximity sensor to turn off completely when in a purse or pocket. The user can change what appears on the Always On Display screen. Back up and sync your contacts, photos, videos, and more from your device. Bixby Vision gives you a deeper understanding of what you are looking at through your camera by identifying landmarks, translating languages, or showing you where to buy an item. Watch, search, and record your favorite movies and shows, and turn your device into your remote control, with the DIRECTV app on your phone. All of HBO together with new hits, classic favorites, plus new Max Originals. Hello Bixby allows you to quickly set reminders, create voice dictation, search and access content on your phone and on the internet. The Multi Window feature provides split-screen functionality, which allows you to use two applications at the same time. Complete multiple tasks on one screen, take notes while watching a video, or search the web and check your email messages simultaneously. View and pay your AT&T bills online, manage your account, reset passwords, or upgrade your AT&T services.Learn how to find your device and secure your info. Free apps typically get revenue through ads, pop-ups, or notifications. Learn how to manage these on your device. Find My Mobile allows you to manage your device in a secure way by tracking and controlling your device remotely. Secure your personal content and keep it hidden on your device. Lock or unlock your display, set a screen security lock type (pin, password, pattern, fingerprints, or iris and face recognition), get your PUK code, or request your device be unlocked from the ATnT network. Learn how to determine if you might have harmful software (malware) on your device and get tips to help fix the issue.Given current technology, could TV display screens double as video camera sensors?Yes, with interferometry based synthetic aperture imagery, but...It would take several orders of magnitude improvement in digital signal processing technology for it to work at the scale of a video screen. The sensors will need to record at a very high data rate, on the order of petahertz. Every single pixel will be receiving all of the light that is in its field of view, and none of the light will be focused. Fortunately, light is not just photons, it's also electromagnetic waves. The sensors will behave like antennas, rather than eyes, passively collecting the radio waves at the wavelength of visible light.Radio signal sources can be tracked quite easily, by measuring the timing of a wave reaching multiple antennas. The same applies to all sorts of waves; an earthquake's epicenter is calculated by measuring the timing when the waves arrive at seismometers. We even have the same types of sensors built into our own human bodies. : Our ears can taking a wave and determine the direction that it came from, based on changes of intensity and timing. We have already proven the concept using vast antenna arrays to collect unfocused photons, to create a focused image. We imaged the supermassive black hole M87* using the Event Horizon Telescope.Of course, when astronomers use the term "photon" they do not just mean visible light; they mean any coherent electromagnetic wave. This image represents the peak of current engineering feasibility for synthetic aperture imagery. The EHT uses a Very Long Baseline Interferometry, which works in 450 GHz, using very narrowly calibrated equipment designed specifically to tease out the glow of the accretion disk at the wavelengths to detect event horizons around black holes. In order to get meaningful data, though, your sample rate needs to be at least twice the frequency of the signal rate, preferably more than 4 times the signal rate, or you start getting downsampling errors called aliasing. In order to record visible light, which has frequencies between 405 THz to 790 THz, you will need a sample rate that is at least 1.58 PHz.Due to limitations from the speed of light, and the time that it takes electrons to pass through silicon and copper in computers, this is just past the fastest speed that we can record data meaningfully.We would have to pass the data from several sensors in order to build up a meaningful synthetic aperture image from interferometry. We would need specialized recording technology that we just do not have yet.And, there's also the problem that LEDs are not designed to collect light, even though they are capable of doing it. .. just as sound coming out of a microphone would sound terrible, and sound recorded from speakers is also low quality. It would take several generations of iterating on the current science in order to use an LED-based computer monitor to record what is happening it a room, and it will always require specialized systems to just record the data in a meaningful way, much less process it into an image. It took several petabytes of data and 3 years of processing in order to build the EHT's image of M87*. It was faster to hand-carry the hard drives from the telescopes around the world to the datacenter, than it would have been to send the data over high speed internet links. It would take a lot of iterative work to miniaturize the chips necessary to do the calculations, but the technology just barely exists.Such a screen would be prohibitively expensive, as it's much easier to just put a lense in front of a cluster of photodiodes (i. e. , a webcam) and hide that in the corner of the screen, but those leave physical evidence... you can see the lense if you take the screen apart. It could be possible, with non-digital interferometry, to construct such an image of the room in real time. .. but that equipment barely fits in the basements of large telescope observatories, and requires cryogenic cooling. You would not be able to collect it clandestinely, and would be much cheaper (and higher quality) to use a webcam.
What Are the Components of LED Display_ Application Method of LED Display Screen
What Are the Components of LED Display_ Application Method of LED Display Screen
What are the components of LED displayLED display is a flat panel display, which is composed of small LED module panels. It is used to display text, image, video, video signal and other information. The components are as follows:1 LED unit board: it is one of the core components of LED display. The quality of the unit board directly affects the display effect of the display screen. The unit board is composed of LED module, driver chip and PCB circuit board. The LED module is actually composed of many LED light emitting points encapsulated in resin or plastic lattice.2 Connection: it can be divided into data line, transmission line and power line. The data cable is a flat cable used to connect the control card and the LED unit board. The transmission line is used to connect the control card and the computer. The power cord is used to connect the power supply, control card and LED unit board. The copper core diameter of the power cord connecting the unit board shall not be less than 1mm.3 Power supply: the power supply generally uses switching power supply, 220V input and 5V DC output. It should be pointed out that because the LED display screen belongs to precision electronic equipment, switching power supply should be used instead of transformer.4 Control card: we recommend using a low-cost strip screen control card, which can control a 1 / 16 scanned 256x16 point two-color screen and assemble the most cost-effective LED screen. The control card belongs to asynchronous card, that is, the card can save information without power off, and the information stored in it can be displayed without connecting to PC.Application method of LED display screenLED display screen can help a unit to show what they want to say and release some announcements and information, so as to facilitate visitors to understand some basic information of the unit.1. First of all, our equipment has been debugged normally. Turn on the power switch first.2. Open the icon on the computer and enter the operation page, as shown in the figure3. Turn on the switch of LED display screen, as shown in the figure4. Turn on the audio5. The following is the renderingsWonderful reading recommendations:Application place of LED display screen_ Development status and trend of LED displayScanning mode and principle of LED display screen_ What does the P of LED display stand forWhat is the power consumption of LED display_ How to connect LED display screen with mobile phoneHow to change words with U disk for LED display screen_ Steps of importing subtitles with U disk for LEDHow long is the service life of LED display_ Six daily maintenance of LED display
What Aspects Should Be Considered When Selecting LED Display Screen
What Aspects Should Be Considered When Selecting LED Display Screen
Indoor LED screen is favored by advertisers in large hotels and supermarkets because of its good display effect and visual feeling. So what should we pay attention to in the selection of LED display in hotel banquet hall?Generally, in the indoor environment, the screen area will exceed 3 m2. Therefore, in this case, there are three options: ordinary rear projection, DLP (digital liquid crystal rear projection) and LED display.The advantages of ordinary rear projection display screen are small pixels and high definition. The disadvantages are low brightness, small viewing angle and short lens lamp life (only a few thousand hours). DLP has the advantages of small pixel points and high definition. The disadvantage is that it has seam. At present, the minimum seam can reach 1mm. Rear projection and plasma display screens are suitable for close viewing. For indoor LED display, the advantages are high brightness and no seam, while the disadvantages are coarse pixel particles and low definition. At present, the economic model of commercialized indoor full-color LED screen is p5p6, and other models include p3p4p7.62p8. LED display screen is suitable for indoor places with long viewing distance.When selecting LED display in banquet hall, the following aspects can be considered:1 die. Like the outdoor full-color LED screen, it is generally recommended that the LED of the indoor full-color display screen adopt the LED encapsulated by Maipu brilliance, and the tube cores of Japan Riya and Cree of the United States are recommended for high-end products.2. Packaging form. The 3528211010 surface mount package has the advantages of large viewing angle, good luminous consistency and easy automatic welding processing. It is the mainstream product of full-color screen.3 density. Due to the large heating capacity of indoor full-color LED chip and high density of control circuit, the point density of commercial full-color screen can not be very high. The screen models in lianchengfa room include p1.6p22.5p3p4p5, P6, p7.62, P8, etc.4. Driving mode. The driving mode of Maipu Guangcai indoor full-color LED screen is constant current driving and adopts dynamic scanning mode (mainly 1 / 4, 1 / 81 / 16 and other scanning modes).5 refresh rate. Improve the refresh rate, and there is no flicker and tailing when shooting with the camera.Other considerations include the scale and brand, price, purpose, installation location and environment of LED display manufacturers. The above are some suggestions on the selection of LED display in hotel banquet hall.fqj
System Design of LED Display Screen
System Design of LED Display Screen
With the rapid development of science and technology, the development of traditional TV, newspaper and magazine media has lagged behind the development of outdoor media. Here we will introduce the system design of dot matrix LED dot matrix display.Composition of LED dot matrix displayComposition of LED dot matrix display: it is a new display device, which is composed of multiple LED's encapsulated together. In order to explain the principle of LED dot matrix display, a display system including hardware and software is designed and manufactured with single chip microcomputer as the control core. The circuit can realize various display forms such as rolling shutter, moving up and moving left of any number of Chinese characters through key control. It can be widely used in public places such as airports, shopping malls and hospitals for text advertising and information release. Moreover, it has the characteristics of small volume, simple circuit structure and easy implementation.LED dot matrix displaySystem hardware circuitThe hardware circuit of the display controller is mainly composed of three parts: serial communication interface, expansion of external memory, LED dot matrix display driver and interface circuit. Generally speaking, there are many contents to be displayed, so the external data memory must be expanded. Static data memory has the advantages of low cost, low power consumption and fast reading and writing speed. We use two pieces of static ram62256 data memory (64KB in total). Store all the content codes to be displayed in 62256.System software programSoftware program is the core of the whole control system. After the system main program starts, the system environment is initialized first, including setting serial port, timer, interrupt and port. The whole software design is mainly divided into two parts: display part and communication part.Communication part: the upper computer software adopts visual basic programming, and VB is used to provide a powerful communication control MSComm, which controls the message format and protocol setting of serial port and serial port communication, and directly uses the serial port of PC to send data. In order to realize the reliable communication between MCU and PC, both sides must have the same data format and baud rate. The use of the software is relatively simple. When using, you can use Microsoft Word to handle the content to be displayed (note that the width of the page setting should be the same as that of the LED dot matrix display), then select the select all command and copy command in the edit menu, and then run the LED display Download Software v1.1. Select the "clipboard" button in the interface, and the content to be downloaded can be displayed in the preview box, After checking, select the baud rate and connect to the serial port, click the "download" button, and you can download the display. Repeat the above operation when you need to modify or display new content. It is very convenient to use.Display part: use dynamic scanning to realize the control and display functions of Chinese characters, characters, images and data transmission on the display screen. The program divides the data memory into three areas: display buffer, data storage area and receiving buffer. The single chip microcomputer receives the data from the PC through the serial port interrupt, temporarily stores it in the receiving buffer, analyzes and processes it, saves it in the data storage area according to certain rules, and then extracts the data from the data in the memory according to the display mode sequence to display it in the display buffer. The display adopts progressive scanning. The real-time communication part of PC mainly uses the MCU serial port to interrupt the reception of data information and realize the data information transmission with the computer.
Composition and Working Principle of LED Display Screen
Composition and Working Principle of LED Display Screen
In this paper, LED display screen is composed of several display units (unit display board or unit display box) that can be combined and spliced, plus a set of appropriate controller (main control board or control system). Therefore, a variety of display boards (or unit boxes) with different control technologies can form many kinds of LED displays to meet the needs of different environments and display requirements.1 Main composition of LED display screen (taking the more complex synchronous full-color screen as an example)1. The metal structure frame is used to form an inner frame and carry various circuit boards such as display unit board or module and switching power supply2. Display unit: it is the main part of LED display screen, which is composed of LED lamp and driving circuit. The indoor screen is the unit display board of various specifications, and the outdoor screen is the module box.3. Scanning control board: the function of the circuit board is data buffer to generate various scanning signals and duty cycle gray control signals.4. Switching power supply: change 220V AC into various DC to supply various circuits.5. Transmission cable: the display data and various control signals generated by the main controller are transmitted to the screen body by twisted pair cable.6. Main controller: buffer the input RGB digital video signal, transform the gray level, reorganize it, and generate various control signals.7. Special display card and multimedia card: in addition to the basic functions of computer display card, it also outputs digital RGB signals and line, field, blanking and other signals to the main controller. In addition to the above functions, multimedia can also change the input analog video signal into digital RGB signal (i.e. video acquisition).8. Computer and its peripheralsFigure 1 LED display system composition2 Analysis of main functional modules1. Video broadcastThrough multimedia video control technology and VGA synchronization technology, various forms of video information sources can be easily introduced into the computer network system, such as radio and satellite TV signals, camera video signals, VCD video signals of video recorders, computer animation information, etc. Therefore, the following functions can be realized:Support VGA display and display various computer information, graphics and images.Support various input modes; Support pal, NTSC and other systems.Display color video images in real time to realize on-site broadcasting.Broadcast radio and television, satellite television and cable television signals.Real time playback of video signals such as TV, camera and video disc (VCR, VCD, DVD and LD).It has the function of playing pictures and words with different proportions on the left and right at the same time2. Computer broadcastGraphic stunt display function: it has the functions of editing, zooming, flowing and animation.Display various computer information, graphics, images and 2D and 3D computer animation and overlay text.The broadcasting system is equipped with multimedia software, which can flexibly input and broadcast a variety of information.There are a variety of Chinese fonts and fonts to choose from. At the same time, you can also input English, Spanish, French, German, Greek, Russian, Japanese and other languages.There are many broadcast modes, such as single / multiple line translation, single / multiple line up / down, left / right pull, up / down, rotation, stepless zoom, etc.Editing, broadcasting and instant release of notices, announcements, announcements and news, and there are a variety of fonts to choose from.3. Network functionEquipped with standard network interface, it can be connected with other standard networks (information query system, Municipal Publicity network system, etc.).Collect and broadcast real-time data of each database to realize remote network control.You can access the Internet through the network systemIt has a sound interface, which can be connected to audio equipment to achieve audio-visual synchronization.4. Screen controllerThe screen controller controls the display effect of its corresponding display screen. It can automatically run a continuous cycle program to obtain relevant display data according to the given program list, or it can intervene manually to produce the display effect on the screen. The pixels on the screen are directly mapped with the pixels on the corresponding area of the screen controller display.The screen controller can manually adjust the brightness of the display screen and select the gray nonlinear correction data suitable for the current environment. The screen controller can also automatically adjust the brightness of the display screen and select different gray nonlinear correction data according to the ambient brightness through the network system.The contrast and chroma of image display can be adjusted through the screen control machine. The screen controller transmits the information to be displayed to the video processing and control unit for video processing.5. Video processing and control unitThe video processing and control unit completes the image processing of the display data, including:The second level of gray nonlinear correction can be adjusted automatically or manually.Automatic or manual stepless brightness adjustment.The gray level control system can control the display screen to display 24 bit data of 8 bits of each primary color, that is, 256 gray levels of each primary color.Image noise reduction processing to ensure that the image is cleaner and smoother.Image enhancement technology, image edge enhancement technology.Motion compensation technology, chroma adjustment function.6. Visual processingIn the system, the brightness of each primary color of a single module can be adjusted respectively, the color balance can be adjusted, and the mosaic phenomenon can be basically eliminated. The brightness consistency of all modules and display modules is good, and the monochrome display has no visual difference.The video processing and control unit transmits the processed display information to the communication module for long-distance transmission to the display screen.7. Communication moduleThe communication module ensures that the display content of the screen control machine is accurately transmitted to the display screen for a long distance. The communication module encodes and decodes the transmitted information, and processes the long-distance transmission and reception data. The communication module transmits the display information to the data distribution and scanning unit.The LED display screen is usually composed of the main controller, the scanning board, the display control unit and the LED display screen body. The main controller obtains the color brightness data of each pixel of a screen from the computer display card, and then assigns it to several scanning boards. Each scanning board is responsible for controlling the dry lines (columns) on the LED display screen, and each line (column) The LED display signal on the is transmitted in series through each display control unit of the bank, and each display control unit directly faces the LED display body. The work of the main controller is to convert the signal of the computer display card into the data and control signal format required by the LED display screen. The function of display control unit operation is similar to that of image display screen. It is generally composed of shift register latch with gray level control function. However, the scale of video LED display is often larger, so we should use integrated circuits with larger integration scale. The function of the scanning plate is the so-called connecting link. On the one hand, it receives the video signal of the main controller, on the other hand, it transmits the data belonging to the current level to its own display control units, and also transmits the data not belonging to the current level to the next cascade scanning plate. The differences between video signals and LED display data in space, time, sequence and other aspects need to be coordinated by a scanning board.
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