How to Distinguish Between LED Display Screen and SMD Conventional Screen

LED display is a flat panel display, which is composed of small LED module panels. It is used to display text, image, video and other information. LED electronic display screen integrates microelectronics technology, computer technology and information processing. It has the advantages of bright color, wide dynamic range, high brightness, long service life, stable and reliable operation and so on. LED display screen is widely used in commercial media, cultural performance market, stadiums, information dissemination, news release, securities trading, etc., which can meet the needs of different environments. Nowadays, with the continuous development of market economy, there are many high-rise buildings in cities, and transparent LED display screen has been widely used in the fields of urban glass curtain wall landscape lighting, architectural art beauty improvement and so on. Many customers are very unfamiliar with the term transparent LED display screen. What is the difference between transparent LED display screen and SMD conventional screen?

How to Distinguish Between LED Display Screen and SMD Conventional Screen 1

High transmittance, does not affect indoor lighting, cool displayAs we all know, SMD conventional display screen is opaque and will affect the daylighting of buildings. The herno led transparent screen adopts the self-developed side light-emitting display technology. The light bar is almost invisible to the naked eye from the front, which greatly improves the permeability, and supports machine pasting, with higher production efficiency.Lightweight design to save steel structure cost

SMD conventional display screen is 42kg per square meter. When the screen area is too large, it is a great challenge to the screen steel structure and the original building structure. The LED transparent screen can be installed vertically and independently without glass. If it is installed behind the glass curtain wall, it can be directly attached to the steel structure of the curtain wall. Its extremely light weight of 16KG / has very low load demand for the steel structure.Easy maintenance, support hot plug, light bar maintenanceMost of the problems of SMD conventional screen are post maintenance, or the whole module or box is disassembled for maintenance. The transparent LED display only needs to replace one light bar during maintenance, which is simple and fast to operate and reduce the maintenance cost.

For outdoor screen application, indoor installation and outdoor viewingSMD conventional display screen is installed indoors, which will block the sun and line of sight. Led transparent screen for outdoor screen application, indoor installation, outdoor viewing, do not worry about waterproof and UV protection, and the product performance is very stable.Perfectly matched with the glass curtain wall, hidden installation, does not affect the building shape

SMD conventional screen needs large-scale steel frame structure during construction, which is time-consuming and laborious, and has a certain impact on the building shape and aesthetics. When the LED transparent screen is installed and used, it can be easily and perfectly combined with the wall with a small amount of construction, without damage to the wall, and can also improve its overall appearance.Strip lamp strip structure, special-shaped designWhen making special-shaped products for SMD conventional display screen, it will be limited by its box structure. There are some defects in splicing special-shaped products, and there will be splicing seams. Herno special-shaped led transparent screen can be customized, spliced perfectly, and the curved surface transition is natural and beautiful. The product screen can be set into various special-shaped shapes such as cylinder, round platform, triangle, arc and so on.

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Analysis of Some Professional Terms About LED Display Screen
Analysis of Some Professional Terms About LED Display Screen
With the rapid development of LED display technology, it has been widely used in all walks of life. However, for novices, many professional terms of LED display are unknown. What are the common professional terms of LED display?1. LED brightness: the brightness of LED is generally expressed by luminous intensity, and the unit is candela CD; 1000ucd (micro candela) = 1mcd (millicandela), 1000mcd = 1CD. The light intensity of a single LED for indoor use is generally 500ucd-50mcd, while the light intensity of a single LED for outdoor use is generally 100mcd-1000mcd, or even more than 1000mcd.2. LED pixel module: the LEDs are arranged into a matrix or pen segment and prefabricated into a module of standard size. 8 * 8 pixel module and 8-character 7-segment digital module are commonly used for indoor display screen. The outdoor display pixel module has 4 * 4, 8 * 8, 8 * 16 pixels and other specifications. The pixel module for outdoor display screen is also called collecting tube bundle module because each pixel is composed of more than two LED tube bundles.3. Pixel and pixel diameter: each LED light emitting unit (point) in the LED display screen that can be controlled separately is called pixel (or pixel). Pixel diameter refers to the diameter of each pixel, in millimeters.4. Resolution: the number of rows and columns of LED display pixels is called the resolution of LED display. Resolution is the total number of pixels of a display screen, which determines the information capacity of a display screen.5. Grayscale: grayscale refers to the degree of light and shade change of pixels. The grayscale of a primary color generally has 8 to 12 levels. For example, if the gray level of each primary color is 256, the display color of the dual primary color screen is 256? 256 = 64K color, also known as 256 color display screen.6. Dual primary color: Nowadays, most color LED displays are dual primary color screens, that is, each pixel has two LED tube cores: one is red tube core and the other is green tube core. When the red light tube core is on, the pixel is red, when the green light tube core is on, the pixel is green, and when the red and green tube cores are on at the same time, the pixel is yellow. Red and green are called primary colors.7. Full color: red green double primary color plus blue primary color, three primary colors constitute full color. Because the technology of forming full-color blue tube and pure green tube core is now mature, full-color is basically used in the market.
What Are the OLED Display Phones? Analysis of Advantages and Disadvantages of OLED Display Screen
What Are the OLED Display Phones? Analysis of Advantages and Disadvantages of OLED Display Screen
OLED is also known as electromechanical laser display and organic light-emitting semiconductor. It was discovered in the laboratory by Chinese American Professor Deng Qingyun in 1979. OLED display technology has the advantages of self illumination, wide viewing angle, almost infinite high contrast, low power consumption, high reaction speed and so on. However, as a high-end display, the price will be more expensive than LCD TV. So what are the mobile phones with OLED screen? What are the advantages and disadvantages of OLED display? Let's make a simple analysis.What are the OLED screen phones?Since OLED technology is mainly developed and produced by Samsung, most mobile phones equipped with OLED screens are also Samsung mobile phones. However, in recent years, other mobile phone manufacturers have adopted OLED screens to make mobile phones, as follows:Samsung Galaxy s65.1-inch 2ksuperamoled, reference price 4488 yuanSamsung Galaxy s6edge 5.1-inch 2ksuperamoled, reference price 5288 yuanXiaomi Note2 5.7-inch 1080p OLED, the current reference price is 2799 yuanJinli M6 Plus6.0 inch super large AMOLED, with the current reference price of 2999 yuanAdvantages of OLED display:1. Thinner, the OLED thickness can be less than 1mm, only 1 / 3 of the LCD screen, and the weight is lighter; This is very important for mobile phone design.2. Solid state mechanism, no liquid material, so the seismic performance is better. Lower power consumption. Similarly, white background OLEDs have no advantages over LCD, and black background has obvious advantages. Because of ultra-high contrast, the visual perception brightness is higher under the same brightness, which helps to reduce power consumption.3. Simple manufacturing process and lower cost;4. Higher luminous efficiency and lower energy consumption than LCD;5. It can be manufactured on substrates of different materials and can be made into flexible displays;6. The response time is one thousandth of that of LCD, and the moving picture will never be dragged.Defect analysis of OLED display:1. The service life is usually only 5000 hours, which is at least 10000 hours lower than that of LCD;2. It can not realize mass production of large-size screen, so it is only suitable for portable digital products at present;3. There is a problem of insufficient color purity, which is not easy to show bright and rich colors.The above is all the news about OLED display carefully sorted out by Xiaobian. I hope it can be a reference for you.
Analysis of Various Process Problems of High Density LED Display Screen
Analysis of Various Process Problems of High Density LED Display Screen
With the rapid progress of LED display technology, the dot spacing of LED display screen is becoming smaller and smaller. Now the market has launched P1.4 and P1.2 high-density LED display screens, and began to be applied in the field of command and control and video monitoring.In the indoor monitoring large screen market, DLP splicing and LCD splicing, two display technologies, take the lead in the market. Although they have their own advantages, they all have a common problem, that is, the splicing between display units. High density LED display has inherent advantages and can realize seamless splicing. The pixels of high-density display screen are smaller and smaller, the resolution is higher and higher, and the display screen is clearer and more delicate. When displaying standard high-definition images, it can fully meet the requirements of resolution. If the price of high-density lamp is getting lower and lower, it is bound that high-density LED display will occupy a larger market in the field of indoor video monitoring.High density LED display has the characteristics of high-definition display, high refresh frequency, seamless splicing, good heat dissipation system, convenient and flexible disassembly and assembly, etc. With the smaller and smaller pixel spacing, higher and higher requirements are put forward for the mounting, assembly, splicing process and structure of LED. In this paper, some technological problems are discussed.1. Led selection: 1515, 2020 and 3528 lamps are generally used for display screens with density above P2, and the LED pin shape adopts J or l packaging. When welding pins laterally, there will be reflection in the welding area, and the ink effect is poor. It is bound to need to increase the mask to improve the contrast. The density is further improved. The packaging of L or J can not meet the minimum electrical performance spacing requirements, so QFN packaging must be adopted. Guoxing's 1010 and crystal platform's 0505 adopt this package.The unique QFN packaging welding process is unique. This process is characterized by no lateral welding pins and no reflection in the welding area, which makes the color rendering effect very good. In addition, all black integrated design molding is adopted, and the picture contrast is increased by 50%. The picture quality effect of display application is better than that of previous display screens.2. Process selection of printed circuit board: with the trend of high density, 4-layer and 6-layer boards are adopted. The printed circuit board will adopt micro via and buried hole design. The printed circuit graphic wires are thin, microporous and narrow spacing. The mechanical drilling process technology used in processing can no longer meet the requirements. The rapid development of laser drilling technology will meet the needs of micro hole processing.3. Printing technology: too much or too little solder paste and printing offset directly affect the welding quality of high-density display lamp tube. The correct PCB pad design needs to be implemented in the design after communication with the manufacturer. The opening size of the screen plate and whether the printing parameters are correct or not are directly related to the amount of solder paste printed. Generally, 0.1-0.12mm thick electropolished laser steel mesh is used for 2020rgb devices, and 1.0-0.8 thick steel mesh is recommended for devices below 1010rgb. The thickness and opening size increase in proportion to the amount of tin. The welding quality of high-density LED is closely related to solder paste printing. The use of printing machine with functions such as thickness detection and SPC analysis will play an important role in reliability.4. Mounting technology: the slight deviation of the position of each RGB device of the high-density display screen will lead to uneven display of the screen, which will inevitably require the mounting equipment to have higher precision. The mounting accuracy (QFN 0.03mm) of Panasonic NPM equipment will meet the mounting requirements above P1.0.5. Welding process: too fast temperature rise of reflow welding will lead to uneven wetting, which is bound to lead to offset of devices in the process of unbalanced wetting. Excessive wind circulation will also cause displacement of the device. Try to select reflow soldering machine above 12 temperature zone, chain speed, temperature rise, circulating wind force, etc. as strict control items, that is, to meet the requirements of welding reliability, reduce or avoid device displacement, and try to control it within the required range. Generally, the range of 2% of the pixel spacing is used as the control value.6. Box assembly: the box is spliced with different modules. The flatness of the box and the gap between modules are directly related to the overall effect after box assembly. Aluminum plate processing box and cast aluminum box are widely used box types at present, and the flatness can reach within 10 wires. The splicing gap between modules is evaluated based on the distance between the nearest pixels of the two modules. If the two pixels are too close, there will be a bright line when lit, and if the two pixels are too far away, there will be a dark line. Before assembly, it is necessary to measure and calculate the module joint, and then select the metal sheet with relative thickness as the fixture to be inserted in advance for assembly.7. Screen assembly: the assembled box needs to be assembled into a screen before fine pictures and videos can be displayed. However, the dimensional tolerance of the box itself and the cumulative assembly tolerance can not be ignored for the assembly effect of high-density display screen. The pixel spacing of the nearest device between the box and the box is too large or too small, which will lead to the display of dark lines and bright lines. The problem of dark line and bright line is a difficult problem that can not be ignored and needs to be solved urgently. Some companies adjust by sticking 3M adhesive tape and fine adjusting nuts on the box to achieve the best effect.8. System card selection: the light and dark lines, uniformity and color difference of high-density display screen are the accumulated criticism of LED device difference, IC current difference, circuit design layout difference and assembly difference. Some system card companies can reduce the light and dark lines, brightness and chromaticity imbalance through software correction. Novartis introduced brightness and chroma correction system, which has been applied to various high-density displays and achieved good display results.
What Is the Seamless Splicing Technology of LED Display Screen and How to Realize It
What Is the Seamless Splicing Technology of LED Display Screen and How to Realize It
At this stage, as China's monitoring technology level and data collection capacity have been improved to a certain extent, whether the display terminal can accurately present the collected data on the display wall in time is very important, which is directly related to the rationality of the decision-making of the superior department. In order to meet the needs of the market, the technicians of the display terminal improved the existing technology and made it develop towards seamless and high-definition. Then, the seamless high-definition LED display came into being.Seamless stitching technology is a special and demanding projection display application, which can realize the fusion of multi screen images and minimize the stitching gap so that it is completely coincident. Seamless splicing technology not only needs a complete ultra large screen, but also has special requirements for the projection used to project ultra large pictures. The biggest difference between seamless splicing technology and BSV liquid crystal splicing technology is that the gap is small.Solve the visual defect that the spliced picture is segmentedThroughout the current large screen splicing system in China, there are still many splicing seams in many display screens. For example, the gap of LCD splicing system is too large to meet the needs of users; Compared with liquid splicing technology, plasma and back projection large screen splicing system has more advantages, but there are still a large number of segmentation lines from its visual effect. Even the application of LCD, DLP and PDP technology in engineering can only reduce the gap, but can not completely eliminate it. Seamless led splicing technology can completely solve the problem of screen segmentation and meet the requirements of complete seamless.The seamless led splicing technology can improve the screen resolution in a small area, ensure the texture of the picture and meet the needs of users for close viewing. Compared with the existing splicing technology, the physical seamless splicing of LED can realize cross screen display. For butt joints, the level is not the size of the gap, but whether the gap exists.Solve the inconsistency between brightness and chroma attenuation of spliced large screenThe application of seamless LED technology will effectively deal with the different brightness and chroma attenuation of the spliced large screen. In this technology, point by point brightness and chroma correction technology is generally adopted, which ensures the unity of brightness and chroma. For example, the application of point control technology creates a platform for users to correct chromaticity and brightness point by point, and controls the pixels of the screen to realize the height restoration of the image. This technology also has the functions of SMS and e-mail prompt, which can enable users to grasp the status information of the splicing wall in time.Intensive display and control platformSeamless LED technology applies an intensive display and control platform to ensure the reliability of monitoring video sources, create a management platform for customers, effectively realize the management of video signals, computer signals and network signals, and provide better services for users.Powerful redundant backup design of power supply and signalIn the design of seamless led system, the redundancy of power supply and signal is backed up, which can reduce the problems in its use.Long service life, simple maintenance and low costCompared with the general display screen, the service life of LED is longer, and its maintenance and repair costs are relatively low.Ultra large angle, ultra-high contrast, ultra-high refresh rateThe project provides a large viewing angle and prevents the occurrence of reflection. When capturing the picture, the state is relatively stable. In response to the dynamic display picture, the image edge is clear and has good dynamic expressiveness, so as to restore the image information accurately and truly. Make the video picture delicate and smooth, and bring the greatest visual enjoyment. In addition, it is specially pointed out that the brightness uniformity of LED screen is excellent. With the single point brightness correction, the brightness uniformity of the whole screen tends to the extreme.To sum up, seamless splicing technology is another great leap forward in the LED display industry. It comprehensively solves the seamless splicing defects that can not be completed by other display equipment. At the same time, it can also achieve the characteristics of energy conservation and environmental protection, intensive display and increasing service life. It is an indispensable technology in the LED industry.
The Optimization of Dot Spacing of LED Display Screen Makes the Display of Products More and More De
The Optimization of Dot Spacing of LED Display Screen Makes the Display of Products More and More De
The continuous miniaturization of the dot spacing of LED display screen makes the picture of its display products clearer and clearer, and the color more and more delicate and soft. However, since last year, the exhibition has no longer displayed LED lamps below smd1010, which means that the small spacing of LED has reached an extraordinary period, and the realization of smaller spacing is difficult to realize SMD packaging technology. So in order to make the spacing smaller, cob small spacing came.The development time of cob small spacing is not long, but it has also accumulated 4-5 years of development experience. Compared with SMD packaging technology, cob technology still needs to improve some contents. However, it is certain that cob small spacing has more advantages in protection, display, service life and product reliability than led small spacing in SMD packaging.In addition, at present, the cob packaging process is still in the improvement stage, so there are not many cob small spacing manufacturers in China. Because the entry threshold of cob display screen is high, the technical requirements are high, and it is difficult for enterprises to transform from the original SMD packaging production process.The price of cob small spacing products is not beautiful because there are few manufacturers of cob display screens. However, the high price of cob small spacing products is not because they are rare, but because in the current R & D process, the R & D cost is too high, the product yield and the success rate of one-time packaging are not good-looking. In the production control cost, the spiritual strength and economy need to be invested are high, This is also the reason why cob displays are expensive.There are few cob small spacing manufacturers. Shenzhen Dayuan is one of the cob small spacing manufacturers. If you have any questions about them, you can contact them to get the information you want to know.fqj
Harmonic Control Scheme of LED Display Screen
Harmonic Control Scheme of LED Display Screen
Due to the large number of LED display screens installed, a large number of harmonics are generated in the display screen, which leads to zero line overheating, tripping and other faults. So what is the harmonic control scheme and method of LED display screen?Harmonic problem of LED display screen - excessive zero line currentIn fact, not only the LED display screen will have this problem, but also some advertising light boxes using electronic ballasts will have similar problems. The reason for this problem is that the power supply of LED display screen is switching power supply. The input of switching power supply is rectifier circuit, so it is a typical harmonic source. The harmonic current of single-phase bridge rectifier circuit has 3 times, 5 times, 7 times and 9 times. The 3rd harmonic current is arithmetically superimposed on the zero line, and the effective value is 1.73 times of the phase line current. Since the cross-sectional area of the zero line is the same as that of the phase line during wiring, when the phase line reaches the rated current, the current on the zero line will exceed the rated current, resulting in overheating of the zero line.It should be noted that when AC current flows on a conductor, there is a physical phenomenon called skin effect, or skin effect. The skin effect means that the AC current is not evenly distributed in the conductor, but concentrated on the conductor surface. The higher the frequency of AC, the more significant this effect is. The current concentration near the surface means that the actual cross-sectional area of the conductor is reduced. Therefore, when the third harmonic current flows through the zero line, the zero line presents a greater resistance to the third harmonic current.The AC resistance is directly proportional to the square root of the frequency. Therefore, the resistance of a conductor to the third harmonic current is 1.7 times that of the fundamental current. According to the calculation of power P = I2R, the calorific value of the third harmonic current with the same amplitude is 1.7 times that of the fundamental current. This exacerbates the overheating of the zero line.We know that when the current flows through the conductor, it will cause the conductor to heat. The heat is directly proportional to the resistance of the conductor and the square of the current flowing through the conductor. Therefore, if the cross-sectional area of the zero line is the same as that of the phase line, when the zero line current reaches twice the phase line current, the calorific value of the zero line is 4 times that of the phase line. If the cross-sectional area of the zero line is 1 / 3 of the phase line and the resistance of the zero line is 3 times that of the phase line, when the zero line current reaches 2 times that of the phase line, the heating capacity of the zero line is 12 times that of the phase line!Through the above analysis, we know that when the current on the zero line exceeds the phase line current, it will inevitably lead to overheating of the zero line, which may lead to fire. Excessive zero line current is a serious fire hazard, because there is no overcurrent protection device on the zero line, unlike safety devices on the phase line. When the current is too large, cut off the current. When the current is too large, it can only allow its temperature to rise, accelerate cable aging, and even cause fire.
Analysis of Various Technologies of Micro Spacing LED Display Screen
Analysis of Various Technologies of Micro Spacing LED Display Screen
With the continuous development of market economy, people's demand for LED display screen is also growing. LED display has a development history of decades in China. Our technology in this industry has made great progress, which is almost the same as the world-class level. In some fields, we even overtake in corners, surpassing foreign technology. Micro spacing display technology is one of the representatives.With the rapid progress and maturity of LED display technology and the improvement of customer requirements, the point spacing of micro spacing LED display screen is becoming smaller and smaller, and is widely used in video conference, command and dispatching center, security monitoring center, radio and television media and other fields. The characteristics of micro pitch LED display, such as high-definition display, high refresh rate, seamless splicing, good heat dissipation system, convenient and flexible disassembly, energy conservation and environmental protection, have been well known by users in the industry. However, when it comes to the specific process technology of micro pitch LED display, many people still don't know. The following is a brief analysis of various process technologies of micro pitch LED display, Let us have a more thorough understanding of micro spacing LED display.1 Packaging technology: 1515, 2020 and 3528 light beads are generally used for LED display with density above P2, and the shape of LED pin adopts J or l packaging. When welding pins laterally, there will be reflection in the welding area, and the ink effect is poor. It is bound to need to increase the mask to improve the contrast. If the density is further improved, l or j packaging can not meet the application requirements, and QFN packaging must be adopted. This process is characterized by no lateral welding pins and no reflection in the welding area, so that the color rendering effect is very good. In addition, all black integrated design molding is adopted, and the picture contrast is increased by 50%. The picture quality effect of display application is better than that of previous display screens.2 Welding process: too fast temperature rise of reflow welding will lead to uneven wetting, which is bound to lead to offset of devices in the process of unbalanced wetting. Excessive wind circulation will also cause displacement of the device. Try to select reflow soldering machine above 12 temperature zone, chain speed, temperature rise, circulating wind force, etc. as strict control items, that is, to meet the requirements of welding reliability, reduce or avoid device displacement, and try to control it within the required range. Generally, the range of 2% of the pixel spacing is used as the control value.3 Box assembly: the box is spliced with different modules. The flatness of the box and the gap between modules are directly related to the overall effect after box assembly. Aluminum plate processing box and die-casting aluminum box are widely used box types at present, and the flatness can reach within 10 wires. The splicing gap between modules is evaluated according to the distance between the nearest pixels of the two modules. If the two pixels are too close, there will be a bright line when lit, and if the two pixels are too far away, there will be a dark line. Before assembly, it is necessary to measure and calculate the module joint, and then select the metal sheet with relative thickness as the fixture to be inserted in advance for assembly.4 Screen assembly: the assembled box needs to be assembled into a screen before fine pictures and videos can be displayed. However, the dimensional tolerance of the box itself and the cumulative assembly tolerance can not be ignored. The pixel spacing of the nearest device between the box and the box is too large or too small, which will lead to the display of dark lines and bright lines. The problem of dark line and bright line is a difficult problem that can not be ignored and needs to be overcome. Some companies adjust by sticking 3M adhesive tape and fine adjusting nuts on the box to achieve the best effect.5 Printed circuit board technology: with the development trend of micro spacing LED display screen, 4-layer and 6-layer boards are adopted. The printed circuit board will adopt micro via and buried hole design. The printed circuit graphic wires are thin, microporous and narrow spacing. The mechanical drilling technology used in processing can no longer meet the requirements. The rapidly developed laser drilling technology will meet the requirements of micro pore processing.6 Printing technology: too much or too little solder paste and printing offset directly affect the welding quality of micro spacing LED display tubes. The correct PCB pad design needs to be implemented in the design after communication with the manufacturer. The opening size of the screen plate and whether the printing parameters are correct or not are directly related to the amount of solder paste printed. Generally, 0.1-0.12mm thick electropolished laser steel mesh is used for 2020rgb devices, and 1.0-0.8 thick steel mesh is recommended for devices below 1010rgb. The thickness and opening size increase in proportion to the amount of tin. The welding quality of micro spacing LED is closely related to solder paste printing. The use of printing machine with functions such as thickness detection and SPC analysis will play an important role in reliability.7 Mounting technology: the slight deviation of RGB device position of micro spacing LED display screen will lead to uneven display of the screen, which is bound to require the mounting equipment to have higher precision.8 System card selection: the light and dark lines, uniformity and color difference of micro spacing LED display screen are the accumulated criticism of LED device differences, IC current differences, circuit design layout differences and assembly differences. Some system card companies can reduce the light and dark lines, brightness and chromaticity unevenness through software correction.
Point by Point Correction Technology of LED Display Screen
Point by Point Correction Technology of LED Display Screen
1 Concept of point by point correction technologyStarting from the last process of display manufacturing, this problem is solved by using differential driving for differential LED light points, which is point by point correction.In the late 1990s, the theoretical prototype of point by point correction appeared at home and abroad, and the practical exploration of this technology was started. However, due to the lack of applicable general data acquisition tools and technical barriers, the research of this technology has been discontinuous and unsystematic for a long time, lack of communication, and lack of a recognized definition of point-to-point correction.At present, the more reasonable definition is: point by point correction, that is, the correction coefficient (or coefficient matrix for each pixel) for each light point is obtained by collecting the brightness (and chroma) data of each light point area on the LED screen, which is fed back to the control system of the display screen, and the control system uses the correction coefficient to realize the differential driving of each light point, Thus, the pixel brightness (chroma) uniformity of the display screen is greatly improved.2 Composition of point by point correction technologyAs can be seen from the above definition, the point by point correction technology can be divided into the following four parts:1. Original data collection;2. Generation of correction data;3. Drive control;4. Combination of acquisition system and control system;These four aspects are analyzed and described below.2.1 original data acquisitionRaw data acquisition is the first step of point-by-point correction, the most basic step, and the slowest and most difficult step of development. According to the acquisition parameters, it can be divided into brightness data and chroma data; According to the acquisition object, it can be divided into module level acquisition, box level acquisition and full screen sub area acquisition; According to the acquisition environment, it can be divided into factory mode acquisition and field mode acquisition; From the perspective of the technical route and tools of collection, it can be roughly divided into the following directions:1. Mechanical device photometric probe: that is, use the mechanical transmission device to control the photometric probe to collect the number of each light point one by one. The early experimental device used to place the screen perpendicular to the ground and measure it point by point with a frame moving luminance meter with equal spacing. Later, it gradually developed into a machine form, with modules or unit boards placed horizontally and probes collecting data vertically. In order to improve efficiency, a single machine can be equipped with multiple probes. The author has seen that the maximum number of probes in a single machine is 16, which is collected in the unit of box.The advantage of this acquisition method is high precision, but it also has a fatal defect: low efficiency. It is difficult to realize large-scale industrial application. In addition, field correction cannot be achieved. In recent years, with the progress of technology, this desktop acquisition method is gradually fading out of the historical stage.2. Digital camera: it is the cheapest acquisition solution to realize point by point correction by using the imaging gray data of light points by digital camera. Since 2008, several major display control system manufacturers have invested heavily in R & D, developed their own camera acquisition system and carried out the practice of point-to-point correction, which has greatly promoted the promotion and popularization of point-to-point correction technology.The advantage of digital camera scheme is that the equipment is relatively cheap, but the disadvantage is that the accuracy is low, the stability is poor, and the consistency between individuals is also very different, which is difficult to meet the needs of large-scale industrial production. In addition, most digital camera schemes are independently developed by control system manufacturers combined with their own systems, which are incompatible with each other.3. CCD based plane luminance / chroma distribution measuring instrument: with the rapid growth of the global flat panel display industry, the R & D of this kind of instrument can efficiently obtain the luminance / chroma value of any area on the imaging plane by using the imaging luminance measurement principle. Since 2006, relevant products have been produced in Japan, the United States, Denmark, France, Germany and China, but few can meet the special requirements of LED point by point correction.This kind of equipment has high precision, good stability and good correction effect, but the price is relatively expensive.4. Industrial CCD acquisition scheme: in addition to the above directions, there are some solutions based on industrial cameras, such as the industrial camera module correction pipeline scheme developed by Barco company; Another example is Changchun Sida, the pioneer of point by point correction. Their independently developed and continuously improved industrial CCD correction scheme is the first bright color integrated correction solution in China.Sharp tools make good work. With the improvement of the efficiency and function of the acquisition tools, the data acquisition of point-to-point correction has a wider space and possibility, extending from the factory to the site, from the new screen to the old screen, from the plane screen to the arc screen and even the special-shaped screen.2.2 generation of correction dataThe generation of correction data can be divided into three parts: the first is the correction processing of original data, the second is the setting of correction target value, and the third is the calculation and generation of correction data. The most important technical breakthrough is the "original data correction processing", especially the data correction in the field correction environment.2.2.1 original data correction processingThe simplest case of on-site correction is: flat screen, select the best audience area of the display screen as a single data acquisition stand, and carry out data acquisition in turn in different areas of the full screen. The data collected in this way must have systematic errors caused by different observation angles. The collected data shows that the brightness in the vertical normal direction is high, the brightness deviates from the normal direction decreases, and the greater the deviation angle is, the lower the brightness is. If it is not corrected, the corrected display screen will be dark at the lower part and bright at the upper part; The vertical direction of the stand is dark and both sides are bright; Distortion of light and shade occurs when viewing away from the correction point.When the screen body is an outer arc or the field environment is limited, and the acquisition can be completed only by multiple positions, due to the different acquisition angles of different positions, if it is not corrected, there will be an obvious boundary at the joint.The above problems make many screens unable to be corrected on site. Recently, some digital camera schemes adopt the method of adjacent area contrast feedback, and some equipment adopt the method of shooting full screen images as reference for correction.2.2.2 setting of correction target valueThe setting of correction target value is also a part of point by point correction technology worthy of further discussion. As we all know, brightness correction loses brightness, and chroma correction will lose both brightness and gamut space and color saturation. So how to set a reasonable correction target brightness and chroma value, combined with customer needs, and find the best balance between brightness, color gamut and uniformity?At present, due to the lack of intermediate data, many digital camera correction schemes put the setting link of target value before acquisition. However, different display screens have different optimal balance points, especially chromaticity correction. The unreasonable setting of target value will directly lead to the failure of correction! Reasonable target value setting depends on the statistical analysis of collected data. Therefore, we set the target value after the collection is completed, and provide various auxiliary parameters and graphs to help users adjust the target value.2.3 drive controlWith the correction data, it also needs the correct application of the control system to realize point by point correction.There are two ways to realize drive control: one is current amplitude control, the other is pulse width control (PWM mode). Because the current amplitude and brightness are not strictly linear, and the increase or decrease of current will cause the offset of the main wavelength of LED chip, current control is less and less applied. At present, the main way to realize point-by-point correction drive control is to adjust the pulse width.Major domestic control system suppliers have already realized the point-to-point differential driving control of LED light points, but due to the lack of general acquisition equipment, point-to-point correction is still the unique technical advantage of a few industry leaders with their own control systems until 2008. With the breakthrough progress of acquisition equipment, most of them remained in the publicity selling points in 2008, and the point-to-point correction function of the control system that can not be applied has gradually become a necessary weapon for the control system to enter the market by 2010. Today, few full-color display control systems on the market do not have the ability of brightness point by point correction.However, the driving control of point by point correction still needs to be improved, which is reflected in the following aspects:1. The corrected low brightness and linearity need to be improved;2. At present, there are few systems with chromaticity correction function;3. The number of load points needs to be expanded after correction;In addition, in addition to using the control system to realize drive control, another technical idea is to realize correction from the level of signal source through real-time processing of front-end video stream. It can be divided into hardware implementation and software implementation. The hardware implementation is to add a signal processor between the video signal source and the control system, store the correction data internally, apply the correction data to the input video stream signal for real-time operation, and then output it to the control system. Software implementation is to intercept the display data stream with the computer as the signal source, correct it, and output it to the DVI port after data operation.Compared with the correction realized by the control system, since the DVI signal is only 8 bits, this method of correction realized by the front-end video processor will seriously lose the gray level, and its low brightness and poor linear performance will be the inevitable result, and the effect will not be ideal due to insufficient accuracy when applying chromaticity correction.2.4 combination of acquisition system and control systemIn the process of point by point correction, the following three steps are required: control the system to control the screen body and display the red, green and blue pictures in the designated area; The acquisition system completes the acquisition respectively; The correction data is generated and written into the control system.Before 2009, the acquisition system was mostly developed by the control system and used with its own control system. LED screen manufacturers introduce imported acquisition equipment combined with their own control system. There are two situations: one is to transform the control system according to the requirements of the control interface protocol of the acquisition system and use the software function of the acquisition system to complete the correction; The second is to develop software to realize the generation and writing of display control, acquisition system acquisition and correction data. These two situations mean that the technology introduction is difficult and costly. Similarly, it is incompatible and cannot be combined with the general control system in the market.Because the acquisition equipment is professional and stable, only one data acquisition is needed to complete the correction, so the display control part becomes very simple and can be completed without interactive communication with the control system. For the step of writing to the control system, the control system can read and write the relevant storage area by itself in the form of data document.In this way, the general control system can realize point-to-point correction by reading the correction data document in the open format of zhongkeweiyou without any modification or disclosure of any control interface command. The workload of system docking is reduced to the minimum, and the acquisition system realizes the maximum compatibility with the emerging control systems at the minimum cost.
How Can We Make the Small Spacing LED Display Screen Not Black
How Can We Make the Small Spacing LED Display Screen Not Black
Do you know how to make the small spacing LED display never black?As we all know, do you know how to make the small spacing LED display never black? The LED display screen is not an ordinary electrical appliance formed at one time in the factory, but a product made on site according to the customer's use requirements and installation environment. The failure rate is much higher than that of other electrical appliances. Therefore, it has high requirements for the rigor of on-site production personnel and after-sales requirements of the manufacturer.In recent years, the application of small spacing LED display screen is becoming more and more popular. With the unique advantages of display effect, its application places range from ordinary conference room, monitoring room and Exhibition Application to National Conference Center, monitoring center, CCTV and large-scale events. Such as G20 meeting, Zhu rihe military parade and Tianjin National Games, the figure of small spacing LED display screen is everywhere.However, as a new technology and high-precision equipment, in addition to the excellent display effect, the user needs are also accompanied by stability considerations, because once the black screen appears in the main venue, it will have a significant international impact and even political impact, such as the 5-ring to 4-ring of the Tianjin National Games.Application field analysis of small spacing display screenAs a new generation of indoor professional display panel, small spacing LED has formed the most direct impact on the traditional DLP. In other words, small spacing LED has actually formed a technical replacement for DLP in product application. But this substitution is not a simple one-to-one. There are still great application differences between small spacing LED display and DLP, so the technical selection of screen is particularly important for different projects.Therefore, when the small spacing LED is used as the main screen of the venue, its stability assessment is the top priority, and the first one is that the screen cannot be black.Analysis of the reasons for never black screenBecause of this demand, we deeply analyze the causes of black screen, so as to fundamentally eliminate the hidden dangers of black screen and truly never black screen. The display screen is an electronic device, the internal control card chip is FPGA, and there is no operating system, so the reasons for the black screen can be classified into two parts, one is device failure and the other is cable failure.1: Equipment failureEquipment failure mainly occurs in two devices: receiving card and switching power supply.A: Receiving cardThere are many devices on the receiving card. An ordinary receiving card integrates two gigabit network communication interfaces, 120P light board drive interfaces, SDRAM, flash, etc. with more than 10000 solder joints. Due to the inductive load of LED, its working environment is relatively complex. In order to pursue ultra-thin, some manufacturers sacrifice internal heat dissipation space and use mini cards. Their electronic devices have many contacts, complex electromagnetic environment and internal high thermal environment, resulting in reduced working stability. An accidental capacitor fault may cause abnormal screen display.B: Switching power supply failureThe LED display screen is an inductive load, and the output load changes with the picture, which has a great impact on the internal devices. In addition, there are many internal capacitors in the switching power supply. In order to reduce the use cost, some manufacturers use the switching power supply with automatic fan cooling. Because both capacitors and fans have a short service life, it has become the most frequent inducement of switching power supply faults, and the black screen fault caused by power supply fault ranks first in the whole device and equipment.2: Cable failureCable faults are mainly divided into external connecting cables, such as cables that provide power and signals to the screen, and internal cable faults, such as internal DC power line, internal gray line, etc.A: External cableAmong the external cables, the signal cable has the highest failure rate and the greatest impact. The signal cable commonly used for the display screen is CAT5e cable, which is difficult to ensure the stability of signal communication due to material construction and other factors, especially the butt joint of 2-end crystal head, with poor vibration resistance.B: Internal cableThe internal cables are mainly gray cables, as shown in the figure below. Most of the gray ribbon cables are made by cold pressing. After many times of plugging, the contacts are easy to have poor contact, and even the gray ribbon cable is broken seriously. Therefore, the internal cable fault has the highest incidence of all cable connection faults.Coping strategies of never black screenThe above analyzes several reasons for the black screen. We will apply the right medicine to the case, shield the above problems from the design end, and fulfill our commitment to customers and users - never black screen.One of the sharp tools to never black screen: no receiving cardCompared with the traditional receiving card design scheme, our company adopts the scheme without receiving card to highly integrate the products,The special chip with higher integration is designed on the adapter board. The chip integrates gigabit network communication, FPGA, SRAM, flash, MCU, etc. in the conventional receiving card. It has changed from seven ICs to one IC, which is highly integrated, reduces the solder joint connection by 80%, reduces the failure rate of electronic devices from the front end, and then improves the system stability.Never black screen sharp weapon 2: no flat cable, connector hard connectionCompared with the flat wire connection just now, there is no connecting cable inside, and all transmission is carried out through PCB and connector, which avoids hidden dangers such as multiple plug-in fatigue of cables and poor contact caused by conventional cold pressing from the design end.Never black screen Sharp Weapon 3: dual power supplyAs mentioned above, switching power supply failure is the first among device failures, so dual power supply backup is generally adopted for high-end applications. At the same time, the switching power supply designed by our company has the function of automatic current sharing, that is, two power supplies are output at the same time, which can reduce the workload of the power supply, prolong the service life of the power supply, avoid the power grid impact caused by the cold switching of the power supply, display jitter or third harmonic caused by equipment restart, and monitor the power supply status in real time at the software end, It can also be replaced quickly during maintenance to eliminate faults.Never black screen Weapon 4: loop designAccording to the level of on-site demand for signal stability and cost budget, our products can complete four levels of backup. The two most important levels of backup are dual interface and dual loop, and dual interface and four loop. Dual interface and dual loop are generally used for TV stations, while dual interface and four loop are used for live broadcasting, national live conference, etc.Double interface and double loop of never black screen loop designAs shown in the figure above, two independent signal loops are composed of dual signals, which can ensure that when one loop fails, the other loop can be switched immediately and the switching time can be reduced 0.1ms. For the hot standby places where some TV stations require power interfaces, power connectors can be added to realize dual power supply and dual signals on the screen. At the splicer end, two independent duplicate signals can be output to two transmission boxes through the backup board card.Double interface four loop design of never black screen loopThe backup level is the highest level, that is, the four input ports of the signal can work normally as long as one is normal. This backup mode is adopted for the main screen of the venue of the Guangzhou Asian Games. Of course, this backup mode will increase the cost of front-end equipment, which is usually more than 4 times higher than the conventional configuration. The above is the solution that the small spacing LED display screen will never be black. I hope it can help you.
Special Shaped Screen: Breaking the Regular Shape Limit of LED Display Screen
Special Shaped Screen: Breaking the Regular Shape Limit of LED Display Screen
The special-shaped screen, also known as the creative screen, has a stronger visual shock effect than the traditional display screen. It breaks the restriction of the regular shape of the traditional LED display screen. It is different from the rectangular and flat plate shape of the conventional LED display screen, but appears in a variety of shapes. Compared with the traditional display screen, its biggest feature is that it can better adapt to the overall structure and environment of the building, and the screen size and size can be customized according to the requirements. It can be said that the special-shaped screen changes various shapes to present different effects on the basis of the traditional LED display screen, making it more novel and unique in shape.For a long time in the past, led special-shaped screens were realized by assembling or wrapping traditional rectangular plane modules. The most common LED special-shaped screens are large arc screens and plane circular screens. At present, led enterprises have specially developed various special-shaped modules such as triangle, trapezoid, circle and parallelogram, which can be combined into various shapes, regular or irregular geometric LED displays such as wave screen, fan screen, arc screen, circular screen, cone screen, spherical screen, diamond screen and diamond screen.Led special-shaped screens have different appearances and structures, so the technical requirements for manufacturers have become extremely stringent. If the manufacturer's technology does not pass the test, the spliced LED screen will inevitably have many problems such as uneven appearance caused by too large splicing gap and discontinuous splicing surface, which will affect the viewing effect and destroy the beauty of the overall design. More importantly, the design of the circuit and structure of the LED special-shaped screen is complex and the installation is difficult, which puts forward higher requirements for the manufacturer's R & D ability and installation accuracy.Special shaped splicing gives users a sense of freshness in addition to shock. Large size is just an advantage of splicing large screen, and its amazing appearance can not be ignored. The appearance of special-shaped splicing technology makes the splicing large screen break the shape design of the traditional display large screen, can create a more personalized appearance for users, and is more eye-catching in practical applications, especially in the field of exhibition. Compared with the traditional splicing methods, the appearance and installation position of special-shaped splicing are more flexible and diversified. The combination of vertical and horizontal placement and the diversity of use forms enable it to play a role in more fields and expand some potential new fields.At present, the special shaped splicing screen can be designed with infinite technology and can be designed in an infinite size, penetrate into the trend of Internet plus, realize cross screen roaming, display multi screen mosaic unit units, and create seamless seamless display effect. With the help of the intelligent hardware and material software of the display screen combined with the environmental design, we can realize the multi-dimensional space, show a novel and unique creative display, and create a dream atmosphere combining real and illusory scenes, so that it can intelligently create an infinitely creative display in both appearance and content!
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