How to Adjust the Brightness and Color of LED Display Screen

LED display screen is more and more favored by the market because of its excellent brightness and color performance and seamless picture integrity. However, some cities also have problems affecting the life and traffic of surrounding residents due to the high brightness of LED display screen. ? Here, I'll share some tips.oneSelection of primary color wavelength

How to Adjust the Brightness and Color of LED Display Screen 1

LED display screen is widely used in all walks of life, and there are different requirements for the primary color wavelength of LED in different application places. Some of the selection of the primary color wavelength of LED is to achieve good visual effect, some is to meet people's habits, and some are the provisions of industry standards, national standards and even international standards. For example, the selection of the primary color wavelength of the green tube in the full-color LED display screen; In the early days, yellow green LEDs with a wavelength of 570nm were widely used. Although the cost was low, the color gamut of the display screen was small, the color reduction degree was poor and the brightness was low. After selecting the pure green tube with the wavelength of 525nm, the color gamut of the display screen is nearly doubled, and the color reduction is greatly improved, which greatly improves the visual effect of the display screen. Another example is the stock market display. People are usually used to using red to indicate the rise of stock prices, green to indicate the decline of stock prices, and $to indicate flat prices. In the transportation industry, the national standard strictly stipulates that the blue-green band indicates passage and the red band is prohibited. Therefore, the selection of primary color wavelength is one of the important links of LED display screen.

twoBrightness adjustment1. Modulating pulse width, using the changing frequency that human eyes can feel, and using pulse width modulation method to realize gray control, that is, periodically changing the optical pulse width. Pulse width modulation is more suitable for digital control and has been widely used. The most common method is to adopt microcomputer. At present, almost all LED displays adopt pulse width modulation to control the gray level.

2. The normal LED tube allows the continuous task current to be about 20 mA. By changing the current flowing through the LED, except that the red LED is saturated, the brightness of other LEDs is basically proportional to the current flowing.threeAllocation of white field color coordinates

White field color coordinate allocation is one of the most basic technologies of full-color LED display. However, in the mid-1990s, due to the lack of industry standards and basic testing methods, the white field color coordinates were usually determined only by human eyes and feelings, resulting in serious color deviation and randomness of white field color temperature. With the promulgation of industry standards and the completion of testing methods, many manufacturers began to standardize the color matching process of full-color screen. However, due to the lack of theoretical guidance of color matching, some manufacturers often allocate 100 field color coordinates at the expense of the gray level of some primary colors, and the comprehensive performance can not be improved.

How to Adjust the Brightness and Color of LED Display Screen 2

fourColor adjustmentHD LED display is displayed according to the principle of three primary colors of light. Determining one of the red, green and blue colors as the benchmark is mainly determined according to the brightness of the red, green and blue colors of the selected product. Generally, the brightness benchmark is the one with low brightness proportion. When one of the benchmarks has reached the maximum brightness, it is necessary to adjust another color for the two-color LED display screen, For the full-color LED display, it is necessary to adjust the colors of the other two LEDs.

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Introduction to the Characteristics of Small Spacing LED Display Screen
Introduction to the Characteristics of Small Spacing LED Display Screen
With the increasing value of small spacing large screen system in command / dispatching center and video conference system in many fields, as well as the continuous improvement of national informatization, new industrialization construction and management application level, the rise of safe city and smart city, and the large screen splicing market will continue to maintain a stable growth trend in the future, From 2011 to 2019, the compound growth rate of market scale will exceed 40%.At the same time, due to the demand of various industries in terms of clarity, brightness, contrast and size, with the rapid growth of social informatization, the demand for information visualization has also expanded sharply. At the same time, it is more and more difficult to realize high-end visualization, especially in some important places such as monitoring center, command center and dispatching center, Therefore, large screen splicing system has become an indispensable core basic system for information visualization.In order to meet this development demand of the market, Jingrui Chuangxian jrcld has launched a variety of more accurate products. Taking the p0.7 p0.8 p0.9 P1.2 P1.4 P1.5 P1.6 small spacing LED display products of Jingrui Chuangxian jrcld as an example, a new generation of fully sealed front and rear full die-casting aluminum box design is adopted. The traditional die-casting aluminum box usually only supports post maintenance and installation, The new generation of full die-casting aluminum box can take into account the front maintenance and installation, which not only maintains the characteristics of high precision, no seam and excellent flatness of the traditional die-casting aluminum box, but also takes into account the characteristics of magnetic suction front maintenance, space saving and convenient installation.High brightness: brightness 1000nit, higher than LCD and DLP rear projection brightness, and can be automatically adjusted to achieve obvious energy saving and consumption reduction effect.Golden Ratio Design: original 16:9 gold unit size and resolution design, showing a perfect vision.High refresh rate: 2K / 4K / 8K # standard resolution display screen, with stable display, no ripple and flicker, and real and natural display effect.Wireless plug-in: full cast aluminum die-casting box structure, light and stable, wireless connector splicing between boxes, simple and generous appearance.High contrast: high quality surface paste three in one LED Black lamp is adopted, and the contrast can reach 5000:1.Strong processing ability of fast dynamic picture: nanosecond response time. When processing fast dynamic picture, there will be no tailing and ghosting.Front and rear maintenance: compatible with the front and rear maintenance methods, the disassembly is convenient and fast, saving maintenance time and cost.Good color consistency: the single point luminance meter color correction technology can ensure the uniformity of brightness and color when the product leaves the factory. It also has skin color restoration and green restoration technology to make the picture color more realistic.
Analysis on the Principle and Design Method of Chromaticity Correction of LED Display Screen
Analysis on the Principle and Design Method of Chromaticity Correction of LED Display Screen
With the technical progress of point-to-point correction, customers have higher and higher requirements for the display quality of LED screen, from only pursuing the brightness and white balance index to gradually improving the requirements for display uniformity and color fidelity. The use of point-to-point correction technology to greatly improve the uniformity of the display screen is currently in the process of rapid popularization and application, and the demand for chromaticity correction has gradually surfaced, which has attracted more and more attention in the industry. This paper will briefly introduce the principle, application, implementation methods and skills of LED display chromaticity correction.1. Basic concepts of chromaticity correctionCIE XYZ 1931 standard chromaticity system shall be used for chromaticity measurement and calculation of LED display screen. In order to introduce the calculation formula of chromaticity correction later, first, briefly sort out the basic concepts related to chromaticity correction:1.1 tristimulus valueAccording to Glassman's color matching principle, three primary colors are selected. Any one of the three primary colors cannot be obtained by adding and mixing the other two primary colors. For example, RGB primary colors, the relative brightness unit of the three primary colors is determined by selecting a specific white light as the standard, and the light of other colors can be regarded as a mixture of different amounts of three primary colors, The number of three primary colors required is the tristimulus value.CIE XYZ 1931 chromaticity system uses three imaginary primary colors, [x], [y], [Z] to replace RGB primary colors, and determines the units of three primary colors by matching isoenergetic white light. When quantitatively expressing the brightness and chromaticity of a light source, the chromaticity equation can be expressed as follows:C [C] = x [x] y [y] Z [Z] (equation 1)In the formula, x, y and Z are the three stimulus values, and the three stimulus values of the mixed color are the sum of the three stimulus values of each component color.Note that among the three primary colors, only [y] primary color represents both chromaticity and brightness, [x] and [Z] only represent chromaticity.1.2 color coordinatesThe relationship between the color coordinates x, y, Z and the tristimulus value XYZ in CIE XYZ 1931 chromaticity system is as follows:It can be seen that x, y and Z are not independent, and X y Z = 1. Therefore, only x and Y color coordinates can uniquely express the chromaticity.With three stimulus values, we can calculate the color coordinates x and y. Conversely, with the color coordinates x, y, and y, the tristimulus value XYZ can also be calculated, as shown in the following formula:Tristimulus value XYZ is the basis of mixed color superposition calculation, and mixed color superposition calculation is the theoretical basis of chromaticity correction.1.3 gamut spaceColor gamut refers to the range area composed of the number of colors that can be expressed by a surface color mode, and also refers to the color range that can be expressed by specific media such as screen display, digital output and printing reproduction.(Figure 1)Note: the large blue and white triangles in the figure are the assumed original color gamut space of the two LED screens, and the small black triangles inside are the set target standard color gamut space sRGB. The color gamut triangle is completely included by the two original color gamut triangles, so it is the color gamut space that can be realized by correction for both displays.For LED display screen, corresponding to CIE 1931 chromaticity diagram (see Figure 1), it is the color gamut triangle composed of three primary color coordinate lines and the set white point. The three primary color gamut triangle determines the color that the LED display can represent. The white dot defines the required ratio of three primary colors, that is, the unit quantity. After the production of a display screen is completed, its color gamut triangle is determined, and the adjustment of white balance can be realized by changing the ratio of RGB by adjusting resistance and other methods.The colors inside the three primary color gamut triangle are all the colors that can be realized by the mixing of the three primary colors.Therefore, the original color gamut space definition of an LED display screen shall include the following parameters:RxRy GxGy BxBy WxWyThe above four groups of color coordinates are the color coordinates of red, green, blue and white when the display screen displays (r255, G0, B0), (R0, g255, B0), (R0, G0, B255) and (r255, g255, B255).White is formed by mixing RGB three primary colors. Therefore, if the luminance values ry, Gy and by of RGB three colors are given, the respective tristimulus values of RGB three colors can be calculated.The white color coordinates Wx, WY and white brightness value WY can be calculated by the superposition of XYZ three stimulus values of RGB three colors:On the contrary, given the color coordinates and brightness value of white, the required brightness value of RGB three primary colors can also be calculated.2. Application field of chromaticity correction2.1 improve color fidelityThe most original application of LED screen chromaticity correction serves to improve the color fidelity of the display, make the displayed image consistent with the color of the source image, and restore the natural color more truly. To put it more popularly, it is to make the displayed color more "positive".The display content on the LED screen is generally from the TV camera, camera, or computer. The color gamut space of TV and computer monitor is inconsistent with that of LED screen, which leads to the phenomenon of display color distortion. For example, the common color gamut space standards pal and NTSC of TV and the color gamut space standard sRGB of computer monitor are inconsistent with the inherent color gamut space of LED display screen. The LED color gamut space is large, the color performance is usually over saturated, and the visual feeling is more gorgeous and exaggerated, so it is distorted.One of the objectives of chromaticity correction is to correct the color gamut space of the display screen to the color gamut space of the video or image source, or as close as possible, so as to improve the color fidelity of the display.2.2 mixing of different batches of boxesRental screen owners often encounter this situation: batch boxes purchased by time periods are expected to be mixed together to facilitate undertaking larger performance projects. Engineers sometimes encounter the requirements of customers, hoping to expand the area of an original display screen, and make a new part of the box and the old screen into a large screen.However, due to the difference between the original brightness and the original color gamut space, different batches of boxes go their own way and are incompatible.At this time, chromaticity correction can correct the original color gamut space of boxes in different batches to a coincident target color gamut space, so as to realize the mixing of boxes in different batches and the splicing of new and old screens.2.3 chromaticity uniformity correctionThe purpose of chromaticity uniformity correction is to improve the color difference between pixels of the display screen. At this time, each pixel and the combination of a group of RGB lamps can be regarded as a color gamut space. The task of chromaticity correction is to correct the color gamut space of all pixels on the display screen to the same color gamut space.At present, the application of chromaticity uniformity is very limited due to the color separation accuracy of light and color splitter and effective lamp mixing technology. Because the color difference resolution of human eyes to pixel level is about 4nm, and the color separation accuracy of light and color splitter can generally reach 1nm. Chromaticity uniformity correction is necessary unless a very large number of batches and a small number of inventory LED lamps are used for the same screen.3. Chromaticity correction principleAfter clarifying the concept of chromaticity and the application field of chromaticity correction, let's take a look at the principle and specific implementation method of chromaticity correction of LED display screen.The principle of chromaticity correction is gamut space transformation. The inherent wide gamut space of LED screen is transformed into a target gamut space set by the user, which can be either a standard gamut space or a user-defined gamut space.For LED screen, in order to ensure the display quality, we must ensure the uniformity of brightness while correcting chromaticity. Therefore, the bright color correction must be completed synchronously. Therefore, the corrected target brightness value shall be given at the same time.3.1 calculation of gamut space conversion coefficient matrixColor gamut space conversion first needs to determine the original color gamut space tristimulus value matrix [XYZ_ Original] and target gamut space tristimulus matrix [XYZ_ Target], so as to calculate the conversion coefficient matrix [conversion]_ coefficientorderAccording to the needs of color gamut space transformation, there are:conversion_ coefficient *XYZ_ original= XYZ_ Target] (equation 9)From the above formula:conversion_ coefficient= XYZ_ target* XYZ_ Original] - 1 (equation 10)In the conversion coefficient matrix of equation 8,RR is the luminance coefficient of the red light when the display source signal is red;RG is the brightness coefficient of green light when the display source signal is red;RB is the luminance coefficient of the blue lamp when the display source signal is red;GR is the luminance coefficient of red light when the display source signal is green;GG is the brightness coefficient of the green light when the display source signal is green;GB is the luminance coefficient of blue lamp when the display source signal is green;BR is the brightness coefficient of red light when the display source signal is blue;BG is the brightness coefficient of green light when the display source signal is blue;BB is the brightness coefficient of the blue lamp when the display source signal is blue;3.2 application of gamut space conversion coefficient matrixAfter obtaining the pixel by pixel color gamut space conversion coefficient matrix, the control system can adjust the color gamut space of the display screen to the target color gamut space by performing real-time pixel by pixel operation on the display source signal.Suppose the conversion coefficient matrix of a pixel is as follows:When the display signal is (r255, G128, B64), the actual lighting of the three lamps of the pixel is as follows:That is, the source signal (r255, G128, B64) is actually displayed as (R238, G128, B71) on this pixel.It should be noted that the above operation is based on linear brightness. In practical application, the coefficient application and linear operation should be carried out after gamma correction.4. Chromaticity correction skills of LED screenThe calculation method and application method are very clear. However, there are still some matters needing attention and skills in the calibration practice of LED screen.4.1 target gamut space settingThe reasonable setting of the target color gamut space is very important. Otherwise, it may not be achieved, or the white balance may not be achieved, or the brightness uniformity may be damaged.1) The three primary color coordinates of the target color gamut space must all be within the original color gamut triangle. The color outside the original color gamut triangle cannot be realized by color mixing on this display screen. In the Sv-1 correction system of zhongkeweiyou, CIE1931 color map is provided. The program will draw the original color gamut triangle and the target color gamut triangle, and give a graphical prompt that the target three primary colors are already within the original color gamut triangle to avoid setting errors.2) Because the maximum brightness of the three primary colors of the display screen is limited, if the white point coordinates and brightness values of the target color gamut space are set unreasonably, a large number of pixels on the display screen will not reach the predetermined target value. In the Sv-1 correction system, the number, proportion and position of pixels that cannot reach the target value on the display screen will be calculated according to the setting parameters of the target color gamut space, The simulation diagram is displayed to help users reasonably set the target white point and brightness.4.2 requirements for display screen and control systemFrom the example chromaticity correction data in 3.2, it can be seen that the value of the complementary color coefficient in the conversion correction coefficient is small and changes greatly, sometimes only one thousandth, and sometimes even 1 / 3. Therefore, the application of conversion correction coefficient puts forward higher requirements for display screen and control system.1) The display screen must be able to realize gray scale of more than 12 bits;2) The control system shall be able to read the conversion correction 9 coefficient data with accuracy of at least 12 bits and conduct real-time operation;Only when the above two conditions are met can the display screen ensure the accuracy of chromaticity correction and the brightness uniformity after correction.4.3 most applications of chromaticity correction are gamut space correction.The original three primary color coordinates required for the correction of color gamut space can be obtained by measuring the regional average color coordinates with a conventional color luminance meter. However, because the RGB brightness ratio in each pixel is inconsistent, it is necessary to ensure the calibration
Design Scheme of Single Card Network Cable Control System for Ultra-high Definition LED Display Scre
Design Scheme of Single Card Network Cable Control System for Ultra-high Definition LED Display Scre
Abstract: for the current 2 & times; Due to the low bandwidth of 1 Gbit / s network led display controller, a design scheme of ultra-high definition LED display single card network cable control system based on 10 Gbit / s Ethernet IEEE 802.3an standard, using twisted pair as transmission medium and transmission distance of 100 m is proposed. HDMI 1.4a/dvi dual input is adopted for audio and video, 10GbE LAN / WAN PHY is adopted for communication, medium and high-grade field programmable gate array (FPGA) with XAUI / sgmii interface is adopted for information processing, and Gigabit network matrix shunting technology is adopted for screen display distribution, so as to realize LED display 4k2k, 3D display and audio synchronous playback controlled by single card.introductionAt present, many companies have launched 4k2k (physical resolution 3840 & Themes; 2160 or 4096 & Themes; 2160) high-end graphics cards, ultra-high definition TVs, naked eye 3D TVs and projectors. In both horizontal and vertical directions, 4k2k specification is the existing mainstream Full HD display device 1920 & tides; Twice the 1080p resolution, the total number of pixels has reached more than 8 million, four times that of Full HD. In the field of LED full-color display, especially in the application of stage background screen and square advertising screen, due to its infinite splicing characteristics, more than 4k2k high-grade LED display and 3dled display have already come out. However, the current mainstream LED display control system in the market mainly adopts DVI input dual port Gigabit network mode for short distance and single channel 1 - 3. 125gbit / s optical fiber communication mode for long distance. The maximum resolution supported by the single board can only reach 1280 when 8-bit color scale input 1024 (60 Hz, no compression). If you want to support ultra-high resolution display or output above 30 bit color scale, you must use multi card or multi controller system and expensive video segmentation splicer. Obviously, the current LED display control system, especially the short-range dual port Gigabit network control system, which has been used for many years, has lagged behind the development of video and communication technology and can not meet the higher needs of the market and users. Therefore, based on the development of the previous generation of dual port Gigabit Network LED controller, a HDMI / DVI dual input ultra-high definition LED display single card network cable control system is designed, which greatly improves the bandwidth, function and cost performance of the traditional LED display controller.1 overall designThe UHD LED display single card network cable control system includes sending and receiving parts. Figure 1 shows the transmitter control logic design, including HDMI input port, DVI input port, USB interface, adv7619, CP2102, FPGA, DDR, flash, PCIe socket, peripherals and high-speed communication logic.Figure 1 Schematic diagram of transmitter logic designFigure 2 shows the receiver control logic design, including high-speed communication logic, FPGA and 3 4 ports 1GBIT / s PHY, 12 It integrates RJ45 socket, DDR, flash, audio output and external equipment, in which the high-speed communication logic is exactly the same as the transmitter.Figure 2 Schematic diagram of receiver logic design.
Difference Between LCD Splicing Screen and Large LED Display Screen
Difference Between LCD Splicing Screen and Large LED Display Screen
LCD splicing screen and LED display large screen are recognized as the most popular and widely used large screen display products in the display market; However, many people are curious about the similarities and differences between the two. Today, Xiaobian will specifically distinguish the characteristics of the two products.1. Brightness due to the strong outdoor lighting, the brightness of the large LED display screen is relatively high, and the brightness of the splicing screen is as high as 7000CD / m In order to adapt to some special environment or users with special requirements. 2. The stitching of the splicing screen can be followed by the naked eye, which is also a disadvantage of the splicing screen itself; The large LED display screen can not see the distance between the lamp beads within the visual distance, but if it is close to the visual range, the image will begin to blur and deform; For example, under the visual condition of P3, if the LED is viewed within 3M close to the screen, the picture must be distorted.3. Quotation: two clocks show the quotation of the large screen, and the LED is calculated according to the square of the project and other expenses; The splicing screen is calculated according to the number of splicing units, processing software, installation cost, etc. 4. The operation time splicing screen can support 7 * 24 hours of uninterrupted and non-destructive hardness, while the large LED reality screen must rest after running for more than 8 hours to ensure the service life of the product. 5. Different splicing technologies. The splicing screen is composed of multiple LCD splicing screens, which supports multiple signal inputs. It can realize the simultaneous display of multiple images and can be enlarged or reduced arbitrarily, so as to realize roaming and cross screen display. In addition, it can also realize single screen segmentation with decoding platform, so that users with multiple monitoring images can display all images on a large screen at the same time; The small spacing LED is the fine processing of LED display technology, which reduces the point spacing.The above are several important differences between the splicing screen and the LED display screen. I hope it will be helpful to some buyers who have just touched the splicing screen or LED. If you have any questions, you can leave a message for consultation.Source: Huabang yingzhuanxian Technology http://www.hbony.com/ , it is personal original, if you need to reprint, please indicate the source.
What Should I Do When the LED Display Screen Does Not Work? Is There Any Solution
What Should I Do When the LED Display Screen Does Not Work? Is There Any Solution
When the LED display screen is installed or used, sometimes the display screen does not work. At this time, many people who do not know the principle may feel that the quality of LED display screen is not good and ask to replace the screen. In fact, the phenomenon that the display screen does not work has nothing to do with the quality of the screen. Let's talk about the handling method of LED display screen not working.The first case that the LED display screen does not work is that the display screen does not work and the green light of the sending card flashes (made into retractable type).The main reason for this situation is that the screen body has no power supply; The network cable is not connected properly; The receiving card has no power supply or the power supply voltage is too low; The sending card is broken; The signal transmission intermediate equipment is connected or faulty (e.g. function card, optical fiber transceiver). The sequence of troubleshooting methods to be adopted at this time is: check and confirm that the power supply of the screen is normal; Check and reconnect the network cable; Ensure that the DC output power supply of the power supply is 5-5.2v; Replace the sending card; Check the connection or replace the function card (optical transceiver).The second case that the LED display screen does not work is that the Maipu Guangcai display screen does not work and the green light of the sending card does not flash.The main reason for this problem is that the DVI or HDMI cable is not connected properly; The copy or expansion mode is not set in the graphics card control panel; The software chooses to turn off the power supply of the large screen; The sending card is not inserted in place or there is a problem with the sending card. At this time, the detection sequence of exclusion method is: check the DVI cable connector; Reset the copy mode; The software selects to turn on the large screen power supply; Reinsert the sending card or replace the sending card.The above are the main problems and detection methods of LED display screen inoperative. I hope it will help you.fqj
Introduction of Advanced Technology Automatic Brightness Control in LED Display Screen
Introduction of Advanced Technology Automatic Brightness Control in LED Display Screen
The cutting-edge technology in LED display screen --- automatic brightness control. LED electronic display screen is composed of many independent pixel points (luminous elements). Due to the separation of pixel points, its luminous control and driving can only be carried out digitally. The luminous states of these pixels are synchronously controlled and independently driven by the controller. Video true color display means that the brightness of each pixel should be controlled separately and completed synchronously within the specified scanning time. The large screen is composed of tens of thousands of pixels, which greatly increases the complexity of the system compared with the large screen of binary display, and puts forward higher requirements for the overall data transmission speed. It is obviously unrealistic to set a conventional D / A for each pixel. We must find a solution that can minimize the system complexity and improve the performance as much as possible.According to the visual principle, the average brightness feeling of a pixel can depend on its on / off duty cycle. In other words, the brightness can be controlled as long as the pixel on / off duty cycle is adjusted. For the LED electronic display screen, this means that the brightness D / a conversion is realized as long as the number representing the brightness of the pixel is converted into the luminous time of the pixel (D / T conversion).Set the refresh cycle of screen data as, and the data controlling the lighting degree of any pixel is n-bit binary numberD = bi2i (where Bi = 0 or 1)Ton is the luminous time corresponding to D, then the duty cycle of pixel on / off is:d=Ton/Ts=D= bi2iThe expression can be realized by preset subtraction counter, but a counter for each pixel will make the display circuit extremely complex. The above formula is rewritten as: ton = TS bi2i, which means that ton can be divided into several time periods. When it is enough, the visual effect of ton synthesized by several separation time periods is the same as that of continuous ton with the same total length. Therefore, generally, for n-bit binary data d = bi2i, divide TS into n segments, and select the appropriate time division function f (I), so that segment I Ti = TSF (I), where 0tibi = TS f (I) Bi, then? d=Ton/Ts=TIbi/Ts=f(i)biThat is, the on / off duty cycle of this pixel. Since the function f (I) can be common to all pixels, the above formula shows that as long as f (I) is used to uniformly control each pixel, independent and synchronous D / T conversion of all pixels on the whole screen can be realized. For a single pixel, the above formula can be realized with the circuit of Fig. 1. In the figure, SFR is an 8-bit shift register and the figure shows the waveform of time division function f (I).The driving circuit of large screen display usually adopts the structure of "serial shift latch drive" in order to minimize the data transmission line. To realize the above formula on the full screen at the same time, all st signals can be controlled by F (I). Of course, the premise of this is that the same weight bits in each pixel control data are stored in the shift register, which can be achieved through pre-processing.
Phenomenon and Solution of LED Display Screen Not Working
Phenomenon and Solution of LED Display Screen Not Working
When the LED display screen is installed or used, sometimes the display screen does not work. At this time, many people who do not know the principle may feel that the quality of LED display screen is not good and ask to replace the screen. In fact, the phenomenon that the display screen does not work has nothing to do with the quality of the screen. Let's talk about the handling method of LED display screen not working.The first case that the LED display screen does not work is that the display screen does not work and the green light of the sending card flashes (made into retractable type). The main reason for this situation is that the screen body has no power supply; The network cable is not connected properly; The receiving card has no power supply or the power supply voltage is too low; The sending card is broken; The signal transmission intermediate equipment is connected or faulty (e.g. function card, optical fiber transceiver). The sequence of troubleshooting methods to be adopted at this time is: check and confirm that the power supply of the screen is normal; Check and reconnect the network cable; Ensure that the DC output power supply of the power supply is 5-5.2v; Replace the sending card; Check the connection or replace the function card (optical transceiver).The second condition that the LED display screen does not work is that the display screen does not work and the green light of the sending card does not flash. The main reason for this problem is that the DVI or HDMI cable is not connected properly; The copy or expansion mode is not set in the graphics card control panel; The software chooses to turn off the power supply of the large screen; The sending card is not inserted in place or there is a problem with the sending card. At this time, the detection sequence of exclusion method is: check the DVI cable connector; Reset the copy mode; The software selects to turn on the large screen power supply; Reinsert the sending card or replace the sending card.The above are the main problems and detection methods of LED display screen inoperative. I hope it will help you.
What Is Creative LED Display Screen and the Advantages of Creative LED Display Screen
What Is Creative LED Display Screen and the Advantages of Creative LED Display Screen
With the improvement of human living standards and the pursuit of spirit, people have higher and higher requirements for LED display screen. Creative LED display came into being. Creative LED display, also known as special-shaped screen, is a new branch of LED display application, with innovation and creativity as the core.Creative LED display screen refers to the LED display screen with special appearance, which is derived from the traditional LED display screen. The creative LED display breaks the simple square shape of the traditional LED screen. It can be spliced into various irregular shapes to display highly creative content.The creative LED display screen can select specific installation methods according to the overall structure and environment of the building, and the size and size can be customized according to the site requirements. In terms of appearance, the LED creative screen can not only attract the attention of the audience for the first time to achieve better publicity effect, but also better expand the application scope of large screen splicing. In real life, you can see creative LED displays with different shapes, including arc, diamond, sphere, barrel, arch, magic cube, cylinder, etc.Innovation, creativity as the core, embodies the innovative spirit, unique modeling, strong rendering ability, full personality and amazing effect.Advantages of creative LED displayToday, the tide of creative industry is sweeping the world. With the extreme pursuit of dynamic dance effects in various cultural performances, wedding performances, opening performances and entertainment, creative display has increasingly become the focus and focus of competition in the field of indoor large screen display and related companies. First, the creative LED display shows the personalized culture. For each creative exhibition project, after in-depth interview, careful listening and careful combing, an exclusive customized solution is formed, which uses metaphorical exaggeration and gorgeous video effects to be visualized through new media technologies.Secondly, the innovative LED display screen can become a city landmark and enhance the city image. On the basis of architecture or landscape, combined with the basic elements and symbols of architecture, seek the best visual language, perfectly integrate the LED display elements and architecture from the perspective of art and aesthetics, further beautify and upgrade, and realize the sublimation of value. And realize the city landmark to enhance the city image.Technically, creative LED display screen must not only have the core technology of LED display screen, but also need rich artistic modeling, structural mechanics technology and experience. In the future, creative LED display will be used in various applications, such as urban light carving, environmental art, architectural appearance, interior decoration, etc.With its unique personality, creative LED display has been in the industry for more than 10 years. Now the arrival of personalized era just brings a new vitality to the creative display and makes the creative LED display more vivid and charming.fqj
Design Scheme of Ambient Light Adaptive LED Display Screen of Msp430f169
Design Scheme of Ambient Light Adaptive LED Display Screen of Msp430f169
This design mainly realizes that the brightness of LED display screen changes with the ambient light, so as to avoid unclear display during the day or dazzling at night; And communicate with the host computer. The system is composed of msp430f169 single chip microcomputer, 16 * 32 common anode LED dot matrix display screen, row driving circuit, column driving circuit, ambient light adaptive circuit, digital switch voltage regulating circuit, DC voltage stabilizing source circuit, etc. The display of LED dot matrix screen is realized by sending data in parallel by column and scanning by row; The single chip microcomputer realizes the automatic adjustment of the power supply voltage of the LED dot matrix screen through the digital switch voltage regulating circuit, so that the screen brightness changes automatically with the ambient light.LED dot matrix display is very common in life, which has brought a lot of convenience to our life. Because the LED display brightness cannot change with the external ambient light, there is a problem of unclear display during the day or dazzling at night. If its brightness can be controlled, it can not only save energy, but also make the display effect of the display more clear. This design introduces the ambient light adaptive LED display screen controlled by msp430f169 single chip microcomputer system. The screen can automatically adjust the brightness according to the intensity of ambient light, so as to avoid unclear display in the day or dazzling at night, and communicate with the host computer. LED display has a wide range of applications, such as shopping malls, entertainment places, factories, schools and other large places. The research on LED display has practical value and good development prospects.1 system structure block diagramThe system is mainly composed of msp430f169 single chip microcomputer system, step-down rectifier filter circuit, voltage stabilizing circuit, switch voltage regulating circuit, RS485 communication interface circuit, led row and column driving circuit, ambient light detection circuit, LED display screen, upper PC computer, etc.The structure block diagram of the system is shown in Figure 1.Figure 1 system structure frame2 basic principlesThis design adopts the way of column sending data and row scanning to realize LED display text or image. The method is combined with the hardware circuit to achieve the purpose of relatively uniform overall brightness of the display screen.Using the sensitive characteristics of photosensitive resistance to ambient light, collect the change of ambient light, convert it into electrical signal and send it to the single chip microcomputer. The single chip microcomputer processes the signal, and controls the duty cycle of output PWM wave according to a certain law.A switch voltage regulating circuit is added between the single chip microcomputer and the LED display screen to realize the brightness adjustment of the display screen by the single chip microcomputer. The adjusted PWM wave is used to control the switching voltage regulating circuit, so as to adjust the input voltage of the display screen, and finally realize the brightness control of the display screen.3 circuit design3.1 msp430f169 single chip microcomputer system circuitMsp430f169 single chip microcomputer system circuit is the main control circuit. MSP430 series single chip microcomputer is a 16 bit ultra-low power mixed signal processor introduced to the market by Texas Instruments in 1996. The single chip microcomputer has the following characteristics: ultra-low power consumption, strong processing capacity, rich on-chip peripheral modules, convenient and efficient development environment and stable system operation. Because msp430f169 MCU integrates 12 bit a / D and D / A, and the program of generating PWM wave is simple, there is no need to add a / D circuit, D / a circuit and PWM wave generation circuit, which simplifies the design of peripheral circuit. Therefore, msp430f169 MCU is selected in this design, as shown in Figure 2.Fig. 2 single chip microcomputer system circuit
Chromaticity Processing Technology of LED Display Screen
Chromaticity Processing Technology of LED Display Screen
1 IntroductionLED display technology from the monochrome display in the early 1980s, to the double primary color display in the late 1980s, and then to the three primary color (full-color) display in the mid-1990s. Until today, we have widely discussed the multi primary color (greater than three primary colors) processing technology in the field of flat panel display. The ranges from the most basic primary color wavelength selection, to the allocation of white field color temperature, to the color space transformation processing to improve the color reduction degree and the chromaticity uniformity processing to improve the image quality. Until today, we have adopted the multi primary color (greater than three primary colors) processing in order to expand the color gamut and reproduce more natural colors. Various color processing technologies run through the development history of LED display screen and become one of the core technologies in the comprehensive discipline of LED display screen.2. Various color processing technologies2.1 selection of primary color wavelengthLED display screen is widely used in all walks of life, and there are different requirements for the primary color wavelength of LED in different application places. Some of the selection of the primary color wavelength of LED is to achieve good visual effect, some is to meet people's habits, and some are the provisions of industry standards, national standards and even international standards. For example, the selection of the primary color wavelength of the green tube in the full-color LED display screen; In the early days, yellow green LEDs with a wavelength of 570nm were widely used, althoughThe cost is low, but the color gamut of the display screen is small, the color restoration degree is poor, and the brightness is low. After selecting the pure green tube with the wavelength of 525nm, the color gamut of the display screen is nearly doubled, and the color reduction is greatly improved, which greatly improves the visual effect of the display screen. Another example is the stock market display. People are usually used to using red to indicate the rise of stock prices, green to indicate the decline of stock prices, and yellow to indicate the flat market. In the transportation industry, the national standard strictly stipulates that the blue-green band indicates traffic and redThe band is forbidden. Therefore, the selection of primary color wavelength is one of the important links of LED display screen.2.2 allocation of white field color coordinatesWhite field color coordinate allocation is one of the most basic technologies of full-color LED display. However, in the mid-1990s, due to the lack of industry standards and basic testing methods, the white field color coordinates were usually determined only by human eyes and feelings, resulting in serious color deviation and randomness of white field color temperature. With the promulgation of industry standards and the completion of testing methods, many manufacturers began to standardize the color matching process of full-color screen. However, due to the lack of theoretical guidance of color matching, some manufacturers often allocate 100 field color coordinates at the expense of the gray level of some primary colors, and the comprehensive performance can not be improved.2.3 chroma uniformity treatmentThe chromaticity uniformity of LED display screen has always been a major problem perplexing people in the industry. It is generally believed that the uneven brightness of LED can be corrected at a single point to improve the brightness uniformity. The chromaticity unevenness cannot be corrected, and can only be improved by subdividing and screening the LED color coordinates.As people have higher and higher requirements for LED display screen, only subdividing and screening led color coordinates can not meet people's critical eyes. It is feasible to comprehensively correct the display screen and improve the chromaticity uniformity.We find that even the same LED of the first international brand has large wavelength deviation and color saturation deviation, and the deviation range greatly exceeds the threshold of human eyes for green color difference identification. Therefore, it is of great significance to correct the chromaticity uniformity.In CIE1931 chromaticity diagram, according to the law of center of gravity, we find that the color coordinates of mixed colors can be adjusted to the intersection o of straight line Cr and straight line dB when green is mixed with a certain proportion of red and blue at any point within the range of G (& square; ABCD).Although the chromaticity uniformity can be greatly improved. However, the corrected color saturation decreases significantly. At the same time, another premise of using red and blue to correct the uniformity of green chromaticity is that the three red, green and blue LEDs in the same pixel should be centrally distributed as far as possible, so that the color mixing distance of red, green and blue can be as close as possible, so as to achieve better results. At present, the industry usually adopts the LED uniform distribution method, which will bring confusion to the chromaticity uniformity correction. In addition, how to measure the color coordinates of tens of thousands of red, green and blue LED is also an extremely difficult problem. We gave a hint.2.4 color restorationThe birth of pure blue and green LED makes the full-color LED display popular in the industry with its wide color gamut and high brightness. However, due to the large deviation between the chromaticity coordinates of red, green and blue LED and that of PAL TV (see Table 1), the color restoration degree of LED full-color screen is poor. Especially in the performance of human skin color, there are obvious visual deviations. Therefore, color restoration technology came into being. Here, the author recommends two methods of color restoration:First, the color coordinate space of red, green and blue LED is transformed to make the three primary color coordinates between LED and PAL TV as close as possible, so as to greatly improve the color restoration degree of LED display screen. However, this method greatly reduces the color gamut range of LED display screen and greatly reduces the color saturation of the picture.Second, only the most sensitive skin color gamut of human eyes is properly corrected; The color gamut that is not sensitive to other human eyes should reduce the original color saturation as little as possible. In this way, a balance can be obtained between color reduction and color saturation.2.5 3 2 multi primary color chroma processing methodEverything recovers in spring. Under the blue sky, the green grass is green; In autumn, wheat waves roll; Under the sun, it was golden. The colorful nature is so beautiful. Unfortunately, the existing LED display screen can not fully reproduce this beautiful scenery. Although LEDs belong to monochromatic light, each color LED still has a half wave width of about 30 50nm, so its color saturation is limited. It can be seen from Figure 3 that the color saturation of LED full-color screen is seriously insufficient in the yellow and cyan areas with extremely rich colors in nature.In recent years, in the field of flat panel display, they are keen to discuss 3 3 multi primary color display (red, green, blue plus yellow, green and purple) to expand the color gamut and reproduce more abundant natural colors. Then, can the LED display realize 3 3 multi primary color display?We know that in the visible light range, yellow and green are monochromatic light, and we have high saturation yellow and green LEDs. Purple is polychromatic light, and single chip purple LED does not exist. Although we can not achieve red, green, blue plus yellow, green and purple 3 3 multi primary color LED display. However, it is feasible to study red, green, blue plus yellow and green 3 2 multi primary color LED displays. Due to the existence of a large number of high saturation yellow and cyan in nature; Therefore, this study is of certain value.In the current TV standards, the video source has only three primary colors of red, green and blue, but no two colors of yellow and green. Then, how to drive the yellow and green primary colors of the display terminal? In fact, when determining the driving intensity of yellow and green primary colors; We follow the following three principles:(1) The purpose of adding yellow and green primary colors is to expand the color gamut and improve the color saturation. The overall brightness value cannot be changed;(2) The hue shall not be changed while increasing the color saturation;(3) Centered on D65; Take the rygcb gamut boundary as the endpoint, and make linear expansion at each point within the gamut range.Under the guidance of the above three principles; According to the law of gravity center, we can find a 3 2 multi primary color chroma processing method. However, in order to truly realize the 3 2 multi primary color full-color screen, we have to overcome the lack of brightness of yellow and cyan LEDs; At present, it is limited to theoretical discussion.3 SummaryTo sum up, we mainly discussed three aspects:(1) How to improve the chromaticity uniformity of LED display screen; (2) How to improve the color restoration of LED display screen; (3) How to expand the color gamut and restore more natural colors.When the above chroma processing technologies are implemented, they are interrelated, and in some aspects, even fish and bear's paw can't have both. The integrated LED display screen also needs brightness uniformity correction, gray nonlinear transformation, noise reduction processing, image enhancement processing, dynamic pixel processing, etc. the whole signal processing process is very complex. Therefore, we must comprehensively weigh various performances from the perspective of system, grasp the order of various processing, and increase the depth of signal processing, so as to make the LED full-color display show a colorful and colorful world.
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