The chromaticity coordinates of red, green and blue LEDs are quite different from those of cameras. So? If there is no color space conversion when LED display screen restores video images, there will be great color distortion. Our company uses large-scale integrated circuits for real-time matrix transformation of video signals, which greatly improves the color reproduction of video images. Among them,

Green:? △X≤0.0 1，△Y≤0.0 1

Red:? △X≤0.005，？ △Y≤0.005

Blue: △X≤0.005,? △Y≤0.005？

Led large screen display system features 2: improved clarity

The video clarity of LED display screen depends on the video front-end signal processing system;

The data sampling frequency, bright/color separation technology, noise reduction technology and signal interpolation mode of the video front-end processing system all play a vital role in the final display screen definition.

Our company completed the video front-end processing with Philips broadcast video decoding processing chip SAA7 1 14H as the core. The horizontal sampling pixels of the picture reach 768 points; PAL/NTCS double comb filter; Digital noise reduction between frames; Advanced processing techniques, such as on-line arithmetic average interpolation and expansion, can effectively eliminate noise, speckles, crawling (light/color crosstalk) and other phenomena in image signals, and ensure the improvement of display screen clarity.

Features of led large screen display system 3: Unique brightness and contrast adjustment method.

There are many ways to adjust the brightness and contrast of LED display screen. Different methods will have different effects on image quality.

Led large screen display system features 4: brightness level mode:

A) black level embedded displacement method (common in the industry)

This method has the advantages of simple implementation, wide adjustment range and many adjustment stages. But at the same time, there are some fatal weaknesses, such as saturation distortion of bright level or cut-off distortion of dark level, gray level decline, color reduction and so on.

b)？ Grey conversion method (unique to our company)

The gray scale control technology of our company deepens the depth of gray scale in the process of gray scale correction and conversion. By changing the gray level, the brightness of the display screen can be changed in the range of 12.5% ~ 100%, and the signal has no saturation distortion of bright level or cut-off distortion of dark level, and there are no phenomena such as gray level reduction and color reduction. Fully display the video image of 16.7M color.

Features of led large screen display system 5: Contrast adjustment method

The contrast adjustment method is as follows:

a)？ Video signal peak value adjustment method;

This method has the same characteristics as the black level embedded displacement method of brightness level: simple implementation, large adjustment range and many adjustment stages; But at the same time, there are some fatal weaknesses, such as saturation distortion of bright level or cut-off distortion of dark level, gray level decline, color reduction and so on. ?

b)？ Current peak adjustment method:

This method is to change the contrast by changing the peak value of LED driving current. Theoretically, this method is the best way to adjust the contrast of LED display screen. However, this method is rarely used at present because of its complicated technical approach and high cost.

c)？ Current pulse width adjustment method:

This method changes the contrast by changing the pulse width of LED driving current. This method is simple to realize, and there is no signal distortion and gray loss. Adjusting the contrast of LED display screen is the best method at present.

By improving the current pulse width adjustment method, our company not only retains the advantages of the current pulse width adjustment method, but also adjusts the contrast to 1024.

Features of led large screen display system 6: White balance and white field color temperature selection

According to the visual characteristics of human eyes, people like images with different color temperatures under different ambient lighting. According to this characteristic, when the environmental brightness changes, we can not only automatically adjust the brightness of the display screen, but also automatically change the color temperature of the display screen to meet the requirements of human visual characteristics.

The relationship between white color temperature and RGB brightness is as follows:

According to the principle of colorimetry, the color matching equation in "RGB" and "XYZ" color counting systems is:

[F]=R(R)+G(G)+B(B)=？ X(X)+Y(Y)+Z(Z)

X, y and z are chromaticity coordinates, where:

x=X/X+Y+Z

y=Y/X+Y+Z

z=Z/X+Y+Z

The advanced chromaticity analyzer CS- 100 accurately measures the chromaticity coordinates of each primary LED and selects the white color temperature, and then obtains the brightness ratio of the three primary colors through the brightness equation, so that the display screen can reach the most comfortable white color temperature for human eyes in various environments.

2. Composition of 2.led electronic large screen system

1)? Adopt special PCTV card for led electronic large screen. This card is a multimedia graphics card with excellent performance, which integrates the functions of display, acquisition and video acquisition. The card comes with a studio editing software. Studio is the peak? Compared with the existing universal multimedia card, a highly praised software of Systems has the following advantages:

① Enable users to make digital movies, shoot videos, edit and add stylized titles, transformations, and even narratives of their own music and digital video works on their own computers.

②Studio allows users to choose to output videos in MPEG or AVI file format and store them on CD, or display or create video emails on the website. Because the studio can talk to the peak? A series of capture devices of Systems began to work, and video capture became easier than ever.

(3) The application software of Studio is like a VCR, which has a good, better and best quality form from easy to useful, and calculates how many videos a computer can store. Studio automatically discovers and records scene changes, making editing easy.

④ Creating with Studio is a fast and interactive process. Use the real-time preview window to preview the movie at any editing time, that is, what you see is what you get.

If you don't like the title or the effect, you can make a change and see it right away. Video clips have never been so fast and interesting. Free enough, personalized enough, but also have background music, voice-over and other effects.

2)? The latest DVI with led electronic large screen? Interface technology. Use? DVI？ The principle and advantages of the interface are as follows: DVI interface (digital? Vision? Interface) is the industrial standard for the interface between PC and digital flat panel display (including). As we all know, the computer is digital, that is, the information it processes is digital, but the most widely used CRT display (such as TV) is analog. Therefore, before sending the data processed by the computer to the display, it is necessary to perform a digital-to-analog conversion (D/A), which leads to the loss of information and the defect of display effect. LCD, PDP, HDTV and other new generation displays are all digital. In the traditional way, the output (analog) of computer graphics card can only be sent to the display after analog-to-digital conversion (A/D), which has caused new losses and troubles. Using DVI interface, the developed LED display system can get data directly from the DVI interface of PC, without special graphics cards such as Galaxy cards or special acquisition cards, and is not limited by PC. At the same time, because DVI is an industrial standard, it can work well even if the bandwidth is as high as 83MHZ. Now DVI can support all display modes from VGA(640×480) to HDTV( 1920× 1080) and QXGA(2048× 1536). In addition, the LED display system developed with DVI interface can integrate many important functions on the basis of obtaining stable and reliable display data, such as: ① No data loss? ② Not restricted by PC. ③ Easy to upgrade. Generally, the memory of a graphics card is 8M, and that of a card is 32-64m. ④ Adjustment of window position and size; ⑤ Screen locking and shady control; ⑥ The frame rate is as high as 120HZ? ⑦? 8 192 gray scale, nonlinear adjustment output, more suitable for human eyes to watch; ? ⑧ Level 32 screen brightness control; Pet-name ruby constant current drive; Attending the red, green and blue brightness of the unit board can be adjusted separately to eliminate mosaics.

4) Adopt the special gray control chip ZQ9702 for led electronic large screen. In addition to displaying the distribution of data, the chip is also characterized by converting the received 8 bits (8? Bit) display data is converted into 8 192-bit output pulses, and on the basis of realizing 8 192 gray scale control on the display screen, the realization of nonlinear 256-level visual gray scale is ensured, and the full-color visual effect is achieved, which can fundamentally solve the system complexity caused by excessive data transmission in the digital display system. Has the following characteristics:

1 Simple? Because the most complex data conversion part of the system is realized in the form of internal logic of the chip, the system becomes very simple.

② Ease of maintenance? Simplicity is directly related to system maintainability. Because of omitting the complicated control part, the system maintenance has become a job that can be completed by junior technicians, which not only reduces the overall maintenance cost, but also improves the user satisfaction.

③ High reliability? The simplicity of the control part of the system further brings about the high reliability of the system, mainly because the integrated chip technology is several times more stable than the discrete device technology.

4 cost-effective? ZQ9702 system realizes the control of the gray level of the screen primary color 8 192 with the most reliable performance, and the image display is realistic and natural, achieving the same display control effect as FPGA system.

⑤ Unitized and structured design? In line with the development direction of the current industry, ZQ9702 large-scale display screen system adopts a unit design in the screen structure, and the system wiring is intuitive and simple, which not only ensures that the size of the display screen can be spliced and adjusted as needed, but also makes the installation, debugging and maintenance of the system extremely simple, thus minimizing the hidden failure rate of the display screen system.

⑥ Industrial reliability design? The system adopts the unit design based on ZQ9702 chip, which replaces a large number of discrete devices in the traditional design and greatly improves the reliability and stability of the system.

⑦ A complete multimedia solution system includes data source, transmission equipment, data processing, data distribution and software management tools, which makes the construction of LED display screen simple and standardized. This technology has been continuously developed and improved in the practical application process, and has become the most mature, stable and easy-to-implement system scheme.

Is it equivalent to the display effect of CRT? The core performance index of LED display screen is the gray level of each primary color (red, green and blue), that is, the brightness level. At present, international display standards require each primary color to reach a visual gray level of 256. The processing logic embedded in ZQ9702 chip can output 8 192 gray scale, and choose 256 gray scale suitable for CRT display, which makes the overall image effect clearer, more realistic and more appealing.

Pet-name ruby high resolution and high refresh rate? In addition to gray scale, the other two performance indicators of the display screen are resolution and refresh frequency. Due to the characteristics and requirements of LED display screen itself, traditional solutions often lose one or two of them as the price of improving another index. Because the data output of each pin of ZQ9702 chip reaches 1 trillion per second, which far exceeds the data output capacity of the traditional scheme, this problem is fundamentally solved. The ZQ9702 system can support the screen resolution of 1024×768 and the screen refresh frequency as high as 140Hz at the same time, far exceeding the performance index of the traditional solution, making the display screen stable, flicker-free and tailing-free.

5) Unique installation mode, no extrusion deformation;

6) Anti-glare and reflective mask (see attached figure 3):

(1) adopts matt material and unique tooth pattern technology to prevent light reflection to the greatest extent, improve contrast and increase image effect.

(2) Prevent direct sunlight from the LED lamp, protect the LED gun, prolong the service life of the LED lamp, and delay the aging speed of the LED lamp.

(3) Prevent sunlight from shining on waterproof glue, delay colloid aging, and ensure waterproof effect.