This article simply LED display is composed of a number of composable patchwork display unit (unit display board or unit cabinet) constitute the screen body, plus a set of appropriate controller (master control board or control system). So a variety of display boards (or unit boxes) of various specifications can be combined with different control technology controllers to form a wide variety of LED displays to meet the needs of different environments and display requirements.
One, the main composition of LED display screen (for example, the more complicated synchronized full color screen)
1. Metal structure frame, whose function is the inner frame, with various circuit boards, such as display unit or module, and switching power supply
2. Display unit: is the main part of LED display, which is composed of LED lights and drive circuit. Indoor screen is the unit display board of various specifications, the outdoor screen is the module box body.
3. Scanning control board: the function of the circuit board is the data buffer, which generates various scanning signals and the control signal of the space ratio grayscale.
4. Switching power supply: the 220V ac is converted into various direct current to provide various circuits.
5. Transmission cable: the display data generated by the master controller and various control signals are transmitted to the screen by the double stranded cable.
6. Main controller: the input RGB digital video signal buffering, grayscale transformation, reorganizing, and generating various control signals.
7. Special display card and multimedia card: besides the basic functions of computer graphics card, the digital RGB signal and line, field, and blanking signal are also sent to the master controller. In addition to the above functions, multimedia can be converted into a digital RGB signal (i.e. Video collection).
8. The computer and its peripherals
Ii. Main function module analysis
1. Video broadcast
Through multimedia video control technology and VGA synchronization technology, can be easily to various kinds of computer network system, introduced video sources, such as radio and TV and satellite TV signal, camera, video recorder VCD video signal, video signal computer animation information, etc., thus can realize the following functions:
Support VGA display, display various computer information, graphics, images.
Support various input modes; Support PAL, NTSC and other formats.
Real-time display color video image, live broadcast.
Broadcast television, satellite television and cable TV signals.
TV, video, DVD and other video signal instant playback (VCR, VCD, DVD, LD).
It has the ability to play both sides of the picture and the text
2. Computer broadcast
Graphic special effects: editing, zooming, moving and animation features.
Displays various computer information, graphics, images and 2, 3d computer animation and superimposed text.
The broadcast system is equipped with multimedia software which can input and broadcast a variety of information.
There are a variety of Chinese fonts and typefaces to choose from, as well as input into English, Spanish, French, German, Greek, Russian, Japanese and other languages.
There are many ways of broadcasting, such as: single/multi-line translation, single/multi-line/down-shift, left/right pull, upper/lower pull, rotation, and no scale.
Notices, announcements, announcements and news editors, and broadcast instant releases, with multiple fonts for selection.
3. Network functions
The standard network interface can be connected with other standard network (information query system, municipal publicity network system, etc.).
The real-time data of each database is collected and the remote network control is realized.
Internet access can be made through the network system
The audio interface can be connected to the audio device to achieve the sound image synchronization.
4. Screen control machine
The screen control machine controls its corresponding display display effect. It can automatically run a continuous loop program, which can be used to obtain relevant display data according to the given program, and can also manually intervene to produce the display effect on the screen. The pixels on the screen and the pixels in the corresponding area of the screen control display correspond directly to the pixels.
Through control machine can manually adjust the brightness of the display screen, choose to suit the current environment of gray nonlinear calibration data, the screen control machine can also through the network system based on environment brightness automatically adjust the screen brightness and choose different grayscale nonlinear calibration data.
The screen control machine can adjust the contrast and color of the image display. The screen controller will display information to video processing and control unit for video processing.
5. Video processing and control unit
Video processing and control unit complete the image processing of display data, which includes:
The second level of grayscale nonlinear correction can be adjusted automatically or manually.
Automatic or manual level brightness adjustment.
The grayscale control system can control the display of 24 bits of data of 8 bits per base color, i.e., each base color 256 gradation grayscale.
Image noise reduction processing ensures the image is cleaner and smoother.
Image enhancement technology, image edge enhancement technology.
Motion compensation technology, color adjustment function.
6. Visual processing
In the system, can adjust the brightness of the individual modules each gezer, respectively, to adjust the color balance, basically eliminated Mosaic phenomenon, all module and display module good brightness uniformity, monochrome display no visual difference.
The video processing and control unit will process good display information to the communication module for long-distance transmission to the display screen.
7. Communication module
The communication module ensures that the display content of the screen controller is transmitted over a long distance to the display screen. The communication module encodes and decodes the transmitted information for long distance transmission and reception data processing. The communication module will display information to the data distribution and scanning unit.
3. The main working principle of the display screen
LED display is usually controlled by the main controller, scanning board, display unit and LED display body composition, main controller from computer display card to get a screen each pixel brightness of of all kinds of data, and then assigned to a number of scanning board, scanning each one is responsible for the control of the LED display screen number of row (column), and each row (column) on the LED display signal is a serial way the display control unit cascaded through the bank transfer, each display control unit directly to the LED display screen. The work of the master controller is to convert the computer to the data and control signal format needed for the LED display. The function of control single transport is shown to be similar to that of the image display screen, which is usually composed of a shift register latch with grayscale control function. Only video LED displays tend to be larger, so you should use a larger integrated circuit. Scanning pull the role of the so-called continuity, on the one hand, it accepts the video signal of the controller, on the other hand to belong to the same level of data transfer to own the display control unit, while the does not belong to the corresponding data down a cascade of scanning transmission. Video signal and LED display data, in space, time, order and other aspects of the difference, need to have scanning board to coordinate.