Large LED display is a digital flat panel display. This requires it to display text, graphics, animation, images, video programs and other information. Full color LED display is designed to create a giant color display. Large-scale LED display and plasma display, large-screen rear projection TV and other flat-panel displays have many similarities.
In contrast, the LED in the data distribution, drive, reduce power consumption, improve efficiency, color reduction and consistency of the degree of consistency may be more difficult than other flat panel display. This is because the light-emitting diode is no indecent device, the switching time is nanosecond, no memory function, coupled with its display area, signal transmission distance, can not use the most advanced COG, SOB and other large Circuit manufacturing method, the following on the LED display on the image signal processing for a brief introduction.
LED display on the image signal processing generally there are two ways:
One way is to use a dedicated large-screen signal processor, the interlaced TV signal, processed into progressive scan signal, and then play on the big screen. High-performance processing can handle up to 10 bits or more, in the scan transform to carry out interpolation operations, motion prediction and compensation, as well as scanning and so on. Now high-end large-scale LED screen also use this method, and more image signal processing, trying to upgrade the signal to the broadcast level, of course, the effect is better. Computer images have to go through this processor, and then sent to the big screen display. Processing technology is constantly evolving, and many new algorithms have been proposed. We are familiar with the large size of the rear projection TV and plasma large-screen TV are widely used in this method, the effect is much better than ordinary TV. In this case, the output signal is usually described in terms of the transformed signal format, which is more precise.
Another method is the multimedia method, commonly referred to as a synchronous screen method, which uses a conventional multimedia card to capture television signals and demodulates, filters and separates sound. After the video signal is A / D converted, the MPEG code is compressed for storage. Play and then decompression, directly on the computer monitor to watch. Sent to the big screen signal through a dedicated interface card from the computer's DVI interface or graphics card access, the interface card will also be some processing. At this time, the big screen is actually equivalent to the computer monitor or part of it, usually called the window, you can achieve one by one corresponding to the synchronous display. As the computer monitor is progressive scan, so if there is no signal sent to the pumping line pumping processing, then the large-screen display format is the monitor format.
For example, the VGA format is a progressive scan format of 640x480 pixels with a scan update rate of 75Hz. But here the 75Hz progressive scan signal, not the image source itself to enhance the quality of the image did not improve, in fact, worse than 50Hz interlaced level, similar to the DVD or VCD effect, which is often confused The place. As for some of the screen for a picture of the exchange, for example, even the occasional screen information discarded only odd information sent to the display, the effect of course worse. Incidentally, non-video programs are relatively simple, although some of the game animation also requires a good continuity, but for the big screen to play the animation, the screen update rate of more than 10Hz can accept.
By the embedded controller or microcontroller control of the display screen, the program generated by the controller, the controller processing capacity constraints, providing the screen speed is not fast enough, will cause the screen is not continuous. The most typical phenomenon is that the screen controlled by the microcontroller, when the text left or right shift, is not smooth but jumping. Experience and calculation can be obtained by a 10 16XI6 dot matrix Chinese characters composed of the bar screen, if the whole picture to 5 seconds to the left, in order to move smooth and coherent, its frame frequency must reach more than 15Hz.