LED screen splicing technology explanation

218 views admin 2023-10-19

With the pixel pitch of the LED display getting smaller and the viewing distance getting closer, in order to achieve excellent display effect, not only requires the LED display itself to improve on the image processing and assembly process, but also puts forward higher requirements for the image splicing processor (hereinafter referred to as the splicer) at the front end of the LED display:

(1) Verify the synchronization of the output to avoid the phenomenon of unsynchronization of the splicing screen;

(2) Optimize the image processing algorithm, so that the zoom processing of the image to maintain high definition;

(3) Customize the output resolution to deal with the irregular physical resolution of the LED display.

A key application of the splicer is that it can output multiple DVI signals and splice multiple display screens arranged in a matrix to make it a complete display area logically.

For LED display, we can define the display area driven by an LED controller as an independent LED display. The current LED controller uses DVI/HDMI as the signal input interface, supporting a maximum input resolution of 1920×1200@60Hz and a maximum bandwidth of 165MHz. The maximum physical resolution of the driven LED display is 1920×1200.

As the display area of LED small pitch products is getting larger and larger, dozens of square meters of projects are common, the physical resolution of LED display is often more than 1920×1200, that is, each large LED display is composed of a number of independent display areas driven by a number of LED controllers, for the application of splicer, It is only necessary to provide a number of DVI output interfaces corresponding to the number of LED controllers, and the entire LED screen can be spliced.

In the application of small-pitch LED display, there are several key technologies worth paying attention to:

In the multichannel DVI signal output of the splicer, there must be the problem of signal synchronization. The asynchronous signal is output to the LED display, and the picture tearing phenomenon will appear at the splice, which is especially obvious when playing high-speed moving images. How to ensure the output synchronization of the signal becomes the key to measure the success or failure of a splicing system.

We know that the point-to-point image display effect is the best, after the reduction of the image, if only the use of ordinary graphics processing technology or general FPGA graphics processing algorithm, the edge of the image will appear jagged, and even pixel loss, the brightness of the image will decline. The high-end image processing chip or the FPGA system using complex graphics processing algorithms will maximize the display effect of the reduced image. Therefore, a good graphics processing algorithm is a key technology for a splicer applied to a small-pitch LED display.

The small-pitch LED display is composed of a matrix of display units of the same specifications, and the size and physical resolution of each display unit is fixed, but the entire large screen is spliced together, often not a standard physical resolution. For example, the resolution of the display unit is 128×96, which can only spell 1920×1152, but cannot spell 1920×1080. In a very large scale splicing system, the LED display area driven by each LED controller may not be the standard resolution, at this time, the splicing device has a non-standard resolution output is key, it can help us quickly find the right splicing method, so as to allocate resources reasonably, effectively save the use of LED controller and transmission equipment.

The whole machine structure usually adopts the design of "backplane + signal acquisition board + main control board + signal output board". The signal acquisition board performs signal processing work such as video acquisition, scaling, superposition and format conversion, and transmits the processed signal to the FPGA signal processing system of the main control board through the backplane bus. Through the embedded ARM system, the main control FPGA configuration, communication with the upper PC, data exchange between the system and other functions are realized, and the signal is output to the display terminal through the signal output board.