The combined LED lattice display takes the light emitting diode as the graphic element. It combines the arrays with high brightness LED chips, and then is packaged through epoxy resin and plastic mold. It has the characteristics of high brightness, low power consumption, fewer pins, large viewing angle, long life, moisture resistance, heat and cold resistance, corrosion resistance and so on.
The lattice display has two kinds: monochrome and bichrome, which can display red, yellow, green, orange and so on. LED dot matrix has 4 *4, 4 *8, 5 *7, 5 *8, 8 *8, 16 *16, 24 *24, 40 *40 and so on. According to the number of pixels, it can be divided into two primary colors, three primary colors, and so on. According to the different color of the pixels, the color of text, image and other contents is different. Single primary color dot matrix can only display fixed colors such as red, green, yellow and so on. The color of the display content is determined by the combination of different light emitting diodes in the primitive, such as yellow when both red and green are bright, and 256 or higher gray level display can be realized if the light-up time of the two primitive and three primitive colors is controlled by pulse mode, so that the true color display can be realized.
The internal circuit structure and external specifications of several kinds of LED dot matrix display, and the structure and pins of other types of dot matrix display can be obtained by experiment. When using a single LED dot matrix display, it can not only replace the digital tube to display digits, but also display various Chinese and Western characters and symbols, such as 5x 7 dot matrix display for displaying Western letters and 5 X8 matrix display. It is used for displaying Chinese and Western languages, 8 x 8 matrix for displaying Chinese characters, and graphic display. A large screen display can be made up of multiple dot matrix displays, but this kind of practical device is usually controlled and driven by a microcomputer or a single chip computer.
According to the internal structure of LED dot matrix display, the device should work by dynamic scanning drive mode. Because most of the LED core is of high brightness type, narrow pulse can be used for driving current of single LED in a row or a column, but its average current should be limited to 20 mA. The forward voltage drop of single LED in most dot matrix display is about 2V left. Right, but the forward voltage drop of the dot matrix display single LED with big bright spot 10 is about 6V.
Large screen display system is generally composed of small modules composed of multiple LED lattices and built-up blocks. Each small module has its own independent control system. When combined, only one master controller is introduced to control the commands and data of each module. This method is simple and easy to develop. Easy to maintain.
There are static and dynamic display modes for each module in the LED dot matrix display system. The principle of static display is simple and easy to control, but the hardware wiring is complex. In practical application, dynamic display is usually operated by scanning mode, driven by narrow pulse with larger peak value. The lines of display screen are continuously gated from top to bottom, and at the same time, graphics or graphs are sent to columns. Pulse signal of text information can display all kinds of graphics or text information by repeating the operation above.