LED display

LED display is a kind of flat panel display, which is composed of small LED module panels. It is used to display text, image, video and other information. [1]
LED electronic display screen integrates microelectronics technology, computer technology and information processing. It has the advantages of bright color, wide dynamic range, high brightness, long service life, stable and reliable operation. LED display screen is widely used in commercial media, cultural performance market, stadium, information dissemination, news release, securities trading, etc., which can meet the needs of different environments. [2-3]
Chinese name led display screen and foreign name LED displayer constitute LED module to display text, image, video, etc. Features: bright color, wide dynamic range, high brightness, long life, stable and reliable operation, etc. Application of commercial media, stadiums, information dissemination, etc.
1 background
2. Basic principles
3 Classification
4 performance characteristics
5 technical advantages
6 performance index
▪  Color, brightness and viewing angle
▪  Gray scale
▪  contrast ratio
▪  refresh frequency
7 key technologies
▪  Image acquisition
▪  Color reproduction of real image
▪  Brightness control D / T conversion
▪  Data reconstruction and storage
▪  ISP in logic circuit design
8 precautions
Background editing
LED display screen is an electronic display screen composed of LED dot matrix. It changes the content form of the screen display such as text, animation, picture and video by changing the red and green light beads on and off, and controls the component display through the modular structure. It is mainly divided into display module, control system and power supply system. The display module is composed of LED light dot matrix to make the screen light up; the control system is to realize the conversion of the display content in the control area; the power system is to convert the input voltage and current to meet the needs of the display screen. [3]
LED screen can realize the transformation of various information presentation modes in different forms, and can be used indoors and outdoors, with incomparable advantages over other display screens. With the characteristics of high brightness, low power consumption, low voltage demand, small and convenient equipment, long service life, stable impact resistance and strong external interference resistance, it has been developed rapidly and widely used in various fields. [4]
The luminous color and efficiency of LED are related to the material and process of making LED. At the beginning, the lamp ball is all blue light, and then the phosphor is added. According to the different needs of users, different light colors are adjusted. There are four widely used colors: red, green, blue and yellow. Due to the low working voltage (only 1.2 ~ 4.0V), the LED can actively light up and have a certain brightness, the brightness can be adjusted by voltage (or current), and it is shock resistant, vibration resistant and long life (100000 hours), so there is no other display mode comparable to LED display mode in large display equipment. [1]
LED, light emitting diode. It is a diode made of gallium (GA) and arsenic (as), phosphorus (P), nitrogen (n), indium (in) by controlling the display mode of semiconductor light-emitting diodes. When electrons and holes compound, it can radiate visible light, so it can be used to make light-emitting diodes. In circuits and instruments as indicator lights, or composition of text or digital display. Gallium arsenide diodes emit red light, gallium phosphide diodes emit green light, silicon carbide diodes emit yellow light, and indium gallium nitrogen diodes emit blue light. [1]
The display screen made by putting the red and green LED chips or tubes together as one pixel is called tricolor or bicolor screen, and the display screen made by putting the red, green and blue LED chips or tubes together as one pixel is called tricolor screen or full color screen. If there is only one color, it is called monochromatic or monochromatic screen. The pixel size of the indoor LED screen is generally 1.5-12mm. Several kinds of LED cores that can produce different primary colors are often used to package into one. Outdoor LED The screen's pixel size is mostly 6-41.5mm, each pixel is composed of several kinds of monochromatic LED, the common finished product is called pixel cylinder, the two-color pixel cylinder is generally composed of 2 red and 1 green, and the three-color pixel cylinder is composed of 1 red, 1 green and 1 blue. [1]
No matter how to make a monochrome, bicolor or tricolor screen with LED, the brightness of each LED that needs to form a pixel to display an image must be adjustable, and the fine degree of adjustment is the gray level of the screen. The higher the gray level, the more delicate the displayed image, the richer the color, and the more complex the corresponding display control system. Generally, the color transition of 256 gray level image is very soft, while the color transition boundary of 16 gray level image is very obvious. Therefore, color LED screens are currently required to be made of 256 to 4096 levels of gray. [1]
Fundamentals editing
LED display is a new type of information display media, which uses LED lattice
Figure 2 8 × 8 lattice LED display structure
Figure 2 8 × 8 lattice LED display structure
Flat display screen composed of modules or pixel units. Figure 2 shows the structure diagram of 8 × 8 lattice LED display screen. From the diagram, 64 light-emitting diodes are required for 8 × 8 lattice, and each light-emitting diode is placed at the intersection of the line and the line. When a line is set with high level and a line is set with low level, the corresponding diode is on. [5]
For example, to display the text, you can light up the corresponding diode according to the strokes of the text, so as to achieve the purpose of displaying the text, as shown in Figure 3. The complete lattice can be composed of 16 × 16, 32 × 32 display modules. [5]
Each pixel of single primary LED display consists of one single LED, i.e. each pixel contains one LED; double primary LED