|LED display terminology-Large Seamless Video Wall Indoor Walls LED Large Display screen panels|
Color: The red and green LEDs are put together as a pixel. The display screen is called a two-color screen or a color screen. The red, green and blue LED tubes are put together as a pixel display screen called a three-color screen or a full-color screen. .
Pixels: The pixel size of the indoor LED screen is generally 2-10 mm, and it is often used to package several LED dies that can produce different primary colors. The outdoor LED screen has a pixel size of 12-26 mm, and each pixel is composed of a plurality of various single-color LEDs. The common finished product is called a pixel tube. The two-color pixel tube is generally composed of 3 red 2 green, and the three-color pixel tube is composed of 2 red 1 green 1 blue. Regardless of whether a single-color, two-color or three-color screen is made with LEDs, the brightness of each LED that needs to constitute a pixel must be adjustable. The fineness of the adjustment is the gray level of the display. The higher the gray level, the finer the displayed image and the richer the color, and the more complex the corresponding display control system. Generally, the image of 256-level gray scale has a very soft color transition, while the color image of 16-level gray scale has a clear color transition boundary. Therefore, color LED screens are currently required to be 256-level grayscale.
Display speed: refers to the speed at which the LED display updates and converts the picture, usually expressed in frames per second.
Interface: VGA input interface: VGA interface adopts asymmetrically distributed 15pin connection mode. Its working principle is to image the image (frame) signal stored in digital format in analog memory into analog high frequency signal in RAMDAC, and then output. To plasma imaging, the VGA signal is at the input (in the LED display) and does not have to be converted by the matrix decoding circuit like other video signals. From the previous video imaging principle, the video transmission process of VGA is the shortest, so the VGA interface has many advantages, such as no crosstalk and no circuit synthesis separation loss.
DVI input interface: The DVI interface is mainly used to connect with a computer graphics card with digital display output function to display the RGB signal of the computer. The DVI (Digital Visual Interface) digital display interface is a digital display interface standard developed by the Digital Display Working Group (DDWG), which was established at the IntEL Developer Forum in September 1998.
The DVI digital terminal is better than the standard VGA terminal signal. The digital interface ensures that all content is transmitted in digital format, ensuring the integrity of the data during the transmission from the host to the monitor (no interference signal is introduced), and a clearer image can be obtained.
Standard video input (RCA) interface: also known as AV interface, usually a pair of white audio interface and yellow video interface, it is usually connected by RCA (commonly known as lotus head), only need to take the lotus head with The standard AV cable can be connected to the corresponding interface. The AV interface enables separate transmission of audio and video, which avoids image quality degradation due to audio/video mixing interference, but the AV interface still transmits a video with a mixed luminance/chroma (Y/C). The signal still needs the display device to perform bright/color separation and chrominance decoding to image. This process of mixing and then separating will inevitably cause loss of color signal, and the chrominance signal and the luminance signal will have a great chance to interact with each other. Interference thus affects the quality of the final output image. AV also has a certain vitality, but due to its insurmountable shortcomings of Y/C mixing, it cannot be used in some situations where visual limits are pursued.
S-Video Input: S-Video's full English name is Separate Video. In order to achieve better video effects, people began to explore a faster and better resolution video transmission method. This is the current S-Video (also known as S-Video). Two-component video interface), the meaning of Separate Video is to separate the Video signal, that is, the chrominance signal C and the luminance signal Y are separated on the basis of the AV interface, and then transmitted in different channels, which appears and develops. In the late 1990s, a standard 4-core (without sound) or an extended 7-core (with sound) was used. Graphics cards and video devices with S-Video interfaces (such as analog video capture/editing card TVs and quasi-professional monitors TV cards/TV boxes and video projection devices, etc.) are now more common, compared to AV interfaces because it is not Then Y/C hybrid transmission is performed, so there is no need to perform bright color separation and decoding work, and the use of independent transmission channels largely avoids image distortion caused by signal crosstalk in the video device, greatly improving the image. Sharpness, but S-Video still needs to mix two color difference signals (Cr Cb) into one chrominance signal C, transmit it and then decode it into Cb and Cr in the display device for processing, so that it still brings some signal. Loss and distortion (this distortion is small but can still be found when tested under strict broadcast-quality video equipment), and the bandwidth of the chrominance signal is limited due to the mixing of Cr Cb, so S-Video is already It's better, but it's still far from perfect. S-Video is not the best, but considering other factors such as current market conditions and overall cost, it should still be Use the most popular video interface.
Video color difference input interface: At present, you can see the interface identification of YUV YCbCr Y/BY/BY and other markings on some professional video workstations/editing card professional video equipment or high-end DVD players, although the marking method and connector shape Different but all refer to the same interface color difference port (also known as component video interface). It usually uses two symbols, YPbPr and YCbCr, the former represents the progressive scan color difference output, and the latter represents the interlaced color difference output. From the above relationship, we only need to know the value of Y Cr Cb to get the value of G (that is, the fourth equation is not necessary), so the green difference Cg is uniformly ignored in the video output and color processing and only retained. Y Cr Cb , which is the basic definition of color difference output. As an advanced product color difference output of S-Video, the chrominance signal C transmitted by S-Video is decomposed into color differences Cr and Cb, thus avoiding the process of mixing and decoding the two-way color difference and again separating the chroma channel. The bandwidth can be restored to the RGB three primary color signals only through the inverse matrix decoding circuit, which minimizes the video signal channel between the video source and the display imaging, and avoids the image caused by the cumbersome transmission process. Distortion, so the interface mode of the color difference output is the best one of the various video output interfaces.
BNC port: A connector commonly used for workstation and coaxial cable connections, standard professional video equipment input and output ports. The BNC cable has 5 connectors for receiving red, green, blue, horizontal sync and vertical sync signals. The BNC connector has a special display interface that is different from the normal 15-pin D-SUB standard connector. It consists of five primary color signals of R, G and B, and five independent signal connectors for line synchronization and field synchronization. It is mainly used to connect workstations and other systems that require high scanning frequency. The BNC connector can isolate the video input signal, so that the interference between the signals is reduced, and the signal bandwidth is larger than that of the ordinary D-SUB, which can achieve the best signal response.
RS232C serial port: The full name of RS-232C standard (protocol) is EIA-RS-232C standard, of which EIA (Electronic Industry Association) stands for American Electronics Industry Association, RS (ecommeded standard) stands for recommended standard, 232 is identification number, C stands for RS232 The latest revision (1969), before this, there are RS232B, RS232A. . It specifies the connection cable and mechanical, electrical characteristics, signal functions and transmission processes. Common physical standards are EIA RS-232-C, EIA RS-422-A, EIA RS-423A, EIA RS-485. Only EIA RS-232-C (232, RS232) is introduced here. Computer input and output interface, is the most common serial interface, RS-232C standard interface has 25 lines, 4 data lines, 11 control lines, 3 timing lines, 7 spare and undefined lines, commonly used only Nine, commonly used with 25-pin D-sub ports, with a maximum transfer rate of 20kbps and a cable length of up to 15 meters. The RS232C port is used to input computer signals into the control LED display.
Communication distance: The signal input of the general P3.91 LED display is a microcomputer or other equipment. The display has a distance from the signal input device. Therefore, the LED display must support the input and restore of the remote signal. Basically all LED displays support it. Signal input above 10 meters.
Lifetime: Usually the LED display is used outdoors, so the LED display can adapt to the outdoor variable environment, and it is better than other display devices in anti-aging and trouble-free operation. Generally, the normal and trouble-free use time can reach more than 5000 hours.
LED display: LED display: LED is the light emitting diode, the abbreviation of LED, referred to as LED. It is a display screen for displaying various information such as text, graphics, images, animations, quotes, videos, video signals, etc. by controlling the display mode of the semiconductor light-emitting diodes.
The LED display is divided into a graphic display and a video display, both of which are composed of LED matrix blocks. The graphic display can display Chinese characters, English text and graphics synchronously with the computer; the video display screen is controlled by a microcomputer, and the pictures and images are displayed together, and various information can be played in real-time, synchronous and clear information dissemination mode, and the second display can also be displayed. Dimensions, 3D animation, video, TV, VCD shows and live live. The LED display screen has bright colors, strong stereoscopic effect, and is as static as oil painting. It is widely used in stations, terminals, airports, shopping malls, hospitals, hotels, banks, securities markets, construction markets, auction houses, industrial enterprises and Other public places.
Its advantages: high brightness, low operating voltage, low power consumption, miniaturization, easy to match with integrated circuits, simple drive, long life, impact resistance, and stable performance.