[Home Theater Network HDAV.com.cn] The projector enters the home, which can make the big picture bring us unlimited fun. But the projection equipment is too professional, especially the interface behind it, which is seen by many people. In the face of that strange interface, we have to study what devices are linked, what are the characteristics of each interface?
VGA input:
The VGA interface adopts an asymmetrically distributed 15 pin connection. The working principle is that the image (frame) signal stored in the digital format in the video memory is analog-modulated into an analog high-frequency signal in the RAMDAC, and then output to the projector for imaging. The VGA signal is at the input (inside the projector) 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:
The DVI interface is mainly used to connect to 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):
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 connect the standard AV cable with lotus head to the corresponding interface. Get it up. 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 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 the 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 respectively. It appears and develops in the last century. In the late 0's, 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:
At present, you can see the interface identifiers of YUV YCbCr Y/BY/BY and other markings on some professional video workstations/editing card professional video equipments or high-end DVD players, although their marking methods and joint shapes are different but they are all Refers 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 input:
Connectors 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 the RS-232C standard (protocol) is the EIA-RS-232C standard, in which EIA (Electronic Industry Association) represents the American Electronics Industry Association, RS (ecommeded standard) represents the recommended standard, 232 is the identification number, and C represents the latest RS232. Modified (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 projector. More fresh and fun home theater information, please pay attention to home theater network (WeChat: cnhifi) http://, the country's most influential home theater audio player interactive media website.
High-quality manufacturer and supplier of column sensors and accessories in China.
It is made of alloy steel and stainless steel. The elastic body is cylindrical, cylindrical, and cylindrical ring structure. It is used for the measurement of tensile force and compression force. It has a fully sealed structure, a wide range, stable and reliable performance, and easy installation and use. Tension and compression load. It is suitable for all kinds of force measurement and industrial automation measurement control system in the city. For example, truck Scales, hopper scales, railroad scales, testing machines, warehouse measurement, etc.
Compression Load Cell,Tank Weighing Load Cell,Silo Weighing Load Cell,Concrete Mixing Load Cell
Ningbo Santwell Imp & Exp Co.,Ltd , https://www.santwell.com