VGA (Video Graphics Array) is a video graphics array, which has the advantages of high Resolution, fast display rate, and rich colors. The VGA interface is not only a standard interface for CRT Display devices, but also a standard interface for LCD( liquid crystal Display devices), which has a wide range of applications.
With the development of the electronics industry and video image processing technology, vga (Video Graphics Array) as a standard display interface has been widely used in the video and computer fields. In image processing, if traditional data transmission methods are used to make high The Resolution image is displayed on the monitor in real time, and the crystal oscillator frequency is generally required to be above 40MHz, which is difficult for traditional electronic circuits. If a special image processing chip is used, its design difficulty and high development cost become a bottleneck choice.
The vga interface is a D-type interface with a total of 15 pin holes, divided into three rows, five in each row. Among them, in addition to 2 NC (Not Connect) signals, 3 Display data buses and 5 GND signals, the more important ones are 3 RGB color component signals and 2 scan synchronization signals HSYNC and VSYNC pins. The color component in the VGA interface adopts the rs343 level standard. The peak voltage of rs343 level standard is 1V. vga interface is the most widely used interface type on graphics cards, and most graphics cards have this kind of interface. Some graphics cards that do not have a VGA interface but have a DVI (Digital Visual Interface) interface can also convert the DVI interface to a vga interface through a simple adapter. Usually, the graphics card without a VGA interface will come with such an adapter. .
Most computers and external display devices are connected through an analog vga interface. The Display image information generated in a digital manner inside the computer is converted into R, G, B three primary color signals and line and field signals by the digital/analog converter in the graphics card. Synchronization signal, the signal is transmitted to the display device through the cable. For analog Display devices, such as analog CRT displays, the signal is directly sent to the corresponding processing circuit, which drives and controls the picture tube to generate images. For digital display devices such as LCD and DLP, the Display device needs to be equipped with a corresponding A/D (analog/digital) converter to convert analog signals into digital signals. After D/A and A/D conversion twice, some image details are inevitably lost. It is understandable that the VGA interface is used in CRT monitors, but when used to connect display devices such as liquid crystals, the image loss during the conversion process will slightly reduce the Display effect.