DVI, known as Digital Visual Interface, is an interface standard introduced by DDWG (Digital Display Working Group) in 1999 by Silicon Image, Intel (Intel), Compaq (Compaq), IBM, HP (HP), NEC, Fujitsu (Fujitsu) and other companies. It is based on Silicon Image's PanalLink interface technology, and based on TMDS (Transition Minimized Differential Signaling) electronic protocol as the basic electrical connection.TMDS is a differential signal mechanism, which can encode pixel data and transmit it through serial connection. The digital signal generated by the graphics card is encoded by the transmitter according to TMDS protocol and sent to the receiver through TMDS channel, and then decoded to the digital display device. A DVI display system consists of a transmitter and a receiver. The transmitter is the source of the signal, which can be built in the graphics card chip, or can appear on the graphics card PCB in the form of additional chips; while the receiver is a circuit on the display, which can accept the digital signal, decode it and transmit it to the digital display circuit. Through these two, the signal emitted by the graphics card becomes the image on the display.

　　At present, there are two kinds of DVI interfaces. One is the DVI-D interface, which can only receive digital signals. There are only three rows and eight columns of 24 pins on the interface. One pin in the upper right corner is empty. Not compatible with analog signals.

　　The other is the DVI-I interface, which can be compatible with both analog and digital signals. Compatible analog does not mean that the analog signal interface D-Subinterface can be connected to the DVI-I interface, but can only be used through a conversion connector. Generally, graphics cards using this interface will have relevant conversion connectors.

　Considering the compatibility problem, DVD-I interface is usually used in graphics cards at present, which can be connected to ordinary VGA interface through conversion connector. Displays with DVI interfaces generally use DVI-D interfaces, because such displays usually have VGA interfaces, so there is no need for DVI-I interfaces with analog signals. Of course, there are a few exceptions. Some displays have only DVI-I interface but no VGA interface. There are two main advantages of using DVI interface in display devices:

1. Fast speed

DVI transmits digital signals. Without any conversion, digital image information will be directly transmitted to the display device, thus reducing the cumbersome conversion process from digital to analog to digital, greatly saving time. Therefore, it is faster and effectively eliminates the shadow phenomenon, and uses DVI for data transmission. The signal has no attenuation, and the color is more pure and lifelike.

2. Clear picture

The internal transmission of computer is binary digital signal. If using VGA interface to connect LCD, it is necessary to transform the signal through D/A (digital/analog) converter in display card into R, G, B primary color signal and line and field synchronization signal. These signals are transmitted to LCD through analog signal line, and the corresponding A/D (analog/digital) converter is also needed to transfer analog signal to LCD and then to analog signal. The image can be displayed on the LCD only when it is converted into a digital signal at one time.In the above D/A, A/D conversion and signal transmission process, signal loss and interference will inevitably occur, leading to image distortion and even display errors. DVI interface does not need these transformations to avoid signal loss, so that the image clarity and detail performance are greatly improved.

　　Finally, DVI interface can support HDCP protocol and lay a foundation for future viewing copyrighted HD video. However, in order to support HDCP, only DVI interface is not feasible. Special chips need to be installed, and a lot of HDCP authentication fees need to be paid. So there are not many graphics cards that really support HDCP protocol at present.