DVI interface

DVI is called the Digital Visual Interface. It was formed in 1999 by Silicon Image, Intel, Compaq, IBM, HP, NEC, and Fujitsu. Digital Display Workgroup) introduced interface standards. It is based on the technology of the PanalLink interface of Silicon Image, based on the TMDS (Transition Minimized Differential Signaling) electronic protocol as a basic electrical connection. TMDS is a differential signal mechanism that can encode pixel data and pass it through a serial connection. The digital signal generated by the video card is encoded by the transmitter in accordance with the TMDS protocol and sent to the receiver over the TMDS channel, which is then decoded and sent to the digital display device. A DVI display system includes a transmitter and a receiver. The transmitter is the source of the signal, which can be built into the graphics chip, or it can appear on the graphics card PCB in the form of an additional chip; and the receiver is a circuit on the display, it can accept digital signals, decode it and pass it Through the digital display circuit, the signal from the video card becomes the image on the display.

The current DVI interface is divided into two types. One is a DVI-D interface, which can only receive digital signals. There are only 3 rows and 8 columns on the interface with 24 pins in total. One of the pins in the upper right corner is empty. Not compatible with analog signals.

The other is a DVI-I interface that is compatible with both analog and digital signals. Compatible analog Fortunately, it does not mean that the analog signal interface D-Sub interface can be connected to the DVI-I interface, but must use an adapter to use, generally using this interface of the graphics card will have the relevant adapter.

Taking into account the compatibility issues, the current graphics card will generally use the DVD-I interface, this can be connected to the ordinary VGA interface through the adapter. The monitor with DVI interface generally uses a DVI-D interface, because such a monitor generally has a VGA interface, so no DVI-I interface with analog signals is required. Of course, there are a few exceptions, some monitors only DVI-I interface and no VGA interface. The DVI interface of the display device has the following two major advantages:

First, the speed of DVI transmission is a digital signal, digital image information without any conversion, it will be directly transmitted to the display device, thus reducing the digital → analog → digital cumbersome conversion process, greatly saving time, so it The speed is faster, the smear phenomenon is effectively eliminated, and DVI is used for data transmission, the signal is not attenuated, the color is more pure and more realistic.

Second, the screen clear computer internal transmission is a binary digital signal, the use of VGA interface to connect the LCD display, then you need to first pass the signal through the graphics card D / A (digital / analog) converter into R, G, B three primary color signals and Line and field synchronization signals. These signals are transmitted to the liquid crystal through analog signal lines. The corresponding A/D (Analog/Digital) converters are required to convert the analog signals into digital signals again to display images on the LCD. In the above-mentioned D/A, A/D conversion and signal transmission process, it is inevitable that signal loss and interference will occur, resulting in distortion of the image or even displaying an error. However, the DVI interface does not need to perform these conversions to avoid loss of the signal. The sharpness and detailed expression of the images have been greatly improved.

Finally, the DVI interface can support the HDCP protocol, laying the groundwork for high-definition video with copyright. However, if you want the video card to support HDCP, the DVI interface alone is not enough, you need to install a dedicated chip, but also pay Feifei HDCP certification fees, so the current true support for HDCP protocol graphics card is not much.