Computer LCD display simulation and digital interface detailed

Analog Interface

The analog signal input to the TFT-LCD display device to show itself is a very ridiculous thing. The computer is running data, including image information, which is converted to analog signals on the display card, then transmitted to the monitor via the connector, and then displayed as a digital signal on the monitor, which is completely superfluous. And the consequences of this is clear, one is to increase the additional hardware overhead, the second is in the signal conversion process inevitably has the loss, the final impact of the display of the image quality. Therefore, the digital signal interface is suitable for liquid crystal display. However, the reality of the market is not necessarily true. At present, most of the liquid crystal display in the market or analog signal interface, the fundamental reason is that the norms and standards are not unified.

　　Digital interface

The standard for digital interfaces for liquid crystal displays is LVDS, TDMs, Gvif, P&d, DVI and DFP, in which case it is difficult for the manufacturer to determine what the user's inclination is. In the 80 's, similar phenomena had occurred, with VHS, Beta and Video2000 in the format of the tape, and the final result was that the VHS standard unified the market, while the technically leading Beta standard fell.

　　Direction of the interface

It is not yet conclusive what kind of standards will eventually be applied uniformly. However, from a technical point of view to analyze. When the digital interface technology used in the display is not yet available, the analog interface of the liquid crystal display dominates the market is taken for granted, and because the standard is not uniform and the problem of the display card manufacturing also slows down the analog interface is eliminated. From the current point of view, analog interface of the liquid crystal display technology is backward, but in the market has been successful in sales. The biggest cause of this phenomenon should be that the application of liquid crystal display is often some special requirements of the occasion, and often is a whole configuration plan part of the buyers are often large companies, schools, government agencies, the military sector. For these units, they often have a ready-made hardware system, these units to buy liquid crystal displays are often designed to upgrade the original CRT monitor, so they naturally hope that the newly purchased LCD monitor directly connected to the original graphics card VGA interface. In this way, it is difficult to upgrade to the digital interface again.

　　The comparison of two kinds of interfaces

Analog interface of TFT display also has one of the biggest weakness is in the display of the phenomenon of pixel flicker, this phenomenon occurs because the clock frequency and the input analog signal is not 100% synchronized, resulting in a small number of pixels flashing. This is more noticeable when displaying characters and lines. and the digital interface TFT does not have the clock frequency and analog signal tuning problem, which means that the digital interface of TFT-LCD, to adjust only brightness and contrast.

　　Digital interface

　　Advantages

No analog-to-digital conversion, signal attenuation in the process of digital mode conversion

No need for clock frequency, vector adjustment

Low price, reduced circuit and component

　　Disadvantages

At present, there are at least three interface standards (P&D, DFP and DVI)

Need a video card with a digital display to work with

　　Analog interface

　　Advantages

Fully compatible with the current computer standard VGA video signal interface

No need to buy a special video card

　　Disadvantages

In order to avoid the occurrence of pixel flicker, must be done to the clock frequency, vector and analog signal exactly the same

The signals transmitted in the cable are susceptible to interference

Inside the monitor to add the circuit responsible for analog-to-digital conversion

Unable to upgrade to digital interface