DVI – For High Quality Digital Displays




Basic

The brainchild of the Digital characterize Working Group (DDWG) the DVI (digital video interface) has dramatically changed the image quality of characterize devices, from LCDs to computer monitors to projectors.

The Need for DVI

Before DVI, the standard used was the Video Graphics range (VGA), and was intended for the use on CRT monitors. The basic course of action involved a source that emits horizontal lines of the image, at the same time it changes the output voltage according to certain brightness levels.

The CRT, which receives this transmission, changes the electron beam while scanning the characterize monitor.

This approach could not work with digital displays, because every pixel there had to be sampled to get an accurate characterize.

How DVI Works

With the Digital Video Interface, distortion no longer presented a problem. Instead of just adjusting the output voltage to determine brightness, DVI takes the brightness of every pixel and puts in a binary code.

Using this method, all the pixels in the source will match correctly with those in the characterize. This allows for a noise and distortion free screen.

The Technology of DVI

The DVI utilizes a format based on the Pnnel Serial which makes use of the change reduced Differential Signaling (TMDS).

All the wires in a DVI (colored red, green and blue and one a clock signal) transmit 24 bits for every pixel. With intervals, the picture images are sent line by line without any form packets. Another advantage of DVI is that it does not use any compression, which was a problem that affected older technologies.

DVI Links

One DVI link can sustain a maximum resolution of 2.6 megapixels at 60Hz, but it has the capability to use other links if the resolution is going to be much higher. consequently there are two modes, the single link, for those displays that require less than 2.6 megapixels, and dual link mode, for that need more megapixels. The dual link mode is also sued when more than 24 pixel bits are needed.

DVI Connectors

Unlike LDVS and Open LDI, DVI provides sustain for digital and analog transmissions. The DVI connectors are consequently classified into the following: DVI-A (DVI Analog), DVI-I (DVI Digital and Analog) and DVI-D (DVI Digital). The DVI-D can, in some instances, work with HDMI (High definition Multimedia Interface).

DVI Specifications

The minimum clock frequency for DVI is 25.175Mhz, and its maximum has been set to 165Mhz. In dual link mode however, the limit is set only by the cable. The pixels per clock cycle for single mode is 1, and for dual link 2. The bits per pixel is set at 24 while in dual mode it is 48.

DVI characterize Modes

For single link, the following displays are possible:
HDTV (1920 × 1080) (60Mhz); UXGA (1600 × 1200) (60Mhz); SXGA (1280 × 1024) (159 MHz); WXGA+ (1440 x 900) (107 MHz) and WQUXGA (3840 × 2400) (164 MHz)

For dual links:

QXGA (2048 × 1536) (2×170 MHz); HDTV (1920 × 1080) (2×126 MHz); WQXGA (2560 × 1600) (2×174 MHz); WQXGA (2560 × 1600) (2×135 MHz) and (WQUXGA (3840 × 2400) (2×159 MHz)




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