A 4 DVI

Digital Visual Interface

Delivering the DVI Digital Interface to the CRT Monitor

As we move into the 21st century, digital displays, such as LCD flat panel monitors, will
be ubiquitous, linked to everyday electronic appliances from desktop computers to DVD
players to set-top boxes. To realize this vision, the PC industry adopted a digital
interface standard called DVI (Digital Visual Interface) to link digital video/graphics
sources to digital displays. By the end of this year, we’ll either own a DVI digital-ready
PC, or know someone that does. To take advantage of the highest possible image
quality and new functionally that the DVI interface offers, CRT monitor makers are
going digital. The first production DVI-compliant digital CRTs will be available in the
first quarter of 2000. This first generation of digital CRTs will employ an architecture
that allows the digital interface to be easily added to existing analog CRT designs.

Why turn a CRT digital?

It is easy to realize the advantages of using an all-digital interface in a display such as a
LCD flat panel monitor. Since the LCD is an inherently digital device, the analog interface
degrades the LCD’s image quality with the required conversion of the PC’s video signal
from digital to analog, then sampling and attempting to reconstruct the original digital
signal. Not only is the image quality degraded in this architecture, but cost is added with
the digital-to-analog and analog to digital converters and associated electronics.
The CRT monitor, on the other hand, is an inherently analog display that ultimately
requires an analog signal input, so the digital video data must be converted to analog
at one point in the link. Until now, this conversation has been done in the graphics
controller chip. CRT monitor makers report that the leading cause of monitor image
complaints is due to the quality of the analog output from the PC’s graphics controller
on the PC motherboard or video add-in board. The analog signal from the graphics
controller chip is still subject to further degradation from required EMI suppression
filters and the video cable itself, all of which act as filters which can distort the
waveform and affect the voltage levels. Unfortunately for the CRT monitor maker, such
an interface and architecture makes it impossible for the monitor to control its image
and quality and offer aconsistent visual experience to the user as the video signal
quality itself is inconsistent.

The LMP A 4 DVI provides an analog RGB and
Sync output of the DVI Data-stream in resolutions
up to UXGA (1600x1200), with the optimum CRTresolution
of SXGA (1280x1024) at a 85 Hz frame
rate.