LCD Monitors Leap Forward

LCD monitors continue to make tremendous strides in the broadcast industry with all of the usual reasons for not deploying an LCD in lieu of a CRT now falling like dominos.
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SAN FRANCISCO
LCD monitors continue to make tremendous strides in the broadcast industry with all of the usual reasons for not deploying an LCD in lieu of a CRT now falling like dominos.

Possibly the biggest milestone of the CRT-to-LCD transition has now been crossed—over the past year, a number of 23- and 24-inch LCD reference monitors have begun to appear on the market.

And, in one case, a major manufacturer launched a HD reference monitor to replace its existing CRT model.

For now, these reference monitors are only available in limited sizes, but that will change as improved panels become available to manufacturers.

THE RIGHT COLORS

For the LCD to dominate professional broadcast monitors, it is not just a question of how many colors it can reproduce—it’s which colors.

Recent years have shown tremendous improvements in the ability of monitors to show more of the SMPTE-C colors. As LCD monitors catch up to the phosphor-friendly SMPTE-C color standards, the market is not standing still; SMPTE-C is not ITU-R BT.601, SMPTE-240M, SMPTE-274M nor SMPTE-296M.

Fortunately, many manufacturers are now working hard to offer better reproduction of the appropriate color spaces. As with any newly emerging developments, it pays to shop around as the gap between various manufacturers in the broadcast engineering market is growing wider.

NATIVE RESOLUTION

Picture quality at non-native resolutions has been a significant barrier faced by LCDs. This is being somewhat offset by the inclusion of better scalars in updated product designs. However, it has not completely solved the problem.

Fortunately, newer LCD panels becoming available have allowed manufacturers to offer monitoring products featuring native resolution display of HD signals, and with that they are taking LCDs beyond the realm of mere confidence monitors.

DITHERING FOR SPEED


(click thumbnail)ESPN uses mostly LCDs in its master control rooms.There is a reason ESPN choose to offer sports at 720p instead of 1080i—speed. 1080i may be more suitable for sitting back and watching a movie, but in sports broadcasting speed is crucial.

Designers of LCD panels have to juggle multiple market demands such as ever-faster response times, higher resolutions and improved color range. To further complicate matters, some LCD panels have been designed for computer use as well as broadcast video and therefore have had to offer even higher response times.

Something had to give, and for some LCD panels out there this has been color depth. By utilizing LCDs designed for reduced bit-counts of color, vastly improved response times became possible.

Designers came up with 18-bit monitors that they combined with dithering algorithms to provide a reasonable visual approximation of 24-bit True Color.

Faster true 24-bit LCD systems are now readily available and many of the units on the broadcast market today are now true 24-bit; soon, the dithering units will probably disappear as the reason for this compromise passes.

NEW FEATURES

Manufacturers continue to innovate with new features for their LCD monitors.

Pixel-to-pixel modes allow an operator to see portions of the video signal at its input resolution, thus somewhat circumventing one of the difficulties of working with non-native LCD resolutions.

Blue gun modes have become available for LCDs and some manufacturers are offering self-calibration features by including circuitry to monitor and adjust color and backlight output to maintain more accurate luminescence reproduction.

One company is now offering a system that shows when a sharp focus is achieved by highlighting the focused areas on screen; another is using the combination of an LCD and touch screen technology to offer an innovative visual router.

NEW DIRECTIONS

The improved availability of large-format LCDs has changed the way broadcast facilities are designed.

In the early days of LCDs, it was assumed that one day they would simply replace the multiscreen CRT rack monitors in monitoring walls; however, the profusion of split-screen monitoring and control hardware has also found a synergy with large-format LCDs.

Like projection systems, individual large LCD monitors are now being used in more and more facilities to show multiple smaller video feeds.

On an ongoing basis it is likely that this large- format-split screen approach will continue to make inroads on multiple separate screens. But there will still be many instances where using separate dedicated screens will remain appropriate.

In most new facilities, the CRT has already become a thing of the past for both the small screen rackmounted monitoring and the split-screen large-format approaches. The question has become what we will do with LCDs, not whether we will choose LCDs over CRTs.

A GREAT LEAP FORWARD

For a long time, if you inputted digital signals such as SDI, they would have been converted to analog at an intermediary stage before display on the LCD. However most of the LCDs being released to market recently have utilized all-digital signal paths.

Ten-bit LCD source driver ICs have been around for a while and 13-bit drivers became available in early 2006, offering impressive 8200 gray-scale levels. As components speed up and offer better matches to the color gamut and luminescence curves demanded by broadcasters, LCDs will soon be taking a great leap forward.

Many of today’s LCDs are judged more on what they cannot do, but soon we will be looking at LCDs in the broadcast environment for what they can do that competing display technologies cannot. The components of tomorrow’s LCDs are now out there, it is only a matter of time before LCDs leap forward, leaving the last vestiges of CRT supremacy behind.