Group launches digital-interface spec for monitors

by David Lieberman

EETimes, May 7, 1998 - A group of companies will take the wraps off a new interface next week, dubbed DFP for digital flat panel, in an effort to create a digital-interface standard for monitors based on flat-panel displays.  Initiated by graphics house ATI Technologies Inc. and Compaq Computer Corp, the effort is quickly gaining support, with a slew of announcements expected this summer for products that will be available by year's end. PC makers who have pressed the effort include Fujitsu, Acer and Siemens-Nixdorf. Dell and Hewlett-Packard are also part of the Digital Flat Panel Group . Monitor members include market leader ViewSonic, Mag Innovision and Princeton Graphics Systems.

The companies intend to jump start the LCD-monitor market by creating a less-costly, less-complex alternative to the Plug and Display (P&D) digital-monitor interface ratified by the Video Electronics Standards Association (VESA) last year.

P&D combines a digital interface and a new analog interface in a 34-pin connector that also contains USB and IEEE 1394. But the 20-pin DFP connector implements only a digital interface, leaving traditional analog interfacing to the 15-pin VGA-style connector and USB and 1394 to other connectors.

The DFP and digital portion of P&D, however, are logically and electrically compatible. Consequently, some see DFP as a stepping-stone to future adoption of P&D. Both use the TMDS (transition-minimized differential signaling) digital interface technology developed by Silicon Image (Cupertino, Calif.), also known as PanelLink. And both incorporate the VESA DDC (display data channel) for plug-and-play monitor connection.

The DFP spec was recently presented to VESA, sources said, and may be brought under the VESA umbrella. The new connector will be available from both 3M and AMP and is expected to cost under $1 in volume.

"A low-cost digital interface will accelerate the FPD [flat-panel-display] monitor market by about a year," said Peter Eisler, director of component product marketing at ATI (Unionville, Ontario). "There was an effort to try to use P&D, but there's too much inside, it adds to cost, and there's no way to easily route it all in a cost-effective manner through a graphics card today. We're not trying to be all things to all people [with DFP]. We just want to complement traditional analog technology, bridge to the digital future, push the technology, and get to market fast."

Added Peter Wheeler, ATI product marketing manager, "PC OEMs don't know how to implement P&D or why they need to pay for it."

Bob Myers, senior engineer for displays at HP's workstation systems division (Fort Collins, Colo.) and chairman of the VESA monitor committee, said, "We're enthused about DFP, but we're not abandoning support for P&D, nor do we expect P&D to be tossed into the dump heap of failed standards." In fact, Myers said, "We don't see DFP as a long-term threat to P&D but, rather, as a way to get there, a way to ease the transition [to digital] and let everybody get their feet wet with a bare-bones digital interface."

The multifaceted P&D interface, said Myers, "is a great idea and we fully intend to support it at some point, but it's awfully hard to make a transition to that connector, which has both digital and analog interfaces on it, unless you're willing to transition everything in your product line to it, and commit to transforming all of your CRT displays into P&D-compatible displays. That's a big, painful transition with a lot of cost and complexity. And, frankly, we don't have a reason to go through that just yet."

The digital-only DFP interface, he said, "lets you transition only the parts of your product line where digital makes sense. Then, at some point later on, when digital video outputs become an expected feature on everything, it will make sense to roll everything over to P&D."

Some don't agree. "We've heard people talk about DFP as an incremental solution on the way to P&D, but that seems somewhat unlikely," said Robert Soderbery, vice president of marketing at Arithmos (Santa Clara, Calif.), a maker of flat-panel-display controller chips and a member of the DFP initiative. "We believe the DFP is a very cost-effective and good solution for FPDs and if we're lucky enough to have this standard stick, I'd expect it to be the preferred solution for multiple generations of products and technology." The P&D, he said, suffers from "the kitchen sink problem."

"P&D looks to have been over-reaching for a world that isn't yet ready to deploy 1394, and in which USB has found a home on the motherboard," said Andy Fischer, analyst at Jon Peddie Associates (Tiburon, Calif.). "Whether the industry will evolve towards P&D remains to be seen. At present, the DFP connector and cabling is significantly less-expensive and more-focused on exactly the problem at hand, and it appears that significant OEM powers are behind the initiative."

Where the PC powers go, the monitor makers are sure to follow.

Paul Wang, director of marketing at Mag Innovision (Santa Ana, Calif.), is enthused about DFP as a way "to supply something that's better performance and better price, the trade-off being that users will have to plug in a new DFP [graphics] card, which isn't a problem." The company currently uses a low-voltage differential-signaling (LVDS) digital interface for its LCD monitors but will change to TMDS, Wang said.

Digital interfaces will bring down the cost of flat-panel monitors, said Wang, because the circuitry now required to convert a graphics board's analog output to a digital input for an FPD will become unnecessary. "We don't need an A/D converter or a horizontal scanning chip or a whole set of electronics in the monitor — that's at least a couple of hundred bucks," he said.

XGA-resolution LCD monitors, whose screen sizes are approximately equivalent to those of 17-inch CRT monitors, for $999 with a passive LCD and $1,399 with an active-matrix (AM) LCD. Mag's goal is to field LCD monitors for no more than two times the cost of comparable CRT monitors, he said. With a DFP interface, the company's AM LCD monitor will hit the market at $999 near the end of the year, he promised. With the recent dramatic declines in CRT monitor pricing, however, that's more than a three times difference in price.

Pricing issues, said Soderbery, are causing OEMs to rethink passive-vs.-AM-LCD issues. "With the advent of the DFP connector, we're seeing renewed interest in [passive] STN [super twisted-nematic] LCDs for those who want absolutely the lowest-cost FPD solution," he said. "Some of the big PC OEMs are realizing that the only way to get to CRT kinds of price points is with STN and digital."

In the last four to five months, Soderbery said, street prices have dropped to $99 for 14-inch CRT monitors, $199 for 15-inchers and $299 for 17-inchers. "At those numbers," Soderbery said, "TFT [thin-film transistor] AM-LCD makers may be able to approach last year's CRT pricing but not this year's. So people are asking themselves if they can hit a $299 price point with STN for a 15-inch-CRT-equivalent monitor — which is 13.x inches for an LCD display — and it looks like they can get pretty close. In any case, the market has clearly expressed its preference for sub-$500 display solutions."

According to an ATI spokesman, DFP monitors will hit the market at approximately 2.5 times the cost of comparable CRT monitors.