Getting a Clearer View

The Standard Panels Working Group Looks Toward Larger, Cheaper Displays

by Stephen J. Bigelow

Processor, January 21, 2005 - Whether you're working through the latest corporate sales figures, pointing out visuals in an important presentation, or just watching a favorite DVD, display characteristics are becoming ever more important for computer users. Displays have grown in terms of physical size and graphic precision, while costs continue to drop. More recently, flat-panel displays have overshadowed traditional CRT monitors for greater portability and lower power demands. Still, the ongoing convergence between work and entertainment applications is driving a healthy demand for larger, brighter, cheaper, and more reliable displays.

Getting Physical

While computers have experienced unprecedented growth in processing power and graphic rendering capabilities, the actual display (the screen itself) hardly seems to be evolving at all. However, Mark Fihn, coordinator of the Standard Panels Working Group, points out that today's screen sizes and resolutions are limited by such factors as cost and physical constraints. (You just can't put a 21-inch display into a 12-inch subnotebook.) He says that the evolution is underway, though many changes are taking place far outside of the media spotlight. "For most applications, as price, weight, and thickness continue to decrease, physical size continues to grow to the outer limits set by that application. Even as few as five years ago, for example, it seemed unlikely that notebook PCs would ever see anything larger than 15-inch displays, but now 15.4-inch (wide aspect ratio) and 17-inch (wide aspect ratio) displays are very common."

Desktop systems now sport 17-inch flat-panel displays. There are certainly 19-inch (and larger) displays available, though they are still a costlier choice for many everyday tasks. As costs continue to fall, Fihn expects 19-inch displays to eventually become standard on the desktop. He also notes that the convergence of entertainment and computing has brought about a fundamental change in aspect ratios. Displays are wider now than they are high, reflecting the 16:10 aspect ratio that is ideally suited to theatrical DVD playback.

Making A Resolution

Of course, overall image quality is limited by the display's resolution, the sheer number of pixels that compose an image. Today's resolutions include 1,280 x 800, 1,440 x 900, 1,680 x 1,050, and 1,920 x 1,200 (each allowing for a 16:10 aspect ratio). Because a human eye cannot resolve differences in the 4 billion colors supported by today's 32-bit color depths (2 32 = 4,294,967,296), it is unlikely that color depth will increase any further, but image resolution is a definite area of potential growth.

"As LCD manufacturing and software support improve in the future, there will almost certainly be a steady trend to higher and higher resolutions," Fihn says. "It seems likely that Microsoft's upcoming Longhorn OS will enable the fast adoption of much higher resolutions, which should enable higher worker productivity and added computing/entertainment capabilities."

But resolution still has a long way to go before truly "lifelike" images become a reality. "Resolution continues to improve in all applications but is still far from that of providing the sort of natural images the eyes see. Most analysts suggest that displays need to improve to something on the order of 200 pixels per inch before the demands of the human eye are reasonably satisfied, but today most mainstream displays are only at about 100ppi, which is 25% of the pixel density represented by 200ppi," says Fihn. Still, any increased resolutions will require corresponding improvements in graphics processing hardware, video memory, and display signal bandwidth (the signal connections between the graphics card/chip and display).

Taming Technologies

Flat-panel displays are essentially fabricated using techniques similar to other chip manufacturing. Fihn says that well-established TFT technology will likely dominate the PC display market into the foreseeable future, except for large (greater than 40-inch) televisions. Several TFT techniques are currently available, he notes. "The vast majority of TFT LCDs produced today are amorphous silicon, while smaller numbers are made from a low-temperature poly-silicon process. There is some promise that p-Si TFT LCDs will grow share due to the promise of higher performance and lower material costs. Unfortunately, p-Si displays are more difficult to manufacture and have not emerged as successfully as many had hoped. OLEDS (organic light emitting diodes) are considered the best possibility of a new technology to display the TFT LCD, but continued manufacturing and lifetime issues suggest that OLEDs will be slow in coming and that p-Si TFT LCDs will remain dominant."

Fihn says that the interface between a graphics subsystem and display may be an unexpected hurdle for display designers. "For notebook PCs, we at the SPWG expect that the LVDS (low-voltage differential signaling) interface will continue to be the dominant interface. As demands for displays at higher resolutions and greater color bit-depth grows, improvements in the interface devices will be necessary, but should not pose any substantial [technical] problems." However, he says the state of desktop interfaces is very different. "Despite several efforts by VESA and other standards organizations, there still is not a broadly accepted digital interface standard. Although DVI is nominally popular on the desktop, it seems that perhaps HDMI or some new digital standard will have to be adopted that will bridge both the computer and entertainment markets."

Ultimately, Fihn says that improvements are coming, but computer users are unlikely to see any fundamental changes in display technologies or implementations for several years. There are no radically new technologies or standards waiting in the wings to revolutionize computer displays. "What they will see are constant improvements to the existing TFT LCD in terms of resolution, wide aspect ratios, brightness, power savings, thickness, weight, viewing angle, response time, etc." He continues, "Rather than any sudden jumps in display performance, it's anticipated that improvements will occur as a gradual evolution, enabled as costs for such enhancements come down."