Cathode-ray-tube (CRT) displays, which once dominated the market, are giving way to a plethora of display types-LCDs, plasma, and projection displays-all because the consumer entertainment electronics sector is demanding more data handling capability, brighter colors and generally higher performance. Display makers have responded by improving basic display characteristics, such as viewing angle and resolution, and are incorporating more advanced software and hardware algorithms to enable the displays to better handle fast-changing images as well as perform functions beyond showing data and graphics.

What's more, emerging technologies such as organic light-emitting-diode (OLED) and flexible displays will further broaden the playing field in this competitive field.

Underlying the LCD's rise have been many evolutionary changes in the various components comprising the displays. "Backlights, polarizer, TFT glass arrays and color filters have all seen improvements," said Omid Milani, vice president of the displays business unit for NEC Electronics (Santa Clara, Calif.).

As an example, Milan noted that color filters originally would lose 30 to 40 percent of light transmitted through them. "Lots of material science has since been done to get the right pigments to get good color density," he said.

Advances in spacer technology have also improved LCDs. "Spherical bead technology, which dispersed liquid crystals, could experience light leakage," said Milan. "The industry has come up with column spacers to improve transmissivity."

Johan van de Ven, chief technology officer of Philips Mobile Display Systems (Eindhoven, Netherlands), added, "Another enabler has been more efficient illumination systems, particularly for liquid crystal displays." He cited the example of white LEDs starting to replace cold cathode systems in LED backlights. "If you extrapolate LED improvements, backlights will be enabling high-efficiency liquid crystal displays."

Not all display improvements lie in the hardware, of course. Software enhancements through intelligent color algorithms are altering human perceptions of what's being displayed, according to Van de Wen.

"Through software, we can better manipulate data streams on the eyes," said Van de Wen.

Making every pixel intelligent is something Van de Wen believes can maximize functionality in future displays, particularly in space-constrained portable products.

"On a small screen, you can use switches to integrate intelligence into the pixel, perhaps add memory," he said. "In the product's standby mode, you can have pictures, and change them."

Improving color characteristics is another key initiative for display suppliers, according to Chris Chinnock, an analyst for the Microdisplay Report (Norwalk, Conn.). He notes that while traditional color systems are based on an RGB (red-green-blue) design, some manufacturers are trying to move to a four-color system that adds yellow.

"If you can use yellow light to create a primary color, you can create a brighter TV," Chinnock said.

Despite progress, more technology enhancements are needed, say companies.

For instance, the Power Group at Texas Instruments Inc. (Dallas) believes integrating the timing controller and scaler processor on the panel side would enable designers to simplify the display's power supply circuit.

Display interface improvements are also needed to ensure high-resolution signals get to the display. Display drivers are moving from 10 to 12 bits, according to Ed Spence, marketing manager of display drivers for Analog Devices Inc.

With the Federal Communications Commission (FCC) phasing in requirements for most TVs to be able to handle digital signals, better decoding circuitry is also required, Spence added. "We're putting a lot of energy into improving video decoders," he said. "There's going to be a huge opportunity for converter boxes."

Display makers are also rethinking their products' form and function-for instance, using the display not only to show information but also function as an input device.

Toshiba Corp., for instance, has for over a year been demonstrating glass input display technology that uses sensors embedded in the LCD to capture color digital images, such as photos or printed text, for redisplay. The input resolution at which the image is captured and redisplayed is up to 320 x 240 pixels.

Toshiba envisions using the technology to capture images from a catalog, read bar codes, recognize and authenticate fingerprints for security, or import a map into a PDA or from a navigation system. The company expects to be able to do the same with photographic images.

So far, however, Toshiba has not disclosed concrete plans to market the display input technology.

Other display suppliers are embedding display drivers on the glass. Sharp Corp., for instance, is incorporating continuous-grain silicon technology in some of its LCDs that claims to provide faster electron mobility than low-temperature polysilicon. This technology enables parts such as the LCD driver IC, controller IC, and power IC to reside on the same substrate as the LCD, increasing the display's functionality.

Sharp is scaling its continuous grain silicon technology for its small displays used in PDAs, bringing the display characteristics once reserved for larger displays to an emerging generation of mobile products.

"We will add more logic and make the display smaller and, later, incorporate additional graphics processing capability," said Joel Pollack, senior vice president of the Displays Business Unit for Sharp Microelectronics of the Americas (Camas, Wash.).

Sharp has also developed LCDs able to display 3-D stereoscopic images without the need for special glasses. The image is generated by controlling the path of light travel from the display so that slightly different images reach the left and right eyes. The technique used is a parallax barrier, a known approach in generating a stereoscopic display.

For Japanese display makers facing fierce competition from Korean, Taiwanese and likely mainland Chinese suppliers in the future, adding special features to displays is not considered a marketing gimmick, but a key vehicle to differentiation required for survival.

"Survival in this industry requires a value proposition," said NEC's Milani. The Japan side of the strategy is high value-added developing new technologies and licensing them."

"Image burn-in is a perception," said Jonas Tanenbaum, senior marketing manager of flat-panel displays for Samsung Electronics America (Ridgefield, N.J.). "There is some risk with phosphor aging, but it is no more of an issue than with other phosphor-based display technologies."

Tanenbaum said improved manufacturing techniques are being developed to improve the half life of the phosphors in plasma displays. "All of our panels are rated to perform for 50,000 hours, or 20 years."

Material and cost improvements are also starting to take another display technology, OLEDs (organic light emitting diode), into the mainstream. But as with LCDs years ago, OLED technology is still experiencing growing pains.

Today's microdisplay is 1,920 x 1,200 pixels on a 0.72-inch diagonal array delivering 500-nits brightness.

The major thrust in OLED displays is the development of active matrix versions, whose viewing characteristics are considered superior to passive-matrix types. Kodak Corp. and Sanyo have teamed to develop an active-matrix OLED display for a digital camera, while Sony has begun producing one for its CLIE PEG-VZ90 handheld consumer entertainment device.

Kodak has developed an OLED formulation that includes red, green, blue and white. The material set provides red, green and blue formulations for full-color active matrix displays, as well as white formulations for panels designed to use a white-emitting OLED material with a color filter array.

But further advances will be needed to improve the lifetime and reliability of OLEDs, according to Philips' Van de Ven.

"For OLEDs, we see development of light-sensitive diodes and systems that can correct for differential aging and differences in environmental illumination."

Analog's Spence said cost and power dissipation were two issues the company was working with OLED display companies to resolve. One key would be designing the interface electronics.

"We're studying very carefully the use of smart partitioning, taking the interface electronics and keeping those in large geometries," he said. "There's no way you can use a garden-variety CMOS driver."

Rear-projection displays that once used three-gun CRT engines are now employing more sophisticated light engines that provide higher brightness and uniformity, according to Analog Devices' Ed Spence. Those developments are paving the way for high-definition, microdisplay-based TVs that promise a cost-effective alternative to flat-panel screens.

For instance, Brillian Corp. has developed a 0.72-inch diagonal panel showing 1,920 x 1,200 pixels that is being incorporated into a 65-inch rear-projection high-definition TV being marketed by a major TV maker under a private-labeling agreement. The display, which has a 0.72-inch diagonal array and an 8.1-micron2 pixel, delivers a brightness of over 500 nits.

While showing lots of promise, Brillian has experienced a setback getting the TV into production. Slated to begin shipping in the third quarter, the high-definition TV is pushed back until the fourth quarter because of delays getting the light engine from JDS Uniphase.

Therein lies a key problem with microdisplays. Unlike makers of liquid crystal and plasma displays, microdisplay companies tend to be smaller, less vertically integrated suppliers that must rely more on partners to help with manufacturing and supplying key components, according to Chinnock.

"Microdisplay companies have to outsource to be competitive," said Chinnock. "You need to build the products and outsource component procurement to China."

Vince Solitto, chairman and chief executive of Brillian Corp., said, "We make the microdisplay in Tempe, Ariz., source the light engine from JDS Uniphase, get the display's bulbs from Asia, the lenses and screens from Japan, and the pc boards from Penang, Malaysia." He added that the microdisplay TVs are assembled by a contract manufacturer in Tijuana, Mexico.

For instance, some companies are developing flexible roll-type displays that can replace traditional paper signage in supermarkets.

Kodak Display Corp. has unveiled flexible plastic displays that use polymer dispersed cholesteric liquid crystals applied to plastic substrate. The liquid crystals have two stable energy states-on and off-and power is required only to change the image displayed. Kodak claims the technology requires no polarizers and allows easy wide-angle viewing.

"We believe there's a lot of paper signage going over to digital," said Chris Johnson, business segment manager for the Display and Components Group of Kodak.

Replacing traditional signage with electronic displays would simplify updated information, such as prices and sales items, say proponents, and give marketers and retail outlets additional flexibility in promoting products and services.

Sanju Khatri, an analyst for iSuppli/Stanford Resources (Santa Clara, Calif.), said the professional audio/video industry is banking that digital signage could be a killer application as display makers such as NEC-Mitsubishi, Samsung, Pioneer, and Sharp already have LCD, plasma and rear-projection cubes in their product lines.

However, Khatri concedes customers need to be convinced digital signage will produce a return on investment for consumers, according to Khatri. "The technologies are there; the problem is coming up with a convincing business case," she said.

One issue, for instance, is whether the user would want to shoulder the responsibility-and cost-of programming and operating the display technology generating the digital signage. Khatri said that consumers whose products are advertised electronically could foot part of the bill.

OLED displays could also find their way onto flexible substrates. Van de Ven also sees OLED displays, because of their absence of a backlight, as candidates for transparent, flexible displays that could be fabricated in a roll-type format.

For instance, LCD makers have touted their next-generation fabs as the catalyst in bringing down the cost of producing large glass substrates for the TV market. But some LCD fabs have seen ramp-up displays and less-than-optimal yields. While such problems are not unusual, suppliers will need to work the kinks out of their production processes if they are to reliably produce the massive amount of panels needed to fulfill what analysts believe will be soaring demand for flat-panel LCD TVs.

At the same time, other members of the display supply chain will need to step up also. Makers of integrated display drivers, for instance, will need to come up with parts capable of keeping up with the fast refresh rates new displays require. And glass makers will continue to need to upgrade their furnaces to handle large sheets of glass.

New display technologies, no matter what benefits they deliver, will also encounter resistance by consumers accustomed to the tried-and-true. Despite growing LCD TV sales, CRT TVs are projected to dominate the market for a few more years, particularly as their prices remain far below that of their flashy LCD counterparts.

Though cost will be crucial in consumer acceptance of advanced display technologies, ease of use, particularly with auxiliary electronics, will also influence the consumer's choice of display technologies, according to Brilliant's Solitto.

"People will pay a lot of money for something simple," Solitto said. "If you look at a rear-projection micro display TV, a whole piece of that box is empty. There's the potential here to integrate the DVD player and cable box. It is very attractive to a lot of people. All the functions can be implemented onscreen."