New Technology Could Make PMOLED Displays at AMOLED-Display Sizes a Reality

CAMBRIDGE, United Kingdom – Cambridge Display Technology (CDT) has announced a new process that could pave the way for passive-matrix organic-light-emitting-diode (PMOLED) displays to achieve the same large sizes as active-matrix OLED (AMOLED) displays, while maintaining the low power consumption and cost-effectiveness properties the PMOLED displays currently enjoy.

Total Matrix Addressing (TMA) offers a new means for driving passive-matrix displays, explained CDT Spokesperson Terry Nicklin. While PMOLED displays have traditionally been simpler and cheaper to manufacture than their active-matrix cousins, and though they consume only about half as much power, AMOLEDs have always had the advantage of size.

"With passive matrix, what happens is power consumption becomes very large once you get above 2, maybe 3 in.," Nicklin explained. "With active matrix, of course, you can go up to almost any size, but they're a lot more expensive, a lot more complicated. And in reality, that means that most of the display companies in the world are prohibited from being able to use (AMOLEDs)."

The TMA method has been demonstrated to halve power consumption or double display luminescence in PMOLED displays, CDT said in a press release in mid-Novem-ber. It also allows the devices to be manufactured at a much lower cost than traditional large-screen OLED displays because it incorporates the inexpensive external driver chips used in passive-matrix displays rather than the costly thin-film-transistor (TFT) layers that drive active-matrix displays.

Nicklin compared the TMA process to MPEG or JPEG image compression. "It's very much the same, the way it analyzes the data stream going into the display and then works out the optimal way of switching the pixels on and off," he explained.

According to DisplaySearch Senior Vice President Barry Young, the TMA approach could allow PMOLED displays to compete with liquid-crystal displays (LCDs) at all sizes. Because it would use a passive matrix, Young said, the display would be significantly less expensive to produce but would retain OLED's traditional advantages including a 360° viewing cone, extremely high response time, 10,000:1 contrast ratio, and 100% NTSC color gamut. In addition, it would be light weight and only about 0.1 mm thick.

—Jessica Quandt

Display Briefs

Planar Systems Inc. announced on Dec. 6 the first shipments of its new line of Clarity rear-projection displays, the SP Series. The release of these products by the Control Room/Signage Business Unit supports the company's strategic plan to deliver innovative products to specialty display markets, Planar said. Through the Control Room/Digital Signage Business Unit (formerly Clarity Visual Systems), Planar's goal is to provide innovative solutions for the display of networked visual information including displays, digital signage software, and control-room solutions for a variety of State, Local and Federal Government customers.

Displaytech Inc., which manufactures microdisplays using its patented Ferroelectric Liquid Crystal on Silicon (FLCOS) technologies, announced in early December the development of the LightView VGA, WVGA and SVGA (LV-VGA, LV-WVGA, LV-SVGA) microdisplays. According to Displaytech, the new compact, single-panel microdisplays enable consumer-electronics companies to deliver products with unsurpassed image quality and power efficiency while reducing manufacturing costs and accelerating time-to-market.

Forth Dimension Displays (ForthDD), the developer, manufacturer, and supplier of microdisplays formerly known as CRLO Displays, has joined Japan's recently formed Micro Device Display Consortium (MDDPC). The MDDPC was formed in September 2006, with founding member companies Arisawa Manufacturing Co. Ltd., Seiko Epson, Texas Instruments Inc., and Victor Company of Japan Ltd. (JVC).

i-sft GmbH, which produces thin-film-transistor (TFT) displays for non-consumer applications, introduced the 100i.12SV, the company's first product using i-sft's new energy-efficient technology, in early December. The display has a luminance of 1000 nits and a high contrast, targeting applications that demand daylight visibility paired with low-power input. According to i-sft, the display and integrated inverter settle for as low as 12 W at maximum brightness — half the power of comparable products, without loss of good viewing angles or other parameters. The company believes the 100i.12SV will be a good match for mobile applications where battery capacity is the limiting factor.

Self-Aligning Liquid Crystals Could Simplify Manufacture of LCDs, Flexible Displays

ATLANTA, GA – Researchers at the Georgia Institute of Technology have developed a new method of creating vertical alignment of liquid-crystal molecules in a breakthrough that could lead to simpler, less costly flexible liquid-crystal displays (LCDs).

By adding side-chains to the display's polymer molecules, the new method eliminates the step of rubbing an LCD's polymer film or alignment layer, which can cause defects by damaging transistors and introducing dust, decreasing yields in the process. Instead of rubbing the layers, the Georgia Tech team used the in-situ photopolymerization of alkyl acrylate monomers in the presence of nematic liquid crystals. This provided a cellular matrix of liquid-crystalline droplets in which the chemical structure of the encapsulating polymer controlled the liquid-crystal alignment.

"There are a number of different polymers that are used for a variety of applications," explained Professor Mohan Srinivasarao of Georgia Tech's School of Polymer, Textile and Fiber Engineering. "The polymers often are linear chains of carbon atoms, as in polyethylene (-CH2-CH2)n-. Adding side chains means that one of these carbons has a short chain added to it, replacing one of the hydrogen atoms."

"It's a very unique approach to aligning liquid crystals on surfaces," commented flexible-display expert Greg Crawford, who is the Dean of Engineering at Brown University. "It alleviates some of the processes (such as the rubbing of an alignment layer) that we're doing today which are more cumbersome and archaic. That type of thing that doesn't require mechanical rubbing is actually more amenable to flexible-display technologies and gives you more flexibility in terms of how and what type of display you can build."

Srinivasarao and colleagues Jung Ok Park and Jian Zhou have used their technique and a nematic material with negative dielectric anisotropy to fabricate highly flexible liquid-crystal devices that have high contrast and fastresponse times without using an alignment layer.

The research being conducted jointly with a team at Kent State University was funded by a $650,000 grant from the National Science Foundation with the objective of understanding what elements lead to a given alignment of the liquid crystal and how the chemical structure of a polymer might influence the alignment, Srinivasarao said.

However, it remains to be seen whether the resulting technology will ever become commercially viable. Though the displays developed with this new process are ideal for flexible displays in that they are less sensitive to mechanical deformations and pressure, the research team at Georgia Tech said material improvements are still needed in the alkyl acrylates that were used.

— Jessica Quandt

NEC Releases Latest Successors in the Monochrome-LCD Market

SANTA CLARA, CA – NEC Electronics America Inc., announced in late November it had developed two new 21.3-in. active-matrix liquid-crystal-display (AMLCD) modules that provide high resolution and luminance for medical applications. NEC's modules represent the newest developments in the decade-old monochrome medical applications.

The first of NEC's new modules is a 6-million-pixel monochrome LCD module with a resolution of 2800 ´ 2100 pixels, which the company states is well suited for use in applications involving the interpretation of high-resolution radiographic images such as digital mammography images. The module also features a wide viewing angle, an aspect ratio of 4:3, luminance of 1000 cd/m2, and a 10-bit thin-film-transistor (TFT) LCD source driver to enable individual subpixel control of 1024 gray scales, allowing the module to display 3070 gray scales simultaneously without the need for interpolation technologies such as frame rate control.

The second new module targeted for use in X-ray image interpretation because of its uniform high brightness and its ability to curb the "washed-out black" phenomenon common when the viewing angle is enlarged. This 2-million-pixel monochrome LCD module has ultra-extended graphics array (UXGA) resolution, an 850:1 contrast ratio, and a luminance of 1700 cd/m2 — one of the highest luminance levels currently available on a monochrome UXGA LCD module. This is achieved through a combination of NEC's super-advanced, super-fine TFT technology and a high-intensity direct backlight system, the company said.

However, NEC's high-resolution monochrome LCDs are hardly the first to hit the market. Almost a decade ago,dpiX — a supplier of high-resolution imaging systems for industrial, military, and medical applications — was producing similarly sized monochrome panels in prototype or at low production rates.

These products included a 13.5-in. monochrome display with 3072 ´ 2240 pixels, 282 dpi and 16 gray levels, and a 19-in. monochrome module with 256 gray levels and a subpixel pitch higher than 1280 x 1024, according to Tom Fiske, who worked with dpiX when these modules were being produced and now serves as the principal optics engineer with Rockwell Collins Display Systems.

—Jessica Quandt

Philips Denies Reports Claiming It Will Back Out of LG.Philips LCD

AMSTERDAM, The Netherlands – A company spokesman said in early December that Royal Philips Electronics will not be backing out of LG.Philips LCD, its liquid-crystal display (LCD) TV manufacturing joint venture with LG Electronics.

Several online journals from around the world reported in early December that Philips would sell all its stock in one of the world's largest LCD-manufacturing companies. According to these reports, Philips President and CEO Gerard Kleisterlee confirmed these suspicions during the annual meeting of the Radiological Society of North America meeting in Chicago at the end of November.

The Dong-A Ilbo from Korea quoted Kleisterlee as saying Philips would "sell all of our shares of the LG.Philips liquid-crystal display venture between LG Electronics and Philips" because "as the price of LCD panels is too volatile, its profits are unreliable." Kleisterlee was quoted further as saying that the company planned to sell the stock according to market principles and to choose the best way to maximize shareholder profits.

Philips Director of Corporate Communications Andre Manning, however, said Kleisterlee's comments and Philips' intentions had been misconstrued by the online media.

"I have read the online stories and these wordings are a bit out of context, as it is presented that this is something new," Manning explained. "During RSNA, Kleisterlee did not unveil a plan to sell all stakes in our joint venture with LG. However, he said earlier this year and last year that the strategy of Philips is to sell the stakes it has in its joint ventures in a gradual way because these joint ventures and participations do not belong to our core business any more, and we will focus on our core business in the future."

Philips announced in December 2005 it had sold 18 million shares of the common stock, bring-ing its own stake in LG.Philips LCD down to about 33%. In 2006, Philips also unloaded several of its other "non-core" businesses, including its sound solutions unit and its semiconductor business.

Philips's core businesses focus on healthcare (through the company's medical division) and lifestyle and technology (including consumer lighting applications, televisions, and other consumer electronics products).

"As a result of this focus, we don't concentrate on manufacturing of our own electrical components such as LCD screens and other components of the electronics industry," Manning explained.