Archive for the ‘ Display technology ’ Category

EETimes.com – Ex-Apple expat leads Samsung’s OLED TV push

EETimes.com – Ex-Apple expat leads Samsung’s OLED TV push.

GIHEUNG, Korea — When you travel all the way to Giheung, Korea, the last thing you expect is to meet an ex-Apple engineer who has morphed into a hotshot at Samsung Electronics, committed to pushing OLED for large-size TVs.Meet Brian Berkeley, vice president of OLED R&D Center at Samsung Mobile Display Co.

In the exclusive global circle of OLED experts, Berkeley is the closest thing to a “rock star,” according to Joe Abelson, vice president of displays research at iSuppli. Berkeley’s presence in Giheung speaks volumes about Samsung’s commitment to lead the industry by recruiting the best and the brightest from all over the world, Abelson observed.

Berkeley, whose passion is flat panel display technology, left Apple and a comfortable home of Saratoga, Calif. in Nov., 2003, and he relocated — along with his family — to Korea, indefinitely.

Samsung, the world’s largest LCD panel manufacturer, is increasingly confident in the future of OLEDs — not just for smart phone’s displays, for which Samsung is the biggest manufacturer and supplier, but for large-size TVs, especially 3-D TV.

At Samsung, OLED TV is no longer a “science fair” project. Samsung’s faith in the technology is backed by the company’s volume production experience of OLED displays over the last 18 months.

Ever since the company began large-scale OLED mass production in late 2008, “We have significantly improved yields and line efficiency,” claimed Berkeley. “Material developments have been accelerated, backplane technology improved and a number of advancements made in color patterning.” Without divulging any specifics of the “unique solutions” developed by Samsung, Berkeley said, “Large-size OLED TVs are viable.”

Samsung brought together all its OLED development teams under one roof in January, 2009, by establishing a new company called Samsung Mobile Display (SMD). SMD, now with 400 people, is no longer, by any standards, a skunkworks.

Through joint financing from Samsung Electronics and Samsung SDI, SMD is set up to “draw upon Samsung Electronics’ market-leading capabilities for LCD panels and its large-scale Active Matrix OLED R&D, and from Samsung SDI’s AM OLED mass production technology and its development capabilities for LCD modules,” according to Samsung.

Indeed, SMD already created the world’s only high-volume OLED manufacturing line (a Gen 4 plant in Cheonan), with $3 billion revenue in 2009. In 2010, 20 percent of smart phones are projected to use OLED for their displays. By 2015, 50 percent of smart phones will be using OLED, predicted Samsung.

Still, the transition from making OLED for mobile screens to production for large-scale TV requires huge advancements in technology.

OLED has always been the darling of technical conferences like the Society of Information Display (SID). It holds the promise of the thinner, brighter and greener (more efficient) displays. And yet, for established applications — such as large-screen TVs, existing technologies (i.e. LCD TVs) have always seemed a step ahead of OLED, leaving the dream of OLED perpetually tantalizing.

Samsung’s Berkeley noted, “We are not saying that OLEDs will replace LCDs.” However, he stressed that Active-Matrix OLED (AMOLED) “needs no backlight, no color filter and no second glass (like an LCD panel does).” That makes OLED a low cost alternative.

Further, when compared to PDPs and LCDs, AMOLED is “the only display that is both self-emissive and active matrix,” he added. “OLED is green and it is getting even greener.”

Berkeley, however, acknowledged that mass production of large-size OLEDs has its challenges.

OLEDs, which are ‘current’-controlled devices, have additional backplane requirements, needing high mobility substrates and tighter threshold voltage. For OLEDs, he noted that the “smart money” has given up on amorphous-silicon. It needs poly-silicon. OLEDs also need better gate insulators, said Berkeley. “SiNx is not adequate.”

Berkeley asked a rhetorical question: “Can this be done?” He answered, “SMD has achieved all of the above at Gen 4.”

But still, for large-screen OLEDs, developers must increase beam length from the currently used 450mm to 623 mm for 46-inch screens. It also needs high laser power, accurate control, high precision optics and high system throughput, Berkeley explained.

In sum, though, he said, “OLED backplane scale-up is under way; OLED emission color patterning scale-up is also underway.”

Berkeley originally came to Korea in 2003 for LCD research. But “the most exciting thing right now is OLED,” he noted.

Even before talking about the future of OLEDs for flexible devices that can be folded or rolled for storage, Berkeley firmly believes that “OLED 3-D TV is superior to LCD 3-D TV.” He said, “There will be no ghost images and it can offer eye-popping good quality.”

It’s mainly because fast OLED response time leads to complete separation of left and right images. Berkeley pointed out the upcoming SID’s session 51 (scheduled on May 27th) on 3-D TV and 3-D Video, in which SMD will present a “novel simultaneous emission drive scheme for crosstalk-free 3-D AMOLED TV.”

Berkely also noted that his boss, Sang Soo Kim, Samsung fellow and executive vice president at SMD, will be a keynote speaker at this year’s SID, discussing “The Next Big Things in Displays.”

SID, held in Seattle this year, opens next week on May 25th.

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Qualcomm’s approach to displays – Small Times

Qualcomm’s approach to displays – Small Times.

by Neha K. Choksi

March 31, 2010 – Displays are a hot topic, especially in the mobile consumer electronics industry. LCD displays are prevalent in today’s handheld devices, but their poor power efficiency and readability in bright light give incentive to uncover alternative approaches. Qualcomm senior engineer Rashmi Rao shared the company’s MEMS-based approach to displays at the IEEE Bay Area Nanotechnology Council meeting on March 16, 2010.

Handheld devices are being used more and more during each day, which has large implications on the battery life of a device. Pike Research predicts that by 2014, 54% of cell phone battery life will be used toward displays. The current trend to address the issue has been to use heavier, thicker batteries, but Rao questions whether this is the true solution. Qualcomm’s mirasol display approaches the issue by trying to reduce the power consumption rather than increase battery size — an approach inspired by nature. Butterfly wings are made of millions of nanostructured etalons (two parallel reflecting surfaces). When light passes through the wing’s multilayered surface, it reflects multiple times, which leads to the intense, iridescent color for which butterfly wings are known.

Mimicking the butterfly, the company approaches a low-power display solution by creating a MEMS etalon device (see figure below). The top layer of this two-layer device is a partial reflector; the bottom layer is a total reflector. By defining the gap size between the two layers, the resulting reflected color can be specified. The bottom layer of the MEMS etalon is a moving membrane; thus the gap between layers can be modulated. The device operates as a bistable capacitive/electrostatic switch. The bright, open state is achieved by a low constant bias. By superimposing a short positive pulse, the movable bottom layer collapses for the “closed” state. The collapsed membrane results in an interference pattern of light that is not visible or “dark” to the viewer. This closed state is maintained until another pulse “un-writes” the device and the lower membrane moves back to its initial open state.

Because the device maintains its state unless pulsed, it is able to achieve lower power consumption than LCD and OLED display technologies that dominate the market today. Furthermore, Rao explains, the display is able to achieve a faster refresh rate and is also lighter than current displays. The device’s response time, on the order of microseconds, indicates that it is well suited for video applications. Also, color filters that reduce brightness in LCD technology are unnecessary for the MEMS-based display.

Brightness is a key differentiator for this display in yet another way. Because the intensity of current display technology is limited by the illumination source, which cannot compete with the intensity of sunlight, LCD and backlight OLED displays are difficult to read in bright sunlight. But since the mirasol MEMS display depends on ambient light for its light source, it has an inherent mechanism for adjusting its brightness to its surrounding light intensity, lending itself to bright light conditions. In fact, the company claims excellent contrast: 90% reflected light in the open state vs. 1% in the dark state. Plus, by utilizing ambient light, the new product eliminates the need for backlight illumination and further reduces power consumption.

On the other hand, in darkened rooms or at night, the ambient light may be insufficient for these MEMS-based displays to reflect. Hence, is Qualcomm exploring the option of frontside illumination for low ambient light conditions. It is unclear what impact the frontside illumination will have on battery life, but the aim is to keep power usage well below current LCD and OLED technology.

When asked about reliability, Rao explains that a universal usage model is still < in the industry, thus complicating a metric for comparison to other devices. The company has conducted initial accelerated lifetime tests on the device in the operational temperature range, with and without humidity, but additional investigations are underway.

Despite work to be done, the new device has received significant attention — the display technology is targeted for the e-book market. Just as cell phones are demonstrating the intersection of technology with the Internet, cameras, gaming, TV/video, contacts, music, calendar, email, and more, Qualcomm’s MEMS displays have opportunities that can reach far beyond its initial entry point. But MEMS are just one of many approaches to next-generation mobile displays, and the company is not alone in pursuing a MEMS-based approach. As Rao states, “convergence is inevitable,” and the company hopes to be on the front line as the push for energy efficiency continues.

EETimes.com – E-books: Battle brews over display alternatives

EETimes.com – E-books: Battle brews over display alternatives.

Until a few weeks ago, the biggest worry for E Ink, maker of the Vizplex technology used in Amazon’s Kindle and a host of other e-book readers, was the two dozen or so e-paper competitors looking to loosen its grip on the market. Then Steve Jobs announced Apple’s iPad tablet, which uses a standard LCD display that sacrifices e-paper’s readability and zero-power modes but offers higher refresh rates and full color.

Will consumers sacrifice “green” e-paper on the altar of fast color, relegating the nascent technology category to a niche? For the analysts who track the display market, the question is a page turner, and they’re of a mixed mind on the likely conclusion.

E-paper displays can replace virtually any printed page with a nonvolatile image that is changed electronically. Beyond e-paper versions of books and periodicals, developers envision applications for blueprints, maps, shelf labels, signage, smart cards and even “skins” that cover your iPhone with changing patterns.

E Ink’s Vizplex display uses microcapsules containing white and black pigments that can be attracted to the surface with electrical potentials to form paperlike white, black or grayscale pixels.

For green paper replacement, the e-paper display must retain its image without any energy being expended (called zero-power or bistable mode). That capability and the lack of a backlight requirement are how e-book readers maintain their long battery lifetimes–which are sometimes measured in page turns, since energy is expended only when the displayed image changes. (LCDs, by contrast, run down a battery in a few hours, regardless of what is being displayed.)

The e-paper category today is dominated by e-books using E Ink’s Vizplex display, which looks remarkably like a clean, white sheet of paper printed with black ink. “Vizplex is widely used today for its best-of-breed whiteness and because it is already being mass produced,” said Gartner analyst Amy Tang, who tracks the e-paper market.

Most other bistable display technologies bounce ambient light off a highly reflective surface, making text look like it is written on a mirror. The paperlike appearance of E Ink’s Vizplex is the result of bouncing ambient light off the same white and black pigments that are used in traditional inks; in the Vizplex, the pigments fill the charged microcapsules that form the display pixels.

E Ink’s monochrome display (no color yet) commands at least a 20 percent price premium over other e-paper solutions. It handles page refreshes fast enough for menus, windows and simple animations, but it cannot display live video. About two dozen independent development efforts worldwide are working to address the Vizplex’s shortcomings. But E Ink itself makes no apologies for its success.

“All these competing technologies have something unique to offer,” said E Ink marketing vice president Sri Peruvemba. “But in e-publishing applications, a great digital reading experience is key. Fast color is better suited for gaming than for reading.”

Though Peruvemba has a point, there is concern that tablets like the iPad could topple the fortunes of the whole e-paper ecosystem. Display vendors, chip makers and OEMs have been holding their breath since Jobs’ announcement, waiting to see how consumers react in March when Apple starts delivering.

“E Ink does provide great readability over reading text on an LCD,” said Tang. “But consumers who planned to buy an e-book reader will be comparing the iPad’s multiple functions and multimedia content to decide if they are worthy enough to exchange for the readability of an e-paper display. Heavy book readers will stay with the readability of e-paper, but that market alone is comparatively smaller.”


Click on image to enlarge.

“If the iPad really gives 10 hours of battery life, as [Apple] claims, then that will change the equation away from E Ink,” said Richard Doherty, principal analyst at Envisioneering (Seaford, N.Y.). “All the disadvantages of electrophoretic displays–that they aren’t color and can’t show motion video–are solved by going with active-matrix LCDs.”

“I think LCD tablets like the iPad and dedicated e-readers will coexist,” said Paul O’Donovan, who follows the LCD market for Gartner. “My personal opinion is that the LCD tablet market might never really take off and that e-readers will evolve to eventually include color with video and animation capabilities.

“We’ll just have to wait and see how this market plays out within the next 18 months.”

The stakes are high for the e-paper competitors vying to break E Ink’s virtual monopoly on the market. Research firm iSuppli predicts that the market for zero- and ultralow-power e-paper displays will top $516 million by 2012.

With shipments slated to pass the 10 million-unit mark this year, vendors are scrambling to line up mass-production capabilities to rival E Ink’s, but at a lower cost to OEMs, while they simultaneously claim to be adding color and video capabilities.

“E Ink is the favorite son today for the low-power market. But when worldwide volumes hit the 10 million-unit mark sometime later this year, investors are going to start seeing that all sorts of other possibilities begin to make sense,” said Envisioneering’s Doherty. “A year from now, E Ink is going to have a lot of competition; 2010 is going to be the year of shakeouts.”


Qualcomm’s Mirasol MEMS display uses the phase difference between light reflected off a membrane and a thin-film stack to reinforce colors selectively.
Click on image to enlarge.

LCD manufacturer Primeview International (PVI, Hsinchu, Taiwan), bought E Ink last year and has licensed its process to Chi Mei Optoelectronics (Tainan, Taiwan) and LG Display Co. Ltd. (Seoul, South Korea). The deals bring E Ink plenty of capacity to meet demand in expanding consumer markets.

Matching E Ink’s production capability, but without announced design wins, is SiPix (Hsinchu, Taiwan), which was purchased last year by LCD panel manufacturing giant AU Optronics Corp. (Hsinchu).

“SiPix/AUO is an electrophoretic alternative to E Ink,” said Gartner’s Tang. “I foresee that SiPix will stimulate E Ink to enlarge their scale of production even further by strategically partnering with other LCD fabs, and as a result supply will become more stable and prices will go down.”

E Ink’s patented electrophoretic display sandwiches its microcapsules of oppositely charged black and white pigments in a fluid between two polymers. When a voltage is applied at a pixel location, its polarity attracts either the black or the white pigment to the backplane. Grayscales are represented by mixing some white microcapsules with some black ones. After power is removed, the page remains displayed because the microcapsules are bistable and will hold their position indefinitely.

SiPix uses the same technique but adds a proprietary roll-to-roll embossing process that impresses microcups into a polymer, then fills them with the transparent liquid containing the charged pigment. The microcups can be filled with pigments of any color, although the company is reportedly still perfecting color pigments that do not fade. Later this year, SiPix expects to begin delivery of a variety of display sizes, from 2 inches (for shelf signs) up to 20 inches diagonally (for public information displays), including both 6-inch and 9-inch versions with built-in touchpanels for e-books.

“SiPix is using a similar technology to E Ink, but they are able to build much larger displays,” said Vinita Jakhanwal, principal analyst at iSuppli. “And there will be other options regarding electrophoretic suppliers in 2010.”

Bridgestone (Tokyo) has developed an approach that is similar to electrophoretic displays but uses a grid and a charged dry pigment called electronic liquid powder (ELP). The ELP is lightweight and reacts up to 1,000 times more quickly than pigments suspended in a liquid–so fast that Bridgestone is reportedly working to reduce wear and tear on the backplane from the impact of the fast-moving pigments at video frame rates. The company has demonstrated both monochrome and color displays.

Bridgestone’s technology “could answer the slow-refresh concerns with electrophoretic displays,” said iSuppli’s Jakhanwal. “I think they currently have a 0.2-millisecond refresh rate, compared with 200 milliseconds for E Ink.”

Also headed for commercial mass production this year is a microelectromechanical system display that its developer, Qualcomm MEMS Technologies (QMT, San Diego), has branded Mirasol. “If I was to predict the most likely display technology to replace E Ink, it would probably be Qualcomm’s Mirasol,” said O’Donovan. “My reasoning is that Mirasol is a reflective technology that uses very low power but, more importantly, offers video capabilities. I think that will be a critical advantage for future e-books supplemented by video content–graphical diagrams that come to life, or video or some kind of moving content. This could be a killer application in the educational e-textbook market.”

QMT thus far has gained design wins for small, cell-phone-sized displays only, but it has shown a 6-inch prototype that could be used to build an e-book reader. The company recently built a dedicated manufacturing facility in Longtan’s Science Park (Taoyuan, Taiwan) in collaboration with industrial giant Cheng Uei Precision Industry Co. Ltd. (Foxlink).

Mirasol uses an optically resonant cavity housing a Fabry-Perot interferometer, consisting of a thin-film stack and a deformable reflective membrane. Normal ambient light reflects off both the thin-film stack at the top of the cavity and the reflective membrane at the bottom. Phases are controlled to reinforce specific colors selectively, thereby yielding light amplification without any filters or polarizers to cut down on the reflected light. That eliminates the need for a backlight. The display can be sidelit for reading in the dark.

For now, however, “we are only going to see Mirasol-style displays for pocket- and pen-sized displays–and I mean literally on the side of a pen,” predicted Envisioneering’s Doherty. “You need very bright ambient light, and even so the colors offered by Mirasol are too washed out except for applications like highlighting text. Advertisers are definitely not going to want their ads displayed on a Mirasol.”

Besides Mirasol, “to my mind, there are only two other likely [electrophoretic] replacements on the horizon,” said O’Donovan. One is Liquavista’s electrowetting technique, he said, and the other is “of the LCD derivatives, such as Pixel Qi’s transflective screen.”

Electrowetting displays work by modification of surface tension in a simple optical switch that electrically contracts droplets in a colored-oil film. Without a voltage, the colored oil forms a continuous film and a solid color is visible. When a voltage is applied to the display pixel, the oil is displaced into a droplet in the corner, and the pixel becomes transparent. While the display is not bistable, it can be updated as infrequently as every few seconds, making its image retention ultralow-power.

“Liquavista’s main advantage is that its display looks very good,” said Jakhanwal.

Liquavista has collaborated with Texas Instruments to support its electrowetting displays with a development system for TI’s Omap-based eBook development platform, which also works with E Ink’s display.

Dialog Semiconductor, Epson, Freescale and Marvell also supply support chips for E Ink’s display.