Bringing the big picture to mobile

Picoprojectors are freeing large-scale displays from the tyranny of small form factors, letting battery-powered handhelds project images as large as 50 to 100 inches. Micro-optical-electromechanical system (MOEMS) devices have shrunk mobile projectors so markedly that the projectors are even being tucked into sleek cell phone handsets.

But phones aren't the only market; mobile device makers of every stripe are evaluating built-in picoprojectors for devices as diverse as camcorders, digital cameras, laptop computers, multimedia players, PDAs, gaming consoles, toys and even heads-up displays for automotive, medical, industrial and military apps. With complete modules measured in millimeters, picoprojectors loom as the next commodity electronics subsystem, much as the digital camera module has become a standard accessory for mobile phones.

Texas Instruments' Emmy-winning Digital Light Processor (DLP), which handles images as bright as 30,000 lumens in modern digital cinemas, has been downsized for even the sleekest mobile handsets with built-in 10-to-50 lumen picoprojectors. DLP has landed the first design wins for picoprojectors in phones; LG's eXpo is the first phone to offer a snap-on picoprojector accessory to U.S. mobile users, and Samsung's W7900, sold in its home market of South Korea, is the first mobile handset with a built-in picoprojector (the U.S. model, designated the i8520, is expected later this year).

"The picoprojector market is really starting to get crazy," said William Coggshall, an analyst at Pacific Media Associates. "It's growing quickly, tripling in size each year right now, but from a very small beginning."

Indeed, worldwide picoprojector revenues last year totaled just $69 million on sales of 224,000 units, but those numbers are predicted to grow to $1.76 billion on 23.8 million units by 2014, according to Pacific Media.

But the tiny modules are still a long way from commodity status. "Many end-user picoprojectors today can be purchased for about $200-a mainstream price point which we think is low enough to start driving demand," said Chris Chinnock, president of Insight Media. "Lower pricing will drive more sales, of course, but you are not likely to see picoprojectors put into every cell phone anytime soon.

"A camera module for a phone is on the order of $1 to $2, which is why they are in nearly every cell phone. In the four- to five-year time frame, picoprojector modules could get into the $20 to $30 range, which is a lot higher price point."

Three picoprojector technologies, each based on a different silicon chip, are competing for dominance: DLP, liquid crystal on silicon (LCOS) and scanning laser. DLP bounces light off a microelectromechanical-system micromirror array, with thousands of digital mirrors on chip. LCOS bounces light off a complete LCD on the surface of a silicon chip. And laser scanners bounce off an individual MEMS micromirror chip that raster-scans the image onto the screen, much as electron beams were once used to raster- scan cathode ray tubes.

"Both DLP and LCOS have the potential to become commodities," said Gartner analyst Amy Teng. "Both can use LEDs for illumination, which gives picoprojectors based on them a greater potential to become commodities compared with lasers, which are more expensive."

Beyond the chip and the LED or laser illumination source, picoprojectors require optical lenses for projection and focusing. "These modules are very complex, involving calibration of the mechanics, optics and electronics," said Teng. "Picoprojector module makers are consistently improving performance."

The modules "have the potential to become commodities, the way the digital camera has in mobile phones and the webcam in laptops, but price is dependent on improving yield and increasing economic scale," Teng added. "Once there are major handheld vendors designing in this hardware-with killer software and impressed consumers-then increasing economic scale will help push prices down."

DLP is the most mature of the three competing technologies; it has been in volume production since 1997, the same year the Motion Picture Academy of Arts and Sciences first selected the technology to project the Oscars at the Academy Awards ceremony. TI has been refining DLP ever since, taking it from analog to digital, and has shipped more than 20 million DLP subsystems. DLP is also used today in 19,000 digital-cinema installations worldwide, 10,000 of which offer DLP-based 3-D projection.

LCOS is the second most mature technology, with design wins under its belt for rear-projection TVs and for direct-view electronic viewfinders in camcorders and near-to-eye applications such as head-mounted displays. But LCOS has followed a rocky development road and has yet to match DLPs in volume shipments.

The LCOS process "is very difficult to master, and there are dozens of LCOS company carcasses out there to prove it," said Pacific Media's Coggshall. "Its a complicated supply chain too, which is an additional challenge."

But while DLP and laser scanners both depend on MEMS, LCOS is essentially just another CMOS chip and thus holds promise for becoming ultra-cheap to mass produce. Betting on that mass-market potential, Micron Technology purchased DisplayTech last year in hopes that the latter's LCOS chips would become a commoditized complement to Micron's own commodity memory-chip business. Indicators are good thus far, since 3M not only has chosen to sell end-user picoprojectors based on Micron's LCOS panel, but also supplies LCOS-based OEM modules for other brands.

"We evaluated all the competing picoprojector technologies and chose LCOS not for any one feature, but because it gave us the best combination of cost, efficiency, brightness and resolution for our market, which is the mobile business user who takes their picoprojector home on the weekends to have fun with it," said 3M program manager Gabe Wiebenga. "We've also supplied OEM modules to others, like Aiptek."

Besides the business and consumer mass markets, niche applications are being pursued that will probably keep all three of the major picoprojector technologies in business for now. At the low end, for example, small, ultralow-cost LCOS panels with only a few hundred pixels could become popular in mass-market applications such as children's toys. At the high end, a whole array of heads-up displays for military, automotive, industrial and medical devices are harnessing the focus-free ability of laser-based projectors to display tactical information, such as speed, on automobile windshields. Even artists are using the focus-free capability; Japanese artist Seiko Mikami, for example, recently unveiled an interactive video installation at the Yamaguchi Center for Arts and Media that mounts six Microvision focus-free laser scanners on robotic arms, from which they project moving images of audience members onto the facets of a 12-foot-tall insect eye.

"We've spent our development time making our display look better; it's brighter, with a higher contrast ratio than anything else today," said Maarten Niesten, optics/photonics engineering manager at Microvision. "We also offer a wider gamut of colors and more grayscales. You can see every little detail in images projected by our displays."

Today the massive consumer market is being cracked with add-on picoprojectors-standalone units, about the size of a pack of cards, that you plug into your laptop or smartphone. Leading suppliers of end-user standalone picoprojectors include 3M (St. Paul, Minn.), Optoma Technology Inc. (Milpitas, Calif.) and Aiptek International Inc. (Taiwan). 3M uses Micron's LCOS panel, Optoma uses DLP and Aiptek uses 3M's LCOS OEM module.

Microvision Inc. (Redmond, Wash.) only recently released its 10-lumen, $549 ShowWX, the first picoprojector to be based on lasers instead of LEDs. "We've got a number of distributors who are shipping in Europe, and we've done a pilot test with Vodafone," said Matt Nichols, director of communications at Microvision. "We are getting ready to announce our first design wins, probably during April; these will be with Uniden, out of Australia, which is private labeling the ShowWX, and a major OEM that will be using our module in their own picoprojector design."

3M recently upgraded its LED-based picoprojector line with the second-generation MPro 150. Priced at $395, it outputs 15 lumens, has internal memory and a micro-SD slot for storing content, and has a pushbutton menu system. "We were the first to have a commercial picoprojector, and we are also the first to have a second-generation device," said Steve Saxe, visual systems division project manager at 3M. "Our second-generation picoprojector holds its own content, freeing the user from having to carry a laptop or smartphone with their content, since you can load and display any file right from the picoprojector."

Other picoprojector models are available from a variety of vendors-from Dell to Hewlett-Packard-priced as low as $149.

"Each picoprojector technology has its strengths and weaknesses, and their suitability depends upon the market or application you are trying to target," said Insight Media's Chinnock. "The MPro 150 has very nice colors and brightness [that's] a little higher than most, with some good functionality and good resolution. TI has several chip sets [used in Optoma's picoprojectors] that are aimed at data and video applications, again offering nice colors and resolution that varies depending on the app. Microvision has the first laser-based picoprojector, which offers decent colors and a no-focus feature that can be very helpful for ease of use."

Architectural options

Picoprojectors today use either panel-based or scanned architectures. Panel-based projector engines encode an entire screen on a silicon chip-either an LCOS or a DLP panel. Scanner-based systems use a micromirror to deflect the light source to specific pixel locations in a raster mode that scans across each line of the display.

In the panel camp, Texas Instruments is the sole supplier of its DLP chips, but a variety of established companies and startups are making LCOS panels. In addition to Micron (Boise, Idaho), they include Aurora Systems Co. Ltd. (San Jose, Calif.), HiMax (Taiwan) and Syndiant (Dallas).

DLPs house an image array of binary micromirrors that can image an entire scene and randomly change any part of it by merely flipping the mirrors associated with the relevant pixels.

Likewise, with LCOS chips, an entire scene can be simultaneously imaged on the tiny liquid crystal display and randomly updated.

In the scanned camp are Microvision and Maradin Technologies Ltd. (Caesarea, Israel), with single-mirror, dual-axis scanners, and bTendo Ltd. (Kfar Sava, Israel), with a dual-mirror, single-axis scanner. National Semiconductor said last year that it was also developing a picoprojector based on lasers. And TI has a laser scanner technology, which was developed for printing applications but which could be repurposed for laser-based picoprojectors in the future.

"We went with DLP by popular demand, but we have the technology to do scanning mirrors at any time," said Frank Mozio, emerging markets business manager at TI. "When we started the picoprojector business, we built prototypes using both scanning mirrors with lasers and DLP illuminated by LEDs, and customers liked the DLP/LED solution best."

The other major component of a picoprojector is the light source-either LEDs or microlasers. LEDs are far cheaper today than lasers, which are in short supply. And although lasers have the potential to be brighter than LEDs, today the brightest picoprojectors use high-intensity LEDs to produce as much as 50 lumens from a battery-powered device like Optoma's PK301.

For panel-based picoprojectors, LEDs can either be white, for color-filter-based panels (which project all three colors onto the screen simultaneously), or separate red, blue and green LEDs, for color-sequential panels (which cycle through RGB, illuminating the entire panel with a single color). Color-sequential panels depend on the human eye-brain system to average out the red, blue and green presentations, which switch too quickly (360 Hz) to be seen as separate elements.

Micron supplies 3M's color-sequential LCOS with a unique ferroelectric liquid crystal in place of the conventional nematic liquid crystal, enabling it to switch among the red, green and blue image planes in 100 microseconds, compared with 1 millisecond or more for traditional LCDs.

Lasers can be used to illuminate either panels or scanner-based picoprojectors. For instance, Syndiant has an LCOS panel (developed in cooperation with the Hong Kong Applied Science and Technology Research Institute) illuminated by a focus-free laser that has been used in a picoprojector module from Shanghai Sanxin Technology Development Co. Ltd. The module measures 39 x 24 x 7.8 mm (1.52 x 0.94 x 0.31 inch). For comparison, Microvision's laser-based scanning engine measures 40 x 20 x 7 mm (1.57 x0.79 x 0.28 inch).

Lasers can also be used to illuminate a DLP panel, as is done in some Mitsubishi televisions.

"We are illumination-agnostic; you can use LEDs or lasers with DLP. It's up to the customer," said TI's Mozio.

Panels and scanners have different laser speed requirements. Illuminating a DLP or LCOS panel only means switching the laser on and off at a leisurely pace of 360 Hz. For scanner-based designs, however, the lasers must pulse on and off for every pixel on the display, resulting in speed requirements in the megahertz. The faster lasers are more expensive.

Green microlasers, which only recently became available (from Corning and Osram Opto Semiconductors) and are expected to be short supply until 2011, are particularly pricey. p