Microdisplays and Applications by Chris Chinnock Senior Editor, Microdisplay Report (Insight Media) (Reprinted with permission)
Microdisplays seem always to be late in delivering on their promises - but they do deliver. Viewfinder applications are erupting now, and rear-projection is rumbling.
Before writing this wrap-up of microdisplay-related news at SID 2001, I went back and looked at what I wrote last year. Not surprisingly, many of last year's observations and conclusions still hold true today. While some initiatives have delivered on their promises, almost all have taken longer - in many cases a whole year longer. Nevertheless, the ground swell of microdisplay activity continues to rise, especially in Taiwan. In 2002, many new microdisplay products will roll and liquid-crystal-on-silicon (LCOS) technology will begin to have a market impact - although two years later then most had hoped.
From an applications standpoint, the biggest successes for some of the newer microdisplay technologies have come in the smallest and lowest-resolution panels - mostly for viewfinders in digital cameras and camcorders. At the SID 2001 Microdisplay Roundtable discussion held for press and analysts, Kopin (Taunton, Massachusetts) noted that it was producing QVGA transmissive LCOS panels at a rate of 300,000 per month - and going to around 500,000 per month by the end of 2001. Competitor Displaytech (Longmont, Colorado) said that in the six months prior, they had produced 500,000 LCOS viewfinder modules, and would also reach a rate of 500,000 per month by the end of 2001. A third LCOS viewfinder player, Colorado MicroDisplay (Boulder, Colorado) energetically publicized the company's recent name change to Zight and announced improved versions of its QVGA modules. The modules should be in mass production by the time you read this.
FIG A. Minolta DiMage 7 CAMERA
Displaytech also announced a new design win for their color QVGA module in the high-end Minolta DiMAGE5 and DiMAGE7 digital still cameras. Coming in Q3 will be extended-temperature devices and, in 2002, a color 400x225-pixel panel.
Zight announced an upgrade to its flagship SVGA microdisplay, now called the Z86D-3. By moving to a process with smaller design rules, Zight was able to increase the panel's fill factor to 93 percent for a smoother image, and reduce power consumption for the panel by 25 percent. Several development partners using Zight's SVGA display were at SID showing products that are beginning to ship now, with more on the way in early 2002. Among them was a nice-looking binocular headset from i-O Displays that could retail for $600.
Inviso (Sunnyvale, California) demonstrated the latest version of its bring-to-the-eye Internet appliance, eCase, and its head-worn DVD or PC accessory binocular device called eShades. With a new Taiwanese manufacturing partner, Delta Electronics, Inviso says both products should reach market in early 2002 - again in that $600 price range.
eMagin (Hopewell Junction, New York) showed off its emissive OLED-on-silicon microdisplay with a pixel format of 852x600 - a format chosen to support both wide-aspect 480p DVD video displays and standard 4:3 aspect SVGA data displays. The display uses a white emitter and red, green, and blue filters deposited directly on top of the OLED stack, thus eliminating a cover glass. Targeted for consumer headset applications, eMagin is sampling the panel now and hopes to be in production before the end of the year.
New VGA/SVGA-class near-to-eye (NTE) products keep popping up, but no significant volumes have developed yet. MicroOptical (Westwood, Massachusetts) showed their latest clip-on monocular viewers and integrated eyeglass display systems, which continue to improve.
Kopin showed several products from customers, including a headset from a Chinese company with twin QVGA displays that will upgrade to VGA soon. Minolta has developed a clip-on viewer that embeds a holographic beamsplitter and magnifier inside the optic of a pair of eyeglasses.
On the projection front, there was even more exciting news. Perhaps the most important development at the show was the sequential color recapture (SCR) technology announced by Texas Instruments (Dallas, Texas). The technique, when commercialized, perhaps as early as mid-2002, could give a 40 percent brightness boost to DLP™-based 1-chip projection systems at a modest increase in cost and complexity.
SCR involves a redesign of the patterns on a rotating color wheel and of the light integrator used in 1-chip projection systems. In most systems, the light integrator is a hollow or solid rod that takes light from the lamp and homogenizes the intensity via total internal reflection (TIR). This light is then passed through a rotating color wheel that has large red, green and blue segments. This color-sequential light is reflected off the DLP chip. If the process is performed quickly enough, it produces a flicker-free, full-color image.
TI's innovation calls for the color wheel to use a series of spiral-shaped color segments so that the projected light resembles a series of color bands the scroll over the DLP chip. In itself, this would not improve efficiency, but TI has made the color segments out of dichroic filters rather than absorptive filters, and has added a tiny reflector on the input side of the integrator with a small aperture to let the light in.
FIG B. SCR engine design.
The light coming out of the integrator impinges on all three color bands simultaneously. The red dichroic filter, for example, passes the appropriate wavelengths in the incoming white light and reflects the rest back into the integrator. It is retro-reflected by the tiny reflector and can now pass through the green and blue parts of the color wheel. Similar sequences of events are going on simultaneously with the blue and green dichroic filters, which produces a big boost in light efficiency.
A scrolling-color projection system was also demonstrated by Philips Components (Sunnyvale, California). This is also a 1-panel system, but it uses a 1280x720 LCOS panel. The scrolling color bands are produced by a white light source and color-separating dichroic elements to produce three channels of red, green, and blue light. Three rapidly rotating prisms are inserted in these light paths to produce the scrolling color bands. The beams are then combined and imaged on the LCOS panel so all three bands illuminate the panel at one time.
Philips showcased this technology at SID in 64-inch and 36-inch rear-projection demonstrators that looked very good. Philips Consumer Electronics has apparently committed to producing an HDTV using the technology and will debut it sometime in 2002. Other OEMs are expected to follow suite and will use Philips' LCOS panels and technology, branded as engaze™.
JVC (Kanagawa, Japan) is probably the leader in LCOS panel and projection-system technology at this time. At SID, they showcased their expanding line of D-ILA™-branded LCOS panels, including a 1.3-inch Quad-XGA (2048x1536) panel intended for digital-cinema applications. But the company is also accelerating development of smaller and lower-cost panels. It recently decided to emphasize development of a 0.5-inch WXGA (136x768) panel for use in either 16:9 HDTV products or 4:3 PC-TV products. This panel should be ready by early 2002.
Interest in 0.5-inch projection microdisplays is heating up because reducing the size of the panel and optical system is an important way to reduce the cost of these systems. Three-Five Systems (Tempe, Arizona) has a 0.5-inch XGA LCOS panel, too, and shortly after SID the company announced that the panels would be used with several other components to produce a small-footprint optical engine for projection systems. Color management will be provided by ColorLink (Boulder, Colorado) using a new "mini ColorQuad" design. New lamp reflectors from Cogent Light Technologies (Santa Clarita, California) will increase the efficiency of coupling light onto these smaller panels. Advanced Digital Optics (Westlake Village, California), a new division of ViewSonic, will concentrate on engine design and integration.
FIG. C, TFS 1920x1080 display
Three-Five also announced a new name for their line of LCOS panels: Brillian. At SID, it unveiled the Brillian 1920, a 0.85-inch WUXGA (1920x1200) panel, and the Brillian 768, a 0.7-inch WXGA (1280x768) panel. The WXGA panel will sample in Q3; the WUXGA panel should reach production in early 2002. The company believes this WUXGA product will become one of the most cost-effective LCOS microdisplay systems offered for high-resolution applications.
Aurora Systems (San Jose, California) says it is now shipping sample quantities of its latest LCOS display, the ASI 3200. The 0.72-inch panel, which has 1024x768 pixels, is being targeted for rear-projection applications. A trio of these panels were integrated in a 50-inch TV demonstrator, which Aurora hopes to license to system integrators. The company has received major funding from Taiwan-based UMC and is part of a consortium headed by UMC. This group includes several Taiwanese projection-system developers that are intensely focused upon LCOS systems.
While shipments of such LCOS panels and projection systems remain small - only several thousand systems will be shipped by the end of 2001 -- volumes are expected to be significant in several years.
Meanwhile, LCOS-panel developer SpatiaLight (Novato, California) jumped back into the spotlight at SID with the announcement that it had forged an engine-manufacturing deal with Japan-based Fuji Photo Optical Co. Fuji has agreed to scale up its manufacturing capabilities to support the production of 10,000 LCOS-based light engines per month. SpatiaLight has not yet revealed a customer for these engines, but has confirmed the engine will be used in rear-projection monitors and high-definition televisions. A 50-inch HDTV demonstrator was on display at the company's booth at SID. The company's new 0.71-inch WXGA panel is sampling now with production slated for the end of 2001. This is a milestone for SpatiaLight. Fuji is already recognized as one of the best engine manufacturers in Japan, where it is also working with Displaytech on a single-panel engine design.
Samsung Electronics America (Ridgefield Park, NJ) was demonstrating 43- and 50-inch HDTV units featuring three LCOS panels from Displaytech. These sets survived four or five product introduction delays and were set to launch in August 2001. Ironing out production issues has clearly taken longer than anticipated.
Sister company Samsung Electro-Mechanics Company showed their 25-inch SXGA monitor in the Three-Five booth. This product looks good but may not be commercially produced. It may be that a resolution upgrade to UXGA will be needed to compete with direct-view TFT monitors in this size range. But the rear-projection monitor could be cheaper, and with only a modest penalty in footprint size.
Supporting technologies for the microdisplay industry were also detailed in papers and in booths at SID. For example, Philips Research Labs (Aachen, Germany) showed a new UHP lamp design that features a small cavity outside of the main chamber. The cavity is used to pre-charge the gas, and Philips believes it will lead to smaller, more efficient lamp systems.
FIG. D. Unaxis ColorCorner engine config augmented
After two years of quietly developing and sampling customers with it's compact ColorCorner LCOS engine architecture, Unaxis (Balzers, Lichtenstein) has finally begun to promote the assembly publically. Unaxis uses a polarizing beam splitter (PBS), several optical elements, and two ColorSelect Filters from ColorLink to form the basis of a three-panel LCOS engine. Final products using the ColorCorner system from at least two, and perhaps four, companies are possible in 2001, says Unaxis.
A new kind of polarizer, called a Wire Grid Polarizer (WGP), was officially unveiled by Moxtek (Orem, Utah). A WGP is constructed by forming a series of closely-spaced aluminum bars on a glass substrate. This grid reflects light of one polarization state (p) while transmitting light of the orthogonal polarization state (s). This is different from conventional polarizers, which transmit and absorb light in orthogonal polarization state. This reflective property, coupled with the device's rugged construction, enable a host of new uses in projection systems.
Microdisplay technology and applications will continue to remain a fertile area for innovation with the potential for market-reshaping products. Insight Media's recently-released LCOS 2001 Industry Report, for example, documents 21 different LCOS projection-engine architectures. In addition, there are probably half a dozen architectures for the other two microdisplay projection technologies (high-temperature polysilicon and DLP), so the pace of innovation is furious. Microdisplay rear-projection systems may be late to the dance, but they're coming - and they're coming with bells on.
Bio: Chris Chinnock is Senior Editor of the Microdisplay Report, a monthly newsletter covering the microdisplay industry. His company, Insight Media, also publishes reports on various aspects of the industry. Phone 203/831-8404; e-mail
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