Displays 1. (Slide) 2. Describe the objective of the high definition systems program. Emphasize the point that we are developing displays that are important to the Department of Defense, with particular interest in rugged, light weight, and low power. We are also supporting the demonstration and transition of display technology into military systems. 3. Describe the current emphasis of the display program includes: 1) developing new technology such as flexible displays 2) complete developing technologies to the point where they can be demonstrated 3) demonstrate/transition technologies supported by HDS in the past 4. The CLADS program (Common Large Area Display Set) was supported by the Air Force. The goal of the CLADS program was to come up with a technology independent display to replace aging CRTs in platforms such as AWACS, JSTARS, and ABCCC. The CRTs are very expensive because they are no longer manufactured, and their mean-time to failure is short for many reasons. Eventually the CLADS display could be a common platform for DoD for ~20" diagonal displays that required 1280x1024 resolution. Technologies that have been demonstrated in the CLADS display include AMLCD by dpiX, Plasma by Photonics, and rear projection by Texas Instruments. All three of these technologies have been supported by the DARPA HDS program in the past. Some of the benefits of the CLADS display include reduced weight, reduced power, better reliability, and larger viewing angle. Bob Zwitch of the Air Force in Warner Robbins is the program manager for the CLADS program. 5. Small image sources for head mounted displays have been developed under both the high definition systems program and the head mounted display program. Examples of state-of- the-art small image sources that are being evaluated include the 640x480 active matrix electroluminescent display (Planar) in the Land Warrior program and the 1280x1024 high brightness active matrix liquid crystal display (Kopin) being developed for Comanche. The government groups that have been involved in this program, as well as several of the contractors involved are listed at the bottom. Both image sources are based on 12 micron pixels. 6. A particular example of a small image source that is unique to the Department of Defense is the high brightness display required for the Comanche helicopter head mounted display system. The system requires 1280x1024 resolution, 1650 ft-L of brightness (because it is a see-through display), 80:1 contrast ratio, <1% reflectance, and a viewing angle of +/- 30 degrees. Two nearer term technologies that are being developed for this kind of stringent requirements are active matrix liquid crystal displays and active matrix electroluminescence. Also, work in active matrix organic light emitting displays could be applicable to this type of application in the future. The Comanche activity is a joint program between DARPA, Comanche, the Army, and Night Vision labs. 7. Another technology that has been supported by the HDS program that has unique attributes for the military is cholesteric liquid crystal displays. Cholesteric materials are typically used in the reflective state, which makes them intrinsically low power. The other advantage of cholesteric materials is that they are bistable, the image stays as written, until it is changed, even when no power is applied to the display. We currently have a joint program with Honeywell and Kent Displays to develop a cholesteric display that reflects in the visible and the infrared, and that has a wireless update link. Because the display is reflective, it is readable from full sunlight, to night time with night vision goggles. The goal is to have the VGA display operate for over a year on 2 AA batteries. 8. There are several projects within the HDS program to support the underlying science of display technology. Two examples are the Phosphor Technology Center of Excellence (PTCOE) and the Improved Field Emission Reliability Activity. The PTCOE has worked closely with Planar to improve the efficiency of blue phosphors for thin-film electroluminescent devices. Over the past year, the blue phosphor efficiency has improved over 5X, and through detailed experimental and theoretical work, our understanding of charge transport in these materials has improved significantly. The PTCOE has also improved our understanding of the requirements for phosphors used in field emission displays. They have demonstrated that fast decay phosphors such as SrGaS4:Eu are less susceptible to saturation at low voltage. In the area of field emission reliability work at MIT and MCNC has lead to an improved understanding of the degradation mechanisms in silicon based field emitters. MCNC has studied the effects of residual gasses on emission properties, and MIT has been working on the effects of dielectric fatigue, and trying to design structures that are less susceptible to intrinsic degradation. 9. One of the suggested advantages of organic light emitting diode based displays is their low voltage operation. One of the disadvantages of a low voltage display is that it requires a significant amount of current to generate adequate light. In order to minimize power consumption, and to improve uniformity across a current-based display, an active matrix backplane will probably be required for displays much larger than 5" diagonal and many more than 200 lines. The graph on the left shows that for a passively addressed display with normal operating parameters, the power efficiency can drop by over 5X as the display gets up to 800 rows. Since the goal of the program is to develop emissive displays on flexible substrates, we have been looking at several methods to build flexible active matrix backplanes. 10. In order to provide enough drive current for a current driven display, we are supporting activities to develop polycrystalline silicon transistors on flexible substrates. One of the activities, described above, uses laser crystallization to produce polycrystalline silicon on plastic. The maximum, sustained processing temperature is 150C. Transistor mobilities are 50cm2/v sec, with on/off ratios >10^6. Areas that still require further development include reducing the off current and improving the gate dielectric. 11. The self-orienting fluidic transport process is being developed to produce high performance electronics that can be distributed over large areas. This is especially compatible with display applications. The integrated circuits are produced on single crystal silicon on insulator substrates. The circuits are then separated into individual "nanoblocks". The nanoblocks have a very specific shape. A receptor site is produced in the substrate where the nanoblocks are to be distributed. The blocks are then floated into the receptor sites. The advantages of the technology are that it provides high performance electronics on any substrate material, shape, or size. It involves only low temperature processing, and requires a low capital investment. 12. This is an example of a monochrome, active matrix display based on organic light emitting materials. The transistors were produced using a high temperature polysilicon process. The organic material is Alq3. The brightness of the display was 850 cd/m2. The display was based on a 4 transistor pixel that was developed under this program. The 4 transistor pixel design minimizes brightness variation due to variation or changes in transistor threshold voltages. 13. The polymer switched matrix display is an optical integrated circuit. The display is based on using infrared LEDs (980nm) that are coupled at one edge of the display. The IR light is guided across the display using waveguides that are developed in the substrate. At the pixel that is to be illuminated the IR light is switched out of the waveguide into a phosphor pit containing an up-conversion phosphor. The phosphor converts the IR light into visible light through a multi-photon process. The brightness generated is controlled by modulating the laser diodes. The display should scale to large sizes. 14. The goal of the program is to make displays rugged and inexpensive. One path to making displays inexpensive is to use roll-to-roll processing. One of the projects we currently have is to develop the processes required to build reflective liquid crystal displays on flexible substrates using roll-to-roll processing. Two of the important steps are the ability to directly etch the transparent conductor, eliminating costly and slow photolithography steps, and to assemble the display into a finished module. The program at Polaroid will determine the feasibility of these steps and will produce prototype displays. 15. In summary, we want displays that have low power, are rugged and light weight, legible from sunlight to dark, are interactive and inexpensive.