Representative functional requirements for large screen displays (LSDs) in C3I applications are developed including requirements for the C3I facility as well as for the LSD equipment. Performance metrics are defined for LSD and commentary provided on the utility of these metrics and contemporary technical specifications for available LSD products.
Several large-screen display (LSD) technologies are applicable for use in military C3I systems. These include devices using lasers, direct-projection CRTs, light valves (oil-film, liquid crystal, and solid-state), and direct-view flat panels. Comparative information on operational characteristics of current production models and descrip-tions of new large-screen devices, which are either just entering the marketplace or are in an advanced state of development, are presented. The systems material is based upon a survey of international manufacturers and developers of large-screen display equipment for military and commercial applications. The study was based on manufacturer-provided information and was augmented with in-plant discussions with cognizant technical staff and marketing managers. Forthcoming improvements to existing displays and technological advances in the field over the last five years are highlighted.
This paper describes the development of a Servo Optical Projection System (SOPS) that provides out-the-window scenery for a pilot training simulator. A system overview addresses the parametric tradeoffs in the optical design, mechanical packaging and servo network performance of the unit as integrated into a research and training helicopter flight simulator.
The grouping of red, green and blue cathode ray tubes optically and electronically converged and projected upon a common screen surface has found wide usage for large screen projection of color video images. The majority of such projectors need only have sufficient convergence and geometry correction capability to "look good" with relatively low resolution broadcast and personal computer graphics video. These projectors typically use analog waveform correction techniques derived from standard broadcast technology which has evolved over many years. Colorimetry only needs to be good enough to give "good skin tones". There is another class of large screen color projectors which is gaining increased attention. These projectors are used with high resolution computer image generators in such demanding applications as flight simulators, image interpretation and military command and control systems. Often the images from multiple projectors are mosaicked to create a single very wide field of view-image. In these applications attention must be given to edge matching and blending between adjacent channels and matching the colorimetry of the multiple channels. Misconvergence and other errors between the three colors must be essentially zero. Until now the electrical waveforms used for convergence, blending, colorimetry and geometrical correction have been based on the use of second and third order power series and their cross products. The coefficients of the waveforms have been either adjusted by analog or digital techniques but the main waveform has had to be analog since subpixel correction as required when using fully digital techniques has been impractical from a size, cost and difficulty of calibration standpoint. This paper describes in detail the requirements for the various corrections mentioned above for single and multiple channel high resolution projectors and introduces a new and novel patent pending three dimensional digital waveform generation technique with two dimensional smoothing that functionally has subpixel bit mapping correction capability, yet is small in size, economical to construct and, best of all, easy to calibrate.
Very large fields of view are needed in certain training scenarios (i.e. flight training, etc.). One solution is to provide a display screen in the shape of a sphere, surrounding the student (or observer) station. The image quality and other display parameters of such a system are dependent upon the geometry of projector(s), screen and viewer(s), as well as the image generation and projection technology. Another major factor is the shape of the screen (usually spherical) and the extent of "closure" of the dome. This last factor is sometimes overlooked in the design and so performance suffers. This paper discusses the display parameters of dome systems and presents performance of such systems as a function of screen size, shape, and quality, the generation and projection of the visual scene, and the overall system geometries.
A new lenticular surface construction makes it possible to fabricate finer and more accurate specular mirror or lens array surfaces for use in high-gain reflection and transmission screens using conventional processes. The new surface enables the finished screen embodiment to be more specular, and approach the theoretical maximums in efficiency, performance and control of the light distribution field.
Pioneer Electric Company has developed a new generation 40-inch rear projection SD-P40 television, a revolutionary, new television that realizes white peak brightness of 300 ft-I and high contrast. The combination of high brightness and high contrast is made possible primarily by newly developed optical-coupling technology that utilizes newly developed concepts. This new optical coupling technology cools the CRT quite efficiently, making it possible to greatly increase the CRT power input to obtain high brightness and at the same time provides greater reliability than direct view televisions. The new optical-coupling technology also makes it possible to almost completely eliminate the reflectance at the boundaries between the CRT and the lens and air, which gives much higher contrast than previous televisions. Not only does this optical-coupling technology provide high performance, in addition since the liquid coolant it employs functions as a liquid lens, the coupling lens can be designed to a uniform thinness and a small aperture. This greatly reduces the cost of the lens. Our newly developed optical-coupling technology is the ultimate form of cooling for the CRT tubes of projection televisions and coupling with the lens and will become the mainstream technology in the future. It is forecast that other manufacturers will also adopt this type of technology. The optical lens section, which is the heart of a projection television, is a hybrid structure with three aspherical plastic lenses and one glass spherical lens. It has higher performance image formation and greater temperature stability than previous televisions. The plastic lenses are all finished with multi-coating to hold down light loss and maximize transparency. This con-tributes greatly to increasing the brightness for a projection television. Previous 3-tube type projection televisions were bothered by low color uniformity, color shift, and low color rela-tive illumination. This model uses three bends in the optical path to lengthen the optical path and reduce the R, G, and B lens pitch angle, so these problems can be virtually ignored. In particular, the special design of the lenticular lens screen greatly. suppresses color shift. The rear surface of the screen is printed with black stripes to hold down. reflectance from outside light sources and minimize the reduction of contrast in bright rooms. In addition, the opti-mal design of the fresnel lens keeps the hot band from being too noticeable. A variety of steps were taken in the design of the bends in the optical path to prevent ghosts.
We have developed a new optical system which enables the miniaturization of the lens sys tem for projection. televisions, while maintaining a high. resolution image. This optical system consists of a simple 3-lens element and a new radially arranged baffle stop. Using this optical system, lens length can be reduced by 25% concomitantly resulting in smaller projection TV. cabinets.
Image Distortions introduced by the optical geometry of typical video projection systems are discussed and analyzed. The major distortions are caused by the fact that the object (e.g. the projection CRT image) and the projection screen are not parallel. Means for correcting the distortions are discussed and examples are given for a typical CRT based projector and for a liquid crystal light valve projector.
A compact, high resolution, large screen projector,which can project a B4 size image at maximum 3000 x 3000 pixel resolution onto a maximum 2 meter square screen, has been developed. This projector size is compact and has low power consumption in comparison with the former projector using a gas laser, for example, an Argon laser, a big Xenon lamp with high power consumption and the liquid crystal light valve (LCLV) with complex thermal control mechanism. The projector measures 430 mm (W) x 365 mm (H) x 595 mm (D) and has less than 1kW (100 VAC,10 A) power consumption, using high power laser-diodes, a compact Xenon lamp (300 W) and the LCLVs installed in a compact cassette holder with thermal control mechanism. Furthermore, the projector can project a controllable cursor image, overlapping a B4 size document image, onto the screen, using two LCLVs projection and laser beam path changed by a moving mirror.
The requirements for a military map overlay display and the decision to use a projected laser addressed liquid crystal are outlined. The design and construction of the display is described with an emphasis on recently implemented improvements. Key parameters of the display's performance are presented.
An electrically writable bistable liquid crystal projection display has been developed. This projection display uses the bistable effect of nematic-cholesteric liquid crystal phase transition under an electric field. The nematic-cholesteric liquid crystal has some advantages in application for a projection display. These are a bright screen with no need for polarizers, a high information content, thanks to the bistable memory effect, a compact system written by only electric field, and a low cost projection system using a simple matrix panel. The newly developed liquid crystal projector has 640x400 pixels, and has good contrast under the bright ambient light of a normal office environment. It takes 1.6 seconds to write all the pixels and 100 milliseconds to type in a 16x16-dot letter. It operates satisfactorily between 5 to 45 T. Use of the nematic-cholesteric liquid crystal results in the total size of the projection system to that of a portable overhead projector. Writing by an electric field makes it quite easy to connect with floppy disk systems, key boards and communication equipment systems.
The projection system of the liquid crystal light valve (LCLV) coupled to Xenon arc source and high resolution CRT gives the advantage of high brightness and excellent resolution. The single light valve color projector concept lessens the cost at a slight sacrifice in resolution compared to a three light valve projector. The novel features and typical performance parameters for a new color graphics projector are: 1) use of miniature CRT's coupled to a single LCLV; 2) a color filter set to achieve color bands with minimum loss of light; 3) imaging and converging the color information by use of offset projection lenses; and 4) fine convergence of the information by digitally stored deflection correction signals. A prototype brassboard system was designed and constructed to evaluate the requirements for convergence, effect of the LCLV characteristics on uniformity of displayed hues, and the general performance parameters obtainable from a single LCLV color projector. Measurements to date shows modulated output of approx. 550 lumens (open gate of 800 lumens), limiting resolution for a primary color of 950 TVL, and contrast ratio of >50:1 for any of the colors. This paper describes the design and performance measurements in more detail.