Choice of the "best" visual system for a given set of simulation training tasks is considered by many as a black magic process. Considerable confusion, misunderstanding and misapplication of visual requirements exists within the simulation community. Several elementary mistakes are frequently made, so that the simulation visual system is unsatisfactory for the simulation user. This paper presents management methodology for selection of the optimum visual system for a given set of simulation training tasks. Discussion of several current "pitfalls" in visual system use is given to increase confidence in choice methodology. Comparison tables are developed for current state-of-the-art visual systems to provide understanding of visual systems strengths and weaknesses.
Two experiments were performed to assess the effects of touch key design parameters on menu-selection error rates, The first experiment determined that the optimal design consisted of touch keys 10,16-mm high, either 10,16- or 20, 2- wide, and separated vertically by less than 10,16 mm, The second experiment extended the investigation by including the effects of viewing angle, These latter results replicated the first experiment, but also favored the 2012-mm wide key for off-axis viewing conditions, In both experiments, the horizontal separation between touch keys did not affect menu-selection accuracy; however, subjective selection favored a 20.32-mm horizontal separation.
The inability of the human visual system to adapt quickly to a wide range of environmental luminances poses a stiff challenge to the design of airborne displays. Using a repeated measures factorial design, the present study investigated the independent and interactive effects of adaptation luminance, contrast ratio, and display background luminance on this "eye adaptation mismatch" phenomenon. Adaptation luminances ranged from 1 fL to 10,000 fL, with legibility defined as the time required by observers to recognize CRT symbols. Overall, response time increased systematically with increases in adaptation luminance, and decreased with increases in contrast ratio and display background luminance. Additional analyses revealed that contrast ratio and display luminance influence response time multiplicatively, such that quests to maintain large contrast ratios under bright ambient light at the expense of lowered display luminance could exaggerate the mismatch between adaptation luminance and display luminance and thus degrade symbol legibility.
Data is required to assist in the assessment, evaluation and optimisation of colour and other displays for both military and general use. A general aim is to develop a mathematical technique to aid optimisation and reduce the amount of expensive hardware development and trials necessary when introducing new displays. The present standards and methods available for evaluating colour differences are known not to apply to the perception of typical objects on a display. Data is required for irregular objects viewed at small angular subtense ((1°) and relating the recognition of form rather than colour matching. Therefore laboratory experiments have been carried out using a computer controlled CRT to measure the threshold colour difference that an observer requires between object and background so that he can discriminate a variety of similar objects. Measurements are included for a variety of background and object colourings. The results are presented in the CIE colorimetric system similar to current standards used by the display engineer. Apart from the characteristic small field tritanopia, the results show that larger colour differences are required for object recognition than those assumed from conventional colour discrimination data. A simple relationship to account for object size and background colour is suggested to aid visual performance assessments and modelling.
Limiting resolution criteria for detection, orientation, recognition and identification of objects in the visual scene or display have been developed using static high contrast targets. Misconception or misapplication of these criteria to television systems has led to underspecification or underdesign of visual display systems by a factor of 3 to 4 times. Limiting resolution criteria for rastered visual display systems are presented, together with other visual parameter effects. These criteria are used to develop "standard" sets of parameters for the specification of raster visual display systems.
A program to develop a 2048 by 2048 pixel display is described. Key technical limits are identified and an R & D Program to advance the state-of-the-art by constructing monochrome and color feasibility model display is discussed. The paper will concentrate on the CRTs, the 160 megapixels per second video circuitry and the deflection systems developed for the two feasibility model displays.
A full-color projection display system, incorporating CRT driven liquid crystal light valves, has been designed for use in land-based command and control centers. A novel three-channel, two-projection lens approach has been utilized with this system. A polarizing beamsplitting prism partially pre-polarizes the incoming illumination and directs the light along two parallel paths. Red and green primaries of opposite polarization are directed along one illumination path where they are further separated by a main beamsplitting prism and directed to the red and green channel light valves. The blue primary illumination is directed along the other path where another beamsplitting prism directs the light to the blue channel light valve. The main prisms function as both polarizers and analyzers and direct the output light to the projection lenses. Because the light valves operate in linearly polarized light, it is necessary to remove undue stress birefringence, which, if present, would cause contrast degradation and non-uniformity in the projected image. For that reason, index-matching fluid-filled prisms are used instead of glass. The illumination system includes a 2500-watt air-cooled xenon arc lamp which produces an output of over 1500 lumens in additive white. A novel feature of the projection optics is that while one projection lens handles the red and green primaries the other projection lens (blue channel) can be laterally translated to provide for coarse mechanical registration of the images. Remaining image registration requirements are achieved by both dynamic digital-correction circuitry and by image sensors at the screen that provide feedback to the projector's analog deflection drivers. The projector has a resolution of 1400 TV lines and a contrast ratio of greater than 10:1 in white.
Advances in the simulation industry in Computer Image Generation (CIG) systems and the desire to go to very wide fields of view have created a need for advances in display technology. Hybrid CIG, combining sometimes conflicting raster and stroke (calligraphic) technologies, has furthered the need for advancement. This paper describes some of the challenges and solutions encountered in the production of a projector which fulfills these needs. Problems associated with off-axis projection, convergence, and dynamic spot size control are discussed.
A 4x8 inch, 256x512 pixel EL display has been evaluated for use in a portable computer. The display has proven to have excellent visual qualities as well as good reliability. The main challenge now is for manufacturer's to get the cost down.
Several companies have recently introduced flat panel matrix displays into data terminal equipment, desk top and portable computers and similar equipment. There is a great need for the flat panel displays in aircraft and helicopter cockpits because of the severely re-stricted space and power limitations. If one examines the history of the display industry, however, one observes a gap of from 5 to 20 years between the time a display technology is introduced into commercial and domestic usage in a room or laboratory type environment and its introduction into the aircraft cockpit. The major reasons for this are the difficult environment that must be faced by cockpit displays and the relatively small market for such equipment. In order to minimize the time lapse before introduction of matrix displays into the cockpit, Collins Avionics Divisions of Rockwell International Corporation have initiated a program to develop and build Thin Film Electroluminescent (TFEL) flat panel displays specifically for the aircraft cockpit.
A 10" x 12" AC thin-film electroluminescent display system has been developed which uses video as a data source to drive the 512 row by 640 column panel. Characteristics of both the panel and circuitry are discussed in this paper. Also, the operation of TFEL panels in general is described. Finally, power and circuit reduction possibilities are suggested.
Yield issues for fabrication of electroluminescent display panels through the development program cycle are discussed. A model based on learning curve theory is presented which allows estimation of time and resources required for development of panels meeting prescribed technical specifications including freedom from defects. The analysis is supported by data on development history of EL devices.
In the past, flat panel displays usually required multiple printed circuit boards to contain the display driver ICs and the circuitry that communicates with the CPU and/or system. The result was a relatively bulky monitor package, compared to the thinness of the flat panel display element alone. An electroluminescent display element, for example, is less than .20 inches thick. However, when packaged with circuit boards, bezel, etc., the complete monitor depth exceeded 2 inches. Compared with a standard CRT, a 2-inch EL display represents significant volume savings. However, an EL display of this size still lacks the packaging flexibility required for ultra-port,ble designs where the entire display component cannot exceed the depth of a product's front panel, knobs, and switches.
Technical design considerations are reviewed in detail in the context of meeting specific, user required performance criteria for large area, high density liquid crystal displays. Physical screen size, pixel density, total screen content, optical characteristics and price are discussed. Optical performance of the display, as well as electrical performance of the thin film transistors are given. Off current, on current, switching speed, time constants, and angular dependence of contrast are discussed. Yield is considered in relation to detailed device structure and processing details. The impact of total pixel count, screen size, number of processing steps, processing criticality, defect density, and minimum feature size are examined. High yielding, high performance devices are being manufactured and sold. Only standard production equipment, standard materials and standard processing are used to manufacture these devices.
Transmission controllability (TC) and contrast ratio (CR) of PCGH-cells representing three thicknesses, 6, 9 and 12 μm, have been obtained from the transmission versus wavelength data. The phase change guest host (PCGH) mixture consists of 4% black dye in an optically active twisted nematic matrix. TC and CR are sensitive to wavelength and polarization of the incident light, and to the cell thickness. TC is low, less than 10%, for incident wavelengths of 400 to 500 nm. It reaches a maximum for 550 to 650 nm and becomes low for wavelengths above 700nm. The maximum increases in magnitude and becomes narrow with decreasing cell thickness. TC MAX is approximately 45% and 25% for 6 and 12 pm thicknesses respectively. PCGH cells with one polarizer provide better TC.CR products than the twisted nematic and dynamic scattering test cells in 600 to 650 nm wavelength region.
A flat panel display technology has been conceived which utilizes a matrix of line addressable light valves back lighted with a partially collimated source. The basic pixel element of the display is an optical switch based on the zero order of diffraction by two aligned transmission phase gratings. The transmission of light is modulated by mechanic-ally displacing one grating with respect to the other by one-half of the grating period. The color transmitted by the light valve is controlled by the grating profile. Optical spectra of a large-scale prototype of the switchable light valve element are in good agreement with calculations according to simple diffraction theory. Technology for the construction of an optical switch of the desired size has been developed, with 85% of the area devoted to light transmission. The elements are one millimeter squares made of polyvinylidene fluoride (PVDF), a transparent, piezoelectric plastic. Gratings of nearly square profile with 3.8 micron period are produced in 9 micron films of PVDF by embossing at 4000 bars and 70Ã‚Â°C and show the expected optical transmission spectra. Mechanical displacement is produced by applying voltage to two sets of bending arms attached to either side of the movable element. The bending arms amplify motion due to piezoelectric strain. Nickel electrodes are patterned onto the PVDF film by photolithography and liftoff. Perforations around the movable element and the bending arms are etched through the film by reactive ion etching in oxygen, using patterned aluminum as a mask. Motion exceeding 2 microns has been observed, which is sufficient to operate the light valve.
A continuous matrix liquid crystal display (LCD) system for presenting dynamic in-formation and animated graphics to large audiences is described. The advantages of low cost, low power, light weight, flatness and high reliability make LCD's well suited for large public information display systems. The system described is assembled by stacking standard modules in both X and Y directions. Each module is an 8 x 12 array of individual LCD light valves. The modules can be readily assembled into custom sized systems.