Although engineers profess to have a working knowledge of testing methods, ergonomics is an area of testing with which engineers are only beginning to grapple. Testing for such human factors as personal goals, requirements, limitations and comfort is necessary to evaluate the human consequences of new technologies. While engineers are concerned with performance of the technology and its components, ergonomists assume working machinery and test for human performance and preference effects. Examples from the literature illustrate the approach to ergonomics research. Despite the problems and tradeoffs inherent in arriving at human factors solutions, ergonomics must be included in the design of new technologies so that they not only enhance human productivity, but also are accepted by users.
Various approaches can be used to improve the viewability of VDT screens. These function by reducing glare and improving contrast. Both OEM and retrofit solutions are discussed and compared. The use of the MTF methodology is applicable to the evaluation of reflected glare and the viewed image. This metric is used to evaluate the reflected glare from screens. Optimum filters are recommended.
A pair of picture quality experiments was conducted using ratio and ordinal scaling methodologies. The ratio scales were generated by the method of magnitude estimation and the ordinal scales were rank-ordered category scales. The purpose was to compare the methodologies, to see if one method would out perform the other. Two stimulus ranges were employed on otherwise equivalent stimulus material and observers. The ratio scale results showed much smaller context effects and have the additional virtue of providing meaningful ratios and intervals in the numerical responses.
A complex and difficult problem for the design of color display systems is the selection of a repertoire of display colors. Color selection is the process in which display visual parameters, operational ambient lighting characteristics, and human visual/perceptual functions are integrated for the purposes of specifying an optimized set of display colors. The object of color selection is not necessarily one of establishing an aesthetic repertoire of display colors, but rather the goal is to select a minimum set of colors that maximize the visual utility and information transfer capabilities of the display. The present paper describes a unique, algorithmic approach to color selection which is based upon psychophysical models of color processing. The selection algorithm, currently implemented on a personal computer, seeks to develop color sets of specified numbers in which the minimum color difference between any pair of colors in the set is maximized. In addition, the computer program combines the selection algorithm with internally derived correction factors for color image field size, ambient lighting characteristics, and anomalous red-green color vision deficiencies of display operators. The program and color selection algorithm together provide an extremely powerful tool for color display system design.
This paper describes NOSC-Hawaii's program of perceptual sciences research, supporting the development of advanced military and civilian teleoperator systems. The general objective of NOSC's Advanced Teleoperator Program is to provide the technology base required to produce teleoperator systems which will be capable of performing man-like tasks in areas too hazardous or too costly for human habitation. For several years, we have been engaged in a program of research aimed at developing a systematic understanding of the dynamic interactions which occur between the human operator and the sensors, controls and displays that constitute the interface between man and machine. Our current work is directed toward assessing the impact of several geometric parameters of stereoscopic viewing systems (camera separation, convergence and magnification), on both target detection performance and measures of operator acceptance of these display features. The results of several psychophysical studies will be presented and related to display system design issues.
There is only one real world. We "see" that world as extending into three dimensions because we look at it with two visual systems and with two eyes. We are not presented with two "pictures" of the real world, but with two separate sets of inputs into two separate systems. The analog of the eye as a camera has been a constant problem in the visualization of the "seeing" process. Overcoming the persistence of such an approach is the first requirement in developing a true stereoscopic display system. The eye is a dynamic sensing apparatus and supplies the brain with visual inputs. The brain constructs the scene we "see", and is responsible for our perceptions of the visual world. The sensory inputs from the human dual visual system (Ambient - wide FOV, Focal - detail FOV) are combined with other body senses in this perceptual process. Indeed, other body senses, in some degree, direct and control where and at what our eyes look. This process of conceptualization of the "real" world as perceived by ourselves can be related only within limits to the "real" world as perceived by others.. This paper addresses the processes by which our minds (with sensor inputs) work to form our stereoscopic perceptual concepts of the world, real or simulated, and the advantages (and problems) caused by our egocentric reduction of those data inputs. Discussion and evaluation of stereoscopic display systems compares current and future display systems.
An electroluminescent flat-panel display has been developed and recently introduced that fills any of the needs of the portable computer market. The display is very thin, yet rugged enough for the rigors of portability. It is highly integrated, and very reliable. It has the crisp and clear display image that is typical of high quality electroluminescent displays. The unit has a pixel matrix organization and pixel dimensions that are not only asthetically and ergonomically pleasing, but also make the display compatible with the most widely used software packages run on today's personal computers (Figure 1).
Thin-Film Electroluminescent (TFEL) display systems can consume large amounts of energy since their operation involves the repetitive charging and discharging of an inherently capacitive panel. Typically, energy stored in the panel capacitance is discharged into a resistance where it is dissipated in the form of heat. An energy recovery drive scheme involves the return of some portion of this stored panel energy into the supply from which it originated. In addition to recovery of the stored energy, the efficiency of the initial energy transfer may also be increased by use of an energy recovery scheme. This paper covers several topics relevant to the concept of energy recovery. First discussed are the panel and system characteristics, and the approximations which are used to allow simple modeling of a TFEL panel and associated drivers. Next, several conventional (non-energy recovery) drive schemes are analyzed, to be used as a reference in determining the energy savings which may result by the use of one of the energy recovery schemes which follow. A hypothetical drive scheme representing the mathematical limit on peak efficiency as well as the minimum peak charging current is examined. Finally, panel and system characteristics which are conducive to the implementation of energy recovery schemes are identified.
Model refinements representing ACTFEL characteristics in electrical terms for use by the drive system designer are presented. Of particular interest is the addition of a memory mechanism (analogous to space charge) that allows a drive pulse to influence the light production of the following pulse. Also of importance is the inclusion of insulator leakage resistances to explain the effects of dc and low frequency components in driving waveforms. Work remaining includes refinements to more closely relate light production to electrical quantities of the model.
Design considerations for large EL displays with high pixel density are reviewed. Physical limitations on materials and drive components restrict performance or dictate special fabrication techniques for displays larger than one half page.
Photothermal,deflection spectroscopy is used to determine optical absorption in ZnS:Mn thin film electroluminescent phosphors. The ZnS:Mn sample is immersed in a transparent liquid and optically pumped with a square-wave intensity modulated monochromatic light source. This produces a thermal gradient in the fluid which is probed by a He-Ne laser beam grazing the sample surface. The optical absorption in the sample can be related to the deflection of the laser beam by the thermal lens in the fluid. The relation of the absorption to the energy levels in ZnS:Mn will be discussed.
A thin film system of PC-EL type composed of two elements which are connected in series was constructed. The first element, a photoconductive element (PC), was a copper - and chlorine doped CdS thin film evaporated under vacuum. The second one was a thin film elec-troluminescent cell (EL) with a copper, chlorine and manganese - doped ZnS phosphor layer. This PC-EL system was supplied with sinusoidal voltage. Moreover a light signal in the shape of rectangular pulses, illuminating the PC element as being input, was applied. The output signals in the form of the luminance of light, emitted from the electroluminescent cell at various values of the supplying voltage frequency (ranging from 50 Hz to 10 kHz) were measured.
Soft copy autostereoscopic displays -- systems which present directly viewable three dimensional images from projected film or video sources -- involve formidable optical and information handling problems. Past attempts to develop such displays have resulted in systems which had serious limitations or were in fact theoretically nonfunctional. Recent developments in display optics, video technology and data transmission, however, make autostereoscopic displays a practical objective. Applications include aerial photo interpretation, medical imaging, molecular modeling and ultimately entertainment.
A cost effective and supportable color visual system has been developed to provide the necessary visual cues to United States Air Force B-52 bomber pilots training to become proficient at the task of inflight refueling. This camera model visual system approach is not suitable for all simulation applications, but provides a cost effective alternative to digital image generation systems when high fidelity of a single movable object is required. The system consists of a three axis gimballed KC-l35 tanker model, a range carriage mounted color augmented monochrome television camera, interface electronics, a color light valve projector and an infinity optics display system.
A new lens design, featuring user variable focus adjustment, has been incorporated into a raster scanned 3 CRT graphics and video projector. Since registration is accomplished internally in the crossed dichroic single lens design, good color convergence and focus can be maintained over a large projected image range of 6 to 12 feet diagonal. Field curvature and focus tilt compensation is separately adjustable for optimum focus on curved or flat screens at various projection angles.
The International Commission on Optics (ICO) defines the modulation transfer function (MTF) as the modulus of the Fourier transform of the line spread function. The purpose of this paper is to introduce, from an engineering standpoint, the MTF and its properties to the display engineer.
The successful development of a high luminosity, multicolor, AC-plasma display panel is reported. Area luminance values for both yellow and green are in excess of 200 fL. The brightness for red and blue is also excellent. The radiant efficiency of the color AC-plasma panel is at least twice that of neon AC-plasma displays; in addition, very little phosphor degradation or cell crosstalk is evident.
There is reported the successful design and development of a high resolution, large area AC gas discharge display addressable at a rapid update rate of over 30 frames per second. A special display panel designed for the development has a matrix of 1024 by 2048 pixels at 83 pixels per inch. The display employs special scanning techniques to reduce update artifacts in applications where information rapidly changes on the display. Brightness control features dimming without loss of update rate.
The Active Matrix Liquid Crystal Display (LCD) has been the subject of extensive Research and Development and the first products utilizing this technology are now available on a production basis. This paper will describe the enhancement that the active matrix brings to the performance of a LCD and establish the current product performance capability. From this baseline, the possibilities and expectations for a large area high resolution full color display will be explored.