This paper concerns how to make automotive displays easy to use. Five questions are examined from the perspective of the general human factors and automotive-specific literatures. They are: Which kinds of displays are best for which tasks? How big should letters and numbers be? How should displays be arranged? How should gauges be marked? How well do drivers understand messages? In addition, examples of good and bad automotive displays are provided along with recommendations for improving the design process.
An experiment was conducted to determine whether socalled feature displays allow for faster and more accurate processing compared to object displays. Previous psychological studies indicate that features can be processed in parallel across the visual field, whereas objects must be processed one at a time with the aid of attentional focus. Numbers and letters are examples of objects; line orientation and color are examples of features. In this experiment, subjects were asked to search displays composed of up to 16 elements for the presence of specific elements. The ability to detect, localize, and identify targets was influenced by display format. Digital errors increased with the number of elements, the number of targets, and the distance of the target from the fixation point. Line orientation errors increased only with the number of targets. Several other display types were evaluated, and each produced a pattern of errors similar to either digital or line orientation format. Results of the study were discussed in terms of Feature Integration Theory, which distinguishes between elements that are processed with parallel versus serial mechanisms.
The paper discusses about different ways of introducing a HUD (Head-Up Display) in a car. Will the combiner be sealed in or to the windshield or fixed separately from it. In one case the aesthetic is better but with aberration and relay optics complications mainly because of the curvatures of the windshield. In the second case, we have a simplification from an optical and engineering point of view. Shall we use data visualization at a fixed position from the driver. Or would it be interesting to have a possibility to vary the distance of the displayed information, and how to do this. Then we proceed to an analysis of the combiners optimum recorded phase distribution. Chromaticity aspect of the holographic combiner is also discussed.
A high performance multiple color automotive head-up display system using a holographic element embedded within a standard automotive windshield is described. The system uses an optical system designed to compensate the aspheric curvature characteristics of the windshield and to project the display ahead of the vehicle. The image source is a high contrast transmissive liquid crystal display illuminated with a high intensity white light source. The display is clearly visible against all ambient light conditions tested. The system has been designed for volume production.
The automobile instrument panel is undergoing a revolutionary transition from mechanical and electromechanical displays to all-electronic displays. This is not an easy transition in that the "ideal" automotive display does not exist and all principal candidates have significant limitations. To identify the obstacles standing in the way of successful application of these candidate displays, we examine these limitations from the view of system performance and cost, concluding that innovative approaches to implementing the electronic control of the display can both improve display performance and reduce system cost. Specifically, the development of a high performance, cost effective thin-film transistor (TFT) technology is essential to the successful implementation of automotive quality flat panel dot matrix displays. The potential of competitor TFT technologies will be assessed for their ability to provide the performance required in mature flat panel displays.
A flexible format dot matrix electronic instrument cluster (EIC) permits display graphics redesign without hardware changes. The main objective of this design is to illustrate the flexibility of the dot matrix format by presentation of three radically different graphics themes of the same driver information. Some existing production hardware was utilized to illustrate the feasibility of the concept and to reduce the development time. A CAE Instrumentation Simulation System provides the capability for EIC graphics design, alteration, and evaluation prior to actual implementation. The system consists of a high performance graphics workstation equipped with a software paint system and an i age digitizer. Existing automotive display graphics may be loaded into the system through a scanning CCD camera where they may then be colored, positioned, or scaled for use with new designs. A dot matrix graphics software subroutine package enables fast display updates of critical information. Two key techniques developed for the dot matrix EIC application include software double buffering of the displayed images and high
A very high contrast liquid crystal display ( VHC ) was developed. The VHC is based on 3 technologies; light shielding black mask, the positive mode twisted nematic configuration and an inversed driving method. Maximum contrast ratio exceeds 1,000, and thus it realizes a "bleed-through" free dashboard display. The VHC has some additional advantages, such as little temperature dependence in ON-color, fast switching speed and so on. Typical usages of the VHC in the instrument panels are described.
Electro-optical contrast ratio studies are made on polymer dispersed liquid crystal (PDLC) films with regard to automotive displays. Various methods of measuring and defining contrast ratio are compared and the dominating factors controlling each method are evaluated as related to PDLC displays. These methods are discussed in relation to the illumination technique used for display cells. Transmissive and reflective mode PDLC display test cells are measured with both black on white and white on black symbology. For evaluating direct view displays, contrast ratio measurements are made by using a TV/Video analyzer system. With transmission mode test cells, the contrast ratio is dependent upon the angle of illumination, and maximum values are observed with illumination angles in the range of 25-45° off normal, depending upon the PDLC film properties. Contrast ratio values from direct view lab models were in the 20-28 range for transmission mode displays and 10-26 for reflective displays. The use of colored filter segments in the reflective model resulted in similar contrast for all colors as for white. The lab models showed excellent viewability in bright ambient light, even direct sunlight, with increased brightness offsetting some decrease in contrast ratio.
Liquid crystal displays are beginning to be used for automotive applications. However, so far their use has been limited to relatively simple, low-information content displays. It is anticipated that with the advent of cost effective active matrices, the penetration of liquid crystal displays will be dramatically accelerated. The active matrix will both improve the performance and extend the applicability of LCDs in the automotive environment. It will impact monochrome and full-color displays; direct view and projection displays; and fixed-format alphanumeric and simple graphic displays as well as high resolution graphic displays. This paper will review the electro-optic bases of active matrix liquid crystal displays and the current research, development and commercial status of these displays. The two most promising active matrix technologies are based on low-temperature, amorphous and polycrystalline silicon. Particular emphasis will be placed on specific technical aspects of the amorphous silicon and polycrystalline silicon active matrix technotgies and how they relate to display performance for automotive applications.
The Liquid Crystal Shutter (LCS) is being developed for the automotive market. Liquid crystal material that meets operation to 85°C has been screened. Thin film heaters have been explored to obtain -40°C operation. Sunlight viewability has been improved and system colors have been matched to standard vacuum fluorescent automotive instrumentation. Successful completion of automotive humidity and thermal cycling tests have led to the adaptation of a flex connector.
A new type of low-loss, high-intensity projector is described for possible use in full-color reflective head-up or other automotive displays. The device is based on light shutters made from polymer dispersed liquid crystals (PDLC) which avoid the use of light-absorbing polarizers. Voltage-controlled Rayleigh scattering from PDLC shutters placed in parallel additively mix three primary colors produced by dielectric dichroic mirrors from white light, providing for arbitrary colors of the outgoing light. High-intensity and low heat dissipation due to the scattering-induced light attenuation that is possible from refractive index-matched PDLC shutters yields bright color and high-intensity large-scale projection. The light intensity yield exceeds that of conventional electrically-controlled light modulators by at least a factor of two. With the addition of an active matrix PDLC shutter, this system can replace the CRT in high information content automotive displays.
In this paper we review the requirements for displays used in automotive applications. Data is presented for PIN diode driven active matrix liquid crystal displays capable of operating over a wide temperature range (-40 C to 85 C). These displays offer wide viewing angle (+/-50 H and +15/-30 V), high contrast ratio (20:1), full color, and are being made today with resolutions of 164 lines per inch and up to 10" diagonal size. The active matrix displays have been fabricated to operate in the reflective, transmissive and transflective modes. This flexibility allows the displays to be used in many configurations from a simple backlit or reflective mode to incorporation in a head up display. The high resolution of these displays will allow a wide range of information to be displayed ranging from simple speedometer readings to detailed output from a navigational system such as a road map.
Polymer-dispersed liquid crystal (PDLC) films, consisting of micrometer-sized liquid crystal (LC) droplets dispersed in a polymer matrix, have considerable promise for a variety of electro-optic applications. VVe report the first measurements of the electro-optic performance of PDLC films over an extended temperature range. These properties are strongly sensitive to the liquid crystal microdroplet size. Calorimetric studies have shown that the droplet size is controlled by the rate at which the film is cured while the operating temperature range is determined, not by cure rate, but by the choice of liquid crystal and polymer matrix material. We have measured transmittance vs voltage and response time characteristics of PDLC films for temperatures from -10°C to 60°C. For thin (≈ 17.5 μm) films, transmittance of 70% or greater is achieved over this entire temperature range for driving voltages below 60 Vrms. Off-state transmittance of collimated light) is typically about 17o. The threshold voltage, at which transmittance begins to increase from its off-state value, and the voltage needed to achieve maximum transmittance both decrease with increasing temperature. Response times are rapid compared to those of conventional nematic liquid crystal devices. At a 60 Vrms driving voltage, rise time decreases from about 250 μs to 500 μs as temperature increases from -10°C to 60°C; even shorter rise times are measured at higher driving voltages. Decay times are nearly independent of voltage at temperatures above 0°C; at subzero temperatures, decay time increases with increasing voltage. This behavior can be explained in terms of molecular reorientation within the PDLC film. Decay times at -10°C range from 300 ms to 600 ms for voltages between 60 and 120 Vrms ; at temperatures above 15°C, decay times are below 50 ms for all voltages in this range. These results suggest that PDLC films of 12-25µm thickness are promising systems for future automotive displays.
A low cost Head-Up Display (HUD) for an automobile has been developed using the windshield as the optical scene combiner. The HUD system parameters have been optimized and tailored for the automotive industry through several prototype stages and human factors engineering reviews.
Older drivers present unique challenges to the display designer. Approximately 30 percent of all drivers in the U.S. are over 50 years of age. Visual impairment, e.g., presbyopia, begins after 40. After age 55, approximately 91 percent of the population use bifocals. Unfortunately, bifocals with significant add power create zones of decreased acuity in the critical instrument panel viewing distances of 500-800 mm. In this paper, the demands for vision in driving are related to the special visual disabilities associated with the older driver, such as increased sensitivity to glare, high contrast ratio blurring of electronic displays and increased time for target recognition. A computer legibility model is presented to relate the principal factors in design, namely character height and width, viewing distance, contrast ratio and background luminance with legibility impairment associated with various age groups. Implications of model predictions to display design are discussed.
Lighting continues to evolve. From the introduction of the incandescent lamp over 100 years ago to metal halide technology, the user is faced with an ever increasing number of choices. Each technology has its own set of advantages and limitations. Metal halide with its high efficacy, white light, long life and compact size is finding its way into many lighting applications; replacing the more mature technologies. Developments in metal halide products over the past five years have expanded the available choices. Many new product families have been added which provide the user with unique benefits which overcome some of the limitations found in the standard products.
New developments in industrial lighting systems have greatly increased industrial production levels and also have helped to improve quality in the products produced. An examination from the invention of artificial light through to modern, highly efficient, reliable lighting systems for industrial production illustrates how much our current civilization depends upon lighting and the continuing promise presented for the future.
The spectral and temperal characteristics of light sources are important considerations to optimize the performance of a lighting system to meet the needs of the receiver. The output of sources varies by wave length and may peak in the ultra violet, visible or infra-red portion of the spectrum. Variations in the supply frequency (dc, 60 hertz, etc) and the wave shaping provided by the ballast needed for some lamps plus the lamp operation characteristics will produce changes in output with time. Proper selection of the lamp and its ballast when required can achieve optimum performance to meet the receiver needs and any added system requirements.
A 150W compact xenon arc lamp is described, utilizing a mixed-oxide cathode to achieve 85% lumen maintenance at 2,000 hours and positional/brightness stability 7.6 times better than that of conventional lamps. Aspects of lamp stability are defined, and a method for measuring stability is described.
A relatively new type of laser, the copper vapor laser (CVL) has shown much potential in the area of high-speed imaging by helping extend the capabilities of existing high-speed recording equipment. It has helped image data or events that might have otherwise been obscured or lost by a blurred image, inadequate light, or too low a frame rate.
Simple photometric relationships governed the previous imaging systems in film and video applications. More recently the introduction of wide-band image sensors, particularly those based upon silicon, has required greater sophistication in the understanding of spectral considerations for their proper application. Such understanding can lead to the optimization of performance, or the ability to operate-in applications which were difficult or impossible with previous sensors. Of particular significance is the effect on performance of available lenses.
Reflective fiducial marks, or targets, permit the location of objects relative to a robot. Usually, object luminance falls off as the inverse square of the distance from the source. However, selected retroreflective marks illuminated by a source near the sensor can have luminances which are almost constant over a wide range of distances and which are also over one hundred times greater than those of diffuse reflectors. Retroreflective materials and illuminator design guidelines are discussed.
This paper discusses some accuracy related problems of a vision inspection system which were studied in developing such a system for a drill inspection. A structured illumination device was designed to obtain high quality image of a drill. The errors in image conversion was studied and it was found that the variation of the illumination intensity changed the dimension of the parts due to the quantization effect of the digital computer. A CCD linear array based light monitoring system was proposed to provide the information about the light distribution of the image. Several possible control schemes upon the output of the monitoring system are discussed.
An analysis is conducted with a finite size lamp arc located at the focal point of a paraboloid reflector. It is shown how the illumination is affected when, the focal length is slightly changed, the lamp arc is slightly out of position and the arc size is changed. Also, the sensitivity rate is determined due to these changes. This provides available tolerances and better understanding of the system before its fabrication. Case studies are discussed using standard conic sections. In one case, a rectangular beam is desired and in another case the reflector is modified, without redesigning to double the beam cone size. After modification, a three dimensional beam pattern was measured and plotted. Some concepts are discussed showing unique optical system for dynamic simulations. An application of optical beats is discussed. The beats phenomenon is quite popular in the field of sound and vibration studies. Here it will be shown how 'beats' could be used for optical adjustments where a linear photodiode array is used as an image receptor, such as in the case of a facsimile document scanner.
This paper will present the applications of fiber optics in machine vision. Fiber optics extend the lighting and image acquisition options available to the fabricators and users of vision equipment. Areas addressed include: structured illumination with fibers and associated optics, accessing space limited areas, and relaying images to a remote location via coherent fiber optics.