Effects of ambient illuminance on users' visual performance using various electronic displays

Abstract— This study investigated the effect of ambient illuminance (50, 500, 1500, 3000, 6000, and 9000 lx) on participants' visual performance using four electronic displays (conventional LCD under transmissive mode, conventional LCD under reflective mode, Ch‐LC display, and E‐ink display). Analysis results indicate that participants' visual performance shows significant difference under various ambient illuminance and electronic displays. The interaction between ambient illuminance and electronic display also has significant effect on participants' visual performance. When participants use the conventional LCD under transmissive mode, ambient luminance has no significant effect on participants' visual performance. However, participants' visual performance is significantly different under various ambient illuminances using the conventional LCD under reflective mode, Ch‐LC display, and E‐ink display. The conventional LCD under transmissive mode is the only choice at a lower illuminance of 50 lx. Higher illuminance (500 lx) for E‐ink displays may result in as good a performance as the conventional LCD under transmissive mode; nevertheless, much higher illuminance (1500 lx) for the conventional LCD under reflectance mode and Ch‐LC display may achieve better performance.     

Effects of ambient illuminance and electronic displays on users' visual performance for young and elderly users

Abstract— This study investigated the effects of age (young participants aged 20–30 and elderly participants older than 60), ambient illuminance (50, 500, 1 500, 3000, 6000, and 9000 lx) on participants' visual performance when using various electronic displays (conventional transmissive LCD, Ch‐LC display, and E‐ink display). Overall, the results indicated that participants' visual performance showed sign if icant difference among various ambient il luminance cond itions, electronic displays, and between two groups of participants. Significantly different visual performance was observed between young and elderly participants. The interaction among ambient illuminance, type of electronic display, and age had a significant effect on participants' visual performance. When participants used the E‐ink display, both young and elderly participants had significantly worse visual performance under an ambient illuminance of 50 lx compared to other illuminance settings. When participants used the Ch‐LC display, young participants had significantly worse visual performance under an ambient illuminance of 50 lx compared to other illuminance settings, but elderly participants had significantly better visual performance under an ambient illuminance higher than 1500 lx. When young participants used a conventional transmissive LCD, the ambient illuminance had no significant effect on their visual performance. When elderly participants use a conventional transmissive LCD, an illuminance of 50 and 6000 lx seem to have a detrimental effect on their visual performance.     

Effects of text/background color combination,ambient illuminance,and display type on discriminating performance for young and elderly users

Abstract— This study examined the effects of text/background color combinations (black‐on‐white, red‐on‐white, green‐on‐white, and blue‐on‐white), ambient illuminance (50, 500, and 12,000 lx), and display type (color electronic‐paper displays and conventional transmissive liquid‐crystal displays) on the discriminating performance of young and elderly users. The results showed that when participants used the color e‐paper display, young participants had significantly better discriminating performance than elderly participants under the text/background color combinations of black‐on‐white, green‐on‐white, and blue‐on‐white, whereas no significant difference was present between young and elderly participants under red‐on‐white. When participants used a conventional transmissive LCD, however, there was no significant difference between young and elderly participants under all text/background color‐combination settings. Young participants had substantially better discriminating performance under 500 and 12,000 lx than under 50 lx, whereas elderly participants had the best discriminating performance under 12,000 lx, followed by that under 500 lx, and the worst performance under 50 lx. Participants who used a conventional transmissive LCD had substantially better discriminating performance under 500 and 12,000 lx than under 50 lx. Participants who used the color e‐paper display had the best discriminating performance under 12,000 lx, followed by that under 500 lx, and the worst performance under 50 lx. The results can be the guild for the designers of color e‐paper displays.     

Development of active‐matrix electronic‐ink displays for handheld devices

Abstract— Interest in the use of electrophoretic displays for smart handheld applications has grown tremendously over the past few years. Since the launch of the Philips and E Ink joint development effort in February 2001, material parameters, TFT backplane, electronic hardware and software and modulization skills have been developed to make this promising display concept into a real product. The first commercial launch of active‐matrix electronic‐ink display modules is planned for mid 2004.     

A Flexible electronic‐paper display with an ultra‐thin and flexible LSI driver using quick‐response liquid‐powder technology

Abstract— A thin and flexible LSI driver with a thickness of less than 35 μm for a passive‐matrix‐driven Quick‐Response Liquid‐Powder Display (QR‐LPD?) was successfully mounted onto the flexible printed circuit (FPC) and the back substrates of a flexible QR‐LPD?. Amounted LSI driver on a plastic substrate shows no significant degradation in the driving performances and maintains physical flexibility without any connection failures. This technology can realize a fully flexible electronic paper in combination with a plastic‐substrate QR‐LPD? fabricated by a roll‐to‐roll process.     

Single‐layered multi‐color electrowetting display by using ink‐jet‐printing technology and fluid‐motion prediction with simulation

Abstract— This paper describes a single‐layered multi‐color electrowetting display (EWD) by using ink‐jet‐printing (IJP) technology and comparing different pattern electrodes with the use of the numerical investigations of ANSYS FLUENT®. This work consists of two parts: the first describes the design of implementing a single‐layered multi‐color EWD and the second demonstrates the application of ANSYS FLUENT® simulation in different pattern electrodes settings on the proposed EWD. The single‐layered multi‐color EW device was evaluated by using various colored oils without adopting a color filter. The single‐layered multi‐color EWD at a driving voltage of 25 V can achieve a maximum aperture ratio and reflectivity of 80% and 38.5%, respectively. The colored saturation of R, G, B oils can increase to 50% (NTSC: 13.3–27.8%). In addition, a radiate electrode at the required viewable area condition of 85% and force 5 * F^k, which results in ink stable contraction and a shorter response time of 50% (radiate vs. square), was proposed. The experimental results and simulation demonstrate that ink‐jet‐printing (IJP) technology along with the use of radiate electrodes can result in a single‐layered multi‐color EWD with a shorter response time.     

Effects of display area and corneal illuminance on oculomotor system based on eye-tracking data

Light reaching the retina elicits ocular symptoms that lead to some changes of human physiology and performance. However, its influence on ocular system is still unclear due to the lack of comprehensive analysis of ocular parameters. This study investigated the effects of corneal illuminance and display area on the oculomotor system based on eye-tracking technology, and a visual display unit was used as the illumination source. Results showed that oculomotor symptoms were sensitive to not only corneal illuminance but also display area. Fewer microsaccades, longer microsaccade duration and slower microsaccade peak velocity were found under high corneal illuminance, as well as longer fixation duration and faster saccade velocity. More microsaccades, shorter microsaccade duration and slower saccade velocity were observed under large display area. Pupil dilated with decreased corneal illuminance and increased display area. We conclude that oculomotor symptoms can be triggered by corneal illuminance and display area, which regulates human physiology and performance.     

Predicting the viewing direction performance of e‐paper displays with front light under ambient lighting conditions

The inherent advantages of reflective e‐paper displays (EPD) – wide viewing direction range and excellent readability even under bright sunlight – can be extended into low‐light conditions by the addition of an integrated lighting unit (ILU) such as a front light. A methodology for predicting the viewing direction dependence of ambient contrast and color from display measurements and illumination models is here applied to reflective EPD where the ILU is switched on. The predictions can be used to optimize task lighting. The ILU improves the indoor performance of EPD without compromising their superior daylight performance.     

Effects of contrast and ambient illumination on visual discomfort of autostereoscopic display

The conflict between vergence and accommodation is the main perceptual factors contributing to visual discomfort when viewing autostereoscopic display. The key factors relevant to the accommodation and vergence are the ambient illumination and the contrast. The current study was a 2 × 3 × 3 mixed design comparing VFSI and VIMS symptoms between 2D and 3D video clips with three contrast levels under three ambient illumination levels on the autostereoscopic display. Twenty participants were required to evaluate the degree of discomfort by filing out questionnaires after watching those video clips. According to the result analysis, the 3D viewing participants reported more severe symptoms compared to 2D. The moderate contrast conditions were found to be the optimum for viewing comfort. The difference between VFSI and VIMS symptoms become larger with increasing contrast. The results also suggested the optimum 3D illumination condition should not be too high to effectively relieve visual discomfort. VIMS symptoms were more sensitive to the changes in ambient illumination than VFSI. Moreover, significant interaction between contrast and ambient illumination was found. Participants felt the most comfortable in the combination effect of moderate level of contrast and the high level of ambient illumination.     

A 5.8‐in. phosphorescent color AMOLED display fabricated by ink‐jet printing on plastic substrate

Abstract— A flexible phosphorescent color active‐matrix organic light‐emitting‐diode (AMOLED) display on a plastic substrate has been fabricated. Phosphorescent polymer materials are used for the emitting layer, which is patterned using ink‐jet printing. A mixed solvent system with a high‐viscosity solvent is used for ink formulation to obtain jetting reliability. The effects of evaporation and the baking condition on the film profile and OLED performances were investigated. An organic thin‐film‐transistor (OTFT) backplane, fabricated using pentacene, is used to drive the OLEDs. The OTFT exhibited a current on/off ratio of 10⁶ and a mobility of 0.1 cm²/V‐sec. Color moving images were successfully shown on the fabricated display.     

The effects of graphic metaphor,gesture interaction,and form factor on e‐book performances and preferences

Reading e‐books on touch‐based mobile devices such as smartphones and tablet personal computer (PCs) are increasing. We conducted a comparative study on the usability of e‐books provided on smartphones and tablet PCs, which are typical touch‐based mobile devices. An experiment was carried out to see the effects of graphic metaphor and gesture interaction. This study evaluated reading speed, readability, similarity, and satisfaction for 16 combinations of e‐book interfaces (two Metaphor levels × four Display size and Screen modes × two Gesture levels). Overall, performance and subjective ratings showed better results on tablet PCs with larger fonts on a larger screen than on smartphones with smaller fonts on smaller screens. In the smartphone‐landscape mode, the effect of turning a page is a factor that hinders the speed of user reading. In contrast, the users’ readability, similarity, and satisfaction were higher when the page‐turning effect was provided. It showed faster reading speeds when a flicking interaction is provided on tablet PCs. From the standpoint of readability, the portrait mode was better on smartphones. Also, the tablet PC‐portrait mode was the most satisfactory.     

The effects of keyword cues and 3R strategy on children's e‐book reading

Various studies have found that electronic books (e‐books) promote learning, but few works have examined the use of e‐books along with an adaptive reading strategy for children. The current study implemented a method to extract keyword cues from e‐books to support e‐book reading with the read, recite and review (3R) strategy, and then examined the impact of this on children's reading performance. A pilot work recruited 76 first‐graders, developed the related reading tests and questionnaires. These were later used in assessing the effects of different interventions on the reading performances and perspectives of 74 first‐graders in the main study. Based on the findings of this work, the 3R strategy can be used as an effective approach to guide children's reading with e‐books. In addition, the use of keyword cues incorporated with retrieval practice can provide support with regard to Chinese characters and phonetic information in order to aid children's memorization of the story, thus promoting both phonological awareness and reading comprehension.     

Effects of bending curvature and text/background color-combinations of e-paper on subjects’ visual performance and subjective preferences under various ambient illuminance conditions

The study used the simulated e-paper to investigate how the bending radius of curvature (−10 cm, plane, and 10 cm) and 12 text/background color-combinations of e-paper affect subjects’ visual performance and subjective preference under various ambient illuminance conditions (200 and 500 lx). Analysis results indicated that the bending curvature and ambient illuminance did not significantly affect subjects’ visual performance. However, subjects visual performance differed significantly for different text/background color combinations of the simulated e-paper. When the background color of the simulated e-paper was set to yellow-like condition and the luminance of the text was low (2.2 and 4.6 cd/m²), subjects’ visual performance was best. Regarding the subjective preferences of subjects, the results of this research also demonstrated that the bending curvature, text/background color combinations and ambient illuminance all significantly affected the subjective preferences of subjects. Subjects exhibited the best preference under the following settings: bending curvature of the simulated e-paper set to plane; background color of the simulated e-paper set to yellow-like condition and low text luminance (2.2 or 4.6 cd/m²); high ambient illuminance (500 lx).     

Effects of post‐annealing on a‐Si:H TFT characteristics fabricated on stainless‐steel substrate

Abstract— A 14.1‐in.‐diagonal backplane employing hydrogenated amorphous‐silicon thin‐film transistors (a‐Si:H TFTs) was fabricated on a flexible stainless‐steel substrate. The TFTs exhibited a field‐effect mobility of 0.54 cm²/V‐sec, a threshold voltage of 1.0 V, and an off‐current of 10^?13 A. Most of the electrical characteristics were comparable to those of the TFTs fabricated on glass substrates. To increase the stability of a‐Si:H TFTs fabricated on stainless‐steel substrate, the specimens were thermally annealed at 230°C. The field‐effect mobility was reduced to 71% of the initial value because of the strain of the released hydrogen atoms and residual compressive stress in a‐Si:H TFT under thermal annealing at 230°C.     

Fabrication of pinhole/micro‐lens array for improving resolution of integral imaging 3‐D display

In this paper, we present a new fabrication of micro‐lens array (MLA) with pinhole array—pinhole/micro‐lens array (P/MLA) for integral imaging 3‐D display (II), which combine lithography and ink‐jet printing. A black circular groove array (BCGA) is used as pinhole array, and laser 3‐D microscope and a homemade setup have been used for the characterization of P/MLA. The results show that high‐precision P/MLA can be obtained using BCGA as templates. By controlling the driving voltage at different steps, the distance between nozzle and substrate, as well as the number of liquid droplets, P/MLA with smooth morphology, different sizes, good repeatability of geometry parameters, great uniformity of focusing, and good converging performance can be achieved. For demonstration, P/MLA with curvature, focal length, numerical aperture, and F‐number of 815.8 μm, 1.60 mm, 0.1311, and 3.8 are applied for the reconstruction in II, exhibiting good reconstruction performance with high resolution, and BCGA reduces the influence of stray light on II and improves the quality of the reconstructed image.     

Effects of display method,text display rate and observation angle on comprehension performance and subjective preferences for reading Chinese on an LED display

This study examined the effects of display method, text display rate, and observation angle on comprehension performance and subjective preferences for Chinese characters presented on an LED display. The factors and levels studied were as follows: four text display methods (rapid serial visual presentation ‘RSVP’, leading, paged view scrolling, and continuous scrolling), three text display rates (160 characters per min ‘cpm’, 240 cpm, and 320 cpm), and seven observation angles (−75°, −60°, −30°, 0°, 30°, 60°, and 75°). The results indicated that a display rate of 160 cpm was in general superior to 240 and 320 cpm for comprehension scores and subjective evaluations. The effects of display method and observation angle were found to be non significant. However, there was a significant interaction between display method and display rate. The results of this study were used to make ergonomics recommendations applicable to LED displays for determining optimum dynamic text display methods for Chinese characters.     

Effects of display properties on perceived color‐gamut volume and preference

Abstract— The effect of varying the color gamut of an extended‐gamut LCD on color appearance and preference was measured psychometrically in two experiments at each of two separate laboratories over a representative set of 10 images each. The first experiment measured the effect of color gamut on appearance, and the effect on the appearance attribute colorfulness was shown to be relatively strong compared with other attributes as the volume of display color gamut is varied. Overall, colorfulness monotonically increased at constant sensitivity as the gamut area in xy chromaticities increased while tending to become less and less sensitive to increasing the gamut volumes in CIELAB and CIECAM02. In the second experiment, the overall preference indicated an optimal color gamut for the display gamut volume even though the results were shown to be highly scene dependent.     

Character‐contrast measurements on emissive displays using replica masks under uniform ambient illumination

A replica‐mask method is presented to measure the contrast of character strokes on emissive displays under carefully controlled illumination. The method accounts for veiling glare introduced into the detector by the bright areas surrounding the dark characters. A sampling sphere is used to provide a uniform diffuse surround. Measurements of the diffuse reflectances are provided with specular included and with specular excluded. For emissive displays, the contrast depends both upon the darkroom characteristics of the emissive display and its reflective characteristics. Details are provided to replicate the measurement procedure.     

Influence of the monocular near‐to‐eye display position on the visual system during dual‐task performance

Abstract— In this research project, the influence of different monocular near‐to‐eye display (NED) positions on user comfort has been investigated. In total, 43 subjects participated in tests; 22 used above and 21 below NED positions during dual‐task performance for 40 minutes. SSQ and VSQ questionnaires were used to compare the eyestrain and other sickness symptoms before and after the task performance for both display positions. According to the subjective test results, the NED position above the eye causes more symptoms than the position below the eye.     

In‐field evaluation of the modulation transfer function and the signal‐to‐noise ratio of electronic‐display devices

Abstract— This paper describes a charged‐coupled device (CCD) camera, which was developed for in‐field evaluation of the image quality of electronic‐display devices [such as cathode‐ray tubes (CRTs) and liquid‐crystal displays (LCDs)] used for medical applications. Contrary to traditional cameras for display‐image‐quality evaluation, this CCD camera does not require a sophisticated x‐y‐z translation stage for mounting and adjustment. Instead, it is handheld and pressed by gentle pressure against the display screen. It is controlled by a software package which was originally developed for display calibration according to the DICOM 14 gray‐scale standard display function (GSDF). This software package controls the camera gain when measurements are made at different display luminance, display test patterns, performs image analysis and displays the results of the measurements and calculations. The work concentrated on the measurement of modulation transfer function (MTF) and of signal‐to‐noise ratio (SNR) per display pixel. The MTF is derived from the Fourier transform of the line spread function (LSF). The single‐display‐pixel SNR is derived from the integration of the noise power spectrum (NPS) of a camera image taken of a display with a uniform luminance. It is demonstrated that the device can produce repeatable results in terms of MTF and SNR. MTFs were measured on three monochrome CRTs and five monochrome LCDs in order to study repeatability and similar quantities. The MTF was measured on a 5‐Mpixel LCD yielding values that lie within 3.5% of the average MTF at the Nyquist frequency and 4.0% of the maximum total sharpness (∫ MTF² df). The MTF was also measured on a 9‐Mpixel LCD, yielding values that lie within 9.0% of the average MTF at the Nyquist frequency and 8.0% of the maximum total sharpness. The SNR was measured eight times on a 3‐Mpixel monochrome LCD at nine digital driving levels (DDLs). At a DDL of 185, the mean SNR was 15.694 and the standard deviation (Stdv) was 0.587. At a DDL of 65, the mean SNR was 5.675 and Stdv was 0.120.