Byeonghwa Choi

A study on the optimum curvature for the curved monitor

Curved displays have been actively developed beyond the limits of the conventional flat displays. The curved displays are known to be advantageous for immersion, preferences, and viewing convenience. As such, it is necessary to conduct ergonomic studies on the curvature of the curved display. In this study, experiments were conducted to determine the optimal curvature of the curved display for six kinds of contents. The results of the experiments showed that the optimal curvature is 560.9 mm at the standard viewing distance of 600 mm, which can be considered an evidence that there is an intriguing correlation between the viewing distance and the display curvature. It is expected that the results of this study would improve the existing display products and would provide ergonomic guidelines for the users.

Effects of Display Curvature and Task Duration on Proofreading Task Performance, Visual Fatigue, Visual Discomfort, and Display Satisfaction:

With more curved display products in the market and more exposure to such products, it is necessary to examine the effects of display curvature and task duration from the ergonomics perspective. The current study examined the effects of these two factors on visual performance, visual fatigue, visual discomfort, and display satisfaction during proofreading tasks. We incorporated five display curvatures (600R, 1140R, 2000R, 4000R, and flat) and five task durations (0, 15, 30, 45, and 60 min). Each of 50 individuals completed a 1-hr proofreading task at one of five display curvature conditions. The horizontal viewing distance was fixed at 600mm. Proofreading performance (speed and error rate), subjective visual fatigue [on ECQ (Eye Complaint Questionnaire)], physiological visual fatigue [CFF (Critical Fusion Frequency), blink duration, and blink frequency], visual discomfort (on VAS), and display satisfaction (on VAS) were measured. The highest mean proofreading speed was at 600R. The mean proofreading speed and error rate increased by 15.5% and 22.3%, respectively, over the 1-h task. The mean ECQ score and visual discomfort increased by 188.6% and 107.2% during 45 and 60 min of the task, respectively. The mean CFF and display satisfaction decreased by 0.49Hz and 11.2% during 15 and 15-45 min of the task. A polynomial regression model for subjective visual fatigue was developed (adjusted R2 = 0.6). These findings can be used when determining ergonomic display curvatures and predicting visual fatigue.

Depth sensitivity of stereoscopic displays

Depth sensitivity is considered one of the factors influencing 3D displays the most. In this paper, the perceptual 3D depth was quantitatively measured to compare the depth difference among the display devices. No difference was found in the typical display performance among the devices, but the subjective evaluation of the depth sensitivity where the disparity was varied showed that the organic light emitting diode (OLED) had the highest performance, mainly due to its almost 0% crosstalk, one of the features of OLED. Crosstalk is a form of image superposition that greatly affects the depth sensitivity. The experiment results showed that the quantitative depth sensitivity varies due to geometric factors such as disparity, viewing distance, and subjective sensitivity, depending on the display image characteristics, such as crosstalk and contrast.

Determining Ergonomic Smartphone Forms With High Grip Comfort and Attractive Design

Objective: The authors aimed to identify ergonomic smartphone forms by investigating the effects of hand length, four major smartphone dimensions (height, width, thickness, and edge roundness), and smartphone mass on grip comfort and design attractiveness. Background: Despite their potential effect on grip comfort and design attractiveness, the dimensions specified above have never been simultaneously considered in a study investigating smartphone gripping. Method: Seventy-two young individuals participated in a three-stage study. Stage 1 determined the ranges of the four smartphone dimensions suitable for grip comfort and identified the strengths of their influences. Stage 2 investigated the effects of width and thickness (determined to have the greatest influence) on grip comfort and design attractiveness. Mock-ups of varying masses were fabricated using the dimensions determined during the first two stages to investigate the effect of mass on grip comfort and design attractiveness in Stage 3. Results: Phone width was found to significantly influence grip comfort and design attractiveness, and the dimensions of 140 × 65 (or 70) × 8 × 2.5 mm (height × width × thickness × edge roundness) provided high grip comfort and design attractiveness. The selected dimensions were fit with a mass of 122 g, with masses in the range of 106–137 g being comparable. Conclusion: The findings of this study contribute to ergonomic smartphone design developments by specifying dimensions and mass that provide high grip comfort and design attractiveness. Application: The dimensions and mass determined in this study should be considered for improving smartphone design grip comfort and attractiveness.

The crease perception in flexible display

There is a growing possibility applied to the foldable display for mobile devices because consumers want to see the big screen and they prefer mobile devices easy to carry around. However, a foldable display has crease because it generally uses laminated films or plastic substrates. In this study, we conducted the experiments in which people perceive crease on the flexible display for the various display viewing environments. The result shows that subjects most easily perceived crease in a bright room and panel off-state when the folding radius is 5 mm (5R). They perceived crease at an average height of 143 µm in that condition. The subjects perceived crease at an average height of 185.5 µm in the outdoor with display off condition. Also we analyzed that the subjects perceived the crease better when the folding radius of the flexible display was smaller than 5R. We expect that this study will contribute to the standardization of the new assessment method and to setting perception standards for the flexible display.

67.2: Perceptual Brightness Analysis of 2D and Stereoscopic 3D Displays

In a 3D stereoscopic display, transmissive losses in the shutter glasses cause a reduction of luminance compared to a 2D display. In stereoscopic 3D, evaluation of perceptual brightness through assessment of both of bright and dark luminance levels is needed. This study compares perceptual brightness of 2D and 3D with shutter glasses between AMOLED displays and LCDs considering simultaneous contrast. When 3D luminance of an AMOLED is 12% lower than an LCD as viewed through shutter glasses, according to a comparison based on perceptual contrast length, the displays are perceived as having the same brightness range.