Abstract
Wearable device has been becoming popular over the past few years. With the fast development of the computer network technology, the functions and performance of head mounted displays are constantly making progress. There are few researches addressing the issues of user interface design of head mounted display.This study considered the font size and font lightness of Google Glass to determine the best setting of user interface elements in see-through head-mounted display and investigate the usability in different application situations. In here, the reading completion time, error rate, and the subjective measures including SUS and NASA-TLX were collected. Then, the critical fusion frequency value and eye fatigue scale were collected to evaluate the differences of visual fatigue after reading articles using Google Glass. Lastly, the users are invited to assess the overall feelings and preference through interview.The results indicated that the completion time of women was better than men. The font size, font lightness and reading situation showed significant effects on reading performance and subjective comfort level. In static situation, the best font size was 24 pt and the best font lightness was 165. In dynamic situation, the best font size was 32 pt and the best font lightness was 210. From the overall evaluation, the study observed that the font size must be greater than 24 pt, 32 pt was the best font size and font lightness must be brighter than 165, and 210 was the best. In addition, the results also indicated when users are reading on Google Glass at a static situation, the measures in eye fatigue, usability and mental workload were better than those in a dynamic reading situation. The results of this study can provide very important reference information for interface design of Google glass related products.