Usability Evaluation of the Size of Small Touch Keys for the Smart Phone
Bo-Ram Kim, Tae Il Kim, Young-Jae Lim, Eui-S. Jung · Journal of Korean Institute of Industrial Engineers · 2012
This paper focuses on small touch key size and spacing that affect the usability of the smart phones. The experiments examined thirty-six different touch key designs, combinations of four touch key sizes (width (mm) ${\times}$ height (mm); $4{\times}4$ , $4{\times}7$ , $7{\times}4$ , and $7{\times}7$ ), and nine spacings (horizontal (mm) ${\times}$ vertical (mm); $0{\times}0$ , $0{\times}1$ , $0{\times}3$ , $1{\times}0$ , $1{\times}1$ , $1{\times}3$ , $3{\times}0$ , $3{\times}1$ , and $3{\times}3$ ). Forty participants volunteered in the experiment. The completion time, error rate, identification discomfort, and control discomfort were measured. The results revealed that the touch key sizes of $7{\times}7$ and $7{\times}4$ provide the best performance in terms of the error rate measure, while the touch key size of $7{\times}7$ provides the best results for other measures. In addition, touch key spacings of $1{\times}1$ , $1{\times}3$ and $3{\times}1$ are regarded as the best for all the measures. The results of this study suggest a practical approach for the small touch key design for the smart phones.