A Nonlinear Mapping-Based Virtual Touchpad for One-Handed Smartphone Operation

Smartphones with 6-inch or larger screens have become popular. However, such large-screen smartphones are difficult to operate with one hand. Widely used techniques for assisting the user in one-handed operation, such as iPhone’s Reachability and Android’s one-handed mode, reduce the display areas of screens, which degrades the benefits of large-screen smartphones. In this paper, we propose a virtual touchpad for a large-screen smartphone that uses nonlinear mapping to enable the user to manipulate distant areas as well as to accurately manipulate close areas. We conducted a preliminary experiment to compare eight instances of the proposed virtual touchpad with different mappings and conditions in a target selection task. In addition, we performed experiments to compare the three best instances of the virtual touchpad with conventional normal touchscreen operation and also to evaluate it in web browsing. The results show that the proposed virtual touchpad could reduce the target selection time and largely reduce the strain on the thumb.