Input interface suitable for touch panel operation on a small screen

Recent years have seen rapid widespread adoption of smart devices equipped with a small touch panel. Generally, a software keyboard is problematic despite the use of a small touch panel for input; however, the number of choices and the operational flexibility of the input characters are always equal. This is because an increase in the number of buttons reduces the size of each button, whereas retaining the button size would necessarily reduce the number of buttons. In this study, we propose a new character input interface suitable for a small screen. In addition, we con figured the input interface based on the proposed method, and report the experiments that were carried out to evaluate the interface. As a result, even though the input may be difficult when using the conventional method, the proposed method is hardly considered to influence the input performance.