Determining the Optimal Size of Handwriting Character Entry Boxes for Pen-Based Systems

This paper presents two experiments to determine the optimal size of a box for the input of Chinese characters (called Kanji in Japanese) mixed with Japanese Kana (phonetic) handwriting characters on a tablet computer. The experiments involve an evaluation of boxes of different sizes. The results are assessed in terms of high performance factors (e.g., high character recognition rates, minimal stroke protrusions outside the character box) and subjective ratings (e.g., ease of writing and a minimum level of fatigue). The results show that the optimal size of character boxes for Kanji and Kana characters is around 1.44 x 1.44 cm. The experimental results also show that the optimal size is the same for both PDAs and Tablet PCs. The results provide important guidelines to designers who are concerned about the interplay between user comfort, input efficiency and output display efficiency. The knowledge obtained from our experiments on Tablet PCs will be added to the literature on optimal size for handwriting character entry boxes.