A method for using one finger to press three separate keys on a three-dimensional keyboard designed to be mounted on a mouse

Here we propose and verify the feasibility of a new keyboard structure for keyboard-mounted mouse. Reducing the distance that fingers move while typing within a three-dimensional (3-D) key arrangement that fits along the fingers is effective for keyboard-mounted mouse, provided that each finger can separately press three different keys. Our objective was to design and test a method for separately being able to press three keys with a single finger, and in the process, reduce finger-moving distance. We analyzed 3-D finger motion while participants typed on a standard keyboard, and used this data to develop a 3-D layout for keys that are arranged along the fingers. Analysis of 3-D finger motion while using our new keyboard showed that the distance fingers traveled was 74 % less than that when using a standard keyboard (p < 0.05). Moreover, this did not result in typing mistakes caused by interference between the keys and finger movements. After typing 30 characters 20 times, the average input error rate in the 20th trial was 18 %, while the average error rate across all trials for the standard keyboard was 9.5 %. We conclude that our proposed 3-D keyboard can be used accurately with one finger while reducing the distance fingers must move. However, input mistakes were caused by finger linkage motion. In the future, we must devise a character-input algorithm that eliminates such erroneous input. We must also include the mouse function and evaluate the operability of the device in tasks that require keyboard and mouse use.