| 摘要 |
PROBLEM TO BE SOLVED: To provide a mobile phone to which a user can enter characters faster than the conventional state. SOLUTION: At least one joy key, two shift keys, and six keys are provided at a wide front side of nearly a rectangular solid shape of the mobile phone or a small-sized PDA (personal digital assistant) and at least 20 keys are provided to the rear side. The keys are arranged as shown in Figure, the user grips the mobile phone by both the hands without placing the mobile phone on a desktop or a laptop. Since the user can enter any of 26 alphabets by one depression of one of 10 fingers of each hand by using them entirely without the need for shift operations by using the shift key or the like, the user can enter characters at an ultrahigh speed in comparison with the operations by one thumb. The character keys are arranged such that the characters are laid out in the order of higher appearance frequency in a line and the shortest moving distance off the fingers and the rhythm of alternate key depression by both the left and right hands are taken into account. COPYRIGHT: (C)2003,JPO
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