1. A method of controlling a mobile terminal, the method comprising: displaying a touch keypad on a touch screen of the mobile terminal, said touch keypad including an array of character input regions, a specific character input region including a first character symbol and a second character symbol, the first character symbol being larger than the second character symbol; displaying an output window above the touch keypad, said output window displaying character symbols touched on the character input regions; receiving a touch selection signal indicating a touch selection of the specific character input region; as a result of the received touch selection signal, displaying a new character input region which includes displaying the first character symbol in the specific character input region and then the second character symbol in the new character input region, the new character input region being displayed directly above and adjacent to the specific character input region, the first character symbol being displayed, as a result of the received touch selection signal, at a same proportional size as the first character symbol displayed in the specific character input region prior to the touch selection signal being received, the second character symbol being displayed, as a result of the received touch selection signal, at a larger size than the second character symbol displayed in the specific character input region prior to the touch selection signal being received; as a result of the displaying of the new character input region, continuously displaying the first character symbol and the second character symbol as long as the touch selection signal is received and while continuing to display the touch keypad; and displaying the second character symbol in the output window when the touch selection is released from the character input region.