OPERATION DEVICE, OPERATION METHOD, AND IMAGE FORMING APPARATUS INCLUDING AN OPERATION DEVICE

摘要

An operation device that displays a predetermined number of item keys among plural item keys on a predetermined screen so as to be enabled to be pressed down, includes: a determining unit configured to determine whether or not pressing down a display switching key to switch currently displayed item keys on the screen and display item keys that have not been displayed on the screen is successive pushes when the display switching key is pressed down; and a displaying-receiving unit configured to display a list of a larger number of item keys that have not been displayed on the screen than a number that has been set to the screen so as to be enabled to be pressed down if the determining unit determines that pressing down the display switching key is successive pushes.