JPH0524528B

PURPOSE:To improve the operability of key input by providing a transparent sheet switching input means placed on a color liquid crystal display means. CONSTITUTION:When the power switch of a key input device 1 is turned on, only mode selecting keys 20 are displayed in green on an input panel 2. An operator who confirms these mode selecting keys 20 depresses, for example, a program generation mode key 20a if the wants to generate a program, and then, program generation keys 21 required for program generation are displayed in red, and the green display of mode selecting keys 20 is extinguished and only the program generation mode key 20a is displayed in red. Since keys are inputted through the input panel where a switching sheet is placed on the liquid crystal display plate to display keys in the area corresponding to each input key in color, keys to be used are distinctly discriminated from the other keys to effectively reduce the occurrence of input failure.