Method for automatic determination of validity or invalidity of input from a keyboard or a keypad

The method for automatic determination of validity or invalidity of input from miniaturized keypads or keyboards, in which more than one key is operated at the same time, includes designating a number of keys as principal keys and assigning each key neighboring each principal key as nearest neighbor or next nearest neighbor and then testing each signal produced by key operation. The signal is valid if it is produced by operation of only one single key. However testing continues if two or more keys produce the signal. Then the signal is valid when the two or more keys are correlated in an unambiguous principal key-nearest neighbor key relationship. If not, testing continues further and the signal is valid if the plural keys are correlated in an unambiguous principal key-nearest neighbor key-next nearest neighbor key relationship. Otherwise the signal is an invalid key input.