Alphanumeric input terminal

摘要

An alphanumeric input terminal is provided which allows a user to enter a sequence of characters that is compared to a stored valid entry code to determine whether access should be granted. The terminal displays a random number which the user adjusts by a rotatable knob to obtain a desired character. The character is entered by pushing the knob. The entered character is no longer displayed and the terminal displays another random character which is similarly adjusted and entered. This prevents observation of the characters being entered since only one character is displayed at any one time. By initially displaying a random character for each entry position, the adjustment made by the user to reach the selected character is different every time. This prevents one from determining the selected character by observing the direction and extent that the user rotates the knob before entering the character.