Abstract: A printing device is implemented to activate a hidden function by inputting tap sequences on a tap screen. The hidden function includes displaying an icon of a title of a secret document on a display screen without showing the content of the secret document. A method for activating the hidden function using tap sequences is also disclosed. The method compares the input tap sequences with a plurality sets of predetermined codes, each of which corresponds to a hidden function. When the input tap sequences match one set of predetermined codes, the method activates and executes the hidden function. By executing the hidden function, the secret document is printed. The tap sequences are tapping actions that do not generate tangible symbols that are reviewable on the tap screen. By doing so, the confidential document is further protected.

Abstract: A printing device is implemented to activate a hidden function by inputting tap sequences on a tap screen. The hidden function includes displaying an icon of a title of a secret document on a display screen without showing the content of the secret document. A method for activating the hidden function using tap sequences is also disclosed. The method compares the input tap sequences with a plurality sets of predetermined codes, each of which corresponds to a hidden function. When the input tap sequences match one set of predetermined codes, the method activates and executes the hidden function. By executing the hidden function, the secret document is printed. The tap sequences are tapping actions that do not generate tangible symbols that are reviewable on the tap screen. By doing so, the confidential document is further protected.

Abstract: A printing device is implemented to activate a hidden function by inputting tap sequences on a tap screen. The hidden function includes displaying an icon of a title of a secret document on a display screen without showing the content of the secret document. A method for activating the hidden function using tap sequences is also disclosed. The method compares the input tap sequences with a plurality sets of predetermined codes, each of which corresponds to a hidden function. When the input tap sequences match one set of predetermined codes, the method activates and executes the hidden function. By executing the hidden function, the secret document is printed. The tap sequences are tapping actions that do not generate tangible symbols that are reviewable on the tap screen. By doing so, the confidential document is further protected.

Abstract: A printing device is implemented to activate a hidden function by inputting tap sequences on a tap screen. The hidden function includes displaying an icon of a title of a secret document on a display screen without showing the content of the secret document. A method for activating the hidden function using tap sequences is also disclosed. The method compares the input tap sequences with a plurality sets of predetermined codes, each of which corresponds to a hidden function. When the input tap sequences match one set of predetermined codes, the method activates and executes the hidden function. By executing the hidden function, the secret document is printed. The tap sequences are tapping actions that do not generate tangible symbols that are reviewable on the tap screen. By doing so, the confidential document is further protected.