Activating display and performing additional function in mobile terminal with one-time user input

A method of operating a mobile communication terminal including a button and a display, the method comprising:

• sensing a single pressing of the button by a user while said display is to led off;
• in response to sensing of the single pressing of the button while said display is turned off, turning on said display and displaying a lock screen thereon;
• further in response to sensing of the single pressing of the button while said display is turned off, performing user authentication in addition to turning on the display with no additional user input onto the terminal, wherein the user authentication caused by the single pressing of the button with no additional user input onto the terminal is performed while maintaining the lock screen on the display;
• and
• upon completion of the user authentication caused by the single pressing of the button with no additional user input onto the terminal, releasing a lock state of the terminal if the user is authenticated.

A mobile communication terminal comprising:

• a display;
• a camera;
• and
• a button located outside the display;
• wherein the terminal is configured to turn on the display and display a lock screen in response to a user input received on the button while the display is turned off;
• wherein the terminal is configured to authenticate the user with no additional user input;
• wherein the display is turned on during the authentication;
• wherein the terminal is configured to release a lock state of the terminal for accessing functions of the terminal if said user is authenticated.

A method of operating a mobile communication terminal, the method comprising:

• receiving a user input on a button of the terminal while a display of the terminal is turned off;
• in response to the user input received on the button while the display is turned off, turning on the display and displaying a lock screen;
• authenticating said user with no additional user input, wherein the display is turned on during the authentication;
• and
• releasing a lock state of the terminal for accessing functions of the terminal if said user is authenticated, and
• continuing the lock state of the terminal if said user is not authenticated.