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

1. A mobile communication terminal comprising:

a display; and

a button configured to receive user inputs,

wherein the terminal is configured to turn on the display and display a lock screen thereon in response to a first pressing of the button while the display is turned off,

wherein, in response to the first pressing of the button, the terminal is further configured to initiate an authentication process of a user with no additional user input,

wherein the terminal is configured to release a lock state of the terminal for accessing functions of the terminal if the user is authenticated by the authentication process,

wherein the terminal is configured to continue the lock state of the terminal if the user is not authenticated by the authentication process,

wherein during the authentication process, the terminal is configure to have the display turned on,

wherein the terminal is configured to perform at least one function other than the authentication process in response to consecutive re-pressing of the button within a threshold time from the first pressing.

2. The mobile communication terminal of claim 1 , wherein the at least one function comprises activating a first camera of the terminal.

3. The mobile communication terminal of claim 2 , wherein said first camera is located on a side of the terminal on which the display is not located.

4. The mobile communication terminal of claim 3 , wherein the authentication process comprises at least one selected from the group consisting of:

a fingerprint authentication;

an iris authentication; and

a face authentication.

5. The mobile communication terminal of claim 4 , wherein the authentication process comprises the face authentication, wherein the face authentication comprises:

activating a second camera;

recognizing a face of the user from an image captured with the second camera; and

comparing the face of the user to pre-stored face information.

6. The mobile communication terminal of claim 5 , wherein the second camera is located on the same side of the terminal as the display.

7. The mobile communication terminal of claim 4 , wherein the authentication process comprises the iris authentication, wherein the iris authentication comprises:

activating a second camera;

recognizing an iris of the user from an image captured with the second camera; and

comparing the iris of the user to pre-stored iris information.

8. The mobile communication terminal of claim 7 , wherein the second camera is located on the same side of the terminal as the display.

9. The mobile communication terminal of claim 4 , wherein the authentication process comprises the fingerprint authentication, wherein the fingerprint authentication comprises:

acquiring information from the first pressing; and

comparing the acquired information to pre-stored fingerprint information.

10. The mobile communication terminal of claim 2 , wherein the terminal is configured to display an image that is being captured by said first camera.

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

receiving a first pressing of a button of the terminal while a display of the terminal is turned off;

in response to said first pressing, turning on the display and displaying a lock screen thereon;

in response to said first pressing, initiating an authentication process for a user with no additional user input;

receiving consecutive re-pressing of the button within a threshold time from the first pressing; and

in response to said consecutive re-pressing, performing at least one function other than the authentication process,

wherein if the user is authenticated by the authentication process, a lock state of the terminal is released for accessing function of the terminal,

wherein if the user is not authenticated by the authentication process, the lock state of the terminal continues,

wherein the display is turned on during the authentication process.

12. The method of claim 11 , wherein the at least one function comprises activating a first camera.

13. The method of claim 12 , wherein the first camera is located on a side of the terminal on which the display is not located.

14. The method of claim 12 , further comprising displaying an image that is being captured by the first camera.

15. The method of claim 14 , wherein the authentication process comprises at least one selected from the group consisting of:

performing a fingerprint authentication;

performing an iris authentication; and

performing a face authentication.

16. The method of claim 15 , wherein the authentication process comprises performing the face authentication, wherein performing the face authentication comprises:

activating a second camera;

recognizing a face of the user an image captured with the second camera; and

comparing the face of the user to pre-stored face information.

17. The method of claim 16 , wherein the second camera is located on the same side of the terminal as the display.

18. The method of claim 15 , wherein the authentication process comprises performing the iris authentication, wherein performing the iris authentication comprises:

activating a second camera;

recognizing an iris of the user with the second camera; and

comparing the iris of the user to pre-stored iris information.

19. The method of claim 18 , wherein the second camera is located on the same side of the terminal as the display.

20. The method of claim 15 , wherein the authentication process comprises the fingerprint authentication, wherein performing the fingerprint authentication comprises:

acquiring information from the first pressing; and

comparing the acquired information to pre-stored fingerprint information.