Flexible display apparatus

1. A flexible display device comprising:

a display unit configured to display information on a screen, the screen being configured to be expanded or reduced;

a sensing unit configured to sense an expansion or a reduction of the screen; and

a control unit configured to:

display first information on a first region corresponding to a first distance of the screen of the display unit,

expand the screen by a second region corresponding to a second distance,

display, on the second region, second information time-series associated with the first information,

receive a request for selecting an attached-file item included in the second information,

detect the screen is expanded by a third region corresponding to a third distance while receiving the request for selecting the attached-file item, and

display, on the third region, a preview information of the selected attached-file item.

2. The flexible display device of claim 1 , wherein the second information is information that is transmitted or received, before the first information is received.

3. The flexible display device of claim 2 , wherein the first information is a first mail received from a counterpart, and

wherein the second information is a second mail sent to the counterpart by a user before the first mail is received.

4. The flexible display device of claim 3 , wherein each of the first mail and the second mail includes:

at least one of the attached-file item for indicating presence of an attached file, a sender item for identifying a person who sends a mail, and a reply item for replying to the mail.

5. The flexible display device of claim 4 , wherein the control unit receives a request to select a sender item included in the first mail and displays, on the second region, another mail sent by a sender corresponding to the selected sender item selected according to the received request.

6. The flexible display device of claim 4 , wherein the control unit receives a request to select a reply item included in the first mail and displays, on the second region, a reply mail window for replying to a counterpart having sent the first mail, according to the received request.

7. The flexible display device of claim 6 , wherein the first mail includes an attached file, and

wherein the control unit adds the attached file to a reply mail window based on an input of dragging or dropping the attached file into the second region.

8. The flexible display device of claim 1 , wherein the control unit sequentially displays other pieces of information, which is not displayed, on the second region when expansion of the screen is detected after a screen size of the display unit is expanded to a maximum size.

9. The flexible display device of claim 8 , wherein the control unit maintains the first information to be displayed on the first region while sequentially displaying, on the second region, the other pieces of information which is not displayed.

10. The flexible display device of claim 1 , wherein the control unit expands the screen by the third region corresponding to the third distance, and to display, on the third region, third information time-series associated with the second information.

11. The flexible display device of claim 10 , wherein the control unit switches the second information, which is displayed on the second region, to the third information, when the third information is selected and the screen is reduced by the third area.

12. The flexible display device of claim 10 , wherein the control unit stores the third information when the third information is selected and reduction of the screen is detected.

13. The flexible display device of claim 1 , wherein the control unit independently controls the first region and the second region.