Mobile terminal

1. A mobile terminal comprising:

a foldable case including a front case and rear case and configured to be in one of an opened flat state in which a protrusion of the rear case is slid inward into a sliding area of the front case, a folded state in which the protrusion of the rear case is slid outward from the sliding area, and an intermediate state between the opened flat state and the folded state;

a flexible display on a surface of the foldable case; and

electrical components between the front case and the rear case,

wherein the rear case includes a corrugated middle portion configured to flex when the mobile terminal is changed from the opened flat state to the folded state or from the folded state to the opened flat state,

wherein the corrugated middle portion disposed on a side of the rear case is exposed to the outside,

wherein the corrugated middle portion includes a first corrugation area located in a center of the corrugated middle portion, a second corrugation area located on a first side of the first corrugation area, and a third corrugation area located on a second side of the first corrugation area,

wherein a width of the first corrugation area is greater than a width of one corrugation of the second corrugation area or one corrugation of the third corrugation area to provide a space for a coupling hole formed on the first corrugation area, and

wherein the front case includes a protruded area located on a center of the front case, the protruded area corresponding to the coupling hole formed on the first corrugation area.

2. The mobile terminal of claim 1 , wherein the protrusion of the rear case moves in the sliding area so as to correspond to a difference in length between the front case and the rear case.

3. The mobile terminal of claim 1 , wherein the corrugated middle portion includes a plurality of slits formed on a lateral side of the rear case.

4. The mobile terminal of claim 1 , wherein a thickness of the corrugated middle portion varies from a first thickness to a second thickness periodically.

5. The mobile terminal of claim 1 , wherein non-flexible electronic components are disposed on the rear case as positions outside of the corrugated middle portion.

6. The mobile terminal of claim 1 , wherein the corrugated middle portion of the rear case includes a plurality of slits and ribs alternating with each other.

7. The mobile terminal of claim 6 , wherein a thickness of a corresponding rib is greater than a thickness of a corresponding slit in the corrugated middle portion, and

wherein the corrugated middle portion comprises an external side surface of the mobile terminal.

8. The mobile terminal of claim 1 , wherein the sliding area of the front case has a first depth, and

wherein the protrusion of the rear case is inserted into the sliding area as much as the first depth when the foldable case is in the opened flat state.

9. The mobile terminal of claim 8 , wherein the protrusion of the rear case is inserted into the sliding area to a second depth smaller than the first depth when the foldable case is in the intermediate state.

10. The mobile terminal of claim 9 , wherein the protrusion of the rear case is inserted into the sliding area to a third depth smaller than the second depth when the foldable case is in the folded state.

11. The mobile terminal of claim 1 , wherein the foldable case further includes:

a first region including a central portion of the foldable case, the first region being bendable;

a second region positioned between the first region and an end of the mobile terminal; and

a third region positioned between the first region and another end of the mobile terminal.

12. The mobile terminal of claim 11 , wherein the second and third regions are flat.

13. The mobile terminal of claim 11 , further comprising:

inflexible components including a battery and a PCB positioned in at least one of the second and third regions.

14. The mobile terminal of claim 1 , wherein the flexible display includes a plurality of layers, at least one of the plurality of layers includes a silicon (Si) material.

15. The mobile terminal of claim 1 , wherein the rear case includes:

a first band disposed on the rear case in a longitudinal direction; and

a second band disposed on the rear case in the longitudinal direction, a portion of the second band being overlapped with the first band,

wherein the first band includes a plurality of convexities,

wherein the second band includes a plurality of concavities facing the plurality of convexities of the first band, and

wherein at least a portion of the plurality of the convexities is fitted in the plurality of concavities.

16. The mobile terminal of claim 1 , further comprising:

a wire connecting an end of the case to another end of the case; and

a winding gadget connected to the wire and configured to apply tension to the wire.

17. The mobile terminal of claim 1 , further comprising:

a controller configured to control the flexible display based on a change in the state of the case.

18. The mobile terminal of claim 17 , wherein the controller controls the flexible display based on at least one of a speed of the change in the state of the foldable case, an amount of the change in the state of the foldable case, and a direction of the change in the state of the foldable case.

19. The mobile terminal of claim 17 , wherein the controller controls the flexible display to display contents on a full screen when the state of the foldable case changes from the folded state to the opened flat state.