Flexible display devices

1. A flexible display device, comprising:

a display panel having a flat region, a bending region, and a boundary region therebetween;

a first protective structure having a first portion formed under the flat region and a second portion formed under the boundary region,

wherein the thickness of the first portion is substantially uniform, and

wherein the thickness of the second portion decreases along a direction from the flat region toward the bending region; and

a second protective structure having a third portion formed under the flat region and a fourth portion formed under the boundary region,

wherein the thickness of the third portion is substantially uniform,

wherein the thickness of the fourth portion decreases along a direction from the flat region toward the bending region, and

wherein the first protective structure and the second protective structure are spaced apart from each other with a gap therebetween.

2. The flexible display device of claim 1 , wherein the thickness of the second portion linearly decreases along the direction from the flat region toward the bending region.

3. The flexible display device of claim 1 , wherein the thickness of the second portion decreases in a stepped manner along the direction from the flat region toward the bending region.

4. The flexible display device of claim 1 , wherein each of the first and second protective structures includes a plurality of stacked films each having a different width.

5. The flexible display device of claim 4 , wherein thicknesses of the films are substantially the same.

6. The flexible display device of claim 4 , wherein widths of the films decrease by a substantially equal amount along a direction from an uppermost layer of the films toward a lowermost layer of the films.

7. The flexible display device of claim 1 , wherein each of the second portion and the fourth portion includes a plurality of holes and wherein depths of the holes increase along the direction from the flat region toward the bending region.

8. The flexible display device of claim 7 , wherein horizontal distances between the holes are substantially the same.

9. The flexible display device of claim 7 , wherein the depths of the holes increase by a substantially equal amount along the direction from the flat region toward the bending region.

10. The flexible display device of claim 1 , wherein the bending region is located at the center of the display panel and wherein the flat region is located at a side of the bending region.

11. The flexible display device of claim 1 , wherein each of the first and second protective structures is formed of at least one of the following materials: polyethylene (PE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene sulfide (PES), polypropylene (PP), and polycarbonate (PC).

12. The flexible display device of claim 1 , wherein the display panel includes:

a flexible substrate formed over the first and second protective structures;

an organic light-emitting diode (OLED) structure formed over the flexible substrate; and

an encapsulation layer formed over the OLED.

13. The flexible display device of claim 1 , further comprising an adhesive layer interposed between the display panel and the first and second protective structures.

14. The flexible display device of claim 13 , wherein the adhesive layer is formed of an acryl-based resin.

15. The flexible display device of claim 1 , wherein the gap is formed under the bending region.

16. The flexible display device of claim 15 , wherein a surface of the bending region of the display panel is exposed by the gap.