Rollable display apparatus

1. A rollable display apparatus comprising:

a rolling drum; and

a flexible display panel comprising an end bonded to the rolling drum, the flexible display panel being windable around an outer circumferential surface of the rolling drum,

wherein the flexible display panel comprises:

a flexible substrate including a first surface on which a display device is arranged; and

a first protection film over the first surface of the flexible substrate,

wherein the first protection film comprises a first layer comprising an elastic polymer, and a second layer on the first layer and having a smaller surface frictional force than the first layer, and

wherein the second layer comprises a plurality of first grooves each indented in a depth direction of the second layer toward the first layer from a surface of the second layer facing away from the first layer.

2. The rollable display apparatus of claim 1 , wherein first grooves of the plurality of first grooves extend in a first direction that is parallel to a lengthwise direction of the rolling drum.

3. The rollable display apparatus of claim 2 , wherein intervals between first grooves of the plurality of first grooves in a second direction perpendicular to the first direction are different from one another.

4. The rollable display apparatus of claim 3 , wherein the intervals between the first grooves increase in a direction from the end to another end of the flexible display panel opposite to the end.

5. The rollable display apparatus of claim 2 ,

wherein the flexible substrate comprises a first region comprising the end, and a second region adjacent to the first region and farther from the rolling drum than the first region, and

wherein the plurality of first grooves is located in the first region of the flexible substrate.

6. A rollable display apparatus comprising:

a rolling drum; and

a flexible display panel comprising an end bonded to the rolling drum, the flexible display panel being windable around an outer circumferential surface of the rolling drum,

wherein the flexible display panel comprises:

a flexible substrate including a first surface on which a display device is arranged; and

a first protection film over the first surface of the flexible substrate,

wherein the first protection film comprises a first layer comprising an elastic polymer, and a second layer on the first layer and having a smaller surface frictional force than the first layer,

wherein the second layer comprises a plurality of first grooves each indented in a depth direction of the second layer from a surface of the second layer,

wherein first grooves of the plurality of first grooves extend in a first direction that is parallel to a lengthwise direction of the rolling drum,

wherein the flexible substrate comprises a first region comprising the end, and a second region adjacent to the first region and farther from the rolling drum than the first region,

wherein the plurality of first grooves is located in the first region of the flexible substrate, and

wherein a width of the first region in a second direction perpendicular to the first direction is twice or less of a perimeter length of the rolling drum.

7. A rollable display apparatus comprising:

a rolling drum; and

a flexible display panel comprising an end bonded to the rolling drum, the flexible display panel being windable around an outer circumferential surface of the rolling drum,

wherein the flexible display panel comprises:

a flexible substrate including a first surface on which a display device is arranged; and

a first protection film over the first surface of the flexible substrate,

wherein the first protection film comprises a first layer comprising an elastic polymer, and a second layer on the first layer and having a smaller surface frictional force than the first layer,

wherein the second layer comprises a plurality of first grooves each indented in a depth direction of the second layer from a surface of the second layer,

wherein first grooves of the plurality of first grooves extend in a first direction that is parallel to a lengthwise direction of the rolling drum,

wherein the flexible substrate comprises a first region comprising the end, and a second region adjacent to the first region and farther from the rolling drum than the first region,

wherein the plurality of first grooves is located in the first region of the flexible substrate,

wherein the flexible display panel comprises a display region in which the display device is located, and

wherein a boundary between the first region and the second region is located corresponding to ⅓ or less of a width of the display region in a second direction perpendicular to the first direction.

8. The rollable display apparatus of claim 1 , wherein first grooves of the plurality of first grooves are filled with an organic material.

9. The rollable display apparatus of claim 8 , wherein the second layer comprises an inorganic material, and surfaces of the plurality of first grooves are coated with a coupling agent.

10. A rollable display apparatus comprising:

a rolling drum; and

a flexible display panel comprising an end bonded to the rolling drum, the flexible display panel being windable around an outer circumferential surface of the rolling drum,

wherein the flexible display panel comprises:

a flexible substrate including a first surface on which a display device is arranged; and

a first protection film over the first surface of the flexible substrate,

wherein the first protection film comprises a first layer comprising an elastic polymer, and a second layer on the first layer and having a smaller surface frictional force than the first layer,

wherein the second layer comprises a plurality of first grooves each indented in a depth direction of the second layer from a surface of the second layer,

wherein the flexible display panel further comprises a pad unit located on the end, and a circuit substrate electrically connected to the pad unit,

wherein the rolling drum comprises an insertion groove extending in a lengthwise direction of the rolling drum, and

wherein the circuit substrate is inserted into the insertion groove.

11. The rollable display apparatus of claim 10 , wherein the circuit substrate and the pad unit are connected to each other by a flexible printed circuit board (PCB) comprising an integrated circuit, and the flexible PCB is bent along an outer surface of the rolling drum and extends within the insertion groove.

12. The rollable display apparatus of claim 1 , wherein the flexible display panel further comprises a second protection film on a second surface opposite to the first surface.

13. The rollable display apparatus of claim 12 , wherein the second protection film comprises a third layer comprising an elastic polymer, and a fourth layer having a smaller surface frictional force than the third layer, and the fourth layer is farther from the second surface than the third layer.

14. The rollable display apparatus of claim 13 , wherein the fourth layer comprises a plurality of second grooves each indented in a depth direction of the fourth layer from a surface of the fourth layer.

15. The rollable display apparatus of claim 14 , wherein second grooves of the plurality of second grooves are filled with an organic material.

16. A rollable display apparatus comprising:

a rolling drum; and

a flexible display panel comprising an end bonded to the rolling drum, the flexible display panel being windable around an outer circumferential surface of the rolling drum,

wherein the flexible display panel comprises:

a flexible substrate including a first surface on which a display device is arranged; and

a first protection film over the first surface of the flexible substrate,

wherein the first protection film comprises a first layer comprising an elastic polymer, and a second layer on the first layer and having a smaller surface frictional force than the first layer,

wherein the second layer comprises a plurality of first grooves each indented in a depth direction of the second layer from a surface of the second layer,

wherein the flexible display panel further comprises a second protection film on a second surface opposite to the first surface, and

wherein an interval between an end of the flexible substrate closest to the rolling drum and an end of the first protection film is greater than an interval between the end of the flexible substrate and an end of the second protection film.

17. The rollable display apparatus of claim 16 , wherein a pad unit is located between the end of the flexible substrate and the end of the first protection film.

18. The rollable display apparatus of claim 17 , wherein the second protection film comprises a first overlapping portion overlapping with the first protection film, and a second overlapping portion overlapping with the pad unit and separated from the first overlapping portion.

19. The rollable display apparatus of claim 18 , wherein the first overlapping portion comprises a plurality of second grooves each indented in a depth direction of the second protection film from a surface of the second protection film.

20. The rollable display apparatus of claim 12 , wherein the flexible display panel further comprises a first adhesion layer between the first surface and the first protection film and a second adhesion layer between the second surface and the second protection film.

21. The rollable display apparatus of claim 1 , wherein a plurality of metal particles are dispersed in the first layer.

22. The rollable display apparatus of claim 1 , further comprising a conductive layer between the first protection film and the first surface.

23. The rollable display apparatus of claim 1 , wherein the flexible display panel further comprises an encapsulation member located between the flexible substrate and the first protection film and encapsulating the display device.

24. The rollable display apparatus of claim 1 , wherein the display device comprises an organic light-emitting device.