Back film and display device

1. A back film for a curved display panel, wherein the back film comprises: a central area, having a first edge and a second edge adjacent to the first edge, wherein the first edge extends in a first direction, the second edge extends in a second direction, and the first direction intersects with the second direction; a first foldable area, connected to the first edge of the central area and extending in the first direction; a second foldable area, connected to the second edge of the central area and extending in the second direction; and a third foldable area, connected to a junction between the first edge and the second edge of the central area, and connected further to the first foldable area and the second foldable area, wherein the third foldable area is provided with a plurality of openings, and wherein the first foldable area and the second foldable area are each provided with a plurality of openings, wherein the first edge and the second edge are perpendicular to each other, the first foldable area and the second foldable area are both rectangular in shape, an extension length of the first foldable area in the first direction is equal to a length of the first edge of the central area, and an extension length of the second foldable area in the second direction is equal to a length of the second edge of the central area; and the third foldable area comprises a first straight edge connected to the first foldable area, a second straight edge connected to the second foldable area, and an arc-shaped edge connected to the first straight edge and the second straight edge, wherein a length of the first straight edge is equal to a width of the first foldable area in the second direction, and a length of the second straight edge is equal to a width of the second foldable area in the first direction, wherein lengths of the first straight edge and the second straight edge are equal, and the third foldable area is in a fan shape, and wherein each opening of the third foldable area is arc-shaped, and an extension direction of each arc-shaped opening is the same as an extension direction of the arc-shaped edge of the third foldable area; a first end of each arc-shaped opening extends to the first straight edge, and a second end of each arc-shaped opening extends to the second straight edge; and the arc-shaped openings are arranged at intervals in a direction from a corner of the central area towards the arc-shaped edge.

2. The back film according to claim 1 , wherein a width of each arc-shaped opening is 80-120 μm, and a distance between two adjacent arc-shaped openings is 150-250 μm.

3. The back film according to claim 1 , wherein a spacing between adjacent openings of the third foldable area gradually decreases in a direction towards the central area.

4. The back film according to claim 1 , wherein the central area is rectangular in shape, a number of the third foldable areas is four, and the third foldable areas are respectively located at four corners of the central area.

5. The back film according to claim 1 , wherein each opening of the first foldable area and the second foldable area is in a circle or strip shape.

6. The back film according to claim 1 , wherein

shape and distribution of the openings in the first foldable area are the same as or different from shape and distribution of the openings in the second foldable area; and

shapes and distributions of the openings in the first foldable area and of the openings in the second foldable area are the same as or different from shape and distribution of the openings in the third foldable area.

7. The back film according to claim 1 , wherein each opening of the third foldable area is a through hole penetrating through the back film or a blind hole not penetrating through the back film.

8. The back film according to claim 1 , wherein the back film is a single-layer film or a multi-layer film.

9. A display device, comprising:

a curved display panel, having a central area, a first curved area and a second curved area respectively located at two adjacent sides of the central area, and a transition area located at a corner of the central area and connected to the first curved area and the second curved area; and

a back film, disposed on a back side of the curved display panel, wherein the back film comprises:

a central area, having a first edge and a second edge adjacent to the first edge, wherein the first edge extends in a first direction, the second edge extends in a second direction, and the first direction intersects with the second direction;

a first foldable area, connected to the first edge of the central area and extending in the first direction;

a second foldable area, connected to the second edge of the central area and extending in the second direction; and

a third foldable area, connected to a junction between the first edge and the second edge of the central area, and connected further to the first foldable area and the second foldable area, the third foldable area comprises a first straight edge connected to the first foldable area, a second straight edge connected to the second foldable area, and an arc-shaped edge connected to the first straight edge and the second straight edge,

wherein a length of the first straight edge is equal to a width of the first foldable area in the second direction, and a length of the second straight edge is equal to a width of the second foldable area in the first direction,

wherein lengths of the first straight edge and the second straight edge are equal, and the third foldable area is in a fan shape,

wherein the central area of the back film covers the central area of the curved display panel, the first foldable area of the back film covers the first curved area of the curved display panel, the second foldable area of the back film covers the second curved area of the curved display panel, and the third foldable area of the back film covers the transition area of the curved display panel,

wherein the third foldable area is provided with a plurality of openings, and

wherein the first foldable area and the second foldable area are each provided with a plurality of openings, and

wherein each opening of the third foldable area is arc-shaped, and an extension direction of each arc-shaped opening is the same as an extension direction of the arc-shaped edge of the third foldable area;

a first end of each arc-shaped opening extends to the first straight edge, and a second end of each arc-shaped opening extends to the second straight edge; and the arc-shaped openings are arranged at intervals in a direction from a corner of the central area towards the arc-shaped edge.

10. The display device according to claim 9 , wherein

the central area of the curved display panel is rectangular in shape, a number of the transition areas is four, and the transition areas are respectively located at four corners of the central area of the curved display panel;

the central area of the back film is rectangular in shape, a number of the third foldable areas is four, and the third foldable areas are respectively located at four corners of the central area of the back film; and

each of the third foldable areas of the back film covers a respective transition area of the transition areas of the curved display panel.