a backplane comprising a bottom wall and a side wall; wherein the bottom wall and the side wall are connected to each other to define an accommodating portion of the backplane;

a light guide plate in the accommodating portion;

an optical film on a side of the light guide plate away from the bottom wall; and

a plastic frame comprising a retaining wall and a bearing portion; wherein the retaining wall is arranged side by side with the side wall and on a side of the side wall away from the light guide plate; the bearing portion is connected to the retaining wall and is on a side of the side wall and the optical film away from the bottom wall; wherein

the bearing portion comprises a first surface away from the side wall and opposite to the retaining wall; at least a portion of the first surface protrudes towards a side close to the retaining wall;

wherein the at least a portion of the first surface comprises a first sub-surface and a second sub-surface opposite to the retaining wall, and a first connection sub-surface connecting the first sub-surface and the second sub-surface together;

the first sub-surface and the second sub-surface are sequentially arranged in a direction away from the optical film, and a farthest distance between the first sub-surface and the retaining wall is different from a farthest distance between the second sub-surface and the retaining wall; and

the first sub-surface and the second sub-surface are substantially parallel to a plane where the retaining wall is located; and the first connection sub-surface is substantially parallel to a plane where the optical film is located.