Sub-display device and tiled display device

The invention provides a sub-display device and a tiled display device, and relates to the technical field of display. The display device comprises a display panel, a frame, a back plate and a lamp panel. The frame is connected to the edge of the display panel. The back plate comprises a bottom wall and a side wall, the side wall is connected to the edge of the bottom wall, the side wall and the frame are at least partially attached and fixedly connected, and the area, attached to the frame, in the side wall is a connecting area. The lamp panel is fixedly connected to the bottom wall, and the orthographic projection of the lamp panel on the side wall is not overlapped with the connecting area. The arrangement position of the lamp panel can be closer to the edge of the display area, so that the lamp beads on the edge of the lamp panel are closer to the edge of the display area, the brightness of the edge of the display area is improved, and the influence of splicing seams in the splicing display device on the watching experience of a user is reduced.