Back cover for backlight source, backlight source, and display apparatus

A display apparatus, comprising a display panel, a back cover and a light source;

• wherein the back cover comprises at least one reflection surface facing the display panel;
• the reflection surface comprises a first reflection region and a second reflection region adjoining the first reflection region;
• the first reflection region comprises a plurality of concave arc-shaped regions whose radius of curvature gradually decrease in a direction toward the second reflection region;
• the second reflection region comprises a plurality of concave arc-shaped regions whose radius of curvature gradually increase in a direction away from the first reflection region;
• and
• the concave arc-shaped region having a minimum radius of curvature in the first reflection region is connected with the concave arc-shaped region having a minimum radius of curvature in the second reflection region;
• wherein the display apparatus further comprises an extension portion located between the back cover and the display panel;
• the extension portion extends inward from an edge of the back cover and is parallel to the display panel;
• the extension portion has a first surface facing the display panel, and an opposite second surface facing the back cover;
• the light source is on the second surface and faces the back cover.