Direct type backlight module and display device

A display device comprising a display screen and a direct type backlight module;

• wherein the direct type backlight module comprises:
• a back board, a plurality of point light sources distributed in array and located on the back board, and a diffusion plate located over the plurality of point light sources;
• wherein a plurality of ring shaped inverted prism structures distributed in array are arranged between the diffusion plate and the plurality of point light sources;
• each ring shaped inverted prism structure is opposite to one of the plurality of point light sources;
• an apex angle of a prism in the ring shaped inverted prism structures faces the back board;
• a line connecting a center point of each ring shaped inverted prism structure and a point light source opposite to the ring shaped inverted prism structure is perpendicular to a plane in which the plurality of point light sources are located;
• and wherein angles between three surfaces of each prism on a ring shaped inverted prism structure are arranged so that light emitted from a point light source directly enters the prism at a surface of the prism facing the point light source at a first angle with respect to a vertical axis and exits the ring shaped inverted prism structure at a second angle with respect to the vertical axis, where the second angle is greater than the first angle.