Light guide assembly, light collimation assembly, backlight module and display device

A light guide assembly, comprising:

• a first prism sheet, a dielectric layer and a second prism sheet which are sequentially laminated along a first direction,
• wherein a light refractive index of the dielectric layer is smaller than a light refractive index of the first prism sheet and a light refractive index of the second prism sheet;
• the first prism sheet includes a light incident side surface, and a first plane and a first prism surface which are opposite to each other, the first plane is closer to the dielectric layer with respect to the first prism surface, and the first prism surface includes a plurality of first prism portions extending along a second direction;
• the second prism sheet includes a second plane and a second prism surface which are opposite to each other, the second plane is closer to the dielectric layer with respect to the second prism surface, the second prism surface includes a plurality of second prism portions extending along the second direction, and the second prism portion has a reflection surface;
• the first prism sheet is configured to receive light being incident to the light incident side surface, totally reflect light with an included angle not smaller than a first angle with a surface of the dielectric layer by the first prism portion, and reduce an included angle between the light being totally reflected and the first direction;
• the second prism sheet is configured to enable light incident to the second prism portion through the second plane to be reflected towards the first direction by the reflection surface of the second prism portion and emerge from the first prism surface;
• wherein the second direction is parallel to the light incident side surface, and the first angle is a total reflection critical angle between the first prism sheet and the dielectric layer;
• the plurality of second prism portions are continuously disposed on the second prism surface;
• a main cross-section of the second prism portion is of a triangle shape;
• the second prism portion includes a third sub prism surface;
• and
• the third sub prism surface is configured as the reflection surface, a vertex of an included angle α3 between a plane where the third sub prism surface is positioned and the second plane is away from the light incident side surface, and the included angle α3 is calculated by a formula below:
• α
• ⁢
• ⁢
• 3
• =
• 1
• 2
• ⁢
• arcsin
• ⁡
• [
• ⁢
• n
• ⁢
• ⁢
• 1
• n
• ⁢
• ⁢
• 3
• ×
• sin
• ⁡
• (
• arcsin
• ⁡
• (
• n
• ⁢
• ⁢
• 2
• n
• ⁢
• ⁢
• 1
• )
• -
• α
• ⁢
• ⁢
• 1
• )
• ]
• where n1 represents a refractive index of the first prism sheet, n2 represents a refractive index of the dielectric layer, n3 represents a refractive index of the second prism sheet, and α1 is an included angle between the first sub prism surface and the first plane.