LIGHT GUIDE PLATE AND BACKLIGHT MODULE

A light guide plate includes a light emitting surface, a bottom surface, a light incident surface and many optical units. Each of the optical units includes a first optical microstructure and a second optical microstructure. The second optical microstructure has a first surface and a second surface. A first cross-sectional line obtained by cutting the first surface along a direction perpendicular to the light incident surface and the light emitting surface is an inclined straight line. A first end of a second cross-sectional line obtained by cutting the second surface along the direction perpendicular to the light incident surface and the light emitting surface and a second end of the second cross-sectional line are connected to form a reference straight line. An acute angle included by the reference straight line and a normal line of the light emitting surface is α. The acute angle α satisfies an equation: [ 90  ° + sin - 1  ( sin   ψ n ) ] 2 - 15  ° ≤ α ≤ [ 90  ° + sin - 1  ( sin   ψ n ) ] 2 + 15  °