Patent ID: 8573825

Claim:
A backlight module, comprising: a first light guide plate including a first lower structure layer formed on a surface of the first light guide plate, wherein the first lower structure layer includes: a first primary strip, distributed along a first side of the first light guide plate, having a microstructure aperture ratio less than 60%; and a first secondary strip, distributed along the first primary strip, having a microstructure aperture ratio greater than 60%, wherein the first primary strip is located between the first secondary strip and the first side of the first light guide plate; a first light source set, disposed corresponding to the first side of the first light guide plate, for emitting lights toward the first side; a second light guide plate, stacked to the first light guide plate facing the first lower structure layer, the second light guide plate including a second lower structure layer formed on a surface of the second light guide plate facing away from the first light guide plate, wherein the second lower structure layer includes: a second primary strip, distributed along a second side of the second light guide plate, wherein the second side is parallel with the first side of the first light guide plate, the second primary strip has a microstructure aperture ratio less than 60%; and a second secondary strip, distributed along the second primary strip, having a microstructure aperture ratio greater than 60%, wherein the second primary strip is located between the second secondary strip and the second side of the second light guide plate; and a second light source set, disposed corresponding to the second side of the second light guide plate, for emitting lights toward the second side; wherein the second primary strip is exposed outside a projection of the first lower structure layer on the second lower structure layer, the first lower structure layer at least partially overlaps the second secondary strip.