Backlight unit with reflection structure formed on light guide plate and display device thereof

A backlight unit, comprising:

• a light guide plate, a light source member, a reflection film, wherein:
• the light guide plate (LGP) comprises a light incident side, a light emission side and a bottom side opposite to the light emission side, the light guide plate is for emitting light entered from the light incident side through the light emission side;
• the light source member is disposed on the light incident side of the LGP and light emitted by the light source member enters the LGP through the light incident side of the LGP;
• the reflection film is at least disposed on the bottom side of the LGP and is for reflecting light back into the LGP;
• wherein a reflection structure is disposed on the bottom side of the LGP and a microstructure is disposed on the light emission side of the LGP,
• wherein the LGP comprises a first refraction layer close to the light emission side of the LGP and second refraction layer close to the bottom side of the LGP, the microstructure is disposed on a side of the first refraction layer close to the light emission, and a refraction index of the second refraction layer is smaller than that of the first refraction layer.