Brightness enhancement film and backlight module

A backlight module, comprising:

• at least one light source;
• a light guide plate having at least a ray entering side and a ray displaying side, said ray entering side being adapted to receive ray from said light source and said ray displaying side being adapted to guide the ray outward;
• and
• a brightness enhancement film disposed on said ray displaying side of said light guide plate, said brightness enhancement film comprising:
• a pair of first sides corresponding to each other, a pair of second sides corresponding to each other, and a plurality of first micro-reflectors and second micro-reflectors disposed side by side, said first micro-reflectors having a first average height and a first average width, said second micro-reflectors having a second average height and a second average width, said first average height and said first average width being different from said second average height and said second average width,
• each of said first micro-reflectors and said second micro-reflectors having a triangular cross-section viewed from the first side, said triangular cross-section having an apex and a base, said apex of said triangular cross-section defining a crest line extending longitudinally from the first side,
• neighboring lines being disposed between crest lines to delineate adjacent ones of said first micro-reflectors and said second micro-reflectors, said crest lines of said first and second micro-reflectors each defining a straight horizontal profile and a wavy vertical profile having continuous valleys and peaks, said first micro-reflectors being longitudinally offset in vertical profile from said second micro-reflectors, the widths of said first micro-reflectors and said second micro-reflectors varying along with said valleys and said peaks, said neighboring lines between said first micro-reflectors and said second micro-reflectors being wavy.