US Patent 9633803 Keyboard backlight module with improved light guide structure

A keyboard backlight module includes a backlight device including a reflective layer, a light shielding layer and a light guide layer sandwiched between the reflective layer and the light shielding layer and carrying a set of key switches on the top surface thereof, a light source mounted between the reflective layer and the light shielding layer, and high-refractive index scatter points prepared from a mixture containing a colored light-transmissive ink and high-refractive index particles at a predetermined ratio and mounted in the top side and/or bottom side of the light guide layer for refracting light toward the key switches to enhance illumination brightness.