LED backlight system with double-prism pattern

A LED backlight system with a double-prism pattern for use in mobile phones to achieve thin and high luminance LED backlight systems is proposed. The double-prism pattern is formed on the light guide of the proposed LED backlight system and simultaneously exhibited two optical functions: shifting of the light from the direction of the guided light toward the radiated light and controlling the directivity of the radiated light. Therefore, using the double-prism pattern eliminates two prism sheets and a diffusive sheet, which are indispensable optical elements to exhibit the optical function that controls the directivity of light in conventional LED backlight systems. Consequently, the thickness of the proposed LED backlight system is reduced to 0.75 mm compared to that of the conventional system. A luminance of 3115 nits and a full-width half maximum of 35 degrees for radiated light, which are comparable to conventional LED backlight systems, were obtained.