US Patent 7703969 Backlight unit having multilayer light deflecting film

A backlight unit includes a light guide plate having opposite side surfaces and a peripheral edge surface. A part of the peripheral edge surface is a light entrance surface, and one of the opposite side surfaces is a light exit surface. A light source is disposed adjacent to the light entrance surface of the light guide plate. A light deflecting film is disposed adjacent and parallel to the light exit surface of the light guide plate. The light deflecting film has a multilayer construction wherein light reflecting layers and light transmitting layers are stacked one by one alternately. The light reflecting and transmitting layers are tilted at a predetermined angle to the light exit surface.