US Patent 7547468 Optical film and lighting device using the optical film

An optical film for use in a side-light type lighting device of a liquid crystal display or the like includes a plurality of tilted column-shaped transparent film cells extending from a light entrance surface to a light exit surface of the optical film. Light-reflecting layers are provided on a part of side surfaces of each film cell. Light from an LED light source enters a light guide plate, exits the top surface of the light guide plate, and enters the film cells. The light is reflected by the light-reflecting layers of the cells to exit therefrom as directed light.