Light guide film for altering direction of incident sunlight in window system of room, has microstructure including surface inclined at angle to reference plane that is perpendicular to film base

摘要

The film (1) has a microstructure (12) on a side (112) of a film base (11), where the microstructure includes a surface (121) inclined at an angle to a reference plane that is perpendicular to the film base. An output angle of an incident light beam (30) passing through the film is defined at 180 degrees if the outgoing light beam is upward directed and is parallel to the film, where total energy of the outgoing light beams with the output angles of 85 to 120 degrees is more than 40 percent of the total energy of the outgoing light beams with output angles of 0 to 180 degrees. An independent claim is also included for a window system comprising a protection plate.