US Patent 9004726 Light directing films

Light directing films employing at least two layers forming a continuous corrugated boundary between major surfaces of the film. Light received by a major surface of the film is internally redirected by interacting with the facets of the corrugated inter-layer boundary and is emitted from the opposing major surface towards a new propagation direction which is different from the original propagation direction by up to 90 degrees. Light directing films may have additional layers and/or layer boundaries which may provide additional bend angles to light rays or otherwise diffuse the emitted beam.