Patent ID: 8167461

Claim:
A method of manufacturing a sign, said method comprising: separating a plurality of regions in a film with a thickness not greater than 0.5 millimeters to form a plurality of lightguide legs continuous with a body of the film, the legs having internally light reflecting, optically smooth, lateral edges; folding the plurality of legs such that each leg terminates in a stack of bounding edges, wherein each leg is folded at a radius of curvature less than 50 times the thickness of the film, such that portions of each leg on opposing sides of a fold have faces oriented in at least substantially parallel planes, and lengthwise axes extending at a nonzero angle with respect to each other, with the bounding edges stacked in parallel face-to-face relation; disposing the stack of bounding edges proximate at least one light source such that light from the at least one light source propagates through the legs and the body by total internal reflection; treating a surface of the body of the film to form a plurality of light scattering features on the surface such that: the light scattering features frustrate totally internally reflected light from the at least one light source propagating through the legs and the body; the frustrated totally internally reflected light exits the sign at a visible light emitting area; and the light scattering features do not appreciably change an appearance of a window when the sign is disposed adjacent the window and the at least one light source is not emitting light.