Illumination device comprising a film-based lightguide

A light emitting device comprising:

• a lightguide comprising a film having a thickness not greater than 0.5 millimeters, the lightguide having a lightguide region and an array of coupling lightguides continuous with the lightguide region, wherein each coupling lightguide terminates in a bounding edge and each coupling lightguide is folded such that the bounding edges of the array of coupling lightguides form a stack defining a light input surface;
• a light source configured to emit light into the light input surface, such that the light propagates within each coupling lightguide to the lightguide region, with light from each coupling lightguide combining with light from one or more other coupling lightguides of the array of coupling lightguides and totally internally reflecting within the lightguide region;
• a plurality of light extraction features operatively coupled to the lightguide and configured to frustrate the totally internally reflected light within the lightguide region such that the light exits the lightguide in a light emitting region defined within the lightguide region;
• and
• a low contact area cover comprising a surface having a plurality of surface relief features adjacent a first region of the lightguide with one or more of the plurality of surface relief features contacting the lightguide,
• wherein the low contact area cover is configured to extract out of the lightguide a total of less than 30% of the light propagating within the lightguide.

A method of producing a light emitting device, said method comprising:

• a. forming an array of coupling lightguides extending continuously from a lightguide region of a film, each coupling lightguide of the array of coupling lightguides having a bounding edge at the end thereof;
• b. folding the array of coupling lightguides such that the bounding edges of the array of coupling lightguides form a stack defining a light input surface;
• c. positioning a light source to direct light into the light input surface such that light from the light source propagates within each coupling lightguide and the lightguide region by total internal reflection;
• d. forming one or more light extraction features on or within the film in a light emitting region of the lightguide region;
• and
• e. positioning a low contact area cover comprising a plurality of surface relief features adjacent a first region of the film wherein one or more of the plurality of surface relief features contact the film in an area less than 30% of a surface area of the film in the first region.