Light emitting device comprising a lightguide film and aligned coupling lightguides

Abstract

A light emitting device includes a film-based lightguide and coupling lightguides having ends stacked and aligned. In one embodiment, the light emitting device comprises a relative position maintaining element that extends beyond the light input surface defined by the stacked ends of an array of coupling lightguides. In another embodiment, a light emitting device comprises an alignment guide or cavity.

What is claimed is: 
     
         1 . A light emitting device comprising:
 a light source having an optical axis;   a relative position maintaining element; and   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 of the array of coupling lightguides terminates in an edge and at least one of the array of coupling lightguides is folded at least partially around the relative position maintaining element such that the edges of the array of coupling lightguides form a stack defining a light input surface,   wherein light from the light source enters into the light input surface and propagates by total internal reflection within each coupling lightguide to the lightguide region and the relative position maintaining element extends past the light input surface in a direction parallel to the optical axis.   
     
     
         2 . The light emitting device of  claim 1  wherein the relative position maintaining element extends past the light source in a direction parallel to the optical axis. 
     
     
         3 . The light emitting device of  claim 1  wherein the relative position maintaining element comprises an array of guide members and the at least one of the array coupling lightguide is folded at least partially around a guide member. 
     
     
         4 . The light emitting device of  claim 1  further comprising a light redirecting optical element positioned to direct the light from the light source to the light input surface. 
     
     
         5 . The light emitting device of  claim 4  wherein at least one of the light source and the light redirecting optical element is coupled to the relative position maintaining element. 
     
     
         6 . A display comprising the light emitting device of  claim 1  and a spatial light modulator wherein the light emitting device illuminates the spatial light modulator. 
     
     
         7 . A light emitting device comprising:
 a light source;   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 of the array of coupling lightguides terminates in an edge and at least one of the array of coupling lightguides is folded such that the edges of the array of coupling lightguides form a stack defining a light input surface; and   a light redirecting optical element positioned to direct light from the light source to the light input surface such that the light propagates by total internal reflection within each coupling lightguide to the lightguide region,   wherein the light redirecting optical element comprises an alignment guide configured to align the light redirecting optical element to the light input surface.   
     
     
         8 . The light emitting device of  claim 7  wherein the alignment guide aligns the light redirecting optical element to the light input surface in a direction of the stack. 
     
     
         9 . The light emitting device of  claim 7  wherein the alignment guide constrains the edges of the coupling lightguides in a direction of the stack. 
     
     
         10 . The light emitting device of  claim 7  wherein the light redirecting optical element is a secondary optic for the light source. 
     
     
         11 . The light emitting device of  claim 10  wherein the light redirecting optical element collimates the light from the light source such that the light incident on the light input surface has an angular full-width at half maximum intensity less than 60 degrees in a plane orthogonal to the light input surface. 
     
     
         12 . The light emitting device of  claim 7  further comprising a relative position maintaining element comprising an array of guide members and the at least one of the array of coupling lightguide is folded at least partially around the array of guide members. 
     
     
         13 . A display comprising the light emitting device of  claim 7  and a spatial light modulator wherein the light emitting device illuminates the spatial light modulator. 
     
     
         14 . A light emitting device comprising:
 a light source;   a lightguide formed from 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 of the array of coupling lightguides terminates in an edge and at least one of the array of coupling lightguides is folded such that the edges of the array of coupling lightguides form a stack defining a light input surface; and   an alignment guide defining a cavity,   wherein the light input surface is positioned within the cavity and light from the light source propagates into the light input surface such that that the light propagates by total internal reflection within each coupling lightguide to the lightguide region.   
     
     
         15 . The light emitting device of  claim 14  wherein the alignment guide redirects light from the light source such that the redirected light is more collimated in a first plane orthogonal to an optical axis of the light from the light source. 
     
     
         16 . The light emitting device of  claim 15  wherein the first plane is parallel to direction of the stack. 
     
     
         17 . The light emitting device of  claim 14  wherein the light incident on the light input surface has an angular full-width at half maximum intensity less than 60 degrees in a plane orthogonal to the light input surface. 
     
     
         18 . A display comprising the light emitting device of  claim 14  and a spatial light modulator wherein the light emitting device illuminates the spatial light modulator. 
     
     
         19 . A method of manufacturing a light emitting device, said method comprising:
 separating a plurality of regions in a film with a thickness less than 0.5 millimeters to form a plurality of coupling lightguides continuous with a lightguide region of the film;   folding at least one coupling lightguide of the plurality of coupling lightguides such that ends of the plurality of coupling lightguides form a stack defining a light input surface; and   positioning a light redirecting optical element to receive light from a light source and transmit the light to the light input surface such that the light propagates within each coupling lightguide to the lightguide region,   wherein the light redirecting optical element comprises one of an alignment guide and a cavity defined within the light redirecting optical element configured to align the light input surface with the light redirecting optical element.   
     
     
         20 . The method of  claim 19  wherein positioning a light redirecting optical element comprises positioning the light input surface within the cavity.