| 摘要 |
The present invention provides a planar light guide film for a backlight unit having at least one point light source, the light guide film comprising a light input surface for receiving light from the point light source, a light redirecting surface for redirecting light received from the light input surface and a light output surface for outputting at least the light redirected from the light redirecting surface. The light input surface further comprises a composite lens structure having a circular tip segment with a first contact angle, and a first and second elliptical base segments with a second contact angle, the second contact angle being greater than the first contact angle and the second contact angle being equal to each other and wherein the first and second circular tip segments satisfy the following equations respectively: y1=a1+{square root over ((r12−x2))} y2=a2+{square root over ((r22−x2))} and the first and second elliptical base segments satisfy the following equations respectively: y3=d3+b3×{square root over ((1−((x−c3)/a3)2)} y4=d4+b4×{square root over ((1−((x+c4)/a4)2)} and each of the composite lens structures is randomly disposed along the light input surface.
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