Patent ID: 9494726
Filing Date: 2016-11-15
CPC Classification: G02B

Claim Text:
1. A backlight unit comprising: a light guide configured to receive light at a first light interface located at an end of the light guide and output light via a second light interface located at a face of the light guide; a plurality of light sources configured to inject light into the light guide at the first light interface, each light source of the plurality of light sources being configured to selectively emit light having at least one of an intensity profile having a narrower distribution relative to an optical axis of the backlight unit, and an intensity profile having a wider distribution relative to the optical axis; and an angle dependent diffuser layer comprising a first graded index film and a second graded index film, each of the first graded index film and the second graded index film configured to receive light from the second light interface of the light guide, the first graded index film being configured to homogenize received light that is incident on the graded index film from within a first range of acceptance angles corresponding to the intensity profile having a narrow distribution, and not homogenize light incident on the graded index film from outside of the first range of acceptance angles, and direct the received light that is homogenized by the first graded index film toward a first eye box, and the second graded index film being configured to homogenize received light that is incident on the graded index film from within a second range of acceptance angles corresponding to intensity profile having a wide distribution, and not homogenize light incident on the graded index film from outside of the second range of acceptance angles, and direct the light that is homogenized by the second graded index film toward a second eye box.