| CPC G02F 1/13362 (2013.01) [G02F 1/13338 (2013.01); G02F 1/133504 (2013.01); G02F 1/133553 (2013.01); G02F 1/133615 (2013.01); G02F 2203/11 (2013.01)] | 20 Claims |
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1. A backlight for providing illumination to a liquid crystal panel, the backlight comprising a front reflector disposed on a back reflector and defining a cavity therebetween and substantially uniformly filled with a material, each of the front and back reflectors comprising a plurality of polymeric layers numbering at least 50 in total, each of the polymeric layers having an average thickness of less than about 500 nm, such that for an incident light propagating in an incident plane and a visible wavelength range extending from about 420 nm to about 650 nm and an infrared wavelength range extending from about 900 to about 1500 nm:
the front reflector has:
in the visible wavelength range: a first incident angle of less than about 5 degrees, an average transmittance of less than about 20% for the incident light polarized along a first direction, and an average transmittance of between about 20% and about 85% for the incident light polarized along an orthogonal second direction, and for a second incident angle of greater than about 40 degrees, an average transmittance of less than about 40% for each of the first and second directions lying in the incident plane and for each of a p-polarized and an s-polarized incident lights; and
for at least a first wavelength in the infrared wavelength range: a transmittance of greater than about 40% for each of the first and second incident angles, for each of the p-polarized and an s-polarized incident lights, and for each of the first and second directions lying in the incident plane; and
the back reflector has:
for each of the first and second incident angles, for the incident light polarized along each of the first and second directions, and for each of the first and second directions lying in the incident plane, a transmittance of greater than about 30% for the at least the first wavelength in the infrared wavelength range, and an average transmittance of less than about 20% in the visible wavelength range;
wherein the material has an index of refraction of less than about 1.2 for at least one wavelength in the visible wavelength range.
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