Display comprising plurality of birefringent protrusions on a waveguide of a backlight
First Claim
1. A backlight comprising:
- a waveguide; and
a structure overlying the waveguide, selected regions of the structure having birefringent properties whereby the interface between the waveguide and the selected regions of the structure is not totally internally reflective for at least one polarization of light propagating within the waveguide,wherein a plurality of birefringent protrusions are disposed on the first face of the waveguide of the backlight, each protrusion having a refractive index that, for light of a first polarization, is not lower than the refractive index of the waveguide whereby the protrusion is not totally internally reflective for light of the first polarization propagating within the waveguide, andwherein each protrusion has a refractive index, for light of a second polarization different from the first polarization, that is lower than the refractive index, for the second polarization, of the waveguide whereby the protrusion is totally internally reflective for light of the second polarization propagating within the waveguide.
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Abstract
A display comprises: a transmissive pixilated spatial light modulator (21); and a backlight (22). The backlight has a light-transmissive waveguide (26), with a first face of the waveguide being opposed to the spatial light modulator (21). The first face of the waveguide comprises a plurality of regions that are not totally internally reflective for at least one polarization of light propagating within the waveguide, and the remainder of the first face of the waveguide is totally internally reflective for light propagating within the waveguide. Light is extracted from the waveguide at the regions where first face of the waveguide is not totally internally reflective. The pitch of the regions where first face of the waveguide is not totally internally reflective is substantially an integer multiple of the pitch of the pixels of the spatial light modulator.
20 Citations
21 Claims
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1. A backlight comprising:
- a waveguide; and
a structure overlying the waveguide, selected regions of the structure having birefringent properties whereby the interface between the waveguide and the selected regions of the structure is not totally internally reflective for at least one polarization of light propagating within the waveguide,wherein a plurality of birefringent protrusions are disposed on the first face of the waveguide of the backlight, each protrusion having a refractive index that, for light of a first polarization, is not lower than the refractive index of the waveguide whereby the protrusion is not totally internally reflective for light of the first polarization propagating within the waveguide, and wherein each protrusion has a refractive index, for light of a second polarization different from the first polarization, that is lower than the refractive index, for the second polarization, of the waveguide whereby the protrusion is totally internally reflective for light of the second polarization propagating within the waveguide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
- a waveguide; and
Specification