High contrast projection screen with stray light rejection
View Patent ↗A multi-layer projection screen includes a transparent substrate having first and second sides, a stray light rejection layer, and a lens array. The stray light rejection layer is disposed across the first side of the transparent substrate. The stray light rejection layer includes an array of pillar structures, wherein each pillar structure of the array of pillar structures includes an entrance aperture, an exit aperture, a substantially transparent pathway extending from the entrance aperture to the exit aperture, and an opaque side wall surrounding the transparent pathway. The lens array is disposed across the second side of the transparent substrate and optically aligned to the array of pillar structures. The stray light rejection layer blocks display light received from the lens array having an oblique trajectory that is greater than a threshold angle from a normal of the second side of the transparent substrate.
1. A multi-layer projection screen, comprising:
a substantially transparent substrate having first and second sides;
a stray light rejection layer disposed across the first side of the transparent substrate, the stray light rejection layer including an array of pillar structures, wherein each pillar structure of the array of pillar structures includes:
an entrance aperture;
an exit aperture;
a substantially transparent pathway extending from the entrance aperture to the exit aperture; and
an opaque side wall surrounding the transparent pathway; and
a lens array disposed across the second side of the transparent substrate and optically aligned to the array of pillar structures such that each lens of the lens array focuses first display light having a normal trajectory relative to the second side of the transparent substrate through the entrance and exit apertures of a corresponding pillar structure while second display light having an oblique trajectory that is greater than a threshold angle from the normal trajectory is directed onto the opaque side wall and substantially blocked from reaching the exit aperture,
wherein the opaque side wall and transparent pathway are formed of materials having substantially similar refractive indexes.
2. The multi-layer projection screen of claim 1 , wherein the exit aperture has a smaller cross-sectional area than the entrance aperture.
3. The multi-layer projection screen of claim 2 , wherein each opaque side wall separating adjacent transparent pathways has a T-shaped cross-section.
4. The multi-layer projection screen of claim 2 , wherein the transparent pathway has a truncated cone shaped cross-section.
5. The multi-layer projection screen of claim 2 , wherein the transparent pathway has a cross-sectional shape comprising:
a truncated cone adjacent to the entrance aperture; and
a rectangular nipple adjacent to the exit aperture.
6. The multi-layer projection screen of claim 1 , further comprising:
a diffuser disposed across the exit aperture of each pillar structure and upon which an image plane for the first display light is formed, wherein the diffuser increases a divergence of the first display light.
7. The multi-layer projection screen of claim 6 , wherein the diffuser comprises one of:
a texture applied across an entire emission surface of the stray light rejection layer; or
a texture applied to the transparent pathway at the exit aperture of each pillar structure of the array of pillar structures.
8. The multi-layer projection screen of claim 6 , wherein the diffuser comprises one of:
a diffusive material layer disposed across an entire emission surface of the stray light rejection layer; or
diffusive material disposed within transparent pathway proximate to the exit aperture of each pillar structure of the array of pillar structures.
9. The multi-layer projection screen of claim 1 , wherein the threshold angle is approximately 5 degrees.
10. The multi-layer projection screen of claim 1 , wherein the array of pillar structures further comprises:
a plurality of trenches formed in a material layer that forms the transparent pathway of each pillar structure;
dark ink filled into the plurality of trenches; and
a planarized top surface of the dark ink forming an emission surface of the stray light rejection layer.
11. The multi-layer projection screen of claim 1 , wherein the lens array comprises a two-dimensional array of microlenses.
12. The multi-layer projection screen of claim 1 , wherein the lens array comprises:
a first one dimensional (“1D”) array of cylindrical lenses; and
a second 1D array of cylindrical lenses orthogonally oriented relative to the first 1D array of cylindrical lenses.
13. The multi-layer projection screen of claim 12 , wherein the stray light rejection layer comprises a first stray light rejection layer and wherein the array of pillar structures comprises a first 1D array of pillar structures, the multi-layer projection screen further comprising:
a second stray light rejection layer including a second 1D array of pillar structures orthogonally oriented relative to the first 1D array of pillar structures,
wherein the second stray light rejection layer is interposed between the first and second 1D array of cylindrical lenses,
wherein the first 1D array of cylindrical lenses is aligned to the first 1D array of pillar structures of the first stray light rejection layer and the second 1D array of cylindrical lenses is aligned to the second 1D array of pillar structures of the second stray light rejection layer.
14. The multi-layer projection screen of claim 1 , wherein the array of pillar structures comprises a two-dimensional array of pillar structures.
15. A rear projection display, comprising:
a projection screen including:
a substantially transparent substrate having first and second sides;
a stray light rejection layer disposed across the first side of the transparent substrate, the stray light rejection layer including an array of pillar structures, wherein each pillar structure of the array of pillar structures includes an entrance aperture, an exit aperture, a substantially transparent pathway extending from the entrance aperture to the exit aperture, and an opaque side wall surrounding the transparent pathway; and
a lens array disposed across the second side of the transparent substrate and optically aligned to the array of pillar structures, wherein the stray light rejection layer blocks display light received from the lens array having an oblique trajectory that is greater than a threshold angle from a normal of the second side of the transparent substrate;
a display layer including a transmissive pixel array to project an image onto the projection screen from a backside of the projection screen; and
an illumination layer including an illumination source to illuminate a backside of the transmissive pixel array,
wherein the opaque side wall and transparent pathway are formed of materials having substantially similar refractive indexes.
16. The rear projection display of claim 15 , wherein the exit aperture has a smaller cross-sectional area than the entrance aperture.
17. The rear projection display of claim 16 , wherein each opaque side wall separating adjacent transparent pathways has a T-shaped cross-section.
18. The rear projection display of claim 16 , wherein the transparent pathway has a truncated cone shaped cross-section.
19. The rear projection display of claim 16 , wherein the transparent pathway has a cross-sectional shape comprising:
a truncated cone adjacent to the entrance aperture; and
a rectangular nipple adjacent to the exit aperture.
20. The rear projection display of claim 15 , further comprising:
a diffuser disposed across the exit aperture of each pillar structure and upon which an image plane for the display light is formed, wherein the diffuser increases a divergence of the display light.
21. The rear projection display of claim 20 , wherein the diffuser comprises one of:
a texture applied across an entire emission surface of the stray light rejection layer; or
a texture applied to the transparent pathway at the exit aperture of each pillar structure of the array of pillar structures.
22. The rear projection display of claim 20 , wherein the diffuser comprises one of:
a diffusive material layer disposed across an entire emission surface of the stray light rejection layer; or
diffusive material disposed within transparent pathway proximate to the exit aperture of each pillar structure of the array of pillar structures.
23. The rear projection display of claim 15 , wherein the array of pillar structures further comprises:
a plurality of trenches formed in a material layer that forms the transparent pathway of each pillar structure;
dark ink filled into the plurality of trenches; and
a planarized top surface of the dark ink forming an emission surface of the stray light rejection layer.
24. The rear projection display of claim 15 , further comprising a Fresnel collimator disposed between the display layer and the lens array to reduce a divergence of the display light output from the transmissive pixel array.