Flat Panel Lens
First Claim
1. A flat light guide (1) with first and second faces acting as input and output parts (2, 3a) of the Light guide, the first face (2) being small in relation to the total width of the light guide and the light guide having optical properties such that the angle at which a ray is injected into the first face determines the position at which it leaves the second face (3a), or the position at which the ray enters the second face determines the angle at which the ray leaves the first face;
- in which the optical profile of the light guide is polar-symmetric about the first face (2), so that rays travelling along the light guide are always following the local direction of taper.
2 Assignments
0 Petitions
Accused Products
Abstract
A light guide with input and output faces 2, 3a is polar-symmetric about the first face 2 and has optical properties such that the angle at which a ray is injected into the first face determines the position at which it leaves the second face 3a, or, if operated in the reverse direction, the position at which the ray enters the second face determines the angle at which the ray leaves the second face. The light guide includes a tapered transparent sheet 3, light from the first face entering at the thick end of this sheet, and the second face forming one face of the tapered sheet. An input/output slab 4 adjoins the tapered sheet 3 for fan-out of light from the first face 2 to the tapered sheet, and a transition region 8 is located between flat and tapered sheets. The polar symmetry means that light rays always travel in line with the taper direction, which suppresses banding. Preferably the light guide further includes a prism device 20 for folding the light so that the flat and tapered sheets can be folded over each other. A method of making such a prism is also disclosed.
156 Citations
15 Claims
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1. A flat light guide (1) with first and second faces acting as input and output parts (2, 3a) of the Light guide, the first face (2) being small in relation to the total width of the light guide and the light guide having optical properties such that the angle at which a ray is injected into the first face determines the position at which it leaves the second face (3a), or the position at which the ray enters the second face determines the angle at which the ray leaves the first face;
- in which the optical profile of the light guide is polar-symmetric about the first face (2), so that rays travelling along the light guide are always following the local direction of taper.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A prism for folding a tapered light-guide through an angle β
- , which prism has a cross-section equal to a triangle with angles 180°
−
β
, (β
−
α
)/2 and (β
+α
)/2, where α
is the angle of taper of the light-guide, and a high enough refractive index to prevent light returning down the light guide from which it enters the prism. - View Dependent Claims (11, 12, 13)
- , which prism has a cross-section equal to a triangle with angles 180°
- 14. A mould (30) for making a prism, whose cross-section is congruent at all points but the dimension of which cross-section varies along the length of the prism.
Specification
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- Resources
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Current AssigneeMicrosoft Technology Licensing LLC (Microsoft Corporation)
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Original AssigneeCambridge Flat Projection Displays Limited
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InventorsTravis, Adrian R. L.
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Granted Patent
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Time in Patent OfficeDays
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Field of Search
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US Class Current362/617
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CPC Class CodesG02B 27/0994 Fibers, light pipes optical...G02B 6/0011 the light guides being plan...G02B 6/0046 Tapered light guide, e.g. w...G02B 6/0053 Prismatic sheet or layer; B...Y10S 385/901 Illuminating or display app...
