Marks for angular optical filters
AssigneeRealD Spark, LLC
InventorsJonathan Harrold, Graham J. Woodgate, Michael G. Robinson, Robert Ramsey, Ben Ihas
Life of this patent
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Abstract
A privacy display comprises a spatial light modulator and a view angle control element that may comprise a first polariser that may be a reflective polariser, a liquid crystal retarder, a compensation retarder and an additional polariser. The layer of liquid crystal material is patterned with a mark. The display provides visibility of the mark in reflected light to an off-axis snooper but no visibility of the image on the spatial light modulator; and provides high visibility of an image with no visibility of the mark to an on-axis display user.
Claims20
A view angle control element for arrangement outside a first polariser that is a linear polariser, the view angle control element comprising:
- an additional polariser, the additional polariser being a linear polariser;
- and
- at least one polar control retarder for arrangement between the first polariser and the additional polariser, the at least one polar control retarder including a passive liquid crystal retarder comprising a layer of liquid crystal material, wherein the layer of liquid crystal material has at least one region in a shape of a mark for display to an observer arranged such that:
- along a predetermined viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are sufficiently small in the at least one region and the remainder of the layer of liquid crystal material that the mark is not visible;
- and
- along a non-viewing axis at a different angle from the viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are different in the at least one region and the remainder of the layer of liquid crystal material such that the mark is visible.
Dependencies are inferred from the claim text.