Privacy display apparatus
AssigneeRealD Spark, LLC
InventorsMichael G. Robinson, Graham J. Woodgate, Jonathan Harrold, Robert A Ramsey, Ben Ihas
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Abstract
A privacy display comprises a liquid crystal spatial light modulator, a switchable retarder and a passive compensation retarder arranged between a pair of polarisers. In a privacy mode of operation, on-axis light from the spatial light modulator is directed without change of image contrast, whereas off-axis light has reduced contrast to reduce the visibility of the display to off-axis snoopers over a wide polar angular range. In a wide angle mode of operation, the retardance of the switchable retarder is adjusted so that off-axis contrast is substantially unmodified.
Claims20
A display device comprising:
- a spatial light modulator comprising a layer of liquid crystal material arranged to output light on an output side;
- an input polariser arranged on an input side of the spatial light modulator;
- an output polariser arranged on the output side of the spatial light modulator;
- and
- plural retarders arranged between the input polariser and the output polariser on either the input side or the output side of spatial light modulator,
- wherein
- the plural retarders include at least one switchable liquid crystal retarder comprising a layer of liquid crystal material and electrodes arranged to apply a voltage for switching the layer of liquid crystal material, and at least one passive retarder, and
- the plural retarders are arranged to introduce no phase shift to polarisation components of light passed by the input polariser along an axis along a normal to the plane of the retarder and are arranged to introduce a phase shift to polarisation components of light passed by the input polariser along an axis inclined to the axis along a normal to the plane of the retarder in a switchable mode of the at least one switchable liquid crystal retarder.
Dependencies are inferred from the claim text.