Optical stack for directional display
AssigneeRealD Spark, LLC
InventorsMichael G. Robinson, Graham J. Woodgate, Robert A. Ramsey, Jonathan Harrold
Life of this patent
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Abstract
A privacy display comprises a spatial light modulator and a passive retarder arranged between first and second polarisers arranged in series with the spatial light modulator. On-axis light from the spatial light modulator is directed without loss, and off-axis light has reduced luminance. The visibility of the display to off-axis snoopers is reduced by means of luminance reduction over a wide polar field of view. Off-axis visibility of the display in an automotive vehicle can be reduced.
Claims30
A display device comprising:
- a spatial light modulator;
- at least one display polariser arranged on a side of the spatial light modulator;
- an additional polariser arranged on the same side of the spatial light modulator as the display polariser;
- a first pair of passive retarders arranged between the additional polariser and the display polariser, wherein the first pair of passive retarders have slow axes in the plane of the passive retarders that are crossed;
- and
- an additional pair of passive retarders arranged between the first pair of passive retarders, wherein the additional pair of passive retarders have slow axes in the plane of the passive retarders that are crossed, there being no other retarders arranged between the additional polariser and the display polariser,
- wherein the retardance for light of a wavelength of 550 nm of each passive retarder is in a range from 600 nm to 850 nm.
A view angle control optical element for application to a display device comprising a spatial light modulator and a display polariser, the view angle control optical element comprising:
- a control polariser;
- a first pair of passive retarders for arrangement between the control polariser and the display polariser on application of the view angle control optical element to the display device, wherein the first pair of passive retarders have slow axes in the plane of the passive retarders that are crossed;
- and
- an additional pair of passive retarders arranged between the first pair of passive retarders, wherein the additional pair of passive retarders have slow axes in the plane of the passive retarders that are crossed, the view angle control element having no other retarders,
- wherein the retardance for light of a wavelength of 550 nm of each passive retarder is in a range from 600 nm to 850 nm.
Dependencies are inferred from the claim text.