Pupillated illumination apparatus
AssigneeRealD Spark, LLC
InventorsMichael G Robinson, Graham J Woodgate, Jonathan Harrold
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Abstract
A switchable backlight for a switchable privacy display apparatus comprises a collimated waveguide, first and second light sources and an optical turning film comprising elongate prismatic elements with facet orientations that pupillate the output of the waveguide in two orthogonal directions for each of first and second light sources. High luminance uniformity is achieved for a head-on user in privacy and public viewing modes and high uniformity of security factor is achieved for off-axis snoopers, with increased speed of privacy switch-on in privacy mode.
Claims61
An illumination apparatus comprising:
- at least one light source arranged to provide input light;
- a waveguide arrangement comprising at least a first waveguide that extends across a plane and comprises:
- first and second opposed light guiding surfaces arranged to guide light along the first waveguide, the second light guiding surface being arranged to guide light by total internal reflection;
- and
- an input end arranged between the first and second light guiding surfaces and extending in a lateral direction between the first and second light guiding surfaces,
- the first waveguide being arranged to receive the input light from the at least one light source through the input end, and being arranged to cause light from the at least one light source to exit from the first waveguide through the second light guiding surface by breaking total internal reflection;
- and
- an optical turning film component comprising:
- an input surface arranged to receive the light exiting from the first waveguide, the input surface extending across the plane;
- and
- an output surface facing the input surface,
- wherein the input surface comprises:
- an array of prismatic elements each comprising a pair of facets defining a ridge therebetween, the ridges extending along an array of lines across the plane in which the input surface extends, wherein the prismatic elements are arranged to deflect the light exiting the first waveguide, the deflection varying in at least one direction across the plane so that the deflected light is directed towards a common optical window in front of the illumination apparatus.
An optical turning film component comprising:
- an input surface for receiving light exiting from a waveguide through a light guiding surface of the waveguide by breaking total internal reflection, the input surface extending across a plane;
- and
- an output surface facing the input surface,
- wherein the input surface comprises:
- an array of prismatic elements each comprising a pair of facets defining a ridge therebetween, the ridges extending along an array of lines across the plane in which the input surface extends, wherein the prismatic elements are arranged to deflect the light exiting the waveguide, the deflection varying in at least one direction across the plane so that the deflected light is directed towards a common optical window in front of the illumination apparatus.
Dependencies are inferred from the claim text.