Abstract: A directional illumination apparatus comprises a waveguide with a reflective surface comprising reflective light input facets, reflective light extraction facets and an output transmissive surface. An array of sub-arrays of micro-LEDs is arranged to illuminate the reflective surface in a rearwards direction. The reflective light extraction facets cooperate to provide a uniform output illumination across the output aperture of the waveguide with collimated light that is controllable by control of the sub-arrays of micro-LEDs. A thin and efficient illumination apparatus may be used for switching high dynamic range display backlighting, privacy display or environmental illumination applications.

Abstract: An illumination apparatus comprises a first substrate; an optical structure; an array of light emitting elements disposed between the first substrate and the optical structure and an array of passive optical nanostructures disposed between the first substrate and the optical structure. Each of the passive optical nanostructures are disposed on a respective one of the light emitting elements and each passive optical nanostructure comprises an air gap. Each passive optical nanostructure is disposed between its respective light emitting element and the optical structure, wherein each passive optical nanostructure is configured to receive light emitted by its respective light emitting element, pass the received light, and output the pass light towards the optical structure.

Abstract: An imaging directional backlight apparatus including a waveguide, a light source array, for providing large area directed illumination from localized light sources. The waveguide may include a stepped structure, in which the steps may further include extraction features optically hidden to guided light, propagating in a first forward direction. Returning light propagating in a second backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. The directional backlight may be arranged to switch between at least a first wide angular luminance profile mode and a second narrow angular luminance profile mode. The directional backlight is arranged to illuminate an LCD with a bias electrode arranged to switch liquid crystal directors in black state pixels between a first wide angular contrast profile mode and a second narrow angular contrast profile mode.

Abstract: A control system for a switchable privacy display apparatus comprises an ambient light sensor and a display luminance controller arranged to control the luminance of the display in response to measured illuminance. High image visibility is provided for public mode operation while in privacy mode visual security level above a perceived privacy threshold may be obtained by means of control of image luminance, in response to the output of the ambient light sensor.

Abstract: A directional illumination apparatus comprises a catadioptric micro-optic array comprising a reflective surface comprising light reflecting facets and an output transmissive surface comprising refractive structures. An array of micro-LEDs is arranged between the reflective surface and output transmissive surface and arranged to illuminate the reflective surface. The light reflecting facets and refractive structures cooperate to provide a uniform output illumination across the output aperture of the array with collimated output. A thin and efficient illumination apparatus may be used for switching display backlighting or environmental illumination applications.

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.

Abstract: A control system for a switchable privacy display apparatus comprises sensors arranged to determine device location, operating environment, document type, application type and further comprises a privacy policy for control of privacy images. High image visibility is provided for public mode operation while in privacy mode a high visual security level may be obtained by means of control of image luminance, contrast and white point in response to the privacy policy.

Abstract: A switchable privacy display apparatus comprises a spatial light modulator, a light control film, and a polar control retarder that comprises plural retarders arranged between a display polariser of the spatial light modulator and an additional polariser. The display achieves high image visibility to an off-axis user in a public mode of operation and high image security to an off-axis snooper in privacy mode of operation.

Abstract: A switchable backlight for a switchable privacy display apparatus comprises a collimated backlight arranged to provide two off-axis beams and at least one polar control liquid crystal retarder arranged between parallel polarisers. The alignment layers of the liquid crystal retarder are rotated with respect to the electric vector transmission direction of the polarisers. In use in the centre stack of a vehicle, in one mode of operation high image luminance and high image visibility is provided for the passenger while the image is invisible to the driver. In another mode of operation an image is provided to the driver with low stray light to the passenger for night time operation. In a third mode of operation both passenger and driver can see an image with high luminance and image visibility.

Abstract: A switchable directional display apparatus comprises a spatial light modulator and a backlight comprising a waveguide, two light sources arranged to provide illumination through the edge of the waveguide and a switchable liquid crystal retarder. The light sources and switchable liquid crystal retarder may be controlled to provide a first operating state with a narrow field of view and a second operating state with a wide field of view. Image visibility in wide angle mode of operation may be maximised while visual security level may be maximised in a narrow angle mode of operation, to provide an efficient privacy mode of operation.

Abstract: A switchable privacy display comprises a spatial light modulator, and switchable liquid crystal retarder arranged between crossed quarter-wave plates and polarisers. In a privacy mode of operation, on-axis light from the spatial light modulator is directed without loss, whereas off-axis light has reduced luminance to reduce the visibility of the display to off-axis snoopers. The display may be rotated to achieve privacy operation in landscape and portrait orientations. Further, display reflectivity may be reduced for on-axis reflections of ambient light, while reflectivity may be increased for off-axis light to achieve increased visual security. In a public mode of operation, the liquid crystal retardance is adjusted so that off-axis luminance and reflectivity are unmodified. The display may also be operated to switch between day-time and night-time operation, for example for use in an automotive environment.

Abstract: A privacy display comprises a spatial light modulator and a compensated switchable liquid crystal retarder arranged between first and second polarisers arranged in series with the spatial light modulator. In a privacy mode of operation, on-axis light from the spatial light modulator is directed without loss, whereas 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. In a wide angle mode of operation, the switchable liquid crystal retardance is adjusted so that off-axis luminance is substantially unmodified.

Abstract: A display comprises a polarised output spatial light modulator, switchable liquid crystal retarder, absorbing polariser and touch panel electrodes. The switchable liquid crystal layer is stabilised by a cured reactive mesogen material during application of an applied voltage. Light scatter in privacy mode is reduced and visual security level enhanced. Visibility of disclinations during application of applied pressure, for example from a finger on a touch screen is minimised.

Abstract: An imaging directional backlight apparatus includes a waveguide and a light source array, providing large area directed illumination from localized light sources. The waveguide may include a stepped structure, and the steps may further include extraction features optically hidden to guided light, propagating in a forward direction. Returning light propagating in a backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. Viewing windows are formed through imaging individual light sources and define the relative positions of system elements and ray paths. The imaging directional backlight apparatus further includes a control system for controlling the light output directional distribution in an automotive or vehicle environment in dependence on the output from sensors mounted on the vehicle.

Abstract: A display device comprising a spatial light modulator having a display polariser arranged on one side of the spatial light modulator is provided with an additional polariser arranged on the same side as the display polariser and polar control retarders between the additional polariser and the display polariser. The polar control retarders include a liquid crystal retarder having two surface alignment layers disposed adjacent to a layer of liquid crystal material on opposite sides. The surface alignment layers provide alignment in the adjacent liquid crystal material with an in-plane component, wherein the angle of said in-plane component changes monotonically along a predetermined axis across the display device, providing reduction of luminance in directions that are offset from a viewing axis, increasing uniformity in the reduction of luminance in directions that are offset from a viewing axis.

Abstract: A privacy display comprises a spatial light modulator and a compensated switchable guest-host liquid crystal retarder arranged between first and second polarisers arranged in series with the spatial light modulator. In a privacy mode of operation, on-axis light from the spatial light modulator is directed without loss, whereas 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. In a wide angle mode of operation, the switchable liquid crystal retardance is adjusted so that off-axis luminance is substantially unmodified.

Abstract: A privacy display comprises a luminance-privacy arrangement and a contrast-privacy arrangement. In a privacy mode of operation, ambient light levels are detected and a visual security level is calculated. At and above a visual security level threshold the luminance-privacy arrangement is operable and below the threshold both the luminance-privacy and contrast-privacy arrangements are operable. Image quality for on-axis users is optimised and high levels of visual security are achieved for off-axis snoopers over a wide range of display illuminance conditions.

Abstract: An imaging directional backlight apparatus includes a waveguide and light source array for providing large area directed illumination from localized light sources. The waveguide may include a stepped structure in which steps may include extraction features optically hidden to guided light, propagating in a forward direction. Returning light propagating in a backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. Viewing windows are formed through imaging individual light sources and defines the relative positions of system elements and ray paths. Alignment of the waveguide to mechanical and optical components may be provided by surface relief features of the waveguide arranged in regions adjacent the input surface and intermediate the light emitting regions of the light sources.

Abstract: A directional privacy display may include a waveguide; and an array of light sources and spatial light modulator that operate in a time sequential manner. The waveguide may include light extraction features arranged to direct light from an array of light sources by total internal reflection to an array of viewing windows and a reflector arranged to direct light from the waveguide by transmission through extraction features of the waveguide to the same array of viewing windows. First and second phases may be temporally multiplexed with respective primary and secondary images and primary and secondary angular illumination distributions. An efficient and bright privacy display may be provided with obscured primary image visibility for off-axis observers.

Abstract: A colour micro-LED display apparatus comprises an array of reflective optical elements and an array of micro-LED pixels with a uniform emission colour across the array arranged between the array of reflective optical elements and an output substrate. Light from the micro-LEDs is directed into the reflective optical elements and is incident on scattering regions in the apparatus. Colour converted scattered light is transmitted by the output substrate. A thin and efficient display apparatus may be provided with high spatial and angular colour uniformity and long lifetime.