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 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 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 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 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 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: 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 switchable directional illumination apparatus comprises first and second arrays of LEDs, some of which are micro-LEDs; an aligned catadioptric micro-optic array and an aligned light guide array. In a first mode a narrow angular output is provided by a first micro-LED array and catadioptric micro-optics. In a second mode a wider angular output is provided by the second LED array and light guides. A thin and efficient illumination apparatus may be used for switching illumination in environmental lighting, display backlighting or direct display.

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. In operation, luminance streaks and bright illumination regions may be formed due to undesirable imaging characteristics from the structure of the Fresnel mirror. Fresnel mirror draft facets and reflective facet microstructures are provided that achieve reduction of visibility of light streaks and bright illumination regions.

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.

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. Retarder stack arrangements are provided to reduce the display visibility to snoopers located in polar viewing regions of the display while achieving minimal reduction of head-on luminance. Further visibility of light reflections from automotive windscreens may be reduced.

Abstract: A control system for a switchable privacy display apparatus comprises an ambient light sensor, a controllable light source and a display controller arranged to control the light source and the display luminance. 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 and display illuminance, in response to the output of the ambient light sensor.

Abstract: Reflections from a display device are controlled using retarders arranged on the output side of a display panel which outputs light with a predetermined polarization state. First and second planes of incidence are defined in respect of first and second rays of light output from the device and first and second normals to first and second surfaces of optically transmissive material at first and second points at which the first and second rays of light are reflected. The retarders are selected to cause the polarization state of the first ray to be linearly polarized in a direction that is in the first plane of incidence, and to cause the polarization state of the second ray to be linearly polarized in a direction that is in the second plane of incidence. The reflections from the surfaces are minimized because for both surfaces the polarization direction is in-plane.

Abstract: Disclosed is an imaging directional backlight including an array of light sources, and a control system arranged to provide variable distribution of luminous fluxes, scaled inversely by the width associated with the respective light sources in the lateral direction, across the array of light sources. The luminous intensity distribution of output optical windows may be controlled to provide desirable luminance distributions in the window plane of an autostereoscopic display, a directional display operating in wide angle 2D mode, privacy mode and low power consumption mode. Image quality may be improved and power consumption reduced.

Abstract: A directional display apparatus including a directional display device that is capable of directing a displayed image into a viewing window of variable width is provided with a privacy control function. A control system detects the presence of one or more secondary viewers in addition to a primary viewer, and decides whether the one or more secondary viewers is permitted to view the displayed image. The control system directs a displayed image into a viewing window which is adjusted, for example by decreasing the width, in dependence on that detection. In addition, the control system detects relative movement between the primary viewer and the display device, and the width of the viewing window is increased in response to detection of said relative movement.

Abstract: A privacy display comprises a polarised output spatial light modulator, reflective polariser, plural polar control retarders and a polariser. A birefringent surface relief diffuser structure is arranged to transmit light from the display with high transparency and provide diffuse reflection of ambient light to head-on display users. In a privacy mode of operation, on-axis light from the spatial light modulator is directed without loss and with low diffusion, whereas off-axis light has reduced luminance and increased diffusion. Further, overall display reflectivity is reduced for on-axis reflections of ambient light, while reflectivity is increased for off-axis light. The visibility of the display to off-axis snoopers is reduced by means of luminance reduction, increased frontal reflectivity and diffusion of ambient light. In a public mode of operation, the liquid crystal retardance is adjusted so that off-axis luminance and reflectivity are unmodified.