# US 9,436,015 B2 · Superlens component for directional display > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,436,015 B2 - Document ID: US9436015B2 - Status: Granted - Kind: B2 - Application number: 14/137,569 - Filed: 2013-12-20 - Published: 2014-06-26 - Granted: 2016-09-06 - Earliest claimed: 2012-12-21 - Assignees: RealD Inc. - Applicants: RealD Inc. - Inventors: Graham J. Woodgate; Jonathan Harrold; Michael G. Robinson - Web page: https://patentgrep.com/patent/US9436015B2 ## CPC - G02B 30/27: involving lenticular arrays - G02B 6/002: {by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces} - G02B 6/0048: {with stepwise taper} - G02B 30/33: involving directional light or back-light sources - H04N 13/305: using lenticular lenses, e.g. arrangements of cylindrical lenses - H04N 13/32: using arrays of controllable light sources; using moving apertures or moving light sources - H04N 13/356: having separate monoscopic and stereoscopic modes - H04N 13/366: using viewer tracking - H04N 13/398: Synchronisation thereof; Control thereof - G02B 6/0038: {Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide} - G02B 6/0053: {Prismatic sheet or layer; Brightness enhancement element, sheet or layer} - G02B 6/0068: {Arrangements of plural sources, e.g. multi-colour light sources} - H04N 2013/403: {the images being monoscopic} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Disclosed is an imaging directional backlight apparatus comprising a waveguide, a light source array, and a further optical element for providing large area directed illumination from localized light sources. The imaging directional backlight may comprise a stepped waveguide that 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. Viewing windows are formed through imaging individual light sources. The further optical element may comprise a superlens comprising first and second aligned lens arrays that may be arranged to modify the output viewing windows to achieve enhanced window imaging from the directional backlight. ## Claims ### Claim 1 A display device, comprising: a transmissive spatial light modulator comprising an array of pixels arranged to modulate light passing therethrough; a waveguide having an input end, and first and second opposed guide surfaces for guiding light along the waveguide, the first and second opposed guide surfaces extending from the input end across the spatial light modulator, wherein the waveguide is arranged to output light through the first guide surface for supply through the spatial light modulator, the waveguide being arranged to direct input light from different input positions across the input end in output directions relative to the normal to the first guide surface that are dependent on said input position; and an optical element disposed between the waveguide and the spatial light modulator, comprising first and second arrays of lenses, the lenses each having a positive optical power in respective first meridians and no optical power in respective second meridians perpendicular to the first meridians, the first and second arrays of lenses being arranged with respective focal planes that extend perpendicular to the normal to the spatial light modulator between the first and second arrays of lenses, the lenses of each array having parallel second meridians. ### Claim 2 (depends on 1) A display device according to claim 1, wherein the first and second arrays of lenses are arranged with respective focal planes that are coincident. ### Claim 3 (depends on 1) A display device according to claim 1, wherein the first and second arrays of lenses are arranged with respective focal planes that are offset. ### Claim 4 (depends on 1) A display device according to claim 1, wherein the focal length of the lenses of the first array of lenses arranged to receive light from the waveguide is greater than the focal length of the lenses of the second array. ### Claim 5 (depends on 1) A display device according to claim 1, wherein the first and second arrays of lenses have the same pitch. ### Claim 6 (depends on 5) A display device according to claim 5, wherein the first and second arrays of lenses have optical axes that are aligned. ### Claim 7 (depends on 5) A display device according to claim 5, wherein the first and second arrays of lenses have optical axes that are offset. ### Claim 8 (depends on 1) A display device according to claim 1, wherein the first and second arrays of lenses have different pitches. ### Claim 9 (depends on 1) A display device according to claim 1, further comprising a third array of lenses, the lenses each having a positive optical power in respective first meridians and no optical power in respective second meridians perpendicular to the first meridians, the third array of lenses having the same pitch as the first and second arrays of lenses and being disposed between the first and second arrays of lenses, and arranged to image the apertures of the first array of lenses onto the apertures of the second array of lenses. ### Claim 10 (depends on 1) A display device according to claim 1, wherein the optical element is switchable between a first state in which the lenses of the first and second arrays have said positive optical power in said first meridians and a second state in which the lenses of the first and second arrays have no optical power in said first meridians. ### Claim 11 (depends on 10) A display device according to claim 10, wherein the array of pixels are arranged in an aperture with a shape having two perpendicular axes of mirror symmetry, and the display device is arranged so that, in the first state of the optical element, the viewing windows are distributed across the one of said axes of mirror symmetry, and, in the second state of the optical element, the optical element is arranged to rotate the viewing windows around the normal to the spatial light modulator so that the viewing windows are distributed across the other one of said axes of mirror symmetry. ### Claim 12 (depends on 1) A display device according to claim 1, wherein the lenses of each array have second meridians that extend parallel to the optical axis of the waveguide. ### Claim 13 (depends on 1) A display device according to claim 1, wherein the lenses of each array having parallel second meridians that extend at a non-zero-acute angle to the optical axis of the waveguide. ### Claim 14 (depends on 13) A display device according to claim 13, wherein the array of pixels are arranged in an aperture with a shape having two perpendicular axes of mirror symmetry, and the optical element is arranged to rotate the viewing windows around the normal to the spatial light modulator; and the output viewing, windows extend at an angle in a range from 65 to 115 degrees, 80 to 100 degrees or 90 degrees relative to one of said axes of the shape of the aperture. ### Claim 15 (depends on 1) A display device according to claim 1, wherein the first and second arrays of lenses are formed by a common piece of material within which the respective focal planes are disposed. ### Claim 16 (depends on 1) A display device according to claim 1, wherein the first guide surface is arranged to guide light by total internal reflection and the second guide surface has a plurality of light extraction features inclined to reflect light guided through the waveguide in directions allowing exit through the first guide surface of the output light. ### Claim 17 (depends on 16) A display device according to claim 16, wherein the second guide surface has intermediate regions between the light extraction features that are arranged to direct light through the waveguide without extracting it. ### Claim 18 (depends on 17) A display device according to claim 17, wherein the intermediate regions of the second guide surface extend parallel to the first guide surface. ### Claim 19 (depends on 17) A display device according to claim 17, wherein the light extraction features are reflective facets extending laterally to the intermediate regions and the second guide surface has a stepped shape with reflective facets and the intermediate regions. ### Claim 20 (depends on 16) A display device according to claim 16, wherein the extraction features of the waveguide are curved along the direction in which they are elongated. ### Claim 21 (depends on 1) A display device according to claim 1, wherein the first guide surface is arranged to guide light by total internal reflection and the second guide surface is substantially planar and inclined at an angle to reflect light in directions that break the total internal reflection for outputting light through the first guide surface, the display device further comprising a deflection element extending across the first guide surface of the waveguide for deflecting light towards the normal to the spatial light modulator. ### Claim 22 (depends on 1) A display device according to claim 1, wherein the waveguide has a reflective end facing the input end for reflecting light input through the input end back through the waveguide, the waveguide being arranged to output light through the first guide surface after reflection from the reflective end. ### Claim 23 (depends on 1) A display device according to claim 1, further comprising: an array of light sources at different input positions across the input end of the waveguide; and a control system arranged to selectively operate the light sources to direct light into viewing windows corresponding to said output directions. ### Claim 24 (depends on 1) A display device according to claim 1, wherein the first and second arrays of lenses are curved along the direction in which they are elongated. ### Claim 25 A display apparatus, comprising: a transmissive spatial light modulator comprising an array of pixels arranged to modulate light passing therethrough; a waveguide having an input end, and first and second opposed guide surfaces for guiding, light along the waveguide, the first and second opposed guide surfaces extending from the input end across the spatial light modulator, wherein the waveguide is arranged to output light through the first guide surface for supply through the spatial light modulator, the waveguide being arranged to direct input light from different input positions across the input end in output directions relative to the normal to the first guide surface that are dependent on said input position; an optical element disposed between the waveguide and the spatial light modulator, comprising, first and second arrays of lenses, the lenses each having a positive optical power in respective first meridians and no optical power in respective second meridians perpendicular to the first meridians, the first and second arrays of lenses being arranged with respective focal planes that extend perpendicular to the normal to the spatial light modulator between the first and second arrays of lenses, the lenses of each array having parallel second meridians; an array of light sources at different input positions across the input end of the waveguide; and a control system arranged to selectively operate the light sources to direct light into viewing windows corresponding to said output directions; wherein the control system is arranged to control the light sources so that, when light is directed from a given light source into a given viewing window, in the event that the light from the given light source is directed into a viewing window other than the given viewing window by splitting through different lenses of the second array, a further, separated light source is operated to direct compensatory light into the given viewing window. ### Claim 26 (depends on 25) A display apparatus according to claim 25, the display apparatus being an autostereoscopic display apparatus wherein the control system is further arranged to control the display apparatus to display temporally multiplexed left and right images and synchronously to direct the displayed images into viewing windows in positions corresponding to left and right eyes of an observer. ### Claim 27 (depends on 26) A display apparatus according to claim 26, wherein the control system further comprises a sensor system arranged to detect the position of an observer across the display apparatus, and the control system is arranged to direct the displayed images into viewing windows in positions corresponding to left and right eyes of an observer, in dependence on the detected position of the observer. ### Claim 28 (depends on 25) A display apparatus according to claim 25, the display apparatus being, a dual view display apparatus, wherein the control system is arranged to direct the same displayed image into viewing windows in at least first and second viewing positions.