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EP-3532881-B1 - METHOD AND SYSTEM FOR LARGE FIELD OF VIEW DISPLAY WITH SCANNING REFLECTOR

EP3532881B1EP 3532881 B1EP3532881 B1EP 3532881B1EP-3532881-B1

Inventors

  • PREMYSLER, PHILIP
  • YEOH, Ivan Li-Chen
  • EDWIN, LIONEL ERNEST
  • FREEDMAN, BARAK
  • MATHUR, VAIBHAV
  • ZHANG, XIAOYANG
  • DALRYMPLE, Tim mark
  • CARLISLE, CLINTON
  • OH, CHULWOO

Dates

Publication Date
20260513
Application Date
20171027

Claims (13)

  1. An image display system (200; 300; 500; 600; 700; 900; 1000; 1100; 1800; 3100), comprising: an optical subsystem (310; 510; 710; 1002; 1300; 1400; 1600; 1802, 1804, 1806, 1808; 2000; 2100; 220; 2300; 2400; 2600; 3102-3024) configured to emit a first imagewise modulated light beam (241; 320; 720; 3126R) at a first angle and a second imagewise modulated light beam (242; 320; 720; 3126G) at a second angle, wherein the first imagewise modulated light beam (241; 320; 720; 3126R) illuminates a first portion of a tiled composite field of view (261, 262; 400) and the second imagewise modulated light beam (242; 320; 720; 3126G) illuminates a second portion of the tiled composite field of view (261, 262; 400); a scanning mirror (230; 330; 730; 930; 1008; 1030; 1822; 3130) positioned to intercept and reflect the first imagewise modulated light beam (241; 320; 720; 3126R) and the second imagewise modulated light beam (242; 320; 720; 3126G); and a waveguide (250; 350; 750; 1006; 1050; 1809, 1811, 1812), having: at least one input coupling optical element (252; 352; 752; 952; 1012; 1152; 1814, 1816, 1818) for reflectively diffracting the first imagewise modulated light beam (241; 320; 720; 3126R) and the second imagewise modulated light beam (242; 320; 720; 3126G) into the waveguide (250; 350; 750; 1006; 1050; 1809, 1811, 1812); and an output coupling optical element (254; 354; 754; 1054; 2774) for projecting a plurality of output light beams derived from the first imagewise modulated light beam (241; 320; 720; 3126R) and the second imagewise modulated light beam (242; 320; 720; 3126G) from the waveguide (250; 350; 750; 1006; 1050; 1809, 1811, 1812) to illuminate the tiled composite field of view (261, 262; 400), wherein the at least one input coupling optical element (352) is a polarization selective device.
  2. The image display system (200; 300; 500; 600; 900; 1000; 1100; 1800) of claim 1 wherein: the optical subsystem (310; 510; 1002; 1300; 1400; 1600; 1802, 1804, 1806, 1808; 2000; 2100; 220; 2300; 2400; 2600) is disposed on an opposite side of the waveguide (250; 350; 750; 1006; 1050; 1809, 18011, 1812) from the scanning mirror (230; 330; 730; 930; 1008; 1030; 1822; 3130), and preferably the at least one input coupling optical element (252; 352; 752; 952; 1012; 1814, 1816, 1818) is positioned between the optical subsystem (310; 510; 1002; 1300; 1400; 1600; 1802, 1804, 1806, 1808; 2000; 2100; 220; 2300; 2400; 2600) and the scanning mirror (230; 330; 730; 930; 1008; 1822) such that the first imagewise modulated light beam (241; 320) and the second imagewise modulated light beam (242; 320) emitted from the optical subsystem pass through the at least one input coupling optical element (252; 352; 752; 952; 1012; 1814, 1816, 1818) before reaching the scanning mirror (230; 330; 730; 930; 1008; 1822).
  3. The image display system (300; 1800) of claim 2 further comprising a polarization control element positioned between the optical subsystem (310; 1802, 1804, 1806, 1808) and the at least one input coupling optical element (352; 1814, 1816, 1818) such that the first imagewise modulated light beam (320) and the second imagewise modulated light beam (320) pass through the polarization control element before reaching the at least one input coupling optical element (352).
  4. The image display system (300) of claim 3 wherein the optical subsystem (310) is configured to produce the first imagewise modulated light beam (320) and the second imagewise modulated light beam (320) in a linearly polarized state and the polarization control element comprises a waveplate (370) that is configured to convert the first imagewise modulated light beam and the second imagewise modulated light beam to at least one circularly polarized light state and the at least one input coupling optical element (352) is polarization selective in that the at least one input coupling optical element (352) is selective on the basis of handedness of circularly polarized light.
  5. The image display system (1800) of claim 3 wherein the at least one input coupling optical element (1814) comprises a diffraction grating that includes a cholesteric liquid crystal (1902), preferably wherein the at least one input coupling optical element (1814) further comprises an alignment layer (1928) that establishes a periodic lateral variation in an alignment direction of the cholesteric liquid crystal (1902).
  6. The image display system of one of claims 1 to 5 wherein the optical subsystem comprises: a first three color channel modulated light source that is configured to produce the first imagewise modulated light beam; and a second three color channel modulated light source that is configured to produce the second imagewise modulated light beam, preferably wherein: the first three color channel modulated light source comprises a first red laser, a first green laser, and a first blue laser; and the second three color channel modulated light source comprises a second red laser, a second green laser and a second blue laser, and preferably wherein: the first three color channel modulated light source comprises a first dichroic beam combiner optically coupled to the first red laser, the first green laser and the first blue laser; and the second three color channel modulated light source comprises a second dichroic beam combiner optically coupled to the second red laser, the second green laser and the second blue laser.
  7. The image display system (200; 300; 500; 600; 700; 900; 1000; 1100; 1800; 3100) of one of claims 1 to 6 wherein the optical subsystem (310; 510; 710; 1002; 1300; 1400; 1600; 1802,1804, 1806, 1808; 2000; 2100; 220; 2300; 2400; 2600; 3102-3024) is configured to emit the first imagewise modulated light beam (241; 320; 720; 3126R) along a first path and to emit the second imagewise modulated light beam (242; 320; 720; 3126L) along a second path that intersects (1428) the first path at the scanning mirror.
  8. The image display system (700) of one of claims 1 to 7 further comprising a polarizer (780) and a wave plate (770) wherein the optical subsystem (710) and the scanning mirror (730) are disposed on a common side of the waveguide (750 along with the polarizer (780) and the wave plate (770) and wherein a first optical path segment from the optical subsystem (710) to the scanning mirror (730) extends from the optical subsystem (710) to the polarizer (780) and from the polarizer (7809 through the wave plate (770) and a second optical path segment from the scanning mirror (730) to the at least one input optical coupling optical element (752) traverses the wave plate (770) and the polarizer (780).
  9. The image display system (600; 1800) of one of claims 1 to 8, wherein at least one input coupling optical element (352; 1814, 1816, 1818) comprises a first input coupling grating (ICG1; 1814) and a second input coupling grating (ICG2; 1816).
  10. An image display system (800; 900), comprising: a light source (802-826) for providing a collimated incoming light beam (845; 920), the collimated incoming light beam including multiple imagewise modulated components; a scanning mirror (830; 930) with a diffractive surface (832; 932) for receiving the collimated incoming light beam (845; 920) and for providing a plurality of reflectively diffracted light beams (841-844; 940) having different angles of diffraction, each of the plurality of reflectively diffracted light beams configured to illuminate a portion of a field of view (966); and a waveguide (851; 950), having: an input coupling optical element (850; 952) for reflectively diffracting the plurality of reflectively diffracted light beams (841-844; 940) into the waveguide (851; 950); and an output coupling optical element (853; 954) for projecting a plurality of output light beams (946) from the waveguide (851; 950) to form a projected image with a composite field of view (966), the plurality of output light beams (946) being derived within the waveguide (851; 950) from the plurality of reflectively diffracted light beams (841-844; 940).
  11. The image display system (800; 900) of claim 10, wherein the multiple imagewise modulated components comprise components having different wavelengths, and preferably wherein the multiple components comprise a plurality of sets of red, green, and blue components.
  12. The image display system (800; 900) of one of claims 10 and 11, wherein the multiple imagewise modulated components comprise components having different polarization, and preferably wherein the input coupling optical element (850; 952) is polarization state selective.
  13. The image display system (900) of one of claims 10 to 12, wherein: the scanning mirror (930) is disposed on an opposite side from the light source with respect to the waveguide (950); and the input coupling optical element (952) of the waveguide (950) is configured to allow the collimated incoming light beam (920) to pass through the input coupling optical element (952) and the waveguide (950), and the input coupling optical element (952) is configured to couple the plurality of reflectively diffracted light beams (940) into the waveguide (950) by diffracting the plurality of reflectively diffracted light beams (940) at an angle above a critical angle for the waveguide (950).

Description

TECHNICAL FIELD The invention is in the field of computing and display technologies. BACKGROUND OF THE INVENTION Modern computing and display technologies have facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, wherein digitally produced images or portions thereof are presented in a wearable device to a user in a manner wherein they seem to be, or may be perceived as, real. A virtual reality, or "VR," scenario typically involves presentation of digital or virtual image information without transparency to other actual real-world visual input; an augmented reality, or "AR," scenario typically involves presentation of digital or virtual image information as an augmentation to visualization of the actual world around the user. The wearable device may include augmented and/or virtual reality glasses. The image can be displayed using image frames or raster scanned images. In a scanning image display system, each of the light beams defines the pixels of the image. By scanning the mirrors in two orthogonal axes, a two-dimensional field of view (FOV) can be created. The images can be projected onto the spectacle lens, which can include waveguide-based eyepieces and other optical elements, such as optical fibers. The image display systems can be mounted on each of the left and right side the glasses frames. US 2010/0149073 A1 discloses (in figure 29e) an image display system comprising an optical subsystem configured to emit a first imagewise modulated light beam and a second imagewise modulated light beam, and a scanning mirror positioned to intercept and reflect the first and second imagewise modulated light beams, producing a composite field of view. US 2010/0201953 A1 and US 2010/0079865 A1 disclose each an image display system comprising an optical subsystem configured to emit a light beam, a scanning positioned to intercept and reflect the light beam, a waveguide receiving the light beam and projecting the light beam to illuminate a field of view. SUMMARY OF THE INVENTION Conventional scanning image displays in a wearable device for virtual reality or augmented reality applications often have limited field of view, because the scanning mirror has limited range of scan motion and design constraints in the arrangement of optical elements. However, this arrangement can lead to a larger device size, which can be undesirable. Embodiments of the present invention provide scanning image display systems with large field of view while maintaining a small device form factor. In some embodiments, the larger field of view can be achieved by scanning multiple incoming light beams at the same time and combining the individual fields of view into a larger composite field of view. According to a first aspect of the invention, an image display system according to claim 1 is provided. It includes a scanning mirror for receiving two or more incoming light beams and providing a plurality of reflected light beams. Each of the plurality of reflected light beams is configured to provide an image in a respective field of view. The image display system also includes a waveguide having an input coupling optical element and an output coupling optical element. The input coupling optical element is configured for coupling the plurality of reflected light beams into the waveguide. The output coupling optical element is configured for projecting a plurality of output light beams from the waveguide to form a projected image in a tiled composite field of view. Further developments of the first aspect of the invention are according to dependent claims 2. 9. In some embodiments, the image display system also includes two or more RGB (Red-Blue-Green) combiners disposed on an opposite side of the waveguide from the scanning mirror. The RGB combiners are configured to provide the two or more incoming light beams having different incident angles. The input coupling optical element is configured to allow the incoming light beams to pass through the waveguide to reach the scanning mirror. The input coupling optical element is also configured to couple the reflected light beams into the waveguide. In some embodiments of the image display system, the two or more RGB combiners are disposed at different angles with respect to the scanning mirror to provide the two or more incoming light beams having different incident angles. In alternative embodiments, the two or more RGB combiners are disposed at the same angle with respect to the scanning mirror, and the image display system further includes reflective optical elements to provide two or more light beams having different incident angles. In some embodiments, the input coupling optical element is a polarization sensitive diffractive input coupling grating (ICG). In some embodiments, the image display system also includes a polarization control element disposed between the scanning mirror and the waveguide to convert the incoming beam to a polarizati