EP4792174A1 - Curved eye box - Google Patents

Abstract

A wearable display for displaying augmented reality (AR) content to one or more eyes of a user, said wearable display comprising: (a) a wearable structure; (B )at least one display attached to said wearable structure and having a curved three-dimensional light-emitting surface configured for emitting light beams containing AR content; (c) at least one combiner attached to said wearable structure and having a curved, three-dimensional reflective surface configured for reflecting said light beams toward an eye of said user and causing said light beams to converge in a curved, three-dimensional eye box.

Description

CURVED EYE BOX

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present patent application claims the benefit of U.S. Provisional Patent Application 63/543,755, filed October 12, 2023, the entire disclosure of which is hereby incorporated herein by reference.

FIELD OF INVENTION

[0002] The present invention is directed generally to displaying content focused on a user’s eye, and, more specifically, to expanding the eye box in virtual reality (VR) or augmented reality (AR) applications.

BACKGROUND

[0003] In VR or AR applications, the "eye box" refers to the optimal area in which the user's eyes can move while still maintaining a clear and immersive view of the display. It is essentially a three-dimensional volume in front of the VR/AR headset's lenses where the virtual image appears sharp and in focus.

[0004] The size and quality of the eye box affect the overall comfort and usability of the headset. A larger eye box allows more freedom of movement for the user's eyes without needing to adjust the headset or experience blurriness. In contrast, a smaller eye box may require the user to keep their eyes more precisely centered to maintain a clear image.

[0005] Typical AR/VR devices use a flat imaging plane in their optical design. The image plane is the source of the viewed image and may be an emitter of light or a reflector of light coming from a display device. As more and more field of view (FOV) is wanted, this flat imaging plane does not allow for the best large FOV AR/VR experience due to distortion, form factor, resolution at the edge of FOV, and pupil swim. More specifically, the eyeball rotates about the central vertical axis and horizontal axis and this rotation causes the lens and/or pupil to move in and out of the eye box as the eye rotates because the flat plane of the display device is arranged in space to intersect with the pupil/lens area of the eye only when the eye is in one position, which is usually looking straight ahead or slightly downward. This is exacerbated when the field of view of the display system gets larger because the eye shifts further from side to side, up and down or angularly, depending on the shape of the field of view, to view the digital content presented towards the edges of the larger field of view.

[0006] Accordingly, Applicant recognizes a need to expand the size and quality of the FOV. The present invention fulfills this need among others.

SUMMARY OF INVENTION

[0007] The following presents a simplified summary of the invention in order to provide a basic understanding of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

[0008] In one embodiment, the present invention relates to a wearable display for displaying augmented reality (AR) content to one or more eyes of a user, the wearable display comprising: (a) a wearable structure; (b) at least one display attached to the wearable structure and having a curved three-dimensional light-emitting surface configured for emitting light beams containing AR content; and (c) at least one combiner attached to the wearable structure and having a curved, three-dimensional reflective surface configured for reflecting the light beams toward an eye of the user and causing the light beams to converge in a curved, three-dimensional eye box.

BRIEF DESCRIPTION OF FIGURES

[0009] Fig. 1 shows a schematic of one embodiment of the curved eye box of the present invention.

[0010] Fig. 2 illustrates a curved eye box and curved optic to generate the eye box in accordance with one embodiment of the present inventions.

[0011] Fig. 3 A illustrates a curved eye box and curved optic in accordance one embodiment of the present inventions.

[0012] Fig. 3B illustrates a curved eye box and curved optic with a thickened optical surface in accordance with one embodiment of the present inventions. [0013] Fig. 3C illustrates a curved eye box and curved optic with a thickened optical surface and vertical plane in accordance with one embodiment of the present inventions.

[0014] Fig. 3D illustrates a curved eye box and curved optic as they appear in the vertical plane in accordance with one embodiment of the present inventions.

[0015] Fig. 3E illustrates computed curved optic surfaces in accordance with one embodiment of the present inventions.

[0016] Fig. 4 illustrates the optical properties of a fiber composite structure in accordance with one embodiment of the present inventions.

[0017] Fig. 5 illustrates an optical fiber composite structure in accordance with one embodiment of the present inventions.

[0018] Figs. 6A and 6B show different perspectives of the intersection plane of the present invention.

[0019] Figs. 7A-7B shows a comparison between a conventional flat eye box and the curved eye box of the present invention.

[0020] Figs. 8A-8C show the integration of the intersection plane in various positions about the vertical axis.

[0021] Fig. 9 shows one embodiment of the optics of the present invention.

[0022] Fig. 10 shows a schematic of one embodiment of the light rays leaving the curved light emitting surface at normal angles.

[0023] Fig. 11 shows one embodiment of the wearable display of the present invention.

DETAILED DESCRIPTION

[0024] There are disclosed herein new systems and methods for displaying content within a curved, shaped eye box for mixed reality headsets.

[0025] Referring to Figs. 9 and 11, one embodiment is shown of a wearable display of the present invention for displaying augmented reality (AR) content to one or more eyes of a user. The wearable display comprises: (a) a wearable structure 1101, for example, at helmet 1102; (b) at least one display 901 attached to the wearable structure and having a curved three-dimensional lightemitting surface 901a configured for emitting light beams 903 containing AR content: (c) at least one combiner 902 attached to the wearable structure and having a curved, three-dimensional reflective surface 902a configured for reflecting the light beams 904 toward an eye 910 of the user 911 and causing the light beams to converge in a curved, three-dimensional eye box 905. These elements are described in greater detail below along with selected alternative embodiments.

[0026] Fig. 1 illustrates an exemplary and non-limiting embodiment of a curved eye box in accordance with one embodiment of the present inventions. The front surface of the eye (e.g., a lens portion, lens front, iris, white portion of the eyeball) rotates along a surface 104, which is a surface determined by rotating the eyeball 102 about its vertical axis. An eye box in accordance with the principles of the present inventions has an image surface that substantially conforms with the rotating front surface of the eyeball. The image surface is generally described as a volume of space in which when the eye is positioned a person can see the digital content presented by the XR display.

[0027] The eye box volume is generally defined by its front surface 108, rear surface 106 and its length measured along the curve of either surface 106, 108 from side to side. The length of the eye box generally corresponds with the field of view of the XR optical system. The larger the field of view, the larger the length of the eye box. In embodiments the eye box is curved substantially coincident with the front turning surface of the eyeball throughout its entire length, or much of its length. In embodiments, the curve is continuous, compounded, spanning the length, spanning a portion of the length, etc. The curved eye box volume better covers the front surface of the eyeball as the eyeball moves and it should be understood that a shaped eye box may be configured to accommodate a large vertical field of view and a large-angled field of view.

[0028] Referring to Figs. 7A and B, a comparison of a conventional planar eye box 701 is shown relative to the curved eye box 702 of the present invention. As shown in the embodiment of Fig. 7B, the curved, three-dimensional eye box is convex. In one embodiment, the wearable structure has horizonal and vertical axes, wherein the eye box is convex along the horizontal axis and flat along the vertical axis. In other words, the eye box may be convex along the horizontal axis of the user’s eye and essentially flat along a vertical axis of the user’s eye. In one embodiment, the eye box is convex long both the horizontal and vertical axes of the user’s eye.

[0029] Fig. 2 illustrates an exemplary and non-limiting embodiment of a partially see- through optic (e.g., combiner for AR headset) 210 with a curved surface 202 designed to reflect image light towards the eye of a user and form a curved eye box 208. The shape of the curved surface 202 may mimic that of the desired curvature of the eye box 208. In embodiments, a flat wavefront is generated from a display (e.g., backlit LCD, OLED, LCoS) and directed to reflect off of the curved surface 202 of the combiner 210 such that a curved eye box 208 is presented to the user's eye.

[0030] Figs. 3 A-F show one embodiment of a method for configuring the display and combiner to achieve a curved eye box as disclosed herein. With reference to Fig. 3 A, there is illustrated an exemplary and non-limiting embodiment of the first step performed when modeling the geometry of the curved surface. As illustrated, there is imported a freeform optical surface 302, image plane 304 and entrance pupil/eye box 306 from an optical modeling program into a solid modeling program. Next, utilizing the solid modeling program, the surface of the optical surface 302 is thickened as illustrated in exemplary and non-limiting form with reference to Fig. 3B.

[0031] Next, with reference to Fig. 3C, there is illustrated an exemplary and non-limiting embodiment of the creation of an intersection plane 308 oriented vertically and passing through the center of eye box to create an intersection between eye box 306, imaging plane 304 and thickened optical surface 302. Next, with reference to Fig. 3D, there is an exemplary and nonlimiting illustration of the removal of all modeled elements outside of the intersection plane. The resulting cross section of the optical surface 312 and the cross section of the image plane 314 are illustrated as existing within the intersection plane 308.

[0032] Referring to Figs 6A and 6B, the modeled elements along the intersection plane 308 shown in Fig. 3D are shown with respect to the user’s eye. Specifically, Fig. 6A shows a side view of the intersection plane 308 in which light rays being emitted from the light emitting surface of the display are reflected by the combiner, causing them to converge in the eye box of the user. Fig. 6B shows the intersection plane 308 as a vertical plane in the pupil of the user’s eye.

[0033] With reference to Fig. 3E, there is illustrated a curved optical surface 316 and curved image plane 318 resulting from pivoting the intersection plane 308 about a vertical axis about the center of an eye labelled axis 101. In practice, axis 101 is approximately half the diameter of a human eye from the pupil, or about 12.5 mm. A typical horizontal field of view may be approximately 135 degrees.

[0034] Referring to Figs. 8A-C, the process of defining the curved display surface and the curved combiner surface is shown schematically. In Fig. 8A, the intersection plane 308 is rotated about the vertical axis in 4 positions, in Fig. 8B the intersection plane is rotated about the vertical axis in 6 positions, and finally, in Fig. 8C the intersection plane is rotated about the vertical axis in an infinite number of positions thereby defining continuous curved surfaces for the light emitting of the display and the reflective surface of the combiner.

[0035] The resulting curved surface may be imported into an optical modeling program with the curved optical surface 316 and curved image plane 318 and fit to a desired degree of correlation with a set of Zemike polynomials.

[0036] As described with reference to Figs. 3 A-3E a curved display space allows for a high resolution throughout the entire FOV, an unlimited horizonal FOV limited by form factor constraints, no pupil swim, better human form factor and minimal distortion. The described design method is agnostic to horizontal FOV and designed for human centric viewing by optimizing for the retina as the image sensor.

[0037] This design is not limited to a helmet but may apply to any VR/AR application. Standard and well known optical modeling programs may be utilized to define a reflective surface with total required vertical FOV. In some instances, the model be configured with an entrance pupil size set to a desired vertical eye box size. As described more fully below, the shape of the reflective surface is optimized and/or improved until a required modulation transfer function (MTF) is satisfied.

[0038] In some embodiments, the curved surface is designed by optimizing a set of Zernike polynomials within specific constraints. Zemike polynomials may be combined in differing amounts in accordance with a coefficient unique to each polynomial to define a surface of arbitrary shape.

[0039] With reference to Fig. 5, one embodiment of the display 500 is shown. In one embodiment, display’s curved three-dimensional light-emitting surface 318 is a convex surface. In one embodiment, the wearable structure has horizonal and vertical axes, wherein the curved three- dimensional light-emitting surface is convex along the horizontal axis and essentially flat along the vertical axis.

[0040] In one embodiment, the display 500 comprises a backplane 503 opposing the curved three-dimensional light-emitting surface 318. In one embodiment, the display transmits the light rays from the backplane 503 to the curved three-dimensional light-emitting surface. In one embodiment, a flat image display 503 operates as a source for emitting image data which is conveyed to the curved three-dimensional light-emitting surface 318 such that the light rays are emitted essentially normal to the surface 318 (see, for example, Fig. 10, which is a schematic of surface 318 in which light rays are emitted essentially normally from the surface).

[0041] In one embodiment, the backplane 503 comprises a liquid crystal display (LCD) and a backlight. In one embodiment, the backlight controls chief rays and cone angle.

[0042] In one embodiment, optical conduit couples the light rays from the backplane to the curved three-dimensional light-emitting surface. In one embodiment, the optical conduit comprises optical fibers. It is known to utilize fiber optics to guide beams of light. With reference to Fig. 4, there is illustrated an exemplary and non-limiting embodiment of a fiber optic mechanism for directing source light. As illustrated, composite fiber optic 400 is formed of a plurality of fiber elements, each a fiber optic strand, packed closely together and extending generally parallel one to the other. In practice, individual fiber elements are on the order of approximately 4 to 25 um. The fiber strands may be fused together in a coherent imaging array forming a billet. In this way, an image, such as the text shown resting below the composite fiber optic 400, may be transferred to the upper circular surface of the composite fiber optic 400. In the illustrated example, while extending upwards from the bottom surface of the composite fiber optic 400 to the top surface, the fiber strands are rotated 180 degrees resulting in an inverted image of the inputted text image. This is illustrative of the ability of the billet to transmit a coherent image comprised of many pixels each formed by the terminus of a single fiber strand.

[0043] In one embodiment, the display comprises pixels and each optical fiber corresponds to a pixel. In accordance with an exemplary and non-limiting embodiment, in some instances, hundreds, thousands or even millions of individual optical fibers approximating the number of pixels in a display, may be utilized to transfer an image plane. In one embodiment, composite fiber optic 502 is shaped to transmit the image data emitted by the flat image display 503 to a bottom surface comprising curved image plane 318. In this manner, a flat image display 500 may be utilized to produce a curved surface of image emission formed by the curved image plane 318.

[0044] In some embodiments, a face of a fiber optic mechanism may be optically coupled to a light emitting display, such as a micro-OLED display. In such instances, each fiber optic strand’s cross-sectional size may be comparable to an OLED pixel size in order to maintain high resolution imagery.

[0045] Alternatively, rather than using optical wave guides to convey light from the planar surface to the curved light-emitting surface, the light emitting surface may be bent or otherwise distorted. Still other alternatives will be obvious to those of ordinary skill in the art in light of this disclosure.

[0046] In one embodiment, the reflective surface of the combiner is concave. In one embodiment, the wearable structure has horizonal and vertical axes, and wherein the curved, three- dimensional reflective surface is concave along both the horizontal and vertical axes.

[0047] In one embodiment, the wearable structure 1101 is headgear. In one embodiment, the headgear is a helmet. In one embodiment, the helmet is a pilot’s helmet.

[0048] These and other advantages maybe realized in accordance with the specific embodiments described as well as other variations. It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

CLAIMS What is claimed is:

1. A wearable display for displaying augmented reality (AR) content to one or more eyes of a user, said wearable display comprising: a wearable structure; at least one display attached to said wearable structure and having a curved three- dimensional light-emitting surface configured for emitting light beams containing AR content: at least one combiner attached to said wearable structure and having a curved, three- dimensional reflective surface configured for reflecting said light beams toward an eye of said user and causing said light beams to converge in a curved, three- dimensional eye box.

2 The wearable display of claim 1, wherein said curved three-dimensional light-emitting surface is a convex surface.

3 The wearable display of claim 2, wherein said wearable structure has horizonal and vertical axes, wherein said curved three-dimensional light-emitting surface is convex along the horizontal axis and flat along the vertical axis.

4 The wearable display of claim 1, wherein said curved, three-dimensional reflective surface is a concave surface.

5 The wearable display of claim 4, wherein said wearable structure has horizonal and vertical axes, and wherein said curved, three-dimensional reflective surface is concave along both said horizontal and vertical axes.

6 The wearable display of claim 1, wherein said curved, three-dimensional eye box is a convex.

7 The wearable display of claim 6, wherein said wearable structure has horizonal and vertical axes, wherein said eye box is convex along the horizontal axis and flat along the vertical axis.

8. The wearable display of claim 1, wherein said at least one display comprises two displays, one for each eye of said user, and wherein said at least one combiner comprises two combiners, each combiner associated with one of said two displays.

9. The wearable display of claim 1, wherein said wearable structure is headgear.

10. The wearable display of claim 9, wherein said headgear is a helmet.

11. The wearable display of claim 10, wherein said helmet is a pilot’s helmet.

12. The wearable display of claim 1, wherein said curved three-dimensional light-emitting surface emits said light rays essentially normal to said curved three-dimensional light-emitting surface.

13. The wearable display of claim 1, wherein said display comprises a backplane opposing said curved three-dimensional light-emitting surface.

14. The wearable display of claim 13, wherein said display transmits said light rays from said backplane to said curved three-dimensional light-emitting surface.

15. The wearable display of claim 13, wherein said backplane comprises a liquid crystal display (LCD) and a backlight.

16. The wearable display of claim 15, wherein said backlight controls chief rays and cone angle.

17. The wearable display of claim 14, wherein optical conduit couples said light rays from said backplane to said curved three-dimensional light-emitting surface.

18. The wearable display of claim 17, wherein said optical conduit comprises optical fibers.

19. The wearable display of claim 18, wherein said display comprises pixels and wherein each optical fiber corresponds to a pixel.