Patent Description:
In present society, there has been increasing traction towards more immersive light-field and/or autostereoscopic three-dimensional (3D) displays, due to advancement in electronics and micro fabrications. Most current and common autostereoscopic 3D displays can require virtual reality (VR) headgear or similar devices. However, VR headgear can cause eye strain and other similarly-related fatigue issues. These issues occur due to two primary issues with current and common VR headgear. Firstly, most common and current VR headgear divide the image into two viewing zones in which parallax is extracted from those viewing zones and overlapped to procure a seemingly single, whole image. Secondly, most current and common VR headgear have the viewing zones too near to the user's eyes. Another issue with most current and common VR headgear is the binocular gaps in the image projected due to the images being fed into two separate viewing zones, one for each eye of the user with separate optics.

Document <CIT> generally relates to head-mounted displays, and more specifically, to high-density energy directing devices for two-dimensional, stereoscopic, light field and holographic head-mounted displays.

Document <CIT> discloses a vision display system and a head-mounted display device applied to light field display.

Document <CIT> generally relates to correcting for optical aberrations, and specifically relates to correcting for pupil swim.

One or more embodiments of the present disclosure are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements.

In this description, references to an "embodiment," "one embodiment" or similar words or phrases mean that the particular feature, function, structure or characteristic being described is included in at least one embodiment of the technique introduced here. Occurrences of such phrases in this specification do not necessarily all refer to the same embodiment. On the other hand, the embodiments referred to herein also are not necessarily mutually exclusive.

All illustrations of the drawings are to be describing selected versions of the technique introduced here and are not intended to limit the scope of the technique introduced here. All references of user or users pertain to either individual or individuals who would utilize the technique introduced here.

The technique introduced here includes a display system that generates a high-quality virtual image, which may be a 2D, stereoscopic 3D and/or multifocal image, where the display system has an intended (designed) viewing point for the human viewer that is at least <NUM> from the display (in contrast with conventional head-mountable displays (HMDs)) but not more than <NUM> from the display, without causing visual discomfort to the human viewer, while providing a diagonal field of view of at least <NUM> degrees. The system produces a single, contiguous light field that enables simultaneous detection of monocular depth by each eye of the human viewer, where the monocular depth can be greater than the actual distance of the display from the human viewer, and provides an apparent size of the display (as perceived by the human viewer) that is at least twice (2X) the actual size of the display when the human viewer is located at the intended viewing point. "Monocular depth" is the optical depth perceived by one eye, which the eye can accommodate to by varying the focal length of the eye lens. Monocular depth is based on the true curvature of the wavefront of the light. This is in contrast with stereoscopic depth, which is based solely on parallax. With the technique introduced here, monocular depth is also dynamically modifiable and, in contrast with current autostereoscopic displays, is not fixed at the physical location of the surface of the display panel.

For example, in some embodiments, a display system in accordance with the technique introduced here is designed to be positioned about <NUM> from the viewer's eyes and provides an apparent display size (i.e., as perceived by the human viewer) of approximately <NUM> inches diagonally while using a display that is only approximately <NUM> inches in size diagonally, with a field of view greater than <NUM> degrees and a headbox (useful viewing region) that spans at least <NUM> horizontally, all while providing a high quality virtual image without visual discomfort to the human viewer. In this context, "horizontally" means parallel to an imaginary line that passes through the geometric centers of the human viewer's two eyes when the human viewer is viewing the display in the normal (intended) manner.

The technique introduced here produces a concentric light field and provides monocular-to-binocular hybridization. The term "concentric light field" (also called "curving light field") as used herein means a light field in which, for any two pixels of the display at a fixed radius from the viewer (called "first pixel" and "second pixel"), the chief ray of the light cone emitted from the first pixel in a direction perpendicular to the surface of the display at the first pixel intersects with the chief ray of the light cone emitted from the second pixel in a direction perpendicular to the surface of the display at the second pixel. A concentric light field produces an image that is focusable to the eye at all points, including pixels that are far from the optical axis of the system (the center of curvature), where the image is curved rather than being flat, and the image is viewable within a reasonable viewing space (headbox) in front of the light field.

The term "monocular-to-binocular hybridization" (MBH) as used herein refers to the characteristic that a stereoscopic image is produced in a contiguous viewable spatial region that, in at least one dimension (e.g., horizontally), is significantly larger than (e.g., at least twice) the distance between the two eyes of the viewer of the display, where each eye of the viewer can detect the monocular depth that the light field is providing and can detect correct stereoscopic cues on that depth. MBH produces an image that does not require binocular isolation (the isolation of the two images for two eyes, such as is necessary in stereoscopic HMDs or any 3D that requires wearing a pair of glasses) to view, meaning there is no gap between the images seen by the left eye and right eye.

The technique introduced here can provide users with a device that reduces and/or eliminates eyes strain and other similarly-related fatigue on the user's eyes. It can also provide users with a device that provides a concentric light field display in which the image is not divided into two viewing zones. Also, the technique can provide users with a device that does not require the viewing zone to be too close to the user's eyes. The technique introduced here can provide users with a device that allows the user to be at the center of the light field projection, and that eliminates or minimizes binocular gaps in the image projected. The technique introduced here further can provide users with a device that generates continuous converging light ray bundles towards to the user's face in order to create a wrap-around viewing experience or a panoramic viewing experience.

The technique introduced here includes systems and methods for realizing concentric light field with MBH. As shown in <FIG>, in certain embodiments a display system <NUM> according to the technique introduced here includes a display portion <NUM> and a stand <NUM>, where the display portion <NUM> is attached to the stand <NUM> when in use, and may be removably attachable to the stand <NUM> by a connector <NUM>. <FIG> shows a perspective view of the display portion <NUM> mounted to the stand <NUM>. <FIG> shows a perspective view of the display portion <NUM> by itself, while <FIG> shows a perspective view of the stand <NUM> by itself.

The system is designed to enable the display portion <NUM> to be positioned very close to the eyes of the user (also called "viewer" herein) when in use, though not as close as in a conventional HMD device. Hence, the stand <NUM> can include a base <NUM>, and a plurality of elongate members <NUM> connected by one or more joints <NUM>. At least some of joints <NUM> may allow pivoting and/or rotational movement of the connected members <NUM> to allow for adjustment by the user of the position and orientation of the display portion <NUM>, as desired.

In at least some embodiments, the base <NUM> is connectable to the bottommost member of the plurality of members <NUM>, as illustrated in <FIG>. The plurality of members <NUM> can be of any shape, size, material, features, type or kind, orientation, location, quantity, components, and arrangements of components that would allow the technique introduced here to fulfill the objectives and intents of the technique introduced here. The plurality of members <NUM> can be pivotally attached to one another from end to end. The bottommost member can be mounted to the topside of the base <NUM>. The topmost member can be mounted to the rear end of a connector <NUM>. The rear end of the connector <NUM> can be mounted to the topmost member of the plurality of members <NUM>, while the front end of the connector <NUM> is mounted to the display portion <NUM>, as illustrated in <FIG>.

The display portion <NUM> has a mechanical housing that houses, as shown schematically in <FIG>, a computer <NUM>, at least one display <NUM> and an optical subsystem <NUM>. The optical subsystem <NUM> includes the preparation optics <NUM>, relay optics <NUM> and an exit pupil <NUM>. The computer <NUM> can be of any shape, size, material, features, type or kind, orientation, location, quantity, components, and arrangements of components that would allow the technique introduced here to fulfill the objectives and intents of the technique introduced here. As shown in <FIG>, the computer <NUM> can primarily include a content engine <NUM> and (optionally) one or more sensors <NUM>. The sensors <NUM> can include, for example, one or more of tracking sensors, localization sensors, or other similar objects, and/or any combination of the aforementioned items. Such sensors can also include, for example: mapping sensors, camera sensors, time-of-flight sensors, dual mono camera sensor rigs, eye-tracking sensors, hand-tracking sensors, head-tracking sensors, and other similar or similarly-related objects.

The computer <NUM> can be or include, for example, one or more conventional programmable microprocessors, digital signal processors, application-specific integrated circuits (ASICs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), or any combination of such types of devices. The content engine <NUM> in the computer <NUM> enables the computer <NUM> to generate digital image content <NUM> for generation of images. At least a portion of the content engine <NUM> can be implemented as software or firmware. The digital content <NUM> can be isolated content to be displayed to the user, content that is based on some localization and/or tracking data surrounding the display, other similarly-related items, and/or a combination of the aforementioned items. The computer <NUM> may be capable of pre-compensating for distortion or modifications needed on the digital content to produce the images needed to be generated to the user, so that the image (based on the digital content) is emitted from the display portion <NUM> to the eye of the user with corrected aspect ratio and structure depending on whether the digital image content is 3D, 2D, multi-focal, and/or other similarly-related types or kinds. The computer <NUM> sends the digital image content <NUM> from the content engine <NUM> to the display <NUM> of the display portion <NUM>. In other embodiments, the computer <NUM> and/or the content engine <NUM> may be external to the display portion <NUM>.

Referring still to <FIG>, the display portion <NUM> contains at least one display <NUM> that can generate images from the digital content <NUM> provided by the computer. The display <NUM> can be or include, for example, any one or more of: an image panel, a projector, a liquid crystal on silicon device (LCoS); or the like. In the case of a display <NUM> that is or includes a panel, the panel can be, for example, flat or curved, and can be of a liquid crystal display (LCD), organic light emitting diodes (OLED), light emitting diodes (LED), or other similar related types. In the case of a display <NUM> that is or includes a projector, the projector can be of a type or kind similar to, for example, the following: a scattering or diffusive screen projected with multiple projectors at different angles, pico-projectors, laser projectors, or other similarly-related objects. The display <NUM> can feed the image via generated light ray bundles of any form and/or shape to the preparation optics <NUM>. The back light of the display portion <NUM> may vary with angle to provide autostereoscopic 3D at the concentric region. In some embodiments, such angular light is prepared by Vertical Cavity Surface Emitting Laser arrays (VCSEL). In some embodiments, the display <NUM> is or includes a stack of LCD panels to provide 3D images with computational methods.

As shown in <FIG>, the display portion also contains preparation optics <NUM>, which receive the generated light ray bundles from the display, adjust the generated light ray bundles to adjust and/or tune the depth and/or size of the perceived image, and submit the adjusted light ray bundles to relay optics <NUM>. <FIG> illustrate different examples of the preparation optics <NUM> in detail. In these figures and in subsequent figures discussed below, the arrows show examples of ray bundle paths in the system. The preparation optics <NUM> may include, for example: a curved (e.g., conjugate) mirror, a lenticular lenslet array, a field-evolving (FE) cavity, a Fresnel plate, a tunable lens, a projection screen, mechanical adjusts, and/or other similarly related or relevant objects. The preparation optics <NUM> may also be such that the image can be transformed from a 2D format into a 3D presentation.

The preparation optics <NUM> can have any of several alternative examples. In the example of <FIG>, the preparation optics <NUM> include a field-evolving (FE) cavity that can change the focal plane of the virtual image by modulating the trajectory of the light ray bundles, i.e., by dynamically modifying the path lengths of the rays. In some instances, the FE cavity can set different sections of the display to different focal distances. In this example, the preparation optics <NUM> includes a beamsplitter plate <NUM> between two waveplates <NUM>. One waveplate <NUM> is near to the display <NUM>, while the other waveplate <NUM> is nearer to one side of a liquid crystal (LC) plate <NUM>. The other side of the liquid LC plate <NUM> is near to a polarization-dependent beamsplitter <NUM>.

In <FIG> and other figures discussed below, the arrows show examples of ray bundle paths in the system. In the left portion of <FIG>, light rays emitted from the display <NUM> are x-polarized. The light rays become y-polarized when they exit the waveplate <NUM> that is farther from the display <NUM>. They then become x-polarized again when they exit the polarization-dependent beamsplitter <NUM> toward the viewer (not shown, but toward the left of the figure). Conversely, in the right side of <FIG>, light rays reflected back toward the display <NUM> by the polarization-dependent beamsplitter <NUM> remain y-polarized, but are converted to x-polarization when they are reflected back (left) toward the viewer by the waveplate <NUM> that is farther from the display <NUM>.

In the example of <FIG>, the preparation optics <NUM> can include passive optics <NUM> on the submitting end or side of the display <NUM>, such that the image can be compensated for aberration, distortion, and/or directional brightness correction. Such examples of passive optics <NUM> can include, for example: Fresnel plates, lenticular lenslet arrays, parallax barriers, layered masks, and/or other similarly-related or similarly-relevant objects.

In the example of <FIG>, the preparation optics <NUM> include a passive FE cavity, the length of which (i.e., distance from display <NUM> to beamsplitter <NUM>) can be changed or altered via a mechanical actuator <NUM> or other similar mechanism. In the example of <FIG>, the preparation optics <NUM> include passive optics <NUM> combined with a mechanical actuator <NUM> mounted to the display <NUM> to change the position or distance of the display <NUM> with respect to the passive optics <NUM>.

Referring again to <FIG>, the display portion <NUM> can also include relay optics <NUM>. The relay optics <NUM> can be or include, for example, a freeform back visor, a waveguide, a screen with holographic element, or some combination thereof. However, the relay optics <NUM> can also have any combination of the following features and characteristics: curved or flat, with or without electromagnetic metasurface, with or without a holographic element, with or without diffraction grating, with or without Fresnel grating, polarized or non-polarized, transparent or opaque, utilizing geometrical optics or utilizing waveguides, and/or other similarly-related and/or similarly-relevant objects or features. <FIG> illustrates how the relay optics <NUM> can include any of various combinations of these features/characteristics. The relay optics <NUM> may receive the submitted light ray bundles from the preparation optics at one end, while being able to relay those light ray bundles through to the exit pupil.

As shown in <FIG>, the display portion can have an exit pupil <NUM>. The exit pupil <NUM> can be a hypothetical, three-dimensional manifold surrounding aperture that encircles the ray bundles that are exiting and propagating away from the display portion <NUM>. The exit pupil <NUM> may be positioned between the front of the user's face and the remainder of the display portion <NUM> where the image is seen by the user.

According to the invention, as discussed further below, the preparation optics <NUM> include a curved mirror in form of a conjugate mirror, to provide a concentric light field. A conjugate mirror has the shape of a partial ellipse when viewed in cross-section (i.e., an end of the ellipse where its radius is smallest), as viewed in a vertical plane parallel to the viewing axis. An ellipse has two foci (focal points). In the technique introduced here, the display portion <NUM> is designed to be positioned such that the viewer's head is located at or near (i.e., within several centimeters of) the focal point that is closest to the mirror, and between the two focal points of the ellipse that the mirror partially forms.

Conventionally, most curved mirrors have been hyperbolic, parabolic, bi-conic or spherical. Such mirrors are generally suitable for single point imaging in paraxial regime when the light is close to symmetry axis of the optical elements, such as the ones in telescopes or laser and sensing applications. However, in displays these mirrors fail, because they tend to perform very well at the center but fail at the edges of the image, as the edges are very much off axis and not in paraxial regime anymore. They are not suitable to provide a large horizontal field of view with high image accuracy where the displays and mirror are very close together. For example, if one has a long, flat horizontal display and positions it closer than or at the focal point of the parabolic mirror and looks at the reflection of that through a parabolic mirror, one will see that the image at the center of the display is acceptable, but the image becomes increasingly distorted and/or blurry the farther one looks from the center of the display.

A concentric light field, such as can be produced by use of a conjugate mirror, overcomes these problems. <FIG> shows a concentric light field <NUM>, which is shown in contrast with a planar light field <NUM> illustrated in <FIG>. In each of <FIG>, several bundles of light rays are shown, emanating from various different pixels of the display. In the concentric light field <NUM> produced by the curved display in <FIG>, a perpendicular ray from every pixel will converge toward a focal point and toward perpendicular rays from other pixels. In contrast, in the planar light field <NUM> of <FIG>, perpendicular rays from different pixels are parallel and therefore do not converge. Note that in alternative examples, a diffractive mirror or nanostructured mirror can be used instead of a conjugate mirror.

According to the invention of the technique introduced here, as shown in <FIG>, the head of the viewer <NUM> is positioned at or close to the focal point <NUM> of the conjugate mirror <NUM> (one of the two foci <NUM>, <NUM> of the ellipse <NUM> that the conjugate mirror <NUM> partially traces). The display <NUM> is close to the mirror <NUM>, above the user's field of view. A beamsplitter <NUM> is positioned in the field-of-view at a <NUM> degree angle as viewed from the side. The other focal point <NUM> of the ellipse <NUM> is behind the viewer's head when the viewer is looking at the displayed images.

In at least one embodiment, the distance between the foci <NUM>, <NUM> of the ellipse <NUM> is about <NUM>; and the viewer <NUM> can perceive a high quality image on the entire display as long as his or her head is positioned within about <NUM>% of that distance (about <NUM> in this example) from the focal point <NUM> closest to the mirror <NUM>, as measured along the viewer's viewing axis. (not shown) The viewer can move forward or backward within that range (along the viewing axis) and still see the image with high quality. The reflection in the mirror <NUM>, which is what the viewer <NUM> actually sees, is perpendicular to the axis (not shown) between the foci <NUM>, <NUM>, and therefore is coaxial with the long axis of the ellipse <NUM>. The fact that the viewer <NUM> is close to one of the foci (e.g., within about <NUM>% of the distance between the foci) of the ellipse <NUM> allows the viewer <NUM> to have almost equal distance to each edge of the mirror <NUM>, which reduces edge aberration.

Additionally, the fact that the second focal point <NUM> of the ellipse <NUM> is farther away means that, unlike with a parabolic or hyperbolic mirror, light rays propagating from the edges of the conjugate mirror <NUM> actually do not keep diverging, but instead bend inward faster. This enables pixels further away from the center of the display to be as focused as pixels at the center of the display.

The use of a conjugate mirror in this manner can provide a very large region in which the virtual magnified 2D or 3D image is visible on a curved surface or a curved volume with all pixels being focusable to the eye. This is unlike when one has a lens or magnifying glass in front of a display, since all points on the virtual image are focusable to the eye, including pixels that are far from the optical axis of the system (the center of the curvature), and the virtual image is curved rather than flat.

A curved or concentric light field in accordance with the technique introduced here can illuminate a large area in front of the display that is on the order of tens of centimeters; which is much larger than (e.g., at least <NUM> times) the approximately <NUM> distance between the two eyes of an average adult person, i.e., at least <NUM>. Consequently, both eyes not only can appreciate the monocular depth that the light field is providing, but they can also pick up correct stereoscopic cues on that depth. Monocular depth is the depth perceived by one eye via accommodation (change in focal length) of the eye lens; binocular depth is perceived based on the parallax between the image in the left eye and right eye. In most conventional systems such as head-mounted displays the curvature is either too steep such that it supersedes natural human horopter, or it is completely flat. This can cause eye fatigue; especially as the field of view increases.

Additionally, the technique introduced here provides a very large field of view with no gaps in the binocular vision. Unlike goggles, where there is a gap between the eyes that makes it appear like looking through two pipes, there is no pipe-like effect (binocular mask) with the technique introduced here. That is due to monocular-to-binocular hybridization (MBH) and the fact the viewable zone is a large continuous area, not two localized points in front of each eye. This allows the user to move and rotate his or her head and still perceive the depth correctly.

The human brain perceives depth based on eight cues, five of which are contextual and three of which are optical. The optical cues are motion parallax, static parallax and accommodation cue. If the wave front of the light is impacted to mimic the virtual distance, then the perceived 3D not only provides the accommodation depth cue but also provides the motion parallax and static parallax. However, a display system may provide only one of these depth cues; for example, autostereoscopic and stereoscopic headsets rely solely on parallax to provide depth. They do not provide the monocular depth cue for all depths for which they provide parallax. All stereoscopic AR/AR headsets and any 3D experience that requires wearing glasses, and most of glasses-free autostereoscopic 3D displays, rely on an approach where light is fed to left eye and right eye with different content to create parallax. Most conventional implementations require wearing some sort of binocular to eliminate the crosstalk between the left eye and right eye.

In contrast, the technique introduced here provides monocular depth (a depth that a single eye can perceive), which is perceivable in a very large contiguous area in front of the display system. This is MBH, which not only provides the correct depth per eye, but also provides matching vergence of the two eyes (parallax) for objects at different depths in the scene.

<FIG> illustrate differences between conventional techniques and MBH as provided by the technique introduced here. Specifically, <FIG> show the gap <NUM> in the binocular region (binocular isolation) that occurs with conventional curved-display HMDs and flat-display HMDs, respectively. In contrast, <FIG> shows the MBH (no gap) provided by using the technique introduced here.

Unlike in conventional techniques, the effective binocular viewing area with the technique introduced here is significantly larger than the distance between the viewer's eyes, so that the viewer can rotate and move her head and rotate her eyes to left and right and still see the depth with no gap in between the eyes. Hence, MBH, as provided by the technique introduced here, means the region where monocular depth is perceivable to the viewer is larger than the distance between the viewer's eyes, such that not only the accommodation of each eye is correct but also the vergence of the eyes follows the accommodation. This hybridization creates a much more realistic representation of the depth than conventional 3D displays.

<FIG> shows an embodiment of a display system in accordance with the technique introduced here, which uses a conjugate mirror to achieve concentric light field and MBH. The conjugate mirror <NUM>, which can be occlusive or partially transparent, forms the back of the display portion <NUM>, i.e., the visor, which can be mounted to an adjustable stand <NUM> as described above. In this embodiment, the display portion includes a flat directional or enhanced backlight positioned in front of and above the mirror, with its light emission surface disposed horizontally facing downward. The display <NUM> is positioned below and parallel to the backlight <NUM>. The backlight <NUM> can be either standard side-lit diffusive back light or preferably directional back light, such as backlight with directional film or directional layer on top, or backlight with diffractive layer to change the direction. In at least some embodiments the elements have local dimming techniques, such as micro-LED backlight where backlight can be dimmed in certain regions to provide better contrast and dynamic range. The elements in the backlight can be side-lit waveguide, micro LED array, diffractive directional waveguide, light diffuser, for example.

A privacy film <NUM> or other type of layer with directional optical transmissive properties is disposed over the downward facing surface of the display <NUM>. The privacy film may have a pass angle smaller than <NUM> degrees, for example. A beamsplitter <NUM> is disposed between the mirror <NUM> and the viewer <NUM> at a <NUM>-degree angle (as viewed cross-sectionally from the side, perpendicularly to the viewing axis.

In operation, light emitted by the backlight <NUM> and modulated by the display <NUM> propagates downward and then reflects off the beamsplitter <NUM> toward the mirror <NUM>, which reflects the light back toward the beamsplitter <NUM> with a rotated polarization, such that the reflected light then passes through the beamsplitter <NUM> and propagates to the eyes of the viewer <NUM>. An absorptive polarizer <NUM> may be disposed on the lower surface of the beamsplitter <NUM>, to reduce reflections. A lower baffle <NUM> of the display portion <NUM> may be disposed below the beamsplitter <NUM>, parallel to the display. One or more audio speakers <NUM> may be positioned at any convenient locations, such as attached to the underside of the lower baffle <NUM>.

<FIG> shows another example of a display system. In this example, the display portion <NUM> includes a curved-surface display <NUM>, which can be made of numerous contiguous active displays, such as OLED elements, for examples. A first curved-surface quarter-wave plate <NUM> is disposed directly upon the light emission surface of the curved display <NUM>. A semi-reflective curved-surface mirror <NUM> is disposed on top of one quarter-wave plate <NUM>. A second curved-surface quarter-wave plate <NUM> is disposed directly on the surface of the semi-reflective curved mirror <NUM>. A curved-surface liquid crystal (LC) plate <NUM> optionally is disposed on the surface of the second quarter wave plate. A curved-surface wire grid polarizer or a polarization-dependent beamsplitter <NUM> is disposed on the surface of the LC plate <NUM> (if present) or the second quarter-wave plate <NUM>. Line <NUM> represents the line of sight of the viewer <NUM>.

<FIG> show various additional illustrative details of the technique introduced here. In each of these figures, the display portion <NUM> may be mounted on a stand <NUM> (e.g., a hinged arm such as described above), which is not shown in these figures for simplicity. In the example of <FIG>, the display portion <NUM> contains at least two display panels <NUM>, one located above the user's field of view and the other beneath the user's field of view. Each display panel <NUM> is coated with preparation optics72 on the light emission surface of the display panel <NUM>. Also, in this embodiment the display portion <NUM> includes relay optics in the form of a freeform back visor <NUM> to relay or reflect the light ray bundles towards to the user's field of view.

In the embodiment of <FIG>, the display portion <NUM> contains a single display panel <NUM> beneath (or above, or to the side of) the user's field of view. The display panel <NUM> can be coated with preparation optics <NUM> on the surface of the display panel that projects light ray bundles. The display portion <NUM> in this embodiment also contains a beamsplitter <NUM> plate adjacent to and/or opposite from the display panel <NUM>, with the preparation optics such that the light ray bundles projected from the display panel with the preparation optics are fed to the beamsplitter plate before reaching or being reflected to the relay optics in the form a freeform back visor, which in turns sends the light ray bundles into the user's field view.

In the example of <FIG>, the display portion <NUM> of this alternative example can be seen as similar to the display portion in <FIG>, except that the display panels <NUM> are located to each side of the user's field of view. In yet another example shown in <FIG>, the display portion <NUM> of this alternative example can be seen as similar to the display portion in <FIG>, except that the relay optics are of holographic element <NUM> of either a flat or curved feature, instead of a freeform back visor. The holographic element <NUM> can be in the form of a three-layered panel, with each layer dedicated to different color channels of display, such as red, blue, and green, or some other color space. The dashed line represents the trace of rays coming from the virtual image.

As shown in <FIG>, the technique introduced here includes a second set of alternative examples of the technique introduced here. In the example of <FIG>, the display portion <NUM> contains a display in the form of at least two projectors <NUM>, with a projector <NUM> on each opposing side of the user's field of view. Also, in this example, the display portion <NUM> contains a curved holographic element screen <NUM>, where the light ray bundles are projected from the projectors <NUM> towards the curved holographic element screen <NUM>. From there, the light ray bundles are redirected towards the exit pupil and through to the user's field of view.

In another embodiment, shown in <FIG>, the display portion <NUM> is similar to the display portion in the embodiments of <FIG> and <FIG>; however, in this embodiment, the display of the display portion utilizes one or more projectors <NUM>, instead of a flat or curved panel. Each projector <NUM> can feed the light ray bundles through a scattering screen <NUM> before passing through the preparation optics <NUM>. The scattering screen <NUM> may be directional, for example. In at least some embodiments, the scattering screen <NUM> can be fed by a plurality of projectors <NUM> to create a high-density display 3D image. This image can then be fed through to the preparation optics <NUM>. Alternatively, the scattering screen <NUM> can be fed similarly by a plurality of projectors <NUM> to create a super multiview bundle of light rays for a three-dimensional image that is fed to the relay optics. A beamsplitter <NUM> is also used in this embodiment, in the manner described above.

In the example of <FIG>, the display portion contains one or more projectors <NUM>, relay optics in the form of a freeform back visor <NUM> and a transparent scattering screen <NUM>, thereby negating the need for a preparation optics. In this example, the projector or projectors <NUM> can be located adjacent to a side of the user's field of view and adjacent and/or opposite to the transparent side of the transparent scattering screen, as shown. The transparent scattering screen <NUM> can be made of, for example, mesh-like object with metallic microwire or nanowire arrays such that the light ray bundles can be reflected and/or scattered off the transparent scattering screen towards the freeform back visor, where the convergence of those light ray bundles are prepared for the user's eyes. The transparent scattering screen <NUM> be capable of operating in transmission mode and/or reflection mode alternatively. The transparent scattering screen <NUM> may be of various thickness and surface roughness across its face(s), to allow the light ray bundles to be scattered and/or reflected from the transparent scattering screen <NUM>.

<FIG> show a third set of alternative examples of the technique introduced here. In the example of <FIG>, the display portion <NUM> contains at least two displays <NUM>, one at the top and one at the bottom of the display portion. Each display may be preceded by preparation optics <NUM> in the light transmission path. The light ray bundles may be fed from each display <NUM> through its associated preparation optics <NUM> into the top end and bottom end of the relay optics <NUM>. In some alternative examples, each display <NUM> and its corresponding preparation optics <NUM> can be located on the sides of the display portion <NUM>, and more specifically, on the side faces of the relay optics <NUM> of the display portion <NUM>.

In the example of <FIG>, the relay optics can be a waveguide <NUM>. The waveguide <NUM> may be of a single-layered or a multilayered structure that confines electromagnetic waves and allows few modes of the electromagnetic waves to propagate. The waveguide <NUM> may be of a flat or a curved panel. The waveguide <NUM> may be of transparent materials with embedded angled reflecting surfaces to allow the light ray bundles to exit through to the exit pupil. Alternatively, the exiting face of the waveguide <NUM> may contain a surface featuring diffraction grating such that the light ray bundles can diffract and exit from the waveguide. Or, the waveguide <NUM> may be similar to a thin sheet of glass such that the light ray bundles are confined to a few modes of electromagnetic waves and allowed to propagate along the exiting face of the waveguide.

Alternatively, the waveguide <NUM> in the example of <FIG> can be a lightguide. The lightguide can be similar to the above-mentioned waveguide in shape, size, material, features, type or kind, orientation, location, quantity, components, and arrangements of components, except that the lightguide can be a single-layered or a multilayered transparent panel such that light ray bundles are reflected only a few times before exiting out the exiting face of the lightguide.

In the example of <FIG>, the display portion <NUM> contains additional relay optics in the form of a freeform back visor <NUM>, such that the waveguide <NUM> can feed the light ray bundles to the freeform back visor <NUM> before the light ray bundles are sent through the exit pupil to the user from the freeform back visor <NUM>.

In the example of <FIG>, the display portion contains a curved LCoS display <NUM>. The inner or medial face of the curved LCoS display can be coated or covered with preparation optics <NUM> in the form of a lenticular lenslet array, or similar objects, for example. The inner or medial face of the preparation optics <NUM> may be covered by a curved waveguide <NUM>. The preparation optics may be in the form of a curved FE cavity, or similar object. In at least some cases in which the light ray bundles from the display can be directional, the display portion <NUM> may not contain a waveguide or other similarly-related relay optics with reflective, curved surfaces.

<FIG> show another set of embodiments of the technique introduced here. In the embodiment of <FIG>, the display portion <NUM> contains one or more spatial mapping and localization sensors <NUM>, each of which can include one or more stereo cameras, time-of-flight cameras, depth cameras, and/or any other modules that can provide depth and/or mapping information. These sensors <NUM> may acquire, among other things, positional and/or orientational information of the display portion <NUM>. Also, this embodiment can contain eye-tracking modules, head-tracking modules, and/or other modules that provide or utilize information about the position of the user's head and/or gaze to adjust and/or calibrate the image or manipulate the rendered data. The output of these sensors <NUM> can be used for user interaction with the display or for adjusting the content based on the location of the display, for example. A more specific example is where the display is attached to a swiveling office chair (see, e.g., <FIG>), and when the user swivels the chair the content of the display changes digitally based on the localization data given by the sensors <NUM>. This provides a digital extension to the physical size of the display and can be used to put different digital files at different locations. Another example is where the light field provides 3D objects that can be interacted with by the viewer and where the sensors <NUM> can be used to capture and feed back information about the interaction to the display system, to determine the content that should be shown to the user.

In the embodiment of <FIG>, the display portion <NUM> (which can be similar to the display portion of other embodiments previously discussed above) is attached to a shoulder rest <NUM> by one or more rigid members <NUM> or similar objects. The shoulder rest <NUM> can be similar to, for example, shoulder straps commonly found in objects like backpacks. Also, the shoulder rest may contain the computer <NUM> (<FIG>) or another computer (not shown) to assist in rendering images. Alternatively, the shoulder rest <NUM> can contain a necklace-like object (not shown) that can house such computer(s).

In the embodiment of <FIG>, the display portion <NUM> (which can be similar to the display portion of other embodiments) can be contained within an eyewear-like structure <NUM>. The display portion <NUM> may contain a singular, continuous relay optics that runs from one end of the user's field of view to the opposite end of the user's field of view, or from one eye of the user to the other eye of the user. The three-dimensional perception may be provided by an autostereoscopic mechanism applied to a singular display.

In the embodiment of <FIG>, the display portion <NUM> (which can be similar to the display portion of other embodiments) can be attached to a tablet- or notebook-type computing device <NUM> by one or more rigid members, such that the display portion <NUM> can be stowed away into or against the tablet or notebook-like computing device <NUM>. In a variation upon this embodiment, shown in <FIG>, the content engine of the display can be included in a smart device <NUM>, such as a cellphone, a tablet, a portable screen panel, or other similar object.

<FIG> show another set of embodiments of the technique introduced here. In the embodiment of <FIG>, the base <NUM> of the stand <NUM> can be attached or mounted to a bed or other similar object, such that the user can be lying down while using the display system. In the embodiment of <FIG>, the stand <NUM> can be attached to or mounted to the headrest or backrest of a chair <NUM>, sofa, or other similar object, to allow the user to utilize the technique introduced here in the circumstance that there is not desk or table in which the base of the stand can be rested upon. In some embodiments, the display system can contain other sensors and/or mechanical actuators in which the chair's movements can be synchronized in conjugation with the image content displayed from the display portion, in a manner akin to amusement park rides. In a variation of the embodiment of <FIG>, shown in <FIG>, the display portion <NUM> can be worn on the user's face like eyeglasses while at the same type being supported by and/or suspended from the stand <NUM>.

<FIG> shows yet another embodiment, in which the display portion <NUM> includes wearable glasses <NUM> that the user wears. The wearable glasses <NUM> can be simple lenses. Alternatively, the wearable glasses <NUM> can include crossed polarized films over the lenses to provide three-dimensional content in conjugation with the screen that is encoding stereoscopic information into different polarizations. Or, the wearable glasses <NUM> can contain a plurality of lenses in series such that the depth of field can be increased so that the user's head can be moved nearer to and/or farther from the display portion without loss of optical focus.

Any or all of the features and functions described above can be combined with each other, except to the extent it may be otherwise stated above or to the extent that any such embodiments may be incompatible by virtue of their function or structure, as will be apparent to persons of ordinary skill in the art. Unless contrary to physical possibility, it is envisioned that (i) the methods/steps described herein may be performed in any sequence and/or in any combination, and that (ii) the components of respective embodiments may be combined in any manner.

Claim 1:
A display system comprising:
a display (<NUM>) arranged to emit or transmit light rays collectively forming a first image; and
an optical subsystem (<NUM>) optically coupled to the display (<NUM>) and arranged to configure the light rays from the display (<NUM>) into a single contiguous light field that forms a virtual image in a contiguous spatial region based on the first image and that simultaneously encompasses both eyes of a human viewer when the human viewer is viewing the virtual image, such that each eye of the human viewer can detect monocular depth of the display (<NUM>) anywhere within the contiguous spatial region, wherein the optical subsystem includes
a conjugate mirror (<NUM>) disposed proximate to the display (<NUM>) and partially forming an ellipse (<NUM>) that has two focal points (<NUM>, <NUM>), the conjugate mirror (<NUM>) being positioned within the display system such that when the human viewer is viewing the virtual image, the head of the human viewer is located at or near the focal point (<NUM>) of the ellipse that is closest to the conjugate mirror (<NUM>) between the two focal points (<NUM>, <NUM>) of the ellipse (<NUM>); and
a beamsplitter positioned in the field-of-view and oriented at an acute angle relative to an output surface of the display (<NUM>), the beamsplitter arranged to reflect the light rays from the display toward the conjugate mirror, such that the conjugate mirror reflects the light rays back toward the beamsplitter;
wherein the display (<NUM>) is positioned outside a field of view of the display system.