HK40031486A - Multibeam element-based head-up display, system, and method - Google Patents

Description

Head-up display, system and method based on multi-beam element

Cross Reference to Related Applications

Not applicable to

Statement regarding federally sponsored research or development

Not applicable to

Background

For users of a wide variety of devices and products, electronic displays are an almost ubiquitous medium for conveying information to users. The most common of these include Cathode Ray Tubes (CRTs), Plasma Display Panels (PDPs), Liquid Crystal Displays (LCDs), electroluminescent displays (ELs), Organic Light Emitting Diodes (OLEDs), and active matrix OLED (amoled) displays, electrophoretic displays (EPs), and various displays employing electromechanical or electrofluidic light modulation (e.g., digital micromirror devices, electrowetting displays, etc.). In general, electronic displays may be classified as either active displays (i.e., displays that will emit light) or passive displays (i.e., displays that modulate light provided by another light source). Among the categories of active displays, the most obvious examples are CRT, PDP, and OLED/AMOLED. In the case of the consideration of the emitted light, LCD and EP displays are generally classified as passive displays. Passive displays, while often exhibiting attractive performance characteristics including, but not limited to, inherent low power consumption, may have limited use in many practical applications due to their lack of ability to emit light.

A heads-up display is an electronic display that displays images or more generally information in a simultaneously viewable manner while viewing the physical environment outside of the heads-up display. Specifically, the heads-up display creates a combined view, superimposing an image generated by the heads-up display with the view of the physical environment. Further, the user may view the heads-up display in a so-called "heads-up" configuration (e.g., without having to look down or away from the physical environment view). In many applications, various heads-up displays and head-up display systems may provide a more immersive experience than traditional displays.

Drawings

Various features of examples and embodiments in accordance with the principles described herein may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals identify like structural elements, and in which:

fig. 1A is a perspective view illustrating a multi-view display in an example, according to an embodiment consistent with principles described herein.

Fig. 1B is a schematic diagram illustrating angular components of light beams having principal angular directions of a multi-view display in an example, according to an embodiment consistent with the principles described herein.

Figure 2 is a cross-sectional view illustrating a diffraction grating in an example, according to an embodiment consistent with the principles described herein.

Fig. 3 is a block diagram illustrating a heads-up display in an example, according to an embodiment consistent with the principles described herein.

Fig. 4A is a cross-sectional view illustrating an example of a multibeam element-based display in an example, according to an embodiment consistent with the principles described herein.

Fig. 4B is a plan view illustrating a multibeam element-based display in an example, according to an embodiment consistent with the principles described herein.

Fig. 4C is a perspective view illustrating a multibeam element-based display in an example, according to an embodiment consistent with the principles described herein.

Fig. 5A is a cross-sectional view illustrating a portion of a multibeam element-based display including a multibeam element in an example, according to an embodiment consistent with the principles described herein.

Fig. 5B is a cross-sectional view illustrating a portion of a multibeam element-based display including a multibeam element in an example, according to an embodiment consistent with the principles described herein.

Figure 6A is a cross-sectional view illustrating a diffraction grating including a plurality of sub-gratings in an example, according to an embodiment consistent with the principles described herein.

Figure 6B is a plan view illustrating the diffraction grating of figure 6A in an example, according to an embodiment consistent with the principles described herein.

FIG. 7 is a plan view illustrating a pair of multibeam elements in an example, according to an embodiment consistent with principles described herein.

Fig. 8A is a cross-sectional view illustrating a portion of a multi-beam display including a multi-beam element in an example, according to another embodiment consistent with the principles described herein.

Fig. 8B is a cross-sectional view illustrating a portion of a multibeam element-based display including a multibeam element in an example, according to an embodiment consistent with the principles described herein.

FIG. 9 is a cross-sectional view illustrating a portion of a multibeam element-based display including a multibeam element in an example, according to an embodiment consistent with the principles described herein.

Fig. 10 is a cross-sectional view illustrating an optical combiner in an example, according to an embodiment consistent with the principles described herein.

FIG. 11 is a schematic diagram illustrating an exemplary automotive heads-up display according to an embodiment consistent with the principles described herein.

Fig. 12 is a block diagram illustrating a multi-view heads-up display system in an example, according to an embodiment consistent with the principles described herein.

Fig. 13 is a flow chart illustrating a method of operation of a heads-up display in an example, according to an embodiment consistent with the principles described herein.

Some examples and embodiments have other features in addition to, or instead of, those shown in the above-referenced figures. These and other features will be described in detail below with reference to the above-identified figures.

Detailed Description

According to embodiments and examples described herein, a heads-up image display is provided. In particular, according to various embodiments of the principles described herein, the present invention provides a heads-up display employing a multi-beam element based display to produce a plurality of different views of a multi-view image. A plurality of different views are projected or arranged into a viewing frame (eye box) where the multi-view image is viewed. In addition, the heads-up display provides a view of the physical environment and an overlay of multi-view images including different views. According to various embodiments, the different views may contain different perspective views of a three-dimensional (3D) scene or similar content. For example, different views of a multi-view image may enable a user to perceive elements within the multi-view image that are located at different depths of view (apparent depths) in the physical environment to assist the user in looking around.

In this context, a "two-dimensional display" or "2D display" is defined as a display to provide an image whose view is substantially the same regardless of the direction from which the image is viewed (i.e., within a predetermined viewing angle or 2D display range). Liquid Crystal Displays (LCDs) that may be found in smart phones and computer screens are examples of 2D displays. In contrast, a "multi-view display" is defined as an electronic display or display system configured to provide different views (differentiatviews) of a multi-view image in or from different view directions. In particular, the different views may represent different perspective views of a scene or object of the multi-view image. In some cases, a multiview display may also be referred to as a three-dimensional (3D) display, e.g., providing the sensation of viewing a three-dimensional image when two different views of the multiview image are viewed simultaneously.

Fig. 1A illustrates a perspective view of a multi-view display 10 in an example, according to an embodiment consistent with principles described herein. As shown in fig. 1A, the multi-view display 10 includes a screen 12 for displaying or providing a multi-view image to be viewed. The multi-view display 10 provides different views 14 of the multi-view image in different view directions 16 relative to the screen 12. The view direction 16 extends from the screen 12 in various principal angular directions, as indicated by the arrows. The different views 14 are displayed as shaded polygonal boxes at the end of the arrows (i.e., representing the view directions 16), and only four views 14 and four view directions 16 are shown, all by way of example and not limitation. Note that although the different views 14 are shown above the screen in fig. 1A, when a multi-view image is displayed on the multi-view display 10, the views 14 actually appear on or near the screen. The depiction of the views 14 above the screen 12 is merely for simplicity of illustration and is intended to represent viewing of the multi-view display 10 from a respective one of the view directions 16 corresponding to a particular view 14.

A view direction, or equivalently a light beam having a direction corresponding to the view direction of a multi-view display, generally has a principal angular direction given by the angular components theta, phi, according to the definition herein. The angular component θ is referred to herein as the "elevation component" or "elevation angle" of the light beam. The angular component φ is referred to as the "azimuth component" or "azimuth" of the beam. By definition, the elevation angle θ is an angle in a vertical plane (e.g., perpendicular to the screen plane of the multiview display) and the azimuth angle is an angle in a horizontal plane (e.g., parallel to the screen plane of the multiview display).

FIG. 1B is a schematic diagram illustrating, in an example, angular components { θ, φ } of a light beam 20 having a particular principal angular direction, or simply "direction," corresponding to a view direction (e.g., view direction 16 in FIG. 1A) of a multi-view display, according to an embodiment consistent with the principles described herein. Further, the light beam 20 is emitted or emitted from a particular point, as defined herein. That is, by definition, the light beam 20 has a central ray associated with a particular origin within the multi-view display. Fig. 1B also shows the beam (or view direction) at the origin O.

Further, in this document, the term "multi-view" as used in the terms "multi-view image" and "multi-view display" is defined as multiple views representing different views or containing angular differences of the views between views among the multiple views. In addition, as defined herein, the term "multi-view" herein expressly encompasses more than two different views (i.e., a minimum of three views and often more than three views). As such, the term "multi-view display" as used herein is clearly distinguished from stereoscopic displays that only include two different views representing a scene or image. It should be noted that although the multi-view image and the multi-view display may contain more than two views, the multi-view image may be viewed on the multi-view display as a stereoscopic image pair (e.g., one view per eye) by selecting only two of the multi-views at a time, as defined herein.

The term "multi-view pixel" is defined, as defined herein, as a group of sub-pixels or a group of "view" pixels in each of a similar plurality of different views of a multi-view display. In particular, the multi-view pixels may have individual view pixels that correspond to or represent view pixels in each of the plurality of different views in the multi-view image. Furthermore, the view pixels of a multi-view pixel are, by definition herein, so-called "directional" pixels, in that each view pixel is associated with a predetermined view direction of a respective one of the different views. Furthermore, according to various examples and embodiments, different view pixels of a multiview pixel may have identical or at least substantially similar positions or coordinates in each different view. For example, a first multi-view pixel may have an individual view pixel located at { x1, y1} in each different view of the multi-view image; while the second multi-view pixel may have an individual view pixel located at x2, y2 in each different view of the multi-view image, and so on.

In some embodiments, the number of view pixels in a multi-view pixel may be equal to the number of different views of the multi-view display. For example, the multi-view pixel may provide sixty-four (64) view pixels, the sixty-four (64) view pixels being associated with a multi-view display having sixty-four (64) different views. In another example, the multiview display may provide an eight by four array of views (i.e., 32 views), and the multiview pixels may include 32 view pixels (i.e., one for each view). Further, for example, each of the different view pixels may include an associated direction (e.g., a beam direction) corresponding to a different view direction of a plurality of view directions corresponding to 64 different views. Further, according to some embodiments, the number of multiview pixels of the multiview display may be substantially equal to the number of pixels of the multiview display (i.e. the pixels constituting the selected view). For example, if a view contains six hundred forty by four hundred eighty view pixels (i.e., a view resolution of 640x 480), a multiview display may have thirty-zero seven thousand two hundred (307,200) multiview pixels. In another example, when a view includes one hundred by one hundred pixels, a multiview display may include a total of ten thousand (i.e., 100x100 ═ 10,000) multiview pixels.

Herein, a "light guide" is defined as a structure that guides light within the structure using total internal reflection or "TIR". In particular, the light guide may comprise a core that is substantially transparent at the operating wavelength of the light guide. In various examples, the term "light guide" generally refers to a dielectric optical waveguide that utilizes total internal reflection to guide light at an interface between a substance of the dielectric material of the light guide and a substance or medium surrounding the light guide. By definition, the condition for total internal reflection is that the refractive index of the light guide is greater than the refractive index of the surrounding medium adjacent to the surface of the light guide material. In some embodiments, the light guide may include a coating in addition to, or in place of, the aforementioned refractive index difference, thereby further contributing to total internal reflection. For example, the coating may be a reflective coating. The light guide may be any of several light guides including, but not limited to, one or both of a flat plate (plate) or slab (slab) light guide and a strip light guide.

Further, in the present disclosure, the term "slab," as applied to light guides, such as a "slab light guide," is defined as a layer or sheet of piecewise linear or differential ground plane (differential planar), which is sometimes referred to as a "slab" light guide. In particular, a flat-panel light guide is defined as a light guide configured to guide light in two substantially orthogonal directions bounded by a top surface and a bottom surface (i.e., opposing surfaces) of the light guide. Further, by definition herein, the top and bottom surfaces are both separate from each other and may be substantially parallel to each other in at least a differential sense. That is, within any differentially small portion of the flat-panel light guide, the top and bottom surfaces are substantially parallel or coplanar.

In some embodiments, the plate light guide may be substantially flat (i.e., confined to a plane), and thus the plate light guide is a planar light guide. In other embodiments, the flat panel light guide may be curved in one or two orthogonal dimensions. For example, a flat-panel light guide may be bent in a single dimension to form a cylindrical flat-panel light guide. However, any curvature has a radius of curvature large enough to ensure that total internal reflection is maintained within the plate-type light guide to guide the light.

Herein, a "conformal scattering feature" or equivalent "conformal diffuser" is any feature or diffuser configured to scatter light in a manner that substantially preserves the angular spread (angular spread) of light incident on the feature or diffuser in the scattered light. More specifically, by definition, the angular spread σ of the light scattered by the conformal scattering feature_sIs a function of the angular spread σ of the incident light (i.e., σ)_sF (σ)). In some embodiments, the angular spread σ of the scattered light_sIs a linear function of the angular spread or collimation factor σ of the incident light (e.g., σ_sA · σ, where a is an integer). That is, the angular spread σ of the light scattered by the conformal scattering feature_sMay be substantially proportional to the angular spread or collimation factor sigma of the incident light. For example, the angular spread σ of the scattered light_sMay be substantially equal to the angular spread σ (e.g., σ) of the incident light_sσ). A uniform diffraction grating (i.e., a diffraction grating having a substantially uniform or constant diffraction feature pitch or grating pitch) is an example of a conformal scattering feature. In contrast, Lambertian diffusers or Lambertian reflectors, as well as diffusers in general (e.g., with or approximating Lambertian scattering), are not conformal diffusers, as defined herein.

As used herein, a "polarization-preserving scattering feature" or, equivalently, a "polarization-preserving diffuser" is any feature or diffuser configured to scatter light in a manner that substantially preserves the polarization, or at least the degree of polarization, of light incident on the feature or diffuser in the scattered light. Thus, a "polarization-preserving scattering feature" is any feature or scatterer for which the degree of polarization of light incident on the feature or scatterer is substantially equal to the degree of polarization of the scattered light. Further, by definition, "polarization preserving scattering" refers to scattering (e.g., of guided light) that preserves or substantially preserves a predetermined polarization of scattered light. For example, the scattered light may be polarized light provided by a polarized light source.

Herein, a "diffraction grating" is generally defined as a plurality of features (i.e., diffractive features) arranged to provide diffraction of light incident on the diffraction grating. In some examples, the plurality of features may be arranged in a periodic or quasi-periodic manner. For example, a diffraction grating may comprise a plurality of features (e.g., a plurality of grooves or ridges in the surface of a material) arranged in a one-dimensional (1D) array. In other examples, the diffraction grating may be a two-dimensional (2D) array of features. For example, the diffraction grating may be a two-dimensional array of protrusions on or holes in the surface of the material.

Thus, a "diffraction grating" is a structure that provides diffraction of light incident on the diffraction grating, according to the definitions herein. If light is incident from the light guide on the diffraction grating, the provided diffraction or diffractively scattering may result in and is therefore referred to as "diffractively coupled in" because the diffraction grating may couple light out of the light guide by diffraction. Diffraction gratings also redirect or change the angle of light by diffraction (i.e., at a diffraction angle). In particular, due to diffraction, light exiting a diffraction grating typically has a propagation direction that is different from the propagation direction of light incident on the diffraction grating (i.e., incident light). The change in the direction of propagation of light by diffraction is referred to herein as "diffractive redirection". A diffraction grating may thus be understood as a structure comprising diffractive features which redirect light incident on the diffraction grating via diffraction and which may also diffractively couple out light from the light guide if the light is emitted by the light guide.

Further, the features of a diffraction grating are referred to as "diffractive features" according to the definitions herein and may be one or more of at, in, and on the surface of a material (i.e., the boundary between two materials). For example, the surface may be a surface of a light guide. The diffractive features may comprise any of a variety of structures that diffract light, including, but not limited to, one or more of grooves, ridges, holes, and protrusions at, in, or on the surface. For example, the diffraction grating may comprise a plurality of substantially parallel grooves in the surface of the material. In another example, the diffraction grating may comprise a plurality of parallel ridges protruding from the surface of the material. The diffractive features (e.g., grooves, ridges, apertures, protrusions, etc.) can have any of a variety of cross-sectional shapes or profiles that provide diffraction, including but not limited to sinusoidal profiles, rectangular profiles (e.g., binary diffraction gratings), triangular profiles, and sawtooth profiles (e.g., blazed gratings).

According to various examples described herein, light may be diffractively scattered or coupled into a light beam from a light guide (e.g., a flat-panel light guide) using a diffraction grating (e.g., of a multibeam element, as described below). In particular, the diffraction angle θ of the locally periodic diffraction grating_mOr the diffraction angle provided by a locally periodic diffraction grating can be given by equation (1):

where λ is the wavelength of the light, m is the diffraction order, n is the refractive index of the light guide, d is the spacing or pitch between the features of the diffraction grating, and θ_iIs the angle of incidence of the light on the diffraction grating. For simplicity, equation (1) assumes that the diffraction grating is adjacent to a surface of the light guide and that the refractive index of the material outside the light guide is equal to 1 (i.e., n)_out1). Typically, the diffraction order m is given as an integer. Diffraction angle theta_mThe beam produced by the diffraction grating may have a diffraction order therein that is positive (e.g., m)>0) Equation (1) of (a). For example, first order diffraction is provided when the diffraction order m is equal to 1 (i.e., m is 1).

Figure 2 is a cross-sectional view illustrating a diffraction grating 30 in an example, according to an embodiment consistent with the principles described herein. For example, the diffraction grating 30 may be located on a surface of the light guide 40. In addition, FIG. 2 shows the angle of incidence θ_iAn incident beam 50 incident on the diffraction grating 30. Incident light beam 50 may be a guided light (i.e., a guided light beam) within light guide 40. Also shown in fig. 2 is that diffraction grating 30 diffractively generates and couples out directional beam 60 due to diffraction of incident beam 50. The directional beam 60 has a diffraction angle θ as shown in equation (1)_m(or, in this context, "principal angular direction"). Diffraction angle theta_mMay correspond to the diffraction order "m" of the diffraction grating 30, e.g., m ═ m1 (i.e., the first diffraction order).

A "multibeam element" is, as defined herein, a structure or element of a backlight or display that generates light comprising a plurality of light beams. In some embodiments, the multi-beam element may be optically coupled to a light guide of the backlight panel to provide a plurality of light beams by coupling out or scattering out a portion of the light guided in the light guide. Further, the beams of the plurality of beams produced by the multibeam element have a plurality of principal angular directions different from each other, according to the definitions herein. In particular, by definition, a light beam of the plurality of light beams has a predetermined principal angular direction different from another light beam of said plurality of light beams. Thus, a light beam is referred to as a "directional light beam" and multiple light beams may be referred to as multiple directional light beams, as defined herein.

Further, the plurality of directional light beams may represent a light field. For example, the plurality of directional light beams may be confined in a substantially conical spatial area or have a predetermined angular spread comprising different principal angular directions of the light beams of the plurality of light beams. Thus, a combination of the predetermined angular spread of the plurality of light beams (i.e. the plurality of light beams) may represent a light field.

According to various embodiments, the different principal angular directions of the various directional beams of the plurality of directional beams are determined according to characteristics, including but not limited to, the size (e.g., length, width, area, etc.) of the multibeam element. In some embodiments, the multi-beam element may be considered an "extended point light source," i.e., a plurality of point light sources distributed within the extent of the multi-beam element, according to the definitions herein. Furthermore, the directional beams of light produced by the multibeam element have a principal angular direction given by the angular components { θ, φ }, as defined herein, and as described above with respect to FIG. 1B.

In this context, a "collimator" is defined as essentially any optical device or means for collimating light. By way of example, the collimator may include, but is not limited to, a collimating mirror or reflector, a collimating lens, a diffraction grating, a tapered light guide, and combinations of the various collimators described above. According to various embodiments, the amount of collimation provided by the collimator may vary from one embodiment to another by a predetermined angle or amount. Further, the collimator may be configured to provide collimation in one or both of two orthogonal directions (e.g., a vertical direction and a horizontal direction). In other words, according to some embodiments of the invention, the collimator may comprise a shape or similar collimating feature for providing one or both of the two orthogonal directions of light collimation.

Herein, the "collimation factor" is defined as the degree to which light is collimated. In particular, the collimation factor defines the angular spread of the rays in the collimated beam. For example, the collimation factor σ may specify that a majority of rays in a beam of collimated light are within a particular angular spread (e.g., +/- σ degrees with respect to the central or principal angular direction of the collimated beam). According to some examples, the rays of the collimated light beam may have a Gaussian distribution (Gaussian distribution) in angle, and the angular spread may be an angle determined by half of the peak intensity of the collimated light beam.

Herein, a "light source" is defined as a source that emits light (e.g., an optical emitter configured to generate light and emit light). For example, the light source may include an optical emitter, such as a Light Emitting Diode (LED), that emits light when activated or turned on. Specifically, a light source herein can be substantially any source of light or optical emitter including, but not limited to, one or more LEDs, lasers, Organic Light Emitting Diodes (OLEDs), polymer light emitting diodes, plasma optical emitters, fluorescent lamps, incandescent lamps, and any other source of visually-visible light. The light generated by the light source may be of a color (i.e., may include light of a particular wavelength), or may be a range of wavelengths (e.g., white light). In some embodiments, the light source may include a plurality of optical emitters. For example, the light source may comprise a group or cluster of optical emitters, wherein at least one optical emitter produces light having a color or equivalent wavelength that is different from the color or wavelength of light produced by at least one other optical emitter of the group or cluster. The different colors may comprise, for example, primary colors (e.g., red, green, blue). A "polarized" light source is defined herein as essentially any light source that produces or provides light having a predetermined polarization. For example, the polarized light source may include a polarizer at the output of the optical emitter of the light source.

The term "accommodation" used in the present specification refers to a process of focusing on an object or an image element by changing the optical energy of the eye. In other words, accommodation refers to the ability of the eye to focus. Herein, a "range of accommodation" or equivalently "accommodation distance" is a range defined as a distance from the eye in which focusing can be achieved. Although the range of accommodation may vary from individual to individual, for example, for simplicity and not limitation, the minimum "normal" accommodation distance is set to be approximately equal to 25 centimeters. Thus, when an object is in the so-called "normal range of accommodation," it is generally understood that the object is located more than 25 centimeters away from the eye.

Herein, "eyebox" refers to an area or space where a user can view an image formed by a display or other optical system (e.g., a lens system). In other words, the viewing frame defines the position in space where the user's eyes are suitably positioned for viewing the image produced by the display system. In some embodiments, the frame represents a two-dimensional region of space (e.g., a region having a length and a width but no actual depth), while in other embodiments the frame may encompass a three-dimensional region of space (e.g., a region having a length, a width, and a depth). Furthermore, when reference is made herein to a "box," the view box is not limited to a rectangular area. For example, in some embodiments, the view frame may be a cylindrical spatial region.

Further, as used herein, the articles "a" and "an" are intended to have their ordinary meaning in the patent arts, i.e., "one or more". For example, "multibeam element" refers to one or more multibeam elements, more specifically, "multibeam element" means "the multibeam element(s)" herein. Further, references herein to "top," "bottom," "upper," "lower," "upward," "downward," "front," "rear," "first," "second," "left," or "right" are not meant to be limiting. As used herein, the term "about" when applied to a value generally means within the tolerance of the equipment used to produce the value, or may mean plus or minus 10%, or plus or minus 5%, or plus or minus 1%, unless specifically stated otherwise. Further, the term "substantially" as used herein refers to an amount that is mostly, or almost entirely, or in the range of about 51% to about 100%. Moreover, the examples herein are merely illustrative and are for purposes of discussion and not limitation.

According to some embodiments consistent with principles described herein, the present invention provides a heads up display. Fig. 3 is a block diagram illustrating an exemplary heads-up display 100 according to an embodiment consistent with the principles described herein. The heads-up display 100 is configured to provide an image (i.e., a displayed image) at a viewing frame 102 of the heads-up display 100. In particular, the heads-up display 100 may be used to provide a multi-view image comprising a plurality of different views 104, each view having a respective view direction.

In some embodiments, different views 104 of the multi-view image may be provided at different locations within the view frame 102. The different views 104 provided at different locations in the view box 102 are configured to provide depth of focus cues to a user of the heads-up display 100. For example, the depth of focus cue may enable a user to perceive the depth or distance of the displayed image based on the depth of focus cue. The depth of focus cues provided to the user by heads-up display 100 may include, but are not limited to, a pan and a retinal blur.

As shown in fig. 3, heads-up display 100 includes a multibeam element-based display 110. The multi-beam element based display 110 is used to provide a plurality of different views 104 of the displayed multi-view image. According to various embodiments, substantially any number of views may be provided as the plurality of different views 104. For example, the number of different views 104 of the displayed image may include two, three, four, five, six, seven, eight, or more different views. In other examples, the plurality of different views 104 of the displayed image includes a relatively large number of different views, which may include sixteen (16), thirty-two (32), sixty-four (64), one-hundred twenty-eight (128), or two-hundred fifty-six (256) different views, but the number of different views is not so limited. In some embodiments, the plurality of different views 104 includes at least four different views.

In some examples, the multi-view images provided or displayed by heads-up display 100 include only three-dimensional (3D) information or content (e.g., 3D images representing 3D objects or scenes). In other examples, the multi-view image may contain a portion that provides 3D content and a portion that contains two-dimensional (2D) information or content (e.g., a 2D image portion). When the multi-view image comprises 3D content or equivalently a "3D image", the plurality of different views 104 may represent different perspective views of the 3D image. In accordance with the principles described herein, the different views may enhance the user's perception of depth of field in the displayed image, for example, by way of one or both of accommodation or retinal blur. Furthermore, according to some embodiments, heads-up display 100 may be an autostereoscopic (autostereoscopic) or "holographic" multiview display (i.e., a so-called "glasses-free" 3D or multiview display).

According to various embodiments, the multibeam element based display 110 of the heads-up display 100 includes an array of multibeam elements. The multi-beam element array is configured to provide a plurality of directional light beams having directions corresponding to respective view directions of a plurality of different views of the multi-view image. According to various embodiments, the multibeam element based display 110 of the heads-up display 100 further comprises a light valve array configured to modulate the plurality of directional light beams to provide the multi-view image.

Fig. 4A is a cross-sectional view illustrating an example multibeam element-based display 110, according to an embodiment consistent with the principles described herein. Fig. 4B is a plan view illustrating an example multibeam element-based display 110, according to an embodiment consistent with the principles described herein. Fig. 4C is a perspective view illustrating an example multibeam element-based display 110, according to an embodiment consistent with the principles described herein. The perspective view in fig. 4C is shown partially cut away to facilitate discussion herein only.

The multi-beam element based display 110 shown in fig. 4A-4C is used to provide a plurality of directional light beams 111 (e.g., light fields) having different principal angular directions from each other. In particular, according to various embodiments, the provided plurality of directional light beams 111 are directed away from the multibeam element based display 110 in different principal angular directions corresponding to various view directions of the plurality of different views 104. Further, the directional beam 111 is modulated (e.g., using a light valve, as described below) to provide or display a multi-view image. In some embodiments, the multi-view image may contain 3D content (e.g., virtual objects are represented in different perspective views that would render the 3D object when viewed by the user).

As shown in fig. 4A-4C, the multibeam element-based display 110 includes a light guide 112. According to some embodiments, the light guide 112 may be a flat plate light guide. The light guide 112 is configured to guide light along a length of the light guide 112 as guided light 113. For example, the light guide 112 may comprise a dielectric material configured as an optical waveguide. The dielectric material may have a first refractive index that is greater than a second refractive index of a medium of the optical waveguide surrounding the dielectric. For example, the difference in refractive index is configured to contribute to total internal reflection of the guided light 113 according to one or more guiding modes of the light guide 112.

In particular, the light guide 112 may be a slab or slab optical waveguide that includes an extended, substantially flat sheet of optically transparent dielectric material. The generally planar sheet-like dielectric material guides the guided light 113 by total internal reflection. According to various examples, the optically transparent material in the light guide 112 can comprise any of a variety of dielectric materials, which can include, but are not limited to, one or more of various forms of glass (e.g., quartz glass, alkali-aluminosilicate glass, borosilicate glass, etc.) and substantially optically transparent plastics or polymers (e.g., poly (methyl methacrylate) or "acrylic glass", polycarbonate, etc.). In some examples, the light guide 112 can also include a cladding layer (not shown) on at least a portion of a surface (e.g., one or both of the top and bottom surfaces) of the light guide 112. According to some examples, cladding layers may be used to further contribute to total internal reflection.

Further, according to some embodiments, the light guide 112 is configured to guide the guided light 113 according to total internal reflection between a first surface 112' (e.g., a "front" surface or side) and a second surface 112 "(e.g., a" back "surface or side) of the light guide 112 over a non-zero propagation angle. In particular, the guided light 113 is guided by reflecting or "bouncing" between the first surface 112' and the second surface 112 "of the light guide 112 at a non-zero propagation angle. In some embodiments, the directed light 113 includes a plurality of directed light beams of different light colors. Light beams of the plurality of guided light beams may be guided by the light guide 112 at respective ones of the different color-specific non-zero propagation angles. It should be noted that the non-zero propagation angle is not shown for simplicity of illustration. However, the thick arrows depicting the conduction direction 115 show the overall conduction direction of the guided light 113, which is along the length of the light guide in fig. 4A.

As defined herein, a "non-zero propagation angle" is an angle relative to a surface of the light guide 112 (e.g., the first surface 112' or the second surface 112 "). Further, according to various embodiments, the non-zero propagation angles are each greater than zero and less than the critical angle for total internal reflection within the light guide 112. For example, the non-zero propagation angle of the guided light 113 may be between about ten (10) degrees and about fifty (50) degrees, or in some examples, between about twenty (20) degrees and about forty (40) degrees, or between about twenty-five (25) degrees and about thirty-five (35) degrees. For example, the non-zero propagation angle may be about thirty (30) degrees. In other examples, the non-zero propagation angle may be about 20 degrees, or about 25 degrees, or about 35 degrees. Further, for particular implementations, a particular non-zero propagation angle may be selected (e.g., arbitrary), as long as the particular non-zero propagation angle is selected to be less than the critical angle for total internal reflection within the light guide 112.

Guided light 113 in the light guide 112 may be introduced or coupled into the light guide 112 at a non-zero propagation angle (e.g., about 30-35 degrees). For example, one or more lenses, mirrors, or similar reflectors (e.g., tilted collimating reflectors), diffraction gratings, and prisms (not shown) may cause light to be coupled into the input end of the light guide 112 at a non-zero propagation angle to become the guided light 113. Once coupled into the light guide 112, the guided light 113 is guided along the light guide 112 in a direction that may be generally away from the input end (e.g., shown in fig. 4A with a bold arrow pointing toward the x-axis).

Further, according to various embodiments, the guided light 113, or equivalently the guided light beam 113, produced by coupling light into the light guide 112 may be a collimated light beam. In the present disclosure, "collimated light" or "collimated light beam" is generally defined as a beam of light in which several beams of light are substantially parallel to each other within the beam (e.g., within the guided light 113). Further, light rays that diverge or scatter from the collimated beam are not considered part of the collimated beam, as defined herein. In some embodiments, the multibeam element-based display 110 may include a collimator, such as, but not limited to, a lens, reflector or mirror, a diffraction grating, or a tapered light guide, to collimate light, such as to collimate light from a light source. In some embodiments, the light source comprises a collimator. The collimated light provided to the light guide 112 is collimated guided light 113. In various embodiments, the guided light 113 may be collimated according to a collimation factor σ, or the guided light 113 may have both a collimation factor σ.

In some embodiments, the light guide 112 may be configured to "recycle" the guided light 113. In particular, guided light 113 guided along the length of the light guide may be redirected back along another conduction direction 115' different from the conduction direction 115. For example, the light guide 112 may include a reflector (not shown) at an end of the light guide 112 opposite the input end adjacent the light source. The reflector may be configured to reflect the guided light 113 back to the input end as recycled guided light. Recycling the guided light 113 in this manner increases the brightness (e.g., the intensity of the directional light beam 111) of the multibeam element-based display 110 by having the guided light provided more than once, e.g., to the multibeam element, as described below.

In fig. 4A, a thick arrow (e.g., pointing in the negative x-direction) showing the direction of propagation 115' of the recycled guided light shows the general direction of propagation of the recycled guided light within the light guide 112. Alternatively (e.g. as opposed to recycling guided light), guided light 113 guided in another direction of propagation 115 'may be provided by introducing light into the light guide 112 in another direction of propagation 115' (e.g. in addition to guided light 113 having a direction of propagation 115).

As shown in fig. 4A-4C, the multibeam element based display 110 further includes a plurality of multibeam elements 114 or an array of multibeam elements 114 spaced apart from each other along the length of the light guide 110. In particular, the multibeam elements 114 in the array of multibeam elements 114 (or array of multibeam elements) are separated from each other by a finite space, and represent separate, distinct elements along the length of the light guide. Thus, the multibeam elements 114 in the multibeam element array are spaced apart from one another according to a finite (i.e., non-zero value) inter-element distance (e.g., a finite center-to-center distance), as defined herein. Further, the multibeam elements 114 in the array of multibeam elements generally do not intersect, overlap, or contact each other, according to some embodiments. Thus, each multi-beam element 114 in the array of multi-beam elements is generally distinct and separate from other multi-beam elements 114 in the plurality of multi-beam elements 114.

According to some embodiments, the multibeam elements 114 of the multibeam element array may be arranged in a one-dimensional (1D) array or a two-dimensional (2D) array. For example, the array of multibeam elements 114 may be arranged in a linear 1D array. In another example, the array of multibeam elements 114 may be arranged in a rectangular 2D array or a circular 2D array. Further, in some examples, the array (i.e., 1D or 2D array) may be a conventional or unified array. In particular, the inter-element distance (e.g., center-to-center distance or pitch) between the plurality of multibeam elements 114 may be substantially uniform or constant across the array. In other examples, the inter-element distance between the plurality of multibeam elements 114 may vary to one or both of across the array and along the length of the light guide 112.

According to various embodiments, the multibeam elements 114 in the multibeam element array are to couple or scatter a portion of the guided light 113 into the plurality of directional light beams 111. In particular, fig. 4A and 4C show the directional light beam 111 as a plurality of diverging arrows, depicted as being directed away from a first surface (or front surface) 112' of the light guide 112. Further, according to various embodiments, the size of the multibeam element 114 is comparable to (compatible) the size of the view pixels (or equivalently, the size of the light valves 116 as described below) in the multiview pixels of the multibeam element based display 110.

As used herein, "dimension" may be defined in any of a variety of ways including, but not limited to, length, width, or area. For example, the size of a view pixel may be its length, and a comparable size of the multibeam element 114 may also be the length of the multibeam element 114. In another example, the dimensions may refer to areas such that the area of the multibeam element 114 may be comparable to the area of the view pixel.

In some embodiments, the size of the multibeam element 114 may be comparable to the size of a view pixel, and the size of the multibeam element is between fifty percent (50%) to two hundred percent (200%) of the size of the view pixel. For example, if the size of the multibeam element is denoted as "S" and the size of the view pixel is denoted as "S" (as shown in fig. 4A), the size of the multibeam element S can be given by equation (2), equation (2) being:

in other examples, the size of the multibeam element is greater than about sixty percent (60%), or about seventy percent (70%), or greater than about eighty percent (80%), or greater than about ninety percent (90%) of the size of the view pixel, and the multibeam element is less than about one hundred eighty percent (180%), or less than about one hundred sixty percent (160%), or less than about one hundred forty percent (140%), or less than about one hundred twenty percent (114%) of the size of the view pixel. For example, with "comparable dimensions," the size of the multibeam element may be between about seventy-five percent (75%) and about one hundred fifty percent (150%) of the size of the view pixel. In another example, the multibeam element 114 may be comparable in size to a view pixel, where the size of the multibeam element is between approximately one hundred twenty five percent (125%) to eighty five percent (85%) of the size of the view pixel. According to some embodiments, the comparable sizes of the multibeam element 114 and the view pixels (or light valves 116) may be selected with the goal of reducing, or in some examples minimizing, dark regions between views of the multiview image, while the overlap between different views of the multiview display may be reduced, or in some examples minimized.

As shown in fig. 4A-4C, the multibeam element-based display 110 further includes an array of light valves 116. The array of light valves 116 is used to modulate the directional light beam 111 of the plurality of directional light beams. In particular, the light valve array may be configured to modulate the directional light beams 111 into an image, such as a multi-view image, for display by the multi-beam element based display 110. In fig. 4C, the array of light valves 116 is partially cut away to allow visualization of the light guide 112 and the multibeam element 114 below the light valve array.

Further, different ones of the directional light beams 111 having different principal angular directions are configured to pass through different ones of the light valves 116 in the light valve array and thus be modulated by the different ones of the light valves 116. Further, as shown, the pairs of light valves 116 in the array correspond to view pixels, and a group of light valves 116 in the array of light valves correspond to multi-view pixels of the multibeam element-based display 110. Specifically, a set of different light valves 116 in the light valve array is used to receive and modulate the directional light beams 111 from different ones of the different multibeam elements 114. Thus, as shown, each multibeam element 114 has a unique set of light valves 116. In various embodiments, any of a variety of light valves may be used as the plurality of light valves 116 of the light valve array, including, but not limited to, one or more of a plurality of liquid crystal light valves, a plurality of electrophoretic light valves, and a plurality of light valves based on or using electrowetting.

As shown, FIG. 4A shows a first set of valves 116-1 configured to receive and modulate directional beams 111 from a first multibeam element 114-1, while a second set of valves 116-2 is configured to receive and modulate directional beams 111 from a second multibeam element 114-2. Thus, as shown in fig. 4A, each of the plurality of groups of light valves in the light valve array (e.g., the first and second groups of light valves 116-1 and 116-2) respectively corresponds to a different multiview pixel, wherein individual light valves 116 of the plurality of groups of light valves correspond to view pixels of the respective multiview pixel.

It should be noted that in fig. 4A, the size of the view pixels may correspond to the actual size of the light valves 116 in the light valve array. In other examples, the size of a view pixel or an equivalent light valve size may be defined as the distance (e.g., center-to-center distance) between adjacent light valves 116 in the light valve array. For example, the light valves 116 may be smaller than a center-to-center distance between a plurality of light valves 116 in the array of light valves. For example, the size of the view pixel or the light valve size may be defined as the size of the light valve 116 or a size corresponding to a center-to-center distance between the plurality of light valves 116.

In some embodiments, the relationship between the multibeam elements 114 in the multibeam element array and the corresponding multiview pixels (e.g., the set of light valves 116) may be a one-to-one relationship. That is, there may be the same number of multiview pixels and multibeam elements 114. Fig. 4B explicitly illustrates, by way of example, a one-to-one relationship in which each multi-view pixel, including a different set of light valves 116, is delineated by a dashed line enclosure. In other embodiments (not shown), the number of multiview pixels and the number of multiple beam elements 114 may be different from each other.

In some embodiments, an inter-element distance (e.g., center-to-center distance) between adjacent pairs of the multibeam elements 114 in the multibeam element array may be equal to an inter-pixel distance (e.g., center-to-center distance) between adjacent pairs of the multiview pixels in the corresponding plurality of multiview pixels, e.g., represented by a plurality of groups of light valves. For example, as shown, in fig. 4A-4B, the center-to-center distance D between the first and second multibeam elements 114-1 and 114-2 is substantially equal to the center-to-center distance D between the first and second valve sets 116-1 and 116-2. In another embodiment (not shown), the relative center-to-center distances of the pair of multibeam elements 114 and the corresponding sets of valve groups may be different, e.g., the multibeam element 114 may have an inter-element spacing (i.e., center-to-center distance D) that is greater or less than the spacing (e.g., center-to-center distance D) between the sets of valve groups representing the multiview pixel.

In some embodiments, the shape of the multibeam element 114 may be similar to the shape of a multiview pixel, or equivalently, the shape of a set of light valves 116 (or "sub-array") corresponding to a multiview pixel. For example, the multibeam element 114 may have a square shape, and the multiview pixel (or corresponding set of arrangements of light valves 116) may be substantially square. In another example, the multibeam element 114 may have a rectangular shape, i.e., may have a length or longitudinal dimension that is greater than a width or transverse dimension. In this example, the multiview pixels (or an arrangement equivalent to the plurality of groups of light valves 116) of the corresponding multibeam element 114 may have a rectangular-like shape. Figure 4B illustrates a top or plan view of a square multibeam element 114 and a corresponding square multi-view pixel that includes a plurality of group light valves 116 that are square. In still other examples (not shown), the multibeam element 114 and corresponding multiview pixel have various shapes, including or at least approximating, but not limited to, triangular, hexagonal, and circular.

Further (e.g., as shown in fig. 4A), according to some embodiments, each multibeam element 114 is to provide a directional light beam 111 to one and only one multiview pixel. In particular, for a given one of the multibeam elements 114, the directional beams 111 having different principal angular directions corresponding to different views 104 of the multiview image are substantially limited to a single corresponding multiview pixel and its view pixel, i.e., a single set of light valves 116 corresponding to the multibeam element 114 (e.g., as shown in fig. 4A). Thus, each multibeam element 114 of the multibeam element based display 110 provides a corresponding set of directional light beams 111 having a set of different principal angular directions corresponding to different views 104 of the multiview image (i.e., the set of directional light beams 111 includes light beams having directions corresponding to each of the different view directions).

According to various embodiments, the multibeam element 114 may include any one of a number of different structures to couple out a portion of the guided light 113. For example, the different structures may include, but are not limited to, diffraction gratings, micro-reflective elements, micro-refractive elements, or various combinations thereof. In some embodiments, the multibeam element 114 includes a diffraction grating to diffractively couple out a portion of the guided light into a plurality of directional light beams 111 having different principal angular directions. In other embodiments, the multibeam element 114 comprises a micro-reflective element to reflectively couple out a portion of the guided light into the plurality of directional beams 111, or the multibeam element 114 comprises a micro-refractive element to couple out a portion of the guided light into the plurality of directional beams 111 by or with refraction (i.e., refractively couple out a portion of the guided light).

Fig. 5A is a cross-sectional view illustrating a portion of a multibeam element-based display 110 including a multibeam element 114 in an example, according to an embodiment consistent with the principles described herein. FIG. 5B is a cross-sectional view illustrating a portion of a multibeam element-based display 110 including a multibeam element 114 in one example, according to an embodiment consistent with the principles described herein. In particular, fig. 5A-5B illustrate the multibeam element 114 of the multibeam element based display 110 including the diffraction grating 114 a. The diffraction grating 114a is configured to diffractively couple a portion of the guided light 113 into a plurality of directional light beams 111. The diffraction grating 114a includes a plurality of diffractive features spaced apart from one another by a diffractive feature pitch, or diffractive feature, or grating pitch, that serves to provide the diffractively coupled-out portion of the guided light. According to various embodiments, the pitch of the diffractive features in the diffraction grating 114a, or the grating pitch, may be a sub-wavelength (i.e., less than the wavelength of the guided light).

In some embodiments, the diffraction grating 114a of the multibeam element 114 may be located at a surface of the light guide 112, or may be adjacent to a surface of the light guide 112. For example, the diffraction grating 114a may be located at the first surface 112 'of the light guide 112 or near the first surface 112' of the light guide 112, as shown in FIG. 5A. The diffraction grating 114a at the first surface 112 'of the light guide may be a transmission mode diffraction grating to diffractively couple a portion of the guided light through the first surface 112' into the directional beam 111. In another example, as shown in fig. 5B, the diffraction grating 114a may be located at or near the second surface 112 "of the light guide 112. When located on the second surface 112 ", the diffraction grating 114a may be a reflection mode diffraction grating. As a reflection mode diffraction grating, the diffraction grating 114a is to diffract part of the guided light and reflect part of the guided light toward the first surface 112 'to exit the directional light beam 111 as a diffraction through the first surface 112'. In other embodiments (not shown), the diffraction grating may be located between surfaces of the light guide 112, for example as one or both of a transmission mode diffraction grating and a reflection mode diffraction grating. It should be noted that in some embodiments described herein, the principal angular direction of the directional light beam 111 may include a refraction effect resulting from the directional light beam 111 exiting the light guide 112 at the light guide surface. For example, by way of example and not limitation, fig. 5B illustrates refraction (i.e., bending) of directional beam 111 due to a change in refractive index as directional beam 111 passes through first surface 112'. See also fig. 8A and 8B, as described below.

According to some embodiments, the diffractive features of the diffraction grating 114a may include one or both of grooves and ridges that are spaced apart from one another. The grooves or ridges may comprise the material of the light guide 112, e.g. may be formed in a surface of the light guide 112. In another example, the grooves or ridges may be formed of a material other than the light-guiding material, such as a film or layer of another material on the surface of the light guide 112.

In some embodiments, the diffraction grating 114a of the multibeam element 114 is a uniform diffraction grating, wherein the diffractive feature pitch is substantially constant or invariant throughout the diffraction grating 114 a. In other embodiments, the diffraction grating 114a may be a chirped (chirped) diffraction grating. By definition, a "chirped" diffraction grating is a diffraction grating that exhibits or has a diffraction spacing (i.e., grating pitch) of diffractive features that varies over the range or length of the chirped diffraction grating. In some embodiments, a chirped diffraction grating may have or exhibit a "chirp" or variation of the diffractive feature spacing that varies linearly with distance. Thus, by definition, a chirped diffraction grating is a "linearly chirped" diffraction grating. In other embodiments, the chirped diffraction grating of the multibeam element 114 may exhibit a non-linear chirp of the diffractive feature pitch. Various non-linear chirps may be used, including but not limited to exponential chirps, logarithmic chirps, or chirps that vary in a substantially non-uniform or random but still monotonic manner. Non-monotonic chirps may also be used, such as but not limited to sinusoidal chirps, or triangular, or saw tooth chirps. Combinations of any of these types of chirps may also be used.

In some embodiments, the diffraction grating 114a may include multiple diffraction gratings or an equivalent plurality of sub-gratings. Figure 6A is a cross-sectional view illustrating a diffraction grating 114a including a plurality of sub-gratings in an example, according to an embodiment consistent with the principles described herein. FIG. 6B is a plan view illustrating the diffraction grating 114a of FIG. 6A in an example, according to an embodiment consistent with the principles described herein; the cross-sectional view in fig. 6A may represent a cross-section taken, for example, from left to right from the bottom column of sub-gratings of the diffraction grating 114a shown in fig. 6B. As shown in fig. 6A and 6B, the plurality of sub-gratings includes a first sub-grating 114a-1 and a second sub-grating 114a-2 within a diffraction grating 114a of the multibeam element 114 on a surface of the light guide 112 (e.g., the second surface 112 as shown). The size s of the multibeam element 114 is shown in fig. 6A and 6B, and the boundaries of the multibeam element 114 are shown in fig. 6B with dotted lines.

According to some embodiments, the differential density of sub-gratings within the diffraction grating 114a between different multibeam elements 114 in the plurality of multibeam cells may be used to control the relative intensities of the plurality of directional light beams 111 diffractively scattered by the respective different multibeam elements 114. In other words, the diffractive multibeam element 114 may have the diffraction grating 114a therein in different densities, and the different densities (i.e., the different densities of the sub-gratings) may be used to control the relative intensities of the plurality of directional beams 111. Specifically, in the diffraction grating 114a, the multibeam element 114 having fewer sub-gratings may generate the plurality of directional beams 111 having a lower intensity (or beam density) than another multibeam element 114 having relatively more sub-gratings. For example, the differential density of the sub-gratings may be provided by using locations in the multibeam element 114, such as the location 114 a' shown in fig. 6B where the sub-gratings are absent or not disposed.

Fig. 7 is a plan view illustrating a pair of multibeam elements 114 in an example, according to an embodiment consistent with the principles described herein. As shown, a first multibeam element 114-1 of the pair of multibeam elements 114 has a higher density of sub-gratings within the diffraction grating 114a than is present in a second multibeam element 114-2 of the pair of multibeam elements 114. Specifically, the second multibeam element 114-2 has a diffraction grating 114a with fewer sub-gratings and more locations 114 a' without sub-gratings than the first multibeam element 114-1. In some embodiments, a higher density of sub-gratings in the first multibeam element 114-1 may provide a plurality of directional beams having a higher intensity than the intensity of the plurality of directional beams provided by the second multibeam element 114-2. According to some embodiments, the higher and lower intensities of the respective plurality of directional light beams provided by the differential sub-grating density shown in fig. 7 may be used to compensate for the light intensity of the guided light, which varies with the propagation distance within the light guide. By way of example and not limitation, FIG. 7 also shows a diffraction grating 114a having sub-gratings with curved diffractive features.

Fig. 8A is a cross-sectional view illustrating a portion of a multi-beam display 110 including a multi-beam element 114 in an example, according to another embodiment consistent with the principles described herein. Fig. 8B is a cross-sectional view illustrating a portion of a multibeam element-based display 110 including a multibeam element 114 in an example, according to an embodiment consistent with the principles described herein. In particular, fig. 8A and 8B illustrate various embodiments of the multibeam element 114 including micro-reflective elements. The plurality of micro-reflective elements used as or in the multi-beam element 114 may include, but are not limited to, reflectors employing reflective materials or films thereof (e.g., reflective metals) or reflectors based on Total Internal Reflection (TIR). According to some embodiments (e.g., as shown in fig. 8A-8B), the multibeam element 114 comprising the micro-reflective elements may be located at a surface (e.g., the second surface 112 ") of the light guide 112 or in the vicinity of the light guide 112. In other embodiments (not shown), the micro-reflective elements may be located in the light guide 112 at a position between the first surface 112 and the second surface 112.

For example, fig. 8A shows a multibeam element 114 that includes a micro-reflective element 114b, the micro-reflective element 114b having a reflective multi-faceted structure (facets) (e.g., a "prismatic" micro-reflective element) located near the second surface 112 "of the light guide 112. The faceted structure of prismatic micro-reflective elements 114b serves to reflect (i.e., reflectively scatter) a portion of the guided light 113 out of light guide 112 as a directional light beam 111. For example, the faceted structure may be tilted or skewed (i.e., have a tilt angle) relative to the direction of propagation of the guided light 113 to reflect a portion of the guided light out of the light guide 112. According to various embodiments, the multi-faceted structure may be formed using a reflective material within the light guide 112 (e.g., as shown in fig. 8A), or may be multiple surfaces of a prismatic cavity in the second surface 112 ″. In some embodiments, when prismatic cavities are employed, the refractive index variation at the cavity surface may provide reflection (e.g., TIR reflection), or the cavity surfaces forming the multi-faceted structure may be coated with a reflective material to provide reflection.

In another example, fig. 8B illustrates a multibeam element 114 that includes a micro-reflective element 114B, the micro-reflective element 114B having a substantially smooth curved surface, such as, but not limited to, a hemispherical micro-reflective element 114B. For example, a particular surface curve of the micro-reflective element 114b may be used to reflect portions of the guided light in different directions, depending on the point of incidence on the curved surface that is in contact with the guided light 113. As shown in fig. 8A and 8B, by way of example and not limitation, the portion of the guided light that is reflectively scattered from the light guide 112 is ejected or exited from the first surface 112'. Like prismatic micro-reflective elements 114B in fig. 8A, micro-reflective elements 114B in fig. 8B may be reflective material within light guide 112 or a cavity (e.g., a semicircular cavity) formed in second surface 112 ", as shown by way of example and not limitation in fig. 8B. By way of example and not limitation, fig. 8A and 8B also illustrate guided light 113 having two directions of propagation 115, 115' (i.e., illustrated by the bold arrows). For example, utilizing two propagation directions 115, 115' may help to provide a symmetric principal angular direction for the plurality of directional beams 111.

Fig. 9 is a cross-sectional view illustrating a portion of a multi-beam display 110 including a multi-beam element 114 in an example, according to another embodiment consistent with the principles described herein. In particular, fig. 11 shows a multibeam element 114 including a micro-refractive element 114 c. According to various embodiments, the micro-refractive element 114c is to refractively couple out or scatter out a portion of the guided light 113 from the light guide 112. That is, as shown in fig. 9, the micro-refractive element 114c is configured to use refraction (e.g., refractive coupling as opposed to diffraction or reflection) to couple or scatter partially guided light from the light guide 112 into the directional beam 111. Micro-refractive element 114c may have various shapes including, but not limited to, a hemispherical shape, a rectangular shape, a prismatic shape (i.e., a multi-faceted structure having a slope), and an inverted prismatic shape (e.g., as shown in fig. 9). According to various embodiments, the micro-refractive element 114c may extend or protrude from a surface (e.g., the first surface 112') of the light guide 112, as shown, or may be a cavity in the surface (not shown). Further, in some embodiments, the micro-refractive element 114c may comprise the material of the light guide 112. In other embodiments, the micro-refractive element 114c may comprise another material adjacent to the light guide surface, and in some examples, the micro-refractive element 114c may comprise another material in contact with the light guide surface.

Referring again to fig. 4A, the multibeam element-based display 110 may further include a light source 118. According to various embodiments, the light source 118 is used to provide light that is guided within the light guide 112. In particular, the light source 118 may be located adjacent to an entrance surface or entrance end (input end) of the light guide 112. In various embodiments of the present invention, light source 118 may comprise substantially any kind of light source (e.g., optical emitter), including one or more Light Emitting Diodes (LEDs) or lasers (e.g., laser diodes), but is not so limited. In some embodiments, the light source 118 may include an optical emitter for producing substantially monochromatic light having a narrow spectrum of frequencies representative of a particular color. Specifically, the color of the monochromatic light may be a primary color of a specific color space or a specific color model (e.g., a red-green-blue (RGB) color model). In other examples, light source 118 may be a substantially broadband light source to provide substantially broadband or polychromatic light. For example, light source 118 may provide white light. In some embodiments, the light source 118 may include a plurality of different optical emitters for providing different colors of light. Different optical emitters may be used to provide light having different, color-specific, non-zero propagation angles of the guided light corresponding to each of the different light colors.

In some embodiments, the light source 118 may further include a collimator (not shown). The collimator may be used to receive substantially non-collimated light from one or more optical emitters of the light source 118. The collimator is further for converting substantially non-collimated light into collimated light. In particular, according to some embodiments, the collimator may provide collimated light having a non-zero propagation angle and being collimated according to a predetermined collimation factor. Also, when different color optical emitters are employed, the collimator may be configured to provide collimated light having one or both of different, color-specific, non-zero conduction angles and different color-specific collimation factors. The collimator is further used to transmit the collimated beam to the light guide 112 to be conducted as guided light 113, as described above.

Referring again to fig. 3, the heads-up display 100 also includes a light combiner 120. According to various embodiments, the light combiner 120 is configured to relay the plurality of different views 104 of the multi-view image to the view frame 102 of the heads-up display 100. According to various embodiments, the optical combiner 120 is further configured to provide a view of the physical environment 106 (or equivalently a "physical environment view" 106) across the optical combiner 120 at view block 102. By "beyond," it is meant that the view of the physical environment is a view visible to a user of the physical environment, which is on the side of the light combiner 120 opposite the user. Thus, by definition herein, a "view across the light combiner 120" of the physical environment 106 is a view "seen through" the light combiner 120 ".

By way of example and not limitation, FIG. 3 illustrates cones, squares, and cylinders as a representation of the physical environment 106. In particular, the light combiner 120 is configured to combine the multi-view image (i.e., including the plurality of different views 104) provided by the multi-beam element based display 110 with the physical environment view 106 into the combined view 108, and then provide the combined view 108 at the view box 102. According to various embodiments, a combined view 108 comprising a physical environment view 106 and a plurality of different views 104 of a displayed image may be viewed by a user at a view box 102. For example, the combined view 108 may be displayed to the user as a displayed image containing a different view 104 overlaid with the physical environment view 106.

According to some embodiments, the light combiner 120 includes a partially reflective surface configured to reflect the plurality of different views 104 of the image toward the view frame 102. In various embodiments, the partially reflective surface can be substantially any surface that provides partially reflected incident light. For example, the partially reflective surface may be a half-silvered mirror, a beam splitter, or substantially any equivalent. In another example, the partially reflective surface may be a surface (coating or otherwise) of a substantially transparent dielectric material adjacent to air or another dielectric material (i.e., the partially reflective surface may be provided by a change in the refractive index of the surface). The partially reflective surface is further configured to allow or facilitate viewing of the physical environment 106 across the optical combiner 120. Thus, the partially reflective surface is also partially transparent to light (e.g., from another direction such as the physical environment 106). In particular, according to various embodiments, a portion of the light from the physical environment 106 can pass through the partially reflective surface to be combined with the light representing the different views 104 as a combined view 108 at the view block 102. In other embodiments, the optical combiner 120 may be another type of optical combiner, including, but not limited to, a waveguide (waveguide) or optical waveguide optical combiner.

Fig. 10 is a cross-sectional view illustrating an optical combiner 120 in an example, according to an embodiment consistent with the principles described herein. In particular, fig. 10 shows a light combiner 120 that includes a partially reflective surface 122. Light 104' incident on the partially reflective surface 122 from the multibeam element-based display 110 (not shown in fig. 10) and representing a different view 104 of the displayed image is reflected by the partially reflective surface 122 in the direction indicated by the arrow, away from the partially reflective surface 122 (i.e., toward the viewing frame 102 (not shown in fig. 10)). Also, as shown, light 106 ' from the physical environment 106 representing a view (including an image) of the physical environment is combined with the reflected light 104 ' through the partially reflective surface 122 into combined light 108 '. The combined light 108' forms a combined view 108 (e.g., at view block 102, as shown in fig. 3). As described above, the combined view 108 is an overlay of the display image and the different views 104 of the physical environment view 106.

In some embodiments, the light combiner 120 may comprise a portion of a viewport (viewport), window, or windshield of a vehicle, such as, but not limited to, an automobile, camper, utility vehicle, military vehicle, aircraft, space vehicle, or marine vessel, such as a boat, or the like. In particular, in embodiments where the vehicle is an automobile, heads-up display 100 may be referred to as an automobile heads-up display 100. In this context, "automobile" and "windshield" are used for purposes of simplifying the discussion and are not limiting. In some embodiments, a portion of the windshield may be the windshieldThe material itself (e.g., windshield glass, acrylic glass, polycarbonate, etc.). In other embodiments, the portion of the windshield may be a layer or film of material applied or affixed to a surface of the windshield material. For example, the light combiner 120 including the partially reflective surface 122 may include a partially reflective metal layer (e.g., aluminum, silver, gold, etc.) deposited on a surface of the windshield material. In another example, partially reflective surface 122 can be a partially reflective film (e.g., partially metallized) applied to a surface of a windshield materialThin film) to serve as the optical combiner 120.Is a registered trademark of DuPont Corporation (Dupont De Nemours and Company Corporation, Wilmington, Delaware, U.S.).

Fig. 11 is a schematic diagram illustrating an automotive heads-up display 100 in an example, according to an embodiment consistent with principles described herein. The automotive heads-up display 100 includes a multibeam element-based display 110 to generate different views 104 of an image. The automotive heads-up display 100 also includes a light combiner 120. As shown, the light combiner 120 includes a portion of a windshield 124 of an automobile (not shown) that serves as or includes a partially reflective surface 122. The light 104' representing the different views 104 is relayed from the multibeam element-based display 110 to a light combiner 120 at an automotive windshield 124. The light 104' is reflected by the light combiner 120 towards the view frame 102. In addition, light 106 'from a physical environment 106 outside the automobile (i.e., a view through the windshield) is combined with light 104' reflected by the light combiner 120 as a combined view 108 at view block 102. A user (e.g., by a driver or passenger of an automobile) may view the combined view 108 at view box 102. The combined view 108 includes views from the physical environment 106 superimposed with images from different view 104 representations of the multibeam element-based display 110.

According to some embodiments of the principles described herein, a multi-view heads-up display system is provided. Fig. 12 is a block diagram of a multi-view heads-up display system 200 in an example, according to an implementation consistent with principles described herein. The multi-view heads-up display system 200 of fig. 12 is configured to provide a multi-view image to a viewing frame 202 for viewing by a user. According to various embodiments, the multi-view image includes a plurality of different views 204 (e.g., different perspective views). Further, the user may view the multi-view image and a view of the physical environment 206 (or equivalently, a "physical environment view" 206) at the view box 202 as a combined view 208. Further, according to various embodiments, the user may view the combined view 208 in a so-called "heads up" manner.

As shown in fig. 12, the multi-view heads-up display system 200 includes a multi-beam element based display 210. The multibeam element based display 210 is used to provide a multiview image comprising a plurality of different views 204. In particular, for example, the multibeam element-based display 210 may be a multiview display or a naked-eye stereoscopic display to provide multiview images. In some embodiments, the multi-beam element based display 210 may be substantially similar to the multi-beam element based display 110 described above with respect to the near-eye display 100.

Specifically and as shown, the multibeam element-based display 210 includes a light guide 212. The light guide 212 serves to guide light into guided light. For example, the guided light may be a collimated light beam and may be guided at a non-zero propagation angle. According to some embodiments, the light guide 212 may be substantially similar to the light guide 112 of the multibeam element-based display 110 described above.

In addition, the multibeam element-based display 210 shown in fig. 12 includes a multibeam element array 214. The array of multibeam elements 214 is to scatter a portion of the guided light into a plurality of directional light beams having principal angular directions corresponding to view directions of the plurality of different views 204. In some embodiments, the multibeam elements of the multibeam element array 214 may be substantially similar to the array of multibeam elements 114 described above with respect to the multibeam element based display 110 of the heads-up display 100. For example, the multibeam elements in the multibeam element array 214 may include one or more of a diffraction grating, a micro-reflective element, and a micro-refractive element optically connected to the light guide 212 to scatter out the portion of the guided light. The diffraction grating, micro-reflective elements, and micro-refractive elements may be substantially similar to diffraction grating 114a, micro-reflective elements 114b, and micro-refractive elements 114c, also described above. Further, in some embodiments, the multibeam elements of the multibeam element array 214 may be used to provide conformal scattering of a portion of the guided light.

In some embodiments, as shown in fig. 12, the multibeam element-based display 210 may further include a light source 216 and a light valve array 218. For example, the light source 216 may be used to provide light to the light guide 212 as guided light. In some embodiments, the light source 216 may include an optical emitter that emits light, and a collimator that converts the emitted light into a collimated light beam as the light is provided. In some embodiments, the light sources 216 may be substantially similar to the light sources 118 of the multibeam element-based display 110 described above.

According to various embodiments, the light valve array 218 is configured to selectively modulate directional beams of the plurality of directional beams as pixels representing different views 204 of the provided multi-view image. In some embodiments, the array of light valves 218 may be substantially similar to the array of light valves 116 described above with respect to the multibeam element-based display 110. For example, the light valve array 218 may include any of a variety of light valves, including but not limited to liquid crystal light valves and electrowetting light valves. Further, according to some embodiments, the size of the multibeam elements of the multibeam element array 214 is comparable to the size of the light valves in the light valve array 218 of the multibeam element-based display 210.

The multi-view heads-up display system 200 shown in fig. 12 also includes a light combiner 220. The light combiner 220 is configured to relay the multi-view image to the view frame 202 of the multi-view heads-up display system 200. Further, the light combiner 220 is configured to provide a combined view 208 (e.g., across the light combiner 220) containing the multi-view image and the physical environment view 206 at the view box 202. In other words, the light combiner 220 is configured to combine the multi-view image containing the different views 204 with the physical environment view 206 and provide the combined view 208 to the view box 202. In some embodiments, the light combiner 220 may be substantially similar to the light combiner 120 of the heads-up display 100 described above.

In particular, in some embodiments, the light combiner 220 includes one of a partially reflective surface and a substantially transparent light guide configured to relay the provided multi-view image to the bezel 202 of the multi-view heads-up display system 200. According to various embodiments, the partially reflective surface and the substantially transparent light guide are each configured to facilitate viewing of the physical environment through a respective one of the partially reflective surface and the substantially transparent light guide. In some embodiments, the light combiner 220 may comprise a portion of a windshield of the vehicle. For example, vehicles may include, but are not limited to, automobiles, airplanes, and boats. Thus, according to some embodiments, the multi-view heads-up display system 200 may be a vehicle heads-up display system. For example, according to various embodiments, the multi-view heads-up display system 200 may be an automotive heads-up display system, an aircraft heads-up display system, or the like.

In some embodiments (e.g., as shown in fig. 12), the multi-view heads-up display system 200 also includes a relay optical element (relay optical) 230. The relay optics 230 may be located between the multibeam element based display 210 and the light combiner 220. The relay optics 230 are configured to relay the light of or corresponding to the multi-view image (e.g., contained and displayed as the different views 204) from the multi-beam element based display 210 to the light combiner 220. In some embodiments, relay optics 230 include a collimating lens, such as, but not limited to, one or both of a lens and a reflector. For example, the lenses and reflectors may be configured to relay and collimate light from the multibeam element-based display 210. Thus, the lenses and reflectors of relay optics 230 that provide collimation may be referred to as collimating lenses and collimating reflectors, respectively. For example, the collimation of the light may provide a focus of the light representing the different views 204 at the view box 202.

According to other embodiments consistent with principles described herein, the present invention provides a method of operating a heads-up display. Fig. 13 is a flow chart illustrating a method 300 of operation of a heads-up display in an example, according to an embodiment consistent with the principles described herein. As shown in fig. 13, a method 300 of operating a heads-up display includes a step 310 of scattering a portion of guided light from a light guide using an array of multibeam elements to produce a plurality of directional light beams having a principal angular direction corresponding to a view direction of a multi-view image. According to some embodiments, the light guide and the array of multibeam elements may be substantially similar to the array of light guides 112 and multibeam elements 114 of the multibeam element based display 110 described above with respect to the heads-up display 100. For example, the step 310 of scattering the portion of the guided light may include using a multibeam element of a multibeam element array comprising a diffraction grating to diffractively scatter out the portion of the guided light. Further, the scattering 310 the portion of the guided light may include using a multibeam element of a multibeam element array including micro-reflective elements to reflectively scatter out the portion of the guided light. Further, the step 310 of scattering the portion of the guided light may include using a multibeam element of a multibeam element array including micro-refractive elements to refractively scatter out the portion of the guided light.

The method 300 of operation of the heads-up display shown in fig. 13 also includes a step 320 of modulating a directional beam of the plurality of directional beams using a light valve array to provide a multi-view image. In some embodiments, the array of light valves may be substantially similar to the array of light valves 116 of the multibeam element based display 110 of the heads-up display 100, as described above.

As shown in fig. 13, the method 300 of operating a heads-up display further includes a step 330 of combining a plurality of different views of the multi-view image with views of the physical environment using a light combiner to form a combined view. In particular, the physical environment is the view viewed across and through the optical combiner. In some embodiments, the light combiner may be substantially similar to the light combiner 120 described above with respect to the heads-up display 100. For example, the light combiner may include a partially reflective surface (e.g., a partially reflective portion of a windshield). In some embodiments, the light combiner comprises a portion of a windshield of the vehicle.

According to various embodiments, the method 300 of operation of a multi-view heads-up display relays a combined view (or equivalently a "combined image") to a view frame. The viewing frame may be substantially similar to the viewing frame 102 of the heads-up display 100 described above. In particular, the view frame may be a position where the user views a relayed combined view that includes the physical environment view and the multi-view image. According to various embodiments, a user viewing the combined view may perceive the multi-view image and the physical environment simultaneously, or superimpose them into a combined view.

Thus, examples and embodiments of heads-up displays, multi-view head-up display systems, and methods of operation of head-up displays have been described herein that employ multi-beam element based displays to provide multiple different views of a multi-view image, and also provide for superposition of a physical environment view and the multi-view image in a view frame. It should be understood that the above-described examples are merely illustrative of some of the many specific examples that represent the principles described herein. It should be apparent that numerous other arrangements can be readily devised by those skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims (21)

1. A heads-up display comprising:

a multibeam element based display configured to provide a plurality of different views of a multiview image, the multibeam element based display comprising a multibeam element array configured to provide a plurality of directional beams having directions corresponding to respective view directions of the plurality of different views and a light valve array configured to modulate the plurality of directional beams to provide the multiview image; and

a light combiner configured to relay the multi-view image to a bezel of the heads-up display, the light combiner further configured to provide a combined view at the bezel, the combined view comprising the multi-view image and a view of a physical environment behind the bezel.

2. The heads up display of claim 1 wherein the size of the multibeam elements of the multibeam element array is between fifty to two hundred percent of the size of the light valves of the light valve array.

3. The heads-up display of claim 1 wherein the multibeam element based display further comprises a light guide configured to guide light along a length of the light guide as the guided light, the multibeam elements of the multibeam element array configured to scatter a portion of the guided light out of the light guide as directional beams of the plurality of directional beams.

4. The heads up display of claim 3 wherein the multibeam element comprises a diffraction grating configured to diffractively scatter out the portion of the directed light.

5. The heads-up display of claim 3 wherein the multibeam element comprises one or both of a micro-reflective element configured to reflectively scatter out the portion of the directed light and a micro-refractive element configured to refractively scatter out the portion of the directed light.

6. The heads up display of claim 3 wherein the multibeam element is positioned at one of a first surface and a second surface of the light guide, the multibeam element configured to scatter the portion of the guided light out through the first surface.

7. The heads-up display of claim 3 wherein the multi-beam element based display further comprises a light source optically coupled to the input end of the light guide, the light source configured to provide the light to be guided as one or both of the guided light having a non-zero propagation angle and the guided light collimated by a predetermined collimation factor.

8. The heads-up display of claim 1 wherein the light combiner includes a partially reflective surface configured to reflect the plurality of different views of the image toward the bezel and further configured to transmit the view of the physical environment through the partially reflective surface toward the bezel.

9. The heads-up display of claim 1 wherein the light combiner comprises a portion of a windshield of an automobile, the heads-up display being an automobile heads-up display.

10. A multi-view heads-up display system comprising:

a multibeam element based display configured to provide a multiview image comprising a plurality of different views, the multibeam element based display comprising: a light guide configured to guide light as guided light and a multi-beam element array configured to scatter portions of the guided light out as a plurality of directional light beams having principal angular directions corresponding to view directions of the plurality of different views; and

a light combiner configured to relay the multi-view image to a bezel of the heads-up display system and combine a view of the multi-view image and a view of a physical environment behind the bezel within the bezel.

11. The multi-view heads-up display system of claim 10 wherein a multibeam element of the array of multibeam elements includes one or more of a diffraction grating, a micro-reflective element, and a micro-refractive element optically connected to the light guide to scatter out the portion of the guided light.

12. The multi-view heads-up display system of claim 11 wherein the multi-beam elements of the array of multi-beam elements are configured to provide conformal scattering of the portion of the guided light.

13. The multi-view heads-up display system of claim 10 wherein the multi-beam element based display further comprises:

a light source configured to provide light to the light guide as the guided light; and

a light valve array configured to selectively modulate directional beams of the plurality of directional beams, the selectively modulated directional beams representing pixels of different views of the provided multi-view image,

wherein the guided light has a predetermined collimation factor, a multibeam element of the array of multibeam elements being located at a surface adjoining the light guide.

14. The multi-view heads-up display system of claim 13 wherein the multi-beam element has a size comparable to a size of a light valve in the light valve array of the multi-beam element based display.

15. The multiview heads up display system of claim 13, wherein the light valve array comprises a plurality of liquid crystal light valves.

16. The multiview heads-up display system of claim 10, wherein the light combiner comprises one of a partially reflective surface and a substantially transparent light guide configured to relay the provided multiview image to the view box, each of the partially reflective surface and the substantially transparent light guide configured to facilitate viewing of the physical environment through the respective one of the partially reflective surface and the substantially transparent light guide.

17. The multi-view heads-up display system of claim 10 wherein the light combiner comprises a portion of a windshield of a vehicle, the multi-view heads-up display system being a vehicle heads-up display system.

18. The multiview heads-up display system of claim 10, further comprising a relay optical element interposed between the multibeam element based display and the light combiner, the relay optical element configured to relay light corresponding to the multiview image from the multibeam element based display to the light combiner.

19. A method of operating a heads-up display, comprising:

scattering out a portion of the guided light from the light guide using the multi-beam element array to produce a plurality of directional light beams having a principal angular direction corresponding to a view direction of the multi-view image;

modulating a directional beam of the plurality of directional beams using a light valve array to provide the multi-view image; and

combining the multi-view image and a view of a physical environment using a light combiner to form a combined view, the physical environment being viewed through the light combiner,

wherein the size of the multibeam elements in the multibeam element array is comparable to the size of the light valves in the light valve array.

20. The method of operating a heads up display of claim 19 wherein the portion of the directed light that is scattered out includes one or more of:

using a multibeam element of the multibeam element array comprising a diffraction grating to diffractively scatter out the portion of the directed light;

using a multibeam element of the multibeam element array comprising micro-reflective elements to reflectively scatter out the portion of the directed light; and

using a multibeam element of the multibeam element array comprising micro-refractive elements to refractively scatter out the portion of the directed light.

21. The method of operating a heads up display of claim 19 wherein the light combiner comprises a portion of a windshield of a vehicle.