Multi-view display with shiftable convergence plane, system and method - Patents.com

Abstract

The multi-view display includes a multi-view backlight configured to emit directional light beams configured to converge to a point in a convergence plane, and an array of light valves configured to modulate the directional light beams in the convergence plane, wherein the distance between the multi-view backlight and the light valve array is configured to be adjustable to shift a corresponding position of the convergence plane relative to the multi-view display.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS N / A

[0002] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT N / A [Background technology]

[0003] Electronic displays are a nearly ubiquitous medium for conveying information to users of a wide variety of devices and products. The most commonly used electronic displays include cathode ray tubes (CRTs), plasma display panels (PDPs), liquid crystal displays (LCDs), electroluminescent displays (ELs), organic light emitting diode (OLED) and active matrix OLED (AMOLED) displays, electrophoretic displays (EPs), and various displays that use electromechanical or electrofluidic light modulation (e.g., digital micromirror devices, electrowetting displays, etc.). In general, electronic displays can be classified as either active displays (i.e., displays that emit light) or passive displays (i.e., displays that modulate light provided by another light source). The most obvious examples of active displays are CRTs, PDPs, and OLED / AMOLEDs. Displays that are typically classified as passive when considering emitted light are LCDs and EP displays. Passive displays often exhibit attractive performance characteristics, including but not limited to, inherently low power consumption, but their lack of light emission may limit their use somewhat in many practical applications.

[0004] To overcome the limitations of passive displays related to the emitted light, many passive displays are coupled to an external light source. The coupled light source may enable these otherwise passive displays to emit light and essentially function as active displays. An example of such a coupled light source is a backlight. A backlight is a light source (often a panel backlight) arranged behind an otherwise passive display to illuminate the passive display. For example, the backlight may be coupled to an LCD or EP display. The backlight emits light, which passes through the LCD or EP display. The emitted light is modulated by the LCD or EP display, and the modulated light is then emitted from the LCD or EP display. In many cases, the backlight is configured to emit white light. In that case, color filters are used to convert the white light into the various colors used in the display. The color filters may, for example, be located at the output of the LCD or EP display (less common) or between the backlight and the LCD or EP display. Alternatively, the different colors can be achieved by field sequential illumination of the display using different colors, such as primary colors. Summary of the Invention

[0005] The present invention includes the following [1] to

[20] . [1] A multi-view display, comprising: a multi-view backlight configured to emit light as directional light beams having different principal angular directions corresponding to respective different view directions of a multi-view image, the directional light beams being configured to converge at points in a convergence plane corresponding to positions of the different views of the multi-view image; an array of light valves configured to modulate the directional light beams as the different views of the multi-view image at the convergence plane; A multi-view display, wherein a distance between the multi-view backlight and the light valve array is configured to be adjustable to shift a corresponding position of the convergence plane relative to the multi-view display. [2] A multi-view display as described in [1] above, configured such that inter-view spacing between the different views of the multi-view image is constant as a function of the adjustable distance between the multi-view backlight and the light valve array and the corresponding position of the convergence plane. [3] A multi-view display as described in [2] above, wherein the inter-view spacing in the convergence plane is commensurate with the interocular distance of a user of the multi-view display. [4] The multi-view display of [1] above, wherein adjusting the distance between the multi-view backlight and the light valve array comprises mechanical movement of the multi-view backlight relative to the light valve array. [5] The multi-view display of [1], wherein the multi-view backlight is a first multi-view backlight, the convergence plane is a first convergence plane of the multi-view display, and the multi-view display further comprises a second multi-view backlight configured to provide a directional light beam that converges within the second convergence plane at a point corresponding to a position of the different view of the multi-view image at the second convergence plane, and the position of the second convergence plane relative to the multi-view display is different from the position of the first convergence plane. [6] The multi-view display of [5], wherein the first multi-view backlight is disposed between the second multi-view backlight and the light valve array, the first multi-view backlight transmits the directional light beam provided by the second multi-view backlight, and adjusting the distance between the multi-view backlight and the light valve array includes selectively activating one of the first multi-view backlight and the second multi-view backlight to provide the multi-view image within each of the first and second convergence planes. [7] The multi-view backlight is a light guide configured to direct light in a direction of propagation along a length of the light guide; and a plurality of multi-beam elements spaced apart along a length of the light guide, one multi-beam element of the plurality having a size corresponding to a size of a light valve of the light valve array, the plurality of multi-beam elements being configured to scatter a portion of the guided light out of the light guide as the directional light beam. [8] The multi-view display of [7], wherein the multi-beam element includes one or more of a diffraction grating, a micro-reflective element, and a micro-refractive element optically connected to the light guide, the diffraction grating configured to diffractively scatter the portion of the guided light, the micro-reflective element configured to reflectively scatter the portion of the guided light, and the micro-refractive element configured to refractively scatter the portion of the guided light. [9] A multi-view display system comprising the multi-view display of [1] above, further comprising a head tracker configured to determine a distance between the multi-view display and a user, the distance between the multi-view backlight and the light valve array being adjusted in accordance with the determined distance between the multi-view display and the user, and configured to shift the convergence plane position to correspond to a position of the user relative to the multi-view display.

[10] A multi-view display system, comprising: a multi-view backlight configured to provide directional light beams having different principal angular directions corresponding to different view directions of respective different views of the multi-view image; an array of light valves configured to modulate the directional light beams to provide the multi-view image at a convergence plane of the multi-view display system; a head tracker configured to determine a distance of a user from the multi-view display system; A multi-view display system, wherein the distance between the multi-view backlight and the light valve array is configured to be adjustable according to the determined user distance to shift the position of the convergence plane to correspond to the determined user distance.

[11] A multi-view display system as described in

[10] , wherein the inter-view spacing of the different views in the convergence plane is configured to remain constant when the convergence plane is shifted, and the inter-view spacing within the convergence plane is commensurate with the interocular distance of the user.

[12] The multi-view display system of

[10] , wherein the multi-view backlight is a first multi-view backlight of the multi-view display system at a first distance from the light valve array, the multi-view display system further comprising a second multi-view backlight at a second distance from the light valve array, the first distance being different from the second distance, and the convergence plane position being configured to be shifted by selectively activating one of the first multi-view backlight and the second multi-view backlight.

[13] The multi-view backlight is a light guide configured to direct light in a direction of propagation along a length of the light guide;

[10] A multi-view display system as described in

[10] above, comprising a plurality of multi-beam elements spaced apart from one another along a length of the light guide, one multi-beam element of the plurality of multi-beam elements having a size corresponding to a size of a light valve of the light valve array, and configured to scatter a portion of the guided light from the light guide as the directional light beam.

[14] The multi-view display system described in

[10] above, wherein the head tracker comprises one or more of a plurality of cameras configured to determine user distance using disparity estimation, and a time-of-flight sensor configured to determine user distance using a time of propagation of a signal reflected by the user.

[15] A method of multi-view display operation, comprising: emitting light using a multi-view backlight as directional light beams having different principal angular directions corresponding to different view directions of a multi-view image, the directional light beams converging at points in a convergence plane corresponding to positions of the different views of the multi-view image; modulating the directional light beams using the array of light valves to provide the different views of the multi-view image at the convergence plane; and adjusting a distance between the multiview backlight and the light valve array to shift a position of the convergence plane relative to the multiview display.

[16] The step of emitting light using a multi-view backlight includes: Guiding light in a light guide as guided light; and scattering a portion of the guided light from the light guide as the directional light beam using an array of multibeam elements, the size of the multibeam elements in the multibeam element array corresponding to the size of the light valves in the light valve array.

[17] The method of operating a multi-view display described in

[16] , wherein the multi-beam element includes one or more of a diffraction grating, a micro-reflective element, and a micro-refractive element optically connected to the light guide, the diffraction grating diffractively scattering the portion of the guided light, the micro-reflective element reflectively scattering the portion of the guided light, and the micro-refractive element refractingly scattering the portion of the guided light.

[18] A method of operating a multi-view display as described in

[15] above, wherein adjusting the distance between the multi-view backlight and the light valve array comprises mechanically moving the multi-view backlight relative to the light valve array.

[19] A method of multi-view display operation as described in

[15] above, further comprising the steps of determining a user's distance from the multi-view display using a head tracker, and adjusting the distance between the multi-view backlight and the light valve array to shift the convergence plane position to correspond to the determined user distance.

[20] The step of determining the distance of the user from the multi-view display using a head tracker comprises: capturing images of the user using multiple cameras and determining the distance of the user from the multi-view display using disparity estimation; determining the distance of the user from the multi-view display using a time-of-flight sensor from a time of propagation of a signal emitted by the time-of-flight sensor and reflected by the user; The method of multi-view display operation according to

[19] above, comprising one or more of the following: Various features of examples and embodiments according to the principles described herein can be more readily understood by reference to the following detailed description in conjunction with the accompanying drawings, in which like reference numerals indicate like structural elements and in which: [Brief description of the drawings]

[0006] [Figure 1A] 1 shows a perspective view of an example multi-view display according to an embodiment consistent with principles described herein.

[0007] [Figure 1B]1 illustrates a graphical representation of angular components of a light beam having a particular principal angular direction corresponding to a view direction of a multi-view display in one example, according to an embodiment consistent with principles described herein.

[0008] [Figure 2A] 1 illustrates a side view of an example multi-view display according to an embodiment consistent with principles described herein. [Figure 2B] 1 illustrates a side view of an example multi-view display according to an embodiment consistent with principles described herein.

[0009] [Figure 3A] 1 illustrates an example multi-view display with two multi-view backlights, according to an embodiment consistent with principles described herein. [Figure 3B] 1 illustrates an example multi-view display with two multi-view backlights, according to an embodiment consistent with principles described herein.

[0010] [Figure 4] 1 illustrates a multi-view display with a multi-view backlight with a light guide in one example, according to an embodiment consistent with principles described herein.

[0011] [Diagram 5] 1 shows a block diagram of an example multi-view display system according to an embodiment consistent with principles described herein.

[0012] [Figure 6] 1 illustrates a flowchart of an example method of multi-view display operation, according to an embodiment consistent with principles described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Some examples and embodiments may have other features in addition to and / or in place of the features shown in the above-referenced figures. These and other features are described in more detail below with reference to the above-referenced figures.

[0014] Examples and embodiments according to the principles described herein provide a multi-view display using an adjustable convergence plane with application to electronic displays. In various embodiments consistent with the principles herein, a multi-view display is provided. The multi-view display is configured to emit directional light beams configured to converge at points in the convergence plane corresponding to different views of a multi-view image. A distance between the multi-view backlight and the light valve array of the multi-view display is configured to be adjustable to shift a corresponding position of the convergence location relative to the multi-view display.

[0015] A "multi-view display" is defined herein as an electronic display or display system configured to provide different views of a multi-view image in different viewing directions. FIG. 1A shows a perspective view of an example multi-view display 10 according to an embodiment consistent with the principles described herein. As shown in FIG. 1A, the multi-view display 10 includes a screen 12 for displaying a multi-view image to be viewed. The multi-view display 10 provides different views 14 of the multi-view image in different viewing directions 16 relative to the screen 12. The viewing directions 16 are shown as arrows extending from the screen 12 in various different principal angular directions. The different views 14 are illustrated as shaded polygonal boxes at the ends of the arrows (i.e., indicating the viewing directions 16). Although only four views 14 and four viewing directions 16 are illustrated, these are all illustrative and not limiting. It should be noted that although the different views 14 are shown in FIG. 1A as being on the screen, when a multi-view image is displayed on the multi-view display 10, the views 14 actually appear on or near the screen 12. The views 14 depicted on the screen 12 are merely for ease of explanation and are meant to represent viewing of the multi-view display 10 from each one of the viewing directions 16 corresponding to a particular view 14.

[0016] A light beam having a view direction, or equivalently a direction corresponding to a view direction of a multi-view display, generally has a principal angular direction given by angular components {θ, φ}, as defined herein. Angular component θ is referred to herein as the "elevation component" or "elevation angle" of the light beam. Angular component φ is referred to herein as the "azimuth component" or "azimuth angle" of the light beam. By definition, elevation angle θ is the angle in a vertical plane (e.g. perpendicular to the plane of the multi-view display screen) and azimuth angle φ is the angle in a horizontal plane (e.g. parallel to the plane of the multi-view display screen).

[0017] FIG. 1B illustrates a graphical representation of angular components {θ, φ} of a light beam 20 having a particular principal angular direction corresponding to a view direction (e.g., view direction 16 in FIG. 1A) of a multi-view display in one example, according to an embodiment consistent with principles described herein. Furthermore, the light beam 20, as defined herein, emanates or radiates from a particular point. 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 illustrates the origin O of the light beam (or view direction).

[0018] Further, in this specification, the term "multi-view" as used in the terms "multi-view image" and "multi-view display" is defined as a plurality of views that represent different viewpoints or include angular parallax between the views of the plurality of views. Furthermore, in this specification, the term "multi-view" explicitly includes more than two different views (i.e., a minimum of three views, and generally more than three views) as defined in this specification. Thus, as used in this specification, a "multi-view display" is explicitly distinguished from a stereoscopic display that includes only two different views to represent a scene or image. However, it should be noted that although a multi-view image and a multi-view display include more than two views as defined in this specification, a multi-view image can be viewed (e.g., on a multi-view display) as a stereoscopic pair of images by selecting to view only two of the multiple views at a time (e.g., one view per eye).

[0019] As defined herein, a "multibeam element" is a structure or element of a backlight or display that generates light comprising a plurality of directional light beams. The directional light beams of the plurality of directional light beams (or "directional light beam plurality") generated by the multibeam element have, as defined herein, different principal angular directions from each other. In particular, by definition, a directional light beam of the plurality of directional light beams has a predefined principal angular direction that is different from another directional light beam of the plurality of directional light beams. According to some embodiments, the size of the multibeam element may correspond to the size of a light valve used in a display (e.g., a multiview display) associated with the multibeam element. In particular, in some embodiments, the size of the multibeam element may be about half to about twice the size of the light valve. In some embodiments, the multibeam element may provide polarization selective scattering.

[0020] According to various embodiments, the multiple directional light beams can represent a light field. For example, the multiple directional light beams can be confined to a substantially conical spatial region or can have a predetermined angular spread that includes different principal angular directions of the light beams in the multiple light beams. Thus, the predetermined angular spread of the combined directional light beams (i.e., the multiple directional light beams) can represent a light field.

[0021] According to various embodiments, the different principal angular directions of the various directional light beams in the multiple directional light beams are determined by characteristics including, but not limited to, the size (e.g., one or more of length, width, area, etc.) of the multibeam element along with other characteristics. For example, in a diffractive multibeam element, the "grating pitch" or diffractive feature spacing and the orientation of the diffraction grating within the diffractive multibeam element may be characteristics that at least partially determine the different principal angular directions of the various directional light beams. In some embodiments, the multibeam element may be considered as an "extended point source," as defined herein, i.e., multiple point sources distributed over the extent of the multibeam element. Furthermore, the directional light beams generated by the multibeam element may have principal angular directions given by the angular components {θ, φ}, as described below with respect to FIG. 1B.

[0022] As used herein, a "light guide" is defined as a structure that uses total internal reflection to guide light within the structure. In particular, a light guide may include a core that is substantially transparent at the operating wavelength of the light guide. The term "light guide" generally refers to a dielectric light guide that uses total internal reflection to guide light at the interface between the dielectric material of the light guide and the material or medium that surrounds 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 the surface of the light guide material. In some embodiments, the light guide may include a coating in addition to or instead of the aforementioned refractive index difference to further promote total internal reflection. The coating may be, for example, a reflective coating. The light guide may be any of a number of light guides, including, but not limited to, one or both of a flat plate or slab guide and a strip guide.

[0023] Further, the term "flat" as applied to a light guide, such as a "flat light guide", is defined herein as a piecewise or differentially planar layer or sheet, sometimes referred to as a "slab" guide. In particular, a flat light guide is defined as a light guide configured to direct light in two substantially orthogonal directions bounded by the top and bottom (i.e., opposing) surfaces of the light guide. Further, as defined herein, the top and bottom surfaces are both separated from each other and may be substantially parallel to each other, at least in a differential sense. That is, within any differentially small section of the flat light guide, the top and bottom surfaces are substantially parallel or coplanar.

[0024] In some embodiments, the flat light guide may be substantially flat (i.e., confined to a plane), and thus the flat light guide is a planar light guide. In other embodiments, the flat light guide may be curved in one or two orthogonal dimensions. For example, the flat light guide may be curved in one dimension to form a cylindrical flat light guide. However, any curvature has a radius of curvature large enough to ensure that total internal reflection is maintained within the flat light guide to guide the light.

[0025] Furthermore, as used herein, the article "a" is intended to have its ordinary meaning in the patent art, i.e., "one or more." For example, "a light valve" means one or more light valves, and thus, "the light valve" means "light valve(s)" herein. Also, any reference herein to "top," "bottom," "upper," "lower," "up," "down," "front," "rear," "first," "second," "left," or "right" is not intended to be limiting herein. As used herein, the term "about," when applied to a value, generally means within the tolerance of the equipment used to generate the value, or may mean plus or minus 10%, or plus or minus 5%, or plus or minus 1%, unless otherwise specified. Additionally, as used herein, the term "substantially" means a majority, or nearly all, or all, or an amount in the range of about 51% to about 100%. Additionally, the examples herein are for illustrative purposes only and are presented for purposes of explanation and not limitation.

[0026] According to some embodiments of the principles described herein, a multi-view display is provided. Figures 2A and 2B show side views of an example multi-view display 100 according to embodiments consistent with the principles described herein. The multi-view display 100 comprises a multi-view backlight 110. The multi-view backlight 110 is configured to emit light as directional light beams 102 having different principal angular directions. The different principal angular directions of the directional light beams 102 correspond to different respective view directions of the multi-view image. Figures 2A and 2B show the directional light beams 102 as multiple radiating arrows drawn pointing away from a second (or bottom) surface 110'' of the multi-view backlight 110. In particular, the directional light beams are configured to converge at points in a convergence plane 120 that correspond to the locations of the different views of the multi-view image. The convergence plane 120 represents an optimal viewing position for a user. In particular, the convergence plane 120 represents a plane in which the user's line of sight should be placed to obtain an optimal view of the multi-view image. As shown in FIGS. 2A and 2B, the converging plane 120 is a plane parallel to the first (or top) surface 110′ of the multi-view backlight 110. As shown in FIG.

[0027] The multi-view display 100 further comprises an array of light valves 140. In various embodiments, different types of light valves may be used as the light valves 140 of the light valve array, including, but not limited to, one or more of a liquid crystal light valve, an electrophoretic light valve, and an electrowetting based light valve. The array of light valves 140 is configured to modulate the directional light beam 102 as different views of the multi-view image at the convergence plane 120.

[0028] The distance d between the multi-view backlight 110 and the array of light valves 140 is configured to be adjustable to shift the corresponding position of the convergence plane 120 relative to the multi-view display 100. FIG. 2B shows a side view of a multi-view display 100 with the convergence plane 120 shifted relative to FIG. 2A in one example, according to an embodiment consistent with principles described herein. In the illustrated view, the distance d represents the distance between the bottom surface 110″ of the multi-view backlight 110, which emits the directional light beam 102, and the light valves 140. In other embodiments, the distance d can represent the distance between the top surface 110′ of the multi-view backlight 110 and the array of light valves 140. Returning to FIG. 2B, the distance d between the multi-view backlight 110 and the array of light valves 140 has been adjusted from a smaller distance d1, shown in FIG. 2A, to a larger distance d2, shown in FIG. 2B. Correspondingly, the position d' of the convergence plane 120 relative to the multi-view display 100 has shifted from a distance d1' from the multi-view display 100 to a distance d2' from the multi-view display 100. Thus, the distance d' between the convergence plane 120 and the multi-view display 100 may be increased to move the convergence plane 120 further away from the multi-view display 100, or may be decreased to move the convergence plane 120 closer to the multi-view display 100.

[0029] Since the convergence plane 120 represents the optimal viewing position of the multi-view image in any configuration, shifting the convergence plane 120 up or down from the multi-view display 100 maintains the attributes of the multi-view image between different positions of the convergence plane 120, as shown in Figures 2A and 2B. In particular, the inter-view spacing i between different views of the multi-view image is configured to be constant as a function of an adjustable distance d between the multi-view backlight 110 and the light valves 140 of the light valve array. Similarly, the inter-view distance i is also configured to be constant as a function of the corresponding position d' (e.g., d1' and d2') of the convergence plane 120 relative to the multi-view display 100. Thus, as shown in Figures 2A and 2B, the inter-view distance i of the multi-view image is the same for the convergence plane 120 of Figure 2B located at a distance d2' from the multi-view display 100 as it is for the convergence plane 120 of Figure 2A located at a distance d1' from the multi-view display 100.

[0030] The inter-view spacing i at the convergence plane 120 is commensurate with the interocular distance of a user of the multi-view display 100. This feature makes the convergence plane 120 an optimal viewing distance for the user. When the convergence plane 120 is moved as described above, the inter-view distance i remains commensurate with the inter-eye distance of the user, ensuring that the user can continue to see a three-dimensional image provided by a combination of two different views (one for each eye) at each position of the convergence plane 120.

[0031] The distance d between the multi-view backlight 110 and the array of light valves 140 can be adjusted in a variety of ways. In some embodiments, the adjustment can include mechanical movement of the multi-view backlight 110 relative to the array of light valves 140. The mechanical movement can be produced by a mechanical, electrical, electromechanical, or other type of actuator configured to move the multi-view backlight 110 away from or closer to the light valve array.

[0032] In some embodiments, the distance between a multi-view backlight of a multi-view display and an array of light valves 140 can be adjusted using multiple multi-view backlights. FIGS. 3A-3B show a multi-view display 100 including a pair of multi-view backlights in one example, according to embodiments consistent with principles described herein. In particular, as shown in FIGS. 3A-3B, the multi-view backlight 110 is a first multi-view backlight 110 of the multi-view backlight pair. The first multi-view backlight 110 is positioned adjacent to the array of light valves 140 as shown. The multi-view display 100 shown in FIGS. 3A-3B further includes a second multi-view backlight 115 of the pair of multi-view backlights. The second multi-view backlight 115 is located on a side of the first multi-view backlight 110 opposite the side of the first multi-view backlight 110 adjacent to the light valves 140. Thus, the first multi-view backlight 110 is located between the second multi-view backlight 115 and the array of light valves 140 of the multi-view display 100. Furthermore, the first and second multi-view backlights 110, 115 have different positions relative to the light valve array, as shown.

[0033] According to various embodiments, the second multi-view backlight 115 may be substantially similar to the multi-view backlight 110 described above. In particular, the second multi-view backlight 115 is configured to provide directional light beams 116 that converge in the second converging plane 120'' at points that correspond to the positions of the different views of the multi-view in the second converging plane 120''. Furthermore, the first multi-view backlight 110 transmits the directional light beams 116 provided by the second multi-view backlight 115. Thus, the directional light beams 116 provided by the second multi-view backlight 115 are emitted through the thickness of the first multi-view backlight 110 and modulated as directional emitted light by the array of light valves 140.

[0034] The multi-view backlights of the multi-view display 100 of Figures 3A and 3B may be selectively activated (one at a time) to provide a multi-view image. Because the first and second multi-view backlights 110, 115 are positioned at different distances d1 and d2 from the array of light valves 140, selective activation of each of the first and second multi-view backlights 110, 115 changes the distance d between the multi-view backlights and the light valves 140 of the light valve array. As previously mentioned, selective activation of the first and second multi-view backlights 110, 115 shifts the distance d' of the convergence plane 120 because adjusting the distance d between the light valve array and the backlight of the multi-view display 100 shifts the distance d' of the convergence plane 120 from the light valve array.

[0035] 3A and 3B illustrate the selective activation of the first and second multi-view backlights 110, 115 of the multi-view display 100 and the resulting shift of the convergence plane 120 of the multi-view display 100 from a distance d1' to a distance d2'. In both figures, the active backlights are shown in solid lines and the inactive backlights are shown in dashed lines. Thus, referring again to FIG. 3A, as shown, the first multi-view backlight 110 is active while the second multi-view backlight 115 is inactive. Thus, the distance between the active first multi-view backlight 110 and the light valve 140 is d1, and correspondingly, the convergence plane 120 of the multi-view display is a first convergence plane 120' corresponding to the active first multi-view backlight 110. Moreover, the first convergence plane 120' is located at a distance d1' from the light valve 140 in FIG. 3A.

[0036] In FIG. 3B, the first multi-view backlight 110 is deactivated, whereas the second multi-view backlight 115 is active. Thus, the distance between the active second multi-view backlight 115 and the light valve array is d2. The convergence plane 120 of the multi-view display 100 is then shifted to a second convergence plane 120″ resulting from the distance d2 between the active second multi-view backlight 115 and the light valve array. Furthermore, as shown, according to various embodiments, the position of the second convergence plane 120″ relative to the multi-view display 100 is different from the position of the first convergence plane 120′. That is, the distance d2′ is different from the distance d1′ by selectively activating either the first multi-view backlight 110 or the second multi-view backlight 115.

[0037] In some embodiments, the multi-view backlight 110 includes a light guide 111. FIG. 4 illustrates a multi-view display 100 with a multi-view backlight 110 including the light guide 111 in one example, according to an embodiment consistent with principles described herein. The light guide 111 is configured to guide light as guided light 104 (i.e., guided light beam 104) along the length of the light guide. For example, the light guide 111 can include a dielectric material configured as a light guide. The dielectric material can have a first refractive index greater than a second refractive index of a medium surrounding the dielectric light guide. The refractive index difference is configured to promote total internal reflection of the guided light 104, for example, according to one or more guided modes of the light guide 111.

[0038] In some embodiments, the light guide 111 may be a slab or plate of optical waveguide (i.e., a planar light guide) that includes a stretched, substantially planar sheet of optically transparent dielectric material. The substantially planar sheet of dielectric material is configured to direct the guided light 104 using total internal reflection. According to various examples, the optically transparent material of the light guide 111 may include or be composed of any of a variety of dielectric materials, including, but not limited to, one or more of various types of glasses (e.g., silica 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 111 may further include a cladding layer (not shown) on at least a portion of the surfaces of the light guide 111 (e.g., one or both of the first and second surfaces). According to some examples, the cladding layer may be used to further promote total internal reflection.

[0039] Further, according to some embodiments, the light guide 111 is configured to guide the guided light 104 by total internal reflection at a non-zero propagation angle between a first surface 111′ (e.g., a front or top surface or side surface) and a second surface 111″ (e.g., a back or bottom or side surface) of the light guide 111. In particular, the guided light 104 propagates by reflection or “bouncing” between the first surface 111′ and the second surface 111″ of the light guide 111 at a non-zero propagation angle. In some embodiments, the guided light 104 may include multiple guided light beams having different colors of light. The guided light beams of the multiple guided light beams having different colors of light may be guided by the light guide 111 at different color-specific non-zero propagation angles, respectively. It should be noted that for ease of illustration, the non-zero propagation angles are not shown in FIG. 4. However, the thick arrow indicating the propagation direction 103 indicates the general propagation direction of the guided light 104 along the length of the light guide in FIG. 4.

[0040] The multi-view backlight 110 further comprises a plurality of multi-beam elements 112. The plurality of multi-beam elements 112 are spaced apart from one another along the length of the light guide. The plurality of multi-beam elements 112 may be disposed on or adjacent to a first (or "top") surface 111' of the light guide 111. In some embodiments, the plurality of multi-beam elements 112 may be disposed on a second (or "bottom") surface 111'' of the light guide 111, for example, as shown in FIG. 4. In some embodiments, the plurality of multi-beam elements 112 may be disposed within the light guide 111 between the first surface 111' and the second surface 111''.

[0041] The multibeam element 112 of the multi-view backlight 110 is configured to scatter light from the light guide 111 as multiple directional light beams having principal angular directions corresponding to the view directions of the multi-view image. According to various embodiments, the multibeam element 112 can include any of several different structures configured to scatter a portion of the guided light 104. For example, the different structures can include, but are not limited to, a diffraction grating, a micro-reflective element, a micro-refractive element, or various combinations thereof. In some embodiments, a multibeam element 112 including a diffraction grating is configured to diffractively scatter the guided light portion as multiple directional light beams having different principal angular directions. In other embodiments, a multibeam element 112 including a micro-reflective element is configured to reflectively scatter the guided light portion as multiple directional light beams, or a multibeam element 112 including a micro-refractive element is configured to scatter the guided light portion as multiple directional light beams by or using refraction (i.e., refractively scatter the guided light portion).

[0042] In some embodiments, the size of the multibeam element 112 corresponds to the size of the light valve 140 of the multiview display 100. As used herein, "size" may be defined in any of a variety of ways, including but not limited to length, width, or area. For example, the size of the light valve 140 may be the length of the light valve 140, and the corresponding size of the multibeam element 112 may also be the length of the multibeam element 112. In another example, size may refer to an area, such that the area of ​​the multibeam element 112 may correspond to the area of ​​the light valve 140.

[0043] In some embodiments, a head tracker may be used with the multi-view display 100 as part of a multi-view display system. The head tracker may be configured to determine a distance between the multi-view display 100 and a user. For example, the head tracker may be configured to determine a distance between the multi-view display 100 and the user's head, more specifically, the distance between the multi-view display 100 and one or both of the user's eyes. Using the determined distance between the multi-view display 100 and the user, the multi-view display system may adjust the distance between the multi-view backlight 110 and the array of light valves 140 to shift the convergence plane to the user's eye level in accordance with the principles described herein. Thus, the multi-view display system may adjust the convergence plane based on the user's movements to follow the user's eye line to ensure an optimal viewing experience.

[0044] According to various embodiments, any of a variety of devices, systems, and circuits that provide head tracking (or equivalently tracking of a user's position) can be used as a head tracker in a multi-view display system. For example, in some embodiments, the head tracker can include a camera configured to capture an image of the user relative to the screen of the multi-view display 100. Additionally, the head tracker can include an image processor (or a general-purpose computer programmed as an image processor) configured to determine the position of the user in the captured image relative to the screen of the multi-view display 100. The position of the user relative to the screen of the multi-view display 100 can be determined by the image processor from the captured image using various techniques, including, for example, but not limited to, image recognition or pattern matching. The output of the head tracker can be used to modify the operation of the multi-view display system. For example, the determined position of the user can be provided to an actuator to adjust the distance d between the multi-view backlight 110 and the array of light valves 140 of the multi-view display 100 of FIGS. 2A and 2B. In another example, the determined position of the user may be provided to the multi-view display 100 of Figures 3A and 3B to selectively activate and / or deactivate one of the first multi-view backlight 110 and the second multi-view backlight 115. Other examples of head tracker implementations may include any of a variety of two-dimensional (2D) and three-dimensional (3D) object tracking systems.

[0045] According to some embodiments of the principles described herein, a multi-view display system 200 is provided. FIG. 5 illustrates a block diagram of the multi-view display system 200 in one example according to an embodiment consistent with the principles described herein. The multi-view display system 200 comprises a multi-view backlight 210. The multi-view backlight 210 is substantially similar to the multi-view backlight 110 of the multi-view display 100 described above. The multi-view backlight 210 is thus configured to provide directional light beams 202 having different principal angular directions corresponding to different viewing directions of the respective different views of the multi-view image. The multi-view backlight 210 can be formed as a "slab" or substantially flat block of substrate including two substantially parallel and opposing planar surfaces (i.e., a top surface and a bottom surface).

[0046] The multi-view display system 200 further comprises an array of light valves 240. The array of light valves 240 is substantially similar to the array of light valves 140 of the multi-view display 100 described above. Different types of light valves may therefore be used as light valves in the light valve array, including but not limited to one or more of liquid crystal light valves, electrophoretic light valves, and electrowetting-based light valves. The array of light valves 240 is configured to modulate directional light beams to provide a multi-view image at a convergence plane 220 of the multi-view display system. The convergence plane 220 is a plane parallel to the light valve array and represents an optimal viewing position for a user. In particular, the convergence plane 220 represents a plane where the user's line of sight should be placed to obtain an optimal view of the multi-view image.

[0047] The multi-view display system 200 further comprises a head tracker 250. The head tracker 250 is substantially similar to the head tracker used in the multi-view display 100 described above. The head tracker 250 is therefore configured to determine the distance of the user from the multi-view display system 200. Any of a variety of devices, systems, and circuits that provide head tracking, including any of a variety of two-dimensional (2D) and three-dimensional (3D) head tracking systems, can be used as the head tracker of the multi-view display system 200. For example, the head tracker 250 can comprise one or both of a plurality of cameras configured to determine the user distance using disparity estimation and a time-of-flight sensor configured to determine the distance using the time of flight of a signal reflected by the user. The signal emitted by the time-of-flight sensor can include, but is not limited to, an acoustic signal (e.g., an acoustic range finder) and an optical signal (e.g., emitted by a laser). In another example, the head tracker 250 can comprise an optical sensor configured to measure the distance to a plurality of points using laser light reflected from one or more objects in the scanned area. For example, the head tracker 250 may include an Intel RealSense® 3D camera that combines a 2D camera, a second infrared camera, and an infrared laser projector. The 2D camera is configured to capture a 2D image of the scan area, and the infrared laser projector and the second infrared camera cooperate as a distance sensor to collect distance information within the scan area. Intel RealSense® and Intel® are registered trademarks of Intel Corporation, Santa Clara, Calif., USA.

[0048] The distance between the multi-view backlight 210 and the light valve array 240 is configured to be adjustable according to the determined user distance to shift the position of the convergence plane 220 to correspond to the determined user distance. The shifting of the convergence plane 220 based on the user's distance from the multi-view backlight 210 operates substantially as shown and described in Figures 2A and 2B in relation to the multi-view display 100. In particular, to increase the distance between the convergence plane 220 and the light valve array, the distance between the multi-view backlight 210 and the array of light valves 240 is increased. Similarly, to decrease the distance between the convergence plane 220 and the array of light valves, the distance between the multi-view backlight 210 and the light valve array is decreased.

[0049] Since the convergence plane 220 represents an optimal viewing position for the multi-view image in any configuration, shifting the convergence plane 220 up or down from the multi-view display 100 as shown in Figures 2A and 2B preserves the attributes of the multi-view image between different positions of the convergence plane 220. In particular, the inter-view spacing of the different views in the convergence plane 220 is configured to be constant as the convergence plane 220 is shifted. Furthermore, the inter-view spacing within the convergence plane 220 is commensurate with the interocular distance of the user. As a result, a user of the multi-view display system 200 whose line of sight remains on the convergence plane 220 as the convergence plane 220 changes position can have a substantially similar viewing experience across various positions of the convergence plane 220.

[0050] In some embodiments, the multi-view display system 200 comprises multiple multi-view backlights. A multi-view display system comprising multiple multi-view backlights is substantially similar to the multi-view display 100 of FIGS. 3A and 3B. Thus, the first multi-view backlight is disposed at a first distance from the array of light valves 240, and the second multi-view backlight is disposed at a second distance from the light valve array, the second distance being different from the first distance. In particular, the first multi-view backlight is disposed between the light valve array and the second multi-view backlight. Since each multi-view backlight is disposed at a different distance from the array of light valves 240, the convergence plane 220 of the multi-view display system 200 has a position depending on which multi-view backlight is active. Thus, one of the first and second multi-view backlights is selectively activated to shift the position of the convergence plane 220.

[0051] In some embodiments, the multi-view backlight 210 includes a light guide 211. The light guide 211 is configured to guide light in a propagation direction along the length of the light guide as guided light. The light guide 211 may be substantially similar to the light guide 111 of the multi-view display 100 described above. According to various embodiments, the light guide 211 may be configured to guide the guided light using total internal reflection. Furthermore, the guided light may be guided at a non-zero propagation angle by or within the light guide 211. In some embodiments, the guided light may be collimated or may be a collimated light beam. In particular, in various embodiments, the guided light may be collimated according to or to have a collimation factor σ.

[0052] The multi-view backlight 210 further comprises a plurality of multi-beam elements 212 spaced apart from one another along the length of the light guide. The plurality of multi-beam elements 212 are substantially similar to the multi-beam elements 112 of the multi-view display 100 described above. The plurality of multi-beam elements 212 are configured to scatter a portion of the guided light as directional emission light associated with the multi-view display system 200. The directional emission light comprises a plurality of directional light beams 202 having principal angular directions corresponding to respective different viewing directions of the multi-view display system 200. The plurality of multi-beam elements 212 may be disposed on or within a surface of the light guide 211.

[0053] A size of one or more of the multiple multibeam elements corresponds to a size of a light valve 240 of the light valve array. In some embodiments, the size of the multibeam element 212 corresponds to the size of the light valve such that the size of the multibeam element is between about fifty percent (50%) and about two hundred percent (200%) of the size of the light valve.

[0054] According to some embodiments of the principles described herein, a method 300 of multi-view display operation is disclosed. FIG. 6 shows a flowchart of a method 300 of multi-view display operation in one example according to embodiments consistent with the principles described herein. The method 300 includes emitting light 310 using a multi-view backlight as directional light beams having different principal angular directions corresponding to the respective different view directions of the multi-view image. The multi-view backlight is substantially similar to the multi-view backlight 110 of the multi-view display 100 described above. The directional light beams converge at points in a convergence plane corresponding to the positions of the different views of the multi-view image. The convergence plane is a plane parallel to the multi-view backlight and represents an optimal viewing position for a user. In particular, the convergence plane represents a plane where the user's line of sight should be located to obtain an optimal view of the multi-view image.

[0055] The method 300 further includes a step 320 of modulating the directional light beams using an array of light valves to provide different views of the multi-view image at the convergence plane. The array of light valves is substantially similar to the array of light valves 140 of the multi-view display 100 described above. Thus, different types of light valves may be used as light valves in the light valve array, including but not limited to one or more of liquid crystal light valves, electrophoretic light valves, and electrowetting-based light valves. Different ones of the directional light beams having different principal angular directions are configured to pass through and be modulated by different ones of the light valves in the light valve array.

[0056] The method 300 further includes a step 330 of adjusting a distance between the multiview backlight and the light valve array to shift a position of the convergence plane relative to the multiview display. The shifting of the position of the convergence plane based on the adjustment of the distance between the multiview backlight and the light valve array operates substantially as shown and described in Figures 2A and 2B with respect to the multiview display 100. In particular, to increase the distance between the convergence plane and the multiview display, the distance between the multiview backlight and the light valve array is increased. Similarly, to decrease the distance between the convergence plane and the multiview display, the distance between the multiview backlight and the light valve array is decreased.

[0057] In some embodiments, emitting light using a multi-view backlight 310 includes directing the light in a light guide as guided light. The light may be directed at a non-zero propagation angle between opposing inner surfaces of the light guide. Emitting light using a multi-view backlight 310 further includes scattering a portion of the guided light from the light guide as a directional light beam using an array of multi-beam elements. The multi-beam elements of the array may be substantially similar to the multi-beam elements 122 of the multi-view display 100. Thus, the multi-beam elements may include one or more of a diffraction grating configured to diffractively scatter a portion of the guided light, a micro-reflecting structure configured to reflectively scatter a portion of the guided light, and a micro-refractive structure configured to refractively scatter a portion of the guided light. Additionally, the multi-beam elements may have a size comparable to the size of a light valve of the light valve array.

[0058] In some embodiments, adjusting the distance between the multi-view backlight and the light valve array includes mechanically moving the multi-view backlight relative to the light valve array. The mechanical movement can be produced by a mechanical, electrical, electromechanical, or other type of actuator configured to move the multi-view backlight away from or closer to the light valve array.

[0059] In some embodiments, the method 300 further includes using a head tracker to determine a distance of a user from the multi-view display and adjusting a distance between the multi-view backlight and the light valve array to shift a convergence plane position to correspond to the determined user distance. The head tracker may be substantially similar to the head tracker of the multi-view display 100 described above. Thus, any of a variety of devices, systems, and circuits that provide head tracking, including any of a variety of two-dimensional and three-dimensional head tracking systems, may be used as the head tracker of the multi-view display. Additionally, the output of the head tracker may be used to modify the operation of the multi-view display. For example, the determined user position may be provided to an actuator to adjust the distance between the multi-view backlight and the light valve array of the multi-view display (or to selectively activate one or more multi-view backlights in the multi-view display) to shift the convergence plane.

[0060] In some embodiments, using a head tracker to determine the distance of the user from the multi-view display may include one or both of the following: using multiple cameras to capture images of the user and using disparity estimation to determine the distance of the user from the multi-view display; and using a time-of-flight sensor to determine the distance of the user from the multi-view display from a time of propagation of a signal emitted by the time-of-flight sensor and reflected by the user. The signal emitted by the time-of-flight sensor may include, but is not limited to, an acoustic signal and an optical signal (e.g., emitted by a laser).

[0061] Thus, examples and embodiments of a multi-view display with adjustable convergence plane and a method of multi-view display operation have been described. It should be understood that the above examples are merely illustrative of some of the many specific examples which represent the principles described herein. Clearly, those skilled in the art could readily devise numerous other configurations without departing from the scope defined by the following claims. [Explanation of symbols]

[0062] 10,100 Multi-view Display 12 Screens 14 Views 16 View Directions 20 Light Beam 102,116,202 Directional light beam 103 Propagation direction 104 Waveguide Light 110,115,210 Multi-view backlight 110' first (or top) surface 110” Second (or bottom) surface 111,211 Light Guide 111' First Side 111” Second Side 112,212 Multi-beam elements 120 Convergence Surface 120' First Converging Plane 120” Second Converging Plane 140,240 Light bulb 200 Multi-view Display System 250 Head Tracker 300 ways 310 Light Emitting Step 320 Modulating a directional light beam 330 Steps to Adjust Distance d,d1,d2,d',d1',d2' distance O Origin i Interview Spacing View Distance θ,φ angular component θ elevation angle φ Azimuth σ Collimation factor

Claims

1. 1. A multi-view display, comprising: a multi-view backlight configured to emit light as directional light beams having different principal angular directions corresponding to respective different view directions of a multi-view image, the directional light beams being configured to converge at points in a convergence plane corresponding to positions of the different views of the multi-view image; an array of light valves configured to modulate the directional light beams as the different views of the multi-view image at the convergence plane; a distance between the multi-view backlight and the light valve array is configured to be adjustable to shift a corresponding position of the convergence plane relative to the multi-view display; A multi-view display, wherein the multi-view backlight is a first multi-view backlight, the convergence plane is a first convergence plane of the multi-view display, and the multi-view display further comprises a second multi-view backlight configured to provide a directional light beam that converges in the second convergence plane at a point corresponding to a position of the different views of the multi-view image at the second convergence plane, and the position of the second convergence plane relative to the multi-view display is different from the position of the first convergence plane.

2. 2. The multi-view display of claim 1 , configured such that inter-view spacing between the different views of the multi-view image is constant as a function of the adjustable distance between the multi-view backlight and the light valve array and the corresponding position of the convergence plane.

3. A multiple view display as claimed in claim 2 , wherein the inter-view spacing in the convergence plane is commensurate with the interocular distance of a user of the multiple view display.

4. The multi-view display of claim 1 , wherein adjusting the distance between the multi-view backlight and the light valve array comprises mechanical movement of the multi-view backlight relative to the light valve array.

5. 2. The multi-view display of claim 1, wherein the first multi-view backlight is disposed between the second multi-view backlight and the light valve array, the first multi-view backlight transmits the directional light beam provided by the second multi-view backlight, and adjusting the distance between the multi-view backlight and the light valve array includes selectively activating one of the first multi-view backlight and the second multi-view backlight to provide the multi-view image within each of the first and second convergence planes.

6. The multi-view backlight comprises: a light guide configured to direct light in a direction of propagation along a length of the light guide; 2. The multi-view display of claim 1, comprising: a plurality of multi-beam elements spaced apart from one another along a length of the light guide, one multi-beam element of the plurality of multi-beam elements having a size corresponding to a size of a light valve of the light valve array, and configured to scatter a portion of the guided light from the light guide as the directional light beam.

7. 7. The multi-view display of claim 6, wherein the multi-beam element comprises one or more of a diffraction grating, a micro-reflective element, and a micro-refractive element optically connected to the light guide, the diffraction grating configured to diffractively scatter the portion of the guided light, the micro-reflective element configured to reflectively scatter the portion of the guided light, and the micro-refractive element configured to refractively scatter the portion of the guided light.

8. 2. A multi-view display system comprising the multi-view display of claim 1, further comprising a head tracker configured to determine a distance between the multi-view display and a user, the distance between the multi-view backlight and the light valve array being adjusted in accordance with the determined distance between the multi-view display and the user, and configured to shift the convergence plane position to correspond to a position of the user relative to the multi-view display.

9. 1. A multi-view display system, comprising: a multi-view backlight configured to provide directional light beams having different principal angular directions corresponding to different viewing directions of respective different views of the multi-view image; an array of light valves configured to modulate the directional light beams as the different views of the multi-view image at a convergence plane of the multi-view display system to provide the multi-view image at the convergence plane; a head tracker configured to determine a distance of a user from the multi-view display system; a distance between the multi-view backlight and the light valve array is configured to be adjustable according to the determined user distance, shifting a position of the convergence plane to correspond to the determined user distance; A multi-view display system, wherein the multi-view backlight is a first multi-view backlight of the multi-view display system at a first distance from the light valve array, the multi-view display system further comprising a second multi-view backlight at a second distance from the light valve array, the first distance being different from the second distance, and the convergence plane position being configured to be shifted by selectively activating one of the first multi-view backlight and the second multi-view backlight.

10. 10. The multi-view display system of claim 9, wherein the inter-view spacing of the different views in the convergence plane is configured to remain constant when the convergence plane is shifted, and the inter-view spacing within the convergence plane is commensurate with the interocular distance of the user.

11. The multi-view backlight comprises: a light guide configured to direct light in a direction of propagation along a length of the light guide; 10. The multiple view display system of claim 9, comprising: a plurality of multi-beam elements spaced apart from one another along a length of the light guide, one multi-beam element of the plurality of multi-beam elements having a size corresponding to a size of a light valve of the light valve array, and configured to scatter a portion of the guided light from the light guide as the directional light beam.

12. 10. The multi-view display system of claim 9, wherein the head tracker comprises one or more of a plurality of cameras configured to determine user distance using disparity estimation and a time-of-flight sensor configured to determine user distance using a time of propagation of a signal reflected by the user.

Images