CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] N/A

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] N/A

BACKGROUND

[0003] Electronic displays are a nearly ubiquitous medium for communicating information to users of a wide variety of devices and products. Most commonly employed electronic displays include the cathode ray tube (CRT), plasma display panels (PDP), liquid crystal displays (LCD), electroluminescent displays (EL), organic light emitting diode (OLED) and active matrix OLEDs (AMOLED) displays, electrophoretic displays (EP) and various displays that employ electromechanical or electrofluidic light modulation (e.g., digital micromirror devices, electrowetting displays, etc.). Generally, electronic displays may be categorized as either active displays (i.e., displays that emit light) or passive displays (i.e., displays that modulate light provided by another source). Among the most obvious examples of active displays are CRTs, PDPs and

OLEDs/ AMOLED s. Displays that are typically classified as passive when considering emitted light are LCDs and EP displays. Passive displays, while often exhibiting attractive performance characteristics including, but not limited to, inherently low power consumption, may find somewhat limited use in many practical applications given the lack of an ability to emit light.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] 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, where like reference numerals designate like structural elements, and in which: [0005] Figure 1 A illustrates a perspective view of a multiview display in an example, according to an embodiment consistent with the principles described herein. [0006] Figure IB illustrates a graphical representation of the angular components of a light beam having a particular principal angular direction corresponding to a view direction of a multiview display in an example, according to an embodiment consistent with the principles described herein.

[0007] Figure 2A illustrates a cross-sectional view of a multiview backlight in an example, according to an embodiment consistent with the principles described herein. [0008] Figure 2B illustrates a plan view of a multiview backlight in an example, according to an embodiment consistent with the principles described herein.

[0009] Figure 2C illustrates a plan view of a multiview backlight in an example, according to another embodiment consistent with the principles described herein.

[0010] Figure 3 A illustrates a cross-sectional view of a multiview backlight in another example, according to an embodiment of the principles described herein.

[0011] Figure 3B illustrates a plan view of a multiview backlight in another example, according to an embodiment consistent with the principles described herein. [0012] Figure 4A illustrates a cross-sectional view of a multiview backlight having a diffuser in an example, according to an embodiment consistent with principles described herein.

[0013] Figure 4B illustrates a cross-sectional view of a multiview backlight having a diffuser in another example, according to an embodiment consistent with the principles described herein.

[0014] Figure 5 illustrates a block diagram of a multiview display in an example, according to an embodiment consistent with the principles described herein.

[0015] Figure 6 illustrates a flow chart of a method of multiview backlight operation in an example, according to an embodiment of the principles described herein. [0016] Certain examples and embodiments have other features that are one of in addition to and in lieu of the features illustrated in the above-referenced figures. These and other features are detailed below with reference to the above-referenced figures. DETAILED DESCRIPTION

[0017] Examples and embodiments in accordance with the principles described herein provide a multiview backlight and a multiview display employing the multiview backlight that utilize an aperture mask having apertures to selectively control or restrict light emitted by an array of active emitters. In particular, embodiments consistent with the principles described herein provide a multiview backlight employing an array of active emitters and an aperture mask having an aperture configured to restrict the emitted light from a corresponding active emitter of the active emitter array. The aperture of the aperture mask, in turn, is configured to define a size of an effective emitter represented by light passing through the aperture. As a result, the effective emitter provided by the aperture of the aperture mask has a predetermined size and provides a plurality of directional light beams. According to various embodiments, different principal angular directions of the directional light beams provided by the effective emitter correspond to directions of various different views of a multiview display or equivalently of a multiview image displayed by the multiview display.

[0018] According to various embodiments, the predetermined size is provided by a size of the aperture may be selected based on an actual size of the active emitter along with a spacing between the active emitter and a location of the effective emitter. Further, in some embodiments, selective activation of the active emitter array and a plurality of active emitters disposed between the active emitters of the active emitter array may facilitate reconfiguration of the multiview backlight to provide either directional light beams associated with a multiview display or emitted light consistent with a two- dimensional (2D) display. As a result, a multiview display that employs the multiview backlight may be switched between a multiview mode and a 2D mode by the selective activation of the active emitter array and the plurality of active emitters dispose between active emitters of the active emitter array.

[0019] Herein a ‘two-dimensional display’ or ‘2D display’ is defined as a display configured to provide a view of an image that is substantially the same regardless of a direction from which the image is viewed (i.e., within a predefined viewing angle or range of the 2D display). A conventional liquid crystal display (LCD) found in may smart phones and computer monitors are examples of 2D displays. In contrast and herein, a ‘multiview display’ is defined as an electronic display or display system configured to provide different views of a multiview image in or from different view directions. In particular, the different views may represent different perspective views of a scene or object of the multiview image. Uses of multiview backlighting and multiview displays applicable to the display of multiview images described herein include, but are not limited to, mobile telephones (e.g., smart phones), watches, tablet computes, mobile computers (e.g., laptop computers), personal computers and computer monitors, automobile display consoles, cameras displays, and various other mobile as well as substantially non-mobile display applications and devices.

[0020] Figure 1 A illustrates a perspective view of a multiview display 10 in an example, according to an embodiment consistent with the principles described herein. As illustrated in Figure 1A, the multiview display 10 comprises a screen 12 configured to display a multiview image to be viewed. The screen 12 may be a display screen of a telephone (e.g., mobile telephone, smart phone, etc.), a tablet computer, a laptop computer, a computer monitor of a desktop computer, a camera display, or an electronic display of substantially any other device, for example.

[0021] The multiview display 10 provides different views 14 of the multiview image in different view directions 16 relative to the screen 12. The view directions 16 are illustrated 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 termination of the arrows (i.e., depicting the view directions 16); and only four views 14 and four view directions 16 are illustrated, all by way of example and not limitation.

Note that while the different views 14 are illustrated in Figure 1 A as being above the screen, the views 14 actually appear on or in a vicinity of the screen 12 when the multiview image is displayed on the multiview display 10. Depicting the views 14 above the screen 12 is only for simplicity of illustration and is meant to represent viewing the multiview display 10 from a respective one of the view directions 16 corresponding to a particular view 14. A 2D display may be substantially similar to the multiview display 10, except that the 2D Display is generally configured to provide a single view (e.g., one view similar to view 14) of a displayed image as opposed to the different views 14 of the multiview image provided by the multiview display 10. [0022] A view direction or equivalently a light beam having a direction corresponding to a view direction of a multiview display generally has a principal angular direction given by angular components {6, </)}, by definition herein. The angular component is referred to herein as the ‘elevation component’ or ‘elevation angle’ of the light beam. The angular component is referred to as the ‘azimuth component’ or ‘azimuth angle’ of the light beam. By definition, the elevation angle #is an angle in a vertical plane (e.g., perpendicular to a plane of the multiview display screen while the azimuth angle ^ is an angle in a horizontal plane (e.g., parallel to the multiview display screen plane).

[0023] Figure IB illustrates a graphical representation of the angular components { 6, (f>} of a light beam 20 having a particular principal angular direction corresponding to a view direction (e.g., view direction 16 in Figure 1 A) of a multiview display in an example, according to an embodiment consistent with the principles described herein. In addition, the light beam 20 is emitted or emanates from a particular point, by definition herein. That is, by definition, the light beam 20 has a central ray associated with a particular point of origin within the multiview display. Figure IB also illustrates the light beam (or view direction) point of origin O.

[0024] The term ‘multiview’ as used in the terms ‘multiview image’ and ‘multiview display’ is defined herein as a plurality of views representing different perspectives or including angular disparity between views of the view plurality. In addition, herein the term ‘multiview’ explicitly includes two or more different views (e.g., a minimum of three views and generally more than three views), by definition herein. In some embodiments, ‘multiview display’ as employed herein may be used to explicitly distinguish from a stereoscopic display that includes only two different views to represent a scene or an image. Note however, while multiview images and multiview displays may include more than two views, by definition herein, multiview images may be viewed (e.g., on a multiview display) as a stereoscopic pair of images by selecting only two of the multiview views to view at a time (e.g., one view per eye).

[0025] A ‘multiview pixel’ is defined herein as a set of view pixels representing pixels of views in each of a similar plurality of different views of a multiview display. In particular, a multiview pixel may have an individual view pixel corresponding to or representing a particular view pixel in each of the different views of the multiview image. Moreover, the view pixels of the multiview pixel are so-called ‘directional pixels’ in that each of the view pixels is associated with a predetermined view direction of a corresponding one of the different views, by definition herein. Further, according to various examples and embodiments, the different view pixels of a multiview pixel may have equivalent or at least substantially similar locations or coordinates in each of the different views. For example, a first multiview pixel may have individual view pixels corresponding to pixels located at {xi, yi} in each of the different views of a multiview image, while a second multiview pixel may have individual view pixels corresponding to pixels located at { 2, 2} in each of the different views, and so on. View pixels, in turn, are equivalent to light valves of an array of light valves of the multiview display, by definition herein. As such, the terms ‘view pixel’ and ‘light valve’ may be used interchangeably herein unless a distinction is necessary for proper understanding.

[0026] Herein, an ‘active emitter’ is defined as an active source of light (e.g., an optical emitter configured to produce and emit light when activated). As such, an active emitter does not receive light from another source of light, by definition. Instead, the active emitter directly generates light when activated. The active emitter may be activated by applying a power source such as a voltage or a current, by definition herein. For example, the active emitter may comprise an optical emitter such as a light emitting diode (LED) that emits light when activated or turned on. The LED may be activated by applying a voltage to terminals of the LED, for example. In particular, herein the light source may be substantially any active source of light or comprise substantially any active optical emitter including, but not limited to, one or more of a light emitting diode (LED), a laser, an organic light emitting diode (OLED), a polymer light emitting diode, a plasmabased optical emitter, a miniLED (mLED), and a microLED (pLED). The light produced by the active emitter may have a color (i.e., may include a particular wavelength of light), or may be a plurality or range of wavelengths (e.g., polychromatic light or white light). Different colors of light provided or produced by an active emitter may include, but are not limited to, primary colors (e.g., red, green, blue), for example. By definition herein, a ‘color emitter’ is an active emitter that provides light having a color. In some embodiments, the active emitter may comprise a plurality of active emitters. For example, the active emitter may include a set or group of active emitters. In some embodiments, at least one of the active emitters in the set or group of active emitters may generate light having a color, or equivalently a wavelength, that differs from a color or wavelength of light produced by at least one other optical emitter of the plurality.

[0027] Further by definition herein, the term ‘broad-angle’ as in ‘broad-angle emitted light’ is defined as light having a cone angle that is greater than a cone angle of the view of a multiview image or multiview display. In particular, in some embodiments, the broad-angle emitted light may have a cone angle that is greater than about sixty degrees (60°). In other embodiments, the broad-angle emitted light cone angle may be greater than about fifty degrees (50°), or greater than about forty degrees (40°). For example, the cone angle of the broad-angle emitted light may be about one hundred twenty degrees (100°). Alternatively, the broad-angle emitted light may have an angular range that is greater than plus and minus forty-five degrees (e.g., > ± 45°) relative to the normal direction of a display. In other embodiments, the broad-angle emitted light angular range may be greater than plus and minus fifty degrees (e.g., > ± 50°), or greater than plus and minus sixty degrees (e.g., > ± 60°), or greater than plus and minus sixty-five degrees (e.g., > ± 65°). For example, the angular range of the broad-angle emitted light may be greater than about seventy degrees on either side of the normal direction of the display (e.g., > ± 70°). A ‘broad-angle backlight’ is a backlight configured to provide broad-angle emitted light, by definition herein.

[0028] In some embodiments, the broad-angle emitted light cone angle may defined to be about the same as a viewing angle of an LCD computer monitor, an LCD tablet, an LCD television, or a similar digital display device meant for broad-angle viewing (e.g., about ± 40-65°). In other embodiments, broad-angle emitted light may also be characterized or described as diffuse light, substantially diffuse light, non-directional light (i.e., lacking any specific or defined directionality), or as light having a single or substantially uniform direction.

[0029] Further, as used herein, the article ‘a’ is intended to have its ordinary meaning in the patent arts, namely ‘one or more’. For example, ‘an active emitter’ means one or more arrays and as such, ‘the active emitter’ means ‘the active emitter(s)’ herein. Also, any reference herein to ‘top’, ‘bottom’, ‘upper’, ‘lower’, ‘up’, ‘down’, ‘front’, back’, ‘first’, ‘second’, ‘left’ or ‘right’ is not intended to be a limitation herein. Herein, the term ‘about’ when applied to a value generally means within the tolerance range 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 otherwise expressly specified. Further, the term ‘substantially’ as used herein means a majority, or almost all, or all, or an amount within a range of about 51% to about 100%. Moreover, examples herein are intended to be illustrative only and are presented for discussion purposes and not by way of limitation. [0030] According to some embodiments of the principles described herein, a multiview backlight is provided. Figure 2A illustrates a cross-sectional view of a multiview backlight 100 in an example, according to an embodiment consistent with the principles described herein. Figure 2B illustrates a plan view of a multiview backlight 100 in an example, according to an embodiment consistent with the principles described herein. Figure 2C illustrates a plan view of a multiview backlight 100 in an example, according to another embodiment consistent with the principles described herein. The multiview backlight 100 is configured to emit or provide directional light beams 102 having directions corresponding to view directions of a multiview display that employs the multiview backlight 100 or equivalently view directions of a multiview image displayed by the multiview display, according to various embodiments. In particular, the directional light beams 102 may be or represent a lightfield, in some embodiments. The cross-sectional view of Figure 2A also illustrates an array of light valves 104 that may be part of the multiview display that employs the multiview backlight 100, by way of example and not limitation.

[0031] The multiview backlight 100 illustrated in Figures 2A-2C comprises an array of active emitters 110 disposed on a substrate 101. The active emitters 110 are configured to provide emitted light 102'. In some embodiments (e.g., as illustrated), the substrate 101 may be a planar substrate. According to various embodiments, active emitters 110 of the active emitter array are spaced apart from one another on the substrate 101. In particular, active emitters 110 of the active emitter array may be spaced apart by a spacing that corresponds to a spacing between multiview pixels or equivalently sets of light valves of a light valve array that represent multiview pixels of a multiview display that employs the multiview backlight 100, as described in more detail below. For example, Figure 2A illustrates a spacing t/between adjacent active emitters 110 that corresponds to a spacing D between multiview pixels 106 or equivalently sets of the light valves 104 of the array of light valves 104.

[0032] In some embodiments, the active emitters 110 may be arranged in a two- dimensional (2D) array (e.g., a rectangular array) having rows and columns. For example, Figure 2B illustrates the first active emitter array arranged as a 2D array in which the active emitters 110 are disposed on the planar substrate as a rectangular array of spaced-apart active emitters 110. Figure 2B also illustrates the spacing d between active emitters 110 that corresponds to the spacing of multiview pixels 106. In some embodiments, the active emitter spacing as well as the multiview pixel spacing may be in each of two orthogonal directions of the 2D array, e.g., as illustrated in Figure 2B.

[0033] In another example, active emitters 110 of the active emitter array may be arranged as plurality of parallel columns distributed across the substrate 101, as illustrated in Figure 2C. When arranged as parallel columns the spacing d may be between adjacent columns, as illustrated in Figure 2C. In some embodiments (e.g., as illustrated in Figure 2C), the columns may be ‘slanted columns’, i.e., columns that are slanted relative to one or both of an edge of the substrate 101 or relative to an arrangement of light valves in a light valve array (not illustrated in Figure 2C). In yet other embodiments (not illustrated), active emitters 110 of the first active emitter array may be arranged as a one-dimensional (ID) such as a linear array.

[0034] As illustrated in Figures 2A-2C, the multiview backlight 100 further comprises an aperture mask 120. The aperture mask 120 comprises a plurality of apertures 122 spaced apart from one another by a distance or spacing corresponding to a spacing between multiview pixels 106 or equivalently sets of light valves 104 representing multiview pixels 106 of a multiview display. According to various embodiments, each aperture 122 of the aperture mask 120 is aligned with and configured to restrict light emitted by a corresponding active emitter 110 of the active emitter array to define an effective emitter 110' at the aperture 122. In Figure 2 A, the effective emitter 110' is illustrated as a dashed line spanning the aperture 122. According to various embodiments, the effective emitter 110' (and also the aperture 122) has a size 5 between one quarter and two times a size S of a light valve 104 of the multiview display. For example, the size s of the aperture 122 and also the effective emitter 110' may be about 50 micrometers (pm). Light emitted by the effective emitter 110' at the aperture 122 comprises the plurality of directional light beams 102 having directions corresponding to view directions of the multiview display, according to various embodiments.

[0035] In particular, the aperture 122 is configured to provide the effective emitter 110' from or using the emitted light 102' provided by the corresponding active emitter 110 of the active emitter array. That is, the aperture 122 is configured to receive the emitted light 102' and restrict an extent of the emitted light 102' that passes through the aperture 122 to provide light as or in the form of the effective emitter 110'. In turn, the effective emitters 110' provided by the apertures 122 of the aperture mask 120 are configured to provide or emit light that mimics light emitted by an active emitter having the size of the individual effective emitters 110'. For example, the effective active emitters 110' may be provided at or in a vicinity of a surface of the aperture mask 120. Further, as illustrated in Figure 2A, the various effective emitters 110' at the aperture mask surface are configured to emit the light comprising the directional light beams 102 having directions corresponding to the view directions of a multiview display that employs the multiview backlight 100, according to various embodiments.

[0036] As described above, the apertures 122 of the aperture mask 120 are each configured to provide the effective emitter 110' having a predetermined size. In particular, the aperture 122 is configured to restrict an apparent area of size of the corresponding active emitter 110 of the active emitter array such that the effective emitter 110' has the predetermined size between one quarter and two times the size of light valve 104, as noted above. In embodiments in which the active emitters 110 are arrange in parallel columns, the predetermined size of effective emitters 110' provided by the aperture 122 of the aperture mask 120 is in a width direction across the parallel columns. For example, the predetermined size may be in an x-direction where the parallel columns are substantially in the -direction, e.g., as illustrated in Figure 2C. In some of these embodiments, the apertures 122 of the aperture mask 120 may be configured to provide another size of the effective emitters 110' along a length of the columns that is comparable to a spacing between active emitters 110 along the length of the column, as illustrated in Figure 2C. In some embodiments, a size of an aperture 122 of the aperture plurality of the aperture mask 120 is less than a size of the corresponding active emitter 110 of the active emitter array, e.g., as illustrated in Figure 2A.

[0037] In some embodiments, the apertures 122 may have a two-dimensional (2D) shape. For example, a shape of the aperture 122 may be a square or a rectangle. Figure 2B illustrates square-shaped apertures 122, for example. In embodiments in which the active emitters 110 are arranged in parallel columns, the apertures 122 may comprise slots extending in a direction along the parallel columns. Figure 2C illustrates apertures 122 of the aperture mask 120 comprising slots, for example.

[0038] According to some embodiments, the aperture mask 120 may comprise a sheet or layer of material with apertures 122 formed in and penetrating through the layer. The layer of material may be a continuous layer, for example. Figure 2A illustrates the aperture mask 120 as a continuous layer of material, by way of example and not limitation. In some embodiments, the aperture mask 120 may comprises a layer of lightblocking material configured to block light except within a boundary of an aperture 122 of the aperture mask 120. In some of these embodiments, the light-blocking material may comprise a light absorber such that the aperture mask 120 is an absorptive aperture mask. In other embodiments, the light-blocking material may comprise a reflective lightblocking material (i.e., a reflector) and the aperture mask 120 may be a reflective aperture mask 120 configured to reflect light that does not pass through the apertures 122. A reflective aperture mask 120 may increase a brightness of the multiview backlight by effectively recycling light rejected by the apertures 122. In yet other embodiments, the aperture mask 120 may be both absorptive and reflective, e.g., partially absorptive and partially reflective.

[0039] In other embodiments, the aperture mask 120 may comprise a plurality of discrete segments or sections having apertures 122 formed therein. In some embodiments, the discrete segments or sections of the plurality may be aligned in a layer to provide the aperture mask 120, for example. In particular, there may be a discrete segment or segment of the aperture mask 120 corresponding to each of the active emitters 110 of the active emitter array, the discrete segment or section providing the aperture 122 that is aligned with the corresponding active emitter 110. Further areas between the discrete segments or sections may be light-transmissive. That is, the light-blocking material of the aperture mask 120 in these embodiments may be absent or at least substantially absent in the areas between the discrete segments or sections. As such, the area between the discrete segments or sections may be configured to pass light without substantial restriction, in these embodiments. In some embodiments, the segments or sections may comprise the light-blocking material described above including either a light absorber or a reflective light-blocking material, as described above.

[0040] Figure 3 A illustrates a cross-sectional view of a multiview backlight 100 in another example, according to an embodiment consistent with the principles described herein. Figure 3B illustrates a plan view of a multiview backlight 100 in another example, according to an embodiment consistent with the principles described herein. As illustrated in Figures 3A-3B, the multiview backlight 100 comprises the array of active emitters 110 and the aperture mask 120. Further, the aperture mask 120 illustrated in Figures 3A-3B comprises discrete segments or sections of light-blocking material aligned with active emitters 110 of the active emitter array, i.e., as opposed to a continuous or substantially continuous light-blocking layer, as illustrated Figure 2A-2C. Figure 3A-3B also illustrates the array of light valves 104, e.g., light valves 104 that are part of the multiview display that employs the multiview backlight 100.

[0041] Referring to Figures 3 A-3B, in some embodiments, the multiview backlight 100 may further comprise a plurality of active emitters 130 disposed between the active emitters 110 of the active emitter array. As with the array of active emitters 110, active emitters 130 of the active emitter plurality are also configured to emit light as emitted light. The emitted light provided by the array of active emitters 110 in combination with the emitted light provided by the plurality of active emitters 130 may be or represent broad-angle light, according to some embodiments. In some embodiments, the plurality of active emitters 130 may be disposed on the substrate 101 between the active emitters 110 of the active emitter array, e.g., as illustrated in Figure 3 A.

[0042] In some embodiments, the active emitters 130 of the active emitter plurality are disposed about halfway between the active emitters 110 of the active emitter array. In other embodiments, a spacing between active emitters 130 of the active emitter plurality and also between the active emitters 130 and active emitters 110 of the active emitter array is an integer multiple of a spacing between light valves of a light valve array of a multiview display, e.g., light valves 104. For example, the active emitters 130 of the active emitter plurality may be spaced apart from one another and from the active emitters 110 of the first active emitter array by a distance equal to a spacing between or pitch of the light valves 104 of the light valve array. When the active emitters 110, 130 of the active emitter array and active emitter plurality are arranged as columns, columns of the active emitter plurality are disposed between and may alternate with the columns of the active emitter array. In various embodiments, the columns of active emitters 130 of the active emitter plurality may have different spacings such as, but not limited to, halfway between columns of active emitters 110 of the active emitter array and a spacing corresponding to the light valve pitch.

[0043] Figure 3A illustrates an active emitter 130a of the active emitter plurality that is located about halfway between active emitters 110 of the active emitter array. Figure 3A also illustrates the active emitters 130 of the active emitter plurality having a spacing or pitch corresponding to the spacing or pitch of the light valves 104 in the light valve array, by way of example and not limitation.

[0044] Figure 3B illustrates the active emitters 130 of the active emitter plurality disposed between the active emitters 110 of the active emitter array in both a row direction and a column direction across the substrate 101. In Figure 3B, some of the active emitters 130 of the active emitter plurality are between active emitters 110 of the active emitter array both along rows and columns of the active emitter array, as illustrated. Further, Figure 3B illustrates additional active emitters 130 of the active emitter plurality distributed across the substrate 101, e.g., such that active emitters 110, 130, in combination, have a pitch corresponding to the light valve pitch (at least in the x- direction, as illustrated). Note that while not explicitly illustrated, the active emitters 110 may be arranged in columns and the aperture mask 120 comprising segments or sections of light-blocking material may include apertures 122 that are or form slots across the segments or sections that are aligned with active emitters 110, e.g., slots as illustrated in Figure 2C.

[0045] Note that while not explicitly illustrated, the active emitters 110, 130 may be arranged as columns with the active emitters 130 of the active emitter plurality disposed between columns of active emitters 110 of the active emitter array across the substrate 101, e.g., as illustrated in Figure 2C. In addition, also as illustrated in Figure 2C, the columns of active emitters 110, 130 as slanted columns. Further, as with the active emitters 130 of Figure 3B, the columns of active emitters 130 of the active emitter plurality may have a spacing corresponding to the light valve pitch. In some embodiments, the active emitters, 110 130 having a spacing corresponding to the light valve pitch may provide a substantially uniform source of illumination when active emitters 110, 130 of both the active emitter array and the active emitter plurality are activated to emit light. Also, the apertures 122 of the aperture mask 120 may be slots when the active emitters 110, 130 are arranged as columns.

[0046] According to some embodiments, the active emitters 110 of the active emitter array are configured to provide emitted light during a first or ‘multiview’ mode of the multiview backlight 100. In particular, during the multiview mode the active emitters 110 are activated or turned on and emit light as illustrated by cross-hatching, while the active emitters 130 of the active emitter plurality (if present) are inactivated or turned off and do not emit light. As such, effective emitters 110' provided by the aperture mask 120 from the light emitted by the active emitter array during the multiview mode provide the directional light beams 102, e.g., to be modulated by the light valves 104 as the multiview image.

[0047] In some embodiments, active emitters 110, 130 of both the active emitter array and the active emitter plurality are configured to provide emitted light as combined emitted light 108 during a second or ‘two-dimensional’ (2D) mode of the multiview backlight 100. In particular, during the 2D mode both the active emitters 110 and the active emitters 130 are activated and emit light. As illustrated in Figures 3A-3B using cross-hatching, active emitters 110 of the active emitter array and active emitters 130 of the active emitter plurality are activated and provide the combined emitted light 108 during the 2D mode. The emitted light provided by the active emitters 110 may pass through apertures 122 of the aperture mask 120, while emitted light from the active emitters 130 may pass through light-transmissive areas between the spaced-apart segments or sections of the aperture mask 120 to provide the combined emitted light 108. As such, during the 2D mode the combined emitted light 108 may be modulated by light valves 104 of the light valve array to provide a 2D image, according to various embodiments. In general, in contrast to the directional light beams 102, the combined emitted light 108 is non-directi onal.

[0048] As mentioned above, Figure 2A and 3 A both illustrate an array of light valves 104 as well as multiview pixels 106 for the purpose of facilitating discussion herein. The illustrated light valve array may be part of a multiview display that employs the multiview backlight 100, for example. As illustrated, light valves 104 of the light valve array are configured to modulate the directional light beams 102, e.g., as illustrated in Figure 2A. Further, different ones of the directional light beams 102 having different principal angular directions pass through and may be modulated by different ones of the light valves 104 in the light valve array, as illustrated. The light valves 104 are also configured to modulate the combined emitted light 108 illustrated in Figure 3 A provided by the active emitters 110, 130 when activated in combination, for example during a 2D mode of the multiview backlight 100.

[0049] By definition herein, a light valve 104 of the light valve array may correspond to a view pixel of the multiview display, while a set of the light valves 104 or set of view pixels may correspond to a multiview pixel 106. In particular, a different set of light valves 104 of the light valve array may be configured to receive and modulate the directional light beams 102 from different ones of the active emitters 110 of the first active emitter array. As such, there may be one unique set of light valves 104 (or multiview pixel 106) for each active emitter 110, e.g., as illustrated in Figure 2A with respect to active emitters 110. In various embodiments, different types of light valves may be employed as the light valves 104 of the light valve array including, but not limited to, one or more of liquid crystal light valves, electrophoretic light valves, and light valves based on electrowetting.

[0050] Further, a size S of a light valve 104 may correspond to an aperture size of the light valve 104 in the light valve array, as illustrated in Figure 2 A. In other examples, the light valve size may be defined as a distance (e.g., a center-to-center distance) between adjacent light valves 104 of the light valve array. For example, an aperture of the light valves 104 may be smaller than the center-to-center distance between the light valves 104 in the light valve array. Thus, the light valve size may be defined as either the size of the light valve 104 or a size corresponding to the center-to-center distance between the light valves 104, among other definitions. Also, in Figure 2A, a size 5 of the effective emitters 110' provided by the apertures 122 of the aperture mask 120 from light emitted by the active emitter array is illustrated as comparable to the light valve size S.

[0051] In some embodiments (e.g., as illustrated in Figure 2A), an inter-emitter distance (e.g., center-to-center distance) between a pair of adjacent active emitters 110 may be equal to an inter-pixel distance (e.g., a center-to-center distance) between a corresponding pair of adjacent multiview pixels 106, e.g., represented by light valve sets. For example, as illustrated in Figure 2A, a center-to-center distance d between an active emitter 110a of the first active emitter array and another active emitter 110b of the active emitter array is substantially equal to a center-to-center distance D between a first light valve set 104a and the second light valve set 104b, where each light valve set 104a, 104b represents a multiview pixel 106. In other embodiments (not illustrated), the relative center-to-center distances of pairs of columns of active emitters 110a, 110b and corresponding light valve sets 104a, 104b may differ, e.g., the pairs of columns of active emitters 110a, 110b may have an inter-element spacing (i.e., center-to-center distance d) that is one of greater than or less than a spacing (i.e., center-to-center distance £>) between light valve sets representing multiview pixels 106. Further, when columns of active emitters 110 are used, the multiview image provided by a multiview display that employs the multiview backlight 100 may be a so-called ‘horizontal-parallax-only’ (HPO) multiview image having a plurality of views in only one direction, i.e., in a direction perpendicular to or across the columns.

[0052] According to some embodiments, an active emitter 110, 130 of one or both of the active emitter array and the active emitter plurality may comprise a mini light emitting diode (miniLED or mLED). Herein, a miniLED is defined as a light emitting diode having dimensions that are less than about 1.0 millimeters (mm). For example, a miniLED may have dimensions in the range of about 75 micrometers (pm) to about 500 pm or about 100 pm to about 300 pm. By comparison, microLED (pLED) may be defined as a microscopic light emitting diode (LED) having microscopic dimensions that are less than 100 pm. For example, a pLED may have a size of about 10-50 pm. In some embodiments, the miniLED may comprise a plurality of either miniLEDs or pLEDs that, when combined, function together as a unit as the active emitter 110, 130. [0053] In some embodiments, a miniLED may comprise a plurality of different regions, each of the different regions (or equivalently the plurality of miniLEDs or pLEDs) being configured to provide a different color of light. For example, the miniLED may comprise three regions, a first region being configured to provide red light, a second region being configured to provide green light, and a third region being configured to provide blue light. As such, the miniLED may be configured to selectably provide red, green, or blue light or any combination thereof (e.g., white light).

[0054] According to some embodiments, an active emitter 110, 130 of one or both of the first active emitter array and the active emitter plurality may comprise an organic light emitting diode (OLED). As defined herein, an OLED is an emitter having an emissive electroluminescent film or layer comprising an organic compound configured to emit light in response to an electric current or similar electrical stimulus. As with the miniLED, the OLED may comprise a plurality of OLEDs that, when combined, function together as a unit as the active emitter 110, 130. Further, in some embodiments, the OLED may comprise a plurality of different regions, each of the different regions being configured to provide a different color of light. For example, the OLED may comprise three regions, a first region being configured to provide red light, a second region being configured to provide green light, and a third region being configured to provide blue light. As such, the OLED serving as the active emitter 110, 130 may be configured to provide by selection red, green, or blue light or any combination thereof (e.g., white light). In yet other embodiments, another type of active optical emitter may be used as the active emitter 110 such as, but not limited to, a high intensity LED and a quantum dot LED.

[0055] In some embodiments, the active emitters 110, 130 may be configured to provide light that is substantially monochromatic having a particular color (i.e., the light may include a particular wavelength of light). In other embodiments, the active emitter 110, 130 may be configured to provide polychromatic light such as, but not limited to, white light, that includes a plurality or range of wavelengths. For example, the active emitter 110, 130 may be configured to provide one or more of red light, green light, blue light, or a combination thereof. In another example, the active emitter 110 may be configured to provide light that is substantially white light (i.e., the active emitter 110, 130 may be a white LED or white OLED). In some embodiments, active emitters 110, 130 may comprise a blue or ultraviolet (UV) emitter (e.g., LED or OLED) in combination with a phosphor element aligned with each emitter. In another embodiments, a phosphor plate that spans multiple active emitters 110, 130 may be employed. In other embodiments, white light may be provided by active emitters 110, 130 comprising sets of red, green, and blue LEDs that in combination provide white light.

[0056] In some embodiments, the active emitter 110, 130 may include a microlens, a diffraction grating, or another optical film or component configured to provide one or both of collimation (e.g., according to a collimation factor) and polarization control of emitted light or equivalently of the directional light beams 102. The micro-lens, the diffraction grating, or the other optical film or component may also or alternatively be configured to control a direction of the directional light beams 102. Alternatively, one or both of the collimation and polarization control may be provided by an optical layer or film between the active emitter arrays and the light valve array, for example.

[0057] The active emitters 110 of the active emitter array and active emitters 130 of the active emitter plurality may be independently controlled, activated, or powered to provide local dimming and also to enable switching between directional light beam production by the effective active emitters using light emitted by active emitter array and broad-angle light provided by a combination of the active emitters 110, 130 of the active emitter array and active emitter plurality, according to some embodiments. In particular, in some embodiments, the active emitters 110 of the active emitter array may be configured to provide by selective activation the directional light beams 102, e.g., during the multiview mode of the multiview backlight. Similarly, the active emitters 110, 130 of both the active emitter array and the active emitter plurality may be configured to provide emitted light by selective activation during a 2D mode of the multiview backlight 100. In some embodiments, selective activation of the active emitter 110, 130 may be used in different zones or regions of the multiview backlight 100 to provide a 2D mode in a first zone (e.g., a 2D zone) or region and simultaneously provide a multiview mode in a second zone (multiview zone) or region, for example.

[0058] Referring again to Figures 2A and 3 A, the multiview backlight 100 may further comprise a planar substrate, e.g., the substrate 101, in some embodiments. In particular, the active emitters 110 of the active emitter array as well as the active emitters 130 of active emitter plurality (when present) may be disposed on and spaced apart across a surface of the substrate 101, as described above. The substrate 101 may further comprise electrical interconnects to provide power to the active emitters 110, 130. In some embodiments, the substrate 101 is configured to be optically transparent or at least substantially optically transparent (i.e., may be a planar transparent substrate). For example, the substrate 101 may comprise an optically transparent material capable of transmitting light from a first side to a second side of the substrate 101. Further, electrical interconnects may be optically transparent, in some embodiments. Moreover, a combination of the active emitter array and the active emitter plurality, when present, and the substrate 101 (e.g., along with the electrical interconnects) may be configured to be optically transparent, in some embodiments.

[0059] In some embodiments, the multiview backlight 100 may further comprise a diffuser configured to diffuse light emitted by one or both of the active emitters 110 and the active emitters 130. In some embodiments, the diffuser may be disposed in or adjacent to the apertures 122 of the aperture mask 120, for example. The diffuser disposed in or adjacent to the apertures 122 may serve to spread the light of the effective emitter 110'. Spreading the light of the effective emitter 110' may improve intensity uniformity of the directional light beams 102, for example. In another embodiment, the diffuser may comprise a diffuser layer that extends across an extent of the multiview backlight 100. In some embodiments, the diffusers as a diffuser layer may be disposed between the aperture mask 120 and the active emitters 110 of the active emitter array as well as between the aperture mask 120 and the active emitters 130 of the active emitter plurality, when present. In other embodiments, the diffuser layer may be disposed at or adjacent to an output of the aperture mask 120. In these embodiments, the diffuser may provide diffusion or homogenization of light emitted by the active emitters 110, 130. For example, the diffuser may both on or both of improve intensity uniformity of the directional light beams 102 (e.g., during a multiview mode) and improve intensity uniformity of emitted light provided by the combined active emitters 110, 130 (e.g., during a 2D mode). In addition to providing intensity uniformity through homogenization, the diffuser may also facilitate positioning the aperture mask 120 further away from the active emitters 110, 130 without incurring possible Moire effects.

[0060] Figure 4A illustrates a cross-sectional view of a portion of a multiview backlight 100 having a diffuser 140 in an example, according to an embodiment consistent with principles described herein. Figure 4B illustrates a cross-sectional view of a portion of a multiview backlight 100 having a diffuser 140 in another example, according to an embodiment consistent with the principles described herein. As illustrated in Figures 4A and 4B, the portion of the multiview backlight 100 comprises an active emitter 110 of the active emitter array disposed on a portion of the substrate 101, a portion of the aperture mask 120, and a portion of the array of light valves 104, e.g., as illustrated in Figures 2A-2C. The multiview backlight 100 illustrated in Figures 4A-4B further comprises the diffuser 140. As illustrated in Figure 4 A, the diffuser 140 is disposed in apertures 122 of the aperture mask 120, while Figure 4B illustrates the diffuser 140 as a diffusion layer disposed between the active emitter 110 and the aperture mask 120. In other embodiments (not illustrated), the diffuser 140 as a diffusion layer may be disposed between the aperture mask 120 and the light valve array.

[0061] In some embodiments, active emitters 110 are driven in a manner to ensure a constant brightness or a substantially constant brightness of the emitted light during each of the multiview mode and the 2D mode. For example, active emitters 110 during the multiview mode (or in a multiview zone) may be driven with a relatively higher drive currents or voltages when compared to drive currents or voltages used to drive the active emitters 110, 130. The relatively higher drive currents or voltages may be chosen to provide the constant brightness of the emitted light during each of the multiview mode and the 2D mode.

[0062] In accordance with some embodiments of the principles described herein, a multiview display is provided. The multiview display is configured to display a multiview image, according to various embodiments. Figure 5 illustrates a block diagram of a multiview display 200 in an example, according to an embodiment consistent with the principles described herein.

[0063] As illustrated, the multiview display 200 comprises an array of effective emitters 210. Each effective emitter 210 of the effective emitter array comprises an active emitter 212 and an aperture mask 214. According to various embodiments, the active emitter 212 is configured to emit light and may be disposed on a planar substrate of the multiview display 200. The aperture mask 214 has an aperture configured to define a size of the effective emitter 210 by restricting light emitted by the active emitter 212. That is, the aperture of the aperture mask 214 defines the size of the effective emitter 210 by restricting an extent of the light emitted by the active emitter 212 that passes through the aperture and therefore becomes or serves as the effective active emitter 210. According to some embodiments, the active emitter 212 of the effective emitter 210 may be substantially similar to the active emitter 110 of the array of active emitters 110 described above with respect to the multiview backlight 100. For example, the active emitters 212 may comprise, but are not limited to, a mini light emitting diode (miniLED), an organic light emitting diode (OLED), and another active optical emitter. In some embodiments, the miniLED, OLED, or other active optical emitter may have a size that is larger than the aperture of the aperture mask 214 of the effective emitter 210. In some embodiments, the aperture of the aperture mask 214 may be substantially similar to the aperture 122 of the aperture mask 120 of the above-described multiview backlight. In particular, each effective emitter 210 of the effective active emitter array is configured to provide emitted light 202 using light emitted by the active emitter 212 that passes through the aperture of the aperture mask 214.

[0064] As illustrated in Figure 5, the multiview display 200 further comprises an array of light valves 220 configured to modulate the emitted light 202 from the effective active emitter array and provide a displayed image. In particular, the displayed image may be the multiview image when the light valves 220 modulate directional light beams provided by the effective emitters 210, in some embodiments. In some embodiments, the light valves 220 may be substantially similar to the light valves 104, as described above. According to various embodiments, the size of the effective emitter 210 defined by the aperture of the aperture mask 214 is between one quarter and two times a size of a light valve 220 of the light valve array. Further, the emitted light 202 provided by each effective emitter 210 of the effective emitter array comprises directional light beams having directions corresponding to views of the multiview image. In some embodiments, a spacing between effective emitters 210 is an integer multiple of a spacing between light valves 220 of the light valve array. In particular, the effective emitter array may comprise effective emitters 210 spaced apart from one another by a distance corresponding to a spacing between multiview pixels of the multiview display. In these embodiments, he emitted light 202 from the various effective emitters 210 that comprises the plurality of directional light beams may be or represent a lightfield. Also in these embodiments, the displayed image provided by the modulation of the emitted light 202 from the effective emitters 210 may be the multiview image.

[0065] According to some embodiments, the multiview display 200 further comprises a set of active emitters 230 distributed between active emitters 212 of the effective emitters 210 of the effective emitter array. In some of these embodiments, a displayed image of the multiview display 200 provided by modulation of light emitted by a combination of the effective emitter array and the set of active emitters 230 dispersed between the effective emitters 210 of the effective emitter array may be a two- dimensional (2D) image. In some embodiments, the effective emitters 210 of the set of active emitters 230 may be spaced apart from one another and from adjacent effective emitters 210 of the effective emitter array by spacing corresponding to the light valve spacing, according to some embodiments. In some embodiments, the set of active emitters 230 may be substantially similar to the plurality of active emitters 130 of the multiview backlight, described above.

[0066] In particular, the active emitters 212 of the effective emitters 210 may be activated during a multiview mode of the multiview display 200. The multiview mode is illustrated on a left side of Figure 5 and activated active emitters 212 are illustrated using cross-hatching. During the multiview mode, the multiview display 200 may provide a multiview image. Alternatively, both the active emitters 212 of effective emitters 210 and the set of active emitters 230 dispersed between the effective emitters 210 of the effective emitter array may be activated to during a two-dimensional (2D) mode of the multiview display 200 to provide a 2D image. The 2D mode is illustrated on a right side of Figure 5. Arrows having dashed lines in Figure 5 illustrate modulated emitted light 202 (Multiview Mode) and modulated combined emitted light 202' (2D Mode). Crosshatching is employed in Figure 5 to illustrate activation of the active emitters of the effective emitters 210 during both the multiview mode and 2D mode as well as activation of the set of active emitters 230 dispersed between the effective emitters 210 during the 2D mode, but not during the multiview mode (i.e., no cross-hatching).

[0067] According to some embodiments, effective emitters 210 of the effective active emitter array are arranged in parallel columns, e.g., across the planar substrate. In these embodiments, aperture of the aperture mask 214 may comprise a slot aligned with and along the columns. Further, the size of effective emitters defined by the aperture of the aperture mask 214 may be in a width direction across the parallel columns, in these embodiments. In some embodiments, the aperture of the aperture mask 214 may be configured to determine another size of the effective emitters 210 along a length of the columns that is comparable to a spacing between active emitters along the length of the column, in some embodiments.

[0068] In accordance with some embodiments of the principles described herein, a method of multiview backlight operation is provided. Figure 6 illustrates a flow chart of a method 300 of multiview backlight operation in an example, according to an embodiment of the principles described herein. The method 300 of multiview backlight operation illustrated in Figure 6 comprises emitting 310 light using an array of active emitters disposed across a planar substrate. In some embodiments, the array of active emitters may be substantially similar to the array of active emitters 110, described above with respect to the multiview backlight 100. For example, active emitters of the active emitter array may be spaced apart by a spacing that corresponds to a spacing between multi view pixels of a multi view display.

[0069] The method 300 illustrated in Figure 6 further comprises restricting 320 emitted light from each active emitter of the active emitter array using aperture mask having an aperture aligned with each active emitter to define an effective emitter corresponding to each active emitter. In some embodiments, the aperture mask and aperture used in restricting 320 emitted light may be substantially similar to the aperture mask 120 and the aperture 122, respectively, described above with respect to the multiview backlight 100. In particular, the aperture mask and aperture may provide the effective emitter having a size that is between one quarter and two times a size of a light valve of the multiview display by restricting 320 the emitted light. In other embodiments, the effective emitter size may be between about fifty percent and one hundred fifty percent of the light valve size. In yet other embodiments, the effective emitter size may be comparable or even about equal to the light valve size.

[0070] In some embodiments, the active emitters of the active emitter array may be arranged in a two-dimensional (2D) array across the planar substrate. For example, active emitters of the active emitter array may be arranged in a 2D array having rows and columns of spaced-apart active emitters, as illustrated in and described above with respect to Figure 2B. In other embodiments, the active emitters of the active emitter array may be arranged in parallel columns across the planar substrate, e.g., as illustrated in and described above with respect to Figure 2C. In these embodiments, the size of effective emitters provided by the aperture of the aperture mask is a size in a width direction across the parallel columns. In some embodiments, the apertures of the aperture mask may provide another size of the effective emitters along a length of the columns that is comparable to a spacing between active emitters along the length of the column.

[0071] The method 300 of multiview backlight operation illustrated in Figure 6 further comprises emitting 330 light from the effective active emitters. In some embodiments, the light emitted 330 by the effective active emitters may comprise a plurality of directional light beams having directions corresponding to view directions of a multiview image or equivalently of a multiview display that provide the multiview image. The plurality of directional light beams may be or represent a lightfield, for example.

[0072] In some embodiments (not illustrated), the method of multiview backlight operation further comprises emitting light using a plurality of active emitters disposed between active emitters of the active emitter array. The plurality of active emitters may be substantially similar to the plurality of active emitters 130 of the above-described multiview backlight 100. In particular, in some embodiments, active emitters of the active emitter array may emit light during a multiview mode of the multiview backlight and active emitters of both the active emitter array and the plurality of active emitters disposed between the active emitters of the active emitter array may emit light during a two-dimensional (2D) mode of the multiview backlight.

[0073] In some embodiments (not illustrated), a method of multiview display operation is provided. The method of multiview display operation comprises the method 300 of multiview backlight operation. The method of multiview display operation further comprises modulating the emitted light from each of the effective emitters of the array of active emitters to provide a multiview image having different views in a plurality of different view directions. According to various embodiments, the emitted light from each of the effective emitters may comprise a plurality of directional light beams having directions corresponding to view directions of the multiview display.

[0074] In some embodiments (not illustrated), the method of display operation further comprises modulating combined emitted light from the effective emitters and from light emitted by both the effective emitters and active emitters of the set of active emitters. For example, the modulating the combined emitted may be performed during a two-dimensional (2D) mode of the multiview display, while modulation of light emitted by only the effective emitters may be performed during a multiview mode of the multiview display. Modulating the combined emitted light may provide a 2D image, according to various embodiments.

[0075] Thus, there have been described examples and embodiments of a multiview backlight, a multiview display, and a method of operating a multiview backlight that employ an aperture mask having apertures to provide effective emitters using light emitted by an array of active emitters. It should be understood that the abovedescribed examples are merely illustrative of some of the many specific examples that represent the principles described herein. Clearly, those skilled in the art can readily devise numerous other arrangements without departing from the scope as defined by the following claims.