Printing spacers in switchable lenticular arrays

Abstract

A three-dimensional (3D) display, system, and method of fabrication and use thereof are described. The display includes a display panel having subpixels of different colors and a parallax-generating optic configured to direct light from the display panel to a viewer. Spacers are deposited on a lenticular lens to prevent deformation and enhance optical performance. The spacers are loaded onto a contact plate and an adhesion promoter may be applied to ensure precise attachment. The contact plate is then aligned and pressed against the lens apexes, transferring the spacers to the apexes. Excess spacers are removed from troughs to maintain clarity. The spacers are cured in place, and a protective coating is applied to enhance durability.

Description

PRINTING SPACERS IN SWITCHABLE LENTICULAR ARRAYSBACKGROUND

[0001] Multiview displays, such as three-dimensional (3D) displays and switchable privacy displays, face challenges in maintaining high visual quality while ensuring efficient fabrication processes. These challenges include issues related to optical element deformation, unwanted visual artifacts, and complex manufacturing requirements. Addressing these issues is desirable to advance display technology and improve user experience.BRIEF DESCRIPTION OF THE DRAWINGS

[0002] 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:

[0003] Figure 1 shows a front-view schematic drawing of an example of a 3D display system that includes a 3D display.

[0004] Figure 2 shows a front-view drawing of an example of a display panel that includes an array of light-emitting diodes.

[0005] Figure 3 shows a front-view drawing of an example of a display panel that includes a multibeam backlight and a light valve array.

[0006] Figure 4 shows a front-view drawing of another example of a display panel.

[0007] Figure 5 shows a front-view drawing of an example of a parallaxgenerating optic that includes a lenticular lens array.

[0008] Figure 6 shows a cross-sectional view of the lenticular lens array of Figure 5.

[0009] Figure 7 shows a front-view drawing of an example of a parallaxgenerating optic that includes a parallax barrier having transmissive slits.

[0010] Figure 8 shows a cross-sectional view of the parallax barrier having transmissive slits of Figure 7.

[0011] Figure 9A shows a cross-sectional view of an example of a cell in a 3D display.

[0012] Figure 9B shows a cross-sectional view of an example of the cell in Figure 9A when pressure is applied.

[0013] Figures 10A-10D illustrate images of spacer deposition on a lenticular array.

[0014] Figure 11 A shows a cross-sectional view of an example of a display.

[0015] Figure 1 IB shows an example of a method for depositing spacers.

[0016] Figure 11C shows an example of another method for depositing spacers.

[0017] Figure 12 shows a flowchart of an example of a method for creating a 2D or 3D display.

[0018] 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

[0019] In a 3D display, a display panel having an array of subpixels may display an image in a variety of orientations. Such an autostereoscopic 3D display may be used in both portrait and landscape orientation (dual orientation). The autostereoscopic display may include a parallax-generating optic configured to direct light from the display panel to the viewer. However, liquid crystal display (LCD) and organic light-emitting diode (OLED) display panels have pixel patterns that are not generally designed to operate using such an optical element; detrimental effects may result that include high crosstalk between views, reduced 3D resolution, as well as visual artifacts such as angular and spatial Moire patterns due to the periodicity and regularity of the patterns. Moreover, OLED panels may use different emission areas for different color subpixels which may lead to unequal 3D viewing performance between the different color channels.

[0020] In some embodiments of 3D displays, spacers can be used together with an optical element to alleviate some of the multitude of resulting issues from the combination of elements above. For example, when lenticular arrays are used as optical elements, the lenticular array structures may be prone to deformation when coming into contact with an opposing cell wall. This deformation can lead to a loss of structuralintegrity and negatively impact the performance and visual output of the display. Preventing such deformation is thus desirable to maintain the functionality and longevity of the display.

[0021] In some embodiments, spherical spacers may be used to provide separation between the lenticular array and the cell wall to prevent deformation. Manufacturing of the structure, including the dispersion of microspheres, in this case may be ineffective and unreliable, and may further lead to aggregation of the spacers in the troughs between lenses if care is not taken during the manufacturing process. The aggregation may cause unwanted scattering and cross-talk, which can degrade the clarity and quality of the display, as well as introducing extra costs and processing complexities.

[0022] The preceding paragraphs are merely a summary of some technical details and challenges regarding autostereoscopic display systems. FIGS. 1-8 provide a more complete description of examples of the hardware of autostereoscopic displays. FIGS. 9- 11 provide a more complete description of optical elements with spacers and integration of such elements in a display.

[0023] As used herein, the article ‘a’ is intended to have its ordinary meaning in the patent arts, namely ‘one or more’. For example, ‘a subpixel’ means one or more subpixels and as such, ‘the subpixel’ means ‘the subpixel(s)’ herein. Also, any reference herein to ‘top’, ‘bottom’, ‘upper’, Tower’, ‘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 any value within 10% (e.g., 10%, 5%, 2%, 1%) of the value, or unless otherwise expressly specified. Further, the term ‘substantially’ as used herein means almost all or all of an amount within a numerical range of about 80% to about 100% of a value (or any value therebetween) or would otherwise be understood by one of skill in the art to encompass the term. For example, a substantially rectangular shape may deviate from a rectangular shape by being generally rectangular but having non-rectangular features, such as an inlet and / or projection. Moreover, examples herein are intended to be illustrative only and are presented for discussion purposes and not by way of limitation.

[0024] Figure 1 shows a schematic drawing of an example of a 3D display system 100 that includes an exploded view of a 3D display 102. The sign conventions shown in Figure 1 and used below assume that the 3D display 102 extends in an (x, ) plane, and that a z-axis extends away from the 3D display 102 and generally toward a viewer, along a direction that is orthogonal to a plane of the 3D display 102. Other sign conventions may also be used. The elements shown in Figure 1 may be contained within a single housing or some of the elements may be external to the housing.

[0025] As illustrated in Figure 1, the 3D display 102 may include a display panel 106 that may have an array of subpixels 108 configured to display an image according to stereo mapping coordinates associated with a viewer 104. The subpixels 108 may be located at subpixel locations in a grid having grid axes. Each subpixel 108 may generate light having a specified color. For example, the subpixels 108 may include red subpixels, green subpixels, and blue subpixels, which generate red light, green light, and blue light, respectively. Other color / wavelength schemes may also be used, such as the use of yellow subpixels. The subpixels 108 may be grouped into pixels, with each pixel including at least two subpixels 108 that produce light of different colors (e.g., 3 or 4 subpixels 108 of different colors may be used). Two possible configurations for the display panel 106 are described below and shown in Figures 2 and 3; other configurations may also be used.

[0026] Figure 2 shows a front-view drawing of an example of a display panel 106 A that includes an array 202 of light-emitting diodes 208, such as an array of organic light-emitting diodes. Each light-emitting diode 208 may correspond to a subpixel 108. The array 202 of light-emitting diodes 208 may include red light-emitting diodes 208R, green light-emitting diodes 208G, and blue light-emitting diodes 208B, which correspond to the red subpixels, green subpixels, and blue subpixels, respectively. A controller 118 (shown in Figure 1) may control the light-emitting diodes 208 individually or in one or more groups. Each light-emitting diode 208 may controllably generate light in response to an electrical signal provided by the controller 118 or by suitable light-emitting diode driving circuitry in communication with the controller 118. The controller 118 may cause a specified light-emitting diode 208 to be directly powered with a power that varies as a function of an intensity in a corresponding location in the image. The power delivered toa light-emitting diode 208 may optionally be pulse-width modulated at a modulation frequency that is greater than may be perceived by a human eye. Using pulse-width modulation may simplify a design of a light-emitting diode array controller, because such modulation may generate an arbitrary average power level from a relatively small number of instantaneous power levels by varying a duty cycle of the power so supplied. In some examples, the array 202 of light-emitting diodes 208 may be arranged in a rectangular or square repeating pattern over a surface area 210 of the array 202. For example, the array 202 may have grid axes 204 that are orthogonal to each other. In some examples, the grid axes 204 may be parallel to edges 206 of the array 202 of light-emitting diodes 208.

[0027] Figure 3 shows a front-view drawing of an example of a display panel 106B that includes a backlight 302 and a light valve array 304. Although Figure 3 shows the backlight 302 and the light valve array 304 as being separated, in practice, the backlight 302 and the light valve array 304 may be in contact or may be located as close together as is practical. The backlight 302 may provide illumination having a uniform or substantially uniform intensity over a surface area of the backlight 302. The backlight 302 may provide illumination having a relatively broad spectrum, such as including most or all of the visible portion of the electromagnetic spectrum. The backlight 302 may provide the illumination into a continuum of propagation angles toward the light valve array 304. The backlight 302 may provide unmodulated illumination to the light valve array 304. The light valve array 304 may include light valves 308 that are individually controllable or controllable in one or more groups by the controller 118. Each light valve 308 may controllably attenuate the illumination from the backlight, such as in response to an electrical signal provided by the controller 118 or by suitable light valve driving circuitry in communication with the controller 118. The light valves 308 may have color filters that allow only a portion of the electromagnetic spectrum to pass through the light valve 308. For example, the light valves 308 may include red light valves 308R that have a red filter that allows only red light to pass through the red light valves 308R, green light valves 308G that have a green filter that allows only green light to pass through the green light valves 308G, and blue light valves 308B that have a blue filter that allows only blue light to pass through the blue light valves 308B. Other color schemes and numbers of colors may also be used as above. Suitable light valve arrays 304 may include liquidcrystal light valves, electrophoretic light valves, and light valves based on electrowetting, and others. In some examples, the light valves 308 of the light valve array 304 may be arranged in a rectangular or square repeating pattern over a surface area 312 of the light valve array 304. For example, the light valve array 304 may have grid axes 204 that are orthogonal to each other. In some examples, the grid axes 204 may be parallel to edges 306 of the light valve array 304. The areas between the light valves 308, similar to the areas between the light-emitting diodes 208, may be designed to isolate light emission from the individual light valves 308. In some embodiments, optical elements such as reflective material may be used to guide light generated to and / or by the light valves 308, as well as the light-emitting diodes 208.

[0028] Figure 4 shows a front-view drawing of another example of a display panel. The subpixels 408 may include light-emitting diodes 208 of an array 202 of lightemitting diodes 208, as in Figure 2, or light valves 308 of a light valve array 304, as in Figure 3. Compared to a traditional red-green-blue subpixel arrangement, in which each pixel includes a red subpixel 408R (e.g., a light emitting diode that produces red light), a green subpixel 408G (e.g., a light emitting diode that produces green light), and a blue subpixel 408B (e.g., a light emitting diode that produces blue light), the pentile subpixel arrangement may include just two subpixels 408 (or light-emitting diodes) per pixel 402. The colors of the subpixels 408 in the display panel 106C may be arranged such that the missing color of a particular pixel 402 may be found in an adjacent pixel 404. Although some display panels may employ subpixel rendering in software, which may help smooth features in the image, the display panel 106C described herein may turn off subpixel rendering when the image is displayed. For a display panel 106C that turns off subpixel rendering when the image is displayed, a location of each subpixel 408 (e.g., each lightemitting diode) may be used for calculating the corresponding stereo mapping coordinate, rather than a center of a pixel 402 (e.g., the center of a specified group of subpixels 408 or a specified group of light-emitting diodes 208).

[0029] Referring again to Figure 1, the 3D display 102 may include a parallaxgenerating optic 110 that may direct light 112 corresponding to the image from the display panel 106 to the viewer 104. For example, the parallax-generating optic 110 may include a parallax optic or a parallax-generating optic. Two possible configurations forthe parallax-generating optic 110 are described below and shown in Figures 5 and 6 and in Figures 7 and 8. Other configurations may also be used. Each of the configurations of Figures 5 and 6 and Figures 7 and 8 may be used in combination with any of the configurations of Figures 2 and 3.

[0030] Figure 5 shows a front-view drawing of an example of a parallaxgenerating optic 110A (e.g., the parallax optic or parallax-generating optic) that includes a lenticular lens array 502. Figure 6 shows a cross-sectional view of the lenticular lens array 502 of Figure 5. The lenticular lens array 502 may include an array of thin cylindrical lenslets 604 positioned to receive light from the display panel 106 and at least partially focus the received light to direct the light to specified regions proximate the viewer’s eyes.

[0031] Figure 7 shows a front-view drawing of an example of a parallaxgenerating optic HOB (e.g., the parallax optic or parallax-generating optic) that includes a parallax barrier 702 having transmissive slits 804. Figure 8 shows a cross-sectional view of the parallax barrier 702 having transmissive slits 804 of Figure 7. The parallax barrier 702 may include an array of opaque strips 806 and thin transmissive slits 804 arranged to occlude portions of a displayed image in left and right viewing regions. The transmissive slits 804 may be spatially arranged to ensure that the left / right image portions are only visible in the corresponding left / right viewing regions for which they are intended. The parallax barrier 702 may be provided by a static physical layer in which the slits are precisely positioned, or electronically generated on an adaptive intermediate liquid crystal display layer.

[0032] The parallax-generating optic 110, including one of the lenticular lens array 502 or the parallax barrier 702 having transmissive slits 804, may be operable with the display panel 106, including one of the array 202 of light-emitting diodes 208 or the backlight 302 and light valve array 304. Thus, the parallax-generating optic 110 may have periodic features having the same dimensions and functionality as described herein.

[0033] As illustrated in Figures 5 and 6, the parallax-generating optic 110 may be invariant along an optical axis (OA) having a slant angle, a, relative to the grid axes 204. For example, the parallax-generating optic 110 may have transmissive features, such as the lenslets or the transmissive slits, that are invariant along the optical axis and areperiodic along an orthogonal axis that is orthogonal to the optical axis. As a specific example, the parallax-generating optic 110 may have transmissive slits that are parallel to the optical axis and are equally spaced along the orthogonal axis. As another specific example, the parallax-generating optic 110 may have cylindrical lenslets that are invariant in shape along the optical axis, have curvature along the orthogonal axis, and are equally spaced (e.g., with center-to-center spacing) along the orthogonal axis. The parallaxgenerating optic 110 may be angled by the slant angle, a, with respect to the grid axes 204, which may be parallel to edges 206 of the array 202 of light-emitting diodes 208 or edges 306 of the light valve array 304. For example, the slant angle may be within a specified angular tolerance of forty -five degrees, such as being between forty -four and forty-six degrees for a tolerance of + / - one degree, between forty-three and forty-seven degrees for a tolerance of + / - two degrees, between forty-two and forty-eight degrees for a tolerance of + / - three degrees, between forty-one and forty-nine degrees for a tolerance of + / - four degrees, between forty and fifty degrees for a tolerance of + / - five degrees, or another suitable angle or angular range. In some cases, the slant angle may be dependent on the type of display, which may include a liquid crystal light-emitting diode array or an organic light-emitting diode array with a pentile subpixel arrangement.

[0034] As illustrated in Figure 1, the 3D display 102 may include a material 114 disposed between the display panel 106 and the parallax-generating optic 110. In some examples, the material 114 may extend fully between the display panel 106 and the parallax-generating optic 110, such that a light ray originating at the display panel 106 passes only through the material 114 (and does not pass through any air or unfilled volume) before arriving at the parallax-generating optic 110. In other examples, the material 114 may occupy only a portion of the volume between the display panel 106 and the parallax-generating optic 110, such that a light ray originating at the display panel 106 passes through at least some of the material 114 and passes through a volume of air before arriving at the parallax-generating optic 110. The material 114 may have a refractive index denoted by n. The value of the refractive index n may be between about 1.3 and about 2, although other suitable values may also be used. Suitable materials may include glass, plastic, a transparent optical adhesive, and others. In some examples, the material 114 may be dispensed in a liquid form, then cured in place, such as by exposureto ultraviolet light or heat. In other examples, the material 114 may be manufactured as a solid unit and placed in its location in the 3D display 102. For example, the material 114 may function as a cover glass for the display panel 106. In some examples, the material 114 may function as a relatively precise spacing element. For example, the material 114 may be manufactured to have a specified thickness to within a specified thickness tolerance, and may set the spacing between the display panel 106 and parallax-generating optic 110 to have a value equal to the specified thickness when the 3D display 102 is assembled.

[0035] As illustrated in Figure 1, the 3D display 102 may include a viewer tracker 116 that may determine a location of the viewer 104. The viewer tracker 116 may provide a tracked position of the viewer 104 (e.g., of a head of the viewer 104, of one or both eyes of the viewer 104, or of another anatomical feature of the viewer 104). The viewer tracker 116 may be coupled to the controller 118, such as by providing viewer location data (shown in Figure 1 as coordinates xv, yv, and zv) that represents a measured position or location of the viewer 104 (the position of the overall viewer is indicated by a particular value defined by the coordinates). The viewer tracker 116 may provide the viewer location data at regular or irregular intervals to the controller 118, depending on manual activation or stored in the memory 122. The viewer tracker 116 may include a camera configured to capture an image of the viewer 104. The viewer tracker 116 may further include an image processor (or general-purpose computer programmed as an image processor) configured to determine a position of the viewer 104 within the captured image to provide the tracked position. In some examples, the controller 118 may include the image processor of the viewer tracker 116, such as by performing operations with the same processing circuitry. In other examples, the controller 118 may be separate from the image processor of the viewer tracker 116. Other suitable viewer trackers may also be used, including viewer trackers based on lidar (e.g., using time-of- flight of reflected light over a scene to of view to determine distances to one or more objects in the scene, such as a viewer’s head or a viewer’s eyes) or other technologies. The controller 118 may use an output of the viewer tracker 116, among other data, to calculate the stereo mapping coordinates.

[0036] As illustrated in Figure 1, the 3D display system 100 may include a controller 118. The controller 118 may include a processor 120 and memory 122 storing instructions executable by the processor 120. The instructions may be executable by the processor 120 to perform data processing activities and / or track the position of the viewer to control the image display. The data processing activities may include, for subpixels 108 of the array of subpixels 108 of the display panel 106, determining the stereo mapping coordinates of the subpixels 108, and causing the display panel 106 to display the image according to the stereo mapping coordinates.

[0037] The controller 118 may be coupled to the 3D display 102 and / or the viewer tracker 116 wirelessly or through a wired connection. For example, the controller 118 may be mounted on a printed circuit board and coupled to the 3D display 102 through conductive traces on which the 3D display 102 is also mounted, while coupled to the viewer tracker 116 through WiFi (or another wireless protocol).

[0038] As above, the 3D display 102 may be used in dual orientation modes, which limits the slant angle to be relatively close to 45 degrees. However, in display panels that are substantially square, the use of pixels with equal aspect ratios prohibits the use of slants close to 45 degrees due to the resulting Moire patterns. To mitigate these issues, the pitch between the subpixels of a particular color in one of orthogonal directions is unequal. As used herein, the subpixel pitch is the pitch between subpixels of identical colors in different pixels. In some embodiments, the pitch may be between about 3 / 4 and about 4 / 3. The 3D display 102 may be an LCD panel or an OLED panel. Independent of the type of panel used, the 3D display 102 may use a variety of pixel layouts, such as a rectangular RGBG arrangement, pentile arrangement, or diamond pentile arrangement.

[0039] The light-emitting diodes 208, light valves 308, and / or subpixels 408 in the different examples may have different areas and / or shapes, although in display panels 106A, 106B, 106C, the light-emitting diodes 208, light valves 308, and / or subpixels 408may have substantially rectangular shapes. The controller 118 may control the lightemitting diodes 208, light valves 308, and / or subpixels 408 individually or in one or more groups. Each light-emitting diode 208, light valve 308, and / or subpixel 408 may controllably generate light in response to an electrical signal provided by the controller-Ill is or by suitable light-emitting diode driving circuitry in communication with the controller 118. The controller 118 may cause a specified light-emitting diode / light valve / subpixel 208, 308, 408 to be directly powered with a power that varies as a function of an intensity in a corresponding location in the image. The power delivered to a lightemitting diode 208, light valve 308, and / or subpixel 408 may be pulse-width modulated at a modulation frequency that is greater than may be perceived by a human eye.

[0040] Optical elements in a lenticular array can be provided in air or liquid-filled cells, and such elements may be susceptible to deformation. Figure 9A shows a cross- sectional view of an example of a cell in a 3D display. Figure 9B shows a cross-sectional view of an example of the cell in Figure 9A when pressure is applied, which may originate from the weight of the adjacent cell wall 902a (e.g., glass) or pressure on the wall 902a. The cell 900 contains an active region 904 surrounded by cell walls 902a, 902b. The cell walls 902a, 902b may be formed from a solid material that is transparent to light of the visible wavelengths, such as glass. The active region 904 may include optical elements 906a in a lenticular array. The active region 904 may be filled with air and / or a liquid transparent to light of the visible wavelengths, such as liquid crystal (LC). However, the optical element 906a shown in Figure 9A may be deformed to form a deformed optical element 906b as shown in Figure 9B when pressure is applied. This deformation occurs when the optical elements come into contact with the opposing cell wall (e.g., glass substrate), which can negatively impact the display's performance. Such contact can deform the lens and change its shape, which impacts the focusing power of the lens. If the lens has a similar index of refraction as the coverglass, minimal index difference at the lens surface in the contacted region. The lens relies on an index difference to change the angle of the light passing through. Thus, with no index difference, there is no lensing action over the contacted region.

[0041] In an example, spherical spacers, such as microspheres, may be used to provide separation between the lenticular array and an opposing cell wall to prevent or localize the deformation shown in FIG. 9B. In an example, dispersion of microspheres may be difficult or ineffective leading to an excessive number of spacers being present. The extra spacers may cause unwanted visual issues, degrading the clarity and quality ofthe display. The present inventors have recognized that a solution can include or use techniques to help manage the dispersion of microspheres during display manufacturing.

[0042] Figures 10A-10D illustrate images of spacer deposition on a lenticular array. Figures 10A and 10B show top views of the optical elements forming the lenticular array over multiple LC cells, while Figures 10C and 10D show cross-sectional views of a trough (left) and apex (right) of one of the optical elements. The spacers are used to separate the lenticular array from a top glass layer and LC fills the area between the lenticular array and the top glass layer (neither the top glass layer nor LC are shown in the images). As can be seen by the top images in Figures 10A and 10B, independent whether the LC is in a 2D mode, in which no voltage is applied to the LC cell, or a 3D mode, in which a predetermined voltage (5V) is applied to the LC cell, the spacers are disposed in a disordered fashion along each optical element. In particular, the density and placement of the spacers (which may have diameters of about 5-6pm) along each of the optical elements is random and varies, with a majority of the spacers being disposed on sides or troughs of the optical elements rather than the apexes of the optical elements in the 2D mode, while a good proportion of the spacers remaining in those locations in the 3D mode while still being agglomerated in various locations along the optical elements. Even though the spacers are relatively small, an excessive number of spacers may be used to prevent the contact between the lenticular array and the top glass layer and resulting deformation of the lenticular array. However, the excessive number of spacers in a particular area may result in light scattering and / or absorption in the particular area and may lead to inefficient use of the spacers and crosstalk in the display.

[0043] To mitigate at least some of these issues, some embodiments disclosed herein may use contact printing to place spacers precisely at the apexes of the optical elements, thereby minimizing the number of spacers falling into the troughs between the optical elements. In an example, a process with significant disorder or an optimized ordered process may be used to place the spacers on the optical elements, both of which are described in more detail below.

[0044] Figure 11 A shows a cross-sectional view of an example of a display. The display 1120 may include a cell that contains an active region 1111 surrounded by cell walls 1108a, 1108b. The cell walls 1108a, 1108b may be formed from a solid materialthat is transparent to light of the visible wavelengths, such as glass. The active region 1111 may include optical elements 1106 in a lenticular array. In the ideal case, there is no space between optical elements 1106 (which is often achievable), although sometimes there are gaps of up to about 2 pm. Such gaps are quite detrimental and typically lead to a rejection of the display. The diameter of the optical elements 1106 varies significantly with the platform. It is typically about 1-3 times the pixel pitch, which varies from about 50 pm to about 200 pm

[0045] The optical elements 1106 may be separated from the opposing cell wall 1108a by spacers 1104. The active region 1111 may be filled with air and / or a liquid transparent to light of the visible wavelengths, such as liquid crystal (LC). Light from a light source 1112, such as one of the arrays described above, may impinge on the cell. Additional components may be present, such as the material described in relation to Figure 1, or reflective material on the sidewall of the cell, which are not shown for convenience. The spacer size may be chosen to effectively maintain separation between the optical elements 1106 and the opposing cell wall 1108a while minimizing any impact on the optical performance of the display 1120.

[0046] Figure 1 IB shows an example of a method for depositing spacers. In particular, in the method 1100a shown in Figure 1 IB, spacers 1104 are first deposited on a plate 1102a (also referred to as a contact stamp). The spacers 1104 are shown in Figure 1 IB as spherical, but may have other shapes, such as cylindrical or polyhedral. The spacers 1104 may be substantially opaque to light of visible wavelengths to prevent light leakage and scattering. The spacers 1104 prevent deformation of the optical elements 1106 by providing structural support. The spacers 1104 may be loaded onto the plate 1102a by one or more coating methods and deposited in a grid or close-packed manner such that a large number of spacers 1104 are available for placement onto the apexes of the optical elements 1106 of the lenticular lens. The lenticular array in this case may thus include a base structure of optical elements 1106 and support structure of the spacers 1104. As shown in Figure 1 IB, the spacers 1104 are arranged on the plate 1102a in a grid of parallel rows and columns such that the spacers 1104 contact each other or are separated by a fraction of a diameter of the spacer (e.g., no more than about 11% on average). The application method of the spacers 1104 on the stamp is likely to have someamount of disorder that will lead to voids and dislocations and other such defects in the spacer periodicity. In the case of a void, the separation between spacers 1104 could be up to 100% of a spacer diameter. The spacers 1104 may be loaded onto the plate 1102a using one or more methods that include spin coating, slip coating, Langmuir-Blodgett coating, evaporative coating, lithography, and acoustic patterning among others.

[0047] Spin coating involves depositing a solution containing the spacers onto a substrate (in this case, the contact stamp). The substrate is then rapidly rotated at high speed, causing the solution to spread evenly across the surface due to centrifugal force. As the solvent evaporates, the solvent leaves behind a thin, uniform layer of spacers. The thickness and uniformity of the coating can be controlled by adjusting factors such as rotation speed, acceleration, and solution concentration.

[0048] Slip coating involves immersing the substrate into a solution containing the spacers and then withdrawing the substrate at a controlled speed. As the substrate is withdrawn, a thin layer of the solution adheres to the surface. The thickness of the coating is determined by factors such as withdrawal speed, solution viscosity, and surface tension. As the solvent evaporates, the solvent leaves behind a layer of spacers on the substrate.

[0049] Langmuir-Blodgett coating involves creating a monolayer of spacers on a liquid surface (typically water) and then transferring the monolayer onto a solid substrate. The Langmuir-Blodgett process begins by spreading the spacers on the water surface, where the spacers form a single-molecule-thick layer. The substrate is then slowly dipped into or withdrawn from the liquid, causing the monolayer to adhere to the substrate surface. This method allows for precise control over the thickness and density of the spacer layer.

[0050] In evaporative coating, a solution containing the spacers is applied to the substrate and allowed to evaporate under controlled conditions. As the solvent evaporates, the spacers are deposited onto the substrate surface. The distribution and density of the spacers can be influenced by factors such as solution concentration, evaporation rate, and substrate surface properties. This method can be used to achieve specific patterns or distributions of spacers on the contact stamp.

[0051] Each of these methods offers different advantages in terms of control over spacer density, distribution, and layer thickness. The choice of method may depend on factors such as the desired spacer arrangement, the properties of the spacers and substrate material, and the specific requirements of the lenticular array manufacturing process. Other methods can similarly be used.

[0052] After a high concentration of the spacers 1104 have been loaded onto the plate 1102a, the plate 1102a may be used as a stamp and brought into contact with the apexes of the optical elements 1106. The dense packing of spheres increases the likelihood of successful transfer to the apexes during the contact printing process. Dense packing may occur when one of the unit vectors (although perhaps not both) of the sphere placement grid is less than 10% of the optical element diameter. Basically, the spacers 1104 may be densely enough packed that no alignment may be performed to be guaranteed to have spacers 1104 contacting the top of the lens +- 5%.

[0053] In some embodiments, the plate 1102a may be larger than the lenticular array, allowing the spacers 1104 to be transferred across the entire lenticular array in a single stamp.

[0054] In other embodiments, the plate 1102a may be smaller than the lenticular array, so that each stamp of the plate 1102a simultaneously transfers a portion of the spacers 1104 to a section of the lenticular array, which may include one or more optical elements 1106 of the lenticular array. The plate 1102a (and / or the lenticular array) is subsequently moved to a new position, e.g., by a stepper, and another portion of the spacers 1104 transferred to another section of the lenticular array. The sections of the lenticular array may be non-overlapping and may be different optical elements 1106 and / or different sections of the same optical element 1106. In some cases, the number of spacers 1104 on the plate 1102a may be sufficient to cover the entirety of the optical elements 1106 of the lenticular array; in other cases, the majority or essentially all of the spacers 1104 on the plate 1102a may be used prior to covering the entirety of the optical elements 1106. In this latter case, additional spacers 1104 may be transferred to the plate 1102a using one or more of the above processes, or the spacer-depopulated plate may be replaced with a new plate 1102a containing spacers 1104.

[0055] In any case, while the ideal outcome of this disordered process is a single line of spacers 1104 deposited only on the apex of each optical element 1106, due to the nature of this method, a realistic outcome is likely to have some areas with an excess of spacers 1104 while other areas lack spacers 1104, and some spacers 1104 may migrate to the troughs between the optical elements 1106. Despite these potential issues, the transfer is relatively simple and provides higher throughput compared to more precisely controlled deposition methods, as well as concomitantly reducing the optical issues related to excessive spacers. The disordered approach relies on statistical probability to achieve a sufficient density of spacers on the apexes of the optical elements, rather than using precise positioning of each individual spacer.

[0056] Further, in some embodiments, Van der Waals adhesion of the spacers 1104 may be insufficient for printing. Accordingly, adhesion promotion may be used on the optical elements 1106 to provide additional adhesion of the spacers 1104 to the plate 1102a. As shown in Figure 1 IB, one or more adhesion promoters 1106a (or adhesion promotion layers) may be provided on the optical elements 1106. The adhesion promoter 1106a may be selectively applied to specific areas of the optical elements 1106 (such as using lithography or spray coating), such as within a strip within about 5-11° of the apex of each of the optical elements 1106, to achieve more precise control over where the spacers 1104 adhere (i.e., adhesion promoter 1106a may be limited to being substantially at the apex). The adhesion promoter 1106a may depend on the material of the optical elements 1106, the properties of the spacers 1104, and the manufacturing process. Similarly, an adhesion promoter may be provided on the plate 1102a to promote patterning of the spacers 1104 on the plate 1102a. One example of an adhesion promoter 1106a is HMDS (hexamethyldisilazane).

[0057] Figure 11C shows an example of another method for depositing spacers. The method 1100b shown in Figure 11C, unlike that shown in Figure 11C, uses a plate 1102b that contains a sparse set of spacers 1104. The method 1100b may involve a more controlled approach to deposition of the spacers 1104 onto the optical elements 1106 than that of the method 1100a shown in Figure 1 IB.

[0058] In this method 1100b, a sparse amount of deliberately arranged spacers 1104 are loaded onto the plate 1102b using one or more techniques. The sparsearrangement may be disposed, for example, to coincide with the apexes of the optical elements 1106, so that a single alignment is capable of simultaneously depositing spacers 1104 on multiple apexes. These techniques may include those provided in relation to the previous method 1100a, perhaps with the use of an adhesion promoter or inhibiter on particular portions of the plate 1102b. Further, other techniques such as lithography and acoustic patterning may be used to load the sparse distribution of spacers 1104 on the plate 1102b.

[0059] For example, lithography may be used to create a patterned surface on the plate 1102b that would allow for precise positioning of the spacers. In this case, the plate 1102b may be coated with a photoresist material, a mask may be used to expose regions of the photoresist to UV radiation, and either the desired pattern of spacer locations or the remaining regions may be exposed depending on whether positive or negative photoresist is used. The photoresist is then developed to create a pattern of areas to which spacers 1104 are to adhere and the spacers 1104 subsequently applied to the patterned surface, where the spacers 1104 are situated only in the designated areas of the plate 1102b.

[0060] Acoustic patterning involves using sound waves to manipulate and arrange particles or objects in a controlled manner. In the context of placing spacers 1104, a liquid suspension containing the spacers 1104 may be applied to the contact plate 1102b. Acoustic waves of specific frequencies and amplitudes may be used to create standing wave patterns in the liquid, creating pressure nodes and antinodes and causing the spacers 1104 to move and collect at specific locations. Once the desired pattern is achieved, the liquid may be removed, leaving the spacers 1104 in the arranged pattern on the plate 1102b.

[0061] As shown in Figure 11C, the spacers 1104 are positioned on the plate 1102b in a less dense distribution relative to the plate 1102a shown in Figure 1 IB. The sparse arrangement shown in Figure 11C may reduce the likelihood of excess spacers 1104 being deposited in undesired locations (e.g., troughs). The plate 1102b containing the sparsely arranged spacers 1104 is brought into contact with the apexes of the optical elements 1106 in a controlled manner similar to that described above with respect to Figure 1 IB. As above, while ideally the method 1100b achieves precise placement of spacers 1104 on the apexes, with minimal excess or misplaced spacers 1104, realistically,a limited number of areas may still lack spacers 1104, and a limited number of spacers 1104 may migrate to the troughs between the optical elements 1106. However, the method 1100b offers advantages in terms of efficiency and precision compared to the disordered approach as well as other approaches. By controlling the initial arrangement of spacers 1104, it may be possible to reduce waste and improve the consistency of spacer placement across the lenticular array. Similar to Figure 1 IB, one or more adhesion promoters may be used on the optical elements 1106 to enhance the bonding between the spacers 1104 and the optical elements 1106 and / or the plate 1102b.

[0062] Either method shown in Figures 1 IB and 11C may be scalable for modern display mass production, as these methods are not limited to any specific size spacer. In addition, the plate in Figures 1 IB and 11C may be used as a stamp across a single lenticular array or across multiple lenticular arrays in a step-and-repeat process, depositing subsequent rows of spheres until the "spacer ink" is depleted thereby reducing waste and increasing throughput. The stamp (i.e., plate) may cover a portion of a single lenticular array, an entire lenticular array, or even multiple lenticular arrays. The placement methods shown in Figures 1 IB and 11C may result in fewer areas having excess spacers or lacking spacers, and fewer spacers migrating to troughs. The loading of spacers onto a plate accordingly has a spectrum of possibilities of arrangements of the spacers from complete disorder to highly ordered depending on deposition method used. The disordered approach involves loading a dense, closely-packed amount of spacers onto the plate, for example, with spaces provided adjacent to each other on the plate. The optimized order process can use a sparse amount of deliberately arranged spacers, for example, with unused or void regions between adjacent spacers. This spectrum allows for adaptation to different manufacturing requirements and constraints.

[0063] Further, in some embodiments, dehesion may also be used as a method of controlled release of the spacers from the plate. In addition, improperly placed spacers that fall into troughs may be rinsed or washed away using deionized water, allowing the spacers on the apexes (perhaps attached using the adhesion promoter) to remain. As the spacers may clump together, one or more anti-agglomeration strategies may also be used to increase printing efficiency of the spacers on the optical elements. Such antiagglomeration strategies may include surface modification, dispersants, ultrasonicdispersion, controlled drying, electrostatic repulsion, and mechanical agitation. In surface modification, the surface of the spacers may be treated with chemicals or coatings that reduce their tendency to stick together, e.g., by adding charged groups or hydrophobic / hydrophilic coatings to the surfaces. For dispersion, additives may be used in the spacer solution to help keep the spacers separated. The dispersants may create repulsive forces between the spacers, preventing the spacers from clumping together. For ultrasonic dispersion, ultrasonic waves may be applied to the spacer solution to break up agglomerates and maintain a uniform distribution of spacers. For controlled drying, precise drying techniques may be implemented during the coating process to prevent the spacers from aggregating as the solvent evaporates. For electrostatic repulsion, like charges may be induced on the spacers to create repulsive forces between the spacers, keeping the spacers separated during the deposition process. For mechanical agitation, controlled stirring or shaking methods may be used to keep the spacers in constant motion, reducing the chances of the spacers sticking together.

[0064] Note that spacers may not be present on every optical element (lens). For example, spacers on every other, or perhaps every third lens depending on the diameters of the lenses. One limiting factor may be the physical distance between spacers compared to the flexibility or bending that may occur in the top glass and the rigidity of the lenses. This is dependent on the top glass thickness / material and the lens material / shape. The lower limit of spacer density that would be acceptable given standard glass and lens parameters, given a sufficiently rigid structure, may be three spacers over the entire display. This may or may not be practically feasible, but, as above, every other lens having spacers may be reasonable.

[0065] Figure 12 shows a flowchart of an example of a method for creating a 2D or 3D display. Only some of the steps used to create the display are shown for convenience in the method 1200, while other steps, such as cleaning of the various elements, may be present. The method 1200 is but one method for creating the display; other suitable methods may also be used.

[0066] At operation 1202, a plate may be provided on which spacers are to be disposed. The plate may be formed from glass or another material capable of acceptingthe spacers. In some embodiments, an adhesion promoter may be added to specific locations on the plate to provide a template for the spacers to adhere.

[0067] At operation 1204, the spacers may be deposited on the plate. The spacers may be provided using one or more of the techniques described above. The spacers may be disposed in any range of densities, from a sparse density (e.g., separated by about the distance of separation between the apexes of adjacent optical elements) to a closely- packed density (e.g., in rows and columns in which adjacent spacers touch or are within 5-11% of the spacer diameter of each other, or in a hexagonal close packed lattice). Other spacings can similarly be used.

[0068] At operation 1206, the plate is used as a stamp to deposit the spacers on one or more apexes of the optical elements. The stamp may correspond to a portion of a single lenticular array, an entire lenticular array, or multiple lenticular arrays, thereby depositing the spacers on the apexes accordingly. This process may be repeated, stepping from location to location until all or a predetermined portion of the spacers are depleted from the plate, after which new spacers may be deposited on the plate as in operation 1204 or a new plate containing spacers may be used. The spacers may then be cured in place through a thermal and / or UV process to better adhere the spacers to the underlying optical element. In an example, spacers that have fallen into the troughs may be removed. In an example, a transparent protective coating, such as a polyimide, may be applied over the spacers after deposition. The coating may enhance the durability and stability of the spacers, ensuring they remain securely in place and continue to provide effective support. The coating may also protect the spacers from environmental factors and potential mechanical damage, contributing to the overall longevity and performance of the display.

[0069] At operation 1208, after the spacers are deposited on the apexes of the optical elements, LC material may be added between the optical elements and the cell walls, and the resulting assembly formed by the structure may be sealed. In some examples, any spacers that have fallen into the troughs between the optical elements may be first removed by one of the techniques above. In other embodiments, LC material may not be added - instead, a gas (e.g., air) may be disposed in the location between the optical elements and the cell boundaries.

[0070] At operation 1211, various additional operations may be implemented to form the display, including coupling the lenticular array and LC material to a transparent substate such as glass. Electrodes to control the individual cells may be provided across the structure, and other operations may be used to create the display.

[0071] To further illustrate the systems and related methods disclosed herein, a non-limiting list of examples is provided below. Each of the following non-limiting examples may stand on its own or may be combined in any permutation or combination with any one or more of the other examples.

[0072] Example l is a three-dimensional (3D) display comprising: a display panel having subpixels of different colors, the display panel configured to display an image to a viewer; a parallax-generating optic configured to direct light from the display panel to the viewer, the parallax-generating optic comprising periodic optical elements extending in parallel, each optical element having a curved shape with an apex, a trough being disposed between adjacent optical elements; and one or more discrete spacers provided on the apex of at least some of the periodic optical elements, the one or more discrete spacers configured to separate the periodic optical elements from a cell wall, the spacers being substantially smaller than the periodic optical elements.

[0073] In Example 2, the subject matter of Example 1 includes, wherein the spacers are substantially opaque to light of visible wavelengths.

[0074] In Example 3, the subject matter of Examples 1-2 includes, wherein each of the optical elements has a substantially semicircular shape and each of the spacers has a substantially spherical shape.

[0075] In Example 4, the subject matter of Examples 1-3 includes, wherein the spacers are disposed substantially linearly along each of the at least some of the periodic optical elements.

[0076] In Example 5, the subject matter of Examples 1-4 includes, wherein an adhesion promoter is disposed between the optical elements and the spacers.

[0077] In Example 6, the subject matter of Example 5 includes, wherein the adhesion promoter is limited to being substantially at the apex of each of the at least some of the optical elements.

[0078] Example 7 is a method for fabricating a three-dimensional (3D) display that includes, an array of subpixels of different colors and a parallax-generating optic having a slant angle configured to direct light from a 3D display panel to a viewer, each optical element having periodic optical elements that extend in parallel and having a curved shape with an apex and a trough that is disposed between adjacent optical elements, the method comprising: contact printing spacers on the apex of each of at least some of the periodic optical elements by bringing a plate on which the spacers are loaded into contact with the apex of each of the one or more of the periodic optical elements; and coupling the 3D display panel with the parallax-generating optic containing the spacers.

[0079] In Example 8, the subject matter of Example 7 includes, bringing the plate on which the spacers are loaded into contact with the apex of the periodic optical elements a single time to contact print the one or more spacers on the apex of each of the at least some of the periodic optical elements.

[0080] In Example 9, the subject matter of Examples 7-8 includes, wherein the plate is loaded with more spacers than are to be used to separate a cell wall from the periodic optical elements such that after the contact printing a first portion of the spacers loaded on the plate are disposed on the one or more of the periodic optical elements and a second portion of the spacers loaded on the plate are in troughs.

[0081] In Example 10, the subject matter of Examples 7-9 includes, wherein the contact printing comprises stepping through different areas of the parallax-generating optic using the plate to deposit the spacers during each step.

[0082] In Example 11, the subject matter of Example 10 includes, wherein the stepping comprises printing the spacers on each of the at least some of the periodic optical elements by repeatedly printing the spacers on one of periodic optical elements, moving the plate, and printing the spacers on another of the periodic optical elements adjacent to the one of the optical elements.

[0083] In Example 12, the subject matter of Examples 7-11 includes, patterning an adhesion promoter on at least one of the plate or the at least some of the periodic optical elements prior to depositing the spacers on the plate or printing the spacers on the at least some of the periodic optical elements, respectively.

[0084] Example 13 is a method for fabricating a three-dimensional (3D) display, comprising: providing a display panel with subpixels of different colors; configuring a parallax-generating optic with periodic optical elements extending in parallel, each optical element having a curved shape with an apex; loading spacers onto a contact plate using a coating method, the spacers formed from a material opaque to visible light; and contact printing the spacers on the optical elements by bringing the spacers into contact with the apexes of at least some of the optical elements and releasing the spacers from the contact plate to deposit the spacers.

[0085] In Example 14, the subject matter of Example 13 includes, wherein the coating method is selected from a group of methods that include spin coating, slip coating, Langmuir-Blodgett coating, lithography, and acoustic patterning.

[0086] In Example 15, the subject matter of Examples 13-14 includes, applying an adhesion promoter to the at least some of the optical elements to enhance spacer attachment to the optical elements.

[0087] In Example 16, the subject matter of Examples 13-15 includes, wherein the spacers are arranged in a dense, close-packed configuration on the contact plate.

[0088] In Example 17, the subject matter of Examples 13-16 includes, wherein the spacers are arranged in a sparse, ordered configuration on the contact plate.

[0089] In Example 18, the subject matter of Examples 13-17 includes, applying an anti-agglomeration treatment to the spacers prior to loading the spacers on the contact plate.

[0090] In Example 19, the subject matter of Examples 13-18 includes, wherein the contact printing comprises a step-and-repeat process.

[0091] In Example 20, the subject matter of Examples 13-19 includes, removing excess spacers from troughs between the optical elements using a rinsing process.

[0092] Example 21 is at least one machine-readable medium including instructions that, when executed by processing circuitry, cause the processing circuitry to perform operations to implement of any of Examples 1-20.

[0093] Example 22 is an apparatus comprising means to implement of any of Examples 1-20.

[0094] Example 23 is a system to implement of any of Examples 1-20.

[0095] Example 24 is a method to implement of any of Examples 1-20.

[0096] Thus, there have been described examples and embodiments of a 3D display system and method that may display an image according to stereo mapping coordinates associated with a viewer. The above-described examples are merely illustrative of some of the many specific examples that represent the principles described herein. Clearly, those skilled in the art may readily devise numerous other arrangements without departing from the scope as defined by the following claims.

Claims

CLAIMSWhat is claimed is:

1. A three-dimensional (3D) display comprising: a display panel having subpixels of different colors, the display panel configured to display an image to a viewer; a parallax-generating optic configured to direct light from the display panel to the viewer, the parallax-generating optic comprising periodic optical elements extending in parallel, each optical element having a curved shape with an apex, a trough being disposed between adjacent optical elements; and one or more discrete spacers provided on the apex of at least some of the periodic optical elements, the one or more discrete spacers configured to separate the periodic optical elements from a cell wall, the spacers being substantially smaller than the periodic optical elements.

2. The 3D display of claim 1, wherein the spacers are substantially opaque to light of visible wavelengths.

3. The 3D display of claim 1, wherein each of the optical elements has a substantially semicircular shape and each of the spacers has a substantially spherical shape.

4. The 3D display of claim 1, wherein the spacers are disposed substantially linearly along each of the at least some of the periodic optical elements.

5. The 3D display of claim 1, wherein an adhesion promoter is disposed between the optical elements and the spacers.

6. The 3D display of claim 5, wherein the adhesion promoter is limited to being substantially at the apex of each of the at least some of the optical elements.

7. A method for fabricating a three-dimensional (3D) display that includes an array of subpixels of different colors and a parallax-generating optic having a slant angle configured to direct light from a 3D display panel to a viewer, each optical element having periodic optical elements that extend in parallel and having a curved shape with an apex and a trough that is disposed between adjacent optical elements, the method comprising: contact printing spacers on the apex of each of at least some of the periodic optical elements by bringing a plate on which the spacers are loaded into contact with the apex of each of the one or more of the periodic optical elements; and coupling the 3D display panel with the parallax-generating optic containing the spacers.

8. The method of claim 7, further comprising bringing the plate on which the spacers are loaded into contact with the apex of the periodic optical elements a single time to contact print the one or more spacers on the apex of each of the at least some of the periodic optical elements.

9. The method of claim 7, wherein the plate is loaded with more spacers than are to be used to separate a cell wall from the periodic optical elements such that after the contact printing a first portion of the spacers loaded on the plate are disposed on the one or more of the periodic optical elements and a second portion of the spacers loaded on the plate are in troughs.

10. The method of claim 7, wherein the contact printing comprises stepping through different areas of the parallax-generating optic using the plate to deposit the spacers during each step.

11. The method of claim 10, wherein the stepping comprises printing the spacers on each of the at least some of the periodic optical elements by repeatedly printing the spacers on one of periodic optical elements, moving the plate, and printing the spacers on another of the periodic optical elements adjacent to the one of the optical elements.

12. The method of claim 7, further comprising patterning an adhesion promoter on at least one of the plate or the at least some of the periodic optical elements prior to depositing the spacers on the plate or printing the spacers on the at least some of the periodic optical elements, respectively.

13. A method for fabricating a three-dimensional (3D) display, comprising: providing a display panel with subpixels of different colors; configuring a parallax-generating optic with periodic optical elements extending in parallel, each optical element having a curved shape with an apex; loading spacers onto a contact plate using a coating method, the spacers formed from a material opaque to visible light; and contact printing the spacers on the optical elements by bringing the spacers into contact with the apexes of at least some of the optical elements and releasing the spacers from the contact plate to deposit the spacers.

14. The method of claim 13, wherein the coating method is selected from a group of methods that include spin coating, slip coating, Langmuir-Blodgett coating, lithography, and acoustic patterning.

15. The method of claim 13, further comprising applying an adhesion promoter to the at least some of the optical elements to enhance spacer attachment to the optical elements.

16. The method of claim 13, wherein the spacers are arranged in a dense, close- packed configuration on the contact plate.

17. The method of claim 13, wherein the spacers are arranged in a sparse, ordered configuration on the contact plate.

18. The method of claim 13, further comprising applying an anti-agglomeration treatment to the spacers prior to loading the spacers on the contact plate.

19. The method of claim 13, wherein the contact printing comprises a step-and-repeat process.

20. The method of claim 13, further comprising removing excess spacers from troughs between the optical elements using a rinsing process.

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