Patterned layer on a micro-led panel in an eyewear display

Abstract

An eyewear display includes a micro-light emitting diode (micro-LED) panel and a patterned layer applied over a front surface of the micro-LED panel such that the micro-LED panel emits light through the patterned layer. The eyewear display further includes a waveguide with an incoupler to incouple light emitted from the micro-LED panel. In some cases, a portion of emitted light incident on the incoupler is reflected back towards the micro-LED panel as a display beam reflection, and the patterned layer scatters the display beam reflection away from the micro-LED panel.

Description

PATTERNED LAYER ON A MICRO-LED PANEL IN AN EYEWEAR DISPLAYBACKGROUND

[0001] In augmented reality (AR) or virtual reality (VR) eyewear displays, display light beams emitted from an image source are coupled into a waveguide by an incoupler which can be formed as an optical grating on a surface, or multiple surfaces, of the waveguide or disposed within the waveguide. Once the display light beams have been coupled into the waveguide, the incoupled display light beams are “guided” through the waveguide, typically by multiple instances of total internal reflection (TIR), to then be directed out of the waveguide by an outcoupler, which can also be formed as an optical grating on or within the waveguide. The outcoupled display light beams overlap at an eye relief distance from the waveguide forming an exit pupil within which a virtual image generated by the image source can be viewed by the user of the eyewear display.

[0002] In some eyewear displays, the image source is a micro-light emitting diode (LED) panel that emits the display light beams to the incoupler through a light engine assembly (LEA) made of a series of optical components (e.g., lenses, mirrors, optical filters, prisms, or the like) that perform beamshaping and focusing of the display light beams prior to incoupling. The micro-LED panel has a back surface reflector to increase the amount of light that is extracted from the micro-LED panel for propagation towards the LEA and, eventually, to the incoupler. In some cases, some of the display light beams incident on the incoupler are reflected from the incoupler back through the LEA to the micro-LED panel instead of being incoupled into the waveguide. In some scenarios, the back surface reflector of the micro-LED panel effectively operates as a mirror that redirects these reflected display light beams through the LEA towards the incoupler at undesired angles (i.e., outside of the field of view) which can contribute to the generation of ghost artifacts that degrade the image quality of the eyewear display.SUMMARY

[0003] In a first embodiment, an eyewear display includes a micro-light emitting diode (micro-LED) panel and a patterned layer applied over a front surface of the micro-LED panel. The micro-LED panel is configured to emit light through the patterned layer. The eyewear display also includes a waveguide including an incoupler to incouple light emitted from the micro-LED panel. In some cases, a portion of emitted light incident on the incoupler is reflected back towards the micro- LED panel as a display beam reflection, and the patterned layer is configured to scatter the display beam reflection away from the micro-LED panel.

[0004] In some aspects of the first embodiment, the patterned layer includes a surface pattern that transmits light incident thereon from a first side adjacent to the micro-LED panel and scatters light that is incident thereon from a second side that is opposite to the first side. For example, in some cases, the surface pattern reflects light that is incident thereon from the second side at oblique angles such that the reflections of light are not transmitted back towards the incoupler. In some aspects, the surface pattern transmits light that is incident thereon from the first side, wherein the light that is incident thereon from the first side includes light having red, green, and blue wavelengths. Furthermore, in some aspects, the surface pattern scatters light that is incident thereon from the second side, wherein the light that is incident thereon from the second side includes light having red, green, and blue wavelengths. In some aspects, the surface pattern scatters light that is incident thereon from the second side, wherein the light is incident on the second side at a range of angles from -30° to 30°, where 0° corresponds to a normal direction from the front surface of the micro-LED panel. In some aspects, the surface pattern scatters light that is incident thereon from the second side, wherein the light that is incident thereon from the second side includes one or more of S-polarized light or P-polarized light.

[0005] In some aspects of the first embodiment, the surface pattern includes a periodic structure, where the periodic structure includes a diffraction grating with either a binary, blazed, or slanted profile or a metasurface. In some aspects of the first embodiment, the surface pattern is rotationally symmetric. In some aspects of thefirst embodiment, the surface pattern is a random texture that generates reflections of light incident on the second side.

[0006] In some aspects of the first embodiment, the front surface of the micro-LED panel is opposite to a back surface of the micro-LED panel comprising a back reflector.

[0007] In some aspects, the micro-LED panel includes a plurality of micro-LEDs arranged adjacent to one another on a substrate, and the patterned layer is applied across the plurality of micro-LEDs. Furthermore, in some aspects, the patterned layer includes multiple subsections, and each subsection of the multiple subsections covers a subset of the plurality of micro-LEDs. One or more of the subsets of the plurality of micro-LEDs includes a red micro-LED, a green micro-LED, and a blue micro-LED, and the patterned layer includes a gap between adjacent subsections of the multiple subsections.

[0008] In some aspects, the micro-LED panel includes a plurality of micro-LEDs arranged in a stack on a substrate, and the patterned layer is applied across a top layer of the stack. Furthermore, in some aspects, the patterned layer includes multiple subsections, and each subsection of the multiple subsections covers a subset of the plurality of micro-LEDs. One or more of the subsets includes a red micro-LED, a green micro-LED, and a blue micro-LED arranged in a stack, and the patterned layer includes a gap between adjacent subsections of the multiple subsections.

[0009] In some aspects of the first embodiment, the patterned layer modifies an emission profile of light emitted from the micro-LED panel to increase an amount of light that is propagated towards the incoupler.

[0010] In a second embodiment, a method includes emitting light from a micro-light emitting diode (LED) panel in an eyewear display through a patterned layer applied over a front surface of the micro-LED panel and incoupling, via an incoupler, a first portion of the light emitted from the micro-LED panel into a waveguide arranged in a lens of the eyewear display, wherein a second portion of the light is reflected from the incoupler back towards the micro-LED panel. The method further includes scattering,via the patterned layer, the second portion of the light before it reaches the microLED panel.

[0011] In some aspects of the second embodiment, at least some of the scattered second portion of light is absorbed by other components of the eyewear display such that it is not reflected back towards the incoupler.

[0012] In a third embodiment, a method includes applying a polymer resin using an inkjet-dispense process to a micro-light emitting diode (LED) panel and patterning the resin via nanoimprint lithography to create an optically selective surface pattern on the micro-LED panel. The optically selective surface pattern transmits light received from a first side corresponding to receiving light from the micro-LED panel and scatters light received from a second side opposite to the first side.

[0013] In some aspects of the third embodiment, the micro-LED panel includes a plurality of subsets of micro-LEDs, and each subset of the plurality of subsets includes a red micro-LED, a green micro-LED, and a blue micro-LED. In some aspects, the patterning of the resin via nanoimprint lithography includes creating gaps in the resin between adjacent subsets of the plurality of subsets.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference symbols in different drawings indicates similar or identical items.

[0015] FIG. 1 shows an example eyewear display in accordance with some embodiments.

[0016] FIG. 2 shows an example of a projection system with a patterned layer applied to an image source such as a micro-LED panel in the eyewear display of FIG. 1 in accordance with some embodiments.

[0017] FIG. 3 shows light propagation from an image source to a user of an eyewear display, such as that of FIGs. 1 and 2, in accordance with some embodiments.

[0018] FIG. 4 shows an example of a micro-LED panel projection system with a patterned layer on the front surface of the micro-LED panel in accordance with some embodiments.

[0019] FIG. 5 shows examples of a patterned layer applied to the front surface of a micro-LED panel in accordance with some embodiments.

[0020] FIGs. 6-7 show examples of methods for applying a front surface pattern to a micro-LED panel in accordance with some embodiments.

[0021] FIG. 8 shows a method flowchart for emitting light from a micro-LED panel and scattering light reflected back towards the micro-LED panel in an eyewear display, in accordance with some embodiments.DETAILED DESCRIPTION

[0022] The ensuing description and corresponding figures describe micro-LED panel front surface patterning techniques to reduce or eliminate the generation of ghost artifacts in an eyewear display. The surface pattern applied to the front-side (i.e. , the side facing the LEA) of the micro-LED re-directs the display light beams that are reflected off of the incoupler or other components of the eyewear display (these reflections are collectively referred to herein as display beam reflections). The surface pattern re-directs the display beam reflections away from the micro-LED panel such that the display beam reflections are not redirected back through the LEA again. That is, instead of the display beam reflections impinging on the micro-LED panel and being reflected specularly by the micro-LED’s back surface reflector through the LEA towards the incoupler a second time, the display beam reflections are scattered by the front surface pattern away from the LEA. The scattered display beam reflections are absorbed by other parts of the eyewear display so that they do not degrade the quality of the virtual image delivered to the user of the eyewear display.

[0023] In some embodiments, in addition to scattering the display beam reflections to mitigate the generation of ghost artifacts, the front surface pattern (also referred to herein as a patterned layer) also modifies the light emission profile of the micro-LED to increase the amount of display light beams that are initially transmitted by the micro-LED panel into the LEA. For example, the patterned layer concentrates the display light beams emitted from the micro-LED panel within a narrower angular range compared to no patterning in order to increase the emitted light that is transmitted through the LEA and eventually incoupled into the waveguide. This increases the efficiency of the projection system of the eyewear display.

[0024] In some embodiments, the patterned layer is applied to the front surface of the micro-LED panel by, for example, nanoimprint lithography or patterned film bonding. In some embodiments, the application of the patterned layer includes leaving airgaps in the patterned layer between subsets of adjacent red-green-blue (RGB) elements of the micro-LED panel to provide optical separation between the pixels of the micro-LED display. This further improves the quality of the virtual image delivered to the user.

[0025] FIG. 1 illustrates an example eyewear display 100 in accordance with various embodiments. The eyewear display 100 (also referred to as a wearable heads up display (WHUD), head-mounted display (HMD), near-eye display, or the like) has a support structure 102 that includes an arm 104, which houses a microdisplay projection system configured to project images towards the eye of a user, such that the user perceives the projected images as being displayed in a field of view (FOV) area 106 of a display at one or both of lens elements 108, 110. I n the depicted embodiment, the support structure 102 of the eyewear display 100 is configured to be worn on the head of a user and has a general shape and appearance (i.e., “form factor”) of an eyeglasses frame. The support structure 102 contains or otherwise includes various components to facilitate the projection of such images towards the eye of the user, such as an image source, a light engine assembly (LEA), and a waveguide (shown in FIG. 2, for example). In some embodiments, the support structure 102 further includes various sensors, such as one or more front-facing cameras, rear-facing cameras, other light sensors, motionsensors, accelerometers, and the like. The support structure 102 further can include one or more radio frequency (RF) interfaces or other wireless interfaces, such as a Bluetooth™ interface, a WiFi interface, and the like. Further, in some embodiments, the support structure 102 includes one or more batteries or other portable power sources for supplying power to the electrical components of the eyewear display 100. In some embodiments, some or all of these components of the eyewear display 100 are fully or partially contained within an inner volume of support structure 102, such as within the arm 104 in region 112 of the support structure 102. It should be noted that while an example form factor is depicted, it will be appreciated that in other embodiments the eyewear display 100 may have a different shape and appearance from the eyeglasses frame depicted in FIG. 1 .

[0026] In some embodiments, one or both of the lens elements 108, 110 are used by the eyewear display 100 to provide a mixed reality (MR) or an augmented reality (AR) display in which rendered graphical content can be superimposed over or otherwise provided in conjunction with a real-world view as perceived by the user through the lens elements 108, 110. In some embodiments, one or both of lens elements 108, 110 serve as optical combiners that combine environmental light (also referred to as ambient light) from outside of the eyewear display 100 and light emitted from an image source in the eyewear display 100. For example, light used to form a perceptible image or series of images may be projected by the image source of the eyewear display 100 onto the eye of the user via a series of optical elements, such as a waveguide formed at least partially in the corresponding lens element, a LEA including one or more light filters, lenses, scan mirrors, optical relays, prisms, or the like, and a patterned layer formed on the front surface of the image source. In some embodiments, the image source is configured to emit light having a plurality of wavelength ranges, e.g., red light, green light, and blue light (collectively referred to as RGB light). The light passes through the patterned layer to the LEA, which propagates the light towards an incoupler of the waveguide. The incoupler of the waveguide receives this light and incouples it into the waveguide. One or both of the lens elements 108, 110 thus includes at least a portion of a waveguide that routes display light received by the incoupler of the waveguide to an outcoupler of the waveguide, which outputs the display light towards an eye of a user of the eyeweardisplay 100. The display light is modulated and projected onto the eye of the user such that the user perceives the display light as an image in FOV area 106. In addition, in some embodiments, each of the lens elements 108, 110 is sufficiently transparent to allow a user to see through the lens elements to provide a field of view of the user’s real-world environment such that the image appears superimposed over at least a portion of the real-world environment.

[0027] In some embodiments, the image source is a modulative light source such as a display panel having one or more light-emitting diodes (LEDs) or organic lightemitting diodes (OLEDs) (e.g., a micro-LED display panel or the like) located in region 112. In some embodiments, the image source is configured to emit RGB light. The image source is communicatively coupled to the controller (not shown) and a non-transitory processor-readable storage medium or memory storing processorexecutable instructions and other data that, when executed by the controller, cause the controller to control the operation of the image source. In some embodiments, the controller controls a display area size and display area location for the image source and is communicatively coupled to the image source that generates virtual content to be displayed at the eyewear display 100. In some embodiments, the image source emits light over a variable area, designated the FOV area 106, of the eyewear display 100. The variable area corresponds to the size of the FOV area 106, and the variable area location corresponds to a region of one of the lens elements 108, 110 at which the FOV area 106 is visible to the user. Generally, it is desirable for a display to have a wide FOV area 106 to accommodate the outcoupling of light across a wide range of angles.

[0028] As previously mentioned, a waveguide is integrated into one or both of lens elements 108, 110. In some configurations, the waveguide includes a single waveguide substrate and in other configurations, the waveguide includes multiple waveguide substrates stacked on top of one another (referred to as a waveguide stack). The waveguide is separated from the image source by a first distance that is restricted by the form factor of the eyewear display 100 and, according to some aspects of the present disclosure, a LEA is positioned within this first distance. In addition, a patterned layer is applied to the surface of the image source between theimage source and the LEA. In some embodiments, the incoupler of the waveguide includes features to increase the incoupling of light into the waveguide for eventually outcoupling to the user via FOV area 106.

[0029] FIG. 2 illustrates a diagram of a projection system 200 that projects images onto the eye 216 of a user in accordance with various embodiments. The projection system 200, which may be implemented in the eyewear display 100 in FIG. 1 , includes one or more of an image source 202 such as a micro-LED panel, a light engine assembly (LEA) 204, a patterned layer 230 applied to the image source 202, and / or a waveguide 220. In the illustrated embodiment, the LEA 204 includes a first scan mirror 206, a second scan mirror 208, and an optical relay 210. In alternative embodiments, the LEA 204 does not include the first scan mirror 206 and the second scan mirror 208. The waveguide 220 includes one or more incouplers 222 and one or more outcouplers 224, with the one or more outcouplers 224 being optically aligned with an eye 250 of a user. For example, the one or more outcouplers 224 substantially overlap with the FOV area 106 shown in FIG. 1 .

[0030] The image source 202 includes one or more light sources configured to generate and project display light 218 (e.g., visible light such as RGB light and, in some embodiments, non-visible light such as infrared light). In some embodiments, the image source 202 is coupled to a driver or other controller (not shown), which controls the timing of emission of display light from the light sources of the image source 202 in accordance with instructions received by the controller or driver from a computer processor coupled thereto to modulate the display light 218 to be perceived as images when output to the retina of an eye 250 of a user. For example, during operation of the projection system 200, one or more beams of display light 218 are output by the light source(s) of the image source 202 and then directed into the waveguide 220 before being directed to the eye 250 of the user. The image source 202 modulates the respective intensities of the light beams so that the combined light reflects a series of pixels of an image, with the particular intensity of each light beam at any given point in time contributing to the amount of corresponding color content and brightness in the pixel being represented by the combined light at that time.

[0031] In some embodiments, the image source 202 projects the display light 218 to the LEA 204. In some embodiments, one or both of the scan mirrors 206 and 208 in the LEA 204 are MEMS mirrors that are driven by respective actuation voltages to oscillate during active operation of the projection system 200, causing the scan mirrors 206 and 208 to scan the light 218. Oscillation of the scan mirror 206 causes light 218 output by the light engine 202 to be scanned through the optical relay 210 and across a surface of the second scan mirror 208. The second scan mirror 208 scans the light 218 received from the scan mirror 206 towards the incoupler 222 of the waveguide 220. In some embodiments, the scan mirror 206 oscillates along a first scanning axis 211 , such that the light 218 is scanned in only one dimension (i.e. , in a line) across the surface of the second scan mirror 208. In some embodiments, the scan mirror 208 oscillates or otherwise rotates along a second scanning axis 213. In some embodiments, the first scanning axis 211 is perpendicular to the second scanning axis 213.

[0032] In some embodiments, the optical relay 210 is a line-scan optical relay that receives the light 218 scanned in a first dimension by the first scan mirror 206 (e.g., the first dimension corresponding to the small dimension of the incoupler 222), routes the light 218 to the second scan mirror 208, and introduces a convergence to the light 218 in the first dimension to an exit pupil beyond the second scan mirror 208. Herein, an “exit pupil” in an optical system refers to the location along the optical path where beams of light intersect. For example, the possible optical paths of the light 218, following reflection by the first scan mirror 206, are initially spread along the first scanning axis, but later these paths intersect at an exit pupil beyond the second scan mirror 208 due to convergence introduced by the optical relay 210. For example, the width (i.e., smallest dimension) of a given exit pupil approximately corresponds to the diameter of the light corresponding to that exit pupil. Accordingly, the exit pupil can be considered a “virtual aperture.” According to various embodiments, the optical relay 210 includes one or more collimation lenses that shape and focus the light 218 on the second scan mirror 208 or includes a molded reflective relay that includes two or more spherical, aspheric, parabolic, and / or freeform lenses that shape and direct the light 218 onto the second scan mirror 208. The second scan mirror 208 receives the light 218 and scans the light 218 in a second dimension, the second dimensioncorresponding to the long dimension of the incoupler 222 of the waveguide 220. In some embodiments, the second scan mirror 208 causes the exit pupil of the light 218 to be swept along a line along the second dimension.

[0033] As previously mentioned, in some embodiments, the LEA 204 does not include the first scan mirror 206 and the second scan mirror 208. That is, in some embodiments, the LEA 204 is formed of the optical relay 210 which includes one or more collimation lenses that shape and focus the light 218 onto the incoupler 222, a molded reflective relay that includes two or more spherical, aspheric, parabolic, and / or freeform lenses that shape and direct the light 218 onto the incoupler 222, or any combination thereof. In such embodiments, the image source 202 and the optical relay 210 may be aligned with the incoupler 222 (e.g., as shown in FIG. 3).

[0034] In some embodiments, the image source 202 is a micro-LED panel which includes a plurality of micro-LED elements to implement a high-resolution display. For example, the micro-LED panel includes a matrix of red, green, and blue (RGB) LEDs that provide an M x N display, where M and N are both integers. Micro-LED panels typically include a back reflector 232 (e.g., a metallic layer) applied to the back surface 242 of the micro-LED panel. The purpose of the back reflector is to maximize the amount of light generated by the micro-LEDs that is extracted from the micro-LED panel towards the intended direction (e.g., through the front surface 244). However, in some scenarios, the back reflector 232 also causes the micro-LED panel (serving as image source 202) to act as a mirror when some of the display light 218 emitted from the micro-LED panel is reflected back towards the micro-LED panel. For example, in some cases, a portion of the display light 218 incident on the incoupler 222 is reflected by the incoupler 222 instead of being incoupled into the waveguide 220. This reflected portion of the display light 218 may be redirected back through the LEA 204 towards the micro-LED panel 202, where the back reflector 232 acts as a mirror to reflect the light back through the LEA 204 to the incoupler 222 a second time. The incoupling of this reflected light results in the generation of ghost artifacts, thereby degrading the quality of the image delivered to the eye 250 of the user.

[0035] In some embodiments, the projection system 200 includes a patterned layer 230 on the front surface 244 of the micro-LED panel 202 to reduce or eliminate ghostartifacts generated by the scenario described above. The patterned layer 230 is made of a resin or polymer with optical properties and a surface pattern that transmits light generated by the micro-LED panel 202. That is, the patterned layer 230 allows the display light 218 generated by the micro-LED panel 202 to pass through towards the LEA 204. Furthermore, the patterned layer 230 is designed such that its surface pattern reflects light that is redirected back towards the micro-LED panel 202 away from the optical entry point of the LEA 204. That is, if some of the display light 218 is reflected by one or more optical components (such as the incoupler 222) in the projection system 200 back towards the micro-LED panel 202, the patterned layer 230 scatters this light away from the LEA 204 so that it is not propagated towards the incoupler 222 a second time. This reduces or eliminates the generation of ghost artifacts and improves the quality of the image delivered to the eye 250 of the user.

[0036] The incoupler 222 is configured to receive the display light 218 and direct the display light 218 into the waveguide 220. The term “waveguide,” as used herein, is understood to mean a combiner using one or more of total internal reflection (TIR), specialized filters, or reflective surfaces, to transfer light from an incoupler (such as incoupler 222) to an outcoupler (such as the outcoupler 224). In some display applications, the light is a collimated image, and the waveguide 220 transfers and replicates the collimated image to the eye. In general, the terms “incoupler” and “outcoupler” will be understood to refer to any type of optical grating structure, including, but not limited to, reflective facets, diffraction gratings, holograms, holographic optical elements (e.g., optical elements using one or more holograms), volume diffraction gratings, volume holograms, surface relief diffraction gratings, and / or surface relief holograms. In some embodiments, a given incoupler or outcoupler is configured as a transmissive grating (e.g., a transmissive diffraction grating or a transmissive holographic grating) that causes the incoupler or outcoupler to transmit light and to apply designed optical function(s) to the light during the transmission. In some embodiments, a given incoupler or outcoupler is a reflective grating (e.g., a reflective diffraction grating or a reflective holographic grating) that causes the incoupler or outcoupler to reflect light and to apply designed optical function(s) to the light during the reflection. In the present example, the display light 218 received at the incoupler 222 is propagated to the outcoupler 224 via thewaveguide 220 using TIR. A portion of the display light 218 is then output to the eye 250 of a user via the outcoupler(s) 224. Also, in some embodiments, one or more exit pupil expanders (not shown), such as a fold grating, are arranged in an intermediate stage between incoupler 222 and outcoupler 224 to receive light that is coupled into waveguide 220 by the incoupler 222, expand the light in one dimension, and redirect the light towards the outcoupler 224. As described above, in some embodiments the waveguide 220 is implemented in an optical combiner as part of an eyeglass lens, such as the lens element 108, 110 (FIG. 1) of the display system having an eyeglass form factor and employing projection system 200.

[0037] FIG. 3 illustrates a portion of an eyewear display 300 in accordance with various embodiments. In some embodiments, the eyewear display 300 represents the display 100 of FIG. 1 and includes the components of the projection system 200 of FIG. 2. The image source 202, the LEA 204, the incoupler 222, the patterned layer 230, and a portion of the waveguide 220 are included in an arm 302 of the eyewear display 300, in the present example.

[0038] The eyewear display 300 includes an optical combiner lens 304, which includes a first lens 306, a second lens 308, and the waveguide 220, with the waveguide 220 disposed between the first lens 306 and the second lens 308. Light exiting through the outcoupler 224 travels through the second lens 308 (which corresponds to, for example, the lens element 110 of the eyewear display 100). In use, the light exiting second lens 308 enters the pupil of an eye 250 of a user wearing the eyewear display 300, causing the user to perceive a displayed image carried by the laser light output by the image source 202. In some embodiments, the optical combiner lens 304 is substantially transparent, such that light from real-world scenes corresponding to the environment around the eyewear display 300 passes through the first lens 306, the second lens 308, and the waveguide 220 to the eye 250 of the user. In this way, images or other graphical content output by the projection system 200 are combined (e.g., overlayed) with real-world images of the user’s environment when projected onto the eye 250 of the user to provide an AR experience to the user. The eyebox of eyewear display 300 corresponds to the region (or volume) in whichthe eye 250 of the user can perceive images associated with light projected from image source 202.

[0039] In some embodiments additional optical elements are included in any of the optical paths between the image source 202 and the incoupler 222, in between the incoupler 222 and the outcoupler 224, and / or in between the outcoupler 224 and the eye 250 of the user (e.g., in order to shape the display light from image source 202 for viewing by the eye 250 of the user). As an example, the patterned layer 230 is used to scatter light that is reflected back towards the image source 202 away from the LEA 204 such that the reflected light is not propagated towards the incoupler 222 a second time. Other parts of the eyewear display 300, such as parts in the arm 302, absorb the light that is scattered by the patterned layer 230. In addition, in some embodiments, the patterned layer 230 enhances the emission profile of the light emitted by the image source 202 such that a higher amount of this light is transmitted to the LEA 204 compared to no patterning, and eventually, to the incoupler 222.

[0040] FIG. 4 illustrates an example of a portion of a projection system 400 with a patterned layer 430 on a front surface of the micro-LED panel 402 in accordance with some embodiments. The projection system 400 includes a waveguide 420 with an incoupler 422 such as that corresponding to waveguide 220 and incoupler 222 of FIG. 2, respectively. The projection system 400 also includes an LEA 404 such as one corresponding to LEA 204 of FIG. 2. In the illustrated embodiment, the projection system 400 includes a micro-LED panel 402 as the image source that is configured to emit display light. The micro-LED panel 402 includes a back surface reflector 460 to direct the light generated by the micro-LEDs (not labeled for clarity purposes) in the micro-LED panel 402 out the front surface towards the LEA 404.

[0041] In addition, the projection system 400 includes a patterned layer 430 applied to the front surface of the micro-LED panel 402. The patterned layer 430 is made of an at least partially transparent resin or other polymer material and includes a surface pattern. The patterned layer 430 allows light generated at the micro-LED panel 402 to pass through towards the LEA 404. In some cases, the micro-LEDs in the micro-LED panel 402 emit light in a Lambertian or other similar type of emission profile. Thus, in some embodiments, the patterned layer 430 modifies the emission profile of themicro-LED panel 402 to focus a higher amount of the light emitted from the microLED panel 402 to the optical entry point (also referred to as the exit pupil) of the LEA 404. This increases the amount of light that is emitted from the micro-LED panel 402 that is propagated to the incoupler 422, thereby increasing the efficiency of the projection system 400.

[0042] The micro-LED panel 402 generates the light at its micro-LEDs and emits display light beams 470 (one light beam shown for clarity purposes) towards the LEA 404. The display light beams 470 are shaped and focused by optical components (e.g., lenses) in the LEA 404 and propagated by the LEA 404 to the incoupler 422. A first portion 472 of the display light beams 470 incident on the incoupler 422 is incoupled into the waveguide 420. A second portion 474 of the display light beams 470 incident on the incoupler 422 is reflected by the incoupler 422 back through the LEA 404 towards the micro-LED panel 402 as display beam reflections 474. Prior to reaching the micro-LED panel 402, the display beam reflections 474 are scattered 476 by the patterned layer 430 away from the LEA 404. That is, instead of entering the micro-LED panel 402 and reflecting from the back surface reflector 460, the patterned layer 430 blocks the display beam reflections 474 from entering the micro- LED panel 402, which in turn blocks the display beam reflections 474 from being reflected from the back surface reflector 460. In this manner, the patterned layer 430 scatters the display beam reflections 474 away from being input into the LEA 404 a second time. The scattered light 476 is then absorbed by other components of the eyewear display housing the projection system 400. This reduces or eliminates the display beam reflections that are incoupled by the incoupler 422 into the waveguide 420, which helps to minimize the generation of ghost artifacts.

[0043] The surface pattern of the patterned layer 430 allows light generated at the micro-LED display 402 to pass through to the LEA 404. In other words, the patterned layer 430 allows light received at a first side of the patterned layer 430 adjacent to the micro-LED panel 402 to pass through. The surface pattern of the patterned layer 430 also scatters light that is reflected back towards the micro-LED display 402. In other words, the patterned layer 430 scatters light received at a second side opposite to the first side away from the LEA 404. The patterned layer 430 thus transmits lightreceived from a first side adjacent to the micro-LED panel 402 and scatters light received from a second side opposite to the first side. In some embodiments, the light transmitted through the patterned layer 430 when received at the first side adjacent to the micro-LED panel 402 and scattered by the patterned layer 430 when received at the second side includes broadband spectrum light covering the red, blue, and green light wavelengths and both S and P polarizations. That is, the surface pattern of the patterned layer 430 is designed to allow RGB light generated at the micro-LED panel 402 to pass through and is designed to scatter RGB light that is reflected back from the LEA 404 or the incoupler 422 away from the LEA 404. In addition, in some embodiments, the surface pattern of the patterned layer 430 reflects light incident thereon from the second side (i.e., the side facing the LEA 404) that is received in a range of incident angles from -30 ° to 30° (where 0° is perpendicular to the front surface of the micro-LED display 402) away from the micro-LED display 404 as reflected light 476 at a larger angle such that the light is redirected away from an optical entry point of the LEA 404.

[0044] In some embodiments, to further reduce ghost artifacts and other artifacts attributed to stray light, the surface pattern of the patterned layer 430 is designed in combination with the optical features of the LEA 404. For example, the surface pattern of the patterned layer 430 is co-optimized in combination with a collimation lens (or other beam shaping or focusing lens) of the LEA 404. The geometric features and surface properties of the patterned layer 430 are selected to increase the scattering of the incident light away from re-entering the LEA 404. The patterned layer 430 is thus implemented in terms of positioning and geometry based on the display beam reflections’ reflectance spectrum of the designed surface pattern. In addition to being designed to maximize the reflectance (or scattering) of the light reflected back to the micro-LED panel 402, the patterned layer 430 is also designed to improve the emission profile of the micro-LED panel 402 to increase the amount of light that is initially input into the LEA 404.

[0045] In addition, the surface pattern of the patterned layer 430 is selected based on the chief ray angle of the optics of the projection system 400. For example, in some embodiments, the surface pattern radially varies as a function of the chief rayangle to decrease the amount of light that is reflected back towards the LEA 403 that contributes to the generation of ghost artifacts. This improves the efficiency of the projection system 400.

[0046] FIG. 5 shows examples of patterned layers 510, 520, 530, 540, 550 applied to a front surface of a micro-LED panel in accordance with some embodiments. In the illustrated embodiments, a cross section view is shown for patterned layers 510, 520, 530, 540 and a top, plan view is shown for patterned layer 550.

[0047] In some embodiments, the patterned layer is a periodic structure such as that shown in the examples of patterned layers 510, 520, 530. In some embodiments, the periodicity is defined in one direction and in other embodiments, the periodicity is defined in two dimensions. For example, the periodicity can include a matrix of elements, where each row or column in the matrix is either aligned or offset with the row(s) or column(s) adjacent to it.

[0048] Patterned layer 510 has a blazed grating surface pattern that is defined by a series of angular protrusions with a slanted profile. Each angular protrusion in the series of angular protrusions 512 (one labeled for clarity) has a length 514 and a height 516. Although not shown, each angular protrusion 522 also includes a depth that extends into and out of the page. In addition, each of the angular protrusions 512 includes a top angle 518-1 and a bottom angle 518-2 that defines the respective protrusion’s shape 512 and orientation with respect to an adjacent protrusion, respectively. The side 519 of the patterned layer 510 facing the micro-LED panel (the micro-LED panel not shown for clarity purposes) is also shown.

[0049] Patterned layer 520 has a surface pattern that is defined by a series of elliptical protrusions 522 (one labeled for clarity). Each elliptical protrusion in the series of elliptical protrusions 522 has a first axis 524 and a height 526. In addition, each elliptical protrusion 522 includes a second axis (not labeled) that extends into and out of the page. Each elliptical protrusion 522 is separated from adjacent elliptical protrusion(s) by spacing 528. The side 529 of the patterned layer 520 facing the micro-LED panel (the micro-LED panel not shown for clarity purposes) is also shown.

[0050] Patterned layer 530 has a surface pattern that is defined by a series of dimples 532 (one labeled for clarity). Each dimple in the series of dimple 522 has a first axis 534 and a dimple depth 536. In addition, each dimple 532 includes a second axis (not labeled) that extends into and out of the page. Each dimple 532 is separated from adjacent dimple(s) by spacing 538. The side 539 of the patterned layer 530 facing the micro-LED panel (the micro-LED panel not shown for clarity purposes) is also shown.

[0051] Patterned layer 540 has an irregular surface pattern. That is, different from the periodicity illustrated in the embodiments for patterned layers 510, 520, 530, patterned layer 540 is not defined by a pattern of repeating surface features. The side 549 of the patterned layer 530 facing the micro-LED panel (the micro-LED panel not shown for clarity purposes) is also shown. In some embodiments, patterned layer 540 contains high-frequency spectral components which generate reflections of light at large oblique angle when received from the side opposite to side 549.

[0052] Patterned layer 550 has a surface pattern defined by a series of concentric circles. In some embodiments, the series of concentric circles is implemented as a stacked layer of circular shapes or as a single layer comprising a series of annular ridges. In either case, patterned layer 550 is rotationally symmetric which can provide a lensing capability when designed in combination with one or more elements of the LEA (not shown in FIG. 5).

[0053] FIG. 6 shows an example of a process 600 for fabricating a patterned layer (such as the patterned layers of FIGs. 2, 3, 4, and 5) on a front surface of a micro- LED panel in accordance with various embodiments.

[0054] At 610, the method includes positioning a microLED panel 612 under an inkjet dispenser (not shown). The microLED panel 612 includes a plurality of sets of adjacent RGB pixels 616 (one set labeled for clarity) on a substrate 614. Although not depicted for clarity purposes, the microLED panel 612 includes a back surface reflector positioned between each set of RGB pixels 616 and the substrate 614.

[0055] At 620, the inkjet dispenser applies 622 a polymer resin 624 on the front surface of the microLED panel 612. A particular amount of polymer resin 624 isapplied individually to each set of RGB pixels 616 so as to coat the front surface of the set of RGB pixels 616 and the sides of the set of RGB pixels 616. In the illustrated embodiment, the inkjet dispenser applies the polymer resin 624 so as to leave a gap 626 between each set of adjacent RGB pixels. In other embodiments, the inkjet dispenser (or alternative polymer resin dispensing method) does not leave gap 626 between the sets of RGB pixels 616 and the gap between sets of RGB pixels is implemented in the following step.

[0056] At 630, the polymer resin is subject to nanoimprint lithography (NIL) 632 so as to form the surface pattern 634 of the patterned layer applied to the front of the microLED panel 612. For example, NIL 632 includes applying a mold with surface features to the front surface of the polymer resin 624 applied at step 620, releasing the mold, and curing the polymer resin. In addition to imparting the surface pattern 634, the NIL 632 maintains, or alternatively imparts, the gap 636 between adjacent sets of RGB pixels 616 as described above. As such, each set of RGB pixels 616 is optically separated from one another so light from one set of RGB pixels does not leak into an adjacent set of RGB pixels.

[0057] In an alternative embodiment, an additional step involving planarization of the top surface of the polymer resin layer 624 applied at step 620 is included prior to NIL at step 630.

[0058] FIG. 7 shows an example of a process 700 for fabricating a patterned layer (such as the patterned layers of FIGs. 2, 3, and 5) on a front surface of a micro-LED panel in accordance with various embodiments.

[0059] At 710, the method includes positioning a microLED panel 712 under an inkjet dispenser (not shown). The microLED panel 712 includes a plurality of stacks of RGB pixels 716 (one stack labeled for clarity) on a substrate 714. Although not depicted for clarity purposes, the microLED panel 712 includes a back surface reflector positioned between each stack of RGB pixels 716 and the substrate 714.

[0060] At 720, the inkjet dispenser applies 722 a polymer resin 724 on the front surface of the microLED panel 712. A particular amount of polymer resin 724 is applied individually to each stack of RGB pixels 716 so as to coat the front surface ofthe stack of RGB pixels 716 and the sides of the stack of RGB pixels 716. In the illustrated embodiment, the inkjet dispenser applies the polymer resin 724 so as to leave a gap 726 between each stack of adjacent RGB pixels. In other embodiments, the inkjet dispenser (or alternative polymer resin dispensing method) does not leave gap 726 between the stacks of RGB pixels 716 and the gap between stacks of RGB pixels is implemented in the following step.

[0061] At 730, the polymer resin is subject to nanoimprint lithography (NIL) 732 so as to form the surface pattern 734 of the patterned layer applied to the front of the microLED panel 712. For example, NIL 732 includes applying a mold with surface features to the front surface of the polymer resin 724 applied at step 720, releasing the mold, and curing the polymer resin. In addition to imparting the surface pattern 734, the NIL 732 maintains, or alternatively imparts, the gap 736 between adjacent stacks of RGB pixels 716 as described above. As such, each stack of RGB pixels 716 is optically separated from one another so light from one stack of RGB pixels does not leak into an adjacent stack of RGB pixels.

[0062] In an alternative embodiment, an additional step involving planarization of the top surface of the polymer resin layer 724 applied at step 720 is included prior to NIL at step 730.

[0063] In some embodiments, the patterned layer is formed separately from the micro-LED panel and subsequently bonded to the front surface of the micro-LED panel using an adhesive with suitable optical properties.

[0064] FIG. 8 shows an example of a flowchart 800 illustrating a method for reducing the generation of ghost artifacts in an eyewear display according to some embodiments. The eyewear display includes a micro-LED panel as an image source, an LEA, and a waveguide with an incoupler as described in any one of the previous figures.

[0065] At 802, the method includes emitting light from a micro-LED panel through a patterned layer. For example, referring to the previous figures, the micro-LED panel is the image source of the eyewear display such as eyewear display 100 of FIG. 1 and the patterned layer is any one of the patterned layers described in FIGs. 1-7.

[0066] At 804, the method includes incoupling a first portion of the light emitted from the micro-LED panel into a waveguide. For example, referring to the previous figures, the waveguide is waveguide 220 of FIGs. 2 and 3 or waveguide 420 of FIG. 4. A second portion of the light emitted from the micro-LED panel is reflected by the incoupler back towards the micro-LED panel, such as depicted in FIG. 4.

[0067] At 806, the method includes scattering, via the patterned layer, the second portion of light that is reflected back towards the micro-LED panel. In some embodiments, the patterned layer scatters this light (also referred to as display beam reflections) away from the LEA (such as LEA of FIGs. 2, 3, and 4) so that it is not redirected back towards the incoupler of the waveguide, such as depicted in FIG. 4. As such, the generation of ghost artifacts is reduced or eliminated.

[0068] In some embodiments, certain aspects of the techniques described above may be implemented by one or more processors of a processing system executing software. The software comprises one or more sets of executable instructions stored or otherwise tangibly embodied on a non-transitory computer readable storage medium. The software can include the instructions and certain data that, when executed by the one or more processors, manipulate the one or more processors to perform one or more aspects of the techniques described above. The non-transitory computer readable storage medium can include, for example, a magnetic or optical disk storage device, solid state storage devices such as Flash memory, a cache, random access memory (RAM) or other non-volatile memory device or devices, and the like. The executable instructions stored on the non-transitory computer readable storage medium may be in source code, assembly language code, object code, or other instruction format that is interpreted or otherwise executable by one or more processors.

[0069] Note that not all of the activities or elements described above in the general description are required, that a portion of a specific activity or device may not be required, and that one or more further activities may be performed, or elements included, in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed. Also, the concepts have been described with reference to specific embodiments. However, one ofordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure.

[0070] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims. Moreover, the particular embodiments disclosed above are illustrative only, as the disclosed subject matter may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. No limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope of the disclosed subject matter. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

WHAT IS CLAIMED IS:1 . An eyewear display comprising: a micro-light emitting diode (micro-LED) panel; a patterned layer applied over a front surface of the micro-LED panel, wherein the micro-LED panel is configured to emit light through the patterned layer; and a waveguide comprising an incoupler to incouple light emitted from the micro- LED panel, wherein a portion of emitted light incident on the incoupler is reflected back towards the micro-LED panel as a display beam reflection, wherein the patterned layer is configured to scatter the display beam reflection away from the micro-LED panel.

2. The eyewear display of claim 1 , wherein the patterned layer comprises a surface pattern that transmits light incident thereon from a first side adjacent to the micro-LED panel and scatters light that is incident thereon from a second side that is opposite to the first side.

3. The eyewear display of claim 2, wherein the surface pattern reflects light that is incident thereon from the second side at oblique angles such that the reflections of light are not transmitted back towards the incoupler.

4. The eyewear display of claim 2, wherein the surface pattern transmits light that is incident thereon from the first side, wherein the light that is incident thereon from the first side comprises light having red, green, and blue wavelengths.

5. The eyewear display of claim 4, wherein the surface pattern scatters light that is incident thereon from the second side, wherein the light that is incident thereon from the second side comprises light having red, green, and blue wavelengths.

6. The eyewear display of claim 4, wherein the surface pattern scatters light that is incident thereon from the second side, wherein the light is incident on thesecond side at a range of angles from -30° to 30°, wherein 0° corresponds to a normal direction from the front surface of the micro-LED panel.

7. The eyewear display of claim 4, wherein the surface pattern scatters light that is incident thereon from the second side, wherein the light that is incident thereon from the second side comprises one or more of S-polarized light or P- polarized light.

8. The eyewear display of claim 2, wherein the surface pattern comprises a periodic structure, wherein the periodic structure comprises a diffraction grating with either a binary, blazed, or slanted profile or a metasurface.

9. The eyewear display of claim 2, wherein the surface pattern is rotationally symmetric.

10. The eyewear display of claim 2, wherein the surface pattern is a random texture that generates reflections of light incident on the second side.11 . The eyewear display of claim 1 , wherein the front surface of the micro-LED panel is opposite to a back surface of the micro-LED panel comprising a back reflector.

12. The eyewear display of claim 11 , wherein the micro-LED panel comprises a plurality of micro-LEDs arranged adjacent to one another on a substrate, wherein the patterned layer is applied across the plurality of micro-LEDs.

13. The eyewear display of claim 12, wherein the patterned layer comprises multiple subsections, wherein each subsection of the multiple subsections covers a subset of the plurality of micro-LEDs, wherein the subset comprises a red micro-LED, a green micro-LED, and a blue micro-LED, wherein the patterned layer comprises a gap between adjacent subsections of the multiple subsections.

14. The eyewear display of claim 11 , wherein the micro-LED panel comprises a plurality of micro-LEDs arranged in a stack on a substrate, wherein the patterned layer is applied across a top layer of the stack.

15. The eyewear display of claim 14, wherein the patterned layer comprises multiple subsections, wherein each subsection of the multiple subsections covers a subset of the plurality of micro-LEDs, wherein the subset comprises a red micro-LED, a green micro-LED, and a blue micro-LED arranged in a stack, wherein the patterned layer comprises a gap between adjacent subsections of the multiple subsections.

16. The eyewear display of claim 1 , wherein the patterned layer modifies an emission profile of light emitted from the micro-LED panel to increase an amount of light that is propagated towards the incoupler.

17. A method comprising: emitting light from a micro-light emitting diode (LED) panel in an eyewear display through a patterned layer applied over a front surface of the micro-LED panel; incoupling, via an incoupler, a first portion of the light emitted from the micro- LED panel into a waveguide arranged in a lens of the eyewear display, wherein a second portion of the light is reflected from the incoupler back towards the micro-LED panel; and scattering, via the patterned layer, the second portion of the light before it reaches the micro-LED panel.

18. The method of claim 17, wherein at least some of the scattered second portion of light is absorbed by other components of the eyewear display such that it is not reflected back towards the incoupler.

19. A method comprising: applying a polymer resin using an inkjet-dispense process to a micro-light emitting diode (LED) panel; and patterning the resin via nanoimprint lithography to create an optically selective surface pattern on the micro-LED panel, wherein the optically selective surface pattern transmits light received from a first side corresponding to receiving light from the micro-LED panel and scatters light received from a second side opposite to the first side.

20. The method of claim 19, wherein the micro-LED panel comprises a plurality of subsets of micro-LEDs, wherein each subset of the plurality of subsets comprises a red micro-LED, a green micro-LED, and a blue micro-LED, and wherein patterning the resin via nanoimprint lithography comprises creating gaps in the resin between adjacent subsets of the plurality of subsets.

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