Athermalization concept for polymer eyepieces used in augmented reality or mixed reality devices

Abstract

An embodiment of the present disclosure provides a system and method for a display. In an embodiment, the display system includes a frame, an eyepiece coupled to the frame, and a first adhesive bond disposed between the frame and the eyepiece. The eyepiece can include a light entry region and a light exit region. The first adhesive bond can be disposed along a first portion of a circumference of the eyepiece, the first portion of the circumference of the eyepiece abutting the light entry region such that the first adhesive bond is configured to maintain a position of the light entry region relative to the frame.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the priority of U.S. Provisional Patent Application No. 63 / 160,419, filed on March 12, 2021, the content of which is hereby incorporated by reference in its entirety.

[0002] Field The present disclosure generally relates to systems for displaying visual information, and more particularly to eyewear for displaying visual information in an extended reality or mixed reality environment.

Background Art

[0003] Background Virtual environments are ubiquitous in computing environments and are used in video games (where the virtual environment can represent a game world); maps (where the virtual environment can represent the terrain to be navigated); simulations (where the virtual environment can simulate a real - world environment); digital storytelling (where virtual characters can interact with each other in the virtual environment); and many other applications. Modern computer users generally perceive and interact comfortably with virtual environments. However, the user experience with virtual environments can be limited by the technology used to present the virtual environment. For example, conventional displays (e.g., a 2D display screen) and audio systems (e.g., fixed speakers) may not be able to realize a virtual environment in a way that creates an attractive, realistic, and immersive experience.

[0004] Virtual reality ("VR"), augmented reality ("AR"), mixed reality ("MR"), and related technologies (collectively "XR") share the ability to present users of XR systems with sensory information corresponding to a virtual environment represented by data within a computer system. This disclosure assumes distinctions between VR systems, AR systems, and MR systems (however, some systems may be classified as VR in one aspect (e.g., a visual aspect) and simultaneously as AR or MR in another aspect (e.g., an auditory aspect)). As used herein, a VR system presents a virtual environment that replaces the user's real environment in at least one aspect. For example, a VR system may present a user with a view of the virtual environment while simultaneously obscuring the view of the real environment, such as by using a light-shielding head-mounted display. Similarly, a VR system may present a user with sounds corresponding to the virtual environment while simultaneously blocking (attenuating) sounds from the real environment.

[0005] VR systems can experience various drawbacks stemming from replacing the user's real-world environment with a virtual one. One drawback is the sensation of motion sickness that can occur when the user's field of view in the virtual environment no longer corresponds to the state of their inner ear that detects their balance and orientation in the real (non-virtual) environment. Similarly, users may experience disorientation in a VR environment where they cannot directly see their own body and limbs (the view on which the user feels "grounded" in the real world). Another drawback is the computational load (e.g., storage, processing power) imposed on VR systems, especially in real-time applications that aim to immerse the user in the virtual environment, as they must present a complete 3D virtual environment. Likewise, users tend to be sensitive to even slight imperfections in the virtual environment, any of which can detract from the sense of immersion; therefore, such environments may need to reach a very high standard of presence to be considered immersive. Furthermore, another drawback of VR systems is that such applications of the system cannot utilize the wide range of sensory data from the real world, such as the various sights and sounds experienced in the real world. A related drawback is that VR systems can sometimes struggle to create a shared environment where multiple users can interact, because users sharing a physical space in the real world may not be able to see or interact with each other directly in the virtual environment.

[0006] As used herein, an AR system presents a virtual environment that overlaps with or overlays the real environment in at least one aspect. For example, an AR system can present a user with a view of the virtual environment overlaid on the user's view of the real environment, such as a transparent head-mounted display that presents a display image while allowing light to pass through the display and enter the user's eyes. Similarly, an AR system can present a user with audio corresponding to the virtual environment while simultaneously mixing audio from the real environment. Likewise, as used herein, an MR system, like an AR system, presents a virtual environment that overlaps with or overlays the real environment in at least one aspect, and further, the virtual environment within the MR system may enable interaction with the real environment in at least one aspect. For example, a virtual character in the virtual environment may toggle a light switch in the real environment, turning a corresponding light bulb in the real environment on or off. As another example, a virtual character may react (e.g., with facial expressions) to audio signals in the real environment. By maintaining the presentation of the real environment, AR and MR systems can avoid some of the aforementioned shortcomings of VR systems. For example, visual cues from the real environment (including the user's own body) can remain visible, and such systems do not need to present the user with a fully realized 3D environment for immersion, thus reducing user motion sickness. Furthermore, AR and MR systems can utilize sensory input from the real world (e.g., scenery, objects, and the views and sounds of other users) to create new applications that enhance that input.

[0007] Presenting a virtual environment in a realistic way and creating a robust and cost-effective user immersion experience can be challenging. For example, a head-mounted display may include an optical system with one or more multilayer glass eyepieces. Glass eyepieces can be expensive and fragile components. For instance, each layer may be manufactured through a complex process involving multiple steps to achieve a diffraction grating and associated film for effectively projecting a digital image to the user. Furthermore, glass can be a fragile component that is prone to failure or damage if the head-mounted display is not handled carefully. Therefore, there is a need for an eyepiece that is easier to manufacture and more robust than a glass eyepiece, without sacrificing the quality of the digital image. [Overview of the project] [Means for solving the problem]

[0008] overview This specification discloses systems and methods for displays, such as those for head-wearable devices. An exemplary display may include a frame, an eyepiece coupled to the frame, and a first adhesive joint positioned between the frame and the eyepiece. The eyepiece may include a light-incident region and a light-ejecting region. The first adhesive joint may be positioned along a first portion of the outer periphery of the eyepiece, the first portion of the outer periphery of the eyepiece being in contact with the light-incident region such that the first adhesive joint is configured to maintain the position of the light-incident region relative to the frame. Embodiments disclosed herein may provide a robust and easily manufactured display system capable of providing consistent digital image quality during use. The present invention provides, for example, the following: (Item 1) It is a display, Frame and, An eyepiece coupled to the frame, wherein the eyepiece is The region where light is incident, Light emission region and An eyepiece equipped with, A first adhesive joint positioned between the frame and the eyepiece Equipped with, The first adhesive bond is positioned along a first portion of the outer circumference of the eyepiece, and the first portion of the outer circumference of the eyepiece is in contact with the light incident region, such that the first adhesive bond maintains the position of the light incident region relative to the frame, in a display. (Item 2) The display according to item 1, further comprising a second adhesive joint positioned between the frame and the eyepiece, wherein the second adhesive joint is positioned along a second portion of the outer circumference of the eyepiece, the second portion of the outer circumference of the eyepiece is in contact with the light-emitting region, and the second adhesive joint is configured to allow in-plane expansion of the eyepiece relative to the frame. (Item 3) The display according to item 1, wherein the first adhesive bond is associated with a first elastic modulus, the second adhesive bond is associated with a second elastic modulus, and the first elastic modulus is greater than the second elastic modulus. (Item 4) The display according to item 1, further comprising a third adhesive bond, the third adhesive bond being associated with the first elastic modulus, and the first and third adhesive bonds being positioned on both sides of the light incident region. (Item 5) The display according to item 4, wherein the length of the first adhesive bond is less than half the length of the light incident region. (Item 6) The display according to item 1, wherein the first adhesive bonding portion includes an arc-shaped bonding portion positioned in close proximity to the outer periphery of the light incident region. (Item 7) It is an eyepiece, The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers are placed between the first eyepiece layer and the second eyepiece layer. Equipped with, The one or more edge spacers mentioned above are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer An eyepiece configured to perform the following actions. (Item 8) The eyepiece described in item 7, wherein one or more edge spacers are coupled to the first eyepiece layer. (Item 9) The eyepiece according to item 8, further comprising a layer of lubricant disposed between the one or more edge spacers and the second eyepiece layer. (Item 10) The eyepiece according to item 8, wherein the one or more edge spacers are formed integrally with the first eyepiece layer. (Item 11) The first eyepiece layer is made from the first material, The one or more edge spacers are made from a second material different from the first material. The second material has a lower coefficient of friction than the first material. The eyepiece described in item 8. (Item 12) The eyepiece according to item 7, wherein the first surface of the first eyepiece layer is provided with a slot, and the corresponding edge spacers of the one or more edge spacers are positioned within the slot. (Item 13) The eyepiece according to item 7, further comprising a plurality of pillar spacers disposed between the first eyepiece layer and the second eyepiece layer, wherein the plurality of pillar spacers are configured to maintain a consistent spacing between the first eyepiece layer and the second eyepiece layer. (Item 14) It is a display, Frame and, An eyepiece coupled to the frame, wherein the eyepiece is The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers are placed between the first eyepiece layer and the second eyepiece layer. It is equipped with an eyepiece and Equipped with, The one or more edge spacers mentioned above are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer A display configured to perform the following actions. (Item 15) The display according to item 14, wherein the frame comprises a cap arranged along the outer circumference of the frame. (Item 16) The aforementioned frame is A first stage corresponding to the first outer perimeter, The second stage corresponding to the second outer perimeter and Equipped with, The display according to item 14, wherein the first eyepiece layer is arranged in the first step along the first outer circumference, and the second eyepiece layer is arranged in the second step along the second outer circumference. (Item 17) The display according to item 14, wherein the one or more edge spacers are formed integrally with the first eyepiece layer. (Item 18) The display according to item 17, further comprising a layer of lubricant disposed between the one or more edge spacers and the second eyepiece layer. (Item 19) The display according to item 14, wherein the first surface of the first eyepiece layer is provided with a slot, and the corresponding edge spacers of the one or more edge spacers are positioned within the slot. [Brief explanation of the drawing]

[0009] [Figure 1A] Figures 1A to 1C illustrate exemplary mixed reality environments relating to one or more embodiments of the present disclosure. [Figure 1B] Figures 1A to 1C illustrate exemplary mixed reality environments relating to one or more embodiments of the present disclosure. [Figure 1C] Figures 1A to 1C illustrate exemplary mixed reality environments relating to one or more embodiments of the present disclosure.

[0010] [Figure 2A] Figures 2A to 2D illustrate components of an exemplary mixed reality system that can be used to generate and interact with a mixed reality environment, according to one or more embodiments of the present disclosure. [Figure 2B] Figures 2A to 2D illustrate components of an exemplary mixed reality system that can be used to generate and interact with a mixed reality environment, according to one or more embodiments of the present disclosure. [Figure 2C] Figures 2A to 2D illustrate components of an exemplary mixed reality system that can be used to generate and interact with a mixed reality environment, according to one or more embodiments of the present disclosure. [Figure 2D] Figures 2A to 2D illustrate components of an exemplary mixed reality system that can be used to generate and interact with a mixed reality environment, according to one or more embodiments of the present disclosure.

[0011] [Figure 3A] Figure 3A shows an exemplary mixed reality handheld controller that can be used to provide input to a mixed reality environment, according to one or more embodiments of the present disclosure.

[0012] [Figure 3B] Figure 3B shows an exemplary auxiliary unit that can be used with an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0013] [Figure 4] Figure 4 shows an exemplary functional block diagram of an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0014] [Figure 5] Figure 5 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0015] [Figure 6] Figure 6 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0016] [Figure 7] Figure 7 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0017] [Figure 8] Figure 8 shows an exemplary eyepiece and mounting scheme for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0018] [Figure 9] Figure 9 shows an exemplary eyepiece and mounting scheme for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0019] [Figure 10] Figure 10 shows an exemplary eyepiece and mounting scheme for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0020] [Figure 11] Figure 11 shows an exemplary eyepiece and mounting scheme for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0021] [Figure 12] Figure 12 shows an exemplary eyepiece and mounting scheme for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0022] [Figure 13] Figures 13A to 13C show examples of the bimetallic effect.

[0023] [Figure 14]Figure 14 is a chart illustrating exemplary performance degradation based on increasing interlayer CTE variation according to one or more embodiments of the present disclosure.

[0024] [Figure 15] Figure 15 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0025] [Figure 16] Figure 16 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0026] [Figure 17] Figure 17 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0027] [Figure 18] Figure 18 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0028] [Figure 19] Figure 19 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0029] [Figure 20] Figure 20 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0030] [Figure 21] Figure 21 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0031] [Figure 22]Figure 22 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0032] [Figure 23] Figure 23 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0033] [Figure 24] Figure 24 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure.

[0034] [Figure 25] Figure 25 shows an exemplary eyepiece for an exemplary mixed reality system according to one or more embodiments of the present disclosure. [Modes for carrying out the invention]

[0035] Detailed explanation The following examples refer to the accompanying drawings illustrating specific examples that form part of this specification and can be implemented. It should be understood that other examples may be used and structural modifications may be made without departing from the scope of the disclosed examples. Mixed reality environment

[0036] Like all people, users of a mixed reality system are present in the real environment, that is, in all three-dimensional parts and contents of the "real world" that are perceptible to the user. For example, the user perceives the real environment using their normal human senses (sight, sound, touch, taste, smell) and interacts with the real environment by moving their body within it. A position in the real environment can be described as coordinates in coordinate space. For example, coordinates can include latitude, longitude, and altitude relative to sea level; distance in three orthogonal dimensions from a reference point; or other appropriate values. Similarly, vectors can describe quantities that have direction and magnitude in coordinate space.

[0037] A computing device can maintain a representation of a virtual environment in, for example, the memory associated with the device. As used herein, a virtual environment is a computational representation of a three-dimensional space. A virtual environment can include representations of any object, action, signal, parameter, coordinate, vector, or other properties associated with that space. In some examples, the circuitry of a computing device (e.g., a processor) can maintain and update the state of a virtual environment. That is, the processor can determine the state of the virtual environment at a second time t1 based on data associated with the virtual environment and / or inputs provided by the user at a first time t0. For example, if an object in the virtual environment is located at a first coordinate at time t0 and has certain programmed physical parameters (e.g., mass, coefficient of friction), the input received from the user instructs that a force should be applied to the object in a direction vector. The processor can apply the laws of kinematics to determine the object's position at time t1 using basic mechanics. The processor can determine the state of the virtual environment at time t1 using any appropriate information known about the virtual environment and / or any appropriate inputs. When maintaining and updating the state of a virtual environment, the processor may execute any appropriate software, including: software related to the creation and deletion of virtual objects in the virtual environment; software for defining the behavior of virtual objects or characters in the virtual environment (e.g., scripts); software for defining the behavior of signals in the virtual environment (e.g., audio signals); software for creating and updating parameters associated with the virtual environment; software for generating audio signals in the virtual environment; software for handling input and output; software for implementing network operations; software for applying asset data (e.g., animation data for moving virtual objects over time); or many other possibilities.

[0038] Output devices such as displays or speakers can present any or all aspects of a virtual environment to the user. For example, a virtual environment may include virtual objects that can be presented to the user (this may include representations of inanimate objects; people; animals; lights, etc.). A processor can determine the view of the virtual environment (e.g., corresponding to a “camera” with origin coordinates, view axes, and a frustum) and render a viewable scene of the virtual environment corresponding to that view on the display. Any suitable rendering technique may be used for this purpose. In some examples, the viewable scene may include only some virtual objects in the virtual environment and exclude certain other virtual objects. Similarly, a virtual environment may include audio aspects that can be presented to the user as one or more audio signals. For example, virtual objects in a virtual environment may generate sounds resulting from the object’s position coordinates (e.g., a virtual character may speak or produce sound effects). Alternatively, a virtual environment may be associated with musical cues or ambient sounds that may or may not be associated with a specific location. The processor can handle audio signals corresponding to "listener" coordinates, such as the synthesis of sounds within a virtual environment, determine a mixed and processed audio signal to simulate the audio signal heard by the listener at listener coordinates, and present the audio signal to the user through one or more speakers.

[0039] Because virtual environments exist only as computational structures, users cannot directly perceive them using their normal senses. Instead, users can only perceive virtual environments indirectly, such as through displays, speakers, or haptic output devices. Similarly, while users cannot directly touch, manipulate, or interact with virtual environments, they can provide input data via input devices or sensors to a processor that can use the device or sensor data to update the virtual environment. For example, a camera sensor can provide optical data indicating that the user is attempting to move an object within the virtual environment, and the processor can use that data to cause the object to respond accordingly within the virtual environment.

[0040] A mixed reality system can present a user with a mixed reality environment ("MRE") that combines aspects of the real and virtual environments, for example, using a transparent display and / or one or more speakers (which may be incorporated, for example, into a wearable head device). In some embodiments, one or more speakers may be located outside the head-mounted wearable unit. As used herein, an MRE is a simultaneous representation of the real environment and its corresponding virtual environment. In some examples, the corresponding real and virtual environments share a single coordinate space. In some examples, the real coordinate space and the corresponding virtual coordinate space are related to each other by a transformation matrix (or other suitable representation). Thus, a single coordinate (in some examples, together with the transformation matrix) can define a first location in the real environment and a second corresponding location in the virtual environment, and vice versa.

[0041] In MRE, virtual objects (e.g., in a virtual environment associated with the MRE) can correspond to real-world objects (e.g., in a real-world environment associated with the MRE). For example, if the real-world environment of the MRE includes a real-world ramp post (real-world object) at its position coordinates, the virtual environment of the MRE may include a virtual ramp post (virtual object) at its corresponding position coordinates. As used herein, a real-world object, combined with its corresponding virtual object, constitutes a "mixed-reality object." A virtual object does not need to perfectly match or align with its corresponding real-world object. In some examples, a virtual object can be a simplified version of its corresponding real-world object. For example, if the real-world environment includes a real-world ramp post, the corresponding virtual object may include a cylinder with approximately the same height and radius as the real-world ramp post (reflecting that the ramp post can have a nearly cylindrical shape). Simplifying virtual objects in this way can improve computational efficiency and simplify the calculations performed on such virtual objects. Furthermore, in some examples of MRE, not all real-world objects in the real-world environment are necessarily associated with corresponding virtual objects. Similarly, in some MRE examples, not all virtual objects within the virtual environment are necessarily associated with corresponding real-world objects. That is, some virtual objects may exist only within the MRE's virtual environment without any real-world counterparts.

[0042] In some examples, virtual objects may have properties that sometimes differ significantly from those of their corresponding real-world objects. For instance, a real-world environment within an MRE might contain a green, two-armed cactus (a thorny, inanimate object), while a corresponding virtual object within the MRE might possess the characteristics of a green, two-armed virtual character with human facial features and an expressionless face. In this example, the virtual object resembles its corresponding real-world object in certain properties (color, number of arms), but differs in other properties (facial features, personality). In this way, virtual objects can represent real-world objects in creative, abstract, exaggerated, or imaginative ways, or otherwise give behavior (e.g., human personality) to inanimate real-world objects. In some examples, virtual objects may be purely imaginative creations with no real-world counterparts (e.g., a virtual monster in a virtual environment that, in some cases, occupies a position corresponding to an empty space in the real-world environment).

[0043] Compared to VR systems, which present a virtual environment to the user while obscuring the real environment, mixed reality systems presenting MRE offer the advantage that the real environment remains perceptible while the virtual environment is being presented. Therefore, users of mixed reality systems can experience and interact with the corresponding virtual environment using visual and auditory cues associated with the real environment. For example, as mentioned above, users of VR systems may struggle to perceive or interact with virtual objects displayed in the virtual environment because they cannot directly perceive or interact with it. However, users of MR systems may find it intuitive and natural to interact with virtual objects by seeing, hearing, and touching the corresponding real objects within their own real environment. This level of interactivity can enhance immersion, connection, and engagement with the virtual environment. Similarly, by presenting the real and virtual environments simultaneously, mixed reality systems can reduce the negative psychological (e.g., cognitive dissonance) and physical (e.g., motion sickness) associated with VR systems. Mixed reality systems further offer many possibilities for applications that can enhance or modify the experience of the real world.

[0044] Figure 1A shows an exemplary reality environment 100 in which a user 110 uses a mixed reality system 112. The mixed reality system 112 may include a display (e.g., a transmissive display) and one or more speakers, as well as one or more sensors (e.g., a camera), as described below, for example. The illustrated reality environment 100 includes a rectangular room 104A in which the user 110 is standing, and reality objects 122A (a lamp), 124A (a table), 126A (a sofa), and 128A (a painting). Room 104A further includes position coordinates 106, which can be considered the origin of the reality environment 100. As shown in Figure 1A, an environment / world coordinate system 108 (including x-axis 108X, y-axis 108Y, and z-axis 108Z) having its origin 106 (world coordinates) can define the coordinate space of the reality environment 100. In some embodiments, the origin 106 of the environment / world coordinate system 108 may correspond to the location where the mixed reality system 112 is powered on. In some embodiments, the origin 106 of the environment / world coordinate system 108 may be reset during operation. In some examples, the user 110 may be considered a real object in the real environment 100. Similarly, parts of the user 110's body (e.g., hands, feet) may be considered real objects in the real environment 100. In some examples, a user / listener / head coordinate system 114 (including x-axis 114X, y-axis 114Y, and z-axis 114Z) with point 115 (e.g., user / listener / head coordinate) as its origin can define a coordinate space for the user / listener / head on which the mixed reality system 112 is positioned. The origin 115 of the user / listener / head coordinate system 114 may be defined for one or more components of the mixed reality system 112. For example, the origin 115 of the user / listener / head coordinate system 114 may be defined relative to the display of the mixed reality system 112, such as during the initial calibration of the mixed reality system 112. Matrices (which may include translation matrices and quaternion matrices or other rotation matrices), or other suitable representations, can characterize the transformation between the user / listener / head coordinate system 114 space and the environment / world coordinate system 108 space.In some embodiments, the left ear coordinates 116 and the right ear coordinates 117 may be defined relative to the origin 115 of the user / listener / head coordinate system 114. Matrices (which may include translation matrices and quaternion matrices or other rotation matrices), or other suitable representations, can characterize the transformation between the left ear coordinates 116 and the right ear coordinates 117 and the user / listener / head coordinate system 114 space. The user / listener / head coordinate system 114 can simplify the representation of the user's head, or the position of a head-mounted device relative to, for example, the environment / world coordinate system 108. The transformation between the user coordinate system 114 and the environment coordinate system 108 can be determined and updated in real time using simultaneous localization and mapping (SLAM), visual odometry, or other techniques.

[0045] Figure 1B shows an exemplary virtual environment 130 corresponding to a real environment 100. The illustrated virtual environment 130 includes a virtual rectangular room 104B corresponding to a real rectangular room 104A, a virtual object 122B corresponding to a real object 122A, a virtual object 124B corresponding to a real object 124A, and a virtual object 126B corresponding to a real object 126A. The metadata associated with virtual objects 122B, 124B, and 126B may include information derived from the corresponding real objects 122A, 124A, and 126A. The virtual environment 130 further includes a virtual monster 132 that does not correspond to any real object in the real environment 100. Real object 128A in the real environment 100 does not correspond to any virtual object in the virtual environment 130. A persistent coordinate system 133 (including the x-axis 133X, y-axis 133Y, and z-axis 133Z) with point 134 as its origin can define the coordinate space of virtual content. The origin 134 of the persistent coordinate system 133 may be defined with respect to / relative to one or more real objects, such as real object 126A. Matrices (which may include translation matrices and quaternion matrices or other rotation matrices), or other suitable representations, can characterize transformations between the persistent coordinate system 133 space and the environment / world coordinate system 108 space. In some embodiments, each of the virtual objects 122B, 124B, 126B, and 132 may have its own persistent coordinate point with respect to the origin 134 of the persistent coordinate system 133. In some embodiments, there may be multiple persistent coordinate systems, and each of the virtual objects 122B, 124B, 126B, and 132 may have its own persistent coordinate point with respect to one or more persistent coordinate systems.

[0046] Persistent coordinate data can be coordinate data that persists with respect to the physical environment. Persistent coordinate data may be used by an MR system (e.g., MR systems 112, 200) to position persistent virtual content, and the persistent virtual content does not have to be tied to the movement of the display on which the virtual object is displayed. For example, a two-dimensional screen may only display a virtual object relative to its position on the screen. As the two-dimensional screen moves, the virtual content may move with the screen. In some embodiments, persistent virtual content may be displayed in the corner of a room. The MR user may look at the corner, see the virtual content, look out from the corner (the virtual content may no longer be visible because, due to the user's head movement, it may have moved from within the user's field of view to outside of it), or look behind them and see the virtual content in the corner (similar to how a real object may behave).

[0047] In some embodiments, persistent coordinate data (e.g., a persistent coordinate system and / or persistent coordinate frame) may include an origin and three axes. For example, a persistent coordinate system may be assigned by the MR system to the center of a room. In some embodiments, the user may move around in the room, leave the room, and re-enter the room, and the persistent coordinate system may remain at the center of the room (e.g., persisting relative to the physical environment). In some embodiments, virtual objects may be displayed using a transformation to persistent coordinate data that enables the display of persistent virtual content. In some embodiments, the MR system may use simultaneous localization and mapping to generate persistent coordinate data (e.g., the MR system may assign persistent coordinate systems to points in space). In some embodiments, the MR system may map the environment by generating persistent coordinate data at regular intervals (e.g., the MR system may assign persistent coordinate systems within a grid, where each persistent coordinate system may be at least 5 feet from another persistent coordinate system).

[0048] In some embodiments, persistent coordinate data may be generated by the MR system and transmitted to a remote server. In some embodiments, the remote server may be configured to receive persistent coordinate data. In some embodiments, the remote server may be configured to synchronize persistent coordinate data from multiple observation instances. For example, multiple MR systems may map the same room with persistent coordinate data and transmit that data to the remote server. In some embodiments, the remote server may use this observation data to generate standard persistent coordinate data that can be obtained based on one or more observations. In some embodiments, the standard persistent coordinate data may be more accurate and / or reliable than a single observation of persistent coordinate data. In some embodiments, the standard persistent coordinate data may be transmitted to one or more MR systems. For example, an MR system may use image recognition and / or location data to recognize that it is located in a room with corresponding standard persistent coordinate data (e.g., from the fact that another MR system has previously mapped the room). In some embodiments, an MR system may receive standard persistent coordinate data corresponding to its location from the remote server.

[0049] In relation to Figures 1A and 1B, the environment / world coordinate system 108 defines a shared coordinate space for both the real environment 100 and the virtual environment 130. In the illustrated example, the coordinate space has its origin at point 106. Furthermore, the coordinate space is defined by the same three orthogonal axes (108X, 108Y, 108Z). Thus, a first location in the real environment 100 and a second corresponding location in the virtual environment 130 can be described with respect to the same coordinate space. This simplifies the identification and representation of corresponding locations in the real and virtual environments, as the same coordinates can be used to identify both locations. However, in some examples, the corresponding real and virtual environments do not need to use a shared coordinate space. For example, in some examples (not shown), matrices (which may include translational matrices and quaternion matrices or other rotation matrices), or other suitable representations, can characterize transformations between the real environment coordinate space and the virtual environment coordinate space.

[0050] Figure 1C shows an exemplary MRE 150 that simultaneously presents aspects of the real environment 100 and the virtual environment 130 to the user 110 via the mixed reality system 112. In the illustrated example, the MRE 150 simultaneously presents to the user 110 real objects 122A, 124A, 126A, and 128A from the real environment 100 (e.g., via the transparent portion of the display of the mixed reality system 112) and virtual objects 122B, 124B, 126B, and 132 from the virtual environment 130 (e.g., via the active display portion of the display of the mixed reality system 112). As described above, the origin 106 functions as the origin of the coordinate space corresponding to the MRE 150, and the coordinate system 108 defines the x, y, and z axes of the coordinate space.

[0051] In the illustrated example, the mixed reality object includes corresponding pairs of real and virtual objects (i.e., 122A / 122B, 124A / 124B, 126A / 126B) that occupy corresponding positions in coordinate space 108. In some examples, both real and virtual objects may be visible to the user 110 simultaneously. This may be desirable, for example, when the virtual object presents information designed to extend the view of the corresponding real object (such as in a museum application where the virtual object presents a missing piece of an old, damaged sculpture). In some examples, the virtual object (122B, 124B, and / or 126B) may be displayed in a way that obscures the corresponding real object (122A, 124A, and / or 126A) (e.g., via active pixelated occlusion using a pixelated occlusion shutter). This may be desirable, for example, when the virtual object acts as a visual replacement for the corresponding real object (such as in an interactive storytelling application where an inanimate real object becomes a “living” character).

[0052] In some examples, real-world objects (e.g., 122A, 124A, 126A) may be associated with virtual content or helper data that does not necessarily constitute a virtual object. Virtual content or helper data can facilitate the processing or handling of virtual objects in a mixed reality environment. For example, such virtual content may include a two-dimensional representation of the corresponding real-world object; a custom asset type associated with the corresponding real-world object; or statistical data associated with the corresponding real-world object. This information can enable or facilitate calculations involving real-world objects without incurring unnecessary computational overhead.

[0053] In some examples, the presentation described above may also incorporate audio modes. For example, in MRE150, the virtual monster 132 may be associated with one or more audio signals, such as footsteps generated when the monster walks around MRE150. As will be further described below, the processor of the mixed reality system 112 may compute an audio signal corresponding to the mixture and processed synthesis of all such sounds within MRE150 and present the audio signal to the user 110 via one or more speakers included in the mixed reality system 112 and / or one or more external speakers. Exemplary Mixed Reality System

[0054] An exemplary mixed reality system 112 may include a wearable head device (e.g., a wearable augmented reality or mixed reality head device) comprising: displays (which may comprise left and right transmissive displays, which may be near-eye displays, and associated components for coupling light from the displays to the user's eyes); left and right speakers (e.g., positioned adjacent to the user's left and right ears, respectively); an inertial measuring unit (IMU) (e.g., mounted on the temple arms of the head device); an orthogonal coil electromagnetic receiver (e.g., mounted on the left temple piece); left and right cameras (e.g., depth (time-of-flight) cameras) oriented away from the user; and left and right eye cameras oriented towards the user (e.g., for detecting the user's eye movements). However, the mixed reality system 112 may incorporate any suitable display technology and any suitable sensors (e.g., optical, infrared, acoustic, LiDAR, EOG, GPS, magnetic). Furthermore, the mixed reality system 112 may incorporate networking capabilities (e.g., Wi-Fi capabilities) for communicating with other devices and systems, including other mixed reality systems. The mixed reality system 112 may further include a battery (which may be mounted in an auxiliary unit such as a belt pack designed to be worn around the user's waist), a processor, and memory. The wearable head device of the mixed reality system 112 may include a tracking component, such as an IMU or other suitable sensor, configured to output a set of coordinates of the wearable head device relative to the user's environment. In some examples, the tracking component may provide input to a processor that performs simultaneous localization and mapping (SLAM) and / or visual odometry algorithms. In some examples, the mixed reality system 112 may also include a handheld controller 300 and / or auxiliary unit 320, which may be a wearable belt pack, as further described below.

[0055] Figures 2A to 2D show components of an exemplary mixed reality system 200 (which may correspond to mixed reality system 112) that may be used to present an MRE (which may correspond to MRE150) or other virtual environment to a user. Figure 2A shows a perspective view of a wearable head device 2102 included in the exemplary mixed reality system 200. Figure 2B shows a plan view of the wearable head device 2102 mounted on the user's head 2202. Figure 2C shows a front view of the wearable head device 2102. Figure 2D shows an end view of an exemplary eyepiece 2110 of the wearable head device 2102. As shown in Figures 2A to 2C, the exemplary wearable head device 2102 includes an exemplary left eyepiece (e.g., a left transparent waveguide set eyepiece) 2108 and an exemplary right eyepiece (e.g., a right transparent waveguide set eyepiece) 2110. Each eyepiece 2108 and 2110 may include a transmissive element from which the real environment can be viewed, as well as a display element for presenting a display that overlaps with the real environment (e.g., via imagewise modulated light). In some examples, such a display element may include a surface diffractive optical element for controlling the flow of imagewise modulated light. For example, the left eyepiece 2108 may include a left internally coupled grating set 2112, a left orthogonal pupillary dilation (OPE) grating set 2120, and a left exit (output) pupillary dilation (EPE) grating set 2122. As used herein, pupil may refer to the emission of light from an optical element such as a grating set or reflector. Similarly, the right eyepiece 2110 may include a right internally coupled grating set 2118, a right OPE grating set 2114, and a right EPE grating set 2116. Imagewise modulated light can be transmitted to the user's eye via the internally coupled gratings 2112 and 2118, OPE 2114 and 2120, and EPE 2116 and 2122. Each internally coupled grating set 2112, 2118 can be configured to deflect light toward its corresponding OPE grating set 2120, 2114.Each OPE grating set 2120, 2114 can be designed to gradually deflect light downward toward its associated EPE 2122, 2116, thereby extending the formed exit pupil horizontally. Each EPE 2122, 2116 can be configured to gradually redirect at least a portion of the light received from its corresponding OPE grating set 2120, 2114 toward the user's eyebox position (not shown) defined behind the eyepieces 2108, 2110, thereby extending the formed exit pupil vertically toward the eyebox. Alternatively, instead of the internal coupling grating sets 2112 and 2118, OPE grating sets 2114 and 2120, and EPE grating sets 2116 and 2122, the eyepieces 2108 and 2110 may include other arrangements of gratings and / or refractive and reflective mechanisms to control the coupling of imagewise-modulated light to the user's eye.

[0056] In some examples, the wearable head device 2102 may include a left temple arm 2130 and a right temple arm 2132, the left temple arm 2130 including a left speaker 2134, and the right temple arm 2132 including a right speaker 2136. The orthogonal coil electromagnetic receiver 2138 may be located within the left temple piece or in another suitable location within the wearable head unit 2102. The inertial measurement unit (IMU) 2140 may be located within the right temple arm 2132 or in another suitable location within the wearable head device 2102. The wearable head device 2102 may also include a left depth (e.g., time-of-flight) camera 2142 and a right depth camera 2144. The depth cameras 2142 and 2144 may be appropriately oriented in different directions to cover a wider field of view together.

[0057] In the examples shown in Figures 2A to 2D, the left source 2124 of imagewise modulated light can be optically coupled to the left eyepiece 2108 via the left internal coupling grating set 2112, and the right source 2126 of imagewise modulated light can be optically coupled to the right eyepiece 2110 via the right internal coupling grating set 2118. The imagewise modulated light sources 2124, 2126 can include, for example, fiber optic scanners; projectors including electronic optical modulators such as digital light processing (DLP) chips or liquid crystal on silicon (LCoS) modulators; or light-emitting displays such as micro light-emitting diodes (μLEDs) or micro organic light-emitting diode (μOLED) panels coupled to the internal coupling grating sets 2112, 2118 using one or more lenses on each side. The input coupling grating sets 2112, 2118 can deflect the light from the imagewise modulated light sources 2124, 2126 to an angle exceeding the critical angle of total internal reflection (TIR) ​​of the eyepieces 2108, 2110. The OPE grid sets 2114 and 2120 gradually deflect the light propagating by TIR downwards toward the EPE grid sets 2116 and 2122. The EPE grid sets 2116 and 2122 gradually fuse the light toward the user's face, including the pupil of the user's eye.

[0058] In some examples, as shown in Figure 2D, each of the left eyepiece 2108 and the right eyepiece 2110 includes multiple waveguides 2402. For example, each eyepiece 2108, 2110 may include multiple individual waveguides, each dedicated to its respective color channel (e.g., red, blue, and green). In some examples, each eyepiece 2108, 2110 may include multiple sets of such waveguides, each set configured to impart a different wavefront curvature to the emitted light. The wavefront curvature may be convex to the user's eye, for example, to present a virtual object positioned at a distance in front of the user (e.g., only a distance corresponding to the reciprocal of the wavefront curvature). In some examples, the EPE grid sets 2116, 2122 may include curved grid grooves that achieve convex wavefront curvature by changing the Poynting vector of the emitted light crossing each EPE.

[0059] In some examples, stereoscopically adjusted left and right eye images can be presented to the user through imagewise optical modulators 2124, 2126 and eyepieces 2108, 2110 to create the perception that the displayed content is three-dimensional. The perceived presence of the three-dimensional virtual object can be enhanced by selecting waveguides (and thus corresponding to wavefront curvature) so that the virtual object is displayed at a distance close to the distance indicated by the stereoscopic left and right images. This technique can also reduce motion sickness experienced by some users, which may be caused by the difference between the depth perception cue provided by the stereoscopic left and right eye images and the autonomic nervous system regulation of the human eye (e.g., focus depending on object distance).

[0060] Figure 2D shows a top-down end view of the right eyepiece 2110 of an exemplary wearable head device 2102. As shown in Figure 2D, the multiple waveguides 2402 can include a first subset 2404 of three waveguides and a second subset 2406 of three waveguides. The two subsets of waveguides 2404, 2406 can be distinguished by different EPE gratings featuring different grating line curvatures to impart different wavefront curvatures to the emitted light. Within each subset of waveguides 2404, 2406, each waveguide can be used to couple different spectral channels (e.g., one of the red, green, and blue spectral channels) to the user's right eye 2206. (Although not shown in Figure 2D, the structure of the left eyepiece 2108 is similar to that of the right eyepiece 2110.)

[0061] Figure 3A shows an exemplary handheld controller component 300 of the mixed reality system 200. In some examples, the handheld controller 300 includes a grip portion 346 and one or more buttons 350 arranged along the top surface 348. In some examples, the buttons 350 may be configured to be used as optical tracking targets for tracking, for example, six-degree-of-freedom (6DOF) motion of the handheld controller 300, together with a camera or other optical sensor (which may be mounted on the head unit of the mixed reality system 200 (e.g., a wearable head device 2102)). In some examples, the handheld controller 300 includes a tracking component (e.g., an IMU or other suitable sensor) for detecting position or orientation, such as position or orientation relative to the wearable head device 2102. In some examples, such a tracking component may be located within the handle of the handheld controller 300 and / or mechanically coupled to the handheld controller. The handheld controller 300 can be configured to provide one or more output signals corresponding to one or more of the following: the state of a button being pressed; or the position, orientation, and / or movement of the handheld controller 300 (e.g., via the IMU). Such output signals can be used as inputs to the processor of the mixed reality system 200. Such inputs may correspond to the position, orientation, and / or movement of the handheld controller (and, by extension, the position, orientation, and / or movement of the user's hand holding the controller). Such inputs may also correspond to the user pressing button 350.

[0062] Figure 3B shows an exemplary auxiliary unit 320 of the mixed reality system 200. The auxiliary unit 320 may include a battery to supply energy to operate the system 200 and may include a processor to run programs to operate the system 200. As shown, the exemplary auxiliary unit 320 includes a clip 2128 for attaching the auxiliary unit 320 to a user's belt, for example. Other form factors, including form factors that do not involve attaching the unit to a user's belt, may be suitable for the auxiliary unit 320 and will become apparent. In some examples, the auxiliary unit 320 is coupled to a wearable head device 2102 via a multi-conduit cable that may include, for example, electric wires and optical fibers. Wireless connectivity between the auxiliary unit 320 and the wearable head device 2102 may also be used.

[0063] In some examples, the mixed reality system 200 may include one or more microphones for detecting sound and providing corresponding signals to the mixed reality system. In some examples, the microphones may be attached to or integrated with the wearable head device 2102 and may be configured to detect the user's voice. In some examples, the microphones may be attached to or integrated with the handheld controller 300 and / or auxiliary unit 320. Such microphones may be configured to detect ambient sounds, surrounding noise, the voice of the user or a third party, or other sounds.

[0064] Figure 4 shows an exemplary functional block diagram that may correspond to exemplary mixed reality systems, such as the mixed reality system 200 described above (which may correspond to mixed reality system 112 relating to Figure 1). As shown in Figure 4, the exemplary handheld controller 400B (which may correspond to the handheld controller 300 ("Totem")) includes a totem-to-wearable head device 6-degree-of-freedom (6DOF) totem subsystem 404A, and the exemplary wearable head device 400A (which may correspond to wearable head device 2102) includes a totem-to-wearable head device 6DOF subsystem 404B. In this example, the 6DOF totem subsystem 404A and the 6DOF subsystem 404B work together to determine the six coordinates of the handheld controller 400B relative to the wearable head device 400A (e.g., three translational offsets and three rotations along axes). The six degrees of freedom may be expressed relative to the coordinate system of the wearable head device 400A. The three translational offsets can be represented as X, Y, and Z offsets in such a coordinate system, as a translational matrix, or as any other representation. The rotational degrees of freedom can be represented as a sequence of yaw, pitch, and roll rotations, as a rotation matrix, as a quaternion, or as any other representation. In some examples, a wearable head device 400A; one or more depth cameras 444 (and / or one or more non-depth cameras) included in the wearable head device 400A; and / or one or more optical targets (e.g., button 350 on the handheld controller 400B described above, or a dedicated optical target included in the handheld controller 400B) can be used for 6DOF tracking. In some examples, the handheld controller 400B may include a camera as described above, and the wearable head device 400A may include an optical target for optical tracking in conjunction with the camera. In some examples, the wearable head device 400A and the handheld controller 400B each include a set of three orthogonally oriented solenoids used to wirelessly transmit and receive three identifiable signals.The 6DOF of the wearable head device 400A relative to the handheld controller 400B can be determined by measuring the relative magnitudes of three identifiable signals received in each of the coils used for receiving. Furthermore, the 6DOF totem subsystem 404A may include an inertial measurement unit (IMU) that is useful for providing improved accuracy and / or more timely information regarding the rapid movement of the handheld controller 400B.

[0065] In some embodiments, the wearable system 400 may include a microphone array 407 that includes one or more microphones positioned on a headgear device 400A. In some embodiments, the microphone array 407 may include four microphones. Two microphones may be positioned on the front of the headgear 400A, and two microphones may be positioned on the back of the headgear 400A (e.g., one on the left rear and one on the right rear). In some embodiments, the signals received by the microphone array 407 may be transmitted to a DSP 408. The DSP 408 may be configured to perform signal processing on the signals received from the microphone array 407. For example, the DSP 408 may be configured to perform noise reduction, acoustic echo rejection, and / or beamforming on the signals received from the microphone array 407. The DSP 408 may be configured to transmit the signals to a processor 416.

[0066] In some examples, it may be necessary to transform the coordinates from local coordinate space (e.g., a coordinate space fixed relative to the wearable head device 400A) to inertial coordinate space (e.g., a coordinate space fixed relative to the real environment) in order to compensate for the movement of the wearable head device 400A relative to coordinate system 108. For example, such a transformation may be necessary to maintain the illusion that the virtual object exists in the real environment (and does not appear to be unnaturally positioned in the real environment as the wearable head device 400A moves and rotates), so that the display of the wearable head device 400A presents the virtual object in a position and orientation expected relative to the real environment (e.g., a virtual person sitting in a real chair and facing forward regardless of the position and orientation of the wearable head device), rather than in a fixed position and orientation on the display (e.g., the same position in the lower right corner of the display). In some examples, the compensatory transformation between coordinate spaces can be determined by processing images from the depth camera 444 using SLAM and / or visual odometry procedures to determine the transformation of the wearable head device 400A relative to coordinate system 108. In the example shown in Figure 4, the depth camera 444 can be coupled to the SLAM / visual odometry block 406 and provide images to the block 406. The implementation of the SLAM / visual odometry block 406 may include a processor configured to process these images and determine the position and orientation of the user's head, which can be used to identify transformations between the head coordinate space and another coordinate space (e.g., inertial coordinate space). Similarly, in some examples, additional information about the user's head pose and position is obtained from the IMU 409. The information from the IMU 409 can be integrated with the information from the SLAM / visual odometry block 406 to provide improved accuracy and / or more timely information regarding the rapid adjustment of the user's head pose and position.

[0067] In some examples, the depth camera 444 can supply 3D images to a hand gesture tracker 411, which may be implemented in the processor of a wearable head device 400A. The hand gesture tracker 411 can identify the user's hand gestures, for example, by matching the 3D images received from the depth camera 444 with stored patterns representing hand gestures. Other suitable techniques for identifying the user's hand gestures will become apparent.

[0068] In some examples, one or more processors 416 may be configured to receive data from the wearable head device's 6DOF headgear subsystem 404B, IMU 409, SLAM / visual odometry block 406, depth camera 444, and / or hand gesture tracker 411. The processor 416 may also send and receive control signals from the 6DOF totem system 404A. The processor 416 may be wirelessly coupled to the 6DOF totem system 404A, as in an example where the handheld controller 400B is not connected. The processor 416 may further communicate with additional components such as an audiovisual content memory 418, a graphical processing unit (GPU) 420, and / or a digital signal processor (DSP) voice spatializer 422. The DSP voice spatializer 422 may be coupled to a head-related transfer function (HRTF) memory 425. The GPU 420 may include a left channel output coupled to the left source 424 of the imagewise modulated light and a right channel output coupled to the right source 426 of the imagewise modulated light. The GPU 420 can output stereoscopic image data to the imagewise modulated light sources 424 and 426, for example, as described above with reference to Figures 2A to 2D. The DSP audio spatializer 422 can output audio to the left speaker 412 and / or the right speaker 414. The DSP audio spatializer 422 can receive an input from the processor 419 indicating a direction vector from the user to a virtual sound source (which may be moved by the user, for example, via the handheld controller 320). Based on the direction vector, the DSP audio spatializer 422 can determine the corresponding HRTF (for example, by accessing the HRTF or by interpolating multiple HRTFs). The DSP audio spatializer 422 can then apply the determined HRTF to an audio signal, such as an audio signal corresponding to a virtual sound generated by a virtual object.This can enhance the realism and presence of virtual sounds by incorporating the user's relative position and orientation to virtual sounds in a mixed reality environment; that is, by presenting virtual sounds that match the user's expectations of how those virtual sounds would sound if they were real sounds in a real environment.

[0069] In some examples, as shown in Figure 4, one or more of the processor 416, GPU 420, DSP voice spatializer 422, HRTF memory 425, and audiovisual content memory 418 may be included in an auxiliary unit 400C (which may correspond to the auxiliary unit 320 described above). The auxiliary unit 400C may include a battery 427 for powering its components and / or for powering the wearable head device 400A or the handheld controller 400B. Including such components in an auxiliary unit that can be worn on the user's waist can limit the size and weight of the wearable head device 400A, and thus reduce fatigue in the user's head and neck.

[0070] Figure 4 shows elements corresponding to various components of an exemplary mixed reality system, but various other suitable arrangements of these components will become apparent to those skilled in the art. For example, the elements shown in Figure 4 as associated with the auxiliary unit 400C could instead be associated with the wearable head device 400A or the handheld controller 400B. Furthermore, some mixed reality systems may completely omit the handheld controller 400B or the auxiliary unit 400C. Such variations and modifications should be understood to fall within the scope of the disclosed examples. Example eyepiece

[0071] An exemplary mixed reality system (e.g., mixed reality system 200) wearable head device or head-mounted display may include an optical system having an eyepiece for presenting images to the user via the display. Figures 5–7 show examples of eyepieces that may be used in a wearable head device (e.g., wearable head device 2102) according to embodiments of the present disclosure.

[0072] Figure 5 shows an exemplary eyepiece 500 that may be used in a wearable head device (e.g., wearable head device 2102). The eyepiece 500 may include multiple layers 510. The multiple layers 510 may be arranged in parallel to form an eyepiece stack. As used herein, the term eyepiece may refer to an eyepiece stack formed from multiple eyepiece layers. In some embodiments, one or more of the multiple layers of the eyepiece may include a light incidence region 501 and a light emission region 505. The light incidence region 501 may refer to a region of the eyepiece 500 that receives light from a light source. The light emission region 505 may refer to a region from which light is projected from the eyepiece 500.

[0073] Figure 6 shows an enlarged cross-sectional view of an eyepiece stack 600 having one or more layers. The eyepiece stack 600 may include multiple layers separated by gaps 607. In one or more embodiments, the gaps may be maintained by multiple edge spacers 609 and pillar spacers 611 positioned between each layer. In some embodiments, the eyepiece stack may include one or more layers 610, 620. In some embodiments, different layers may perform different functions. For example, the eyepiece stack 600 may include one or more active layers 610 and one or more cover layers 620. As shown in the figure, the eyepiece stack 600 may include three active layers 610 and two cover layers 620. The cover layers 620 may be positioned to form the outer surface of the eyepiece stack 600. For example, a first cover layer 620 may be positioned on the outer surface of the eyepiece stack 600 that is close to the external environment, and a second cover layer 620 may be positioned on the opposing outer surface of the eyepiece stack 600, closer to the user's eye when the wearable head device is in use. The active layer 610 can be placed between the cover layers 620. In this way, the cover layers 620 can protect the active layer 610 from damage such as loads, scratches, cuts, and cracks.

[0074] As shown in the figure, in some examples, the eyepiece 600 may include at least three active layers 610 and two cover layers 620. The eyepiece may further include spacers positioned between each layer to maintain a gap 607 between the layers. The spacers may include edge spacers 609 and pillar spacers 611. The edge spacers 609 may be provided on the outer periphery of the eyepiece stack 600, for example, on the edge of the eyepiece, to maintain a consistent gap between each layer. In some embodiments, each of the layers 610, 620 may be coupled to the edge spacer 609. These couplings may allow the eyepiece 600 to be processed and mounted as a single unit. In some embodiments, the edge spacers may be formed integrally with the layers. The pillar spacers 611 may be provided across the faces of the layers to maintain a consistent gap 607 between each layer. Maintaining a consistent gap 607 across the periphery and faces of each layer may help ensure that light from each layer is projected in the same direction.

[0075] Figure 7 shows a plan view of the active layer 710 of an eyepiece (e.g., eyepiece 500). The layer 710 may include a light incident region 701 and a light exit region 705. The light incident region 701 and the light exit region 705 may correspond to the light incident region 501 and the light exit region 505 described in relation to eyepiece 500. The light incident region 701 may be configured to receive light from a light source (not shown). The received light can be internally coupled into the layer 710 via the light incident region 701. The internally coupled light 703 can be projected across the layer 710 toward the light exit region 705. The light exit region 705 may be configured to project light from the layer 710 and the eyepiece (e.g., eyepiece 500) toward the eye of a user wearing a head-mounted display.

[0076] As described above, an eyepiece, for example, eyepiece 500 or 600, may comprise multiple layers, each having one or more active layers. In some embodiments, each active layer may be configured to diffract or couple light of a specific wavelength into a corresponding waveguide. For example, the optical system of a head-mounted display may include at least a light source (e.g., light sources 2124, 2126 in Figure 2A) configured to direct light towards the eyepiece. In some embodiments, the light source may be configured to emit light of one or more wavelengths, and the incident region 701 may be tuned to one of these wavelengths. For example, the incident region 701 may be configured to diffract light corresponding to the wavelength emitted by the light source. In some embodiments, the multiple active layers may be stacked together, and each of the light incident regions 701 may be tuned to a different wavelength corresponding to one or more wavelengths emitted by the light source. In this way, an eyepiece, for example, eyepiece 500, can form a multicolor digital image that can be presented to a user wearing a head-mounted display.

[0077] In some embodiments, one or more layers of an eyepiece (e.g., eyepiece 500 or 600) may be formed from a polymer. As mentioned above, glass eyepieces can be fragile and expensive. For example, glass eyepieces included in head-mounted displays can be susceptible to damage due to regular wear and tear, such as dynamic forces from use, handling, and drops on the head-mounted display. Furthermore, manufacturing a glass layer may involve numerous complex manufacturing steps to achieve diffraction gratings and associated films for internal and external bonding of light between the layer and the surface. In comparison, polymer layers can be more robust and easier to manufacture than glass. For example, polymer materials can absorb more energy (about 5-8 times) than glass before breaking. Moreover, polymer layers can be formed relatively easily into various shapes using molds, and diffraction gratings for internal and external bonding of light can be molded directly onto the polymer layer.

[0078] While polymers offer advantages over glass, using them in multilayer eyepieces for head-mounted displays also presents challenges. For example, polymer layers can have a coefficient of thermal expansion (CTE) approximately 10 times greater than that of glass. In other words, when a polymer layer is subjected to temperature changes, it can expand (or contract) up to 10 times more than glass. Furthermore, the CTE of polymers is not as consistent as that of glass. In other words, there can be greater variation in CTE between different batches of the same type of polymer compared to different batches of glass. Therefore, layers formed from the same batch of polymer may experience different amounts of expansion and contraction due to temperature changes.

[0079] In practice, the relatively high and variable CTE of polymers can make it difficult to manufacture polymer eyepieces that can provide consistent, high-quality digital images while maintaining robustness. For example, head-mounted displays can experience temperature increases due to device use and heat generation from electronic components. Therefore, the relatively high CTE of polymers (compared to, for example, glass and metal) can introduce challenges when mounting eyepieces, e.g., eyepiece 500, to materials with lower CTEs. In some embodiments, the eyepiece may be mounted to the head-mounted display via a frame. In some embodiments, the entire circumference of the eyepiece may be mounted to the frame. The frame may be formed from a rigid material such as a metal, e.g., magnesium, which has a relatively low CTE compared to the polymer. This difference in CTE between the metal and polymer can cause the polymer eyepiece to expand more than the metal frame when the head-mounted display is subjected to temperature changes. The relative expansion of the polymer eyepiece to the metal frame can result in eyepiece deformation, which can degrade the performance and quality of the digital image presented to the user.

[0080] Furthermore, for example, variable CTE of polymers between batches can make it difficult to maintain the quality of the digital image presented to the user. For example, the quality of the digital image may depend on maintaining a consistent distance or gap between layers and on the alignment of layers in the stack, e.g., top-down. Variations in CTE between layers can affect the gap and alignment of the layers. For example, as the eyepiece heats up, differences in CTE may cause some layers to expand (longitudinally and laterally) more than others. Longitudinal expansion, e.g., in-plane expansion, may affect the alignment of the layers, particularly the alignment of the light incidence region 701 and the light emission region 705, while lateral expansion, e.g., out-of-plane expansion, may affect the gap size.

[0081] The eyepieces relating to this disclosure may result in athermalization of the fit between the eyepiece, e.g., eyepiece 500 and / or 600, and the frame, as well as between the layers of the eyepiece. As used in this disclosure, athermalization may refer to processes and / or structures used to improve the optical stability (e.g., the quality of the displayed image) of the eyepiece and / or display with temperature variations. Athermalized eyepieces may reduce the effects of relatively large CTE and variable CTE of polymers in eyepieces used in head-mounted displays. Exemplary athermalized mounting

[0082] As mentioned above, polymer eyepieces mounted on a metal frame without using athermalization technology may experience performance degradation when the head-mounted display is subjected to changes in operating temperature and load. For example, a head-mounted display may include one or more polymer eyepieces, such as eyepiece 500, mounted on a metal frame. Mounting the eyepiece to the frame helps to fix the eyepiece to the head-mounted display and align the eyepiece with other components of the optical system, such as a light source, to deliver a digital image to the user. During operation, a head-mounted display including a polymer eyepiece may generate heat. As a result, the polymer eyepiece may expand in all directions, e.g., in-plane expansion in the x and y directions, as well as out-of-plane expansion in the z direction. The amount of expansion can correspond to the entire span of the polymer material in a given direction. Therefore, the eyepiece may expand the most in the plane where longer spans of the polymer material exist and the least in the z direction.

[0083] As described above, the outer circumference of the eyepiece can be attached to the metal frame of the head-mounted display via adhesive. Due to the difference in CTE between the metal and polymer and the dimensions of the components, when the head-mounted display is subjected to temperature changes, the polymer eyepiece may expand more than the metal frame. As a result, the polymer eyepiece may become constrained by the adhesive. The constraints imposed by attaching the polymer eyepiece to the metal frame may lead to deformation of the eyepiece, which may degrade the performance and quality of the digital image presented to the user. For example, deformation may cause misalignment between the layers of the eyepiece and / or between the eyepiece and the light source, affecting the consistency of the gap.

[0084] The mounting method for facilitating athermalization between the frame and the polymer eyepiece according to embodiments of the present disclosure can securely hold the eyepiece in place while allowing the polymer eyepiece to expand and / or contract relative to the metal frame without degrading the quality of the output digital image. Embodiments of the present disclosure may provide a polymer eyepiece, e.g., eyepiece 500, attached to a metal frame using one or more adhesives along the outer circumference of the polymer eyepiece. One or more adhesives and / or frames can fix the polymer eyepiece, e.g., eyepiece 500, to the frame while allowing the eyepiece to expand and / or contract.

[0085] Figure 8 shows an optical system for a mixed reality system, comprising an eyepiece 800 mounted within a frame 830, according to an embodiment of the present disclosure. As shown in the figure, the eyepiece 800, for example, a polymer eyepiece, may be positioned within a metal frame 830. The polymer eyepiece 800 may be bonded to the frame 830 using at least two sets of connectors. The first set of connectors 831 may be formed from a first rigid adhesive, and the second set of connectors may be formed from a second relatively flexible rigid adhesive compared to the adhesive of the first set. For example, if the first set of connectors has a rigidity of about 1000 MPa, the second set of connectors may have a rigidity of about 100 MPa. The adhesives may include, for example, Dymax (E=730 MPa) and Epotek (E=2300 MPa). In some embodiments, the rigidity of the adhesive can be adjusted to achieve desired performance.

[0086] In some embodiments, the first set of couplings 831 may be positioned near the light incident region 801 of the eyepiece 800. For example, the first set of couplings 831 may include at least two coupling segments located on both sides of the light incident region 801 along the outer circumference of the eyepiece 800. The coupling segments may be relatively short in length compared to the size of the eyepiece 800 and the light incident region 801. For example, the coupling segments may be less than half the length of the light incident region. In some embodiments, the coupling segments are shown as being the same length, but the coupling segments may have different lengths. The first set of couplings 831 may be formed from a relatively rigid or hard adhesive. Positioning the first set of couplings 831 with a relatively rigid coupling near the light incident region 801 can restrain the eyepiece near the light incident region 801. In this way, the first set of couplings may be used to maintain alignment between the light incident region 801 and a light source (not shown) during temperature fluctuations of the head-mounted display. Maintaining alignment between the light source and the light incidence region ensures that the eyepiece 800 can properly internally couple light from the light source into the eyepiece 800.

[0087] The second set of couplings 833 may include at least two coupling segments located along the outer circumference of the eyepiece near the light-emitting region 805. The coupling segments may be relatively short in length compared to the size of the eyepiece 800 and the light-emitting region 805. In some embodiments, the coupling segments of the second set of couplings 833 may be the same length as those of the first set of couplings 831 (but not limited thereto). The second set of couplings 833 may be positioned on both sides of the eyepiece 800 and / or the light-emitting region 805 near the region from which incident light, e.g., light 703, is projected across the eyepiece 800. In some embodiments, the second set of flexible couplings may include a single flexible coupling. In some embodiments, the eyepiece 800 can be mounted to the frame 830 without using the second set of couplings, i.e., the eyepiece is mounted to the frame using the first set of couplings 831.

[0088] The second set of joints 833 may be formed from a relatively compliant or softer adhesive compared to the first set of joints 831. For example, the second set of joints 833 may allow movement of the eyepiece 800 due to in-plane expansion and / or contraction. In comparison, the first set of joints 831 may restrict the movement of the eyepiece 800 due to in-plane expansion and / or contraction. The second set of joints 833 may provide additional strength and stability to the eyepiece mounting while minimizing resistance between the eyepiece and the adhesive as the eyepiece expands and / or contracts in plane.

[0089] Figure 9 shows an optical system according to an embodiment of the present disclosure, including an eyepiece 900 mounted within a frame 930. As shown in the figure, the eyepiece 900, for example, a polymer eyepiece, may be positioned within a metal frame 930. The polymer eyepiece 900 may be bonded to the frame 930 using at least two types of bondings, where a first rigid bonding 931 may be formed from a first rigid adhesive, and a second set of flexible bondings 933 may be formed from a second relatively flexible rigid adhesive compared to the first rigid bonding 931. The rigid bonding 931 may be positioned near the light incident region 901. Compared to the first set of bonding 831 shown in Figure 8, the rigid bonding 931 may be positioned along a longer length of the outer circumference of the eyepiece 900 near the light incident region 901. For example, the rigid bonding 931 may form an arc along the outer circumference of the eyepiece 900. This additional length of adhesive may provide greater bonding strength between the eyepiece 800 and the frame 930 compared to the mounting configuration of the eyepiece 900. The flexible joint 933 may be similar to the joint 833 of the second set described above.

[0090] Figures 8 and 9 illustrate specific configurations of the first set of couplings and the second set of couplings, and those skilled in the art will understand that multiple configurations of the first set of couplings and the second set of couplings can be implemented without departing from the scope of the present disclosure. For example, in some embodiments, the first set of rigid couplings may be positioned at different locations along the outer circumference of the eyepiece, for example, based on the shape and / or position of the light incidence and emission regions.

[0091] Figure 10 shows an exemplary eyepiece 1000 for a mixed reality system mounted on a frame 1030 according to an embodiment of the present disclosure. As shown in the figure, the frame may include one or more lips 1035a, 1035b configured to engage with the eyepiece 1000 to prevent out-of-plane deformation and potential damage. The eyepiece 1000 may include one or more layers 1010. One or more layers may include an active layer and / or a cover layer. The frame 1030 may include a primary frame member 1031 having a lip 1035b. The frame 1030 may also include a cap 1033 having a lip 1035a. The cap 1033 may be positioned on the primary frame member 1031 so as to form a gap between the lip 1035a and the lip 1035b. As shown in Figure 10, the lip 1035a may be an upper lip and the lip 1035b may be a lower lip. Those skilled in the art will understand that the upper / lower notation is not intended to limit the scope of the present disclosure.

[0092] The eyepiece 1000 may be positioned within the frame 1030 such that the upper lip 1035a can contact the upper surface 1021 of the eyepiece 1000. The lower lip 1035b can contact the bottom surface 1022 of the eyepiece 1000. In this way, the upper lip 1035a and the lower lip 1035b can secure the eyepiece 1000 with light contact between the eyepiece 1000 and the lips 1035a and 1035b. This light contact may allow the eyepiece 1000 to expand within the frame without deformation. In other words, the gap formed between the upper lip 1035a and the lower lip 1035b may be allowed to boundary the outer circumference of the eyepiece 1000 and hold the eyepiece 1000 within the frame 1030, while still allowing the eyepiece to expand and contract with temperature changes.

[0093] In some embodiments, the frame, including the frame member 1031 and the cap 1033, may be used in conjunction with the adhesive joint described above in relation to Figures 8 and 9. In some embodiments, the lips 1035a, 1035b may be slightly angled with respect to the eyepiece 1000 such that the gap between the lip and the eyepiece (e.g., lip 1035a and the upper surface 1021 of the eyepiece 1000) is smaller at the distal end of the lip. In some embodiments, the cap 1033 may be positioned along the entire circumference of the frame member 1031. In some embodiments, the cap 1039 may be positioned intermittently along the outer segments of the frame member 1031. For example, the caps may be positioned in areas without adhesive joints (e.g., the first joint segment 831 and the second joint segment 833).

[0094] Figure 11 shows an exemplary eyepiece 1100 for a mixed reality device mounted on a frame 1130 according to an embodiment of the present disclosure. As shown in the figure, the frame 1130 may include one or more lips 1135 configured to engage with the eyepiece 1000 to prevent out-of-plane deformation as described with respect to the eyepiece 1100. For example, the frame 1130 may include a primary frame member 1131 and a cap 1133, as described above with respect to the frame 1030. The frame 1130 may further include a layer of foam 1139 positioned on the underside of the cap 1133. The layer of foam 1139 may be positioned so as to lightly contact the upper surface 1121 of the eyepiece 1100 when the eyepiece 1100 is positioned within the frame 1130, i.e., within the gap between the upper lip 1135a and the lower lip 1135b. As the eyepiece 1100 expands and contracts within the frame, the eyepiece 1100 may compress the foam 1039. In this way, the foam 1139 allows the eyepiece to expand with minimal resistance, while applying contact force to the eyepiece 1100 to hold it in place when expansion is not occurring. Compared to the frame 1030, the frame 1130 allows for a wider range of tolerances for the cap 1133 and frame member 1131 due to the presence of the foam layer 1139.

[0095] Figure 12 shows an exemplary eyepiece 1200 mounted on a frame 1230 according to an embodiment of the present disclosure. As shown in the figure, the eyepiece 1200 may include two glass cover layers 1220 that can sandwich one or more polymer active layers 1210. The configuration of this eyepiece will be described in more detail in the layer-by-layer athermalization section. Due to the difference in CTE between glass and polymer, the active layer 1210 and the glass cover layer 1220 may be mounted separately to the frame 1230. This may allow the polymer layer 1210 to expand and contract at a different rate than the glass cover layer 1220 without affecting the bond between the frame 1230 and the cover layer 1220. For example, the glass cover layer 1220 may be mounted to the frame 1230 using a connector 1235, and the polymer active layer 1210 may be mounted to the frame 1230 using a connector 1237.

[0096] As shown in the figures, the polymer active layers 1210 may be attached together to the frame 1230 as a unit, for example, and one or more active layers 1210 can be attached using the connectors 1237. The active layers 1210 may be attached to the frame as shown in Figures 8 and 9. For example, the active layers 1210 may be attached to the frame 1230 using at least one set of rigid connectors, for example, rigid connectors 831. In some embodiments, the active layers 1210 may be attached using one set of rigid connectors and one set of flexible connectors, for example, flexible connectors 833.

[0097] The glass cover layer 1220 can be attached to the frame 1230 using couplings 1235. As shown in the figure, the cover layer 1220 can be attached separately on both sides of the active layer 1210. In some embodiments, the entire circumference of one or more of the glass cover layers 1220 can be coupled to the frame 1230. In other words, the couplings 1235 can be arranged continuously along the outer circumference of the glass cover layer 1220. In some embodiments, the couplings 1235 may be arranged along the outer periphery of the glass cover layer 1220 such that the couplings 1235 span separate segments of the outer circumference.

[0098] Although the above examples are illustrated with respect to specific figures, those skilled in the art will understand that the eyepiece-to-frame mounting schemes according to embodiments of the present disclosure may include embodiments from one or more of the above figures. For example, an optical system having a mounting scheme such as the one described in relation to Figures 8 and 9 may also include a frame having caps, e.g., cap 1033, cap 1133, for restraining out-of-plane movement of the eyepiece, for example, when at least one set of rigid couplings 831 are used to mount the eyepiece 800 to the frame 830. Exemplary interlayer athermalization

[0099] As mentioned above, for example, the variable CTE of a polymer between batches can make it difficult to maintain the quality of the digital image presented to the user. Negative performance due to normal fluctuations in CTE can be attributed to bimetallicity. As used herein, bimetallicity can refer to the deformation of materials that occurs when two or more materials having different CTEs are attached or bonded together and subjected to a temperature change together. Figures 13A to 13C illustrate an example of bimetallicity. As shown in Figure 13A, component 1300A comprises two layers, each layer formed from a different material having a different CTE. For example, layer 1350 may be formed from brass, and layer 1355 may be formed from steel. As shown in the figure, when the component is at a reference temperature, the first and second layers may be flat. As used herein, the reference temperature may refer to a temperature at which neither material is deformed.

[0100] Figure 13B shows component 1300B when heat is applied. Due to the difference in CTE between the two layers, one material may expand more than the other, resulting in displacement or bending of the component. As seen in the figure, brass 1350 may expand more than steel 1355, resulting in convex bending of component 1300. Figure 13C shows component 1300B when cooled (compared to the reference temperature). As seen in the figure, steel 1355 may expand more than brass 1350, resulting in concave bending of component 1300C.

[0101] The bimetallic effect can be applied to polymer lenses, where differences in CTE can cause the eyepiece layers to expand and separate at different rates, negatively impacting eyepiece performance. For example, the eyepiece performance and quality of digital images can depend on maintaining a consistent distance or gap between layers and on the alignment of the layers in the stack, e.g., top-down. Variations in CTE between layers can affect the gap and alignment of the layers.

[0102] For example, different batches of polymer may have a CTE variation of ±5 ppm. This variation in CTE can lead to a decrease in eyepiece performance. Figure 14 shows Chart 1400 illustrating the effect of CTE variation on performance degradation, where the performance degradation corresponds to surface normal RMS rotation. Acceptable performance may correspond to a surface normal root mean square (RMS) rotation of less than 1 arcmin. As shown in the figure, the surface normal RMS rotation increases with increasing CTE, and a variation of ±1 ppm may correspond to an increase of about 1 arcmin or more. Therefore, normal variations in CTE between polymer batches can adversely affect the performance of the eyepiece and the quality of the image produced. Embodiments according to this disclosure may provide an eyepiece that is less susceptible to the effects of bimetallic phenomena.

[0103] Figure 15 shows an exemplary eyepiece 1500 according to an embodiment of the present disclosure. The eyepiece 1500 may include two glass cover layers 1520 flanking one or more polymer active layers 1510. As shown in the figure, the two glass cover layers 1520 may be substantially flat, and the polymer layer 1510 may include flat regions 1562 (e.g., corresponding to regions where the active layer 1510 is substantially flat) and spherical regions 1564 (e.g., corresponding to regions where the active layer is curved). As described above, multiple pillars may be positioned between the various layers to maintain a consistent spacing between each layer. For example, the eyepiece 1500 may include multiple variable-height pillars 1566 positioned between the glass cover layer 1520 and the polymer active layer 1510. In this way, the variable-height pillars 1566 can maintain the spacing between the flat glass cover layer 1520 and the polymer active layer 1510. The eyepiece 1500 may further include a plurality of uniform-height pillars 1568 positioned between polymer active layers 1510. The uniform-height pillars 1568 may be provided to maintain a consistent gap between the polymer active layers. In some embodiments, the plurality of variable-height pillars 1566 and the plurality of uniform-height pillars 1568 may be formed integrally with adjacent polymer active layers. Although the eyepiece 1500 is shown having aligned variable-height pillars 1566 and uniform-height pillars 1568, in some embodiments, the variable-height pillars 1566 and uniform-height pillars 1568 may not be aligned.

[0104] Figure 16 shows a detail view of an eyepiece 1600 for a mixed reality system according to an embodiment of the present disclosure. As shown in the figure, the eyepiece 1600 may include one or more layers and a plurality of spacers, such as pillars. For example, the eyepiece 1600 may include a glass cover layer 1620 sandwiching one or more polymer active layers 1610. A variable height pillar 1666 may extend over the distance between the flat glass layer 1620 and the polymer layer 1610. In some embodiments, the polymer layer 1610 may include a flat region 1662 and a spherical region 1664. In some embodiments, the variable height pillar 1666 may be configured to slide along the glass layer 1620 when an adjacent polymer layer 1610 expands. In some embodiments, the variable height pillar 1666 may be formed integrally with the adjacent polymer layer 1610, thereby allowing the variable height pillar 1666 to move and / or slide along the glass cover layer 1620 based on the expansion of the polymer layer 1610. Due to the difference in CTE between the glass and the polymer, the glass layer 1620 can be attached to the frame 1630 separately from the polymer active layer 1610, as described with respect to Figure 12.

[0105] Forming eyepieces with one or more glass cover layers instead of a polymer cover layer, e.g., eyepieces 1500 and / or 1600, can leverage the relative rigidity of glass compared to polymer to maintain the shape of the active layer when the eyepiece heats up. For example, because glass has a relatively low CTE, the glass cover layer can retain its shape even when the display heats up and / or consistently maintain its shape over the operating temperature of the head-mounted display. Furthermore, because the polymer layer 1610 is sandwiched between relatively rigid glass cover layers 1620, deformation and / or separation of the polymer active layer 1610 can be limited. That is, the glass cover layer 1620 may also be able to resist the deformation of the polymer layer 1610 located within it. Moreover, the glass cover layer 1620 can be relatively cost-effective because it does not require the expensive manufacturing steps associated with forming the glass active layer. Furthermore, a more durable surface finish can be achieved on the glass cover layer compared to a glass active layer, providing a more robust eyepiece. The surface finish may include, but is not limited to, Gorilla Glass. In some examples, embodiments relating to eyepieces 1500 and / or 1600 can improve the performance of non-athermalized eyepieces by up to 90%.

[0106] Figure 17 shows an eyepiece 1700 according to an embodiment of the present disclosure. As shown in the figure, the eyepiece may include multiple layers, including one or more cover layers 1722, 1724 and one or more active layers 1710. Embodiments according to the example may utilize the bimetallic effect to "tune" the upper and lower cover layers so that the eyepiece can be deformed as a unit. In other words, the upper cover layer 1722 may be pre-selected to have a relatively high CTE compared to the CTE of the active layer 1710, and the lower cover layer 1724 may be pre-selected to have a relatively low CTE. For example, if the active layer 1710 has a CTE variation of ±5 ppm, the cover layers may vary by ±10 ppm or ±20 ppm. Thus, the behavior of the cover layers of the eyepiece is known, and as the eyepiece temperature rises, the upper cover layer 1722 may expand, while the lower cover layer 1724 may contract so that it resembles component 1300B when the eyepiece 1700 is heated. In other words, the eyepiece 1700 may deform into a curved shape exceeding its reference temperature. As the temperature of the eyepiece 1700 rises, each of the active layers 1710 may also expand based on their respective CTEs, but the overall shape of the active layers may be adjusted to conform to the shape determined by the CTEs of the cover layers 1722, 1724.

[0107] Figure 18 shows an eyepiece 1800 for a mixed reality device according to an embodiment of the present disclosure. The figure shows the eyepiece 1800 before assembly. A pre-assembled eyepiece 1800 may include one or more substantially flat glass cover layers 1820 flanking one or more substantially flat polymer active layers 1810. The eyepiece 1800 may further include a plurality of variable-height pillars 1866 positioned between the glass cover layers 1820 and adjacent polymer layers 1810. In some embodiments, a plurality of pillars of uniform height (not shown) may be positioned between adjacent polymer layers 1810, as described above with respect to the eyepiece 1500. The eyepiece 1800 may be configured to have a flat shape before assembly and a second different shape after assembly. In some embodiments, one or more active layers may be deformed during assembly.

[0108] Figure 19 shows an assembled eyepiece 1800 that may correspond to the assembled eyepiece 1900. As seen in the figure, the assembled eyepiece 1900 may include a flat region 1962 and a spherical region 1964. In some embodiments, the variable height pillar 1966 may be sized to engage with the glass cover layer 1920 such that, when the eyepiece is assembled, the assembled shape of the polymer active layer 1920 includes the flat portion 1962 and the spherical portion 1964. In other words, the process of assembling the eyepiece 1800 may deform a substantially flat polymer active layer to arrive at the eyepiece shape represented by the eyepiece 1900, which includes the flat portion and the spherical portion. The shape of the eyepiece 1900 may be exaggerated to show the flat portion and the spherical portion, i.e., the deflection of the spherical portion may not be actually significant, but those skilled in the art will understand that the eyepiece according to embodiments of the present disclosure may include a flat region and a spherical portion. In some embodiments, the configuration of the assembled eyepiece 1900 may be the same as that of eyepieces 1200, 1500, and 1600.

[0109] In this way, the assembled eyepiece 1900 may have advantages related to eyepieces 1500 and 1600, namely, one or more glass cover layers may help maintain the shape of the active layer 1910 as the eyepiece expands with increasing temperature. For example, because the CTE of the glass is relatively low, the glass cover layer may retain its shape even when the display heats up and / or maintain its shape consistently over the operating temperature of the head-mounted display. Furthermore, because the polymer layer 1910 is sandwiched between the relatively rigid glass cover layers 1920, deformation and separation of the polymer layer 1910 may be limited.

[0110] Furthermore, deforming the active layer 1910 during the assembly of the eyepiece 1900 to form a desired shape having, for example, a flat region 1962 and a spherical region 1964 can pre-tension the polymer active layer 1910. A pre-tensioned polymer active layer 1910 may be less likely to separate due to thermal expansion compared to, for example, a stack of unpre-tensioned polymer active layers, if the polymer active layer is molded to include a flat region 1962 and a spherical region 1964. Moreover, since a pre-assembled stack of the active layer 1810 is flat, the manufacturing process for the active layer 1810 can be simplified. For example, the active layer 1810 can be manufactured as a flat layer, and a variable height pillar can be relied upon to pre-tension the eyepiece into the desired shape during assembly. In comparison, the active layers 1510 and / or 1610 may be manufactured to include a flat region and a spherical region, which may add complexity to the manufacturing process.

[0111] Figure 20 shows a perspective view of an eyepiece 2000 according to an embodiment of the present disclosure. As shown in the figure, the eyepiece may include multiple layers, including one or more cover layers 2020 and one or more active layers 2010. The active layers 2010 and the cover layers 2020 may be configured to slide relative to each other. For example, as described above, an edge spacer 2009 may be positioned between each layer on the outer periphery of each layer of the eyepiece. In some embodiments, the edge spacer may be coupled to one of the eyepieces. Coupling the edge spacer to one of the adjacent eyepiece layers rather than both may allow the eyepiece layers to move and / or slide relative to each other. In contrast, as described above with respect to eyepiece 600, the edge spacer 609 may be coupled between both adjacent eyepiece layers to prevent relative sliding of the eyepiece layers relative to each other. For example, an edge spacer 2009a may be positioned between the lower cover layer 2020 and the active layer 2010. As shown in the figure, the edge spacer 2009a may be bonded to the lower cover layer 2020 so that the active layer 2010 can slide against the upper cover layer 2020.

[0112] Allowing the eyepiece layers to slide relative to each other can reduce the separation of the eyepiece layers caused by the bimetallic effect. In other words, because the eyepiece layers are made to slide relative to each other, they may not be subject to deformation associated with the bimetallic effect. Therefore, an eyepiece according to an embodiment of the disclosure including layers that are made to slide relative to each other can improve the performance of the eyepiece from, for example, a baseline design that does not consider thermal expansion effects.

[0113] In some embodiments, relative sliding of eyepiece layers may affect the optical alignment between layers. For example, relative sliding of eyepiece layers may cause misalignment between the light incident region and the light source and / or between the light incident region and the light exit region of the layers within the eyepiece. Some embodiments of the present disclosure may provide an eyepiece having sliding layers that can maintain an acceptable optical alignment between each of the layers during use. In one or more examples, the acceptable optical alignment can be predetermined based on specific design considerations related to the eyepiece. Furthermore, some embodiments of the present disclosure may be assembled as a unit and provide an eyepiece including sliding layers that can resist damage and out-of-plane deformation and / or movement when the head-mounted display experiences dynamic events, such as when it falls.

[0114] Figure 21 shows an eyepiece 2100 according to an embodiment of the present disclosure. As shown in the figure, the eyepiece 2100 may include one or more eyepiece layers 2110 mounted on a frame 2130. The frame 2130 may include one or more steps 2172a-c such that each step corresponds to an eyepiece layer 2110. In some embodiments, each of the eyepiece layers 2110 may be of a different size corresponding to the outer circumference of the frame in each of the steps 2172. For example, as seen in the figure, the upper step 2172a of the frame may have a larger outer circumference than the lower step 2172c of the frame. Thus, the upper eyepiece layer 2110 may be larger than the lower eyepiece layer 2110 to accommodate the larger outer circumference of the upper step 2172a.

[0115] One or more eyepiece layers 2110 may be configured to slide relative to one another, as described above with respect to the eyepiece 2000. For example, each eyepiece layer 2110 may be coupled to its respective step 2172 by a coupling 2137. The eyepiece layers 2110 do not have to be coupled to one another. Thus, the eyepiece layers 2110 may be made able to slide relative to one another as the eyepiece 2100 changes in temperature. In some embodiments, the coupling 2137 may be positioned along separate portions of the eyepiece layer 2110. In other words, the coupling 2137 does not have to be positioned around the entire circumference of the eyepiece layer 2110 and frame 2130. In some embodiments, the configuration of the coupling 2137 may correspond to the configurations of the couplings 831 and 833 described with respect to the eyepiece 800. That is, at least one set of couplings may be positioned near the light incident region of the eyepiece. The joint 2137 between the eyepiece layer 2110 and the frame 2130 can help the eyepiece maintain optical alignment when the layers 2110 slide against each other. Furthermore, because each eyepiece layer 2110 is coupled to the frame 2130, the eyepiece can resist damage if the head-mounted display is dropped or subjected to dynamic forces.

[0116] In some embodiments, the step 2172 may be manufactured to provide a consistent gap between each of the eyepiece layers 2110. The gap may be sized to allow each of the eyepiece layers 2110 to expand while maintaining a consistent gap 2107 between the layers. In some embodiments, a further number of spacers may be included to maintain the gap between the layers (e.g., spacers 609, 611).

[0117] Figure 22 shows an eyepiece 2200 according to an embodiment of the present disclosure. As seen in the figure, the eyepiece 2200 may include a plurality of eyepiece layers 2210 and have one or more rollers 2274 positioned between each of the plurality of eyepiece layers 2210. In some embodiments, the rollers 2274 may be positioned near the outer circumference of the eyepiece 2210. The rollers can facilitate relative sliding between the eyepiece layers 2210. The eyepiece layers 2210 may include an active layer and / or a cover layer.

[0118] In some embodiments, one or more of the eyepiece layers 2210 may be formed to include a slot 2276 configured to receive a roller 2274. The slot 2276 can prevent the roller 2274 from moving away from a desired position, such as near the outer edge of the eyepiece, which could adversely affect the performance and stability of the eyepiece 2210. In some embodiments, the slot 2276 may be molded as a feature of the eyepiece layer 2210. The ability to mold unique shapes is one of the advantages of polymer layers compared to glass layers. For example, a roller 2274a may be placed in a slot 2276a molded on the upper surface of the eyepiece layer 2210a. In this way, the roller 2274a can be confined to the slot 2276a while allowing relative sliding of the upper eyepiece layer 2210b over time. In addition to allowing sliding between layers, the roller 2274 can act as a spacer, helping to maintain a consistent spacing between the eyepiece layers 2210. The roller 2274 may be made from a variety of materials, such as glass beads. In some embodiments, the roller may be formed from a material having a relatively low CTE.

[0119] Figure 23 shows an optical system including an eyepiece 2300 and a frame 2330 according to an embodiment of the present disclosure. The eyepiece 2300 may be similar to the eyepiece 2200. That is, the eyepiece may include a plurality of eyepiece layers 2310, one or more of the eyepiece layers 2310 including a plurality of slots 2276. As shown in the figure, rollers 2374 may be positioned in the corresponding slots 2376 to facilitate relative sliding between the plurality of eyepiece layers 2310. Furthermore, the optical system may include a frame 2330 including a cap 2335. The cap 2335 may be provided to prevent out-of-plane deflection perpendicular to the surface of the eyepiece 2300. In this way, the optical system including the eyepiece 2300 and frame 2330 may be more robust by including the cap 2335 so that the optical system can withstand the daily loads on the head-mounted display resulting from daily use. The configuration of the cap 2335 may be similar to that of the lips 1035 and 1135. In some embodiments, the cap 2335 may include a layer of foam (not shown) similar to the layer of foam 1139 contained in the frame 1130.

[0120] Figure 24 shows an eyepiece 2400 according to an embodiment of the present disclosure. The eyepiece 2400 may include one or more edge spacers 2409a, 2409b which can be formed integrally with the corresponding eyepiece layer. In this way, an edge spacer, for example, edge spacer 2409a, is formed integrally with the corresponding eyepiece layer, for example, eyepiece layer 2410a, and can move together with the corresponding eyepiece layer. In some embodiments, a layer of lubricant or other material that reduces friction may be applied between the edge spacer 2409 and an adjacent unbonded and / or unintegrated eyepiece layer. For example, in some embodiments, a layer of lubricant may be applied between the edge spacer 2409a and an adjacent eyepiece layer 2410b. In this way, the lubricant can promote sliding between the eyepiece layers.

[0121] Figure 25 shows an eyepiece 2500 according to an embodiment of the present disclosure. As shown in the figure, the eyepiece 2500 may include one or more eyepiece layers 2510 and one or more edge spacers 2509a, 2509b positioned between each of the one or more eyepiece layers 2510. In some embodiments, the edge spacers 2509s, 2509a, 2509b may be formed separately from a different material than the eyepiece layers. The edge spacers 2509a, 2509b may be coupled to one of adjacent eyepiece layers. For example, as shown in the figure, the edge spacer 2509a may be coupled to an adjacent eyepiece layer 2510a. This may allow the edge spacers 2509a, 2510a to slide relative to the eyepiece layer 2510b. In some embodiments, the edge spacer material may be selected to have a low coefficient of friction in order to facilitate sliding between the edge spacer, for example, the edge spacer 2509a and the adjacent unbonded eyepiece layer, for example, the eyepiece layer 2510b.

[0122] In some embodiments, the eyepiece, for example, the eyepieces shown in Figures 15 to 25, may be assembled at or near the steady-state operating temperature of the head-mounted display. The embodiments described above are generally described under the assumption that the eyepiece is assembled and / or manufactured at a reference temperature corresponding to the temperature of the eyepiece when the head-mounted display is not in use. With the use of the head-mounted display, the temperature of the display and eyepiece may rise due to the heat generated by the electronic components. The head-mounted display and eyepiece may eventually reach a “steady state” operating temperature at which the head-mounted display no longer heats up. Assembling the eyepiece at room temperature may result in an eyepiece that provides peak performance and / or digital image quality at room temperature. When the head-mounted display and eyepiece heat up to the steady-state operating temperature, the image quality of the optical system may be adversely affected. Assembling the eyepiece at or near the steady-state operating temperature may provide optimal image quality and performance when the head-mounted display is at the steady-state operating temperature. This embodiment may result in improved optical performance of the head-mounted display as it heats up, so that the head-mounted display has peak performance at the steady-state temperature. As a result, the image quality at startup may be inferior to the image quality when the device is operating at a steady temperature.

[0123] Embodiments of the present disclosure provide systems and methods for displays. In some embodiments, the display system includes a frame, an eyepiece coupled to the frame, and a first adhesive joint positioned between the frame and the eyepiece. The eyepiece may include a light-incident region and a light-exit region. The first adhesive joint may be positioned along a first portion of the outer circumference of the eyepiece, the first portion of the outer circumference of the eyepiece being in contact with the light-incident region such that the first adhesive joint is configured to maintain the position of the light-incident region relative to the frame.

[0124] In some embodiments, the display may further include a second adhesive joint positioned between the frame and the eyepiece, the second adhesive joint positioned along a second portion of the outer circumference of the eyepiece, the second portion of the outer circumference of the eyepiece being in contact with the light-emitting region, and the second adhesive joint being configured to allow lateral expansion of the eyepiece relative to the frame. In some embodiments, the display may have a first adhesive joint associated with a first modulus, a second adhesive joint associated with a second modulus, the first modulus being greater than the second modulus. In some embodiments, the display further includes a third adhesive joint, the third adhesive joint being associated with a first modulus, and the first and third adhesive joints being positioned on either side of the light-incident region. In some embodiments, the length of the first adhesive joint may be less than half the length of the light-incident region. In some embodiments, the first adhesive joint may include an arc-shaped joint positioned close to the outer circumference of the light-incident region.

[0125] Embodiments of the present disclosure provide systems and methods for eyepieces for displays. In some embodiments, the eyepiece may include a first eyepiece layer, a second eyepiece layer positioned substantially parallel to the first eyepiece layer, and one or more edge spacers positioned between the first and second eyepiece layers. The one or more edge spacers may be configured to maintain a consistent gap between the first and second eyepiece layers and to allow relative sliding between the first and second eyepiece layers. In some embodiments, one or more edge spacers of the eyepiece may be coupled to the first eyepiece layer. In some embodiments, the eyepiece may further include a layer of lubricant positioned between the one or more edge spacers and the second eyepiece layer. In some embodiments, the lubricant is formed integrally with the first eyepiece layer.

[0126] In some embodiments, the first eyepiece layer may be made from a first material, and one or more edge spacers may be made from a second material different from the first material, the second material may have a lower coefficient of friction than the first material. In some embodiments, the first surface of the first eyepiece layer is provided with slots, and the corresponding edge spacers of one or more edge spacers are positioned within the slots. In some embodiments, the eyepiece may further include a plurality of pillar spacers positioned between the first eyepiece layer and the second eyepiece layer, the plurality of pillar spacers configured to maintain a consistent spacing between the first eyepiece layer and the second eyepiece layer.

[0127] Embodiments of the present disclosure provide systems and methods for displays. In some embodiments, the display may include a frame and an eyepiece coupled to the frame. The eyepiece may include a first eyepiece layer, a second eyepiece layer positioned substantially parallel to the first eyepiece layer, and one or more edge spacers positioned between the first and second eyepiece layers. The one or more edge spacers may be configured to maintain a consistent gap between the first and second eyepiece layers and to allow relative sliding between the first and second eyepiece layers. In some embodiments, the display of the display frame may include a cap positioned along the outer perimeter of the frame. In some embodiments, the frame includes a first step corresponding to the first outer perimeter and a second step corresponding to the second outer perimeter. The first eyepiece layer is positioned on the first step along the first outer perimeter, and the second eyepiece layer is positioned on the second step along the second outer perimeter. In some embodiments, one or more edge spacers may be formed integrally with the first eyepiece layer. In some embodiments, the display may further include a layer of lubricant disposed between one or more edge spacers and a second eyepiece layer. In some embodiments, the first surface of the first eyepiece layer may include slots, and the corresponding edge spacers of the one or more edge spacers may be placed within the slots.

[0128] Embodiments of the present disclosure provide systems and methods for displays. In some embodiments, the display may include a frame comprising a first step corresponding to a first outer perimeter and a second step corresponding to a second outer perimeter. The display may further include an eyepiece disposed within the frame. The eyepiece may include at least a first eyepiece layer and a second eyepiece layer disposed substantially parallel to the first eyepiece layer, wherein the first eyepiece layer may be arranged in a first step along the first outer perimeter, and the second eyepiece layer may be arranged in a second step along the second outer perimeter.

[0129] While the disclosed examples are adequately illustrated with reference to the accompanying drawings, it should be noted that various modifications and changes will be apparent to those skilled in the art. For example, elements and / or components shown in the drawings may not be to scale and / or may be exaggerated for illustrative purposes. As another example, elements of one or more implementations may be combined, deleted, modified, or supplemented to form further implementations. For example, in some embodiments, an eyepiece according to embodiments of the present disclosure may include an eyepiece combining the features of eyepieces 2100 and 2200, and the eyepiece may be mounted on a frame including multiple stages (e.g., eyepiece 2100 mounted on frame 2130). The eyepiece may further include multiple rollers (e.g., roller 2276) positioned between the multiple layers to maintain spacing between the eyepiece layers and to facilitate relative sliding of the eyepiece layers. In some embodiments, a cap, e.g., cap 2335, may be included along a portion of the frame to restrict the movement of the eyepiece layers in the out-of-plane direction. Other combinations and changes should be understood to fall within the scope of the disclosed examples as defined by the accompanying claims.

Claims

1. It is a display, Frame and, An eyepiece coupled to the frame, wherein the eyepiece is The region where light is incident, Light emission region and An eyepiece equipped with, A first adhesive bonding portion is positioned between the frame and the eyepiece. Equipped with, The frame comprises a first lip and a second lip separated from the first lip by a certain distance. The first adhesive bonding portion is positioned along a first portion of the outer circumference of the eyepiece, and the first portion of the outer circumference of the eyepiece is in contact with the light incident region such that the first adhesive bonding portion maintains the position of the light incident region relative to the frame. Each of the first lip and the second lip is in contact with the second portion of the outer circumference of the eyepiece. The eyepiece is configured such that the expansion of the second portion of the outer circumference of the eyepiece increases the distance separating the first lip from the second lip.

2. Each of the first lip and the second lip comprises a first lip portion and a second lip portion, The first lip portion is in contact with the second portion of the outer circumference of the eyepiece. The display according to claim 1, wherein the first lip portion is thicker than the second lip portion in the direction of the distance separating the first lip from the second lip.

3. The display according to claim 1 or 2, further comprising a second adhesive bonding portion disposed between the frame and the eyepiece, wherein the second adhesive bonding portion is disposed along a third portion of the outer circumference of the eyepiece, the third portion of the outer circumference of the eyepiece is in contact with the light emission region, and the second adhesive bonding portion is configured to allow in-plane expansion of the eyepiece relative to the frame.

4. The display according to claim 3, wherein the first adhesive bond is associated with a first elastic modulus, the second adhesive bond is associated with a second elastic modulus, and the first elastic modulus is greater than the second elastic modulus.

5. The display according to claim 1 or claim 2, further comprising a third adhesive joint disposed between the frame and the eyepiece, wherein the third adhesive joint is arranged along a third portion of the outer circumference of the eyepiece, the third adhesive joint is associated with a first modulus of elasticity, and the light incident region is located between the first portion of the outer circumference of the eyepiece and the third portion of the outer circumference of the eyepiece.

6. The display according to claim 5, wherein the length of the first adhesive bond is less than half the length of the light incident region.

7. The display according to claim 1 or claim 2, wherein the first adhesive bonding portion includes an arc-shaped bonding portion positioned in close proximity to the outer periphery of the light incident region.

8. It is an eyepiece, The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers are disposed between the first eyepiece layer and the second eyepiece layer, A layer of lubricant disposed between the one or more edge spacers and the second eyepiece layer. Equipped with, The one or more edge spacers are coupled to the first eyepiece layer, The one or more edge spacers are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer An eyepiece configured to perform the following actions.

9. An eyepiece, The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers disposed between the first eyepiece layer and the second eyepiece layer and Equipped with, The one or more edge spacers are formed integrally with the first eyepiece layer, The one or more edge spacers are coupled to the first eyepiece layer, The one or more edge spacers are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer An eyepiece configured to perform the following actions.

10. The first eyepiece layer is made from the first material, The one or more edge spacers are made from a second material different from the first material. The eyepiece according to claim 8, wherein the second material has a lower coefficient of friction than the first material.

11. An eyepiece, The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers disposed between the first eyepiece layer and the second eyepiece layer and Equipped with, The one or more edge spacers are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer It is configured to do the following: An eyepiece in which the first surface of the first eyepiece layer is provided with a slot, and the corresponding edge spacers of the one or more edge spacers are positioned within the slot.

12. An eyepiece, The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, A plurality of pillar spacers disposed between the first eyepiece layer and the second eyepiece layer, wherein the plurality of pillar spacers are configured to maintain a consistent distance between the first eyepiece layer and the second eyepiece layer, One or more edge spacers disposed between the first eyepiece layer and the second eyepiece layer and Equipped with, The one or more edge spacers are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer An eyepiece configured to perform the following actions.

13. It is a display, A frame comprising a cap arranged along the outer circumference of the frame, An eyepiece coupled to the frame, wherein the eyepiece is The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers disposed between the first eyepiece layer and the second eyepiece layer and It is equipped with an eyepiece and Equipped with, The one or more edge spacers are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer A display configured to perform the following actions.

14. A display, Frame and, An eyepiece coupled to the frame, wherein the eyepiece is The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers disposed between the first eyepiece layer and the second eyepiece layer and It is equipped with an eyepiece and Equipped with, The one or more edge spacers are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer It is configured to do the following: The aforementioned frame is A first stage corresponding to the first outer perimeter, The second stage corresponding to the second outer perimeter and Equipped with, A display in which the first eyepiece layer is arranged in the first step along the first outer circumference, and the second eyepiece layer is arranged in the second step along the second outer circumference.

15. A display, Frame and, An eyepiece coupled to the frame, wherein the eyepiece is The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers disposed between the first eyepiece layer and the second eyepiece layer and It is equipped with an eyepiece and Equipped with, The one or more edge spacers are formed integrally with the first eyepiece layer, The one or more edge spacers are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer A display configured to perform the following actions.

16. The display according to claim 15, further comprising a layer of lubricant disposed between the one or more edge spacers and the second eyepiece layer.

17. A display, Frame and, An eyepiece coupled to the frame, wherein the eyepiece is The first eyepiece layer, A second eyepiece layer is arranged substantially parallel to the first eyepiece layer, One or more edge spacers disposed between the first eyepiece layer and the second eyepiece layer and It is equipped with an eyepiece and Equipped with, The one or more edge spacers are Maintaining a consistent gap between the first eyepiece layer and the second eyepiece layer, To enable relative sliding between the first eyepiece layer and the second eyepiece layer It is configured to do the following: A display wherein the first surface of the first eyepiece layer is provided with a slot, and the corresponding edge spacers of the one or more edge spacers are positioned within the slot.

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