# Patent

## Title
Head-mounted display device with stress-resistant components

## Abstract

A head-mounted display (HMD) device has a chassis, a display assembly, and various sensors and electronics, where the display assembly, sensors and electronics are mounted to the chassis and enclosed within a sealed protective visor, and where the display assembly is mounted to the chassis only through a central location that is aligned with a center-point between the user's eyes, thereby decoupling the display assembly from most mechanical and thermal stresses.

## Background
This application claims the benefit of U.S. provisional patent application No. 62/105,676, filed on Jan. 20, 2015, which is incorporated herein by reference.


BACKGROUND
Augmented Reality (AR) HMD devices (“AR-HMD” devices) include transparent display elements that enable a user to see concurrently both the real world around them and AR content displayed by the device. An AR-HMD device may include sensitive components, such as light-emission elements, waveguides, and various types of sensors. These components may require very precise positioning and alignment within the device in order to function properly. Even minor mechanical or thermal stresses applied to these components can potentially affect the positioning or alignment of such components and thereby adversely affect functionality of the device. Additionally, these components may be vulnerable to damage due to being dropped or other impacts, normal handling, or environmental factors.
SUMMARY
Introduced here is an HMD device that has display and electronic assemblies that are resistant to mechanical and thermal stresses. More specifically, in certain embodiments the HMD device has a display assembly that is mounted to a chassis only through a central location that is aligned with a center-point between the user's eyes, thereby decoupling the display assembly from most mechanical and thermal stresses. In certain embodiments, the HMD device comprises a head fitting by which the device can be worn on the head of a user, a chassis coupled to the head fitting, and the display assembly, where the display assembly includes left and right display components and a central bridge disposed between the left and right display components. The left and right display components are arranged to project light to a left eye and a right eye of the user, respectively. In certain embodiments the display assembly is mounted to the chassis only through its central nose bridge region. This manner of mounting decouples most mechanical and thermal stresses from the display assembly.
The display assembly can comprise a waveguide carrier, including the central bridge and left and right transparent mounting surfaces that extend from opposite sides of the central bridge, where the left and right mounting surfaces each have one or more transparent waveguides mounted thereon, and where each of the waveguides is arranged to project light into the left eye or right eye of the user when the display device is in operation. Further, the display assembly can comprise a display engine that includes a plurality of light emission elements optically coupled to each of the waveguides. To reduce stresses applied to the display engine, the display engine can be physically coupled to the waveguide carrier only at the central bridge. Other aspects of the technology will be apparent from the accompanying figures and detailed description.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.



BRIEF DESCRIPTION OF THE DRAWINGS
One or more embodiments of the present disclosure are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements.
FIG. 1 shows an example of an environment in which an AR-HMD device can be used.
FIG. 2A is a perspective view of an example of an AR-HMD device.
FIG. 2B schematically illustrates the AR-HMD device of FIG. 2A.
FIG. 3 shows a front perspective view of the visor assembly according to an embodiment.
FIGS. 4A and 4B show right side and front views, respectively, of the front shield.
FIG. 5 shows a front perspective view of the visor, with the front shield removed.
FIG. 6 shows a rear perspective view of the visor.
FIG. 7 shows a rear perspective view of the visor without the rear shield.
FIGS. 8A and 8B show front and left side orthogonal views, respectively, of the front shield of the shield enclosure.
FIG. 9 shows a rear perspective view of the shield enclosure.
FIGS. 10A, 10B and 10C illustrate right side, front and rear orthogonal views, respectively, of the optics assembly.
FIG. 11A shows a front perspective view of the display engine.
FIG. 11B shows a front perspective view of how the display engine can be mounted in the final assembly.
FIGS. 12A, 12B, 12C and 12D show front, side, top and rear orthogonal views, respectively, of the display engine.
FIGS. 13A and 13B show right side and front orthogonal views of the display assembly.
FIGS. 14A, 14B and 14C show top, right side and front orthogonal views of the chassis.
FIG. 15 shows a front perspective view of the chassis, with a printed circuit board (PCB) mounted to it.
FIGS. 16A and 16B shows right side and front orthogonal views, respectively, of the optics assembly mounted to the chassis.
FIG. 17 shows a rear perspective view of the display assembly and sensor assembly coupled to each other.
FIGS. 18A through 18D, show front, rear side and bottom orthogonal views, respectively, of the combined display assembly and sensor assembly.
FIG. 19 shows the front view of the sensor assembly.
FIGS. 20A, 20B and 20C show, respectively, the right side, front and bottom orthogonal views of the sensor frame and anti-reflection shields.
FIG. 21 shows a front view of the combination of the display assembly and sensor assembly mounted to the chassis
FIG. 22 shows a right side view of the visor assembly.



DETAILED DESCRIPTION
In this description, references to “an embodiment”, “one embodiment” or the like, mean that the particular feature, function, structure or characteristic being described is included in at least one embodiment of the technique introduced here. Occurrences of such phrases in this specification do not necessarily all refer to the same embodiment. On the other hand, the embodiments referred to also are not necessarily mutually exclusive.
FIG. 1 schematically shows an example of an environment in which an AR-HMD device such as described herein can be used. In the illustrated example, the AR-HMD device 1 is configured to communicate data to and from an external processing device 2 through a connection 3, which can be a wired connection, a wireless connection, or a combination thereof. In other use cases, however, the AR-HMD device 1 may operate as a standalone device. The connection 3 can be configured to carry any kind of data, such as image data (e.g., still images and/or full-motion video, including 2D and 3D images), audio, multimedia, voice, and/or any other type(s) of data. The processing system 2 may be, for example, a game console, personal computer, tablet computer, smartphone, or other type of processing device. The connection 3 can be, for example, a universal serial bus (USB) connection, Wi-Fi connection, Bluetooth or Bluetooth Low Energy (BLE) connection, Ethernet connection, cable connection, DSL connection, cellular connection (e.g., 3G, LTE/4G or 5G), or the like, or a combination thereof. Additionally, the processing system 2 may communicate with one or more other processing systems via a network 4, which may be or include, for example, a local area network (LAN), a wide area network (WAN), an intranet, a metropolitan area network (MAN), the global Internet, or a combination thereof.
FIGS. 2A and 2B show a perspective views of an illustrative AR-HMD device 20 (hereinafter simply “HMD device” or “device” 20) that can incorporate the features being introduced here, according to one embodiment. Specifically, FIG. 2A shows a realistic view of the HMD device 20, while FIG. 2B shows a schematic view of the HMD device 20 including various ones of its components. The HMD device 20 can be an embodiment of AR-HMD device 1 in FIG. 1.
In certain embodiments, the display components, sensors and processing electronics of the HMD device 20 are mounted on a chassis 31, as described in detail below. The chassis 31 is part of a protective sealed visor assembly 22 that contains the sensors, electronics, and display components, including left and right AR displays 23. The AR displays 23 are designed to overlay images on the user's view of his real-world environment, e.g., by projecting light into the user's eyes. Left and right side arms 24 are structures that attach to the chassis 31 at the left and right open ends of the chassis 31, respectively, via a flexible or rigid fastening mechanisms (including one or more clamps, hinges, etc.). The HMD device 20 includes an adjustable headband (or other type of head fitting) 21, attached to the side arms 24, by which the AR-HMD device 20 can be worn on a user's head.
In certain embodiments, the visor assembly 22 encloses an ambient light sensor (ALS) 18, one or more microphones 25 to input speech from the user (e.g., for use in recognizing voice commands and providing audio effects); one or more visible-spectrum head-tracking tracking cameras 27 for use in capturing images of surrounding surfaces to allow tracking of the user's head position and orientation in real-world space; one or more infrared (IR) spectrum depth cameras 28 for use in determining distances to nearby surfaces (e.g., for use in surface reconstruction to model the user's environment); one or more IR illumination sources 29 for use with the depth camera(s) 28; one or more visible spectrum video cameras 30 for use in capturing standard video of what the user sees. Note that the term “visible” in the context of this description means visible to a typical human being. The visor assembly 22 may also enclose electronic circuitry (not shown in FIG. 2) to control at least some of the aforementioned elements and to perform associated data processing functions. The circuitry may include, for example, one or more processors and one or more memories. The HMD device 20 also includes one or more audio speakers 26 to output sound to the user. Note that in other embodiments the aforementioned components may be located in different locations on the AR-HMD device 20. Additionally, some embodiments may omit some of the aforementioned components and/or may include additional components not mentioned above.
The visor assembly 22 provides the user with relatively unobstructed and transparent vision of the user's surrounding real world environment, while also providing physical protection of the sensitive display components and sensors from damage due to handling, impact, and environmental factors. The visor assembly 22 is further illustrated in FIGS. 3 and 4. In certain embodiments the visor assembly 22 includes the chassis 31, various display elements, sensors and electronics, and a protective shield enclosure 37. The shield enclosure 37, which includes a rear shield 32 and a front shield 33, protects the sensitive display elements, sensors and electronics from damage or misalignment due to ordinary handling and impacts. The display elements are suspended within the visor assembly 22 such that in the event of a drop, the display elements and shield enclosure 37 do not collide when there is minor deflection of the shield enclosure 37. The visor assembly 22 protects the sensitive optics, sensors and electronics during cleaning and wearing of the HMD device 20. It prevents the user's face, eyes, nose, etc., from touching the optics assembly by encapsulating them with durable transparent material molded into an ergonomically correct form. The shield enclosure 37 can include an add-on or molded-in nose pad. It can also incorporate some degree of optical diopter curvature (prescription) from, for example, the molding process. The shield enclosure 37 can incorporate tinted, mirrored, anti-reflective and/or other coatings, colors and/or finishes. The shield enclosure 37 can include features such as snaps, bosses, screws, and other types of fasteners, to attach it to a chassis. The shield enclosure 37 can be made of a single part or multiple parts, including clear parts, opaque parts, or a combination thereof.
In certain embodiments, the shield enclosure 37 can be a molded transparent component that is attached to the chassis 31 of the HMD device 20 to provide protection for the optics assembly from the environment and the user. In this disclosure, the term “rear” generally refers to a part or surface that is closest to the user (wearer) of the HMD, while the term “front” generally refers to a corresponding part or surface that is farthest from the user. The optics and sensors are mounted to the chassis 31 (as described further below) and suspended within the shield enclosure so that the sensitive (display) surfaces of the optics do not touch the shields or any other part.
The shield enclosure 37 can incorporate at least a portion (e.g., one half) of an amount of optical correction provided by the HMD, where the remainder of the optical correction can be incorporated into the display assembly (e.g., AR displays 23). The optical correction used to focus holographic images about 2 meters in front of the user's eyes, for visual comfort. In certain embodiments, this optical correction can be built partially into the rear shield as a negative curvature and partially into the front surface of the optics assembly as a positive curvature. Distributing the optical correction between two or more parts in this manner helps to reduce the thickness and weight of the optics assembly.
The visor assembly 22 is now further described in reference to FIGS. 3 through 9. FIG. 3 shows a front perspective view and FIG. 9 shows a rear perspective view of the visor assembly 22, according to an embodiment. In the illustrated embodiment, the shield enclosure 37 includes the rear shield 32, front shield 33, and shield cover 34 (the shield cover 34 is shown detached in FIG. 3, which is a partial exploded view). The front shield 33 and rear shield 32 are at least partially transparent to visible light. In some embodiments, a tinted coating is applied to at least the front shield 33, along with a protective coating. The back of the shield cover 34 may contain small protrusions, or “teeth,” that fit into corresponding grooves at the top of the front shield 33, to allow the shield cover to lock into place.
Note that in some embodiments, side strips 34B of the shield cover 34 (located on either side of the center strip 34A) may be or may contain antennas usable by the HMD for wireless communication, such as for WiFi and/or Bluetooth based communication.
FIGS. 4A and 4B show right side and front views, respectively, of the front shield 33. FIG. 5 shows a front perspective view, with the front shield removed, illustrating how the optics assembly 35 can be mounted to a chassis 31 and suspended within the shield enclosure. The chassis 31 can be attached, directly or indirectly, to the headband side arms 24 other similar structure(s) (FIG. 2). The side arms 24 or other similar structure can be inserted into the left and right open ends of the chassis 31 and attached to a surface of the chassis 31 (e.g., via screws, clamps and/or other types of fasteners), as discussed further below.
As shown in FIG. 5, the chassis 31 is positioned above and in contact with the rear shield 32 and front shield 33 of the shield enclosure 37. The chassis 31 serves as a mounting base to which the optics assembly 35, light-emission elements (not shown in FIG. 5) and certain sensors (not shown in FIG. 5) are mounted. The optics assembly 35 includes multiple optical waveguides mounted on a transparent optical waveguide carrier, as described further below. The optics assembly 35 can be attached to the chassis 31 by one or more screws (or other types of fasteners) through a center tab 51 located over the nose bridge region of the optics assembly 35. In the illustrated embodiment, the optics assembly 35 is mounted to the chassis 31 only through its central nose bridge region, which decouples most mechanical and thermal stresses from the optics assembly and thereby helps prevent damage or performance degradation due to deflection and warping of the optics.
FIG. 6 shows a rear perspective view of the visor assembly 22, providing an additional view of the rear shield 32 and rear surface of the chassis 31. The shield enclosure 37 includes a nose pad 36, which may be initially formed as a separate piece and then bonded to the shield enclosure 37, or which may be formed as an integral part of the rear shield 32 and/or front shield 33. As mentioned above, the front or rear surface of the rear shield 32 may provide at least a portion of the overall optical correction used to focus holographic images about 2 meters in front of user. FIG. 7 shows a rear perspective view of the visor without the rear shield.
In certain embodiments, at least the exterior surfaces of the rear shield 32 and front shield 33 of the shield enclosure 37 are coated with one or more layers of coating to provide, for example, tint, anti-reflectiveness, oleophobicity, scratch resistance, etc. In certain embodiments, the upper portion 91 of the exterior front shield 33 is uniformly coated with a tinting that is substantially opaque to visible light but transparent to IR light. FIGS. 8A and 8B show, respectively, front and left side orthogonal views of the front shield 33 of the shield enclosure 37, illustrating an example of the tinting scheme. The opaque tinting on the upper portion 91 hides most of the sensor assembly from view, to improve the visual aesthetics of the HMD 20, while still allowing the IR depth camera 28 and IR illumination sources 29 to serve their intended purpose. However, the upper portion 91 of the front shield 22 also has small regions (“windows”) 93 and 94 that are devoid of tinting, or that have substantially less tinting, so as to transmit visible light, located over the visible spectrum head-tracking cameras 27 and visible-spectrum video camera 30 (not shown in FIG. 8). In the final assembly of the HMD 20, Windows 93 are located over the head tracking cameras 27, and window 94 is located over the ALS 18 and visible-spectrum video camera 30. The lower portion 95 is preferably tinted but still transparent to visible light. Note that the term “transparent” in this context should be understood to encompass any of various degrees of transparency and does not imply 100% transparency, unless so stated. The tinting on the lower portion 95 may be uniform, or it may have a variable (e.g., graded along a vertical axis) tinting. In some embodiments, the tinting on the lower portion 95 varies from about 90% opaque to visible light at the border of the upper portion to about 10% opaque to visible light at the bottom of the front shield 33.
FIG. 9 shows a rear perspective view of the shield enclosure 37. The interior surfaces of the shield enclosure 37 define a protective space within which the optics assembly 35 and sensors can be suspended from the chassis 31 (not shown). In the final assembly of the HMD device 20, in which the shield enclosure 37 is attached to the chassis 31 (with the optics assembly and sensors mounted to the chassis 31), the display elements and sensors are contained within a completely sealed enclosure defined by the chassis 31 and the shield enclosure 37. The shield enclosure 37 can be attached to the chassis 31 using any known or convenient bonding method, such as gluing, laser welding, ultrasonic welding, etc.
The shield enclosure 37 (including the front shield 33 and rear shield 32) can be formed of, for example, optical-grade polycarbonate. In at least some embodiments, the front shield 33 and rear shield 32 have thicknesses in the range of approximately 0.8 to 1.2 millimeters. The shield enclosure 37 can be formed as a single part (e.g., by thermal molding), or the front shield 33 and rear shield 32 can be formed as separate pieces (e.g., by thermal molding) that are subsequently bonded together to form the shield enclosure 37. Such bonding (if any) can be, for example, gluing, laser welding, ultrasonic welding, or any other known or convenient bonding technique.
FIGS. 10A, 10B and 10C illustrates right side, front and rear orthogonal views, respectively, of the optics assembly 35. As mentioned, the optics assembly 35 includes the waveguide carrier 101 and multiple waveguides 102. The waveguide carrier 101 is a mounting structure for the waveguides 102 and the display engine 103 (see FIGS. 11 through 13). The waveguides 102 mount onto two flat mounting surfaces 121 of the waveguide carrier 101 (one for the user's left eye and one for the user's right eye) that extend from either side of a central nose bridge section 110 of the carrier 101. In some embodiments, as shown, on each of the left and right mounting surfaces 120, three waveguides 102 are stacked on top of each other, i.e., one waveguide for each of the red, green and blue components of an RGB display, for each eye. Note, however, that other color formats and corresponding waveguide configurations may be used.
As mentioned above, even minor mechanical or thermal stresses applied to the display-related components of the HMD 20 may affect the positioning or alignment of such components and thereby adversely affect functionality of the device. For example a slight misalignment of the left or light light-emission elements or waveguides can cause holographic images to become distorted, adversely affecting their degree of realism and potentially causing physical discomfort to the user. Additionally, misalignment of sensors such as the head-tracking cameras 27 may cause the HMD device 20 to incorrectly compute the user's head position or orientation relative to the user's environment, thereby adversely affecting the quality or realism of the images or sounds presented to the user.
Therefore, in certain embodiments, the display assembly of the HMD device 20 is mounted to the chassis 31 only through a central location that is aligned approximately with a center-point between the user's eyes, with no other points of physical contact, thereby decoupling the display assembly from most mechanical and thermal stresses.
Referring again to FIGS. 10A, 10B and 10C and FIG. 13, the display assembly 130 includes the optics assembly 35 (which includes a waveguide carrier 101 and multiple waveguides 102) and a display engine 103 (see FIGS. 11 through 13). The display engine 103 contains one or more light-emission elements (not shown) for each of the left-eye and right-eye displays. In some embodiments, the light-emission elements are light-emitting diodes (LEDs). During fabrication of the HMD device 20, the display engine 103 is first mounted to the optics assembly 35, by screws or other suitable fasteners, through the center tab 51 of the waveguide carrier 101 (located over the nose bridge region of the optics assembly 35). When so mounted, light emitted by the light-emission elements within the display engine 103 is optically coupled to the waveguides 102, which convey the emitted light toward the user's eyes. Subsequently, the optics assembly 35, with display engine 103 mounted thereto (see FIGS. 13A and 13B), is mounted to the chassis 31, by screws or other suitable fasteners, through the nose bridge region 110 of the waveguide carrier 101. A sensor assembly 111, including the head-tracking cameras 27, IR depth camera 28 and visible-spectrum camera 30, is then mounted to the carrier 31 and display assembly 130.
The optics assembly 35 can be attached to the chassis 31 by one or more screws (or other types of fasteners) through holes 123 in the center tab 51. Alignment holes 124 are used to properly align the waveguide carrier 101 onto the chassis 31 during assembly, prior to fastening of the screws. The display engine 103 (not shown in FIG. 12) mounts to the waveguide carrier 101 by screws (or other suitable fastening mechanism) through corresponding screw holes 126 in the central nose bridge region 110 of the carrier 101 and holes 156 in the display engine 103, as shown in FIGS. 15A and 15B. Left and right optical ports 125 on the waveguide carrier 101 are physically and optically coupled to corresponding optical ports 155 on the display engine 103. The entire display assembly 130 (i.e., optics assembly 35 and display engine 103 mounted to it) is then mounted to the chassis 31 via screws (or other suitable fastening mechanism) through holes 123 in the center tab 51. Notably, this is the only mechanical interface between the entire display assembly 130 and the rest of the HMD 20; the display assembly 130 is coupled to the chassis 31 and suspended within the visor assembly 22 only from this single mounting location on the center tab 51. Similarly, the display engine 103 is mounted to the waveguide carrier 101 only at the central nose bridge region 110 of the waveguide carrier 101.
FIGS. 11 and 12 illustrate the display engine 103 in greater detail. More specifically, FIG. 11 shows a rear perspective view of the display engine 103, while FIGS. 12A, 12B, 12C and 12D show, respectively, front, side, top and rear orthogonal views of the display engine 103. The display engine 103 combines two or more light projectors in one small envelope. The display engine 103 is laterally symmetrical, having identical left and emitter housings 144. The left and right emitter housings 144 each contain one or more light-emission elements (not shown), such as pico projector LEDs. A PCB 141 is mounted on the outside of the display engine 103 and includes one or more motion sensors, such as one or more accelerometers and gyroscopes. Flex circuit 146 on top of the display engine 103 (FIG. 12C) connects the light emission elements (not shown) to a display processor elsewhere in the HMD 20 (e.g., on a PCB mounted to the chassis 31).
To mount the display engine 103 to the waveguide carrier 101, screws (or other suitable mounting mechanism) can be passed through the rear side of the waveguide carrier 101 into corresponding holes 156 in the display engine 103. Left and right optical ports 155 of the display unit 103 physically and optically couple to corresponding optical ports 125 of the waveguide carrier 101. The left and right sides of the display assembly 130 may be very sensitive to distortion due to any physical or thermal stresses. However, the center-mount design of the display engine's interface to the waveguide carrier 101 decouples any external forces from the display engine body, thus keeping left to right alignment intact even if the device is under stress.
The light-emission elements in display engine 103 may generate a significant amount of heat. Accordingly, in some embodiments, as shown in FIG. 11A, the display engine 103 includes a thermal plate 132, which facilitates transfer of heat away from the display engine 103. Specifically, in the final assembly of the HMD 20, as shown in FIG. 11B, the left end and/or right end of thermal plate 132 may lie against one of two other thermal plates 136 that are mounted to the chassis 31 (one on each side of thermal plate 132) and that form part of an overall heat transfer system designed to convey heat away from the display engine 103 and the electronics. A thin layer of compliant thermally conductive material may be sandwiched between plate 132 and one or both of plates 136. This approach helps to reduce thermal stress on the display engine 103 and optics assembly 35.
The chassis 31 is the structural component by which all of the display elements, optics, sensors and electronics are coupled to the rest of the HMD device 20. FIGS. 14A, 14B and 14C show, respectively, top, front and right-side views of the chassis 31, while FIG. 15 shows a perspective view of the chassis 31. The chassis can be formed of molded plastic or polymer, for example. The front surface 160 of the chassis 31 may include various fixtures (e.g., screw holes, raised flat surfaces, etc.) to which the sensor assembly (not shown) can be attached. For example, the chassis 31 has screw holes (or other similar mounting fixtures) 161 by which the optics assembly 35 can be attached to the chassis 31. The chassis 31 further has one or more fixtures by which at least one printed circuit board (PCB) 172 bearing the electronics components of the HMD 20 can be mounted, as shown in FIG. 15. An example of such a PCB is illustrated in FIG. 15, which shows a front perspective view of the chassis 31 with a PCB 172 mounted to a top inner surface 176 of the chassis 31 (see FIGS. 14A, 14B and 14C).
FIGS. 16A and 16B further illustrate how the optics assembly 35 (including waveguide carrier 101 and waveguide 102) can mount to the chassis 31. Specifically, FIG. 16B shows the front view while FIG. 16A shows the right side view of these components. Note, however, that during assembly of the HMD device 20, according to at least some embodiments the waveguide carrier 101 is mounted to the chassis 31 only after the display engine 103 has been mounted to the waveguide carrier 101; however, the display engine 103 is not shown in FIGS. 16A and 16B to facilitate illustration a how the waveguide carrier 101 is mounted to the chassis 31.
Referring now to FIG. 17, the HMD device 20 also includes a sensor assembly 111, which includes a sensor frame 210, and various sensors (e.g., head-tracking cameras 27, IR depth camera 28, visible-spectrum camera 30, and ambient light sensor (ALS) 18) and IR light sources 29, some or all of which may be mounted to the sensor frame 210. FIG. 17 shows a rear perspective view of the display assembly 130 (including optics assembly 35 and display engine 103) and sensor assembly 111, coupled to each other. The sensor frame 210 is preferably made of a material that is lightweight, structurally stable and strong, which in some embodiments may be metal. The sensor frame 210 may be formed of a single part, or multiple pieces connected to each other. The sensor frame 210 attaches to the top inner surface 176 of the chassis 31 (see FIGS. 14A, 14B and 14C) via two mounting points 184 on the sensor frame 210, for example, by screws or other fastening mechanism. Hence, the combined sensor assembly 111 and display assembly 130 mount to the chassis 31 through only three points: the center tab 51 of the waveguide carrier 101 and the two mounting points 184 on the sensor frame. FIGS. 18A through 18D, show front, rear side and bottom orthogonal views, respectively, of the combined display assembly and sensor assembly. FIG. 19 shows the front view of the sensor assembly 111, i.e., the sensor frame 210 with the various sensors mounted to it. FIGS. 20A, 20B and 20C show, respectively, the right side, front and bottom orthogonal views of the sensor frame 210 and anti-reflection shields 192, i.e., without the sensors.
FIG. 21 shows a front view of the combination of the display assembly 130 and sensor assembly 111 mounted to the chassis 31. FIG. 22 shows a right side view of the visor assembly 22, in which the integrated display and sensor assemblies are mounted to the chassis 31 and suspended within the shield enclosure 37. The display assembly 130 is suspended from the chassis 31 so that the waveguides 102 and waveguide carrier 101 do not touch the shield enclosure 37 or any other component. Note that the rear shield 32 of the shield enclosure 37 is curved (as is the front shield 33), such that there may actually be more clearance between the waveguides 102 and the inner surface of the rear shield 32 than appears in FIG. 25.
Any or all of the features and functions described above can be combined with each other, except to the extent it may be otherwise stated above or to the extent that any such embodiments may be incompatible by virtue of their function or structure, as will be apparent to persons of ordinary skill in the art. Unless contrary to physical possibility, it is envisioned that (i) the methods/steps described herein may be performed in any sequence and/or in any combination, and that (ii) the components of respective embodiments may be combined in any manner.
EXAMPLES OF CERTAIN EMBODIMENTS
Certain embodiments of the technology introduced herein are summarized in the following numbered examples:
1. A display device comprising: a head fitting by which the display device can be worn on the head of a user; a chassis coupled to the head fitting; and a display assembly including left and right display components and a central bridge disposed between the left and right display components, the left and right display components arranged to project light to a left eye and a right eye, respectively, of the user, the display assembly being mounted to the chassis only through the central bridge.
2. A display device according to example 1, wherein the display assembly comprises: a waveguide carrier including the central bridge and left and right mounting surfaces extending from opposite sides of the central bridge, the left and right mounting surfaces each having one or more waveguides mounted thereon, each of the waveguides arranged to project light into the left eye or right eye of the user when the display device is in operation.
3. A display device according to example 2, wherein the mounting surfaces and the waveguides are transparent.
4. A display device according to example 2 or 3, wherein the display assembly further comprises: a display engine including a plurality of light emission elements, the display engine being physically coupled to the waveguide carrier only at the central bridge and optically coupled to each of the waveguides.
5. A display device according to any of examples 2 through 4, wherein each of the one or more waveguides is substantially planar.
6. A sub-assembly for use in a head-mounted display device, the sub-assembly comprising: a chassis configured to be coupled to a head fitting to be worn on the head of a user of the head-mounted display device; and an optics assembly including a waveguide carrier and a plurality of waveguides mounted on the waveguide carrier, the waveguide carrier including a central bridge and transparent left and right mounting surfaces extending from opposite sides of the central bridge, the left and right mounting surfaces each having one or more of the waveguides mounted thereon, each of the waveguides arranged to project light into a left eye or right eye of the user when the head-mounted display device is in operation, the optics assembly being coupled to and physically contacting the chassis only through the central bridge.
7. A sub-assembly according to example 6, further comprising: a display engine including a plurality of light emission elements, the display engine being optically coupled to each of the waveguides and being mounted to the chassis only through the waveguide carrier.
8. A sub-assembly according to example 6 or 7, wherein each of the one or more waveguides is substantially planar.
9. A sub-assembly according to any of examples 6 through 8, wherein the mounting surfaces and the waveguides are transparent to visible light.
10. A display device comprising: a head fitting by which the display device can be worn on the head of a user; a chassis coupled to the head fitting; a waveguide carrier including a central bridge and substantially flat left and right mounting surfaces extending from opposite sides of the central bridge, the left and right mounting surfaces each having one or more waveguides mounted thereon, each of the waveguides arranged to project light into a left eye or right eye of the user when the display device is in operation, the waveguide carrier being coupled to and physically contacting the chassis only through the central bridge; and a display engine including a plurality of light emission elements, the display engine being physically coupled to the waveguide carrier only at the central bridge and optically coupled to each of the waveguides.
11. A display device according to example 10, further comprising: a sensor frame coupled to the chassis; a plurality of sensors mounted to the sensor frame; and a strut bar having a first end coupled to the waveguide carrier at the central bridge and a second end coupled to the sensor frame.
12. A display device according to example 10 or 11, wherein the chassis has a substantially C-shaped cross-section, and the waveguide carrier is mounted to a first inner surface of the chassis.
13. A display device according to example 12, wherein the strut bar is mounted to a second inner surface of the chassis.
14. A display device according to any of examples 10 through 13, further comprising: a printed circuit board mounted to the chassis; an integrated circuit mounted on the printed circuit board; and a flexible electrical connector electrically coupling the integrated circuit to the display engine.
15. A display device according to any of examples 10 through 14, the central bridge having a tab at which the waveguide carrier is coupled to the chassis.
16. A display device according to any of examples 10 through 15, wherein the mounting surfaces and the waveguides are transparent.
Any or all of the features and functions described above can be combined with each other, except to the extent it may be otherwise stated above or to the extent that any such embodiments may be incompatible by virtue of their function or structure, as will be apparent to persons of ordinary skill in the art. Unless contrary to physical possibility, it is envisioned that (i) the methods/steps described herein may be performed in any sequence and/or in any combination, and that (ii) the components of respective embodiments may be combined in any manner.
Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

## Claims

1. A sub-assembly for use in a head-mounted display device, the sub-assembly comprising:
a chassis configured to be coupled to a head fitting to be worn on the head of a user of the head-mounted display device; and
an optics assembly including a waveguide carrier and a plurality of substantially flat, substantially transparent waveguides mounted on the waveguide carrier, the waveguide carrier including a central bridge and substantially flat, substantially transparent left and right mounting surfaces extending from opposite sides of the central bridge, the left and right mounting surfaces each having one or more of the waveguides mounted thereon, each of the waveguides arranged to project light to a left eye or right eye of the user when the head-mounted display device is in operation, the optics assembly being coupled to and physically contacting the chassis only through the central bridge.

2. A sub-assembly according to claim 1, further comprising:
a display engine including a plurality of light emission elements, the display engine being optically coupled to each of the waveguides and being mounted to the chassis only through the waveguide carrier.

3. A sub-assembly according to claim 1, wherein the chassis has a substantially C-shaped cross-section, and the waveguide carrier is mounted to an inner surface of the chassis.

4. A sub-assembly according to claim 1, further comprising:
a sensor frame coupled to the chassis;
a plurality of sensors mounted to the sensor frame; and
a strut bar having a first end coupled to the waveguide carrier at the central bridge and a second end coupled to the sensor frame.

5. A sub-assembly according to claim 4, wherein the chassis has a substantially C-shaped cross-section, and the waveguide carrier is mounted to a first inner surface of the chassis.

6. A sub-assembly according to claim 5, wherein the strut bar is mounted to a second inner surface of the chassis.

7. A sub-assembly according to claim 1 further comprising:
a printed circuit board mounted to the chassis;
an integrated circuit mounted on the printed circuit board; and
a flexible electrical connector electrically coupling the integrated circuit to the display engine.

8. A sub-assembly according to claim 1, the central bridge region having a tab at which the waveguide carrier is coupled to the chassis.

9. A display device comprising:
a head fitting by which the display device can be worn on the head of a user;
a chassis coupled to the head fitting;
a waveguide carrier including a central bridge and substantially flat, substantially transparent left and right mounting surfaces extending from opposite sides of the central bridge, the left and right mounting surfaces each having one or more substantially flat, substantially transparent waveguides mounted thereon, each of the waveguides arranged to project light to a left eye or right eye of the user when the display device is in operation, the waveguide carrier being coupled to and physically contacting the chassis only through the central bridge; and
a display engine including a plurality of light emission elements, the display engine being physically coupled to the waveguide carrier only at the central bridge and optically coupled to each of the waveguides.

10. A display device according to claim 9, further comprising:
a sensor frame coupled to the chassis;
a plurality of sensors mounted to the sensor frame; and
a strut bar having a first end coupled to the waveguide carrier at the central bridge and a second end coupled to the sensor frame.

11. A display device according to claim 10, wherein the chassis has a substantially C-shaped cross-section, and the waveguide carrier is mounted to a first inner surface of the chassis.

12. A display device according to claim 11, wherein the strut bar is mounted to a second inner surface of the chassis.

13. A display device according to claim 9, further comprising:
a printed circuit board mounted to the chassis;
an integrated circuit mounted on the printed circuit board; and
a flexible electrical connector electrically coupling the integrated circuit to the display engine.

14. A display device according to claim 9, the central bridge region having a tab at which the waveguide carrier is coupled to the chassis.