A head-mounted display adjustable to accommodate different head and face sizes

Abstract

To provide a head-mounted display (HMD) that allows for customizing the HMD to different users.SOLUTION: An HMD includes an interpupillary distance (IPD) adjustment mechanism that includes a double biasing assembly for smooth, controlled adjustment of the spacing between lens tubes. The HMD may include a field of view (FOV) adjustment mechanism that includes first and second gear assemblies connected via a connecting rod to allow uniform adjustment of the spacing between the lenses and the user's face. The HMD may further include a swappable face gasket, a swappable visor, a removable head strap, and a modular accessory compartment for further customizations to the HMD. The HMD may further include inconspicuous spectrum-transmissive windows that are made with a spectrum-transmissive base material for the HMD housing that is coated with a spectrum-opaque material, the spectrum-opaque material being selectively removed.SELECTED DRAWING: Figure 5A

Description

Cross - Reference to Related Applications

[0001] This is a PCT application claiming priority to U.S. Patent Application No. 16 / 850,426, filed on April 16, 2020, which claims priority to U.S. Provisional Patent Application No. 62 / 837,662, filed on April 23, 2019. Applications No. 16 / 850,426 and 62 / 837,662 are hereby incorporated by reference in their entirety.

Technical Field

[0002] [Background Art] Head - mounted displays are used in various fields, including engineering, medicine, military, and video games. In some cases, a head - mounted display can present information or images to a user as part of a virtual reality or augmented reality environment. For example, while playing a video game, a user can wear a head - mounted display to immerse the user within a virtual environment.

[0003] Conventional head - mounted displays are insufficiently adjustable or not adjustable at all to accommodate different head sizes, face shapes, and inter - eye distances. As a result, some users may find it difficult to wear a head - mounted display comfortably. For example, if the lens barrel is horizontally misaligned with the user's eyes, the scene presented on the head - mounted display may be only partially visible to the user. If the display panel is too close to or too far from the user's eyes, the user's field of view (FOV) may not be optimized. Thus, conventional head - mounted displays may not be able to adapt to different users. Adjustable head - mounted displays tend to be difficult and / or inconvenient to adjust with crude adjustment mechanisms, do not provide an optimized level of comfort, and frustrate the user.

Brief Description of the Drawings

[0004] A detailed description will be given with reference to the accompanying drawings. In the drawings, the leftmost digit of a reference number identifies the figure in which the reference number first appears. The same or similar reference numbers in different figures indicate the same or identical items.

[0005]

Figure 1

[0006]

Figure 2

[0007]

Figure 3A

[0008]

Figure 3B

[0009]

Figure 4

[0010]

Figure 5A

[0011]

Figure 5B

[0012]

Figure 6A

[0013]

Figure 6B

[0014]

Figure 7A

[0015]

Figure 7B

[0016]

Figure 8

[0017]

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0018] As described above, head-mounted displays (HMDs) have a wide range of applications and, in some cases, may need to accommodate various head sizes, face shapes, and interpupillary distances (IPDs) among different users. However, conventional HMDs provide little or no adjustment for fitting different users. For example, in conventional HMDs, the distance between lens barrels may be fixed, or if adjustable, the adjustment mechanism may be difficult or inconvenient to operate, particularly while wearing the HMD. In conventional HMDs, the distance between the user's face and the display panel (or lens) may also be fixed, or if adjustable, the adjustment mechanism may be difficult or cumbersome to operate while wearing the HMD.

[0019] In this specification, among other things, techniques and systems including an HMD for adjusting the spacing between a pair of lens barrels of the HMD are described, particularly for accommodating users with various interpupillary distances (IPDs). For example, the HMD may include a rod coupled to an intermediate frame of the HMD, and a pair of lens barrels coupled to the rod (e.g., via a pair of movable frames coupled to the pair of lens barrels), where each lens barrel / movable frame is movable bidirectionally along the rod (e.g., in a first direction toward the left side of the HMD or in a second direction toward the right side of the HMD). The HMD may also include an actuator accessible from outside the housing of the HMD, and a movable elongate member coupled to the actuator and the intermediate frame. A first biasing member coupled to the movable elongate member and the intermediate frame is configured to resist movement of the movable elongate member in the direction of travel of the elongate member. A rotatable gear coupled to the intermediate frame and disposed between the pair of lens barrels / movable frames engages the movable elongate member, and a pair of second biasing members coupled to the rod are configured to physically bias the pair of lens barrels / movable frames toward the rotatable gear (e.g., by physically biasing the pair of movable frames against a pair of helical protrusions extending from the face of the rotatable gear).

[0020] Also, in this specification, among other things, techniques and systems including a head-mounted display (HMD) are described for adjusting the distance between a user's face and the lens of the HMD to adjust the field of view (FOV) and / or eye relief in order to adapt to different users. For example, the HMD may comprise a pair of lens assemblies coupled to a first portion of the HMD. An actuator disposed on a first side of the HMD may be accessible from outside the housing of the HMD, and a pair of gear assemblies disposed on the opposite side of the HMD may be connected by a connecting rod and coupled to a second portion of the HMD that is movable relative to the first portion of the HMD. One of the gear assemblies of the pair of gear assemblies is disposed on the first side and coupled to the actuator, such that actuation of the actuator causes the pair of gear assemblies to move the second portion of the HMD relative to the first portion of the HMD.

[0021] Also, in this specification, among other things, an electronic device (e.g., an HMD) having a housing made of a spectrally transmissive material configured to allow electromagnetic radiation of a specific spectrum to pass through is described. The outer surface of the housing may be coated with a spectrally non-transmissive material configured to block electromagnetic radiation of a specific spectrum, and one or more locations on the outer surface are lacking the spectrally non-transmissive material so as to provide one or more spectrally transmissive windows on the housing. One or more spectrum-specific components (e.g., sensors, beacons, etc.) can be disposed inside the housing behind the one or more spectrally transmissive windows.

[0022] A process for manufacturing an electronic device (e.g., an HMD) having at least one window that permits electromagnetic radiation of a specific spectrum to pass therethrough may include forming a housing for the electronic device from a first material configured to permit electromagnetic radiation of a specific spectrum to pass therethrough, coating an outer surface of the housing with a second material configured to block electromagnetic radiation of a specific spectrum, and removing the second material from at least one location on the outer surface to create at least one window. In some embodiments, the specific spectrum is the IR spectrum.

[0023] This disclosure provides an overall understanding of the structures, functions, manufacture, and principles of use of the systems and methods disclosed herein. One or more embodiments of the disclosure are described in the accompanying drawings. Those skilled in the art will understand that the systems and methods described specifically herein and illustrated in the accompanying drawings are non-limiting embodiments. Features described or depicted in connection with one embodiment, including those between a system and a method, can be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of the appended claims.

[0024] FIG. 1 illustrates a front perspective view of an exemplary head-mounted display (HMD) 100 (also referred to herein as a “wearable display,” “VR headset,” “AR headset,” or “headset”), with the visor 106 removed from the HMD 100 to reveal the modular accessory compartment 102. The HMD 100 may include a front portion (or main unit) positioned in front of or above the user's eyes to render images output by an application (e.g., a video game). In some cases, the application may be executed on a computing device (e.g., a personal computer (PC), a game console, etc.) associated with and / or communicatively coupled to the HMD 100. In some cases, the HMD 100 may be independent of an external computing device and may execute an application and use the onboard components (e.g., logic, hardware, memory, processors (e.g., a central processing unit (CPU), a graphics processing unit (GPU), etc.), a battery, etc.) to render the corresponding images. The HMD 100 is configured to output a series of images (frames) viewable by the user through the optics within the HMD 100, causing the user to perceive the images as if immersed in a virtual reality (VR) or augmented reality (AR) environment.

[0025] The HMD100 may include a visor 106 that is interchangeable or mutually replaceable with other types of visors. The visor 106 may be of a customized shape, and the customized material and / or the visor 106 may include customized artwork (e.g., coloring, stickers, markings, holes, surface features, etc.). The user can interchange the visor 106 with a different visor to change the appearance or look of the HMD100 above the front of the HMD100. Different users using the HMD100 may have their own customized visors 106, and thereby, the user can remove the existing visor 106 and replace the existing visor 106 with the user's own customized visor. The visor 106 can be removably attached to the front of the HMD100 in any suitable manner, such as by a magnetic coupling mechanism (e.g., a magnet on the front of the HMD100 that couples to a corresponding magnet on the visor 106), a hook and loop fastener (e.g., Velcro®), pins, screws, hooks, snap / press fit mechanisms, adhesives, or any suitable type of fastener.

[0026] When attached to the HMD 100, the visor 106 may cover the compartment 102 (sometimes referred to herein as the "modular accessory compartment 102"). The compartment 102 may be of any suitable shape. FIG. 1 illustrates a rectangular compartment 102 that is recessed a certain distance in front of the HMD 100. The compartment 102 may include ports 104 such as a universal serial bus (USB) port 104 that is electrically connected to components of a printed circuit board (PCB) within the housing of the HMD 100. The port 104 may enable a user to connect a modular accessory to the HMD 100 and provide further customization to the user of the HMD 100. For example, lights (plural) (e.g., light-emitting diodes (LEDs)) can be connected to the port 104, thereby powering the lights and turning them on. These lights may be disposed within the compartment 102 behind the visor 106 and made of an optically transparent material (e.g., clear or colored plastic) to provide a customized lighting effect to the HMD 100. The visor 106 may be of any suitable color, and when the visor 106 covers the lights within the compartment 106 connected via the port 104, the visor 106 can be illuminated to provide a customized visual appearance. In some embodiments, a display (e.g., a liquid crystal display (LCD)) can be connected to the port 104 and disposed within the compartment 102 to render an image on the display while the HMD 100 is being worn by the user. In other scenarios, auxiliary camera(s) can be connected to the port 104 and disposed within the compartment 102. In some embodiments, auxiliary and / or backup computer processing resources (e.g., processing, memory, power, etc.) can be connected via the port 104 to enhance the processing power, memory capacity, and / or battery life of the HMD 100.

[0027] Figure 2 illustrates a front perspective view of the front portion of the HMD 100 of FIG. 1 according to an embodiment of the present disclosure. As shown in FIG. 2, the HMD 100 may include one or more forward-facing cameras 200(1) and / or 200(2). FIG. 2 illustrates an embodiment having two forward-facing cameras 200 including a first camera 200(1) and a second camera 200(2), but any suitable number of forward-facing cameras 200 may be utilized. The forward-facing cameras 200 may be used for any suitable purpose, such as optical tracking, pass-through imaging (e.g., projecting an image of the real-world environment onto the HMD 100, such as by projecting an image of the real world above the VR scene), obstacle detection (e.g., detecting objects within the real-world environment and optionally warning the user of a potential collision with such objects), recording video of the environment during gameplay, and the like. The forward-facing cameras 200 may be located at any suitable location on the HMD 100, such as on the upper front of the HMD 100, towards the bottom of the HMD 100 (e.g., the bottom half of the HMD 100), as shown in FIG. 2.

[0028] FIG. 3A illustrates a rear perspective view of an exemplary HMD 100 of FIG. 1 in a configuration where a head strap 300 of the HMD 100 is attached to a main unit 302 of the HMD 100, according to an embodiment of the present disclosure. FIG. 3B illustrates the exemplary HMD 100 shown in FIG. 3A, except that the head strap 300 is in a configuration where it is removed from the main unit 302 of the HMD 100. The head strap 300 can be removed so as to be exchanged or interchanged with a different head strap 300. Prolonged use of the HMD 100 may result in the material of certain portions of the head strap 300 absorbing body odor, such that the user may desire to occasionally remove the head strap 300 in order to "air out" the head strap 300, wash the head strap 300, replace the head strap 300 with a new head strap, etc. In some cases, the user may desire to interchange or exchange the head strap 300 with a different type of head strap (e.g., one having different features such as different headphones, different adjustment mechanisms, etc.). This provides further customization of the HMD 100 for different users.

[0029] As shown in FIG. 3B, the head strap 300 can be removed by removing an actuator 304 (e.g., a rotatable knob) located on the side surface of the HMD 100, and access can be gained to one or more screws 310(1) or similar fasteners. The removal of the actuator 304 can be achieved in any suitable manner, such as by forcibly pulling the actuator 304 outwardly to remove the actuator 304 from the mounting pin 308(1). The mounting pin 308(1) can be inserted through a main opening within a portion of the head strap 300, while one or more screws 310(1) can be threaded into one or more corresponding openings 306(1) within a portion of the head strap 300 so as to secure the head strap 300 to the main unit 302. The user can unscrew the screw(s) 310(1) and then slide and remove a portion of the head strap 300 from the mounting pin 308(1) to remove one side surface of the head strap 300 from the corresponding side surface of the main unit 302. On the opposite side surface of the main unit 302, there may be one or more screws (e.g., similar to the screw 310(1)) threaded into one or more corresponding openings 306(2) within another portion of the head strap 300 for securing the head strap 300 to the main unit 302 on the opposite side surface of the main unit 302. The user can unscrew these screws from the opposite side surface of the main unit 302 to remove the other side surface of the head strap 300 and thus the entire head strap 300 from the main unit 302. FIG. 3B also shows a belt loop 312 at the top of the main unit 302 of the HMD 100, and the belt loop 312 is configured to receive the top member of the head strap 300 by looping the top member of the head strap 300 through the belt loop 312 and securing the top member of the head strap 300 to the belt loop 312 itself. The securing mechanism for the top member of the head strap 300 may be any suitable mechanism such as a hook and loop fastener (e.g., Velcro (registered trademark)), snap, etc. In this way, the head strap 300 is removable and the user can freely reattach it again.

[0030] Figure 4 illustrates a rear perspective view of the main unit 302 of the exemplary HMD 100 of FIG. 1, according to one embodiment of the present disclosure, with the face gasket 400 disconnected from the main unit 302. The face gasket 400 can be removably attached to the main unit 302 of the HMD 100 in any suitable manner, such as by a magnetic coupling mechanism, hook and loop fasteners (e.g., Velcro®), pins, screws, hooks, snap / press fit mechanisms, adhesives, or any suitable type of fastener. FIG. 4 illustrates one embodiment in which a magnetic coupling mechanism(s) is used to removably couple the face gasket 400 to the main unit 302. For example, a plurality of first magnetic elements 402(1)-(4) (e.g., metal screws) disposed on the rear of the main unit 302 can be coupled to a plurality of second magnetic elements 404(1)-(4) (404(1) and 404(2) are not shown in FIG. 4) disposed on the front of the face gasket 400. In this way, the face gasket 400 can be easily and conveniently secured to the rear of the main unit 302 or removed from the rear of the body unit 302. A pad can be placed on the rear of the face gasket 400 to provide a comfortable fit when the HMD 100 is worn. As described above, long-term use of the HMD 100 may result in the material of certain components, such as the face gasket 400, absorbing body odor. As a result, the user may sometimes desire to remove the face gasket 400 in order to "air it out," wash the face gasket 400, replace the face gasket 400 with a new face gasket, etc. In some embodiments, the user may desire to interchange or replace the face gasket 400 with a different type of face gasket (e.g., one having different features, profiles, contours, etc.). This allows for further customization of the HMD 100 for different users.

[0031] FIG. 5A illustrates a partial front view and bottom view of the exemplary HMD 100 of FIG. 1 according to one embodiment of the present disclosure, with the front portion of the HMD housing removed to reveal the components of the interpupillary distance (IPD) adjustment mechanism, and the IPD adjustment mechanism is adjusted to the first end of the adjustment range in FIG. 5A and to the second end of the adjustment range in FIG. 5B. The IPD adjustment mechanism of the HMD 100 enables adjustment of the horizontal distance between a pair of lens barrels of the HMD 100. FIGS. 6A and 6B illustrate exemplary lens barrels 600(1) and 600(2) (which may also be referred to herein as "lens assemblies"), and the lens barrels 600(1) and 600(2) can be moved closer to or farther apart from each other using the IPD adjustment mechanism to respectively decrease or increase the horizontal distance between the lens barrels. In particular, the IPD adjustment mechanism described herein is particularly convenient to operate while wearing the HMD 100, can be operated using a single hand or finger, and includes a dual biasing assembly for providing a smooth and controlled operation of the IPD adjustment mechanism over the adjustment range. Thereby, the distance between the lens barrels 600(1) and 600(2) can be finely adjusted to correspond to the user's IPD.

[0032] As shown in FIGS. 5A and 5B, the IPD adjustment mechanism may include an actuator 500. The actuator 500 may be located on (or within) the bottom of the HMD 100 and face the right or left half of the HMD 100. The actuator 500 can be implemented in any suitable manner (e.g., a rotatable knob, a lever, a pushable button that toggles between adjustment positions, etc.). However, the actuator 500 shown in FIGS. 5A and 5B includes a knob that is slidable (or otherwise movable) within a channel 502 defined within the housing of the HMD 100. The actuator 500 is configured to be actuated by a user of the HMD 100 to adjust the distance (or spacing) between the lens barrels 600(1) and 600(2) (as shown in FIGS. 6A and 6B). Thus, the actuator 500 is accessible from the outside of the housing of the HMD 100. In the embodiment of FIGS. 5A and 5B, moving the actuator 500 to the first end of the channel 502 (as shown in FIG. 5A, for example) maximizes the horizontal distance (or spacing) between the pair of lens barrels 600 of the HMD 100. Moving the actuator 500 to the second end of the channel 502, which is opposite the first end of the channel 502 (as shown in FIG. 5B, for example), minimizes the horizontal distance (or spacing) between the pair of lens barrels 600 of the HMD 100. In this way, a user with a smaller IPD can adjust the knob towards the second end of the channel 502 (as shown in FIG. 5B), while a user with a larger IPD can adjust the knob towards the first end of the channel 502 (as shown in FIG. 5A). Markings can be provided on the outer surface of the HMD housing along the channel 502 to indicate to the user that the horizontal spacing between the lens barrels 600 is adjustable. Since the actuator 500 and the channel 502 are located on either the right or left half of the HMD 100, on the bottom of the HMD 100, the user can easily and conveniently slide the actuator 500 within the channel 502 using their right or left thumb (e.g., with a single hand) to adjust the spacing between the lens barrels 600.The locations of the actuator 500 and the channel 502, along with the ease of operation of the actuator 500 and the channel 502, enable the user to adjust the spacing of the lens barrel 600 with a single hand and to perform this adjustment while wearing the HMD 100 without the need for the user to remove the HMD 100 or hold the HMD 100 with two hands while adjusting the spacing of the lens barrel 600. This enables the user to determine, while wearing the HMD 100 and in real time, which position of the actuator 500 is optimal for them, thus enabling the user to more quickly obtain the optimal lens barrel 600 spacing.

[0033] The IPD adjustment mechanism may include components inside the housing of the HMD 100 that enable smooth and easy operation of the IPD adjustment mechanism. For example, an end of the actuator 500 that is inside the HMD housing may be coupled to an elongate member 504 that is movable at a first end of the elongate member 504. As shown in FIGS. 5A and 5B, the elongate member 504 may be oriented horizontally and adjacent to the bottom of the HMD 100. However, it should be understood that other orientations of the elongate member 504 are possible. A channel or slot may be defined within the elongate member 504 adjacent an end of the elongate member 504 coupled to the actuator 500, and an anchor 506 attached to an intermediate frame of the HMD 100 may extend through the channel / slot of the elongate member 504 to enable the elongate member 504 to translate bidirectionally (e.g., in a first or second horizontal direction when the HMD 100 is upright and oriented) over the adjustment range of the IPD adjustment mechanism. In this way, the elongate member 504 is coupled to the intermediate frame of the HMD 100 but is movable bidirectionally.

[0034] The first end of the first biasing member 508 may be connected to the first end of the elongate member 504, and the second end of the first biasing member 508 may be connected to the intermediate frame of the HMD 100. Here, the first end of the elongate member 504 (connected to the first biasing member 508) is farthest from the actuator 500, while the second end of the elongate member 504 is closest to the actuator 500. The second end of the first biasing member 508 may be attached to the intermediate frame of the HMD 100 at a point closer to the actuator 500 than the point at which the first end of the elongate member 504 is with respect to the actuator 500. In this way, the first biasing member 508 is configured to physically bias the elongate member 504 horizontally by applying a biasing force to the elongate member 504 that resists the movement of the elongate member 504 in the direction of travel of the elongate member 504. In the embodiments of FIGS. 5A and 5B, when the actuator 500 moves from the left end of the channel 502 to the right end of the channel 502 (from the perspective of FIGS. 5A and 5B), the elongate member 504 translates in the rightward direction of travel, and the first biasing member 508 resists the rightward movement of the elongate member 504 by the biasing force applied to the elongate member 504 in the leftward direction. In some embodiments, the first biasing member 508 is a spring, and the biasing force of this spring on the elongate member 504 increases as the elongate member 504 moves farther and farther in the rightward horizontal direction (from the perspective of FIGS. 5A and 5B). This biasing force from the first biasing member 508 smooths the sliding movement of the actuator 500 within the channel 502 when the user slides the actuator 500 within the channel 502, rather than a jerky movement. Additionally, or alternatively, one or more friction members assist in resisting the movement of the actuator 500 within the channel 502, making the movement smoother and more controlled, and allowing for easier fine-tuning of the IPD adjustment.

[0035] The elongated member 504 may include a plurality of teeth that extend over at least a portion of the elongated member 504 on the top side surface of the elongated member 504. The teeth of the elongated member 504 engage the teeth of a rotatable gear 510 (sometimes referred to herein as a "helical gear") mounted on an axis on the intermediate frame of the HMD 100. The gear 510 may be disposed between a pair of movable frames 516(1) and 516(2) that are connected to a pair of lens barrels 600 near or at the center of the HMD 100. The gear 510 may include a face having a pair of helical protrusions 512(1) and 512(2) that extend from the face of the gear 510. A rod 514 (sometimes referred to herein as a "sliding rod") may be connected to the intermediate frame of the HMD 100. The sliding rod 514 may be oriented horizontally (when the HMD 100 is upright and oriented) and may extend substantially across the width of the HMD 100. As described above, each lens barrel 600 of the pair of lens barrels 600 may be connected to a corresponding movable frame 516 within the HMD housing, and each movable frame 516 may include a wing member 518, and the wing member 518 protrudes from the back side of the movable frame 516 connected to the sliding rod 514 (e.g., by the sliding rod 514 passing through an opening within the wing member 518). In this way, the pair of lens barrels 600 may be connected to the rod 514 via the movable frame 516. As shown in FIG. 5A, each wing member 518 may also include a protrusion 519 that extends horizontally from the wing member 518 toward the gear 510. The protrusion 519 extending from the wing member 518 engages one of the helical protrusions 512 extending from the face of the gear 510. For example, a first protrusion 519(1) may extend from the wing member 518(1) and may engage the helical protrusion 512(1), while a second protrusion 519(2) may extend from the wing member 518(2) and may engage the helical protrusion 512(2).

[0036] A pair of second biasing members 520(1) and 520(2) can be connected to the sliding rod 514. For example, the second biasing member 520 can be installed on the sliding rod 514 and can include a spring positioned between a stop portion 522 on the sliding rod 514 and a wing member 518 of each movable frame 516. FIGS. 5A and 5B show a first stop portion 522(1), and a second biasing member 520(1) between the first stop portion 522(1) and the wing member 518(1), as well as a second stop portion 522(2), and a second biasing member 520(2) between the second stop portion 522(2) and the wing member 518(2). Each of the second biasing members 520 can be fixedly positioned in place with respect to the sliding rod 514 at one end of the second biasing member 520 (e.g., the stop portion 522 on the sliding rod 514), and the second biasing member 520 can apply a biasing force to the corresponding wing member 518 connected to the sliding rod 514, and the biasing force is applied in a direction toward the gear 510 such that a protrusion 519 extending horizontally from the wing member 518 is physically biased against a corresponding helical protrusion 512 extending from the face of the gear 510. Since the movable frame 516 is movable bidirectionally along the rod 514 between the left and right sides of the HMD 100, the movable frame 516, and thus the lens barrel 600 connected to the movable frame 516, moves in response to the operation of the actuator 500.

[0037] As shown in FIGS. 5A and 5B, the user can slide the actuator 500 of the IPD adjustment mechanism within the channel 502, thereby translating the elongated member 504 in a first direction (e.g., the rightward direction from the perspective of FIGS. 5A and 5B). The teeth of the elongated member 504 that engage the teeth of the gear 510 cause the gear 510 to rotate. In a first rotational direction of the gear 510, the helical protrusion 512 extending from the face of the gear 510 applies a force to the protrusion 519 extending from the wing member 518 of the movable frame 516, moving the movable frame 516 (and thus the lens barrel 600) further away and increasing the distance between the lens barrels 600 (as shown in FIG. 5A). In a second rotational direction of the gear 510, a pair of second biasing members 520 apply a biasing force to the wing member 518 of the movable frame 516, moving the movable frame 516 (and thus the lens barrel 600) closer together and decreasing the distance between the lens barrels 600 (as shown in FIG. 5B). This is partially due to the helical protrusion 512 on the gear 510 moving spirally inward from each point around the gear 510 to a point closer to the center of the gear 510 than each of those points around the gear 510.

[0038] In particular, when the movable frame 516 (and thus the lens barrel 600) moves further away, the pair of second biasing members 520 resist the movement of the movable frame 516 in the direction of travel of each movable frame 516. This makes the sliding movement of the actuator 500 in the channel 502 smooth and controlled rather than jerky when the user slides the actuator 500 in the channel 502. Thus, the first biasing member 508 and the pair of second biasing members 520 work together to enable smooth and controlled sliding movement of the actuator 500 in the channel 502, so that the user can easily fine-tune the IPD adjustment even while wearing the HMD 100. Additionally or alternatively, one or more friction members can assist in resisting the movement of the actuator 500 in the channel 502, making the movement smoother and making it easier to fine-tune the IPD adjustment. Due to the opposing biasing members and / or friction members, the actuator 500 is movable within the channel 502 to any position within the channel 502 as desired by the user, and when the user removes their finger from the actuator 500, the actuator 500 remains stationary at its current position within the channel 502.

[0039] As shown in FIGS. 6A and 6B, the operation of the actuator 500 causes a corresponding adjustment of the distance between the lens barrels 600 of the HMD 100. For example, as shown in FIG. 6A, when the actuator 500 is moved to the first end of the channel 502, the horizontal distance (spacing) between the lens barrel 600(1) and the lens barrel 600(2) is maximized. The lens barrels 600 can be substantially horizontally aligned. As shown in FIG. 6B, when the actuator 500 is moved to the second end of the channel 502, the horizontal distance (spacing) between the lens barrel 600(1) and the lens barrel 600(2) is minimized. Intermediate spacing can be achieved by moving the actuator 500 to an intermediate position within the channel 502. In this sense, the actuator 500 can move in a smooth and continuous motion along the channel 502, as opposed to individual "clicks" between multiple adjustment positions, and the user feels a bi-directional resistance in either direction in which the actuator 500 moves by the biasing assembly described herein.

[0040] FIG. 7A illustrates a partial front perspective view of an exemplary HMD 100 of FIG. 1 according to an embodiment of the present disclosure, with a portion of the HMD housing removed to reveal components of the field of view (FOV) adjustment mechanism, and in FIG. 7A the FOV adjustment mechanism is adjusted to a first end of the adjustment range. FIG. 7B shows the FOV adjustment mechanism adjusted to a second end of the adjustment range. The FOV adjustment mechanisms illustrated in FIGS. 7A and 7B enable adjustment of the distance between the user's face and the lens or lens barrel 600 (or display panel) of the HMD 100. This field of view (FOV) adjustment mechanism (which may also be referred to herein as an "eye relief adjustment mechanism") is particularly convenient to operate while wearing the HMD and is operable using a single hand to smoothly adjust (e.g., increase or decrease) the distance between the lens of the HMD 100 and the user's face over the adjustment range. The FOV adjustment mechanism may include an actuator 304 disposed on a first side of the HMD 100 (of two sides, i.e., the right and left sides). Generally, the actuator 304 is configured to be actuated by a user of the HMD 304, and thus the actuator 304 is accessible from the outside of the HMD housing.

[0041] Actuator 304 is shown as a rotatable actuator (e.g., a rotatable knob) in FIGS. 7A and 7B, but actuator 304 can include any suitable adjustable element including, but not limited to, a dial, lever, wheel, and / or slider (or slidable knob). Actuator 304 can be located where head strap 300 abuts major unit 302 of HMD 100. Actuator 304 can be actuated (e.g., rotated) over an adjustment range to thereby actuate (e.g., rotate) the actuator to a first end of the adjustment range in a first direction to minimize the distance (or spacing) between the lens and the user's face and to a second end of the adjustment range in a second direction opposite the first direction to maximize the distance (or spacing) between the lens and the user's face. In this way, the FOV and / or eye relief can be optimized for different users. Markings can be provided on the outer surface of the HMD housing around or on actuator 304 to indicate to the user that the spacing between the lens and the user's face is adjustable. Since actuator 304 is located on one side (e.g., the right or left side) of HMD 100, the user can easily and conveniently actuate actuator 304 using the user's right or left hand (e.g., a single hand) to adjust the spacing between the lens and the user's face. The location of actuator 304, along with the ease of operation of actuator 304, enables the user to adjust the FOV and / or eye relief with a single hand and to perform this adjustment while wearing HMD 100 without the need to remove HMD 100 or hold HMD 100 with both hands while the user adjusts the FOV and / or eye relief. This enables the user to more quickly obtain an optimal FOV and / or eye relief since the user can wear HMD 100 while adjusting the FOV and / or eye relief and determine in real time which position of actuator 304 is optimal for them.

[0042] The FOV adjustment mechanism includes components inside the housing of the HMD 100 that enable uniform, smooth, controlled, and / or comfortable operation of the FOV adjustment mechanism. Actuator 304 (e.g., a rotatable knob), in addition to being rotatable, may be pushable between a first position and a second position by pushing actuator 304, similar to a pushable button. A biasing member biases actuator 304 in an outward direction with respect to the HMD 100 such that when the user is not pushing actuator 304, actuator 304 is physically biased to a first position where it extends (i.e., is not pushed). When actuator 304 is extended, a protrusion (or tooth) engages a certain detent among a plurality of detents inside actuator 304, thereby locking actuator 304 in the sense of preventing actuator 304 from rotating in either direction (clockwise or counterclockwise) over its adjustment range. The user can move actuator 304 to the second position where actuator 304 is pushed, thereby unlocking actuator 304 by disengaging the protrusion from the detent inside actuator 304. In this second position, while pushing actuator 304, the user can rotate actuator 304 as needed to adjust the distance between the lens and the user's face. When actuator 304 is released or the pressure on actuator 304 is relieved, the biasing member inside actuator 304 physically biases actuator 304 to the extended first position, engaging the protrusion with the detent, thereby locking actuator 304 in place (in the rotational direction). This locking mechanism prevents unwanted adjustment of the distance between the lens and the user's face, such as during a game play where the user desires to keep the FOV and / or eye relief fixed at a desired position.

[0043] The actuator 304 can cause rotation of a pair of gear assemblies on both sides of the HMD 100 connected by the connecting rod 706. The pair of gear assemblies can adjust the lens closer to or farther from the user's face. Specifically, the main unit 302 of the HMD 100 may include a first portion connected to the lens barrel 600 and a second portion movable relative to the first portion. For example, the second portion of the HMD 100 may be a portion of the main unit 302 that is closer to (e.g., in contact with) the user's face while the user is wearing the HMD 100. Referring briefly to FIG. 3B, this second portion 314 is the portion of the main unit 302 where the actuator 304 is disposed thereon. The first portion 316 of the HMD 100 may be a portion of the main unit 302 that is farther from (e.g., not in contact with) the user's face while the user is wearing the HMD 100. For example, the first portion 316 of the HMD 100 may include, but is not limited to, the lens barrel 600, the display panel, a PCB with electrical components mounted thereon, etc. These first and second portions of the HMD 100 are movable relative to each other in both directions and by the rotational operation of the actuator 304.

[0044] The first gear assembly disposed on the side surface of the same HMD 100 as the actuator 304 can be connected to both the actuator 304 and both the first portion 316 of the HMD 100 and the second portion 314 of the HMD 100 that are movable in both directions and relative to each other. The first gear assembly may include a first rotatable gear 702(1) having teeth that engage the teeth of the elongated member 700(1). The teeth of the elongated member 700(1) may be disposed on the top side surface of the elongated member 700(1). The elongated member 700(1) may be oriented such that the elongated member 700(1) extends in a direction from the rear of the HMD 100 to the front of the HMD 100. The elongated member 700(1) may be connected to or engaged with the actuator 304, and the elongated member 700(2) may also be connected to the second portion 314 of the HMD 100 that is closer to the user's face than the first portion 316 of the HMD 100. Since the elongated member 700(1) is connected to the second portion 314 of the HMD 100, when the actuator 304 rotates, the elongated member 700(1) translates forward or backward to translate the second portion 314 of the HMD 100 (the portion closer to the user's face) forward or backward relative to the first portion 316 of the HMD 100 (the portion farther from the user's face including the lens, display, and PCB).

[0045] The elongated member 700(1) may also include teeth that engage the teeth of the first gear 702(1), and the first gear 702(1) is mounted on a shaft on the intermediate frame of the HMD100. The first gear 702(1) of the first gear assembly engages the second rotatable gear 704(1) of the first gear assembly, and the second gear 704(1) is coupled to a rod 706 (which may also be referred to herein as the "connecting rod"). The connecting rod 706 may be coupled to the intermediate frame of the HMD, the connecting rod 706 may be oriented horizontally, and may extend substantially across the width of the HMD100. The connecting rod 706 also connects the first gear assembly to the second gear assembly, and the second gear assembly is disposed on a second side of the HMD100 opposite the first side of the HMD100 where the first gear assembly is disposed. Rotation of the second gear 704(1) of the first gear assembly causes a corresponding rotation of the connecting rod 706.

[0046] The second gear assembly may include a third rotatable gear coupled to the connecting rod 706 in substantially the same manner as the second gear 704(1) of the first gear assembly is connected to the connecting rod 706 at the opposite end of the rod 706. Rotation of the connecting rod 706 causes a corresponding rotation of this third gear of the second gear assembly. This third gear of the second gear assembly engages a fourth rotatable gear of the second gear assembly, and the fourth gear of the second gear assembly is substantially the same as the first gear 702(1) of the first gear assembly. Thus, the fourth gear of the second gear assembly may likewise be mounted on a shaft on the intermediate frame of the HMD100. The teeth of the fourth gear engage the teeth of the second elongate member 700(2) of the second gear assembly. This second elongate member 700(2) may also have teeth on the top side surface of the elongate member 700(2), and the elongate member 700(2) of the second gear assembly is likewise movable relative to the first portion 316 of the HMD100 (the portion further from the user's face, including the lens, display, and PCB), except that the second elongate member 700(2) is connected to the second portion 314 of the HMD100 on the side opposite the side to which the first elongate member 700(1) is connected to the second portion 314 of the HMD100, and may be attached to the second portion 314 of the HMD100 (the portion closer to the user's face).

[0047] Accordingly, when the actuator 304 rotates, both of the elongated members 700(1) and 700(2) of each gear assembly translate forward or backward depending on the direction of rotation of the actuator 304, thereby translating the first and second portions of the HMD 100 in opposite directions relative to each other, thereby adjusting the FOV and / or eye relief. For example, the first portion 316 of the HMD 100 (the portion farther from the user's face, including the lens, display, and PCB) can move away from the second portion 314 of the HMD 100 (the portion closer to the user's face) in a first direction or toward the second portion 314 in a second direction. By controlling the movement of these HMD portions using the elongated members 700(1) and 700(2) on opposite sides of the HMD 100 connected by the connecting rod 706, the first and second portions of the HMD 100 can translate uniformly relative to each other without any wobbling (or racking) of these portions when translating bidirectionally forward or backward. This smooth and uniform adjustment provided by the FOV (or eye relief) adjustment mechanism enables convenient operation by a user using a single hand while wearing the HMD 100.

[0048] FIG. 8 illustrates a front perspective view of an exemplary HMD 100 of FIG. 1, and FIG. 8 illustrates exemplary locations of unobtrusive spectral transmissive windows 800(1) to (N) (collectively 800, where N is any integer) within the housing of the HMD 100, according to one embodiment of the present disclosure. In some embodiments, as indicated by the dashed lines behind each window 800, a plurality of corresponding spectrum-specific sensors are mounted inside the HMD housing behind the spectral transmissive window 800. The sensors within the HMD housing are sensitive to light of a particular spectrum. In some embodiments, the spectral transmissive window 800 is an infrared (IR) transmissive window, and the spectrum-specific sensor located behind the window 800 is an IR sensor (i.e., a sensor configured to detect light in the IR spectrum). The examples herein mainly relate to IR transmissive windows and IR sensors, but any mention of "IR transmissive" herein can be replaced with "spectral transmissive" for spectra other than the IR spectrum, and "IR sensor" can be understood to be replaced with "spectrum-specific sensor" to describe a sensor configured to detect electromagnetic radiation in a spectrum other than the IR spectrum. Further, instead of sensors, a plurality of corresponding spectrum-specific beacons may be mounted inside the HMD housing behind the spectral transmissive window 800, and the beacons are configured to emit light (electromagnetic radiation) of a particular spectrum.

[0049] Accordingly, the HMD 100 can comprise a housing made of a spectrally transmissive (IR transmissive) material, the outer surface of the housing being coated with an IR non-transmissive material, and one or more locations on the outer surface being lacking in the IR non-transmissive material, the location(s) corresponding to the window 800. One or more spectrum-specific sensors (and / or beacons) can be disposed behind the housing at one or more locations corresponding to the window 800. In some embodiments, the outer surface of the HMD housing is also coated with a spectrally transmissive coating that covers a spectrally non-transmissive material and one or more locations on the outer surface lacking the spectrally non-transmissive material. Any suitable IR transmissive material and IR non-transmissive material known to those skilled in the art can be used herein to create an IR transmissive window 800 that allows electromagnetic radiation (light) in the IR spectrum to pass through. For example, the IR non-transmissive material can include acrylic or paint configured to block electromagnetic radiation in the IR spectrum. An IR transmissive polycarbonate plastic can be used for the base material of the HMD housing.

[0050] The thickness of the housing at the location(s) of the window(s) 800 can be thinner than the thickness of the remainder of the HMD housing. In this way, when the sensor is mounted on the inner surface of the HMD housing directly behind the window 800, the sensor can be brought closer to the outer surface of the HMD housing, minimizing the size of the window 800. Accordingly, the size of each spectrally transmissive window 800 can be configured based on the tolerance for installing the corresponding sensor behind the spectrally transmissive window 800. In some embodiments, the spectrum-specific sensor is mounted inside the HMD housing using an adhesive behind the corresponding spectrally transmissive window 800. The spectrally transmissive window 800 can be configured to allow electromagnetic radiation in a specific spectrum (e.g., light in the IR spectrum) to pass through the window 800 while filtering (or blocking) electromagnetic radiation in at least one spectrum (e.g., the visible spectrum).

[0051] As shown in FIG. 8, a plurality of spectral transmissive windows 800 may be provided on the housing of the HMD 100. At least some of the plurality of spectral transmissive windows 800 may be located on the front of the HMD 100 along the top of the HMD 100, along the bottom of the HMD 100, and / or along one or more sides in front of the HMD 100. As shown in FIG. 8, at least some of the windows 800 may be located on the top of the HMD 100, the bottom of the HMD 100, and / or on one or more sides of the HMD 100. By covering the HMD 100 in this way, optimal tracking is provided using an optical tracking system that may include one or more beacons that emit electromagnetic radiation in a particular spectrum. For example, one or more beacons positioned within the environment of the HMD 100 may sweep a beam of IR light (e.g., a fan beam) across the play space, and an IR sensor disposed inside the HMD housing behind the IR transmissive window 800 may detect the beam sweep and, in some cases, detect a synchronization pulse emitted by the optical tracking system.

[0052] The processes described herein are presented as a collection of blocks in a logical flow graph representing the order of operations. The order in which the operations are described is not intended to be construed as a limitation, and any of the several described blocks may be combined in any order and / or in parallel to implement the process.

[0053] A process for manufacturing an HMD housing including a plurality of spectral transmissive windows 800 may include, at 902, forming an HMD housing made of a spectral transmissive material (e.g., IR transmissive polycarbonate plastic). As indicated by sub-block 904, forming the housing may include injection molding the HMD housing using injection molding techniques.

[0054] At 906, material can be removed from the inner surface of the HMD housing at the location where the spectral transmissive window 800 is fabricated. This removal of material reduces the thickness of the HMD housing only at the location where the spectrum-specific sensor (and / or beacon) is positioned (e.g., mounted), thereby bringing the sensor / beacon closer to the outer surface of the HMD housing when positioned (e.g., mounted) adjacent to the inner surface of the HMD housing behind the spectral transmissive window 800. In this way, positioning the sensor closer to the outer surface enables achieving the field of view (FOV) of the sensor with a particular angular range while minimizing the size of the spectral transmissive window 800. In some embodiments, removing the material from the inner surface creates a recess within the HMD housing where the sensor / beacon is positioned (e.g., mounted). Removing the material from the inner surface of the HMD housing also enables keeping the outer surface flat and smooth (as opposed to creating a recess within the outer surface of the HMD housing).

[0055] At 908, the outer surface of the HMD housing can be coated with a spectrally non-transmissive material (e.g., coating the outer surface of the housing with an IR non-transmissive film). This can include coating substantially the entire outer surface of the HMD housing to cover the outer surface with the spectrally non-transmissive material.

[0056] At 910, the spectrally non-transmissive material can be selectively removed from the outer surface at the location where the sensor / beacon is to be mounted later. This creates a spectrally transmissive window 800 within the HMD housing. As indicated by sub-block 912, the selective removal of the material can involve using laser etching techniques to remove the spectrally non-transmissive material. In some embodiments, a circular portion of the spectrally non-transmissive material is removed to create a circular spectrally transmissive window 800 (also referred to herein as an "aperture") within the HMD housing. In some embodiments, at block 910, a photolithography process can be used to remove the spectrally non-transmissive material from the outer surface at the location of the sensor / beacon. In some embodiments, at block 910, removing the spectrally non-transmissive material can involve placing a sticker on the outer surface of the HMD housing at the location where the spectrally transmissive window 800 will be created prior to block 908, then, at block 908, coating the outer surface of the HMD housing with the spectrally non-transmissive material, and, at block 910, removing the sticker and selectively removing the spectrally non-transmissive material at the location of the sticker to create the spectrally transmissive window 800 where the sticker was located. In some embodiments, a fixture having a pattern of pins can be moved to a position where the pins contact the outer surface of the HMD housing prior to block 908, and while the pins are in contact with the outer surface, at block 908, coating the outer surface of the HMD housing with the spectrally non-transmissive material, and, at block 910, removing the pins from the HMD housing and selectively "removing" the spectrally non-transmissive material at the locations where the pins were located to create the spectrally transmissive window 800 at these locations.Yet another way to create the spectral transmissive window 800 is to apply an oleophobic coating on the HMD housing in a specific pattern before block 908, and then, in block 908, paint the outer surface of the HMD housing with a spectrally non-transmissive material. At this point, the spectrally non-transmissive material adheres to the portions of the outer surface that are not coated with the oleophobic coating and does not adhere to the portions of the outer surface that are coated with the oleophobic coating.

[0057] In 914, after removing the spectrally non-transmissive material at the selected location, the outer surface of the HMD housing can be painted with a spectrally transmissive coating (e.g., a hard and clear coating material (or film) that is IR transmissive) to create an HMD housing with a smooth outer surface and a spectral transmissive window 800 that is hardly visible to the naked eye even in broad daylight. In a dark environment, the spectral transmissive window 800 is at least unobtrusive if not visible to the naked eye, and the outer surface of the HMD housing has a smooth appearance.

[0058] The disclosed process for manufacturing an HMD housing that includes a plurality of spectral transmissive windows 800 is more cost-effective than manufacturing a similar HMD housing using a so-called "two-shot" injection molding process that involves fabricating most of the HMD housing from an IR-opaque plastic and fabricating a small portion of the HMD housing from an IR-transmissive plastic to create a window over an IR sensor mounted inside the HMD housing. In contrast, the disclosed manufacturing process for creating a spectral transmissive (e.g., IR-transmissive) window 800 on an HMD housing involves using a common spectral transmissive material as the base material for the HMD housing and then coating most of the HMD housing with a spectral non-transmissive material, which is cost-effective compared to a two-shot process for manufacturing an HMD housing that includes a plurality of spectral transmissive windows 800. Since the HMD housing is made from a spectral transmissive material, a portion of the light of a particular spectrum (e.g., IR light if the particular spectrum is the IR spectrum) can pass through the spectral transmissive window 800 to the underlying sensor, while a portion of the light of a particular spectrum can internally reflect within the HMD housing itself. As a result, a portion of the light of a particular spectrum received through one spectral transmissive window 800(1) can reach a nearby sensor (e.g., the sensor behind window 800(2)) due to these internal reflections. To reduce the effect of internally reflected light of a particular spectrum on nearby spectrum-specific sensors, the spectral transmissive material used as the base material for the HMD housing can be modified with an additive that causes the HMD housing to absorb slightly more light of a particular spectrum (e.g., absorb slightly more IR), thereby reducing the degree of internal reflection.

[0059] Another method of manufacturing an HMD housing that includes a plurality of spectral transmissive windows involves the use of so-called "in-mold labeling." For example, a spectral transmissive ink (e.g., an IR transmissive ink) can be printed on a plastic sheet in a specific pattern corresponding to the positioning of the spectral transmissive windows on the HMD housing to be formed, the sheet with the spectral transmissive ink printed thereon can be thermoformed into the desired shape of the HMD housing, and then a spectrally non-transmissive material can be overmolded onto the thermoformed sheet to create an HMD housing with spectral transmissive windows. Yet another method of manufacturing an HMD housing that includes a plurality of spectral transmissive windows involves the so-called "laser direct structuring" technique. For example, the HMD housing can be injection molded, a laser beam can be used to create a recessed pattern within the HMD housing, and a metal can be plated onto the recessed pattern within the HMD housing by a metallization process to create spectral transmissive windows within the HMD housing.

[0060] As described above, the thickness of the HMD housing at the location of the spectral transmissive window 800 can be made as thin as possible (e.g., by using a subtractive manufacturing process that removes material from the inner surface of the HMD housing at these locations), while the remaining portions of the HMD housing can maintain a greater thickness so as to provide rigidity to the HMD housing. Having a locally thinned portion of the HMD housing where the spectrum-specific sensor / beacon is located means that the sensor can be positioned closer to the outer surface of the HMD housing, which reduces the amount of refraction and the amount of optical artifacts when light of a particular spectrum passes through the spectral transmissive window 800. Since the sensor / beacon disposed behind the window 800 can be used in an optical tracking system that tracks the pose of the HMD 100 as the HMD 100 moves within a volume, the reduction in refraction and optical artifacts means that a more accurate spectrum-specific (e.g., IR) beam sweep window is achieved. Further, the size of the spectral transmissive window can limit the angular range within which each spectrum-specific sensor can receive light of a particular spectrum and / or within which a spectrum-specific beacon can emit light of a particular spectrum. In some embodiments, the spectral transmissive window 800 is sized such that the sensor receives and / or the beacon emits light of a particular spectrum over an angular range of about 120 degrees. The goal may be to make the size of each spectral transmissive window 800 as small as possible (e.g., for aesthetic purposes) without unduly limiting the angular range within which the sensor receives light of a particular spectrum and / or within which the beacon emits light of a particular spectrum. In some embodiments, the diameter of an individual spectral transmissive window may be in the range of 4 millimeters to 7 millimeters or in the range of 6 millimeters to 6.5 millimeters.

[0061] It should be understood that the optical tracking of the HMD100 is just one example of the use of the spectrum-specific sensors / beacons and the spectral transmissive window 800 described herein. For example, a spectrum-specific camera (e.g., an IR camera) can be mounted inside the HMD housing and under the spectral transmissive window so as to remain unobtrusive when the HMD100 is fully assembled. Such a camera can be a tracking camera or any other type of sensor configured to detect electromagnetic radiation of a specific spectrum.

[0062] The above can also be understood in consideration of the following clauses. 1. A head-mounted display (HMD) comprising: A rod connected to an intermediate frame of the HMD; A first movable frame connected to the rod and a first lens barrel, the first movable frame being movable bidirectionally along the rod in a first direction towards the left side of the HMD or a second direction towards the right side of the HMD; A second movable frame connected to the rod and a second lens barrel, the second movable frame being movable bidirectionally along the rod in the first direction or the second direction; An actuator on the bottom of the HMD, the actuator being configured to be actuated by a user of the HMD; A movable elongated member connected to the actuator and the intermediate frame, the movable elongated member being movable bidirectionally in the first direction or the second direction; A first biasing member connected to the movable elongated member and the intermediate frame, the first biasing member being configured to physically bias the movable elongated member in at least one of the first direction or the second direction; A rotatable gear connected to the intermediate frame and disposed between the first movable frame and the second movable frame, the rotatable gear engaging the movable elongated member; A second biasing member coupled to the rod and configured to physically bias a first movable frame against a first helical protrusion extending from a face of a rotatable gear. A third biasing member coupled to the rod and configured to physically bias a second movable frame against a second helical protrusion extending from a face of a rotatable gear. A head-mounted display (HMD) in which actuation of an actuator causes movement of a movable elongated member in one of a first direction or a second direction, rotates a rotatable gear, and moves a first movable frame and a second movable frame in opposite directions to adjust a spacing between a first lens barrel and a second lens barrel. 2. The HMD according to clause 1, wherein the actuator comprises a knob slidable within a channel defined within a housing of the HMD. 3. The HMD according to clause 1, wherein the actuator is located on at least one of a right half of the HMD or a left half of the HMD. 4. The HMD according to clause 1, wherein the first helical protrusion and the second helical protrusion spiral inwardly from respective points around the rotatable gear to respective points closer to the center of the rotatable gear than the respective points around the periphery. 5. The first movable frame includes a first wing member protruding from a back side of the first movable frame, and the first wing member includes a first opening. The first movable frame is coupled to the rod by passing the rod through the first opening within the wing member. The second movable frame includes a second wing member protruding from a back side of the second movable frame, and the second wing member includes a second opening. 20. The HMD according to clause 1, wherein the second movable frame is coupled to the rod by passing the rod through the second opening within the wing member. 6. A head-mounted display (HMD), comprising: A pair of lens barrels, including a first lens barrel and a second lens barrel; A rod connected to an intermediate frame of the HMD; A pair of movable frames connected to the pair of lens barrels, the pair of movable frames being movable bidirectionally along the rod in a first direction toward the left side of the HMD or a second direction toward the right side of the HMD; An actuator accessible from the outside of the housing of the HMD; A movable elongated member connected to the actuator and the intermediate frame; A first biasing member connected to the movable elongated member and the intermediate frame, the first biasing member being configured to resist movement of the movable elongated member in the direction of travel of the elongated member; A rotatable gear connected to the intermediate frame and disposed between the pair of movable frames, the rotatable gear engaging with the movable elongated member; A pair of second biasing members connected to the rod, the pair of second biasing members being configured to physically bias the pair of movable frames against a pair of spiral protrusions extending from the face of the rotatable gear. A head-mounted display (HMD). 7. The HMD according to clause 6, wherein the actuator comprises a knob slidable within a channel defined within the housing of the HMD. 8. The HMD according to clause 6, wherein the actuator is located on at least one of the right half or the left half of the HMD. 9. The HMD according to clause 6, wherein the pair of spiral protrusions spiral inwardly from respective points around the rotatable gear to respective points closer to the center of the rotatable gear than the respective points around the rotatable gear. 10. Each movable frame of the pair of movable frames includes a wing member protruding from the back side of the movable frame, the wing member including an opening. The HMD according to clause 6, wherein the rod passes through an opening in the wing member of each movable frame. 11. The HMD according to clause 10, wherein the pair of second biasing members are springs disposed on the rod, and each spring extends between a stop portion connected to the rod and a corresponding one of the wing members of the pair of movable frames. 12. The HMD according to clause 6, wherein a movable elongate member is connected to the intermediate frame by an anchor extending through a channel defined within the movable elongate member. 13. A wearable display, a rod connected to an intermediate frame of the wearable display, a pair of movable frames connected to a pair of lens assemblies and movable bidirectionally along the rod in a first direction toward the left side of the wearable display or a second direction toward the right side of the wearable display, an actuator accessible from outside the housing of the wearable display, a movable elongate member connected to the actuator and the intermediate frame, a first biasing member connected to the movable elongate member and the intermediate frame and configured to resist movement of the movable elongate member in the direction of travel of the elongate member, a rotatable gear connected to the intermediate frame and disposed between the pair of movable frames, engaging the movable elongate member, having a face, and having a pair of spiral protrusions extending from the face of the rotatable gear, and a pair of second biasing members connected to the rod, the pair of second biasing members being configured to physically bias the pair of movable frames against the pair of spiral protrusions. 14. The wearable display according to clause 13, wherein the actuator comprises a knob movable within a channel defined within the housing of the wearable display. 15. The wearable display according to clause 14, wherein movement of the knob towards the first end of the channel minimizes the distance between the pair of lens assemblies, and movement of the knob towards the second end of the channel maximizes the distance. 16. The wearable display according to clause 13, wherein the actuator is positioned on at least one of the right half or the left half of the wearable display. 17. Each movable frame of the pair of movable frames includes a wing member protruding from the back side of the movable frame, the wing member including an opening, The wearable display according to clause 13, wherein a rod passes through the opening in the wing member of each movable frame. 18. The wearable display according to clause 17, wherein the pair of second biasing members are springs disposed on the rod, and each spring extends between a stop connected to the rod and the corresponding wing member of one of the pair of movable frames. 19. The wearable display according to clause 13, wherein a movable elongate member is connected to the intermediate frame by an anchor extending through a channel defined within the movable elongate member. 20. The wearable display according to clause 13, wherein the first biasing member is a spring connected to the first end of the movable elongate member furthest from the actuator, and the spring is connected to the intermediate frame at a point closer to the actuator than the point where the first end of the movable elongate member is connected to the actuator. 21. A head-mounted display (HMD), a pair of lens barrels connected to the first part of the HMD, an actuator disposed on the first side of the HMD and configured to be actuated by a user of the HMD, A first gear assembly disposed on a first side of the HMD and connected to the actuator, a first portion of the HMD, and a second portion of the HMD, wherein the second portion of the HMD is movable bidirectionally relative to the first portion of the HMD. A second gear assembly disposed on a second side of the HMD opposite to the first side of the HMD and connected to the first portion of the HMD and the second portion of the HMD. A rod connecting the first gear assembly to the second gear assembly. A head-mounted display (HMD) in which the operation of the actuator causes the first portion of the HMD to move in a first direction away from the second portion of the HMD or in a second direction toward the second portion of the HMD. 22. The first gear assembly includes a first elongated member connected to the second portion of the HMD and the actuator, and the first elongated member is movable bidirectionally in the first direction or the second direction. The HMD according to clause 21, wherein the second gear assembly includes a second elongated member connected to the second portion of the HMD, and the second elongated member is movable bidirectionally in the first direction or the second direction. 23. The first gear assembly further includes a first rotatable gear and a second rotatable gear. The first elongated member engages with the first rotatable gear. The first rotatable gear engages with the second rotatable gear. The second rotatable gear is connected to the rod. The second gear assembly further includes a third rotatable gear and a fourth rotatable gear. The third rotatable gear is connected to the rod. The third rotatable gear engages with the fourth rotatable gear. The HMD according to clause 22, wherein the fourth rotatable gear engages with the second elongated member. 24. The first elongated member comprises a first plurality of teeth on a top side surface of the first elongated member, and the first plurality of teeth engage with teeth of a first rotatable gear. The HMD according to clause 22, wherein the second elongated member comprises a second plurality of teeth on a top side surface of the second elongated member, and the second plurality of teeth engage with teeth of a fourth rotatable gear. 25. The HMD according to clause 21, wherein the actuator is a rotatable knob. 26. The rotatable knob is depressible between a first position where the rotatable knob is not depressed and a second position where the rotatable knob is depressed. The rotatable knob is physically biased to the first position by a biasing member. While the rotatable knob is in the first position, a protrusion engages with a detent to prevent the rotatable knob from rotating. The HMD according to clause 25, wherein the rotatable knob is rotatable while in the second position such that the protrusion does not engage with the detent or a different detent. 27. A head-mounted display (HMD) comprising: A pair of lens assemblies coupled to a first portion of the HMD; An actuator disposed on a first side surface of the HMD and accessible from outside the housing of the HMD; A pair of gear assemblies disposed on an opposite side surface of the HMD, connected by a connecting rod, and coupled to a second portion of the HMD that is movable relative to the first portion of the HMD, wherein a gear assembly disposed on the first side surface of the pair of gear assemblies is further coupled to the actuator. 28. A first gear assembly disposed on a first side surface comprises a first elongated member connected to a second portion of the HMD and an actuator, the first elongated member being movable bidirectionally in a first direction from the front of the HMD towards the rear of the HMD or a second direction from the rear of the HMD towards the front of the HMD. The HMD according to clause 27, wherein a second gear assembly comprises a second elongated member connected to a second portion of the HMD, the second elongated member being movable bidirectionally in the first direction or the second direction. 29. The first gear assembly further comprises a first rotatable gear and a second rotatable gear. The first elongated member engages with the first rotatable gear. The first rotatable gear engages with the second rotatable gear. The second rotatable gear is connected to a connecting rod. The second gear assembly further comprises a third rotatable gear and a fourth rotatable gear. The third rotatable gear is connected to the connecting rod. The third rotatable gear engages with the fourth rotatable gear. The HMD according to clause 28, wherein the fourth rotatable gear engages with the second elongated member. 30. The first elongated member comprises a first plurality of teeth on a top side surface of the first elongated member, the first plurality of teeth engaging with teeth of the first rotatable gear. The HMD according to clause 28, wherein the second elongated member comprises a second plurality of teeth on a top side surface of the second elongated member, the second plurality of teeth engaging with teeth of the fourth rotatable gear. 31. The HMD according to clause 27, wherein the actuator is a rotatable knob. 32. The rotatable knob is depressible between a first position where the rotatable knob is not depressed and a second position where the rotatable knob is depressed, and the rotatable knob is physically biased to the first position by a biasing member. The rotatable knob is physically biased to the first position by a biasing member. While the rotatable knob is in the first position, the protrusion engages with the detent to prevent the rotatable knob from rotating, While the rotatable knob is in the second position, the rotatable knob is rotatable such that the protrusion does not engage with the detent or a different detent, the HMD according to clause 31. 33. A wearable display, A pair of lens assemblies coupled to a first portion of the wearable display, A rotatable knob disposed on a first side of the wearable display and accessible from outside the housing of the wearable display, A pair of gear assemblies disposed on the opposite side of the wearable display, connected by a connecting rod, and coupled to a second portion of the wearable display that is movable relative to the first portion of the wearable display, wherein a gear assembly disposed on the first side of the pair of gear assemblies is further coupled to the rotatable knob. 34. The gear assembly disposed on the first side is a first gear assembly comprising a first elongated member coupled to the second portion of the wearable display and the rotatable knob, the first elongated member being movable bidirectionally in a first direction from the front of the wearable display towards the rear of the wearable display or in a second direction from the rear of the wearable display towards the front of the wearable display, The second gear assembly comprises a second elongated member coupled to the second portion of the wearable display, the second elongated member being movable bidirectionally in the first direction or the second direction, the wearable display according to clause 33. 35. The first gear assembly further comprises a first rotatable gear and a second rotatable gear, The first elongated member engages with the first rotatable gear, The first rotatable gear engages with the second rotatable gear, The second rotatable gear is connected to the connecting rod, The second gear assembly further comprises a third rotatable gear and a fourth rotatable gear, The third rotatable gear is connected to the connecting rod, The third rotatable gear engages with the fourth rotatable gear, The wearable display according to clause 34, wherein the fourth rotatable gear engages with the second elongated member. 36. The first elongated member comprises a first plurality of teeth on the top side surface of the first elongated member, and the first plurality of teeth engage with the teeth of the first rotatable gear, The wearable display according to clause 34, wherein the second elongated member comprises a second plurality of teeth on the top side surface of the second elongated member, and the second plurality of teeth engage with the teeth of the fourth rotatable gear. 37. The second part of the wearable display is closer to the user's face when the user is wearing the wearable display, and the first part of the wearable display is farther from the user's face when the user is wearing the wearable display, the wearable display according to clause 33. 38. The rotatable knob is depressible between a first position where the rotatable knob is not depressed and a second position where the rotatable knob is depressed, The wearable display according to clause 33, wherein the rotatable knob is physically biased to the first position by a biasing member. 39. While the rotatable knob is in the first position, the protrusion engages with the detent to prevent the rotatable knob from rotating, The wearable display according to clause 38, wherein while the rotatable knob is in the second position, the rotatable knob is rotatable such that the protrusion does not engage with the detent or a different detent. 40. The wearable display according to clause 33, wherein the distance between the user's face and a pair of lens assemblies is adjustable using a rotatable knob while the user is wearing the wearable display, without the user having to activate any additional actuators. 41. A head-mounted display (HMD) comprising: A housing made of an infrared (IR) transmissive material, wherein the outer surface of the housing is coated with an IR non-transmissive material, and one or more locations on the outer surface are lacking the IR non-transmissive material so as to provide one or more IR transmissive windows on the housing; and One or more IR sensors disposed inside the housing behind one or more of the IR transmissive windows. 42. The HMD according to clause 41, wherein the outer surface is coated with an IR transmissive coating that substantially covers the outer surface lacking the IR non-transmissive material and one or more locations on the outer surface lacking the IR non-transmissive material. 43. The HMD according to clause 41, wherein the thickness of the housing at one or more locations is thinner than the thickness of the remaining portion of the housing. 44. The HMD according to clause 41, wherein one or more IR sensors are mounted on the inner surface of the housing behind one or more locations on the outer surface. 45. The HMD according to clause 41, wherein one or more locations on the outer surface lacking the IR non-transmissive material are circular in shape so as to provide a circular IR transmissive window inside the housing. 45. The HMD according to clause 41, wherein the housing is the housing of the main unit of the HMD, and the housing includes a plurality of IR transmissive windows. 46. The HMD according to clause 45, wherein at least some of the IR transmissive windows are located on the front of the HMD. 47. A method of manufacturing a head-mounted display (HMD) having at least one window that allows electromagnetic radiation of a specific spectrum to pass through at least one window, the method comprising: Forming a housing for an HMD from a first material configured to allow electromagnetic radiation of a specific spectrum to pass therethrough, Coating an outer surface of the housing with a second material configured to block electromagnetic radiation of a specific spectrum, Removing the second material from at least one location on the outer surface, a method comprising. 48. The method according to clause 47, wherein removing the second material comprises laser etching the second material in a direction away from the outer surface. 49. The method according to clause 47, further comprising removing material from an inner surface of the housing behind at least one location on the outer surface to reduce the thickness of the housing at the at least one location. 50. The method according to clause 47, further comprising coating the outer surface with the first material or a third material configured to allow electromagnetic radiation of a specific spectrum to pass therethrough. 51. The method according to clause 47, wherein forming the housing comprises injection molding the housing. 52. The method according to clause 47, further comprising mounting at least one sensor configured to detect electromagnetic radiation of a specific spectrum on an inner surface of the housing behind at least one location on the outer surface. 53. The method according to clause 47, further comprising mounting at least one beacon configured to emit electromagnetic radiation of a specific spectrum on an inner surface of the housing behind at least one location on the outer surface. 54. The method according to clause 47, wherein the specific spectrum is the infrared (IR) spectrum. 55. The method according to clause 54, wherein the first material comprises IR-transparent polycarbonate plastic. 56. A housing made of a spectral transmissive material configured to allow electromagnetic radiation of a specific spectrum to pass through, wherein an outer surface of the housing is coated with a spectral non-transmissive material configured to block electromagnetic radiation of the specific spectrum, and one or more locations on the outer surface are lacking the spectral non-transmissive material so as to provide one or more spectral transmissive windows on the housing. One or more component elements specific to the spectrum disposed inside the housing behind one or more spectral transmissive windows. An electronic device comprising the same. 57. The electronic device according to clause 56, wherein the outer surface is coated with a spectral transmissive coating that substantially covers the spectral non-transmissive material and one or more locations on the outer surface lacking the spectral non-transmissive material. 58. The electronic device according to clause 56, wherein one or more component elements specific to the spectrum are at least one of a sensor that detects electromagnetic radiation of a specific spectrum or a beacon that emits electromagnetic radiation of a specific spectrum. 59. The electronic device according to clause 56, wherein the thickness of the housing at one or more locations is thinner than the thickness of the remaining portion of the housing. 60. The electronic device according to clause 56, wherein the specific spectrum is the infrared (IR) spectrum.

[0063] (Conclusion) Although various examples and embodiments have been described individually herein, the examples and embodiments can be combined, rearranged, and modified to reach other variations within the scope of the present disclosure. Additionally, although the present subject matter has been described in language specific to structural features and / or methodological acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms for implementing the claims. [1] A head-mounted display (HMD), a rod connected to an intermediate frame of the HMD, a first movable frame connected to the rod and a first lens barrel, the first movable frame being movable bidirectionally along the rod, a second movable frame connected to the rod and a second lens barrel, the second movable frame being movable bidirectionally along the rod, an actuator on a bottom of the HMD, the actuator being configured to be actuated by a user of the HMD, a movable elongated member connected to the actuator and the intermediate frame, the movable elongated member being movable bidirectionally in a first direction or a second direction, a first biasing member connected to the movable elongated member and the intermediate frame, the first biasing member being configured to physically bias the movable elongated member in at least one of the first direction or the second direction, a rotatable gear connected to the intermediate frame and disposed between the first movable frame and the second movable frame, the rotatable gear engaging with the movable elongated member, a second biasing member connected to the rod, the second biasing member being configured to physically bias the first movable frame with respect to the rotatable gear, a third biasing member connected to the rod, the third biasing member being configured to physically bias the second movable frame with respect to the rotatable gear, comprising The head-mounted display (HMD) in which the actuation of the actuator causes movement of the movable elongated member in one of the first direction or the second direction, rotates the rotatable gear, and moves the first movable frame and the second movable frame in opposite directions to adjust the distance between the first lens barrel and the second lens barrel. [2] The HMD according to [1], wherein the actuator comprises a knob slidable within a channel defined within the housing of the HMD. [3] The HMD according to [1], wherein the actuator is located on at least one of the right half or the left half of the HMD. [4] The rotatable gear is a first helical protrusion extending from a face of the rotatable gear, and a second helical protrusion extending from the face of the rotatable gear, and the second biasing member is configured to physically bias the first movable frame against the first helical protrusion. The HMD according to [1], wherein the third biasing member is configured to physically bias the second movable frame against the second helical protrusion. [5] The HMD according to [4], wherein the first helical protrusion and the second helical protrusion spiral inwardly from respective points around the rotatable gear to respective points closer to the center of the rotatable gear than the respective points around the periphery. [6] A head-mounted display (HMD) comprising a rod connected to an intermediate frame of the HMD, a pair of lens barrels connected to the rod, each lens barrel being movable bidirectionally along the rod, an actuator accessible from outside the housing of the HMD, a movable elongate member connected to the actuator and the intermediate frame, a first biasing member connected to the movable elongate member and the intermediate frame, the first biasing member being configured to resist movement of the movable elongate member in the direction of travel of the elongate member, a rotatable gear connected to the intermediate frame and disposed between the pair of lens barrels, the rotatable gear engaging the movable elongate member, and a pair of second biasing members connected to the rod, the pair of second biasing members being configured to physically bias the pair of lens barrels toward the rotatable gear. [7] The HMD according to [6], wherein the actuator comprises a knob slidable within a channel defined within the housing of the HMD. [8] The HMD according to [6], wherein the actuator is located on at least one of the right half or the left half of the HMD. [9] The pair of lens barrels is connected to the rod via a pair of movable frames. The rotatable gear includes a pair of spiral protrusions extending from the face of the rotatable gear. The HMD according to [6], wherein the pair of second biasing members is configured to physically bias the pair of lens barrels toward the rotatable gear by physically biasing the pair of movable frames against the pair of spiral protrusions.

[10] Each movable frame of the pair of movable frames includes a wing member protruding from the back side of the movable frame, and the wing member includes an opening. The HMD according to [9], wherein the rod passes through the opening in the wing member of each movable frame.

[11] The HMD according to

[10] , wherein the pair of second biasing members are springs disposed on the rod, and each spring extends between a stop portion connected to the rod and the corresponding one of the wing members of the pair of movable frames.

[12] The HMD according to [6], wherein the movable elongated member is connected to the intermediate frame by an anchor extending through a channel defined within the movable elongated member.

[13] A wearable display, A rod connected to an intermediate frame of the wearable display, A pair of lens assemblies connected to the rod and movable bidirectionally along the rod, An actuator accessible from the outside of the housing of the wearable display, A movable elongated member connected to the actuator and the intermediate frame, A first biasing member connected to the movable elongated member and the intermediate frame, the first biasing member being configured to resist movement of the movable elongated member in the direction of travel of the elongated member. A rotatable gear connected to the intermediate frame and disposed between the pair of lens assemblies, the rotatable gear engaging the movable elongated member. A wearable display, comprising a pair of second biasing members coupled to the rod, wherein the pair of second biasing members are configured to physically bias the pair of lens assemblies toward the rotatable gear.

[14] The wearable display according to

[13] , wherein the actuator comprises a knob movable within a channel defined within the housing of the wearable display.

[15] The wearable display according to

[14] , wherein movement of the knob to a first end of the channel minimizes the spacing between the pair of lens assemblies, and movement of the knob to a second end of the channel maximizes the spacing.

[16] The wearable display according to

[13] , wherein the actuator is located on at least one of the right half or the left half of the wearable display.

[17] The pair of lens assemblies are coupled to the rod via a pair of movable frames, each movable frame of the pair of movable frames including a wing member protruding from the back side of the movable frame, the wing member including an opening. The wearable display according to

[13] , wherein the rod passes through the opening within the wing member of each movable frame.

[18] The wearable display according to

[17] , wherein the pair of second biasing members are springs disposed on the rod, each spring extending between a stop coupled to the rod and the corresponding one of the wing members of the pair of movable frames.

[19] The pair of lens assemblies are coupled to the rod via a pair of movable frames. The rotatable gear comprises a pair of helical protrusions extending from the face of the rotatable gear. The wearable display according to

[13] , wherein the pair of second biasing members are configured to physically bias the pair of lens assemblies toward the rotatable gear by physically biasing the pair of movable frames against the pair of helical protrusions.

[20] The first biasing member is a spring connected to a first end of the movable elongated member farthest from the actuator, and the spring is connected to the intermediate frame at a point closer to the actuator than a point where the first end of the movable elongated member is connected to the actuator, the wearable display according to

[13] .

Claims

1. A head mounted display (HMD), a housing made of an infrared (IR) transparent material, an exterior surface of the housing being coated with an IR non-transparent material, one or more locations on the exterior surface being devoid of the IR non-transparent material to provide one or more IR transparent windows on the housing; and one or more IR sensors disposed inside the housing directly behind the one or more IR transmissive windows.

2. The HMD of claim 1 , wherein the exterior surface is coated with an IR transparent coating that substantially covers the IR non-transparent material and the one or more locations.

3. The HMD of claim 1 , wherein the thickness of the housing at the one or more locations is less than the thickness of the remainder of the housing.

4. The HMD of claim 1 , wherein the one or more IR sensors are mounted on an inner surface of the housing behind the one or more locations.

5. The HMD of claim 1 , wherein the one or more locations are circular in shape so as to provide one or more circular IR-transparent windows within the housing.

6. The HMD of claim 1 , wherein the one or more IR-transparent windows include a plurality of IR-transparent windows.

7. The HMD of claim 6 , wherein at least some of the plurality of IR-transmissive windows are located on a front of the HMD.

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