Patent Application
20230358920
This relates generally to electronic devices, and, more particularly, to electronic devices with displays and lenses.
Electronic devices such as head-mounted devices may have displays for displaying images. The displays may be housed in optical modules. Lenses may be mounted in the optical modules. Using the lenses, a user may view displayed images.
A head-mounted device may have optical modules or other support structures with displays that present images to a user's left and right eyes. Each optical module may have a lens support structure that supports a respective display and fixed lens. Vision correction lenses may be removably coupled to the fixed lenses to accommodate a user's vision.
During operation, a user may view images on the displays through the vision correction lenses and the fixed lenses from eye boxes. The optical modules may include infrared light sources that supply infrared light to the eye boxes and infrared light sensors such as infrared cameras. The infrared components may be used for gaze tracking and authentication.
The lenses of the head-mounted device may have optical surfaces covered with coatings that enhance optical performance such as antireflection coatings and other coating layers. The lenses may also have edge surfaces with structures that help reduce stray light reflections. The lenses may be configured to pass visible light associated with the displays and to pass infrared light associated with the infrared light sources and infrared cameras.
An electronic device such as a head-mounted device may have a head-mounted support structure that supports lenses, displays and other components. During operation, the head-mounted device may display visual content for a user such as virtual reality content or augmented reality content.
The head-mounted support structure may be configure to form a pair of glasses, a pair of goggles, a helmet, or other head-mounted device. Illustrative configurations in which the head-mounted device is a pair of goggles may sometimes be described herein as an example.
The head-mounted support structure may have a front face that faces away from a user's head and may have an opposing rear face that faces the user's head. Optical modules on the rear face may be used to provide images to a user's eyes. Each optical module may have a lens barrel in which a fixed lens is mounted. Optional removable supplemental lenses may be coupled to the optical modules. The supplemental lenses, which may sometimes be referred to as vision correction lenses may be used to correct for a user's vision defects such as near-sightedness, far-sightedness, and astigmatism.
To ensure satisfactory operation of the head-mounted device, the vision correction lenses (and, if desired, the fixed lenses) may be provided with coatings and other structures that help reduce stray light and provide the lenses with a desired mechanical robustness while ensuring that the lenses exhibit desired amounts of light transmission over all operating wavelengths.
A top view of an illustrative head-mounted device is shown in
Main housing portion 12M may include housing structures formed from metal, polymer, glass, ceramic, and/or other material. For example, housing portion 12M may have housing walls on front face F and housing walls on adjacent top, bottom, left, and right side faces that are formed from rigid polymer or other rigid support structures and these rigid walls may optionally be covered with electrical components, glass, metal, fabric, leather, or other materials. The walls of housing portion 12M may enclose internal components 38 in interior region 34 of device 10 and may separate interior region 34 from the environment surrounding device 10 (exterior region 36). Internal components 38 may include integrated circuits, actuators, batteries, sensors, control circuitry, and/or other circuits and structures for device 10. These components may include sensors such as image sensors, ambient light sensors, touch sensors, force sensors, orientation sensors (e.g., orientation sensors based on accelerometers, compasses, and/or gyroscopes such as orientation sensors based on inertial measurement units containing some or all of these components), proximity sensors, capacitive sensors, optical sensors, three-dimensional image sensors such as structured light sensors and/or three-dimensional sensors based on stereoscopic pairs of two-dimensional image sensors, gaze tracking sensors, hand sensors, sensors for monitoring the movement and position of accessories such as controllers, microphones for gathering voice commands and measuring ambient noise, temperature sensors, fingerprint sensors and other biometric sensors, and/or other sensing circuitry.
Front face F of housing 12 may face outwardly away from a user's head and face. Opposing rear face R of housing 12 may face the user. Portions of housing 12 (e.g., portions of main housing 12M) on rear face R may form a cover such as cover 12C (sometimes referred to as a curtain). The presence of cover 12C on rear face R may help hide internal housing structures, internal components 38, and other structures in interior region 34 from view by a user.
Device 10 may have left and right optical modules 40. A left optical module and associated left eye box 13 are shown in the left portion of device 10 of
Lenses 30 may be fixedly mounted to support structures 32. Additional vision correction lens modules 54 may be fixedly or removably coupled to modules 40 (e.g., to form a left lens that is corrected for the user's left eye vision and a right lens that is corrected for the user's right eye vision).
Vision correction lens modules 54 may each have one or more vision correction lens elements (sometimes referred to as vision correction lenses or lens substrates) mounted in a vision correction lens housing such as housing 50. As shown in
Each housing 50, which may sometimes be referred to as a lens mount or vision correction lens support structure may be formed from a ring of polymer, metal, and/or other materials. An opening in the center of housing 50 may accommodate lens element 54. One or more magnets 56 or other attachment structures (e.g., press-fit connections, fasteners, etc.) may be mounted in housing 50 and may be mounted in corresponding portions of support structure 32 of module 40 to allow vision correction lens 52 to be removably attached to module 40. This type of arrangement may allow different users to install different vision correction lenses.
Displays 14 may include arrays of pixels or other display devices to produce images. Displays 14 may, for example, include organic light-emitting diode pixels formed on substrates with thin-film circuitry and/or formed on semiconductor substrates, pixels formed from crystalline semiconductor dies, liquid crystal display pixels, scanning display devices, and/or other display devices for producing images.
Lenses 30, which may sometimes be referred to as fixed lenses, may include one or more lens elements and may be used in conjunction with respective overlapping vision correction lenses 52 to provide image light from displays 14 to respective eyes boxes 13. Lenses for device 10 (e.g., lenses 30) may be implemented using refractive lens elements, using mirror lens structures (catadioptric lenses), using Fresnel lenses, using holographic lenses, and/or other lens systems. Removable lenses 52 may likewise be formed from such lens elements (e.g., refractive lens elements).
When a user's eyes are located in eye boxes 13, displays (display panels) 14 operate together to form a display for device 10 (e.g., the images provided by respective left and right optical modules 40 may be viewed by the user's eyes in eye boxes 13 so that a stereoscopic image is created for the user). The left image from the left optical module fuses with the right image from a right optical module while the display is viewed by the user.
It may be desirable to monitor the user's eyes while the user's eyes are located in eye boxes 13. For example, it may be desirable to use a camera to capture images of the user's irises (or other portions of the user's eyes) for user authentication. It may also be desirable to monitor the direction of the user's gaze. Gaze tracking information may be used as a form of user input and/or may be used to determine where, within an image, image content resolution should be locally enhanced in a foveated imaging system. To ensure that device 10 can capture satisfactory eye images while a user's eyes are located in eye boxes 13, each optical module 40 may be provided with a camera such as camera 42 and one or more light sources such as light sources 44 (e.g., light-emitting diodes, lasers, etc.).
Cameras 42 and light sources 44 may operate at any suitable wavelengths (visible, infrared, and/or ultraviolet). With an illustrative configuration, which may sometimes be described herein as an example, light sources 44 emit infrared light that is invisible (or nearly invisible) to the user. The emitted light may, as an example, be near infrared light at a wavelength of 740 nm to 1000 nm, 940 nm, 850 nm to 1000 nm, or other suitable near infrared wavelength. This allows eye monitoring operations to be performed continuously without interfering with the user's ability to view images on displays 14. Light sources 44 may, for example, include multiple light-emitting diodes or lasers arranged in a ring around the periphery of support structure 32. During operation, emitted infrared light from light sources 44 may pass through lenses 30 and 52 to illuminate the user's eyes (e.g., as flood illumination and/or glints) and cameras 42 may capture infrared images of the user's illuminated eyes through lenses 30 and 52.
Not all users have the same interpupillary distance. To provide device 10 with the ability to adjust the interpupillary spacing between modules 40 along lateral dimension X and thereby adjust the spacing between left and right eye boxes 13 to accommodate different user interpupillary distances, device 10 may be provided with actuators 43 (e.g., left and right actuators or a common actuator that adjusts the position of both left and right optical modules). Actuators 43 can be manually controlled and/or actuators 43 may be computer-controlled actuators (e.g., computer-controlled motors) that are used to move support structures 32 relative to each other. Information on the locations of the user's eyes may be gathered using, for example, cameras 42. The locations of eye boxes 13 can then be adjusted accordingly.
Device 10 of
Vision-correction lenses 52 (and, if desired, fixed lenses 30) may have coatings and/or other surface treatments that help reduce stray light reflections and enhance light transmission. Coatings for lenses 52 may include one or more deposited layers of material that provide the lenses with desired mechanical and optical properties.
A cross-sectional side view of an illustrative vision correction lens with optional coating layers is shown in
One or more lens coatings such as illustrative coating layers 64, 66, and 68 of
Lens coatings for lens 52 may include, for example, anti-scratch layers (sometimes referred to as hard coats), anti-smudge layers, anti-fog layers, antireflection layers, anti-static layers, adhesion layers, anti-viral and/or anti-bacterial layers, and/or other coatings. In some configurations, each of these functions may be implemented using a separate respective coating layer. In other configurations, a single layer may serve multiple functions. For example, a layer of material may serve as both an anti-viral layer and as an anti-bacterial layer. As another example, an antireflection coating may include an antistatic layer. Coatings may be formed on the inwardly facing surface of lens 52 and/or on the outer surface of lens 52 (e.g., the surface of lens 52 that faces eye boxes 13 at the rear of device 10). Illustrative configurations in which coatings are provided symmetrically to both the inner and outer surfaces of lens 52 may sometimes be described herein as an example.
Coatings may be provided in any suitable order. As one example, coating 64 may be a hard coat that helps prevent scratches that could damage lens 54, layer 66 may be an antireflection coating (e.g., an antireflection coating containing a stack of sublayers), and layer 68 may be an anti-smudge coating or anti-fog coating. Antistatic layers, anti-viral layers, and anti-bacterial layers may be incorporated into one or more of the coatings of
Substrate 60 may be formed from polymer, glass, crystalline material such as sapphire, and/or other materials. In an illustrative configuration, lens 52 operates at visible light wavelengths (e.g., wavelengths from 380-740 nm) and near-infrared wavelengths (e.g., wavelengths from 740 nm to 800 nm, 740-900 nm, 740-1000 nm, 740-1200 nm, infrared light wavelengths less than 1100 nm, less than 1000 nm, or other suitable infrared wavelengths associated with operation of light sources 44 and camera 42 range). This allows a user to view visible light images produced by displays 14 and allows infrared optical components such as gaze tracking systems, iris scanning systems, and/or other infrared components based on light sources 44 and cameras 42 to operate satisfactorily using light that is invisible to the eye of the user. Polymer, glass, and/or sapphire or other crystalline materials that are transparent at these visible and infrared wavelengths may be used in forming substrate 60. Materials such as glass and sapphire or other crystalline materials may have refractive index values that are larger than for polymers, which may make the use of these materials satisfactory in scenarios in which the ability to reduce lens size is desired. For example, sapphire may have a refractive index of 1.75 at visible light wavelengths. Glass may have a refractive index value of 1.5-1.65. Some polymers may have refractive index values of 1.5-1.6. Materials such as glass and sapphire may provide enhanced durability. The use of polymer in lenses 52 may help reduce weight. High-index polymers (e.g., cyclic olefin copolymer or polycarbonate) and/or polymer with embedded nanostructures (e.g., inorganic particles having particles of subwavelength diameter) may be used, if desired.
A hard coat on lenses 54 may help enhance durability. The hard coat may have a thickness of 5 nm to 5 microns, less than 2 microns, less than 1 micron, or other suitable thickness. A wet hard coat, a hard coat based on a durable inorganic dielectric such as silicon oxide, a hard coat of diamond-like carbon, or other hard coat may be used (as examples). In an illustrative configuration, a hard coat may be formed from a material such as aluminum oxynitride.
The refractive index of the hard coat may be matched (e.g., within +/−0.1, within +/−0.05, or other suitable refractive index difference) to the refractive index of substrate 60 to help avoid undesired reflections at the interface between substrate 60 and the hard coat. If desired, hard coats may be applied by a physical vapor deposition process such as evaporation or sputtering. The use of sputter deposited hard coats may help enhance scratch resistance. In some configurations, hard coat layers may serve as one of the thin-film layers in a thin-film interference filter configured to form an antireflection coating (e.g., antireflection coating layer 66 of
Antireflection coatings for lenses 54 may be formed from moth-eye structures, single-layer coatings, graded-index coatings, or coatings formed from thin-film interference filters. A single layer antireflection coating may have a refractive index value that lies between that of the lens substrate and surrounding air or other suitable refractive index value to help reduce reflections. A graded-index coating may have a composition that changes smoothly so as to produce a corresponding smoothly varying value of refractive index from one side of the coating to the other (e.g., a value that monotonically varies between a first composition that is entirely or mostly composed of a higher index material to a second composition that is entirely or mostly composed of a lower index material).
A moth-eye coating antireflection coating may have an array of nanostructures (e.g., nanostructures with subwavelength dimensions such as vertical and/or lateral dimensions of less than 300 nm, less than 250 nm, or other subwavelength size). The nanostructures may form an array of tapered nanoscale protrusions. A moth-eye coating may, for example, have an array of protrusions such as an array of pyramidal structures (e.g., an array of pyramids), an array of hemispheres (e.g., an array of hemispherical protrusions), an array of hexagonally sided protrusions, and/or other nano-sized protrusions. These moth-eye nanostructures create a graded index structure that helps to reduce reflections. Nano-imprinting techniques (e.g., roller embossing), photolithography, laser processing, and/or other fabrication techniques may be used in forming moth-eye coating layers. Antireflection coatings formed from moth-eye structures may have broadband antireflection characteristics (e.g., a moth-eye coating may help reduce reflections over visible wavelengths, near infrared wavelengths, and, if desired other wavelengths). In general, any suitable techniques may be used in forming moth eye structures. For example, moth-eye antireflection coatings may be produced in situ on a lens substrate, moth-eye structures may be formed using a film with moth-eye structures that is laminated to a lens substrate, etc. If desired, moth-eye structures can be covered with other layers and/or may be formed on top of other layers (e.g., anti-smudge, anti-fog, anti-static, anti-viral, and/or anti-bacterial layers).
A thin-film interference filter antireflection coatings may be formed from a stack of organic and/or inorganic dielectric layers (and, in some configurations, other layers such as semiconductor and/or metal layers). The dielectric layers in the stack of dielectric layers may, as an example, have alternating refractive index values (e.g., layers with higher refractive index values may alternate with layers with lower refractive index values). The thicknesses of the dielectric layers, the refractive indices of the dielectric layers, and the number of dielectric layers in the antireflection coating may be configured to provide the antireflection coating and lens with a desired optical characteristics (e.g., absorption, reflection, and transmission as a function of wavelength).
As an example, it may be desirable to ensure that visible and infrared light reflectivity for lenses 52 is relatively low, as this allows the user of device 10 to view images on displays 14 without undesired visible light reflections from the surfaces of lenses 52 and helps to reduce undesired infrared light reflections from the surfaces of lenses 52 associated with the operation of infrared components such as light sources 44 and cameras 42.
If desired, the reflection spectrum of the antireflection coatings on lenses 52 may be configured to impart a desired non-neutral color to lenses 52. For example, the reflection spectrum of the antireflection coating (and/or other layers of material on lenses 52) can be configured to make lenses 52 appear pinkish, bluish, purplish, or to exhibit other non-neutral color casts while ensuring sufficiently low reflectivity for lenses 52 at operating wavelengths.
In some configurations, antireflection coatings for lenses 52 may be formed from layers of inorganic dielectric such as alumina, zirconia, titania, other metal oxides, silica, silicon-nitride-based materials, etc. Dielectric layers for the antireflection coating may be deposited by physical vapor deposition processes (e.g., evaporation or sputtering). The use of sputter-deposited dielectric layers may help enhance coating durability. Diamond-like carbon (e.g., amorphous carbon layers that exhibit diamond-like properties such as elevated hardness) may be used in forming one or more antireflection coating layers or other dielectric coating layers such as hard coat layers (e.g., to provide the antireflection coating and/or other layers on lenses 52 with scratch resistance). If desired, polymer coating layers for the antireflection coating may be deposited by dipping, spraying, printing, and/or other deposition techniques. In some configurations, antireflection coatings for lenses 52 may contain one or more sol-gel layers (e.g., a sol-gel coating having inorganic nanoparticles in a polymer). If desired, a coating may be formed from a polymer that contains suspended inorganic particles. For example, metal oxide particles may be embedded in a binder of polyacrylic or other clear polymer to help enhance the refractive index of the binder.
An antistatic layer may be incorporated into an antireflection coating (e.g., as one of the layers in a stack of transparent layers of alternating refractive index that form a thin-film interference filter antireflection coating) and/or may be deposited as a layer that is separate from the antireflection coating. The antistatic layer may be formed from a transparent conductive material that dissipates electric charge such as a layer of transparent semiconductor (e.g., indium tin oxide).
Anti-smudge coatings (e.g., hydrophobic polymer coatings) may be formed on lens 52 to help reduce fingerprints and other undesired marks on the surfaces of lens 52 when lens 52 is handled. An example of an anti-smudge coating is a fluoropolymer coating (e.g., a fluoropolymer formed from evaporated perfluoropolyether) that serves as an oleophobic layer. Fluoropolymers can be adhered to underlying coating layers using an intervening adhesion layer. In an illustrative configuration, a silicon oxide layer may serve as the adhesion layer and an optional NaF catalyst layer may be used to help chemically bond the fluoropolymer to the silicon oxide layer. Depositing NaF catalyzed fluoropolymer in this way may help ensure satisfactory adhesion of the anti-smudge coating.
The coatings on lenses 52 may include antifog layers. Antifog layers may be formed form hydrophilic materials such as hydrophilic polymers (as an example). In some configurations, the coatings on lenses 52 may include layers that serve as antivirus and/or antibacterial layers. For example, layer 68 of
Light rays that reflect from the peripheral edges of lenses 52 may degrade contrast and/or otherwise adversely affect optical performance. As shown in
In an illustrative configuration, stray light rays produced at lens edge surfaces such as edge surface 76 can be reduced or eliminated by incorporating opaque masking structures such as masking rings 78 around the periphery of lens 52. Masking rings 78 may have central openings through which light rays 80 may pass without scattering from edge surface 76. Rings 78 may be formed from opaque polymer (e.g., part of housing 50 of
If desired, undesired light reflections from edge surfaces 76 of lenses 52 can be reduced by coating, roughening, and/or otherwise configuring edge surfaces 76 to scatter and/or absorb light. Consider, as an example, the illustrative arrangement of
Another illustrative configuration for reducing edge surface light reflections involves texturing edge surface 76. Etching, sandblasting, machining techniques, and/or other edge surface treatments may be used to create protrusions of varying height (see, e.g., short protrusion 90 and tall protrusion 92 on edge surface 76 of lens 52 in
In the illustrative configuration of
In the example of
If desired, layer 96 or other coating layer on lens edge surface 76 may have a graded refractive index of the type shown in
A graded-index layer may include additives such as additive 86 so that the graded-index layer absorbs visible and/or infrared light (e.g., light at wavelengths VIS and/or IR), may be interposed between lens 52 and an overlapping coating (see, e.g., coating 98, which may be a light absorbing coating such as a polymer layer or other layer that includes light-absorbing additives such as additive 86), and/or may cover a surface such as textured surface 76 of
In an illustrative configuration, the edge surface of lens 52 includes an optional light-scattering structure (e.g., an edge surface texture of the type shown in
If desired, lens 52 may have one or more light-blocking rings such as light-blocking rings 78 of
If desired, moth-eye structures may be formed on the optical surfaces of lens 52. Consider, as an example, the arrangement of
In accordance with an embodiment, a head-mounted device lens module is provided that includes a support structure; a display coupled to the support structure; a lens through which the display is visible from an eye box; an infrared light source configured to emit infrared light through the lens towards the eye box; and an infrared camera configured to capture an image from the eye box through the lens, the lens includes opposing first and second optical surfaces and an edge surface that extends between the first and second optical surfaces and the lens includes a light-absorbing coating on the edge surface.
In accordance with another embodiment, the lens has a lens substrate, the head-mounted device lens module includes an antireflection coating on the first and second optical surfaces that is configured so that the lens exhibits less than 2.5% reflectivity from 380 nm to 1000 nm; a hard coat between the antireflection layer and the lens substrate; and a fluoropolymer layer on the antireflection coating.
In accordance with another embodiment, the light-absorbing coating includes polymer with a light-absorbing additive configured to absorb visible light and infrared light.
In accordance with another embodiment, the light-absorbing coating has a first refractive index, the lens has a substrate with a second refractive index, and the first and second refractive indices differ by less than 0.1.
In accordance with another embodiment, the light-absorbing additive includes pigment.
In accordance with another embodiment, the light-absorbing additive includes dye.
In accordance with another embodiment, the head-mounted device lens module includes an antireflection coating on the edge surface that is overlapped by the light-absorbing coating.
In accordance with another embodiment, the antireflection coating includes a stack of thin-film dielectric layers.
In accordance with another embodiment, the antireflection coating includes a moth-eye coating.
In accordance with another embodiment, the antireflection coating includes a dielectric layer characterized by a graded refractive index.
In accordance with another embodiment, the head-mounted device lens module includes an anti-viral layer on the first and second optical surfaces.
In accordance with another embodiment, the head-mounted device lens module includes an anti-fog layer on the first and second optical surfaces
In accordance with another embodiment, the head-mounted device lens module includes an anti-bacterial layer on the first and second optical surfaces.
In accordance with another embodiment, the head-mounted device lens module includes a hard coat on the first and second optical surfaces; an antireflection layer on the hard coat; and an anti-smudge layer on the antireflection layer.
In accordance with another embodiment, the antireflection layer includes a thin-film interference filter antireflection layer.
In accordance with another embodiment, the antireflection layer includes a graded index layer.
In accordance with another embodiment, the antireflection layer includes a moth-eye coating.
In accordance with another embodiment, the head-mounted device lens module includes an antistatic layer on the first and second optical surfaces.
In accordance with another embodiment, the head-mounted device lens module includes first and second opaque masking rings respectively on the first and second optical surfaces.
In accordance with another embodiment, the edge surface has protrusions of different sizes that form a light-scattering texture on the edge surface.
In accordance with another embodiment, the lens includes a lens substrate including a material selected from the group consisting of: sapphire and glass and the lens includes a sputtered hard coat on the first and second optical surfaces.
In accordance with another embodiment, the head-mounted device lens module includes a NaF catalyzed polymer anti-smudge coating on the first and second optical surfaces.
In accordance with another embodiment, the head-mounted device lens module includes a thin-film interference filter antireflection coating on the first and second optical surfaces that is configured to suppress reflections at visible and infrared wavelengths while imparting a non-neutral color to the lens.
In accordance with another embodiment, the lens includes a fixed lens and a removable vision correction lens that is removably coupled to the fixed lens and the first and second optical surfaces and the edge surface are on the removable vision correction lens.
In accordance with an embodiment, a vision-correction lens configured to removably couple to a head-mounted device in alignment with a fixed lens that overlaps a display, an infrared light source, and an infrared camera, the vision-correction lens is provided that includes
In accordance with another embodiment, the vision-correction lens includes a light-reflection-reduction structure on the edge surface.
In accordance with another embodiment, the light-reflection-reduction structure includes a coating configured to absorb the visible and infrared light.
In accordance with another embodiment, the light-reflection-reduction structure includes irregular protrusions on the edge surface that are configured to scatter light.
In accordance with another embodiment, the lens substrate has a lens substrate refractive index and the light-reflection-reduction structure has a refractive index that is within 0.1 of the lens substrate refractive index.
In accordance with another embodiment, the vision-correction lens includes first and second opaque masking rings respectively on the first and second optical surfaces.
In accordance with an embodiment, a head-mounted device is provided that includes a head-mounted support structure; left and right optical modules on the head-mounted support structure each of which has a display, a fixed lens through which the display of that module is visible from an eye box and an infrared light source that emits light through the fixed lens; and left and right removable vision correction lenses that are removably coupled to the fixed lenses of the left and right optical modules, respectively, each removable vision-correction lens includes a lens substrate with optical surfaces and an edge surface; a light-reflection-reduction coating on the edge surface; a hard coat on the optical surfaces; a thin-film interference filter antireflection coating on the hard coat; and a fluoropolymer coating on the thin-film interference filter antireflection coating.
In accordance with another embodiment, the thin-film interference filter antireflection coating of each removable vision-correction lens is configured to pass visible light from the display and infrared light from the infrared light source and is configured to impart a non-neutral color to the vision correction lens.
The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.
This application is a continuation of international patent application No. PCT/US2021/057732, filed Nov. 2, 2021, which claims priority to U.S. provisional patent application No. 63/120,648, filed Dec. 2, 2020, which are hereby incorporated by reference herein in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 63120648 | Dec 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2021/057732 | Nov 2021 | US |
| Child | 18324078 | US |
