Patent Description:
A smart device is an electronic device that typically communicates with other devices or networks. In some situations the smart device may be configured to operate interactively with a user. A smart device may be designed to support a variety of form factors, such as a head mounted device, a head mounted display (HMD), or a smart display, just to name a few.

Smart devices may include one or more electronic components for use in a variety of applications, such as gaming, aviation, engineering, medicine, entertainment, video/audio chat, activity tracking, and so on. In some examples, a smart device, such as a head-mounted device or HMD, may include a display that can present data, information, images, or other virtual graphics while simultaneously allowing the user to view the real world.

<CIT> describes a device including an electronic display configured to generate an augmented reality image element and an optical combiner configured to receive the augmented reality image element along with ambient light from outside the device. The optical combiner is configured to provide an augmented reality image having the augmented reality image element located within a portion of an ambient image formed from the ambient light. The device also includes a dimmer element configured to selectively dim the portion of the ambient image in which the augmented reality image element is located.

<CIT> describes an optical device that includes variable optical material that alters at least one of: incident ambient light, spectral content of incident ambient light or direction of incident ambient light through the optical device in response to a stimulus provided by the device. The device can sense intensity and/or spectral characteristics of ambient light and provide appropriate stimulus to various portions of the optical device to activate the variable optical material and alter at least one of: incident ambient light, spectral content of incident ambient light or direction of incident ambient light.

<CIT> describes a subtractive augmented reality display system including one or more light emitting displays, an optical system with which the user can view the ambient scene and the light emitted from the display(s) and a material in the way of the user's line of sight to the ambient scene which changes color, darkens or lightens based on interaction with light from the display system.

<CIT> describes a head-mounted device having a transparent display. The transparent display may be formed from a display unit that provides images to a user through an optical coupler. A user may view real-world objects through the optical coupler while control circuitry directs the transparent display to display computer-generated content over selected portions of the real-world objects. The head-mounted display may also include an adjustable opacity system. The adjustable opacity system may include an adjustable opacity layer such as a photochromic layer that overlaps the optical coupler and a light source that selectively exposes the adjustable opacity layer to ultraviolet light to control the opacity of the adjustable opacity layer. The adjustable opacity layer may block or dim light from the real-world objects to allow improved contrast when displaying computer-generated content over the real-world objects.

The scope of the present invention is set out in the claims appended hereto.

Examples of the present disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. <FIG> illustrates an arrangement according to the present invention. The remaining figures illustrate example arrangements useful to understanding the background to the invention.

Various examples are disclosed in the following description and related drawings to show specific examples relating to the local dimming provided by a head-mounted device. Well-known elements will not be described in detail or may be omitted so as to not obscure the relevant details of the examples disclosed herein.

In some implementations of the disclosure, the term "near-eye" may be defined as including an element that is configured to be placed within <NUM> of an eye of a user while a near-eye device is being utilized. Therefore, a "near-eye optical element" or a "near-eye system" would include one or more elements configured to be placed within <NUM> of the eye of the user.

In aspects of this disclosure, visible light may be defined as having a wavelength range of approximately <NUM> - <NUM>. Non-visible light may be defined as light having wavelengths that are outside the visible light range, such as ultraviolet light and infrared light. Infrared light having a wavelength range of approximately <NUM> - <NUM> includes near-infrared light. In aspects of this disclosure, near-infrared light may be defined as having a wavelength range of approximately <NUM> - <NUM>. Violet light may include light having a wavelength in the range of approximately <NUM>-<NUM>.

As mentioned above, a head-mounted device may include a display that is configured to present data, information, images, or other virtual graphics while simultaneously allowing the user to view the real world. However, the virtual graphics may be difficult for the user to view if the environment is too bright, if there is insufficient contrast between the virtual graphics and the user's current view of the real world, if a color of the virtual graphic matches the color of the real world behind the virtual graphic, or some combination thereof. By way of example, <FIG> illustrates a user's view of a real-world scene <NUM> through an optical assembly <NUM> of a head-mounted device. As shown in <FIG>, the optical assembly <NUM> allows the user to view the real-world scene <NUM> while simultaneously presenting a virtual graphic <NUM> to the user. In the illustrated example, virtual graphic <NUM> is an icon, but in other examples, the virtual graphic <NUM> may include text, a picture, video, or other visual information that is generated by the optical assembly <NUM> for presentation to the user. However, as shown in <FIG> the virtual graphic <NUM> is positioned on the optical assembly <NUM> at the same location as the user's view of a real-world object <NUM> (e.g., illustrated as a shrub/bush in <FIG>). In some examples, the real-world object <NUM> may interfere with the user's visibility of the virtual graphic <NUM>. That is, the real-world object <NUM> may be the same or similar color as the virtual graphic <NUM>, and/or the contrast between the real-world object <NUM> and the virtual graphic <NUM> may be too low. Thus, in some conditions, the virtual graphic <NUM> may be difficult for the user to discern when it is co-located with the user's view of the real-world object <NUM>.

Accordingly, aspects of the present disclosure provide for the local dimming of light received from the real-world scene <NUM> to increase the visibility of the virtual graphic <NUM>. For example, <FIG> illustrates the darkening of a region <NUM> that is provided by the optical assembly <NUM>. As shown, the region <NUM> is darkened by the optical assembly <NUM> to dim or occlude light received from the real-world scene <NUM> at a location that corresponds to the real-world object <NUM> and the virtual graphic <NUM>. In some examples, "local dimming" refers to dimming only a portion of the field-of-view provided by the optical assembly <NUM> (e.g., less than the entire field-of-view). <FIG> illustrates the virtual graphic <NUM> as being unchanged with respect to the view shown in <FIG>, but the virtual graphic <NUM> may have increased visibility due to the dimming of the real-world object <NUM> provided by the darkening of region <NUM>.

The dimming provided by the optical assembly <NUM> may be provided by a dimming layer of the optical assembly <NUM> that includes a photochromic material that darkens in response to exposure to a range of light wavelengths. In some aspects, when activated, the photochromic material may undergo a reversible photochemical reaction that results in a change in its visible light absorption, in strength and/or wavelength.

In some examples, the darkening of a region of the dimming layer, such as region <NUM>, is activated by way of one or more in-field dimmers that are included within the optical assembly <NUM>. The in-field dimmer may include a waveguide, an extraction feature, a diffraction grating, and the like, that is incorporated within the optical assembly <NUM>, where the in-field dimmer is configured to selectively emit an activation light to activate the darkening of the photochromic material corresponding to a particular region of the optical assembly <NUM>.

In other examples, the darkening of the region <NUM> may be activated by a digital projector that is incorporated into the head-mounted device. For example, a digital projector may be mounted to a frame and/or temple arms of a head-mounted device to selectively emit an activation light to a particular region of the optical assembly <NUM> to activate the darkening of the photochromic material. These and other examples will be discussed in more detail below.

<FIG> illustrates an example head-mounted device <NUM>, in accordance with aspects of the present disclosure. A head-mounted device, such as head-mounted device <NUM>, is one type of smart device, typically worn on the head of a user to provide artificial reality content to a user. Artificial reality is a form of reality that has been adjusted in some manner before presentation to the user, which may include, e.g., virtual reality (VR), augmented reality (AR), mixed reality (MR), hybrid reality, or some combination and/or derivative thereof.

The illustrated example of head-mounted device <NUM> is shown as including a frame <NUM>, temple arms 204A and 204B, and a near-eye optical assembly 206A and a near-eye optical assembly 206B. <FIG> also illustrates an exploded view of an example of near-eye optical assembly 206A. Near-eye optical assembly 206A is shown as including a display layer <NUM>, an activation layer <NUM>, and a dimming layer <NUM>.

As shown in <FIG>, frame <NUM> is coupled to temple arms 204A and 204B for securing the head-mounted device <NUM> to the head of a user. Example head-mounted device <NUM> may also include supporting hardware incorporated into the frame <NUM> and/or temple arms 204A and 204B. The hardware of head-mounted device <NUM> may include any of processing logic, wired and/or wireless data interfaces for sending and receiving data, graphic processors, and one or more memories for storing data and computer-executable instructions. In one example, head-mounted device <NUM> may be configured to receive wired power and/or may be configured to be powered by one or more batteries. In addition, head-mounted device <NUM> may be configured to receive wired and/or wireless data including video data.

<FIG> illustrates near-eye optical assemblies 206A and 206B that are configured to be mounted to the frame <NUM>. The frame <NUM> may house the near-eye optical assemblies 206A and 206B by surrounding at least a portion of a periphery of the near-eye optical assemblies 206A and 206B. The near-eye optical assembly 206A is configured to receive visible scene light <NUM> at a backside <NUM> of the near-eye optical assembly 206A and to direct the visible scene light <NUM> on an optical path towards the eyeward side <NUM>. In some examples, near-eye optical assembly 206A may appear transparent to the user to facilitate augmented reality or mixed reality such that the user can view visible scene light <NUM> from the environment while also receiving display light <NUM> directed to their eye(s) by way of display layer <NUM>. In further examples, some or all of the near-eye optical assemblies 206A and 206B may be incorporated into a virtual reality headset where the transparent nature of the near-eye optical assemblies 206A and 206B allows the user to view an electronic display (e.g., a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a micro-LED display, etc.) incorporated in the virtual reality headset.

As shown in <FIG>, the display layer <NUM> is disposed on the optical path of the near-eye optical assembly 206A, between the eyeward side <NUM> and the backside <NUM> of the near-eye optical assembly 206A. In particular, the display layer <NUM> is disposed between the eyeward side <NUM> and the dimming layer <NUM>. In some examples, display layer <NUM> may include a waveguide <NUM> that is configured to direct display light <NUM> to present one or more virtual graphics to an eye of a user of head-mounted device <NUM>. In some aspects, waveguide <NUM> is configured to direct display light <NUM> that is generated by an electronic display to the eye of the user. In some implementations, at least a portion of the electronic display is included in the frame <NUM> of the head-mounted device <NUM>. The electronic display may include an LCD, an organic light emitting diode (OLED) display, micro-LED display, pico-projector, or liquid crystal on silicon (LCOS) display for generating the display light <NUM>.

<FIG> illustrates the dimming layer <NUM> as being disposed on the optical path of the near-eye optical assembly 206A, between the eyeward side <NUM> and the backside <NUM>. In particular, the dimming layer <NUM> is shown as being disposed between the display layer <NUM> and the backside <NUM>. In some examples, the dimming layer <NUM> includes a photochromic material that is configured to darken in response to exposure to a range of light wavelengths. For example, the photochromic material may be configured to undergo a reversible photochemical reaction in response to exposure to non-visible light, such as infrared (IR) and/or ultraviolet (UV) light. In other examples, the photochromic material may be activated to darken in response to exposure to violet light having wavelengths in the range of <NUM> to <NUM>. In some aspects, the photochromic material is a film or dye that is applied to a transparent material, such as plastic or glass. In other aspects, the photochromic material is provided by a photochromic compound that is suspended within a transparent substrate, such as plastic or glass.

In some aspects, the photochromic material of the dimming layer <NUM> is distributed across the entire field-of-view provided by the near-eye optical assembly 206A (e.g., across the entire dimming layer <NUM>). In other aspects, the photochromic material may be provided in only certain portions of the field-of-view (e.g., upper half of the dimming layer <NUM>).

<FIG> also shows the near-eye optical assembly 206A as including an activation layer <NUM> that is disposed on the optical path of the near-eye optical assembly 206A, adjacent to the dimming layer <NUM>. Although the illustrated example shows the activation layer <NUM> as being disposed on the eyeward side <NUM> of the dimming layer <NUM>, in other examples, the activation layer <NUM> may be disposed on the backside <NUM> of the dimming layer <NUM>. The activation layer <NUM> is also shown as including at least one in-field dimmer <NUM>. The in-field dimmer is configured to selectively emit an activation light <NUM> to activate a darkening of a region <NUM> of the dimming layer <NUM>. In some examples, the activation light <NUM> is within the range of light wavelengths that activate the photochromic material of the dimming layer <NUM> (e.g., IR light, UV light, violet light, etc.).

In some examples, the in-field dimmer <NUM> may be disposed on a transparent substrate and may be configured to emit the activation light <NUM> towards the dimming layer <NUM>. In some aspects, the in-field dimmer <NUM> may include a waveguide that is configured to direct light generated by a light source that is incorporated into the rim of frame <NUM> to an extraction feature or diffraction grating for emitting the light as activation light <NUM> towards the dimming layer <NUM>. The light source that generates the activation light may be a light emitting diode, a micro light emitting diode (micro-LED), an edge emitting LED, a vertical cavity surface emitting laser (VCSEL) diode, or a Superluminescent diode (SLED).

As shown in <FIG>, the in-field dimmer <NUM> is disposed within the field-of-view provided by the near-eye optical assembly 206A. While the in-field dimmer <NUM> may introduce minor occlusions into the near-eye optical assembly 206A, the in-field dimmer <NUM> may be so small as to be unnoticeable or insignificant to a wearer of head-mounted device <NUM>. Additionally, any occlusion from in-field dimmer <NUM> will be placed so close to the eye as to be unfocusable by the human eye and therefore assist in the in-field dimmer <NUM> being not noticeable or insignificant.

In some examples, the activation layer <NUM> and/or the dimming layer <NUM> may have a curvature for focusing light (e.g., scene light <NUM>) to the eye of the user. Thus, the activation layer <NUM> and/or the dimming layer <NUM> may, in some examples, may be referred to as lenses. In some aspects, the activation layer <NUM> and/or the dimming layer <NUM> have a thickness and/or curvature that corresponds to the specifications of a user. In other words, the activation layer <NUM> and/or dimming layer <NUM> may be a prescription lens.

As mentioned above, the in-field dimmer <NUM> of the activation layer <NUM> is configured to emit the activation light <NUM> towards the dimming layer <NUM> to activate a darkening of the region <NUM>. In some examples, enabling of the in-field dimmer <NUM> is dynamically determined by a computing device of the head-mounted device <NUM>. For instance, the head-mounted device <NUM> may include a computing device that determines whether the visible scene light <NUM> will interfere with the visibility of a virtual graphic generated by the visible display light <NUM> in the region <NUM>. The computing device may make such a determination based on a comparison of a color of the visible scene light <NUM> within the region <NUM> and/or by determining a contrast between the visible scene light <NUM> and the visible display light <NUM> within region <NUM>. If the color of the visible scene light <NUM> within region <NUM> is the same or similar to the color of the visible display light <NUM>, and/or if the contrast between the visible scene light <NUM> and the visible display light <NUM> is lower than a low-contrast threshold, then the computing device may enable the in-field dimmer <NUM> to emit the activation light <NUM> to darken the region <NUM>.

In some aspects, the photochemical reaction of the dimming layer <NUM> that is induced by the activation light <NUM> may be reversible. In one example, disabling the in-field dimmer <NUM>, such that it no longer emits the activation light <NUM>, allows the photochromic material of the dimming layer <NUM> to naturally revert to its previous non-darkened state. In other examples, the head-mounted device <NUM> may be configured to actively restore the dimming layer <NUM> to its non-darkened state by directing a bleaching light to the dimming layer <NUM>. In some examples, the bleaching light may be emitted by the in-field dimmer <NUM> or by other light sources (not explicitly shown) that are included in the head-mounted device <NUM>. The bleaching light may be light having a wavelength that increases the rate at which the photochromic material is restored to its non-darkened state, such as visible light, UV light, and/or IR light.

<FIG> illustrates a portion of a head-mounted device <NUM> that includes an in-field dimmer, in accordance with aspects of the present disclosure. The illustrated example of head-mounted device <NUM> is shown as including a frame <NUM>, a near-eye optical assembly <NUM>, a light source <NUM>, an optical waveguide <NUM>, and an extraction feature <NUM> (optical waveguide <NUM> and extraction feature <NUM> are collectively referred to herein as an in-field dimmer). Head-mounted device <NUM> is one possible implementation of head-mounted device <NUM> of <FIG>, where frame <NUM> corresponds to frame <NUM> and near-eye optical assembly <NUM> corresponds to near-eye optical assembly 206A.

As shown in <FIG>, the light source <NUM> may be incorporated into the frame <NUM> of the head-mounted device <NUM>, where the light source <NUM> is configured to selectively generate an activation light (e.g., activation light <NUM> of <FIG>). The optical waveguide <NUM> may be a transparent high-index waveguide that is embedded within a low-index cladding of the dimming layer (e.g., dimming layer <NUM>). In some examples, the optical waveguide <NUM> is optically coupled to the light source <NUM> by way of an index-matching prism or by a grating incoupler. The optical waveguide <NUM> is configured to direct the activation light (e.g., by total internal reflection) from the light source <NUM>, at a periphery of the near-eye optical assembly <NUM>, to the extraction feature <NUM> that is within the field-of-view.

The extraction feature <NUM> is optically coupled to the optical waveguide <NUM> and is configured to emit the activation light towards the dimming layer to activate the darkening of a region of the near-eye optical assembly <NUM>. For example, <FIG> illustrates the head-mounted device <NUM> where the in-field dimmer is enabled to darken a region <NUM> of the near-eye optical assembly <NUM>. In some examples, the extraction feature <NUM> includes a tapered expander to outcouple the activation light to have an extended beam width.

<FIG> is a cross-sectional view of a near-eye optical assembly <NUM>, in accordance with aspects of the present disclosure. The illustrated example of near-eye optical assembly <NUM> is shown as including a display layer <NUM>, an activation layer <NUM>, and a dimming layer <NUM>. Also shown in <FIG> is an eye <NUM> of a user of the head-mounted device. Near-eye optical assembly <NUM> is one possible implementation of the near-eye optical assembly 206A of <FIG>.

As shown in <FIG>, the display layer <NUM> is configured to direct visible display light <NUM> towards the eyeward side <NUM> of the near-eye optical assembly <NUM> for presenting one or more virtual graphics to the eye <NUM>. The near-eye optical assembly <NUM> is also shown as receiving visible scene light 222A-222C at the backside <NUM>, where the near-eye optical assembly <NUM> is configured to direct the visible scene light 222A-222C to the eyeward side <NUM> for viewing by the eye <NUM>. The activation layer <NUM> is shown as including an optical waveguide <NUM> that is optically coupled to the extraction feature <NUM>. The optical waveguide <NUM> and extraction feature <NUM> as shown as being embedded within a transparent material <NUM> of the activation layer <NUM>. When the in-field dimmer (e.g., optical waveguide <NUM> and extraction feature <NUM>) are disabled (i.e., not emitting activation light), then scene light 222A-222C is allowed to propagate through the dimming layer <NUM> substantially unaffected.

<FIG> is a cross-sectional view of the near-eye optical assembly <NUM> of <FIG> when the in-field dimmer is enabled to emit the activation light <NUM> to activate a darkening of region <NUM> within the dimming layer <NUM>. As shown in <FIG>, the darkening of the photochromic material within the dimming layer <NUM> is limited to the region <NUM>, where scene light 222A and 222C, that does not pass through the region <NUM>, continues to propagate through the dimming layer <NUM> substantially unaffected, whereas the scene light 222B, which does pass through region <NUM>, is indeed dimmed to dimmed scene light 222D. In some examples, the darkening of region <NUM> increases the absorption of the visible scene light 222B, such that the visible scene light 222D has a lower brightness than visible scene light 222B. In other examples, the darkening of region <NUM> may block the visible scene light 222B such that substantially none of the visible scene light 222B is passed through the dimming layer <NUM>.

<FIG> is a cross-sectional view of a near-eye optical assembly <NUM> that includes a backside filter 502A and an eyeward side filter 502B, in accordance with aspects of the present disclosure. The near-eye optical assembly <NUM> is one possible implementation of the near-eye optical assembly 206A of <FIG>.

As shown in <FIG>, the backside filter 502A is disposed on the optical path of the near-eye optical assembly <NUM> between the backside <NUM> and the dimming layer <NUM>. The backside filter 502A may be configured to absorb and/or reflect the activation light <NUM> to prevent leakage of the activation light <NUM> outside of the near-eye optical assembly <NUM>. The backside filter 502A may also be configured to block external light (e.g., scene light or other light incident on the backside <NUM>) that would activate the darkening of the photochromic material of the dimming layer <NUM>. As further shown in <FIG>, the backside filter 502A is configured to pass the visible scene light 222A-222C.

In some examples, the backside filter 502A is configured to be selectively switched between a first state and a second state. The first state may enable the backside filter 502A to block the range of light wavelengths (received at the backside <NUM>) that would activate the darkening of the photochromic material of the dimming layer <NUM>, while passing the visible scene light 222A-222C. The second state may enable the backside filter 502A to pass both the range of light wavelengths and the visible scene light 222A-222C. When in the second state, the backside filter 502A may allow the darkening of the dimming layer <NUM> across an entire field-of-view of the near-eye optical assembly <NUM>, such as may be desirable in bright light conditions. In this example, the backside filter 502A may include one or more of a switchable waveplate and at least one polarization layer.

<FIG>, further illustrates the near-eye optical assembly <NUM> as including an eyeward side filter 502B that is disposed on the optical path of the near-eye optical assembly <NUM> between the eyeward side <NUM> and the dimming layer <NUM>. The eyeward side filter 502B may be configured to absorb and/or reflect the activation light <NUM> to prevent leakage of the activation light <NUM> outside of the near-eye optical assembly <NUM>. The eyeward side filter 502B may also be configured to block external light (e.g., scene light or other light incident on the eyeward side <NUM>) that would activate the darkening of the photochromic material of the dimming layer <NUM>. As further shown in <FIG>, the eyeward side filter 502B is configured to pass the visible scene light 222A-222D.

<FIG> is a cross-sectional view of a near-eye optical assembly <NUM> that includes multiple dimming layers <NUM> and <NUM>, in accordance with aspects of the present disclosure. The near-eye optical assembly <NUM> is implemented as the near-eye optical assembly 206A of <FIG>.

The in-field dimmer (e.g., extraction feature <NUM>) is configured to emit activation light in multiple (e.g., opposite) directions. <FIG> illustrates the extraction feature <NUM> as emitting activation light <NUM> towards the eyeward side <NUM> as well as emitting activation light <NUM> towards the backside <NUM> of the near-eye optical assembly <NUM>. Thus, the near-eye optical assembly <NUM> includes multiple dimming layers, each including photochromic material. As shown in <FIG>, the activation layer <NUM> is disposed between a first dimming layer <NUM> and a second dimming layer <NUM>. The extraction feature <NUM> is configured to emit the activation light <NUM> towards the first dimming layer <NUM> to activate a darkening of a first region <NUM>. The extraction feature is also configured to emit the activation light <NUM> towards the second dimming layer <NUM> to activate a darkening of a second region <NUM>.

<FIG> is a cross-sectional view of a near-eye optical assembly <NUM> that includes a gap <NUM> for spacing the dimming layer <NUM> apart from an activation layer <NUM>, in accordance with aspects of the present disclosure. The near-eye optical assembly <NUM> is one possible implementation of the near-eye optical assembly 206A of <FIG>. In some examples, the gap <NUM> may be provided to increase a beam width <NUM> of the activation light <NUM> and to also increase a size of the region <NUM> that is darkened. In one example, the gap <NUM> is provided by one or more spacers <NUM> placed between the activation layer <NUM> and the dimming layer <NUM>, such that the gap <NUM> is an air gap. In other examples, gap <NUM> may be provided by a transparent layer, such as glass or plastic.

In some aspects, the extraction feature included in the activation layer may be configured to emit activation light such that the region of the dimming layer that is darkened has a variety of shapes and/or configurations. For example, referring back to <FIG>, the extraction feature <NUM> is configured to emit the activation light such that the region <NUM> is circularly-shaped. In another implementation, <FIG> illustrates a portion of the head-mounted device <NUM> with a rectangularly-shaped darkened region <NUM>, in accordance with aspects of the present disclosure. The illustrated example of head-mounted device <NUM> is shown as including a frame <NUM>, an optical assembly <NUM>, and a light source <NUM>. The optical assembly <NUM> is shown as including an optical waveguide <NUM> and an extraction feature <NUM>. As shown, the extraction feature <NUM> is configured to emit activation light having rectangular profile, resulting in a square-shaped region <NUM> that is darkened. In some examples the extraction feature <NUM> includes one or more microgratings, nanogratings, and/or metasurfaces that are designed and engineered to achieve a desired light output pattern. Head-mounted device <NUM> is one possible implementation of head-mounted device <NUM> of <FIG>.

<FIG> and <FIG> illustrate a portion of a head-mounted device <NUM> that includes a near-eye optical assembly <NUM> with multiple in-field dimmers (i.e., extraction features 910A-<NUM>), in accordance with aspects of the present disclosure. The illustrated example of head-mounted device <NUM> is shown as including a frame <NUM> and a near-eye optical assembly <NUM>. The frame <NUM> is shown as including light sources 906A-<NUM>, while near-eye optical assembly <NUM> is shown as including extraction features 910A-<NUM>. Head-mounted device <NUM> is one possible implementation of head-mounted device <NUM> of <FIG>.

As shown in <FIG>, the frame <NUM> includes a plurality of light sources 906A-<NUM>. Each of the light sources 906A-<NUM> may be individually-controllable to generate a respective activation light. <FIG> further illustrates a plurality of extraction features 910A-<NUM> coupled to receive the activation light from a respective light sources 906A-<NUM> via a respective optical waveguide. Although FIG. 5A illustrates the near-eye optical assembly <NUM> as including thirteen in-field dimmers (e.g., extraction features 910A-<NUM>), in other examples the near-eye optical assembly <NUM> may include any number of in-field dimmers, including one or more. In addition, the in-field dimmers may be arranged within the field-of-view in a variety of configurations, where the in-field dimmers provide coverage over only a portion of the field-of-view, or over the entire field-of-view.

As shown, each extraction feature 910A-<NUM> is configured to emit activation light to darken a respective region 912A-<NUM> of a dimming layer of the near-eye optical assembly <NUM>. In some examples, a computing device of the head-mounted device <NUM> may selectively enable one or more of the light sources 906A-<NUM> to dynamically darken a variety of the regions 912A-<NUM>. In some examples, the determination of which of the regions 912A-<NUM> to darken is based on the size, shape, number, and/or position of the virtual graphics that are to be generated by the near-eye optical assembly <NUM>. <FIG> illustrates an example where light sources 906C, 906E, and 906F-<NUM> are enabled to darken respective regions 912C, 912E, and 912F-<NUM>, while light sources 906A, 906B, 906D, <NUM>, and <NUM> are disabled (i.e., not generating activation light).

<FIG> illustrates a portion of a head-mounted device <NUM> that includes a near-eye optical assembly <NUM> with multiple in-field dimmers that provide separate and distinct darkened regions 1014A-1014C, in accordance with aspects of the present disclosure. Head-mounted device <NUM> is one possible implementation of head-mounted device <NUM> of <FIG>. Head-mounted device <NUM> is shown as including a frame <NUM> and a near-eye optical assembly <NUM>. The frame <NUM> is shown as including light sources <NUM>, <NUM>, and <NUM>. The near-eye optical assembly <NUM> is shown as including multiple in-field dimmers (i.e., extraction features 1012A-<NUM>).

In some implementations, the virtual graphics generated by the near-eye optical assembly <NUM> may be generated in known and repeatable locations within the field-of-view. Accordingly, the in-field dimmers may be located within the near-eye optical assembly <NUM> to provide regions 1014A-1014D that correspond to these known locations for the virtual graphics. In addition, each of the light sources <NUM>, <NUM>, and <NUM> may be individually-controlled, such that each of the regions 1014A-1014D may be individually darkened based on a determined need.

<FIG> illustrates a portion of a head-mounted device <NUM> that includes a near-eye optical assembly <NUM> with an optical waveguide <NUM> for leaking activation light to provide a darkened region <NUM>, in accordance with aspects of the present disclosure. The illustrated example of head-mounted device <NUM> is shown as including a frame <NUM> and a near-eye optical assembly <NUM>. The frame <NUM> is shown as including a light source <NUM> and the near-eye optical assembly <NUM> is shown as including the optical waveguide <NUM>. Head-mounted device <NUM> is one possible implementation of head-mounted device <NUM> of <FIG>.

The above-described examples of an in-field dimmer are provided by way of a dedicated extraction feature that is coupled to an optical waveguide. However, in some examples, the extraction features may be omitted, where the optical waveguide is configured to leak the activation light towards the dimming layer of the near-eye optical assembly. For example, the optical waveguide <NUM> may be designed to be intrinsically lossy in a controlled manner as the activation light propagates through it. The activation light may leave the optical waveguide <NUM> towards the dimming layer to activation darkening in a region <NUM>. In another example, the optical waveguide <NUM> may be designed to be less lossy, but designed scatterers are arranged along the length of and integrated into the optical waveguide <NUM>. When the activation light propagates in the optical waveguide <NUM> and meets a scatterer, a portion of the activation light leaks from the optical waveguide <NUM> into the dimming layer to darken the region <NUM>.

<FIG> illustrates a portion of a head-mounted device <NUM> with an in-field dimmer that includes multiple extraction features <NUM> optically coupled to a single waveguide <NUM>, in accordance with aspects of the present disclosure. The illustrated example of head-mounted device <NUM> is shown as including a frame <NUM> and a near-eye optical assembly <NUM>. The frame <NUM> is shown as including a light source <NUM> and the near-eye optical assembly <NUM> is shown as including the optical waveguide <NUM> and a plurality of extraction features <NUM>. Head-mounted device <NUM> is one possible implementation of head-mounted device <NUM> of <FIG>.

As shown in <FIG>, each of the extraction features <NUM> are optically coupled to the optical waveguide <NUM>. In operation, the optical waveguide <NUM> is configured to direct the activation light from the light source <NUM> to each of the extraction features <NUM>, where each extraction feature <NUM> is configured to emit the activation light towards the dimming layer to darken the region <NUM>.

<FIG> illustrates a portion of a head-mounted device <NUM> with an in-field dimmer that includes a diffraction grating <NUM>, in accordance with aspects of the present disclosure. The illustrated example of head-mounted device <NUM> is shown as including a frame <NUM> and a near-eye optical assembly <NUM>. The frame <NUM> is shown as including a light source <NUM> and the near-eye optical assembly <NUM> is shown as including the optical waveguide <NUM>, a tapered expander <NUM>, and diffraction grating <NUM>. Head-mounted device <NUM> is one possible implementation of head-mounted device <NUM> of <FIG>.

In the illustrated example, the diffraction grating <NUM> (e.g., volume Bragg grating) is optically coupled to the optical waveguide <NUM> by way of the tapered expander <NUM>. The optical waveguide <NUM> is configured to direct the activation light from light source <NUM> to the diffraction grating, where the diffraction grating <NUM> is configured to direct the activation light towards the dimming layer to darken the region <NUM>.

<FIG> illustrates an example computing device <NUM> for the dynamic control of in-field dimmers, in accordance with aspects of the present disclosure. The illustrated example of computing device <NUM> is shown as including a communication interface <NUM>, one or more processors <NUM>, hardware <NUM>, and a memory <NUM>. In one example, one or more of the components illustrated in <FIG> may be incorporated into the frame <NUM> and/or temple arms 204A/204B of the head-mounted device <NUM> of <FIG>. In another example, one or more of the components illustrated in <FIG> may be incorporated into the frame <NUM> and/or temple arm <NUM> of the head-mounted devices 1400A and 1400B of <FIG> and <FIG>. In other examples, one of more of the components illustrated in <FIG> may be incorporated into a remote computing device that is communicatively coupled to the head-mounted device <NUM>/<NUM> for performing one or more aspects of the dynamic control of the in-field dimmers.

The communication interface <NUM> may include wireless and/or wired communication components that enable the computing device <NUM> to transmit data to and receive data from other networked devices. The hardware <NUM> may include additional hardware interface, data communication, or data storage hardware. For example, the hardware interfaces may include a data output device (e.g., electronic display, audio speakers), and one or more data input devices.

The memory <NUM> may be implemented using computer-readable media, such as computer storage media. In some aspects, computer-readable media may include volatile and/or non-volatile, removable and/or non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data. Computer-readable media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD), high-definition multimedia/data storage disks, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information for access by a computing device.

The processors <NUM> and the memory <NUM> of the computing device <NUM> may implement a display module <NUM> and a dimming control module <NUM>. The display module <NUM> and the dimming control module <NUM> may include routines, program instructions, objects, and/or data structures that perform particular tasks or implement particular abstract data types. The memory <NUM> may also include a data store (not shown) that is used by the display module <NUM> and/or dimming control module <NUM>.

The display module <NUM> may be configured to determine that the visible scene light (e.g., visible scene light <NUM> of <FIG>) in a region of the near-eye optical assembly will interfere with a visibility of a virtual graphic (e.g., virtual graphic <NUM> of <FIG>) that is generated by the visible display light <NUM> located in the same region. In some implementations, the head-mounted device may include one or more light sensors that provide information about the visible scene light (e.g., brightness, contrast, color, etc.). In another implementation, the head-mounted device may include a camera that is positioned (e.g., on the temple arm 204B of <FIG>) to obtain images of the field-of-view provided by the optical assembly. The display module <NUM> may receive the images and/or data from the light sensor to determine whether the visible scene light is interfering with a visibility of the virtual graphic.

In some aspects, the display module <NUM> determines the visibility of the virtual graphic based on readings obtained from the light sensors and/or by performing image processing on images of the field-of-view. This may include determining an ambient brightness and/or determining a contrast between the visible scene light and the virtual graphic. In another example, the display module <NUM> may determine the visibility of the virtual graphic by comparing a color of the visible scene light in a region that corresponds to where the virtual graphic is to be displayed. If the visible scene light is too bright, the contrast between the scene light and the virtual graphic is too low, and/or if a color of the scene light is similar to that of the virtual graphic, then the display module <NUM> then determines that the visible scene light will indeed interfere with the visibility of the virtual graphic.

In response the determination by the display module <NUM> that the visible scene light will interfere with the visibility of the virtual graphic, the dimming control module <NUM> may then activate the darkening of one or more regions of the dimming layer of the near-eye optical assembly to dim and/or occlude the visible scene light. For example, with reference to head-mounted device <NUM> of <FIG>, the dimming control module <NUM> may enable in-field dimmer <NUM> to emit the activation light <NUM> to activate the darkening of region <NUM> in dimming layer <NUM>. As discussed above, the darkening of region <NUM> may dim the visible scene light <NUM> within the region <NUM> to increase the visibility of the virtual graphic generated by display light <NUM>.

By way of another example, and with reference to the head-mounted device <NUM> of <FIG>, the dimming control module <NUM> may control the digital projector 1408A to emit the activation light 1410A to activate the darkening of region <NUM> to increase the visibility of a virtual graphic generated by a display layer of the near-eye optical assembly <NUM> within the region <NUM>. The dimming control module <NUM> may also be configured to control the laser scanner of the digital projector 1408A to raster scan the region <NUM> to activate the darkening. In some examples, the dimming control module <NUM> may be configured to control the digital projector 1408A to direct the activation light 1410A to darken a plurality of separate and distinct regions of the dimming layer.

In some aspects, the dimming control module <NUM> may be configured to vary an amount of darkening that is provided by a region of the dimming layer. For example, <FIG> illustrates a varying amount of darkening provided by a dimming layer of a near-eye optical assembly <NUM>, in accordance with aspects of the present disclosure. The near-eye optical assembly <NUM> illustrates various amounts of darkening that may be provided by the near-eye optical assembly 206A of <FIG> and/or by the near-eye optical assembly <NUM> of <FIG> and <FIG>. For example, a first region <NUM> is darkened by a first amount, a second region <NUM> is darkened by a second amount, and a third region <NUM> is darkened by a third amount. In some aspects, the amount to darken a particular region is determined based on the amount of dimming needed to make the virtual graphic sufficiently visible to the user. For example, in some implementations an upper region of the field-of-view may include a view of the sky which is generally brighter than a lower region of the field-of view which may include a view of the ground. Thus, regions in the upper half of the field-of-view may be darkened more than those is the lower half of the field-of-view. Even still, a bright spot within the field-of-view caused by external light sources (e.g., oncoming vehicle headlight, lamp, etc.) may need to be dimmed more as compared to the surrounding areas.

When incorporated into the head-mounted device <NUM> of <FIG> or the head-mounted device 1400B of <FIG>, varying the amount of darkening may include the dimming control module <NUM> performing pulse-width modulation of the light source of the in-field dimmer <NUM> or the digital projector 1408A. For example, the dimming control module <NUM> may adjust the frequency, ON time, and/or OFF time of the light source to increase or decrease the amount of darkening of the dimming layer.

When incorporated into the head-mounted device 1400A of <FIG>, varying the amount of darkening may include the dimming control module <NUM> controlling the scanning speed and/or laser power of the laser scanner of the digital projector 1408A to increase or decrease the darkening of the dimming layer included in near-eye optical assembly <NUM>.

Embodiments of the invention may include or be implemented in conjunction with an artificial reality system. Artificial reality is a form of reality that has been adjusted in some manner before presentation to a user, which may include, e.g., a virtual reality (VR), an augmented reality (AR), a mixed reality (MR), a hybrid reality, or some combination and/or derivatives thereof. Artificial reality content may include completely generated content or generated content combined with captured (e.g., real-world) content. The artificial reality content may include video, audio, haptic feedback, or some combination thereof, and any of which may be presented in a single channel or in multiple channels (such as stereo video that produces a three-dimensional effect to the viewer). Additionally, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, that are used to, e.g., create content in an artificial reality and/or are otherwise used in (e.g., perform activities in) an artificial reality. The artificial reality system that provides the artificial reality content may be implemented on various platforms, including a head-mounted display (HMD) connected to a host computer system, a standalone HMD, a mobile device or computing system, or any other hardware platform capable of providing artificial reality content to one or more viewers.

Claim 1:
An optical assembly (<NUM>), comprising:
an eyeward side (<NUM>) and a backside (<NUM>), wherein the optical assembly (<NUM>) is configured to receive visible scene light (<NUM>) at the backside (<NUM>) of the optical assembly (<NUM>) and to direct the visible scene light (<NUM>) on an optical path toward the eyeward side (<NUM>);
a first dimming layer (<NUM>) and a second dimming layer (<NUM>) disposed on the optical path between the eyeward side (<NUM>) and the backside (<NUM>), wherein the first dimming layer (<NUM>) and the second dimming layer (<NUM>) include a photochromic material that is configured to darken in response to exposure to a range of light wavelengths; and
an activation layer (<NUM>) disposed on the optical path, adjacent to the first dimming layer (<NUM>) and the second dimming layer (<NUM>);
characterized in that the activation layer (<NUM>) is disposed between the first dimming layer (<NUM>) and the second dimming layer (<NUM>), and the activation layer (<NUM>) includes an in-field dimmer that is configured to selectively emit an activation light (<NUM>, <NUM>) within the range of light wavelengths in multiple directions towards the first dimming layer (<NUM>) and the second dimming layer (<NUM>) to activate a darkening of a first region (<NUM>) of the first dimming layer (<NUM>) and a second region (<NUM>) of the second dimming layer (<NUM>) to dim the visible scene light (<NUM>) within the first region (<NUM>) and the second region (<NUM>).