Patent Description:
Head-mounted display devices (HMDs) are display devices, worn on the head of a user, having one or more display units for presenting visual content to a user. HMDs are becoming increasingly popular to provide virtual reality (VR) or augmented reality (AR) experiences, or to facilitate gaming or presentation of audiovisual media. The display units are typically miniaturized and may include CRT, LCD, Liquid crystal on silicon (LCos), or OLED technologies, for example. Some HMDs are binocular and have the potential to display a different image to each eye. This capability is used to display stereoscopic images to present a more immersive user experience.

Existing HMDs do not account for a user's vision defects or deficiencies. For instance, persons with astigmatism, myopia, or hyperopia (also known as Presbyopia) may wear glasses to correct one or more of these conditions. However, previously-implemented HMDs display visual content to users without adapting virtual image light to correct for these conditions. At least some HMDs do not have sufficient space in front of or around a user's eyes to allow the user to wear vision correction glasses and the HMD. As a result, the visual content may appear unfocused or unclear to a user afflicted with defects or deficiencies in vision who wear glasses, detracting from the user's overall experience.

International patent application <CIT> relates to a virtual or augmented reality headset comprising two lens groups for imaging two side-by-side <NUM>-dimensional images displayed on a display within the headset to form a virtual stereo-graphic <NUM>-dimensional image; each lens group comprising a primary lens, a first adjustable lens for correcting a spherical refractory error in a user's distance vision and a second adjustable lens for correcting astigmatism, the primary lens and first and second adjustable lenses within each lens group being in mutual optical alignment on a respective optical axis. Suitably, the first adjustable lens comprises a cubic surface-type adjustable lens (e.g. an Alvarez lens) comprising two superposed lens elements having mutually cooperating cubic or higher order surfaces that are slidable relative to one other along an x-axis of the first adjustable lens, while the second adjustable lens is rotatable about the z-axis and comprises a cubic surface-type in which two similarly superposed lens elements are slidable relative to one other along a y-axis of the second adjustable lens.

A head-mounted display may be summarized as including a frame comprising a cavity, and a virtual image display device coupled to the frame and configured to generate virtual image light for causing a user to perceive visual content. The head-mounted display device further comprising an optical system that is selectively removably insertable into the cavity of the frame and, when the inserted into the cavity, the optical system is located along an optical path of rays of the virtual image light.

The optical system comprises a first correcting portion having a left optical subsystem and a right optical subsystem. Each of the left and right optical subsystems of the first correcting portion include one or more actuators, and a first set of lenses positioned at a first location along the optical path and having first optical characteristics correcting for a first set of vision conditions. At least one of a first lens and a second lens of the first set of lenses are selectively adjustable relative to the other of the first lens and the second lens of the first set of lenses, via the one or more actuators, along a first axis transverse to the optical path to modify the first optical characteristics. The optical system further comprises one or more electrical contacts exposed on an exterior surface of the optical system, the one or more electrical contacts sized and shaped to engage with corresponding electrical contacts within the cavity of the frame to establish an electrical connection through which signals and power may be transmitted to the one or more actuators of the optical system.

In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed implementations. However, one skilled in the relevant art will recognize that implementations may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with computer systems, server computers, and/or communications networks have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the implementations.

Unless the context requires otherwise, throughout the specification and claims that follow, the word "comprising" is synonymous with "including," and is inclusive or open-ended (i.e., does not exclude additional, unrecited elements or method acts). References to the term "set" (e.g., "a set of items"), as used herein, unless otherwise noted or contradicted by context, is to be construed as a nonempty collection comprising one or more members or instances.

Reference throughout this specification to "one implementation" or "an implementation" means that a particular feature, structure or characteristic described in connection with the implementation is included in at least one implementation. Thus, the appearances of the phrases "in one implementation" or "in an implementation" in various places throughout this specification are not necessarily all referring to the same implementation. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more implementations.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the context clearly dictates otherwise.

The headings and Abstract of the Disclosure provided herein are for convenience only and do not interpret the scope or meaning of the implementations.

<FIG> shows an overhead plan view of a head-mounted display device (HMD) <NUM> according to one or more embodiments. The HMD <NUM> is configured to present a virtual reality (VR) to a user <NUM>, such as via corresponding video presented at a display rate such as <NUM> frames (or images) per second or <NUM> frames per second, while other embodiments of a similar system may present an augmented reality display to the user <NUM>. The HMD <NUM> provides corrected virtual image light <NUM> to a left eye <NUM> and a right eye 105r of a user <NUM>. The HMD <NUM> includes one or more virtual image display units <NUM> mounted to or within a frame <NUM>. The virtual image display units <NUM> generate virtual image light <NUM> for causing the user to perceive visual content. The HMD <NUM> may further include left and right sets of lenses <NUM> and 107r provided on an emission side of the virtual image display units <NUM>. The left and right sets of lenses <NUM> and 107r may focus, collimate, or otherwise modify the virtual image light <NUM> after it is emitted from the virtual image display units <NUM>. The left and right sets of lenses <NUM> and 107r may include, for example, Fresnel lenses that refract or collimate the virtual image light <NUM>.

The HMD <NUM> also includes an optical system <NUM> that has optical characteristics that are selectively variable for correcting for one or more vision conditions of the user. For instance, the optical system <NUM> is selectively adjustable to correct for one or more of myopia, hyperopia, and astigmatism. The virtual image light <NUM> emitted from the virtual image display units <NUM> travels along an optical path <NUM> through the optical system <NUM>, which modifies the virtual image light <NUM> according to the optical characteristics of the optical system <NUM> and emits corrected virtual image light <NUM> to the left and right eyes <NUM> and 105r, respectively, of the user.

The frame <NUM> is a mounting structure for supporting the HMD <NUM> on the head of the user <NUM>. The frame <NUM> includes a main body <NUM> having a front portion <NUM> and a viewing portion <NUM> opposite to the front portion <NUM> for positioning in front of the user's eyes <NUM> and 105r to view the visual content generated. The HMD <NUM> includes one or more support structures for selectively mounting the HMD <NUM> to the user's head. For instance, the HMD <NUM> of <FIG> includes left and right temples <NUM> and 122r for respectively resting over the left and right ears <NUM> and 124r of the user <NUM>. In some embodiments, the HMD <NUM> may include another support structure, such as a strap connected to the main body <NUM> that wraps around the back of the head of the user <NUM>. A nose assembly (not shown) of the HMD <NUM> may support the main body <NUM> on the nose of the user <NUM>. The frame <NUM> may be shaped and sized to position the optical system <NUM> in front of one of the user's eyes <NUM> and 105r. Although the frame <NUM> is shown in a simplified manner similar to eyeglasses for explanatory purposes, it should be appreciated that in practice more sophisticated structures (e.g., goggles, integrated headband, helmet, straps, etc.) may be used to support and position the HMD <NUM> on the head of the user <NUM>.

The virtual image display units <NUM> generate the virtual image light <NUM> that is transmitted through and selectively modified by the optical system <NUM>. The virtual image display units <NUM> include a left display unit <NUM> for generating image light for presentation to the left eye <NUM> and a right display unit 106r for generating image light for presentation to the right eye 105r. The virtual image display units <NUM> may include liquid crystal displays (LCDs), light emitting diodes (LEDs), cathode ray tubes (CRTs), liquid crystal on silicon (LCos), or other light emitting technologies that generate the virtual image light <NUM>. The virtual image display units <NUM> of the embodiment shown in <FIG> are located in a front portion of the HMD <NUM> and emit light in a rearward direction toward the eyes of the user <NUM>. In some embodiments, the virtual image display units <NUM> may include waveguides that direct (e.g., reflect, refract) the virtual image light <NUM> toward the eyes <NUM> or 105r such that the light emitting elements of the virtual image display units <NUM> are not required to be directly in front of the eyes <NUM> and 105r for the user <NUM> to perceive the visual content. In some embodiments, the front portion <NUM> of the main body <NUM> may be at least partially transparent such that the user <NUM> may perceive external content for providing an augmented reality experience. While not illustrated here, some embodiments of the HMD <NUM> may include various additional internal and/or external sensors, such as to perform pupil tracking separately for each eye <NUM> and 105r, to track head location and orientation (e.g., as part of head tracking), to track various other types of movements and position of the user's body, cameras to record external images (e.g., of an environment), etc..

While the described techniques may be used in some embodiments with a display system similar to that illustrated in <FIG>, in other embodiments other types of display systems may be used, including with a single optical lens and display device, or with multiple such optical lenses and display devices. Non-exclusive examples of other such devices include cameras, telescopes, microscopes, binoculars, spotting scopes, surveying scopes, etc. In addition, the described techniques may be used with a wide variety of display panels or other display devices that emit light to form images, which one or more users view through one or more optical lens. In other embodiments, the user may view one or more images through one or more optical lens that are produced in manners other than via a display panel, such as on a surface that reflects light from another light source in part or in whole.

The virtual image light <NUM> may comprise a plurality of light rays that travel from each of the virtual image display units <NUM> along an optical path <NUM> through the optical system <NUM> and toward the viewing portion <NUM>. The optical system <NUM> modifies some or all of the plurality of light rays to provide the corrected virtual image light <NUM>. The optical system <NUM> includes a plurality of optical subsystems <NUM> including a left optical subsystem <NUM> for modifying the virtual image light <NUM> for the left eye <NUM> and a right optical subsystem 130r for modifying the virtual image light <NUM> for the right eye 105r. Each of the left and right optical subsystems <NUM> and 130r may be independently adjustable to correct for visual deficiencies or defects in the left eye <NUM> and the right eye 105r, respectively.

<FIG> shows a diagram <NUM> of the optical subsystem <NUM> (e.g., optical subsystem <NUM> or 130r ) of <FIG> according to one or more embodiments. The optical subsystem <NUM> includes a receiving portion <NUM> for receiving initial virtual image light <NUM> corresponding to the virtual image light <NUM> for a single eye, and an emitting portion <NUM> for emitting the corrected virtual image light <NUM>. The optical subsystem <NUM> further comprises a first correction portion <NUM> located at a first location along optical path <NUM> (<FIG>) of the plurality of light rays <NUM> and a second correction portion <NUM> located at a second location along the optical path <NUM> downstream from the first location. The first correction portion <NUM> and the second correction portion <NUM> each comprise a set of lenses and are operable to correct for deficiencies or defects in the vision of the user <NUM>. The first correction portion <NUM> may correct for a different set of vision conditions than the second correction portion <NUM>. For instance, one of the first correction portion <NUM> and the second correction portion <NUM> may correct for myopia or hyperopia whereas the other of the first correction portion <NUM> and the second correction portion <NUM> corrects for astigmatism. Optical characteristics of the first correction portion <NUM> and/or the second correction portion <NUM> may be adjusted as a result of receiving a stimulus, such as an electronic signal or an application of mechanical force, as described below in further detail. Although two correction portions <NUM> and <NUM> are described with respect to <FIG>, the optical system <NUM> may include a single correction portion in some embodiments. For instance, the optical system <NUM> may include one of the first correction portion <NUM> and the second correction portion <NUM> for correcting myopia and/or hyperopia and the other of the first correction portion <NUM> and the second correction portion <NUM> may be omitted. As another example, the optical system <NUM> may include one of the first correction portion <NUM> and the second correction portion <NUM> for correcting astigmatism and omit the other of the first correction portion <NUM> and the second correction portion <NUM>.

The first correction portion <NUM> is operable to apply first corrections to the initial virtual image light <NUM> to correct for the first set of vision conditions of the user <NUM>. The initial virtual image light <NUM> may comprise a plurality of light rays <NUM> each having a particular set of attributes (e.g., color, direction, luminance) for causing the user <NUM> to perceive the visual content. In operation, the first correction portion <NUM> may receive a first stimulus <NUM> that causes first optical characteristics of the first correction portion <NUM> to change or modify the initial image light <NUM> as a correction for the first set of vision conditions. The first correction portion <NUM> may then emit intermediate virtual image light <NUM>, which is received by the second correction portion <NUM>. The intermediate virtual image light <NUM> comprises a plurality of light rays <NUM> at least some of which correspond to the plurality of light rays <NUM>. In cases where the user does not have the first set of vision conditions, the intermediate virtual image light <NUM> may be substantially unmodified from the initial virtual image light <NUM>. That is, the intermediate virtual image light <NUM> may have the same attributes as the initial virtual image light <NUM> received if the first correction portion <NUM> receives the first stimulus <NUM> that causes the first correction portion <NUM> to pass the initial virtual light without substantial modification since the user does not require correction for the first set of vision conditions.

The second correction portion <NUM> is operable to apply second corrections to the intermediate virtual image light <NUM> (or to the initial virtual image light <NUM> in implementations wherein the first correction portion <NUM> is not present) to correct for the second set of vision conditions of the user <NUM>. The second correction portion <NUM> may receive a second stimulus <NUM> that causes second optical characteristics of the second correction portion <NUM> to change to modify the intermediate virtual image light <NUM> as a correction for the second set of vision conditions, which may be distinct from the first set of vision conditions. The second correction portion <NUM> may then emit the corrected virtual image light <NUM>, which comprises a plurality of light rays at least some of which correspond to the light rays <NUM>. As with the first correction portion <NUM>, the corrected virtual image light <NUM> may be substantially unmodified from the intermediate virtual image light <NUM> if the user <NUM> is not afflicted with any of the second set of vision conditions. That is, the second correction portion <NUM> may not modify the intermediate virtual image light <NUM> if the second stimulus <NUM> causes the second correction portion not to correct for any one or more of the second set of vision conditions.

<FIG> is a diagram <NUM> that shows an overhead plan view of a set of lenses <NUM> of a correction portion according to one or more embodiments. In particular, the set of lenses <NUM> are lenses of one of the first correction portion <NUM> and the second correction portion <NUM> of <FIG>. The set of lenses <NUM> includes a first lens <NUM> and a second lens <NUM> that are successively arranged along the optical path <NUM> of the virtual image light <NUM>. Each of the set of lenses <NUM> may have a width W longer than a thickness T. In some embodiments, the lenses <NUM> may have a substantially rectangular shape when viewed from a perspective along the optical path <NUM>, for example. Rays <NUM> of the virtual image light <NUM> travelling along the optical path <NUM> are incident upon and travel through at least a portion of the first lens <NUM> and at least a portion of the second lens <NUM>. At least one of the first lens <NUM> and the second lens <NUM> is selectively adjustable in directions transverse to the optical path <NUM> for modifying attributes of the rays <NUM>. For instance, the set of lenses <NUM> may be adjustable to set an optical power or focus of the optical system <NUM> to correct for deficiencies or defects in the vision of the user <NUM>. The first lens <NUM> may be selectively movable along an axis <NUM> that is transverse to the optical path <NUM> and the second lens is also selectively movable along an axis <NUM> that is transverse to the optical path <NUM> and spaced apart from the first axis <NUM> along the optical path <NUM>. In some embodiments, a single one of the first lens <NUM> and the second lens <NUM> may be moveable relative to the other one of the first lens <NUM> and the second lens <NUM>. In some embodiments, each of the first lens <NUM> and the second lens <NUM> is moveable relative to the other of the first lens <NUM> and the second lens <NUM>.

The first lens <NUM> and the second lens <NUM> have respective widths W that extend along the first axis <NUM> and the second axis <NUM>. The first lens <NUM> may have different characteristics at different portions along a width W of the first lens <NUM>. A first portion 304a of the first lens <NUM> may have a different thickness and surface curvature than a thickness and/or curvature of a second portion 304b. The first portion 304a may, for instance, have a convex lens surface and have a first thickness in a thickness direction T whereas the second portion 304b may have a concave lens surface and a second thickness different than the first thickness. A first surface <NUM> of the first lens <NUM> may have a different shape than a second surface <NUM> of the first lens <NUM> - for example, the first surface <NUM> may be flat along the width W whereas the second surface <NUM> may be curved (e.g., convex, concave, serpentine) along the width W. In some embodiments, the first lens <NUM> may have a surface that is curved along its entire length. In some embodiments, the first lens <NUM> may have a surface that is curved in one portion but flat in another portion. The flat portion may be used as a non-corrective portion that does not modify the virtual image light <NUM> to correct for vision conditions.

The second lens <NUM> may also have different characteristics at different portions along a width W of the second lens <NUM>. A first portion 306a of the second lens <NUM> may have a different thickness and surface curvatures than a thickness and/or curvature of a second portion 306b. The first portion 306a may, for instance, have a concave lens surface and have a first thickness in a thickness direction T whereas the second portion 306b may have a convex lens surface and a second thickness different than the first thickness. The first portion 306a of the second lens <NUM> may have different characteristics than the first portion 304a of the first lens <NUM>. A first surface <NUM> of the second lens <NUM> may have a different shape than a second surface <NUM> of the second lens <NUM> - for instance, the first surface <NUM> may be curved along the width W whereas the second surface <NUM> may be flat along the width W. In some embodiments, the second lens <NUM> may have a surface that is curved along its entire length. In some embodiments, the second lens <NUM> may have a surface that is curved in one portion but flat in another portion. The flat portion may be used as a non-corrective portion that does not modify the virtual image light <NUM> to correct for vision conditions. In some embodiments, the first lens <NUM> and the second lens <NUM> may be Alvarez lenses or Lohmann lenses that have opposing complementary refractive surfaces (e.g., having a profile with a cubic function) and opposite-facing plano surfaces. For instance, opposite surfaces (surfaces facing away from each other) of the first lens <NUM> and the second lens <NUM> may have substantially plano surfaces whereas opposing surfaces (surfaces facing each other) of the first lens <NUM> and the second lens <NUM> may have complementary curved profiles that are the inverse of each other.

The first lens <NUM> and/or the second lens <NUM> may be selectively moved along the axis <NUM> and <NUM>, respectively, to correct for a first set of vision conditions, which may include myopia and hyperopia. The set of lenses <NUM> may include a first actuator <NUM> that is physically coupled to the first lens <NUM> and that is configured to move the first lens <NUM> along the axis <NUM>. The first actuator <NUM> may be moved as a result of the first stimulus <NUM> described above with respect to <FIG> - for example, moved as result of a mechanical force applied to a dial, button, knob, etc., or as a result of the optical system <NUM> receiving an electronic signal for causing the first actuator <NUM> to move. The set of lenses <NUM> may also include a second actuator <NUM> that is physically coupled to the second lens <NUM> and that is configured to move the second lens <NUM> along the axis <NUM>. The second actuator <NUM> may be moved as a result of a stimulus in a manner similar to the relationship of the first actuator <NUM> and the first stimulus <NUM>. The first actuator <NUM> and the second actuator <NUM> may be moved independently of each other. Accordingly, the first actuator <NUM> may move the first lens <NUM> relative to the second lens <NUM> and the second actuator <NUM> may move the second lens <NUM> relative to the first lens <NUM>. The first lens <NUM> and the second lens <NUM> may be moved relative to one another to provide optical characteristics correcting for vision conditions. In some embodiments, one of the first lens <NUM> and the second lens <NUM> may be fixed whereas the other of the first lens <NUM> and the second lens <NUM> is adjustable relative to the fixed lens.

The first lens <NUM> and the second lens <NUM> may be aligned along the optical path <NUM> of the virtual image light <NUM> to correct one or more of the first set of vision conditions. For instance, the first portion 304a of the first lens <NUM> may be aligned with the first portion 306a of the second lens <NUM> to correct for myopia. As another example, the second portion 304b of the first lens <NUM> may be aligned with the second portion 306b of the second lens <NUM> to correct for hyperopia. In some embodiments, other portions of the first lens <NUM> and the second lens <NUM> may be aligned to transition the set of lenses <NUM> into a non-corrective state. Portions of the first lens <NUM> and the second lens <NUM> may be aligned along the optical path <NUM> to satisfy an optical prescription of the user <NUM> in some instances. For instance, the first lens <NUM> and the second lens may be positioned relative to each other to adjust the optical power (i.e., diopter) of the set of lenses <NUM>. In some embodiments, the set of lenses <NUM> may provide corrections corresponding to a "spherical" or refractive portion of an optical prescription. Although only two lenses are depicted and described as comprising the set of lenses <NUM>, the set of lenses <NUM> may include additional lenses without departing from the scope of the instant disclosure.

<FIG> shows an arrangement <NUM> of a set of lenses <NUM> of a correction portion according to one or more embodiments. In particular, the set of lenses <NUM> are lenses of the other one of the first correction portion <NUM> and the second correction portion <NUM> than the set of lenses <NUM>. The set of lenses <NUM> includes a first lens <NUM> and a second lens <NUM> that are successively arranged along the optical path <NUM> of the virtual image light <NUM> either before or after the set of lenses <NUM>. The first lens <NUM> and the second lens <NUM> may have a substantially circular shape when viewed from a direction parallel to the optical path <NUM>, for example. Rays <NUM> of the virtual image light <NUM> travelling along the optical path <NUM> are incident upon and travel through at least portions of the first lens <NUM> and the second lens <NUM>.

The first lens <NUM> and the second lens <NUM> are selectively rotatable about axes parallel to the optical path <NUM>. The first lens <NUM> is rotatable about a first axis <NUM> that is transverse to the axis <NUM> and the axis <NUM>. The second lens <NUM> is also rotatable about a second axis <NUM> that is transverse to the axis <NUM> and the axis <NUM>. In the current embodiment, the first axis <NUM> is coaxial with the second axis <NUM>. In some embodiments, a single one of the first lens <NUM> and the second lens <NUM> may be rotatable relative to the other of the first lens <NUM> and the second lens <NUM>. In such instances, the other one of the first lens <NUM> and the second lens <NUM> may be non-rotatable. In some embodiments, each of the first lens <NUM> and the second lens <NUM> is rotatable relative to each other.

A first actuator <NUM> is physically coupled to the first lens <NUM> and operable to selectively rotate the first lens <NUM> about the first axis <NUM>. A second actuator <NUM> is physically coupled to the second lens <NUM> and operable to selectively rotate the second lens <NUM> about the second axis <NUM>. As an example, the first and second actuators <NUM> and <NUM> may be respectively coupled to gears or teeth associated with the first lens <NUM> and the second lens <NUM> to cause the lenses to rotate in response to application of force by the actuator. The first and second actuators <NUM> and <NUM> respectively cause particular portions of the first and second lenses <NUM> and <NUM> to be positioned within the optical path <NUM> to modify attributes of the rays <NUM>. For instance, the set of lenses <NUM> are selectively adjustable to correct for optical aberrations in the vision of the user <NUM>, such as astigmatism. The set of lenses <NUM> may be adjustable to provide corrections for "cylinder" and "axis" portions of an optical prescription. In some implementations, however, the set of lenses <NUM> may be adjustable to provide correction for "spherical" or refractive portions of an optical prescription.

The first lens <NUM> and the second lens <NUM> may be Alvarez or Lohmann lenses (sometimes known as Alvarez-Lohmann lenses). In some embodiments, the Alvarez or Lohmann lenses have a circular shape when viewed from an optical surface thereof. In some embodiments, the Alvarez lenses have a rectangular shape when viewed from an optical surface thereof. The controller described herein operates the first and second actuators <NUM> and <NUM> to position portions of the first lens <NUM> and the second lens <NUM> in the optical path <NUM> to modify attributes of the rays <NUM>, as described herein. For instance, in embodiments where one or both of the first lens <NUM> and the second lens <NUM> are Alvarez lenses, the relative positions of the first lens <NUM> and the second lens <NUM> may be adjusted to provide a profile (e.g., circular profile, cylindrical profile, elliptical profile) inducing phase variations in the rays <NUM> that correct for a vision condition of the user <NUM>.

<FIG> shows a front plan view of the first lens <NUM> taken along the line A-A of <FIG>. The first lens <NUM> may have different characteristics at different angular positions or angular regions about the first axis <NUM>. A second surface <NUM> of the first lens <NUM> may vary along a width W of the first lens <NUM> to form a curved surface providing different optical aberration correction at different angular positions about the axis <NUM>. For instance, the second surface <NUM> may be non-symmetric along different angular positions about the axis <NUM>. As shown in <FIG>, for instance, the first lens <NUM> may have a plurality of regions <NUM>, each centered about a different angular position θ around the axis <NUM>. Each region <NUM> may have different optical characteristics for applying different corrections for optical aberrations in an eye or vision of the user <NUM>, such as for correcting astigmatism. For instance, a first region 420a is centered about an angular position θ<NUM>, a second region 420b is centered about an angular position θ<NUM>, and so forth, up to a number N regions. Each region <NUM> is shown in <FIG> as being exclusive to the other regions <NUM>; however, this is merely for illustrative purposes and not intended to be limiting. The regions 420a, 420b, 420c,. 420N may overlap each other in at least some embodiments.

In <FIG>, the angular position of the first lens <NUM> is at θ<NUM> such that the optical path <NUM> of the rays <NUM> of virtual image light is through the first region 420a. Accordingly, attributes of the rays <NUM> are modified, at least in part, according to the optical aberration correction characteristics of the first region 420a. The first actuator <NUM> may selectively rotate the first lens <NUM> such that the optical path <NUM> of the rays <NUM> is through a different region than the first region 420a to provide a different optical aberration correction. Each region <NUM> may cause the rays <NUM> of virtual image light <NUM> to refract at angles different than the rays <NUM> would refract at other regions <NUM>. A first surface <NUM> of the first lens <NUM> opposite to the second surface <NUM> may have a different shape than the second surface <NUM> - for instance, the first surface <NUM> may be flat or plano such that the rays <NUM> entering the first lens <NUM> are not refracted.

The second lens <NUM> may have a circular shape similar or identical to the first lens <NUM> a circular shape when viewed from a direction parallel to the optical path <NUM>. The second lens <NUM> may have a first surface <NUM> that receives the rays <NUM> emitted from the first lens <NUM> and a second surface <NUM> that emits the rays <NUM>. The first surface <NUM> may be similar or the same as the second surface <NUM> of the first lens <NUM>. That is, the first surface <NUM> may vary along a width W of the second lens <NUM> to form a curved surface providing different optical aberration correction at different angular positions about the axis <NUM> to refract the rays <NUM> of virtual image light <NUM> in a manner similar to that described with respect to the first lens <NUM>. In some embodiments, the first surface <NUM> of the second lens <NUM> may be complementary to the second surface <NUM> such that the first surfaces <NUM> and <NUM> may be places in contact with one another with no space existing therebetween. In some embodiments, the second surface <NUM> of the second lens <NUM> may have a flat or plano shape that does not refract the rays <NUM> of virtual image light <NUM> incident thereon. The second actuator <NUM> may selectively rotate the second lens <NUM> to cause the optical axis <NUM> to be aligned with a region of the first surface <NUM> corresponding to a particular angular position to correct for an optical aberration of the vision of the user <NUM>, as described above with respect to the first lens <NUM>.

The first actuator <NUM> and the second actuator <NUM> may respectively rotate first lens <NUM> and the second lens <NUM> in concert with each other to achieve a desired optical aberration correction for the vision of the user <NUM>. An angular position θ of the first lens <NUM> and an angular position θ of the second lens <NUM> may be adjusted to provide an optical correction in the virtual image light <NUM> compensating astigmatism of the user's <NUM> vision. The optical correction may correspond to an optical prescription indicating spherical optical power, cylindrical optical power, and an axis of the user's <NUM> eye. The first lens <NUM> and the second lens <NUM> may be operated in concert to satisfy other indications of optical correction than correction for astigmatism. Further, angular positions θ of the first lens <NUM> and the second lens <NUM> may be adjusted such that the set of lenses <NUM> provide no optical correction for a vision condition, such as astigmatism.

In some embodiments, the set of lenses <NUM> may include more than two lenses. For instance, the set of lenses may include one or more additional lenses positioned between the first lens <NUM> and the second lens <NUM>. The one or more additional lenses may each have one or both optical surfaces that have a curvature that varies along the width W of the lenses. As another example, pairs of lenses similar or identical to the first and second lenses <NUM> and <NUM> may be provided before or after the lenses <NUM> and <NUM> along the optical path <NUM>. The additional lens or lenses may have actuators associated therewith for selectively rotating the lens to adjust a region of the lens through which the optical path extends.

<FIG> show an arrangement <NUM> of the first lens <NUM> and the second lens <NUM> according to one or more embodiments. The first lens <NUM> and the second lens <NUM> of the arrangement <NUM> have the same size and shape as the arrangement <NUM> with the exception that the axis <NUM> of the first lens <NUM> is not coaxial with the axis <NUM> of the second lens <NUM>. In some embodiments, one or both of the first lens <NUM> and the second lens <NUM> may be moveable along axes transverse to the optical path <NUM> to adjust attributes of optical aberration correction.

<FIG> shows an exterior <NUM> of the HMD <NUM> according to one or more embodiments. The HMD <NUM> includes a set of straps <NUM> attached to the main body <NUM>. The set of straps <NUM> are useable to selectively and securely mount the HMD <NUM> to the head of the user <NUM> for viewing visual content. The main body <NUM> may include a control panel <NUM> for controlling various aspects of the HMD <NUM>. The control panel <NUM> may include one or more input devices for controlling optical characteristics of the optical system <NUM> to correct the visual content for vision conditions (e.g., myopia, hyperopia, astigmatism) of the user <NUM>. The input devices may be coupled to the first and second actuators <NUM> and <NUM> to respectively control positions of the first lens <NUM> and the second lens <NUM> along the first axis <NUM> and the second axis <NUM>. The input devices may be coupled to the first actuator <NUM> and the second actuator <NUM> to respectively control angular positions of the first lens <NUM> and the second lens <NUM> about the first axis <NUM> and the second axis <NUM>.

The input devices may be mechanical devices that are mechanically coupled to and configured to control corresponding lenses. For instance, the input devices may be knobs or dials that are mechanically linked to actuators of corresponding lenses through, e.g., gears and shafts. Interaction with the mechanical input devices by the user <NUM> may cause a mechanical force to be applied to corresponding actuators to adjust the position of a lens. The input devices may be electrical devices that are electrically coupled to and configured to control corresponding lenses. As an example, the input devices may, in response to interaction by the user <NUM>, cause an electrical signal to be sent to a controller that, in response, sends a control signal to corresponding actuators to adjust positions of the lenses. Non-limiting examples of an electrical input device of the control panel <NUM> include a keypad having a set of keys for providing alphanumeric input or navigating a menu, or a dial or knob that is electrically coupled to a controller that operates one or more actuators. The exterior <NUM> may include a display <NUM> for displaying information regarding the HMD <NUM>, such as current optical settings of the optical system <NUM>. In some embodiments, the display <NUM> may be a touchscreen input device that the user <NUM> may interact with to control the optical system <NUM>.

In some embodiments, the user may adjust the optical settings of the optical system <NUM> in connection with visual content presented by the virtual image display unit(s) <NUM>. For instance, the user wearing the HMD <NUM> may interact with the control panel <NUM> or other input device (e.g., hand-held controller, mouse, keyboard) according to a menu or other visual content displayed by the virtual image display unit(s) <NUM> to adjust the optical settings. As one example, the user may navigate a menu via the control panel <NUM> or other input device and provide user input that causes the optical settings of the optical system <NUM> to be changed in response. As another example, the HMD <NUM> may adjust the optical settings of the optical system <NUM> in real-time in response to user input regarding visual content perceived by the user <NUM>. The user may initiate a visual test on the HMD <NUM> causing the virtual image display unit(s) <NUM> to display visual content, such as test patterns, and prompting the user to provide input regarding clarity of the visual content. As a result of receiving the input, the HMD <NUM> may automatically adjust the optical settings of the optical system <NUM> for improving the clarity of the visual content to improve the user's <NUM> experience.

<FIG> is a block diagram <NUM> showing interconnections of various parts of the HMD <NUM> according to one or more embodiments. The HMD <NUM> includes a controller <NUM> comprising one or more processors <NUM> and memory <NUM> storing a set of instructions that, as a result of execution by the one or more processors <NUM>, cause the HMD <NUM> to perform one or more operations described herein. The memory <NUM> may include read-only memory (ROM) and random access memory (RAM) and may be in the form of solid-state memory or a hard disk drive, by way of non-limiting illustrative example. The HMD <NUM> also includes a communication interface <NUM> electrically coupled to the controller <NUM> for sending and receiving communications with external devices. The communication interface <NUM> may include one or more wireless transceivers, such as Wi-Fi transceivers, cellular transceivers, Bluetooth™ transceivers, etc., that wirelessly send and receive communications to and from external devices, such as a network router or a computing device (e.g., laptop, desktop, tablet, mobile device). The communication interface <NUM> may include a wired communication port, such as a universal serial bus port, a network interface port, or the like, for wired communication with external devices.

The HMD <NUM> may include a set of input devices <NUM> electrically coupled to the controller <NUM> for providing user input to the HMD <NUM>. One or more of the set of input devices <NUM> may be provided on the exterior <NUM> of the HMD <NUM> - for example, as part of the control panel <NUM>. The controller <NUM> may also be electrically coupled to and configured to control the virtual image display units <NUM> and/or the display <NUM> if included. In some embodiments, the controller <NUM> may include one or more graphics processing units for generating the virtual image light <NUM> via the virtual image display units <NUM>.

The controller <NUM> is electrically coupled to the optical system <NUM> and configured to control the optical system <NUM> for adjusting the optical characteristics thereof, as described herein. In particular, the controller <NUM> is electrically coupled to and configured to control a first correction portion <NUM> of the left optical subsystem <NUM>, a second correction portion <NUM> of the left optical subsystem <NUM>, a first correction portion <NUM> of the right optical subsystem 130r, and a second correction portion <NUM> of the right optical subsystem 130r. The first correction portions <NUM> and <NUM> include one of the set of lenses <NUM> and the set of lenses <NUM>, and the second correction portions <NUM> and <NUM> include the other one of the set of lenses <NUM> and the set of lenses <NUM>.

The controller <NUM> is electrically coupled to actuators <NUM> of the correction portions <NUM>, <NUM>, <NUM>, and <NUM> to control the positions of the lenses <NUM> of the optical system <NUM>. Specifically, the controller <NUM> sends signals (e.g., control signals) to the actuators <NUM> causing the actuators <NUM> to move or rotate the lens <NUM> coupled thereto. As described above, the positions (e.g., lateral offsets, angular positions θ) of the lenses <NUM> may be controlled to modify optical characteristics of the first correction portions <NUM> and <NUM> and/or the second correction portions <NUM> and <NUM>. The controller <NUM> may send signals to control the optical subsystem <NUM> in response to receiving input. For instance, the controller <NUM> may adjust the optical characteristics of the optical system <NUM> in response to receiving input provided via the input device(s) <NUM>. As another example, the controller <NUM> may adjust the optical characteristics of the optical system <NUM> in response to receiving an input via the communication interface <NUM>.

The input received by the controller <NUM> may have a particular format. The input may indicate a prescription for the right eye and/or a prescription for the left eye. For each respective eye, the input may indicate a refractive or spherical power (sometimes denoted as SPH or S), a cylinder power (sometimes denoted as CYL or C), and/or an axis (usually between <NUM> and <NUM>). The input may include input for the left optical subsystem <NUM> and the right optical subsystem 130r.

Adjustment of the optical settings of the optical subsystem <NUM> may be adjusted in real-time through feedback provided by the user <NUM>. The controller <NUM> may initiate a test to determine adjustments to make to the optical settings of the optical system <NUM>. The test may involve causing the virtual image display unit(s) <NUM> to display particular visual content, such as a test pattern or a detailed visual image, and prompting the user to provide feedback via the input device(s) <NUM> or the control panel <NUM>. The user <NUM> may provide feedback indicating that aspects (e.g., text, images) of the visual content appear unclear. The controller <NUM> may adjust the optical settings of the optical system <NUM> and ask the user <NUM> whether the adjustments improved clarity of the aspects of the visual content. This process may be iterated until the user <NUM> is satisfied with the clarity of the visual content. The test may be performed in response to receiving user input from a user <NUM> via an input device <NUM> or the control panel <NUM>.

Input over the communication interface <NUM> may be provided by a device (e.g., laptop, desktop, mobile device, controller) as a result of user interaction. The computing device may include a set of instructions (e.g.,. application, program) that the user can interact with to cause the computing device to send communications including information indicating or representative of optical characteristics for modifying the virtual image light <NUM> to correct for the user's <NUM> vision conditions. The user may enter the input into the input device <NUM> or the computing device as a prescription provided by a medical professional and may have a predetermined format, as described above.

The controller <NUM> may, in response to receiving the input from the input device(s) <NUM> or the communication interface <NUM>, determine signals to send to the actuators <NUM>. One or more of the processors <NUM>, for example, may access a data structure stored in the memory <NUM> indicating control signals to be sent to corresponding actuators <NUM>. The data structure may be an array, lookup table, or other referential structure in which input data is associated with the corresponding output (i.e., control signal) to be sent to particular actuators <NUM>. In some implementations, the controller <NUM> may store information in the memory <NUM> indicating a current state of the optical system <NUM> (e.g., current states of the actuators <NUM>) from which the controller <NUM> may determine adjustments to the actuators <NUM> to be made to satisfy the input received.

In some embodiments, the HMD <NUM> may be configured to detect vision conditions of the user's eyes <NUM> and 105r and automatically adjust the optical system <NUM> as a result of the detection. In such embodiments, the HMD <NUM> may include one or more sensors <NUM> that detect information regarding the user's eyes <NUM> and 105r and provides measurements to the controller <NUM>, which adjusts the optical system <NUM> accordingly. The HMD <NUM> may also include one or more lighting elements <NUM> coupled to the controller <NUM> for use in connection with the sensor(s) <NUM> for obtaining information. The light emitting element(s) <NUM> may emit light at an angle and having certain characteristics (e.g., frequency, intensity) such that the light is reflected and received by the sensor(s) <NUM>. The sensor(s) <NUM> may determine, based on the light detected from the user's eye, information about the user's eyes. As a result of the information determined regarding the user's <NUM> eyes, the controller <NUM> may adjust the optical characteristics of the optical system <NUM> accordingly. Such information may include information indicating a topology of the cornea, which the controller <NUM> may process to determine control signals to be sent to the actuators <NUM> for adjusting the optical system <NUM> so that the user <NUM> can resolve the virtual image light <NUM> as clear visual content.

<FIG> shows an embodiment of an HMD <NUM> according to the claimed invention, having an optical subsystem <NUM> that is selectively installable in and removable from the HMD <NUM>. In particular, the HMD <NUM> has a cavity <NUM>, provided between a front portion <NUM> and a viewing portion <NUM>, sized and shaped to receive the optical subsystem <NUM>. The optical system <NUM> has a body <NUM> sized and shaped to snuggly fit within the cavity <NUM>. The optical system <NUM> contains the left and right optical subsystems <NUM> and 130r (<FIG>) each comprising one or both of the first correction portion <NUM> and the second correction portion <NUM> described herein. The HMD <NUM> is configured to securely and selectively retain the optical system <NUM> upon insertion of the body <NUM> therein. The body <NUM> may, for instance, have a fastener or other feature <NUM> that engages with a corresponding feature within the cavity <NUM> to retain the optical subsystem <NUM> once inserted in the cavity <NUM>. The HMD <NUM> may, in some implementations, have a set of doors <NUM> that open to allow insertion of the optical system <NUM>, but which remain closed otherwise to prevent dust and debris from entering the HMD <NUM>.

A front side <NUM> of the body <NUM> includes a receiving portion <NUM> for receiving virtual image light <NUM> from the virtual image display units <NUM>, as described above. A back side <NUM> of the body <NUM> includes left and right emitting portions <NUM> and 206r for emitting the corrected virtual image light <NUM> for viewing by the user <NUM>. The optical subsystem <NUM> has one or more electrical contacts <NUM> exposed on an exterior surface sized and shaped to engage with corresponding electrical contacts within the cavity <NUM> for establishing an electrical connection through which signals and power may be transmitted to actuators of the optical system <NUM>.

In some embodiments, the optical system <NUM> may include a controller independent of the controller <NUM> for sending control signals to the actuators <NUM>. The independent controller of the optical system <NUM> may receive signals or information from the controller <NUM> or the communication interface <NUM> and adjust the optical characteristics of the left and right optical subsystems <NUM> and 130r according to the signals or information received. In some instances, the user <NUM> may interact with input devices <NUM> provided on an exterior of the HMD <NUM> to adjust the optical characteristics, as described above with respect to the control panel <NUM>.

Claim 1:
A head-mounted display device (<NUM>; <NUM>), comprising:
a frame (<NUM>) comprising a cavity (<NUM>);
a virtual image display device (<NUM>) coupled to the frame (<NUM>) and configured to generate virtual image light (<NUM>) for causing a user (<NUM>) to perceive visual content;
and
an optical system (<NUM>) that is selectively removably insertable into the cavity (<NUM>) of the frame (<NUM>) and, when inserted into the cavity (<NUM>), the optical system (<NUM>) is located along an optical path (<NUM>) of rays (<NUM>) of the virtual image light (<NUM>), the optical system (<NUM>) comprising:
a first correcting portion (<NUM>; <NUM>) having a left optical subsystem (<NUM>) and a right optical subsystem (130r), each of the left and right optical subsystems (<NUM>, 130r) of the first correcting portion (<NUM>; <NUM>) including:
one or more actuators (<NUM>, <NUM>); and
a first set of lenses (<NUM>, <NUM>) positioned at a first location along the optical path (<NUM>) and having first optical characteristics correcting for a first set of vision conditions, at least one of a first lens (<NUM>) and a second lens (<NUM>) of the first set of lenses (<NUM>, <NUM>)
being selectively adjustable relative to the other of the first lens (<NUM>) and the second lens (<NUM>) of the first set of lenses (<NUM>, <NUM>), via the one or more actuators (<NUM>, <NUM>), along
a first axis (<NUM>) transverse to the optical path (<NUM>) to modify the first optical characteristics; and
one or more electrical contacts (<NUM>) exposed on an exterior surface of the optical system (<NUM>), the one or more electrical contacts (<NUM>) sized and shaped to engage with corresponding electrical contacts within the cavity (<NUM>) of the frame (<NUM>) to establish an electrical connection through which signals and power may be transmitted to the one or more actuators (<NUM>, <NUM>) of the optical system (<NUM>).