Patent Description:
<CIT> discloses a device for adjusting alignment of a near-eye optic of a see-through head-mounted display system. In one embodiment, a method of detecting eye location for a head-mounted display system includes directing positioning light to an eye of a user and detecting the positioning light reflected from the eye of the user. The method further includes determining a distance between the eye and a near-eye optic of the head-mounted display system based on attributes of the detected positioning light, and providing feedback for adjusting the distance between the eye and the near-eye optic.

<CIT> discloses eye-tracked head-mounted displays which, in one aspect, may utilize the same optics for eyetracking and image viewing, with a selected portion of the optics used for an eyetracking optical path and a selected portion of the display optics used for an image viewing optical path.

<CIT> discloses a video image display device with an ocular optical system that guides video image light from a display element to the pupil of an observer through an ocular prism and at the same time guides ambient light to the pupil of the observer through the ocular prism. The eyepiece optical system has reflection planes set in the ocular prism that are provided with three or more planes to fold down three or more times an optical path for the video image light from the display element, wherein an HOE is formed on at least one plane of the reflection planes. The video image display device satisfies a conditional equation that properly prescribes the relationship between an incident range of the video image light incident on the HOE formed plane in the ocular prism and a display screen size of the display element. Thus, the video image display device can widely secure both a video image observation area and a see-through area with a small compact structure.

<CIT> discloses a display apparatus including a light guide system that includes a light-incident portion including a light-incident curved surface on which image light beams as non-parallel light beams are incident and a light-reflective curved surface which reflects the image light beams such that the image light beams are converted into parallel light beams, and a light guide portion being a portion in which a plurality of partial reflection layers are disposed in parallel. The light guide portion is filled with a parallel light flux emitted from the light-incident portion. The light-incident portion is formed of a first transparent member, the portion in which the partial reflection layers are formed is formed of a second transparent member which is surface-bonded to the first transparent member via a bonding surface, and the bonding surface is inclined in the same direction as that of the partial reflection layer.

Electronically enhanced eyewear devices have multiple practical and leisure applications but many of these applications are limited due to cost, size, weight, thickness, field of view, and efficiency of optical systems used to implement existing eyewear devices. For example, use of conventional components typically yields a CGI of only a few degrees width and a few degrees of height, resulting in a poor user experience. Previous eyewear designs have attempted to address these issues by employing curved lightguides in conjunction with a micro-display positioned in a temple region of a head wearable frame similar to a conventional pair of glasses. However, based on the particular geometry and physical constraints of these designs, the lightguide restricts a light path to so as to implement the concealing of the optics within the temple region. In addition, conventional constraints in positioning the components of certain eyewear devices lead to low field of view (FOV) displays.

Some eyewear devices having a micro-display ("display") are prone to leaking light outside of the device and thereby inadvertently announce the use of an electronic device. Further, some electronically-enhanced eyewear devices require a lightguide length longer than desired. For example, when the display is at the temple location, the lightguide is often required to be tilted at a relatively high angle (e.g.<NUM> degrees or more) so as to facilitate total internal reflection (TIR) of the display light within the lightguide. These and other constraints yield a low field of view (FOV) display (e.g., on the order of approximately ten degrees diagonal or less).

The proposed solution relates to an optical device of claim <NUM>.

Some embodiments described herein relate to orienting the display of an eyewear device toward the eye-side of the device and re-use of world-side and eye-side optical components to magnify the display light. The resulting eyewear device has an appearance of regular, non-electronic eyewear - e.g., an appearance of conventional glasses - while simultaneously augmenting an image from the display for improved viewing of information. The eyewear device is able to accommodate prescriptive adjustments to vision with a lens positioned at an eye-side of a frame and incorporate a display within a top portion of the frame where the display generates an image that supplements a world view with text, images, icons, and the like.

A particular feature of some of the embodiments is that a display is oriented to first emit light towards the user wherein the display and other components are sealed from dust and held in place inside the frame such that little to no light from the display leaks to the world-side of the device. This arrangement helps to hold the components in alignment with one another and makes it difficult for an observer to identify if someone is wearing an electronically-enhanced optical system. The arrangement of components makes thinner temples of the eyewear possible and a conventional eyewear arm hinge can be used. When display properly light emerges from the lightguide, the device reuses a base curvature of a curved prescription lens or sunglass to augment the display light, which makes some embodiments desirable in many environments. Many existing forms of state-of-the-art AR-based eyewear devices use flat lightguides and do not accommodate vision correction. Here, use of curved lens surfaces in the lightguide creates a thin, lightweight eyewear device that accommodate a corrective lens in the frame along with the lightguide without substantively enlarging the overall size of the optical device.

The proposed solution in particular relates to an optical device that includes a display oriented toward an eye-side of the optical device and the display is configured to emit light toward the eye-side of the optical device based on an input signal. The optical device further includes a lightguide, a reflector, and a head mountable frame. The lightguide includes a curved first surface at the eye-side of the optical device. A curved second surface reflects the light through the curved first surface to a user eye. The reflector includes a reflective surface positioned at the eye-side relative to the display above at least one of the curved first surface and the curved second surface of the lightguide. The reflector is positioned to reflect light from the display into the lightguide. The head mountable frame supports the display, the reflective surface, and the lightguide, and the display is positioned at a top of the head mountable frame.

In an exemplary embodiment, the optical device further includes a field lens having a first surface to receive light from the reflector and a second surface oriented toward an interior of the lightguide. The field lens is positioned at a top side of the lightguide. The second surface of the field lens, oriented toward the lightguide, is, for example, spherical in shape.

The display, the lightguide, and the reflector may be positioned so as to reflect light at least two times from at least one of the curved first surface and the curved second surface of the lightguide before the light from the display reaches the user eye.

In an exemplary embodiment, the lightguide includes a third surface at a top of the lightguide for receiving light from the reflector.

In an exemplary embodiment, a surface of the field lens, the lightguide, or both the field lens and the lightguide may be shaped to correct an astigmatism of a computer-generated image (CGI) of the light from the display in at least one of a first dimension and a second dimension, the dimensions being orthogonal to each other or not, as the light progresses from the display toward the user eye.

In an exemplary embodiment, the display is mounted to the head mountable frame and fits within a region having a height that is <NUM> or less above a top edge of the lightguide.

In an exemplary embodiment, the display includes at least <NUM> vertically arranged pixel rows.

In an exemplary embodiment, the arrangement of the display, the reflector, and the lightguide are arranged in the optical device to provide at least a <NUM> degree diagonal field of view with respect to a resulting image from the display.

In an exemplary embodiment, the arrangement of the display, the reflector, and the lightguide are arranged in the optical device to provide at least a <NUM>:<NUM> horizontal-to-vertical aspect ratio with respect to a resulting image from the display.

In an exemplary embodiment, a distance between the curved first surface at the eye-side of the optical device and the curved second surface of the lightguide is <NUM> or less along a cross-section of the lightguide.

In an exemplary embodiment, an eye relief distance from the curved first surface of the lightguide to the user eye is <NUM> or less.

In an exemplary embodiment, the optical device provides a wrap angle of at least two degrees.

In an exemplary embodiment, a top edge of a resulting image is located at least two degrees below a center axis of a pupil of the user eye.

In an exemplary embodiment, a top edge of a resulting image is located at least two degrees above a center axis of a pupil of the user eye.

In an exemplary embodiment, a resulting image from the display is oriented with at least two degrees of pantoscopic tilt relative to the user eye.

In an exemplary embodiment, a fourth surface of the lightguide is spherical having a spherical dimension between <NUM> and <NUM> of curvature.

In an exemplary embodiment, the curved second surface of the lightguide includes a combiner for a resulting image from the display, where the resulting image is from the display and a world view form a combined view for observing by the user eye. Generally, the lightguide, the display, a field lens, and the reflector may be positioned in front of a user's eye such that a combiner surface of the combiner is in front of the user's eye and the combiner surface is at or near an intersection of the lightguide and an optical axis extending horizontally from a center of the pupil. The combiner surface may have a non-planar combiner curvature.

In an exemplary embodiment, the optical device may include a filler piece having a first surface shaped to conform to a world-side fourth surface of the lightguide and shaped to fit into a recess (aperture) in the lightguide, wherein the filler piece has a second surface shaped to conform to the curved second surface of the lightguide. For example, on an eye-side of the filler piece, a first matching surface of the filler piece may be shaped to match a combiner curvature of a combiner surface of a combiner aperture of the lightguide. In such an embodiment, display light from the display and ambient light from the world-side of the lightguide are combined in or near the combiner aperture.

In an exemplary embodiment, the first and second curved surfaces are transparent and the lightguide may further include a transparent third surface oriented toward the top of the head wearable frame for receiving display light, the display light reflecting inside the lightguide via total internal reflection. A transparent curved fourth surface is shaped to reflect light from the display through the transparent curved first surface to a user eye and to combine the display light with ambient light entering from the world-side through the transparent curved second surface of the lightguide, wherein the reflector is positioned on the eye-side of the apparatus and oriented to direct light from the display into the lightguide through the transparent third surface.

In such an embodiment, the optical device may include a display lens positioned at the top of the lightguide, wherein a first surface of the display lens is oriented toward the third surface of the lightguide, and wherein the first surface of the display lens is curved in a freeform manner along a first axis and the first surface of the display lens is curved along a second axis perpendicular to the first axis thereby augmenting a resultant image area in at least one dimension at the transparent curved fourth surface of the lightguide. Additionally, a curvature of the transparent curved fourth surface of the lightguide may be freeform along at least one axis, and light from the display may be reflected at least two times by internal reflection from each of the curved first and second surfaces of the lightguide before reflecting from the transparent curved fourth surface and then the light may be transmitted through the transparent curved first surface on the eye-side of the lightguide toward a user eye. Additionally or alternatively, a curvature of the transparent curved third surface of the lightguide may be freeform along at least one axis thereby augmenting a resultant image area in at least one dimension at the transparent curved fourth surface of the lightguide.

The proposed solution further relates to an apparatus including a display positioned at a top of a head wearable frame (of the apparatus) and oriented toward an eye-side of the apparatus. A lightguide directs light from the display toward an eye-direction. A reflector is positioned on the eye-side of the apparatus. The lightguide includes a transparent curved first surface on the eye-side of the lightguide, a transparent curved second surface on a world-side of the lightguide, and a transparent third surface oriented toward the top of the head wearable frame for receiving display light. The display light reflects inside the lightguide via total internal reflection. A transparent curved fourth surface is shaped to reflect light from the display through the transparent curved first surface of the lightguide to a user eye and combines the display light with ambient light entering from the world-side through the transparent curved second surface of the lightguide. The reflector is oriented to direct light from the display into the lightguide through the transparent third surface.

In an exemplary embodiment, a display lens may be positioned at the top of the lightguide, wherein a first surface of the display lens is oriented toward the third surface of the lightguide, and wherein the first surface of the display lens is curved in a freeform manner along a first axis and the first surface of the display lens is curved along a second axis perpendicular to the first axis thereby augmenting a resultant image area in at least one dimension at the transparent curved fourth surface of the lightguide. In such an embodiment, a curvature of the transparent curved fourth surface of the lightguide may be freeform along at least one axis, and light from the display may be reflected at least two times by internal reflection from each of the curved first and second surfaces of the lightguide before reflecting from the transparent curved fourth surface and being transmitted through the transparent curved first surface on the eye-side of the lightguide toward a user eye. Additionally or alternatively, a curvature of the transparent curved third surface of the lightguide is freeform along at least one axis thereby augmenting a resultant image area in at least one dimension at the transparent curved fourth surface of the lightguide.

<FIG> illustrates a perspective view of an optical device in the form of an eyewear device <NUM> in accordance with some embodiments. The device <NUM> broadly illustrates components of eyewear devices further described herein. The device <NUM> includes one or a pair of lightguides <NUM> mounted in a frame <NUM>. The frame <NUM> secures the lightguides <NUM> between a top side <NUM> and a bottom side <NUM> thereof. The frame <NUM> is shaped into a form similar to an ordinary pair of eyeglasses. Generally, the lightguide <NUM> is transparent and operates as a lens for viewing in front of a user and for directing light of a display <NUM> toward the user eye thereby providing an AR-based view from the device <NUM>.

For a single display <NUM>, a lightguide <NUM> includes a surface having a dielectric mirror coating that acts as a combiner <NUM> that reflects light <NUM> originating from the display <NUM>. The display <NUM> is mounted above a top edge <NUM> of one of the lightguides <NUM> at the top side <NUM> of the frame <NUM>. The lightguide <NUM> allows ambient light <NUM> from a world-side <NUM> to pass through to the eye-side <NUM> of the lightguide <NUM> and the dielectric mirror coating of the combiner <NUM>. The frame <NUM> includes two arms <NUM> that extend from a temple location of the frame <NUM> on respective sides of the frame <NUM> toward and over ears of a user (not illustrated). In some embodiments, one arm <NUM> houses a cord <NUM> to power the various components including the display <NUM> and its package and to provide an image data signal to the display <NUM> from a computing device or other display driving data source (not illustrated). In other embodiments, at least one arm <NUM> includes or houses components to receive and provide the signal wirelessly to the display <NUM>. Power is provided by a battery or other form of energy local to the device <NUM> or from a source external to the device <NUM>.

The placement of the display <NUM> in an eye-ward orientation at the top of the lightguide <NUM> is supported by various features of the lightguide <NUM> such as having a curved eye-side (first) surface <NUM> and a curved world-side (second) surface <NUM>.

According to certain embodiments, these curved surfaces <NUM>, <NUM> are spherical, and each of these curved surfaces <NUM>, <NUM> has a similar or approximately a same sized characteristic dimension (e.g., spherical dimension, radius, set of curvature parameters) as each other so as to implement zero optical power (diopter) optical see-through. The curved world-side surface <NUM> is a second surface and the eye-side surface <NUM> is a first surface. A surface at a top of the lightguide <NUM>, according to certain embodiments, is freeform so as to correct for astigmatism, if any, with respect to the display <NUM> and light emitted therefrom. The surface at the top of the lightguide <NUM> is a third surface of the device <NUM>.

Another surface of the lightguide <NUM> provides a final reflection of light from the display <NUM> toward a user eye, and the surface is also curved in a freeform manner in at least some embodiments. This final surface is referred to herein as a combiner <NUM> or combiner surface. The image reflected therefrom is referred to as a light field and is provided to the user eye. In other embodiments, the final surface of the lightguide <NUM> is a rotationally symmetric aspherically-shaped surface, an anamorphic aspherically-shaped surface, a toroid-shaped surface, a Zernike polynomial-shaped surface, a radial basis function-shaped surface, an x-y polynomial-shaped surface, or a non-uniform rational b-spline-shaped surface. In some embodiments, at least the surfaces of the lightguide <NUM> of the device <NUM> operate as an optical magnifier for the light emitted from the display <NUM>. The described techniques are applicable to all types of see-through devices, such as eyeglasses, helmets, head-mounted display (HMD) devices and windshields and enable optical merging of computer generated and real-world scenes to form a combined view. A thickness of certain embodiments of the lightguide <NUM> is up to approximately <NUM>. Parts of the optics, including the display <NUM>, take up about <NUM> of space hidden in the rim of a top of the frame <NUM> of the device <NUM>. To lighten a weight of the eyewear device <NUM>, some embodiments are monocular as illustrated - a device <NUM> with a single lightguide <NUM> and one display <NUM>.

<FIG> illustrates a front view <NUM> of a rim frame portion <NUM> of the eyewear device <NUM> in accordance with some embodiments. By way of example, the rim frame portion <NUM> provides prescriptive support of between approximately -4D and +2D, with D referring to diopters, for a user as the user is provided with augmented reality vision through the lightguide <NUM>. Dimensions of the device <NUM> are based on a pupil diameter <NUM> of approximately <NUM> positioned relative to a pupil center <NUM>. Each of the lightguides <NUM> for the left and right eyes (not illustrated) are based on a frame horizontal box distance <NUM> of approximately <NUM> and a frame vertical box distance <NUM> of approximately <NUM>. The lightguides <NUM> are separated by a bridge length <NUM> of approximately <NUM>. The bridge length <NUM> is generally centered at a medial position <NUM> when the device <NUM> is worn by the user. A fitting height <NUM> is a distance from the bottom side <NUM> toward the top edge <NUM> of the lightguide <NUM> and the fitting height is approximately <NUM> to the pupil center <NUM>. The rim frame portion <NUM> is based on an inter-pupillary distance (IPD) of approximately <NUM>.

Some embodiments of the lightguides <NUM> are oriented with a pantoscopic tilt up to approximately <NUM> degrees. The frame portion <NUM> positions one or two curved lightguides <NUM> at a wrap angle up to approximately <NUM> degrees with some embodiments having a wrap angle of approximately <NUM> degrees with respect to a planar field of view in front of the user. In some embodiments, a base curve of the frame is approximately <NUM> (<NUM> R). A top portion of the rim frame portion <NUM> has a thickness <NUM> of up to <NUM> with some embodiments having a thickness <NUM> of <NUM> or less. In a particular embodiment, the display inside of the top portion of the frame <NUM> provides an image of about a <NUM>:<NUM> ratio width-to-height. The corresponding thickness is approximately <NUM> of head space. For a display <NUM> producing an image of about a <NUM>:<NUM> ratio width-to-height, the head space is up to approximately <NUM>.

<FIG> illustrates a side cross-sectional view <NUM> of a lightguide <NUM>, a display <NUM>, a field lens <NUM>, and a reflector in the form of a mirror <NUM> along line <NUM>-<NUM> of <FIG> in accordance with some embodiments. The view <NUM> illustrates the orientation of various components of a device like the eyewear device <NUM> with respect to an eye <NUM> of a user <NUM>. In the view <NUM>, a frame like the frame <NUM> is not shown for sake of clarity of illustration and numbering. The display <NUM> is oriented toward the eye-side <NUM> of the lightguide <NUM>. The display <NUM> generates display light <NUM> toward the mirror <NUM>. The display light <NUM> travels along a light path <NUM> toward the eye <NUM> and its pupil <NUM>. A profile of a nose <NUM> in front of the eye <NUM> is visible and shows the device components relative thereto. While one eye <NUM> is shown, it is understood that a similar set of components is provided for a second eye of the user <NUM> as shown in other figures when a second screen and lightguide are provided.

In the view <NUM>, the lightguide <NUM>, the display <NUM>, the field lens <NUM>, and the mirror <NUM> are positioned in front of the eye <NUM> as shown such that a combiner surface <NUM> is in front of the eye <NUM> and the combiner surface <NUM> is at an intersection of the lightguide <NUM> and an optical axis <NUM> extending horizontally from a center of the pupil <NUM>. The combiner surface <NUM> has a non-planar combiner curvature <NUM>. The display <NUM>, the field lens <NUM>, and the mirror <NUM> fit within the device rim thickness <NUM> that is <NUM> or less.

In some embodiments, a center of a combiner area or resultant image producing area (not illustrated) within the combiner surface <NUM> provides a resultant image for the eye <NUM> and is positioned at a first angle <NUM> below the optical axis <NUM> as measured at a center of the image. In some embodiments, the first angle <NUM> is within <NUM>-<NUM> degrees such as at approximately <NUM>-<NUM> degrees. Horizontally (perpendicular to the view <NUM>), the center of the resultant image is approximately <NUM>-<NUM> degrees offset with respect to a center of the eye <NUM> at rest. For a right eye, the horizontal offset is to the right of the optical axis <NUM>, and for a left eye, the horizontal offset is to the left of the optical axis <NUM>. Ambient light <NUM> from the world-side <NUM> of the lightguide <NUM> passes through the lightguide <NUM>, including the combiner surface <NUM>, and into the pupil <NUM> and the eye <NUM>.

From the display <NUM>, the display light <NUM> first passes to, and is reflected by, a surface of mirror <NUM> before reaching the field lens <NUM>. In some embodiments, the field lens <NUM> is mounted to or held in place by one or more of the frame and the lightguide <NUM>. The field lens <NUM> is made of a same or a different material than a material of the lightguide <NUM>. Based on these materials, one or more of the field lens <NUM> and the lightguide <NUM> provide a color correction to one or more of the display light and the ambient light <NUM> in the eyewear device <NUM>. For example, the display light is corrected for the eye <NUM> such that color separation in the display light <NUM> as this light <NUM> travels through the optics is magnified less than <NUM> arcminutes before reaching the eye <NUM>. In some embodiments, this adjustment is less than <NUM> arcminutes based on geometries of the components and materials of manufacture of the components between the display <NUM> and the eye <NUM>.

The field lens <NUM> is also referred to as a prism and is a component having one, two, or more features that direct light to a desired location and with one or more desired characteristics. For example, in some embodiments, a first surface <NUM> of the field lens <NUM> is curved along a first axis, along a second axis (e.g., perpendicular to the page containing <FIG>), or along both a first axis and a second axis. As another example, the first surface <NUM> is spherical or freeform along one or more of these axes. According to some embodiments, the first surface <NUM> is positioned at a third angle <NUM> of approximately <NUM> degrees above the optical axis <NUM>. The display light <NUM> passes through a body of the field lens <NUM> and out a second surface opposite of the first surface <NUM>. The second surface is curved along a first axis, along a second axis, or along both a first axis and a second axis. For example, the second surface is spherical or freeform along one or more of the axes.

Further, the field lens <NUM> is made of a first material and the lightguide <NUM> is made of a different second material. For example, the first material is a plastic material and the second material is a glass material, or a synthetic resin material such as Zeonex® E48R. According to some embodiments, a combination of the first material and the second material causes a color correction of the display light <NUM> by the time the display light <NUM> reaches the eye <NUM>. For sake of clarity, only a single ray of display light <NUM> is shown within the lightguide <NUM> in the view <NUM>. While not illustrated, one or more of the components in the light path <NUM> - such as the display <NUM>, the mirror <NUM>, the field lens <NUM>, and the lightguide <NUM> - include one or more coatings for affecting a quality or a quantity of the display light <NUM> reaching the eye <NUM>. The field lens <NUM> directs the display light <NUM> into an incoupler <NUM> of the lightguide <NUM> or a gap between a world-side (second) surface <NUM> and an eye-side (first) surface <NUM> of the lightguide <NUM>. The angles of reflection as illustrated do not necessarily reflect actual angles of reflection between the surfaces <NUM>, <NUM>.

In some embodiments, the incoupler <NUM> is flat or curved where a curvature is spherical or freeform in contour along a first axis, along a second axis, or along both a first axis and a second axis at a top position of the lightguide <NUM>. The curvature of the incoupler <NUM> corrects some or all of an astigmatism in the resulting CGI formed at the combiner surface <NUM>. According to some embodiments, the resulting CGI or FOV thereof is approximately <NUM> degrees horizontal and <NUM> degrees vertical relative to the eye <NUM> and the pupil <NUM>. In other embodiments, the FOV has an aspect ratio width-to-height with the horizontal size being approximately <NUM> degrees and the vertical size being approximately <NUM> degrees.

The lightguide <NUM> includes the world-side (second) surface <NUM> having a world-side curvature <NUM> and an eye-side (first) surface <NUM> having an eye-side curvature <NUM>. The world-side surface <NUM> and the eye-side surface <NUM> are formed or otherwise positioned relative to the incoupler <NUM> so as to allow for total internal reflection of the display light <NUM> between the two surfaces <NUM>, <NUM> as the light <NUM> travels between the top of the lightguide <NUM> and the combiner surface <NUM>. Display light <NUM> enters the incoupler <NUM> within approximately <NUM> degrees of a normal of the incoupler <NUM>. The display light <NUM> reflects from each of the two surfaces <NUM>, <NUM> one or more times on each surface <NUM>, <NUM> before reflecting from the combiner surface <NUM> when traveling toward the eye <NUM>. In certain embodiments, the display light <NUM> has at least two total internal reflection interactions with the surfaces of the lightguide <NUM> such as the surfaces <NUM>, <NUM>. In many embodiments, the two surfaces <NUM>, <NUM> are positioned within about <NUM> of each other. In certain embodiments, the lightguide thickness <NUM> is approximately <NUM> or less horizontally as measured at any point along the lightguide <NUM> from a top to a bottom of the lightguide <NUM>, but the lightguide thickness <NUM> can vary as needed depending on the various components used and the orientations of these components to create a final AR image by way of the lightguide <NUM>. The lightguide thickness <NUM> as used herein is a distance between the world-side surface <NUM> and a closest point or a point opposite at the eye-side surface <NUM>.

According to some embodiments, along the world-side surface <NUM>, the world-side curvature <NUM> includes a first spherical curvature <NUM> having a radius between <NUM>-<NUM> at the eye-side. Along the eye-side surface <NUM>, the eye-side curvature <NUM> includes a second spherical curvature <NUM> having a radius between <NUM>-<NUM> at the eye-side. In some embodiments, the first spherical curvature <NUM> is approximately <NUM> and the second spherical curvature <NUM> is approximately <NUM>. In other embodiments, a base curvature of the curvatures <NUM>, <NUM> is approximately <NUM> diopters. An efficiency of the device <NUM>, from the display <NUM> to the eye <NUM>, is approximately <NUM> percent. In arcminutes, an acuity is approximately <NUM>. A chief ray telecentricity, as measured at a center pixel of the display <NUM>, is approximately <NUM> degrees. An eye relief distance <NUM> between the lightguide <NUM> and a front (cornea) of the eye <NUM> is approximately <NUM>.

The combiner surface <NUM> of the lightguide <NUM> is positioned at a second angle <NUM>, a pantoscopic tilt angle, relative to a vertical axis in front of the eye <NUM>. According to some embodiments, the second angle <NUM> is measured from the vertical axis to a point within the resultant image reflected from, and relative to, the combiner surface <NUM>. By way of example, the second angle <NUM> is measured relative to a center of the resultant image from the display <NUM> reflected from the combiner surface <NUM>. As another example, the second angle <NUM> is measured relative to a center of the combiner surface <NUM> of the lightguide <NUM>. In some embodiments, the second angle <NUM> is approximately <NUM>-<NUM> degrees. A combined angle <NUM>, taking the various configurations of all elements of the device <NUM> into account, including the first angle <NUM> and the second angle <NUM> relative to a vertical axis in front of the eye <NUM>, is approximately <NUM>-<NUM> degrees. A first lightguide <NUM> is provided for a first (right) user eye, and a second lightguide is provided for a second (left) user eye. Each of the first and second lightguides in the device <NUM> is wrapped approximately five degrees from a view axis thereby resulting in an overall wrap angle of approximately <NUM> degrees for the device <NUM>. According to some embodiments, a wrap angle is at least two degrees relative to the view axis.

According to some embodiments, spherical radii of curvature of spherical surfaces of the lightguide <NUM> are designed such that an optical power thereof sums to zero (i.e., each light guide is a zero power shell). In other embodiments, the spherical radii of curvature optically enlarge light passing through the lightguide <NUM>. As shown in other figures, a see-through shell is maintained a small distance from the lightguide resulting in an aesthetically pleasing eyewear device that provides a substantially enlarged image relative to conventional devices and image viewing systems.

<FIG> illustrates a side cross-sectional view <NUM> of the lightguide <NUM>, the display <NUM>, and a reflector <NUM> along line <NUM>-<NUM> of <FIG> in accordance with some embodiments. The view <NUM> illustrates the orientation of various components of a device like the eyewear device <NUM> with respect to the eye <NUM> of the user <NUM>. In the view <NUM>, a frame like the frame <NUM> is not shown for sake of clarity of illustration and numbering. The display <NUM> is oriented toward the eye-side <NUM> of the lightguide <NUM>. The display <NUM> generates display light <NUM> toward the reflector <NUM>. The display light <NUM> travels along a light path <NUM> toward the eye <NUM> and its pupil <NUM>. For reference the profile of the nose <NUM> is visible and shows the device components relative thereto. The display <NUM> and the reflector <NUM> fit within the device rim thickness <NUM> that is approximately <NUM> or less. In certain embodiments, the reflector <NUM> is in addition to a field lens such as the field lens <NUM> in the device shown in the view <NUM>. The reflector <NUM>, the field lens <NUM>, and/or the lightguide <NUM> operate together as a magnifier of the display light <NUM> when creating an image from the display <NUM> for the user <NUM>. The lightguide thickness between the world-side surface <NUM> and a closest point at the eye-side surface <NUM> is up to approximately <NUM>.

In the view <NUM>, the lightguide <NUM>, the display <NUM>, and the reflector <NUM> are positioned in front of the eye <NUM> as shown such that the combiner surface <NUM> is in front of the eye <NUM> and the combiner surface <NUM> is at an intersection of the lightguide <NUM> and the optical axis <NUM> through the pupil <NUM> and the eye <NUM>. In some embodiments, a center of a resultant image producing area <NUM> is within the combiner surface <NUM>. The combiner surface <NUM> has a combiner curvature <NUM> in one or two dimensions relative to the user <NUM>. The center of the image producing area <NUM> is below an intersection of the optical axis <NUM>. At least a point in the image producing area <NUM> is located generally an image producing angle <NUM> and this point is on the combiner surface <NUM>. For example, the image producing angle <NUM> is at approximately <NUM> degrees. The angle <NUM> is also referred to as a combiner tilt angle. This angle <NUM> is also referred to as a combiner tilt angle and, in some instances, is determined as an average of angles at points within the image producing area <NUM>. Ambient light <NUM> from the world-side <NUM> of the lightguide <NUM> passes through the lightguide <NUM>, including the combiner surface <NUM>, and into the pupil <NUM> and the eye <NUM>.

From the display <NUM>, the display light <NUM> first passes into a first planar surface <NUM> of the reflector <NUM> and is subsequently reflected by a second planar surface <NUM> of the reflector <NUM> before the light <NUM> reaches a top (third) surface <NUM> of the lightguide <NUM>. The top surface <NUM> of the lightguide <NUM> is also referred to as an incoupler surface of the lightguide <NUM>. In some embodiments, the top surface <NUM> is planar and is positioned at an incoupler tilt angle <NUM> of approximately <NUM> degrees. The orientations and positions of the display <NUM> and the reflector <NUM> with respect to the lightguide <NUM> are arranged so as to cause total internal reflection of display light <NUM> within the lightguide <NUM>. The total internal reflection occurs, for example, two times from an eye-side <NUM> of the lightguide <NUM> and two times from the world-side <NUM> of the lightguide <NUM> and thereby achieves two total internal reflections in the lightguide <NUM>. Further, a shape of the reflector <NUM> and the orientations of the surfaces <NUM>, <NUM> of the reflector <NUM> are selected and formed so as to produce a desired quality, size, shape, and position of a resulting image at the image producing area <NUM> of the lightguide <NUM>. In some embodiments, planes of the planar surfaces <NUM>, <NUM> are not parallel with each other. Yet further, a material is selected for each of the reflector <NUM> and lightguide <NUM>. As an example, the reflector <NUM> is made of a first material and the lightguide <NUM> is made of a different second material. In this example, the first material is a borosilicate, medium-index (BSM) glass and the second material is a synthetic resin-based material such as Zeonex® E48R. For sake of clarity, only a single ray of display light <NUM> is shown within the lightguide <NUM> in the view <NUM>.

<FIG> illustrates a set of example coefficients <NUM> characterizing reflective surfaces of a demonstrative curved lightguide such as the lightguide <NUM> in accordance with some embodiments. A first surface <NUM> corresponds to the combiner surface <NUM> and a second surface <NUM> corresponds to the top surface <NUM>. A spherical radius of curvature of the combiner surface <NUM> is approximately -<NUM>. A spherical radius of curvature of the world-side surface <NUM> is approximately <NUM>. The example coefficients <NUM> are consistent with coefficients and measurements known to those in the optics art for freeform lenses and which satisfy the following sag equation relative to an axis or center of a corresponding spherical lens: <MAT> where m and n and x and y are integers, and where R is a length of the radius of the particular surface <NUM>, <NUM>. For example, m = <NUM> and n = <NUM> corresponds to C<NUM>,<NUM> = x<NUM>. A first coefficient <NUM> corresponds to m = <NUM> and n = <NUM>. For the first surface <NUM>, x<NUM> is approximately -<NUM>. 2148E-<NUM> and for the second surface <NUM>, x<NUM> is approximately <NUM>. 5773E-<NUM>. The values of the other coefficients <NUM>-<NUM> for the surfaces <NUM>, <NUM> are as shown in <FIG> for a curved lightguide such as the light guide <NUM> of the device <NUM>. A thickness between the eye-side surface <NUM> and the world-side surface <NUM> of the lightguide <NUM> is approximately four mm.

<FIG> illustrates a perspective view <NUM> of the eyewear device <NUM> worn by the user <NUM> in accordance with some embodiments. Only a right portion of the device <NUM> is illustrated to expose operation and a position of the device <NUM> relative to the user eye <NUM>. Light from the display <NUM> is first directed toward the eye-side of the device <NUM> inside a top portion of the frame <NUM> and is directed into a top side of the lightguide <NUM> by reflection from a surface of the mirror <NUM>. The frame <NUM> rests on the bridge of the nose <NUM> of the user <NUM>. The mirror <NUM> directs the display light to the combiner <NUM>. The combiner <NUM> reflects the display light into the pupil <NUM> of the user eye <NUM>.

<FIG> illustrates a perspective view of an eyewear device <NUM> generally from the back and right sides where the device <NUM> is similar to the device <NUM> illustrated in other figures. The device <NUM> is worn by the user <NUM> in accordance with some embodiments. Only a right portion of the device <NUM> is illustrated to expose operation and a position of the device <NUM> relative to the user eye <NUM>. Light from the display <NUM> is first directed toward the eye-side of the device <NUM> inside a top portion <NUM> of the frame <NUM> and is then directed into a top side of the lightguide <NUM> by reflection from the mirror <NUM>. The display <NUM> and the mirror <NUM> are incorporated into the frame <NUM> between the top side <NUM> (e.g., top surface) of the frame <NUM> and the top edge <NUM> of the lightguide <NUM>. The frame <NUM> rests on the bridge of the nose <NUM> of the user <NUM>. The mirror <NUM> directs the display light to the combiner <NUM>. The combiner <NUM> reflects the display light into the pupil of the user eye <NUM>. Certain parts of the device <NUM> fit within the top portion <NUM> of the frame <NUM>. The top portion <NUM> of the device <NUM> is up to about <NUM> in size vertically. For a +0D eye glass device <NUM> (no vision correction), a lightguide thickness <NUM> is approximately <NUM> or less horizontally. The eye relief distance <NUM> between the lightguide <NUM> and the front (cornea) of the eye <NUM> is approximately <NUM>.

<FIG> illustrates a perspective view of an eyewear device <NUM> in accordance with some embodiments generally from the back and right sides where the device <NUM> is similar to the device <NUM> illustrated in other figures. The device <NUM> provides a prescriptive eye correction of approximately +2D with addition of a corrective lens <NUM> positioned interiorly in the frame <NUM>. Only a right portion of the device <NUM> is illustrated to expose operation and a position of the device <NUM> relative to the user eye <NUM>. Light from the display <NUM> is first directed toward the eye-side of the device <NUM> inside a top portion <NUM> of the frame <NUM> and is then directed into a top side of the lightguide <NUM> by reflection from the mirror <NUM>. As shown in the inset, the lightguide <NUM>, light is reflected between a second surface - the world-side surface <NUM> - and a first surface - the eye-side surface <NUM>. The display <NUM> and the mirror <NUM> are incorporated into the frame <NUM> between the top side <NUM> (surface) of the frame <NUM> and the top edge <NUM> of the lightguide <NUM>. The frame <NUM> rests on the bridge of the nose <NUM> of the user <NUM>. The mirror <NUM> directs the display light to the combiner <NUM>. The combiner <NUM> reflects the display light into the pupil of the user eye <NUM>. Certain parts of the device <NUM> fit within the top portion <NUM> of the frame <NUM> including the display <NUM> and the mirror <NUM>. The top portion <NUM> of the device <NUM> is up to about <NUM> in size vertically for a <NUM>:<NUM> ratio display <NUM>. For a +2D eye glass device <NUM>, at least at or near an optical axis through the user eye <NUM>, a total thickness <NUM> is approximately <NUM> and an eye relief distance <NUM> between the lightguide and a front (cornea) of the eye <NUM> is approximately <NUM>. For a <NUM> lightguide thickness <NUM>, a corrective lens thickness <NUM> is approximately <NUM>.

<FIG> illustrates a perspective view of an eyewear device <NUM> in accordance with some embodiments generally from the back and right sides where the device <NUM> is similar to the device <NUM> illustrated in other figures. The device <NUM> provides a prescriptive eye correction of approximately -4D with addition of a corrective lens <NUM> positioned interiorly in the frame <NUM>. Only a right portion of the device <NUM> is illustrated to expose operation and a position of the device <NUM> relative to the user eye <NUM>. Light from the display <NUM> is first directed toward the eye-side of the device <NUM> inside a top portion <NUM> of the frame <NUM> and is then directed into a top side of the lightguide <NUM> by reflection from the mirror <NUM>. As shown in the inset, the lightguide <NUM>, light is reflected between a second surface - the world-side surface <NUM> - and a first surface - the eye-side surface <NUM>. The display <NUM> and the mirror <NUM> are incorporated into the frame <NUM> between the top side <NUM> (surface) of the frame <NUM> and the top edge <NUM> of the lightguide <NUM>. The frame <NUM> rests on the bridge of the nose <NUM> of the user <NUM>. The mirror <NUM> directs the display light to the combiner <NUM>. The combiner <NUM> reflects the display light into the pupil of the user eye <NUM>. Certain parts of the device <NUM> fit within the top portion <NUM> of the frame <NUM> including the display <NUM> and the mirror <NUM>. The top portion <NUM> of the device <NUM> is up to about <NUM> in size vertically for a <NUM>:<NUM> ratio display <NUM>. For a -4D eye glass device <NUM>, at least at or near an optical axis through the user eye <NUM>, a total thickness <NUM> is approximately <NUM> and an eye relief distance <NUM> between the lightguide and a front (cornea) of the eye <NUM> is approximately <NUM>. The lens <NUM> is thicker at a top and bottom of the lens <NUM> to conform with a lens curvature to provide the -4D correction. While a vertical cross-section and a single thickness profile are shown for the corrective lenses <NUM>, <NUM>, the shape of these lenses is adjustable so as to provide correction for astigmatism for a user eye. For a <NUM> lightguide thickness <NUM>, a corrective lens thickness <NUM> is approximately <NUM> at its thinnest.

<FIG> illustrates a scene <NUM> as viewed through one of the lenses of an eyewear device in accordance with some embodiments. For sake of illustration, the scene <NUM> is visible inside of an edge <NUM> of a frame and the scene <NUM> is divided into quadrants by a horizontal bisecting line <NUM> and a vertical bisecting line <NUM>. An augmented reality (AR) image <NUM> is produced by a display of the eyewear device such as the device <NUM>. The AR image <NUM> is displayed according to a <NUM>:<NUM> aspect ratio <NUM>:<NUM> (width-to-height; horizontal-to-vertical) where the image <NUM> and display generating the same are approximately <NUM> pixels by <NUM> pixels in size along a horizontal dimension <NUM> and a vertical dimension <NUM>. The display would then have <NUM> pixel rows having a pixel row length of <NUM> pixel units.

The resolution of the AR image <NUM> corresponds to a number of pixels per unit of measure and a size of each pixel of the display generating the AR image <NUM>. As observed by a user, the device <NUM> produces the AR image <NUM> with <NUM>-<NUM> pixels per degree of visibility in the observed image. Such range of magnification of pixels provides adequate legibility and unobtrusive pixel visibility. Pixel size at the display is between <NUM> and <NUM>. In terms of color bit depth, at least <NUM> bits per color is used for the AR image <NUM>. The AR image <NUM> is refreshed at a refresh rate between <NUM> and <NUM>. In terms of a display interface, multiple types of display interfaces are usable. In some embodiments, a one-lane display serial interface (DSI) that complies with a specification of the Mobile Industry Processor Interface (MIPI) and that is operated in a command mode is used to drive the display to generate the AR image <NUM> according to an image data source. In terms of power consumption, the AR image <NUM> is generated by a power source having at least 50mWh of battery capacity when battery driven.

In terms of size, a FOV of the image <NUM> is approximately <NUM> degrees horizontal and <NUM> degrees vertical and is located in a bottom right quadrant of the scene <NUM> according to some embodiments. This location is based on user feedback across a number of trials. For an eyewear device <NUM>, the AR image <NUM> is positioned in any one of the quadrants of the scene <NUM> and, depending on its location, would exhibit a change in size based on the geometries of the components of the device <NUM>. In terms of location within the scene <NUM>, the AR image <NUM> is positioned at approximately <NUM> degrees to the right from a vertical plane as indicated by a first angle <NUM> and at approximately <NUM> degrees downward from a horizontal plane through an optical axis as indicated by a second angle <NUM>.

For an AR image having an <NUM>:<NUM> aspect ratio, the FOV is approximately <NUM> degrees horizontal by <NUM> degrees vertical and the generating display would be of a correspondingly different number of pixels in relation to the display generating the <NUM>:<NUM> aspect ratio AR image <NUM>. In terms of hardware, as measured at the display, each of the pixels are of a particular size between <NUM> microns to <NUM> microns depending on the type of display used in the eyewear device (e.g., an OLED display, an LCD display). The image <NUM> exhibits less than a <NUM>% distortion and at least a <NUM>% polychromatic modulation transfer function (MTF) at a pixel near a center of the image <NUM>. When mounted in the frame, the display is less than <NUM>% vignetted in a first (horizontal) direction and in a second (vertical) direction such that a mask does not obscure many of the pixels of display when generating the AR image <NUM>.

In some embodiments, the AR image <NUM> is provided with three lines of text <NUM> over some or all of the entire image. These lines of text <NUM> provide AR information to the viewer. In this instance, as illustrated, the AR information confirms a business name at a location in the scene <NUM>, street address, and hours of operation as the user stands across a street outside of the business and gazes in a direction toward the business. Beyond text, other types of information are deliverable in the AR image <NUM> including video, icons, and images and this information is updated over time. For example, while driving, the AR image <NUM> provides text and driving symbols to a user depending on a location of the user wearing the eyewear device <NUM>.

<FIG> illustrates an exploded perspective view of a lightguide such as the lightguide <NUM> first illustrated in <FIG>. A set of components <NUM> of an eyewear device <NUM> include the lightguide <NUM> and a matching filler piece <NUM>. The filler piece <NUM> is optional and together with the lightguide <NUM> are one embodiment of a lens for an optics device described herein. The matching filler piece <NUM> is included with the lightguide <NUM> so as to create the eyewear device <NUM> with an appearance of ordinary eyewear and having the functionalities as described herein. Surfaces of the filler piece <NUM> are shaped to match surfaces of the lightguide <NUM> including surfaces of a recess <NUM> in the lightguide <NUM>. For example, on an eye-side of the filler piece <NUM>, a first matching surface <NUM> of the filler piece <NUM> is shaped to match a combiner curvature <NUM> of a combiner surface <NUM> of a combiner aperture <NUM> of the lightguide <NUM>. To the extent that the filler piece <NUM> extends to an eye-side of the lightguide <NUM>, another surface of the filler piece <NUM> is shaped to match an eye-side curvature <NUM> of an eye-side surface <NUM> of the lightguide <NUM>. The combiner aperture <NUM> is found within boundaries of the combiner surface <NUM>. The combiner surface <NUM> is defined by a top interface line <NUM>, a bottom interface line <NUM>, an outer interface line <NUM>, and an inner interface line <NUM>. Each of the lines <NUM>-<NUM> are found at the intersection of respective surfaces of the lightguide <NUM>. On a world-side of the filler piece <NUM>, a second matching surface <NUM> is shaped to match a world-side curvature <NUM> of a world-side surface <NUM> of the lightguide <NUM>.

Display light <NUM> from a display <NUM> and ambient light <NUM> from the world-side of the lightguide <NUM> are combined in the combiner aperture <NUM>. The display <NUM> includes light emitting elements (e.g., passive- or active-matrix organic light-emitting or organic electroluminescent diode (OLED)) and is supported electronically and mechanically by a set of components grouped together in a package <NUM> as known to those in the art. Display light <NUM> emitted from the display <NUM> travels to a reflector <NUM> as shown by a light path <NUM> and is reflected into the lightguide <NUM>. An area on a back surface of the reflector <NUM> shows where light <NUM> is reflected. The combiner aperture <NUM> is a portion of the combiner surface <NUM> that ultimately reflects the display light <NUM> toward the eye-side of the lightguide <NUM>. Display light <NUM> generated by the display <NUM> is directed by a surface of the reflector <NUM> into a top surface <NUM> of the lightguide <NUM> and travels therein by total internal reflection (TIR). In some embodiments, the top surface <NUM> is part of a prism or field lens that is then sealed inside a frame (not illustrated) relative to and with other components of the lightguide <NUM>.

Once directed inside the lightguide <NUM>, the display light <NUM> reflects inside the lightguide <NUM> at least one time from each of the world-side surface <NUM> and the eye-side surface <NUM>. Preferably, the display light <NUM> reflects one time from each of the surfaces <NUM>, <NUM> before exiting on the eye-side of the lightguide <NUM>. The shapes of the surfaces of each component of the set of components <NUM>, including the surfaces of the lightguide <NUM> and the filler piece <NUM>, include a dimensional component along one or more of a first (x) axis <NUM>, a second (y) axis <NUM>, and a third (z) axis <NUM>. For example, the combiner surface <NUM> is curved from a perspective relative to the first axis <NUM> and curved from a perspective relative to the second axis <NUM> as further shown in other figures and further described herein.

The lightguide <NUM> includes an outer groove <NUM> in an outer edge <NUM> and an inner edge <NUM>. The outer groove <NUM> extends from a top side <NUM> to a bottom side <NUM>. The outer groove <NUM> is also formed in the top side <NUM> and the bottom side <NUM> of the lightguide <NUM>. The outer groove <NUM> along the edges <NUM>, <NUM> and sides <NUM>, <NUM> mate to a ridge of a frame (not illustrated) so as to hold the lightguide <NUM> fixed in the frame as shown in the frame <NUM> of <FIG>. In <FIG>, the lightguide <NUM> also includes one or more features such as one or more passages <NUM> into or through the lightguide <NUM> for receiving fasteners (not illustrated) to hold a display housing (not illustrated) and the display <NUM> at a fixed position and orientation at the top side <NUM>.

<FIG> illustrates an overhead view <NUM> of two lightguides <NUM>-<NUM>, <NUM>-<NUM> as positioned in the frame <NUM> as shown in <FIG> in accordance with some embodiments. The lightguides <NUM>-<NUM>, <NUM>-<NUM> are arranged in a binocular arrangement, one for each eye, which facilitates a proper view of 3D and AR content. The first (right) lightguide <NUM>-<NUM> is positioned in front of a first (right) eye <NUM> and a first (right) pupil <NUM>. A second (left) lightguide <NUM>-<NUM> is positioned in front of a second (left) eye <NUM> and a second (left) pupil <NUM>. Each of the lightguides <NUM>-<NUM>, <NUM>-<NUM> includes one or more grooves <NUM> in one or more edges thereof for interfacing with the frame <NUM> (not illustrated for clarity). For example, a groove <NUM> is found in the outer edge <NUM> and the inner edge <NUM> of each of the lightguides <NUM>-<NUM>, <NUM>-<NUM>. Visible in an eye-side surface of each lightguide <NUM>-<NUM>, <NUM>-<NUM> is an opening <NUM> corresponding to a back side of recess between parts of the lightguide <NUM> as in other figures including <FIG> and <FIG>. In some embodiments, a transparent shell <NUM> is positioned on a world-side of each lightguide <NUM>-<NUM>, <NUM>-<NUM>. One or more passages are formed in each of the lightguides <NUM>-<NUM>, <NUM>-<NUM> to facilitate affixing certain elements thereto. A top surface <NUM> for receiving display light from a display (not illustrated) is located in a central position at a top edge of each lightguide <NUM>-<NUM>, <NUM>-<NUM>.

The lightguides <NUM>-<NUM>, <NUM>-<NUM> are positioned an equal distance from a central axis <NUM> as evidenced by a respective visual axis <NUM> for each of the eyes <NUM>, <NUM>. A center <NUM> of a combiner aperture <NUM> in each lightguide <NUM>-<NUM>, <NUM>-<NUM> is positioned a first wrap angle <NUM> with respect to the respective eye <NUM>, <NUM>. The first wrap angle <NUM> is greater than a second wrap angle <NUM> of each of the lightguides <NUM>-<NUM>, <NUM>-<NUM> where the second wrap angle <NUM> is relative to a normal taken from a front surface of the respective lightguides <NUM>-<NUM>, <NUM>-<NUM>. For example, the first wrap angle <NUM> is approximately seven degrees while the second wrap angle <NUM> is approximately <NUM> degrees. The IPD <NUM> is approximately <NUM> between the visual axis of each eye <NUM>, <NUM>. Each of the combiner apertures <NUM> includes a vertical field size <NUM> of approximately <NUM> degrees and a total horizontal field size <NUM> of approximately <NUM> degrees relative to and for each of the pupils <NUM>, <NUM> of the first and second eyes <NUM>, <NUM> based on a pupil size <NUM> of approximately four mm. Because of an image offset and geometries of the various components, the FOV of the resultant AR image <NUM> at the combiner surface <NUM> is approximately <NUM> degrees by <NUM> degrees for a <NUM>:<NUM> aspect ratio display <NUM> and approximately <NUM> degrees by <NUM> degrees for an <NUM>:<NUM> aspect ratio display <NUM>. Overall, a total horizontal FOV (HFOV) <NUM> across each of the combiner surfaces <NUM> is approximately <NUM> degrees with a nasal side width of approximately <NUM> degrees and a temporal side width of another approximately <NUM> degrees. A binocular overlap is approximately <NUM> degrees.

<FIG> illustrates a perspective cut-away view of an assembled eyewear device <NUM> in accordance with some embodiments. The device <NUM> illustrates a world-side portion <NUM> and an eye-side portion <NUM> of the frame <NUM>. One or more components of the device <NUM> are mounted inside of a generally pentahedral-shaped compartment <NUM> of a top portion of the frame <NUM>. The hollow compartment <NUM> is alternatively described as a cavity having a vaulted interior where the sides or surfaces are shaped to facilitate mounting of the various components therein. In some embodiments, the components in the compartment <NUM> include one or more of the display <NUM>, the package <NUM>, the field lens <NUM>, and the mirror <NUM>. The compartment <NUM> is above an optical axis of the apparatus when worn by a user.

Two or more of these and other components are assembled as a unit and the unit is then mounted inside of the frame <NUM> during assembly to create a finished eyewear device <NUM>. Various combinations of the contents of these assembly units are possible for convenience during assembly. As one example, the field lens <NUM> is assembled and sealed with the lightguide <NUM>. In another example, the field lens <NUM>, the display <NUM>, the package <NUM>, and the mirror <NUM> are assembled together as a unit and are then placed or formed inside of the compartment <NUM>. The compartment <NUM> and frame <NUM> shaped with one or more ridges or contours so as to receive and hold securely in place an assembled unit. In terms of arrangement of components, as illustrated, the display <NUM> and the package <NUM> are mounted against the world-side portion <NUM> of the frame <NUM> and the compartment <NUM>. The package <NUM> includes various electronic components that power and activate light emitting elements (not illustrated) of the display <NUM>.

The mirror <NUM> is mounted on the eye-side portion <NUM> of the compartment <NUM>. The mirror <NUM> includes a reflective surface <NUM>. The display <NUM> is oriented to direct light emitted from the display <NUM> toward the eye-side of the device <NUM> and toward the mirror <NUM>. In this orientation, with the substantially enclosed compartment <NUM>, the device <NUM> avoids leaking light outside of the frame <NUM> except through the interior <NUM> of the lightguide <NUM>. The device <NUM> thereby maintains an appearance of ordinary eyewear. At least the reflective surface <NUM> of the mirror <NUM> is oriented with respect to the display <NUM> and the field lens <NUM> so as to reflect light into a first surface <NUM> of the field lens <NUM>, out of a second surface <NUM>, and into an interior <NUM> of the lightguide <NUM>. In some embodiments of the device <NUM>, no field lens <NUM> is used. In other embodiments, the field lens <NUM> is combined with or coupled to the mirror <NUM> such that a single reflector component takes the place of the mirror <NUM> as illustrated without losing any of the functionality of the device <NUM>. In this way, the field lens <NUM> would not appear as its own separate component and would thereby be an optional component when considering a number of components to assemble the device <NUM>.

The interior <NUM> of the lightguide <NUM> is between the world-side surface <NUM> and the eye-side surface <NUM>. A top portion of the frame <NUM> that houses the various components has a thickness <NUM> of up to <NUM> with some embodiments having a thickness <NUM> of <NUM> or less depending on one or more factors such as a size of the pixels of the display <NUM>, a number of pixels in the display <NUM>, and a dimensional size of one or more of the display <NUM>, the package <NUM>, the field lens <NUM>, and the mirror <NUM>.

To achieve a desired and minimized vertical thickness <NUM>, a plurality of factors is considered. For example, and in no particular order, a first angle of orientation between the display <NUM> and the mirror <NUM> is selected. This first angle is coordinated with a second angle of orientation between the mirror <NUM> and the field lens <NUM>. The first and second angles of orientation and the physical arrangement of the components <NUM>, <NUM>, <NUM> are coordinated with the orientation of one or both surfaces <NUM>, <NUM> of the field lens <NUM> so as to direct the display light into the lightguide <NUM> at a desired orientation and a desired magnification at a top edge of the lightguide <NUM>. Further, the orientations and curvatures of the world-side surface <NUM> and the eye-side surface <NUM> are also considered in order to deliver a desired AR image as illustrated in other figures in relation to the combiner <NUM> and the position of the combiner <NUM> relative to the user eye.

In some embodiments, one or more surfaces of a component inside of the compartment <NUM> are mounted directly against an interior surface of the compartment <NUM> with a fastener or an adhesive. When secured in this manner, the component maintains its position with respect to the others in the device <NUM> and with respect to the lightguide <NUM>. In some embodiments, a plurality of the components <NUM>, <NUM>, <NUM>, <NUM> are assembled together before being assembled as a unit into the compartment <NUM> of the frame <NUM> thereby providing a more consistent orientation with respect to each other during manufacture of many copies of the device <NUM>.

<FIG> illustrates a perspective cut-away view of an eyewear device <NUM> in accordance with some embodiments. The device <NUM> includes an alternative arrangement of the components of the device <NUM> of <FIG>. The device <NUM> illustrates the world-side portion <NUM> and the eye-side portion <NUM> of the frame <NUM>. Components of the device <NUM> are mounted inside of the generally pentahedral-shaped compartment <NUM> of a top portion of the frame <NUM>. The compartment <NUM> is a first compartment in the frame <NUM>. The components of the device <NUM> include the display <NUM>, the package <NUM>, the field lens <NUM>, and the mirror <NUM>. The display <NUM> and the package <NUM> are mounted against a support structure <NUM> along the eye-side portion <NUM> of the frame <NUM> and the compartment <NUM>. Between the support structure <NUM> and an exterior of the frame <NUM> is formed a second compartment <NUM> in which is positioned an assembly structure <NUM>. The assembly structure <NUM> is mounted to the package <NUM> and the display <NUM> such as through the use of one or more fasteners through the support structure <NUM> or is otherwise interlocked by a dovetail or other mechanical feature of the package <NUM> with a mechanical feature of the support structure as used by those in the art. The support structure <NUM>, in some embodiments, is formed in and with a same material as the frame <NUM>. Other shapes and sizes of the support structure <NUM> are possible depending on a final shape of the components to be incorporated into the eyewear device <NUM>. In some embodiments, two or more of the package <NUM>, the display <NUM>, the field lens <NUM>, and the mirror <NUM> are formed into an assembly unit for placing into the compartment <NUM> and securing the unit such as by way of the assembly structure <NUM>. When one or more of the compartments <NUM>, <NUM> are sealed, sensitive electronics can be placed therein and are protected against dust and contact such as during assembly, handling, and operation by an end user.

In terms of orientation of the components, the mirror <NUM> is mounted on the world-side portion <NUM> of the frame <NUM> relative to the compartment <NUM>. The mirror <NUM> includes a reflective surface. The display <NUM> is oriented to direct light emitted from the display <NUM> toward the world-side <NUM> of the device <NUM> and toward the mirror <NUM>. In this orientation, with the substantially enclosed compartment <NUM>, the device <NUM> avoids leaking light outside of the device <NUM> except through the interior <NUM> of the lightguide <NUM>. The device <NUM> thereby maintains an appearance of ordinary eyewear. Further, the thickness <NUM> of the frame <NUM> above the lightguide <NUM> is held to a minimum or at least to a similar size as an ordinary eyewear. At least the reflective surface of the mirror <NUM> is oriented with respect to the display <NUM> and the field lens <NUM> so as to reflect light into a first surface of the field lens <NUM>, out of a lower, second surface of the field lens <NUM>, and into an interior <NUM> of the lightguide <NUM>. In some embodiments of the device <NUM>, no field lens <NUM> is used. In other embodiments, the field lens <NUM> is combined with or coupled to the mirror <NUM> such that a single reflector component takes the place of the mirror <NUM> as illustrated without losing any of the functionality of the device <NUM>. In this way, the field lens <NUM> would not appear as its own separate component and would thereby be an optional component when considering a number of components to assemble the device <NUM>.

To achieve a desired and minimized vertical thickness <NUM>, a plurality of factors is considered. For example, and in no particular order, a first angle of orientation between the display <NUM> and the mirror <NUM> is selected. This first angle is coordinated with a second angle of orientation between the mirror <NUM> and the field lens <NUM>. The first and second angles of orientation and the physical arrangement of the components <NUM>, <NUM>, <NUM> are coordinated with the orientation of one or both surfaces <NUM>, <NUM> of the field lens <NUM> so as to direct the display light into the interior <NUM> of the lightguide <NUM> at a desired orientation and a desired magnification at a top edge of the lightguide <NUM>. Further, the orientations and curvatures of the world-side surface <NUM> and the eye-side surface <NUM> are also considered in order to deliver a desired AR image as illustrated in other figures in relation to the combiner <NUM> and the position of the combiner <NUM> relative to the user eye.

In some embodiments, certain aspects of the techniques described above may implemented by one or more processors of a processing system executing software such as to generate a signal for the display in the eyewear whereby the signal causes the display to provide light that ultimately is the AR-based image that is viewable by the user eye. The signal may be generated by a software that includes one or more sets of executable instructions stored or otherwise tangibly embodied on a non-transitory computer readable storage medium. The software includes the instructions and certain data that, when executed by the one or more processors, manipulate the one or more processors to perform one or more aspects of the techniques described above including operating of the display inside of the eyewear device. The non-transitory computer readable storage medium includes, for example, a magnetic or optical disk storage device, solid state storage devices such as Flash memory, a cache, random access memory (RAM) or other non-volatile memory device or devices, and the like.

However, various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the claims below.

Claim 1:
An optical device (<NUM>) comprising:
a display (<NUM>, <NUM>) oriented toward an eye-side of the optical device (<NUM>) and configured to emit light toward the eye-side of the optical device (<NUM>) based on an input signal;
a lightguide (<NUM>,<NUM>) having: an incoupler surface (<NUM>, <NUM>, <NUM>) at a top side of the lightguide (<NUM>, <NUM>);
a curved first surface (<NUM>, <NUM>) at the eye-side of the optical device (<NUM>); and
a curved second (<NUM>, <NUM>) surface for reflecting the light through the curved first surface (<NUM>, <NUM>) to a user eye;
a reflector (<NUM>, <NUM>,<NUM>) having a reflective surface (<NUM>) positioned at the eye-side relative to the display (<NUM>, <NUM>) above the incoupler surface (<NUM>, <NUM>, <NUM>) and at least one of the curved first surface (<NUM>, <NUM>) and the curved second surface (<NUM>, <NUM>) of the lightguide (<NUM>, <NUM>), wherein the reflector (<NUM>, <NUM>, <NUM>) is positioned to reflect light from the display (<NUM>, <NUM>) into the lightguide (<NUM>, <NUM>); and
a head mountable frame (<NUM>) supporting the display (<NUM>, <NUM>), the reflective surface (<NUM>), and the lightguide (<NUM>, <NUM>), wherein the display (<NUM>, <NUM>) is positioned at a top of the head mountable frame (<NUM>).