CN116848455A - Projector alignment system - Google Patents

Abstract

An Augmented Reality (AR) or Virtual Reality (VR) device (1) is provided. The AR or VR device (1) comprises: a waveguide (6 a,6 b), a projector (4 a,4 b) and a housing (2). The waveguide (6 a,6 b) comprises an input region (20 a) configured to receive light incident along a first direction and an output region (22 a), wherein the waveguide (6 a,6 b) is configured such that a first portion of light propagates along the waveguide (6 a,6 b) by total internal reflection in a direction substantially perpendicular to the first direction towards the output region (22 a) where it is coupled out to a viewer to form an image. A projector (4 a,4 b) is arranged adjacent to the waveguide, the projector (4 a,4 b) being adapted to project light into the waveguide (6 a,6 b) at the input area (20 a). A housing (2) for holding the projector (4 a,4 b) and the waveguide (6 a,6 b) relative to each other, the housing (2) comprising a hole (8 a), the hole (8 a) being arranged adjacent to the input area (20 a) and spaced apart from the input area along a first direction on a side of the input area (20 a) opposite the projector (4 a,4 b).

Description

Projector alignment system

Technical Field

The present invention relates to methods and systems for aligning projectors on AR/VR devices, particularly waveguide AR/VR devices.

Background

Most Augmented Reality (AR) devices utilize waveguide technology to display images. In these types of devices, typically a projector couples light representing an image into a waveguide. The light travels by total internal reflection along the waveguide towards an output region in which the light is coupled out to the eyes of the viewer, so that the viewer sees an image enhanced on their real world view.

Proper alignment of the projector is required to ensure that the light is efficiently coupled into the waveguide and that the light is coupled in the desired orientation. Furthermore, the AR device may have a separate projector and waveguide for each eye. Accordingly, it is desirable that the projectors be accurately aligned with each other and with respect to the housing so that the images viewed by each eye are identical and converging. However, achieving accurate alignment can be difficult.

The present invention aims to solve this problem of achieving accurate alignment of projectors on these types of AR devices.

Disclosure of Invention

According to a first aspect, there is provided an Augmented Reality (AR) or Virtual Reality (VR) device comprising: a waveguide including at least an output region and an input region configured to receive light incident along a first direction, wherein the waveguide is configured such that a first portion of the light propagates along the waveguide in a direction substantially perpendicular to the first direction by total internal reflection toward the output region where it is coupled out to a viewer to form an image; a projector disposed adjacent the waveguide, the projector for projecting light into the waveguide at the input region; a housing for holding the projector and the waveguide relative to each other, the housing comprising an aperture disposed adjacent to the input area and spaced apart from the input area along a first direction on a side of the input area opposite the projector.

The holes may be used, for example, to align projectors on the device when the device is assembled. This may be achieved in that a portion of the light from the projector may pass directly through the waveguide and through the aperture in a first direction before being incident on the object to form the image. Thus, calibration may be performed by adjusting the angular position of the projector or prism/mirror so that the image formed at the target may be used to align the angular position of the projector or prism/mirror with respect to a known reference point on the target. Such calibration may ensure that the projector and housing are aligned relative to each other as desired.

By having holes or holes in the housing, light passing directly through the input region of the waveguide may be used to align the projector, which light is not coupled along the waveguide.

The light is preferably incident on a first side of the input area and a portion of the light may pass through the input area before exiting a second side opposite the first side. The aperture is positioned at a second side of the input area, i.e. at the opposite side of the input area from the projector. In this way, the input area is positioned between the aperture and the projector.

Preferably, the aperture extends through the housing in a first direction. The aperture, when used for alignment, provides a passage through the housing such that a portion of the light from the projector, after being incident on the input area, may pass directly through the housing along a first direction such that the portion of the light may form an image at the target, as outlined above.

The first direction may be a first axis. For example, the input region may be configured to receive light incident along the x-axis and the light propagates along the waveguide in a direction substantially perpendicular to the first direction, e.g., in the z-axis and/or the y-axis.

The aperture may have a first end and a second end such that the aperture extends from the first end to the second end, the first adjacent the input region, wherein the aperture is closed at the second end. In some arrangements, the cover may be positioned at the second end of the aperture such that the aperture is closed at the second end. Having a cover at the second end of the aperture prevents unwanted light from being projected from the device in the first direction when in use. The purpose of the aperture is to aid in the alignment of the projector, while the AR view for the viewer is provided by the light output from the output area. In this way, the aperture may not play any role when the AR/VR device is in use, with the purpose of being used for alignment of the projector prior to use and/or during assembly of the device.

The cover may be a cap or any type of fitting that can be used to block the aperture. The cover may be of the same material as the housing. Alternatively, it may be a different material. The cover may be plastic, rubber or any type of light shielding material. The dimensions of the cover may be similar or identical to the dimensions of the aperture such that it is placed within the aperture to prevent light emission from the aperture, as mentioned above. Alternatively, the cover may be larger than the aperture such that the cover extends over the aperture when applied to prevent light from being emitted from the aperture. In other arrangements, the plug or filler may be located in the aperture when the device is in use. The plug or filler may extend along the length of the aperture so as to prevent light from passing through the aperture when the device is in use.

In some arrangements, the projector may be positioned on the housing such that the projector emits light in the first direction. In other arrangements, one or more optical components may be positioned in the optical path between the projector and the waveguide to ensure that light is coupled into the input region along the first direction. For example, the projector may be arranged such that it emits light perpendicular to the first direction, and the device may comprise an optical component configured to change the direction of light emitted from the projector such that said light is incident on the input area along the first direction. For example, a prism, mirror, or other optical component may be used to alter the path of light from the projector such that the light is still incident on the waveguide in the first direction. In this context, the term "adjacent" is used to connote that the projector is in close proximity or very close proximity, e.g., that the projector is disposed adjacent to the waveguide.

Those skilled in the art will appreciate that adjusting the positioning of the projector relative to the housing need not be limited to adjusting the positioning of the projector itself. This is an efficient positioning of the projector. In other words, one skilled in the art will appreciate that this may mean any adjustment of the angular position of the projector and/or optical components (e.g., prisms or mirrors) in the path between the projector and the aperture.

Preferably, the input area is a diffraction input grating. The input grating may be configured to couple light from the projector into the waveguide. Preferably, the input diffraction grating may comprise grooves in one surface of the waveguide. The input grating may be a one-dimensional diffraction grating comprising grooves in one surface of the waveguide. The input grating may be an input grating as described in WO 2016/020643. Since the input grating is not perfect in coupling light from the projector into the waveguide, a portion of the light may pass directly from the waveguide through the input grating and into the aperture, rather than being coupled into the waveguide. This portion of the light may be used for projector alignment.

The output region of the waveguide may be a diffraction output grating. The output grating may provide a two-dimensional expansion and outcoupling of light to a viewer. The output grating may be an output grating as described in WO 2016/020643. Alternatively, the output region may comprise a plurality of gratings, each providing an expansion of light of a different dimension. The output gratings may be spaced apart at locations along the waveguide in a direction perpendicular to the first direction in which the light is incident on the input area.

Preferably, the apparatus may include a pair of projectors and a pair of waveguides, each having an associated aperture disposed adjacent to an input area of an associated waveguide of the aperture, and the aperture being spaced apart from the input area along a first direction on a side of the input area opposite the associated projector of the aperture. Each waveguide may be associated with a particular eye of the wearer such that it is configured to project light to the particular eye of the wearer. The housing may extend between a first end and a second end defining an axis perpendicular to a first direction in which light is incident on the waveguide. The first waveguide and its associated projector and aperture may be positioned at a first end of the housing and the second waveguide and its associated projector and aperture may be positioned at a second end of the housing.

The housing may be a frame, or rack, of the AR/VR device. It may act as a support for holding the waveguide and projector together. In some cases, the AR/VR device may be a headset configured to be worn on the head of the user. The housing may be the frame of such a headset. Alternatively, the AR/VR device may be goggles, glasses, or any other type of AR/VR device configured to be worn by a user. The housing may be a frame for goggles/glasses. Alternatively, the AR/VR device may be a heads-up display.

The holes may be holes or gaps in the housing, the only purpose of which is for alignment of the projector. The aperture provides an optical path from the projector, through the input region of the waveguide, and through the housing so that light may be incident on the target during the alignment process. The holes may have a circular cross-section. Alternatively, it may have a rectangular, square or any other shaped cross-section. The depth of the hole may be equal to the thickness of the portion of the housing in which the hole is formed.

Although the purpose of the holes has been described above as being for alignment of light after an input grating through the waveguide is to be received from the projector, it will be appreciated that the alignment process itself may be completed before the waveguide is presented on the device. In this way, when the device is assembled, light from the projector passes through the area where the input grating is located.

The projector may be any type of light engine capable of projecting light into the waveguide. This may be any type of micro projector. For example, the projector may include a liquid crystal on silicon, an LCOS panel, and a light source. The LCOS panel may be positioned in the optical path between the light source and the input region of the waveguide. The LCOS panel may be responsible for forming an image using light incident on the LCOS panel from a light source. The image may then be projected as an input pupil onto an input region of the waveguide. The light source may be an LED array. Alternatively, any other type of image generation device or light source may be used. For example, the light source may be a lamp or a laser. The panel may be any type of image generator including a self-emissive panel, a transmissive liquid crystal display, a reflective liquid crystal panel, a scanning laser beam generator, a digital light processing panel, or a dynamic mirror array. The projector may be multi-colored. Alternatively, the projector may be monochromatic.

The waveguide may be a planar slab waveguide. The maximum axis of the planar slab waveguide may be perpendicular to the first direction, i.e. the plane of the waveguide may be perpendicular to the first direction. The input grating and/or the output grating may be placed in or on the waveguide. For example, it may be placed on one of the outer surfaces of the plate. Alternatively, the grating may be placed within the waveguide as long as its refractive index is different from that of the slab. The purpose of the waveguide is to act as a near-eye display for the AR/VR device.

The waveguide may include: a planar slab of transparent optical material surrounded by a medium having a refractive index lower than that of the planar slab such that when light is arranged with a sufficiently large angle of incidence, the light will be confined within the slab by total internal reflection in a direction perpendicular to the plane of the slab. Preferably, the plane of the plate is parallel to the plane of the grating.

According to yet another aspect, there is provided a method of aligning a projector on an Augmented Reality (AR) or Virtual Reality (VR) device, the AR or VR device including a housing for holding the projector and a waveguide of the AR or VR device relative to each other, the housing including an aperture arranged adjacent an input area of the waveguide when the waveguide is on the housing and spaced apart from the input area along a first direction on a side of the input area opposite the projector, the method comprising: positioning a projector on the housing; coupling light from the projector through an aperture in the housing in a first direction such that the light forms an image at the target; comparing the image formed at the target with a reference point; the positioning of the projector relative to the housing is adjusted until the image formed at the target is at a desired positioning relative to the reference point, which indicates that the projector is properly aligned on the housing.

In this way, a portion of the light from the projector may pass directly through the aperture along the first direction before being incident on the target. Thus, calibration may be performed by adjusting the positioning of the projector so that the image formed at the target may be used to align the positioning of the projector relative to the reference point. Such calibration may ensure that the projector and the housing are aligned relative to each other as desired. This may be performed prior to placing the waveguide on the housing. Alternatively, it may also be performed when the waveguide is located on the housing.

Those skilled in the art will appreciate that adjusting the positioning of the projector relative to the housing need not be limited to adjusting the positioning of the projector itself. This is an efficient positioning of the projector. In other words, one skilled in the art will appreciate that this may mean any adjustment of the angular position of the projector and/or an optical component (e.g., a prism or mirror) in the path between the projector and the aperture that affects the path of light from the projector.

The correct alignment of the projector may be an alignment that has been predetermined to be the ideal alignment of the projector. For example, ensuring that maximum light can be coupled into the waveguide at a desired angle (e.g., when the waveguide is properly positioned). The correct alignment may be any point that has been selected relative to which other components (e.g., additional projectors and/or waveguides) may be aligned, as will be outlined below. In this way, the projector is properly aligned with respect to a known reference point, enabling other components of the device to be precisely aligned with respect to the projector as desired.

Preferably, the reference point may be a reference image having at least one characteristic with which the image formed at the target is to be aligned. In this way, the characteristics of the reference image serve as points to which the image formed at the target can be aligned. The at least one characteristic may be a shape of the reference image.

In some cases, the characteristic may be a common feature between images. For example, a common shape or a portion of a shape.

The at least one characteristic may be a shape of at least a portion of the reference image, and the shape of at least a portion of the image formed at the target is the same as the shape of at least a portion of the reference image. The reference image and the image formed at the target may have the same shape as each other. The size of the reference image and the size of the image formed at the target may also be the same. For example, the reference image and the target image may be circular, square, cross-shaped, or any other shape that enables alignment. In other arrangements, only a portion of the reference image may be the same as the image formed at the target. Alignment may be achieved by comparing the same portions of the reference image as the image formed at the target. Alternatively, only a portion of the image formed at the target may be identical to the reference image.

In other arrangements, the shape of the image formed at the target may be different from the shape of the reference image. For example, the reference image may be square or rectangular, and the image formed at the target may be cross-shaped. In this arrangement, correct alignment can be achieved when the center of the cross is at the center of the circle.

When the image formed at the target overlays the reference image, the image formed at the target may be at a desired location relative to the reference point. This enables accurate alignment of the projector. Furthermore, it provides a simple visual way for the user to know when proper alignment has been achieved. The overlay may be a precision overlay. For example, the projector may be properly aligned when the image formed at the target and the reference image are directly overlaid on each other. In other arrangements, the coverage may be only partial coverage. For example, in the case where the image formed at the target and the reference image are not identical in shape, the image formed at the target may only need to cover a specific position of the reference image.

In some arrangements, the screen may be a wall in a room in which alignment is performed, for example. This may be a fixed wall or a temporary wall. Alternatively, the screen may be a movable screen that may be placed at a desired location. Light may be projected directly onto the screen to form the image at the target.

The reference point may be a physical feature located on the screen. For example, it may be an image on a poster hanging on a screen, or it may be drawn directly on a screen/wall. Alternatively, the reference point may be an image projected on the screen by an external light source.

The method may further comprise: capturing an image formed at the target with an image pickup device, and displaying the reference point and the image formed at the target on a screen, and performing the comparing step and the adjusting step.

In some arrangements, the target may comprise a camera, wherein light passing through the aperture is captured by the camera, thereby forming the image formed at the target. In this way, light can be detected by the camera device instead of projecting the light directly onto the screen. Advantageously, by using an imaging device, the distance required to align the system can be reduced, as the imaging device can be positioned closer to the AR/VR device than the convergence distance of the images.

In other arrangements, the camera may be placed at a distance from the wall in order to capture an image formed at the target. This may replace a user looking directly at the image on the wall.

The light captured by the camera device may be displayed as an image on a display. This may be an external display, such as a monitor or other type of electronic display. This may allow the user to perform the comparison and adjustment in the same way as when light is projected directly onto a physical screen, but with greater convenience. The monitor may be connected to one or more processors.

In other arrangements, rather than displaying an image on a display, the user may be shown what adjustments are to be made to the position of the projector to achieve the direction of alignment. For example, instructions such as "move up", "move down", "move left", "move right" may be provided. This may be achieved by having a processor configured to analyze the light received at the target and compare it to a reference point to determine the movement of the projector required to achieve alignment. In other arrangements, these instructions may be provided in addition to the images so that the user can use the orientation or comparison of the images.

Adjusting the positioning of the projector may include angular adjustment of the projector. These angular adjustments may be made by pitch, yaw and/or roll. This may include, for example, moving the projector up or down, left or right, or tilting the projector forward or backward. The position of the image formed at the target (and its orientation) may inform the type of movement required to achieve alignment.

In some arrangements, positioning the projector on the housing includes positioning the projector on the housing adjacent to the input region of the waveguide; and wherein coupling light from the projector through the aperture in the housing in a first direction such that the light forms an image at the target further comprises: coupling light from the projector onto an input region of the waveguide such that the light is incident on the input region in a first direction such that: a first portion of the light propagates along the waveguide in a direction substantially perpendicular to the first direction by total internal reflection towards an output region of the waveguide for outcoupling the light to a viewer; and a second portion of the light passes directly through the waveguide and through the aperture in the housing in the first direction such that the second portion of the light forms an image at the target.

For example, the alignment method may be performed after the waveguide has been located on the housing. In this way, a portion of the light from the projector may pass directly through the waveguide along a first direction before being incident on the target. Thus, calibration may be performed by adjusting the positioning of the projector so that the image formed at the target may be used to align the positioning of the projector relative to the reference point. Such calibration may ensure that the projector and the housing are aligned relative to each other as desired.

The alignment is relative to the housing. By having holes or holes in the housing, light passing directly through the input region of the waveguide may be used to align the projector, which light is not coupled along the waveguide.

Alternatively, alignment of the projector may be performed before the waveguide is located on the housing. For example, when in a transmissive arrangement, i.e. where the projector is arranged on the opposite side of the waveguide to the eye (when viewing the light output from the output grating), the waveguide may have no effect on the alignment of the projector. Thus, the waveguide need not be in place before aligning the projector. In contrast, when in a reflective arrangement, i.e. in the case where the projector is arranged on the same side of the waveguide as the eye (when viewing the light output from the output grating), the waveguide does have an effect on the alignment of the projector. Thus, in the reflective mode, the waveguide may be positioned on the waveguide prior to aligning the projector, or alternatively, further adjustment of the projector alignment may be performed to correct the projector alignment when the waveguide is placed on the housing.

Preferably, the projector is a first projector and the AR/VR device includes a second projector, the method may further include aligning the second projector on the housing by performing the method as outlined above on the second projector.

Advantageously, by precisely aligning the two projectors relative to the housing, each projector may be precisely aligned relative to each other. In this way, light from each of the projectors may be emitted toward each other in the same direction when properly aligned on the housing.

The waveguide may be a first waveguide and the second projector may be associated with a second waveguide. The first and second waveguides may be identical to each other, each having an input region and an output region. The first projector may couple light into the first waveguide and the second projector may couple light into the second waveguide. The first projector and the first waveguide may be associated with a first eye of the user and the second projector and the second waveguide may be associated with a second eye of the user. In this way, when properly aligned, each projector may form an image as light is coupled out of its respective output area to the user's eye. Thus, as explained above, the projectors may be positioned at opposite ends of the headphones from each other.

Since each projector forms its own image at the target, each projector can be aligned independently of the other projectors. The alignment of each projector may be performed simultaneously or sequentially. For example, the alignment of the second projector may be performed after the alignment (completion) of the first projector. Alternatively, a stepwise adjustment may be made to each projector so that they are all adjusted toward the desired alignment.

In some arrangements, the reference point used to align the second projector may be a different reference point than the reference point to which the first projector is aligned. For example, there may be separate images aligned by the images formed at the target by each projector. These reference images may be identical to each other. For example, they may have the same shape. Preferably, they may be spaced apart from each other on the target. For example, a reference image to which an image formed by a first projector at a target is to be aligned may be at a first location on the target, and a reference image to which an image formed by a second projector at the target is to be aligned may be at a different location on the target, wherein the first location and the second location may be different from each other. The positioning of the reference point for aligning the first projector may be at a known position relative to the reference point for aligning the second projector. For example, the positioning of the two reference points may be selected such that the two projectors are properly aligned relative to each other when aligned with their respective reference points.

In other arrangements, the reference image used to align the first projector may be different in at least one characteristic from the reference image used to align the second projector. For example, the reference images may have different colors and/or shapes from each other.

Further, the image formed by the first projector at the target may differ from the image formed by the second projector at the target in at least one characteristic. For example, the images formed by each projector at the target may have different colors and/or shapes from each other. Advantageously, this allows the user to distinguish between images from each projector so that they know which projector needs to be aligned. In an arrangement, the image formed at the target from the first projector and its corresponding reference image may be the same, and the image formed at the target from the second projector and its corresponding reference image may be the same. This further enables the user to know which already formed image should be aligned with which reference image.

Alternatively, in other arrangements, the image formed at the target from the first projector may be the same (i.e., the same characteristics) as the image formed at the target by the second projector.

In other arrangements, the reference points may be identical. For example, the reference point may be an image having a first portion of the image aligned with an image formed at the target by the first projector and a second portion of the image aligned with an image formed at the target by the second projector.

After properly aligning the first projector and the second projector on the housing, the method may further include: viewing a first image formed by light from a first portion of a first projector after being coupled out at an output region of a first waveguide; viewing a second image formed by light from the first portion of the second projector after being coupled out at an output region of the second waveguide; the positioning of the first and second waveguides is adjusted until the first and second images are overlaid on each other.

Since the projectors are already aligned with respect to each other, the relative position between them is unchanged. However, if the projector and the waveguide are in a reflective mode (such that the projector is on the eye side of the waveguide), the waveguide and the projector need to be properly aligned so that convergence of the image formed from the projector from the light coupled out of the output region can be achieved. In this way, both projectors are properly aligned with respect to their waveguides and each other. If the projector is used in a transmissive mode (the projector is on the opposite side of the waveguide from the eye), only the projector needs to be aligned to ensure convergence of the image formed from the projector. No adjustment of the waveguide is required in the alignment process in the transmissive mode.

In the reflection mode, by aligning the projector with respect to the housing, less waveguide movement is required when performing adjustment of the positioning of the waveguides to achieve convergence than in the case where the projector is not first aligned. Advantageously, this may reduce the amount of space on the AR/VR device required to allow the waveguide to move. Thus, the housings may be more tightly packed together when the device is assembled, thereby reducing the overall size of the AR/VR device.

Adjusting the positioning of the waveguides may include adjusting the orientation relative to each other, and thus the orientation of the housing and projector. For example, the adjustment of the waveguide may be an angular adjustment. This may be done in pitch and/or yaw.

Alignment may be achieved when the first image and the second image overlay each other. This may be a direct overlay on each other. For each respective projector, the first image and the second image may be the same shape as the shape of the image formed at the target from the light of the second portion. In this way, the first image and the second image may appear the same as the image formed at the target for aligning the respective projectors, although they may appear at different locations on the display. In some arrangements, the first image and the second image may be different in size than the image formed at the target by the light from the second portion of each respective projector. In other arrangements, the dimensions may be the same.

Unlike the image formed at the target for the alignment projector, the first image and the second image may be considered virtual images in that, although they are visible to the user and appear at the target when viewed through the output region of the waveguide, they are virtually invisible when viewed at the target unless viewed through the output region of the waveguide.

Preferably, adjusting the positioning of the first and second waveguides may further comprise adjusting the positioning such that the first and second images appear to be overlaid on the further reference image at the target. In this way, convergence of the first and second images from the projector may be achieved by aligning the first and second images with a further reference image when viewed through the output region of the waveguide. Providing a visual indicator to the user to achieve this correct positioning improves the accuracy that can be achieved with alignment. In addition, it facilitates easy alignment of the system. The further reference image may have the same shape as the first image and/or the second image. Alternatively, it may have a shape in which the first image and the second image may be aligned.

In some arrangements, additional reference images for adjusting the position of the waveguides relative to each other may be located at a target positioned between the reference images, with which each of the projectors is aligned. For example, it may be located at the midpoint between the reference images.

Preferably, the housing is at a known location relative to the target. The known location in space may be a particular spatial location. Additionally or alternatively, it may be a specific orientation of the housing. This can help achieve accurate alignment by knowing the precise positioning of the housing relative to the target. For example, when the housing is at this known location relative to the target, the reference point may be selected as a point that represents proper alignment of the projector.

Preferably, the target may be at a predetermined distance from the AR/VR device. It may be desirable for images formed by the AR/VR device that are coupled out to the viewer to converge at a distance. The target may be positioned at the desired convergence distance. This allows the entire field of view to be viewed during the alignment process. It further helps to correct convergence of the images. Preferably, the distance may be 4m. However, this may be 1m, 2m, 3m, or any other distance at which convergence is desired.

Alternatively, the target may be closer than the desired convergence distance. In this arrangement the entire field of view will not be visible, but alignment correction is still possible. This is advantageous because less space may be required than if the entire distance is used at which to achieve convergence.

Preferably, after the projector is properly aligned, the method may include applying a cover to the aperture of the housing such that light is no longer able to pass through the aperture. The purpose of the aperture is to facilitate alignment of the projector relative to the housing. By masking the aperture, light from the second portion of the projector can no longer form an image on the target. Advantageously, this serves to prevent light from being emitted from the AR/VR device through the aperture in a direction away from the user of the device during normal use, which is undesirable when the device is in use. A cover may be applied to each aperture associated with each projector.

According to yet another aspect, there is provided a system for aligning a projector on an Augmented Reality (AR) or Virtual Reality (VR) device, the system comprising: an Augmented Reality (AR) or Virtual Reality (VR) device, the AR or VR device comprising: a waveguide for displaying an AR or VR image, the waveguide comprising an input region for receiving light and an output region at which light is coupled out to a viewer; a projector disposed adjacent the waveguide display, the projector for projecting light into the waveguide at the input region such that a first portion of the light propagates along the waveguide toward the output region by total internal reflection; a housing for holding the projector and the waveguide relative to each other, wherein the housing comprises an aperture arranged such that a second portion of light incident on the input area passes directly out through the aperture and onto the target, thereby forming an image at the target; and a target for providing a reference point with which an image formed on the target can be compared to align the projector on the housing.

The system may be configured to perform the method of the above aspect.

The AR/VR device may be a device according to the above aspects.

The system may further comprise an imaging device as described in the above aspects. Alternatively or additionally, the target may comprise a screen.

According to yet another aspect, there is provided a system for aligning a projector on an Augmented Reality (AR) or Virtual Reality (VR) device, the system comprising: an AR or VR device, the AR or VR device comprising: a projector; a housing for holding a projector and a waveguide of an AR or VR device relative to each other, the housing comprising an aperture arranged adjacent an input area of the waveguide when the waveguide is located on the housing, and the aperture being spaced apart from the input area along a first direction on a side of the input area opposite the projector; and a target for providing a reference point with which an image formed on the target can be compared to align the projector on the housing, wherein the system is configured to perform the method of the above aspect.

According to one aspect of the present invention, there is provided a method of aligning a projector on an Augmented Reality (AR) or Virtual Reality (VR) device, the AR or VR device including a waveguide and a housing for holding the projector and the waveguide relative to each other, the method comprising: positioning a projector adjacent to an input region of the waveguide; coupling light from the projector onto an input region of the waveguide such that the light is incident on the input region in a first direction such that: a first portion of the light propagates along the waveguide in a direction substantially perpendicular to the first direction by total internal reflection towards an output region of the waveguide for outcoupling the light to a viewer; and a second portion of the light passes directly through the waveguide and through the aperture in the housing in a first direction such that it forms an image at the target; comparing the image formed at the target with a reference point; the positioning of the projector relative to the housing is adjusted until the image formed at the target is at a desired positioning relative to the reference point, which indicates that the projector is properly aligned on the housing.

It should be noted that any features of the specific aspects described herein may be applied in any suitable combination to any other aspects described herein. It should also be appreciated that the particular combinations of various features described and defined in any of the aspects described herein may be implemented and/or provided and/or used independently.

Drawings

FIG. 1 is a schematic top cross-sectional view of an Augmented Reality (AR) headset according to one aspect of the invention;

FIG. 2 is a schematic side cross-sectional view of an example system for aligning a projector on an AR headset in a reflective mode;

FIG. 3 is a schematic top cross-sectional view of an AR headset having a first projector that has been aligned relative to a housing and a second projector that is aligned on the AR headset;

fig. 4A-4D illustrate example images and example reference images formed by a projector at a target at various stages of alignment of the projector according to one aspect of the invention;

FIG. 5 illustrates an example image formed by a projector at a target and yet another example reference image in accordance with yet another aspect of the invention;

FIG. 6 illustrates an example image formed by a projector at a target and yet another example reference image in accordance with yet another aspect of the invention;

FIG. 7 illustrates a schematic top cross-sectional view of an AR headset showing light from a projector incident on a target in accordance with an aspect of the present invention;

FIG. 8 is a schematic side cross-sectional view of yet another example system for aligning a projector on an AR headset;

FIG. 9 is a schematic side cross-sectional view of an example system for aligning a projector on an AR headset in a transmissive mode;

fig. 10A and 10B show schematic top cross-sectional views of an AR headset in a reflective mode and a transmissive mode, respectively; and

fig. 11 is an example method of aligning a projector on an AR device.

Detailed Description

Fig. 1 shows a schematic top cross-sectional view of an example AR headset 1. The AR headset 1 is formed by a housing 2 housing a pair of projectors 4a, 4 b. The housing 2, also referred to as a frame, forms a structure that holds the components of the AR headset 1 relative to each other. The housing 2 has a first portion 13 with two cavities 12a, 12b. Each projector 4a, 4b is located within its respective cavity 12a, 12b, which is within the first portion 13 of the housing 2. Once aligned, the projectors 4a, 4b are secured within their respective cavities 12a, 12b. The housing 2 has a generally elongated shape extending along a y-axis as shown in fig. 1, wherein the projectors 4a, 4b are positioned at opposite ends of the housing 2 along the y-axis.

A pair of waveguides 6a, 6b are also located on the housing 2. Each projector 4a, 4b is associated with a particular one of the waveguides 6a, 6 b. The waveguides 6a, 6b are offset along the x-axis relative to their associated projector 4a, 4b. As shown in fig. 1, the waveguide 6a is located on the optical path of the projector 4a, and the waveguide 6b is located on the optical path of the projector 4b. Thus, each waveguide 6a, 6b is located at opposite ends of the housing to each other along the y-axis.

The housing 2 further comprises a second portion 18 separated from the first portion by a gap (along the x-axis). The attachment portion 16 of the housing 2 connects the first portion 13 and the second portion 18 at a point approximately midway between the first projector 4a and the second projector 4b. The first portion 13, the second portion 18 and the attachment portion 16 of the housing thereby form slots 14a, 14b. Each waveguide 6a, 6b is located within an associated slot 14a, 14b. Once properly positioned within their slots 14a, 14b, the waveguides 6a, 6b are secured in place with glue 15, although any other type of securing mechanism may be used. As can be seen in fig. 2, the projectors 4a, 4b protrude through the cavities 12a, 12b into the associated slots 14a, 14b, such that there is an optical path between each projector 4a, 4b and its associated waveguide 6a, 6 b.

The second portion 18 of the housing 1 comprises a pair of holes 8a, 8b, each associated with a waveguide 6a, 6b and positioned along the x-axis with respect to said waveguides 6a, 6b. The holes 8a, 8b are located on the opposite side of their associated waveguides 6a, 6b from their associated projectors 4a, 4 b. The holes 8a, 8b are in fact holes or gaps in the housing. A cover 10a, 10b is positioned over each aperture 8a, 8b on the opposite side of the aperture from the waveguide.

Attachment means (not shown) provide attachment of the headset 1 to the head of the wearer. This may include a temple piece, an elastic band configured to wrap around and/or over the head, or any other known device.

When the headset 1 is in use, light from each projector 4a, 4b passes out of the projector into its associated waveguide 6a, 6b in the x-direction as seen as ray 32. Each waveguide 6a, 6b is associated with a different eye of the user such that each waveguide 6a, 6b acts as a near-eye display. For example, waveguide 6a is associated with the left eye of the wearer, while waveguide 6b is associated with the right eye of the wearer. Further description of the use of the waveguide will be described below with respect to fig. 2.

Fig. 2 is a schematic side cross-sectional view of an example system 100 for aligning a projector 4a on an AR device 1 as shown in fig. 1. The same features are shown with the same reference numerals as in fig. 1

The same reference numerals are used. Projector 4a is located in chamber 12a, although the projector is not already in chamber 12a

Aligned with respect to the housing 2. The cover 10a is also not located over the aperture 8 a. AR headset 100

In the reflective mode, because the user 201 views the virtual image from the same side of the waveguide as the projector 4a is located.

The left eye 201 of the wearer is shown adjacent the waveguide 6a. The screen 101 is located on the opposite side of the waveguide 6a from the wearer's eye 201 (i.e., displaced along the x-direction). The screen 101 may be a wall, temporary screen, or other suitable surface on which one or more reference images are located (as will be described below with respect to fig. 4A-4D).

Further details of the waveguide 6a are shown in fig. 2, which cannot be seen in fig. 1. The waveguide has an input grating 20a located at the end of the waveguide 6a where the projector 4a is located. The input grating 20a is a reflective diffraction grating. It is located on the face of the waveguide 6a closest to the aperture 8a, i.e. furthest from the projector 4 a. The waveguide 6a also has an output grating 22a positioned towards the end of the waveguide 6a opposite the input grating. The output grating 22a is on the same side of the waveguide 6a as the input grating 20a.

The path of light from projector 4a during the alignment process is shown in fig. 2. As shown by ray 32, light from projector 4a is incident on input grating 20a of waveguide 6a along the x-direction. As shown by ray 36, input grating 20a couples a portion of the light into waveguide 6a. Light 36 coupled into the waveguide will be turned so that it expands in the-z direction and + -y direction. This provides a 2D expansion of the light. As can be seen in fig. 2, the light travels along the waveguide 36 by total internal reflection until it reaches the output grating 22a. Light is then coupled out to the eye 201 to form a virtual image at the eye 201. This path 36 of light through the waveguide is a path that when coupled out to the eye 201 forms an AR image that is viewed by the wearer.

However, a portion of the light is not coupled into waveguide 6a along ray 36. The input grating 20a is not 100% efficient and a portion of the light passes directly through the input grating 20a along the x-direction, the portion of the light traveling substantially in the x-direction. In a typical AR device, this contribution will be ignored, as it will be absorbed by the housing 2. However, in the present alignment system 100, as indicated by ray 34, the light passes directly through the input grating 20a and then through the aperture 8a. The light 34 is then incident on the screen 101. In this way, the light rays 34 form an image at the screen 101, which represents the image emitted by the projector 4a that has not yet been coupled into the waveguide 6 a. As will be described below, the reference image on the screen 101 may be used to align the projector 4a relative to the housing 2.

As outlined above, fig. 2 shows only a part of the headset 1 during the alignment process. Fig. 3 shows a schematic top cross-sectional view of the AR headset 1 with the second projector 4b in the aligned process. As can be seen in fig. 3, light 34b passes through an aperture 8b in the housing 2 of the headset 1 for aligning the projector 4 b. The projector 4a in fig. 3 has been aligned before the alignment process of the projector 4 b. The cover 10a has been secured over the aperture 8a to prevent light from being emitted from the device through the aperture 8a. Light traveling through the aperture 8a is absorbed by the cover 10 a. Although ray 34b is shown as a single ray, it will have some angular spread.

Fig. 4A to 4D show the screen 101 when viewed from the position of the wearer shown in fig. 2. Located on the screen is a reference image 42 for alignment of the projectors 4a, 4 b. The reference image 42 is formed of a horizontal line 48 and three vertical lines 44a, 44b and 46 intersecting the horizontal line and equidistant from each other. The horizontal lines 48 and vertical lines 44a, 46, 44b effectively form three cross shapes connected together by the horizontal lines 48.

Also shown in fig. 4A-4D are images 50a and 50b. The image 50a is formed by light 34 from projector 4a which has passed through the input grating 20a and aperture 8a before being incident on the target 101. The image 50b is formed by the equivalent of the light 34 from the projector 4b that has passed through the input grating (of the waveguide 6 b) and the aperture 8b before being incident on the target 101.

Fig. 4A to 4D also show an image 52a and an image 52b. These images are virtual images and are not actually present at the screen 101. The image 52a corresponds to an image viewed by the wearer formed by the light 38 coupled out of the output grating 22a of the waveguide 6 a. The image 52b corresponds to the image viewed by the wearer formed by the light 38 coupled out of the output grating of the waveguide 6 b. Each of the images 50a, 50b, 52a and 52b is cross-shaped.

Alignment of projector 4a on housing 2 is achieved by aligning image 50a with reference image 42 such that the cross directly covers the intersection between vertical line 44a and horizontal line 48. Likewise, alignment of projector 4b on housing 2 is achieved by aligning image 50b with reference image 42 such that the cross directly covers the intersection between vertical line 44b and horizontal line 48.

Once alignment of the projectors 4a and 4b is achieved by aligning the images 50a and 50b as described above, correction of the positioning of each of the waveguides 6a and 6b is required to ensure convergence of the virtual images viewed by each of the wearer's eyes when viewed through the output grating. This is accomplished by aligning images 52a and 52b with vertical line 46 such that the cross shape of image 52a and the cross shape of image 52b directly cover the intersection between vertical line 46 and horizontal line 48.

The screen 101 is positioned at a distance at which the virtual images are desired to converge. Thus, by viewing the images 52a, 52b, convergence can be achieved as described above. Furthermore, when the housing is at a known position relative to the target, the reference image (e.g., 42) on the screen is selected to represent the correctly aligned positioning of the projector (and waveguide). Thus, when the alignment process is performed, the housing 2 is in a known position and orientation relative to the screen.

As can be seen in fig. 4A, none of the projectors 4A, 4b are properly aligned, e.g. fig. 4A may indicate that at that time the projectors 4A, 4b are first placed on the housing 2. Although the projector may be generally aligned when placed on the housing 2 such that the light 32 is substantially parallel to the x-direction and thus passes through the aperture in the housing, precise alignment is required in these AR devices. By adjusting the position of the projectors 4a, 4b on the housing 2, a correct alignment can be achieved. Adjusting the position of the projectors 4a, 4b may include angular adjustment of the projectors 4a, 4 b. These angular adjustments may be made by pitch, yaw and/or roll. This may include, for example, moving the projector 4a, 4b up or down, left or right, or tilting the projector forward or backward, depending on the position and orientation of the image 50a, 50b relative to the reference image.

Fig. 4B shows an image 50a aligned with the reference image such that it directly overlays the cross formed by the intersection between vertical line 44a and horizontal line 42. This is achieved by tilting the projector 4A up and to the right relative to its positioning in fig. 4A. This means that the projector 4a is properly aligned. At this stage, the positioning of projector 4b has not been adjusted as compared with that in fig. 4A.

Fig. 4C shows an image 50b aligned with the reference image such that it directly overlays the cross formed by the intersection between vertical line 44b and horizontal line 42. This is achieved by tilting the projector 4B up and to the left with respect to its positioning in fig. 4B. This means that the projector 4b is properly aligned. Projector 4a is not moving and still is properly aligned as indicated by image 50a at the same location as in fig. 4B.

Thus, in fig. 4C, alignment of the two projectors 4a, 4b with respect to the housing is achieved.

Once both projectors 4a, 4b are properly aligned with respect to the housing, alignment of waveguides 6a, 6b is required to ensure convergence of images 52a, 52 b. As can be seen in fig. 4C, images 52a and 52b do not converge. Thus, the angular position of both waveguides 6a, 6b can be adjusted by moving the waveguides by pitch and yaw. The waveguides 6a, 6b are adjusted simultaneously or consecutively until the images 52a and 52b overlap each other and so that they cover the cross formed by the intersection of the vertical line 46 and the horizontal line 48, as shown in fig. 4D. Fig. 4D shows the positions of the images 50a, 50b, 52a, 52b when the projectors 4a, 4b and the waveguides 6a, 6b are properly aligned on the housing 2. Once this is achieved, the projectors 4a, 4b and the waveguides 6a, 6b may be fixed to the housing such that their positioning is not movable. This may include glue or other securing means as discussed above.

The reference images shown in fig. 4A to 4D are just one example of how alignment may be performed. Fig. 5 shows an alternative arrangement of reference images located at the target screen 101. The images 50a, 50b are images from the projectors 4A, 4b, as outlined above with respect to fig. 4A-4D. The images 52a, 52b are virtual images viewed from the projectors 4A, 4b, as outlined above with respect to fig. 4A-4D. The target reference image is formed of three squares 54a, 56, 54b offset from each other along the horizontal axis.

Square 54a indicates the correct alignment of projector 4 a. Therefore, in order to achieve alignment of the projector 4a, the center of the cross of the image 54a must be positioned at the center of the square 54 a. As shown in fig. 5, the projector 4a is properly aligned.

Square 54b represents the correct alignment position of projector 4 b. Therefore, in order to achieve alignment of the projector 4b, the center of the cross of the image 54b must be positioned at the center of the square 54 b. As shown in fig. 5, the projector 4b is not properly aligned.

Square 56 represents the location to which the images 52a, 52b must be aligned to ensure proper alignment of the waveguides 6a, 6b, thereby ensuring convergence of the images from the two projectors 4a, 4 b. As shown in fig. 5, this alignment of the waveguides has not been achieved.

Fig. 6 shows an alternative arrangement of reference images located at the target screen 101. The example shown in fig. 6 shows a series of three cross-shaped reference images spaced apart from each other.

Cross 58a represents the correct alignment of projector 4 a. Therefore, to achieve alignment of projector 4a, image 50a must be positioned over cross 58 a. Cross 58b indicates the correct alignment of projector 4 b. Thus, to achieve alignment of projector 4b, image 52b must be positioned over cross 58 b. The cross 60 represents the location to which the images 52a, 52b must be aligned to ensure proper alignment of the waveguides 6a, 6b to ensure convergence of the images. As shown in fig. 5, the alignment of the waveguides 6a, 6b and the projectors 4a, 4b has not been achieved. It can be seen that comparing image 50a to reference image 58a, image 50a requires roll angle adjustment due to the original position of the image.

Although it is described above that the waveguide is already in place when the projector alignment is performed, this need not be the case. For example, the waveguides may be added after alignment of images 50a and 50b has been performed. By this method of adding the waveguide to the housing after this initial alignment, the virtual images 52a, 52b will not be visible until the waveguide is added. After adding the waveguide, the alignment of the images 50a, 50b may require further slight adjustment when in the reflective mode, due to slight shifting of these images caused by the action of the waveguide.

Fig. 7 shows a schematic top cross-sectional view of AR headset 1 and screen 101. As can be seen, the rays 64A, 64b show the view of the wearer as seen through the waveguides 6a, 6b, forming virtual images 52a, 52b as described above with respect to fig. 4A-4D. For example, ray 64a forms image 52a, and ray 64b forms image 52b. The screen 101 is at a convergence distance. As can be seen, convergence has been achieved as shown in fig. 4D.

Fig. 8 is a schematic side cross-sectional view of a further example system 200 for aligning a projector 4a on an AR device 1 as shown in fig. 1. The difference between the system 100 shown in fig. 2 and the system 200 shown in fig. 8 is that the camera 102 is used to collect the light 34 after exiting through the aperture 8a of the housing 2, instead of collecting the light projected directly on the screen 101 in which the image is formed. The camera 102 is connected to an electronic display (not shown) on which an image is displayed to show the positioning of the image relative to a fixed reference point indicating the correct aligned positioning of the image. For example, the display may display image 50a and reference image 58a, as shown in FIG. 6. The user may then adjust the positioning of projector 4a by using image 50a displayed on the display as a guide until the image is displayed on the display overlapping reference image 58 a.

An advantage of using the camera 102 in this arrangement rather than projecting directly onto the screen is that less physical space is required for performing projector alignment. The camera device need not be at a convergence distance from the AR headset 1 as is typically required for the screen 101.

The camera 102 may be coupled to one or more computing devices capable of processing the detected light to correct for any distortion in the formed image to facilitate alignment.

The same camera 102 may be used to align the two projectors 4a, 4b. For example, once projector 4a has been properly aligned, the camera device may be placed adjacent aperture 8b through which projector 4b emits light 34. In other arrangements, there may be a separate camera 102 for aligning each projector 4a, 4b. In this way, the two projectors 4a, 4b may be displayed on the display at the same time and, if desired, aligned at the same time.

Even when the image pickup device 102 is used to align the projectors 4a, 4b, the screen 101 can still be used to ensure that the correct waveguide alignment is achieved, for example using the reference image 60 shown in fig. 6, thereby ensuring convergence of the images.

The positioning of the image pickup device is not limited to that shown in fig. 7, and the image pickup device may be moved or positioned appropriately. In other arrangements, the camera may alternatively be positioned adjacent to the output region of the waveguide where the eye 201 is located. In this arrangement, the screen 101 can also be presented with an image pickup device that views the screen 101 by outputting a raster to view images (both real images and virtual images) as shown in fig. 4 to 6. The view seen by the camera may then be output to a computer monitor that the user may view and make relevant adjustments to the positioning of the projector and, if necessary, the waveguide as described above. Advantageously, using the camera device in this manner, rather than the user's eyes, may help provide a stable image, thereby improving the accuracy of alignment.

Fig. 9 shows a schematic side cross-sectional view of an example system 100 for aligning a projector 4a on an AR device 1 as shown in fig. 1. The same features are shown with the same reference numerals as in fig. 1 and 2. In the system shown in fig. 9, the waveguide acts in a transmissive mode rather than a reflective mode as in fig. 2. In other words, the user's eyes are on the opposite side of the waveguide from the projector.

The method of aligning the projector 4a when in the transmissive mode is slightly different from the method of aligning the projector when in the reflective mode. In the transmissive mode, alignment of the projector may be performed as described above. For example, the real images 50a and 50b are aligned with on-screen references 58a and 58b, respectively. However, when in the transmissive mode, the adjustment of the waveguide has no effect on the convergence of the virtual image. Thus, alignment of the virtual images 52a and 52b as described above for the reflection mode is not required. As shown in fig. 9, when the user looks through the waveguide 6a, the virtual image is converged by only making an adjustment to the projector. This difference can be illustrated by the following facts: the waveguide acts as a window in transmission and as a mirror in reflection, and is therefore insensitive to angular offset in transmission mode.

Fig. 10A and 10B show schematic top views of an AR headset according to further arrangements when in a reflective mode (fig. 10A) and a transmissive mode (fig. 10B).

Looking first at fig. 10A, fig. 10A illustrates the AR device in a reflective mode, it can be seen that the real images 50A and 50b (as described with respect to fig. 4A-4D) can be considered as divergent images as shown when viewed from the perspective of the output region of the waveguide through the user's eye 201 or camera. These divergent images may be aligned with the reference image as previously described to ensure that the projector is at the desired position. Once the waveguides 6a, 6b are placed on the housing, the virtual images 52a, 52b may be viewed and, by adjustment of the waveguides 6a, 6b, the virtual images may be converged as described above with respect to fig. 4A-4D.

Turning now to fig. 10B, fig. 10B shows the AR device in a transmissive mode, it can be seen that, in view of the nature of the device, alignment of the projector is performed by looking in the opposite direction to that shown in fig. 10A. In this arrangement, images 50a and 50b, such as those shown in fig. 4A to 4D, may be viewed by a user or an imaging device on wall 101 where the divergent images are again displayed. The virtual images 52a, 52b are converged by alignment of the projector's use images 50a, 50b without requiring adjustment of the waveguide to achieve convergence of the virtual images.

In the system shown in fig. 10A and 10B, the images 50A and 50B may be viewed after the waveguides 6a, 6B are added to the housing as described above, but the images 50A and 50B may also be viewed before the waveguides 6a, 6B are placed on the housing 2 as outlined before.

An additional difference of the AR device 100 shown in fig. 10A and 10B from that shown in the other figures is that the projectors 4a, 4B are not positioned such that light emitted from the projectors is directly incident on the waveguides 6a, 6B after being emitted by the projectors. Instead, the projector is positioned such that light is emitted in the ±y directions. The prisms 11a, 11b are positioned adjacent to each projector 4a, 4b along the y-axis such that the prisms turn the light so that the light travels in the x-direction before being coupled into the waveguides 6a, 6b and passing through the apertures 8a, 8b as described above. It should be understood that the positioning of the projectors 4a, 4b as described above may include the positioning of the projectors 4a, 4b, the prisms 11a, 11b, or both the prisms and the projectors.

Fig. 11 is a flowchart listing an example method of aligning a projector on Augmented Reality (AR) as described in detail above.

At step 801, the method includes positioning a projector on a housing of an AR or VR device that includes a housing for holding the projector and waveguide of the AR or VR device relative to one another, the housing including an aperture disposed adjacent an input area of the waveguide when the waveguide is positioned on the housing and spaced apart from the input area along a first direction on a side of the input area opposite the projector.

At step 803, the method includes coupling light from a projector through an aperture in a housing in a first direction such that the light forms an image at a target.

At step 805, the image formed at the target is compared to a reference point.

At step 807, the positioning of the projector relative to the housing is adjusted until the image formed at the target is at a desired positioning relative to the reference point, which indicates that the projector is properly aligned on the housing.

The projector 4a, 4b as outlined above may be any type of light engine capable of projecting light into a waveguide. This may be any type of micro projector. For example, the projector may include a liquid crystal on silicon, an LCOS panel, and a light source. The LCOS panel may be positioned in the optical path between the light source and the input region of the waveguide. The LCOS panel may be responsible for forming an image using light incident on the LCOS panel from a light source. The image may then be projected as an input pupil onto an input region of the waveguide. The light source may be an LED array. Alternatively, any other type of image generation device or light source may be used. For example, the light source may be a lamp. The panel may be any type of non-self-emissive panel including transmissive liquid crystal displays, reflective liquid crystal panels, digital light processing panels, or dynamic mirror arrays. The projector may be multi-colored. Alternatively, the projector may be monochromatic.

Having described aspects of the present disclosure in detail, it will be apparent that numerous other alternatives or modifications to the arrangement described above, which should be possible, are present without departing from the scope of the aspects of the present disclosure as defined in the appended claims.

The housing 2 shown in the above examples is only one example of a housing and should not be considered as limiting. For example, any other arrangement of housings may be used. This may depend on the nature of the AR/VR device, such as eyeglasses, goggles, or any other type of AR/VR device.

Furthermore, the positioning of the projectors 4a, 4b as described above should not be considered limiting. For example, rather than being positioned such that light from the projector is coupled directly into the waveguide, in other arrangements one or more optical components may be positioned in the optical path between the projector and the waveguide to ensure light coupling into the waveguide. For example, the projector may be arranged such that it emits light perpendicular to the direction shown in fig. 1, for example, along the y-direction, as shown in fig. 10A and 10B. In such an arrangement, a prism, mirror or other optical component may be used to alter the path of the light from the projector so that the light is still incident on the waveguide. Adjusting the positioning of the projector may also include adjusting the positioning of the further optical component to ensure alignment.

The number of projectors is not limited to two. In other arrangements, there may be only a single projector, and an alignment system may be used to align the single projector. In other arrangements, there may be more than two projectors.

Rather than having a cover for masking the aperture after alignment is complete, any other means of preventing light from passing through the aperture may be used. For example, the hole may be filled instead of placing a cover over the hole. For example, the holes may be filled with any of a polymer, silicone, cement, or any other insertable plug.

The input grating as shown in the figures as described above is a reflective input grating. However, the invention is not limited thereto, and the input grating may alternatively be operated in a transmissive mode. Likewise, the output grating may be reflective and/or transmissive.

The alignment of the projector is described above as being performed by the user. However, the system may equally be used in a feedback loop in which the machine is responsible for adjusting the positioning of the projector, for example when using an imaging device as described above.

The display used to display the image captured by the camera 102 as described above may be a monitor or any other type of visual display to which the camera may be connected. The screen 101 may be a wall or screen placed for alignment.

The above-described device 1 is a headset. However, such an alignment method/system may be used to align projectors on any type of AR device. Furthermore, it is not particularly limited to AR, but may be used for VR devices.

Once the projector and waveguide are properly positioned, they can be glued in place to ensure that their position is fixed. Alternatively, or in addition, any other fixation means may be used. For example, any type of adhesive may be used, or additional components may be attached to the housing to hold them in place.

In other arrangements, alignment of the projector may be performed before the waveguide is attached to the housing. In this way, the projector may be positioned adjacent to the aperture and the comparing and aligning performed with respect to the reference image.

Claims (15)

1. An Augmented Reality (AR) or Virtual Reality (VR) device, the AR or VR device comprising:

a waveguide comprising an output region and an input region configured to receive light incident along a first direction, wherein the waveguide is configured such that a first portion of the light propagates along the waveguide in a direction substantially perpendicular to the first direction towards the output region by total internal reflection, in which output region the first portion of the light is coupled out to a viewer to form an image;

A projector disposed adjacent to the waveguide, the projector for projecting the light into the waveguide at the input region;

a housing for holding the projector and the waveguide relative to each other, the housing comprising an aperture disposed adjacent to the input area and spaced apart from the input area along the first direction on a side of the input area opposite the projector.

2. The apparatus of claim 1, wherein the aperture extends through the housing in the first direction.

3. The apparatus of any one of claims 1 or 2, wherein the aperture has a first end and a second end such that the aperture extends from the first end to the second end, the first adjacent the input region, wherein the aperture is closed at the second end.

4. A device according to claim 3, wherein a cover is positioned at the second end of the aperture such that the aperture is closed at the second end.

5. The apparatus of any preceding claim, wherein the input region is a diffraction input grating.

6. The apparatus of any preceding claim, wherein the apparatus comprises a pair of projectors and a pair of waveguides, each having an associated aperture, the aperture being arranged adjacent to an input region of an associated waveguide of the aperture, and the aperture being spaced apart from the input region along the first direction on a side of the input region opposite to the associated projector of the aperture.

7. A method of aligning a projector on an Augmented Reality (AR) or Virtual Reality (VR) device, the AR or VR device including a housing for holding the projector and a waveguide of the AR or VR device relative to one another, the housing including an aperture disposed adjacent an input area of the waveguide when the waveguide is located on the housing and spaced apart from the input area along a first direction on a side of the input area opposite the projector, the method comprising:

positioning the projector on the housing;

coupling light from the projector through the aperture in the housing in the first direction such that the light forms an image at a target;

comparing the image formed at the target with a reference point;

the positioning of the projector relative to the housing is adjusted until the image formed at the target is at a desired positioning relative to the reference point, which indicates that the projector is properly aligned on the housing.

8. The method of claim 7, wherein the reference point is a reference image having at least one characteristic to which the image formed at the target is to be aligned.

9. The method of claim 8, wherein the at least one characteristic is a shape of at least a portion of the reference image, and the shape of at least a portion of the image formed at the target is the same as the shape of at least a portion of the reference image.

10. The method of any one of claims 7 to 9, further comprising capturing the image formed at the target with a camera; and

displaying the reference point and the image formed at the target on a screen, and performing the comparing and the adjusting.

11. The method of any of claims 7-10, wherein positioning the projector on the housing comprises positioning the projector on the housing adjacent to an input region of the waveguide; and

wherein coupling light from the projector through the aperture in the housing along the first direction such that the light forms an image at a target further comprises:

coupling light from the projector onto an input region of the waveguide such that the light is incident on the input region in a first direction such that:

A first portion of the light propagates along the waveguide in a direction substantially perpendicular to the first direction by total internal reflection toward an output region of the waveguide for outcoupling the light to a viewer; and

the light of the second portion passes directly through the waveguide and through the aperture in the housing in the first direction such that the light of the second portion forms an image at a target.

12. The method of claim 11, wherein the projector and the waveguide are a first projector and a first waveguide, and the AR or VR device includes a second projector and a second waveguide, the method further comprising aligning the second projector on the housing by performing the method of any of claims 7-11 for the second projector.

13. The method of claim 12, further comprising, after the first projector and the second projector are properly aligned on the housing:

viewing a first image formed by light from the first portion of the first projector after being coupled out at an output region of the first waveguide;

viewing a second image formed by light from the first portion of the second projector after being coupled out at an output region of the second waveguide;

The positioning of the first and second waveguides is adjusted until the first and second images are overlaid on each other.

14. The method of any of claims 7 to 13, further comprising applying a cover to the aperture of the housing after the projector is properly aligned such that light can no longer pass through the aperture.

15. A system for aligning a projector on an Augmented Reality (AR) or Virtual Reality (VR) device, the system comprising:

an AR or VR device comprising a projector, a housing for holding the projector and a waveguide of the AR or VR device relative to each other, the housing comprising an aperture arranged adjacent an input area of the waveguide when the waveguide is located on the housing, and the aperture being spaced apart from the input area along a first direction on a side of the input area opposite the projector; and

a target for providing a reference point with which an image formed on the target can be compared to thereby align the projector on the housing, wherein the system is configured to perform the method of any of claims 7 to 14.