Binocular extended reality display alignment based on eye position

Abstract

Non-transitory computer-readable media described herein store instructions that, when executed by at least one processor, direct a display device with a first display for a first eye and a second display for a second eye to perform processes for binocular extended reality display alignment based on eye position. For example, one illustrative process may include: changing between a monocular presentation of an image on the first display and a binocular presentation of the image on the first display and the second display; detecting an eye position modification associated with the second eye in response to the changing between the monocular presentation and the binocular presentation; and determining, based on the eye position modification associated with the second eye, an alignment of the first display with respect to the second display. Corresponding methods and devices are also disclosed.

Description

BINOCULAR EXTENDED REALITY DISPLAY ALIGNMENT BASED ON EYE POSITIONBACKGROUND

[0001] Extended reality is an umbrella term referring to various technologies that serve to augment, virtualize, or otherwise extend a user’s experience of reality in a variety of ways. For example, virtual reality, augmented reality, mixed reality, and other types of extended reality have been developed and deployed for use with entertainment, educational, vocational, and other types of applications. In certain cases, extended reality experiences may be presented on handheld devices such as smartphones or laptop computers viewed from a few feet away. In other cases, extended reality experiences may be presented by way of headmounted display devices that immerse users more fully in virtual or augmented worlds by presenting images in front of the user’s eyes.SUMMARY

[0002] Implementations described herein are configured to manage binocular extended reality display alignment based on eye position. When a monocular presentation of an image (i.e., a presentation in which an image is displayed only for one eye while no image content is displayed for the other eye) is presented to a user of a binocular display device (i.e., a display device that includes dedicated displays for each eye, such as, for instance, a headmounted display device), both eyes of the user tend to align and synchronize in a way that is comfortable and desirable for the user. In other words, the eye that is not being presented with image content will tend to stay properly aligned with the eye that is viewing the image. When a binocular presentation of misaligned images (i.e., a presentation in which the image, or corresponding versions of the image, is displayed for both eyes at once) is presented, however, the eyes may tend to come out of alignment as the eyes attempt to correlate and interpret the misaligned images (causing visual discomfort, headache, eye fatigue, and / or other undesirable consequences in the process). Accordingly, methods and systems described herein monitor eye movements of a user when a binocular presentation changes to a monocular presentation and / or when a monocular presentation changes to a binocular presentation. Based on these eye movements (and particularly a detected change of eye position of the eye that is not presented with content during the monocular presentation, referred to herein as an eye position modification), devices described herein are configured todetermine the alignment of the two displays on a display device. This information may be used to calibrate (and / or to update a calibration of) the display device to ultimately help provide a comfortable and high-quality user experience and reduce the discomfort and other undesirable consequences mentioned above.

[0003] To this end, one implementation described herein involves a non-transitory computer-readable medium storing instructions that, when executed by at least one processor, direct a display device with a first display for a first eye (of a user of the display device) and a second display for a second eye (of the user) to perform a process. For example, the process may include: 1) changing between a monocular presentation of an image on the first display and a binocular presentation of the image on the first display and the second display; 2) detecting an eye position modification (e.g., an eye movement) associated with the second eye in response to the changing between the monocular presentation and the binocular presentation; and 3) determining, based on the eye position modification associated with the second eye, an alignment of the first display with respect to the second display. One purpose of determining the alignment (and thereby potentially identifying a misalignment) may be to trigger an alignment calibration operation. Such an alignment calibration operation may include initially calibrating (e.g., at the beginning of a new session in which the display device will be operated, etc.) how the displays are aligned and / or updating or correcting the alignment calibration (e.g., during the session). In response to triggering the alignment calibration operation, at least one calibration parameter may be initialized (i.e., set) and / or updated for use by the display device to control how image content presented by the first display is aligned (e.g., vertically aligned) with corresponding image content presented by the second display. It will be understood that this process that has been described as being stored as instructions in a computer-readable medium may also be performed as a method, performed by at least one processor of a display device, and / or otherwise implemented in various ways described herein.

[0004] Another example implementation described herein involves a method that may be performed by a display device that includes a first display for a first eye and a second display for a second eye. For instance, the method may include: 1) performing a binocular presentation of an image on the first display and the second display; 2) determining a first position of the second eye during the binocular presentation; 3) changing the binocular presentation to a monocular presentation of the image on the first display; 4) determining a second position of the second eye during the monocular presentation; and 5) determining, based on the first position of the second eye and the second position of the second eye, analignment of the first display with respect to the second display. It will be understood that this method may be embodied as instructions stored in a non-transitory computer-readable medium, may be performed by at least one processor of a display device, or otherwise implemented in various ways described herein.

[0005] Another example implementation described herein involves a display device that includes a first display for a first eye, a second display for a second eye, a memory storing instructions, and at least one processor communicatively coupled to the memory and configured to execute the instructions to perform a process. For example, the process may include: 1) performing a monocular presentation of an image on the first display; 2) determining a first position of the second eye during the monocular presentation; 3) changing the monocular presentation to a binocular presentation of the image on the first display and the second display; 4) determining a second position of the second eye during the binocular presentation; and 5) determining, based on the first position of the second eye and the second position of the second eye, an alignment of the first display with respect to the second display. It will be understood that this process that has been described as being performed by at least one processor of a display device could also be stored as instructions in a computer- readable medium, performed as a computer-implemented method, and / or otherwise implemented in various ways described herein.

[0006] Various additional operations may be added to these processes and methods as may serve a particular implementation, examples of which will be described in more detail below. Additionally, it will be understood that each of the processes and operations described as being performed by different types of implementations in the examples above (e.g., the non-transitory computer readable medium, the method, the display device, etc.) may additionally or alternatively be performed by other types of implementations as well. For example, a process described above as being included in a computer readable medium could be performed as a method or could be performed by at least one processor of the display device. Similarly, the method set forth above could be encoded in instructions stored by a computer readable medium or stored within the memory of the display device, and so forth.

[0007] The details of these and other implementations are set forth in the accompanying drawings and the description below. Other features will also be made apparent from the following description, drawings, and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 shows certain aspects of one illustrative implementation of binocularextended reality display alignment based on eye position in accordance with principles described herein.

[0009] FIG. 2 shows an illustrative display device configured to perform binocular extended reality display alignment based on eye position in accordance with principles described herein.

[0010] FIG. 3 shows an illustrative method for binocular extended reality display alignment based on eye position in accordance with principles described herein.

[0011] FIG. 4A shows a first type of alignment calibration cycle in accordance with principles described herein.

[0012] FIG. 4B shows an illustrative method associated with the alignment calibration cycle illustrated in FIG. 4A in accordance with principles described herein.

[0013] FIG. 5A shows a second type of alignment calibration cycle in accordance with principles described herein.

[0014] FIG. 5B shows an illustrative method associated with the alignment calibration cycle illustrated in FIG. 5 A in accordance with principles described herein.

[0015] FIG. 6A shows illustrative aspects of how a plurality of alignment calibration cycles may be used to determine and / or modify a calibration parameter for a display device in accordance with principles described herein.

[0016] FIG. 6B shows illustrative aspects of when the plurality of alignment calibration cycles of FIG. 6 A may be performed with respect to time in accordance with principles described herein.

[0017] FIG. 7 shows an illustrative computing system that may be used to implement various devices and / or systems described herein.DETAILED DESCRIPTION

[0018] Implementations described herein are configured to manage binocular extended reality display alignment based on eye position. Visual discomfort can be a major impediment to adoption of extended reality technologies, particularly when the extended reality experience is presented by way of a binocular display device that has dedicated displays positioned in front of the two eyes of the wearer (e.g., head-mounted display devices, etc.). One cause of this discomfort may arise from vertical misalignment between images presented at each eye. Unlike normal binocular vision of the real world, where each eye views the same objects from slightly different vantage points, a user wearing a headmounted display device is presented with different (albeit related) images at each eye. Theseseparate images may be vertically misaligned as a result of mechanical issues (e.g., headset deformation, bumps, vibrations, mechanical stress, temperature changes, etc.), software issues (e.g., errors in the separate render pipelines for each display, erroneous assumptions about virtual scene geometry, etc.), and / or other problems. These technical problems arise with all types of head-mounted display devices (e.g., including bulkier virtual reality headsets), but may be especially problematic and difficult to detect and address for more smaller and lower-profile display devices that are emerging (e.g., lightweight augmented reality glasses, etc.).

[0019] As used herein, a misalignment may relate to a deviation of a reference position of two objects (displays, eyes, etc.) relative to each other about more than a tolerance value along or about a spatial axis. For example, a misalignment between two eyes of a user of a display device may occur when the user’s eyes are not vertically aligned (e.g., within a particular tolerance) along an interocular axis that horizontally passes through the centers of both retinas. Similarly, a misalignment between two displays of a display device may occur when corresponding content presented by each screen is not vertically aligned (e.g., within a particular tolerance) along a similar horizontal axis from content on one display to corresponding content on the other display.

[0020] Even a small misalignment (far less than one degree) can lead to significant discomfort for a user of a display device, including eye strain and fatigue, headache, confusion, vertigo, and the like. In some cases, a relatively minor misalignment may even prevent the user’s brain from correlating binocular images to properly interpret the images as depicting the same content (causing the user to see double and interpret the presentation as two separate instances of image content rather than as unitary image content). For all of these reasons, alignment calibration presents an important but difficult technical problem or technical challenge for binocular extended reality display devices (e.g., augmented reality and / or virtual reality head-mounted devices, etc.).

[0021] To address the technical problem of initial and continual vertical alignment calibration between separate displays of a display device, methods and devices described herein use binocular extended reality display alignment based on eye position as detected using eye tracking technology. In other words, rather than attempting to detect and account for miniscule mechanical deformations or software errors as previous approaches to the problem have done, methods and devices described herein provide at least one technical solution that takes advantage of information revealed by the user’s brain itself. More specifically, as mentioned above, the eyes tend to remain in vertical synchronization undernormal circumstances (i.e., when one eye moves, the other follows). This is true even when one eye is presented with an image and the other is not. Only when both eyes are presented with slightly misaligned images that the brain is trying to reconcile do the eyes come out of alignment (thereby resulting in the discomfort described above). Accordingly, as will be described in more detail below, at least one technical solution is presented herein to use information detectable as a result of these involuntary eye movements to initially calibrate (and later update the calibration of) the vertical alignment of a display device featuring separate displays for each eye. For example, an image may be shown to only a first eye with the assumption that the second eye will follow as the first views the image. The image may then be shown to the second eye as well while eye tracking detects whether the second eye makes an adjustment from its previous position (thereby coming out of alignment) as it views the image. Since perfect binocular alignment would allow the second eye to not need to move at all in response to this change, any eye movement detected may indicate how far out of alignment the second image is with the first so that it can be corrected.

[0022] At least one technical effect of this technical solution is that vertical alignment between binocular displays can be elegantly assessed and calibrated to whatever alignment is most comfortable for the user with minimal resources dedicated to addressing the problem. For example, while conventional solutions have involved dedicated cameras, waveguides, calibration time, and other resources to assess and correct vertical misalignment, technical solutions described herein make use of eye tracking resources (which would generally be included in the display device anyway) to perform vertical alignment calibration procedures that may be performed consistently and inconspicuously (e.g., in a manner that the user may not even be aware that the calibration is occurring).

[0023] Additionally, another technical effect arising from technical solutions described herein is that misalignment may be determined and corrected without regard to what caused the misalignment (e.g., whether the misalignment arose as a result of a mechanical issue, a software issue, or some other issue) and even without regard to whether the user’s eyes themselves are perfectly aligned. For example, even if a particular user suffers from a vertical heterophoria condition in which the user’s eyes themselves happen to be slightly misaligned (such that the user may be most comfortable with misaligned input normally provided by prism glasses), a technical effect of addressing the calibration problem in accordance with technical solutions described herein is that the user will automatically be presented with the alignment their brain prefers and is most comfortable with.

[0024] Various implementations will now be described in more detail with referenceto the figures. It will be understood that particular implementations described below are provided as non-limiting examples and may be applied in various situations. Additionally, it will be understood that other implementations not explicitly described herein may also fall within the scope of the claims set forth below. Systems and methods described herein for binocular extended reality display alignment based on eye position may result in any or all of the technical effects mentioned above, as well as various additional effects and benefits that will be described and / or made apparent below.

[0025] FIG. 1 shows certain aspects of one illustrative implementation 100 of binocular extended reality display alignment based on eye position in accordance with principles described herein. It will be understood that while implementation 100 shows certain features and attributes that may be present in certain examples, other features and attributes not included as part of implementation 100 and / or not explicitly illustrated in FIG. 1 may also be present in other examples.

[0026] As illustrated by implementation 100, a display device with two displays 102- 1 and 102-2 may be configured to present an image in different ways. One of these ways is referred to herein as a monocular presentation of the image. In a monocular presentation of an image, the image is presented only on one display (i.e., shown only to one of the user’s eyes) while no image content is presented on the other display (i.e., nothing is presented to the user’s other eye). For a display device implemented as a virtual reality presentation device that blocks a passage of incoming light from the environment, the non-presenting display may be temporarily disabled (turned off) or may otherwise present a black screen (or other suitable color that the brain will not interpret as content) during the monocular presentation. Similarly, for a display device implemented as an augmented reality presentation device that allows a passage of incoming light from the environment, the non-presenting display may be temporarily disabled (turned off) so as to present no content. In this example, however, the eye may still perceive light passing through the display from the environment (rather than perceiving a black screen, etc.).

[0027] To illustrate this type of presentation, implementation 100 shows a monocular presentation 104-M (‘M’ for monocular) in which display 102-1 is shown to be presenting image content (a ‘+’ -shaped reticle in this example, though it will be understood that any suitable image may be presented to the same effect), and in which display 102-2 is shown to be blank (e.g., due to being disabled, turned off, showing a black screen, showing nothing, etc.). As used herein, monocular presentation 104-M may be described as being a monocular presentation of an image on the first display 102-1. While it may not always be explicitlystated, the meaning of the monocular term implies that, during a monocular presentation such as monocular presentation 104-M, the non-presenting display (i.e., second display 102-2 in this example) is left blank or, in other words, is not presenting content.

[0028] Another way illustrated by implementation 100 for a display device to present an image is referred to herein as a binocular presentation of the image. In a binocular presentation of an image, the image is presented on both displays (i.e., shown to both of the user’s eyes) concurrently. While a single image may be referred to as being the subject of a binocular presentation, it will be understood that slightly different (yet related) images may in fact be presented on the two displays. For example, stereoscopically-related images presented on the screens to produce a three-dimensional (3D) visual effect for the user will be referred to as a single image presented by both displays for purposes of the binocular presentation.

[0029] To illustrate this type of presentation, implementation 100 shows a binocular presentation 104-B (‘B’ for binocular) in which both displays 102-1 and 102-2 are shown to be presenting the same image content (a ‘+’-shaped reticle in this example, though, again, it will be understood that any suitable image may be presented to the same effect). While the illustrated image content (the ‘+’ -shaped reticle) appears identical for simplicity of illustration, it will be understood that slight differences in the content presented by each display during the binocular presentation may be present (e.g., to produce stereoscopic, 3D effects such as mentioned above).

[0030] While the image content itself is identical in the example of implementation 100, dotted lines extending from each of the reticle objects depicted in the image content show a discrepancy in an alignment 106 of display 102-1 with respect to display 102-2. In other words, displays 102-1 and 102-2 are shown to be vertically misaligned by the amount illustrated by alignment 106, thereby potentially putting a viewer of the displays at risk of experiencing eye strain, discomfort, and / or other undesirable effects that have been mentioned herein. While alignment 106 is illustrated as being fairly significant in FIG. 1 to emphasize the misalignment for illustrative clarity, it will be understood that a much smaller misalignment than that shown (e.g., a misalignment that may not even be consciously perceptible by a user) may still be undesirable and lead to negative effects such as have been described.

[0031] One objective of binocular display alignment implementations described herein, such as implementation 100, may be to determine alignment 106 as it is perceived by the user so that undesirable misalignment may ultimately be corrected. To this end, implementation 100 shows two eyes of a user looking at displays 102-1 and 102-2 duringboth the monocular presentation 104-M and the binocular presentation 104-B. In the case where displays 102-1 and 102-2 are included in a head-mounted display device worn by the user over the eyes, for example, these images may represent the eye position of the two eyes as detected by a user-facing camera (e.g., an eye-tracking camera, etc.) built into the headmounted display device.

[0032] In the eye images associated with monocular presentation 104-M, both eyes are shown to be aligned along an interocular axis 108 that is shown to horizontally pass through the centers of both retinas. This is because, as mentioned above, the eye that is not being presented with content during a monocular presentation (the eye looking at display 102-2 in this example) tends to naturally maintain alignment with the other eye that is being presented an image (the eye looking at display 102-1 in this example). As shown by the eye images associated with binocular presentation 104-B, however, this situation may change when the eye on the non-presenting side is suddenly presented with content (e.g., when switching from monocular presentation 104-M to binocular presentation 104-B). As that eye attempts to focus in on the same point in the misaligned image, the eye goes out of alignment from the interocular axis where it previously resided. As shown, a misalignment 110 of the two eyes when viewing binocular presentation 104-B corresponds to (and is a direct result of) the alignment 106 of the displays (in this case, the lack of alignment that the displays are exhibiting). As will be described in more detail below, by tracking eye movements to detect an eye misalignment such as misalignment 110, methods and devices described herein may determine (e.g., infer) the alignment, or lack thereof, of two display screens (e.g., alignment 106 of displays 102-1 and 102-2).

[0033] FIG. 2 shows an illustrative display device 200 configured to perform binocular extended reality display alignment based on eye position in accordance with principles described herein. For example, functions performed by display device 200 may implement eye-position-based display alignment similar to that described above in relation to implementation 100.

[0034] As shown, display device 200 may include a first display 202-1 for a first eye, a second display 202-2 for a second eye, a memory 204 that stores instructions, and a processor 206 communicatively coupled to memory 204 and configured to execute the instructions to perform a process 208 that may be encoded within the instructions stored by memory 204.

[0035] Display device 200 may be implemented as any suitable type or form factor of device as may implement the attributes being described. For example, display device 200may be implemented as a head-mounted display device that is specifically configured to be worn on the head (e.g., over the eyes) to facilitate extended reality experiences. In this type of example, the two displays 202-1 and 202-2 may be implemented by separate display panels integrated within a head-mountable enclosure (e.g., a headset, a pair of glasses, etc.). As another example, display device 200 may be implemented as a mobile device (e.g., a smartphone, etc.) that is generally configured to be held and operated at arm’s length but that may be positioned in front of the eyes (e.g., using an apparatus configured to position the device on the head and / or provide optics to convert the device into an extended reality viewer) in order to provide an extended reality experience. In this type of example, the two displays 202-1 and 202-2 may be implemented by different portions of a singular screen of the mobile device. For example, the device screen may be divided down the middle so that the two halves may be used as individual displays for extended reality sessions.

[0036] In various implementations, display device 200 may be implemented as an extended reality device of a particular type and form factor such as a virtual reality form factor, an augmented reality form factor, or the like. More particularly, in one implementation, display device 200 may be implemented as a head-mounted virtual reality presentation device (e.g., a virtual or mixed reality headset) in which both displays 202-1 and 202-2 are configured to block a passage of incoming light from an environment. In another implementation, display device 200 may be implemented as a head-mounted augmented reality presentation device (e.g., augmented reality glasses, etc.) in which the first display and the second display are configured to allow a passage of incoming light from an environment.

[0037] In this augmented reality type of example, visual content (e.g., augmented reality content) may be presented on a screen that is otherwise transparent to allow a view into the real world. As such, and as mentioned above, the user may continue to see the environment even when the screen is not presenting any image content (e.g., when the glasses are turned off, when a monocular presentation is being performed, etc.). Certain image content in this type of implementation may be registered to real world objects that are viewed directly by the user (based on light from the environment). It will be understood that such content may not be as prone to alignment issues since the content is registered to real-world objects that are viewed directly without being prone to the misalignment issue. Other content in this type of augmented reality implementation, on the other hand, may appear to be floating unregistered to any real -world object in the environment. This type of floating or unanchored image content is more prone to alignment issues, just as any image content on non-transparent displays (e.g., of the virtual reality presentation devices described above)would be. Display device 200 may be configured to assess and mitigate alignment issues in any and all of these types of situations.

[0038] Processor 206 may represent one or more of any type of computer processor or processing resources configured to execute the instructions stored in memory 204 to thereby perform process 208. In some examples, process 208 may be loaded into memory 204 from a non-transitory computer-readable medium (not shown) storing instructions that, when executed, cause processor 206 to perform process 208 in any of the ways described herein.

[0039] One way process 208 may be performed is illustrated by an illustrative method 300 for binocular extended reality display alignment based on eye position shown in FIG. 3. Method 300 shows one sequence of operations that may be performed by display device 200 to implement process 208. However, while FIG. 3 shows illustrative operations 302-306 according to one implementation, it will be understood that other implementations of method 300 could omit, add to, reorder, and / or modify any of operations 302-306 shown in FIG. 3. In some examples, multiple operations shown in FIG. 3 or described in relation to FIG. 3 may be performed concurrently (e.g., in parallel) with one another, rather than being performed sequentially as illustrated and / or described. Each of operations 302-306 of method 300 will now be described in more detail as the operations may be performed by an implementation of display device 200. The following description will also provide more information about various elements of FIG. 2, including a monocular presentation 210-M, a binocular presentation 210-B, a change 212 between these presentations (also referred to as a toggle or toggling between the presentations), an eye camera 214 included within display device 200, and an eye position modification 216 (which may be detected by eye camera 214 in response to the change 212). One or more sensors 218 (e.g., temperature sensors, acceleration sensors, clocks or timers, etc.) are also shown to be included within display device 200. As will be described in more detail below, these (and other suitable sensors) may be used for various purposes, including to trigger alignment calibration cycles involving the other elements shown in FIG. 2.

[0040] At operation 302, a display device may change (e.g., toggle, switch, etc.) between a monocular presentation of an image on a first display and a binocular presentation of the image on the first display and a second display. As will be more explicitly described and illustrated below, this change between monocular presentation 210-M and binocular presentation 210-B may go in either direction between the two types of presentations (i.e., monocular and binocular), and, accordingly, may be referred to as a toggling between thepresentations, a switch between the presentations, or the like. More particularly, referring to display device 200 in FIG. 2, display device 200 may perform one change 212 to toggle from monocular presentation 210-M (on display 202-1 only) to binocular presentation 210-B (on both displays 202-1 and 202-2). Additionally (e.g., at a later time) or alternatively, display device 200 may perform another change 212 to toggle from providing binocular presentation 210-B (on both displays 202-1 and 202-2) to providing monocular presentation 210-M (on display 202-1 only).

[0041] It will also be understood that, while this example arbitrarily describes first display 202-1 as being the presenting display for the monocular presentation 210-M (making second display 202-2 the non-presenting display for the monocular presentation) other implementations or other calibration cycles (e.g., later calibration cycles) may reverse this and use the second display 202-2 as the presenting display for the monocular presentation. Indeed, as will be described and illustrated in more detail below, it may be desirable and advantageous to switch back and forth between the two sides when a series of alignment calibration cycles (each associated with a performance of method 300 or certain operations therein) are performed. It is noted that an “OR” is shown to characterize the connections between monocular presentation 210-M and displays 202-1 and 202-2 in FIG. 2 to indicate that only one or the other display presents image content during the monocular presentation, while an “AND” is shown to characterize the connections between binocular presentation 210-B and displays 202-1 and 202-2 in FIG. 2 to indicate that both displays present image content during the binocular presentation.

[0042] At operation 304, the display device may detect an eye position modification associated with the second eye in response to the changing at operation 302 between the monocular presentation (on the first display to the first eye in this example) and the binocular presentation. Detecting an eye position modification associated with the second eye may therefore refer to a change in the second eye’s position with respect to a position of the second eye previously detected before the changing image representation (e.g., a movement of the second eye to a different position in response to the toggling of the presentation type). For example, referring to display device 200 in FIG. 2, display device 200 may use eye camera 214 (an inward-facing camera configured to perform eye tracking on the eyes as the display device is used) to detect an eye position modification 216 of the second eye in response to a toggling of second display 202-2 between presenting (during binocular presentation 210-B) and not presenting (during monocular presentation 210-M). As used herein, an eye position modification such as eye position modification 216 may refer to anymovement or adjustment of the eye position as may be detected by an eye tracking apparatus such as eye camera 214. In particular, eye position modifications may be detected in response to instances of change 212 (i.e., toggling between different types of presentations that may cause the eyes to drift into and out of alignment in accordance with the alignment of the images). For example, if the change 212 is from binocular presentation 210-B to monocular presentation 210-M, eye position modification 216 may represent an eye movement in which the second eye comes into alignment with the first eye. Conversely, if the change 212 is from monocular presentation 210-M to binocular presentation 210-B, eye position modification 216 may be an eye movement in which the second eye goes out of alignment with the first eye. Both of these scenarios will be illustrated and described in more detail below.

[0043] At operation 306, the display device may determine, based on the eye position modification associated with the second eye detected at operation 304, an alignment of the first display with respect to the second display. For example, referring to display device 200 in FIG. 2, display device 200 may determine the alignment of display 202-1 with respect to display 202-2 based on one or more eye position modifications 216 detected in response to one or more times that change 212 between monocular presentation 210-M and binocular presentation 210-B is performed. The alignment determined at operation 306 may be directly related to the amount of modification that is observed in the eye position. For example, if the change 212 leads to an eye position modification of a certain amount by the second eye (while the first eye remains static since display 202-1 remains unchanged during the toggling in this example), the alignment may be determined to be off by that certain amount (or by a value proportional to or derived from that amount).

[0044] It will be understood that certain operations 302-306 may be broken up into multiple operations. For example, as will be more explicitly illustrated in other methods below, the detecting of an eye position modification may be performed by determining a first position of the eye during one of the presentations (binocular or monocular) and then determining a second position of that eye during the other presentation after the toggling. Additionally, while not explicitly shown in FIG. 3, it will be understood that other operations may be added to method 300 as may serve a particular implementation. As one example, one purpose of determining the alignment at operation 306 may be to initially calibrate (e.g., at the beginning of a new session, etc.) how the screens are aligned and / or to update or correct the alignment calibration (e.g., during the session). This may include, for an alignment calibration operation, initializing (setting) and / or updating a calibration parameter used by the display device to control how image content presented by the first display 202-1 is verticallyaligned with corresponding image content presented by the second display 202-2.

[0045] The vertical alignment calibration between the screens may be of particular interest since horizontal vergences along interocular axis 108 may be a more natural part of 3D vision and not indicative of a display misalignment. Given this objective, another example operation that may be performed in method 300 may involve adjusting a calibration parameter used by the display device to control how image content presented by the first display is vertically aligned with corresponding image content presented by the second display. For instance, the calibration parameter may be based on the alignment, determined at operation 306, of the first display with respect to the second display. Once the calibration parameter is adjusted, later frames presented by the display device may be more closely aligned, with an ultimate goal being to achieve and maintain an alignment that results in as little change to the eye position of either eye as possible in response to a toggling between a monocular presentation and a binocular presentation.

[0046] Method 300 broadly describes an alignment calibration cycle with a toggling that may be in either direction (e.g., from a monocular presentation to a binocular presentation or vice versa) and a detection of an eye position modification that could either bring the eyes into, or put the eyes out of, a comfortable alignment. As mentioned above, method 300 actually covers at least two different types of alignment calibration cycle that may be performed (e.g., on their own, in a sequence that includes both types, etc.) as part of an overall alignment calibration procedure. Each of these types of alignment calibration cycle will now be described in more detail with reference to FIGS. 4A-5B.

[0047] FIG. 4A shows a first alignment calibration cycle 400 in which an implementation of display device 200 toggles from monocular presentation 210-M to binocular presentation 210-B, and FIG. 4B shows an illustrative method 410 associated with this alignment calibration cycle 400. FIG. 5A then shows a second alignment calibration cycle 500 in which the implementation of display device 200 toggles from binocular presentation 210-B to monocular presentation 210-M, and FIG. 5B shows an illustrative method 510 associated with this alignment calibration cycle 500. In both FIGS. 4A and 5A, display device 200 is illustrated as a head-mounted display device that will be understood to represent a head-mounted virtual reality presentation device (e.g., a virtual reality headset, etc.), a head-mounted augmented reality presentation device (e.g., augmented reality glasses, etc.), or the like. In these illustrations, both displays 202-1 and 202-2 are illustrated as circular display screens incorporated within the head-mounted display devices. Additionally, as similarly described above in relation to FIG. 1, displays 202-1 and 202-2 are shown toeither present image content (a ‘+’ -shaped reticle in these examples) or to present nothing (represented by cross hatching filling in the circle).

[0048] Referring specifically now to the example illustrated in FIG. 4A, alignment calibration cycle 400 includes a change 212-1 between monocular presentation 210-M and binocular presentation 210-B. As shown, change 212-1 includes performing monocular presentation 210-M of the image and then changing monocular presentation 210-M of the image to binocular presentation 210-B of the image. FIG. 4 A further shows an eye 402-1 observing display 202-1 and an eye 402-2 observing display 202-2 before and after the change 212-1. The depictions of eyes 402-1 and 402-2 below display device 200 will be understood to represent an example of what a tracking device such as eye camera 214 may capture during each of presentations 210-M and 210-B. Since eye 402-2 is associated with the non-presenting display (display 202-2 in this example), an eye position of eye 402-2 may be of particular interest during change 212-1. Accordingly, as shown, display device 200 may be configured to determine a first position 404-1 of eye 402-2 during monocular presentation 210-M, then, after the change 212-1 to binocular presentation 210-B, display device 200 may determine a second position 404-2 of eye 402-2.

[0049] The difference between first position 404-1 and second position 404-2 is represented by an eye position modification 216-1 that illustrates the change in eye position resulting from change 212-1 with respect to a neutral interocular axis 406 at which eye 402-1 remains positioned before and after the toggling. As shown, the eye position modification 216-1 in this example arises from eye 402-2 going out of alignment with eye 402-1 in response to the changing to binocular presentation 210-B. For example, when the reticle is suddenly presented on display 202-2, eye 402-2 may naturally move out of alignment in an attempt to reconcile what it perceives with the image being viewed by eye 402-1. Based on this eye position modification 216-1, display device 200 may determine an alignment of display 202-1 with respect to display 202-2, illustrated in FIG. 4A by a vertical misalignment 408 between the displays that corresponds with (and indeed is the cause of) eye position modification 216-1. As mentioned above, based on vertical misalignment 408, display device 200 may adjust a vertical alignment calibration parameter so as to improve the vertical alignment (i.e., reduce vertical misalignment 408) for future frames.

[0050] FIG. 4B shows an illustrative method 410 that may be used by display device 200 to perform alignment calibration cycle 400. Method 410 may be understood to be related to the method 300 described above (e.g., as an implementation thereof). However, as mentioned above, method 410 may more particularly spell out additional operations that maybe used to carry out this particular type of alignment calibration cycle in which the toggling goes from a monocular presentation to a binocular presentation. As with method 300, it will be understood that multiple operations 412-420 may be performed concurrently (e.g., in parallel) with one another, rather than being performed sequentially as illustrated and / or described. Each of operations 412-420 of method 410 will now be described in more detail as the operations may be performed by the implementation of display device 200 illustrated in FIG. 4A.

[0051] At operation 412, display device 200 may perform monocular presentation 210-M of an image (e.g., including the simple reticle image content for this example) on display 202-1. At operation 414, display device 200 may determine first position 404-1 of second eye 402-2 during monocular presentation 210-M. At operation 416, display device 200 may change monocular presentation 210-M on display 202-1 to binocular presentation 210-B of the image on display 202-1 and display 202-2. At operation 418, display device 200 may determine second position 404-2 of second eye 402-2 during binocular presentation 210- B. Accordingly, based on first position 404-1 of eye 402-2 and second position 404-2 of eye 402-2, display device 200 may determine an alignment of display 202-1 with respect to display 202-2 (represented by vertical misalignment 408). This determined alignment may then be used for any suitable purpose, such as for initializing and / or adjusting a calibration parameter used by display device 200 to control how image content presented by display 202- 1 is vertically aligned with corresponding image content presented by display 202-2.

[0052] Referring now to the example illustrated in FIG. 5 A, alignment calibration cycle 500 includes a change 212-2 between binocular presentation 210-B and monocular presentation 210-M. As shown, change 212-2 includes performing binocular presentation 210-B of the image and then changing binocular presentation 210-B of the image to monocular presentation 210-M of the image. Similar to FIG. 4A, FIG. 5 A shows eye 402-1 observing display 202-1 and eye 402-2 observing display 202-2 before and after the change 212-2. Here again, since eye 402-2 is associated with the non-presenting display (display 202-2 in this example), an eye position of eye 402-2 may be of interest during change 212-1. Accordingly, as shown, display device 200 may be configured to determine a first position 504-1 of eye 402-2 during binocular presentation 210-B, then, after the change 212-2 to monocular presentation 210-M, display device 200 may determine a second position 504-2 of eye 402-2.

[0053] The difference between first position 504-1 and second position 504-2 is represented by an eye position modification 216-2 that illustrates the change in eye positionresulting from change 212-2 with respect to a neutral interocular axis 506 at which eye 402-1 remains positioned before and after the toggling. As shown, the eye position modification 216-2 in this example arises from eye 402-2 coming into alignment with eye 402-1 in response to the changing to monocular presentation 210-M. For example, when the reticle that the second eye has been attempting to reconcile with the image being viewed by eye 402- 1 suddenly disappears from view on display 202-2, eye 402-2 may naturally relax back into alignment with eye 402-1 as it no longer needs to strain to attempt the reconciliation of the misaligned image. Based on this eye position modification 216-2, display device 200 may determine an alignment of display 202-1 with respect to display 202-2, illustrated in FIG. 5A by a vertical misalignment 508 between the displays that corresponds with (and indeed is the cause of) eye position modification 216-2. As with the example of FIG. 4A, based on vertical misalignment 508, display device 200 may adjust a vertical alignment calibration parameter so as to improve the vertical alignment (i.e., reduce vertical misalignment 508) for future frames.

[0054] FIG. 5B shows an illustrative method 510 that may be used by display device 200 to perform alignment calibration cycle 500. As with method 410, method 510 may also be understood to be related to the method 300 described above (e.g., as an implementation thereof). However, method 510 may more particularly spell out additional operations that may be used to carry out this type of alignment calibration cycle in which the toggling goes from a binocular presentation to a monocular presentation. As with methods 300 and 410, it will be understood that multiple operations 512-520 may be performed concurrently (e.g., in parallel) with one another, rather than being performed sequentially as illustrated and / or described. Each of operations 512-520 of method 510 will now be described in more detail as the operations may be performed by the implementation of display device 200 illustrated in FIG. 5A.

[0055] At operation 512, display device 200 may perform binocular presentation 210- B of an image (e.g., including the simple reticle image content for this example) on displays 202-1 and 202-2. At operation 514, display device 200 may determine first position 504-1 of second eye 402-2 during binocular presentation 210-B. At operation 516, display device 200 may change binocular presentation 210-B on displays 202-1 and 202-2 to monocular presentation 210-M of the image on display 202-1. At operation 518, display device 200 may determine second position 504-2 of second eye 402-2 during monocular presentation 210-M. Accordingly, based on first position 504-1 of eye 402-2 and second position 504-2 of eye 402-2, display device 200 may determine an alignment of display 202-1 with respect todisplay 202-2 (represented in this example by vertical misalignment 508). This determined alignment may then be used for any suitable purpose, such as for initializing and / or adjusting a calibration parameter used by display device 200 to control how image content presented by display 202-1 is vertically aligned with corresponding image content presented by display 202-2.

[0056] Both alignment calibration cycles 400 and 500 illustrated above happen to use display 202-2 as the non-presenting display during monocular presentation 210-M, as has been described. It will be understood however, that other alignment calibration cycles similar to those explicitly illustrated in FIGS. 4A-5B may instead use display 202-1 as the nonpresenting display during the monocular presentation 210-M. More particularly, a method similar to method 300 could be performed that toggles the first display and analyzes the modification of the first eye position, rather than toggling the second display and analyzing the second eye position as illustrated in examples above. For example, such a method may include: 1) toggling between a monocular presentation of the image on the second display (i.e., with the first display not presenting) and a binocular presentation of the image on the first display and the second display; and 2) detecting an eye position modification associated with the first eye in response to the toggling between the monocular presentation and the binocular presentation. Similarly, in a more detailed instance of this type of method (analogous to methods 410 and 510), a display device may: 1) perform a binocular presentation of the image on the first display and the second display; 2) determine a first position of the first eye during the binocular presentation; 3) change the binocular presentation to a monocular presentation of the image on the second display (with the first display not presenting content); and 4) determine a second position of the first eye during the monocular presentation.

[0057] Moreover, while the alignment calibration cycles illustrated and described above have generally been described in isolation (e.g., as if the cycles are performed as discrete actions), it will be understood that multiple alignment calibration cycles (e.g., multiple passes through any or all of methods 300, 410, 510, and / or the methods described in the previous paragraph, etc.) may be combined and used as part of an integrated, comprehensive alignment calibration procedure (referred to herein as a multi-cycle alignment calibration procedure). For example, if a toggling between the monocular presentation and the binocular presentation and a detecting of an eye position modification are both considered to be performed as part of one alignment calibration cycle, this alignment cycle may be included in a plurality of alignment cycles performed by a display device. Additionally, thedetermining the alignment of the first display with respect to the second display may be performed based on the plurality of alignment cycles. For example, if one alignment calibration cycle is performed with respect to the first eye (i.e., the first display is the nonpresenting display and the first eye position is analyzed as it changes) and another alignment calibration cycle is performed with respect to the second eye, the display device may determine the alignment of the first display with respect to the second display based not only on an eye position modification of the first eye (detected during the first alignment calibration cycle) but also based on an additional eye position modification associated with the second eye (detected during the second alignment calibration cycle).

[0058] FIG. 6A shows an example multi-cycle alignment calibration procedure 600 to illustrate certain aspects of how a plurality of alignment calibration cycles may be used to determine and / or modify a calibration parameter for a display device in accordance with principles described herein. As shown, multi-cycle alignment calibration procedure 600 includes a plurality of alignment calibration cycles 602-1, 602-2, 602-3, 602-4, 602-5, and 606-6, each illustrated as a numbered star. While six cycles are illustrated in this example, it will be understood that more or fewer cycles may be employed as may serve a particular implementation. Each calibration cycle 602-1 through 602-6 will be understood to represent a toggling between a monocular presentation and a binocular presentation of two displays of a display device, as well as a detection of a resulting eye position modification such as has been described above. As shown, a determination of a display alignment 604 between the displays (e.g., a vertical relationship of the displays corresponding, for example, to alignment 106 of FIG. 1, vertical misalignment 408 of FIG. 4A, vertical misalignment 508 of FIG. 5 A, etc.) may be performed based on the plurality of alignment calibration cycles 602-1 through 602-6. For example, a determination taking all these cycles into account may be performed after the cycles have all been performed or display alignment 604 may be initially determined, then repeatedly modified, with the completion of each alignment calibration cycle as it is performed over a period of time. FIG. 6A further shows that display alignment 604 may be used as a basis for determining a calibration parameter 606 (e.g., a vertical alignment calibration parameter) such as has been described.

[0059] As shown in a column labeled “Monocular Presentation Side” in FIG. 6A, different alignment calibration cycles 602-1 through 602-6 may be associated with different sides, left (L) or right (R). This will be understood to refer to which side the monocular presentation is performed on. For example, for alignment calibration cycle 602-1 (labeled with monocular presentation side R), the monocular presentation may be presented on theright-side display, leaving the left-side display blank (as the non-presenting side) and detecting the resulting movement of the left eye. Conversely, for alignment calibration cycle 602-3 (labeled with monocular presentation side L) the monocular presentation may be presented on the left-side display, leaving the right-side display blank (as the non-presenting side) and detecting the resulting movement of the right eye. A well-rounded multi-cycle alignment calibration procedure may include a balance of alignment calibration cycles associated with both left and right sides, as is shown for procedure 600. While not explicitly shown in FIG. 6A, it will also be understood that a balance of monocular-to-binocular (illustrated in FIG. 4A) and binocular-to-monocular (illustrated in FIG. 5 A) alignment calibration cycles may be incorporated into the multi-cycle alignment calibration procedure. For instance, display device 200 may be configured to normally perform binocular presentation 210-B by default, but to periodically toggle into and back out of monocular presentation 210-M. Each toggling (into monocular presentation 210-M and back out to binocular presentation 210-B) may be used as an alignment calibration cycle for a multi-cycle alignment calibration procedure such as procedure 600.

[0060] Multi-cycle alignment calibration procedures such as procedure 600 may facilitate several useful technical effects. As one example, multi-cycle alignment calibration procedure 600 may facilitate a display device in initially achieving, then consistently maintaining, an accurate display alignment 604 by way of an optimal calibration parameter 606. Rather than performing a single alignment calibration cycle, display device 200 may perform a series of alignment calibration cycles (e.g., in a burst over the course of a relatively short period of time) to progressively reduce detected misalignment between the displays until the misalignment is effectively eliminated (e.g., until the eye of interest does not move at all in response to a toggle, until the detected eye movement falls beneath a suitable threshold, etc.). Thereafter, occasional alignment calibration cycles (or bursts of several alignment calibration cycles) may then be used to keep the display alignment in check (in case temperature, acceleration, time, or other events arise that cause the displays to again become misaligned).

[0061] As another example technical effect, multi-cycle alignment calibration procedure 600 may be useful to mitigate limitations of relatively imprecise eye tracking. If an eye-tracking mechanism (e.g., such as eye camera 214) happens to not be precise enough to capture eye position modifications with a desirable precision or accuracy, averaging, over time, multiple eye position detections (e.g., associated with multiple alignment calibration cycles 602) may help address this issue.

[0062] As yet another example technical effect, multi-cycle alignment calibration procedure 600 may be useful in making an assessment of what type of eye-position-based calibration techniques described herein may be most effective (or whether this type of technique is likely to be effective at all) for a particular user or situation. For example, eyeposition-based calibration techniques may be less effective for certain users who have an amblyopia condition (i.e., “lazy eye”), a strabismus condition (i.e., “crossed eyes”), or another condition that may tend to affect the alignment of the eyes for reasons unrelated to the toggling of the monocular and binocular presentations of the image content. As such, if a series of alignment calibration cycles fails to reveal eye position modifications that converge to lead to an improved display alignment 604 and / or calibration parameter 606, the display device may determine that this type of calibration approach is not particularly effective for this user and an alternative approach may be employed instead. Similarly, a series of multiple alignment calibration cycles 602 may reveal, for example, that this eye-position-based calibration is effective, but only when performed with respect to one side (e.g., when the monocular presentation side corresponds to the user’s weaker eye, etc.). Accordingly, this information may allow the display device to develop a profile for a particular user and to adapt multi -cycle alignment calibration procedure 600 to that profile (e.g., by using more effective types of alignment calibration cycles while avoiding less effective types of cycles, etc.).

[0063] The various alignment calibration cycles 602 within a multi -cycle alignment calibration procedure 600 may be performed with any suitable timing, with any suitable frequency, and in response to any suitable event or circumstance as may serve a particular implementation. Various factors may influence how often calibration may be performed for a given display device. For example, depending on certain mechanical aspects of the design of a display device and how it is used, certain display devices may need only be calibrated for vertical alignment once per session or less (e.g., once per month, a few times per year, once after manufacturing, etc.). Conversely, it may be helpful for other display devices to be recalibrated significantly more often, such as several times per session. To illustrate certain time-related aspects, FIG. 6B shows an example of when the plurality of alignment calibration cycles 602 of multi-cycle alignment calibration procedure 600 may be performed with respect to a timeline 610.

[0064] As a first timing aspect illustrated in FIG. 6B, timeline 610 is shown to extend from a starting place on the left (where it may be assumed that the display device is first powered on for use by a user) through a dedicated calibration period 612 in which calibrationprocedures may be performed (including, in some examples, at least part of a multi-cycle vertical alignment calibration procedure), and then through an extended reality session 614 (understood as a primary stage in which the device presents extended reality content and generally performs normal operations after having been initially set up and configured).

[0065] As shown in the example of FIG. 6B, various alignment calibration cycles 602 may be distributed in each of the different phases of timeline 610. Specifically, as shown, alignment calibration cycle 602-1 may be performed immediately upon the display device being powered on, alignment calibration cycles 602-2 and 602-3 may be performed during dedicated calibration period 612, and alignment calibration cycles 602-4, 602-5, and 602-6 may be performed during extended reality session 614. As such, given a display device configured to present an extended reality session in which extended reality content is presented on a first display and on a second display (e.g., extended reality session 614), FIG. 6B shows that at least some alignment calibration cycles (e.g., alignment calibration cycles 602-4 through 602-6 in this example) may be performed during the extended reality session (e.g., extended reality session 614) instead of during a dedicated calibration period (e.g., dedicated calibration period 612). As has been described, each of these alignment calibration cycles may include any of the methods or processes described herein. For instance, one of alignment calibration cycles 602-4 through 602-6 could include performing a binocular presentation, determining a first position of the second eye, changing the binocular presentation to a monocular presentation, and determining a second position of the second eye. Then, as part of that alignment calibration cycle (or independently at a later time), the alignment may be determined based on the first and second positions in any of the ways that have been described.

[0066] The timing illustrated for alignment calibration cycles 602-1 through 602-3 may comport with a typical calibration paradigm (often occurring at power up or during a dedicated calibration period such as calibration period 612). The timing of other alignment calibration cycles 602-4 through 602-6, however, may be less typical and highly advantageous in certain implementations. At least one significant technical effect and benefit of technical solutions described herein is that alignment calibration cycles in accordance with principles described herein may be so low impact to the user and the overall system that these alignment calibration cycles 602-4 through 602-6 may be performed right in the middle of extended reality session 614 (e.g., as the user is engaged with an extended reality experience). If performed in certain ways, these alignment calibration cycles may be carried out without the user noticing or perceiving them at all. Even if the user does notice the alignmentcalibration cycles being performed (e.g., when a monocular presentation is performed and one screen is blank), the cycles may still be performed in a manner that is not disruptive or distracting to the user so that good vertical alignment may be maintained without undue interruption to or distraction from the extended reality experience.

[0067] While it might be assumed that a monocular presentation performed as part of alignment calibration cycles described herein could be a possible distraction to a user (particularly when performed during extended reality session 614), there are several reasons that this may not necessarily be the case. A first reason is that, because the brain and eyes tend to be very responsive and to largely function on an instinctive, subconscious plane, the monocular presentation portion of a given alignment calibration cycle need not last long enough to even be particularly noticeable, much less distracting or irritating. For example, the eye may adjust to a toggling between a monocular and binocular view in a few tenths of a second at most, meaning that an alignment calibration cycle may include a monocular presentation phase that lasts far less than one second (e.g., 250 ms, etc.). It is acknowledged that, as the eyes get accustomed to being out of alignment (e.g., after looking at a misaligned binocular presentation for a relatively long period), this response time may take longer as the eyes may not realign themselves as quickly when the monocular presentation is shown. This may serve as yet another motivation for a display device to be configured to achieve a good initial alignment (e.g., at power-on and / or during dedicated calibration period 612) and to update it often enough that the eyes never get too misaligned (since it may take more drastic measures to correct that misalignment).

[0068] A second reason relates to how the brain perceives one display temporarily going blank (as occurs during a brief monocular presentation during alignment calibration cycles described herein). In the augmented reality case (where the semi-transparent displays may go blank while still allowing the passage of light from the environment), the monocular presentation may be perceived as slightly washed out or a bit dimmer than the binocular presentation. This generally would not be noticeable for a brief period such as described above (e.g., a fraction of a second), but, even if it were, one way to compensate for the washed-out picture may be to temporarily increase the brightness on the display that remains on during the monocular presentation.

[0069] In the virtual reality case (where a non-transparent display may go completely dark when not presenting content), the monocular presentation may be perceived as slightly less sharp than the binocular presentation. For example, the one-sided view of the image content may result in the user being less cognizant of fine details in a manner that might beperceived similarly to viewing an image with a low contrast (e.g., a slightly blurry image). Accordingly, one way to mitigate this type of problem (which could be used for either a virtual or augmented reality device) is for the binocular presentation of the image to include blurring the image (e.g., right before the alignment calibration cycle begins and the toggling to the monocular presentation is carried out) and for the monocular presentation of the image to then include unblurring (i.e., sharpening) the image. In other words, by purposely blurring the binocular presentation prior to changing to the monocular presentation, then taking away that intentional blurring for the monocular presentation, the monocular image may be perceived as approximately equal in sharpness compared with the binocular presentation (in spite of the non-presenting screen going blank). Additionally, to make this even lower impact or less noticeable, the blurring of the image may be performed gradually during a portion of the binocular presentation leading up to the changing to the monocular presentation, while the unblurring of the image may be performed immediately to persist throughout the monocular presentation.

[0070] This type of blurring process is illustrated in FIG. 6B in relation to alignment calibration cycle 602-6. As shown, a small graph 616 shows a portion of time along the x- axis (parallel to timeline 610 and lasting for a portion of timeline 610 before and after alignment calibration cycle 602-6). Graph 616 further shows intentionally introduced “Blur” along the y-axis. As shown in graph 616, the blur may be gradually ramped up leading up to the time when alignment calibration cycle 602-6 is performed, and then may very quickly drop during a monocular presentation included as part of alignment calibration cycle 602-6. Assuming that the monocular presentation is of short duration, graph 616 then shows that the blur quickly rises back to a high level (immediately upon changing back to the binocular presentation), followed by a slow ramp-down period to ensure that there is never a particular moment when the blur is likely to be noticed by the user. For example, the total time covered by graph 616 may represent several seconds (e.g., 10 seconds, 20 seconds, a minute, etc.) in a particular implementation. Accordingly, if this blurring technique were to be performed once per hour, once per session, or at another relatively infrequent period, the blurring would likely not be noticed or considered by the user to be a problem.

[0071] Another aspect illustrated in FIG. 6B is a plurality of triggers 618-1 through 618-6 associated with the alignment calibration cycles 602. More particularly, for example, the toggling between the monocular presentation and the binocular presentation for alignment calibration cycle 602-1 may be triggered by trigger 618-1, the toggling between the monocular presentation and the binocular presentation for alignment calibration cycle 602-2may be triggered by trigger 618-2, and so forth. Each of triggers 618-1 through 618-6 may represent any one or more of a variety of possible events or circumstances that trigger an alignment calibration cycle. To give a few examples, trigger 618-1 may represent an initialization of a new session in which the display device presents image content, or, in other words, an event when the display device is first powered on. Trigger 618-2 may represent a completion of a warmup process for the first display and the second display subsequent to this initialization of the new session. For example, it may take a finite period of time for the displays to warm up and become initialized and fully operational, during which time temperatures may change and vertical alignment could be affected. Accordingly, it may be advantageous to update the calibration parameter at this time as well.

[0072] Trigger 618-3 may represent a presentation of predesignated calibration content, a receiving of a calibration request, or the like. As shown, trigger 618-3 occurs during dedicated calibration period 612 and may thus be understood to be associated with a time where the user is not actively engaged in an experience but, rather, is starting up an application, waiting for an experience to load, updating settings or explicitly requesting the device to perform calibration procedures, or the like. In some cases, any time a new program is loaded by the display device, it may be convenient to perform an alignment calibration cycle in connection with a splash screen associated with the new program (e.g., a screen presented as the application is loading or starting up, etc.).

[0073] Triggers 618-4 through 618-6 may each represent a same type of trigger or different types of triggers from a variety of other triggers that will now be described. One example trigger may involve a periodic timer that goes off on a set schedule (e.g., once per hour, etc.) so that the trigger may represent a predesignated amount of time (e.g., one hour, etc.) elapsing since a previous alignment cycle. Another example trigger may be performed in connection with the user being detected to blink (as this may also make it less likely that the user will notice the toggling between binocular and monocular presentations of the image content). For instance, the display device may be configured (e.g., using the same eye camera doing the eye tracking) to detect a blinking of the first eye and the second eye during extended reality session 614. One or more of alignment calibration cycles 602-4 through 602- 6 may then be based on the detected blinking of the first eye and the second eye by performing the toggling (e.g., changing the binocular presentation to the monocular presentation) in response to the detecting of the blinking of the first eye and the second eye. As humans typically blink several times per minute and often closely in succession, blink- triggered alignment calibration cycles may provide an inconspicuous and low-impact way tokeep the vertical alignment calibration up to date.

[0074] Another example trigger that may be relatively inconspicuous for use during extended reality session 614 involves detecting an attribute of extended reality content being presented during the extended reality session and performing the alignment calibration cycle in response to the detecting of this attribute. For example, the attribute may be related to the contrast present in the image or how many sharp edges are present (and likely to be noticed if one screen blinks off temporarily). In other words, the display device may wait until the image content is relatively smooth and devoid of sharp edges (similar to the effect created by the intentional blurring of the image as described above), and may then perform an alignment calibration cycle at that time, when, by the character of the image, a monocular presentation is less likely to be noticed.

[0075] As mentioned above and illustrated in FIG. 2, display devices may also include certain sensors, such as represented by sensors 218 of display device 200. In some implementations, information detected by such sensors may be useful to trigger alignment calibration cycles because the sensor may help the system gather insight into conditions and events that are likely to bring the displays out of alignment (such that triggering an alignment calibration cycle will be helpful to timely bring the displays back into alignment). As one example, a display device may include a temperature sensor configured to detect a temperature change and an alignment calibration cycle may be triggered by (i.e., performed in response to) the temperature change detected by the temperature sensor. As another example, a display device may include an acceleration sensor configured to detect an acceleration event (e.g., the device being bumped, dropped, undergoing vibrations, or otherwise being subject to a mechanical disturbance that might cause the displays to go out of alignment). Here again, the acceleration event detected by the acceleration sensor may be used to trigger an alignment calibration cycle, or, in other words, the alignment calibration cycle may be performed in response to the detected acceleration event.

[0076] As has been mentioned, various methods and processes described herein may be implemented at least in part as instructions embodied in a non-transitory computer- readable medium and executable by one or more computing devices. In general, a processor (e.g., a microprocessor) receives instructions, from a non-transitory computer-readable medium (e.g., a memory, etc.), and executes those instructions, thereby performing one or more operations such as the operations described herein. Such instructions may be stored and / or transmitted using any of a variety of known computer-readable media.

[0077] A computer-readable medium (also referred to as a processor-readablemedium) includes any non-transitory medium that participates in providing data (e.g., instructions) that may be read by a computer (e.g., by a processor of a computer). Such a medium may take many forms, including, but not limited to, non-volatile media, and / or volatile media. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Volatile media may include, for example, dynamic random-access memory (DRAM), which typically constitutes a main memory. Common forms of computer- readable media include, for example, a disk, hard disk, magnetic tape, any other magnetic medium, a compact disc read-only memory (CD-ROM), a digital video disc (DVD), any other optical medium, random access memory (RAM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EPROM), FLASH- EEPROM, any other memory chip or cartridge, or any other tangible medium from which a computer can read.

[0078] FIG. 7 shows an illustrative computing system 700 that may be used to implement various devices and / or systems described herein. For example, computing system 700 may include or implement (or partially implement) display devices such as display device 200 and / or any components thereof or other devices used therewith.

[0079] As shown in FIG. 7, computing system 700 may include a communication interface 702, a processor 704, a storage device 706, and an input / output (I / O) module 708 communicatively connected via a communication infrastructure 710. While an illustrative computing system 700 is shown in FIG. 7, the components illustrated in FIG. 7 are not intended to be limiting. Additional or alternative components may be used in other embodiments. Components of computing system 700 shown in FIG. 7 will now be described in additional detail.

[0080] Communication interface 702 may be configured to communicate with one or more computing devices. Examples of communication interface 702 include, without limitation, a wired network interface (such as a network interface card), a wireless network interface (such as a wireless network interface card), a modem, an audio / video connection, and any other suitable interface.

[0081] Processor 704 generally represents any type or form of processing unit capable of processing data or interpreting, executing, and / or directing execution of one or more of the instructions, processes, and / or operations described herein. Processor 704 may direct execution of operations in accordance with one or more applications 712 or other computerexecutable instructions such as may be stored in storage device 706 or another computer- readable medium.

[0082] Storage device 706 may include one or more data storage media, devices, or configurations and may employ any type, form, and combination of data storage media and / or device. For example, storage device 706 may include, but is not limited to, a hard drive, network drive, flash drive, magnetic disc, optical disc, RAM, dynamic RAM, other non-volatile and / or volatile data storage units, or a combination or sub-combination thereof. Electronic data, including data described herein, may be temporarily and / or permanently stored in storage device 706. For example, data representative of one or more executable applications 712 configured to direct processor 704 to perform any of the operations described herein may be stored within storage device 706. In some examples, data may be arranged in one or more databases residing within storage device 706.

[0083] I / O module 708 may include one or more VO modules configured to receive user input and provide user output. One or more VO modules may be used to receive input for a single virtual experience. I / O module 708 may include any hardware, firmware, software, or combination thereof supportive of input and output capabilities. For example, I / O module 708 may include hardware and / or software for capturing user input, including, but not limited to, a keyboard or keypad, a touchscreen component (e.g., touchscreen display), a receiver (e.g., an RF or infrared receiver), motion sensors, and / or one or more input buttons.

[0084] I / O module 708 may include one or more devices for presenting output to a user, including, but not limited to, a graphics engine, a display (e.g., a display screen), one or more output drivers (e.g., display drivers), one or more audio speakers, and one or more audio drivers. In certain embodiments, I / O module 708 is configured to provide graphical data to a display for presentation to a user. The graphical data may be representative of one or more graphical user interfaces and / or any other graphical content as may serve a particular implementation.

[0085] The following examples describe systems and methods for binocular extended reality display alignment based on eye position in accordance with principles described herein:

[0086] 1. A non-transitory computer-readable medium storing instructions that, when executed by at least one processor, direct a display device with a first display for a first eye and a second display for a second eye to perform a process comprising: changing between a monocular presentation of an image on the first display and a binocular presentation of the image on the first display and the second display; detecting an eye position modification associated with the second eye in response to the changing between the monocular presentation and the binocular presentation; and determining, based on the eye positionmodification associated with the second eye, an alignment of the first display with respect to the second display.

[0087] 2. The non-transitory computer-readable medium of any of the preceding examples, wherein: the changing between the monocular presentation and the binocular presentation includes: performing the monocular presentation of the image, and changing the monocular presentation of the image to the binocular presentation of the image; and the eye position modification arises from the second eye going out of alignment with the first eye in response to the changing to the binocular presentation.

[0088] 3. The non-transitory computer-readable medium of any of the preceding examples, wherein: the changing between the monocular presentation and the binocular presentation includes: performing the binocular presentation of the image, and changing the binocular presentation of the image to the monocular presentation of the image; and the eye position modification arises from the second eye coming into alignment with the first eye in response to the changing to the monocular presentation.

[0089] 4. The non-transitory computer-readable medium of any one of any of the preceding examples, wherein the process further comprises adjusting, based on the alignment of the first display with respect to the second display, a calibration parameter used by the display device to control how image content presented by the first display is vertically aligned with corresponding image content presented by the second display.

[0090] 5. The non-transitory computer-readable medium of any one of any of the preceding examples, wherein the process further comprises: changing between an additional monocular presentation of the image on the second display and an additional binocular presentation of the image on the first display and the second display; and detecting an additional eye position modification associated with the first eye in response to the changing between the additional monocular presentation and the additional binocular presentation; wherein the determining the alignment of the first display with respect to the second display is further based on the additional eye position modification associated with the first eye.

[0091] 6. The non-transitory computer-readable medium of any one of any of the preceding examples, wherein: the changing between the monocular presentation and the binocular presentation and the detecting the eye position modification are performed as part of an alignment calibration cycle; the alignment calibration cycle is included in a plurality of alignment calibration cycles performed by the display device; and the determining the alignment of the first display with respect to the second display is performed based on the plurality of alignment calibration cycles.

[0092] 7. The non-transitory computer-readable medium of any one of any of the preceding examples, wherein the changing between the monocular presentation and the binocular presentation is triggered based on at least one of: an initialization of a new session in which the display device presents image content; a completion of a warmup process for the first display and the second display subsequent to the initialization of the new session; a presentation of predesignated calibration content; receiving a calibration request; or a predesignated amount of time elapsing since a previous alignment calibration cycle.

[0093] 8. A method comprising: performing, by a display device that includes a first display for a first eye and a second display for a second eye, a binocular presentation of an image on the first display and the second display; determining a first position of the second eye during the binocular presentation; changing the binocular presentation to a monocular presentation of the image on the first display; determining a second position of the second eye during the monocular presentation; and determining, based on the first position of the second eye and the second position of the second eye, an alignment of the first display with respect to the second display.

[0094] 9. The method of any of the preceding examples, further comprising adjusting, based on the alignment of the first display with respect to the second display, a calibration parameter used by the display device to control how image content presented by the first display is vertically aligned with corresponding image content presented by the second display.

[0095] 10. The method of any one of any of the preceding examples, further comprising: performing an additional binocular presentation of the image on the first display and the second display; determining a first position of the first eye during the additional binocular presentation; changing the additional binocular presentation to an additional monocular presentation of the image on the second display; and determining a second position of the first eye during the additional monocular presentation; wherein the determining the alignment of the first display with respect to the second display is further based on the first position of the first eye and the second position of the first eye.

[0096] 11. The method of any one of any of the preceding examples, further comprising presenting an extended reality session in which extended reality content is presented on the first display and on the second display; wherein an alignment calibration cycle that includes the performing the binocular presentation, the determining the first position of the second eye, the changing the binocular presentation to the monocularpresentation, and the determining the second position of the second eye is performed during the extended reality session instead of during a dedicated calibration period.

[0097] 12. The method of any of the preceding examples, further comprising detecting a blinking of the first eye and the second eye during the extended reality session; wherein the alignment calibration cycle is based on the blinking of the first eye and the second eye by performing the changing the binocular presentation to the monocular presentation in response to the detecting of the blinking of the first eye and the second eye.

[0098] 13. The method of any of the preceding examples, wherein, for the alignment calibration cycle performed during the extended reality session, the binocular presentation of the image includes blurring the image and the monocular presentation of the image includes unblurring the image.

[0099] 14. The method of any of the preceding examples, wherein: the blurring the image is performed gradually during a portion of the binocular presentation leading up to the changing to the monocular presentation; and the unblurring the image is performed immediately and persists throughout the monocular presentation.

[0100] 15. The method of any of the preceding examples, further comprising detecting an attribute of the extended reality content being presented during the extended reality session; wherein the alignment calibration cycle is performed in response to the detecting the attribute of the extended reality content being presented during the extended reality session.

[0101] 16. A display device comprising: a first display for a first eye; a second display for a second eye; a memory storing instructions; and at least one processor communicatively coupled to the memory and configured to execute the instructions to perform a process comprising: performing a monocular presentation of an image on the first display; determining a first position of the second eye during the monocular presentation; changing the monocular presentation to a binocular presentation of the image on the first display and the second display; determining a second position of the second eye during the binocular presentation; and determining, based on the first position of the second eye and the second position of the second eye, an alignment of the first display with respect to the second display.

[0102] 17. The display device of any of the preceding examples, further comprising a temperature sensor configured to detect a temperature change; wherein the process is performed in response to the temperature change detected by the temperature sensor.

[0103] 18. The display device of any one of any of the preceding examples, further comprising an acceleration sensor configured to detect an acceleration event; wherein the process is performed in response to the acceleration event detected by the acceleration sensor.

[0104] 19. The display device of any one of any of the preceding examples, wherein the display device is implemented as a head-mounted virtual reality presentation device in which the first display and the second display are configured to block a passage of incoming light from an environment.

[0105] 20. The display device of any one of any of the preceding examples, wherein the display device is implemented as a head-mounted augmented reality presentation device in which the first display and the second display are configured to allow a passage of incoming light from an environment.

[0106] Various implementations of the systems and techniques described herein can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0107] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the description and claims. In addition, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.

[0108] Specific structural and functional details disclosed herein are merely representative for purposes of describing example implementations. Example implementations, however, may be embodied in many alternate forms and should not be construed as limited to only the implementations set forth herein.

[0109] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. A first element could be termed a second element, and, similarly, a second element could be termed a first element,without departing from the scope of the implementations of the disclosure. As used herein, the term and / or includes any and all combinations of one or more of the associated listed items.

[0110] The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting of the implementations. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and / or “including,” when used in this specification, specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0111] It will be understood that when an element is referred to as being “coupled,” “connected,” or “responsive” to, or “on,” another element, it can be directly coupled, connected, or responsive to, or on, the other element, or intervening elements may also be present. In contrast, when an element is referred to as being “directly coupled,” “directly connected,” or “directly responsive” to, or “directly on,” another element, there are no intervening elements present. As used herein the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0112] Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature in relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 130 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.

[0113] Unless otherwise defined, the terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which these concepts belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and / or the present specificationand will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0114] Further to the descriptions above, a user may be provided with controls allowing the user to make an election as to both if and when systems, programs, or features described herein may enable collection of user information (e.g., information about a user's social network, social actions, or activities, profession, a user's preferences, or a user's current location), and if the user is sent content or communications from a server. In addition, certain data may be treated in one or more ways before it is stored or used, so that personally identifiable information is removed. For example, a user's identity may be treated so that no personally identifiable information can be determined for the user, or a user's geographic location may be generalized, or location information may be obtained (such as to a city, zip code, or state level), so that a particular location of a user cannot be determined. Thus, the user may have control over what information is collected about the user, how that information is used, and what information is provided to the user.

[0115] While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover such modifications and changes as fall within the scope of the implementations. It will be understood that they have been presented by way of example only, not limitation, and various changes in form and details may be made. Any portion of the apparatus and / or methods described herein may be combined in any combination, except mutually exclusive combinations. The implementations described herein can include various combinations and / or sub-combinations of the functions, components, and / or features of the different implementations described. As such, the scope of the present disclosure is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features or example implementations described herein irrespective of whether or not that particular combination has been specifically enumerated in the accompanying claims at this time.

Claims

WHAT IS CLAIMED IS:

1. A non-transitory computer-readable medium storing instructions that, when executed by at least one processor, direct a display device with a first display for a first eye and a second display for a second eye to perform a process comprising: changing between a monocular presentation of an image on the first display and a binocular presentation of the image on the first display and the second display; detecting an eye position modification associated with the second eye in response to the changing between the monocular presentation and the binocular presentation; and determining, based on the eye position modification associated with the second eye, an alignment of the first display with respect to the second display.

2. The non-transitory computer-readable medium of claim 1, wherein: the changing between the monocular presentation and the binocular presentation includes: performing the monocular presentation of the image, and changing the monocular presentation of the image to the binocular presentation of the image; and the eye position modification arises from the second eye going out of alignment with the first eye in response to the changing to the binocular presentation.

3. The non-transitory computer-readable medium of claim 1, wherein: the changing between the monocular presentation and the binocular presentation includes: performing the binocular presentation of the image, and changing the binocular presentation of the image to the monocular presentation of the image; and the eye position modification arises from the second eye coming into alignment with the first eye in response to the changing to the monocular presentation.

4. The non-transitory computer-readable medium of any one of claims 1-3, wherein the process further comprises adjusting, based on the alignment of the first display with respect to the second display, a calibration parameter used by the display device tocontrol how image content presented by the first display is vertically aligned with corresponding image content presented by the second display.

5. The non-transitory computer-readable medium of any one of claims 1-4, wherein the process further comprises: changing between an additional monocular presentation of the image on the second display and an additional binocular presentation of the image on the first display and the second display; and detecting an additional eye position modification associated with the first eye in response to the changing between the additional monocular presentation and the additional binocular presentation; wherein the determining the alignment of the first display with respect to the second display is further based on the additional eye position modification associated with the first eye.

6. The non-transitory computer-readable medium of any one of claims 1-5, wherein: the changing between the monocular presentation and the binocular presentation and the detecting the eye position modification are performed as part of an alignment calibration cycle; the alignment calibration cycle is included in a plurality of alignment calibration cycles performed by the display device; and the determining the alignment of the first display with respect to the second display is performed based on the plurality of alignment calibration cycles.

7. The non-transitory computer-readable medium of any one of claims 1-6, wherein the changing between the monocular presentation and the binocular presentation is triggered based on at least one of: an initialization of a new session in which the display device presents image content; a completion of a warmup process for the first display and the second display subsequent to the initialization of the new session; a presentation of predesignated calibration content; receiving a calibration request; or a predesignated amount of time elapsing since a previous alignment calibration cycle.

8. A method compri sing : performing, by a display device that includes a first display for a first eye and a second display for a second eye, a binocular presentation of an image on the first display and the second display; determining a first position of the second eye during the binocular presentation; changing the binocular presentation to a monocular presentation of the image on the first display; determining a second position of the second eye during the monocular presentation; and determining, based on the first position of the second eye and the second position of the second eye, an alignment of the first display with respect to the second display.

9. The method of claim 8, further comprising adjusting, based on the alignment of the first display with respect to the second display, a calibration parameter used by the display device to control how image content presented by the first display is vertically aligned with corresponding image content presented by the second display.

10. The method of any one of claims 8-9, further comprising: performing an additional binocular presentation of the image on the first display and the second display; determining a first position of the first eye during the additional binocular presentation; changing the additional binocular presentation to an additional monocular presentation of the image on the second display; and determining a second position of the first eye during the additional monocular presentation; wherein the determining the alignment of the first display with respect to the second display is further based on the first position of the first eye and the second position of the first eye.

11. The method of any one of claims 8-10, further comprising presenting an extended reality session in which extended reality content is presented on the first display and on the second display;wherein an alignment calibration cycle that includes the performing the binocular presentation, the determining the first position of the second eye, the changing the binocular presentation to the monocular presentation, and the determining the second position of the second eye is performed during the extended reality session instead of during a dedicated calibration period.

12. The method of claim 11, further comprising detecting a blinking of the first eye and the second eye during the extended reality session; wherein the alignment calibration cycle is based on the blinking of the first eye and the second eye by performing the changing the binocular presentation to the monocular presentation in response to the detecting of the blinking of the first eye and the second eye.

13. The method of claim 11 or 12, wherein, for the alignment calibration cycle performed during the extended reality session, the binocular presentation of the image includes blurring the image and the monocular presentation of the image includes unblurring the image.

14. The method of claim 13, wherein: the blurring the image is performed gradually during a portion of the binocular presentation leading up to the changing to the monocular presentation; and the unblurring the image is performed immediately and persists throughout the monocular presentation.

15. The method of any one of claims 11, 13, or 14, further comprising detecting an attribute of the extended reality content being presented during the extended reality session; wherein the alignment calibration cycle is performed in response to the detecting the attribute of the extended reality content being presented during the extended reality session.

16. A display device comprising: a first display for a first eye; a second display for a second eye; a memory storing instructions; and at least one processor communicatively coupled to the memory and configured to execute the instructions to perform a process comprising:performing a monocular presentation of an image on the first display; determining a first position of the second eye during the monocular presentation; changing the monocular presentation to a binocular presentation of the image on the first display and the second display; determining a second position of the second eye during the binocular presentation; and determining, based on the first position of the second eye and the second position of the second eye, an alignment of the first display with respect to the second display.

17. The display device of claim 16, further comprising a temperature sensor configured to detect a temperature change; wherein the process is performed in response to the temperature change detected by the temperature sensor.

18. The display device of any one of claims 16-17, further comprising an acceleration sensor configured to detect an acceleration event; wherein the process is performed in response to the acceleration event detected by the acceleration sensor.

19. The display device of any one of claims 16-18, wherein the display device is implemented as a head-mounted virtual reality presentation device in which the first display and the second display are configured to block a passage of incoming light from an environment.

20. The display device of any one of claims 16-18, wherein the display device is implemented as a head-mounted augmented reality presentation device in which the first display and the second display are configured to allow a passage of incoming light from an environment.

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