Patent Application
20140375540
Mixed reality is a technology that allows holographic, or virtual, imagery to be mixed with a real world physical environment. A see-through, head mounted, mixed reality display device may be worn by a user to view the mixed imagery of real objects and virtual objects displayed in the user's field of view. In order to facilitate the illusion of three-dimensional depth, images of virtual objects are displayed independently to the left and right eyes by the head mounted display device with a small binocular disparity between the images. This binocular disparity is interpreted by the brain as indicative of a depth of the virtual object in the mixed reality environment.
It is desirable to precisely control both the position of a head mounted display device on a user's head and the binocular disparity of displayed images. Even small deviations in the position or binocular disparity can create a blurred image, discomfort and loss of the three-dimensional effect.
Embodiments of the present technology relate to a system and method for sensing a position of a head mounted display device respect to a wearer's eyes, and to provide feedback for adjusting the position of the head mounted display device so as to be optimally centered with respect to the wearer's eyes. In embodiments, a head mounted display device includes display units and an eye position and tracking assembly. The display units display images to optics over the left and right eyes with the appropriate ocular disparity to create the illusion of virtual objects at a given distance away from the user. The eye position and tracking assembly may include one or more light sources and one or more sensors which operate identify a position of a user's eyes with respect to the eye position and tracking assembly. The geometry of the eye position and tracking assembly relative to the display units is known so that the optimal, centered position of the display units may be determined for each eye.
When misalignment of the display units relative to a user's eyes is detected, the head mounted display device may provide visual and/or auditory feedback to the user. This feedback may instruct the user on how to adjust the head mounted display to optimally align and fit the head mounted display device over the user's eyes. In addition to providing feedback on adjustment of a position of the head mounted display, the current technology may provide feedback on adjusting the inter-pupillary distance (IPD) in the head mounted display device for embodiments where the head mounted display device has an adjustable IPD.
In an alternative embodiment, adjustment of the head mounted display device position and/or IPD may occur automatically. In one such automatic example, upon detection of misalignment, the misalignment may be corrected using software to adjust how and where virtual objects are displayed by one or both display units. In another automatic example, motors may be provided on the head mounted display device to adjust certain positions and/or IPD of the head mounted display device.
In an example, the present technology relates to a head mounted display device, comprising: a display unit including optical elements; a position and tracking assembly for sensing a position and angular orientation of the position and tracking assembly with respect to eyes of a wearer; a processor coupled to the display unit and position and tracking assembly for determining a position and angular orientation of the optical elements relative to the eyes; and a feedback routine executed by the processor for providing feedback to the wearer to adjust at least one of the position and orientation of the head mounted display device relative to the eyes based on the determination of misalignment from the processor.
In a further example, the present technology relates to a head mounted display device for providing a mixed reality experience in a space having an x-axis, a y-axis perpendicular to the x-axis and a z-axis perpendicular to the x and y axes, the head mounted display comprising: a display unit including optical elements for displaying virtual images to eyes of a wearer; a position and tracking assembly for sensing a position with respect to the x, y and z axes of the position and tracking assembly to the eyes, and an angular rotation with respect to rotation about the x, y and z axes an x-axis of the position and tracking assembly to the eyes; a processor coupled to the display unit and position and tracking assembly for determining a position and angular orientation of the optical elements relative to the eyes; and a feedback routine implemented by the processor for providing feedback to the user to adjust at least one of the position and orientation of the head mounted display relative to the eyes based on the determination from the processor.
In another example, the present technology relates to a method for indicating misalignment of one or more optical elements of a head mounted display device with eyes of a wearer, the method comprising: (a) determining misalignment of the optical elements to the eyes of the wearer, said misalignment determined by a processing device and an eye position and tracking assembly; and (b) generating feedback providing information to the wearer regarding how to adjust one or more of the optical elements, the feedback displayed as one or more virtual images displayed to the optical elements.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Embodiments of the present technology will now be described with reference to
Head mounted display device 2, which in one embodiment is in the shape of glasses, is worn on the head of a user so that the user can see through a display and thereby have an actual direct view of the space in front of the user. The use of the term “actual direct view” refers to the ability to see the real world objects directly with the human eye, rather than seeing created image representations of the objects. For example, looking through glass at a room allows a user to have an actual direct view of the room, while viewing a video of a room on a television is not an actual direct view of the room. More details of the head mounted display device 2 are provided below.
The processing unit 4 may include much of the computing power used to operate head mounted display device 2. In embodiments, the processing unit 4 communicates wirelessly (e.g., WiFi, Bluetooth, infra-red, or other wireless communication means) to one or more hub computing systems 12. As explained hereinafter, hub computing system 12 may be provided remotely from the processing unit 4, so that the hub computing system 12 and processing unit 4 communicate via a wireless network such as a LAN or WAN. In further embodiments, the hub computing system 12 may be omitted to provide a mobile mixed reality experience using the head mounted display devices 2 and processing units 4.
The head mounted display device 2, either by itself or in conjunction with the hub computing system 12, may provide a mixed reality experience where one or more virtual images, such as virtual object 21 in
A portion of the frame of head mounted display device 2 will surround a display (that includes one or more lenses). In order to show the components of head mounted display device 2, a portion of the frame surrounding the display is not depicted. The display includes a light-guide optical element 115, opacity filter 114, see-through lens 116 and see-through lens 118. In one embodiment, opacity filter 114 is behind and aligned with see-through lens 116, light-guide optical element 115 is behind and aligned with opacity filter 114, and see-through lens 118 is behind and aligned with light-guide optical element 115. See-through lenses 116 and 118 are standard lenses used in eye glasses and can be made to any prescription (including no prescription). Light-guide optical element 115 channels artificial light to the eye. More details of opacity filter 114 and light-guide optical element 115 are provided in U.S. Published Patent Application No. 2012/0127284, entitled, “Head-Mounted Display Device Which Provides Surround Video,” which application published on May 24, 2012.
Control circuits 136 provide various electronics that support the other components of head mounted display device 2. More details of control circuits 136 are provided below with respect to
Microdisplay 120 projects an image through lens 122. There are different image generation technologies that can be used to implement microdisplay 120. For example, microdisplay 120 can be implemented in using a transmissive projection technology where the light source is modulated by optically active material, backlit with white light. These technologies are usually implemented using LCD type displays with powerful backlights and high optical energy densities. Microdisplay 120 can also be implemented using a reflective technology for which external light is reflected and modulated by an optically active material. The illumination is forward lit by either a white source or RGB source, depending on the technology. Digital light processing (DLP), liquid crystal on silicon (LCOS) and Mirasol® display technology from Qualcomm, Inc. are all examples of reflective technologies which are efficient as most energy is reflected away from the modulated structure and may be used in the present system. Additionally, microdisplay 120 can be implemented using an emissive technology where light is generated by the display. For example, a PicoP™ display engine from Microvision, Inc. emits a laser signal with a micro mirror steering either onto a tiny screen that acts as a transmissive element or beamed directly into the eye (e.g., laser).
Light-guide optical element 115 transmits light from microdisplay 120 to the eye 140 of the user wearing head mounted display device 2. Light-guide optical element 115 also allows light from in front of the head mounted display device 2 to be transmitted through light-guide optical element 115 to eye 140, as depicted by arrow 142, thereby allowing the user to have an actual direct view of the space in front of head mounted display device 2 in addition to receiving a virtual image from microdisplay 120. Thus, the walls of light-guide optical element 115 are see-through. Light-guide optical element 115 includes a first reflecting surface 124 (e.g., a mirror or other surface). Light from microdisplay 120 passes through lens 122 and becomes incident on reflecting surface 124. The reflecting surface 124 reflects the incident light from the microdisplay 120 such that light is trapped inside a planar substrate comprising light-guide optical element 115 by internal reflection. After several reflections off the surfaces of the substrate, the trapped light waves reach an array of selectively reflecting surfaces 126. Note that one of the five surfaces is labeled 126 to prevent over-crowding of the drawing. Reflecting surfaces 126 couple the light waves incident upon those reflecting surfaces out of the substrate into the eye 140 of the user. More details of a light-guide optical element can be found in United States Patent Publication No. 2008/0285140, entitled “Substrate-Guided Optical Devices,” published on Nov. 20, 2008.
In accordance with aspects of the present technology, the head mounted display device 2 may also include a system for locating and tracking the position of the user's eyes. This system includes an eye position and tracking assembly 134 (
The position of a user's eyes, and the pupils within the eyes, can be identified by known imaging techniques which detect the reflection of the cornea. For example, see U.S. Pat. No. 7,401,920, entitled “Head Mounted Eye Tracking and Display System”, issued Jul. 22, 2008. Such a technique can locate a position of the center of the eye relative to the tracking sensor 134B. In embodiments, there may be a separate eye position and tracking assembly 134 for each of the left and right eyes so that a user's IPD may be determined. In further embodiments, there may be a single eye position and tracking assembly 134 identifying the center of either the left or right eye.
In one embodiment, the system will use four IR LEDs and four IR photo detectors in rectangular arrangement so that there is one IR LED and IR photo detector at each corner of the lens of head mounted display device 2. Light from the LEDs reflect off the eyes. The amount of infrared light detected at each of the four IR photo detectors determines a position of the eye relative to the sensor 134B, as well as the pupil direction. In particular, the amount of white versus black in the eye will determine the amount of light reflected off the eye for that particular photo detector. Thus, the photo detector will have a measure of the amount of white or black in the eye. From the four samples, the system can determine the direction of the eye.
Another alternative is to use four infrared LEDs as discussed above, but one infrared CCD on the side of the lens of head mounted display device 2. The CCD will use a small mirror and/or lens (fish eye) such that the CCD can image up to 75% of the visible eye from the glasses frame. The CCD will then sense an image and use computer vision to find the image, much like as discussed above. Thus, although
Another embodiment for tracking the direction of the eyes is based on charge tracking. This concept is based on the observation that a retina carries a measurable positive charge and the cornea has a negative charge. Sensors are mounted by the user's ears (near earphones 130) to detect the electrical potential while the eyes move around and effectively read out what the eyes are doing in real time. This provides both the position of a user's eyes relative to the head mounted display device, and the position of the user's pupils. Other embodiments for determining the position of the user's eyes relative to the head mounted display device can also be used.
Using any of the above-described embodiments, the eye position and tracking system 134 is able to determine a position of the left and right eyes relative to a position of the eye position and tracking system 134. Using the known position and geometry of the system 134 relative to the optical elements 115, the position of the optical elements 115 relative to the left and right eyes is also known. This position includes a relative position of the eyes and the optical elements along the x-axis (e.g., horizontal positioning). This position includes a relative position of the eyes and optical elements along the y-axis (e.g., vertical positioning). And this position includes a relative position of the eyes and optical elements along the z-axis (e.g., a distance between the eyes and optical elements).
In addition to position, it is also advantageous to determine the angular orientation (pitch, yaw and roll) of the optical elements 115 relative to the left and right eyes. For this purpose, the eye position and tracking assembly 134 also determines a center of each eye, and an eye vector straight out from the center of the eye.
The eye center may be determined a number of ways. Where sensor 134B captures an image of the eye (either as a color image and/or as a depth image), the image may be analyzed to determine the eye center. For example, an image sensor may examine the corneal surface, and from that, determine major axes and the corneal center. In a further embodiment, the image sensor may examine other features of the eyes, including pupil, sclera (white portions of the eye) and/or eye lashes. Other features of the face such as brow, nose and nose bridge may further be imaged and used to determine the centers of the left and right eyes.
Examples including IR transmitters/receivers may also determine the center of the eye and an eye vector straight out from the center. For example, where there are multiple IR transmitters/receivers, such as four, each of these components may measure the amount of sclera in the eye they detect. These four independent values may be determined and compared. When each measures the same amount of sclera in the eye, the eye is centered (looking straight forward), and the eye vector may be taken perpendicularly straight out from the pupil. This position may either be found when each IR transmitter/receiver measure the same amount of sclera in the eye, or it may be extrapolated from a measurement where the four transmitter/receiver pairs measure different values of sclera in the eye.
As noted above, each eye may its own position and tracking assembly 134, and a separate eye vector may be determined for each. Alternatively, it may be assumed that the eyes are symmetric and move together, and a single eye vector may be determined and used for both eyes.
Using that information and possibly information from hub computing system 12, processing unit 4 may determine where and when to provide a virtual image to the user and send instructions accordingly to the head mounted display device of
Some of the components of
In one embodiment, all of the components of control circuit 200 are in communication with each other via dedicated lines or one or more buses. In another embodiment, each of the components of control circuit 200 is in communication with processor 210. Camera interface 216 provides an interface to the two room-facing cameras 112 and stores images received from the room-facing cameras in camera buffer 218. Display driver 220 will drive microdisplay 120. Display formatter 222 provides information, about the virtual image being displayed on microdisplay 120, to opacity control circuit 224, which controls opacity filter 114. Timing generator 226 is used to provide timing data for the system. Display out interface 228 is a buffer for providing images from room-facing cameras 112 to the processing unit 4. Display in interface 230 is a buffer for receiving images such as a virtual image to be displayed on microdisplay 120. Display out interface 228 and display in interface 230 communicate with band interface 232 which is an interface to processing unit 4.
Power management circuit 202 includes voltage regulator 234, eye tracking illumination driver 236, audio DAC and amplifier 238, microphone preamplifier and audio ADC 240, temperature sensor interface 242 and clock generator 244. Voltage regulator 234 receives power from processing unit 4 via band interface 232 and provides that power to the other components of head mounted display device 2. Eye tracking illumination driver 236 provides the IR light source for eye tracking illumination 134A, as described above. Audio DAC and amplifier 238 output audio information to the earphones 130. Microphone preamplifier and audio ADC 240 provides an interface for microphone 110. Temperature sensor interface 242 is an interface for temperature sensor 138. Power management circuit 202 also provides power and receives data back from three axis magnetometer 132A, three axis gyro 132B and three axis accelerometer 132C.
Power management circuit 306 includes clock generator 360, analog to digital converter 362, battery charger 364, voltage regulator 366, head mounted display power source 376, and temperature sensor interface 372 in communication with temperature sensor 374 (possibly located on the wrist band of processing unit 4). Analog to digital converter 362 is used to monitor the battery voltage, the temperature sensor and control the battery charging function. Voltage regulator 366 is in communication with battery 368 for supplying power to the system. Battery charger 364 is used to charge battery 368 (via voltage regulator 366) upon receiving power from charging jack 370. HMD power source 376 provides power to the head mounted display device 2.
Using components such as the eye position and tracking assembly 134, the processing unit 4 is able to determine the centers of the user's eyes, and whether the optical elements 115 are properly centered in the optimal position over the user's eyes. Referring now to the flowchart of
Using this information, the processing unit 4 is able to determine linear and angular offsets between respective optical elements 115 and the user's left and right eyes in step 608. These offsets may be determined in six degrees of freedom. As shown in
Similarly, the processing unit 4 is able to determine a pitch, yaw and roll of the optical elements 115 relative to the user's eyes. For example, using the eye vector as determined above, the processing unit 4 is able to determine the pitch of the optical elements 115, i.e., rotation about the x axis, and the yaw of the optical elements 115, i.e., rotation about the y axis. As roll of an optical element is about the eye vector from the left or right eye, roll may be determined using information in addition to the eye vector. For example, roll may be determined by examining the eye vectors from both the left and right eyes.
It is understood that additional imaging devices may be provided as part of the head mounted display device 2 to provide additional information regarding pitch and yaw and roll to enable precise determination of the positioning of the optical elements 115 relative to the user's eyes, and a particular any offset in six degrees of freedom. As each eye can have its own dedicated eye position and tracking assembly 134, offset of the optical elements 115 for both the left and right eyes can be determined in twelve degrees of freedom.
In addition to linear offset along the x, y and/or z axes, and rotational offset around the x, y and/or z axes, step 608 may further include the step of determining any offset in binocular disparity requiring an adjustment in the IPD of the respective optical elements 115. In particular, some head mounted display devices may have a variable IPD, which is adjustable depending on the distance between a user's pupils. In such instances, as shown in
Once all offsets have been determined, the head mounted display device 2 may further provide feedback to user in step 610 regarding precise adjustments that can be made to optimally center the head mounted display device 2 with respect to the user's eyes. In one example, the processing unit 4 may include a software feedback routine for providing visible and/or auditory feedback to the user via head mounted display device 2 regarding any offset determined by the processing unit 4. The feedback routine and provide feedback in a wide variety of ways via the head mounted display device 2. For example,
The user may manually adjust the head mounted display device 2 to move it horizontally and vertically until the actual alignment crosshairs 652 alignment with reference alignment crosshairs 650. At this point, the head mounted display device will be correctly positioned on the user's head. As a user moves the head mounted display device 2, the actual alignment crosshairs 62 will move to show the user's progress. Thus, the virtual crosshairs 650, 652 provide a closed loop feedback system indicating to the user the adjustment of the head mounted display device 2.
Instead of or in addition to graphical indications of alignment, visual instructions may be provided to the user and how to adjust the head mounted display device 2. Such an example is shown in
As indicated above, in some examples, the head mounted display device 2 may have an adjustable mechanism to accommodate different IPD settings. The feedback routine of the processing unit 4 may further provide visual and/or auditory feedback instructing the user and how to adjust the distance between optical element 115 to correctly provide the IPD setting. For example,
In each of the feedback scheme shown in
In embodiments, a user may manually adjust the head mounted display device 2 upon receipt of the feedback in a closed loop feedback system. In a further embodiment, adjustment of the head mounted display device 2 may occur automatically as indicated in step 614 in
Where for example the adjusted to be made is to the distance between optical elements 115 to adjust for optimal IPD, this adjustment to be made using software instead of physically adjusting the distance between the optical elements 115. In particular, the display from micro display 120 to the respective optical elements 115 may be adjusted by the processing unit 4 to automatically adjust optimal IPD using software commands from the processing unit 4. Similar software adjustments may be used to automatically compensate for linear and/or angular offsets with respect to the x, y and z axes.
Alternatively, closed loop servo actuators may be provided on the head mounted display device 2 for adjusting optical elements 115 in response to feedback from the processing unit 4. For example, where there is adjustment mechanism for IPD adjustment, adjustment mechanism may be driven by a servo motor which physically adjusts the distance between optical element 115 over a predefined range in response to feedback regarding the binocular disparity offset. It is conceivable that other servomotors be provided to adjust the head mounted display device 2 to automatically compensate for linear and/or angular offsets with respect to the x, y and z axes.
A graphics processing unit (GPU) 508 and a video encoder/video codec (coder/decoder) 514 form a video processing pipeline for high speed and high resolution graphics processing. Data is carried from the graphics processing unit 508 to the video encoder/video codec 514 via a bus. The video processing pipeline outputs data to an A/V (audio/video) port 540 for transmission to a television or other display. A memory controller 510 is connected to the GPU 508 to facilitate processor access to various types of memory 512, such as, but not limited to, a RAM (Random Access Memory).
The computing device 500 includes an I/O controller 520, a system management controller 522, an audio processing unit 523, a network interface 524, a first USB host controller 526, a second USB controller 528 and a front panel I/O subassembly 530 that are preferably implemented on a module 518. The USB controllers 526 and 528 serve as hosts for peripheral controllers 542(1)-542(2), a wireless adapter 548, and an external memory device 546 (e.g., flash memory, external CD/DVD ROM drive, removable media, etc.). The network interface 524 and/or wireless adapter 548 provide access to a network (e.g., the Internet, home network, etc.) and may be any of a wide variety of various wired or wireless adapter components including an Ethernet card, a modem, a Bluetooth module, a cable modem, and the like.
System memory 543 is provided to store application data that is loaded during the boot process. A media drive 544 is provided and may comprise a DVD/CD drive, Blu-Ray drive, hard disk drive, or other removable media drive, etc. The media drive 544 may be internal or external to the computing device 500. Application data may be accessed via the media drive 544 for execution, playback, etc. by the computing device 500. The media drive 544 is connected to the I/O controller 520 via a bus, such as a Serial ATA bus or other high speed connection (e.g., IEEE 1394).
The system management controller 522 provides a variety of service functions related to assuring availability of the computing device 500. The audio processing unit 523 and an audio codec 532 form a corresponding audio processing pipeline with high fidelity and stereo processing. Audio data is carried between the audio processing unit 523 and the audio codec 532 via a communication link. The audio processing pipeline outputs data to the A/V port 540 for reproduction by an external audio user or device having audio capabilities.
The front panel I/O subassembly 530 supports the functionality of the power button 550 and the eject button 552, as well as any LEDs (light emitting diodes) or other indicators exposed on the outer surface of the computing device 500. A system power supply module 536 provides power to the components of the computing device 500. A fan 538 cools the circuitry within the computing device 500.
The CPU 501, GPU 508, memory controller 510, and various other components within the computing device 500 are interconnected via one or more buses, including serial and parallel buses, a memory bus, a peripheral bus, and a processor or local bus using any of a variety of bus architectures. By way of example, such architectures can include a Peripheral Component Interconnects (PCI) bus, PCI-Express bus, etc.
When the computing device 500 is powered on, application data may be loaded from the system memory 543 into memory 512 and/or caches 502, 504 and executed on the CPU 501. The application may present a graphical user interface that provides a consistent user experience when navigating to different media types available on the computing device 500. In operation, applications and/or other media contained within the media drive 544 may be launched or played from the media drive 544 to provide additional functionalities to the computing device 500.
The computing device 500 may be operated as a standalone system by simply connecting the system to a television or other display. In this standalone mode, the computing device 500 allows one or more users to interact with the system, watch movies, or listen to music. However, with the integration of broadband connectivity made available through the network interface 524 or the wireless adapter 548, the computing device 500 may further be operated as a participant in a larger network community. Additionally, computing device 500 can communicate with processing unit 4 via wireless adaptor 548.
Optional input devices (e.g., controllers 542(1) and 542(2)) are shared by gaming applications and system applications. The input devices are not reserved resources, but are to be switched between system applications and the gaming application such that each will have a focus of the device. The application manager preferably controls the switching of input stream, without knowing the gaming application's knowledge and a driver maintains state information regarding focus switches. Capture device 20 may define additional input devices for the device 500 via USB controller 526 or other interface. In other embodiments, hub computing system 12 can be implemented using other hardware architectures. No one hardware architecture is required.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. It is intended that the scope of the invention be defined by the claims appended hereto.
