This disclosure relates generally to displays, and in particular but not exclusively, relates to eye tracking.
Virtual reality (VR) is a computer-simulated experience that reproduces lifelike immersion. Current VR experiences generally utilize a projected environment in front of the user's face. In some situations the VR experience may also include sonic immersion as well, such as through the use of headphones. The user may be able to look around or move in the simulated environment using a user interface. Vibrating the user interface or providing resistance to the controls may sometimes supply interaction with the environment.
Generally the performance requirements for the VR headset systems are more stringent than the display systems of cellphones, tablets, and televisions. This is in part due to the eye of the user being very close to the display screen during operation, and the frequency that the human eye can process images.
Non-limiting and non-exhaustive examples of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.
Examples of an apparatus, system, and method relating to a display device are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of the examples. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.
Reference throughout this specification to “one example” or “one embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present invention. Thus, the appearances of the phrases “in one example” or “in one embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more examples.
The performance requirements for virtual reality (VR) or augmented reality (AR) headset systems are more stringent than the display systems of cellphones, tablets, and televisions. One critical performance requirement is high resolution. Generally, a pixel density of ˜60 pixels/degree at the fovea is usually referred to as eye limiting resolution. For VR, each high resolution stereographic image runs twice, once per eye, to occupy most of the user's peripheral vision (e.g., vertical vision is ˜180 degrees, and horizontal vision is ˜135 degrees). In order to render high resolution images, a large set of image data may need to be provided from the processor/controller of the VR system to the VR display.
Another critical performance parameter is short latency. Long latency can cause the user to experience virtual reality sickness. In some VR embodiments, the ideal latency would be 7-15 milliseconds. A major component of this latency is the refresh rate of the display, which has been driven up to 120 Hz or even 240 Hz. The graphics processing unit (GPU) also needs to be more powerful to render frames more frequently. In some VR examples, in order to feel seamless, the frame rate needs to be at least 90 fps.
Accordingly, due to the large data set required, it is challenging for current graphic cards and displays to achieve at least 90 fps (frames per second), 120 Hz or greater refresh rate (for stereo 3D with over-1080p resolution), and wide field of view all at the same time. This disclosure describes a head-mounted device/system (and operational methods) to reduce the required bandwidth and achieve better latency without perceptible lose in image quality to the user.
The following description discusses the examples disclosed above, as well as other examples as they relate to the figures.
As shown, housing 121 is shaped to removably mount on a head of a user through use of strap 123 (which may be elastic, Velcro, plastic, or the like and wrap around the head of the user). Housing 121 may be formed from metal, plastic, glass, or the like. Display 101 is disposed in housing 121 and positioned to show images to a user when housing 121 is mounted on the head of the user. It is appreciated that display 101 may be built into housing 121, or may be able to removably attach to housing 121. For example, display 101 may be part of a smart phone that may be inserted into housing 121. In another or the same example, display 101 may include an light emitting diode display (LED), organic LED display, liquid crystal display, holographic display, or the like. In some examples, display 101 may be partially transparent (or not obscure all of the user's vision) in order to provide an augmented reality (AR) environment. It is appreciated that display 101 may be constructed so it is only positioned in front of a single eye of the user.
In the depicted example, controller 131 is coupled to display 101 and a sensor (see e.g.,
In some examples, there may be only one sensor 151 or there may be a plurality of sensors 151, and sensors 151 are disposed in various places around lens optics 155 to monitor the eyes of the user. It is appreciated that sensors 151 may be positioned to image the eye through lens optics 155 or may image the eye without intermediary optics. It is also appreciated that the system may be calibrated in order to relate eye position to where the user is looking at on display 101. Calibration may occur at the factory or after purchase by the user.
It is appreciated that second region 263 is concentric with first region 261, and the second resolution image data decreases in resolution gradually from first region 261 to third region 265. Similarly, the resolution of third region 265 may gradually decrease towards fourth region 269. The second resolution image data and third resolution image data may decrease in resolution from the first region to the fourth region at a linear or non-linear rate.
In the same or a different example, the first resolution image data has a first frame rate, the second resolution image data has a second frame rate, the third resolution image data has a third frame rate, and the fourth resolution image has a fourth frame rate. And the first frame rate is greater than the second frame rate, the second frame rate is greater than the third frame rate, and the third frame rate is greater than the fourth frame rate. Reducing the frame rate in the peripheral region of the user's vision may further conserve bandwidth since less data needs to be transferred to display 201. It is appreciated that like resolution, the second frame rate may decrease gradually from first region 261 to the third region 265, and the third frame rate may decrease gradually from the second region 263 to fourth region 269.
In another or the same example, the first resolution image data may have a first refresh rate, the second resolution image data may have a second refresh rate, the third resolution image data may have a third refresh rate, and the fourth resolution image data my have a fourth refresh rate. And the first refresh rate is greater than the second refresh rate, the second refresh rate is greater than the third refresh rate, and the third refresh rate is greater than the fourth refresh rate. It is appreciated that the second refresh rate may decrease gradually from first region 261 to third region 265, and the third refresh rate may decrease gradually from second region 263 to fourth region 269. Like reducing the frame rate and resolution, reducing the refresh rate may similarly reduce the amount of data required in order to operate display 201.
Block 301 shows receiving, with a controller (e.g., controller 131 of
Block 303 depicts determining, with the controller, the gaze location of the eye. In some examples this may include correlating the position of the user's iris or pupil with where the user is looking on the screen. This may be achieved by calibrating the system in a factory, or having the user calibrate the head-mounted display before they use it. Additionally, head-mounted display may iteratively learn where the user is looking using a machine learning algorithm (e.g., neural net) or the like.
Block 305 illustrates outputting images (e.g., video, video game graphics or the like) from the controller (which may be disposed in a PC or gaming system) to a display including first resolution image data for a first region in the images. It is appreciated that the first region includes the gaze location of the eye on the display (e.g., the place on the display where the eye is looking).
Block 307 shows outputting to the display, second resolution image data for a second region in the images. The first resolution image data has a higher resolution (e.g., 1080 p) than the second resolution image data (e.g., 720 p or less). In some examples, the second region is concentric with the first region. In some examples the regions may not have the same center and may have a predetermined amount of offset from one another.
Block 309 depicts outputting, to the display, third resolution image data for a third region in the images. In the depicted example, the second region is disposed between the first region and the third region, and the second resolution image data has a higher resolution than the third resolution image data. The second resolution image data may decrease in resolution gradually from the first region to the third region (e.g., linearly, exponentially, degreasing at a decreasing rate, decreasing at an increasing rate, or the like).
In some examples, it is appreciated that the various regions of the images may have varying frame rates. In one example, the first resolution image data has a first frame rate, the second resolution image data has a second frame rate, and the third resolution image data has a third frame rate. And the first frame rate is greater than the second frame rate, and the second frame rate is greater than the third frame rate. It is appreciated that, like the resolution, frame rate may decrease gradually from the first region to the third region (e.g., linearly, exponentially, degreasing at a decreasing rate, decreasing at an increasing rate, or the like). It is appreciated that in some examples, the frame rates of all the pixels in all of the regions are aligned. Put another way, although the pixels in the different regions have different frame rates, they receive new image data transferred from the controller at the same time. For example, a pixel in the first region may receive image data from the controller at 120 Hz, while a pixel in the second region may receive image data from the controller at 60 Hz; both pixels would update when the second (slower) pixel updated. Thus, the first frame rate is an integer multiple of the second frame rate. In other embodiments, and the second frame rate may be an integer multiple of the third frame rate.
In some examples, it is appreciated that the various regions of the images may have varying refresh rates. In the depicted example, the first resolution image data has a first refresh rate, the second resolution image data has a second refresh rate, and the third resolution image data has a third refresh rate. And the first refresh rate is greater than the second refresh rate, and the second refresh rate is greater than the third refresh rate. In some examples, the second refresh rate decreases gradually from the first region to the third region (e.g., linearly, exponentially, degreasing at a decreasing rate, decreasing at an increasing rate, or the like). It is appreciated that in some examples, the refresh period of all the pixels in all of the regions is aligned. For example, the pixels in the first region may refresh at a rate of 240 Hz, while the pixels in the second region refresh at 120 Hz, thus the pixels in the two different regions refresh at the same time but with different periods. Accordingly, the first refresh rate is an integer multiple of the second refresh rate. In other embodiments, the second refresh rate may be an integer multiple of the third refresh rate.
In one example, the display is initiated by a first frame with full resolution across the entire display (e.g., at both the eye focus regions and out of eye focus regions). This way user experience is not degraded before gaze location calculations are performed. Additionally, one of skill in the art will appreciate that “frame rate” refers to the frequency of the image data, while “refresh rate” refers to the refresh rate of the pixels in the display, and that these rates may be different.
Block 401 shows tracking eye movement with the sensor (which may include tracking eye focus direction, location on the display, angle of gaze, etc.). This information may then be sent to an eye tracking module (e.g., a component in the controller which may be implemented in hardware, software, or a combination of the two), to track the gaze location of the eye.
Block 403 depicts calculating the gaze location (e.g., based on the eye focus angle, and the distance between the eye and the display) and defining the address of each pixel at the boundary of the eye focus region (e.g., gaze location) on the display. These addresses are then sent to the controller. It is appreciated that the processor or control circuitry disposed in the head-mounted device may be considered part of the “controller”, in accordance with the teachings of the disclosure.
Block 405 illustrates comparing the address of image pixel data and the received eye focus boundary address with the controller. As shown, the controller determines if the image pixel is in the eye focus region.
Block 407 shows that, if the image pixel is in the eye focus region, then the image data for each pixel address is sent to the interface module (e.g., another component in the controller which may be implemented in hardware, software, or a combination thereof) for high resolution imaging.
Block 409 depicts that if the image pixel is not in the eye focus region, the system continues comparing the adjacent pixels, until it reaches the Nth pixel (e.g., the 10th pixel), then the system only sends the image data of the Nth (e.g., 10th) pixel to the interface module. Accordingly, the data set may be greatly reduced. In some examples, the Nth pixel could be more pixels or less pixels than the 10th. One of skill in the art will appreciate that other methods may also be used to reduce the data set for partial low resolution imaging.
Block 411 illustrates that the interface module sends a frame to the VR display via wireless or wired connection. Each frame includes a full resolution data set with a pixel address in the eye focus region and a 1/N (e.g., 1/10) full resolution data set for pixel addresses out of the eye focus region. This effectively reduces the bandwidth needed to provide the image data from the controller (e.g., controller 131 of
Block 413 shows displaying (e.g., on display 101) the image with full resolution at eye focus region and 1/N full resolution outside of eye focus region.
Block 501-block 505 depict similar actions as blocks 401-405 in method 400 of
Block 507 shows the system determining if an image pixel is in a transition region if the pixel is not in the eye focus region.
Block 509 shows that if the image pixel is not determined to be in the transition region, the system continues comparing the adjacent pixels, until the system reaches the Nth pixel (e.g., the 10th pixel), then the system sends the image data of the Nth pixel to the interface module.
Block 511 shows that if the image pixel is determined to be in the transition region, the system continues comparing the adjacent pixels, until the system reaches the (N/2)th pixel (e.g., the 5th pixel) then the system sends the image data of (N/2)th pixel to the interface module.
Block 513 shows that if the image pixel is in the eye focus region (see block 505), then image data for each pixel address is sent to the interface module for high resolution imaging.
Block 515 illustrates sending one frame with three sub-frames to the VR display (via wireless or wired connection) with the interface module. The first sub-frame may include a 1/N (e.g., 1/10) full resolution data set, with pixel addresses out of the transition region. The second sub-frame may include 2/N (e.g., 1/5) full resolution data set with pixel address in the transition region. The third sub-frame may include a full resolution data set with pixel address in the eye focus region. Thus, the bandwidth needed to provide the image data from controller to VR headset display is greatly reduced.
Block 517 depicts displaying one frame image with a high resolution at the eye focus region with smoother resolution degradation toward the region away from the gaze location, without perceptible loss in image quality.
Block 601 shows the system using a sensor (e.g., sensor 155) to monitor eye movement, and send the eye focus angle to an eye tracking module.
Block 603 illustrates the eye tracking module in the system calculating (based on the eye focus angle and the distance between the eye and the display) the gaze location of the eye, and defining the address of each pixel at the boundary of eye focus region and a transition region on the display. This address may then be sent to the VR controller.
Block 605 depicts using the controller to compare the address of the image pixel data and the received eye focus boundary address.
Block 607 shows the system determining if the image pixel is in the transition region, if the image pixel was not in the eye focus region.
Block 609 illustrates if the image pixel is not in the transition region, then the system continues to compare the adjacent pixels, until it reaches the Nth pixel (e.g., the 10th pixel), then the system sends the image data of Nth pixel to the interface module.
Block 611 depicts if the image pixel is in the transition region, the system continues comparing the adjacent pixels, until it reaches the (N/2)th pixel (e.g., the 5th pixel), then the system sends the image data of (N/2)th pixel to the interface module.
Block 613 shows if the image pixel is in the eye focus region, the system sends image data for each pixel address to the interface module, for high resolution imaging.
Block 615 illustrates the interface module sending sub-frames with a high frame rate and high refresh rate to the VR display via a wireless or wired connection. Each sub-frame includes high resolution data set with pixel addresses in the eye focus region.
Block 617 depicts the interface module sending sub-frames with a medium frame rate and medium refresh rate to the VR display via a wireless or wired connection. Each sub-frame includes medium resolution data set with pixel addresses in the transition region.
Block 619 shows the interface module sending sub-frames with a low frame rate and a low refresh rate to the VR display via a wireless or wired connection. Each sub-frame includes a low resolution data set with a pixel addresses out of the transition region.
Block 621 illustrates displaying the image with high resolution, fast frame rate and fast refresh rate at eye focus region, without perceptible lose in image quality.
The above description of illustrated examples of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific examples of the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific examples disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.