Computer graphics processing and selective visual display system – Image superposition by optical means – Operator body-mounted heads-up display
Reexamination Certificate
2000-05-11
2003-03-18
Shankar, Vijay (Department: 2673)
Computer graphics processing and selective visual display system
Image superposition by optical means
Operator body-mounted heads-up display
C345S007000, C345S009000
Reexamination Certificate
active
06535183
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to augmented virtual retinal display devices, and more particularly to a system for tracking viewer position and for adding data to a view based upon viewer position.
A virtual retinal display device is an optical device for generating an image upon the retina of an eye. Light is emitted from a light source, passed through a lens, then deflected along a scan path by a scanning device. At a distance defined by the lens the scanned light converges to a focal point for each pixel position. As the scanning occurs the focal point moves along to define an intermediate image plane. The light then diverges beyond the plane. An eyepiece is positioned along the light path beyond the intermediate image plane at some desired focal length. An “exit pupil” occurs shortly beyond the eyepiece in an area where a viewer's eye pupil is to be positioned.
A viewer looks into the eyepiece to view an image. The eyepiece receives light that is being deflected along a raster pattern. Light thus impinges on the viewer's eye pupil at differing angles at different times during the scanning cycle. This range of angles determines the size of the image perceived by the viewer. Modulation of the light during the scanning cycle determines the content of the image.
An augmented virtual retinal display is a see-through display which overlays an image onto a background. The overlaid image is a virtual image. The background is a real world view of the ambient environment. The overall image is formed by adding light to the background. The added light corresponds to the virtual image. The virtual image appears to be transparent because in the display portion at which the image is formed, light from both the virtual image and the background impinge on the same photoreceptors in the viewer's eye.
SUMMARY OF THE INVENTION
According to the invention, a scanned beam tracking system is included in a virtual retinal display. The function of the tracking system is to provide information for determining where a user is looking. In a preferred embodiment head position and orientation is tracked. Information is displayed based upon the viewer's eye position.
According to one aspect of the invention, a non-visible light source (e.g., infrared light source) generates light for scanning the viewer's environment in the direction the viewer's head is looking. A visible light source generates visible light which is scanned on a viewer's retina to generate a virtual image. A common scanning system is used to scan both the non-visible light and the visible light. The visible light is directed into the viewer's eye. The non-visible light is directed away from the viewer's eye into the environment. Thus, the scanning rate for the tracking system is the same as the scanning rate for the virtual display.
According to another aspect of the invention, a beamsplitter with an infrared mirror reflects the infrared light away from the viewer's eye toward the environment, while passing visible light (e.g., virtual image and background light from environment) toward from the viewer's eye.
According to another aspect of the invention, infrared reflectors are positioned in the environment. When the infrared light from the virtual retinal display scans over a reflector the reflector directs the infrared light back toward the virtual retinal display. The virtual retinal display beamsplitter with infrared mirror deflects such light away from the viewer's eye along a path toward an infrared detector. The round trip time of the infrared light is substantially less than the scanning time for scanning an image frame onto the viewer's retina. Thus, the position of the reflector is known relative to the scanning cycle. Specifically, the current pixel of the scanning cycle when the infrared return light is detected corresponds to the position of the reflector.
According to another aspect of this invention, multiple reflectors are positioned in the environment. In some embodiments, a reflector has a reflection pattern identification which allows the system to know which reflector or which type of reflector is being scanned at a given time during the scan cycle.
According to another aspect of this invention, when at least three reflectors are scanned during a given scan cycle, the system can triangulate a precise position of the user relative to such reflectors.
According to another aspect of the invention, an image, graphic information or text information is added to the display imagery when a reflector is scanned. In one embodiment, such added information is stabilized relative to the head position. For example, such information is always displayed at a prescribed portion of the display (e.g., upper right portion) when a reflector is scanned. In another embodiment such information is fixed relative to the background environment. In an exemplary embodiment the reflector is placed upon a target object. When the reflector is detected, the target object is within the field of view of the user. Textual information about the target object is displayed in a prescribed portion of the field of view (e.g., lower right corner). Even when the user's head moves, the textual information stays fixed in the prescribed portion of the field of view as long as the target object remains within the field of view. Once the user looks in a direction which excludes the target object from the field of view, the textual information is removed. Thus, the added information is stabilized relative to the head.
In another embodiment the added information is stabilized relative to the background. For example, a predetermined virtual image is overlaid onto the background at a position registered to the background (e.g., a virtual image ornament is displayed to appear on a given branch of a real tree within the real background viewed by the user). Even when the viewer's head moves (and thus the virtual retinal display), as long as the desired location is still within view of the user, then the information is added to the display at a point fixed relative to the background (e.g., the virtual ornament appears at the same spot on the real tree).
According to another aspect of the invention, the working volume for the tracking system corresponds to the field of view of the retinal display. Thus, any reflectors within the field of view are detected.
According to another aspect of the invention, an augmented virtual retinal display system with view tracking receives an image data signal for generating a virtual image upon a viewers eye. The system also receives background light from a real environment for passing a real environment background image to the viewer's eye. The system has a field of view for viewing the real environment and the virtual image. The system includes a light source for generating visible light and infrared light. A modulator modulates the visible light as a function of the image data signal to define a sequence of display pixels forming the virtual image. A scanner receives the infrared light and the modulated visible light, and deflects the received visible light and infrared light along a raster pattern. The scanned visible light and infrared light impinge on a beamsplitter. The beamsplitter includes a coating at the incident surface which is reflective to the infrared light. The infrared light is reflected off the infrared reflective coating into the real environment. The scanned visible light passes through the infrared reflective coating then is in-part reflected and in-part passed. The reflected portion of the visible light enters the real environment. The passed portion impinges on a concave mirror, then is reflected back to the beamsplitter, and in turn, deflected toward the viewer's eye. Also impinging on the infrared reflective portion of the beamsplitter is the background light and the returning infrared light reflected from the real environment. Background light passes through the beamsplitter and travels a path destined for t
Johnston Richard S.
Melville Charles D.
Koda Steven P.
Shankar Vijay
University of Washington
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