Personal display with vision tracking

Abstract

A display apparatus includes an image source, an eye position detector, and a combiner, that are aligned to a user's eye. The eye position detector monitors light reflected from the user's eye to identify the pupil position. If light from the image source becomes misaligned with respect to the pupil, a physical positioning mechanism adjusts the relative positions of the image source and the beam combiner so that light from the image source is translated relative to the pupil, thereby realigning the display to the pupil. In one embodiment, the positioner is a piezoelectric positioner and in other embodiments, the positioner is a servomechanism or a shape memory alloy.

What is claimed is:  
     
         1 . A method of producing an image for viewing by an eye, comprising the steps of: 
 emitting light from a first location;    modulating the light in a pattern corresponding to the image;    producing a positioning beam;    directing the positioning beam along a first path toward the eye;    receiving a portion of light reflected from the eye with an optical detector;    producing an electrical signal responsive to the received reflected light;    identifying a pupil position responsive to the electrical signal; and    physically repositioning the first location in response to the electrical signal.    
     
     
         2 . The method of  claim 1  wherein an image source produces the light and wherein the step of physically repositioning the first location in response to the electrical signal includes physically repositioning the image source relative to the user's eye.  
     
     
         3 . The method of  claim 2  wherein the step of physically repositioning the image source includes activating a piezoelectric positioner coupled to the image source.  
     
     
         4 . The method of  claim 3  wherein the step of physically repositioning the image shown includes activating a shape memory alloy coupled to the image source.  
     
     
         5 . The method of  claim 1  wherein the optical detector includes a detector array and wherein the step of producing an electrical signal responsive to the received reflected light includes outputting data from the detector array.  
     
     
         6 . The method of  claim 1  wherein the positioning beam is an infrared beam.  
     
     
         7 . The method of  claim 1  wherein the step of producing an electrical signal includes the steps of: 
 outputting data from the detector array;  
 retrieving data stored in a memory; and  
 producing the electrical signal in response to the retrieved data.  
 
     
     
         8 . The method of  claim 1  wherein a portion of the emitted light forms the positioning beam.  
     
     
         9 . The method of  claim 1  wherein the step of emitting light includes producing the light with an image source and guiding the light with guiding optics and wherein the step of physically repositioning the first location in response to the electrical signal includes physically varying the relative positioning of the guiding optics and the image source.  
     
     
         10 . The method of  claim 9  wherein the guiding optics include a lens.  
     
     
         11 . The method of  claim 10  wherein the guiding optics further include a turning reflector.  
     
     
         12 . A method of producing an image in response to an image signal for perception by a user, comprising the steps of: 
 emitting, from a first position, light corresponding to the image responsive to the image signal;    directing the emitted light corresponding to the image toward the user's eye;    determining an eye position while directing the emitted light corresponding to the image toward the user's eye; and    responsive to the determined eye position adjusting the first position to direct the emitted light toward the user's pupil.    
     
     
         13 . The method of  claim 12  wherein the step of determining the eye position includes the steps of: 
 emitting a tracking beam of light;  
 directing the tracking beam of light toward the user's eye; and  
 monitoring light reflected from the user's eye.  
 
     
     
         14 . The method of  claim 13  wherein the step of emitting a tracking beam of light includes the steps of emitting the tracking beam from substantially the first position.  
     
     
         15 . The method of  claim 12  wherein the step of monitoring light reflected from the user's eye includes: 
 positioning an optical detector adjacent to the first position; and  
 receiving a portion of the reflected light with the detector.  
 
     
     
         16 . The method of  claim 12  wherein the step of directing the emitted light corresponding to the image toward the user's eye includes scanning the emitted light with a scanner.  
     
     
         17 . The method of  claim 16  wherein the step of directing the tracking beam of light toward the user's eye includes scanning the tracking beam with the scanner.  
     
     
         18 . A method in a display apparatus of identifying alignment of an optical source with an eye, comprising the steps of: 
 projecting light from a tracking source onto the eye;    receiving light reflected from a plurality of locations on the eye;    generating electrical signals corresponding to the received reflected light;    responsive to the electrical signals, identifying a region of the eye having a reduced reflectance relative to other regions of the eye; and    comparing the identified region of reduced reflectance with a reference region corresponding to centering of the optical source relative to the reduced reflectance region.    
     
     
         19 . The method of  claim 18  further including the step of aligning the tracking source in a substantially fixed position relative to the optical source.  
     
     
         20 . The method of  claim 18  wherein the step of receiving light reflected from a plurality of locations on the eye includes receiving light reflected from a plurality of locations on the eye with a photodetector.  
     
     
         21 . The method of  claim 20  wherein the photodetector is a two-dimensional detector array.  
     
     
         22 . The method of  claim 21  wherein the two-dimensional detector array is a CCD array.  
     
     
         23 . The method of  claim 20  wherein the photodetector includes a plurality of integrated detectors.  
     
     
         24 . A method of aligning a virtual image to an eye, comprising the steps of: 
 directing image light from a first location along a first set of optical paths to the eye produce the virtual image;    directing a tracking beam of light toward the eye such that a portion of the tracking beam is reflected from the eye;    receiving a reflected portion of the tracking beam with a photodetector;    producing an electrical signal in response to the reception of the reflected portion;    responsive to the electrical signal, identifying a region of the reflected portion corresponding to a pupil;    determining an adjustment of first location that increases the amount of image light entering the pupil; and    adjusting the first location responsive to the determined adjustment.    
     
     
         25 . The method of  claim 24  wherein the display includes an image source that produces the image light and a detector that produces the electrical signal, and wherein the image source and detector are mounted to a common supporting body.  
     
     
         26 . The method of  claim 25  wherein the step of adjusting the first set of optical paths responsive to the determined adjustment includes moving the supporting body.  
     
     
         27 . The method of  claim 26  wherein the step of moving the supporting body includes activating a piezoelectric positioner.  
     
     
         28 . The method of  claim 27  wherein the step of moving the supporting body includes activating a shape memory alloy.  
     
     
         29 . A virtual display for producing an image for viewing by a user's eye, comprising: 
 an image source operative to emit light in a pattern corresponding to the image along a path toward the user's eye;    an optical detector aligned to the user's eye and operative to detect a location of a region of the user's eye having a reflectance corresponding to a selected eye feature having a predetermined position relative to a pupil of the eye, the optical detector producing a signal indicative of the detected location; and    a positioning mechanism having a control input coupled to the optical detector and a positioning output coupled to the image source, the positioning mechanism being responsive to the signal indicative of the detected location to physically reposition the image source in a direction that shifts the optical path to the pupil.    
     
     
         30 . The display of  claim 29  wherein the positioned is an electrically actuated positioner and wherein the signal indicative of the detected location is an electrical signal.  
     
     
         31 . The display of  claim 29  wherein the image source includes a light emitter and imaging optics configured for relative repositioning by the positioning mechanism.  
     
     
         32 . The display of  claim 29  wherein the image source and detector are mounted to a common supporting body.  
     
     
         33 . The display of  claim 29  wherein the positioning mechanism is coupled to the common body to physically displace the common body.  
     
     
         34 . The display of  claim 29  wherein the image source is a retinal scanner.  
     
     
         35 . The display of  claim 29  further comprising a beam combiner having a first input aligned to the image source and a second input, the beam combiner being operative to direct light from the first and second inputs and to provide the combined light to a user's retina.  
     
     
         36 . A display apparatus including eye position tracking, comprising: 
 a first scanner;    beam-turning optics aligned to the eye;    an image source mounted to a base and aligned to beam-turning optics at an angle selected to direct light from the image source to the eye;    an optical source aligned to the eye;    a detector aligned to the eye and responsive to output an electrical signal indicative of alignment of the optical source relative to a selected region of the eye; and    a positioning mechanism coupled to the base and responsive to the electrical signal from the detector to physically adjust the relative positions of the base relative and the beam-turning optics.    
     
     
         37 . The display apparatus of  claim 36  wherein the image source is a retinal scanner.  
     
     
         38 . The display apparatus of  claim 36  wherein the positioning mechanism is a piezoelectric positioner.  
     
     
         39 . The display apparatus of  claim 36  wherein the positioning mechanism is a servomechanism.  
     
     
         40 . The display apparatus of  claim 36  wherein the positioning mechanism includes a shape memory alloy.  
     
     
         41 . The display apparatus of  claim 36  wherein beam-turning optics includes a beam combiner.  
     
     
         42 . The display apparatus of  claim 41  wherein the beam combiner includes an optical magnifier.  
     
     
         43 . The display apparatus of  claim 42  wherein the optical magnifier is a mirror.  
     
     
         44 . The display apparatus of  claim 40  wherein the beam combiner includes a beam splitter.  
     
     
         45 . The display apparatus of  claim 36  further including a head mounting structure carrying the optical source, the beam-turning optics, and the positioning mechanism.  
     
     
         46 . A display apparatus, comprising a light movable source operative to emit a beam of light modulated according to a derived image, the movable light source being responsive to a position input to vary the effective position of the beam of light, an exit pupil expander positioned to receive the emitted beam of light, the exit pupil expander being responsive to emit a plurality of exit beams in response to the received beam of light; an eye tracker oriented to detect a user's eye position and configured to output an electric signal corresponding to the detected eye position; a positioner having an electrical input coupled to the eye tracker to receive the electric signal, the positioner further being coupled to the light source, the positioner being operative to provide the position input in response to the electrical signal.  
     
     
         47 . The display apparatus of  claim 46  wherein the exit pupil expander is a diffractive element.