Variable focus stereoscopic display system and method

Abstract

A variable focus stereoscopic display system includes first and second lenses positioned between a viewer's eyes and a stereoscopic display that alters the distance to the focus plane of the viewer based on the vergence of the viewer's eyes while viewing the stereoscopic display.

What is claimed is: 
     
         1 . A variable focus stereoscopic display system modifying a focus distance for viewing a stereoscopic display receiving image data, the variable focus stereoscopic display system comprising:
 a first lens positioned between a first eye and the stereoscopic display;   a second lens positioned between a second eye and the stereoscopic display; and   wherein the first and second lenses are configured to modify the optical power for the variable focus stereoscopic display system and therefore the focus distance, the modification of the focus distance comprising being based on a vergence of the first and second eyes, changes in the focus distance are positively correlated with changes in a convergence distance of lines of sight of the first and second eyes, and the changes in the focus distance are determined independently from the image data.   
     
     
         2 . The variable focus stereoscopic display system of  claim 1  further comprising:
 a sensor configured to sense an amount of the vergence; and 
 a controller configured to modify the optical power of the first and second lenses in response to the amount of the vergence. 
 
     
     
         3 . The variable focus stereoscopic display system of  claim 1  wherein each of the first and second lenses comprise:
 a first portion having a first optical power; and 
 a second portion having a second optical power greater than the first optical power. 
 
     
     
         4 . The variable focus stereoscopic display system of  claim 3  wherein the first portions of the first and second lenses are adjacent to one another. 
     
     
         5 . The variable focus stereoscopic display system of  claim 3  wherein the first portions of the first and second lenses are offset from the second portions with respect to a line between the first and second eyes. 
     
     
         6 . The variable focus stereoscopic display system of  claim 1  further comprising:
 a sensor configured to sense an amount of the vergence; 
 a controller configured to modify the optical power of the first and second lenses in response to the amount of the vergence; 
 a third lens positioned between the first eye and the stereoscopic display; and 
 a fourth lens positioned between the second eye and the stereoscopic display; 
 wherein each of the third and fourth lenses comprise: 
 a first portion having a first optical power; and 
 a second portion having a second optical power greater than the first optical power. 
 
     
     
         7 . The variable focus stereoscopic display system of  claim 1  further comprising:
 an apparatus configured to track a direction of a gaze of the eyes and enable the variable focus stereoscopic display system when the eyes are viewing the stereoscopic display and disable the variable focus stereoscopic display system when the eyes are not viewing the stereoscopic display. 
 
     
     
         8 . The variable focus stereoscopic display system of  claim 1  wherein the first and second lenses are calibrated to provide about a zero optical power at a viewer preferred focus distance. 
     
     
         9 . The variable focus stereoscopic display system of  claim 1  further comprising:
 a flight deck display system of an aircraft including the stereoscopic display. 
 
     
     
         10 . A method for adjusting a focus plane for viewing a stereoscopic display, comprising:
 sensing an amount of the vergence;   altering a distance of the focus plane from first and second eyes in response to vergence of the first and second eyes, wherein changes in the focus plane distance are correlated with changes in the vergence such that the disparity between focus plane and a plurality of cues associated with the vergence are reduced from prior to the distance being altered;   modifying, in response to the amount of the vergence, an optical power of a first lens and a second lens positioned between the stereoscopic display and the first and second eyes, respectively; and   generating image data to be displayed, wherein generation of the image data is independent of the sensed amount of vergence, and sensing the amount of vergence is independent of the image data.   
     
     
         11 . The method of  claim 10  wherein the altering step comprises changing the view of the stereoscopic display from a first portion of each of the first and second lenses to a second portion of each of the first and second lenses in response to a line of sight of the first and second eyes, the second portion having an optical power different than the first portion such that changes in the focus plane distance are positively correlated with changes in a convergence distance associated with the cues. 
     
     
         12 . The method of  claim 10  wherein the first and second lenses comprise a single lens region. 
     
     
         13 . The method of  claim 10  further comprising:
 tracking the direction of the gaze of the eyes; and 
 disabling the altering step when the first and second eyes are not viewing the stereoscopic display. 
 
     
     
         14 . The method of  claim 13  further comprising:
 switching the focus plane to a nominal optical power setting when the altering step is disabled. 
 
     
     
         15 . The method of  claim 13  further comprising:
 increasing the optical power as a convergence distance associated with the cues is decreased when the altering step is disabled.