3-D viewing system

Abstract

A 3-D viewing system is disclosed that enables multiple operators to share a common objective element while readily adjusting the orientation of images that are displayed to one or more moveable display units. The orientation of images that are displayed at a movable display unit can be made to automatically depend on the position/orientation of the display unit. Thus, greater freedom in viewing postures is provided than previously available in 3-D viewing systems that share a common objective element, and each operator may view a 3-D image with proper perspective for his position/orientation. In order to reduce the number of optical components, the need to adjust optical components, and reduce costs, images from at least two different optical perspectives may be time-division multiplexed onto a single optical detecting device. Moreover, wide-angle, electronic color displays are disclosed which demodulate time-multiplexed image signals having two different parallaxes in a manner that dispenses with the need for wearing polarized glasses in order to experience a wide-angle, 3-D viewing experience. An electronic image display unit demultiplexes image data using left and right LED sets that are energized in sequence to emit up to three color light beams toward the left and right eyes of a viewer, at a frequency higher than 30 times per second. The light beams are then modulated with the image data for that color component using one or more high-speed, image modulators. Such modulators may be formed of transmissive or reflective liquid crystals in a known manner, or by an array of DMD's that are controlled in a binary fashion to reflect light for a given pixel within or outside an exit pupil of the display. If DMD's are used as the modulator, the duty cycle for a given pixel may be controlled in order to provide gradation of the display brightness for that pixel.

What is claimed is:  
     
         1 . A 3-D viewing system with which multiple viewers can view electronic display images of an object while sharing an optical objective, and wherein at least one of said multiple viewers may change his position or head orientation while maintaining a moveable electronic display unit in position for viewing, said system comprising: 
 an optical objective that is shared among operators of the 3-D viewing system;    an image detecting unit;    a moveable electronic image display unit that displays images which have been captured by the image-detecting unit; and    means to change images that are displayed by the moveable electronic image display unit in response to a change in location or orientation of the moveable electronic image display unit.    
     
     
         2 . The 3-D viewing system of  claim 1 , wherein the means to change images comprises: 
 an arm that is rotatable about the optical axis of the optical objective, said arm supporting 
 the moveable electronic image display unit,  
 a beam-splitting prism, and  
 two apertures that select light which has been reflected from a surface of the beam-splitting prism, said two apertures passing light to the image detecting unit.  
   
     
     
         3 . The 3-D viewing system of  claim 2 , wherein: 
 said two apertures are left and right apertures in an aperture plate that is rotatable about an axis;    the moveable electronic image display unit may be tilted about an axis that is parallel to the axis about which the aperture plate is rotatable; and    the aperture plate is linked to the moveable electronic image display unit so that tilting the display unit rotates the aperture plate.    
     
     
         4 . The 3-D viewing system of  claim 2 , wherein the means to change images comprises: 
 a detecting means for detecting the location or orientation of the moveable electronic image display unit; and    a changing means for changing the location or orientation of the image detecting unit in response to a change in location or orientation of the moveable electronic image display unit.    
     
     
         5 . The 3-D viewing system of  claim 4 , wherein: 
 the moveable electronic image display unit is separated from the image detecting unit; and    the detecting means uses remote sensing by a navigation unit to detect the location and orientation of the moveable electronic image display unit.    
     
     
         6 . The 3-D viewing system of  claim 5 , wherein the moveable electronic image display unit is head-mounted.  
     
     
         7 . The 3-D viewing system of  claim 1 , wherein the image detecting unit includes two image detecting devices.  
     
     
         8 . The 3-D viewing system of  claim 1 , wherein the image detecting unit consists of a single image detecting device and images from two light paths having different optical perspectives are time-division multiplexed onto the optical detecting device using a switching means that is synchronized in operation with the capture of image data by the optical detecting device.  
     
     
         9 . The 3-D viewing system of  claim 8 , wherein wavelength selective devices having a characteristic that is controlled as a function of time are provided in the two light paths in order to time-division multiplex color image data onto light beams transiting these paths before the light beams are incident onto the image detecting device.  
     
     
         10 . The 3-D viewing system of  claim 1 , wherein the images that are displayed on the moveable electronic image display unit are monochrome images.  
     
     
         11 . The 3-D viewing system of  claim 1 , wherein color images are displayed on the moveable electronic image display unit.  
     
     
         12 . The 3-D viewing system of  claim 1 , wherein said moveable display unit may be moved to a selected one of three angular positions about the optical axis of said shared optical objective, said 3-D viewing system including: 
 two image detecting units that share said optical objective;    two optical imaging systems, each located in optical paths positioned between the shared optical objective and a respective one of said image detecting units, each optical imaging system including means to time-multiplex two light beams that have passed through different apertures onto an optical path; and    means to selectively display image pairs whereby detected images from four apertures are selectively displayed in pairs on the moveable electronic image display unit, depending on its position.    
     
     
         13 . The 3-D viewing system of  claim 12 , wherein: 
 the moveable electronic image display unit includes left and right eye display panels;    a rotation angle of a rotatable arm that supports the moveable electronic image display unit is monitored; and    the means to selectively display image pairs selects the inputs to these left and right display panels depending on the rotation angle of the arm.    
     
     
         14 . The 3-D viewing system of  claim 13 , wherein the means to selectively display image pairs includes means to selectively rotate certain images that are displayed, depending on the rotation angle of the arm so that the images that are displayed are displayed with a proper vertical orientation with respect to the viewer.  
     
     
         15 . The 3-D viewing system of  claim 9 , and further comprising: 
 means to demultiplex color encoded images from different perspectives, said means to demultiplex including LED sets and at least one image modulator that are sequentially energized, in time-sequence, in order to form image-modulated light beams that are separately directed to the left and right eye of a viewer, to thereby enable the viewer to view wide-angle images without polarized glasses that are perceived as wide-angle, 3-D color images.    
     
     
         16 . The 3-D viewing system of  claim 15 , wherein said at least one image modulator is formed of a transmissive, two-dimensional, liquid crystal array.  
     
     
         17 . The 3-D viewing system of  claim 15 , wherein said at least one image modulator is formed of a reflective, two-dimensional, liquid crystal array.  
     
     
         18 . The 3-D viewing system of  claim 15 , wherein said at least one image modulator is formed of a reflective, two-dimensional, DMD array.  
     
     
         19 . The 3-D viewing system of  claim 18 , wherein pixel intensity gradation is provided by controlling the duty cycle that a given pixel reflects light to the eye during the period that an LED is energized.