Patent Publication Number: US-2012033297-A1

Title: Stereoscopic image displaying method and stereoscopic display device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to a stereoscopic image displaying method and a stereoscopic display device, and more particularly, to a stereoscopic image displaying method providing different viewing distances and a stereoscopic display device for different viewing distances. 
     2. Description of the Prior Art 
     Stereoscopic display technique is developed to provide two separate images individually to the left and right eyes of an observer, and thus the observer obtains a stereoscopic vision. 
     The conventional stereoscopic display devices can be classified into passive approach and active approach: The passive approach involves using of eyewear such as polarized glasses or shutter glasses while the active approach provides 3D images without assistance as mentioned above. Conventionally, the active approach involves techniques such as the parallax barrier. 
     Please refer to  FIG. 1 , which is a schematic drawing illustrating optical paths of a conventional stereoscopic display device employing a parallax barrier. As shown in  FIG. 1 , the conventional stereoscopic display device  100  includes a liquid crystal display (LCD) panel  110  and a parallax barrier  120 . The LCD panel  110  provides a left eye image L and a right eye image R, and the parallax barrier  120 , such as an optical grating, includes a plurality of shading regions  122  and transparent regions  124  alternately and repetitively arranged for separating the left eye image L and the right eye image R. Such that the observer can perceive the left eye image L and the right eye image R individually and obtain the 3D stereoscopic images. 
     It is noteworthy that the left eye image L and the right eye image R provided by the LCD panel  110  have a same pixel pitch  130 , which is predetermined and fixed. Furthermore, the shading regions  122  and the transparent regions  124  of the parallax barrier  120  have the same barrier pitches  132 , which are determined according to a distance  134  between the parallax barrier  120  and the LCD panel  110 , an ideal viewing distance  136  between the observer and the LCD panel  110 , and a distance  138  between two eyes and a center of two eyes of the observer. As shown in  FIG. 1 , the observer perceives the desired 3D stereoscopic images at a spot satisfied the viewing distance  136 . But when the observer leaves the spot, no stereoscopic images are observed. 
     In other words, the conventional stereoscopic display device employing the parallax barrier provides an unchangeably fixed ideal viewing distance. When the observer has to change the real viewing distance, the real viewing distance not matching the fixed ideal viewing distance makes the observer cannot obtain the stereoscopic images. Consequently, the stereoscopic display device having the parallax barrier provides stereoscopic images in a limited space. 
     SUMMARY OF THE INVENTION 
     Therefore the present invention provides a stereoscopic image displaying method able to provide different viewing distances and a stereoscopic display device for different viewing distances. 
     According to a first aspect of the present invention, a stereoscopic display device is provided. The stereoscopic display device includes a display panel for displaying an image, a parallax barrier having a first barrier region to an Nth barrier region and a first distance between the parallax barrier and the display panel, the first barrier region to the Nth barrier region respectively having a first barrier pitch to a Nth barrier pitch, a detection-and-calculation device for detecting a second distance between the display panel and an observer, and a parallax barrier adjustment device for selecting one barrier region from the first barrier region to Nth barrier region. 
     According to a second aspect of the present invention, another stereoscopic display device is provided. The stereoscopic display device includes a display panel for displaying an image, a parallax barrier and an adjustable first distance between the parallax barrier and the display panel, a detection-and-calculation device for detecting a second distance between the display panel and an observer and a third distance between two eyes and a center of the two eyes of the observer, and a parallax barrier distance adjustment device for adjusting the adjustable first distance. 
     According to the stereoscopic display devices provided by the present invention, different viewing distances are obtained by providing barrier regions having different barrier pitches or by providing different distances between the parallax barrier and the display panel. Therefore, when the observer increases or reduces the real viewing distance, the stereoscopic image displaying method and the stereoscopic display device provided by the present invention always provide 3D stereoscopic images of high quality. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic drawing illustrating optical paths of a conventional stereoscopic display device employing a parallax barrier; 
         FIG. 2  is a schematic drawing illustrating a stereoscopic image displaying method and a stereoscopic display device provided by a first preferred embodiment of the present invention; 
         FIGS. 3-4  are schematic drawings illustrating different optical paths of the preferred embodiment in different operations; 
         FIG. 5  is a schematic drawing illustrating a modification to the preferred embodiment; 
         FIG. 6  is a schematic drawing illustrating a stereoscopic image displaying method and a stereoscopic display device provided by a second preferred embodiment of the present invention; 
         FIGS. 7-8  are schematic drawings illustrating different optical paths of the preferred embodiment in different operations; and 
         FIGS. 9-10  are schematic drawings illustrating modifications to the preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, electronic equipment manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. 
     Please refer to  FIGS. 2-5 , wherein  FIG. 2  is a schematic drawing illustrating a stereoscopic image displaying method and a stereoscopic display device provided by a first preferred embodiment of the present invention,  FIGS. 3-4  are schematic drawings illustrating different optical paths of the preferred embodiment in different operations, and  FIG. 5  is a schematic drawing illustrating a modification to the preferred embodiment. Please refer to  FIGS. 2-4 . A stereoscopic display device  200  provided by the preferred embodiment includes a display panel  210  for displaying an image. The display panel  210  can be a liquid crystal display (LCD) panel accompanied with a backlight module (not shown), but not limited to this. The image provided by the display panel  210  is divided into a left eye image L and a right eye image R (shown in  FIG. 3  and  FIG. 4 ) according to the preferred embodiment. The adjacent left eye image L and right eye image R respectively has a pixel pitch “i” formed therebetween. The stereoscopic display device  200  further includes a parallax barrier  220  and a first distance “g” between the parallax barrier  220  and the display panel  210 . The parallax barrier  220  includes a first barrier region  2201  to an Nth barrier region  220 N. The first barrier region  2201  has a plurality of shading regions  2221  and a plurality of transparent regions  2241 . In the same concept the Nth barrier region  220 N also has a plurality of shading regions  222 N and a plurality of transparent regions  224 N. The shading region  2221  and the transparent region  2241  of the first barrier region  2201  include a first barrier pitch b 1 . In the same concept, the shading region  222 N and the transparent region  224 N of the Nth barrier region  220 N also include a Nth barrier pitch b n . In other words, the shading regions  2221  and transparent regions  2241  that have strip patterns construct the first barrier region  2201  and each strip pattern has the same width, which is the first barrier pitch b 1 . In the same concept, the shading regions  222 N and the transparent regions  224 N that have strip patterns construct the Nth barrier region  220 N, and each strip pattern has the same width, that is the Nth barrier pitch b n . More important, the first barrier pitch b 1  to the Nth barrier pitch b n  are different from each other. It is noteworthy that in the preferred embodiment, the parallax barrier  220  is positioned in front of the display panel  210 , but it is not limited to position the parallax barrier  220  behind the display panel  210 , in particularly, to position the parallax barrier  220  between the display panel  210  and the backlight module in the present invention. 
     Please refer to  FIGS. 2-4 . The stereoscopic display device  200  provided by the preferred embodiment further includes a detection-and-calculation device  230  for detecting a second distance “z”, namely the viewing distance, between the display panel  210  and an observer. The detection-and-calculation device  230  includes at least a computing circuit (not shown) and a distance meter  232 . The detection-and-calculation device  230  further selectively includes an image device  234 . The distance meter  232  can include an infrared distance meter or a Laser distance meter, but not limited to this. Those skilled in the art would realize that any equipment that is used to detect second distance “z” between the observer and the display panel  210  can be used. Furthermore, the stereoscopic display device  200  includes a parallax barrier adjustment device  240 . The parallax barrier adjustment device  240  can include a roller  242  and a rotary stepping motor  244 . The parallax barrier adjustment device  240  can be positioned on the top/bottom sides of the stereoscopic display device  200  as shown in  FIG. 2 ; it also can be positioned on the left/right sides of the stereoscopic display device  200  as shown in  FIG. 5 . 
     According to the stereoscopic image displaying method provided by the preferred embodiment, it first provides the display panel  210  and the parallax barrier  220  as mentioned above. Then, the second distance “z” between the display panel  210  and the observer is detected by the distance meter  232  of the detection-and-calculation device  230 . After obtaining the second distance “z” from the distance meter  232 , the computing circuit is operated to obtain an ideal barrier pitch “13,” according to a formula (1): 
     
       
         
           
             
               
                 
                   b 
                   = 
                   
                     2 
                      
                     
                       i 
                        
                       
                         ( 
                         
                           
                             z 
                             - 
                             g 
                           
                           z 
                         
                         ) 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     According to the formula (1), it is found the barrier pitch “b” is always corresponding to the second distance “z” because the pixel pitch “i” and the first distance “g” are predetermined and fixed. In other words, ideal barrier pitches b i  suited for different viewing distances are obtained by the detection-and-calculation device  230  according to the preferred embodiment. 
     Please refer to the following exemplars: As shown in  FIG. 3  and  FIG. 4 , the pixel pitch “i” of the display panel  210  is 0.1 millimeter (mm) in and the first distance “g” between the display panel  210  and the parallax barrier  220  is 1.15 mm in the preferred embodiment, which are all predetermined and fixed. When different second distances “z” between the observer and the display panel  210  are detected by the detection-and-calculation device  230 , different ideal barrier pitches “b i ” are obtained according to formula (1), as shown in Table 1: 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 bi 
                 i 
                 z 
                 g 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 0.1996933 
                 0.1 
                 750 
                 1.15 
               
               
                   
                 0.19954 
                 0.1 
                 500 
                 1.15 
               
               
                   
                 0.199425 
                 0.1 
                 400 
                 1.15 
               
               
                   
                   
               
               
                   
                 unit: mm 
               
            
           
         
       
     
     According to the different ideal barrier pitches “b i ” that are suited for different second distances “z”, the rotary stepping motor  244  of the parallax barrier adjustment device  240  is used to select a barrier region that has the barrier pitch “b” equal to the ideal barrier pitch “b i ” from the parallax barrier  220  by rotating the roll  242 . As shown in  FIG. 3 , when the second distance “z” is exemplarily 750 mm, the rotary stepping motor  244  and the roller  242  select a proper barrier region such as the first barrier region  2201  having the barrier pitch “b 1 ” of 0.1996933 mm, that is equal to the ideal barrier pitch “b i ”, from the first barrier region  2201  to the Nth barrier region  220 N of the parallax barrier  220 . Therefore, the observer obtains the stereoscopic images at said viewing distance. In another exemplar as shown in  FIG. 4 , when the second distance “z” is exemplarily 400 mm, the rotary stepping motor  244  and the roller  242  selects another proper barrier region such as the barrier region  2203  having the barrier pitch b 3  of 0.199425 mm that is equal to the ideal barrier pitch “b i ” from the first barrier region  2201  to the Nth barrier region  220 N of the parallax barrier  220 . Therefore, the observer still obtains the stereoscopic images at said viewing distance. 
     According to the stereoscopic image displaying method and the stereoscopic display device of the first preferred embodiment, different viewing distances are obtained by providing different barrier regions having different barrier pitches. When the observer increases or reduces the viewing distance, the detection-and-calculation device of the stereoscopic display device of the present invention is utilized to detect the second distance “z” (the real viewing distance) between the observer and the display panel  210 , and thus an ideal barrier pitch “b i ” is obtained. Accordingly, a proper barrier region is selected from the first barrier region  2201  to the Nth barrier region  220 N of the parallax barrier  220  by the parallax barrier adjustment device  240 . In other words, the parallax barrier adjustment device  240  is used to select a proper barrier pitch that is equal to the ideal barrier pitch “b i ”, from the first barrier pitch “b 1 ” to the Nth barrier pitch “b n ”. Briefly speaking, when the observer increases or reduces the real viewing distance, the stereoscopic image displaying method and the stereoscopic display device of the first preferred embodiment always provides 3D stereoscopic images of high quality by providing a proper barrier region suited for the real viewing distance. 
     Please refer to  FIGS. 6-10 , wherein  FIG. 6  is a schematic drawing illustrating a stereoscopic image displaying method and a stereoscopic display device provided by a second preferred embodiment of the present invention, FIGS.  7 - 8  are schematic drawings illustrating different optical paths of the preferred embodiment in different operations, and  FIGS. 9-10  are schematic drawings illustrating modifications to the preferred embodiment. As shown in  FIG. 6 , a stereoscopic display device  300  having a display panel  310  and a backlight module (not shown) is provided by the preferred embodiment. The display panel  310  provides an image, and the image is divided into a left eye image L and a right eye image R (shown in  FIG. 7  and  FIG. 8 ) according to the preferred embodiment. The left eye image L and the right eye image R respectively have a pixel pitch “i” formed therebetween. The stereoscopic display device  300  further includes a parallax barrier  320  constructed by a plurality of shading regions  322  and a plurality of transparent regions  324  in stripe patterns (shown in  FIG. 7  and  FIG. 8 ). More important, the stereoscopic display device  300  includes an adjustable first distance “g a ” between the parallax barrier  320  and the display panel  310 . The parallax barrier  320  is positioned in front of the display panel  310 . However, it is not limited to position the parallax barrier  320  between the display panel  310  and the backlight module in the present invention. 
     Please still refer to  FIG. 6 . The stereoscopic display device  300  of the preferred embodiment also includes a detection-and-calculation device  330 . The detection-and-calculation device  330  is used to detect a second distance “z”, that is the viewing distance, between the display panel  310  and an observer. The detection-and-calculation device  330  includes at least a computing circuit (not shown), a distance meter  332 , and an image device  334 . The distance meter  332  can be an infrared distance meter or a Laser distance meter, but not limited to this. The image device  334  can be a charge coupled device but not limited to this. The distance meter  332  is used to detect the second distance “z” between the observer and the display panel  310  and the image device  334  is used to detect a third distance “e” between two eyes and a center of the two eyes of the observer. Additionally, the third distance “e” is a detected value in the preferred embodiment, but it also can be a predetermined value. 
     According to the stereoscopic image displaying method of the preferred embodiment, the display panel  310  and the parallax barrier  320  is provided. Then, the distance meter  332  and the image device  334  of the detection-and-calculation device  330  are used to detect the second distance “z” between the display panel  310  and the observer and the third distance “e” between the two eyes and the center of the two eyes of the observer. After obtaining the second distance “z” and the third distance “e” from the distance meter  332  and the image device  334 , the computing circuit is operated to obtain an ideal first distance “g i ” according to a formula (2): 
     
       
         
           
             
               
                 
                   z 
                   = 
                   
                     g 
                      
                     
                       ( 
                       
                         
                           e 
                           + 
                           i 
                         
                         i 
                       
                       ) 
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     According to the formula (2), it is found the first distance “g” is always corresponding to the second distance “z” and the third distance “e” because the pixel pitch “i” is predetermined and fixed. In other words, ideal first distances “g i ” suited for different second differences “z” and different third distances “e” are obtained by the detection-and-calculation device  330  according to the preferred embodiment. 
     As shown in  FIG. 7  and  FIG. 8 , the pixel pitch “i” of the display panel  310  is 0.1 mm in the preferred embodiment. In an exemplar, the third distance “e” between the two eyes and the center of the two eyes of the observer can be 75 mm or 50 mm in the preferred embodiment. When different second distances “z” are detected by the detection-and-calculation device  330 , different ideal first distance “g i ” are obtained according the abovementioned formula (2), as shown in Table 2: 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 e 
                 i 
                 z 
                 g i   
               
               
                   
                   
               
             
            
               
                   
                 75 
                 0.1 
                 750 
                 0.998668 
               
               
                   
                 75 
                 0.1 
                 500 
                 0.665779 
               
               
                   
                 75 
                 0.1 
                 400 
                 0.532623 
               
               
                   
                 50 
                 0.1 
                 750 
                 1.497006 
               
               
                   
                 50 
                 0.1 
                 500 
                 0.998004 
               
               
                   
                 50 
                 0.1 
                 400 
                 0.798403 
               
               
                   
                   
               
               
                   
                 Unit: mm 
               
            
           
         
       
     
     The stereoscopic display device  300  of the present invention further includes a parallax barrier distance adjustment device  340 . (shown in  FIG. 9  and  FIG. 10 ) According to different second distances “z” and different third distances “e” detected by the detection-and-calculation device  330 , different ideal first distance “g i ” are obtained. Consequently, the adjustable first distance “g a ” between the parallax barrier  320  and the display panel  310  is adjusted to be equal to the ideal first distance “g i ” by the parallax barrier distance adjustment device  340 . Therefore the observer positioned at different second distances “z” still obtains 3D stereoscopic images. As shown in  FIG. 7 , when the detected second distance “z” is exemplarily 750 mm and the detected third distance “e” is exemplarily 75 mm, the parallax barrier distance adjustment device  340  as shown in  FIG. 9  and  FIG. 10  is utilized to adjust the adjustable first distance “g a ” to 0.998668 mm, that is equal to the ideal first distance “g i ”. Therefore the observer obtains the stereoscopic images at said viewing distance. In another exemplar as shown in  FIG. 8 , when the detected second distance “z” is exemplarily 400 mm and the detected third distance “e” is exemplarily 50 mm, the parallax barrier distance adjustment device  340  is utilized to adjust the adjustable first distance “g a ” to 0.798403 mm, that is equal to the ideal first distance “g i ”. Therefore the observer still obtains stereoscopic images at said viewing distance. 
     Please refer to  FIG. 9  and  FIG. 10 , the parallax barrier distance adjustment device  340  of the stereoscopic display device  300  can be a telescoping tube  342  as shown in  FIG. 9 . When setting up the stereoscopic display device  300 , the working staff adjusts the telescoping tube  342  to make the adjustable first distance “g a ” equal to the ideal first distance “g i ” that is obtained by the detection-and-calculation device  330 . Furthermore, the barrier distance adjustment device  340  can include a stepping motor  344  and a track  346  with the parallax barrier  320  connected to the stepping motor  344  and positioned on the track  346  as shown in  FIG. 10 . Every time when the stereoscopic display device  300  is turned on, the second distance “z” and the third distance “e” are detected by the detection-and-calculation device  330  and thus the ideal first distance “g i ” is obtained. Consequently, the stepping motor  344  is used to adjust the parallax barrier  320  positioned on the track  346  to make the adjustable first distance “g a ” between the parallax barrier  320  and the display panel  310  equal to the ideal first distance “g i ”. Accordingly, the observer always obtains stereoscopic images in different second distances “z”. 
     According to the stereoscopic image displaying method and the stereoscopic display device of the second preferred embodiment, different viewing distances are obtained by adjusting the adjustable first distance “g a ”: when the observer increases or reduces the real viewing distance, the detection-and-calculation device  330  of the stereoscopic display device of the present invention is utilized to detect the second distance “z” (the real viewing distance) between the observer and the display panel  310 , and thus an ideal first distance “g i ” is obtained. Subsequently, the parallax barrier adjustment device  340  is used to adjust the adjustable first distance “g a ” to be equal to the ideal first distance “g i ”. Briefly speaking, when the observer increases or reduces the real viewing distance, the stereoscopic image displaying method and the stereoscopic display device of the first preferred embodiment still provides 3D stereoscopic images of high quality. Briefly speaking, when the observer increases or reduces the real viewing distance, the stereoscopic image displaying method and the stereoscopic display device of the second preferred embodiment always provides 3D stereoscopic images of high quality by providing a proper adjustable first distance “g a ” suited for the real viewing distance. 
     According to the stereoscopic image displaying method and the stereoscopic display device provided by the present invention, different viewing distances are obtained by providing barrier regions having different barrier pitches or by providing different distances between the parallax barrier and the display panel. Therefore, when the observer increases or reduces the real viewing distance, the stereoscopic image displaying method and the stereoscopic display device provided by the present invention always provide 3D stereoscopic images of high quality. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.