Abstract:
An enhanced liquid crystal display design is provided having relatively fast response time particularly useful in high speed or highly intense applications, such as stereoscopic or autostereoscopic image display. The liquid crystal display device is configured to display stereoscopic images, and comprises an LCD panel and control electronics configured to drive the LCD panel to a desired stereoscopic display state. The control electronics are configured to employ transient phase switching and overdrive the LCD panel to a desired state to enable relatively rapid display of stereoscopic images.

Description:
[0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/933,776, filed Jun. 8, 2007 and entitled “Display Device”, inventors Joseph Chiu, et al., the entirety of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to the art of displays, and more specifically liquid crystal displays. 
         [0004]    2. Description of the Related Art 
         [0005]    Liquid crystal displays are currently readily available. The ability for liquid crystal displays to provide high quality images for complex applications, such as stereoscopic or autostereoscopic applications, is limited by the ability of the display to provide data to pixels in a very short amount of time. Currently available displays in general do not have the response time required to provide a high quality image in stereoscopic applications, and the result is an image that looks less than ideal, particularly when transitioning from dark colors (e.g. black) to light colors (e.g. white) and vice versa. Rapid response time in a liquid crystal display is highly desirable. 
         [0006]    It would therefore be desirable to provide a liquid crystal display having improved functionality over designs previously available, including but not limited to a liquid crystal display that provides faster response time for the display of high quality images such as stereoscopic or autostereoscopic images. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one aspect of the present design, there is provided a liquid crystal display device is configured to display stereoscopic images, and comprises an LCD panel and control electronics configured to drive the LCD panel to a desired stereoscopic display state. The control electronics are configured to employ transient phase switching and overdrive the LCD panel to a desired state to enable relatively rapid display of stereoscopic images. 
         [0008]    These and other advantages of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which: 
           [0010]      FIG. 1  is an ideal representation of a perfect display; 
           [0011]      FIG. 2  illustrates that change in LCD display pixel intensity does not occur instantaneously; 
           [0012]      FIG. 3  shows the change in the pixel intensity in a faster LCD than that shown in  FIG. 2 ; 
           [0013]      FIG. 4  represents the concept of overdriving in a display wherein there is no in-between perceived pixel intensity between the initial state and the final state of the display; 
           [0014]      FIG. 5  illustrates that whether starting from high or low value, in the duration of one frame or one field, the liquid crystal will arrive at a target value; 
           [0015]      FIG. 6  shows an idealized representation of the display operating in a stereoscopic mode; 
           [0016]      FIG. 7  illustrates the shift between left and right eye views showing to the viewer a perceived intensity that shifts from the left eye to the right eye view; 
           [0017]      FIG. 8  shows curves of the liquid crystal response; 
           [0018]      FIG. 9A  shows relative operation of a display and perceived intensity; 
           [0019]      FIG. 9B  illustrates the need for overdriving; 
           [0020]      FIG. 10  shows different values being shown for the left eye and right eye; 
           [0021]      FIG. 11  illustrates that overdrive relies on knowing the starting state of the liquid crystal and the desired perceived pixel intensity for that frame; 
           [0022]      FIG. 12  is a diagrammatic layout of one practical implementation of the design; 
           [0023]      FIGS. 13A and 13B  show the scanned nature of the LCD display; 
           [0024]      FIGS. 14A and 14B  illustrate a segmented backlight, where each segment is controllable; 
           [0025]      FIGS. 15A and 15B  represent a segmented pi cell, where each segment is controllable; 
           [0026]      FIG. 16  illustrates the functional relationship of the processing electronics; and 
           [0027]      FIG. 17  shows the functional diagram of the video processing electronics. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]      FIG. 1  represents the ideal representation of a perfect display. What we show in this drawing is the axis  101  which represents the pixel intensity, and axis  102  which represents time. In this drawing you see the dotted lines  106  and  107 . Those dotted lines describe the frame update intervals. That is, every 16-millisecond interval, as noted by  104 , the display is updated to show a new pixel value. In this figure,  FIG. 1 , we show that during the interval marked by  103  the pixel is of one value, and when the display is updated at time location  107  the pixel will assume a new value shown by the interval  105 . In the ideal world, the pixel will change instantaneously as shown by the vertical slope at  108 . This is an ideal case, where in an ideal “perfect-world” display a pixel will hold one value and as soon as the pixel is updated it will instantaneously go to its new value and maintain that value. 
         [0029]      FIG. 2  shows that in a real-world implementation of liquid crystal devices, the change in the pixel intensity does not occur instantaneously. Similar to  FIG. 1 , two axes are provided with the intensity of the pixel represented on  201  and the time line on  202 . The interval for each display field is 16 milliseconds as indicated by  204 . The dotted lines  206  and  207 , and all the other dotted lines, indicate each moment that the display is refreshed. This example shows one set of pixel values over two frames marked by interval  203 . At time  207  we update the display to try to bring the pixel to a new value, which is the steady state marked by interval  205 . Unlike  FIG. 1 , where in notation  108  the pixel response is instantaneous, in  FIG. 2  at point  208 , the liquid crystal responds much more slowly to reach the final pixel value; and in this case, with  FIG. 2 , a fairly slow panel is shown, and it takes more than one frame period for the pixel to reach the final steady-state value. 
         [0030]      FIG. 3  is similar to  FIG. 2 , but represents a faster liquid crystal device. In  FIG. 3 , again axes  301  and  302  are shown, with axis  301  indicating pixel intensity and axis  302  indicating time. The field interval is 16 milliseconds as indicated by point  304 , and the frame updates are marked again by the vertical dotted lines (for example, at points  306  and  307 ).  FIG. 3  shows that the pixel is at a steady value over the first two frames noted by the interval  303 , and then updated to what will ultimately become the steady-state value noted by interval  305 . The transition period starting at time location  307  and represented by interval  308  shows that the liquid crystal intensity changing in response to the update that occurred at time  307  completes within one frame period. What is shown in this drawing is a representation of a liquid crystal display that can change the pixel value in under one frame rate and settle to a steady-state value. 
         [0031]    However,  FIG. 3  also shows a series of hatched lines  309 ,  310  and  311 , and these hatched lines represent the average value of the liquid crystal during that field duration. During the steady-state interval  303 , the intensity of the liquid crystal is flat, so the average perceived intensity for looking at the pixel during that time at the same location (namely the hatched lines  309 , and the display or the steady-state interval  305 ) show as if it has a similar level pixel intensity, marked by hatched lines  311 . But during the frame, starting at time  307 , when the liquid crystal is going through a transition as indicated by the interval  308 , the average value of the pixel intensity is somewhere between the starting and ending value, represented by the hatched lines  310 . 
         [0032]      FIG. 3  shows an example of what is normally seen as eight millisecond panels. In certain applications that transition value, the perceived pixel intensity  310 , is between the initial intensity  309  and the final intensity  311 . 
         [0033]    Some viewers find “in-between” values visually objectionable.  FIG. 4  represents a display that appears to operate much more quickly, such that there is no in-between perceived pixel intensity between the initial state and the final state of the display. In  FIG. 4 , axes  401  and  402  are shown, with axis  401  representing intensity and axis  402  representing time.  FIG. 4  uses a 16-millisecond frame interval as marked by reference  404 . The initial pixel intensity over the interval  403  is illustrated, and the corresponding perceived pixel intensity is marked by the hatched lines  409 . The vertical lines  407 A,  407 B and  407 C represent the times when the field is being updated, and the hatched lines  411  represent the final value of the display. 
         [0034]    If first displaying a pixel that has the intensity represented by one value is desired, shown as reference  409 , and then the display changes seemingly instantaneously to the new display marked by the hatched lines  411 , the liquid crystal response over the field between time location  407 A and  407 B goes from the low to high value in such a way that the average intensity for that field substantially matches the intended perceived pixel intensity shown by reference  411 . 
         [0035]    So in that first transition, between  407 A and  407 B, the liquid crystal is going through the changing duration marked by the interval  408 A. The liquid crystal then reaches the steady state for the last part of that first field as marked by point  405 A. At this point, however, the pixel intensity created by the liquid crystal is above the desired perceived intensity as marked by  411 , so for the next field between time  407 B and  407 C, in order to again give the appearance of a pixel intensity matching the hatched lines  411 , the pixel is now be driven to a new value such that the average of the pixel intensity during that frame matches that shown at point  411 . The liquid crystal is updated, and the liquid crystal curve is in transition over interval  408 B and reaches steady state  405 B. The average during this frame will again match the perceived intensity target at hatched lines  411 . 
         [0036]    At this point, at the end of this frame, the instantaneous intensity of the liquid crystal is slightly below the desired perceived intensity, so the process repeats using another value to drive the liquid crystal. The liquid crystal goes through a transition again as indicated by the interval  408 C, and then reaches a steady state as indicated by point  405 C.  FIG. 4  thus shows an overdriving technique where, by deliberately steering the liquid crystal to a value either over or above the actual desired target intensity value, the illusion of a much more quickly responding display is formed. The quick response results occurs because the average intensity value, as indicated by the hatched lines  411 , represents the target value and does not appear to create an in-between value as shown in  FIG. 3  by hatched lines  310 . 
         [0037]      FIG. 5  expands on the operation of overdriving in the case where the field rate is 16 milliseconds. Axes  501  and  502  are shown, axis  501  representing the intensity of the pixel by the liquid crystal and axis  502  is the time scale. Interval  504  is a 16 millisecond frame interval.  FIG. 5  shows that the display may start from a high intensity value or a low intensity value. If the pixel in the past was at a high intensity value, the liquid crystal is at position  506 . Starting from a low intensity value begins at position  509 . 
         [0038]    If, in the steady state interval marked by  505 , a mid-level value at the level marked by  507  is desired, the system updates the display such that if the system is starting from a high value  506  and attempting to achieve the midlevel value  507 , the device commands the display to update such that the liquid crystal closely follows curve  508 A. The liquid crystal over the interval of that frame reaches the steady-state value so that by the end of that frame the liquid crystal reaches the steady state indicated by interval  505 . 
         [0039]    In the case where the liquid crystal is driven from below, starting from value  509  and seeking to reach the target value of  507 , the system updates the display with a value appropriate to reach the steady-state value marked as value  507 . The liquid crystal response closely follows the curve  508 B and reaches steady state  505 . 
         [0040]    In either case, whether starting from a high or low value, in the duration of one frame or one field  504 , the liquid crystal arrives at the target value  507 . 
         [0041]    All the design aspects discussed so far have described the pixel response of a liquid crystal display used in planar mode. The present design notably addresses a stereoscopic display, and  FIG. 6  shows an idealized representation of the display operating in a stereoscopic mode. Stereoscopic display in this context requires additional considerations beyond planar applications. Axis  601  represents intensity and axis  602  represents time. In  FIG. 6 , every other field or frame represents switching between left and right eyes, and the frame interval in  FIG. 6  is 8 milliseconds as noted at point  604 . The 8 millisecond frame interval is provided to reduce the appearance of flicker, and flicker reduction can occur using a high enough refresh rate, or a short enough field time. 
         [0042]    In this representation the left and right eye pixel values differ, so there is a high pixel value and a low pixel value. For example, the lower value may be the left eye, and the higher value the right eye. The pixel value is represented at point  609  where, again, the higher value is the right eye and lower value is the left eye. In an ideal situation, a representation of the pixel intensity desired for the left eye is as shown at points  603 A,  603 B and  603 C, whereas the representation of the pixel at the right eye is represented by points  605 A,  605 B and  605 C. In this idealized situation, the pixels change instantaneously, as denoted by points  608 A,  608 B and  608 C. 
         [0043]    As discussed, the liquid crystal response time is not instantaneous. In fact, there is some amount of transition time for the liquid crystal.  FIG. 7  shows that if the shift between the left and right eye views is to be represented, the LC display presents the viewer a perceived intensity that shifts from the left eye to the right eye view, and that perceived intensity is marked by the hatched lines  709 A,  711 A,  709 B and  711 B. In order to achieve the perceived value over each frame interval (the frame interval here is 8 milliseconds as noted by  704 ), the liquid crystal goes through the transition period as marked by  708 A and  708 B such that the average value for each frame yields the hatched lines  709 A and  711 A. 
         [0044]      FIG. 8  shows the curves of the liquid crystal response. Axis  801  is intensity and axis  802  is time. The field is 8 milliseconds long as shown by interval  804 .  FIG. 8  illustrates starting from a high value  806  or from a low value  809  to a target value of  807 . In  FIG. 3 , the period of the liquid crystal transitioning from low to high is marked at point  308 . A similar transition is marked by point  808 B in  FIG. 8 .  FIG. 8  illustrates the transition from a low value to the target value, or from value  809 , which is the low starting point, to the target point  807 . Starting from a high value  806  to the target value  807  results in the liquid crystal substantially following curve  808 A. 
         [0045]    In the case in which the field interval is 16 milliseconds, as in  FIG. 3 , no matter whether the LC starts from a high or a low value, the liquid crystal marked by interval  805  reaches the steady state value  807  within one frame, or 16 milliseconds. 
         [0046]    In  FIG. 8 , if the field or the frame rate is such that the field duration is only 8 milliseconds, starting from point  809  (the low value) and attempting to achieve the target value  807 , at the end of that frame the liquid crystal will not reach the target value or the steady state, and in fact will only reach an intermediate value  811 . If the liquid crystal had started from a high value of  806  and tried to command the display to the target value  807 , at the end of that first frame it would only reach an intermediate value  812 . 
         [0047]      FIG. 9A  has axis  901  representing intensity and axis  902  representing time. Point  904  represents the field rate, or the frame duration here, which is 8 milliseconds. The hatched line  911  represents the desired perceived intensity for one frame. 
         [0048]    Had the frame started from a low value  909 , the system would need to drive the liquid crystal to a target value higher than the desired perceived intensity, shown as higher value  907 B. Driving the liquid crystal from  909  to the target value  907 B, the liquid crystal will substantially follow the curve  908 B. If the system does not have an 8-millisecond interval but instead had allowed the liquid crystal to continue, the liquid crystal would eventually follow the dotted lines  905 A and reach the steady state. 
         [0049]    Had the frame started from a high value  906 , and the average intensity  911  is desired, the system would have to drive the liquid crystal with a target value  907 A, causing the liquid crystal to follow the curve  908 A during the first frame interval. Had operation been allowed to continue, the liquid crystal would follow the dotted line reaching a steady state  905 B. 
         [0050]      FIG. 9A  shows that in order to show a perceived pixel intensity as shown by hatched line  911 , depending on whether the liquid crystal&#39;s actual state is higher or lower, the system needs a different target value to be sent to the display. The different curves being followed, either  908 B or  908 A, over the duration of the first frame average to represent the desired perceived intensity  911 . 
         [0051]      FIG. 9B  expands on  FIG. 9A  (and also  FIG. 4 ) with the idea that if displaying a certain pixel intensity is desired (where, as shown in  FIG. 9B , pixel intensity crossed the hatched line  911 ), the system would need to employ a series of overdriving curves. Axis  901  represents intensity and axis  902  the time.  FIG. 9B  shows that starting from a low value the liquid crystal in the first frame follows curve  908 A. If the liquid crystal were allowed to follow the curve it would have achieved the steady state shown by the dotted line  905 A. 
         [0052]    However, after the first update, the liquid crystal needs to follow a new curve  908 B, which is a curve that is supposed to achieve the steady state of curve  905 B. At the end of the second frame, the system updates the display again such that the liquid crystal follows curve  908 C. Curve  908 C is the transition curve for driving a liquid crystal to what was supposed to be at steady state at point  905 C. 
         [0053]    In  FIGS. 8 ,  9 A and  9 B, the liquid crystal passes through the transition state where the curve has not yet reached equilibrium. At each frame update the liquid crystal moves on to a new curve, and the liquid crystal never gets the opportunity to reach a steady state. 
         [0054]      FIG. 10  returns to the concept that the left eye and the right eye must show different values. In  FIG. 10  axis  1001  is the intensity and axis  1002  which is time.  FIG. 10  represents a stereoscopic still image, where the left eye shows one pixel value and the right eye shows a different pixel value. The left eye value never changes and the right eye value does not change. 
         [0055]    In the still image, the right eye value is represented by the hatched line  1009 A, and the left eye is shown by the hatched lines  1011 A and  1011 B. The liquid crystal starts from intensity  1014 . For the frame to appear as if the perceived intensity is the intensity shown by the hatched line  1009 A, the liquid crystal needs to closely follow the curve  1008 A. In order to have the liquid crystal follow curve  1008 A, the system commands the display to a target value  1014  so that by the end of the frame the liquid crystal reaches intensity  1013 . 
         [0056]    For the left eye value, the desired perceived pixel intensity is as shown by the hatched lines  1011 A, or the intensity at  1012 . In order to achieve this level, the liquid crystal must be overdriven to follow curve  1008 B. This requires the system commanding the display to drive the liquid crystal toward the final value  1015 , and at the end of the second frame, the liquid crystal reaches the intensity value  1014 . 
         [0057]    To then go back to the right eye image requires the liquid crystal to substantially follow curve  1008 C, which can be accomplished by commanding the display to the target value  1014 . Commanding the display in this manner causes the liquid crystal to follow curve  1009 B, and at the end of that frame the liquid crystal reaches intensity value  1003 . The process repeats such that for the right eye, perceived intensity is as shown by hatched line  1009 A and for the left eye, perceived intensity is hatched line  1011 A and  1011 B. 
         [0058]    In  FIG. 11 , the intensity is represented by axis  1101 , time is represented by  1102 . In  FIG. 11 , with a non-still (moving) image, one combination of left and right pixel values over the interval  1103  is shown. However, because the image changes over the interval  1104 , we get a different set of pixel values. On e example is a perceived pixel intensity as indicated by the hatched lines  1109 A,  1109 B,  1109 C, and  1109 D (left eye), and the hatched line perceived pixel intensity value indicated by  1111 A and  1111 B and  1112 A and  1112 B (right eye). During the interval  1103 , the right eye is at pixel intensity as indicated by the hatched lines  1111 A and  1111 B, and in the interval  1104  the perceived pixel intensity is as indicated by  1112 A and  1112 B. 
         [0059]    Similar to  FIG. 10 , during the interval  1103  the liquid crystal is overdriven so that the liquid crystal follows the curves  1108 A,  1108 B,  1108 C,  1108 D and  1108 E. In this manner, the average values again follow the hatched lines  1109 A,  1111 A,  1109 B,  1111 B and  1109 C. When the new right eye perceived pixel intensity is shown for the interval  1104 , the curve that should be followed to achieve the new average value is indicated by the hatched line  1112 A. In order to give the appearance of that level of pixel intensity, the liquid crystal must be driven on a new curve  1108 F, which is different from curves  1108 D and  1108 B. 
         [0060]    This new overdriving results in a new pixel intensity to display. As a result of the overdriving, following the curve  1108 F and achieving the perceived pixel intensity  1112 A, in order to again show the left eye pixel value, the next frame needs to closely follow the curve  1108 G. That curve is different from curves  1108 E,  1108 C or  1108 A, which were used to achieve a similar average intensity. Even though the hatched line  1109 D is at the same perceived pixel intensity as  1109 A,  1109 B and  1109 C, the curve used to achieve point  1109 D (curve  1108 G) differs from the curves used to achieve the perceived intensity for points  1109 A,  1109 B and  1109 C, namely curves  1108 A,  1108 C, and  1108 E. 
         [0061]    Finally, even though the perceived pixel intensity at point  1112 B is the same as at point  1112 A, the liquid crystal is at a different starting point, so the curve  1108 H is different from curve  1112 A. This is again showing that overdriving relies on knowledge of the starting state of the liquid crystal and the desired perceived pixel intensity for the frame. At the end of the frame the liquid crystal is at a different intensity level. 
         [0062]      FIG. 12  shows the diagrammatic layout of a practical implementation of the present design. Three dimensional (3D) images are provided by an external source  1201 . The source  1201  may be in a number of different 3D formats, including sequential frames and canister formats. This source is fed into the processing module  1202 . More than one processing module may be provided. The images are sequenced in the processing module so that left and right eye images alternate. These images are provided sequentially to the TFT panel  1204  where they are displayed by shining a backlight  1203  through the TFT panel  1204 . To separate the left and right eye frames, left and right eye frames are displayed sequentially (at a high frame rate) and the polarization state is changed dynamically by the Pi-cell  1205 , providing opposite circular polarization on left and right frames. The polarization state is analyzed by the polarized eyewear  1206 , sequentially directing left and right images to the corresponding or appropriate eye. 
         [0063]      FIG. 16  provides a description of the functional relationship of the processing electronics. The processing module consists of the control electronics necessary to interpret and manage the incoming images, and control and manage the operation of the display. The block diagram in  FIG. 16  provides a description of the functional relationship of the processing electronics. 
         [0064]      FIG. 16  shows the image input  1601  and optional stereo sync input  1602 , which may provide identification of left and right frames to the video processor board  1603 . The functions within the video processor block are described more fully in  FIG. 17 . A controller  1604  provides the management functions of the display, responds to user interface requests and synchronizes the backlight driver  1607  and pi cell driver  1608  with the image. The backlight driver  1607  controls the timing of switching the backlight segments (see  FIGS. 14A and 14B ). 
         [0065]    The display stack consists of the visual elements of the display. The LED backlight  1609 , controlled by the backlight driver  1607 , provides the illumination to the display in particular in a manner that allows certain rows of the display to be illuminated while others are not. The backlight may be provided by multiple white LEDs (light emitting diodes), triplets of RGB LEDs, or hot cathode fluorescent lamps. The backlight diffuser  1610  serves to provide even illumination to the display panel  1611 . The display panel is usually an active matrix LCD type panel which receives video signals from the video processor. The Pi cell  1612  serves to switch polarization states between left circular and right circular polarization. 
         [0066]    In a preferred embodiment, the LED backlight module  1609  is a PCB approximately 12.5 inches by 15.5 inches in size with 120 LEDs arranged on a grid of 10 rows by 12 columns. The LEDs are spaced approximately 1.1 inches on center. The LEDs in each row are wired in series and are turned on or off as a group independently of the other rows. 
         [0067]    The rows are illuminated in sequence so that a stripe of illumination scans from the top to the bottom. The stripe is made up of one or more rows. 
         [0068]    A diffuser is placed between the display panel and the backlight LEDs to “flatten” the illumination density coming from the backlight. The diffuser also manages the light from the backlight rows to minimize the spill of light onto adjacent rows. 
         [0069]    The pi-cell or pi cell is similar to that described in U.S. Pat. No. 4,792,850, and encodes the display image in one of two polarization states. In one aspect, the pi-cell has 16 segments ( FIG. 15  illustrates the segments). With proper bias and drive voltages, each pi-cell segment either is a ½ wave retarder, or is isotropic. The pi-cell has a fast-axis which is selected to be at 45 degrees to the TFT panel&#39;s linear polarization angle. 
         [0070]    There is a ¼ wave retarder sheet laminated to the pi-cell. The ¼ wave sheet is oriented so that its fast axis is 90 degrees to the pi-cell. A further anti-reflective coating is optionally laminated to the pi cell assembly. Each pi cell segment is addressed individually through connection to the pi cell driver. 
         [0071]      FIG. 17  shows the functional diagram of the Video Processing Electronics. Images to be displayed enter the Fast LCD monitor via an input cable that connects the image source to the monitor. The images can be stereo images in either frame-sequential or in a combined “canister” format, and can also be simultaneous dual-input stereo. The images can also be non-stereo images for non-stereoscopic viewing. 
         [0072]    In addition, there may be a stereo sync signal from the video source to indicate the “eye” of the image currently being output from the video source. 
         [0073]    The system analyzes the video signal to determine its resolution and video timing. If the resolution matches the native resolution of the image display panel, the video timing is compatible with the image display panel, the format is sequential L-R images (page flip) and the refresh rate is sufficiently high for comfortable stereoscopic viewing, the image signal bypasses input buffering shown at point  1701 . 
         [0074]    However, if any of the above conditions is not met, the incoming video is buffered in the input buffers  1702  and then read out in the proper sequence and timing to match the desired operation of the image display panel, and to match the desired output frame rate for comfortable stereoscopic viewing. 
         [0075]    The input buffering allows lower resolution image to be centered to the native resolution of the monitor&#39;s image display panel. For example, if the incoming video is at 1024×768 resolution, the monitor would “pad” the top, bottom, left, and right with additional pixels to fit the image in the monitor&#39;s native 1280×1024 resolution, and would read out the incoming image from the input buffer as needed to draw the image in the center area. 
         [0076]    The input buffering also allows double- or triple-flashing of incoming images. For example, the frame-sequential stereo video could come in at 60 hertz—30 hertz in left eye and 30 hertz in right eye. If this pair of left and right eye images is displayed at the original frame rate, there would be objectionable flicker for the viewer because each eye is presented with a 30 hertz image. In order to reduce the flicker, the frame rate is doubled by displaying the pair of images in half the time period of the original pair, and then the pair is repeated once more. For triple flashing, the pair is displayed in ⅓ rd  the time of the original pair, and then the pair is repeated two more times). 
         [0077]    The input buffering also allows for receiving a stereo image in a single “canister” frame, and then splitting them into separate left and right frames to be processed by later stages. 
         [0078]    The video data that comes out of the INPUT BUFFERING stage (whether by bypassing the INPUT BUFFERING processing, or by performing one or more of padding, double-/triple-flashing, or canister separation) is now formatted in resolution and timing to be suitable for the image display panel, and has timing that is suitable for proper stereoscopic viewing. The “output frame selection”  1703  chooses the correct frame to display, depending on the format selected. 
         [0079]    The intensity of the image is scaled  1704  to prepare the image for future processing. The image data from the video source represents its pixel intensity from black to full intensity using the values 0 to 255, with 0 representing black, 255 representing full intensity, and values in between representing the various shades in between. 
         [0080]    The TFT panel accepts image data with the pixel intensity represented by 8-bit values, with 0 representing black, and 255 representing full intensity, and values in between representing the various shades in between. During standard non-stereoscopic operation, the panel is able to faithfully display a range of intensities represented by the values 0 to 255. 
         [0081]    When the panel is operated in high-frame-rate stereoscopic mode, the useful range of displayed intensities may be limited by the performance limit of the panel. 
         [0082]    For example, for one of the panels currently available and manufactured by LG Electronics, a range of 10 to 236 is used, meaning that the blackest black available on the display has a code value of 10. This range limitation allows for overshoot to be built in to the signal to give faster response. 
         [0083]    It should be noted that the range of values 0 to 255 is for 8-bit representation of image data; other ranges can exist—e.g., 6 bit video representation uses 0 to 63; 12-bit video uses 0 to 4095, and so on. 
         [0084]    The display by its nature has leakage from one eye view to the other. This crosstalk results in ghosting, which is detrimental to providing satisfactory display performance. This ghosting can be predicted and compensation can be performed to minimize its effects. This is performed in the Ghostbusting block  1705 . 
         [0085]    Generally speaking, the ghost busting technique simultaneously evaluates the left and right images of a stereo pair to create a new pair of ghost-compensated images which to be output by the display. For example, the system evaluates the original left image to determine the amount of ghost that the image would introduce into the right view, based on predictive models. This amount of “ghost” is then used to calculate the adjusted right-eye image, which includes the appropriate “anti-ghost” value. To the right eye, when this adjusted image is displayed, the anti-ghost value cancels out the ghost value contributed during the output of the left-eye image. With this cancellation, the right eye of the viewer sees the originally intended right eye view. The same process is used to generate the adjusted left-eye image in order to present the originally intended left eye view. 
         [0086]    The above-described “ghostbusting” scheme operates simultaneously on a pairwise set of original input images to calculate a pairwise set of compensated output images. This simultaneous pair-wise compensation approach works well when both images of the stereo pair can be received simultaneously, but can present a number of shortcomings when processing frame-sequential stereo inputs. 
         [0087]    First, there is a pipeline delay of at least one frame time between the input and the output. This occurs because the image data for both eyes is needed before either eye&#39;s compensated image can be calculated. For each image pair, the first image must be stored until the information from the second image of the pair becomes available. As the second image is received, the calculation can then proceed to generate the compensated first image. 
         [0088]    Second, the pairwise ghostbusting requires at least two image buffers to process each frame-sequential stereo pair. This is because the first image must be held in the buffer until the data for the second image arrives, and the output of the compensated second image must be delayed until the compensated first image has been output. 
         [0089]    Third, the resulting compensated images must be displayed in a pairwise manner because ghost compensation is performed in a pairwise manner. The resulting compensated images are (by definition) calculated to minimize ghosting when both images are output to the display. 
         [0090]    The stereoscopic LCD uses the benefits of ghost compensation, but does it in a process that is more suitable for frame-sequential stereo input. While the pairwise approach works to minimize the ghosting within each stereo pair, the frame-sequential approach works to minimize the ghosting from one output frame to the next. 
         [0091]    The frame-sequential ghost busting scheme eliminates the pipeline delay, reduces the image buffering needed to perform ghost reduction, and reduces ghosting without requiring that the display to always output stereo images in a pairwise manner. When the output is double- or triple-flashed, the compensated images are output in pairs. 
         [0092]    The frame-sequential ghost busting operates as follows. A history buffer (ring buffer/FIFO (first in first out) buffer) contains the output image of the previous frame. As pixel data for the current frame arrive, data for the corresponding pixel from the previous frame are read out from the history buffer. The anti-ghost value needed to compensate for the ghosting by the previous frame is added to the current frame&#39;s pixel value to yield the compensated image value. The compensated image value is output to the display. The compensated image value is also written into the history buffer so that the current frame&#39;s ghost contribution to the next frame can be determined. The anti-ghost calculation can be performed either by explicit calculation, or can be implemented with a lookup table, or both in combination. 
         [0093]    The frame-sequential ghost busting approach offers the several benefits. First the processing pipeline does not require a one frame pipeline delay between the input and the output. Second, only one image buffer is needed to perform the compensation calculation. Third, because the dominant mechanism for ghosting is caused by the residual image from the previous frame, the method is better suited for ghost pre compensation. 
         [0094]    As was discussed with respect to  FIGS. 1 to 8 , the LCD display experiences long switching times relative to the short frame time required for sequential 3D. To assist with the switching time, the pixel drive signal can be overdriven to come to the correct light level in a shorter period of time. The model to characterize the switching speed of the display is complex, and requires that each possible switching transition be characterized. To achieve benefit from this approach, a scheme is developed where the required drive value is predicted to achieve the correct pixel luminance at a given time. 
         [0095]    The predictive model is implemented in either an algorithm or a look up table (or series of tables) and is identified as “pixelbusting”  1706  in  FIG. 17 . Pixel busting and ghost busting may be combined into a single functional block with a look up table that covers both functions. 
         [0096]      FIGS. 13A and 13B  demonstrate the scanned nature of the LCD display. The image on the display is refreshed first at the top of the display, and then sequentially down to the bottom of the display, in lines or small groups of lines. The relationship between the time that a line of the display is activated and the point on the frame time is shown by the line  1303 . 
         [0097]      FIGS. 14A ,  14 B,  15 A, and  15 B illustrate that the backlight  1401  and pi cell  1501  are segmented, with each segment being controllable. This arrangement allows the illumination of the pixel, and the polarization state of the pixel to be timed for optimum performance. As described with respect to  FIGS. 1 to 8 , each individual pixel in the display takes time to come to equilibrium at the desired final drive state. This time is controlled by the luminance level of the previous frame, the desired luminance level and the amount of overdrive applied. By knowing the time when the correct luminance value is achieved, the backlight corresponding to that pixel can be lit at this time. 
         [0098]    A predictive model provides the correct luminance for a given desired luminance value. The model considers the point in time when the pixel is addressed, the pixel value from the previous frame, the desired pixel value, and the display response characteristics. The backlight corresponding to that pixel can be illuminated at a set time, and the ZScreen shutter can be activated at that time. Because all pixels in a given region are affected by a given backlight segment and a corresponding ZScreen segment, the model determines the correct luminance value to occur at the period in time when the backlight is illuminated. 
         [0099]      FIGS. 14A and 14B  illustrate a simplified case of a five segment backlight, while  FIGS. 15A and 15B  illustrate a five segment pi cell. Note that in practice many segments can be used in both the backlight and the pi cell, and that the backlight and pi cell do not necessarily require the same number of segments. In one embodiment, the pi cell has 16 segments and the backlight has 10 segments. 
         [0100]      FIG. 15B  shows the timing relationship for a given pixel. The plot shows time on the x axis  1508  and activation of the elements of the system on the y axis  1509 . 
         [0101]    The pixel is addressed with a pre determined voltage level, and held for the frame duration, as shown at point  1510 . This level is predetermined from the model, using the previous frame value, the desired output luminance value as inputs. The actual luminance response of the pixel is shown at point  1511 . This pixel response demonstrates that reaching equilibrium may take a long time, but that the desired luminance level may be reached earlier given appropriate drive levels. At the point where the luminance level of the pixel is correct, the backlight is illuminated at point  1512 . The period of illumination is a set value representing a fraction of the total frame time. The luminance level of the pixel changes during this time, as shown at point  1514 , but integrates to the desired luminance level. The last step on the display process puts the correct polarization state on the pixel to ensure that it is seen by the desired eye. This is illustrated by the response of the pi cell  1513 . The resulting luminance as seen by the eye is shown in the graph showing perceived average luminance level for the frame  1515 . 
         [0102]    The combination of the LED backlight, the dyes on the LCD cells, the ZScreen and the glasses worn by the viewer introduces some color shift. The color may be corrected through a simple calibration process by measuring the output color on several test screens, and these values are input to the “pixel busting” algorithm, where correction factors are applied to the algorithm to provide the correct color. It may be the case that the color of the left and right eye images is different due to slight imperfections in the polarization states. The correction mechanism will support different calibration factors for left and right eyes. 
         [0103]    Thus the present design includes a liquid crystal display device configured to display stereoscopic images. The liquid crystal display device may include an LCD panel, a backlight positioned behind the LCD panel, and control electronics configured to drive the LCD panel to a desired display state. The control electronics are configured to employ transient phase switching to overdrive the LCD panel to a desired state and facilitate relatively rapid display of stereoscopic images. In certain cases, transient phase switching employs a look up table, and the look up table can be employed to drive or overdrive the LCD panel to a desired state. 
         [0104]    The design presented herein and the specific aspects illustrated are meant not to be limiting, but may include alternate components while still incorporating the teachings and benefits of the invention. While the invention has thus been described in connection with specific embodiments thereof, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses or adaptations of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within known and customary practice within the art to which the invention pertains. 
         [0105]    The foregoing description of specific embodiments reveals the general nature of the disclosure sufficiently that others can, by applying current knowledge, readily modify and/or adapt the system and method for various applications without departing from the general concept. Therefore, such adaptations and modifications are within the meaning and range of equivalents of the disclosed embodiments. The phraseology or terminology employed herein is for the purpose of description and not of limitation.