Abstract:
A first display zone and a second display zone are displayed based on a first light source group, which corresponds to a first voltage data signal; and then the second display zone and a third display zone are displayed based on light for a second light source group, which corresponding to a second voltage data signal. The first light source group and the second light source group illuminate the display zones alternatively. Each display zone is fed with either a first data voltage signal or a second data voltage signal. While the first data voltage signal is updating each display zone in sequence, the second data voltage signal starts updating the first display zone when the first voltage signal is updating the third display zone.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of, and claims priority benefit of, application Ser. No. 12/884,170 filed on Sep. 16, 2010, which is based upon and claims the benefit of priority from the prior Taiwan Patent Application No. 098144605 filed on Dec. 23, 2009. The entirety of each of the above-mentioned patent applications is hereby fully incorporated herein by reference and made a part of this specification. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a stereoscopic display, and more particularly, to a time-sequential stereoscopic display. 
         [0004]    2. Description of Prior Art 
         [0005]    Human beings see real-world images using both eyes. Further, the human brain forms three-dimensional (3D) images according to differences in spatial distance between two views seen by both eyes from two different angles. A 3D display is designed to create simulations of human visual fields from different angles to help users perceive 3D images when viewing two-dimensional (2D) images. 
         [0006]    Currently, 3D displays are divided into two categories. One is auto-stereoscopic displays; the other is stereoscopic displays. Users of auto-stereoscopic displays are able to view 3D images without wearing glasses with a unique structure while ones of stereoscopic displays have to wear specially designed glasses to view 3D images. 
         [0007]    The principle of a 3D display of parallax barrier patterns inside auto-stereoscopic displays is that, based on an opaque parallax barrier, users of auto-stereoscopic displays are able to view parallax images with both eyes, and such a parallax produces the third dimension in the brain. The principle of a spatial sequential 3D display is that a time-irrelevant parallax barrier is employed to let both eyes see two different groups of pixels, and the two groups of pixels are provided with signals from the left and right eyes, respectively, so both eyes can view different images. But, the drawback is that the resolution declines to one-half of the original resolution. The principle of a time sequential 3D display is that a time-manipulating and synchronously-driven-with-display-panel parallax barrier is employed to let both eyes see the same group of pixels at different time points. This group of pixels is supplied with signals of left and right eyes at different time points, respectively, to let each eye view different images. However, considering that a single human eye must receive signals of 60 Hz to avoid perceiving flicker, a time sequential 3D display usually requires a frame rate of at least 120 Hz. 
         [0008]    Referring to  FIG. 1  showing a schematic diagram of a time sequential 3D display device  10 , the display device  10  comprises a liquid crystal panel  12  and a barrier  14 . The liquid crystal panel  12  comprises a pixel matrix. The barrier  14  has multiple stripe openings  14  ( a ) thereon. With the use of the above-mentioned barrier  14 , left-eye and right-eye images are separated, and then the separated images are reflected into a viewer&#39;s left eye L and right eye R, respectively. At frame N, pixels of odd columns are displayed based on left-eye signals, while pixels of even columns are displayed based on right-eye signals, and the barrier  14  is deemed to operate in “LR mode”. While at frame N+1, pixels of odd columns are displayed based on right-eye signals, while pixels of even columns are displayed based on left-eye signals, and the barrier  14  is deemed to operate in “RL mode”. Because the liquid crystal panel  12  adopts a row-by-row scanning, column numbers distributed by left- and right-eye signals on the upper part of the liquid crystal panel  12  are different from those distributed on the lower part when the frame of the liquid crystal panel  12  is updated medially. Take  FIG. 1  for example, signals received by pixels on the upper part of the liquid crystal panel  12  are in RL mode while signals received by pixels on the lower part are in LR mode. However, if the barrier  14  as a disparity barrier is in motion at the same time, the human eye will receive mixed left- and right-eye signals in the end. 
         [0009]    There are two approaches to avoid the above-mentioned problem: one is black frame insertion (BFI) and the other is dynamically switching the backlight module. The BFI approach proceeds as follows: After a frame where images are displayed according to odd columns with right-eye signals and even columns with left-eye signals is shown, insert a black frame and then another frame where images are displayed according to odd columns with left-eye signals and even columns with right-eye signals. Repetitively, insert a black frame and then another frame where images are displayed according to odd columns with right-eye signals and even columns with left-eye signals. As for dynamicly switching the backlight module, the method is as follows: when a liquid crystal panel is scanning, the backlight module is turned off. Then the frame will hold its state for a while after finished being scanned, the backlight module will be turned on at this time. Then the liquid crystal panel will continue scanning the next frame, and the backlight module is turned off again. Unfortunately, the two approaches share a common problem; that is, a refresh rate higher than 120 Hz is required (e.g., 240 Hz is needed for the BFI method) in order to permit the human eye receive frames at 60 Hz. This will produce additional power consumption and increase design complexity. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    It is therefore an object of the present invention to provide a three-dimensional display device where a liquid crystal panel includes at least three display zones and two light sources. Each display zone displays images in different time sequences according to different light sources in order to solve the problem described above. 
         [0011]    According to the present invention, a stereoscopic display for showing a 3D image, comprises: a first light source group for generating first light in response to a first enabling signal; a second light source group for generating second light in response to a second enabling signal; a display unit comprising a first display zone, a second display zone, and a third display zone, each display zone for showing an image in response to a first data voltage signal or a second data voltage signal, based on the first light or the second light; and a barrier comprising a first shielding unit and a second shielding unit, the first shielding unit enabling in response to a first shielding signal and the second shielding unit enabling in response to a second shielding signal. The first and second display zones show the image based on the first light when all the following conditions occur: the first display zone and the second display zone receiving the first data voltage signal, the third display zone receiving the second data voltage signal, the first shielding unit enabling in response to the first shielding signal, and the first light source group turning on in response to the first enabling signal to generate the first light. The second and third display zones show the image based on the second light when all the following conditions occur: the first display zone receiving the second data voltage signal, the second display zone and the third display zone receiving the first data voltage signal, the first shielding unit enabling in response to the first shielding signal, and the second light source group turning on in response to the second enabling signal to generate the second light. The first and second display zones show the image based on the first light whenall the following conditions occur: the first display zone and the second display zone receiving the second data voltage signal, the third display zone receiving the first data voltage signal, the second shielding unit enabling in response to the second shielding signal, and the first light source group turning on in response to the first enabling signal to generate the first light. The second and third display zones show the image based on the second light whenall the following conditions occur: the first display zone receiving the first data voltage signal, the second display zone and the third display zone receiving the second data voltage signal, the second shielding unit enabling in response to the second shielding signal, and the second light source group turning on in response to the second enabling signal to generate the second light. 
         [0012]    In one aspect of the present invention, a frequency of the first shielding signal or the second shielding signal or the first enabling signal or the second enabling signal equals one-half of a scan frequency of the stereoscopic display. 
         [0013]    According to the present invention, a method of driving a display to show a 3D image, the display comprising a display unit and a barrier, is provided. The display unit comprises a first display zone and a second display zone. The barrier comprises a first shielding unit and a second shielding unit. The method comprises the steps of: providing a first light source group for generating first light and a second light source group for generating second light; the first display zone shows the image based on the first light when all the following conditions occur: the first display zone receiving the first data voltage signal, the second display zone receiving the second data voltage signal, the first shielding unit enabling in response to a first shielding signal, and the first light source group turning on to generate the first light; the second display zone shows the image based on the second light when all the following conditions occur: the first display zone receiving the second data voltage signal, the second display zone receiving the first data voltage signal, the first shielding unit enabling in response to the first shielding signal, and the second light source group turning on to generate the second light; the first display zone shows the image based on the first light when all the following conditions occur: the first display zone receiving the second data voltage signal, the second display zone receiving the first data voltage signal, the second shielding unit enabling in response to a second shielding signal, and the first light source group turning on to generate the first light; and the second and third display zones show the image based on the second light when all the following conditions occur: the first display zone receiving the first data voltage signal, the second display zone receiving the second data voltage signal, the second shielding unit enabling in response to the second shielding signal, and the second light source group turning on in response to the second enabling signal to generate the second light. 
         [0014]    These and other objects of the claimed invention will become apparent 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 SEVERAL VIEWS OF THE DRAWINGS 
         [0015]      FIG. 1  shows a schematic diagram of a time sequential 3D display device. 
           [0016]      FIG. 2  shows a schematic diagram of a stereoscopic display according to the present invention. 
           [0017]      FIG. 3  shows a structure diagram of the barrier in  FIG. 2 . 
           [0018]      FIG. 4  shows the display unit, the light-shield layer, and the backlight module in motion of the first embodiment of the present invention. 
           [0019]      FIG. 5  is a method flowchart of the present invention. 
           [0020]      FIGS. 6A and 6B  illustrate the display unit, the light-shield layer, and the backlight module in motion of the second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    Referring to  FIG. 2  showing a schematic diagram of a stereoscopic display  100  of the present invention which displays 3D images, users can view 3D stereoscopic images by using the three-dimensional stereoscopic display  100 . The stereoscopic display  100  comprises a backlight module  102 , a synchronizer  104 , a first polarization plate  130 , a display unit  140 , a second polarization plate  132 , a barrier  160 , and a third polarization plate  134 . The backlight module  102  comprises a light emitting diode (LED) or a cold cathode fluorescent lamp (CCFL). The display unit  140  can be an LCD panel, which comprises pixel matrixes consisting of a plurality of pixels. The backlight module  102  produces light, which is irradiated to the first polarization plate  130 . The first polarization plate  130  is set at about 135 degrees to the polarization axis based upon a view of an observer A, so it allows light with a polarization axis of 135 degrees to be transmitted. 
         [0022]    The second polarization plate  132  is set at about 45 degrees to the polarization axis based upon observer A, so it allows light with a polarization axis of 45 degrees to be transmitted. The third polarization plate  134  is disposed on the light-emitting side of the barrier  160 . The third polarization plate  134  is set at about 135 degrees to the polarization axis based upon the observer A, so it allows light with a polarization axis of 135 degrees to be transmitted. 
         [0023]    Referring to  FIG. 3  showing a structure diagram of the barrier  160  in  FIG. 2 , the barrier  160  comprises a light-shield layer  164 , a conductive glass layer  166 , and a twisted nematic (TN) layer  163  therebetween. The light-shield layer  164  forms a first shielding unit  161  and a second shielding unit  162 , both of which are stripe-shaped. The stripe-shaped first shielding unit  161  and second shielding unit  162  substantially correspond to odd and even columns, respectively. The conductive glass layer  166  is an indium tin oxide (ITO) conductive layer, which is coupled to a common voltage Vcom; the first shielding unit  161  and second shielding unit  162  can be enabled/disabled depending on the first or second shielding signals from the synchronizer  104 . For instance, when the first shielding unit  161  receives the first shielding signals whose voltage level V higher than the common voltage Vcom, TN liquid crystal molecules within TN unit layer  163 , corresponding to a relative position of the first shielding unit  161 , rotate according to the voltage difference between voltage level V applied on the first shielding unit  161  and the common voltage Vcom applied on the conductive glass layer  166 . At this time, the first shielding unit  161  is in an “on” state, allowing the light from the second polarization plate  132  transmit. Meanwhile, the voltage applied on the second shielding unit  162  equals the common voltage Vcom applied on the conductive glass layer  166 , therefore the second shielding unit  162  is in an “off” state that blocks light. Conversely, when the first shielding unit  161  receives a signal whose voltage level equals the common voltage Vcom, and the second shielding unit  162  receives a signal whose voltage level V is higher than the common voltage Vcom, the first shielding unit  161  is disabled so that light cannot transmit while the second shielding unit  162  is enabled to let light transmit. Based on the above-mentioned principle, light can be controlled to transmit through the first shielding unit  161  or the second shielding unit  162  according to the first or second shielding signals generated from the synchronizer  104 . In this way, that the barrier  160  controls whether images of pixels in odd or even columns in the display unit  140  are viewed by the human eye. 
         [0024]      FIG. 4  shows the display unit  140 , the light-shield layer  164 , and the backlight module  102  in a sequence of the first embodiment of the present invention. The display unit  140  scans along the direction of arrow B in a row-by-row manner until the last row is finished being scanned. The duration of the scan is called a frame rate. Afterwards, the display unit  140  restarts scanning the first row. The embodiment thereinafter is explained based on a frame rate of 120 Hz, however it is noted that the frame rate of the display unit  140  is not limited to 120 Hz. The backlight module  102  comprises a first light source group  110  and a second light source group  120 . Preferably, each of the first light source group  110  and the second light source group  120  cover one-half of the light-emitting area of the backlight module  102 . The display unit  140  comprises a first display zone  141 , a second display zone  142 , and a third display zone  143 . Preferably, each of the display zones  141 ,  142 , and  143  cover one-third of the display unit  140 . Signals that enable pixels of odd columns to display images according to left-eye signals and pixels of even columns to display images according to right-eye signals are defined as first data voltage signals “LR”. On the contrary, signals that enable pixels of odd columns to display images according to right-eye signals and pixels of even columns to display images according to left-eye signals are defined as second data voltage signals “RL”. 
         [0025]      FIG. 5  is a method flowchart of the present invention. As Step  502  shows, firstly, the first and second display zones  141  and  142  receive first data voltage signals LR, and the third display zone  143  maintains the second data voltage signals RL corresponding to the previous frame when the second display zone  142  is being scanned. At this time, the first shielding unit  161  of the barrier  160  is enabled in response to first shielding signals, and the first light source group  110  emits first light in response to first enabling signals. Thus, the first and second display zones  141  and  142  display images according to the first light. Meanwhile, because the second light source group  120  is turned off, the images displayed by the third display zone  143  cannot be seen. 
         [0026]    Subsequently, as Step  504  shows, when the first display zone  141  receives the second data voltage signals RL, and the second and third display zones  142  and  143  receive first data voltage signals LR, the first shielding unit  161  is enabled in response to the first shielding signals, and the second light source group  120  produces a second light in response to the second enabling signals. Thus, the second and third display zones  142  and  143  display images according to the second light. Meanwhile, because the first light source group  110  is turned off, the images displayed by the first display zone  141  cannot be seen. 
         [0027]    Afterwards, as Step  506  shows, when the first and second display zones  141  and  142  receive second data the voltage signals RL, and the third display zone  143  receives first data voltage signals LR, the second shielding unit  162  is enabled in response to the second shielding signals, and the first light source group  110  produces a first light in response to the first enabling signals. Thus, the first and second display zones  141  and  142  display images according to the first light. Meanwhile, because the second light source group  120  is turned off, the images displayed by the third display zone  143  cannot be seen. 
         [0028]    Finally, as Step  508  shows, when the first display zone  141  receives the first data voltage signals LR, and the second and third display zones  142  and  143  receive second data voltage signals RL, the second shielding unit  162  is enabled in response to the second shielding signals, and the second light source group  120  produces a second light in response to the second enabling signals. Thus, the second and third display zones  142  and  143  display images according to the second light. Meanwhile, because the first light source group  110  is turned off, the images displayed by the first display zone  141  cannot be seen. 
         [0029]    It is noted that the frequency of the second enabling signals and the first enabling signals equals the scan frequency of the display and the frequency of the first shielding signals, and the second shielding signals equals half of the scan frequency of the display. For example, if the scan frequency of the display is 120 Hz, then that of the first and second shielding signals is 60 Hz and the second and first enabling signals is 120 Hz. The synchronizer  104  synchronously outputs the first and second shielding signals and the second and first enabling signals. In this way, resolution will not decrease and different data voltage signals will not be shown simultaneously in the display unit  140  when an observer views images displayed by the display unit  140 . 
         [0030]      FIGS. 6A and 6B  illustrate the display unit  140 , the light-shield layer  164 , and the backlight module  102  in the sequence of the second embodiment of the present invention. The display unit  140  scans along the direction of arrow B in a row-by-row manner until the last row is finished being scanned. The duration of the scan is called a frame rate. Afterwards, the display unit  140  restarts scanning the first row. The embodiment thereinafter is explained based on a frame rate of 120 Hz, however it is noted that the frame rate of the display unit  140  is not limited to 120 Hz. The backlight module  102  comprises a first light source group  110 , a second light source group  120 , a third light source group  112 , and a fourth light source group  122 . Preferably, each of the first light source group  110 , the second light source group  120 , the third light source group  112 , and the fourth light source group  122  covers one-fourth of the light-emitting area of the backlight module  102 . The display unit  140  comprises a first display zone  141 , a second display zone  142 , a third display zone  143 , and a fourth display zone  144 . Preferably, each display zones  141 ,  142 ,  143 , and  144  cover one-fourth of the display unit  140 . Signals that enable pixels of odd columns to display images according to left-eye signals and pixels of even columns to display images according to right-eye signals are defined as first data voltage signals “LR”. On the contrary, signals that enable pixels of odd columns to display images according to right-eye signals and pixels of even columns to display images according to left-eye signals are defined as second data voltage signals “RL”. 
         [0031]    As  FIG. 6A  shows, firstly, the first and second display zones  141  and  142  receive the first data voltage signals LR, and the third and fourth display zones  143  and  144 , part of which has not been scanned yet, maintain second data voltage signals RL corresponding to the previous frame when the third display zone  143  was scanned. At this time, the first shielding unit  161  of the barrier  160  is enabled (but the second shielding unit  162  is disabled) in response to the first shielding signals, and the first light source group  110  produces first light in response to first enabling signals. Thus, the first display zone  141  displays images according to light of the first light source group  110 . Meanwhile, because the light source groups  112 ,  120 , and  122  are turned off, the images displayed by the second, third, and fourth display zones  142 ,  143 , and  144  cannot be seen. 
         [0032]    Next, the scanning continues downwards. The first, second, and third display zones  141 ,  142 , and  143  receive first data voltage signals LR, and the fourth display zone  144 , part of which has not been scanned, maintains second data voltage signals RL corresponding to the previous frame when the fourth display zone  144  was scanned. At this time, the first shielding unit  161  of the barrier  160  is enabled (but the second shielding unit  162  is disabled) in response to first shielding signals, and the second light source group  120  produces light in response to second enabling signals. Therefore, the second display zone  142  displays images according to light of the second light source group  120 . Meanwhile, because the light source groups  112 ,  120 , and  122  are turned off, the images displayed by the first, third, and fourth display zones  141 ,  143 , and  144  cannot be seen. 
         [0033]    Subsequently, when the first display zone  141  restarts being scanned, the second, third, and fourth display zones  142 ,  143 , and  144  receive first data voltage signals LR, and the first display zone  141  receives second data voltage signals RL. At this time, the first shielding unit  161  of the barrier  160  is enabled (but the second shielding unit  162  is disabled) in response to first shielding signals, and the third light source group  112  produces light in response to third enabling signals. Therefore, the third display zone  143  displays images according to light of the third light source group  112 . Meanwhile, because the light source groups  110 ,  112 , and  122  are turned off, the images displayed by the first, second, and fourth display zones  141 ,  142 , and  144  cannot be seen. 
         [0034]    Afterwards, while the second display zone  142  is scanned, the first display zone  141  receives second data voltage signals RL, the third and fourth display zones  143  and  144  receive first data voltage signals LR, and the first display zone  141  receives second data voltage signals RL. At this time, the first shielding unit  161  of the barrier  160  is enabled (but the second shielding unit  162  is disabled) in response to first shielding signals, and the fourth light source group  122  produces light in response to fourth enabling signals. Therefore, the fourth display zone  144  displays images according to light of the fourth light source group  122 . Meanwhile, because the light source groups  110 ,  112 , and  122  are turned off, the images displayed by the first, second, and third display zones  141 ,  142 , and  143  cannot be seen. 
         [0035]    As shown in  FIG. 6B , the first and second display zones  141  and  142  receive the first data voltage signals LR, and the third and fourth display zones  143  and  144 , part of which has not been scanned yet, maintain second data voltage signals RL corresponding to the previous frame when the third display zone  143  was scanned. At this time, the second shielding unit  162  of the barrier  160  is enabled (but the first shielding unit  161  is disabled) in response to the second shielding signals, and the first light source group  110  produces second light in response to the first enabling signals. Thus, the first display zone  141  displays images according to light from the first light source group  110 . Meanwhile, because the light source groups  112 ,  120 , and  122  are turned off, the images displayed by the second, third, and fourth display zones  142 ,  143 , and  144  cannot be seen. 
         [0036]    Next, the scanning continues downwards. The first, second, and third display zones  141 ,  142 , and  143  receive first data voltage signals LR, and the fourth display zone  144 , part of which has not been scanned, maintains second data voltage signals RL corresponding to the previous frame when the fourth display zone  144  was scanned. At this time, the second shielding unit  162  of the barrier  160  is enabled (but the first shielding unit  161  is disabled) in response to the second shielding signals, and the second light source group  120  produces light in response to second enabling signals. Therefore, the second display zone  142  displays images according to the light of the second light source group  120 . Meanwhile, because the light source groups  112 ,  120 , and  122  are disabled, the images displayed by the first, third, and fourth display zones  141 ,  143 , and  144  cannot be seen. 
         [0037]    Subsequently, when the first display zone  141  restarts being scanned, the second, third, and fourth display zones  142 ,  143 , and  144  receive first data voltage signals LR, and the first display zone  141  receives the second data voltage signals RL. At this time, the second shielding unit  162  of the barrier  160  is enabled (but the first shielding unit  161  is disabled) in response to the second shielding signals, and the third light source group  112  produces light in response to third enabling signals. Therefore, the third display zone  143  displays images according to the light from the third light source group  112 . Meanwhile, because the light source groups  110 ,  112 , and  122  are disabled, the images displayed by the first, second, and fourth display zones  141 ,  142 , and  144  cannot be seen. 
         [0038]    Afterwards, while the second display zone  142  is being scanned, the first display zone  141  receives second data voltage signals RL, the third and fourth display zones  143  and  144  receive first data voltage signals LR, and the first display zone  141  receives second data voltage signals RL. At this time, the second shielding unit  162  of the barrier  160  is enabled (but the first shielding unit  161  is disabled) in response to the second shielding signals, and the fourth light source group  122  produces light in response to fourth enabling signals. Therefore, the fourth display zone  144  displays images according to the light from the fourth light source group  122 . Meanwhile, because the light source groups  110 ,  112 , and  122  are disabled, the images displayed by the first, second, and third display zones  141 ,  142 , and  143  cannot be seen. 
         [0039]    It is noted that the frequency of the first shielding signals the second shielding signals is equal to half of the scan frequency of the display. For example, if the scan frequency of the display is 120 Hz, then that of the first and second shielding signals is 60 Hz and the frequency of turning on each light source groups is also 120 Hz. Resolution will not decrease and different data voltage signals will not be shown simultaneously in the display unit  140  when an observer views images displayed by the display unit  140 . Because the brightness distribution constructed by the backlight module  102  at the boundary of every two light source groups lacks a sharp bright-dark contrast, it is gradual. In this way, crosstalk occurs when a light region of the backlight module  102  is very close to a scanned display zone. The benefit of dividing the display unit  140  and backlight module  102  into four display zones is that the distance between a light region of the backlight module  102  and a scanned display zone increases and crosstalk decreases. 
         [0040]    The display of the present invention is one display that can exhibit diverse images simultaneously. For example, it can be utilized in stereoscopic displays that use binocular disparity, or in displays whose observers on the left and right sides of a display frame can view different images, respectively. More specifically, the display of the present invention can be applied to liquid crystal television sets, liquid crystal displays, plasma displays, overhead projectors, notebook computers, personal digital assistances (PDAs), medical displays, GPS automotive displays, and so on. 
         [0041]    Although the present invention has been explained by the embodiments shown in the drawings described above, it should be understood to the ordinary skilled person in the art that the invention is not limited to the embodiments, but rather various changes or modifications thereof are possible without departing from the spirit of the invention. Accordingly, the scope of the invention shall be determined only by the appended claims and their equivalents.