Abstract:
A display device for showing 3D images includes a backlight module and a display section. The backlight module includes n light source units. The display unit section includes n display sections. Upon conditions that a first through kth display section are scanned to receive an image in an current frame, a (k+1)th through an nth display section receives an image in a previous frame, a first through a kth light source unit generate light, and a (k+1)th through nth light source unit do not generate light, the first through the kth display sections display according to the image in the current frame and the light from the first through the kth light source unit, while the (k+1)th display section through the nth display section do not display the image in the previous frame due to the (k+1)th light source unit through the nth light source unit not generating light.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a display device for showing three dimensional (3D) images and a display method, and more particularly, to a display device for improving crosstalk affecting image quality and a display method adopting the device. 
     2. Description of the Prior Art 
     Human beings see real-world images using both eyes. Further, the human brain forms so-called 3D images (three-dimensional images) according to differences in spatial distance between two views seen by both eyes from two different angles. A so-called 3D display is designed to create simulations of human visual fields from different angles to help users perceive 3D images when viewing 2D images. 
     With the development of liquid crystal display technology, 3D display technology makes a progress, too. 3D display technology is classified into glasses-type 3D displays and auto-stereoscopic 3D displays. Glasses-type 3D display technology indicates that users wear specially-made glasses to view 3D images. This kind of technology is a bit harder to promote widely since it requires the users to spend extra money to buy the specially-made glasses. It also makes the users feel less comfortable since the users need to wear the specially-made glasses to view 3D images. As for the auto-stereoscopic 3D display technology, the users can view 3D images without any help of specially-made glasses or other extra equipment. Compared with the glasses-type 3D display technology, the auto-stereoscopic 3D display technology is much more welcomed by the users or businessmen. 
     Please refer to  FIG. 1 .  FIG. 1  is a schematic diagram of the status of all pixels while a conventional auto-stereoscopic 3D display device  10  is on display. The display device  10  comprises a liquid crystal panel  12  and a grating sheet  14 . The liquid crystal panel  12  comprises a pixel matrix. A light-transmitting stripe  14  and a light-shading stripe  14   b  are formed on the grating sheet  14 . The light-transmitting stripe  14   a  and the light-shading stripe  14   b  are stripe-like. With the use of the above-mentioned grating sheet  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. At this time, the order of the left-eye and right-eye signals labels LR, and the grating sheet  14  operates 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. At this time, the order of the right-eye and left-eye signals labels RL, and the grating sheet  14  operates 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 grating sheet  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, i.e. crosstalk, thereby affecting the 3D image quality. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to propose a display device and a display method. The backlight module is divided into a plurality of light source units. The backlight module and the display panel are scanned simultaneously. After a display section of the display panel is scanned, the light source unit which the scanned display section corresponds to illuminates and the light source units which other wait-to-be-scanned display sections correspond to do not illuminate. This design helps improve 3D image crosstalk and enhance 3D image quality. 
     According to the present invention, a display device for showing three dimensional (3D) images, comprises: a backlight module, comprising a first light source unit and a second light source unit, for producing light; and a display unit section, comprising a first display section and a second display section, the first display section overlapping with an illuminating range of the first light source unit, and the second display section overlapping with an illuminating range of the second light source unit. Upon conditions that the first display section is scanned to receive an image in a current frame, the second display section receives an image in a previous frame, the first light source unit generates light, and the second light source unit does not generate light, the first display section displays according to the image in the current frame and the light from the first light source unit, while the second display section does not display the image in the previous frame due to the second light source not generating light. Upon conditions that the first display section and the second display section are scanned to receive the image in the current frame, and the first light source unit and the second light source unit generate light, the first display section and the second display section display according to the image in the current frame and the light from the first light source unit and the second light source. 
     In one aspect of the present invention, the first display section and the second display section share half an area of the display unit section, respectively. 
     In another aspect of the present invention, the illuminating range of the first light source unit and the illuminating range of the second light source unit share half the area of the display unit section, respectively. 
     In still another aspect of the present invention, the display unit section, further comprises a third display section. Upon conditions that the first display section is scanned to receive the image in the current frame, the second display section and the third display section receive the image in the previous frame, the first light source unit generates light, and the second light source unit does not generate light, the first display section displays according to the image in the current frame and the light from the first light source unit, while the second display section and the third display section does not display the image in the previous frame due to the second light source not generating light. Upon conditions that the first display section and the second display section are scanned to receive the image in the current frame, the third display section receives the image in the previous frame, the first light source unit generates light, and the second light source unit does not generate light, the first display section and the second display section display according to the image in the current frame and the light from the first light source unit, while the second display section and the third display section does not display the image in the previous frame due to the second light source not generating light. Upon conditions that the first display section, the second display section and the third display section are scanned to receive the image in the current frame, and the first light source unit and the second light source unit generate light, the first display section, the second display section display and the third display section display according to the image in the current frame and the light from the first light source unit and the second light source. 
     In yet another aspect of the present invention, the first display section, the second display section, and the third display section share one third of the area of the display unit section, respectively. 
     According to the present invention, a method of showing three dimensional (3D) images by using a display device is provided. The display device comprises: a backlight module and a display section, the backlight module comprising a first light source unit and a second light source unit, and the display unit section comprising a first display section and a second display section. The method comprises: Upon conditions that the first display section is scanned to receive an image in a current frame, the second display section receives an image in a previous frame, the first light source unit generates light, and the second light source unit does not generate light, the first display section displays according to the image in the current frame and the light from the first light source unit, while the second display section does not display the image in the previous frame due to the second light source not generating light; upon conditions that the first display section and the second display section are scanned to receive the image in the current frame, and the first light source unit and the second light source unit generate light, the first display section and the second display section display according to the image in the current frame and the light from the first light source unit and the second light source. 
     In one aspect of the present invention, the first display section and the second display section share half an area of the display unit section, respectively. 
     In another aspect of the present invention, the display unit section further comprises a third display section, and wherein the method further comprises: upon conditions that the first display section is scanned to receive the image in the current frame, the second display section and the third display section receive the image in the previous frame, the first light source unit generates light, and the second light source unit does not generate light, the first display section displays according to the image in the current frame and the light from the first light source unit, while the second display section and the third display section does not display the image in the previous frame due to the second light source not generating light; upon conditions that the first display section and the second display section are scanned to receive the image in the current frame, the third display section receives the image in the previous frame, the first light source unit generates light, and the second light source unit does not generate light, the first display section and the second display section display according to the image in the current frame and the light from the first light source unit, while the second display section and the third display section does not display the image in the previous frame due to the second light source not generating light; upon conditions that the first display section, the second display section and the third display section are scanned to receive the image in the current frame, and the first light source unit and the second light source unit generate light, the first display section, the second display section display and the third display section display according to the image in the current frame and the light from the first light source unit and the second light source. 
     According to the present invention, a display device for showing 3D images comprises: a backlight module, comprising n light source units, each of the n light source units for producing light, and n being a positive integer; and a display unit section, comprising n display sections and each of the n display sections overlapping with an illuminating range of one of the light source units. Upon conditions that a first display section through a kth display section are scanned to receive an image in an current frame, a (k+1)th display section through an nth display section receives an image in a previous frame, a first light source unit through a kth light source unit generate light, and a (k+1)th light source unit through an nth light source unit do not generate light, the first display section through the kth display section display according to the image in the current frame and the light from the first light source unit through the kth light source unit, while the (k+1)th display section through the nth display section do not display the image in the previous frame due to the (k+1)th light source unit through the nth light source unit not generating light, where k is less than n, and is a positive integer. 
     In one aspect of the present invention, the area of each of the n display sections is equal. 
     Compared with the conventional technology, the present invention provides a display device where the backlight module is divided into a plurality of light source units and where the backlight module and the display panel are scanned simultaneously. Whenever a display section of the display panel finishes being scanned, the light source unit which the scanned display section corresponds to illuminates and the light source units which other wait-to-be-scanned display sections correspond to do not illuminate. In this way, images in subsequent frames will not be viewed at the same time before all of the display sections of the display panel finish being scanned. It helps improve 3D image crosstalk and enhance 3D image quality. 
     These and other features, aspects and advantages of the present disclosure will become understood with reference to the following description, appended claims and accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of the status of all pixels while a conventional auto-stereoscopic 3D display device is on display. 
         FIG. 2  is a schematic diagram of a stereoscopic image display device showing 3D images according to the present invention. 
         FIG. 3  is a diagram of the structure of the grating sheet in  FIG. 2 . 
         FIG. 4  is a schematic diagram showing the display unit section, the grating sheet, and the backlight module in operation according to a first embodiment of the present invention. 
         FIG. 5  is a process flow diagram of the image shown on the display device shown in  FIG. 4 . 
         FIG. 6  is a schematic diagram showing a display unit section, a grating sheet, and a backlight module in operation according to a second embodiment of the present invention. 
         FIG. 7  is a process flow diagram of the image shown on the display device shown in  FIG. 6 . 
         FIG. 8  is a schematic diagram showing a display unit section, a grating sheet, and a backlight module in operation according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. 
     Please refer to  FIG. 2 .  FIG. 2  is a schematic diagram of a stereoscopic image display device  100  showing 3D images according to the present invention. An observer of the stereoscopic image display device  100  can view 3D images. The stereoscopic image display device  100  comprises a backlight module  102 , a controller  104 , a first diffuser  130 , a display unit section  140 , a second diffuser  132 , and a grating sheet  160 . The backlight module  102  is used for producing light. A light emitting diode (LED) or a cold cathode fluorescent lamp (CCFL) can used as the light source of the backlight module  102 . The display unit section  140  can be a liquid crystal panel for showing images. The display unit section  140  comprises a pixel matrix comprising a plurality of pixels. The light produced by the backlight module  102  is emitted to the first diffuser  130 . The polarization axis of the first diffuser  130  is set as 135° according to an observer A&#39;s viewpoint, so the first diffuser  130  has a function of light transmission of the polarization axis about 135° based on the observer A&#39;s viewpoint. The following description is basically according to the observer A&#39;s viewpoint; otherwise, other observers&#39; viewpoint will be notified. The polarization axis of the second diffuser  132  is set as 45° according to the observer A&#39;s viewpoint, so he second diffuser  132  has a function of light transmission of the polarization axis about 45° based on the observer A&#39;s viewpoint. 
     Please refer to  FIG. 3 .  FIG. 3  is a diagram of the structure of the grating sheet  160  in  FIG. 2 . The grating sheet  160  comprises a first electrically conducting layer  164 , a second electrically conducting layer  166 , and a twisted nematic (TN) layer  163  inserted by the first electrically conducting layer  164  and the second electrically conducting layer  166 . The first electrically conducting layer  164  and the second electrically conducting layer  166  are transparent conductive layers. The transparent conductive layers may fabricated from be indium tin oxide (ITO). The first electrically conducting layer  164  comprises a plurality of first transparent electrodes  164   a  and a plurality of second transparent electrodes  164   b . The plurality of first transparent electrodes  164   a  and the plurality of second transparent electrodes  164   b  are in parallel. The plurality of first transparent electrodes  164   a  and the plurality of second transparent electrodes  164   b  are stripe-like. The plurality of first transparent electrodes  164   a  and the plurality of second transparent electrodes  164   b  are alternatively arranged. The plurality of first transparent electrodes  164   a  and the plurality of second transparent electrodes  164   b  correspond to the pixels on the odd column of the display unit section  140  and the pixels on the even column of the display unit section  140 , respectively. The second electrically conducting layer  166  is coupled to a common voltage terminal Vcom. The TN layer  163  comprises a plurality of TN liquid crystal molecules. The TN liquid crystal molecules determines penetration of the light according to the pressure difference between the first transparent electrode  164   a  and the second electrically conducting layer  166  and between the second transparent electrode  164   b  and the second electrically conducting layer  166 . For example, the first transparent electrode  164   a  receives a voltage V (a first turn-on signal) which is larger than the common voltage terminal Vcom and the second transparent electrode  164   b  receives an electric potential (a second turn-off signal) which is equal to the common voltage terminal Vcom. The TN liquid crystal molecules in the TN layer  163  corresponding to the first transparent electrode  164   a  rotate according to the pressure difference between the voltage V imposed on the first transparent electrode  164   a  and the common voltage terminal Vcom imposed on the second electrically conducting layer  166 . At this time, the light emitted by the second diffuser  132  penetrates the first transparent electrode  164   a . Contrarily, the TN liquid crystal molecules in the TN layer  163  corresponding to the second transparent electrode  164   b  do not rotate since the voltage V imposed on the second transparent electrode  164   b  is equal to the common voltage terminal Vcom imposed on the second electrically conducting layer  166 . At this time, the light emitted by the second diffuser  132  penetrates the second transparent electrode  164   b . On the contrary, the first transparent electrode  164   a  receives an electric potential (a first turn-off signal) which is equal to the common voltage terminal Vcom and the second transparent electrode  164   b  receives a voltage V (a second turn-on signal) which is larger than the common voltage terminal Vcom. At this time, the light cannot penetrate the first transparent electrode  164   a , but penetrates the second transparent electrode  164   b . Based on this principle, the first turn-on signal and the second turn-on signal sent by the controller  104  controls the light to penetrate the first transparent electrode  164   a  or the second transparent electrode  164   b . It shows that the grating sheet  160  controls the pixels on the odd column of the display unit section  140  or the pixels on the even column of the display unit section  140  for human being to view images. 
     Please refer to  FIG. 4 .  FIG. 4  is a schematic diagram showing the display unit section  140 , the grating sheet  160 , and the backlight module  102  in operation according to a first embodiment of the present invention. The display unit section  140  is scanned row by row along a direction as an arrow B shows until the final row finishes being scanned. The period of scanning time is called a frame rate. Afterwards, scanning continues again from the first row. In this embodiment of the present invention, the frame rate is set as 120 Hz for demonstration. In reality, the frame rate is not restricted. The backlight module  102  comprises the first light source unit  110  and the second light source unit  120 . Preferably, the first light source unit  110  and the second light source unit  120  share half the illuminating area of the backlight module  102 , respectively. The display unit section  140  comprises the first display section  141  and the second display section  142 . Preferably, the first display section  141  and the second display section  142  share half the area of the display unit section  140 , respectively. 
     Please refer to  FIG. 4  and  FIG. 5 .  FIG. 5  is a process flow diagram of the image shown on the display device shown in  FIG. 4 . In Step  502 , the display unit section  140  finishes being scanned halfway. Meanwhile, the first display section  141  receives the image in the Nth frame. The second display section  142  receives the image in the (N−1)th frame as usual. The first light source unit  110  receives the first lighting signal and produces the first light. The first display section  141  shows the image according to the first light. At the same time, the second light source unit  120  does not receive the second lighting signal and does not illumine Although the second display section  142  receives the image in the (N−1)th frame, the image shown on the second display section  142  cannot be seen by the observer because of lack of light. 
     In Step  504 , the first display section  141  and the second display section  142  receive an image in the Nth frame. Meanwhile, the first light source unit  110  receives a first lighting signal for producing a first light. The second light source unit  120  receives a second lighting signal for producing a second light. The first display section  141  and the second display section  142  show the image in the Nth frame according to the first light and the second light. 
     In Step  506 , all of the light source units  110  and  120  are turned off. 
     The controller  104  is used for outputting every signal for the image in each frame, the first lighting signal, and the second lighting signal precisely. In this way, resolution will not decrease when the observer views the image shown on the display unit section  140 . Besides, images with different frames will not be shown on the display unit section  140  at the same time. 
     Please refer to  FIG. 6 .  FIG. 6  is a schematic diagram showing a display unit section  140 , a grating sheet  160 , and a backlight module  102  in operation according to a second embodiment of the present invention. Differing from the first embodiment as  FIG. 4  shows, the display unit section  140  in the second embodiment comprises a first display section  141 , a second display section  142 , and a third display section  143 . Preferably, the first display section  141 , the second display section  142 , and the third display section  143  share one third of the area of the display unit section  140 , respectively. 
     Please refer to  FIG. 6  and  FIG. 7 .  FIG. 7  is a process flow diagram of the image shown on the display device shown in  FIG. 6 . In Step  702 , the first display section  141  is scanned. Meanwhile, the first display section  141  receives the image in the Nth frame. The second display section  142  and the third display section  143  receive the image in the (N−1)th frame as usual. The first light source unit  110  receives the first lighting signal and produces the first light. The first display section  141  shows the image in the Nth frame according to the first light. At the same time, the second light source unit  120  does not receive the second lighting signal and does not illumine Although the second display section  142  and the third display section  143  receive the image in the (N−1)th frame, the image shown on the second display section  142  and the third display section  143  cannot be seen by the observer because of lack of light. 
     In Step  704 , the first display section  141  and the second display section  142  receives an image in the Nth frame after the first display section  141  and the second display section  142  finish being scanned subsequently. The third display section  143  receives an image in the (N−1)th frame as usual. Meanwhile, the first light source unit  110  receives a first lighting signal for producing a first light. So the first display section  141  and the second display section  142  show the image in the Nth frame according to the first light. In the meanwhile, the second light source unit  120  fails to receive a second lighting signal so the second light source unit  120  does not produce the second light. Although the third display section  143  receives the image in the (N−1)th frame, the third display section  143  cannot be seen by the observer because of lack of light. 
     In Step  706 , the first display section  141 , the second display section  142 , and the third display section  143  receive an image in the Nth frame after the first display section  141 , the second display section  142 , and the third display section  143  finish being scanned subsequently. Meanwhile, the first light source unit  110  receives a first lighting signal for producing a first light. The second light source unit  120  receives a second lighting signal for producing a second light. So the first display section  141 , the second display section  142 , and the third display section  143  show the image in the Nth frame according to the first light and the second light. 
     In Step  708 , all of the light source units  110  and  120  are turned off. 
     The controller  104  is used for outputting every signal for the image in each frame, the first lighting signal, and the second lighting signal precisely. In this way, resolution will not decrease when the observer views the image shown on the display unit section  140 . Besides, images with different frames will not be shown on the display unit section  140  at the same time. 
     Please refer to  FIG. 8 .  FIG. 8  is a schematic diagram showing a display unit section  140 , a grating sheet  160 , and a backlight module  102  in operation according to a third embodiment of the present invention. The display unit section  140  is scanned row by row along a direction as an arrow B shows until the final row finishes being scanned. The period of scanning time is called a frame rate. Afterwards, scanning continues again from the first row. The backlight module  102  comprises n light source units  110 - 1 ˜ 110 - n  where the n is a positive integer. Preferably, the illuminating range of each of the light source units is equal. The display unit section  140  comprises n display sections  141 - 1 ˜ 141 - n . Preferably, each of the display sections comprises equal display units, and each of the display sections overlaps the illuminating range of one of the light source units. 
     Whenever a display section finishes being scanned, the light source which the display section corresponds to is turned on simultaneously. The scanning continues until the display unit section  140  finishes being scanned. In other words, the first display section  141 - 1  to the kth display section  141 - k  are scanned and then receive the image in the Nth frame. While the (k+1)th display section  141 - k+ 1 to the nth display section  141 - n  receive the image in the (N−1)th frame, the first light source unit  110 - 1  to the kth light source unit  110 - k  produce light and the (k+1)th light source unit  110 - k+ 1 to the nth light source unit  110 - n  do not produce light. The first display section  141 - 1  to the kth display section  141 - k  show the image in the Nth frame according to the signal of the image in the Nth frame and the light produced by the first light source unit  110 - 1  to the kth light source unit  110 - k . The (k+1)th display section  141 - k+ 1 to the nth display section  140 - n  do not show the image in the (N−1)th frame since the (k+1)th light source unit  110 - k+ 1 to the nth light source unit  110 - n  do not produce light. After each of the display section shows the image in the Nth frame, all of the light source units will be turned off. After the first display section receives the image in the (N+1)th frame and the first light source unit  110 - 1  is turned on again, all of the light source units will be turned on. 
     The display device provided by the present invention is capable of showing different images simultaneously. In other words, the display device provided by the present invention can be used as a stereoscopic image display device which adopts binocular parallax or a display device which adopts right and left display images for the observers to view different images. More specifically, the display device provided by the present invention can serve liquid crystal televisions, liquid crystal displays (LCDs), plasma display panels (PDPs), projectors, notebook computers, medical display devices, global positioning system (GPS) display devices, etc. 
     Compared with the conventional technology, the present invention provides a display device where the backlight module is divided into a plurality of light source units and where the backlight module and the display panel are scanned simultaneously. Whenever a display section of the display panel finishes being scanned, the light source unit which the scanned display section corresponds to illuminates and the light source units which other wait-to-be-scanned display sections correspond to do not illuminate. In this way, images in subsequent frames will not be viewed at the same time before all of the display sections of the display panel finish being scanned. It helps improve 3D image crosstalk and enhance 3D image quality. 
     While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.