Patent Publication Number: US-2012032930-A1

Title: Dual-view display device and display method thereof

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a display device, and more particularly, to a dual-view display device and a display method thereof. 
     BACKGROUND OF THE INVENTION 
     Generally, a liquid crystal display device is required to provide only one frame of image a time to satisfy users&#39; demands. However, technologies have been become more and more progressive, and the liquid crystal display device is now required to provide plural frames of images at the same time to satisfy users&#39; demands depending on situations. For example, the liquid crystal display device that is widely utilized in a car may display an information image of a global positioning system (GPS) for a driver to see, while at the same time displays a multimedia image for other passengers to watch. The driver and the passengers can respectively observe different images because the driver and the passengers have different viewing angles with respect to the liquid crystal display device. 
     Please refer to  FIG. 1 , which illustrates a conventional dual-view display device  1 . Different observers at different viewing angles with respect to the dual-view display device  1  can see different images being displayed on the conventional dual-view display device  1 . The conventional dual-view display device  1  mainly comprises a backlight module  10 , a liquid crystal display panel  12 , and a barrier substrate  14 . The backlight module  10  is utilized for providing light required by the liquid crystal display panel  12 . The barrier substrate  14  has slits  140  and barriers  142  disposed thereon. After the light passes through the liquid crystal display panel  12 , some of the light will be projected through the slits  140  at a specific angle and some of the light will be blocked by the barriers  142 . As a result, the different observers at different viewing angles can see different images. 
     Furthermore, the image data inputted to the liquid crystal display panel  12  have to be processed. That is, a left image for a left-side observer  70  and a right image for a right-side observer  80  have to be processed as a mixed image in advance. Then, the liquid crystal display panel  12  interlacedly displays the left image for the left-side observer  70  and the right image for the right-side observer  80 . As a result, by the slits  140  and the barriers  142  on the barrier substrate  14 , the left-side observer  70  can only see the left image and the right-side observer  80  can only see the right image. 
     However, there exist the following problems in the conventional dual-view display device  1  as shown in  FIG. 1 . First, since the barrier substrate  14  has to be disposed in front of the liquid crystal display panel  12 , a light transmittance of the conventional dual-view display device  1  will be decreased and therefore affecting the image quality. The disposed barrier substrate  14  also increases power consumption. Second, each of the left image and the right image can only have one half of pixels of the mixed image, and accordingly each of the left image and right image can only have one half of resolution. Third, since the left image and the right image have to be processed into the mixed image, a more complicated design of a system end of the conventional dual-view display device  1  is required. 
     Therefore, there is a need for a solution to the above-mentioned problems in the conventional dual-view display device  1 . 
     SUMMARY OF THE INVENTION 
     To solve the drawbacks of the aforementioned prior art of having a low light transmittance, one half of resolution, and high power consumption, a primary objective of the present invention is to provide a dual-view display device and a display method thereof. 
     To accomplish the above-mentioned invention objective, the dual-view display device according to the present invention comprises a backlight module, an optical film, a liquid crystal display panel, and a main control unit. The backlight module comprises a light guide plate, a left light source disposed at a left side of the light guide plate, and a right light source disposed at a right side of the light guide plate. The optical film is disposed in front of the backlight module for refracting light passing through the light guide plate to a left-side observer and refracting light passing through the light guide plate to a right-side observer. The liquid crystal display panel is disposed in front of the optical film. The main control unit is electrically coupled to the left light source, the right light source, and the liquid crystal display panel. The main control unit transmits an image data to the liquid crystal display panel and controls the left light source and the right light source according to the image data, so as to control the liquid crystal display panel to display an identical image for both the left-side observer and the right-side observer to see, one view image for one of the left-side observer and the right-side observer to see, or dual-view images for the left-side observer and the right-side observer to see, respectively. 
     Further, in the display method of the dual-view display device, the dual-view display device comprises a backlight module, an optical film, a liquid crystal display panel, and a main control unit. The backlight module comprises a light guide plate, a left light source disposed at a left side of the light guide plate, and a right light source disposed at a right side of the light guide plate. The optical film is disposed in front of the backlight module. The liquid crystal display panel is disposed in front of the optical film. The main control unit is electrically coupled to the left light source, the right light source, and the liquid crystal display panel. The display method comprises following steps of: inputting an image data to the main control unit; and the main control unit transmitting the image data to the liquid crystal display panel and controlling the left light source and the right light source according to the image data, so as to control the liquid crystal display panel to display an identical image for both a left-side observer and a right-side observer to see, one view image for one of the left-side observer and the right-side observer to see, or dual-view images for the left-side observer and the right-side observer to see, respectively. 
     Since a barrier substrate is not essential to be disposed in front of the liquid crystal display panel in the dual-view display device and the display method thereof according to the present invention, the problems, such as a low light transmittance, one half of resolution, and high power consumption, do not exist. Further, the main control unit of the present invention controls the turning-on and turning-off of the left light source and the right light source according to the image data, and thereby an identical image, one view image, or dual-view images can be adaptively displayed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a conventional dual-view display device; 
         FIGS. 2 and 3  illustrate a dual-view display device and a control block diagram thereof according to an embodiment of the present invention; 
         FIG. 4  illustrates a second method for inputting the image data; 
         FIG. 5  illustrates waveform diagrams inputted to the dual-view controller by the GPU; 
         FIG. 6  illustrates a third method for inputting the image data; 
         FIG. 7  illustrates timing diagrams of scanning the images and controlling the left light source and the right light source when displaying dual-view images at 120 Hertz; 
         FIGS. 8(   a ) and  8 ( b ) respectively illustrate timing diagrams of scanning the images and controlling the left light source and the right light source only when the right image R or the left image data L is displayed; 
         FIGS. 9(   a ) and  9 ( b ) respectively illustrate timing diagrams of scanning the images and controlling the left light source and the right light source when the one same image is displayed at 120 Hz and 60 Hz; and 
         FIG. 10  illustrates a flow chart of a display method of a dual-view display device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Please refer to  FIGS. 2 and 3 , which illustrate a dual-view display device  2  and a control block diagram thereof according to an embodiment of the present invention. The dual-view display device  2  comprises a backlight module  20 , an optical film  22 , a liquid crystal display panel  24 , and a main control unit  26 . The backlight module  20  comprises a light guide plate  200 , a left light source  202  disposed at a left side of the light guide plate  200 , and a right light source  204  disposed at a right side of the light guide plate  200 . The optical film  22  is disposed in front of the backlight module  20  for refracting light passing through the light guide plate  200  to a left-side observer  70  and a right-side observer  80 . The liquid crystal display panel  24  is disposed in front of the optical film  22 . The main control unit  26  is electrically coupled to the left light source  202 , the right light source  204 , and the liquid crystal display panel  24 . The main control unit  26  transmits an image data to the liquid crystal display panel  24  and controls the left light source  202  and the right light source  204  according to the image data, so as to control the liquid crystal display panel  24  to display an identical image for both the left-side observer  70  and the right-side observer  80  to see, one view image for one of the left-side observer  70  and the right-side observer  80  to see (for example, a left image for the left-side observer  70  to see or a right image for the right-side observer  80  to see), or dual-view images for the left-side observer  70  and the right-side observer  80  to see, respectively. 
     A distance from the liquid crystal display panel  24  to the left-side observer  70  or to the right-side observer  80  is usually at least 50 centimeter (cm). A distance between the left-side observer  70  and the right-side observer  80  is at least 100 cm. It can be known from experiments that a refraction angle between a normal line of the optical film  22  and the light refracted by the optical film  22  to the left-side observer  70  is at least greater than 40 degrees, that is, an angle between the light refracted to the left-side observer  70  and a direction Y is at least greater than 40 degrees. A refraction angle between the normal line of the optical film  22  and the light refracted by the optical film  22  to the right-side observer  80  is at least greater than 40 degrees, that is, an angle between the light refracted to the right-side observer  80  and the direction Y is at least greater than 40 degrees. 
     The main control unit  26  comprises a dual-view controller  260 , a memory  262  being electrically coupled to the dual-view controller  260 , and a light source driver  264  being electrically coupled to the dual-view controller  260 . The image data received by the main control unit  26  comprises a left image data  40  and a right image data  50 . The present invention discloses three methods for inputting the left image data  40  and the right image data  50 . A first method is as shown in  FIG. 3 , the left image data  40  and the right image data  50  are inputted to the dual-view controller  260  in parallel via two graphics processing units (GPUs)  90 ,  92 . The dual-view controller  260  stores the left image data  40  and the right image data  50  in the memory  262 , such as a synchronous dynamic random access memory (SDRAM). Then, the dual-view controller  260  reads the left image data  40  and the right image data  50  and outputs the left image data  40  and the right image data  50  to the liquid crystal display panel  24  in turn. According to the outputs of the dual-view controller  260 , the light source driver  264  controls turning-on and turning-off of the left light source  202  and the right light source  204 , so as to achieve an object of displaying dual-view images. In detail, when the dual-view controller  260  reads the left image data  40  and outputs the left image data  40  to the liquid crystal display panel  24 , the dual-view controller  260  controls the light source driver  264  to turn on the left light source  202  and turn off the right light source  204 . When the dual-view controller  260  reads the right image data  50  and outputs the right image data  50  to the liquid crystal display panel  24 , the dual-view controller  260  controls the light source driver  264  to turn on the right light source  204  and turn off the left light source  202 . 
     Please refer to  FIGS. 2 and 4 .  FIG. 4  illustrates a second method for inputting the image data. The left image data  40  and the right image data  50  are inputted to a GPU  94 , and the GPU  94  sequentially inputs the left image data  40  and the right image data  50  to the dual-view controller  260 . Please refer to  FIG. 5 , which illustrates waveform diagrams inputted to the dual-view controller  260  by the GPU  94 . When a data enable signal DE_ 1  is at a high level, a data signal DATA_ 1  including the left image data  40  and the right image data  50  is regarded as valid. Since both the left image data  40  and the right image data  50  are inputted to the dual-view controller  260  by the GPU  94 , the GPU  94  is required to provide an indication signal L/R_ 1  so that the dual-view controller  260  determines the data signal DATA_ 1  is the left image data  40  or the right image data  50 . For example, when the indication signal L/R_ 1  is at a low level as shown in  FIG. 5 , the data signal DATA_ 1  represents the left image data  40 . When the indication signal L/R_ 1  is at a high level, the data signal DATA_ 1  represents the right image data  50 . After the dual-view controller  260  receives the left image data  40  and the right image data  50  which are sequentially inputted, the following process is the same as the process of the first method. That is, the main controller  260  stores the left image data  40  and the right image data  50  in the memory  262 . Then, the dual-view controller  260  reads the left image data  40  and the right image data  50  and outputs the left image data  40  and the right image data  50  to the liquid crystal display panel  24  in turn. Next, the light source driver  264  controls turning-on and turning-off of the left light source  202  and the right light source  204  according to the outputs of the dual-view controller  260 , so as to achieve an object of displaying dual-view images. When the dual-view controller  260  reads the left image data  40  and outputs the left image data  40  to the liquid crystal display panel  24 , the dual-view controller  260  controls the light source driver  264  to turn on the left light source  202  and turn off the right light source  204 . When the dual-view controller  260  reads the right image data  50  and outputs the right image data  50  to the liquid crystal display panel  24 , the dual-view controller  260  controls the light source driver  264  to turn on the right light source  204  and turn off the left light source  202 . 
     Please refer to  FIGS. 2 and 6 .  FIG. 6  illustrates a third method for inputting the image data.  FIGS. 6 and 4  have the same hardware architecture. A difference is that the left image data  40  and the right image data  50  in  FIG. 4  are sequentially inputted to the GPU  94 , and the left image data  40  and the right image data  50  in  FIG. 6  are mixed and encoded into a package  60  then inputted to the GPU  94 . Next, the package is inputted to the dual-view controller  260  by the GPU  94 . After the dual-view controller  260  receives the package  60 , the dual-view controller  260  decodes the package  60  into the left image data  40  and the right image data  50  and stores the left image data  40  and the right image data  50  in different address areas in the memory  262 . That is, a specific address area is set to store the left image data  40 , and another specific address area is set to store the right image data  50 . Next, the dual-view controller  260  reads the left image data  40  and the right image data  50  and outputs the left image data  40  and the right image data  50  to the liquid crystal display panel  24  in turn. The light source driver  264  controls turning-on and turning-off of the left light source  202  and the right light source  204  according to the outputs of the dual-view controller  260 , so as to achieve an object of displaying dual-view images. In addition, the left image data  40  and the right image data  50  can be compared to control display methods when the dual-view controller  260  decodes the package  60 . When the left image data  40  and the right image data  50  are compared to be the same, the liquid crystal display panel  24  is capable of displaying an identical image for the left-side observer  70  and the right-side observer  80  to see. When only the left image data  40  or the right image data  50  exists, the liquid crystal display panel  24  is capable of displaying one view image for one of the left-side observer  70  and the right-side observer  80  to see. 
     In summary, the present invention discloses three methods for inputting the left image data  40  and the right image  50  such that: the left image data  40  and the right image  50  are inputted in parallel as shown in  FIG. 3 , the left image data  40  and the right image  50  are sequentially inputted as shown in  FIG. 4 , and after the left image data  40  and the right image  50  are mixed and encoded into a package then inputted as shown in  FIG. 6 . The above-mentioned three methods can adaptively display dual-view images for the left-side observer  70  and the right-side observer  80  to see, respectively, one view image for one of the left-side observer  70  and the right-side observer  80  to see (for example, the left image for the left-side observer  70  to see or the right image for the right-side observer  80  to see), or an identical image for both the left-side observer  70  and the right-side observer  80  to see. 
     The first is to display dual-view images for the left-side observer  70  and the right-side observer  80  to see, respectively. Please refer to  FIG. 7 , which illustrates timing diagrams of scanning the images and controlling the left light source  202  and the right light source  204  when displaying dual-view images at 120 Hertz (Hz). Arrows as shown in  FIG. 7  represent to finish scanning one image. “L” represents the left image, and “R” represents the right image. LEDs-L and LEDs-R respectively represent driving waveforms of the left light source  202  and the right light source  204 . When the architecture as shown in  FIG. 3  is adopted to display the dual-view images, the left image data  40  and the right image data  50  are inputted in parallel by the GPUs  90 ,  92  at 60 Hz. Then the dual-view controller  260  sequentially outputs the left image data  40  and the right image data  50  to the liquid crystal display panel  24  at 120 Hz. When the architecture as shown in  FIG. 4  is adopted to display the dual-view images, the left image data  40  and the right image data  50  are sequentially inputted by the GPU  94  at 120 Hz. Then the dual-view controller  260  sequentially outputs the left image data  40  and the right image data  50  to the liquid crystal display panel  24  at 120 Hz. As shown in  FIG. 7 , the left light source  202  will be turned on after the life image L is scanned and displayed, and the right light source  204  will be turned on after the right image R is scanned and displayed. 
     The second is to display one view image for one of the left-side observer  70  and the right-side observer  80  to see. Please refer to  FIGS. 8(   a ) and  8 ( b ), which respectively illustrate timing diagrams of scanning the images and controlling the left light source  202  and the right light source  204  only when the right image R or the left image data L is displayed. As shown in  FIG. 8(   a ), only when the right image R is displayed for the right-side observer  80  to see, the right light source  204  will be turned on after the right image R is scanned and displayed (i.e. after the data of the right image R are inputted to the liquid crystal display panel  24 ). Since there is no left image L, therefore scanning and displaying the left image L and turning on the left light source  202  are not essential. That is, there has no image displayed between two adjacent right images R. Time between two adjacent right images R having no image displayed is called black time, and the left light source driving waveform is always at a low level, i.e. the left light source  202  is not turned on. On the other hand, as shown in  FIG. 8(   b ), only when the left image L is displayed for the left-side observer  70  to see, the left light source  204  will be turned on after the left image L is scanned and displayed (i.e. after the data of the left image L are inputted to the liquid crystal display panel  24 ). Since there is no right image R, therefore scanning and displaying the right image R and turning on the right light source  204  are not essential. That is, there has no image displayed between two adjacent left images L. The right light source driving waveform is always at a low level, i.e. the right light source  204  is not turned on. 
     The third is to display an identical image for both the left-side observer  70  and the right-side observer  80  to see. Please refer to  FIGS. 9(   a ) and  9 ( b ), which respectively illustrate timing diagrams of scanning the image and controlling the left light source  202  and the right light source  204  when the identical image is displayed at 120 Hz and 60 Hz. Because the image for the left-side observer  70  to see and the right-side observer  80  to see is the same, the data of the identical image is scanned twice with two opposite polarities, that is, an image F 1 (−) is scanned and then an image F 1 (+) is scanned. When the identical image is switched from the image F 1 (+) to an image F 2 (+), the polarities of the image F 1 (+) and the image F 2 (+) remain unchanged. The left light source  202  will be turned on after the image F 1 (−) is scanned and displayed, and the right light source  204  will be turned on after the image F 1 (+) is scanned and displayed. Then, the left light source  202  will be turned on after the image F 2 (+) is scanned and displayed, and the right light source  204  will be turned on after the image F 2 (−) is scanned and displayed.  FIG. 9(   b ) is the timing diagram of scanning the identical image and controlling the left light source  202  and the right light source  204  when the identical image is displayed at 60 Hz. In the timing diagram, a scanning time is extended and a scanning frequency is decreased to 60 Hz, and therefore a charged time can be more sufficient. 
     Please refer to  FIG. 10 , which illustrates a flow chart of a display method of a dual-view display device. The dual-view display device comprises a backlight module, an optical film, a liquid crystal display panel, and a main control unit. The backlight module comprising a light guide plate, a left light source disposed at a left side of the light guide plate, and a right light source disposed at a right side of the light guide plate. The optical film is disposed in front of the backlight module. The liquid crystal display panel is disposed in front of the optical film. The main control unit is electrically coupled to the left light source, the right light source, and the liquid crystal display panel. The display method comprises following steps. 
     In step S 1000 , an image data is inputted to the main control unit. The image data comprises a left image data and a right image data. The left image data and the right image data are inputted to the main control unit in parallel, sequentially inputted to the main control unit, or then inputted to the main control unit after the left image data and the right image data are mixed and encoded into a package. 
     When the left image data and the right image data are sequentially inputted, an indication signal determines which one of the left image data and the right image data is inputted. After the left image data and the right image data are mixed and encoded into the package then inputted, the package is decoded into the left image data and the right image data. Then, the left image data and the right image data are respectively stored in different address areas. Therefore, the left image data and the right image data can be distinguished according to the address areas. Further, the left image data and the right image data can be compared so as to determine an identical image, one view image, or dual-view images is displayed. 
     In step  1100 , the main control unit transmits the image data to the liquid crystal display panel and controls the left light source and the right light source according to the image data, so as to control the liquid crystal display panel to display an identical image for both a left-side observer and a right-side observer to see, one view image for one of the left-side observer and the right-side observer to see (for example, a left image for the left-side observer to see or a right image for the right-side observer to see), or dual-view images for the left-side observer and the right-side observer to see, respectively. 
     Since a barrier substrate is not essential to be disposed in front of the liquid crystal display panel in the dual-view display device and the display method thereof according to the present invention, the problems, such as a low light transmittance, one half of resolution, and high power consumption, do not exist. Further, the main control unit of the present invention controls the turning-on and turning-off of the left light source and the right light source according to the image data, and thereby an identical image, one view image, or dual-view images can be adaptively displayed. 
     While the preferred embodiments of the present invention have been illustrated and described in detail, various modifications and alterations can be made by persons skilled in this art. The embodiment of the present invention is therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications and alterations which maintain the spirit and realm of the present invention are within the scope as defined in the appended claims.