Abstract:
Disclosed is an image display device for generating input image signals and a method thereof. The image display device includes an outer device connector connected with a digital video interactive (DVI) cable or a high-definition multimedia interface (HDMI) cable, an image signal separator separating an image signal received through the cable into image data, vertical/horizontal synchronizing signals, a data enable (DE) signal, and a pixel clock signal, an image signal processor processing a signal of the image data, and a controller determining the standard of the input image signal and controlling the image signal processor to process the image signal in a mode corresponding to the determined standard. Thus, the input image signal can be processed depending on the determined result after determining the standard of the input image signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit under 35 U.S.C. § 119 from Korean Patent Application No. 2004-106846, filed on Dec. 16, 2004, the entire content of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an image display device for generating input image signals in a best mode and a method thereof, and more particularly to, an image display device for generating input image signals and a method thereof, in which the image signals according to each standard are generated in a best mode by distinguishing an image signal of a video electronics standards association (VESA) standard and an image signal of electronic industry association/consumer electronics association (EIA/CEA861B) standard, which are input to the image display device, from each other.  
         [0004]     2. Description of the Related Art  
         [0005]     Recently, with the increase in popularity of digital image display devices such as an LCD monitor, a digital video interactive (DVI) and a high-definition multimedia interface (HDMI) have received attention with regard to a digital interface between a PC and the image display device and between an HD set-top box and the image display device. Cables for DVI and HDMI are used to transmit the image signal from the PC and the HD set top box to the image display device. In this case, a VESA standard is used to transmit the image signal between the PC and the image display device while an EIA/CEA861B standard is used to transmit the image signal between the HD set-top box and the image display device.  
         [0006]     As described above, since the VESA standard and the EIA/CEA861B standard are together used through the DVI cable and the HDMI cable, a problem may occur in images if the image signal corresponding to the VESA standard and the image signal corresponding to the ELA/CEA861B standard are processed in the same method. In more detail, in the case where the image signal corresponds to the VESA standard, a digital value of 0 to 255 is used for a luminance signal level. In the case where the image signal corresponds to the ELA/CEA861B standard, a digital value of 16 to 235 is used for the luminance signal level. If the image signal corresponding to the VESA standard is input to the image display device which employs the EIA/CEA861B standard, an abnormal phenomenon such as saturation of image occurs.  
       SUMMARY OF THE INVENTION  
       [0007]     Accordingly, the present invention is directed to an image display device for generating input image signals in a best mode and a method thereof, which substantially obviates one or more problems due to limitations and disadvantages of the related art.  
         [0008]     An aspect of the present invention is to provide an image display device for generating input image signals in a best mode and a method thereof, in which the image signals inputted through a digital video interactive (DVI) or a high-definition multimedia interface (HDMI) are generated in a best mode by distinguishing an image signal of a Video Electronics Standards Association (VESA) standard and an image signal of an Electronic Industry Association/Consumer Electronics Association (EIA/CEA861B) standard, which are input to the image display device, from each other.  
         [0009]     To achieve these aspects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, an image display device includes an outer device connector connected with a digital video interactive (DVI) cable or a high-definition multimedia interface (HDMI) cable, an image signal separator separating an image signal received through the cable into image data, vertical/horizontal synchronizing signals, a data enable (DE) signal, and a pixel clock signal, an image signal processor processing a signal of the image data, and a controller determining the standard of the input image signal and controlling the image signal processor to process the image signal in a mode corresponding to the determined standard.  
         [0010]     The controller includes a first determining portion determining the standard of the image signal based on the vertical/horizontal synchronizing signals, the data enable signal, and the pixel clock signal, a second determining portion determining the standard of the image signal based on a signal level of data corresponding to a luminance signal among the image data, and a comparator comparing a first determined result of the first determining portion with a second determined result of the second determining portion.  
         [0011]     The first determining portion includes a resolution determining portion determining resolution based on the vertical/horizontal synchronizing signals, and a standard determining portion determining either the standard of the input image signal based on the number of H-sync periods in a V-sync period of the input image signal if the resolution corresponds to 480p or the standard of the input image signal based on the number of pixel clocks in a H_Front porch period if the resolution corresponds to 720p or 1080i.  
         [0012]     The comparator determines whether the first determined result is equal to the second determined result and controls the image signal processor to process the input image signal in a mode corresponding to the determined standard if the first determined result is equal to the second determined result.  
         [0013]     The comparator transmits a reset signal to the outer device connector to initiate the input image signal and determines again the standard of the initiated input image signal if it determines that the first determined result is different from the second determined result.  
         [0014]     According to the present invention, a method for outputting input image signals of an image display device, comprises receiving an input image signal through at least one cable of a digital video interactive (DVI) cable and a high-definition multimedia interface (HDMI) cable, separating the input image signal into image data, vertical/horizontal synchronizing signals, a data enable (DE) signal, and a pixel clock signal, determining the standard of the input image signal, and processing the input image signal according to the standard and outputting the input image signal.  
         [0015]     The step of determining the standard of the input image signal, may comprise determining the standard of the input image signal based on the vertical/horizontal synchronizing signals, the data enable signal, and the pixel clock signal, and outputting a first determined result, determining the standard of the input image signal based on a signal level of data corresponding to a luminance signal among the image data, and outputting a second determined result, and comparing the first determined result with the second determined result.  
         [0016]     The step of outputting the first determined result may comprise determining a resolution based on the vertical/horizontal synchronizing signals, and determining either the standard of the input image signal based on the number of H-sync periods in a V-sync period of the input image signal if the resolution corresponds to 480p or the standard of the input image signal based on the number of pixel clocks in a H_Front porch period if the resolution corresponds to 720p or 1080i.  
         [0017]     The method may further comprise, if the first determined result is equal to the second determined result, processing the input image signal in a mode corresponding to the determined standard.  
         [0018]     The method may further comprise, if it is determined that the first determined result is different from the second determined result, initiating the input image signal and determining again the standard of the initiated input image signal. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The above aspects and features of the present invention will be more apparent by describing certain embodiments of the present invention with reference to the accompanying drawings, in which:  
         [0020]      FIG. 1  is a block diagram illustrating an image display device according to an exemplary embodiment of the present invention;  
         [0021]      FIG. 2A  illustrates the difference between an image signal corresponding to a VESA standard and an image signal corresponding to an EIA/CEA861B standard in a mode of 480p;  
         [0022]      FIG. 2B  illustrates the difference between an image signal corresponding to a VESA standard and an image signal corresponding to an EIA/CEA861B standard in a mode of 720p;  
         [0023]      FIG. 2C  illustrates the difference between an image signal corresponding to a VESA standard and an image signal corresponding to an EIA/CEA861B standard in a mode of 1080i; and  
         [0024]      FIG. 3  is a flow chart illustrating the operation of an image display device according to an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0025]     Reference will now be made in detail to exemplary embodiments of the present invention, some of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
         [0026]      FIG. 1  is a block diagram illustrating an image display device according to an exemplary embodiment of the present invention.  
         [0027]     Referring to  FIG. 1 , an image display device consistent with the present invention includes an outer device connector  110 , an image signal separator  130 , a controller  150 , an image signal processor  170 , and a display  190 .  
         [0028]     The outer device connector  110  is connected with an outer device (not shown), such as a PC and an HD set-top box, through a DVI cable and an HDMI cable.  
         [0029]     The image signal separator  130  separates an image signal transmitted from the outer device into image data of 24-bit, vertical/horizontal synchronizing signals, a data enable (DE) signal, and a pixel clock signal. The image signal separator  130  transmits the separated values to a controller  150  as described later.  
         [0030]     After receiving the image data of 24-bit, the vertical/horizontal synchronizing signals, the data enable (DE) signal, and the pixel clock signal from the image signal separator  130 , the controller  150  determines the standard of the input image signals. The controller  150  includes a first determining portion  151 , a second determining portion  153 , and a comparator  155 .  
         [0031]     The first determining portion  151  receives the vertical/horizontal synchronizing signals, the data enable (DE) signal, and the pixel clock signal to determine the standard of the input image signals. In other words, a resolution determining portion  151   a  determines whether resolution of the input image signals is 480p, 720p, or 1080i based on the vertical/horizontal synchronizing signals. A standard determining portion  151   b  determines whether the input image signals corresponds to either a VESA standard or an EIA/CEA861B standard based on the vertical/horizontal synchronizing signals, the data enable signal, and the pixel clock signal.  
         [0032]     The image signal corresponding to the VESA standard and the image signal corresponding to the EIA/CEA861B standard have differences depending on resolution as shown in the following Table 1.  
                                                                                         TABLE 1                                       H —         H —     V —         V —                 Reso-   Front   H —     Back   Front   V —     Back   Po-           lution   porch   sync   porch   porch   sync   porch   larity                                    VESA   480p   16T   62T   60T   10H   2H   33H   N/N           720p   70T   40T   260T   5H   5H   20H   N/N           1080i   44T   44T   192T   2H   5H   15H   N/N       EIA/CE   480p   16T   62T   60T   9H   6H   30H   N/N       A 861B   720p   110T   40T   220T   5H   5H   20H   P/P           1080i   88T   44T   148T   2H   5H   15H   P/P                  
 
         [0033]     In Table 1, T represents the number of pixel clocks, and H represents the number of H_sync periods. The standard determining portion  151   b  determines the standard of the input image signals based on the difference between the image signal corresponding to the VESA standard and the image signal corresponding to the EIA/CEA861B standard. The difference between the image signal corresponding to the VESA standard and the image signal corresponding to the EIA/CEA861B standard as shown in Table 1 will be described with reference to  FIG. 2A  to  FIG. 2C .  
         [0034]     The second determining portion 153 receives the image data of 24-bit, compares signal levels of 8-bit data corresponding to a luminance signal among the image data of 24-bit, and determines whether the input image signals correspond to the VESA standard or the ELA/CEA861B standard.  
         [0035]     In other words, a luminance signal corresponding to the VESA standard has a signal level of 0 to 255 while the image signal corresponding to the EIA/CEA861B standard has a signal level of 16 to 235. Therefore, if the luminance signal input during 30 frames has the signal levels of 1 to 8 and 245 to 255, the second determining portion  153  determines the signal level as the VESA standard. If not, the second determining portion  153  determines the signal level as the EIA/CEA861B standard.  
         [0036]     The comparator  155  compares the result of the first determining portion  151  with the result of the second determining portion  153 . If the result of the first determining portion  151  is equal to the result of the second determining portion  153 , the comparator  155  controls the image signal processor  170 , which will be described later, to process the image signal corresponding to the VESA standard or the EIA/CEA861B standard.  
         [0037]     If the result of the first determining portion  151  is different from the result of the second determining portion  153 , the comparator  155  transmits a reset signal to the outer device connector  110  to initiate the image signal input from the outer device. The image signal separator  130  receives again the image signal and separates the received image signal. The first determining portion  151  and the second determining portion  153  determine the standard of the image signal again. The comparator  155  compares the result of the first determining portion  151  with the result of the second determining portion  153 . If the result of the first determining portion  151  is equal to the result of the second determining portion  153 , the comparator  155  controls the image signal processor  170  to process the image signal depending on the determined result. If the result of the first determining portion  151  is different from the result of the second determining portion  153 , the comparator  155  transmits the reset signal to the outer device connector  110 . In this way, if the above two results are different from each other, the controller  150  performs the determining procedures three times. If the result of the first determining portion  151  is different from the result of the second determining portion  153  even after performing the determining procedures three times, the controller  150  controls the image signal processor  170  to process the image signal depending on the standard determined by the first determining portion  151 .  
         [0038]     The image signal processor  170  receives the image data of 24-bit from the image signal separator  130  and processes the image signal of the received data. At this time, the image signal processor  170  processes the image signal depending on the standard determined by the controller  150 .  
         [0039]     The display  190  outputs the image signal processed by the image signal processor  170  to the screen to allow a user to view it.  
         [0040]      FIG. 2A  illustrates the difference between the image signal corresponding to the VESA standard and the image signal corresponding to the EIA/CEA861B in a mode of 480p.  
         [0041]     Referring to  FIG. 2A , if the resolution determining portion 151a determines the input image signal as the mode of 480p, the standard determining portion  151   b  determines the standard based on the number of H_sync periods in a V_sync period of the input image signal. In other words, if the input image signal corresponds to the VESA standard, the number of H_sync periods in the V_sync period is 2H. If the input image signal corresponds to the EIA/CEA861B standard, the number of H_sync periods in the V_sync period is 6H. The standard determining portion  151   b  determines the input image signal as the VESA standard if the number of H_Sync periods in the V_sync period is 2H to 3H. On the other hand, the standard determining portion  151   b  determines the input image signal as the EIA/CEA861B standard if the number of H_sync periods in the V_sync period is 5H to 7H.  
         [0042]      FIG. 2B  illustrates the difference between the image signal corresponding to the VESA standard and the image signal corresponding to the EIA/CEA861B in a mode of 720p.  
         [0043]     Referring to  FIG. 2B , if the resolution determining portion  151   a  determines the input image signal as the mode of 720p, the standard determining portion  151   b  determines the standard based on the number of pixel clocks in a H_Front porch period. In other words, if the input image signal corresponds to the VESA standard, the number of pixel clocks in the H_Front porch period is 70T. If the input image signal corresponds to the EIA/CEA861B standard, the number of pixel clocks in the H_Front porch period is 110T. The standard determining portion  151   b  determines the input image signal as the VESA standard if the number of pixel clocks in the H_Front porch period is 60T to 80T. On the other hand, the standard determining portion  151   b  determines the input image signal as the EIA/CEA861B standard if the number of pixel clocks in the H_Front porch period is 100T to 120T.  
         [0044]      FIG. 2C  illustrates the difference between the image signal corresponding to the VESA standard and the image signal corresponding to the EIA/CEA861B in a mode of 1080i.  
         [0045]     Referring to  FIG. 2C , if the resolution determining portion  151   a  determines the input image signal as the mode of 1080i, the standard determining portion  151   b  determines the standard based on the number of pixel clocks in a H_Front porch period. In other words, if the input image signal corresponds to the VESA standard, the number of pixel clocks in the H_Front porch period is 44T. If the input image signal corresponds to the ELA/CEA861B standard, the number of pixel clocks in the H_Front porch period is 88T. The standard determining portion  151   b  determines the input image signal as the VESA standard if the number of pixel clocks in the H_Front porch period is 40T to 50T. On the other hand, the standard determining portion 151b determines the input image signal as the EIA/CEA861B standard if the number of pixel clocks in the H_Front porch period is 80T to 100T.  
         [0046]      FIG. 3  is a flow chart illustrating the operation of an image display device according to an exemplary embodiment of the present invention.  
         [0047]     Referring to  FIG. 3 , the outer device connector receives the image signal from the outer device connected with the outer device connector  110  through the DVI cable or the HDMI cable (S 200 ).  
         [0048]     The image signal separator  130  separates the input image signal into the image data of 24-bit, the vertical/horizontal synchronizing signals, the data enable signal, and the pixel clock signal (S 210 ).  
         [0049]     After determining resolution of the input image signal based on the vertical/horizontal synchronizing signals, the first determining portion  151  determines the standard of the input image signal based on the vertical/horizontal synchronizing signals, the data enable signal, and the pixel clock signal. The second determining portion  153  receives the image data of 24-bit and compares signal levels of 8-bit data corresponding to a luminance signal among the image data of 24-bit to determine the standard of the input image signal (S 230 ).  
         [0050]     The comparator  155  compares the first determined result of the first determining portion  151  with the second determined result of the second determining portion  153  to determine whether the results are equal to each other (S 240 ).  
         [0051]     As a result, if the first determined result is equal to the second determined result, the comparator  155  processes the image signal depending on the result to output the processed image signal to the screen (S 250 ).  
         [0052]     If the first determined result is different from the second determined result, the reset signal is generated to initiate the image signal received from the outer device (S 270 ). Then, the steps S 200  to S 240  are repeated three times. If the first determined result is different from the second determined result in spite of the repeated steps of three times (S 260 ), the comparator  155  processes the image signal depending on the first determined result to output the processed image signal to the screen (S 280 ). The standard of the input image signal can be determined by the above steps.  
         [0053]     As described above, brightness and picture quality of the screen can be realized in the best mode by determining the standard of the image signal input through the DVI cable or the HDMI cable. The image display device becomes compatible with its peripheral devices connected thereto through the DVI cable or the HDMI cable.  
         [0054]     The foregoing embodiment and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. Also, the description of the embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.