Patent Publication Number: US-2011050863-A1

Title: Display apparatus and control method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2009-0082717, filed on Sep. 2, 2009 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Apparatuses and methods consistent with the present invention relate to a display apparatus which displays an image corresponding to an image signal and a control method thereof, and more particularly, to a display apparatus which processes an image signal to be displayed in an image if an image signal corresponding to a three-dimensional image is input and a control method thereof. 
     2. Description of the Related Art 
     A display apparatus processes an image signal input from an image supplying source, and displays an image in a display panel embodied by a liquid crystal, or the like. The display apparatus scans a scanning line including image information on a panel to display an image in the panel, and configures a single image frame by the scanning line scanned in the panel. 
     An image signal input to the display apparatus corresponds to a two-dimensional image and a three-dimensional image depending on a property thereof. The two-dimensional image signal includes a single image frame data between two vicinal perpendicular blank sections. On the other hand, the three-dimensional image signal, unlike the two-dimensional image signal, includes image frame data of a left eye image and of a right eye image, and shutter eyeglasses which selectively open and close a left eye and a right eye of a user are provided to the display apparatus to correspond to a display of a three-dimensional image. Accordingly, a user is capable of recognizing a cube of a three-dimensional image. 
     Since there is no distinction between a left eye image and a right eye image in a two-dimensional image, the shutter eyeglasses do not operate and maintain an opening state of a left eye and a right eye of a user when a two-dimensional image is displayed in the display apparatus. 
     Accordingly, to display a three-dimensional image signal as a three-dimensional image, it is necessary to divide left eye image frame data and right eye image frame data in an image signal, and to display either of a left eye image or a right eye image that corresponds to an image frame currently displayed on a display. 
     SUMMARY OF THE INVENTION 
     The foregoing and/or other aspects of the present invention can be achieved by providing a control method of a display apparatus, including: receiving a three-dimensional image signal including a plurality of image frame data in an active section between vicinal first and second vertical blank sections in an image signal; generating a synchronizing signal corresponding to a third vertical blank section which divides the plurality of image frame data in the active section of the received image signal; and displaying the received image signal in an image synchronized with the generated synchronizing signal. 
     Generating the synchronizing signal may include determining a feature of the third vertical blank section to have the same width as the first and second vertical blank sections. 
     Generating the synchronizing signal may include: detecting vertical blank information including at least one of a vertical synchronization section width, a vertical front porch value, a vertical back porch value and a vertical synchronization timing of the received image signal, and determining features of the third vertical blank section based on the detected vertical blank information. 
     The third dimensional image signal may include left eye image frame data and right eye image frame data in the active section, and generating the synchronizing signal may include determining features of the third vertical blank section so that each width of the left eye image frame data and the right eye image frame data divided by the third vertical blank section is the same. 
     The image signal may include a video ID code based on a high definition multimedia interface (HDMI) standard, and the receiving the image signal may include: detecting the video ID code of the received image signal; and determining whether the image signal corresponds to a two-dimensional image or a three-dimensional image based on the detected video ID code. 
     The control method may including displaying the received image signal in an image without generating the synchronizing signal if the image signal is determined to correspond to a two-dimensional image based on the detected video ID code. 
     The three-dimensional image signal may include left eye frame data and right eye image frame data in the active section, and the control method may include generating a logical signal representing which of a left eye image and a right eye image an image frame data in the active section corresponds to if the three-dimensional image signal is received. 
     The left eye image frame data and the right eye image frame data may be disposed in a disposition order in the active section, and generating the logical signal may include determining which of a left eye image and a right eye image an image frame data in the active section corresponds to based on the disposition order. 
     The image signal may be received based on the HDMI standard. 
     Another aspect of the present invention may be achieved by providing a display apparatus, including: a display unit; a signal input unit which receives a three-dimensional image signal including a plurality of image frame data in an active section between vicinal first and second vertical blank sections in an image signal; and an image processing unit which generates a synchronizing signal corresponding to a third vertical blank section which divides the plurality of image frame data in the active section of the received three-dimensional image signal, and processes the received three-dimensional image signal to be synchronized with the generated synchronizing signal to be displayed in an image in the display unit. 
     The image processing unit may determine a width of the third vertical blank section to have the same width as the first and second vertical blank sections. 
     The image processing unit may detect vertical blank information which includes at least one of a vertical synchronization section width, a vertical front porch value, a vertical back porch value and a vertical synchronization timing of the received image signal, and determine the third vertical blank section based on the detected vertical blank information. 
     The third dimensional image signal may include left eye image frame data and right eye image frame data in the active section, and the image processing unit may determine the third vertical blank section so that each width of the left eye image frame data and the right eye image frame data divided by the third vertical blank section is the same. 
     The image signal may include a video ID code based on a high definition multimedia interface (HDMI) standard, and the image processing unit may detect the video ID code of the received image signal, and determine whether the image signal corresponds to a two-dimensional image or a three-dimensional image based on the detected video ID code. 
     The image processing unit may process the received image signal to be displayed in an image without generating the synchronizing signal if the image signal is determined to correspond to a two-dimensional image based on the detected video ID code. 
     The three-dimensional image signal may include left eye frame data and right eye image frame data in the active section, and the image processing unit may generate a logical signal representing which of a left eye image and a right eye image an image frame data in the active section corresponds to if the three-dimensional image signal is received. 
     The left eye image frame data and the right eye image frame data may be disposed in a disposition order in the active section, and the image processing unit may determine which of a left eye image and a right eye image an image frame data in the active section corresponds to based on the disposition order. 
     The image signal may be received based on the HDMI standard. 
     The image processing unit may include: a first image processing unit which generates the synchronizing signal, and synthesizes the generated synchronizing signal with the received image signal to output; and a second image processing unit which scales an image signal output from the first image processing unit to be displayed in an image. 
     Another aspect of the present invention may be achieved by providing a display apparatus, including: a display unit; a signal input unit which receives a three-dimensional image signal including left eye image frame data and right eye image frame data between vicinal first and second vertical blank sections in an image signal; a first image processing unit which forms a third vertical blank section in a non-image section between the left eye image frame data and the right eye image frame data to convert the received three-dimensional image signal into a two-dimensional type image signal if it is determined that the three-dimensional image signal input to the signal input unit is the three-dimensional image; and a second image processing unit which processes the image signal converted by the first image processing unit to be displayed in an image in the display unit. 
     The first image processing unit may generate a logical signal representing which of a left eye image and a right eye image an image frame data of the converted two-dimensional image signal corresponds to. 
     The first image processing unit may determine the width of the third vertical blank section to be the same as the widths of the first and second vertical blank sections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  exemplarily illustrates a display system according to a first exemplary embodiment of the present invention; 
         FIG. 2  is a configuration block diagram related to a display apparatus and shutter glasses in  FIG. 1 ; 
         FIG. 3  is a configuration block diagram related to a first image processing unit in  FIG. 2 ; 
         FIG. 4  schematically illustrates configurations of an image signal, a synchronizing signal and a logical signal processed by the first image processing unit in  FIG. 3 ; 
         FIG. 5  is a control flowchart illustrating a control method of the display apparatus in  FIG. 1 ; 
         FIG. 6  is a control flowchart illustrating a process of determining whether an input image signal corresponds to a three-dimensional image or not in the display apparatus in  FIG. 1 ; 
         FIG. 7  illustrates a control flowchart illustrating a process of generating a new synchronizing signal and displaying an image signal in an image to synchronize with the synchronizing signal in the display apparatus in  FIG. 1 ; 
         FIG. 8  is a control flowchart illustrating a process of generating a logical signal and a shutter control signal and operating shutter eyeglasses depending thereon in the display apparatus in  FIG. 1 ; 
         FIG. 9  is a configuration block diagram related to a display apparatus according to a second exemplary embodiment of the present invention; and 
         FIG. 10  is a configuration block diagram illustrating a display system according to a third exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The exemplary embodiments are described below so as to explain the present invention by referring to the figures. Repetitive description with respect to like elements of different embodiments may be omitted for the convenience of clarity. 
       FIG. 1  exemplarily illustrates a display system  1  according to a first exemplary embodiment of the present invention. 
     As shown in  FIG. 1 , the display system  1  according to the present exemplary embodiment is a configuration capable of selectively displaying a two-dimensional image and a three-dimensional image. The display system  1  includes a display apparatus  10  including a display unit  100  in which an image is displayed and displaying an image signal input from at least one image supplying source (not shown) in the display unit  100 , and shutter eyeglasses  20  operating according to an image displayed in the display unit  100 , which is a two-dimensional image or a three-dimensional image. 
     The display apparatus  10  may be embodied by a television or a computer monitor connected to a computer main body. As an image signal corresponding to a two-dimensional image or a three-dimensional image is input from the image supplying source, the display apparatus  10  selectively processes the image signal and displays the two-dimensional or three-dimensional image in the display unit  100 . 
     An image signal input to the display apparatus  10  in the present exemplary embodiment is exemplarily described as a transition minimized differential signaling (TMDS) based on a high definition multimedia interface (HDMI) standard. However, this is just an exemplary embodiment, and does not define the present invention in embodying the display apparatus  10  and the display system  1  according to the present invention. 
     If an image signal corresponds to a two-dimensional image, the image signal includes a single image frame data between two vicinal perpendicular blank sections. On the other hand, if an image signal corresponds to a three-dimensional image, the image signal includes left eye image frame data and right eye image frame data between two vicinal perpendicular blank sections. This configuration of the image signal is designated as a frame pecking type according to the HDMI standard, but this standard and designation do not define the present invention. 
     The display apparatus  10  generates a new synchronizing signal corresponding to a perpendicular blank section which divides left eye image frame data and right eye image frame data with respect to an input three-dimensional image signal, and displays the three-dimensional image signal in an image synchronized with the synchronizing signal. Also, the display apparatus  10  generates a logical signal corresponding to which of a left eye image and a right eye image is currently being displayed as the image. 
     According to this, if a three-dimensional image signal depending on the frame packing type is input, the display apparatus  10  is capable of processing the three-dimensional image signal with only a software configuration although a separate hardware configuration is not applied thereto. 
     If a three-dimensional image is displayed in the display apparatus  10 , the shutter eyeglasses  20  selectively open or block a sight of a left eye or a right eye of a user according to which of a left eye image and a right eye image is displayed in the display unit  100 . That is, if a left eye image is displayed in the display unit  100 , the shutter eyeglasses  20  open a sight of a left eye, and block a sight of a right eye. On the contrary, if a right eye image is displayed in the display unit  100 , the shutter eyeglasses  20  open a sight of a right eye, and block a sight of a left eye. 
     Hereinafter, configurations of the display apparatus  10  and the shutter eyeglasses  20  according to the present exemplary embodiment will be described by referring to  FIG. 2 .  FIG. 2  is a configuration block diagram of the display apparatus  10  and the shutter glasses  20 . 
     As shown in  FIG. 2 , the display apparatus  10  includes the display unit  100 , an image signal switch  200  which selects and outputs one image signal  53  among at least one image signal  51  input from an outside source, a first image processing unit  300  which converts the image signal  53  into a signal type corresponding to a two-dimensional image capable of being processed by a second image processing unit  400  if the image signal  53  corresponds to a three-dimensional image signal type, and the second image processing unit  400  which processes a two-dimensional image signal  55  to be displayed in the display unit  100 . 
     Also, the display apparatus  10  includes a communication unit  500  which transmits a shutter control signal  59  based on a predetermined logical signal with respect to the shutter eyeglasses  20 . This logical signal will be described later. 
     In  FIG. 2 , the first image processing unit  300  and the image signal switch  200  are illustrated as separate configurations, but theses are just an exemplary embodiment and the first image processing unit  300  and the image signal switch  200  may be configured to be integrated. 
     The shutter eyeglasses  20  includes a left eye unit  21  and a right eye unit  23  respectively opening and blocking entrance of a light, and a shutter control unit  25  which selectly opens and blocks the left eye unit  21  and the right eye unit  23  to correspond to the shutter control signal  59  received from the communication unit  500 . 
     Hereinafter, each element of  FIG. 2  will be described. 
     The display unit  100  displays an image processed by the second image processing unit  400 . This configuration of the display unit  100  is not defined, but may be embodied by various display types such as a liquid crystal, a plasma, a light emitting diode, an organic light emitting diode, a surface conduction electron emitter, a carbon nano tube, a nano crystal, etc. 
     If the display unit  100  is embodied by a liquid crystal display panel, a plurality of horizontal lines corresponding to an image frame data are vertically arranged to display a single image frame. 
     The image signal switch  200  is capable of receiving at least one image signal  51  input from an outside, and selects and outputs one image signal  53  among a plurality of image signals  51  input. To select an image signal, the display apparatus  10  may include a menu key (not shown) or a remote controller (not shown) manipulated by a user. 
     If the image signal  53  output from the image signal switch  200  corresponds to a three-dimensional image, the first image processing unit  300  converts and outputs the image signal  53  into the image signal  55  corresponding to a two-dimensional image. Also, the first image processing unit  300  outputs the image signal  55  together with a logical signal  57  or a general purpose input/output signal representing which of a left eye image and a right eye image the image frame data in the image signal  55  corresponds to. That is, the logical signal  57  represents an arrangement, or more specifically an arrangement order, of the left eye image and the right eye image within the active section of the three-dimensional image. The configuration of the first image processing unit  300  will be described later. 
     If the input image signal  53  does not correspond to a three-dimensional image, the first image processing unit  300  does not convert the image signal  53 , and does not output the logical signal  57  as described above. 
     The second image processing unit  400  processes a scaling of the image signal  55  to a size and a resolution corresponding to the display unit  100 , and processes a scanning of an image frame data of the image signal  55  in the display unit  100  to be displayed in an image. For this, the second image processing unit  400  may include a central processing unit (CPU, not shown), a scaler (not shown) and a line scanner (not shown), and may further include a configuration for embodying an additional function such as an image quality reinforcement. This configuration may be separately provided, or may be provided as an integrated body according to a one chip configuration. 
     The second image processing unit  400  may generate the shutter control signal  59  for selectively opening and closing the left eye unit  21  and the right eye unit  23  based on the image signal  55  and the logical signal  57 . For example, if an image data section of the image signal corresponds to a left eye image, a left eye image is displayed in the display unit  100  during a vertical blank section disposed next, and the next image data section corresponds to a right eye image. The second image processing unit  400  may generate the shutter control signal  59  accordingly. 
     The communication unit  500  transmits the shutter control signal  59  to the shutter control unit  25  of the shutter eyeglasses  20 . The type of transmission used to transmit the shutter control signal  59  by the communication unit  500  is not defined, and may be embodied by an infrared ray, etc. Also, the communication unit  500  may be integrated to the display apparatus  10 , or may be configured to be separated from the display apparatus  10  in a dongle type. 
     Hereinafter, the configuration of the first image processing unit  300  will be described by referring to  FIG. 3 .  FIG. 3  is a configuration block diagram related to the first image processing unit  300 . 
     As shown in  FIG. 3 , the first image processing unit  300  includes a signal input unit  310  to which the image signal  53  is input, a vertical blank analyzing unit  320  which detects and analyzes vertical blank information of the image signal  53 , a synchronizing signal generating unit  330  which generates the synchronizing signal  60  based on the analyzed vertical blank information, a logical signal generating unit  340  which generates a logical signal corresponding to a property of an image frame data included in the image signal  53 , a three-dimensional image determining unit  350  which determines whether the image signal  53  corresponds to a three-dimensional image or not, a micro controller  360  which controls turning on and turning off of an element of the first image processing unit  300  depending on a determined result, and a signal output unit  370  which outputs the logical signal  57  together with the image signal  55  which synchronizes the synchronizing signal  60  and the image signal  53 . 
     If the image signal  53  is input, the signal input unit  310  respectively outputs the image signal  53  to the signal output unit  370 , the vertical blank analyzing unit  320  and the three-dimensional image determining unit  350 . Also, the signal input unit  310  may extract and transmit only information referred to by corresponding elements from the image signal  53  with respect to the vertical blank analyzing unit  320  and the three-dimensional image determining unit  350 . 
     If the image signal  53  corresponds to a three-dimensional image, the vertical blank analyzing unit  320  detects vertical blank information of the image signal  53 . The vertical blank information includes information about a vertical synchronization section width, a vertical front porch value, a vertical back porch value and a vertical synchronization timing of the image signal  53 . The vertical blank analyzing unit  320  determines a width and a timing position of a new vertical blank section for dividing left eye image frame data and right eye image frame data of the image signal  53  based on the vertical blank information. The width and the timing position of the new vertical blank section are determined such that the width of the left eye image frame data is equal to the width of the right eye image frame data. 
     If the three-dimensional image signal  53  is input based on a frame packing type of the HDMI, left eye image frame data and right eye image frame data exist between two vicinal vertical blank sections in the image signal  53 . The vertical blank analyzing unit  320  determines a new vertical blank section to be inserted in a non-image section between the left eye image frame data and the right eye image frame data so that the left eye image frame data and the right eye frame data can be divided from each other. 
     The vertical blank analyzing unit  320  transmits these analyzed and determined results to the synchronizing signal generating unit  330  and to the logical signal generating unit  340 . 
     The synchronizing signal generating unit  330  generates the synchronizing signal  60  corresponding to the vertical blank section determined in the vertical blank analyzing unit  320  to transmit to the signal output unit  370 . The synchronizing signal generating unit  330  generates the synchronizing signal  60  such that left eye image frame data and right eye frame data of the image signal  53  are divided according to the width and the timing position of the new vertical blank section. 
     The logical signal generating unit  340  generates the logical signal  57  to transmit to the signal output unit  370 , the logical signal  57  representing which of a left eye image and a right eye image an image frame data in the image signal  53  corresponds to based on a determined content of the vertical blank analyzing unit  320 . The logical signal generating unit  340  refers to a determination of a vertical blank section of the image signal  53  and the synchronizing signal  60  in generating the logical signal  57 , thereby synchronizing a logical level (e.g., a timing of low and high levels) to the image frame data. 
     The logical signal generating unit  340  determines to represent a left eye image and a right eye image to correspond to each of a low level and a high level of the logical signal  57 . For example, the logical signal generating unit  340  may represent a low level of the logical signal  57  to correspond to a left eye image, and a high level of the logical signal  57  to correspond to a right eye image. On the contrary, the logical signal generating unit  340  may represent a high level of the logical signal  57  to correspond to a left eye image, and a low level of the logical signal  57  to correspond to a right eye image. In this logical signal  57 , since there is no image frame data in a vertical blank section, it is unnecessary to consider whether a vertical blank section is a low level or a high level. 
     According to the HIMI standard, if the image signal  53  corresponds to a three-dimensional image, left eye image frame data is disposed to precede right eye image frame data between two vicinal vertical blank sections. 
     Based on this disposition order, the logical signal generating unit  340  determines that image frame data disposed to follow a vertical blank section of the image signal  53  is a left eye image, and image frame data disposed next thereto is a right eye image. Depending on this result, the logical signal generating unit  340  generates the logical signal  57 . 
     The image signal  53  is input to the signal input unit  310 , the three-dimensional image determining unit  350  determines whether the image signal  53  corresponds to a three-dimensional image or not. This determining method may be variously provided, and the three-dimensional image determining unit  350  may determine whether the image signal  53  corresponds to a two-dimensional image or a three-dimensional image by analyzing a register of the image signal  53 . 
     The three-dimensional image determining unit  350  transmits a determination result to the micro controller  360 . 
     The micro controller  360  selectively turns on or turns off the vertical blank analyzing unit  320 , the synchronizing signal generating unit  330  and the logical signal generating unit  340  based on a determination result of the three-dimensional image determining unit  350 . 
     For example, if the image signal  53  is determined to correspond to a three-dimensional image, the micro controller  360  turns on the vertical blank analyzing unit  320 , the synchronizing signal generating unit  330  and the logical signal generating unit  340 . Accordingly, the synchronizing signal  60  and the logical signal  57  can be generated by the above configurations. 
     On the other hand, if the image signal  53  is determined to correspond to a two-dimensional image, since it is unnecessary to generate the synchronizing signal  60  and the logical signal  57 , the micro controller  360  turns off the vertical blank analyzing unit  320 , the synchronizing signal generating unit  330  and the logical signal generating unit  340 . Accordingly, a signal finally output from the signal output unit  370  is the image signal  53  which is the same as the image signal  53  input to the signal input unit  310  (i.e., the two-dimensional image signal). 
     The signal output unit  370  receives the image signal  53  output from the signal input unit  310 , the synchronizing signal  60  output from the synchronizing signal generating unit  330 , and the logical signal  57  output from the logical signal generating unit  340 . The signal output unit  370  synthesizes the image signal  53  and the synchronizing signal  60  to output the new image signal  55  so that image signal  55  can be displayed in an image. For example, the image signal  53  and the synchronizing signal  60  are combined in order to generate the new image signal  55  having a third vertical blank section disposed between left eye image frame data and right eye image frame data. Also, the signal output unit  370  outputs the logical signal  57  together with the new image signal  55 . 
     Hereinafter, processing operations of the three-dimensional image determining unit  350  and the vertical blank analyzing unit  320  will be described in detail by referring to Table 1. Table 1 represents several examples of a video ID code (VIC) which the HIMI standard regulates, and a part of an image frame data and a vertical blank information of each VIC. 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 VIC 
                 description 
                 Vact 
                 Vact_v 
                 Vact_b 
                 Vblank 
                 Vfront 
                 Vsync 
                 Vback 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 32 
                 1080p, 23.98/24 Hz 
                 2205 
                 1080 
                 45 
                 45 
                 4 
                 5 
                 36 
               
               
                 4 
                  720p, 59.94/60 Hz 
                 1470 
                 720 
                 30 
                 30 
                 5 
                 5 
                 20 
               
               
                 19 
                  720p, 50 Hz 
                 1470 
                 720 
                 30 
                 30 
                 5 
                 5 
                 20 
               
               
                   
               
               
                 Each label in the above Table means as follows. 
               
               
                 VIC: video ID code, 
               
               
                 description: resolution information, 
               
               
                 Vact: active section width which is an image frame data section formed between two vicinal vertical blank sections, 
               
               
                 Vact_v: left eye image or right eye image frame data section width in active section, 
               
               
                 Vact_b: non image section width in active section, 
               
               
                 Vblank: vertical blank section width, 
               
               
                 Vfront: vertical front porch value, 
               
               
                 Vsync: vertical synchronization section width, and 
               
               
                 Vback: vertical back porch value. 
               
            
           
         
       
     
     As described above, if the VIC of a certain image signal is present, various information about a signal configuration of the corresponding image signal can be obtained. 
     The three-dimensional image determining unit  350  may analyze the image signal  53  input to the signal input unit  310  to detect the VIC of the corresponding image signal  53 , and may determine whether the corresponding image signal  53  corresponds to a three-dimensional image or not based on a detected VIC. 
     The vertical blank analyzing unit  320  determines a new vertical blank section among the values represented in Table 1 to be inserted in a non-image section of an active section. Since the second image processing unit  400  processes an image signal based on detecting vertical blank sections, if the new vertical blank section is not generated, an active section begins to deviate from a range which is capable of being processed by the second image processing unit  400 . Accordingly, an image fails to be normally displayed. 
     According to Table 1, the values of Vact_b and Vblank are the same. That is, the vertical blank analyzing unit  320  determines a new vertical blank section to have the same width as an existing vertical blank section. Also, in determining a timing position of a new vertical blank section, the vertical blank analyzing unit  320  determines that each width of a left eye frame data and a right eye frame data in an active section is the same. 
     Also, since the value of Vblank is the same as the sum of Vfront, Vsync and Vback, the vertical blank analyzing unit  320  may obtain the width of a vertical blank section by detecting a vertical synchronizing section width, a vertical front porch value and a vertical back porch value of the image signal  53 . 
     Hereinafter, an exemplary embodiment in which the first image processing unit  300  converts a three-dimensional image signal into a type of a two-dimensional image signal, and generates the logical signal  57  will be described by referring to  FIG. 4 .  FIG. 4  schematically illustrates configurations of an image signal, a synchronizing signal and a logical signal according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 4 , an image signal, a synchronizing signal and a logical signal with a timing position are partially represented. 
     (1) represents an image signal corresponding to a two-dimensional image. A vertical blank section V 0  is disposed between each image frame data F 0 . Unlike a three-dimensional image, the two-dimensional image is not divided into a left eye image and a right eye image, and there exists a single image frame data F 0  between two vicinal vertical blank sections V 0 . 
     (2) represents an image signal corresponding to a three-dimensional image. An active section VA is formed between two vicinal vertical blank sections V 1  and V 2 , and there exist two image frame data sections of a left eye image frame data section FL and a right eye image frame data section FR in the active section VA. Also, there exists a non-image section B between the left eye image frame data section FL and the right eye image frame data section FR. 
     The second image processing unit  400  is capable of recognizing the vertical blank sections V 1  and V 2 , but is incapable of recognizing the non-image section B in the active section VA. Accordingly, the first image processing unit  300  determines a new vertical blank section in the non-image section B, by determining features thereof, so that the second image processing unit  400  can recognize the non-image section via the new vertical blank section. 
     (3) is a synchronizing signal corresponding to the vertical blank sections V 1  and V 2  in the three-dimensional image signal in (2). Here, the width WV 1  of the first vertical blank section V 1  and the width WV 2  of the second vertical blank section V 2  are the same. There appears no section corresponding to the non-image section B in the synchronizing signal of (3). Accordingly, the first image processing unit  300  generates a synchronizing signal like that shown in (4). 
     (4) is a synchronizing signal representing a new vertical blank section determined by synchronizing signal generating unit  330  to correspond to the non image section B. The width WV 3  of a third vertical blank section is determined to be the same as WV 1  and WV 2  as described above, and divides the left eye image frame data section FL and the right eye image frame data section FR. 
     (5) is an image signal newly generated when the image signal of (2) is synchronized with the synchronizing signal of (4), that is, when the synchronizing signal of (4) is synthesized or combined with the image signal of (2). In comparison with the image signal of (2), in the image signal of (5), there appears a third vertical blank section V 3  between the first vertical blank section V 1  and the second vertical blank section V 2 . The third vertical blank section V 3  divides the left eye image frame data section FL and the right eye image frame data section FR. That is, the image signal of (5) is in a state converted into a type corresponding to a two-dimensional image like the image signal of (1). 
     Each width WFL and WFR of the left eye image frame data section FL and the right eye image frame data section FR are determined to be the same. That is, the sum of the widths of WFL, WFR and WV 3  is the same as the width VA of the active section of the image signal of (2). 
     Since it is not known which of a left eye image and a right eye image each of the sections FL and FR in the image signal of (5) corresponds to, the first image processing unit  300  generates a logical signal like that shown in (6). 
     (6) is a logical signal having logic levels which represent the sections FL and FR of the image signal of (5) corresponding to a left eye image or a right eye image. According to  FIG. 4 , (6) is represented as a low level in case of a left eye image, and represented as a high level in case of a right eye image. However, the opposite may be possible depending on a design method. Since the vertical blank sections V 1 , V 2  and V 3  are not an image frame data section like the sections FL and FR, it is unnecessary to consider a logic level (i.e., a low level or a high level) in this section. Therefore, the logic level within the logical signal (6) changes its state only when there is a change between a left eye image frame data section FL and a right eye image frame data section FR in the image signal. That is, the logic level in the vertical blank sections V 1 , V 2  and V 3  is the same as the level in the previous section FL or FR. 
     Accordingly, the first image processing unit  300  determines a new vertical blank section V 3  in the non-image section B in the active section VA to convert a three-dimensional image signal into a two-dimensional image type signal, and to generate a logical signal indicating whether an image frame data is a left eye image or a right eye image. 
     Accordingly, although the second image processing unit  400  fails to recognize the non-image section B, an image signal can be normally displayed in an image. 
     Hereinafter, a control method of the display apparatus  10  according to an exemplary embodiment of the present invention will be described by referring to  FIG. 5 .  FIG. 5  is a control flowchart illustrating this process. 
     As shown in  FIG. 5 , if an image signal is input (S 100 ), the first image processing unit  300  determines whether the image signal is a three-dimensional image signal or not (S 110 ). 
     If the first image processing unit  300  determines that the image signal is a three-dimensional image signal, the first image processing unit  300  determines a new vertical blank section in an active section (S 120 ). The new vertical blank section corresponds to a non-image section in an active section. The first image processing unit  300  generates a synchronizing signal corresponding to the determined vertical blank section (S 130 ). 
     The second image processing unit  400  displays the image signal in an image synchronized with a synchronizing signal generated in the first image processing unit  300  (S 140 ). 
     Hereinafter, the control process in  FIG. 5  will be exemplarily described more in detail by referring to  FIGS. 6 to 8 .  FIG. 6  is a control flowchart illustrating a process of determining whether an input image signal corresponds to a three-dimensional image or not,  FIG. 7  is a control flowchart illustrating a process of generating a new synchronizing signal and displaying an image signal in an image synchronized with the synchronizing signal, and  FIG. 8  is a control flowchart illustrating a process of generating a logical signal and a shutter control signal and operating the shutter eyeglasses  20  depending thereon. 
     As shown in  FIG. 6 , if an image signal is input (S 200 ), the first image processing unit  300  analyzes the image signal to detect a VIC (S 210 ). The first image processing unit  300  determines whether the corresponding image signal corresponds to a three-dimensional image or not by using the detected VIC (S 220 ). For this, the first image processing unit  300  may store a predetermined table related to the VIC. 
     If the first image processing unit  300  determines that the image signal is a three-dimensional image signal (S 230 ), the first image processing unit  300  processes the image signal, as described later. However, if the first image processing unit  300  determines that the image signal is not a three-dimensional image signal, the first image processing unit  300  displays an image based on existing vertical synchronizing information of the image signal. 
     As shown in  FIG. 7 , if the image signal is determined to be a three-dimensional image signal in the operation S 230  of  FIG. 6 , the first image processing unit  300  detects vertical blank information of the image signal (S 300 ). 
     The first image processing unit  300  determines the widths of vicinal first and second vertical blank sections based on the vertical blank information (S 310 ), and determines a timing position which makes each width of left eye and right eye image frame data be equal to one another (S 320 ). The first image processing unit  300  determines features of a new third vertical blank section to correspond to the determined width and timing position (S 330 ). Also, the first image processing unit  300  generates a synchronizing signal corresponding to the third vertical blank section (S 340 ). 
     The first image processing unit  300  synthesizes the generated synchronizing signal and the input image signal to output a new image signal (S 350 ). 
     The second image processing unit  400  displays an image based on the synthesized image signal (S 360 ). 
     Also, as shown in  FIG. 8 , if the image signal is determined to be a three-dimensional image signal in the operation S 230  of  FIG. 6 , the first image processing unit  300  detects vertical blank information of the image signal (S 400 ). Based on this information, the first image processing unit  300  determines a timing position of an image frame data (S 410 ), and generates a logical signal representing whether the image frame data is a left eye image or a right eye image to be appropriate to the determined timing position (S 420 ). 
     The second image processing unit  400  generates a shutter control signal based on the logical signal (S 430 ), and transmits the shutter control signal to the shutter eyeglasses  20  (S 440 ). The shutter eyeglasses  20  operates to correspond to the received shutter control signal (S 450 ). 
     According to the above processes, if an input image signal corresponds to a three-dimensional image, the display apparatus  10  according to the present exemplary embodiment generates a new vertical blank section in a non-image section in an active section, and generates a logical signal representing whether an image frame data corresponds to a left eye image or a right eye image, thereby displaying a three-dimensional image. 
     As described above, the first image processing unit  300  is described to be provided separately with the image signal switch  200 , but the present invention is not defined thereto. 
     For example, as shown in  FIG. 9 , the first image processing unit  300   a  may be configured to be integrated to the image signal switch  200   a,  or may be provided to be a sub-element of the image signal switch  200   a.  Each element including the first image processing unit  300   a  shown in  FIG. 9  may employ the configurations described above. 
     In the exemplary embodiment, the second image processing unit  400  is described to generate the shutter control signal  59  based on the logical signal  57 , but the present invention is not defined thereto. For example, the first image processing unit  300  generates the logical signal  57 , and may generate and output the shutter control signal  59  based thereon, or a separate configuration may be provided to the communication unit  500  to generate the shutter control signal  59 . 
     In the above exemplary embodiment, the display system  1  is described to include the shutter eyeglasses  20 , but the present invention is not defined thereto. For example, the display system  1  may be embodied to include polarizing eyeglasses  30  instead of the shutter eyeglasses  20 , and this exemplary embodiment will be described by referring to  FIG. 10 . 
       FIG. 10  is a configuration block diagram illustrating a display system  1  according to another exemplary embodiment of the present invention. 
     As shown in  FIG. 10 , a display system  1  according to the present exemplary embodiment includes a display apparatus  10  and the polarizing eyeglasses  30 . 
     The display apparatus  10  includes a display unit  100   a,  an image signal switch  200 , a first image processing unit  300  and a second image processing unit  400   a.  Here, the image signal switch  200  and the first image processing unit  300  may have the substantially same configurations as the exemplary embodiment described above. 
     In processing a three-dimensional image signal  55  output from the first image processing unit  300 , the second image processing unit  400   a  processes the three-dimensional image signal so that a left eye image and a right eye image can be mixed in a single screen of the display unit  100   a.  This displaying method may employ various methods. For example, the second image processing unit  400   a  alternately forms horizontal scanning lines corresponding to left eye image frame data and right eye image frame data to the display unit  100   a,  and each horizontal scanning line respectively corresponding to the left eye image and the right eye image is provided so that the polarity of a polarizing ingredient is different. 
     The polarizing eyeglasses  30  are provided so that the left eye unit  31  and the right eye unit  33  can transmit a polarizing ingredient having different polarities, and accordingly, a left eye image and a right eye image can be respectively projected to a left eye and a right eye of a user. 
     There are various other methods of displaying a left eye image and a right eye image in the display apparatus  10 . An alternate matrix arrangement of a pixel unit of the display unit  100   a  may be formed, or a left eye image and a right eye image may be alternately displayed by a vertical pixel line. Alternatively, by applying a liquid crystal polarizing switch panel to the display unit  100   a,  the polarity of a polarizing ingredient may be changed by a screen unit, thereby displaying an image. 
     In this exemplary embodiment (e.g.,  FIG. 10 ), unlike the exemplary embodiments described above, the configuration of the communication unit  500  transmitting a shutter control signal to the shutter eyeglasses  20  is not necessary. In this case, the logical signal  57  may be not generated, or may be referred to when the second image processing unit  400   a  forms a scanning line to the display unit  100   a.    
     Although a few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.