Abstract:
An apparatus and a method for eliminating an afterimage while displaying the same image continuously are provided. The afterimage elimination apparatus includes: a display unit for displaying an input image signal; and a controller for moving a display position of the image based on pre-determined movement range information if the controller judges that the image displayed on the display unit continues to be displayed for a certain period of time. The movement range information is within the values that do not allow a user to recognize the movement of the image visibly, and includes a movement direction and a movement amount. Therefore, even though the same image is displayed on a display panel for a certain period of time, an afterimage can be prevented.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a display device and a display method, and more particularly, to an apparatus and a method for eliminating an afterimage generated in a display panel. The present application is based on Korean Patent Application No. 2001-64386, filed Oct. 18, 2001, which is incorporated herein by reference.  
           [0003]    2. Description of the Related Art  
           [0004]    An afterimage is generated when the same image is displayed for a certain period of time. An afterimage may be especially clear when the display device is a Liquid Crystal Display (LCD) panel.  
           [0005]    In the past, if the same image is displayed for a certain period of time, a pre-configured OSD image is displayed instead of the image or the display device is set up in a standby mode in order to eliminate the afterimage. However, when the afterimage is eliminated by the above methods, the user cannot view the image at the time that the afterimage is expected to happen.  
         SUMMARY OF THE INVENTION  
         [0006]    To solve the above-described problem, it is an object of the present invention to provide an apparatus and a method for eliminating an afterimage while displaying the same image continuously.  
           [0007]    To achieve the above object, an apparatus for eliminating the afterimage according to an embodiment of the present invention includes:  
           [0008]    a display unit for displaying an input image signal; and  
           [0009]    a controller for moving a display position of the image based on predetermined movement range information if the controller judges that the image displayed on the display unit continues to be displayed for a certain period of time.  
           [0010]    The movement range information is within the values that do not allow a user to recognize the movement of the image visibly, and includes a movement direction and a movement amount.  
           [0011]    To achieve the above object, an afterimage elimination apparatus according to an embodiment of the present invention includes:  
           [0012]    a memory for storing an input image signal;  
           [0013]    a comparator for comparing frame image signals using data read from the memory and/or data written into the memory;  
           [0014]    a display unit for displaying the image signal;  
           [0015]    an operation unit for operating the display unit so that the image signal can be displayed on the display unit; and  
           [0016]    a controller for controlling the operation unit so that the display position of the image can be moved based on pre-determined movement range information when the controller judges that the image displayed on the display unit continues to be displayed for a certain period of time after the comparison of the comparator.  
           [0017]    To achieve the above object, a method for eliminating an afterimage from a display device, the afterimage elimination method includes:  
           [0018]    setting up a movement range of an image and a time to determine the movement of the image displayed on the display device if an afterimage elimination mode is set up; and  
           [0019]    moving the image based on the information of the movement range if the image displayed on the display device continues to be displayed for a certain period of time.  
           [0020]    It is preferable that moving the image includes:  
           [0021]    a first movement step of moving the image in the left direction by a pre-determined number of pixels if it is judged that the image continues to be displayed for a certain period of time after frame image signals are compared;  
           [0022]    a second movement step of moving the image in the upper direction by the pre-determined number of pixels if it is judged that the image continues to be displayed for the certain period of time after the first movement step;  
           [0023]    a third movement step of moving the image in the right direction by the pre-determined number of pixels if it is judged that the image continues to be displayed for the certain period of time after the second movement step; and  
           [0024]    a fourth movement step of moving the image in the lower direction by the pre-determined number of pixels if it is judged that the image continues to be displayed for the certain period of time after the third movement step. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    The above object and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:  
         [0026]    [0026]FIG. 1 is a block diagram of an apparatus for eliminating an afterimage according to a preferred embodiment of the present invention; and  
         [0027]    [0027]FIG. 2 is a flowchart showing a method to eliminate the afterimage according to the preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    [0028]FIG. 1 is a block diagram of an apparatus for eliminating an afterimage according to a preferred embodiment of the present invention. With reference to FIG. 1, the afterimage eliminating apparatus according to the present invention includes a signal processor  101 , a memory  102 , a comparator  103 , a controller  104 , an operation unit  105  and a display unit  106 .  
         [0029]    The signal processor  101  converts an input image signal into a display format. If the signal processor  101  receives the image signal, it writes the signal into the memory  102 , and reads an image signal stored in the memory  102  and converts the read signal into the display format and outputs it.  
         [0030]    The format conversion processing in the signal processor  101  is performed in a known way. For example, if a display device is a CRT display apparatus, the signal processor  101  converts the image signal inputted from the memory  102  into the format that can be displayed on the CRT. If the display device is an LCD television, the signal processor  101  converts the image signal inputted from the memory  102  into the format that can be displayed on the LCD.  
         [0031]    The memory  102  stores image data by a frame unit.  
         [0032]    The comparator  103  compares the image signal written into the memory  102  with the image signal read from the memory  102 . That is, with a pre-determined time gap, the comparator  103  compares image signals written into the memory  102 , and read from the memory  102  in order to identify if any change exists in the image signals by a frame unit. That is, the comparator  103  identifies if there is any difference between a previous frame image and a current frame image, or between the current frame image and the next frame image. Therefore, the pre-determined time gap is set to compare the image signals by the frame unit.  
         [0033]    However, if there is one frame difference between the image signal read from the memory  102  by the signal processor and the image signal written into the memory  102 , the comparator  103  compares the image written into the memory  102  with that read from the memory  102 . Then, the comparator  103  can identify if there is any difference between frames and display the identification result.  
         [0034]    As for the controller  104 , an afterimage elimination mode is set up by an external input signal. In the afterimage elimination mode, the controller  104  sets up operation conditions necessary to eliminate the afterimage if information of various conditions is inputted from the exterior. According to the present invention, the position of the displayed image may be moved in order to eliminate the afterimage. Therefore, the operation conditions include the time during which the displayed image continues to be displayed and a movement range including the movement direction and the movement amount of the image.  
         [0035]    Then, the controller  104  judges whether the same image is displayed for a certain period of time, based on the comparison result transmitted by the comparator  103 . If the controller  104  judges that the same image is displayed for a certain period of time, it sends a control signal, according to which the position of the displayed image is moved based on the condition information about the movement range, to the operation unit  105 .  
         [0036]    For example, the condition information on the movement range specifies that the image needs to be moved in left, upper, right and lower directions in that order by one pixel. Then, if the controller  104  judges that the same image continues to be displayed for a certain period of time, it sends the control signal, which causes the displayed image to move by one pixel in the left direction, to the operation unit  105 .  
         [0037]    After the image is moved in the left direction by one pixel, if the controller  104  judges that the same image continues to be displayed for a certain period of time, the controller  104  sends the control signal, which causes the displayed image to move by one pixel in the upper direction, to the operation unit  105 .  
         [0038]    After the image is moved in the upper direction by one pixel, if the controller  104  judges that the same image continues to be displayed for a certain period of time, the controller  104  sends the control signal, which causes the displayed image to move by one pixel in the right direction, to the operation unit  105 .  
         [0039]    After the image is moved in the right direction by one pixel, if the controller  104  judges that the same image continues to be displayed for a certain period of time, the controller  104  sends the control signal, which causes the displayed image to move by one pixel in the lower direction, to the operation unit  105 .  
         [0040]    The controller  104  repeats the above operation until it judges that the same image does not continue to be displayed for a certain period of time. In addition, the control signal may be a signal designed to move the start position of the image by one pixel. The movement order of the image is set as left, upper, right and lower directions, but the order may be changed. The pixel movement can be changed from a value of one pixel to another value to the extent that the user cannot visually detect the movement of the image.  
         [0041]    The operation unit  105  operates the display unit  106  so that the image signal transmitted from the signal processor  101  can be displayed on a desired position of the display unit  106  according to the control signal transmitted by the controller  104 . To display the image signal transmitted by the signal processor  101  on the display unit  106 , the operation unit  105  operates the display unit  106  in the same way as an existing display device does.  
         [0042]    The display unit  106  can be a CRT or an LCD display unit.  
         [0043]    The signal inputted from the exterior is the signal that is input by the user who uses a remote controller or a similar key entry unit (not shown).  
         [0044]    [0044]FIG. 2 is a flowchart showing a method to eliminate the afterimage according to the preferred embodiment of the present invention. With reference to FIG. 2, the method to eliminate the afterimage is described below.  
         [0045]    In step  201 , if the controller  104  judges that a signal that requests turning ON of the afterimage elimination mode is entered, it judges whether information of operation conditions that are necessary to eliminate the afterimage is entered and whether the operation conditions are set up in steps  202  through  205 .  
         [0046]    That is, the controller  104  identifies if time information is entered in step  202 . The time information refers to the information of the time previous to the time the afterimage is expected to happen, in case the same image continues to be displayed for a certain period of time. For example, on condition that the afterimage happens when the same image continues to be displayed for five minutes, the entered time information may be four minutes and fifty seconds.  
         [0047]    If the controller  104  judges that the time information is entered in step  202 , in step  203 , it sets the time information as movement determination time. That is, the controller  104  sets a time that can determine whether the displayed image is moved based on the time information.  
         [0048]    The controller  104  judges if the movement range information is entered in step  204 . The movement range information includes the movement direction and the movement amount of the displayed image. The movement direction may be upper, lower, left and right direction, and the movement range may be one pixel. In addition to the one pixel, the movement amount information may be any values so long as the movement of the image cannot be recognized by the user. In step  205 , the controller  104  sets the movement range of the image based on the information of the entered movement range.  
         [0049]    The entry order of the above information about the conditions may change. That is, after the information on the movement range is processed, the time information can be processed.  
         [0050]    In step  206 , the controller  104  judges if the same image continues to be displayed for the movement determination time in the same way as the method of the comparator  103  of FIG. 1. If the controller  104  judges that the same image continues to be displayed for the movement determination time in step  206 , it moves the image based on the information of the movement range in step  207 .  
         [0051]    The movement order and the movement method are performed as shown in the above description of the controller  104  of FIG. 1. That is, if the controller  104  judges first that the same image is maintained, it moves the image to the left by the pre-determined movement amount. Then, in step  208 , the controller  104  judges if the afterimage elimination mode is OFF. If the afterimage elimination mode is not OFF, step  206  is performed.  
         [0052]    If the controller  104  judges that the image is maintained for the pre-determined time in step  206 , it moves the image to the upper direction by the pre-determined movement amount.  
         [0053]    However, if the afterimage elimination mode is OFF in step  208 , the task is completed. In addition, if the controller  104  judges that the same image is not maintained for the time in step  206 , step  208  is performed.  
         [0054]    Therefore, steps  206  through  208  are performed repeatedly if the same image is maintained for the pre-determined time with the afterimage elimination mode ON. Steps  206  and  208  are performed repeatedly if the same image is not maintained for the pre-determined time with the afterimage elimination mode on.  
         [0055]    [0055]FIG. 2 shows that the present invention eliminates the afterimage depending on whether the afterimage elimination mode is ON or OFF. However, the present invention can eliminate the afterimage depending on whether the image position movement function is ON or OFF to eliminate the afterimage.  
         [0056]    According to the present invention, even though the same image is displayed on the display panel for a certain period of time, the afterimage can be prevented.  
         [0057]    Although a few preferred embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.