Abstract:
A method for adjusting display response time includes: a) providing an overdrive table; b) determining a response time setting status; c) changing the overdrive table according to the response time setting status; d) receiving video data; and e) with reference to the video data, looking up the overdrive table changed in step c) to obtain overdrive video data. A display device that implements the method is also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority of Taiwanese application no. 096105216, filed on Feb. 13, 2007. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to flat panel displays, more particularly to a display device and method for adjusting response time of a flat panel display. 
         [0004]    2. Description of the Related Art 
         [0005]    Liquid crystal displays have advantages of slim size, lightweight, low power consumption, low radiation, and high compatibility with semiconductor manufacturing technology, and are widely adopted. 
         [0006]    Under varied alignment conditions of liquid crystal molecules, optical characteristics of light passing through a liquid crystal layer may be different. Hence, through application of electric fields to alter the alignment conditions of liquid crystal molecules, the amount of light that is allowed to pass can be controlled so as to generate different intensities of outputted light. A liquid crystal display uses this characteristic to generate different intensities of red, green, and blue light when displaying an image. The applied electric field and generated intensity for every color component of each pixel can be expressed by a pixel value. For instance, (R, G, B) represents red, green and blue color components, where (0, 0, 0) indicates complete darkness (i.e., the color of black), while (255, 255, 255) indicates complete illumination (i.e., the color of white). 
         [0007]    Since the alteration of the alignment conditions of liquid crystal molecules is a prerequisite to changes in the intensity of outputted light, the response speed is relatively slow; that is, when a pixel is changed from an initial pixel value to a target pixel value, a period of time is required to reach the target pixel value. Therefore, when the liquid crystal display is used to display fast-changing dynamic images (such as when watching a DVD film or playing a computer game) the user is likely to perceive poor display quality (for example, residual images or discontinuities are present on the screen). 
         [0008]    In general, an overdrive scheme is used to reduce liquid crystal response time. For instance, when a pixel is to be changed from an initial pixel value (40, 40, 40) to a target pixel value (80, 80, 80), an electric field corresponding to an overdrive pixel value (120, 120, 120) is applied to the liquid crystal material so that the pixel is able to reach the target pixel value within a designated time period. On the other hand, when a pixel is to be changed from an initial pixel value (120, 120, 120) to a target pixel value (80, 80, 80), an electric field corresponding to an overdrive pixel value (40, 40, 40) is applied to the liquid crystal material so that the pixel is able to reach the target pixel value within a designated time period. 
         [0009]    In order to obtain the overdrive pixel value in an efficient manner, an overdrive table is usually established beforehand and is looked up with reference to the initial and target pixel values, so as to obtain the overdrive pixel value. 
         [0010]    However, since the overdrive table is fixed for each liquid crystal display and cannot be adjusted by the user, use of the overdrive table can only cause the overall liquid crystal response time to reach a preset fixed value. In addition, different users have varied viewing preferences. Therefore, when the display quality is poor, such as when the liquid crystal response time is not fast enough for the user, adjustments cannot be made to satisfy user preference. 
         [0011]    Furthermore, when manufacturing liquid crystal displays, a source overdrive table is first generated according to average characteristics of products, and the source overdrive table is subsequently fine-tuned for each product to achieve uniform display effect. Since a lot of time is spent on fine-tuning, manufacturing costs are undesirably increased. 
       SUMMARY OF THE INVENTION 
       [0012]    Therefore, an object of the present invention is to provide a display device and method for adjusting response time of a flat panel display, which allow users to perform display response time adjustments to suit individual viewing preferences, and also reduce manufacturing costs. 
         [0013]    According to one aspect of the present invention, there is provided a method for adjusting display response time that comprises the steps of: 
         [0014]    a) providing an overdrive table; 
         [0015]    b) determining a response time setting status; 
         [0016]    c) changing the overdrive table according to the response time setting status; 
         [0017]    d) receiving video data; and 
         [0018]    e) with reference to the video data, looking up the overdrive table changed in step c) to obtain overdrive video data. 
         [0019]    According to another aspect of the present invention, there is provided a method for adjusting display response time that comprises the steps of: 
         [0020]    a) providing an overdrive table; 
         [0021]    b) determining a response time setting status; 
         [0022]    c) receiving video data; 
         [0023]    d) looking up the overdrive table with reference to the video data; and 
         [0024]    e) adjusting lookup result obtained in step d) with reference to the response time setting status to obtain overdrive video data. 
         [0025]    According to yet another aspect of the present invention, there is provided a display device that comprises a response time setting unit, a control unit, and a display controller. 
         [0026]    The control unit is coupled to the response time setting unit, maintains at least one overdrive table, and determines a response time setting status according to a setting of the response time setting unit. 
         [0027]    The display controller receives video data, and generates overdrive video data for the video data through table lookup. The overdrive video data is related to the at least one overdrive table and is further related to the response time setting status. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which: 
           [0029]      FIG. 1  is a block diagram of the preferred embodiment of a flat panel display device according to the present invention; 
           [0030]      FIG. 2  is a schematic diagram, which illustrates the use of a slider bar to indicate a response time setting status; and 
           [0031]      FIG. 3  is a schematic diagram, which illustrates the use of numerical symbols selectable to indicate a plurality of preset response time setting statuses, respectively. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0032]      FIG. 1  shows the preferred embodiment of a flat panel display device  100  according to the present invention. In this embodiment, the flat panel display device  100  is based on liquid crystal display (LCD) technology, and can be one of a LCD monitor, a LCD TV, and a digital TV with a liquid crystal display panel. However, it should be apparent to those skilled in the art that the present invention is not limited for application to the above examples and can be further applied to other flat panel display technologies (such as plasma display technology) and non-flat panel display technologies, etc., that employ overdrive techniques. As shown in  FIG. 1 , the flat panel display device  100  includes a control unit  110  (which is implemented as a micro-controller unit, or MCU), a display controller  120 , and a memory  130 . In this embodiment, the control unit  110  and the display controller  120  access the memory  130  through a bus  140 . In this embodiment, the control unit  110  and the display controller  120  are implemented using separate integrated circuit chips. However, in other embodiments of this invention, the control unit  110  and the display controller  120 , as well as the memory  130 , may be integrated into a single integrated circuit chip. The control unit  110  is a processor that operates in accordance with a command cluster. Depending on actual application, the display controller  120  can be a LCD controller, a LCD TV controller, a digital TV controller, etc. 
         [0033]    In this embodiment, the control unit  110  has a source overdrive table  111  pre-established therein. During initialization setting or at any other appropriate point of time, the control unit  110  loads content of the source overdrive table  111  into the memory  130  to result in a temporary overdrive table  131 , which is to be accessed by the display controller  120 . In general, for a flat panel display device  100 , the display controller  120  is used to receive video data of a video source via an interface unit  150 , to perform video processing such as de-interlacing, scaling, color and contrast processing, etc., on the video data received thereby, and to output processed video data for driving a display panel  160  so as to display an image. In order to adjust (usually, to speed up) display response time, aside from the aforesaid video processing, the display controller  120  performs table lookup using the temporary overdrive table  131  stored in the memory  130  with reference to initial pixel values and target pixel values in corresponding positions of two adjacent image frames or image fields of the video data (which could be pre-processing video data, video data that is being processed, or processed video data), so as to output overdrive pixel values for response time adjustment. 
         [0034]    The preferred embodiment of the present invention provides flexibility whenever the user intends to adjust the response time to suit individual viewing preferences. As shown in  FIG. 1 , the user can operate a control panel  170  that is commonly found on the flat panel display device  100  or a remote controller  190  that is operably associated with a remote control unit  180  to alter response time setting of the flat panel display device  100 . In accordance with changes made by the user to the value of the response time setting, the control unit  110  will make corresponding changes to the temporary overdrive table  131  stored in the memory  130  such that there will be corresponding changes in subsequent table lookup results by the display controller  120 , in order to finally adjust the display panel response time. 
         [0035]    Preferably, an onscreen display setup menu generated by an onscreen display (OSD) unit  125  of the display controller  120  is made available to the user when setting is conducted through the control panel  170  and/or the remote controller  190 . Referring to  FIG. 2 , the onscreen display setup menu may incorporate a slider bar to indicate response time setting status. Alternatively, referring to  FIG. 3 , the onscreen display setup menu may present a plurality of numerical symbols, which are available for selection, to indicate a plurality of preset response time setting statuses, respectively. It is noted that other schemes may be utilized to indicate the response time setting status. To update the temporary overdrive table  131 , values in the source overdrive table  111  may be multiplied by a ratio value that corresponds to the response time setting status, and the new overdrive table generated as a result of the multiplication is used to update the temporary overdrive table  131  in the memory  130 . Alternatively, a plurality of the source overdrive tables  111  may be pre-established in the control unit  110 ; then, one of the source overdrive tables  111  is selected according to the response time setting status to update the temporary overdrive table  131  in the memory  130 . 
         [0036]    In this embodiment, when adjusting the display panel response time of the flat panel display device  100 , the temporary overdrive table  131  in the memory  130  is updated such that the display controller  120  performs table lookup using the updated temporary overdrive table  131 . However, the present invention should not be limited thereto. In other embodiments of the present invention, the overdrive table  131  in the memory  130  is not updated by the control unit  110 ; instead, with reference to the response time setting status decided by the user, the control unit  110  generates a corresponding control signal for the display controller  120 . In response to the control signal, the display controller  120  performs computation processing, such as multiplying the table lookup result by a ratio value corresponding to the response time setting status, so as to change the response time. Moreover, it is also possible to adjust pixel values according to the control signal, and then perform table lookup with reference to the adjusted pixel values. Therefore, adjustment of the response time does not involve the memory  130 , and the display controller  120  can use the original source table  111  in the control unit  110  for table lookup. 
         [0037]    In sum, in the preferred embodiment of this invention, through change of a response time setting status, the user is able to change outputted overdrive pixel values so as to achieve a desired response time and a preferred viewing effect. In addition, since users are able to change the response time setting status on their own, manufacturers are no longer required to fine-tune source overdrive tables of individual liquid crystal displays, thereby resulting in lower manufacturing costs. 
         [0038]    While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.