Patent Publication Number: US-2016225347-A1

Title: Liquid crystal display panel

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to a display panel and, in particular, to a liquid crystal display panel. 
     2. Related Art 
     With the progress of technologies, flat display devices have been widely applied to various kinds of fields. Especially, liquid crystal display (LCD) devices, having advantages such as compact structure, low power consumption, less weight and less radiation, gradually take the place of cathode ray tube (CRT) display devices, and are widely applied to various electronic products, such as mobile phones, portable multimedia devices, notebooks, LCD TVs and LCD screens. 
     Nowadays, the related products of the LCD device have become indispensible appliances. For example, LCD TVs are not only enlarged in panel size but also need to satisfy the strict requirement of the user&#39;s visual sense in image quality. Therefore, the developments of the companies are focused on the technology of presenting motion images. 
     In the conventional art, in order to solve the motion blur problem of the LCD device, the liquid crystal (LC) response is accelerated, and that is, the switching time of the LC molecules is reduced. Nowadays, a technique called the overdrive is used to accelerate the LC response, and the main principle thereof is to raise the driving voltage of the pixel to accelerate the rotation rate of the LC molecules and thus to improve the display quality of the motion image. 
     Moreover, in a conventional kind of pixel design, the lengthwise direction of the pixel electrode and the alignment direction of the LC are designed to form an angle (can be called the pre-twist angle). However, in such electrode design, if the extended overdrive technique is used to drive pixels and the driving voltage exceeds the maximum transmittance voltage of the pixel (the maximum transmittance voltage is the driving voltage whereby the pixel transmittance reaches maximum, which also can be called the white voltage), disclination will occur and the transmittance of the display panel is thus lowered down. 
     SUMMARY OF THE INVENTION 
     An objective of the invention is to provide an LCD panel whereby the response of the LC molecules can be accelerated and the switching time can be reduced on the premise that the transmittance is not reduced, and therefore the motion blur problem can be improved and the display quality can be enhanced. 
     A liquid crystal display (LCD) panel comprises a first substrate, a second substrate, a liquid crystal layer, a first electrode and an alignment layer. The liquid crystal layer is disposed between the first substrate and the second substrate. The first electrode is disposed on the first substrate and comprises at least a first electrode portion extended toward a first direction. The first electrode is a line-symmetry structure and has a symmetry axis. An alignment layer is disposed on the first electrode and an included angle formed between the symmetry axis of the first electrode and an alignment direction of the alignment layer is less than or equal to 2°, and the liquid crystal display (LCD) panel is driven by an overdrive technique. 
     In one embodiment, the first electrode is a pixel electrode or a common electrode of the LCD panel. 
     In one embodiment, the first electrode portion has two opposite sides, and the included angle between the tangent direction at a point of one of the sides and the symmetry axis of the first electrode is between 0° and 10°. 
     In one embodiment, the first electrode portion is a bar-like shape. 
     In one embodiment, the first electrode portion has two opposite sides, and the included angle between one of the sides and the symmetry axis of the first electrode is between 0° and 10°. 
     In one embodiment, the first electrode further includes a second electrode portion connected with the first electrode portion, a contact hole is disposed on the second electrode portion, the first electrode portion adjacent to the contact hole has a first width, the first electrode portion far from the contact hole has a second width, and the first width is greater than or equal to the second width. 
     In one embodiment, the included angle formed between the first direction and the alignment direction is less than or equal to 2°. 
     In one embodiment, the first electrode comprises a plurality of the first electrode portions and a second electrode portion connected with the first electrode portions, the included angle formed between the first direction and the alignment direction of the alignment layer is between 178° and 182°. 
     In one embodiment, the interval between the adjacent first electrode portions near the second electrode portion is less than that far from the second electrode portion. 
     In one embodiment, one of the first electrode portions has two opposite sides, and one of the opposite sides away from the symmetry axis is substantially parallel to the alignment direction. 
     In one embodiment, an included angle formed between a normal direction of the first substrate and a long axis direction of the liquid crystal molecules of the liquid crystal layer is larger than 85° and smaller than 90°. 
     In one embodiment, the LCD panel is a fringe field switching (FFS) LCD panel or an in-plane switch (IPS) LCD panel. 
     In one embodiment, the LCD panel is driven by an extended overdrive technique. 
     In one embodiment, the LCD panel further comprises a data line electrically connected with the first electrode, and the first direction is substantially parallel to the data line. 
     In one embodiment, the LCD panel further comprises a second electrode disposed between the first electrode and the first substrate, and the area of the second electrode is larger than that of the first electrode. 
     In one embodiment, the LCD panel further comprises a black matrix layer disposed between the first substrate and the second substrate, and a part of the first electrode portion is covered by the back matrix layer. 
     As mentioned above, in the LCD panel of the invention, the pixel is disposed between the first substrate and the second substrate and includes an alignment layer and a first electrode. The alignment layer is disposed on the first electrode, and the first electrode is a line-symmetry structure and has a symmetry axis and is disposed on the first substrate. Besides, the first electrode includes at least a first electrode portion extended towards a first direction, and the included angle formed between the symmetry axis and the alignment direction of the alignment layer is less than or equal to 2°. By the electrode structure of the pixel and the relation between the first electrode portion of the first electrode and the alignment direction of the alignment layer, the pixel won&#39;t have the additional disclination and the transmittance is thus not reduced when the LCD panel is driven by the overdrive technique, especially by the extended overdrive voltage. Therefore, the LCD panel of this invention can accelerate the response of the LCD molecules and reduce the switching time on the premise that the transmittance is not reduced, and therefore the motion blur problem can be improved and the display quality can be enhanced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1A  is a schematic sectional diagram of an LCD panel of an embodiment of the invention; 
         FIG. 1B  is a schematic top view of the first electrode of the LCD panel in  FIG. 1A ; 
         FIGS. 1C and 1D  are schematic diagrams showing the rotation of the LC molecules in relation to the first electrode in  FIG. 1B  when the pixel is not supplied and supplied with the driving voltage, respectively; 
         FIG. 1E  is a schematic diagram showing the pre-tilt condition of the LC molecules of an embodiment; 
         FIG. 2A  is a schematic diagram of a first electrode of another embodiment of the invention; 
         FIGS. 2B and 2C  are schematic diagrams showing the rotation of the LC molecules in relation to the first electrode in  FIG. 2A  when the pixel is not supplied and supplied with the driving voltage, respectively; 
         FIG. 3  is a schematic diagram showing the switching time of the LC molecules with the varied driving voltage of the pixel transmitted to the first electrode in  FIG. 2A  according to an embodiment of the invention; 
         FIG. 4  is a schematic sectional diagram of an LCD panel of another embodiment of the invention; and 
         FIG. 5  is a schematic diagram of an LCD device of an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
       FIG. 1A  is a schematic sectional diagram of an LCD panel  1  of an embodiment of the invention, and  FIG. 1B  is a schematic top view of the first electrode  141  of the LCD panel  1  in  FIG. 1A . 
     As shown in  FIGS. 1A and 1B , the LCD panel  1  of this embodiment can be a fringe field switching (FFS) LCD panel or an in-plane switch (IPS) LCD panel, or another LCD panel including the liquid crystal with horizontal driving type. Herein for example, the LCD panel  1  is a FFS LCD panel. Moreover, a first direction D 1 , a second direction D 2  and a third direction D 3  are shown in  FIGS. 1A, 1B , and any two of them are perpendicular to each other. The first direction D 1  is substantially parallel to the extending direction of the data line D of the LCD panel  1 , the second direction D 2  is substantially parallel to the extending direction of the scan line (not shown) of the LCD panel  1 , and the third direction D 3  is perpendicular to the first direction D 1  and the second direction D 2 . 
     The LCD panel  1  is driven by an overdrive technique so that the motion blur problem can be reduced and the display quality can be enhanced, especially when driven by the extended overdrive voltage, the disclination phenomenon will be improved. Every stable state of the LC molecules corresponds to a specific voltage, so when the voltage of the pixel electrode is changed, the LC molecules will reach the target state after a certain response time instead of immediately rotating to the target state. However, the higher voltage difference results in the rapid rotation rate of the LC molecules (i.e. the shorter switching time). Accordingly, the overdrive technique is just to supply a driving voltage higher than the voltage of the target state in the beginning to accelerate the rotation of the LC molecules and therefore the response time is reduced. 
     As shown in  FIG. 1A , the LCD panel  1  includes a first substrate  11 , a second substrate  12  and a liquid crystal layer  13  disposed between the first substrate  11  and the second substrate  12 . Each of the first substrate  11  and the second substrate  12  is made by a transparent material, and can be a glass substrate, a quartz substrate or a plastic substrate for example. The LCD panel  1  further includes a pixel array (not shown), which is disposed between the first substrate  11  and the second substrate  12  and includes at least a pixel (or called sub-pixel) P. Here for example, the pixel array includes a plurality of pixels P ( FIG. 1A  just shows a pixel P), and the pixels P are arranged into a matrix. Furthermore, the LCD panel  1  can further include a plurality of scan lines (not shown) and a plurality of data lines D, and the scan lines and the data lines D cross each other and are substantially perpendicular to each other to define the regions of the pixels P. As mentioned above, the extending direction of the data line D of this embodiment is substantially parallel to the first direction D 1 , and the extending direction of the scan line is substantially parallel to the second direction D 2 . 
     In addition to a liquid crystal layer  13  disposed between the first substrate  11  and the second substrate  12 , the pixel P of this embodiment further includes a first electrode  141 , a passivation layer  142 , a second electrode  143 , a planarization layer  144 , an inter-layer dielectric layer  145  and a buffer layer  146 . The buffer layer  146 , the inter-layer dielectric layer  145 , the planarization layer  144 , the second electrode  143 , the passivation layer  142  and the first electrode  141  are formed sequentially, from bottom to top, on the side of the first substrate  11  facing the second substrate  12 . 
     The buffer layer  146  is disposed on the first substrate  11 , and the inter-layer dielectric layer  145  covers the buffer layer  146 . The adjacent two data lines D are disposed on the inter-layer dielectric layer  145  and on the two sides of the pixel P. The planarization layer  144  covers the data line D, and the second electrode  143  is disposed on the planarization layer  144 . Moreover, the passivation layer  142  covers the second electrode  143  and the first electrode  141  is disposed on the passivation layer  142 . Therefore, the second electrode  143  can be disposed between the passivation layer  142  and the planarization layer  144 , and the passivation layer  142  is disposed between the first electrode  141  and the second electrode  143 , so as to avoid the short circuit of the second electrode  143  with the first electrode  141 . The materials of the passivation layer  142 , planarization layer  144 , inter-layer dielectric layer  145  and buffer layer  146  include, for example, SiOx, SiNx or other insulating materials, but this invention is not limited thereto. The first electrode  141  and the second electrode  143  are both a transparent conductive layer, and the materials thereof are, for example but not limited to, indium-tin oxide (ITO) or indium-zinc oxide (IZO). In this embodiment, the first electrode  141  is a pixel electrode and electrically connected with (not shown) the data line D, and the second electrode  143  is a common electrode. In this embodiment, since the second electrode  143  is a continuous layer structure and covers the planarization layer  144  and the data lines, the electric field formed due to the different driving voltages of the two adjacent data lines D will be shielded by the continuous second electrode (common electrode)  143  so as not to affect the operation of the first electrode (pixel electrode)  141 , so favorably, the area of the second electrode  143  is larger than that of the first electrode  141 . However, in other embodiments, the first electrode  141  may be a common electrode while the second electrode  143  is a pixel electrode. 
     The pixel P can further include a black matrix layer BM and a color filter layer  147 . The black matrix layer BM is disposed between first substrate  11  and the second substrate  12 , and is disposed corresponding to the data lines D. The black matrix layer BM is made by opaque material, such as resin or metal (e.g. Cr, chromium oxide, or Cr—O—N compound) for example. In this embodiment, the black matrix layer BM is disposed on the side of the second substrate  12  facing the first substrate  11  and over the data lines D along the first direction D 1 . Accordingly, the black matrix layer BM can cover the data lines D in a top view of the LCD panel  1 . Since the black matrix layer BM is opaque, a corresponding opaque area can be formed on the second substrate  12  so as to define a transparent area (i.e. the area corresponding to the color filter layer  147 ). The color filter layer  147  is disposed on the side of the second substrate  12  facing the first substrate  11  or disposed on the first substrate  11 . In this embodiment, the black matrix layer BM and the color filter layer  147  are both disposed on the second substrate  12 , and the color filter layer  147  is disposed between the adjacent portions of the black matrix layer BM. In other embodiments, the black matrix layer BM or the color filter layer  147  may be disposed on the first substrate  11  for making a BOA (BM on array) substrate or a COA (color filter on array) substrate. To be noted, the above-mentioned structure of the substrate is just for example but not for limiting the scope of the invention. 
     Moreover, the pixel P of this embodiment can further include a protection layer  148  (e.g. over-coating), which can cover the black matrix layer BM and the color filter layer  147 . The protection layer  148  can include photoresist material, resin material or inorganic material (e.g. SiOx/SiOx), protecting the black matrix layer BM and the color filter layer  147  from being damaged during the subsequent processes. Furthermore, the pixel P can further include alignment layers  151 ,  152 . The alignment layer  151  is disposed on the first substrate  11  and covers the first electrode  141  and the passivation layer  142 , and the alignment layer  152  is disposed on the second substrate  12  and covers the protection layer  148 , and besides, the liquid crystal layer  13  is disposed between the alignment layers  151 ,  152 . 
     When the scan lines of the LCD panel  1  receive a scan signal sequentially, the thin film transistor (TFT) (not shown) corresponding to each of the scan lines can be enabled. Then, the data signals can be transmitted to the corresponding pixel electrodes through the data lines D and the LCD panel  1  can display images accordingly. In this embodiment, the over-drive voltage can be transmitted to the first electrode  141  of each of the pixels P through each of the data lines D, and an electric filed can be thus formed between the first electrode  141  and the second electrode  143  to drive the LC molecules of the liquid crystal layer  13  to rotate on the plane that is in the first direction D 1  and the second direction D 2 . Therefore, the light can be modulated and the LCD panel  1  can display images accordingly. 
     As shown in  FIG. 1B , the first electrode (or abbreviated to the electrode)  141  of this embodiment is a line-symmetry structure to have a symmetry axis L. Herein, the “line-symmetry structure” indicates the parts of the first electrode  141  on the two sides of the symmetry axis L are symmetric with each other. Moreover, the first electrode  141  includes at least a first electrode portion  1411  extended towards the first direction D 1 . Herein for example, the first electrode  141  includes a first electrode portion  1411  extended towards the first direction D 1 , and the first direction D 1  is also parallel to the symmetry axis L. For example, the first electrode portion  1411  is bar-like shape. In this embodiment, the first direction D 1  and the alignment direction A of the alignment layer  151  are substantially parallel to each other. The alignment direction A is just the projection of the long axis direction of the LC molecules on the first substrate  11  during the rubbing process or photo alignment process. In other words, in this embodiment, the alignment direction A is substantially parallel to the extending direction of the data line D and perpendicular to the extending direction (second direction D 2 ) of the scan line. However, for the tolerance of the process, the included angle between the symmetry axis L and the alignment direction A of the alignment layer  151  is defined as less than or equal to 2 degrees (i.e. 0°≦included angle≦2°) in this embodiment. In one embodiment, the black matrix layer BM can cover a part of the bar-like first electrode portion  1411  to improve the transmittance. 
     In this embodiment, the first electrode portion  1411  includes two opposite sides L 1 , L 2 . Along the second direction D 2 , and the two opposite sides L 1 , L 2  are equidistant from the adjacent data line D (not shown in  FIG. 1B ). Moreover, the included angle (not marked) formed between the tangent direction at one point of the sides L 1 , L 2  and the symmetry axis L is between 0° and 10°. In other words, although the first electrode portion  1411  is a bar-like electrode extended towards the first direction D 1 , the sides L 1 , L 2  thereof are not both parallel to the symmetry axis L (maybe one is parallel and the other is not), so that the included angle between the tangent direction of at least a part of the sides L 1 , L 2  and the symmetry axis L is between 0° and 10° (larger than 0° and smaller than 10°). Thereby, when the first electrode  141  is supplied with the driving voltage, the rotation rate of the LC molecules can be faster than the case of the completely parallel sides. 
     Moreover, the first electrode  141  of this embodiment further includes a second electrode portion  1412  connected with the first electrode portion  1411 , and the first direction D 1  is the direction away from the second electrode portion  1412 . The second electrode portion  1412  is configured with at least a contact hole H, and the first electrode  141  is electrically connected with the TFT (not shown) corresponding to the pixel P through the contact hole H. Herein, the TFT is the driving TFT of the pixel P, and when the TFT is enabled, the gray-level voltage of the pixel P will be transmitted to the first electrode  141  through the source or drain of the TFT. Furthermore, in the second direction D 2 , the first electrode portion  1411  adjacent to the second electrode portion  1412  has a first width d 1 , the first electrode portion  1411  far from the second electrode portion  1412  has a second width d 2 , and the first width d 1  is greater than or equal to the second width d 2  (d 1 ≧d 2 ). Moreover, in one embodiment, the first width d 1  can be greater than the second width d 2 . In another embodiment, the first width d 1  can be equal to the second width d 2 . When the first width d 1  is greater than the second width d 2 , the rotation rate of the LC molecules can be faster than the case where the first width d 1  is equal to the second width d 2  (i.e. the response time of the LC molecules is shorter). 
     To be noted, in this embodiment, the alignment direction A of this embodiment is the direction from the contact hole H to the end of the first electrode portion  1411 . In other words, if the rightward extending direction from the second direction D 2  is regarded as 0°, the alignment direction A of this embodiment is the direction of the counterclockwise 90° (i.e. the upward extending direction in  FIG. 1B ). Therefore, the included angle formed between the first direction D 1  and the alignment direction A is also less than or equal to 2°. 
       FIGS. 1C and 1D  are schematic diagrams showing the rotation of the LC molecules in relation to the first electrode  141  in  FIG. 1B  when the pixel P is not supplied and supplied with the driving voltage, respectively. 
     As shown in  FIG. 1D , when the driving voltage is applied, the rotation of the LC molecules shows symmetry in relation to the symmetry axis L. Besides, through the experimental demonstration, the additional disclination will not occur in the pixel P when the pixel P is driven by extended driving voltage, so that the transmittance can not be affected. 
     Moreover, from the experimental result on the design of the pixel P of this embodiment, it can be seen the additional disclination will be generated in the pixel P if the LC molecules have no pre-tilt angle, so that the transmittance is reduced. Therefore, the pre-tilt angle of the LC molecules of this embodiment needs to be larger than 0° and less than 5°. In other words, as shown in  FIG. 1E , which is a schematic diagram showing the pre-tilt condition of the LC molecules of an embodiment, the third direction D 3  is parallel to a normal direction of the first substrate  11 , and the included angle θ formed between the normal direction of the first substrate  11  and the long axis direction D 4  of the LC molecules needs to be between 85° and 90° (85°&lt;θ&lt;90°). Thereby, when the first electrode  141  of the pixel P is overdriven, the additional disclination won&#39;t be generated and the transmittance can&#39;t be reduced. 
       FIG. 2A  is a schematic diagram of a first electrode  141  of another embodiment of the invention, and  FIGS. 2B and 2C  are schematic diagrams showing the rotation of the LC molecules in relation to the first electrode  141  in  FIG. 2A  when the pixel is not supplied and supplied with the driving voltage, respectively. 
     The main difference from the first electrode  141  in  FIG. 1B  is that the first electrode  141  in  FIG. 2A  includes two first electrode portions  1411  and a second electrode portion  1412  connected with the first electrode portions  1411 . For example, the first electrode portions are bar-like shape. The included angle between the symmetry axis L and the alignment direction A of the alignment layer  151  is less than or equal to 2 degrees (i.e. 0°≦included angle≦2°). In this embodiment, the alignment direction A is from the end of the first electrode portion  1411  to the contact hole H, so that the included angle between the first direction D 1  and the alignment direction A of the alignment layer  151  is larger than or equal to 178° and less than or equal to 182°. In other words, if the rightward extending direction from the second direction D 2  is regarded as 0°, the alignment direction A of this embodiment is favorably the direction of the counterclockwise 270° (i.e. the downward extending direction in  FIG. 2A ). The reason thereof is that the pixel could have additional disclinations with the design of the first electrode  141  including two first electrode portions  1411 , by the experimental demonstration, if the alignment direction A is the direction of the counterclockwise 90°. 
     Furthermore, in this embodiment, the interval d 3  between the adjacent first electrode portions  1411  near the second electrode portion  1412  is less than the interval d 4  between the adjacent first electrode portions  1411  far from the second electrode portion  1412  (the first electrode  141  has a U-shaped or V-shaped divergent form). In other words, the first electrode portions  1411  farther from the contact hole H have a larger interval in the second direction D 2 . Moreover, although the first electrode portions  1411  are bar-like electrodes extended towards the first direction D 1 , the sides adjacent to each other thereof are not all parallel to the first direction D 1 . Moreover, one of the first electrode portions  1411  has two opposite sides, and one of the opposite sides away from the symmetry axis L is substantially parallel to the alignment direction A. In other words, the included angle between the inner side (the side adjacent to the symmetry axis L) of the first electrode portion  1411  and the symmetry axis L is between 0° and 10° (not marked), and the outer side (the side away from the symmetry axis L) of the first electrode  141  is substantially parallel to the alignment direction A. 
       FIG. 3  is a schematic diagram showing the switching time of the LC molecules with the varied driving voltage of the pixel transmitted to the first electrode  141  in  FIG. 2A  according to an embodiment of the invention. 
     In this embodiment, the driving voltage is 4V when the pixel transmittance reaches the maximum. Therefore, the extended overdrive technique corresponds to the driving voltage higher than 4V (white voltage). As shown in  FIG. 3 , the switching time of the LC molecules in the case of the driving voltage changed from the beginning 0V to 7V (higher than 4V) is obviously shorter than that in the case of the driving voltage changed from 0V to 4V. Besides, even though the driving voltage reaches 7V, the LC molecules of the pixel have no more abnormal arrangement (i.e. disclination) by the experimental demonstration. Therefore, the additional disclination won&#39;t be generated and the panel transmittance is thus not reduced, so the side effect (lower transmittance) will be eliminated when the LCD panel is with fast response time. 
       FIG. 4  is a schematic sectional diagram of an LCD panel  1   a  of another embodiment of the invention. 
     In this embodiment, the first electrode  141   a  of the pixel Pa of the LCD panel  1   a  also has a line-symmetry structure, and the first direction D 1  which the first electrode portion  1411  is extended towards is substantially parallel to the alignment direction A of the alignment layer  151 . 
     The main difference between the LCD panel  1   a  of this embodiment and the LCD panel  1  in  FIG. 1A  is that the first electrode  141   a  of the pixel Pa of the LCD panel  1   a  is a common electrode and the second electrode  143   a  is a pixel electrode. 
     Other technical features of the LCD panel  1   a  can be comprehended by referring to the above-mentioned LCD panel  1  and therefore the related illustration is omitted here for conciseness. 
       FIG. 5  is a schematic diagram of an LCD device  2  of an embodiment of the invention. 
     As shown in  FIG. 5 , the LCD device  2  includes an LCD panel  3  and a backlight module  4  disposed opposite the LCD panel  3 . The LCD panel  3  can be any of the above-mentioned LCD panels  1 , la or their variation so the description thereof is omitted here. When the backlight module  4  emits the light E passing through the LCD panel  3 , the pixels of the LCD panel  3  can display colors to form images accordingly. 
     Summarily, in the LCD panel of the invention, the pixel is disposed between the first substrate and the second substrate and includes an alignment layer and a first electrode. The alignment layer is disposed on the first electrode, and the first electrode is a line-symmetry structure and has a symmetry axis and is disposed on the first substrate. Besides, the first electrode includes at least a first electrode portion extended towards a first direction, and the included angle formed between the symmetry axis and the alignment direction of the alignment layer is less than or equal to 2°. By the electrode structure of the pixel and the relation between the first electrode portion of the first electrode and the alignment direction of the alignment layer, the pixel won&#39;t have the additional disclination and the transmittance is thus not reduced when the LCD panel is driven by the overdrive technique, especially by the extended overdrive voltage. Therefore, the LCD panel of this invention can accelerate the response of the LCD molecules and reduce the switching time on the premise that the transmittance is not reduced, and therefore the motion blur problem can be improved and the display quality can be enhanced. 
     Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.