Source: http://www.patentsencyclopedia.com/app/20120281176
Timestamp: 2018-06-22 22:51:27
Document Index: 411110661

Matched Legal Cases: ['Application No. 1999', 'art 261', 'art 262', 'art 261', 'art 263', 'art 262', 'arts 261', 'arts 262', 'arts 261', 'arts 262']

Patent application number: 20120281176
A liquid crystal display includes a first insulating substrate. A pixel electrode is formed on a top surface of the first insulating substrate. The pixel electrode has a first opening pattern at each pixel area. The pixel electrode is substantially rectangular in shape with first second long sides, and first and second short sides. The pixel electrode is divided into an upper region defined by the first and second long sides and first short side, and a lower region defined by the first and second long sides and second short side. A common electrode is formed on a bottom surface of a second insulating substrate, and has a second opening pattern at each pixel area. The first and second opening patterns each have a plurality of openings, the openings of the first opening pattern and the second opening pattern being alternately arranged parallel to each other.
1. A liquid crystal display, comprising: a first substrate on which a first electrode is formed; a second substrate on which a second electrode is formed; and liquid crystal positioned between the first and second substrates, wherein: the first electrode includes a first domain forming member and the second electrode includes a second domain forming member, the first domain forming member includes a first trunk portion, and the second domain forming member includes a second trunk portion, wherein the first and second trunk portions are substantially parallel to a first side of the first electrode, and at least a portion of the first trunk portion and a portion of the second trunk portion overlap each other.
4. The liquid crystal display of claim 1, wherein the second domain forming member further includes first and second branches extending from the second trunk portion, and first and second sub-branches respectively extending from ends of the first and second branches.
5. The liquid crystal display of claim 4, wherein the first and second sub-branches are oblique to the first and second branches and extend along a second side of the first electrode substantially perpendicular to the first side.
6. The liquid crystal display of claim 5, wherein the first domain forming member includes opening patterns and the second domain forming member includes protrusions.
7. The liquid crystal display of claim 1, wherein the second domain forming member further includes an upper body including a first limb extending therefrom along the first side of the first electrode and oblique to the upper body.
8. The liquid crystal display of claim 7, wherein the upper body extends from the first side of the first electrode to a second side of the first electrode, wherein the first side is substantially perpendicular to the second side.
9. The liquid crystal display of claim 7, wherein the upper body extends from the first side of the first electrode to a second side of the first electrode, wherein the first side is shorter than the second side.
10. The liquid crystal display of claim 7, wherein the upper body further includes a second limb extending therefrom along a second side of the first electrode and oblique to the upper body.
11. The liquid crystal display of claim 10, wherein the second domain forming member further includes a lower body including a third limb extending therefrom along the second side of the first electrode and oblique to the lower body.
12. The liquid crystal display of claim 7, wherein the second domain forming member further includes a lower body including a second limb extending therefrom along a second side of the first electrode and oblique to the lower body.
13. The liquid crystal display of claim 12, wherein the second side is opposite to the first side.
14. The liquid crystal display of claim 7, wherein the second domain forming member further includes a lower body including a second limb extending therefrom substantially parallel to the first limb and oblique to the lower body.
15. The liquid crystal display of claim 14, wherein the upper and lower bodies are formed in a pixel area and are separated from domain forming members of an adjacent pixel area.
16. The liquid crystal display of claim 10, at least on portion of the first limb and the second limb are overlapped at least one of edges of the pixel electrode.
[0001] This application is a Continuation of U.S. patent application Ser. No. 12/502,854 filed on Jul. 14, 2009, which is a Continuation of U.S. patent application Ser. No. 11/557,670 filed on Nov. 8, 2006, which is a divisional of U.S. patent application Ser. No. 11/175,322, filed on Jul. 7, 2005, now U.S. Pat. No. 7,154,577, which is a continuation of U.S. Pat. No. 6,952,247 issued on Oct. 4, 2005, which is a continuation of U.S. Pat. No. 6,738,120 issued on May 18, 2004, which claims priority to Korean Patent Application No. 1999-42216, filed on Oct. 1, 1999, the disclosures of which are all incorporated by reference herein in their entirety.
[0008] FIG. 1 illustrates a schematic view of opening patterns formed at pixel and common electrodes in a prior art liquid crystal display. As shown in FIG. 1, the pixel and common electrodes are formed with opening patterns 1 and 2, respectively. Each of the opening patterns 1 and 2 is formed in a V-shape and is arranged with ends of the V-shapes in proximity to each other so that roughly a diamond shape is formed by the opening patterns 1 and 2. Liquid crystal material is injected between the pixel electrode and the common electrode, and liquid crystal molecules 3 are aligned perpendicular to the electrodes.
[0010] The slow response speed of liquid crystal molecules generates after-images when displaying moving pictures on the screen. There is therefore a need to increase the response speed of liquid crystal molecules.
[0015] The first and second opening patterns each have a middle linear portion. The linear portions of the first and second opening patterns are alternately arranged parallel to each other. The first opening pattern includes a first opening formed in the upper region of the pixel electrode in a first direction. A second opening portion is formed in the lower region of the pixel electrode in a second direction normal to the first direction. The second opening pattern includes a first trunk opening formed in the upper region of the common electrode in the first direction, and a second trunk opening formed in the lower region of the common electrode in the second direction. The first direction is slanted at a predetermined angle with respect to the long or short sides of the pixel electrode. The second opening pattern further includes first branch openings overlapping the first and second short sides of the pixel electrode, and second branch openings overlapping the first and second long sides of the pixel electrode. The first opening pattern further includes a third opening formed where the upper and lower regions of the pixel electrode meet while proceeding parallel to the first and second short sides of the pixel electrode. The second branch openings each have a width greater than that of the trunk opening portion. The first direction is parallel to one of the long and short sides of the pixel electrode. The first and second trunk openings each have opposite ends respectively with a gradually enlarged width. One of the second trunk openings overlaps the second short side of the pixel electrode. The first opening has opposite ends respectively with a gradually reduced width.
[0019] A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by referring to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or the similar components, wherein:
[0024] FIG. 4A is a schematic view of an opening pattern of a pixel electrode according to the other example, of the present invention;
[0031] FIG. 6B is a schematic view of an opening pattern of a common electrode according to the other example of the present invention;
[0033] FIG. 7A is a schematic view of an opening pattern of a pixel electrode according to the other example of the present invention;
[0045] FIG. 11 are schematic views of various types of opening patterns for demonstrating the affect of opening pattern width and spacing on response speed and brightness;
[0064] As shown in FIG. 2, the liquid crystal display includes lower and upper substrates 10 and 20 arranged substantially in parallel with a predetermined gap therebetween. Liquid crystal material is injected between the lower and upper substrates 10 and 20 to farm a liquid crystal layer. The liquid crystal material is comprised of liquid crystal molecules 30. A long axis of liquid crystal molecules 30 is oriented normal to the lower and upper substrates 10 and 20. Both the lower and upper substrates 10 and 20 are transparent material such as glass.
[0067] The LCD can be structured to operate in a normally black mode by arranging the lower polarizer film 14 and the upper polarizer film 24 so that the polarizing directions of each film are perpendicular to each other. It can also be structured to operate in a normally white, mode by arranging the polarizing directions of each film to be parallel with each other. In the following description, only the arrangement for a normally black mode will be described. However, the invention can be also applied to the normally white mode. FIG. 3A shows a schematic view of opening patterns of the pixel and common electrodes 12 and 23 according to one example of the present invention. As shown in FIG. 3A, an opening pattern 101 of the pixel electrode 12 and an opening pattern. 102 of the common electrode are respectively formed in a straight line. The opening pattern 101 is substantially parallel to the opening pattern 102. With this structure, the liquid crystal molecules 30 are arranged in parallel as a result of a fringe field generated by the opening patterns 101 and 102. Furthermore, the liquid crystal molecules 30 move into the parallel arrangement in a single step, thereby enabling a rapid response speed.
[0068] However, the above structure develops texture over a wide area of the screen. It is also possible that white after-images appear on the screen. When a screen displays a dark color on a bright background and then returns to the color of the bright background, it becomes brighter momentarily than the bright background. It is called as "white after-image". FIG. 3B shows a schematic view of opening patterns of the pixel and common electrodes 12 and 23 according to another example of the present invention.
[0070] In the following examples, opening patterns of the pixel and common electrodes 12 and 23 will be described with reference to one pixel area. In a single pixel area, the pixel electrode 12 is substantially rectangular in shape having first and second long sides, respectively corresponding to left and right sides (in the drawings) of the pixel electrode 12. It has first and second short sides, respectively corresponding to top and bottom sides (in the drawings) of the pixel electrode 12. It also has a first corner formed by the ends of the first long side and the first short side, a second corner formed by the ends of the first short side and the second long side, a third corner formed by the ends of the second long side and the second short side, and a fourth corner formed by the ends of the first long side and the second short side. Further, the pixel electrode 12 includes an upper region and a lower region, the upper region corresponding to an upper half (in the drawings) of the pixel electrode 12 and defined by the first long side, the second long side and the first short side, and the lower region corresponding to a lower half (in the drawings) of the pixel electrode 12 and defined by the first long side, the second long side and the second short side.
[0073] As shown in FIG. 4A, a middle opening 121 is formed inwardly from the first long side where the upper and lower regions of the pixel electrode 12 meet. The middle opening 121 extends a predetermined distance toward the second long side while being tapered. The first long side is cut at a predetermined angle on both sides of the middle opening 121, forming a wide inlet area of the middle opening 121. Upper and lower openings 122 and 123 are formed in the upper and lower regions of the pixel electrode 12, respectively, proceeding from the second long side at a predetermined angle respectively toward the first and fourth corners of the pixel electrode 12 in a symmetrical manner.
[0082] As shown in FIG. 5B, the opening pattern of the common electrode 23 includes a right opening 240 and a left opening 250. The right opening 240 includes a base 241 formed along and extending past the first long side of the common electrode 23, and tapers from a middle portion along the first long side toward the first and second short sides. The base 241 of the right opening 240 also includes a projection 242 extending a predetermined distance from the base 241 toward the second long side and tapered in the same direction. A portion of the projection 242 adjacent to the base 241 is formed at a predetermined slant. The left opening 250 includes a body 251 formed along the second long side of the common electrode 23, an upper limb 2.52 extended at a predetermined angle from one end of the body 251 toward and continuing past the first corner of the common electrode 23, and a lower limb 253 extended at a predetermined angle from the other end of the body 251 toward and continuing past the fourth corner of the common electrode 23. Centers of both the right and left openings 240 and 250 are positioned where the upper and lower regions of the common electrode 23 meet.
[0083] FIG. 5c shows a schematic view of the opening patterns of the pixel and common electrodes 12 and 23 shown respectively in FIGS. 5A and 5B in an overlapped state.
[0085] FIG. 6A shows a schematic view of an opening pattern of the pixel electrode 12 according to a fifth preferred embodiment of the present invention. As shown in FIG. 6A, the opening pattern of the pixel electrode 12 includes an upper opening 141 formed in the upper region of the pixel electrode 12, and a lower opening 142 formed in the lower region of the pixel electrode. If the pixel electrode 12 is divided into three areas of equal length, that is, first to third areas, with the first area having as its one side the first short side, the third area having as its one side the second short side, and the second area being formed between the first and third areas, the upper opening 141 is positioned where the first and second areas meet, and the lower opening 142 is positioned where the second and third areas meet. The upper opening 141 extends from the first long side to the second long side of the pixel electrode 12 in the horizontal direction, and areas of the pixel electrode 12 corresponding to where the upper opening 141 is positioned along the first long side are cut away to form a curved shape. Similarly, the lower opening 142 extends from the second long side to the first long side of the pixel electrode 12 in the horizontal direction. Areas of the pixel electrode 12 corresponding to where the lower opening 142 is positioned along the second long side are cut away to form a curved shape. In addition, second and third corners of the pixel electrode 12 are cut such that they are rounded.
[0087] As shown in FIG. 6B, the opening pattern of the common electrode 23 is a zigzag-shaped opening 260. The zigzag-shaped opening 260 includes an upper part 261-proceeding from the first corner of the common electrode 23 at a predetermined slant toward and meeting the second long side of the common electrode 23. A middle part 262 extends at a predetermined slant from an end of the upper part 261 where the same meets the second long side toward and meeting the first long side of the common electrode 23. And a lower part 263 extends at a predetermined slant from an end of the middle part 262 where the same meets the first long side toward and meeting the third corner of the common electrode 23. If the common electrode 23 is divided into three areas of equal length, that is, first to third areas, with the first area having as its one side the first short side, the third area having as its one side the second short side, and the second area being formed between the first and third areas, the upper and middle parts 261 and 262 converge where the first and second areas meet, and the middle and lower parts 262 and 263 converge where the second and third areas meet.
[0089] As shown in FIG. 6C, the opening patterns of the pixel and common electrodes 12 and 23 divide the pixel electrode 12 into several regions. The portion where the upper and middle parts 261 and 262 of the opening 260 of the common electrode 23 meet overlaps an end of the upper opening portion 141 of the pixel electrode 12 adjacent to the second long side, and the portion where the middle and lower parts 262 and 263 of the opening 260 of the common electrode 23 meet overlaps an end of the lower opening portion 142 of the pixel electrode 12 adjacent to the first long side.
[0095] FIG. 7c shows a schematic view of the opening patterns of the pixel and common electrodes 12 and 23 shown respectively in FIGS. 7A and 7B in an overlapped state.
[0097] With the configuration of this example of the present invention as described above, the lower and upper polarizer films 14 and 24 are arranged such that their polarizing directions are respectively 45° and 135° (or vice versa) with respect to the first and second short sides of the pixel electrode 12.
[0105] FIG. 9A shows a schematic view of an opening pattern of the pixel electrode 12 according to the other example of the present invention. As shown in FIG. 9A, the opening pattern of the pixel electrode 12 is a single linear opening 180 parallel to the first and second short sides of the pixel electrode 12. If the pixel electrode 12 is divided into three areas of equal length, that is, first to third areas, with the first area having as its one side the first short side, the third area having as its one side the second short side, and the second area being formed between the first and third areas, the linear opening 180 is positioned, where the second and third areas meet.
[0111] FIG. 10A shows a schematic view of an opening pattern, of the pixel electrode 12 according to the other example of the present invention.
[0118] Second, to obtain a stable partitioned orientation, disinclination or texture should be eliminated or minimized outside of the partitioned regions. Disinclination occurs when the long axes of liquid crystal molecules are oriented in various directions in a confined area, particularly when the long, axes are inclined toward one another. Therefore, it is preferable that the opening patterns of the pixel and common electrodes 12 and 23 are alternately arranged, and the end portions of the opening patterns are adjacent to each other. That is, when viewed from above, the opening patterns of the pixel and common electrodes 12 and 23 are preferably structured in the form of closed polygons. Furthermore, since disinclination is prone to occur when the opening patterns are structured having acute angles, it is preferable that the opening patterns are formed to have only obtuse angles. A stable partitioned orientation of liquid crystal molecules also enhances brightness. At areas where the orientation of the liquid crystal molecules 30 is dispersed, lights tend to leak at an off state, and dark portions are generated at an on state. Also, this dispersion of the orientation of liquid crystal molecules generates after-images when the liquid crystal molecules are rearranged.
[0122] In order to investigate such an interrelation, nine panels, each with different opening patterns were made and tested.
[0123] FIG. 11 shows schematic views of nine different opening patterns A-J for demonstrating the effect of opening pattern width and spacing on response speed and brightness. In the drawing, the opening patterns of the common electrode are indicated by hatched hues, and the opening patterns of the pixel electrode are indicated by solid lines.
[0125] FIG. 12A is a graph illustrating light transmissivity levels of test cells applying the A through J opening patterns, and FIG. 12B is a graph comparing the light transmissivity level of a test cell applying the B opening pattern to the light transmissivity levels of test cells applying the A through J opening patterns. As shown in the graphs, the light transmissivity level of the test cell applying the G opening pattern is the highest, exceeding 13%. The ranking of the light transmissivity levels of the test cells from highest to lowest according to which opening pattern is used is G, E, I, B, D, A, C, F, and J in order.
[0126] FIG. 13 is a graph illustrating response times as a function of gray scale of test cells applying the A through J opening patterns. Although only sixty-nine (69) gray scales are used in an actual application, the experiment was performed with one hundred and ten (110) gray scales. As shown in the graph, response times of the test cells applying the B, C, D, and J opening patterns were relatively fast over the whole range of gray scales. For the test cells applying the other opening patterns, the response times were relatively slow. In the case of the test cells applying the A and I opening patterns, the slow response times were due to the movement of texture. In the case of the test cells applying the B, F, and G opening patterns, the slow response times can be attributed to the two-step movement of liquid crystal molecules.
[0127] The A through J opening patterns shown in FIG. 11 were applied to actual panels and the panels were tested. Testing was performed on a total of four panels for each opening pattern. The results are listed in Table 2.
TABLE-US-00002 TABLE 2 White White Toff Ttotal after- Toff Ttotal after- PTN T (%) Ton(ms) (ms) (ms) image T(%) Ton(ms) (ms) (ms) image A 5.50 21.53 20.38 41.73 Medium 5.12 18.56 13.99 32.55 Weak 5.44 19.14 20.18 39.32 Strong 4.27 14.69 15.15 29.84 Weak B 5.23 18.16 20.28 38.44 very weak 4.79 12.36 14.5 26.86 X 4.88 18.79 20.42 39.21 very weak 4.56 12.64 15.48 28.12 X C 4.96 18.8 21.6 40.4 Strong 4.07 9.6 14.8 24.4 Strong 4.19 8.98 14.3 23.28 Strong D 4.88 24.36 21.2 40.0 X 4.75 12.8 14.8 27.6 X 4.79 13.36 13.47 26.83 X E 5.52 22.2 21.69 46.05 very weak 5.34 44.11 14.28 58.39 X 5.58 23.67 20.0 42.2 very weak F 4.79 20.8 21.63 45.2 X 4.34 70.79 14.89 85.68 X 5.58 20.8 19.2 40.0 X I 5.51 15.0 21.6 42.4 Weak 4.99 10.4 13.0 23.4 very weak 4.77 12.6 15.4 28 X J 4.76 20.8 35.8 Weak 4.49 7.6 12.4 20.0 Weak 3.96 9.6 15.4 25.0 Weak
[0128] The results of the experiment performed with the actual panels were similar to the results when using the test cells. However, there were some differences as follows. First, the actual panel of the I opening pattern exhibited a higher response speed than the test cell of the same opening pattern. Also, better results with regard to brightness were obtained with the actual panel of the J opening pattern than when the test cell was used. Specifically, the brightness of the test cell applying the J opening pattern was 75% of the cell applying the B opening pattern, whereas this was increased to 90% when the J opening pattern was applied to the actual panel.
[0130] On the basis of the above results, the opening patterns are to be selected depending on what the intended area of improvement is. If the improvement of brightness and the minimization of white afterimages are desired, it is preferable to use the B, D, E, and I opening patterns. However, if an improvement in response speed while keeping the brightness at a normal level is desired, the B, D, and I opening patterns are preferred. Finally, if what is needed is solely an improvement in response speed (without concerning brightness), the D and J opening patterns are preferred.
[0131] In order to further examine the interrelation between the response speed and the opening width of the opening patterns, the differences in the optical characteristics of panels applying the B, C, and D opening patterns, which have the same shape but different opening widths, will now be described. FIG. 14 is a graph illustrating response times as a function of gray scale of actual panels applying the B, C, and D opening patterns. As shown in the graph, the response times of the panels applying the opening patterns exhibited the following relation (based on the type of opening pattern) when 20 to 40 gray scales were used: D<B<C. It is evident, therefore, that the larger the width of the opening pattern the faster the response time.
[0132] Roughly between 40 and 45 gray scales, the response time of the panel applying the C opening pattern is shorter than that of the panel applying B opening pattern, and after 45 gray scales, the response time of the panel applying the C opening pattern is shorter than that of the panel applying the D opening pattern. However, such a change in the response time of the panel applying the C opening pattern is not actually taking place, but instead is given the appearance of change as a result of the generation of white after-images. That is, the response waveform is distorted due to the white after-images so that the response time seems to be shorter than it actually is. Accordingly, the conclusion originally reached that the larger the width of the opening pattern the faster the response speed remains valid.
[0133] With the use 60 gray scales or more, the response speed slows considerably due to the occurrence of texture. In conclusion, the panel applying the D opening pattern, which has the greatest width, exhibits the most stable characteristics. FIGS. 15A to 15C are photographs of the C, B and D opening patterns, respectively, at white gray scales. As seen from the photographs, the C opening pattern with poor texture stability displays the lowest level of brightness, with the B and D opening patterns exhibiting similarly higher levels of brightness. The D opening pattern exhibits a low opening ratio due to its significant width, but displays good texture stability such that panels applying this opening pattern have a high brightness. Texture stability is determined by the intensity of the fringe field and the width of the opening pattern.
[0134] The boundary areas between adjacent partitioned regions in the C, B and D opening patterns are formed differently. That is, two clearly distinguishable textures are present in most of the boundary areas of the C opening pattern, and with the B opening pattern, the boundary areas are again distinguishable but not as clearly as with the C opening pattern. The boundary areas of the D opening pattern, on the other hand, are not clearly formed and are faint in many portions.
[0135] FIGS. 16A and 16B are photographs of the C and D opening patterns applied to test cells in which a change in the partitioned regions according to a level of an applied voltage is shown.
[0136] In the C opening pattern, two clearly distinguishable textures are present in the boundary areas when the applied voltage, reaches 3.5V, and becomes clearer with further increases in the applied voltage. However, in the D opening pattern, the boundary areas are somewhat clearly distinguishable only when the applied voltage reaches 5V. Such distinguishable boundary areas are a result of the non-uniform orientation of the liquid crystal molecules. To better describe such a phenomenon, the intensity of the fringe field as a function of the widths of the opening patterns will be examined.
[0137] FIGS. 17A and 17B are schematic views used to illustrate the changes in the intensity of a fringe field according to variations in opening pattern width. As the width of the opening pattern becomes larger, the horizontal component of the fringe field experiences corresponding increases. The horizontal component of the fringe field plays an important role in determining the orienting direction of liquid crystal molecules. Therefore, opening patterns with a large width are preferred in forming partitioned regions. In contrast, the larger the width of the opening pattern the weaker the intensity of the vertical component of the electric field working at the center of the opening pattern.
[0143] Regarding the opening width of the opening pattern, when the spacing between the opening portions of the opening pattern becomes smaller, the opening ratio is significantly reduced but the brightness does not change much. This is due to texture. That is, when the distance between the opening portions is increased, it becomes difficult to control the texture, whereas it can be easily controlled when the opening spacing is small. Therefore, when the distance between the opening portions is small, the opening ratio is reduced but it becomes easy to control the texture which compensates the brightness. The exception is the I opening pattern, in which even though the distance between the opening portions is large, a high brightness can be achieved because texture is easily controlled.
[0145] There exists a direct correlation between texture and response speed. Moving texture reduces response speed. When a high voltage is applied, the response speed is reduced in most of the opening patterns. This is due to the generation of texture. Therefore, if texture can be properly controlled, picture quality as well as response speed can be improved. Techniques of preventing texture will now be described.
[0148] The opening pattern shown in FIG. 20 is similar to that shown in FIG. 8c, but differs in the number of openings extending across the pixel electrode from the first long side to the second long side. Furthermore, the openings of the pixel electrode 12 are such that they are open where they begin at the first long side of the pixel electrode 12 and extend across toward, but not reaching, the second long side of the pixel electrode 12. Portions of the second long side of the pixel electrode 12 adjacent to ends of these openings are protruded externally.
[0150] Such texture can be inhibited in the following way. In the case of area a, a width of the ends of the openings of the common electrode 23 are increased. In the case of area b, the openings of the common electrode 23 are structured to overlap part of area b. For this purpose, it is necessary to control the width and spacing of the opening portions. When the spacing is decreased, the opening ratio is reduced but the response speed is enhanced. In the case of area c, the end of the opening of the pixel electrode 12 extended from the first short side is formed having sharp edges.
[0152] In the above description, a structure in which the opening patterns are formed at both the pixel and common electrodes 12 and 23 is disclosed. However, it is also possible to form the opening patterns, together with the protrusions, only at the pixel electrode 12. In this case, the protrusions are formed using a gate insulating layer or a protective layer. In the formation of the protrusions, care should be taken to avoid the formation of parasitic capacitance between electrical lines. The openings and the protrusions can be arranged as illustrated in FIG. 21.
[0155] FIGS. 22 and 23 are layout views of a TFT substrate and a color filter substrate according to the other examples respectively.
[0156] As shown in FIG. 22, a portion 210 of a gate line 21 which transmits a scanning signal is formed to have a trapezoidal shape without the lower side. Then, the portion 210 made of opaque metal blocks the light from the backlight, and, therefore the light leakage or the decrease of luminance can be prevented.
[0157] Next, as shown in FIG. 23, a black matrix 11 is formed on the color filter substrate to cover the regions where disclination is generated and the aperture in the common electrode. The disclination regions are as described above, the region where the aperture 27 on the TFT substrate meets the boundary of the pixel electrode 20 and the region where the saw-shaped apertures 17 and 27 are bent. The black matrix pattern which covers the disclination includes, as shown in FIG. 23, an edge portion 111 surrounding and defining a pixel region, a saw-shaped portion 112 to cover the apertures 17, a triangular portion 113 to cover the disclination between saw-shaped apertures 17 and 27 and a center portion 114 put across the pixel region to cover the disclination generated in the bent portion of the apertures 17 and 27. Then, the light leakage generated by the disclination or the apertures is prevented by the black matrix 11. Moreover, the aperture ratio does not decrease additionally though a relatively large area of black matrix 11 is formed, because the region that the black matrix covers may not be used for display.
[0159] As shown in FIGS. 24 and 25, a portion 210 of a gate line 21 is formed on a lower TFT substrate. The gate line has a trapezoidal shape without the lower side. An insulating layer 22 covers the gate line 21. A pixel electrode 23 is formed on the insulating layer 22, and portions of the pixel electrode 23 are removed to form saw-shaped apertures 27 over the portion 210 of the gate line 21. A vertical alignment layer 24 is formed on the pixel electrode 20.
[0163] A black matrix 11 is formed to define a pixel region and to cover the aperture 17 to form multi-domain, the disclination between saw-shaped apertures 17 and 27 and the disclination generated in the bent portion of the apertures 17 and 27 as in the immediate previous example. In addition, the black matrix 11 includes another portion to cover the aperture 27 formed on the lower substrate.
[0171] In the described embodiments of the present invention, only apertures form the domains. However, the domains may be formed by protrusions along with apertures. In this case, the protrusions may be made of a gate insulating layer and/or a passivation layer. The layout of the protrusions and the aperture pattern may be the same as that of the apertures in FIGS. 21A to 21C. The protrusions may be formed on the color filter substrate.