JP5511640B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a multiplex-driven vertical alignment type liquid crystal display device.

  Liquid crystal display devices are widely used as information display units in, for example, various consumer and in-vehicle electronic devices. A general liquid crystal display device is configured by disposing a liquid crystal layer made of a liquid crystal material between two substrates arranged to face each other with a gap of about several μm. As one of such liquid crystal display devices, a vertical alignment type liquid crystal display device is known (for example, JP-A-2005-234254). A vertical alignment type liquid crystal display device is a vertical alignment mode (hereinafter referred to as “VA mode”) in which liquid crystal molecules in a liquid crystal layer disposed between two substrates are aligned substantially perpendicular to the surface of each substrate. And a polarizing plate provided outside the liquid crystal cell as main components. Each polarizing plate is often in a crossed Nicol arrangement. In this way, since the transmittance of the liquid crystal display device when no voltage is applied becomes very low, a high contrast can be realized relatively easily.

  When realizing image display of a liquid crystal display device by multiplex driving, substrates each having strip-shaped (stripe) electrodes are arranged facing each other so that the extending directions of the respective electrodes are substantially orthogonal to each other. Each of the regions where the electrode on one substrate and the electrode on the other substrate intersect is defined as a pixel. At this time, the shape of each pixel is substantially rectangular. Further, the surface of each substrate is subjected to an alignment process such as a rubbing process. The direction of the alignment treatment with respect to the surface of each substrate is set to, for example, opposite directions (anti-parallel alignment). As a result, the alignment direction of the liquid crystal molecules is determined in one direction when no voltage is applied at substantially the center in the layer thickness direction of the liquid crystal layer provided between the substrates. For example, when the direction of alignment treatment on each substrate is 6 o'clock and 12 o'clock as viewed from the front of the liquid crystal display device, the alignment direction of the liquid crystal molecules at the approximate center of the liquid crystal layer is determined to be 6 o'clock. At this time, the extending direction of the electrode on one substrate is substantially parallel to the alignment direction of the liquid crystal layer at the approximate center of the liquid crystal layer, and the extending direction of the electrode on the other substrate is substantially orthogonal.

  In the above VA mode liquid crystal display device, a case is considered in which a pair of polarizing plates arranged substantially in crossed Nicols are arranged outside each substrate. One polarizing plate has its absorption axis disposed at an angle of approximately 45 ° with respect to the direction of the alignment treatment applied to the one substrate. When a liquid crystal layer is formed using a liquid crystal material having a negative dielectric anisotropy, and a voltage higher than the threshold voltage is applied between the electrodes of each substrate, most of the liquid crystal molecules in the liquid crystal layer are oriented in the alignment process. In the horizontal alignment direction. When this liquid crystal display device is observed, the bright display state is observed well from the 6 o'clock direction, and conversely, the bright display is not observed from the 12 o'clock direction. The 6 o'clock direction at this time is called the best viewing direction (best viewing direction), and the 12 o'clock direction is called the anti-viewing direction (anti-viewing direction).

  In the VA mode liquid crystal display device, when viewed from the opposite viewing direction in a bright display state when viewed from the front, the inside of the pixel is observed in a dark state, but the four sides of the rectangular pixel are observed. Light leakage occurs in the vicinity of one side of the pixel edge. This light omission is not regular in the state of occurrence and is different for each pixel, and the display quality in appearance is remarkably deteriorated.

  Further, in the VA mode liquid crystal display device, when a bright display state in front view is obtained during multiplex driving, a dark region may be generated in each pixel, and display quality may be deteriorated. Since this phenomenon appears conspicuously by reducing the frame frequency, it is necessary to set the drive frequency higher in order to eliminate this phenomenon. However, when the drive frequency is raised, the impedance between the electrodes increases, so that the current consumption increases, the load on the drive device increases, and the potential difference on the electrodes becomes obvious, resulting in a reduction in display quality. Specifically, so-called crosstalk is likely to occur.

JP 2005-234254 A

  In a specific aspect of the present invention, in a vertical alignment type liquid crystal display device that operates by multiplex driving, the light omission near the edge of each pixel when observed from the opposite viewing direction is homogenized to improve display quality. One of the purposes is to realize display uniformity at the time of front observation with a frame frequency as low as possible.

  As a result of diligent examination by the inventors of the present invention in solving the above-described problems, the shape of the dark region generated in each pixel is made more uniform by preventing the pixel edge of each pixel and the direction of orientation processing from being orthogonal as much as possible. The knowledge that display quality can be improved was acquired. In addition, in such a pixel structure, it has also been found that the effect of lowering the frame frequency can be obtained by making the pixel edge and the direction of the alignment treatment as parallel as possible. And based on the said knowledge, this inventor came to create the following invention.

A liquid crystal display device according to an aspect of the present invention includes (a) a first substrate and a second substrate which are disposed to face each other, and (b) provided on one surface of the first substrate, and extending in a first direction. A first electrode; (c) a second electrode provided on one surface of the second substrate and extending in a second direction intersecting the first direction; and (d) a surface of the first substrate and the first electrode. And (e) a pixel is formed in a region where the first electrode and the second electrode intersect, and (f) the first substrate. wherein the least one of the second substrate, alignment treatment in one direction is performed, (g) each pixel edges of the first electrode, each interlinked second direction and oblique or one different two directions with countercurrent Ward has a plurality of first line segment Re folding connected linear shape, (h) each pixel edge of the second electrode, each first way And oblique to, or One has different two directions folding toward ku plurality of second line segments are connected in Re linear shape, (i) the pixel of the plurality of first segments A pixel edge is defined by two of the first line segments and two of the plurality of second line segments, and each of the plurality of second line segments of the second electrode includes the second line segment. the two directions with respect that not make 15 ° angle of less than greater than 0 °, a liquid crystal display device. Here, “obliquely intersect” means that they intersect obliquely at an angle other than orthogonal.

According to such a configuration, since the pixel edge is defined including the line segment oblique to the direction of the alignment processing, the light omission near the edge of each pixel when viewed from the opposite viewing direction is displayed in a uniform manner. It becomes possible to improve the quality .

  In addition, by setting the pixel edges to be obliquely crossed in both the first direction and the second direction, it is possible to obtain an effect of reducing the frame frequency at which display uniformity can be obtained during front observation.

  Preferably, each of the plurality of first line segments of the first electrode forms an angle of greater than 0 ° and less than or equal to 15 ° with respect to the first direction.

  Moreover, it is also preferable that the said 1st electrode is the shape where each said pixel edge of one side and the other side is equal. Thereby, it is possible to increase the area efficiency when arranging a plurality of first electrodes.

  Moreover, it is also preferable that the second electrode has a shape in which the pixel edges on one side and the other side are the same. Thereby, it is possible to increase the area efficiency when arranging a plurality of first electrodes.

It is typical sectional drawing which shows the structure of the liquid crystal display device of one Embodiment. It is a typical top view which shows an example of an electrode structure. It is a typical top view which shows another example of an electrode structure. It is a typical top view which shows another example of an electrode structure. It is a figure which shows the orientation structure observation image at the time of the voltage application of the liquid crystal display device which has an electrode structure of type a. It is a figure which shows the orientation structure observation image at the time of the voltage application of the liquid crystal display device which has an electrode structure of type b. It is a figure which shows the orientation structure | tissue observation image at the time of the voltage application of the liquid crystal display device which has a type-c electrode structure as a 1st electrode, and has a type-a electrode structure as a 2nd electrode. It is a figure which shows the orientation structure | tissue observation image at the time of the voltage application of the liquid crystal display device which has a type-c electrode structure as a 1st electrode, and has a type-b electrode structure as a 2nd electrode. It is the top view which showed typically the orientation direction (alignment distribution) of the liquid crystal layer in the approximate center of the liquid crystal layer at the time of the voltage application in one pixel obtained by making strip-shaped electrodes cross | intersect. It is a figure which shows the polarization microscope observation image of the pixel at the time of the voltage application of the liquid crystal display device of the prior art example actually produced.

  The inventor of the present application has studied the cause of light leakage near the pixel edge of each pixel when the vertically aligned liquid crystal display device is multiplex driven. FIG. 9 is a plan view schematically showing the alignment direction (alignment distribution) of liquid crystal molecules at the approximate center of the liquid crystal layer when a voltage is applied in one rectangular pixel obtained by crossing strip electrodes. is there. 9 corresponds to the 12 o'clock direction, the horizontal direction corresponds to the 9 o'clock direction, the 3 o'clock direction, and the lower direction corresponds to the 6 o'clock direction, respectively, and the lower direction is the best viewing direction. . The pixel shown in FIG. 9 is formed by crossing the strip electrode 111 and the strip electrode 112. The strip electrode 111 is provided on a first substrate (not shown), and the strip electrode 112 is provided on a second substrate (not shown). The direction 113 of the alignment treatment applied to the first substrate is the 6 o'clock direction, and the direction 114 of the alignment treatment applied to the second substrate is the 12 o'clock direction. In the vicinity of the pixel edge in the 12 o'clock direction, which is the anti-viewing direction, the alignment direction when no voltage is applied and the alignment direction defined by the generation of the oblique electric field differ by 180 °. Will occur. On the other hand, even in the vicinity of each pixel edge in the left-right direction, rotation of the alignment direction 121 occurs because the oblique electric field differs by 90 ° from the alignment direction when no voltage is applied. If each absorption axis of the polarizing plate in the crossed Nicol arrangement is arranged at approximately 45 ° with respect to the alignment direction when no voltage is applied, the region parallel to this is not brightly displayed even when a voltage is applied. It is expected not to be. Further, in the vicinity of the pixel edges on the left, right, and upper three sides, regions having different alignment directions 121 are generated when a voltage is applied. Therefore, this liquid crystal display device exhibits multi-domain alignment when a voltage is applied. Therefore, the best viewing direction is different in the vicinity of each pixel edge, and it is visually recognized as a region where light is lost particularly when observed from the 12:00 direction which is the anti-viewing direction.

  FIG. 10 is a diagram showing a polarization microscope observation image of a pixel when a voltage is applied to a liquid crystal display device of a conventional example actually manufactured. In the liquid crystal display device, one pixel is 0.43 mm square, and the electrode interval between the strip electrodes is 30 μm. Observing the inside of one pixel shows that a cross-shaped dark region is observed. As described above, the rotation of the alignment direction of the liquid crystal molecules occurred due to the influence of the oblique electric field in the vicinity of the pixel edge during voltage application.Therefore, the alignment direction near the direction parallel to or perpendicular to the absorption axis of the polarizing plate is near this dark region. It is thought that it has become. In particular, in the vicinity of the pixel edge in the 12 o'clock direction where the rotation angle of the alignment direction of the liquid crystal molecules is large at the approximate center of the liquid crystal layer, it can be seen that the dark region has entered the pixel from the pixel edge. Further, a cross point in the dark region is observed near the pixel edge. This cross point is considered to be a disclination in which the liquid crystal molecules are held in a substantially vertical orientation despite the application of voltage. When each pixel is observed, there are cases where there are one or three cross points, and the occurrence of the cross points is irregular. Further, the shape of the cross-shaped dark region is completely different depending on the pixel. If the shape of the dark region is not uniform, a difference occurs in the area ratio of each domain in the multi-domain alignment, which is considered to cause a difference in viewing angle characteristics. That is, this is considered to be a factor that causes display non-uniformity in the anti-viewing direction.

  Therefore, when the observation image in FIG. 10 was examined in more detail, it was found that the dark region in each pixel had an irregular shape mostly in the vicinity of the pixel edge in the 12 o'clock direction. In this region, the electrode edge of the strip-shaped electrode 112 and the orientation processing directions 113 and 114 are substantially orthogonal. On the other hand, dark areas regularly occur in each pixel in the vicinity of each pixel edge in the 9 o'clock direction and the 3 o'clock direction where dark areas similarly occur. In this region, the electrode edge of the strip-shaped electrode 111 and the orientation processing directions 113 and 114 are substantially parallel to each other. From these facts, it can be considered that by reducing the number of locations where the pixel edge and the direction of the alignment treatment are orthogonal, the shape of the dark region generated in each pixel can be made uniform and the display quality can be improved.

  An embodiment of the present invention based on the above knowledge will be described below.

  FIG. 1 is a schematic cross-sectional view showing the structure of a liquid crystal display device according to an embodiment. The liquid crystal display device according to the present embodiment shown in FIG. 1 mainly includes a first substrate 1 and a second substrate 2 that are disposed to face each other, and a liquid crystal layer 3 that is disposed between the two substrates. A first polarizing plate 4 is disposed outside the first substrate 1, and a second polarizing plate 5 is disposed outside the second substrate 2. A first viewing angle compensation plate 6 is disposed between the first substrate 1 and the first polarizing plate 4, and a second viewing angle compensation plate 7 is disposed between the second substrate 2 and the second polarizing plate 5. The periphery of the liquid crystal layer 3 is sealed with a sealing material. Hereinafter, the structure of the liquid crystal display device will be described in more detail.

  The first substrate 1 and the second substrate 2 are transparent substrates such as a glass substrate and a plastic substrate, respectively. Between the first substrate 1 and the second substrate 2, spacers (granular bodies) are arranged in a dispersed manner. By these spacers, the gap between the first substrate 1 and the second substrate 2 is maintained at a predetermined distance (about 4.3 μm in this embodiment).

  The liquid crystal layer 3 is provided between the first electrode 11 of the first substrate 1 and the second electrode 12 of the second substrate 2. In the present embodiment, the liquid crystal layer 3 is configured using a liquid crystal material (nematic liquid crystal material) having a negative dielectric anisotropy Δε (Δε <0). The bold line shown in the liquid crystal layer 3 schematically shows the alignment direction of the liquid crystal molecules when no voltage is applied. As shown in the figure, in the liquid crystal display device of the present embodiment, the alignment state of the liquid crystal molecules in the liquid crystal layer 3 is restricted to monodomain alignment. The pretilt angle of the liquid crystal layer 3 in this embodiment is set to approximately 89.9 °. The retardation of the liquid crystal layer 3 is approximately 1100 nm.

  The 1st polarizing plate 4 and the 2nd polarizing plate 5 are arrange | positioned so that each absorption axis may mutually cross substantially orthogonally (cross Nicol arrangement | positioning). Further, the first polarizing plate 4 and the second polarizing plate 5 are substantially the same as either the direction 14 of the alignment treatment applied to the first substrate 1 or the direction 13 of the alignment treatment applied to the second substrate. It arrange | positions so that the angle of 45 degrees may be made. Thereby, the absorption axis of each polarizing plate 4 and 5 makes an angle of about 45 ° with respect to the alignment direction of the liquid crystal layer at the approximate center of the liquid crystal layer 3 defined by the directions 13 and 14 of the alignment treatments. Become.

  The alignment film 8 is provided on one surface side of the first substrate 1 so as to cover the first electrode 11. Similarly, the alignment film 9 is provided on one surface side of the second substrate 2 so as to cover the second electrode 12. Each alignment film 8, 9 is subjected to an alignment process such as a rubbing process. A direction 14 of the alignment treatment applied to the alignment film 8 is as shown in the figure, and substantially coincides with the extending direction (first direction) of the first electrode 11. In addition, the direction 13 of the alignment treatment applied to the alignment film 9 is as illustrated, and is substantially orthogonal to the extending direction (second direction) of the second electrode 12. In the present embodiment, as the alignment film 8 and the alignment film 9, one that regulates the alignment state in the initial state (when no voltage is applied) of the liquid crystal layer 3 to the vertical alignment state (vertical alignment film) is used. More specifically, as the alignment films 8 and 9, those that can give a pretilt angle of an angle very close to 90 ° to the liquid crystal molecules of the liquid crystal layer 3 are used. The alignment treatment may be performed only on one of the alignment films.

  The first electrode 11 is provided on one surface of the first substrate 1. The second electrode 12 is provided on one surface of the second substrate 2. In the present embodiment, a plurality of first electrodes 11 and a plurality of second electrodes 12 each extending in a specific direction are opposed to each other with their extending directions substantially orthogonal to each other. Each first electrode 11 and each second electrode 12 are configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example. In the liquid crystal display device of this embodiment, each of the portions where the first electrode 11 and the second electrode 12 overlap in a plan view is a pixel.

  In the present embodiment, the electrode edge of each electrode has a polygonal line shape, thereby improving both display quality and reducing the frame frequency. Below, some specific structures are illustrated.

  FIG. 2 is a schematic plan view showing an example of an electrode structure. In FIG. 2, each first electrode 11 extending in the vertical direction in the figure is indicated by a dotted line (the same applies hereinafter). As shown in FIG. 2A, the electrode edge of each second electrode 12 extending in the left-right direction in the drawing is formed in a sawtooth shape, and one pitch of the sawtooth corresponds to the electrode width of each first electrode 11. It is set almost equal. In each of the second electrodes 12, the direction of bending at one electrode edge and the other electrode edge is staggered, and the bending points of both electrode edges repeatedly approach and separate. As shown in FIG. 2 (b), each second electrode 12 has one bending point (vertex) of the sawtooth overlapping the substantially central portion of the first electrode 11, and the other one bending point (vertex). It arrange | positions in the state which overlaps with the part between 1st electrodes 11 electrodes. Since the region where each first electrode 11 and each second electrode 12 intersect becomes one pixel, the shape of one pixel is two sides by the electrode edge of the first electrode 11 and two sides by the electrode edge of the second electrode 12. It becomes the substantially hexagon defined by. Hereinafter, the electrode structure shown in FIG. 2 may be referred to as a “type a electrode structure”.

  In FIG. 2, when the angle formed between the electrode edge of the second electrode 12 and the horizontal direction (left-right direction in the figure) is defined as θ, the angle θ is set to be greater than 0 ° and equal to or less than 15 °. By doing so, it is possible to realize a structure in which the upper and lower sides of each pixel and the directions 13 and 14 of each alignment treatment are not orthogonal to each other. In each pixel in the type a electrode structure, adjacent pixels in the vertical direction have different shapes, and adjacent pixels in the horizontal direction have the same shape.

  FIG. 3 is a schematic plan view showing another example of the electrode structure. As shown in FIG. 3A, the electrode edge of each second electrode 12 extending in the left-right direction in the drawing is formed in a sawtooth shape, and one pitch of the sawtooth corresponds to the electrode width of each first electrode 11. It is set almost equal. As shown in FIG. 3 (b), each second electrode 12 has one apex angle portion (bending point) of the sawtooth overlapping the substantially central portion of the first electrode 11, and the other one apex angle portion ( (Bending point) is arranged so as to overlap the inter-electrode portion of the first electrode 11. The bending points of both electrode edges repeatedly approach and separate from each other. Since the region where each first electrode 11 and each second electrode 12 intersect becomes one pixel, the shape of one pixel is two sides by the electrode edge of the first electrode 11 and two sides by the electrode edge of the second electrode 12. Is a substantially inverted V-shaped hexagon defined by The shape of each pixel may be a substantially V-shaped hexagon. Hereinafter, the electrode structure shown in FIG. 3 may be referred to as “type b electrode structure”.

  In FIG. 3, when the angle formed between the electrode edge of the second electrode 12 and the horizontal direction (left-right direction in the figure) is defined as θ, this angle θ is set to be greater than 0 ° and equal to or less than 15 °. By doing so, it is possible to realize a structure in which the upper and lower sides of each pixel and the directions 13 and 14 of each alignment treatment are not orthogonal to each other. In each pixel in the type b electrode structure, adjacent pixels have the same shape in both the vertical and horizontal directions.

  FIG. 4 is a schematic plan view showing another example of the electrode structure. As shown in FIG. 4A, the electrode edge of each first electrode 11 extending in the vertical direction in the drawing is formed in a sawtooth shape, and one pitch of the sawtooth is equal to the electrode width of each second electrode 12. It is set almost equal. Each second electrode 12 has the same electrode structure as that of type a described above. Then, as shown in FIG. 4B, each first electrode 11 has one apex angle portion (bending point) of the sawtooth overlapped with a substantially central portion of the second electrode 12, and the other one apex angle portion ( (Bending point) is arranged so as to overlap the inter-electrode portion of the second electrode 12. Similarly, in each second electrode 12, one apex angle portion (bending point) of the sawtooth overlaps with a substantially central portion of the first electrode 11, and the other one apex angle portion (bending point) of the first electrode 11. It arrange | positions in the state which overlaps with the part between electrodes. Since the region where each first electrode 11 and each second electrode 12 intersect becomes one pixel, the shape of one pixel is two sides by the electrode edge of the first electrode 11 and two sides by the electrode edge of the second electrode 12. Is a hexagon defined by The shape of each pixel may be a substantially V-shaped hexagon. Hereinafter, the electrode structure shown in FIG. 4 may be referred to as “type c electrode structure”.

  In FIG. 4, when the angle formed between the electrode edge of the first electrode 11 and the vertical direction (vertical direction in the drawing) is defined as θ, the angle θ is set to be greater than 0 ° and equal to or less than 15 °. By doing so, it is possible to realize a structure in which the upper and lower sides of each pixel and the directions 13 and 14 of each alignment treatment are not orthogonal to each other. In each pixel in the type c electrode structure, adjacent pixels have the same shape in both the vertical direction and the horizontal direction. Each second electrode 12 may have an electrode structure similar to that of type b described above.

  Next, the results of actually manufacturing a liquid crystal display device having each of the above-described pixel structures of types a to c and performing the alignment structure observation and appearance observation will be described. In the actually manufactured liquid crystal display device, specific numerical conditions in each electrode structure type are as follows. In any type, the distance between adjacent electrodes of each first electrode 11 and each second electrode 12 is set to 0.03 mm so that the opening area does not decrease. In addition, the distance between the bending points of both the first electrode 11 and the second electrode 12 was 0.215 mm, and θ was set to 5 °, 10 °, and 15 °. The direction of the alignment treatment, the alignment direction of the liquid crystal molecules at the approximate center of the liquid crystal layer 3, and the arrangement state of each polarizing plate are as described above.

  FIG. 5 is a diagram showing an alignment structure observation image when a voltage is applied to a liquid crystal display device having a type a electrode structure. Specifically, FIG. 5A is an observation image of θ = 5 °, FIG. 5B is an observation image of θ = 10 °, and FIG. 5C is an observation image of θ = 15 °. It can be seen that in any orientation structure, the uniformity of the distribution shape of the dark region at the pixel edge is improved as compared with the liquid crystal display device according to the conventional example (see FIG. 10). However, in the orientation structure of θ = 5 °, the uniformity of the position of the disclination existing near the bending point is not sufficient. On the other hand, in each oriented structure of θ = 10 ° and θ = 15 °, a tendency was observed that the uniformity of the dark region was improved as θ increased.

  FIG. 6 is a diagram showing an alignment texture observation image when a voltage is applied to a liquid crystal display device having a type b electrode structure. Specifically, FIG. 6A is an observation image of θ = 5 °, FIG. 6B is an observation image of θ = 10 °, and FIG. 6C is an observation image of θ = 15 °. The same tendency as in the case of the type a was also observed in the liquid crystal display device having the type b electrode structure.

  Next, for each of the liquid crystal display device having each of the type a and type b electrode structures and the conventional liquid crystal display device, the evaluation results on the drive frequency dependence of display uniformity during bright display will be described. The drive conditions are 1/64 duty, 1/9 bias, frame-reversed waveform multiplex drive, a bright display drive voltage that can obtain almost maximum contrast, and the lower limit of the frame frequency at which display non-uniformity is observed. It evaluated from appearance observation.

  As a result, the lower limit value of the frame frequency is 105 Hz in the conventional liquid crystal display device, whereas in the liquid crystal display device having the type a electrode structure, θ is 5 °, 10 °, and 15 °. The frame frequency at the time of setting changed to 110 Hz, 130 Hz, and 130 Hz. On the other hand, it became clear that the display uniformity when observed from the opposite viewing direction is improved as θ increases. In the liquid crystal display device having the type b electrode structure, the frame frequency when θ was set to 5 °, 10 °, and 15 ° was changed to 120 Hz, 135 Hz, and 150 Hz. It has been clarified that the display uniformity when observed from the opposite viewing direction is improved as θ is increased. From the above, for both types a and b, as the θ increases, the display uniformity when observed from the anti-viewing direction is improved, but the frame frequency at which display uniformity is obtained during frontal observation tends to increase. .

  FIG. 7 is a diagram showing an alignment texture observation image when a voltage is applied to a liquid crystal display device having a type-c electrode structure as the first electrode and a type-a electrode structure as the second electrode. Specifically, FIG. 7A is an observation image of θ = 5 °, FIG. 7B is an observation image of θ = 10 °, and FIG. 7C is an observation image of θ = 15 °. In any orientation structure, the dark region at the pixel edge is substantially equivalent to the orientation structure shown in FIG. 5 with respect to the second electrode 12 and is relatively uniformly distributed except for θ = 5 °. I understand. The uniformity of the dark region distribution was also good for the first electrode 11. The display uniformity in appearance observation from the counter-viewing direction is further improved as compared with the above-described type a and type b liquid crystal display devices, and is improved over the conventional liquid crystal display device. The driving frequency dependence of display uniformity during frontal observation of this liquid crystal display device was evaluated under the same conditions as described above. As a result, θ = 5 °, 10 °, and 15 ° were 95 Hz, 100 Hz, and 90 Hz, respectively, and no dependency on θ was observed. Further, it has been found that the lower limit value of the frame frequency is lower than that of the conventional liquid crystal display device and each of the type a and b liquid crystal display devices.

  FIG. 8 is a diagram showing an alignment texture observation image when a voltage is applied to a liquid crystal display device having a type-c electrode structure as the first electrode and a type-b electrode structure as the second electrode. Specifically, FIG. 8A is an observation image of θ = 10 °, and FIG. 8B is an observation image of θ = 15 °. The dark region observed in the vicinity of the electrode edge of the second electrode 12 is more uniform than the conventional liquid crystal display device, and the same tendency as in the type a is observed. On the other hand, it was found that the uniformity of the dark region was sufficiently obtained even at the electrode edge of the first electrode 11. The display uniformity in appearance observation from the opposite viewing direction is the same as that of the liquid crystal display device having the electrode structure of type b shown in FIG. 6, and is confirmed to be improved as compared with the conventional liquid crystal display device. did it. Further, when the drive frequency dependence of display uniformity during front observation of this liquid crystal display device was evaluated under the same conditions as described above, the lower limit value of the frame frequency was 100 Hz at θ = 10 ° and 15 °. It has been found that the lower limit of the frame frequency is lower than that of the conventional liquid crystal display device and each of the type a and b liquid crystal display devices.

  From these results, it can be judged that it is effective to employ an electrode structure having flexibility on both the first electrode side and the second electrode side as an effect of lowering the lower limit value of the frame frequency. In this case, the value of θ is preferably 5 ° or more. On the other hand, it is considered that θ is preferably set to 10 ° or more and 15 ° or less in order to further improve the display uniformity from the opposite viewing direction.

  In addition, this invention is not limited to the content of embodiment mentioned above, In the range of the summary of this invention, it can change and implement variously. For example, in the above-described embodiment, the electrode edges on both sides of each of the first electrode and the second electrode have the same shape, but may have different shapes.

  DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate 2 ... 2nd board | substrate 3 ... Liquid crystal layer 4 ... 1st polarizing plate 5 ... 2nd polarizing plate 6 ... 1st viewing angle compensation plate 7 ... 2nd viewing angle compensation plate 8, 9 ... Orientation film 11 ... 1st Electrode 12 ... Second electrode 13, 14 ... Direction of orientation treatment

Claims (4)

A first substrate and a second substrate disposed opposite to each other;
A first electrode provided on one surface of the first substrate and extending in a first direction;
A second electrode provided on one surface of the second substrate and extending in a second direction intersecting the first direction;
A substantially vertically aligned liquid crystal layer provided between one surface of the first substrate and one surface of the second substrate;
A pixel is formed in a region where the first electrode and the second electrode intersect,
At least one of the first substrate and the second substrate is subjected to an alignment process in a direction parallel to the first direction,
Each pixel edge of the first electrode, each interlinked second direction and oblique or One folding of the different two directions toward ku plurality of first line segments are connected Re has a linear shape,
Each pixel edge of the second electrode are each interlinked first direction and oblique or One folding of the different two directions toward ku plurality of second line segments are connected Re has a linear shape,
The pixel is the pixel edges by two second line segments of the plurality of two first line segments and the plurality of second segments of the first line segment is defined, said second electrode a plurality of second line segments, respectively, that have no a 15 ° angle of less than greater than to 0 ° relative to the second direction,
Liquid crystal display device. Wherein the plurality of first segments of the first electrode, respectively, wherein the first direction with respect that have an angle of 15 ° or less greater than 0 °, the liquid crystal display device according to claim 1.   The liquid crystal display device according to claim 1, wherein the first electrode has a shape in which the pixel edges on one side and the other side are the same.   The liquid crystal display device according to claim 1, wherein the second electrode has a shape in which the pixel edges on one side and the other side are the same.

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