JP5572061B2 - 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, the majority 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. Further, in such a pixel structure, it was further found that the effect of lowering the frame frequency can be obtained by relatively narrowing the width of one of the intersecting electrodes. And based on the said knowledge, this inventor came to create the following invention.

(1) 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, in a first direction. A first electrode extending; (c) a second electrode provided on one surface of the second substrate and extending in a second direction intersecting the first direction; and (d) one surface of the first substrate. And a vertically aligned liquid crystal layer having a pretilt angle provided between one surface of the second substrate, and (e) a pair of polarizing plates respectively disposed on the outside of the first substrate and the outside of the second substrate If, comprises, (f) the pixels in the intersection region between the first electrode and the second electrode is formed, and (g) said second direction to at least one of the first substrate and the second substrate alignment treatment in a direction orthogonal is applied, (h) the first electrode, on both sides of the electrode edge is the first way A linear shape extending in, the (i) the second electrode, on both sides of the electrode edges, the oblique line at an angle of 15 ° or less greater than 0 ° with the said second direction ( J ) The pixel has a pixel edge defined by the oblique line segment of the electrode edge of the first electrode and the electrode edge of the second electrode, and ( k ) the pixel , the than the second direction Ri shape der extending along the first direction, (l) the pair of polarizing plates, each of the absorption axis is an angle of direction and 45 ° of the alignment treatment It is a liquid crystal display device arranged .
(2) In the liquid crystal display device according to (1), it is preferable that the pixels have a parallelogram shape extending along the first direction.
(3) In the liquid crystal display device according to (1), it is preferable that the pixel has a trapezoidal shape extending along the first direction.
(4) A liquid crystal display device according to another aspect of the present invention includes: (a) a first substrate and a second substrate arranged opposite to each other; and (b) provided on one surface of the first substrate, in a first direction. (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 first electrode extending from the first substrate. A vertically aligned liquid crystal layer having a pretilt angle provided between one surface and one surface of the second substrate; and (e) a pair of polarized light disposed on the outside of the first substrate and the outside of the second substrate, respectively. includes a plate, a, (f) the pixels in the intersection region between the first electrode and the second electrode is composed, (g) said second direction to at least one of the first substrate and the second substrate And ( h ) the first electrode has an electrode edge on one side of the second electrode. ( I ) the second electrode has an electrode edge on both sides that is greater than 0 ° and less than or equal to 15 ° between the second direction and the second electrode ; including oblique line at an angle a polygonal line shape, (j) the pixel is a pixel by the oblique line of the electrode edge of the second electrode and the electrode edge of the first electrode edge is defined, (k) the pixel, the second Ri shape der extending along the first direction than the direction, (l) the pair of polarizing plates, the alignment processing each of the absorption axis This is a liquid crystal display device that is disposed at an angle of 45 ° with respect to this direction .
(5) In the liquid crystal display device according to (1) or (4), it is also preferable that the oblique line segment of the electrode edge of the second electrode is a straight line segment.
(6) In the liquid crystal display device of the above (1), (4) or (5), it is also preferable that the alignment direction of the liquid crystal molecules at the approximate center in the layer thickness direction of the liquid crystal layer is parallel to the first direction. .

According to whether this configuration, since the pixel edge is defined comprise oblique line with respect to the direction of alignment treatment, and homogenizing the light leakage in the vicinity of the edge of each pixel when viewed from the opposite viewing direction Display quality can be improved. In addition, by making the electrode width of the first electrode relatively small and making the pixel edge long along the first direction, it is possible to obtain an effect of reducing the frame frequency at which display uniformity during front viewing can be obtained. .

  The liquid crystal display device according to another aspect of the present invention includes: (a) a first substrate and a second substrate arranged opposite to each other; and (b) provided on one surface of the first substrate, and extending in a first direction. (C) a second electrode provided on one surface of the second substrate and extending in a second direction substantially orthogonal to the first direction; and (d) a surface of the first substrate. A liquid crystal layer having a substantially vertical alignment provided between one surface of the second substrate; (e) a pixel is formed in a region where the first electrode and the second electrode intersect; and (f) the first At least one of the one substrate and the second substrate is subjected to an alignment process in a direction substantially parallel to the first direction. (G) The first electrode has a linear shape with electrode edges on both sides extending in the first direction. (H) the second electrode includes a line segment in which electrode edges on both sides are oblique to the first direction. (I) the electrode width of the first electrode is smaller than the electrode width of the second electrode, and (j) the pixel includes the electrode edge of the first electrode and the pixel of the second electrode. A pixel edge is defined by the oblique line segment of the edge, and (k) the liquid crystal display device in which the pixel edge has a long shape along the first direction.

In the above liquid crystal display device, for example, the second electrode has a structure in which the shape of the electrode edge on both sides is substantially the same and the electrode width is substantially constant, and the pixel edge is It is preferable that it is a substantially parallelogram shape long along one direction. In the above-described liquid crystal display device, for example, the second electrode alternately repeats a location where the bending point of the electrode edge on one side and the bending point of the electrode edge on the other side are relatively close to each other and a location where they are separated from each other. It is also preferable that the pixel edge has a trapezoidal shape that is long along the first direction.

  In the above liquid crystal display device, it is preferable that an electrode width of the first electrode is approximately ½ or less of an electrode width of the second electrode.

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 typical top view which shows another example of an electrode structure. It is a figure which shows the orientation structure | tissue observation image at the time of the voltage application of a liquid crystal display device. It is a figure which shows the orientation structure | tissue observation image at the time of the voltage application of a liquid crystal display device. 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. It is a figure which shows the orientation structure | tissue at the time of bright display of the liquid crystal display device which narrowed the electrode width of one strip-shaped electrode.

  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. 8 is a plan view schematically showing the orientation direction (orientation 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. 8 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. 8 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 114 of the alignment treatment applied to the first substrate is 6 o'clock, and the direction 113 of the alignment treatment applied to the second substrate is 12 o'clock. 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. 9 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.

  On the other hand, the liquid crystal display device of the conventional example shown in FIG. 9 is multiplex driven by 1/64 duty, 1/9 bias, and frame inversion waveform to obtain display uniformity during front viewing in the case of bright display. When the lower limit of the frequency was examined, the frame frequency was 105 Hz. On the other hand, when a method for further lowering the lower limit value of the frame frequency was examined, it was found that it is effective to relatively narrow the electrode width of one of the strip electrodes. Specifically, in the liquid crystal display device of the conventional example shown in FIG. 9, the electrode width of each strip electrode is set to 0.4 mm, but the electrode width of one strip electrode (segment electrode) is 0.185 mm. A liquid crystal display device having a halved size was manufactured, and multiplex driving was performed under the same conditions as described above. At this time, the lower limit value of the frame frequency at which display uniformity during front observation in the case of bright display was obtained was 85 Hz. When the appearance of the liquid crystal display device is observed from the opposite viewing direction, the display uniformity is improved as compared with the liquid crystal display device shown in FIG. 9, but it is still insufficient. FIG. 10 shows an orientation structure at the time of bright display of the liquid crystal display device in which the electrode width of one strip-shaped electrode is narrowed. Each pixel has a rectangular shape, but it can be seen that the dark region occurring in the 12 o'clock direction among the four sides has no regularity in each pixel. Further, it has been found that the uniformity of the dark areas occurring on each side in the 3 o'clock direction and the 9 o'clock direction is not sufficient. Accordingly, it may be difficult to ensure display uniformity when observed from the opposite viewing direction.

  Therefore, when the observation images in FIGS. 9 and 10 were examined in more detail, it was found that the shape of the dark region was irregular in each pixel, 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 polarizing plate 4 and the polarizing plate 5 are arranged so that their absorption axes are substantially orthogonal to each other (crossed Nicol arrangement). In addition, the polarizing plate 4 and the polarizing plate 5 each have an angle of about 45 ° in each of the alignment processing direction 14 applied to the first substrate 1 and the alignment processing direction 13 applied to the second substrate. It is arranged to make. 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. Further, the direction 13 of the alignment treatment applied to the alignment film 9 is as shown in the figure and substantially coincides with the extending direction ( first direction) of the first electrode 11 . 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 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 second electrode 12 is formed into a polygonal line shape including a line segment that obliquely intersects with the extending direction (first direction) of the first electrode. Of these, the pixel edge of the portion defined by the electrode edge of each second electrode 12 and the orientation processing directions 13 and 14 are not orthogonal to each other, and each pixel has a long pixel edge in one direction. ing. Below, some specific structures are illustrated.

  FIG. 2 is a schematic plan view showing an example of an electrode structure. 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 the 1/4 pitch of the sawtooth is an electrode of each first electrode 11. It is set almost equal to the width. As shown in FIG. 2B, each second electrode 12 is arranged such that one apex angle portion (bending point) of the saw blade overlaps with the inter-electrode portion of the first electrode 11. 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 parallelogram that is long in one direction. 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. Each pixel in the type D electrode structure has the same shape in adjacent pixels in the vertical direction, but has two types of pixel edge shapes that change at each bending point. In the illustrated example, the two first electrodes 11 are disposed between the bending points of the second electrodes 12, but three or more first electrodes 11 may be disposed. In other words, each first electrode 11 may have an electrode width of approximately ½ or less of the electrode width of the second electrode 12 .

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 the 1/4 pitch of the sawtooth is an electrode of each first electrode 11. It is set almost equal to the width. The difference from the type A electrode structure shown in FIG. 2 is that the direction of bending at one electrode edge and the other electrode edge of each second electrode 12 is staggered, and the bent vertices of both electrode edges approach each other. It is that it repeats moving away. As shown in FIG. 3B, each second electrode 12 is arranged in a state where one apex angle portion (bending point) of the sawtooth overlaps with the interelectrode portion of the first electrode 11. 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 a substantially trapezoid shape long in one direction defined by. Hereinafter, the electrode structure shown in FIG. 3 may be referred to as a “type B electrode structure”. In the illustrated example, the two first electrodes 11 are disposed between the bending points of the second electrodes 12, but three or more first electrodes 11 may be disposed. In other words, each first electrode 11 may have an electrode width that is approximately ½ or less of the average value of the widest portion and the narrowest portion of the electrode width of the second electrode 12 .

  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. Each pixel in the type B electrode structure is different in adjacent pixels in the vertical direction and adjacent pixels in the horizontal direction, and has four types of pixel edge shapes.

FIG. 4 is a schematic plan view showing another example of the electrode structure. As shown in FIG. 4A, the electrode edge of each second electrode 12 extending in the left-right direction in the drawing is formed in a sawtooth shape, and a 1/2 pitch of the sawtooth is an electrode of each first electrode 11. It is set almost equal to the width. As shown in FIG. 4B, each second electrode 12 is arranged in a state where one apex angle portion (bending point) of the saw blade overlaps with the inter-electrode portion of the first electrode 11. 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 a substantially rhombus shape long in one direction defined by Hereinafter, the electrode structure shown in FIG. 4 may be referred to as a “type C electrode structure”. In the illustrated example, the two first electrodes 11 are disposed between the bending points of the second electrodes 12, but three or more first electrodes 11 may be disposed. In other words, each first electrode 11 may have an electrode width of approximately ½ or less of the electrode width of the second electrode 12 .

  In FIG. 4, 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. Each pixel in the type C electrode structure has the same pixel edge shape in adjacent pixels in the vertical direction and in adjacent pixels in the horizontal direction.

  FIG. 5 is a schematic plan view showing another example of the electrode structure. The electrode structure shown in FIG. 5 is the same as the type A electrode structure shown in FIG. 2 described above, except that each of the first electrodes 11 is also bent, and the electrode edge is formed into a polygonal line. Specifically, as shown in FIG. 5B, each of the first electrodes 11 has one electrode edge formed in a linear shape and the other electrode edge formed in a sawtooth shape. Further, in this example, two first electrodes 11 disposed so as to face each other with sawtooth electrode edge sides are paired, and the pair of first electrodes 11 are repeatedly disposed. Thereby, the utilization efficiency of the space for arrange | positioning the 1st electrode 11 increases. Hereinafter, the electrode structure shown in FIG. 5 may be referred to as a “type D electrode structure”. Note that FIG. 5 shows an example, and both electrode edges of each first electrode 11 may be formed in a sawtooth shape. Moreover, you may combine the 1st electrode 11 by which one or both electrode edge was formed in the shape of a broken line in this way with each above-mentioned type B and C electrode structure.

  Next, the results of actually producing a liquid crystal display device having the above-described pixel structures of types A to D and performing the orientation structure observation and the 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 the first electrode 11 and the second electrode 12 was set to 0.03 mm. The electrode width of the first electrode 11 is 0.185 mm, the electrode width of the second electrode is 0.4 mm for types A, C and D, and the average value of the widest and narrowest width is 0.4 mm for type B. It was. The bending angle 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. 6 is a diagram showing an alignment texture observation image when a voltage is applied to a liquid crystal display device having a type A electrode structure. As shown in the drawing, it was found that the uniformity of the dark region generated near the short side and the long side of the pixel edge is improved as compared with the liquid crystal display device of the conventional example. Also in the appearance observation from the opposite viewing direction, it was found that the display uniformity was remarkably improved as compared with the liquid crystal display device of the conventional example, and very good uniformity was realized.

  FIG. 7 is a diagram showing an alignment structure observation image when a voltage is applied to a liquid crystal display device having a type D electrode structure. Similar to the example shown in FIG. 6, the uniformity of dark regions generated in the vicinity of the short side and the long side of the pixel edge is improved, and the external appearance observation from the anti-viewing direction is significantly more than the conventional liquid crystal display device. It was found that the display uniformity was improved and a very good uniformity was achieved.

  For the liquid crystal display devices of the examples shown in FIGS. 6 and 7, display uniformity in the case of bright display during front view observation under multiplex drive conditions with 1/64 duty, 1/9 bias, and frame inversion waveform When the lower limit value of the frame frequency at which the above is obtained is examined, it is 80 Hz and 75 Hz, respectively, and it is clear that the lower limit value of the frame frequency is lower than that of the conventional liquid crystal display device.

  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 (6)

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 vertically aligned liquid crystal layer having a pretilt angle provided between one surface of the first substrate and one surface of the second substrate ;
A pair of polarizing plates respectively disposed on the outside of the first substrate and the outside of the second substrate;
Including
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 treatment in a direction orthogonal to the second direction,
The first electrode has a linear shape with electrode edges on both sides extending in the first direction;
The second electrode has a polygonal line shape including a line segment in which the electrode edges on both sides obliquely form an angle of greater than 0 ° and 15 ° or less with the second direction ;
The pixel edge is defined by the oblique line segment of the electrode edge of the first electrode and the electrode edge of the second electrode,
The pixels Ri shape der extending along the first direction than the second direction,
The pair of polarizing plates is arranged such that each absorption axis forms an angle of 45 ° with the direction of the alignment treatment.
Liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the pixel has a parallelogram shape extending along the first direction.   The liquid crystal display device according to claim 1, wherein the pixel has a trapezoidal shape extending along the first direction. 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 vertically aligned liquid crystal layer having a pretilt angle provided between one surface of the first substrate and one surface of the second substrate ;
A pair of polarizing plates respectively disposed on the outside of the first substrate and the outside of the second substrate;
Including
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 treatment in a direction orthogonal to the second direction,
The first electrode has a polygonal shape including a line segment in which an electrode edge on one side is oblique to the second direction;
The second electrode has a polygonal line shape including a line segment in which the electrode edges on both sides obliquely form an angle of greater than 0 ° and 15 ° or less between the second direction ,
The pixel edge is defined by the oblique line segment of the electrode edge of the first electrode and the electrode edge of the second electrode,
The pixels Ri shape der extending along the first direction than the second direction,
The pair of polarizing plates is arranged such that each absorption axis forms an angle of 45 ° with the direction of the alignment treatment.
Liquid crystal display device.   The oblique line segment of the electrode edge of the second electrode is a straight line segment,
  The liquid crystal display device according to claim 1 or 4.   The alignment direction of the liquid crystal molecules at substantially the center in the layer thickness direction of the liquid crystal layer is parallel to the first direction;
  The liquid crystal display device according to claim 1, 4 or 5.