JP4600463B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device capable of improving transmittance.

  As a liquid crystal display device capable of obtaining a high contrast and a wide viewing angle, a liquid crystal display device that controls the orientation of liquid crystal molecules using an electric field in a substantially horizontal direction with respect to two transparent substrates, that is, FFS (Fringe-Field Switching) ) Mode and IPS (In-Plain Switching) mode are known. In this liquid crystal display device, one transparent substrate is provided with both a pixel electrode to which a display signal is supplied and a common electrode to which a common potential is supplied.

  The case where the liquid crystal display device is in the FFS mode will be described. For example, a plurality of linear portions and slits are alternately arranged in parallel on the pixel electrode, and the pixel electrode and the common electrode face each other with an insulating film therebetween. Be placed. The liquid crystal molecules are initially aligned according to the rubbing direction of the alignment film. When a display signal is applied to the pixel electrode, the liquid crystal molecules correspond to an electric field extending from the linear portion of the pixel electrode to the common electrode extending below the slit, that is, an electric field substantially in the horizontal direction with respect to the transparent substrate. The orientation direction is controlled. Optical control is performed through the liquid crystal molecules, and white display or black display is performed.

By the way, as an FFS mode liquid crystal display device, for example, a first transparent substrate and a second transparent insulating substrate are arranged opposite to each other at a predetermined distance via a liquid crystal layer including a plurality of liquid crystal molecules, and a plurality of liquid crystal display devices are arranged on the first transparent substrate. A gate pass line and a data pass line are formed and arranged in a matrix form so as to limit unit pixels, a thin film transistor is provided at an intersection with these, and a counter electrode made of a transparent conductor is arranged in each unit pixel. A plurality of upper and lower slits that form a fringe field together with the counter electrode are arranged in each unit pixel, arranged with a predetermined inclination that is symmetric about the long side of the pixel, A fringe field switching mode liquid crystal display device having a configuration including a pixel electrode made of a transparent conductor has been proposed (for example, Patent Document 1). Irradiation).
JP 2002-182230 A (first page, FIG. 3)

  However, in the conventional example described in Patent Document 1, a rectangular pixel electrode is disposed in a region surrounded by the gate pass line and the data pass line, and the pixel electrode has a short side parallel to the gate pass line. A plurality of slits that are inclined in parallel with each other and a case in which an upper slit and a lower slit having an inclination angle that is symmetrical at the center position in the longitudinal direction of the pixel electrode are formed. Although the transmittance can be improved, the pixel electrode is formed in a rectangular shape and a slit that is inclined with respect to the short side is formed on the pixel electrode. An electrode portion having a right triangle shape remains between the slit and the outer peripheral edge, and there is an unsolved problem that the transmittance is reduced at this portion.

  Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and an object thereof is to provide a liquid crystal display device capable of improving the transmittance of an electrode forming a slit.

In order to achieve the above object, a liquid crystal display device according to a first embodiment includes at least a pair of substrates facing each other with a liquid crystal layer interposed between pixels forming a display portion and one substrate of the pair of substrates. A common electrode and a pixel electrode that drive the liquid crystal molecules of the liquid crystal layer that are provided with an insulating film interposed therebetween, and the electrode on the liquid crystal layer side of the common electrode and the pixel electrode is the pixel A slit inclined at a predetermined angle with respect to the longitudinal direction of the liquid crystal, and an opposing outer peripheral edge parallel to the slit, wherein the slit is formed in parallel with each other, and the longitudinal direction of the slit of the electrode on the liquid crystal layer side The electrode is formed in a comb-like shape, extending to one of the opposing outer peripheral edges of the liquid crystal layer, and the electrode on the liquid crystal layer side is disposed so that the outer electrode portion at least partially overlaps the drain line. Yes.

In the first embodiment, since the electrode formed with the slit among the common electrode and the pixel electrode has an opposing outer peripheral edge parallel to the slit, there is no extra electrode portion on the opposing outer peripheral edge parallel to the slit, so that the transmission of the pixel The rate can be improved.

In addition, by arranging the outer electrode portion of the electrode on the liquid crystal device side and the drain line so that at least part of them overlap each other, the end of the slit can be brought closer to the drain line, and the transmittance in the pixel is further improved. be able to.

In addition, one end of the slit extends to one of the opposing outer peripheral edges on the longitudinal direction side of the slit, and the electrode has a comb-tooth shape. Therefore, the transmittance is further improved compared to the case where the electrode is formed in a parallelogram shape. Can be made.

Further, since a plurality of slits are formed in parallel with each other, the transmittance of the pixel can be improved.
Further, the liquid crystal display device according to another embodiment, the liquid crystal layer side of the electrode is characterized by being arranged such portion outer electrodes do not overlap with at least part of the gate line.

In this embodiment, since the outer electrode portion of the electrode on the liquid crystal layer side is arranged so that at least a part of the gate line does not overlap, the outer electrode portion and the lower electrode formed larger than the electrode on the liquid crystal layer side The liquid crystal molecules between the outer electrode portion and the gate line can be controlled by the electric field, and the transmittance in the pixel can be further improved.

Furthermore, in a liquid crystal display device according to another embodiment, the slit formed in the electrode on the liquid crystal layer side is formed to be inclined at a predetermined angle with respect to the rubbing direction.

In this embodiment, since the slit is formed at a predetermined angle with respect to the rubbing direction, the rotation direction of the liquid crystal molecules in the liquid crystal layer can be stabilized.

Furthermore, a liquid crystal display device according to another aspect is characterized in that the slit is formed by using a mask in which an extended electrode portion is formed at a portion where disclination occurs on the opening side.

In this embodiment, when forming the electrodes in a comb shape, is performed by using the mask extended electrode portion is formed at a site disclination on the opening side of the slit occurs, longitudinal opening It can suppress that an edge part becomes circular arc shape, and can suppress disclination.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing an embodiment in which the present invention is applied to a liquid crystal display device operating in a normally black FFS mode. In FIG. 1, reference numeral 1 denotes a liquid crystal display device including a display unit. 2 includes a plurality of pixels 3 arranged in a matrix. In FIG. 1, only some pixels 3 of the display unit 2 are shown.

  As shown in FIG. 1, the display unit 2 is formed in a rectangular shape in which the X direction is a horizontal direction and the Y direction is a vertical direction, and a plurality of gate lines to which pixel selection signals are supplied along the horizontal direction. 4 are arranged at a predetermined interval, and drain lines 5 to which display signals are supplied are arranged at a predetermined interval along the vertical direction. The horizontal direction of the display unit 2 is set to be parallel to the absorption axis of the polarized sunglasses when the display unit 1 is viewed through the polarized sunglasses.

A pixel 3 is arranged in a pixel region surrounded by the gate line 4 and the drain line 5. Each pixel 3 is provided with a thin film transistor TR having the gate line 4 as a gate electrode at the upper left corner of the pixel formation region.
As shown in the cross-sectional view of FIG. 2, the pixel 3 has a first transparent substrate 12 made of glass or the like having a multilayer structure and a first polarizing plate 11 formed on the lower surface facing the backlight 10. A buffer film 13 is formed on the upper surface of the first transparent substrate 12, and an active layer 14 made of U-shaped polysilicon as viewed in FIG. The gate insulating film 15 is disposed so as to cover the active layer 14.

  On the upper surface of the gate insulating film 15 facing the active layer 14, the gate line 4 is disposed so as to pass through the active layer 14 twice to form a double gate structure. The gate insulating film 15 and the gate line 4 are covered with an interlayer insulating film 16. On the interlayer insulating film 16, a drain line 5 connected to the drain 17 of the thin film transistor TR through the contact hole CH1 and a source electrode 19 connected to the source 18 through the contact hole CH2 are arranged.

The drain line 5 and the source electrode 19 are covered with a passivation film 20, and a planarizing film 21 is formed on the passivation film 20. The passivation film 20 is not always necessary and can be omitted.
On the planarizing film 21, a common electrode 22 having an opening 22 a is disposed at a position facing the source electrode 19. For example, the common electrode 22 is formed as a solid film in the display effective region where the pixel 3 is disposed, and a common potential is supplied to the common electrode 22 through a contact hole (not shown) in the region where the pixel 3 is not disposed. It is connected to an electrode wire (not shown). Further, it may be formed in a strip shape connected in parallel to the gate line or the drain line, or the common electrode line may be connected to each pixel.

A pixel electrode 24 is disposed on the common electrode 22 via an insulating film 23. The pixel electrode 24 is connected to the source electrode 19 through a contact hole CH 3 formed through the insulating film 23, the opening 22 a of the common electrode 22, the planarizing film 21, and the passivation film 20.
The pixel electrode 24 is covered with an alignment film 25, and the rubbing direction of the alignment film 25 is set to be parallel to the transmission axis of the first polarizing plate 11.

  A second transparent substrate 29 having a color filter 27 and an alignment film 28 on the lower surface is disposed on the alignment film 25 via a liquid crystal layer 26 having liquid crystal molecules M. Here, the rubbing direction of the alignment film 28 has the same rubbing direction as the alignment film 25 described above. The liquid crystal molecules M of the liquid crystal layer 26 are initially aligned according to the rubbing direction of the alignment films 25 and 28 and are homogeneously aligned.

Further, a second polarizing plate 30 having a transmission axis orthogonal to the first polarizing plate 11 is disposed on the upper surface of the second transparent substrate 29.
The rubbing direction of the alignment films 25 and 28 coincides with the horizontal direction (X direction) as shown in FIG. In the pixel electrode 24, as shown in FIG. 3, a plurality of slits S1 having a rectangular shape inclined by a predetermined angle θs1 with respect to the rubbing direction of the alignment films 25 and 28 are formed in parallel in the vertical direction with a predetermined interval L1. The so-called single slit configuration is adopted.

The pixel electrode 24 is formed with opposing outer peripheral edges 31 and 32 having short sides parallel to the slit S1 at positions separated by a predetermined distance L2 from the slits S1 on both ends in the vertical direction. Opposing outer peripheral edges 33 and 34 having relatively long long sides extending in the vertical direction connecting the left and right ends of 32 are formed to have a parallelogram-shaped outer shape.
Here, as shown in FIG. 2, each slit S <b> 1 applies a voltage between the pixel electrode 24 that is the upper electrode and the common electrode 22 that is the lower electrode formed through the insulating film 23, thereby This is an opening for driving the liquid crystal molecules M by the generated electric field. Since a plurality of slits S1 are formed in parallel in the vertical direction, the transmittance of the pixel 3 can be improved.

Each slit S1 has, for example, about +5 degrees to +15 degrees with respect to the rubbing direction of the alignment films 25 and 28 so that the tilt angle θs1 does not make the rotation direction of the liquid crystal molecules M of the liquid crystal layer 26 indefinite. , Preferably about +5 degrees larger.
In addition, each slit S1 is formed such that both ends in the longitudinal direction are inside a predetermined distance L3 with respect to the opposing outer peripheral edges 33 and 34 of the pixel electrode 24 facing the both ends. Eventually, the pixel electrode 24 is formed into a parallelogram shape by the outer electrode portions 35 and 36 forming the opposing outer peripheral edges 31 and 32 and the outer electrode portions 37 and 38 forming the opposing outer peripheral edges 33 and 34. 37 and 38 are connected by a connecting electrode portion 39 that forms a slit S1.

When the pixel electrode 24 is patterned, the corner may be slightly rounded by a photolithography process. In order to avoid this roundness as much as possible, if the pattern of the mask used for patterning is a pattern considering the optical proximity effect, the roundness can be suppressed to a level that can be ignored.
Further, as shown in FIG. 1, at least the outer electrode portion 35 of the pixel electrode 24 and the drain line 5 are arranged so that they partially overlap each other when viewed from above, so that the end portion of the slit S1 is drained. It can be brought closer to the line 5 and the transmittance in the pixel 3 can be further improved. Further, by arranging the outer electrode portion 35 of the pixel electrode 24 and the gate line 4 so as not to overlap each other, the outer electrode portion 35 and the common electrode 22 that is a lower electrode formed larger than the pixel electrode 24 The liquid crystal molecules M between the outer electrode portion 35 and the gate line 4 can be controlled by this electric field, and the transmittance in the pixel 3 can be further improved.

  The operation of the liquid crystal display device 1 having the above configuration will be described with reference to FIG. 2. In an off state where no electric field is generated between the common electrode 22 and the pixel electrode 24, the liquid crystal molecules M of the liquid crystal layer 26 are homogeneously aligned. The long axis direction is, for example, parallel to the transmission axis of the first polarizing plate 11. At this time, the light of the backlight 10 linearly polarized by the first polarizing plate 11 passes through the liquid crystal layer 26 with the polarization axis as it is and enters the second polarizing plate 30. However, this light is absorbed by the second polarizing plate 30 because its polarization axis is perpendicular to the transmission axis of the second polarizing plate 30. That is, the display is black (normally black).

  On the other hand, in the ON state in which an electric field is generated between the common electrode 22 and the pixel electrode 24, the major axis of the liquid crystal molecules M of the liquid crystal layer 26 is substantially horizontal with respect to the first transparent substrate 12 according to the electric field. Rotate. At this time, the light of the backlight 10 linearly polarized by the first polarizing plate 11 becomes elliptically polarized light due to birefringence in the liquid crystal layer 26, and enters the second polarizing plate 30. Among the elliptically polarized light, a component that coincides with the transmission axis of the second polarizing plate 30 is emitted and white display is performed.

At this time, since the opposing outer peripheral edges 31 and 32 of the outer electrode portions 35 and 36 of the pixel electrode 24 are formed in parallel with the slit S1, the outer electrode portion is compared with the case where the outer shape of the pixel electrode 24 is rectangular. An extra margin does not occur in 35 and 36, and the transmittance of each pixel 3 can be improved.
When each pixel 3 on which the pixel electrode 24 is arranged operates by so-called line inversion driving, display signals having different polarities are supplied to the pixel electrodes 24 of the pixels 3 adjacent in the vertical direction. Therefore, a desired display may not be obtained by processing between different display signals, and a display defect may occur in the vicinity of the boundary between the pixels 3. In order to avoid this problem, it is preferable to separate the pixel electrodes 24 of the pixels 3 adjacent in the vertical direction as much as possible. However, if the separation distance is too large, the transmittance is lowered.

  Therefore, the distance between the opposing outer peripheral edge 31 of one pixel electrode 24 and the opposing outer peripheral edge 32 of the other pixel electrode 24 is such that the liquid crystal molecules M outside the opposing outer peripheral edges 31 and 32 of the pixel electrode 24 are rotated by a desired electric field. It is preferable to make the range equal to or slightly larger than twice the range in which the value can be obtained. For example, among adjacent pixel electrodes 24, if the distance between the outer peripheral edge 31 of one pixel electrode 24 and the outer peripheral edge 32 of the other pixel electrode 24 is D1, 5 μm <D1 <15 μm, which is a preferable example Is 7 μm <D1 <10 μm.

  In the first embodiment, when the end shape of the slit S1 is rounded, there is a region where the rotation direction of the liquid crystal molecules M is reversed with respect to a desired direction. Disclination, which is a phenomenon in which the area to be displayed is black and the transmittance is reduced, occurs. In order to suppress the occurrence of this disclination, it is necessary to form the end shape of the slit S1 without rounding. As a mask used in the photolithography process for this purpose, FIG. Such an opening electrode formation mask 100 is used.

  In the opening electrode forming mask 100, a basic light-transmitting pattern portion 114 corresponding to the shape of the slit S1 is formed at a position facing the slit S1 of the pixel electrode 24 with respect to the non-light-transmitting pattern portion 112, and further the basic light-transmitting pattern portion 114 is formed. Correction light-transmitting pattern portions 116 and 118 that extend the basic light-transmitting pattern portion 114 to suppress the occurrence of disclination are formed at the portions where the light pattern portion 114 is disclinated.

  Here, the part where the disclination of the basic light-transmitting pattern portion 114 occurs is when the slit S1 is inclined in the positive direction, that is, counterclockwise with respect to the rubbing direction as in the first embodiment described above. Are the corners of the second and fourth quadrants when the center point of the slit S1 is the origin of the XY coordinates, the X direction is the longitudinal direction of the slit, and the Y direction is the width direction of the slit. When the slit S1 is inclined in the negative direction, that is, in the clockwise direction with respect to the rubbing direction, disclination occurs at the corners of the first quadrant and the third quadrant in the XY coordinate system.

  The correction translucent pattern portion 116 communicates with the basic translucent pattern portion 114 so that the basic translucent pattern portion 114 is extended into the non-transparent pattern portion 112 as shown in an enlarged view in FIG. A relatively narrow strip-shaped pattern portion 119 communicating with the basic light-transmitting pattern portion 114 and extending at an angle of, for example, 45 degrees counterclockwise to the longitudinal direction, that is, the X axis, and the strip-shaped pattern portion For example, a triangular pattern portion 120 formed in an isosceles right triangle is formed at the extended end of 119.

Here, the width dimension B of the band-shaped pattern part 119 and the extension dimension C from the end of the basic light transmission pattern 114 to the tip of the triangular pattern part 120 are set smaller than the width dimension A of the basic light transmission pattern part 114. Yes.
For example, when the slit width S of the pixel electrode 24 formed after etching is about 4.0 μm, the width A of the basic light-transmitting pattern portion 114 can be about 3.4 μm. In this case, the extension dimension C of the correction translucent pattern portion 116 can be about 1.75 μm, and the width dimension B can be about 1.4 μm.

  In a high-definition liquid crystal display device, the width dimension A of the basic light-transmitting pattern portion 114 is often set to the minimum dimension near the resolution limit of the exposure apparatus. Therefore, normally, even if the minimum dimension of the pattern of the opening electrode formation mask is smaller than the resolution of the exposure apparatus, it cannot be exposed to a desired dimension and shape. Here, by utilizing the optical proximity effect, it is possible to obtain a fine pattern having a resolution lower than that of the exposure apparatus. This is to correct the shape of the peripheral portion of the basic pattern portion by providing a pattern portion for correcting the shape and dimensions in consideration of light diffraction etc. in the peripheral portion of the basic pattern portion near the resolution limit of the exposure apparatus, This is based on the ability to form a pattern with an accuracy higher than the resolution of the exposure apparatus. In the example of FIG. 4, the exposure pattern has an arc shape at the end portion in the longitudinal direction due to the limit of the resolution of the exposure apparatus only with the basic light transmission pattern portion 114, but the correction light transmission pattern portion 116 is provided. Thus, the arc shape can be corrected to obtain an exposure pattern that is very close to a rectangle.

  Therefore, in order to use the optical proximity effect, the dimension of the correction translucent pattern portion 116 is set smaller than the minimum dimension of the basic translucent pattern portion 114. In the above example, if the resolution of the exposure apparatus is about 3 μm, the minimum dimension of the basic translucent pattern portion 114 is set to about 3.4 μm, which is larger than the resolution of the exposure apparatus of about 3 μm, and The minimum dimension can be set to 1.4 μm, which is smaller than the resolution of the exposure apparatus of 3 μm.

  In such an opening electrode forming mask 100, the minimum dimension of the basic light-transmitting pattern portion 114 is set within the allowable range of the resolution of the exposure apparatus in accordance with a general exposure mask manufacturing method, and the longitudinal light-transmitting pattern portion 114 is arranged in the longitudinal direction. A light-transmitting pattern formed so as to be provided with a correction light-transmitting pattern portion 116 having a small dimension exceeding the resolution of the exposure apparatus can be used at the end.

Further, although the detailed illustration of the correction light-transmitting pattern portion 118 is omitted, the correction light-transmitting pattern portion 118 is formed in the same shape as that of the correction light-transmitting pattern portion 116.
When exposure is performed using the opening electrode forming mask 100 having the above-described configuration, light passes through the basic light-transmitting pattern portion 114 and the correction light-transmitting pattern portions 116 and 118, and the photosensitive resist is exposed. Since the characteristics of the photosensitive resist change when exposed, the exposed portion can be removed by using an appropriate developing solution, whereby the photosensitive resist is the same as the basic translucent pattern portion 114. An opening is formed in the photosensitive resist in shape. The pixel electrode 24 having the slit S1 having a shape corresponding to the opening of the photosensitive resist is formed by etching the transparent conductive material film for the pixel electrode using the photosensitive resist having the opening formed in this manner. Is done.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, by selecting the rubbing direction of the alignment films 25 and 30 and the inclination angle of the slit S1 formed in the pixel electrode 24, the pattern at the end of the slit S1 is limited due to patterning restrictions during manufacturing. Due to the arc shape, the angle between the direction of the electric field extending from the electrode portion of the pixel electrode to the common electrode extending below the slit S1 and the rubbing direction is not uniform, and the rotation direction of the liquid crystal molecules M is the desired direction. In contrast, there is a region that reverses, and the region that should normally be white display becomes black display and the transmittance decreases, that is, the disclination is reduced and the pixel transmittance is increased. is there.

That is, in the second embodiment, as shown in FIG. 6, the rubbing direction of the alignment films 25 and 30 has an inclination angle θr with respect to the horizontal direction (X direction). The inclination angle θr is, for example, about +20 degrees to +50 degrees, and preferably about +30 degrees. The transmission axis of the first polarizing plate 11 is, for example, parallel to this rubbing direction.
In the pixel electrode 24 having a parallelogram or substantially parallelogram shape, a plurality of slits S1 having a parallelogram shape or a substantially parallelogram shape composed of a long side E1 and a short side E2 are parallel to each other. Has been placed. The long side of the parallelogrammatic pixel electrode 24 is parallel to the vertical direction of the display unit 2. The inclination angle θs of the long side E1 of the slit S1 with respect to the horizontal direction of the display unit 1 is, for example, about +5 than the inclination angle θr in the rubbing direction so as not to make the rotation direction of the liquid crystal molecules M of the liquid crystal layer 26 indefinite. It is set to a degree of about +15 degrees, preferably about 5 degrees.

On the other hand, the inclination angle θe of the short side E2 of the slit S1 with respect to the horizontal direction is set larger than the inclination angle θs of the long side E1 and smaller than (θr + 90 °). That is, in the pixel electrode 24, at each end of the slit S1, one part Aac is an acute angle opening.
Further, the opposing outer peripheral edges 31 and 32 on the short side of the pixel electrode 24 have an inclination angle θs with respect to the horizontal direction. That is, the opposing outer peripheral edges 31 and 32 of the pixel electrode 24 are parallel to the long side E1 of the slit S1. These opposed outer peripheral edges 31 and 32 intersect the opposed outer peripheral edges 33 and 34 along the vertical direction at an acute angle. That is, there is an acute corner C at a location where the opposing outer peripheral edge 31 and the opposing outer peripheral edge 34 intersect and a location where the opposing outer peripheral edge 32 and the opposing outer peripheral edge 33 intersect.

  The corner C of the outer peripheral edge of the pixel electrode 24 and the corner Aac of the slit S1 may be slightly rounded due to the optical proximity effect of the photolithography process when the pixel electrode 24 is patterned. In order to use the roundness as much as possible, if the mask pattern used for patterning is a pattern that takes the optical proximity effect into consideration, the roundness can be suppressed to a level that can be ignored.

According to the second embodiment, the pixel electrode 24 is less likely to reverse the rotation direction of the liquid crystal molecules M in the vicinity of the corner Aac that is the acute angle of the slit S1, and thus disclination is suppressed. In the vicinity of the other end of the slit S1, the reversal of the rotation direction of the liquid crystal molecules M does not occur in the first place, so that no disclination occurs.
Further, since the region along the opposing outer peripheral edges 31 and 32 of the pixel electrode 24 is parallel to the long side E1 of the slit S1, the short side E2 of the slit S1 is disposed in the region along the opposing outer peripheral edges 31 and 32. In this region, since the reversal of the rotation direction of the liquid crystal molecules M does not occur, disclination does not occur. Furthermore, the rotation angle of the liquid crystal molecules M in this region can be made the same as that in the pixel 3 by the electric field between the opposed outer peripheral edges 31 and 32 of the pixel electrode 24 and the common electrode 22 arranged on the outside thereof. It can be set as the area | region which contributes to. Thereby, the disclination in the whole pixel 3 can be reduced and the transmittance can be increased.
In this case, the distance between the end of the slit S1 and the portion of the pixel electrode 24 along the opposing outer peripheral edges 33 and 34 that is closest to the end of the slit S1 and the opposing outer peripheral edges 33 and 34 is predetermined for forming the electrode material. Therefore, compared with the case where the distance of the nearest part is set to a predetermined distance, the end of the slit S1 is separated from the opposing outer peripheral edges 33 and 34.

  Since the margin at the end of the pixel electrode 24 reduces the transmittance, disclination occurs particularly when the opposing outer peripheral edges 33 and 34 are longer than the opposing outer peripheral edges 31 and 32 of the pixel electrode 24. The number will increase. That is, the transmittance of the entire pixel 3 is significantly reduced. On the other hand, in the present embodiment, since the inclination angle θs of the slit S1 is larger than the inclination angle θr in the rubbing direction, the edge of the slit S1 at the end of the pixel electrode 24 and the outer peripheral edge of the pixel electrode 24 facing each other. The distance to 33 and 34 can be reduced. Therefore, the decrease in the transmittance can be suppressed.

Next, a third embodiment of the present invention will be described with reference to FIGS.
In the third embodiment, the pixel electrode is formed in a comb shape.
That is, in the third embodiment, as shown in FIGS. 7 and 8, the outer electrode portion 38 on the right side of the pixel electrode 24 in the first embodiment described above is not formed, and the pixel electrode 24 is formed in a comb shape. Except for the above, the configuration is the same as that of FIG. 1 and FIG. 3 described above, and the same reference numerals are given to the corresponding parts to FIG. 1 and FIG.

According to the third embodiment, since the outer electrode portion 38 of the pixel electrode 24 in the first embodiment is not formed, and the pixel electrode 24 is a comb-like pixel electrode, the end of the slit S1 is not formed and transmission is performed. The rate can be improved.
Also in the third embodiment, it is necessary to form the comb-like pixel electrode 24 without rounding the end shape in order to prevent disclination, and this is used in the photolithography process for this purpose. As the mask, an opening electrode formation mask 200 as shown in FIG. 9 is used.

  In the opening electrode forming mask 200, a basic light-transmitting pattern portion 214 corresponding to the shape of the slit S1 is formed at a position facing the slit S1 of the pixel electrode 24 with respect to the non-light-transmitting pattern portion 212. By expanding the non-transparent pattern portion 216 for correction and the basic translucent pattern portion 214 to suppress the occurrence of disclination by reducing the basic translucent pattern portion 214 to the portion where the disclination of the light pattern portion 214 occurs. A correction translucent pattern portion 218 that suppresses the occurrence of disclination is formed.

  Here, the part where the disclination of the basic light-transmitting pattern portion 114 occurs is when the slit S1 is inclined in the positive direction, that is, counterclockwise with respect to the rubbing direction as in the third embodiment described above. In this case, when the center point of the slit S1 is the origin of the XY coordinates, the X direction is the longitudinal direction of the slit, and the Y direction is the width direction of the slit, the corner portions D of the second quadrant and the fourth quadrant are obtained. When the slit S1 is inclined in the negative direction, that is, in the clockwise direction with respect to the rubbing direction, disclination occurs at the corners of the first quadrant and the third quadrant in the XY coordinate system.

  As shown in the enlarged view of FIG. 10, the non-transparent pattern portion 216 for correction is a form in which the non-transparent pattern portion 212 is expanded into the basic translucent pattern portion 214, in other words, the basic translucent pattern portion 214 is reduced. The non-transparent pattern portion 212 is connected to the non-transparent pattern portion 212, and is connected to the non-transparent pattern portion 212 so as to extend at an angle of 45 degrees counterclockwise with respect to the longitudinal direction, that is, the X axis. The band-shaped non-light-transmitting pattern portion 219 having a narrow width and the triangle non-light-transmitting pattern portion 220 formed at an extended end of the band-shaped non-light-transmitting pattern portion 219, for example, a right-angled isosceles triangle.

Here, the width dimension I of the band-shaped non-transparent pattern portion 219 and the extension dimension J from the end of the non-translucent pattern 212 to the tip of the triangular non-transparent pattern portion 220 are the width dimension H of the non-transparent pattern portion 212. Is set smaller than.
For example, when the width of the elongated electrode portion of the pixel electrode 24 formed after etching, that is, the width W of the line is about 3.0 μm, the width H of the non-light-transmitting pattern portion 212 is about 3. In this case, the extension dimension J of the non-transparent pattern portion for correction 216 can be about 1.5 μm, and the width dimension I can be about 1.4 μm.

  As described above with reference to FIGS. 4 and 5, by utilizing the optical proximity effect, it is possible to obtain a fine pattern below the resolution of the exposure apparatus. In the example of FIG. With only the non-transparent pattern 212, the arc shape is corrected by providing a fine correction non-transparent pattern portion 216 in an arc shape at the end in the longitudinal direction of the exposure pattern due to the limit of the resolution of the exposure apparatus. Thus, the exposure pattern can be made substantially rectangular.

  Therefore, in order to use the optical proximity effect, the dimension of the correction non-light-transmitting pattern part 216 is set smaller than the minimum dimension of the basic light-transmitting pattern part 214 or the non-light-transmitting pattern 212. In the above example, assuming that the resolution of the exposure apparatus is about 3 μm, the minimum dimension of the basic translucent pattern portion 214 is set to about 3.6 μm, which is larger than the resolution of the exposure apparatus of about 3 μm, and the non-transparent pattern for correction is used. The minimum dimension of the portion 216 can be about 1.4 μm, which is smaller than the resolution of the exposure apparatus of 3 μm.

  In such an opening electrode forming mask 100, the minimum dimension of the basic light-transmitting pattern portion 114 is set within the allowable range of the resolution of the exposure apparatus in accordance with a general exposure mask manufacturing method, and the longitudinal light-transmitting pattern portion 114 is arranged in the longitudinal direction. A light-transmitting pattern formed so as to be provided with a correction light-transmitting pattern portion 116 having a small dimension exceeding the resolution of the exposure apparatus can be used at the end.

Further, the correction translucent pattern portion 218 has the same configuration as the correction translucent pattern portion 118 of FIGS. 4 and 5 described above.
In the third embodiment, the case where the pixel electrode 24 of the first embodiment described above is comb-shaped has been described. However, the present invention is not limited to this, and the pixel electrode of the second embodiment described above. May be comb-shaped.

In the first to third embodiments, the case where the longitudinal direction of the slit S1 of the pixel electrode 24 is inclined in the positive direction with respect to the rubbing direction has been described. However, the present invention is not limited to this. Further, it may be inclined in the negative direction with respect to the rubbing direction.
In the first to third embodiments, the case where the pixel electrode 24 of the common electrode 22 and the pixel electrode 24 is disposed on the liquid crystal molecule M side and the slit S1 is formed has been described. When the common electrode 22 is disposed on the liquid crystal molecule M side, the slit S1 may be formed in the common electrode 22 instead of the pixel electrode 24.

  Furthermore, in the first to third embodiments, the active layer 14 of the thin film transistor TR is formed in a U shape, and the active layer 14 has a double gate structure so that the gate line 4 crosses twice. Although described above, the present invention is not limited to this, and as shown in FIG. 11, the active layer 14 is formed in a straight line, and the branching portion branches into the gate line 4 at the position of the active layer 14 accordingly. 300 may be formed so that the active layer 14 has a double gate structure in which the gate line 4 crosses twice.

  In the first to third embodiments, the case where the pixel 3 operates in the normally black FFS mode has been described. However, the present invention is not limited to this, and the normally white FFS mode is used. The present invention can also be applied to a liquid crystal display device that operates according to the above. In this case, the relationship between the transmission axes of the first polarizing plate 11 and the second polarizing plate 30 and the rubbing direction of the alignment films 25 and 28 may be changed corresponding to the normally white type.

1 is a plan view showing a liquid crystal display device according to a first embodiment of the present invention. It is sectional drawing on the AA of FIG. It is a top view which shows the pixel electrode of FIG. It is a top view which shows the mask for opening part application applied to 1st Embodiment. It is a figure which shows the detail of the correction | amendment translucent pattern part of FIG. It is a top view of the pixel electrode which shows the 2nd Embodiment of this invention. It is a top view which shows the liquid crystal display device by the 3rd Embodiment of this invention. It is a top view which shows the pixel electrode of FIG. It is a top view which shows the mask for opening part application applied to 3rd Embodiment. It is a figure which shows the detail of the correction | amendment non-translucent pattern part of the mask for opening part formation. It is a top view which shows the other structure of a thin-film transistor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Display part, 3 ... Pixel, 4 ... Gate line, 5 ... Drain line, 10 ... Back light, 11 ... 1st polarizing plate, 12 ... 1st transparent substrate, 13 ... Buffer film , 14 ... Active layer, 15 ... Gate insulating film, 16 ... Interlayer insulating film, 17 ... Drain, 18 ... Source, 19 ... Source electrode, 20 ... Passivation film, 21 ... Planarization film, 22 ... Common electrode, 23 ... Insulation Film, 24 ... pixel electrode, 25 ... alignment film, 26 ... liquid crystal layer, 27 ... color filter, 28 ... alignment film, 29 ... second transparent substrate, 30 ... second polarizing plate, TR ... thin film transistor, S1 ... slit , 31, 32 ... opposing outer peripheral edge, 33, 34 ... opposing outer peripheral edge, 35 to 38 ... outer electrode part, 100 ... opening forming mask, 112 ... non-light-transmitting pattern part, 114 ... basic light-transmitting pattern part, 116 118 ... Transparent light for correction Over down portion, 200 ... opening forming mask, 212 ... non-light pattern section, 214 ... Basic translucent pattern portion 216 ... non-light-transmitting pattern portion for correcting, 218 ... correction translucent pattern portion

Claims (4)

A pixel forming the display portion drives at least a pair of substrates opposed to each other with a liquid crystal layer interposed therebetween, and liquid crystal molecules of the liquid crystal layer provided on one of the pair of substrates with an insulating film interposed therebetween. A common electrode and a pixel electrode,
The electrode on the liquid crystal layer side of the common electrode and the pixel electrode has a slit inclined at a predetermined angle with respect to the longitudinal direction of the pixel, and has an opposing outer peripheral edge parallel to the slit ,
A plurality of the slits are formed in parallel to each other, extend to one of the opposing outer peripheral edges in the longitudinal direction of the slit of the electrode on the liquid crystal layer side, and the electrode has a comb shape,
The liquid crystal display device according to claim 1, wherein the electrode on the liquid crystal layer side is disposed so that an outer electrode portion at least partially overlaps the drain line . 2. The liquid crystal display device according to claim 1, wherein the electrode on the liquid crystal layer side is disposed such that an outer electrode portion does not at least partially overlap the gate line. A slit formed in the electrode of the liquid crystal layer side, the liquid crystal display device according to claim 1 or 2, characterized in that it is inclined at a predetermined angle formed relative to the rubbing direction. 4. The liquid crystal display device according to claim 1, wherein the slit is formed by using a mask in which an extended electrode portion is formed in a portion where disclination occurs. 5.

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