JP2006113206A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an excellent display quality in a liquid crystal display device wherein domain division is performed by providing slits obliquely from one side of a pixel electrode. <P>SOLUTION: In the liquid crystal display device 1, each pixel electrode 23 has slits SLT 3 and SLT 4 extending obliquely from one side thereof. In the two pixel electrodes 23 adjacent to each other in a first direction D1 in these pixel electrodes 23, parts of the sides forming acute angles to the slits SLT3 and SLT4 are opposed to each other. On the surface of a counter substrate opposed to an array substrate, a ridge-shaped projecting part PRT2 having a width W wider than a distance D between the parts opposed to each other is provided in each position corresponding to a region between the parts of the sides opposed to each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device.

  According to a VA (Vertically Aligned) mode liquid crystal display device using a liquid crystal material having a negative dielectric anisotropy and a vertical alignment film, a faster response speed than a TN (Twisted Nematic) mode liquid crystal display device. Can be realized. In addition, the VA mode liquid crystal display device does not require a rubbing process that causes defects such as electrostatic breakdown. Among them, a VA mode (hereinafter referred to as MVA mode) liquid crystal display device adopting a multi-domain method is particularly attracting attention because a wide viewing angle is relatively easy.

  In the MVA mode, each pixel region in the liquid crystal layer is divided into a plurality of domains having different tilt directions of liquid crystal molecules by forming an electric field gradient in the liquid crystal layer and / or providing protrusions on the substrate surface. To do. For example, a slit is provided in the pixel electrode, and a hook-shaped convex portion substantially parallel to the previous slit is provided on the surface of the counter substrate facing the array substrate, shifted from the slit.

  In the vicinity of the slit, the lines of electric force in the liquid crystal layer are inclined, so that the liquid crystal molecules also incline their molecular long axes. Further, in the vicinity of the ridge-shaped convex portion, the liquid crystal molecules tend to be aligned vertically with respect to the surface of the ridge-shaped convex portion. For this reason, the liquid crystal molecules also incline their molecular long axes. Therefore, in the liquid crystal display device adopting this structure, a plurality of domains with the slits and the ridge-shaped protrusions as boundaries are formed in each pixel region.

  By the way, the slit may be provided obliquely from one side of the rectangular pixel electrode. In this case, the liquid crystal molecules may be oriented in an undesired direction in the vicinity of the portion that forms an acute angle with the slit in the previous side. Such disorder of orientation results in a decrease in display quality such as a decrease in transmittance and roughness.

  This disorder of orientation is suppressed by, for example, further providing a hook-shaped convex portion on the surface of the counter substrate facing the array substrate so as to face the portion of the previous side that forms an acute angle with the slit. Can do. Hereinafter, the hook-shaped protrusions, that is, the hook-shaped protrusions extending in a direction parallel to any side of the rectangular pixel electrode are referred to as “parallel hook-shaped protrusions”. A hook-like convex portion extending in an oblique direction with respect to the side of the pixel electrode is referred to as an “oblique hook-like convex portion”.

  In order to suppress the disorder of alignment by the parallel saddle-shaped convex portions, the parallel saddle-shaped convex portions need to face the sides of the pixel electrode. For this reason, the width of the parallel saddle-shaped convex portion must be sufficiently wide in consideration of an alignment error between the array substrate and the counter substrate.

  However, when the parallel saddle-shaped convex portion is widened, if the distance between adjacent pixel electrodes is short, the parallel saddle-shaped convex portion designed to face one side of a certain pixel electrode is However, one side that originally does not need to face the parallel saddle-shaped convex part may face the other side. In this case, the alignment of the liquid crystal molecules is disturbed in the pixel corresponding to the latter. In addition, when the distance between the pixel electrodes is increased to prevent this, the aperture ratio decreases.

  An object of the present invention is to realize an excellent display quality in a liquid crystal display device in which a slit is provided obliquely from one side of a pixel electrode to perform domain division.

  According to one aspect of the present invention, an array substrate including a first substrate and a plurality of pixel electrodes arranged in first and second directions substantially orthogonal to each other on one main surface thereof, and facing the plurality of pixel electrodes A counter substrate including the second substrate and a counter electrode provided on a surface facing the array substrate, and a liquid crystal having a negative dielectric anisotropy interposed between the array substrate and the counter substrate Each of the plurality of pixel electrodes is provided with a slit extending obliquely from one side thereof, and two of the plurality of pixel electrodes adjacent to each other in the first or second direction are: Each side of the side that faces the slit and an acute angle is faced, and each position corresponding to the region between the facing parts of the side is on the surface of the counter substrate facing the array substrate. Than the distance between the facing parts The liquid crystal display device characterized by ridge-shaped protrusions wide is provided is provided.

  According to the present invention, it is possible to realize excellent display quality in a liquid crystal display device that performs domain division by providing a slit obliquely from one side of a pixel electrode.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same referential mark is attached | subjected to the component which exhibits the same or similar function, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a plan view schematically showing a liquid crystal display device according to one embodiment of the present invention. FIG. 2 is an enlarged plan view showing the liquid crystal display device of FIG. FIG. 3 is a cross-sectional view of the liquid crystal display device of FIG. FIG. 4 is a simplified cross-sectional view of the liquid crystal display device of FIG. FIG. 5 is a plan view showing an array substrate of the liquid crystal display device of FIG. FIG. 6 is a plan view showing a counter substrate of the liquid crystal display device of FIG.

  1 and 2 illustrate a liquid crystal display device viewed from the counter substrate side. 5 illustrates the array substrate viewed from the counter substrate side, and FIG. 6 illustrates the counter substrate viewed from the array substrate side.

  In these drawings, some components are omitted for simplification. For example, in FIG. 1, the pixel electrode and the dielectric layer for forming the ridge-shaped convex portion are drawn, and other components are omitted. In FIG. 2, the pixel electrode, the ridge-shaped protrusions, and the liquid crystal molecules are drawn, and other components are omitted. In FIG. 3, the dielectric layer and the slit provided in the common electrode are omitted, and in FIG. 4, the switching element, the color filter, the spacer, the polarizing plate, and the like are omitted. In FIG. 5, the alignment film, the spacer, the color filter, the switching element, and the like are omitted, and in FIG. 6, the alignment film is omitted.

  The liquid crystal display device 1 is an MVA type liquid crystal display device. As shown in FIGS. 3 and 4, the liquid crystal display device 1 includes an array substrate 2 and a counter substrate 3. The array substrate 2 and the counter substrate 3 face each other with a slight gap. The structures of the array substrate 2 and the counter substrate 3 will be described in detail later.

  A spacer 8 is interposed between the array substrate 2 and the counter substrate 3 as shown in FIG. Here, as an example, columnar spacers are used as the spacers 8 and these columnar spacers 8 are formed on the array substrate 2. These spacers 8 serve to keep the distance between the array substrate 2 and the counter substrate 3 constant.

  An adhesive layer 4 is further interposed between the array substrate 2 and the counter substrate 3 as shown in FIG. The adhesive layer 4 is formed using an adhesive such as a thermosetting resin, for example. The adhesive layer 4 has a frame shape. The adhesive layer 4 bonds the array substrate 2 and the counter substrate 3 to each other, and forms an empty cell together with the array substrate 2 and the counter substrate 3.

  The frame formed by the adhesive layer 4 is open on one end face side of the empty cell. This opening is used as an injection port that communicates the internal space surrounded by the array substrate 2, the counter substrate 3, and the adhesive layer 4 with the external space.

  A transfer electrode (not shown) is interposed between the array substrate 2 and the counter substrate 3 and outside the frame formed by the adhesive layer 4. The array substrate 2 and the counter substrate 3 are electrically connected by this transfer electrode.

  The interior space of the empty cell is filled with the liquid crystal material 5 as shown in FIG. The liquid crystal material 5 forms a liquid crystal layer. In the liquid crystal display device 1, a liquid crystal material having a negative dielectric anisotropy, particularly a nematic liquid crystal having a negative dielectric anisotropy, is used as the liquid crystal material 5. For injection of the liquid crystal material into the empty cell, for example, an injection method such as a dip type or a dispenser type is used.

  The inlet of the empty cell is closed with a sealing body (not shown). The sealing body is formed, for example, by dispensing an adhesive such as an ultraviolet curable resin into the injection port and curing it.

  A polarizing plate 7 is attached to the outer surface of the array substrate 2. A polarizing plate 7 is also attached to the outer surface of the counter substrate 3.

  The liquid crystal display device 1 usually further includes a backlight that illuminates the outer surface of the array substrate 2.

Next, the structure of the array substrate 2 and the counter substrate 3 will be described.
As shown in FIG. 3, the array substrate 2 includes an insulating substrate 20 having optical transparency such as a glass substrate as a first substrate. On one main surface of the insulating substrate 20, wiring, an interlayer insulating film, a switching element 21 and the like are formed. On them, a color filter 22, a pixel electrode 23, a columnar spacer 8, and an alignment film 24 are sequentially formed. A peripheral light shielding layer (or frame) 25 is formed around the color filter 22.

  Wirings formed on the insulating substrate 20 are gate lines, signal lines, auxiliary capacitance lines, and the like made of aluminum, molybdenum, copper, or the like. The switching element 21 is, for example, a TFT having amorphous silicon or polysilicon as a semiconductor layer and aluminum, molybdenum, chromium, copper, tantalum, or the like as a metal layer, and includes wiring such as gate lines and signal lines, and pixel electrodes. 23. With such a configuration, the array substrate 2 can selectively apply a voltage to a desired pixel electrode 23.

  The color filter 22 includes blue, green, and red colored layers 22B, 22G, and 22R. The color filter 22 is provided with a contact hole, and the pixel electrode 23 is connected to the switching element 21 through the contact hole. The colored layers 22B, 22G, and 22R can be formed using a photosensitive resin containing a colored dye or a colored pigment.

  As the material of the pixel electrode 23, for example, a transparent conductive material such as ITO (Indium Tin Oxide) can be used. The pixel electrode 23 can be formed by, for example, forming a thin film by a sputtering method or the like and then patterning the thin film using a photolithography technique and an etching technique.

  The pixel electrodes 23 are arranged in first and second directions that are substantially parallel to the main surface of the insulating substrate 20 and intersect each other. In this example, the pixel electrodes 23 are arranged in a first direction D1 substantially parallel to the gate line and a second direction D2 substantially parallel to the signal line. The first direction D1 and the second direction D2 are substantially orthogonal to each other.

  The pixel electrodes 23 adjacent to each other in the first direction D1 form a slit SLT2 whose longitudinal direction is substantially parallel to the second direction D2. Further, the pixel electrodes 23 adjacent to each other in the second direction D2 form a slit SLT1 between which the longitudinal direction is substantially parallel to the first direction D1.

  As shown in FIGS. 1, 2, and 5, each pixel electrode 23 is provided with slits SLT1 ′, SLT3, and SLT4 in a rectangle having a side parallel to the first direction D1 and a side parallel to the second direction D2. It has a different shape. The slits SLT1 ', SLT3, and SLT4 provided in each pixel electrode 23 form a slit pattern.

  The longitudinal direction of the slit SLT1 'is parallel to the first direction D1. In this example, the pixel electrodes 23 are in a line-symmetric relationship with respect to the center line of the slit SLT1 '.

  The longitudinal direction of the slit SLT3 is parallel to a third direction D3 that intersects the first direction D1 and the second direction D2. In this example, the third direction D3 forms an angle of about 45 ° with respect to the first direction D1.

  The longitudinal direction of the slit SLT4 is parallel to a fourth direction D4 that intersects the first direction D1, the second direction D2, and the third direction D3. In this example, the fourth direction D4 is substantially orthogonal to the third direction D3.

  Hereinafter, a slit parallel to the first direction D1 or the second direction D2 is referred to as a “parallel slit”, and a slit parallel to the third direction D3 or the fourth direction D4 is referred to as an “oblique slit”.

  The side parallel to the second direction D2 of each pixel electrode 23 has a portion that forms an acute angle with the oblique slits SLT3 and SLT4 of the pixel electrode 23. In FIG. 5, these parts are shown surrounded by broken lines. The pixel electrode 23 adjacent to the first direction D1 faces a portion that forms an acute angle with the oblique slits SLT3 and SLT4 among the sides parallel to the second direction D2.

  Further, the side parallel to the first direction D1 of each pixel electrode 23 has a portion that forms an acute angle with the oblique slits SLT3 and SLT4 of the pixel electrode 23. The pixel electrode 23 adjacent to the second direction D2 faces a portion that forms an acute angle with the oblique slits SLT3 and SLT4 among the sides parallel to the first direction D1.

  In this example, the pixel electrodes 23 adjacent to each other in the first direction D1 are in a line-symmetric relationship with respect to a line parallel to the second direction D2, as shown in FIGS. In this example, the pixel electrodes 23 adjacent to each other in the second direction D2 are in a line-symmetrical relationship with respect to a line parallel to the first direction D1 and have the same shape and orientation as shown in FIG. .

  The alignment film 24 formed on the pixel electrode 23 is composed of a thin film made of a transparent resin such as polyimide. The alignment film 24 is given a vertical alignment without being rubbed.

  The peripheral light shielding layer 25 surrounds the color filter 22. The peripheral light shielding layer 25 can be formed using a photosensitive resin containing a coloring dye or a coloring pigment.

  As shown in FIGS. 3 and 4, the counter substrate 3 includes a light transmissive insulating substrate 30 such as a glass substrate as a second substrate. As shown in FIG. 4, a common electrode 33, a patterned dielectric layer 36, and an alignment film 34 are sequentially formed on one main surface of the insulating substrate 30.

  The common electrode 33 is formed as a continuous film facing all the pixel electrodes 23. As a material of the pixel electrode 23, for example, a transparent conductive material such as ITO can be used.

  The alignment film 34 is composed of a thin film made of a transparent resin such as polyimide. The alignment film 34 is given a vertical alignment without being subjected to a rubbing treatment.

  In this example, the dielectric layer 36 is patterned into the shape shown in FIGS. The patterned dielectric layer 36 generates convex patterns composed of bowl-shaped convex portions PRT1 to PRT4 shown in FIGS. 2 and 3 at each position corresponding to the pixel electrode 23 on the surface of the alignment film 34. .

  Each portion of the dielectric layer 36 corresponding to the pixel electrode 23 includes strip portions BP1 to BP4 shown in FIG. The longitudinal directions of the strips BP1 to BP4 are substantially parallel to the first direction D1 to the fourth direction D4, respectively. The saddle-like convex portions PRT1 to PRT4 are convex portions formed by the strip-like portions BP1 to BP4 on the surface of the alignment film 34, respectively.

  As shown in FIG. 2, the hook-shaped convex portion PRT1 is a parallel hook-shaped convex portion whose longitudinal direction is parallel to the longitudinal direction of the slit SL1. The hook-shaped convex part PRT1 faces the area surrounded by the broken line of the array substrate 2 shown in FIG. As shown in FIG. 2, the width W of the bowl-shaped protrusion PRT <b> 1 is wider than the distance D between the pixel electrodes 23 adjacent in the first direction. As shown in FIG. 2, the hook-shaped protrusion PRT1 overlaps with the portion of the outline of the pixel electrode 23 where the slit SLT1 is formed when the liquid crystal display device 1 is observed from a direction perpendicular to the main surface. Yes.

  As shown in FIG. 2, the hook-shaped convex part PRT2 is a parallel hook-shaped convex part whose longitudinal direction is parallel to the longitudinal direction of the slit SL2. As shown in FIG. 2, when the liquid crystal display device 1 is observed from a direction perpendicular to the main surface, the hook-shaped protrusion PRT2 overlaps with a portion of the outline of the pixel electrode 23 where the slit SLT2 is formed. Yes.

  As shown in FIG. 2, the hook-shaped convex portion PRT3 is an oblique hook-shaped convex portion whose longitudinal direction is parallel to the longitudinal direction of the slit SL3. As shown in FIGS. 2 and 4, the hook-shaped convex part PRT3 faces a region between the slits SLT3 adjacent to the direction intersecting the third direction D3, for example, the fourth direction D4.

  As shown in FIG. 2, the hook-shaped convex portion PRT4 is an oblique hook-shaped convex portion whose longitudinal direction is parallel to the longitudinal direction of the slit SL4. As shown in FIG. 2, the hook-shaped convex part PRT4 faces a region between the slits SLT4 adjacent to the direction intersecting the fourth direction D4, for example, the third direction D3.

  The slits SLT1 to SLT4 and the hook-shaped protrusions PRT1 to PRT4 control the alignment of the liquid crystal molecules LC contained in the liquid crystal material 5 as follows.

  When a first voltage having a small absolute value is applied between the pixel electrode 23 and the common electrode 33, an electric field is formed in the liquid crystal material 5. Since the liquid crystal material 5 has a negative dielectric anisotropy, a force is applied to the liquid crystal molecules LC to align them perpendicularly to the lines of electric force.

  In the upper part of the slits SLT1 to SLT4, the lines of electric force are tilted without being perpendicular to the main surfaces of the pixel electrode 23 and the common electrode 33. For example, in the upper part of the slit SLT3, the electric lines of force are inclined as shown by the broken lines in FIG. Therefore, in the upper part of the slits SLT1 to SLT4, a force for aligning the liquid crystal molecules LC perpendicularly to the oblique lines of electric force is applied. That is, for example, a force for tilting the liquid crystal molecules LC as shown in FIG.

  On the other hand, since the alignment films 24 and 34 are vertical alignment films, the alignment films 24 and 34 attempt to align the liquid crystal molecules LC perpendicularly to their film surfaces. For this reason, the alignment film 34 tends to tilt the liquid crystal molecules LC as shown in FIG.

  As a result, each pixel region corresponding to the pixel electrode 23 in the liquid crystal layer has different tilt directions of the liquid crystal molecules LC with the slits SLT1 to SLT4 and the ridge-shaped protrusions PRT1 to PRT4 as boundaries, as shown in FIG. Divided into multiple domains. In this example, in each pixel region, a total of four types of domains having different tilt directions of the liquid crystal molecules LC are formed.

  When the voltage applied between the pixel electrode 23 and the common electrode 33 is a second voltage having a larger absolute value compared to the first voltage, the liquid crystal molecules LC maintain their tilt directions while maintaining their molecular axes. And the angle formed by the main surfaces of the pixel electrode 23 and the common electrode 33 are reduced. In the liquid crystal display device 1, display is performed by using the change in the refractive index of the liquid crystal layer generated thereby.

  If the strips BP1 and BP2 are omitted, the parallel hook-shaped projections PRT1 and PRT2 do not occur on the surface of the alignment film 34. In this case, as described above, the liquid crystal molecules LC may be aligned in an undesired direction near the acute angle portion of the pixel electrode 23. This will be described with reference to FIG.

  FIG. 7 is a plan view schematically showing an example of the alignment state of liquid crystal molecules obtained when the parallel saddle-like convex portions are omitted from the liquid crystal display device of FIG. FIG. 7 illustrates a liquid crystal display device viewed from the counter substrate side. In FIG. 7, for the sake of simplicity, the pixel electrode 23, the ridge-shaped protrusion PRT3, and the liquid crystal molecules LC are drawn, and other components are omitted.

  In the vicinity of the slit SLT2, the electric lines of force in the liquid crystal layer are inclined in a plane perpendicular to the second direction D2. Similarly, in the vicinity of the slit SLT3, the electric lines of force in the liquid crystal layer are inclined in a plane perpendicular to the third direction D3. The electric field in the liquid crystal layer attempts to align the liquid crystal molecules in a direction perpendicular to the lines of electric force. On the other hand, the oblique saddle-shaped convex part PRT3 tends to tilt the liquid crystal molecules LC in a plane perpendicular to the third direction D3. As a result, as shown in FIG. 7, the liquid crystal molecules LC are separated from other regions in the same domain in the region near the acute angle portion sandwiched between one side parallel to the second direction D2 of the pixel electrode 23 and the slit SLT3. Are oriented in different directions.

  When the parallel saddle-like convex portions PRT2 are generated on the surface of the alignment film 34, the parallel saddle-like convex portions PRT2 tend to tilt the liquid crystal molecules LC in a plane perpendicular to the second direction D2. Therefore, as shown in FIG. 2, disorder of the alignment of the liquid crystal molecules LC as shown in FIG. 7 can be suppressed.

  Now, in this embodiment, a convex pattern composed of parallel saddle-like convex portions PRT1 and PRT2 and oblique saddle-like convex portions PRT3 and PRT4 is generated on the surface of the alignment film 34, and this convex pattern is shaped as shown in FIG. . Thus, even when the distance D between the pixel electrodes 23 adjacent to each other in the first direction D1 is short, the alignment disorder of the liquid crystal molecules LC due to the alignment error between the array substrate 2 and the counter substrate 3 is less likely to occur. be able to. This will be described with reference to FIG. 2 and FIG.

  FIG. 8 is a plan view schematically showing a liquid crystal display device according to a comparative example. FIG. 8 illustrates the liquid crystal display device viewed from the counter substrate 3 side. Further, in FIG. 8, for simplification, the pixel electrode 23, the ridge-shaped convex portions PRT to PRT4, and the liquid crystal molecules LC are drawn, and other components are omitted.

  The liquid crystal display device 1 shown in FIG. 8 has substantially the same structure as the liquid crystal display device 1 shown in FIG. However, in the liquid crystal display device 1 shown in FIG. 8, not only the pixel electrodes 23 adjacent in the second direction D2 but also the pixel electrodes 23 adjacent in the first direction D1 have the same shape and orientation. For this reason, the pixel electrodes 23 adjacent in the first direction D1 do not face portions of the sides that make an acute angle with the oblique slits SLT3 and SLT4.

  Therefore, in the liquid crystal display device 1 of FIG. 8, the parallel saddle-like convex part PRT2 is prevented from facing the part of the side of the pixel electrode 23 that forms an obtuse angle with the oblique slits SLT3 and SLT4. The convex pattern composed of PRT1 to PRT4 has the shape shown in FIG. That is, in the liquid crystal display device 1 of FIG. 8, in each column formed by the hook-shaped protrusions PRT2 in the second direction D2, the positions of the hook-shaped protrusions PRT2 are on the right side and the left side with respect to the center line of the slit SLT. They are staggered alternately.

  In the liquid crystal display device 1 of FIG. 8, in order for the parallel bowl-shaped convex part PRT2 to perform its intended function, the displacement of the array substrate 2 and the counter substrate 3 in the first direction D1 is changed in the first direction D1. It must be smaller than ½ of the distance D between adjacent pixel electrodes 23. Therefore, it is difficult to shorten the distance D in the liquid crystal display device 1.

  On the other hand, in the liquid crystal display device 1 of FIG. 2, the displacement of the array substrate 2 and the counter substrate 3 in the first direction D1 is the pixel electrode adjacent in the first direction D1 with the width W of the parallel bowl-shaped protrusion PRT2. If it is smaller than 1/2 of the difference (WD) with respect to the distance D between 23, the parallel hook-shaped convex part PRT2 can exhibit its intended function. Therefore, in this liquid crystal display device 1, even if the distance D is shortened, the alignment disorder of the liquid crystal molecules LC is hardly generated. That is, in addition to realizing a high aperture ratio, it is possible to suppress a decrease in transmittance due to disorder in the alignment of the liquid crystal molecules LC.

The difference (WD) is, for example, ( ) Μm or more. When the difference (WD) is small, high accuracy is required for alignment between the array substrate 2 and the counter substrate 3.

Further, when the difference (WD) is increased, the aperture ratio is decreased. Therefore, the difference (WD) is, for example, ( ) Μm or less.

  In this aspect, as described above, the width W of the ridge-shaped protrusion PRT2 is made larger than the distance D between the pixel electrodes 23 adjacent to each other in the first direction D1, and the ridge-shaped protrusion PRT2 is adjacent to the first direction D1. The regions face each other between the pixel electrodes 23. Instead, the width of the ridge-shaped protrusion PRT1 is made wider than the distance between the pixel electrodes 23 adjacent in the second direction D2, and the area between the pixel electrodes 23 adjacent to the ridge-shaped protrusion PRT1 in the second direction D2. You may face each other. Or you may employ | adopt both these structures.

  In this embodiment, the color filter 22 is disposed between the insulating substrate 20 and the pixel electrode 23, but the color filter 22 may be disposed between the insulating substrate 30 and the common electrode 33. In this embodiment, a columnar spacer is used as the spacer 8, but a granular spacer may be used as the spacer 8.

Examples of the present invention will be described below.
(Example)
In this example, the liquid crystal display device 1 shown in FIGS. 1 to 4 was manufactured by the method described below.

  First, film formation and patterning were repeated in the same manner as a normal array substrate formation process, and various wirings, TFTs 21 and the like were formed on the glass substrate 20. Next, a color filter 22 was formed by a conventional method on the surface of the glass substrate 20 on which the TFTs 21 and the like were formed.

  Next, ITO was sputtered on the color filter 22 to a thickness of about 0.1 μm through a mask having a predetermined pattern. Thereafter, a resist pattern was formed on the ITO film, and the exposed portion of the ITO film was etched using the resist pattern as a mask. As described above, the pixel electrode 23 shown in FIGS. 1 to 5 was formed. Here, the width of the slit SLT2, that is, the distance D between the pixel electrodes 23 adjacent in the first direction D1, is 6 μm. In addition, the widths of the slits SLT1 ', SLT3, and SLT4 provided in the pixel electrode 23 were 10 μm.

  Next, the photosensitive resin containing a black pigment was apply | coated to the surface in which the pixel electrode 23 of the glass substrate 20 was formed using the spinner. After drying this coating film, pattern exposure using ultraviolet rays, development using an aqueous alkaline solution, and baking were sequentially performed. Thereby, the spacer 8 and the peripheral light shielding layer 25 were obtained.

  Thereafter, a thermosetting resin was applied to the entire surface of the glass substrate 20 on which the pixel electrode 23 was formed, and this coating film was baked to form an alignment film 24 having a thickness of 70 nm showing vertical alignment. The array substrate 2 was produced as described above.

  Next, an ITO film was formed as a common electrode 33 on one main surface of a separately prepared glass substrate 30 by a sputtering method. Next, a photosensitive resin was applied onto the common electrode 33 using a spinner. After drying this coating film, pattern exposure using ultraviolet rays, development using an aqueous alkaline solution, and baking were sequentially performed. Thereby, the dielectric layer 36 was obtained. Here, the width of the belt-like portions BP1, BP3, and BP4 is 8 μm, and the width W of the belt-like portion BP2 is 16 μm.

  Subsequently, an alignment film 34 was formed on the surface of the glass substrate 30 on which the dielectric layer 36 was formed by the same method as described for the array substrate 2. The counter substrate 3 was produced as described above.

  Next, the array substrate 2 and the peripheral portion of the counter surface of the counter substrate 3 were bonded together using an epoxy thermosetting resin 4 to form an empty cell. A liquid crystal material 5 was injected into this empty cell by a dip method.

  Thereafter, the injection port was closed with an ultraviolet curable resin, and the polarizing plate 7 was attached to the outer surfaces of the array substrate 2 and the counter substrate 3. In accordance with the above method, a large number of liquid crystal display devices 1 shown in FIGS.

  Next, the characteristics of the liquid crystal display device 1 were evaluated. The results are shown in the following table. As shown in the following table, in this example, the liquid crystal display device 1 having excellent transmittance characteristics and viewing angle characteristics (horizontal direction) could be manufactured with a high yield. Such excellent viewing angle characteristics can be realized because the slit pattern provided on the pixel electrode 23 and the convex pattern formed by the dielectric layer 36 have the shape shown in FIG. This is thought to be due to the improvement.

  Further, many liquid crystal display devices 1 shown in FIGS. 1 to 4 are formed by the same method as described above except that the array substrate 2 and the counter substrate 3 are bonded to each other in the first direction D1 while being shifted from each other by ± 5 μm. Produced. When the characteristics of these liquid crystal display devices 1 were also evaluated, all the liquid crystal display devices 1 were able to display good images without roughness.

(Comparative Example 1)
In this example, many liquid crystal display devices 1 were produced by the same method as described in the above example except that the pixel electrode 23 and the dielectric layer 36 were formed in the shape shown in FIG. In this example, the width of the slit SLT2, that is, the distance D between the pixel electrodes 23 adjacent in the first direction D1, is 6 μm, and the widths of the slits SLT1 ′, SLT3, and SLT4 provided in the pixel electrode 23 are 10 μm. Further, the width of the belt-like portions BP1 to BP4 was 8 μm.

  The liquid crystal display device 1 was also evaluated for characteristics similar to those performed in the above examples. The results are shown in the following table. As shown in the table below, in this example, display failure occurred at a rate of about 20%.

  Next, the liquid crystal display device 1 in which these display defects occurred was observed in detail. As a result, it was found that some of the hook-shaped protrusions PRT2 originally faced the pixel electrode 23 adjacent to the pixel electrode 23 that should face each other, and the display image became rough due to the orientation reverse that occurred there.

(Comparative Example 2)
In this example, many liquid crystal display devices 1 were produced by the same method as described in the above example except that the pixel electrode 23 and the dielectric layer 36 were formed in the shape shown in FIG. In this example, the width of the slit SLT2, that is, the distance D between the pixel electrodes 23 adjacent in the first direction D1, is 10 μm, and the widths of the slits SLT1 ′, SLT3, and SLT4 provided in the pixel electrode 23 are 10 μm. Further, the width of the belt-like portions BP1 to BP4 was 8 μm.

The liquid crystal display device 1 was also evaluated for characteristics similar to those performed in the above examples. The results are shown in the following table. As shown in the following table, in this example, no display defect occurred, but the transmittance was remarkably smaller than that in Example and Comparative Example 1.

1 is a plan view schematically showing a liquid crystal display device according to one embodiment of the present invention. FIG. 2 is an enlarged plan view showing the liquid crystal display device of FIG. 1. Sectional drawing of the liquid crystal display device of FIG. FIG. 2 is a cross-sectional view illustrating the liquid crystal display device of FIG. 1 in a simplified manner. FIG. 2 is a plan view showing an array substrate of the liquid crystal display device of FIG. 1. FIG. 2 is a plan view showing a counter substrate of the liquid crystal display device of FIG. 1. The top view which shows roughly the example of the orientation state of the liquid crystal molecule obtained when a parallel saddle-like convex part is abbreviate | omitted from the liquid crystal display device of FIG. The top view which shows schematically the liquid crystal display device which concerns on a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Array substrate, 3 ... Opposite substrate, 4 ... Adhesive layer, 5 ... Liquid crystal material, 7 ... Polarizing plate, 8 ... Spacer, 20 ... Insulating substrate, 21 ... Switching element, 22 ... Color filter , 22B ... colored layer, 22G ... colored layer, 22R ... colored layer, 23 ... pixel electrode, 24 ... alignment film, 25 ... peripheral light shielding layer, 30 ... insulating substrate, 33 ... common electrode, 36 ... dielectric layer, 34 ... Alignment film, BP1 ... strip portion, BP2 ... strip portion, BP3 ... strip portion, BP4 ... strip portion, D ... distance, D1 ... first direction, D2 ... second direction, D3 ... third direction, D4 ... fourth direction LC ... liquid crystal molecule, PRT1 ... bowl-like convex part, PRT2 ... bowl-like convex part, PRT3 ... bowl-like convex part, PRT4 ... bowl-like convex part, SLT1 ... slit, SLT1 '... slit, SLT2 ... slit, SLT3 ... slit , SLT4 ... slit, W ... width.

Claims (3)

An array substrate including a first substrate and a plurality of pixel electrodes arranged in first and second directions substantially orthogonal to each other on one main surface thereof;
A counter substrate including a second substrate facing the plurality of pixel electrodes and a counter electrode provided on a surface facing the array substrate;
A liquid crystal material having a negative dielectric anisotropy interposed between the array substrate and the counter substrate;
Each of the plurality of pixel electrodes is provided with a slit extending obliquely from one side thereof,
Each two of the plurality of pixel electrodes adjacent to each other in the first or second direction faces a portion of the side that forms an acute angle with the slit,
On the surface of the counter substrate that faces the array substrate, hook-shaped convex portions that are wider than the distance between the facing portions are provided at positions corresponding to the regions between the facing portions of the side. A liquid crystal display device characterized by that.   2. The liquid crystal display device according to claim 1, wherein each of the plurality of pixel electrodes is a right-sided rectangular conductor layer provided with one or more slits.   Two of the plurality of pixel electrodes positioned on both sides of the portion of the array substrate facing the ridge-shaped protrusion are symmetrical with respect to a straight line parallel to the center line of the ridge-shaped protrusion. The liquid crystal display device according to claim 1, wherein:

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