JP3217616B2 - Liquid crystal display device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method of manufacturing the same, and more particularly, to a liquid crystal display device which is divided to achieve a wide viewing angle characteristic and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, demand for thin display devices, mainly personal computers, has been increasing. A liquid crystal display device has attracted attention as such a display device. A liquid crystal panel used in a liquid crystal display device has a structure in which liquid crystal is sandwiched between two glass substrates, and the outside of the liquid crystal panel is further sandwiched by a polarizing plate or the like. Is what you do. However, the pretilt that occurs when an orientation is imparted to liquid crystal molecules causes a viewing angle dependency, and the contrast is reduced or the contrast is reduced depending on the viewing direction. For example, when a voltage is applied to the liquid crystal layer, the liquid crystal molecules rise in a direction having a pretilt. Therefore, when viewed from this direction, the liquid crystal molecules are most visible.

In order to improve such viewing angle dependence, one pixel is divided into, for example, two regions, and the liquid crystal molecules are twisted in opposite directions by changing the alignment direction or making the pretilt angle different. I am trying to face it.
A liquid crystal display panel using such an orientation division method will be described with reference to FIG. FIG. 7 is a sectional view of a transmissive alignment division type liquid crystal display panel.

A liquid crystal layer 62 is sandwiched between a first substrate 101 on which a TFT matrix is formed and a second substrate 102 on which a color filter layer 58 is formed.
The first substrate 101 includes a transparent substrate 51, a gate bus line (gate electrode) 52, a gate insulating film 53, a pixel electrode 54, and an alignment film. The second substrate 102 includes a transparent substrate 57, a color filter 58, It comprises a common electrode 59 and an alignment film.

The alignment film on the opposing surface of the first substrate 102 and the second substrate 103 is a two-layer structure in which high pre-tilt alignment films 56 and 61 are selectively formed on lower low-tilt alignment films 55 and 60, respectively. Consists of a membrane. On the facing surface, low pretilt alignment regions and high pretilt alignment regions are alternately arranged, and a pair of high / low pretilt alignment region strip-shaped regions A and B are formed per pixel.

In addition, in the region A, the high pretilt alignment film 56 of the first substrate 102 and the low pretilt alignment film 60 of the second substrate 103 face each other.
The low pretilt alignment film 55 of the second substrate 103 and the high pretilt alignment film 61 of the second substrate 103 face each other. When the high / low pretilt alignment films face each other, the direction of tilt of the liquid crystal molecules sandwiched between the alignment films corresponds to the direction of tilt of the high pretilt alignment films 56 and 61.

Accordingly, assuming that the rubbing directions of the alignment films of the two substrates 102 and 103 are orthogonal to each other and are both in the direction from left to right in FIG.
7, the right side of the liquid crystal molecules is greatly inclined at the pretilt angle θ1 in the rubbing direction on the side of the high pretilt alignment films 56 and 61, and the twisting direction is A when viewed from above or below. The region and the region B are opposite to each other. The liquid crystal molecules on the side of the low pretilt alignment films 55 and 60 have a small pretilt angle θ2.

Further, by applying a voltage to the pixel electrode 54 and the common electrode 59, the liquid crystal molecules are turned into a high pretilt alignment film 56,
It rises in the direction in which the pretilt angle θ1 on the 61 side is further increased, that is, in the directions opposite to each other in the region A and the region B. As described above, since the A region and the B region in which the inclination of the liquid crystal molecules are opposite to each other and the directions of the twists are opposite to each other are present, the viewing angle dependency is averaged, and the viewing angle characteristics are improved.

Next, a method for forming an alignment film on the first substrate 101 will be described with reference to FIGS. 8A to 8C, reference numeral 100 denotes a substrate including the transparent substrate 51, the gate bus line 52, the gate insulating film 53, and the pixel electrode 54 illustrated in FIG. First,
As shown in FIG. 8A, after a low pretilt alignment film 55 and a high pretilt alignment film 56 are laminated on a substrate 100, a resist film 63 is further applied thereon. After exposing the resist film 63 with ultraviolet rays 65 via a mask 64,
Develop to form a resist mask 63a.

Next, as shown in FIG. 8B, an unnecessary portion of the high pretilt alignment film 56 is etched and removed by a resist mask 63a to form a strip-like pattern of the high pretilt alignment film 56. Next, as shown in FIG. 8C, the resist mask 63a is peeled off, and the exposed portion of the low pretilt alignment film 55 and the surface of the high pretilt alignment film 56 are rubbed in one direction with a nylon cloth or the like. In this way, an alignment film pattern in which the rubbing directions are the same and the band-like low / high pretilt alignment regions are alternately arranged.

The method of patterning an alignment film by photolithography has the advantage of high accuracy, but has the disadvantage of complicating the manufacturing process because it requires exposure / development, etching, and stripping steps. Was. In addition, since an alignment film material that can withstand development and etching must be used, the alignment film material is limited. In addition, the inherent characteristics of the alignment film material are impaired in this process.

To address such a problem, FIG.
A method for forming an alignment film pattern by a printing method such as gravure printing as shown in the cross-sectional views of (a) and (b) has been proposed. In this method, first, as shown in FIG. 9A, an alignment film material 56a is attached to the convex portion of a relief plate 66 such as a photosensitive resin engraved with the shape of a selectively formed high pretilt alignment film. As shown in FIG. 9B, the low pretilt alignment film 55
To the appropriate position on the high pretilt alignment film 56.
a is selectively attached. At this time, the size of the convex portion of the conventional relief printing plate 66 is determined such that the high pretilt alignment region and the low pretilt alignment region are finally one to one in consideration of the flow of polyimide.

According to this method, the alignment film can be selectively formed by ordinary printing, so that the steps are simplified, and the steps of exposure / development, etching, and peeling such as photolithography are not required. An alignment film having highly reliable characteristics can be formed without deterioration of characteristics.

[0014]

However, such a method of forming an alignment film pattern by printing uses a relief plate 66.
Is made of resin and has flexibility, and since the alignment film material is a liquid material such as polyimide, the projections of the relief plate 66 are deformed during printing, and the edges of the patterns of the high pretilt alignment films 56 and 61 are wavy. Or the width of the pattern is too wide
The pixel cannot be exactly divided into two.

When such substrates are stacked with a liquid crystal interposed therebetween, when the pattern width of the high pretilt alignment films 56 and 61 is wide, a region where the high pretilt alignment films 56 and 61 face each other is generated. In such a case, as shown in FIG. 3B, a reverse twist region in which the liquid crystal molecules are twisted in a direction opposite to that in a normal case easily occurs. The liquid crystal molecules S and W in the region sandwiched between the high / low pretilt alignment films 56/60 and 55/61 are normally twisted 90 degrees counterclockwise.
The liquid crystal molecules T and V in the region sandwiched by the high pretilt alignment films 56/61 are twisted 90 degrees in a direction opposite to the normal direction. When such a phenomenon occurs, light leakage or light non-transmission region occurs in the partial region, and the display quality is deteriorated.

The present invention has been made in view of such a problem, and a liquid crystal display in which one pixel is divided into regions having different orientations by opposing a high pretilt alignment film and a low pretilt alignment film. In the apparatus and its manufacturing method, without complicating the manufacturing process, to form an alignment division region where the high pretilt alignment films do not face each other,
The purpose is to improve display quality.

[0017]

SUMMARY OF THE INVENTION The first object of the present invention is to firstly control the orientation of liquid crystal molecules by applying a voltage to a first substrate and a second substrate which sandwich a liquid crystal layer. A first electrode formed on the first substrate and a second electrode formed on the second substrate for controlling light transmission;
A first alignment film formed on the substrate and having a high pretilt alignment region and a low pretilt alignment region adjacent to each other in a pixel; and a high pretilt alignment region formed on the second substrate and adjacent to each other in the pixel. And a second alignment film having a low pretilt alignment region. The low alignment of the second alignment film is provided in a region where the high pretilt alignment region of the first alignment film faces the second substrate. A pretilt alignment region exists, and the low pretilt alignment region of the first alignment film exists in a region where the high pretilt alignment region of the second alignment film faces the first substrate, and is adjacent to each other. A liquid crystal in which the low pretilt alignment regions in the first and second alignment films face each other near a boundary region between the high pretilt alignment region and the low pretilt alignment region. Achieved by shown device, the second,
The rubbing direction of the first and second alignment films is achieved by the liquid crystal display device according to the first aspect of the invention, and thirdly, the first and second alignment films are The liquid crystal display device according to the first or second invention, characterized in that the liquid crystal display device is constituted by a two-layer film in which a high pretilt alignment film is selectively formed on a low pretilt alignment film,
Fourth, the high pretilt alignment film is achieved by the liquid crystal display device according to the third invention, wherein the first bus line and the second bus line cross each other. Bus lines are formed on the first substrate, and a side end of the high pretilt alignment region of the first alignment film and the first substrate of the high pretilt alignment region of the second alignment film The side end of the area facing
The invention according to any one of the first to fourth inventions, characterized in that it is located between a center line along the longitudinal direction of the first or second bus line and a side end of the first electrode. Sixth, the invention is achieved by a liquid crystal display device, wherein a thin film transistor is formed for each pixel on the first substrate,
Is a gate bus line connected to the gate electrode of the thin film transistor, the second bus line is a drain bus line connected to the drain electrode of the thin film transistor, and the first electrode is The liquid crystal display device according to the fifth aspect of the present invention is characterized in that the liquid crystal display device is a pixel electrode connected to a source electrode. Seventh, the low pretilt alignment film gives a pretilt angle to liquid crystal molecules of 1 degree or less. The liquid crystal display device according to any one of the first to sixth inventions, wherein the pretilt angle given to the liquid crystal molecules by the high pretilt alignment film is at least 7 degrees.
Applying a voltage to control the alignment of liquid crystal molecules and forming a low pretilt alignment film on a third substrate on which a first electrode for controlling light transmission of the liquid crystal layer is formed; Forming a low pretilt alignment film on a fourth substrate on which a second electrode for controlling the alignment of the liquid crystal molecules and controlling the transmission of light through the liquid crystal layer is provided. As the region and the low pretilt alignment region are adjacent,
Forming a high pretilt alignment film by printing on the low pretilt alignment film of the third substrate; and forming the fourth substrate so that the high pretilt alignment region and the low pretilt alignment region are adjacent in the pixel. Forming a high pretilt alignment film by printing on the low pretilt alignment film,
A step of injecting a liquid crystal between the third and fourth substrates, wherein the high pretilt alignment film is provided in a region where the high pretilt alignment region of the third substrate faces the fourth substrate. The low pretilt alignment region of the third substrate is provided in the region where the low pretilt alignment region of the fourth substrate is present, and the high pretilt alignment region of the fourth substrate is opposed to the third substrate. The present invention is attained by a method for manufacturing a liquid crystal display device, wherein the low pretilt alignment film is formed so as to face and exist near a boundary region between the high pretilt alignment region and the low pretilt alignment region adjacent to each other.

[0018]

FIG. 10 is a graph showing the relationship between the combination of an alignment film that provides a high / medium / low pretilt angle to liquid crystal molecules sandwiching a liquid crystal layer and the applied voltage at which a reverse twist of the liquid crystal molecules occurs, investigated by the present inventors. It is a table showing the relationship. In this table, an alignment film that gives a liquid crystal molecule a pretilt angle of 7 degrees as a high pretilt angle, a pretilt angle of 3 degrees as a medium pretilt angle, and a pretilt angle of 1 degree or less as a low pretilt angle is used.

The upper row of each column has a chiral pitch of 75.
The applied voltage at which a reverse twist occurs when the pitch is set to μm, and the lower row shows the applied voltage at which the reverse twist occurs when the chiral pitch is set to 40 μm. The column marked with “-” indicates a combination of alignment films in which reverse twist does not occur. According to this table, no reverse twist occurs when the pretilt angles of the alignment films are different, but a reverse twist occurs when the pretilt angles of the alignment films are equal.

The voltage at which the reverse twist occurs is higher as the pretilt angle of the alignment film is smaller, and is lower as the pretilt angle of the alignment film is larger. Further, the voltage at which the reverse twist occurs becomes higher as the chiral pitch is smaller, and becomes lower as the chiral pitch is larger. In general, since the saturation voltage of the liquid crystal is about 5.5 V, when the alignment film has a high pretilt angle, reverse twist occurs at a voltage lower than the saturation voltage of the liquid crystal, and conversely, when the alignment film has a low pretilt angle. No reverse twist occurs unless a voltage much higher than the saturation voltage of the liquid crystal is applied.

According to the present invention, the low pretilt alignment region and the high pretilt alignment region are formed adjacent to each other on the first and second substrates sandwiching the liquid crystal layer, and the high pretilt alignment region and the low pretilt alignment region adjacent to each other are formed. Near the boundary region of
The low pretilt alignment regions in the first and second alignment films face each other. That is, it is ensured that the high pretilt alignment regions do not face each other near the boundary region.

Accordingly, the liquid crystal layer may be sandwiched between the low pretilt alignment regions, but not between the high pretilt alignment regions. Therefore, it is possible to reliably prevent the reverse twist of the liquid crystal molecules from occurring at a saturation voltage or lower. Accordingly, it is possible to avoid a decrease in display quality such as light leakage in a partial region, formation of a non-transmissive region, or a decrease in contrast.

Further, since at least the high pretilt alignment region of the first or second alignment film can be formed by printing, the manufacturing process is simplified, and unlike the patterning method by photolithography, development / exposure and Since there is no step that adversely affects the alignment film material such as etching, the characteristics of the alignment film are not impaired. Further, the first and second
Is composed of a two-layer film in which a high pretilt alignment film is selectively formed on a low pretilt alignment film, and the high pretilt alignment film is formed by printing. Thus, it is possible to avoid undesired effects such as a decrease in the pretilt angle of the lower alignment film due to the solvent of the alignment film material and the like, and a reduction in the cross-sectional shape of the patterned lower pretilt alignment film.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a 90 according to an embodiment of the present invention.
FIG. 1 is a cross-sectional view schematically showing a structure of a liquid crystal panel in a twisted nematic mode. A TFT-side substrate (first substrate) 201 on which a thin film transistor of an active matrix circuit is formed, and a CF-side substrate (second substrate) 202 on which a color filter (CF) is formed are opposed to each other with the liquid crystal layer 1 interposed therebetween. ing. Light passes through a CF-side substrate 202 from a light source (not shown) via a TFT-side substrate 201.

On the TFT-side substrate 201, a transparent pixel electrode (first electrode) 5 composed of a gate bus line 3, a gate insulating film 4, and an ITO film is formed on a transparent substrate 2 made of glass or the like. Further, a low pretilt alignment film 6 made of polyimide is formed by covering these, and a high pretilt alignment film 7 is selectively laminated on the low pretilt alignment film 6.

FIG. 2A is a plan view of the TFT-side substrate 201 as viewed from the liquid crystal layer side. The gate bus line 3 and the drain bus line 13 are orthogonal to each other, and a TFT is provided near the intersection.
Are formed. The gate bus line 3 is connected to the gate electrode of the TFT, and the drain bus line 13 is connected to the drain electrode of the TFT. A region divided by the gate bus line 3 and the drain bus line 13 corresponds to a pixel region.

In this pixel region, a pixel electrode 5 separated for each pixel region and a low pretilt alignment film 6 are formed over the entire pixel region so as to cover them. Pixel electrode 5 is TF
It is connected to the source electrode of T. Further thereon, a band-shaped high pretilt alignment film 7 is formed so as to cover a lower region of the upper and lower regions obtained by dividing the pixel region along the gate bus line 3 into approximately two parts. High pretilt alignment film 7
Is formed in a range from slightly below the center line of the pixel region to the center line along the longitudinal direction of the gate bus line 3 below.

The rubbing directions of the low pretilt alignment film 6 and the high pretilt alignment film 7 are the same, as shown in FIG.
Is indicated by arrow C on the right side of. The low pretilt alignment film 6
The pretilt angle given to the liquid crystal molecules by the high pretilt alignment film 7 is different from that of the low pretilt alignment film 6, and the pretilt angle of the high pretilt alignment film 7 is about 7 degrees.

On the other hand, on the CF side substrate 202, a color filter film 9 and a transparent electrode (second
Electrode; common electrode) 10 is laminated, and a low pretilt alignment film 11 made of polyimide is further formed thereon,
A high pretilt alignment film 12 is selectively formed on the low pretilt alignment film 11. FIG. 2B is a plan view of the CF-side substrate B as viewed from the liquid crystal side. A transparent electrode 10 is formed on a rectangular color filter film 9 separated for each pixel region. A low pretilt alignment film 11 is formed over the entire pixel region.

Further, a band-shaped high pretilt alignment film 12 is formed thereon so as to cover the upper region of the upper and lower regions obtained by substantially dividing the pixel region along the gate bus line 3 into two. The high pretilt alignment film 12 is formed in a range slightly above the center line of the pixel region to the center line along the longitudinal direction of the upper gate bus line 3. When the CF-side substrate 202 shown in FIG. 2B is overlapped with the TFT-side substrate 201 as a liquid crystal display panel, the top and bottom remain the same, but the left and right are reversed. Therefore, CF
T of the formation region of the high pretilt alignment film 12 of the side substrate 202
The area facing the FT-side substrate 201 is
And a region where the high pretilt alignment film 7 is formed, and is not overlapped. This interval is set to a dimension that does not overlap with certainty in consideration of manufacturing variations.

The rubbing direction of the low pretilt alignment film 11 and the high pretilt alignment film 12 is, as shown by the arrow D on the right side of FIG. This is a direction orthogonal to the rubbing direction of the film 6 and the high pretilt alignment film 7. As described above, as shown in FIG. 1, the high pretilt alignment films 7 and 12 of the first and second substrates are formed in a region slightly smaller than a region obtained by dividing the pixel region into two, and thus have a low level. Although there are portions where the pretilt alignment films 6 and 11 face each other, the high pretilt alignment films 7 and 12 do not face each other.

Next, FIG. 3 (a) shows an alignment state of liquid crystal molecules near a boundary of a pixel region when a voltage is applied to the liquid crystal display panel having the structure shown in FIG. The alignment state of the liquid crystal molecules S, T, U, V, and W at different positions in the substrate plane direction is shown. The inclination from the alignment film of the TFT side substrate 201 to the alignment film of the CF side substrate 202 with respect to the substrate plane direction is shown. It is shown. The liquid crystal molecules are actually twisted in the plane direction of the substrate, but the twist is not shown in the figure for easy understanding.

When a voltage is applied between the pixel electrode 5 of the TFT side substrate 201 and the transparent electrode 10 of the CF side substrate 202, the liquid crystal molecules in the liquid crystal layer 1 rise. In the liquid crystal display panel of this embodiment, the low pretilt alignment films 6 and 8 overlap, but the high pretilt alignment films 7 and 12 do not overlap. Therefore, as described with reference to the table of FIG. 10, the voltage application that causes the reverse twist of the liquid crystal molecules T and V in the portion where the low pretilt alignment film overlaps is considerably higher than the saturation voltage of the liquid crystal, and therefore, the ordinary At the operating voltage, no reverse twist of the liquid crystal molecules occurs.

Next, a method of manufacturing the liquid crystal display panel according to the present invention described above will be described. 4A to 6B are cross-sectional views schematically showing a manufacturing process of the TFT-side substrate 201 and FIG. 4B schematically showing a manufacturing process of the CF-side substrate 202. First, in the step of FIG. 4, a pixel electrode and a common electrode are formed on each substrate. In FIG. 4A, a gate bus line 3, a gate insulating film 4, and a transparent pixel electrode 5 are laminated on a transparent substrate 2 such as glass. These constitute a third substrate. In FIG. 4B, a transparent substrate 8 such as a glass substrate is used.
The color filter 9 and the transparent electrode 10 are laminated. These constitute a fourth substrate.

Next, in the step of FIG. 5, low pretilt alignment films 6 and 11 are formed. In FIG. 5A, the low pretilt alignment film 6 is printed in a solid pattern, prebaked at 80 ° C. for 3 minutes, and dried. In FIG. 5B, the low pretilt alignment film 11 is printed in a solid pattern on the entire surface on the transparent electrode 10, prebaked, and dried. Next, in the step of FIG. 6, the high pretilt alignment films 7 and 12 are selectively formed. In FIG. 6A, the stripe pattern of the high pretilt alignment film 7 is printed on the low pretilt alignment film 6 in the region from the center of the pixel electrode to the gate bus line 3, and 8
Pre-baking is performed at 0 ° C. for 3 minutes, and baking is performed at 180 ° C. for 1 hour. Similarly, in FIG. 6B, after the stripe pattern of the high pretilt alignment film 12 is printed on the low pretilt alignment film 11, prebaking and firing are performed in the same manner as described above. When the low pretilt alignment films 6 and 11 are formed on the high pretilt alignment films 7 and 12 by printing by changing the stacking order, the pretilt angle of the lower high pretilt alignment film 12 due to the solvent of the alignment film material or the like is reduced. It is not preferable because it lowers or the cross-sectional shape of the patterned low-pretilt alignment film 11 of the upper layer collapses.

Next, the printing of the stripe pattern of the high pretilt alignment films 7 and 12 will be described. As a printing plate, a photosensitive resin relief plate (manufactured by Asahi Kasei Corporation) was used in the same manner as that shown in FIG. 9.
Carve a convex stripe pattern.

The alignment film is patterned by gravure printing using the resin relief printing plate. The resin relief printing plate has a low hardness due to its material properties, and the alignment film material is a liquid having a low viscosity of 40 to 50 cp. When the resin is pressed and adhered, the trapezoidal convex portion of the resin relief plate is crushed or wrapped around the edge of the convex portion, and the width of the alignment film material is spread two to three times the width of the resin relief plate, and the stripes of the alignment film are formed. Since the edge of the pattern is wavy, the width of the printed stripe pattern varies by ± 15%.

In order to cope with such a variation in the width of the stripe pattern, in this embodiment, the width of each of the high pretilt alignment films 7 and 12 after printing is 165 at the maximum.
When the TFT-side substrate 201 and the CF-side substrate 202 are bonded together so as to have a thickness of μm, the high pretilt alignment films 7 and 12 do not face each other. In this example, the pattern width actually printed is 140 ± 20 μm.
m, the value of the plate width of the resin relief printing plate is set to 60 μm.

The TFT-side substrate 2 thus prepared
1 and the CF-side substrate 202 are rubbed in the directions shown in FIGS. 2A and 2B, respectively, and as shown in FIG. 1, after the high / high pretilt alignment films are overlapped so as not to face each other. The liquid crystal 1 is vacuum-injected. At this time, a chiral agent for determining the twist direction of the liquid crystal molecules is added to the liquid crystal 1. However, since the liquid crystal molecules of the liquid crystal panel according to the present embodiment easily cause reverse twist, the chiral pitch is 10 times the cell gap. It is preferable to set the following. Since the liquid crystal panel of this embodiment has a cell gap of 5 μm, the chiral pitch of the liquid crystal is set to 40 μm.

After the liquid crystal has been sealed as described above, the injection port is sealed, and a polarizing plate is attached to the outside of the transparent substrates 1 and 8 so that the transmission axes are parallel or vertical, thereby completing the liquid crystal display panel. I do. As described above, the high pretilt alignment films 7, 1
2 is narrower than the width of the upper and lower regions obtained by dividing the pixel region into two along the gate bus line, so that when the TFT-side substrate 201 and the CF-side substrate 202 are overlapped, a high pretilt alignment film is formed. 7 is separated from the formation region of the high pretilt alignment film 12 with an interval.

In particular, by designing the interval to be equal to or greater than the printing variation, even if the printing variation occurs, the high pretilt alignment films 7 and 12 do not face each other and do not overlap. Thereby, the occurrence of reverse twist of the liquid crystal molecules can be reliably avoided. The liquid crystal panel according to the present embodiment has low pretilt alignment films 6, 11 formed on the entire surface.
By stacking the high pretilt alignment films 7 and 12 on the substrate, the low pretilt alignment films 6 and 6 are formed on the substrates 201 and 202.
11 and high pretilt alignment films 7 and 12 are formed.
Instead of stacking the alignment films in two layers, a low pretilt alignment film and a high pretilt alignment film may be formed in different regions.

Further, although the alignment division region of the liquid crystal display panel according to the present embodiment is divided by a region parallel to the gate bus line, the shape for dividing the pixel region is not particularly limited, and for example, along the drain bus line. The pixel region may be bisected by the region, and the alignment film may be patterned according to the shape of the divided region. Further, although the pixel region is divided into two, the pixel region may be divided into two or more alignment division regions.

[0043]

As described above, according to the present invention, the low pretilt alignment region and the high pretilt alignment region are formed adjacent to each other on the first and second substrates sandwiching the liquid crystal layer, and the high pretilt alignment regions adjacent to each other are formed. Near the boundary region between the region and the low pretilt alignment region, the low pretilt alignment region in the first and second alignment films faces each other.

Therefore, even when the high pretilt alignment film is formed by printing, it is possible to reliably prevent the high pretilt alignment regions of the first and second substrates from facing each other. For this reason, it is possible to avoid reverse twist of liquid crystal molecules caused by the opposing high pretilt alignment regions, thereby improving viewing angle characteristics and improving display quality such as enhancing contrast.

Further, since the high pretilt alignment film can be formed by printing, the manufacturing process of the liquid crystal display panel is simplified, and at the same time, the characteristics of the alignment film are not impaired as in the patterning by photolithography. The reliability of the panel can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display according to an embodiment of the present invention.

2A and 2B show the configuration of each substrate sandwiching a liquid crystal layer of a liquid crystal display device according to an embodiment of the present invention, wherein FIG. 2A is a plan view of a TFT-side substrate viewed from the liquid crystal layer side, and FIG. FIG. 4 is a plan view of a side substrate as viewed from a liquid crystal layer side.

FIGS. 3A and 3B show alignment states of liquid crystal molecules in a liquid crystal display panel, FIG. 3A is a cross-sectional view showing alignment states of liquid crystal molecules in a liquid crystal display panel of the present invention, and FIG. FIG. 3 is a cross-sectional view showing an alignment state of the liquid crystal.

4A and 4B show a method of manufacturing each substrate of the liquid crystal display device according to one embodiment of the present invention, wherein FIG. 4A is a cross-sectional view showing a TFT-side substrate, and FIG. .

5A and 5B show a method of manufacturing each substrate of the liquid crystal display device according to one embodiment of the present invention, wherein FIG. 5A is a sectional view showing a TFT side substrate, and FIG. 5B is a sectional view showing a color filter side substrate. .

6A and 6B show a method of manufacturing each substrate of the liquid crystal display device according to one embodiment of the present invention, wherein FIG. 6A is a cross-sectional view showing a TFT-side substrate, and FIG. .

FIG. 7 is a cross-sectional view for explaining the principle of an alignment division type liquid crystal display panel by controlling a pretilt angle.

FIG. 8 shows a method of forming an alignment film by a photolithography technique, and (a) to (c) are cross-sectional views showing respective steps.

FIGS. 9A and 9B show a method of forming an alignment film by printing, wherein FIGS.
(B) is sectional drawing which shows each process.

FIG. 10 is a table showing a relationship between a pretilt angle of an alignment film sandwiching a liquid crystal layer and a voltage at which a reverse twist of liquid crystal molecules occurs.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal layer, 2, 8, 51, 57 transparent substrate, 3, 52 gate bus line, 4, 53 gate insulating film, 5, 54 pixel electrode (first electrode), 6, 55 low pretilt alignment film, 7, 56, 56a High pretilt alignment film, 9, 58 Color filter film, 10, 59 Transparent electrode (common electrode; second electrode), 11, 60 Low pretilt alignment film, 12, 61 High pretilt alignment film, 13 Drain bus line 63 resist film, 63a resist mask, 64 mask, 65 ultraviolet rays, 66 letterpress, 201 TFT side substrate (first substrate), 202 CF side substrate (second substrate).

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-210099 (JP, A) JP-A-6-43460 (JP, A) JP-A-6-82784 (JP, A) JP-A-6-84784 130397 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1337 505 G02F 1/1368

Claims (8)

(57) [Claims] A first substrate and a second substrate that sandwich a liquid crystal layer, and a first substrate that controls the alignment of liquid crystal molecules by applying a voltage and controls light transmission of the liquid crystal layer. The first formed in
And a second electrode formed on the second substrate, and a first alignment film formed on the first substrate and having a high pretilt alignment region and a low pretilt alignment region adjacent to each other in a pixel. A second alignment film formed on the second substrate and having a high pretilt alignment region and a low pretilt alignment region adjacent to each other in the pixel, wherein the high pretilt alignment region of the first alignment film The low pretilt alignment region of the second alignment film exists in the region facing the second substrate, and the high pretilt alignment region of the second alignment film faces the first substrate. The region includes the low pretilt alignment region of the first alignment film, and the vicinity of a boundary region between the high pretilt alignment region and the low pretilt alignment region adjacent to each other is the first pretilt alignment region.
And a low pretilt alignment region in the second alignment film faces each other. 2. The liquid crystal display device according to claim 1, wherein the rubbing directions of the first and second alignment films are orthogonal. 3. The method according to claim 1, wherein each of the first and second alignment films is a two-layer film in which a high pretilt alignment film is selectively formed on a low pretilt alignment film. 3. The liquid crystal display device according to 1. 4. The liquid crystal display device according to claim 3, wherein the high pretilt alignment film is formed by printing. 5. A first bus line and a second bus line crossing each other are formed on the first substrate, and a side end of the high pretilt alignment region of the first alignment film and the second bus line are formed on the first substrate. The side edge of the high pretilt alignment region of the second alignment film facing the first substrate has a center line extending along a longitudinal direction of the first or second bus line and a first end of the first electrode. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is provided between the liquid crystal display device and a side end. 6. A thin film transistor is formed on the first substrate for each pixel, the first bus line is a gate bus line connected to a gate electrode of the thin film transistor, and the second bus line 6. The liquid crystal display device according to claim 5, wherein is a drain bus line connected to a drain electrode of the thin film transistor, and the first electrode is a pixel electrode connected to a source electrode of the thin film transistor. 7. A pretilt angle given to liquid crystal molecules by the low pretilt alignment film is 1 degree or less, and a pretilt angle given to liquid crystal molecules by the high pretilt alignment film is 7 degrees or more. The liquid crystal display device according to claim 6. 8. A step of applying a voltage to control the alignment of liquid crystal molecules and forming a low pretilt alignment film on a third substrate on which a first electrode for controlling light transmission of the liquid crystal layer is formed. Forming a low pretilt alignment film on a fourth substrate on which a second electrode for controlling the alignment of the liquid crystal molecules by applying a voltage and controlling the light transmission of the liquid crystal layer is formed; Forming a high pre-tilt alignment film by printing on the low pre-tilt alignment film of the third substrate so that the high pre-tilt alignment region and the low pre-tilt alignment region are adjacent to each other; Forming a high pretilt alignment film by printing on the low pretilt alignment film of the fourth substrate so that the region and the low pretilt alignment region are adjacent to each other; and a liquid crystal between the third and fourth substrates. The process of injecting In addition, the high pretilt alignment film has a low pretilt alignment region of the fourth substrate in a region of the third substrate facing the high pretilt alignment region to the fourth substrate; The low pretilt alignment region of the third substrate is present in the region of the high pretilt alignment region of the substrate 4 facing the third substrate, and the adjacent high pretilt alignment region and the low pretilt alignment region Wherein the low pretilt alignment film is formed so as to face the boundary region of the liquid crystal display device.