JP2004341025A - Liquid crystal display device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a liquid crystal display element which easily provides excellent visual angle characteristics and has improved display performance. <P>SOLUTION: Transparent electrodes 2a, 2b are respectively disposed on mutually opposing surfaces of a pair of upper and lower substrates 1a, 1b and slit parts 3a, 3b to be non-electrode parts are formed on mutually opposing parts of the electrodes 2a, 2b. Furthermore, alignment treated alignment layers 4a, 4b are disposed on the electrodes and a liquid crystal layer 5 is interposed in between. A pretilt angle of liquid crystal molecules on the alignment layers 4a, 4b is set to be nearly 0° and further a construction with two domain type liquid crystal arrangement is set up. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device having improved viewing angle characteristics.
[0002]
[Prior art]
Recently, in order to improve the viewing angle characteristics of a TN-LCD, a method using an oblique electric field by a slit of an electrode has been proposed (for example, see Patent Document 1).
[0003]
According to this method, the TN two-domain orientation can be obtained without adding a special step only by processing the transparent electrode, and the viewing angle characteristics are greatly improved.
[0004]
However, in this method, if the liquid crystal cell has a pretilt angle, the oblique electric field generated by the slit does not work, and the liquid crystal molecules rise uniformly from the pretilt angle direction. Has the same viewing angle dependence as.
[0005]
Further, as disclosed in the above-mentioned Patent Document 1, there is a method in which the rubbing direction of one substrate is set to a direction opposite to that of a normal TN-LCD and the tilt angle of liquid crystal molecules at the center of the cell is set to 0 degree. Although effective, even in this method, the center liquid crystal molecule may not have 0 ° due to a slight difference in the rubbing conditions between the two substrates, and may have a tilt angle. As a result, the liquid crystal molecules rise uniformly from the pretilt angle direction without the oblique electric field generated by the slit, and the liquid crystal molecules are not two-domain aligned but have the same viewing angle dependence as that of a normal TN-LCD. This is unlikely to occur on the entire surface of the cell. However, if the cell has viewing angle characteristics in some areas, the cell becomes difficult to see.
[0006]
Another proposal has been made to obtain good display characteristics even when the pretilt angle is small (for example, see Patent Document 2).
[0007]
[Patent Document 1]
JP-A-6-194656 [Patent Document 2]
JP-A-9-297308
[Problems to be solved by the invention]
The conventional liquid crystal display element has a viewing angle dependency similar to that of a normal TN-LCD even when an oblique electric field is applied by the electrode slit as described above, so that good viewing angle characteristics cannot be obtained. There was a point.
[0009]
The present invention has been made in view of the above-described problems, and has as its object to provide a liquid crystal display element which can easily obtain good viewing angle characteristics and has improved display performance, and a method for manufacturing the same.
[0010]
[Means for Solving the Problems]
A liquid crystal display element according to the present invention includes a pair of substrates provided with electrodes on opposing surfaces, an alignment film provided on the electrodes and subjected to an alignment treatment, and a liquid crystal layer sandwiched between the pair of substrates. A pretilt angle of liquid crystal molecules in the alignment film is set to approximately 0 °, and a two-domain liquid crystal arrangement is formed.
[0011]
Further, the electrodes of the pair of substrates are provided with slit-shaped electrodeless portions alternately at opposing portions, and further, the liquid crystal molecules of the liquid crystal layer have an alignment direction on the surface of the alignment film by the alignment treatment. And an angle of about 90 ° with respect to the direction of the alignment treatment.
[0012]
Further, the alignment treatment is rubbing, and the direction in which the alignment treatment is performed is a direction in which rubbing is performed, or the orientation treatment is irradiation of polarized light, and the direction in which the alignment treatment is performed is a polarization axis direction of the irradiated polarized light. It is made to be.
[0013]
The method for manufacturing a liquid crystal display element according to the present invention includes a pair of substrates provided with electrodes on opposing surfaces, an alignment film provided on the electrodes and subjected to an alignment treatment, and a liquid crystal layer sandwiched between the pair of substrates. Wherein the pretilt angle of liquid crystal molecules in the alignment film is set to approximately 0 ° and a two-domain type liquid crystal arrangement is formed.
[0014]
In addition, the electrodes of the pair of substrates are provided with slit-shaped electrodeless portions alternately at opposing portions, and further, the liquid crystal molecules of the liquid crystal layer are subjected to the alignment treatment on the surface of the alignment film. The orientation direction makes an angle of about 90 ° with the direction of the orientation treatment.
[0015]
Further, the alignment treatment is rubbing, and the direction in which the alignment treatment is performed is the direction in which the rubbing is performed, or the orientation treatment is irradiation of polarized light, and the direction in which the alignment treatment is performed is irradiated with polarized light. The direction is the direction of the polarization axis.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
According to the present invention, an orientation with a pretilt angle of 0 ° can be realized to obtain a two-domain orientation, and a TN-LCD excellent in viewing angle characteristics can be obtained. Specifically, for example, an alignment film that performs parallel alignment in a direction perpendicular to the rubbing direction is used. Further, according to another aspect, an alignment film for aligning liquid crystal molecules in parallel to a direction perpendicular to the polarization direction with respect to the irradiation of linearly polarized ultraviolet light is used.
[0018]
1A and 1B are views showing the structure of a liquid crystal display device according to the present invention, wherein FIG. 1A is a top view, and FIG. 1B is a side view (sectional view taken along the line II ′).
[0019]
In the figure, reference numeral 1a denotes an upper substrate, 1b denotes a lower substrate arranged opposite to the upper substrate 1a, 2a and 2b denote transparent electrodes formed inside the substrates 1a and 1b, and a slit is formed on the opposing surface. Slit portions 3a and 3b, which are non-electrode portions, are provided. 4a and 4b are alignment films, and 5 is a liquid crystal layer.
[0020]
The above-mentioned liquid crystal display element comprises a pair of substrates 1a, 1b provided with electrodes 2a, 2b on surfaces facing each other, alignment films 4a, 4b provided on the electrodes and subjected to alignment processing, and a pair of substrates 1a, 1b. 1b, the liquid crystal layer 5 is interposed between the alignment films 4a and 4b, the pretilt angle of the liquid crystal molecules in the alignment films 4a and 4b is set to approximately 0 °, and a two-domain liquid crystal arrangement is formed.
[0021]
Hereinafter, the present invention will be described in more detail by reference examples and examples based on the above structure.
[0022]
(Reference Example 1)
A case in which a two-domain TN-LCD is manufactured in a normal rubbing direction using an alignment film having a low pretilt angle will be described.
[0023]
1) A low pretilt angle alignment film (SE-150, manufactured by Nissan Chemical Industries, Ltd.) is applied to a glass substrate having a predetermined slit electrode pattern (see FIG. 1; when a slit is formed in the display pattern of “1”) with a thickness of 500 °. And firing.
[0024]
2) The substrate on which the above-mentioned alignment film is formed is rubbed in the direction shown in FIG. 2 (both upper and lower substrates). 2A shows the rubbing direction (45 °) of the upper substrate, and 21b in FIG. 2B shows the rubbing direction (45 °) of the lower substrate. The longitudinal direction of the slit is the horizontal direction of the substrate.
[0025]
3) The two substrates are overlapped with each other via a gap control material (Silica beads 6.0 μm, manufactured by Catalysis Kasei Kogyo Co., Ltd.) so that the rubbing direction has the relationship shown in FIG. 3, and the main seal material is cured.
[0026]
4) After cutting the glass to a predetermined size, liquid crystal (Merck, Δn = 0.15, left twist) is injected into the cell by a vacuum injection method, and the injection port is sealed.
[0027]
Thus, a two-domain TN-LCD is manufactured. When a voltage was applied to this liquid crystal display element, the liquid crystal molecules rise from the tilt direction defined by the rubbing direction without the oblique electric field generated by the slit, and have a viewing angle characteristic. FIG. 4 shows a state in which the twist is released.
[0028]
(Reference Example 2)
A case in which a two-domain TN-LCD is manufactured by using a low pretilt angle alignment film and reversing the rubbing direction of one substrate on a normal side will be described.
[0029]
1) A low pretilt angle alignment film (SE-150, manufactured by Nissan Chemical Industries, Ltd.) is applied to a glass substrate having a predetermined slit electrode pattern (see FIG. 1; when a slit is formed in the display pattern of “1”) with a thickness of 500 °. And firing.
[0030]
2) The substrate on which the above-mentioned alignment film is formed is rubbed in the direction shown in FIG. 5 (both upper and lower substrates). 5A shows the rubbing direction (45 °) of the upper substrate, and 22b of FIG. 5B shows the rubbing direction (45 °) of the lower substrate. In FIG. 5, it can be seen that the upper rubbing direction is opposite to that in FIG. The longitudinal direction of the slit is the horizontal direction of the substrate.
[0031]
3) The two substrates are overlapped with each other via a gap control material (silica beads, 6.0 μm, manufactured by Catalysis Chemical Industry Co., Ltd.) so that the rubbing directions have the relationship shown in FIG. 5, and the main seal material is cured.
[0032]
4) After cutting the glass to a predetermined size, liquid crystal (Merck, Δn = 0.15, left twist) is injected into the cell by a vacuum injection method, and the injection port is sealed.
[0033]
Thus, a two-domain TN-LCD is manufactured. When a voltage was applied to this liquid crystal display element, two domains were aligned due to the oblique electric field generated by the slit in a certain region, and the viewing angle characteristics were improved. However, in other regions, the oblique electric field generated by the slit did not work, and depending on the rubbing direction. The liquid crystal molecules rise from the prescribed tilt direction, and have viewing angle characteristics. The region in which the viewing angle characteristics were improved was about 1/3 of the whole, making it difficult to see the whole cell. FIG. 7 shows a state in which the twist is released.
[0034]
[Example 1]
A case in which a two-domain TN-LCD is manufactured using an alignment film that aligns liquid crystal molecules in a direction perpendicular to the rubbing direction will be described. In such an alignment film, the pretilt angle is 0 °.
[0035]
1) An alignment film (JALS-428 manufactured by JSR) for aligning liquid crystal molecules at right angles to the rubbing direction is formed on a glass substrate having a predetermined slit electrode pattern (see FIG. 1; when a slit is formed in the display pattern “1”). Coating and baking with a thickness of 500 °.
[0036]
2) Rubbing the substrate on which the above-mentioned alignment film is formed in the direction shown in FIG. 8 (both upper and lower substrates). In FIG. 8A, 11a indicates the rubbing direction (45 °) of the upper substrate, 12a indicates the alignment direction of the liquid crystal, 11b of FIG. 8B indicates the rubbing direction of the lower substrate (45 °), and 12b indicates the alignment of the liquid crystal. Indicates the direction. The longitudinal direction of the slit is the horizontal direction of the substrate.
[0037]
3) The two substrates are overlapped with each other via a gap control material (silica beads 6.0 μm, manufactured by Catalyst Chemical Industry Co., Ltd.) so that the rubbing direction has the relationship shown in FIG. 9, and the main seal material is cured.
[0038]
4) After cutting the glass to a predetermined size, liquid crystal (Merck, Δn = 0.15, left twist) is injected into the cell by a vacuum injection method, and the injection port is sealed.
[0039]
Thus, a two-domain TN-LCD is manufactured. When a voltage was applied to this liquid crystal display element, two domains were aligned due to the oblique electric field generated by the slits over the entire cell, and the viewing angle characteristics were improved. FIG. 10 shows a state in which the twist is released.
[0040]
[Example 2]
A case where a two-domain TN-LCD is manufactured using polyvinyl cinnamate as an alignment film will be described. Polyvinyl cinnamate can align liquid crystal molecules at right angles to the rubbing direction, and the pretilt angle at that time is 0 °.
[0041]
1) Polyvinyl cinnamate having a thickness of 300 mm is applied to a glass substrate having a predetermined slit electrode pattern (see FIG. 1; a case where slits are formed in a display pattern of "1") and fired.
[0042]
2) Rubbing the substrate on which the above-mentioned alignment film is formed in the direction shown in FIG. 8 (both upper and lower substrates). The longitudinal direction of the slit is the horizontal direction of the substrate.
[0043]
3) The two substrates are overlapped with each other via a gap control material (silica beads 6.0 μm, manufactured by Catalyst Chemical Industry Co., Ltd.) so that the rubbing direction has the relationship shown in FIG. 9, and the main seal material is cured.
[0044]
4) After cutting the glass to a predetermined size, liquid crystal (Merck, Δn = 0.15, left twist) is injected into the cell by a vacuum injection method, and the injection port is sealed.
[0045]
Thus, a two-domain TN-LCD is manufactured. When a voltage was applied to this liquid crystal display element, two domains were aligned due to the oblique electric field generated by the slits over the entire cell, and the viewing angle characteristics were improved. The state in which the twist is released is as shown in FIG.
[0046]
[Example 3]
A case will be described in which a two-domain TN-LCD is manufactured using an alignment film that aligns liquid crystal molecules at right angles to the polarization direction of the irradiation polarized light during the irradiation of polarized light. When a general polyimide liquid crystal alignment film is irradiated with linearly polarized light, liquid crystal molecules are aligned at right angles to the polarization direction, and the pretilt angle becomes 0 °.
[0047]
1) An alignment film (SE-150 manufactured by Nissan Chemical Industries, Ltd.) for aligning liquid crystal molecules at right angles to the polarization direction on a glass substrate having a predetermined slit electrode pattern (see FIG. 1; when slits are formed in the display pattern “1”). ) Is applied and fired at a thickness of 500 °.
[0048]
2) The substrate on which the alignment film is formed is irradiated with polarized ultraviolet light. Irradiation is performed from the normal direction of the substrate so that the polarization direction on the substrate is as shown in FIG. The irradiation energy was 1 J / cm ² . In FIG. 11 (a), 13a indicates the polarization direction (45 °) of the irradiation polarized light on the upper substrate, 14a indicates the orientation direction of the liquid crystal, and 13b in (b) indicates the polarization direction (45 °) of the irradiation polarized light on the lower substrate. , 14b indicate the orientation direction of the liquid crystal. The longitudinal direction of the slit is the horizontal direction of the substrate.
[0049]
3) The two substrates are overlapped with each other via a gap control material (Silica beads 6.0 μm, manufactured by Kasei Kagaku Kogyo Co., Ltd.) so that the irradiation directions have the relationship shown in FIG. 12, and the main seal material is cured.
[0050]
4) After cutting the glass to a predetermined size, liquid crystal (Merck, Δn = 0.15, left twist) is injected into the cell by a vacuum injection method, and the injection port is sealed.
[0051]
Thus, a two-domain TN-LCD is manufactured. When a voltage was applied to this liquid crystal display element, two domains were aligned due to the oblique electric field generated by the slits over the entire cell, and the viewing angle characteristics were improved. The state in which the twist is released is as shown in FIG.
[0052]
[Example 4]
A case in which a two-domain TN-LCD is manufactured by irradiating polarized light using polyvinyl cinnamate as an alignment film will be described. When polarized light is applied, polyvinyl cinnamate can align liquid crystal molecules at right angles to the polarization direction, and the pretilt angle at that time is 0 °.
[0053]
1) Polyvinyl cinnamate having a thickness of 300 mm is applied to a glass substrate having a predetermined slit electrode pattern (see FIG. 1; a case where slits are formed in a display pattern of "1") and fired.
[0054]
2) The substrate on which the alignment film is formed is irradiated with polarized ultraviolet light. Irradiation is performed from the normal direction of the substrate so that the polarization direction on the substrate is as shown in FIG. The irradiation energy was 0.5 J / cm ² . The longitudinal direction of the slit is the left-right direction of the substrate.
[0055]
3) The two substrates are overlapped with each other via a gap control material (Silica beads 6.0 μm, manufactured by Kasei Kagaku Kogyo Co., Ltd.) so that the irradiation directions have the relationship shown in FIG. 12, and the main seal material is cured.
[0056]
4) After cutting the glass to a predetermined size, liquid crystal (Merck, Δn = 0.15, left twist) is injected into the cell by a vacuum injection method, and the injection port is sealed.
[0057]
Thus, a two-domain TN-LCD is manufactured. When a voltage was applied to this liquid crystal display element, two domains were aligned due to the oblique electric field generated by the slits over the entire cell, and the viewing angle characteristics were improved. The state in which the twist is released is as shown in FIG.
[0058]
As described in Examples 1 to 4, two domains are formed using an alignment film that horizontally aligns liquid crystal molecules at right angles to the rubbing direction or an alignment film that horizontally aligns liquid crystal molecules at right angles to the polarization direction. By producing a TN-LCD, a stable two-domain orientation can be obtained. For this reason, the viewing angle characteristics are remarkably improved, and the display performance is improved.
[0059]
The method of manufacturing a liquid crystal display element described in the above embodiment can be applied not only to a segment type liquid crystal display element but also to a dot matrix type liquid crystal display element and a TFT driven liquid crystal display element.
[0060]
【The invention's effect】
As described above, according to the present invention, good viewing angle characteristics can be easily obtained, and there is an effect that display performance is improved.
[Brief description of the drawings]
FIG. 1 is a view showing the structure of a liquid crystal display element according to the present invention. FIG. 2 is an explanatory view showing rubbing directions of upper and lower substrates in Reference Example 1. FIG. 3 is a view showing rubbing directions of two substrates in Reference Example 1. FIG. 4 is a cross-sectional view showing a state in which the twist of Reference Example 1 is unwound. FIG. 5 is an explanatory view showing rubbing directions of upper and lower substrates of Reference Example 2. FIG. 6 is two substrates of Reference Example 2. FIG. 7 is a cross-sectional view showing the untwisted state of Reference Example 2; FIG. 8 is an explanatory view showing the rubbing directions of the upper and lower substrates of Examples 1 and 2; Explanatory drawing showing rubbing directions of two substrates 1 and 2. FIG. 10 is a cross-sectional view showing a state in which the twist of Examples 1 and 2 is unwound. FIG. 11 is a rubbing direction of upper and lower substrates of Examples 3 and 4. FIG. 12 is an explanatory diagram showing the rubbing directions of the two substrates of Examples 3 and 4.
1a Upper substrate 1b Lower substrate 2a Transparent electrode 2b Transparent electrode 3a Slit 3b Slit 4a Alignment film 4b Alignment film 5 Liquid crystal layer

Claims (13)

A pair of substrates provided with electrodes on opposing surfaces, an alignment film provided on the electrodes and subjected to an alignment treatment, and a liquid crystal layer sandwiched between the pair of substrates, and a pretilt of liquid crystal molecules in the alignment film A liquid crystal display element having an angle of about 0 ° and a two-domain liquid crystal arrangement. 2. The liquid crystal display device according to claim 1, wherein the electrodes of the pair of substrates are provided with slit-shaped non-electrode portions alternately at opposing portions. 3. The liquid crystal display according to claim 1, wherein the liquid crystal molecules of the liquid crystal layer have an alignment direction on the surface of the alignment film formed by the alignment processing at an angle of approximately 90 degrees with respect to the alignment processing direction. element. 4. The liquid crystal display device according to claim 3, wherein the alignment processing is rubbing, and the direction in which the alignment processing is performed is a direction in which rubbing is performed. 4. The liquid crystal display device according to claim 3, wherein the alignment treatment is irradiation of polarized light, and a direction in which the alignment treatment is performed is a polarization axis direction of the irradiated polarized light. 6. The liquid crystal display device according to claim 4, wherein the alignment film is polyvinyl cinnamate. 6. The liquid crystal display device according to claim 4, wherein the alignment film is made of polyimide. 8. The liquid crystal display device according to claim 1, wherein an operation mode is a TN mode. A method for manufacturing a liquid crystal display element having a pair of substrates provided with electrodes on opposing surfaces, an alignment film provided on the electrodes and subjected to an alignment treatment, and a liquid crystal layer sandwiched between the pair of substrates. A method for manufacturing a liquid crystal display element, wherein a pretilt angle of liquid crystal molecules in the alignment film is set to approximately 0 ° and a two-domain liquid crystal arrangement is formed. 10. The method for manufacturing a liquid crystal display device according to claim 9, wherein slit-like electrodeless portions are alternately provided in portions facing the electrodes of the pair of substrates. 11. The liquid crystal molecules of the liquid crystal layer, wherein an alignment direction on a surface of an alignment film is formed at an angle of approximately 90 ° with respect to a direction of the alignment process by the alignment process. A method for manufacturing a liquid crystal display element. The method for manufacturing a liquid crystal display element according to claim 11, wherein the alignment treatment is rubbing, and the direction in which the alignment treatment is performed is the direction in which rubbing is performed. 12. The method for manufacturing a liquid crystal display device according to claim 11, wherein the alignment treatment is irradiation with polarized light, and the direction in which the alignment treatment is performed is the direction of the polarization axis of the polarized light to be irradiated.

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