JP3723834B2 - Liquid crystal display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-domain liquid crystal display element having no diffraction phenomenon.
[0002]
[Prior art]
I don't know where the demand for liquid crystals will stop, as represented by LCD TVs and computer displays. In particular, in recent years, demand has further expanded since the narrow viewing angle characteristics such as contrast reduction and display inversion that occur when the liquid crystal screen is viewed from an oblique direction are improved by the multi-domain technology.
Examples of the multi-domain technology include an In-Plane display method and an MVA display method. The In-Plane display method is a method of realizing a wide viewing angle by arranging electrodes on one substrate in a comb shape and forming a domain that induces alignment deformation of liquid crystal in an azimuth direction parallel to the substrate. The MVA display method provides multi-domains by periodically providing protrusions on the substrate, realizing a high contrast ratio by realizing the dark state by vertical alignment, and realizing a wide viewing angle by dividing the multi-domain. It is what you do.
[0003]
[Problems to be solved by the invention]
However, in these image displays using the conventional multi-domain technology, light sources radiating in a plurality of specific directions for each domain are arranged with a pixel interval as a period, so that a diffraction phenomenon occurs. This diffraction phenomenon is perceived as a glare of the screen as a human sensation. For this reason, it is not possible to make the multi-domain too large, and therefore there is a problem that the viewing angle is narrower than that of a light emitting display such as a CRT (Cathode-Ray Tube). Examples of the diffraction phenomenon that occurs on the liquid crystal screen are shown below.
[0004]
FIG. 10 is a diagram showing a structure of a multi-domain liquid crystal display element used for measuring a diffraction phenomenon (refer to Jpn. J. Appl. Phys., 39, 532 (2000)). FIG. 10 shows a structure of the liquid crystal display element as viewed from above. The lower electrode and the upper electrode are formed in a zigzag shape, and the lower electrode is divided into two. With this structure, as can be seen from the figure, there are four orientation directions of the liquid crystal molecules, that is, the viewing angle is widened due to the multi-domain structure.
FIG. 11 is a diagram showing a diffraction phenomenon of a liquid crystal screen in which the liquid crystal elements are arranged as pixels. The pixel area is 10 μm × 10 μm, and the pixel interval is 15 μm. In addition, in order to make a diffraction phenomenon easy to see, it measured using the He-Ne laser monochromatic light source. From this figure, it can be seen that a diffraction pattern is generated due to multi-domaining.
[0005]
Thus, although the viewing angle of the liquid crystal display is greatly improved by the multi-domain technology, there is a problem that the diffraction phenomenon becomes remarkable when the viewing angle is further expanded.
[0006]
In view of the above problems, an object of the present invention is to provide a liquid crystal display element that has a wide viewing angle and does not cause a diffraction phenomenon.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first configuration of the liquid crystal display element of the present invention, a transparent electrode layer having holes at random positions is provided on one surface of the first transparent substrate, A first electrode / alignment layer substrate having an alignment treatment layer subjected to a liquid crystal alignment treatment on the other surface of one transparent substrate, and a hole at a random position on one surface of the second transparent substrate A second electrode / alignment layer substrate having a transparent electrode layer and having an alignment treatment layer subjected to a liquid crystal alignment treatment on the other surface of the second transparent substrate, and first and second electrode / alignment layer substrates The spacers for supporting the alignment treatment layer of the electrode / alignment layer substrate facing each other and forming a void, the liquid crystal material sealed in the void, and the first and second electrode / alignment layer substrates, respectively. It is characterized by comprising a polarizing plate disposed on the outside so that the polarization directions are orthogonal.
[0008]
Moreover, according to the 2nd structure of the liquid crystal display element of this invention, it has the transparent electrode layer which has a hole in a random position on one side of the 1st transparent substrate, and the other of the 1st transparent substrate The first electrode / alignment layer substrate having an alignment treatment layer subjected to liquid crystal alignment treatment on the surface, and the other electrode of the second transparent substrate having a transparent electrode layer on one surface of the second transparent substrate. The second electrode / alignment layer substrate having the alignment treatment layer subjected to the liquid crystal alignment treatment on the surface and the first and second electrode / alignment layer substrates face each other, and the alignment treatment layers of the electrode / alignment layer substrate face each other. Polarized light disposed so that the polarization directions are orthogonal to the outer sides of the spacers that form and support the gap, the liquid crystal material sealed in the gap, and the first and second electrode / alignment layer substrates. It consists of a board.
[0009]
According to the above configuration, when a voltage is applied between the transparent electrode layers of the first and second electrode / alignment layer substrates, the electric field in the portion without the hole faces in the direction perpendicular to the substrate, but the direction of the electric field in the vicinity of the hole Is inclined from the vertical direction of the substrate and dispersed at a wide angle around the central axis of the hole. Since the direction of the electric field is dispersed at a wide angle, the alignment direction of the liquid crystal molecules in the vicinity of the hole is dispersed at a wide angle around the central axis of the hole, and an extremely wide viewing angle is obtained. Since the holes are distributed randomly (randomly), the diffraction phenomenon does not occur even if a large number of liquid crystal display elements are arranged as pixels.
[0010]
In addition, if the liquid crystal material to be used is a nematic liquid crystal material, it is preferable that alignment of liquid crystal molecules due to an electric field is likely to occur.
Further, if the alignment direction of the alignment treatment layer of the first and second electrode / alignment layer substrate is perpendicular to the first and second electrode / alignment layer substrate surfaces, a homeotropic molecular arrangement type wide viewing angle is obtained. In addition, a liquid crystal display element in which no diffraction phenomenon occurs can be formed.
[0011]
Further, if the alignment direction of the alignment treatment layer of the first and second electrode / alignment layer substrate is parallel to the first and second electrode / alignment layer substrate surfaces and the same direction, the homogeneous molecular arrangement type is used. A liquid crystal display element having a wide viewing angle and no diffraction phenomenon can be formed.
[0012]
If the alignment direction of the alignment treatment layer of the first and second electrode / alignment layer substrate is parallel to the first and second electrode / alignment layer substrate surfaces and is perpendicular to each other, the twist molecule arrangement type A liquid crystal display element having a wide viewing angle and no diffraction phenomenon can be formed.
[0013]
The alignment direction of the alignment treatment layer of the first electrode / alignment layer substrate is perpendicular to the first electrode / alignment layer substrate surface, and the alignment direction of the alignment treatment layer of the second electrode / alignment layer substrate is If it is parallel to the substrate surface of the second electrode / alignment layer, a liquid crystal display element of a hybrid molecular arrangement type with a wide viewing angle and no diffraction phenomenon can be formed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a transparent electrode layer used in the liquid crystal display element of the present invention.
The figure is a view of the transparent electrode layer 1 as viewed from directly above, and shows a part of the transparent electrode layer 1. The transparent electrode layer 1 used in the liquid crystal display element of the present invention is provided on one surface of the transparent substrate 2, and is a portion where the transparent electrode material 3 and the transparent electrode material 3 provided at random (random) positions are not present, that is, , Hole 4 is provided. The transparent electrode material 3 is a known transparent electrode material such as a NESA film or an ITO film. The diameter of the hole 4 is a size that can be formed by photolithography or EB lithography, and the smaller the better. The density of the holes 4 can be appropriately increased or decreased depending on the use of the liquid crystal display element. Further, the shape of the hole is not limited to the circular shape shown in FIG. 1, but may be any shape, and holes having various shapes may be mixed.
In order to form holes at random positions, for example, an electrode manufacturing mask having a hole pattern at random positions may be used. A mask having a hole pattern at random positions generates random numbers at the time of mask manufacturing. It can be easily formed by randomly extracting hole positions using a function.
[0015]
FIG. 2 is a cross-sectional view showing the configuration of the liquid crystal display element of the present invention using the transparent electrode layer 1 shown in FIG. In the figure, a liquid crystal display element 20 of the present invention has a transparent electrode layer 1 having holes 4 at random positions on one surface of a transparent substrate 5, and an alignment obtained by performing a liquid crystal alignment treatment on the other surface. The first electrode / alignment layer transparent substrate 7 having the treatment layer 6, the transparent electrode layer 1 having holes 4 at random positions on one surface of the transparent substrate 8, and the liquid crystal alignment on the other surface The second electrode / alignment layer substrate 10 having the processed alignment treatment layer 9, the alignment treatment layer 6 of the first electrode / alignment layer substrate 7, and the alignment treatment layer 9 of the second electrode / alignment layer substrate 10. Facing each other and forming a gap between the alignment treatment layer 6 and the alignment treatment layer 9 to support it, a liquid crystal material 12 sealed in the gap, and the first electrode / alignment layer substrate 7 And polarizing plates disposed on the outer sides of the second electrode / alignment layer substrate 10 so that the polarization directions are orthogonal to each other. It consists of Metropolitan 3,14.
The hole patterns of the transparent electrode layer 1 of the first electrode / alignment layer substrate 7 and the transparent electrode layer 1 of the second electrode / alignment layer substrate 10 are different.
[0016]
FIG. 3 is a cross-sectional view showing another embodiment of the liquid crystal display element of the present invention using the transparent electrode layer 1 shown in FIG. In the figure, the liquid crystal display element 30 of the present invention has a transparent electrode layer 15 that does not have holes on one surface of the transparent substrate 5, that is, the entire surface is a transparent electrode, and a liquid crystal alignment treatment on the other surface. The first electrode / alignment layer transparent substrate 16 having the alignment treatment layer 6 subjected to the treatment, the transparent electrode layer 1 having the holes 4 at random positions on one surface of the transparent substrate 8, and the other surface The second electrode / alignment layer substrate 10 having the alignment treatment layer 9 subjected to the liquid crystal alignment treatment, the alignment treatment layer 6 of the first electrode / alignment layer substrate 16, and the second electrode / alignment layer substrate 10. A spacer 11 that faces the alignment treatment layer 9 and forms a gap between the alignment treatment layer 6 and the alignment treatment layer 9 and supports the liquid crystal material 12 that is sealed in the gap, a first electrode, The polarization direction is outside the alignment layer substrate 16 and the second electrode / alignment layer substrate 10. Intersect each composed disposed the polarizing plate 13 and 14 to.
This configuration differs from the configuration of the embodiment in FIG. 2 in that the transparent electrode layer 1 having holes 4 at random positions is formed only on one electrode / alignment layer substrate 10.
The liquid crystal element of the present invention is characterized by having the transparent electrode layer 1 having the holes 4 at random positions, and is not limited to the configuration of the embodiment shown in FIGS. Is possible.
[0017]
FIG. 4 is a diagram showing another configuration example of the liquid crystal display element of the present invention.
FIG. 4A shows the configuration of FIG. 2 between the first electrode / alignment layer transparent substrate 7 and the polarizing plate 13 and between the second electrode / alignment layer transparent substrate 10 and the polarizing plate 14. The transparent support substrates 17 and 17 are added.
FIG. 4B shows the configuration of FIG. 3 between the first electrode / alignment layer transparent substrate 16 and the polarizing plate 13 and between the second electrode / alignment layer transparent substrate 10 and the polarizing plate 14. The transparent support substrates 17 and 17 are added between them.
The liquid crystal display elements having these configurations have the same functions as those of the liquid crystal display elements shown in FIGS. 2 and 3, but having the transparent support substrate 17 increases the mechanical strength and facilitates manufacture.
[0018]
Next, the operation of the liquid crystal display element of the present invention will be described.
FIG. 5 is a schematic cross-sectional view for explaining the operation of the liquid crystal display element of the present invention. In the figure, a short vertical line 18 represents a nematic liquid crystal molecule having a positive dielectric anisotropy, and a line direction represents an alignment direction of the liquid crystal molecule 18. In addition, although illustration is abbreviate | omitted for the orientation processing layers 6 and 9, the case where the orientation direction of an orientation processing layer is a homeotropic type | mold molecular arrangement | sequence perpendicular | vertical to a substrate surface is shown. 5A shows the orientation of the liquid crystal molecules 18 in a state where no voltage is applied to the upper and lower transparent electrode layers 1 (OFF state), and FIG. 5B shows the voltage applied to the upper and lower transparent electrode layers 1. This shows the orientation of the liquid crystal molecules 18 in the turned-on state (ON state).
As shown in FIG. 5A, in the state where no voltage is applied, the liquid crystal molecules where the electrodes are located above and below and the liquid crystal molecules where the holes are present are perpendicular to the substrate surface according to the alignment direction of the alignment layer. Alignment and OFF state in which light is not transmitted.
In the state where the voltage is applied, as shown in FIG. 5B, the electric field direction of the portion where the electrodes are located above and below is perpendicular to the substrate surface, but the electric field direction near the hole is centered on the central axis direction of the hole. As distributed over a wide angular range. For this reason, since the orientation direction of the liquid crystal molecules is dispersed over a wide angle range to be multi-domained, the viewing angle is wide and the holes are randomly distributed (random). In an image display device in which a large number of are arranged, a diffraction phenomenon does not occur.
[0019]
In the above example, the orientation treatment of the orientation treatment layers 6 and 9 has been described in the case of a homeotropic molecular arrangement in which the orientation direction is perpendicular to the substrate surface. Of course, the orientation treatment of the orientation treatment layers 6 and 9 is performed on the substrate surface. If parallel and in the same direction, a homogeneous molecular arrangement type liquid crystal display element having a wide viewing angle and no diffraction phenomenon can be formed.
If the alignment treatment layers 6 and 9 are aligned parallel to the substrate surface and perpendicular to each other, a twist molecular arrangement type liquid crystal display element having a wide viewing angle and no diffraction phenomenon can be formed.
Further, if the alignment direction of the alignment treatment layer 6 is perpendicular to the substrate surface and the alignment direction of the alignment treatment layer 9 is parallel to the substrate surface, a hybrid molecular arrangement type liquid crystal with a wide viewing angle and no diffraction phenomenon is generated. A display element can be formed.
[0020]
Next, an example is shown.
In this example, the electrode layer shown in FIG. 1 having a hole diameter of 8 μm and a hole density of 2.8 × 10 ⁵ cm ⁻² was used. The liquid crystal used has a positive dielectric anisotropy GR-63 (dielectric anisotropy Δε = 13.7, refractive index anisotropy Δn = 0.1574) and a negative dielectric anisotropy. MLC-2038 (dielectric anisotropy Δ∈ = −5.0, refractive index anisotropy Δn = 0.1022) was used. The orientation was perpendicular to the substrate, and ODSE was used for the orientation treatment. The voltage-transmittance measurement was performed by applying a 1 kHz square wave and using a polarizing microscope and a photomultiplier.
FIG. 6 is a polarization micrograph of the produced liquid crystal display element, FIG. 6 (a) is a GR-63, FIG. 6 (b) is a polarization micrograph of MLC-2038, and the applied voltage is 10 volt.
In FIG. 6A, the dark background color portion corresponds to the portion having the electrode layers above and below, and has a uniform dark background color, which indicates that the liquid crystal molecules are uniformly aligned. Since the circular portion corresponds to the hole position, exhibits a color different from the background color, and has a cross pattern, it is considered that the orientation of the liquid crystal molecules has a hemispherical radial arrangement.
In FIG. 6B, since the interference color of the hole portion changes variously, it can be seen that the alignment of the liquid crystal molecules is disturbed. This is because in the case of the MLC-2038 liquid crystal having a negative dielectric anisotropy, the orientation change of the liquid crystal molecules is large according to the negative dielectric anisotropy.
[0021]
7A and 7B are diagrams showing applied voltage-transmittance characteristics of the liquid crystal display element of this example. FIG. 7A shows the applied voltage-transmittance characteristics of GR-63, and FIG. 7B shows the applied voltage-transmittance characteristics of MLC-2038. FIG.
As shown in FIG. 7A, GR-63 exhibited a characteristic without a threshold value, and the contrast ratio was 13: 1. As shown in FIG. 7B, MLC-2038 had a threshold value of 2v and the contrast ratio was 56: 1.
From these figures, it can be seen that the liquid crystal display element of the present invention having holes has no problem in applied voltage-transmittance characteristics and contrast characteristics.
[0022]
8A and 8B are diagrams showing response time characteristics of the liquid crystal display element of the present invention. FIG. 8A shows the response time characteristics of GR-63, and FIG. 8B shows the response time characteristics of MLC-2038.
The horizontal axis represents the applied voltage. At each applied voltage, the time from application of the voltage to 90% of the maximum transmittance is τ _on (◯), and the time from the voltage is turned off to 10% of the maximum transmittance. Is represented as τ _off (●).
From these figures, it can be seen that the liquid crystal display element of the present invention having holes has no problem in response time characteristics.
[0023]
FIG. 9 is a diagram showing viewing angle characteristics of the liquid crystal display element of this example. The horizontal axis represents the tilt angle from the direction perpendicular to the liquid crystal display element surface, that is, the viewing angle, and the vertical axis represents the liquid crystal transmittance in each viewing angle direction. In the figure, ◯, Δ, □, ●, ▲, and ■ represent differences in applied voltage, and 100%, 80%, 60%, 40%, 20%, and 0% of the applied voltage giving the maximum transmittance, respectively. Represents.
As is apparent from the figure, the liquid crystal display element of this example has a sufficient transmittance over about ± 50 °, and it can be seen that the viewing angle is extremely wide.
[0024]
【The invention's effect】
As understood from the above description, according to the present invention, since the transparent electrode layer has randomly distributed holes, the alignment direction of the liquid crystal molecules in the vicinity of the holes is dispersed at a wide angle, and an extremely wide viewing angle is obtained. can get. Since the holes are distributed randomly (randomly), the diffraction phenomenon does not occur even if a large number of liquid crystal display elements are arranged as pixels. According to the present invention, a liquid crystal display element having a wide viewing angle and no diffraction phenomenon can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a transparent electrode layer used in a liquid crystal display element of the present invention.
2 is a cross-sectional view showing a configuration of a liquid crystal display element of the present invention using the transparent electrode layer shown in FIG.
FIG. 3 is a cross-sectional view showing another embodiment of the liquid crystal display element of the present invention using the transparent electrode layer shown in FIG.
FIG. 4 is a diagram showing another configuration example of the liquid crystal display element of the present invention.
FIG. 5 is a schematic cross-sectional view for explaining the operation of the liquid crystal display element of the present invention.
FIGS. 6A and 6B are polarization micrographs of the manufactured liquid crystal display element, where FIG. 6A is a GR-63 and FIG. 6B is a polarization micrograph of MLC-2038, and the applied voltage is 10 volt.
7A and 7B are diagrams illustrating applied voltage-transmittance characteristics of the liquid crystal display element of this example, where FIG. 7A is a diagram illustrating the applied voltage-transmittance characteristics of GR-63, and FIG. 7B is a diagram illustrating the applied voltage-transmittance characteristics of MLC-2038. is there.
8A and 8B are diagrams showing response time characteristics of the liquid crystal display element of the present invention, in which FIG. 8A shows the response time characteristics of GR-63, and FIG. 8B shows the response time characteristics of MLC-2038.
FIG. 9 is a diagram showing viewing angle characteristics of the liquid crystal display element of the present example.
FIG. 10 is a diagram showing a structure of a multi-domain liquid crystal display element used for measurement of a diffraction phenomenon.
11 is a diagram showing a diffraction phenomenon of a liquid crystal screen in which the liquid crystal elements of FIG. 10 are arranged as pixels.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transparent electrode layer 2 Transparent substrate 3 Electrode material 4 Hole 5 Transparent substrate 6 Liquid crystal alignment layer 7 First electrode / alignment layer substrate 8 Transparent substrate 9 Liquid crystal alignment layer 10 Second electrode / alignment layer substrate 11 Spacer 12 Liquid crystal material 13 Deflector 14 Deflector 15 Transparent electrode layer 16 First electrode / alignment layer substrate 17 Transparent support substrate 18 Liquid crystal molecules

Claims (7)

A first electrode having a transparent electrode layer having holes at random positions on one surface of the first transparent substrate, and having an alignment treatment layer subjected to liquid crystal alignment treatment on the other surface of the first transparent substrate. 1 electrode / alignment layer substrate;
The second transparent substrate has a transparent electrode layer having holes at random positions on one surface, and the other surface of the second transparent substrate has an alignment treatment layer subjected to a liquid crystal alignment treatment. 2 electrode / alignment layer substrates;
A spacer for supporting the first and second electrode / alignment layer substrates by facing the alignment treatment layer of the electrode / alignment layer substrate and forming a void;
A liquid crystal material sealed in the gap;
A liquid crystal display element comprising: a polarizing plate disposed on the outside of each of the first and second electrode / alignment layer substrates so that the polarization directions are orthogonal to each other. A first electrode having a transparent electrode layer having holes at random positions on one surface of the first transparent substrate and an alignment treatment layer subjected to liquid crystal alignment treatment on the other surface of the first transparent substrate. Electrode / alignment layer substrate,
A second electrode / alignment layer substrate having a transparent electrode layer on one surface of the second transparent substrate and an alignment treatment layer subjected to liquid crystal alignment treatment on the other surface;
A spacer for supporting the first and second electrode / alignment layer substrates by facing the alignment treatment layer of the electrode / alignment layer substrate and forming a void;
A liquid crystal material sealed in the gap;
A liquid crystal display element comprising: a polarizing plate disposed on the outside of each of the first and second electrode / alignment layer substrates so that the polarization directions are orthogonal to each other. The liquid crystal display element according to claim 1, wherein the liquid crystal material is a nematic liquid crystal material. The alignment direction of the alignment treatment layer of the first and second electrode / alignment layer substrates is perpendicular to the surfaces of the first and second electrode / alignment layer substrates, according to claim 1 or 2. The liquid crystal display element as described. The alignment direction of the alignment treatment layers of the first and second electrode / alignment layer substrates is parallel to and in the same direction as the first and second electrode / alignment layer substrate surfaces. Item 3. The liquid crystal display element according to item 1 or 2. The alignment directions of the alignment treatment layers of the first and second electrode / alignment layer substrates are parallel to the first and second electrode / alignment layer substrate surfaces and perpendicular to each other. The liquid crystal display element according to claim 2. The alignment direction of the alignment treatment layer of the first electrode / alignment layer substrate is perpendicular to the surface of the first electrode / alignment layer substrate, and the alignment direction of the alignment treatment layer of the second electrode / alignment layer substrate is The liquid crystal display element according to claim 2, wherein the liquid crystal display element is parallel to the surface of the second electrode / alignment layer substrate.

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