KR0163616B1 - Liquid crystal display element and its production - Google Patents

Abstract

The liquid crystal display device of the present invention comprises a pair of substrates, a liquid crystal material sandwiched between the pair of substrates, and an optical polarizing memory film formed on one or both of the pair of substrates.

The optical polarization memory film is exposed to polarized light to become an active alignment means including a plurality of microdomains.

For microdomains, the orientation is uniform and substantially isotropic in each domain. Viewing angle dependency is removed. Since the rubbing treatment has not been performed, problems due to rubbing can be solved.

Description

LCD and its manufacturing method

1A to 1F are enlarged views showing an alignment processing state of a substrate of a liquid crystal display device according to an exemplary embodiment of the present invention.

2A and 2B are schematic cross-sectional views of a substrate of a liquid crystal display device according to an embodiment of the present invention.

3 is a perspective view of an apparatus for performing alignment processing of a substrate of a liquid crystal display device according to an embodiment of the present invention.

4 is an enlarged view showing another alignment treatment state of a substrate according to an embodiment of the present invention.

5 is a perspective view of another apparatus for performing alignment processing on a substrate of a liquid crystal display device according to an embodiment of the present invention.

6A and 6B are cross-sectional views of a liquid crystal display device according to an exemplary embodiment of the present invention.

7 is a schematic cross-sectional view when a liquid crystal material is injected into a liquid crystal display device according to an embodiment of the present invention.

8A and 8B are enlarged plan views showing examples of the alignment treatment state of the substrate according to the embodiment of the present invention.

9A to 9E are enlarged plan views showing examples of alignment states of substrates in which a cutoff portion is provided in a part of a pixel electrode, according to an embodiment of the present invention.

10 is an enlarged cross-sectional view showing an example of an inclined electric field generated by a cutoff portion provided in a part of a pixel according to an embodiment of the present invention.

11A to 11C are enlarged plan views showing examples of the alignment treatment state of the substrate according to the embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: microdomain 2, 3: substrate

4: common electrode 5: polarized light storage film

6: liquid crystal layer 7: thin film transistor drive element

8 pixel electrode 9 laser oscillator

10: optical system 11: polarizing plate

12 polarized laser light 13 transparent glass substrate

14: movable stage 15: miso domain

16: mask 17,18: polarizing plate

19: injection hole 20: liquid crystal molecules

22, 23: heating means 30: pixel region

31, 32, 33, 34: microdomain 35: vertical boundary line

36: horizontal boundary line 40: pixel area

41 to 48: Microdomain 50: Pixel area

51, 52, 53, 54: microdomains 55,58: cutoff portion

60 pixel area 61-68 micro domain

[Field of Invention]

The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly, to a liquid crystal display device and a method for manufacturing the same that can improve the viewing angle.

[Initiation of Related Technologies]

In a liquid crystal display element used in a liquid crystal display device, or a so-called liquid crystal cell, a specific alignment state of liquid crystal molecules is changed to another state by some external action such as an electric field. The change in the optical characteristic due to the change in the orientation of the liquid crystal molecules is used for display as a visual change. Usually, in order to orient the liquid crystal molecules in a specific state, an alignment treatment is performed on the surface of the glass substrate sandwiching the liquid crystal layer.

In a conventional twisted nematic (TN) type liquid crystal cell, a so-called rubbing treatment in which a pair of glass substrates sandwiching the liquid crystal layer (having electrodes, alignment layers, etc. on the surface) is rubbed as a cotton cloth. ) Was subjected to the orientation treatment.

When the rubbing treatment is performed on the substrate, the rubbing direction is performed such that the rubbing directions of the upper and lower substrates are perpendicular to each other. If the liquid crystal cell is of the negative display type, the pair of parallel polarizing plates is arranged such that the polarizing plate adjacent to one of the rubbing directions is parallel to the polarization axis. It is arranged to be parallel.

When the alignment treatment is performed by rubbing as described above, the alignment direction of the liquid crystal molecules becomes uniform on the substrate surface. Thus, when the indication is observed by the observer, the viewing angle dependency of the indication occurs, in which the indication can be easily observed only from a constantly limited observation range.

Regarding the viewing angle characteristics of the conventional liquid crystal cell, US Patent Application Nos. 08 / 115,441 filed on September 1, 1993, US Patent Application Nos. 08 / 191,554 filed on February 2, 1994 and February 4, 1994 See self-pending US patent application Ser. No. 08 / 191,636. In addition, rubbing generates static electricity, which may cause dielectric breakdown in the alignment film, resulting in misalignment of the liquid crystal molecules at the portion thereof, and as a result, inferior liquid crystal display. In a liquid crystal cell using an active driving method, static electricity generated by rubbing may cause damage to a drive element or wiring formed on a substrate.

In addition, a large amount of fine dust generated by the rubbing process may adhere to the substrate by static electricity, which may cause display defects such as gap defects, black spots, and white spots in the liquid crystal cell.

[Summary of invention]

An object of the present invention is to provide a liquid crystal display device and a method of manufacturing the same, which not only require a rubbing process that causes viewing angle dependence and causes product defects such as display defects and element breakdown, but also provides a uniform viewing angle characteristic and high quality display. It is.

The present inventors have proposed a multi-domain liquid crystal display device having a display unit including a plurality of micro domains. In each microdomain, the alignment of the liquid crystal molecules can be considered to be uniform. However, the orientation is different for each microdomain. Such a multidomain structure can be obtained by not performing an orientation treatment.

According to one feature of the invention, at least one of a pair of glass substrates, a chiral nematic liquid crystal layer or a nematic liquid crystal layer sandwiched between a pair of glass substrates, and a pair of substrates The liquid crystal display element which consists of the optical polarization memory film which has an active orientation structure which has many microdomains with a different orientation direction arrange | positioned on the board | substrate is provided.

According to another feature of the invention, there is also a liquid crystal display having a structure similar to that described above, and having an active alignment structure in which at least one of the plurality of microdomains having different orientations in each pixel region is formed on at least one of the pair of substrates in a group. An element is provided. The orientation directions of adjacent microdomains among the four microdomains have different directions of 90 ° or 180 ° to each other.

The present invention also provides a liquid crystal display device having an alignment structure on at least one substrate, having a pair of electrodes formed on the substrates, and having a cutoff portion provided on a portion of one electrode for adjusting the alignment of liquid crystal molecules. do.

At least one of the pair of substrates is provided with an active alignment structure for each of the large amounts of microdomains, where each liquid crystal molecule is oriented in a certain direction. At the same time, the orientation direction of each microdomain is selected such that the substrate has a multidomain structure having a substantially isotropic viewing angle characteristic as a whole. Since rubbing is not performed, problems due to rubbing do not occur.

[Description of Specific Embodiment of the Invention]

A liquid crystal display device and a method of manufacturing the same according to an embodiment of the present invention will be described with reference to the accompanying drawings. Prior art can be applied to the basic structure and the basic manufacturing process of the liquid crystal display device except the alignment structure. US Patent Application No. 08 / 115,441 filed on September 1, 1993, US Patent Application No. 08 / 191,554 filed on February 4, 1994, and US Patent Application No. 08 / 191,636 filed on February 4, 1994 See the disclosure of the call.

1A to 1F are enlarged plan views of an alignment state of a substrate according to an exemplary embodiment of the present invention. Arrows indicate the alignment direction of the liquid crystal molecules.

A plurality of microdomains 1, which are the minimum units constituting the pixel, are provided on the substrate surface. In each of the microdomains, the liquid crystal molecules adjacent to the substrate are substantially aligned in one direction. The alignment process is performed to uniformly orient the directions of the liquid crystal molecules in each microdomain. However, the orientation directions of the micro domains on the substrate surface are arranged such that the liquid crystal molecules are directed in all directions in the substrate surface as a whole. Thus, the surface of the substrate can be considered macroscopically isotropic or random. It is not necessary to have a large number of alignment directions in order to have substantially isotropic properties. For example, several directions can serve as a random orientation to obtain a substantially isotropic orientation. Substantially isotropic orientation is compared with the orientation in the single direction of the prior art.

The size of each microdomain 1 is designed such that the unit pixel contains a sufficiently large number of microdomains. For example, it is designed to include several to several tens of micro domains in an area of 100 x 300 µm 2, which is typical of unit pixels. In order to fill with a large number of microdomains having the same area within a large area of the pixel, each domain has a regular hexagon as shown in Fig. 1a, a rectangle as shown in Fig. 1b, a square as shown in Fig. 1c. It is preferable to form a parallelogram as shown in FIG. 1d, a rhombus as shown in FIG. 1e, a triangle as shown in FIG. 1f, and the like.

One method of manufacturing the substrate subjected to the alignment treatment as shown in FIGS. 1A to 1F is to use an optical polarization memory film.

2A and 2B are cross-sectional views showing the configuration of a liquid crystal display device according to an embodiment of the present invention. One glass substrate 3 having a thin film transistor (TFT) driving element 7 and a pixel electrode 8 and another glass substrate 2 having a common transparent electrode (common electrode) 4 are provided. The liquid crystal layer 6 is disposed to face each other while sandwiching the liquid crystal layer 6. FIG. 2A shows an example of a liquid crystal display cell having active alignment means formed by the optical polarization memory film 5 only on one glass substrate. In the figure, the memory film 5 is covered on the common electrode 4. In order to obtain a flat bottom surface, it is advantageous to use a common electrode substrate. FIG. 2B shows an example of a liquid crystal display cell having active alignment means formed by optical polarization memory films 5a and 5b on both glass substrates. The alignment structure on both substrates will make the alignment of liquid crystal molecules easier and more stable. Hereinafter, a method of forming a substrate provided with an alignment means for each microdomain using the optical polarization memory film will be described.

First, the optical polarization memory film 5 is coated on one side of one or two substrates of the pair of transparent glass substrates 2 and 3 constituting the liquid crystal cell. One side refers to the side of the substrate in contact with the liquid crystal material (layer) 6. The optical polarization memory film 5 stores the polarization direction in a film by irradiation of a polarization beam of a specific wavelength. The liquid crystal material 6 in contact with the optical polarization memory film 5 is oriented in a direction corresponding to the polarization direction stored in the film 5. It is also possible to give the liquid crystal molecules a tilt by memory.

The light polarizing memory film,

(1) Using silicone polyimide with a diazo amine dye (see Wayne M., Gibborn et al., NATURE Vo 1.351 (1991) P. 49).

(2) Using polyvinyl alcohol (PVA) to which an azo dye was added (see Jpn. J. Appl. Phys, Vo 1.32 (1993) PP. L93-L96).

(3) using photopolymerization photopolymers (see Martin Schart et al., Jpn. J. Appl. Phys, Vo 1. 31 (1992) PP. 2155-2164). It can be formed as. See these papers.

Next, a description will be given of the alignment processing technology of the light polarizing memory film.

3 is a device for obtaining an alignment treatment in the form of a small domain on a light polarizing memory film coated on a substrate. The laser light oscillated from the laser oscillator 9 is concentrated at one point by an optical system (for example, including openings and lenses of a predetermined shape). The optical system 10 converts the laser light into a laser beam spot having a predetermined size and shape. In addition, the polarizing plate 11 converts the laser beam into linear polarized laser light.

The linearly polarized laser light 12 is irradiated as a beam foot on the optical polarizing memory film coated on the surface of the transparent glass substrate 13. Beam spots correspond to each microdomain. The micro domain of the optical polarization memory film irradiated with the laser light stores the polarization direction of the laser light.

The glass substrate 13 is disposed on the movable stage 14 which is movable in two-dimensional X and Y directions. When the movable stage 14 is moved, the laser light is irradiated to various positions on the substrate. The polarization direction of the laser beam is changed by rotating the polarizing plate 11 about the optical axis. Orientation directions changed for each microdomain are stored in the optical polarization memory film by performing the above irradiation and rotational actions and irradiating laser light pulses to the memory film through the polarizing plate.

In this case, the angular rotation speed and the rotation direction of the polarizing plate 11 and the moving speed of the movable stage 14 are simultaneously controlled so that the plurality of micro domains 1 can be considered to have a substantially random orientation direction as a whole. It is desirable to. For example, after the first survey, every nth microdomain is exposed to the first survey, skipping one initial domain, surveying the second microdomain, and then exposing it to the second survey every nth. Conference survey exposes all domains to survey. Optionally, the rotation angle in the polarization direction between successive micro domains can be such that there is no simple integer ratio with respect to 360 °. The substrate may be stopped and the surface of the substrate may be irradiated with an optical system such as using a polygon mirror with a laser beam.

4 is an enlarged plan view showing an alignment structure on a substrate surface according to another embodiment of the present invention. The alignment film of this embodiment cannot be regarded as having a random orientation direction between adjacent microdomains, but the orientation direction within successive elongated microdomains 15 is gradually (or indicated) as indicated by the arrows in the figure. Continuous). In such a process, half rotation in the polarization direction occurs within a small area.

The alignment treatment as in FIG. 4 can be performed as follows. In the optical system 10 shown in FIG. 3, an elongated slit corresponding to the microdomain 15 is arranged, and the polarizer 11 is constantly rotated at a relatively low speed. The polarized laser light 12 is irradiated pulsed on the substrate to be moved in order to continuously change the irradiation position.

The system shown in FIG. 3 executes spot irradiation of laser light on each microdomain. This stepwise irradiation requires time to examine the entire surface of the substrate. In Fig. 5, an apparatus for performing the alignment processing shown in Figs. 1A to 1F or Fig. 4 faster for a considerably larger area of the optical polarization memory film is shown.

The laser light output from the laser oscillator 9, which is a laser light source, is enlarged by the optical system 10a to be a beam of a predetermined diameter. The magnified laser beam then passes through a mask 16. The mask 16 is a kind of photomask, for example, has a plurality of microdomains 1a corresponding to any one of FIGS. 1a to 1f, and as shown in FIGS. 1a to 1f. It is a polarizing plate having a random polarization direction.

The polarized laser light passing through the mask 16 is focused by another optical system 10b and is imaged on the optical polarizing memory film of the glass substrate 13. Laser light in various polarization directions is irradiated onto a plurality of micro domains simultaneously.

The alignment treatment is performed on two substrates or one substrate. When the alignment treatment is performed on the optical polarization memory films of two substrates, the polarization direction of each microdomain of one substrate should be accurately adjusted to have a twist of 90 ° with respect to the polarization direction of the other substrate. Such adjustment is unnecessary when the alignment treatment is performed only on one substrate. The latter case would be advantageous industrially.

The two substrates on which the alignment process is completed are disposed to face each other with a gap control means such as a ball or a rod. 6A shows the configuration of a liquid crystal display cell according to the embodiment. In this configuration, a pair of glass substrates 2 and 3 are arranged to face each other while sandwiching the liquid crystal layer 6 having a thickness d. The pair of polarizing plates 17 and 18 sandwiches the glass substrates 2 and 3 therebetween. The thickness d of the liquid crystal layer corresponds to the gap between two organic substrates. The chiral pitch p shown in FIG. 6B is the distance required for the liquid crystal material to be twisted 360 degrees.

The thickness d of the liquid crystal layer is preferably designed to satisfy the condition defined by the following formula (1), and more preferably designed to satisfy the condition defined by the formula (2).

For example, when a chiral nematic liquid crystal is used as the liquid crystal material, the liquid crystal has a polarization rotation angle of about 54 ° to about 270 ° under conditions satisfying equation (2). In addition, d / p = 0.25 corresponds to 90 degree polarization rotation.

7 is a schematic cross-sectional view showing a process of injecting a liquid crystal material into a liquid crystal cell.

While injecting the liquid crystal material, the liquid crystal material 6 is heated on both sides by heating means 22 and 23 such as a heater. The temperature at which the liquid crystal material is heated is set to be equal to or higher than the phase transition temperature (N-I point) between the liquid crystal material nematic phase and the isotropic phase.

In order to control the liquid crystal temperature, a temperature control technique for adjusting the amount of current in the heating means 22, 23 can be used while monitoring the temperature in the liquid crystal material by means of a temperature detector inserted therein. Temperature control can be done manually or automatically.

The heated liquid crystal material 6 is injected into the gap between the two substrates 2 and 3 from the injection hole 19 using a capillary shape. The liquid crystal molecules 20 under this condition are isotropic and are not oriented in a certain direction. Here, any other method of injecting the liquid crystal material 6, such as vacuum absorption, may be used.

After injecting the liquid crystal material, the liquid crystal material 6 is gradually cooled by reducing the calorific value of the heating means 22 and 23. The cooling rate controls the temperature in the range of 0.1-10 ° C / min, for example 0.5 ° C / min. By gradually cooling the temperature to the phase transition temperature (N-I point) at this speed, the liquid crystal material 6 changes its phase from the original isotropic phase to the nematic phase.

Here, in order to maintain the liquid crystal in the isotropic phase while injecting the liquid crystal, the temperature of the liquid crystal is maintained at or above the phase transition temperature between the nematic (N) phase and the isotropic (I) phase, that is, the NI point of the liquid crystal. desirable. After the injection, the temperature of the liquid crystal gradually decreases below the N-I point, and the liquid crystal becomes a liquid crystal phase. This process will make the liquid crystal finally obtained clearer in display as a display element compared with the case where the liquid crystal is injected into a liquid crystal phase.

Further, it is more preferable to inject the liquid crystal between the substrates while maintaining the temperature of the substrate before the liquid crystal injection above the N-I point. The temperature of the substrate is then gradually cooled below the N-I point. According to this method, the display quality of the obtained liquid crystal cell improves more.

The above-described injection method is suitable for uniformly aligning liquid crystal molecules in the orientation direction in each microdomain even when the alignment force of the optical polarizing memory film on the substrate is weak. In the case where the optical polarizing memory film has a strong alignment force to orient the liquid crystal molecules, particularly when the optical polarizing film has an alignment film on both substrates, a conventional injection method can be used without a heating process.

The pair of polarizing plates is arranged such that the polarization axes are mutually orthogonal in the case of 90 ° twisted positive display and parallel to each other in the case of 90 ° twisted negative display. As can be seen from the fact that there is no single reference direction such as the rubbing direction on the substrate surface, the polarization axis direction of the polarizing plate is not limited to any particular direction in the plane parallel to the polarizing plate, except for their mutual relationship.

In the case of d / p = 0.25, the microdomains whose orientation of liquid crystal molecules at the interface are parallel to the polarization direction of incident polarization pass through the polarization and because of their optical rotation power, twist the polarization direction by 90 ° as in the case of conventional TN cells. do. Similarly, microdomains having a direction orthogonal to the direction of incident polarization block incident light as in a conventional TN cell.

However, in a microdomain that is neither parallel to orthogonal to the polarization direction of incident polarization, the twist angle of the transmitted light is the polarization rotational power and the retardation Δn · d (where Δn is the refractive index of the liquid crystal layer is anisotropic. ) And the twist angle is wavelength dependent.

Therefore, light passing through the polarizing plate on the opposite side to these microdomains becomes color. However, since the orientation directions in these multi-domains exist with equal probability in all directions, the wavelength dependence of the emitted light almost disappears as a whole. In the case of positive display, the off state is a transparent state with no color.

Since the alignment structure is formed on one substrate, the liquid crystal molecules are uniformly directed in the alignment direction on the alignment surface. About the thickness direction of a liquid crystal layer, the orientation of liquid crystal molecules rotates along a chiral pitch. The multi-domain type liquid crystal display element is formed in this way.

The method described above can provide tens to hundreds of microdomains in a single pixel, each microdomain having a different orientation. However, even with a smaller number of microdomains in one pixel, by selecting the polarization axis direction of the polarizing plate appropriately for the cell, it is possible to obtain more symmetrical viewing angle characteristics than in the prior art.

That is, by arranging the alignment directions of the liquid crystal molecules in any of the micro-domains on the interface with the substrate and the transmission axis or absorption axis of the neighboring polarizing plates in parallel or orthogonal to each other, the viewing angle characteristics can be improved even in a smaller number of alignment directions. Can be. Essentially, improvement of the viewing angle characteristic is obtained regardless of the relationship between the transmission axis of the polarizing plate and the alignment direction of the liquid crystal molecules when there are four or more alignment directions.

For example, FIG. 8A is an enlarged plan view showing an example of an alignment state in one pixel of the substrate surface. In this embodiment, one pixel region 30 is constituted by four rectangular microdomains 31, 32, 33 and 34 having the same area as each other. The orientation direction of each microdomain | domain changes by 90 degrees clockwise, and is arranged in the direction of the four sides which comprise a pixel.

Arrows in each of the microdomains shown in FIG. 8A indicate the direction of orientation of the domains. The tip of the arrow indicates the direction of the pretilt. Each of the pair of microdomains 31 and 32, likewise adjacent to the left and right of the drawing, bordering the vertical boundary line 35, likewise, each of the pair of microdomains 33 and 34 is 90 ° different from each other. Has a direction. Also, each of the pair of microdomains 31 and 34 adjacent to the upper and lower sides of the drawing and the pair of the microdomains 32 and 33 adjacent to the horizontal boundary line 36 are 90 ° different from each other. It has an orientation direction.

By arranging the polarization axes of the polarizing plates in parallel or perpendicular to the orientation direction of the microdomains, the viewing angle characteristic becomes more uniform in almost all directions. It is needless to say that the four alignment directions in one pixel are not limited to the combination shown in Fig. 8A, and similar effects can be obtained with other combinations. The orientation of each of the adjacent microdomains may also be 90 ° or 180 ° to each other.

By setting four orientation directions for the microdomains, the following effects can be obtained. Since all the microdomains can be arranged in parallel or orthogonal relation to the polarization axes of the flat plate, the wavelength dependence of transmitted light from each microdomain can be minimized, and the problem that the liquid crystal cell becomes colored can be minimized.

In the case of a liquid crystal cell composed of two kinds of domains in which the orientation directions of adjacent domains are different by 180 °, black and white may be inverted and observed when the display is observed from an inclined angle in the normal direction of the cell. However, in the present embodiment, since four kinds of domains in which the orientation directions are different by 90 ° are used, there is no inversion of such display.

8B is an enlarged plan view showing an example of an alignment state in one pixel on the surface of a substrate according to another embodiment of the present invention. In this embodiment, one pixel region 40 is composed of a plurality of micro domains 41 to 48 arranged in the vertical and horizontal directions.

Considering the areas of the four small domains 41, 42, 43, 44 or the small domains 45, 46, 47, 48 as one unit area, the unit area is the case of FIG. 8A. It consists of four microdomains with 90 ° different orientation.

In the substrate of the embodiment shown in FIG. 8B, a plurality of similar unit regions composed of four micro domains (for example, 41, 42, 43, 44) are combined (arbitrarily plural) to form one pixel region 40. FIG. It consists.

The four micro wholesalers in the unit region are substantially symmetric about the center of the unit region. Also in this embodiment, effects similar to those in the embodiment shown in FIG. 8A are obtained. The effect is independent of any method of combining the orientation directions of the four microdomains, as in the case of FIG. 8A.

As described above, in the configuration of the micro domains having different orientation directions 90 ° from each other, the pre-tilt angle may be unnecessary, and a gradient electric field (ie, a peripheral electric field) is used between the electrodes facing each other. Thus, the alignment of the liquid crystal molecules can be controlled.

In FIG. 9A, similarly to FIG. 8A, the pixel region 50 is constituted by four rectangular microdomains 51, 52, 53, and 54, each of which is aligned by 90 degrees. Since the domains do not have a pretilt, the orientation opposite to that shown in FIG. 8A is in the same orientation as that of FIG. 8A. Therefore, there are two orientation directions. In the center of the pixel region 50 where the four micro domains contact each other, a cut-off portion 55 of the electrode formed by partially removing one of the opposing pairs of transparent electrodes is provided. . The pixel shown in Fig. 9a also shows electrodes composed of transparent electrodes.

When a voltage is applied to the electrode, a gradient electric field is generated around the cutoff portion 55 of the electrode because the electrode is cut off. FIG. 10 is an enlarged cross-sectional view corresponding to the pixel region 50 cut along the dashed line A-B in FIG. 9A.

When a voltage is applied between the upper and lower electrodes sandwiching the liquid crystal layer 6, a gradient electric field (i.e., a peripheral electric field) indicated by arrow a is generated around the cutoff portion 55 of the electrode. The generated gradient electric field controls the direction of tilt of the liquid crystal molecules. Therefore, the liquid crystal molecules may be aligned in a desired direction without pre-imposing the pretilt angle.

The shape of the cutoff portion 55 of the electrode is not limited to a rectangle, but any other shape such as a circle or a cross shown in FIGS. 9B and 9C, or any other which can adjust the tilting up direction. It may be a shape.

Next, in FIG. 9D, as in the case of FIG. 8B, one pixel region 6 is composed of a plurality of minute domains 61 to 68 arranged in the vertical and horizontal directions. Regions of the four microdomains 61, 62, 63, 64 or the microdomains 65, 66, 67, 68 are 90 ° differently oriented, similar to the case shown in FIG. 8B. A unit region consisting of four microdomains having a direction is constituted.

A plurality of (any number) similar unit regions having four micro domains (for example, 61, 62, 63, 64) constitute one pixel region 60. In each unit region, as shown in FIG. 9A, a cutoff portion 55 of the electrode is provided by partially removing one of the pair of transparent electrodes against the contact portions of all four small domains. The same effects as in the case of FIG. 8B or 9A can be obtained.

FIG. 9E shows a case where two micro domains having different orientation directions by 90 ° are formed in one pixel region 50. FIG. In this case, the slit type cutoff part 58 of the electrode is formed in the center of the two micro domains 56 and 57 in the direction crossing the boundary surface. Even in this case, the liquid crystal molecules are controlled to face the direction of the arrow because of the gradient electric field caused by the cutoff portion 55 of the electrode.

Finally, examples of other alignment structures will be described.

11A, 11B, and 11C show examples of different orientation directions with microdomains of different shapes. Arrows indicate the orientation direction. In any orientation, the same effects as in the above-described embodiment are exhibited.

In the case where the unit area composed of four micro domains is a quadrangle, a method of dividing a quadrilateral into four micro domains with two diagonal lines is shown in FIG. 11A. Each orientation of the four microdomains is arranged parallel to the sides of the unit region or in the radiation direction from the center of the unit region, as shown in the above-described embodiment. The orientation of the adjacent microdomains is 90 ° different as described above. Also, as shown in FIG. 11B, a plurality of unit regions may be disposed in one pixel.

In addition, in the microdomain shape of the above-described embodiment, that is, even in the case of a rectangular unit area divided into four smaller squares of the same area, the orientation directions of the four microdomains may be arranged radially. Figure 11c shows such a structure.

The invention is not limited to the configurations or numerical values set forth in connection with the above embodiments. It will be apparent to those skilled in the art that various substitutions, modifications, changes and improvements can be made based on the above disclosure. For example, in the above embodiment, the twist angle in the liquid crystal layer is set to 90 degrees. Similar constructions and manufacturing methods are also effective when they have different twist angles.

An alignment film having a plurality of microdomains each may be formed on two substrates. The two alignment layers may be arranged to take the structure of liquid crystal molecules such as nematic type, twisted nematic type, super twisted nematic type, etc. in conjunction with the liquid crystal material. When a multi-domain alignment film is formed on two substrates, a conventional method for manufacturing a liquid crystal display device may be used to inject liquid crystal.

Although the present invention has been described in accordance with the above embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like are possible.

Claims (21)

A pair of transparent substrates; A liquid crystal layer of liquid crystal molecules sandwiched between a pair of transparent substrates; And means for actively aligning the liquid crystal molecules, the plurality of microdomains being disposed on at least one of the pair of substrates and having a random orientation direction, the orientation direction being uniform within each microdomain, A liquid crystal display device comprising an active alignment means. The liquid crystal display device according to claim 1, wherein the electroactive alignment means is a light polarizing memory film. The liquid crystal display device according to claim 1, wherein the electroactive alignment means is formed on both sides of the pair of substrates. The liquid crystal display device according to claim 2, wherein the electroactive alignment means is formed on both of the pair of substrates. 2. The liquid crystal display device according to claim 1, wherein the orientation directions of the electric microdomains are distributed in almost all directions with equal probability. The liquid crystal display device according to claim 1, wherein the electric liquid crystal layer comprises liquid crystal molecules oriented in one direction in each microdomain or liquid crystal molecules twisted at a predetermined angle from one substrate toward the other substrate. 10. The method of claim 1, further comprising transparent electrodes disposed in the electrical pixel region of each surface of the pair of substrates, one of the electrical transparent electrodes generating a gradient electric field when a voltage is applied to the electrodes at a portion thereof. A liquid crystal display device having a cut-off portion. The liquid crystal display of claim 7, wherein the electric cutoff portion has an elongated shape extending across a boundary line of adjacent domains. The liquid crystal display device according to claim 1, wherein the principal axis of the liquid crystal molecules of the electric liquid crystal layer is twisted about 90 degrees between the pair of substrates. The liquid crystal layer of claim 1, wherein the electric liquid crystal layer is composed of a nematic or chiral nematic liquid crystal, the chiral pitch of the electric nematic or chiral nematic liquid crystal is p, and is sandwiched by a pair of transparent substrates. When the thickness of the liquid crystal layer of d is d, the value of d / p satisfies the following formula and the condition of about 0 d / p of about 0.75. The liquid crystal display device according to claim 10, wherein the electric liquid crystal layer is composed of a chiral nematic liquid crystal, and the value of electric d / p is equal to at least 0.25. Forming a plurality of microdomains having a random orientation direction on at least one of the pair of transparent substrates, wherein each domain has an active alignment means for forming a plurality of microdomains having a uniform orientation direction And a process of disposing a liquid crystal material between the pair of transparent substrates. 13. The method of claim 12, wherein the step of forming the electroactive alignment means comprises: forming an alignment film having optical polarization memory characteristics on at least one transparent substrate, and forming an electric microdomain size on the electro alignment film having optical polarization memory characteristics. A method of manufacturing a liquid crystal display device, comprising the step of moving the irradiation position of the electro-alignment film while irradiating polarized laser light of the beam spot. The method of manufacturing a liquid crystal display device according to claim 13, wherein the electric step of forming the positive alignment means further comprises a step of changing the polarization direction of the polarized laser light while moving the irradiation position of the polarized laser light. 15. The method of manufacturing a liquid crystal display device according to claim 14, wherein the step of changing the polarization direction passes the laser light through a polarizing plate having a predetermined polarization axis and rotates the polarizing plate about the optical axis of the laser light. The method of manufacturing a liquid crystal display device according to claim 15, wherein the electric laser light has an elongated slit shape. The method of claim 12, wherein the electrical process for forming the positive alignment means comprises: passing a laser beam through a polarizing plate mask in which a plurality of micro domains in which the polarization axis directions are changed are disposed, A method of manufacturing a liquid crystal display device comprising the step of irradiating transmitted light. 13. The liquid crystal display of claim 12, further comprising forming transparent electrodes on a surface of the pair of substrates, wherein one of the transparent electrodes has a cutoff portion of a predetermined shape. Method of manufacturing the device. The method of claim 12, wherein the electrical process of arranging the liquid crystal material comprises heating the electric substrates above the nematic-isotropic phase transition temperature (NI point) of the liquid crystal material and injecting the liquid crystal material between the substrates. A method of manufacturing a liquid crystal display device, characterized in that. 20. The method of manufacturing a liquid crystal display device according to claim 19, wherein the electric step of arranging the liquid crystal material further comprises a step of heating the liquid crystal material above the temperature of the N-I point. 13. The process of claim 12, wherein the electrical process of forming the active alignment means also forms the alignment means on both pairs of substrates, and the pair of electricity substrates is obtained such that a predetermined twist angle is obtained in each microdomain of the pair of substrates. Method of manufacturing a liquid crystal display device characterized in that the arrangement.