KR19980041931A - LCD and its manufacturing method - Google Patents

Abstract

The liquid crystal display device of the present invention includes a display medium including at least liquid crystal between a pair of substrates. At least one substrate of the pair of substrates includes a film having recesses on the display medium side, and the recesses have a bottom near the center when viewed in the normal direction of the substrate. Liquid crystal molecules contained in the display medium are axially symmetrically aligned with the vicinity of the bottom portion as an axis.

Description

LCD and its manufacturing method

1A to 1D are schematic diagrams showing different embodiments of recesses provided on a substrate of a liquid crystal display device according to the present invention.

Fig. 2A is a schematic view showing a substrate in a process for producing a preferred embodiment of a liquid crystal display device according to the present invention.

FIG. 2B is a cross-sectional view of the substrate along the line B-B in FIG. 2A.

3A is a schematic plan view of a mold used in a process for producing a preferred embodiment of a liquid crystal display device according to the present invention.

3B is a cross-sectional view of the mold along line B-B in FIG. 3A.

4A is a schematic plan view showing an inverted concave portion formed on a substrate by the molds of FIGS. 3A and 3B.

4B is a cross-sectional view of the main portion taken along the line B-B in FIG. 4A.

5 is a schematic view showing an observation result by a polarizing microscope of a liquid crystal cell in a preferred embodiment of the liquid crystal display device according to the present invention.

6A to 6F are graphs and schematics showing electro-optical characteristics of liquid crystal cells in a preferred embodiment of the liquid crystal display device according to the present invention.

7A to 7F are graphs and schematic diagrams showing the electro-optical characteristics of the TN mode liquid crystal display device.

8A is a cross-sectional view of a liquid crystal cell in another embodiment of a liquid crystal display device according to the present invention.

8B is a cross-sectional view of a liquid crystal cell in another embodiment of a liquid crystal display device according to the present invention.

9A is a schematic plan view of a mold for an upper substrate used to manufacture another embodiment of a liquid crystal display device according to the present invention.

Fig. 9B is a schematic plan view of a lower substrate mold used for manufacturing another embodiment of a liquid crystal display device according to the present invention.

10A to 10C are schematic plan views of a negative pattern photomask used to manufacture another embodiment of a liquid crystal display device according to the present invention.

FIG. 11 is a schematic plan view of a negative pattern photomask used following the photomasks of FIGS. 10A, 10B, and 10C.

Fig. 12A is a schematic plan view showing a substrate in still another embodiment of a liquid crystal display device according to the present invention.

12B is a cross-sectional view of the substrate along the line B-B in FIG. 12A.

13 is a schematic cross-sectional view showing a liquid crystal cell in another embodiment of a liquid crystal display device according to the present invention.

14 is a schematic plan view of a negative pattern photomask used to manufacture another embodiment of a liquid crystal display device according to the present invention.

Fig. 15 is a schematic plan view of a negative pattern photomask having a portion where the transmittance is gradually changed, which is used to manufacture another embodiment of the liquid crystal display device according to the present invention.

16A is a schematic plan view showing a pixel on a substrate in another embodiment of a liquid crystal display device according to the present invention.

16B is a cross-sectional view of the pixel taken along the line B-B in FIG. 16A.

16C is a cross-sectional view of the pixel taken along the line C-C in FIG. 16A.

Fig. 17 is a schematic plan view of a negative pattern photomask having a portion where the transmittance is gradually changed, which is used to manufacture another embodiment of the liquid crystal display device according to the present invention.

18 is a schematic view showing an observation result by a polarization microscope of a liquid crystal cell in another embodiment of a liquid crystal display device according to the present invention.

19A and 19B are schematic cross-sectional views showing one example of a process for producing a color filter used in a liquid crystal display device according to the present invention.

20A is a schematic cross-sectional view showing a process for forming recesses in the color filters of FIGS. 19A and 19B under pressure pressed by a mold.

20B is a schematic cross-sectional view showing a process for forming recesses in the color filters of FIGS. 19A and 19B with the mold released.

21 is a schematic cross-sectional view of the color filter obtained by the process shown in FIGS. 20A and 20B.

22 is a schematic view showing the surface shape of the color filter manufactured in Comparative Example 2. FIG.

Fig. 23 is a schematic sectional view of another color filter used in the liquid crystal display device according to the present invention.

Fig. 24 is a schematic cross-sectional view of a conventional color filter in which a black matrix BM portion is concave.

25 is a schematic view showing an observation result by a polarization microscope of a liquid crystal cell in another embodiment of a liquid crystal display device according to the present invention.

Fig. 26 is a schematic view showing that the recesses formed on the substrate of the liquid crystal display device according to the present invention effectively control the position of the alignment axis.

27A to 27D are schematic diagrams showing a step for forming recesses in other color filters used in the liquid crystal display device according to the present invention.

28 is a schematic diagram of a conventional photomask corresponding to the photomask used in the process shown in FIGS. 27A to 27D.

29A and 29B are schematic cross-sectional views showing one example of recessed portions applicable to the present invention.

30A and 30B are schematic cross-sectional views showing another example of recessed portions applicable to the present invention.

FIG. 31 is a schematic cross-sectional view of a liquid crystal cell manufactured using the substrate shown in FIGS. 29A and 29B.

32A to 32F are schematic diagrams showing an effect of improving visual characteristics in the wide visual mode.

Fig. 33A is a schematic diagram showing the observation result by the polarization microscope of the liquid crystal cell in a liquid crystal display element, when an axis does not shift.

Fig. 33B is a schematic diagram showing the observation result by the polarization microscope of the liquid crystal cell in the liquid crystal display element when the axis is shifted.

[Purpose of invention]

The present invention relates to a liquid crystal display device and a manufacturing method thereof. In particular, the present invention relates to an inexpensive and high display quality liquid crystal display device and a simple manufacturing method thereof.

[Technical Field to which the Invention belongs and Prior Art in the Field]

Background Art Conventionally, liquid crystal display devices in twisted nematic (TN) mode have been widely used (for example, flat panel displays such as personal computers, word processors, amusement equipment and TV sets, or display panels, windows, doors or walls using a shutter effect). . The visual characteristics of the TN mode liquid crystal display device will be described below with reference to FIGS. 32A to 32C. 32A to 32C are schematic cross sectional views showing alignment states of liquid crystal molecules in a liquid crystal display device in TN mode. 32A shows a state in which no voltage is applied to the liquid crystal, FIG. 32B shows a state in which halftone is displayed by applying a voltage to the liquid crystal, and FIG. 32C shows a state in which a saturation voltage is applied to the liquid crystal.

In the TN mode liquid crystal display device, as shown in FIGS. 32A to 32C, when voltage is applied to the liquid crystal layer interposed between the substrates 1 and 2, the liquid crystal molecules of the liquid crystal layer are aligned. When the liquid crystal molecules are aligned in the TN mode, in the halftone state shown in Fig. 32B, the apparent light transmittance of the liquid crystal molecules seen in the direction A and the apparent light transmittance of the liquid crystal molecules seen in the direction B are different. As a result, direction dependence occurs in the visual characteristics (for example, when the observer observes from different directions A and B, the display contrast is significantly different). In order to improve the direction dependence of the visual characteristics, a liquid crystal display device of a wide viewing mode has been proposed in which liquid crystal molecules are oriented in at least two directions in a pixel. The improvement of the visual characteristic of the liquid crystal display element in the wide visual mode is demonstrated below with reference to FIGS. 32D-32F.

32D to 32F are schematic cross sectional views showing alignment states of liquid crystal molecules in a wide viewing mode liquid crystal display device. 32D shows a state in which no voltage is applied to the liquid crystal, and FIG. 32E shows a state in which halftone is displayed by applying a voltage to the liquid crystal, and FIG. 32F shows a state in which halftone is displayed by applying a voltage to the liquid crystal. 32F shows a state where a saturation voltage is applied to the liquid crystal.

In the wide-view mode liquid crystal display device, as shown in FIG. 32D, the liquid crystal layer 3 has a liquid crystal region 8 and a polymer region 7 surrounding the liquid crystal region 8. In this type of liquid crystal display element, in the halftone display state shown in Fig. 32E, the liquid crystal molecules 9 of the liquid crystal region 8 are axially symmetrical (e.g., concentric, radial or Spirally wound). Therefore, the apparent light transmittance of the liquid crystal molecules observed in the direction A and the apparent light transmittance of the liquid crystal molecules observed in the direction B are averaged to be substantially the same. As a result, the direction dependence of visual characteristics is improved as compared with the liquid crystal display element of TN mode.

As a specific example of the liquid crystal display element in the wide viewing mode, the following seven types of liquid crystal display elements are known.

The liquid crystal display element of a 1st form is a form shown in FIGS. 32D-32F. This type of liquid crystal display device has a liquid crystal region surrounded by a polymer region (for example, a polymer wall) in the liquid crystal cell. In addition, this liquid crystal display element does not require a polarizing plate, and does not require alignment treatment. In this liquid crystal display element, the transparent or cloudy state is electrically controlled using the birefringence of the liquid crystal. The liquid crystal display device matches the phase refractive index of the liquid crystal molecules with the refractive index of the support medium (polymer in the polymer region), thereby making the alignment of the liquid crystal uniform when voltage is applied, and displaying the transparent state. The light scattering state is indicated by scattering. In this method of manufacturing a liquid crystal display device, a mixture of a photocurable or thermosetting resin and a liquid crystal is injected between liquid crystal cells, and then the resin of the mixture is cured to precipitate a liquid crystal to form a liquid crystal region in the resin (polymer wall). How to do this is proposed (Japanese Patent Office No. 61-502128). Moreover, the technique which obtains a wide viewing mode by providing a polarizing plate so that a polarization axis orthogonally crosses on both sides of this liquid crystal display element is also proposed (Japanese Unexamined-Japanese-Patent No. 4-338923 and 4-212928).

The liquid crystal display device of the second aspect is a non-scattering type, in which a polarizing plate is used. This liquid crystal display element has a liquid crystal region comprising a plurality of domains surrounded by a polymer formed by phase separation from a mixture of liquid crystal and photocurable resin (Japanese Patent Laid-Open No. 5-27242). In this liquid crystal display device, the alignment state of each domain of the liquid crystal region is scattered by the polymer formed by phase separation, and the liquid crystal display device is random. As a result, when the voltage is applied, the standing directions of the liquid crystal molecules are different in individual domains, so that Δn · d is averaged, and the apparent transmittance seen in each direction is the same. Therefore, the visual characteristic in the halftone state is improved.

The liquid crystal display device of the third aspect has a film made of a crystalline polymer on the surface of a substrate and having a spherical structure. In this liquid crystal display element, the liquid crystal molecules in the liquid crystal region are oriented using the axisymmetric alignment control force of the film spherical structure to realize a wide viewing angle display mode (Japanese Patent Laid-Open No. 6-308496).

In the liquid crystal display device of the fourth aspect, an alignment film is coated on a substrate, and the liquid crystal molecules are randomly oriented without performing an alignment process such as rubbing or the like (Japanese Patent Laid-Open No. 6-194655).

In the liquid crystal display elements of the third and fourth aspects, since the liquid crystal molecules in the pixels are oriented in different directions, disclination lines are generated, and contrast is often lowered.

In order to prevent the occurrence of the disclination line in the pixel, a fifth type liquid crystal display device has been proposed. In this liquid crystal display element, the liquid crystal molecules in the pixel are aligned in axisymmetry. For example, the present applicant has proposed a liquid crystal display device which is manufactured by controlling an irradiation amount to a liquid crystal cell having a liquid crystal material and a photocurable resin (for example, by irradiating a liquid crystal cell through a photomask) (Japanese Patent Laid-Open No. 7-A). No. 120728). In this liquid crystal display device, when no voltage is applied, the liquid crystal molecules are aligned in an axisymmetric phase (for example, vortex phase) in the pixel region, and the vortex winding orientation is brought to a homeotropic state by applying a voltage to the liquid crystal molecules. Change. As a result, the visual characteristic is remarkably improved.

In the liquid crystal display device of the sixth aspect, the axisymmetric alignment of liquid crystal molecules is realized by an alignment process (for example, by forming an axisymmetric fine groove in a substrate) (Japanese Patent Laid-Open Nos. 6-265902 and 6). -324337).

The liquid crystal display device of the fifth aspect conceptually lacks practicality. In the liquid crystal display device of the sixth aspect, it is difficult to control the pretilt of the liquid crystal molecules. For this reason, a disclination line often occurs. In addition, the stability of the axisymmetric orientation is insufficient.

The liquid crystal display device of the seventh aspect has a so-called ASM structure. In this liquid crystal display element, the axisymmetric orientation of liquid crystal molecules in a pixel is realized by irradiating light to a liquid crystal cell having a liquid crystal material and a photocurable resin while varying the temperature and applied voltage according to a specific rule. 6-301015 and 7-120728, etc.).

However, in the case of aligning the liquid crystal molecules by the above technique, the position of the axis of axisymmetric alignment cannot be sufficiently controlled. Therefore, the alignment axis of the axisymmetric alignment of the liquid crystal molecules is inclined or the position of the alignment axis is shifted. Problems caused by axial shift will be described with reference to FIGS. 33A and 33B. 33A and 33B are schematic views showing the results of observation with a polarization microscope when the liquid crystal cell is inclined in an orthogonal nicotine state. As can be seen from the comparison of Figs. 33A and 33B, since the average transmittance of the pixel with the deviation of the axis is different from that of the other pixels, roughness is observed in the whole display. In addition, when the vision is changed and observed, the area of the black-looking part in one pixel increases.

As mentioned above, in the conventional liquid crystal display element, the position control of the orientation axis | shaft of liquid crystal molecule orientation is inadequate. In addition, in the conventional liquid crystal display device, a complicated manufacturing process is also required to realize axisymmetric alignment of liquid crystal molecules having insufficient position control of the alignment axis (e.g., by changing the temperature and applied voltage in accordance with a specific rule, Need to be investigated). That is, the conventional liquid crystal display device has a problem of high manufacturing cost and insufficient position control of the alignment axis.

Therefore, it does not require a complicated manufacturing process (hence inexpensive liquid crystal display device), and the position of the alignment axis of the liquid crystal molecule alignment can be precisely controlled (thus, excellent in display characteristics such as excellent visual characteristics and no roughness). A liquid crystal display device is desired.

[Technical problem to be achieved]

The liquid crystal display device of the present invention comprises a display medium including at least liquid crystal between at least one pair of transparent substrates, wherein at least one substrate of the pair of substrates includes a film having recesses on the display medium side, The recessed portion has a bottom portion near the central portion of the recessed portion viewed from the normal direction of the substrate, and liquid crystal molecules contained in the display medium are axially symmetrically aligned with the bottom portion or its vicinity.

In one embodiment of the present invention, the outline defining the recessed portion in the vertical plane through the bottom portion is a curve, and the sign of the second derivative of the curve is positive.

In another embodiment of the present invention, the outline defining the recessed portion in the vertical plane through the bottom portion is a straight line.

In still another embodiment of the present invention, the contour defining the recessed portion in the vertical plane through the bottom portion is a curve, and the sign of the second derivative of the curve is negative.

In still another embodiment of the present invention, the contour defining the recessed portion in the vertical plane through the bottom is a curve, and the curve is a portion having a positive sign of the second derivative of the curve and the curve of the curve. The sign of the second derivative has a negative part.

In still another embodiment of the present invention, a substrate having a film having recesses and a substrate having a film having convex portions are disposed to face each other such that a bottom portion of the recess and an upper portion of the convex portion correspond to each other. The liquid crystal molecules contained in the display medium are axially symmetrical with the bottom and the top or the vicinity thereof as axes.

In another embodiment of the present invention, the display medium has a liquid crystal region mainly containing a liquid crystal and a polymer region surrounding the liquid crystal region.

In another embodiment of the present invention, the recess is formed to maximize the cell gap at the center of the liquid crystal region and to minimize the cell gap at the end of the liquid crystal region, wherein the axisymmetric alignment axis of the liquid crystal molecules is Located in the center of the liquid crystal region.

In another embodiment of the present invention, the inclination of the surface of the film having the recess portion is continuously changed at the boundary between the pixel portion where the liquid crystal region exists and the non-pixel.

In another embodiment of the present invention, the film having the recessed portion is formed of a thermoplastic insulating material or a thermosetting insulating material.

In another embodiment of the present invention, the film having the recessed portion is formed of a photosensitive insulating material.

In another embodiment of the present invention, a transparent electrode is formed on a substrate having a film having the recessed portion.

In another embodiment of the present invention, the device further comprises a color filter including a colored layer, a light shielding layer, and an overcoat layer covering the colored layer and the light shielding layer, wherein the recess is formed in the color filter. have.

In another embodiment of the present invention, the main portion is provided corresponding to the pixel portion, and a part of the color filter corresponding to the non-pixel portion is flat.

In another embodiment of the present invention, a transparent electrode is formed on the overcoat layer.

In another embodiment of the present invention, the overcoat layer is formed of a material selected from the group consisting of thermoplastic resin, thermosetting resin and photocurable resin.

In another embodiment of the present invention, the colored layer has a recess formed by photolithography using a color resist and having an opening having a diameter of 10 µm or less, and the light shielding layer is formed higher than the colored layer. The overcoat layer is formed of an inorganic material or an organic material.

The present invention also provides a method of manufacturing a liquid crystal display device. This method includes forming a film for forming recesses in at least one of the pair of substrates; And pressing the film with a mold having a predetermined concave-convex surface to form recesses of a predetermined shape at predetermined positions of the film.

In one embodiment of the present invention, the uneven surface of the mold has a conical or elliptical cone.

In addition, in the method of the present invention, a convex portion in which a plurality of films are laminated on at least one of the pair of substrates so as to have a circular or oval shape in the normal direction of the substrate and have a larger area as the film is closer to the substrate, and the peripheral portion thereof is stepped. Forming a; And forming a film to cover the convex portion to form a recess having a smooth surface and having a bottom portion between adjacent convex portions.

Moreover, the method of this invention is the process of forming the film | membrane which consists of a photosensitive material in at least one of a pair of board | substrate; And exposing the film to form a recessed portion in the film for patterning through a gradation mask in which light transmittance is changed gradationally.

In one embodiment of the present invention, the method comprises: injecting a mixture of a liquid crystal and a photopolymerizable compound between the pair of substrates; And irradiating the mixture with ultraviolet rays to cure the photopolymerizable compound.

In addition, the method of the present invention comprises the steps of forming a color filter and a light shielding layer at a predetermined position on the substrate, and then forming an overcoat layer covering the colored layer and the light shielding layer to form a color filter; And pressing the overcoat layer with a mold having a predetermined uneven surface to form recesses of a predetermined shape at a predetermined position of the overcoat layer.

In one embodiment of the present invention, the overcoat layer is formed by applying an overcoat agent, and then removing the solvent contained in the overcoat agent.

In another embodiment of the present invention, the mold has a convex portion or protrusion at a position corresponding to the pixel.

In another embodiment of the invention, the mold has a flat surface on a portion thereof.

Further, the method of the present invention includes a step of forming a colored layer of a color filter by photolithography using a color resist, and irradiating light through a photomask so as not to cure a portion corresponding to the pixel center portion of the color resist. And forming a recess to form a predetermined recess in the pixel center portion of the colored layer.

In one embodiment of the present invention, the diameter of the opening of the recess is 10 m or less.

Accordingly, the present invention provides (1) a liquid crystal display device in which the position of the alignment axis of the liquid crystal molecules can be precisely controlled (i.e., excellent viewing angle characteristics and roughness), and (2) the simplicity of such a liquid crystal display device. And provides an inexpensive manufacturing method.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Configuration and Function of Invention]

Lumbar

In the present specification, a substrate having recesses includes a substrate having recesses, a substrate having a film having recesses, and a substrate having a color filter having recesses. The color filter having recesses further includes a color filter having recesses in the colored layer and an overcoat layer, and includes a color filter having recesses in the overcoat layer. In addition, unless otherwise indicated, a recess means a recess which has a bottom near the center of a recess when it sees from the normal direction of a board | substrate.

According to this invention, the following advantages can be acquired by using the board | substrate which has recessed part. When the liquid crystal molecules are aligned parallel to the substrate surface in the vicinity of the bottom of the recess, the liquid crystal molecules are axially symmetrically aligned along the shape of the recess, and the vicinity of the bottom thereof becomes the central axis of the axisymmetric orientation. As a result, the axisymmetric orientation of the liquid crystal molecules can be easily obtained without requiring complicated manufacturing processes (e.g., irradiating light with varying temperature and applied voltage in accordance with specific rules). In addition, since the vicinity of the bottom of the recessed portion serves as the central axis of the axisymmetric alignment, uniform axisymmetric alignment can be easily obtained in the entire screen by forming a recessed portion having a predetermined shape in each pixel at a predetermined position. Thus, by using the board | substrate which has recessed part, the liquid crystal display element of the outstanding display quality which is inexpensive, uniform, and does not have roughness can be obtained.

Cross-sectional shape of the main part

The recessed part formed in a board | substrate is a recessed part which has a bottom part near a center part when seen from the normal line direction of a board | substrate. That is, the recessed portion is a rotationally symmetrical body substantially centered on the bottom portion. The cross-sectional shape of the recessed portion can be defined by the sign of the second derivative of the curve indicating the outline defining the recessed portion in the vertical section through the bottom portion. The cross-sectional shape of the recess formed in the substrate of the present invention can be obtained, for example, by one of the shapes described below, or a combination thereof.

1. If the sign is positive, as shown in Fig. 1A, the curve showing the outline defining the recesses in the vertical section through the bottom has a structure in which the curve is downwardly convex (i.e., U-shaped). .

2. When the sign is 0, as shown in Fig. 1B, the curve showing the outline defining the main portion in the vertical section through the bottom has a straight line (i.e., V-shape).

3. In the case where the sign is negative, as shown in Fig. 1C, the curve showing the outline defining the recesses in the vertical section through the bottom has a structure in which the curve is upwardly convex.

4. When the sign has both positive and negative signs, as shown in Fig. 1D, the curve showing the outline defining the main part in the vertical section through the bottom part is upwardly convex and downwardly. It has a structure having both convex portions.

Number of recesses and shape of bottom

One main part may be formed with respect to each pixel, and two or more main parts may be formed. In addition, one recessed portion may be formed on the substrate for two or more pixels.

It is preferable that the bottom part of a recessed part is 5 micrometers in diameter in conversion to a circle, and becomes a point. When the diameter converted into a circle exceeds 5 micrometers, the position of the axis of axial symmetry alignment is out of the center of the pixel, and the display surface becomes rough in many cases.

In the present invention, the recessed portion can be formed in a film provided on the substrate. Any material may be used for the film on which the recess is formed, as long as it is a transparent and capable of forming recesses. Since the formation of the film and the recesses is both easy, a photosensitive resist can be used representatively. Alternatively, as will be described later, the recessed portion may also be formed in the color filter.

How to form a recess

The recess is typically formed by at least one of the following first to fourth methods.

The first method is a step of forming a film for forming recesses on a substrate, and pressing the film with a mold having a predetermined concave-convex surface (for example, a mold having conical or elliptical convex convex portions) to form a predetermined shape at a predetermined position of the film. Forming a recess. The film for forming recesses is formed of a thermoplastic insulating material, a thermosetting insulating material or a photosensitive insulating material. The film for forming recesses can be formed by any known method. The thickness of the film is preferably about 1 to 3 mu m, more preferably about 2 mu m.

It is preferable to perform pressurization, heating. The heating temperature may vary depending on the material of the film forming the recessed portion, but is preferably 180 to 220 ° C, more preferably about 200 ° C.

The second method comprises the steps of: laminating a plurality of films on a substrate such that the film close to the substrate has a large area in a circular or conical shape as viewed from the normal direction of the substrate, and forming convex portions whose peripheral edges are stepped; And forming a film to cover the convex portion, thereby forming a concave portion having a smooth surface and having a bottom portion between adjacent convex portions (eg, inverted conical or inverted conical).

The third method includes forming a film made of a photosensitive material on a substrate; And exposing the film to pattern through a gradation mask in which light transmittance changes gradation to form recesses (eg, inverted or inverted conical) in the film.

The fourth method includes a step of forming a colored layer of a color filter by photolithography using a color resist. In this method, light is irradiated through a photomask so as not to harden a portion corresponding to the pixel center portion of the color resist, and a recess of the V-shaped cross section is formed to form a predetermined recessed portion in the pixel center portion of the colored layer. To form. In this case, when a light shielding layer (e.g., a black matrix (BM)) provided to surround the colored layer is formed higher than the colored layer, and an overcoat layer is formed thereon, recesses having bottoms in portions corresponding to the recesses are formed. It is formed by an overcoat layer. The size of the opening of the recess is preferably a diameter of 10 mu m or less. When the diameter of an opening exceeds 10 micrometers, a recess may penetrate a colored layer and light may enter a colored layer. As a result, color purity may decrease.

The recessed portion formed by such a method has a smooth surface. Therefore, the outline defining the recessed portion can be a curve in which the slope continuously changes at the boundary between the pixel portion and the non-pixel portion. As a result, since the alignment defect of the liquid crystal molecules is eliminated at the boundary between the pixel portion and the non-pixel portion, it is possible to prevent the decrease in contrast due to the disclination line at the time of voltage application.

Driving method

The liquid crystal display element of this invention is not specifically limited. The present liquid crystal display device can be driven by, for example, a simple matrix driving method and an active matrix driving method such as a-Si TFT, p-Si TFT and MIM. These driving methods can be appropriately selected according to desired characteristics of the liquid crystal display element.

Substrate material

As the substrate material, a glass substrate, a quartz substrate, a plastic substrate made of a polymer film, or the like, which is a transparent solid through which visible light is transmitted, can be used.

To form a plastic substrate, for example, poly (ethylene terephthalate) (PET), acrylic polymer, styrene or polycarbonate and the like can be used. When using such a plastic substrate, it becomes possible to form a recessed portion directly on the substrate itself. In addition, in the case of a plastic substrate, by providing polarization property to the substrate itself, the substrate itself can function as a polarizing plate, thereby producing a liquid crystal display device that does not require an additional polarizing plate.

These substrates are a pair of substrates of the liquid crystal display element, and may be used in combination of different types of substrates. In addition, a laminated substrate combining two or more substrates of different thicknesses regardless of the same type of heterogeneous substrate may be used.

Liquid Crystal and Polymerizable Materials

The liquid crystal included in the display medium of the liquid crystal display device of the present invention is not particularly limited as an organic mixture exhibiting liquid crystal behavior in the vicinity of room temperature, and may be used as any material known in the art. As a form of a liquid crystal, a nematic liquid crystal, a cholesteric liquid crystal, a smectic liquid crystal, a ferroelectric liquid crystal, a discotic liquid crystal, etc. are mentioned. The liquid crystal material may contain a chiral agent if necessary. These liquid crystals may be used alone or in combination.

The display medium of the liquid crystal display device of the present invention includes a polymer region as necessary. As the polymerizable material for forming the polymer region, any known photocurable resin and thermosetting resin can be used. In addition, the polymerizable materials may be used alone or in combination. The polymerizable material may contain a polymerization initiator if necessary. In the case of using the polymerizable material, the polymerizable material can be used in combination with the liquid crystal material at an appropriate ratio according to the use.

Color filter

If necessary, the liquid crystal display of the present invention may include a color filter, and recesses may be formed in the color filter. The color filter has a colored layer and a light shielding layer, and has an overcoat layer as needed. It is preferable that a color filter is formed on a board | substrate.

The colored layer is formed of a color ink of red (R), green (G), blue (B), or a color resist corresponding to R, G, B, or the like. The formation method of a colored layer is not specifically limited. For example, an electrodeposition method, a film adhesion method, a printing method, a color resist method, or the like can be used.

As the light shielding layer (so-called black matrix (BM)), metal materials such as Mo, Al, Ta, and organic materials such as black resist can be used. The formation method of BM is not specifically limited, For example, the electrodeposition method, the film adhesion method, the printing method, the color resist method, etc. can be used.

The recessed part is typically formed in the overcoat layer when formed in the color filter, but may be formed in the colored layer as necessary. Alternatively, recesses for forming recesses may be formed in the colored layer.

Overcoat layer

The overcoat layer in which the recess is formed is (meth) acrylic acid or (meth) acrylate substituted with a photocurable resin (alkyl group having 3 or more carbon atoms or phenyl group (e.g. isobutyl acrylate, n-butyl methacrylate)), It is formed using a thermosetting resin (eg epoxy acrylate), or a thermoplastic resin (eg polyimide, polyphenylene oxide). Polyimide, epoxy acrylate and the like having excellent heat resistance can be preferably used. This is because, in the present invention, the overcut layer exists in the liquid crystal cell until the liquid crystal display element is completed, and the transparent electrode is formed again on the overcoat layer. Alternatively, the overcoat layer is formed using an inorganic material (eg, siloxane compound).

Manufacturing method of color filter

The colored layer and the BM are formed at a predetermined position on the substrate by a predetermined method. The formation order of a colored layer and BM does not become a problem. According to the manufacturing method according to the desired characteristic of a color filter, any of a colored layer and BM may be formed first.

Next, an overcoat agent (for example, a solution containing an overcoat material at a predetermined concentration) is applied onto the substrate on which the colored layer and the BM are formed. If necessary, the contained solvent is removed by a known method.

Next, the mold which has the convex part of a predetermined shape is pressed on the film | membrane which consists of an overcoat agent. In the case where the overcoat agent is a photocurable resin, the resin is cured in a shape formed by a mold by irradiating light to fix the shape. When the overcoat agent is a thermosetting resin, the resin is cured in the shape formed in the mold by heating to fix the shape. When the overcoat agent is a thermoplastic resin, it is heated to the temperature to be plasticized and cooled in a pressurized state, thereby solidifying the resin in the shape formed in the mold to fix the shape. In this way, the color filter which has a recessed part of a desired shape is formed. Therefore, by selecting an appropriate mold, a color filter having desired recesses can be formed with good reproducibility.

For example, in the case of forming a bowl-shaped recess necessary for the axisymmetric orientation, the mode having the inverse bowl structure is pressed to a predetermined position. In order to form a conical recess, a mold having a conical protrusion is pressed at a predetermined position. Thereby, each desired part can be formed.

If necessary, a transparent electrode can be formed on a substrate provided with a color filter, and an insulating film can be formed thereon again.

Hereinafter, preferred embodiments of the present invention will be described. However, the present invention is not limited to these examples.

Example 1

The case where recesses of a predetermined shape are formed (that is, when recesses are formed by the first method) by pressing the membrane with a mold having a predetermined recessed and projecting surface will be described.

The liquid crystal display element of this embodiment is manufactured as follows.

A 500 mm thick ITO (a mixture of indium oxide and tin oxide) was formed on a 1.1 mm thick glass substrate. This substrate is used as a pair of substrates.

On one of the pair of substrates, a photosensitive resist (V-259PA manufactured by Shinil Iron Chemical Co., Ltd.) containing 0.5% by weight of a spacer (4.5 탆 in diameter) for holding a cell gap was applied, and FIGS. 2A and 2B. Patterning is performed on the substrate using a photomask as shown in FIG. Next, after the photosensitive resist (OMR83 manufactured by Tokyo Inc.) was formed into a film having a thickness of about 2.0 mu m on the patterned substrate, the substrate was placed in an oven at 200 deg. C to soften the film. Next, the molds shown in FIGS. 3A and 3B are joined into a soft film to form inverted conical recesses for all the pixels as shown in FIGS. 4A and 4B. Thereafter, an ITO film is formed by sputtering to obtain a target substrate.

A sealing agent (struct-bond XN-21S) containing glass fiber (4.5 탆 in diameter) is printed on another substrate having ITO as a transparent electrode. This process may be performed before the above-mentioned recess forming process.

Next, two substrates prepared as described above are attached to each other.

Next, the following uniform mixture was injected between the attached substrates to prepare a liquid crystal cell: 0.1 g of R-684 (manufactured by Nippon Kayaku Co., Ltd.); 0.1 g p-phenylstyrene; 10.06 g of the compound represented by formula (I); 3.74 g of liquid crystal material ZLI-4792 (manufactured by Merck; 0.4 wt% of S-811); Photopolymerization initiator (Irgacure 651 Ciba-Geigy Co., Ltd.) 0.02 g

Next, the liquid gel is cooled to 25 ° C. at a temperature at which the mixture exhibits a melting state (uniform state) to form a liquid crystal region and a polymer region (polymer wall). Preferably, the axially symmetrical orientation of the liquid crystal molecules can be further improved by slow cooling the liquid crystal cell at a temperature at which the mixture exhibits an isotropic phase (temperature above the isotropic temperature). In particular, the orientation defect by the flow to the vicinity of the injection port can be corrected.

Next, the cell temperature is maintained at 25 ° C., and ultraviolet rays are irradiated for 20 minutes at an intensity of 2.5 mW / cm 2 to stabilize the orientation.

5 is a schematic view showing the results of observing the liquid crystal cell produced as described above with a polarizing microscope. One liquid crystal region is arranged in one pixel 50 (monodomain state), and the liquid crystal molecules are axially symmetrically aligned. In addition, since the center of the axisymmetric alignment is located at the center of the inverted cone shape, the roughness is not visually observed in full screen. That is, good axisymmetric orientation is obtained in all liquid crystal regions. This is because when the two polarizing plates having the orthogonal polarization axes are fixed with the cells interposed therebetween and the cells are allowed to rotate, the position of the shuriren pattern 6 in the liquid crystal region 8 is constant so that the liquid crystal It can be understood by the fact that only the polymer wall 7 around the region 8 is observed to rotate.

Next, two polarizing plates are attached to both sides of the liquid crystal cell thus manufactured so that the polarization axes of the polarizing plates are perpendicular to each other, thereby manufacturing a liquid crystal display device.

The liquid crystal display device manufactured as described above was observed with a polarizing microscope in the state where voltage was applied. As a result, it was observed that no disclination occurred even when voltage was applied and good black display was obtained.

6A to 6F are graphs and schematic diagrams showing the electro-optic characteristics of the liquid crystal cell manufactured in this embodiment, and FIGS. 7A to 7F are graphs and schematic diagrams showing the electro-optical characteristics of the liquid crystal cell of the conventional TN mode. In the measurement of this electro-optical characteristic, two polarizing plates in which the polarization axes are parallel to each other are used as a blank (transmittance 100%). 6A-6F and 7A-7F, as will be apparent, in the liquid crystal cell of this embodiment, no inverted shape observed in the liquid crystal cell of the conventional TN mode is found, and transmittance in the high visual direction at the time of voltage saturation. No increase is found. In addition, roughness is not found even in the intermediate bath.

Example 2

The case where all of a pair of board | substrate has a recessed part is demonstrated.

In the same manner as in Example 1, two substrates having recesses having an inverted cone shape were produced. The two substrates are attached so that their bottoms face each other as shown in Fig. 8A.

A liquid crystal cell was prepared by injecting the same mixture as in Example 1 between the substrates attached thereto, and then irradiating the UV light at 365 nm at 50 ° C. with an intensity of 3.2 mW / cm 2 for 20 minutes to cure the monomers. Area and polymer area (polymer wall) are formed. In addition, a liquid crystal display device is manufactured in the same manner as in Example 1.

In the liquid crystal display device thus obtained, the recessed portion is formed to have the largest cell gap in the center of the liquid crystal region, and thus has the smallest cell gap at the ends of the liquid crystal region. As a result, the axisymmetric alignment axis of the liquid crystal molecules is located at the center of the liquid crystal region.

When the liquid crystal cell is observed with a polarizing microscope, it is confirmed that one axisymmetric orientation is formed for all pixels around the center of the pixel. Further, the obtained liquid crystal display element has a good axisymmetric orientation, whereby the viewing angle is much wider than that of the conventional liquid crystal display element. The viewing angle is 60 degrees or more in the vertical direction and 60 degrees or more in the horizontal direction, and the contrast ratio is 10.

In this embodiment, as shown in Fig. 8A, it is preferable that the two substrates face each other so that the lowermost portion of the recess coincides when viewed in the vertical direction of the substrate, but some displacement can be allowed. In other words, even if the lowermost part of one recess part is slightly displaced in the direction along the substrate surface with respect to the lowermost part of the other recess part, the axisymmetric orientation can be obtained.

Example 3

The other case where a pair of board | substrates all have a recessed part is demonstrated.

In this embodiment, as shown in Fig. 8B, a liquid crystal display device having a pair of substrates in which the lowermost part of the recessed part of one substrate and the uppermost part of the convex part of the other substrate face each other. Such a liquid crystal display device is manufactured as follows.

In the same manner as in Example 1, a substrate having recesses of inverse cone shape was produced. On the other hand, the board | substrate which has a conical convex part is manufactured using the mold which has the form reversed from what was used in Example 1.

Next, both substrates are attached to each other as shown in Fig. 8B. More specifically, the substrates are attached so that the lowermost part of the recessed part of one substrate and the uppermost part of the convex part of the other substrate face each other. The following procedure was performed in the same manner as in Example 2 to produce a liquid crystal cell. In addition, a liquid crystal display device is manufactured in the same manner as in Example 1.

When the liquid crystal cell thus manufactured is observed with a polarizing microscope, it can be seen that one axisymmetric orientation is formed for all pixels around the center of the pixel. In addition, the electro-optical characteristics of the manufactured liquid crystal display device are of the type shown in Figs. 6A-6F as in the first embodiment. That is, the inversion phenomenon of the display image as shown in Figs. 7A-7F is not observed, and no increase in transmittance in the wide viewing direction at the time of voltage saturation is also observed.

Example 4

The case where the board | substrate with which radial microgrooves were formed in all the recessed parts, and the board | substrate with which concave microgrooves were formed in all recesses are demonstrated.

A substrate having recessed portions was prepared in the same manner as in Example 1 except that the molds shown in FIGS. 9A and 9B were used instead of the mold used in Example 1. FIG. The mold shown in FIG. 9A is the mold of the upper substrate and the mold shown in FIG. 9B is the mold of the lower substrate. Therefore, in this embodiment, the fine grooves formed in the upper and lower substrates are perpendicular to each other.

Next, the prepared substrates were attached to each other, and the liquid crystal material ZLI-4792 (Merck S-811 containing 0.4 wt%) was injected between the attached substrates. The following procedure is the same as that of Example 1 except not irradiating an ultraviolet-ray.

In the liquid crystal cell manufactured as described above, liquid crystal molecules are axially symmetrically aligned in all pixels, and unlike the liquid crystal cell of the TN mode, no inversion phenomenon is found and roughness is not observed in the full screen.

In this embodiment, the substrate having the radial microgrooves formed in all the recesses is used as the upper substrate, and the substrate having the concave microgrooves formed in all the recesses is used as the lower substrate, but the upper and lower substrates may be used in other ways. In addition, the shape of the fine grooves formed in the recesses is not particularly limited as long as the axisymmetric alignment of the liquid crystal parts can be realized. For example, in addition to radial and concentric circles, spiral fine grooves can be formed. Corresponding to the shape of the formed microgrooves, the liquid crystal molecules may be aligned in the liquid crystal region, for example radially, concentrically or helically. Moreover, the board | substrate with the groove | channel in all the recessed parts can be used only for one side of a pair of board | substrate.

Example 5

The case where a recess is formed by a 2nd method is demonstrated. That is, on the substrate, a plurality of films having a circular or elliptical shape as viewed in the normal direction of the substrate are stacked to have a larger area as they approach the substrate, thereby forming stepped convex portions on the circumference thereof. Thereafter, a film is formed to cover the convex portion. Thus, in this embodiment, recesses are formed that have a smooth surface and have the lowest (eg, inverted or inverted) between adjacent convex portions.

The liquid crystal display element of this embodiment is manufactured as follows.

A substrate (hereinafter referred to as a TFT substrate) on which a TFT (thin film transistor) is formed and an opposing substrate on which a color filter is formed are prepared. On the opposing substrate, a photosensitive resist containing 0.5 wt% of a spacer having a diameter of about 4.0 탆 is applied, and patterning is performed on the substrate as shown in Figs. 2A and 2B using a photomask.

Next, a resist film is formed on the patterned substrate using the same resist material as in Example 1. FIG. Next, the resist film is patterned by using a photomask having circular light shielding portions (diagonal portions) having different diameters as shown in Figs. 10A-10C.

Among the photomasks, patterning is performed using sequentially from photomasks having a small diameter of the light shielding portion. Next, patterning is performed with a photomask as shown in FIG. 11A to obtain a substrate having convex portions with circumferential portions stepped as shown in FIGS. 12A and 12B. The upper portion of the convex portion corresponds to the non-pixel portion and has a lower portion corresponding to the center or the vicinity of the pixel portion. In addition, by patterning using a photomask, the spacer is present only in the non-pixel portion.

Thereafter, using a resist similar to that used for forming the convex portions, a film is formed on the substrate having the stepped convex portions as shown in Fig. 12B. By forming the film, the stepped convex portions are smoothed, and the boundary between the pixel portion and the non-pixel portion is smoothed to obtain a substrate having a recessed portion having a gentle inverted cone shape. It is desirable to form a gentle curve defining the main portion at the boundary between the pixel portion and the non-pixel portion. This is because the alignment angles of the liquid crystal molecules at the boundary change continuously as the curve defining the recesses at the boundary between the pixel portion and the non-pixel portion continuously changes.

Next, a TFT substrate and a substrate on which recesses are formed as described above are attached in the same manner as in Example 1.

Next, the same mixture as in Example 1 was injected between the substrates attached thereto, followed by irradiation of ultraviolet rays for 40 minutes at an intensity of 3.2 mW / cm 2 to polymerize the photopolymerizable compound to stabilize the alignment state.

When the liquid crystal cell thus produced is observed with a polarizing microscope, the liquid crystal region is arranged with respect to the mode pixel as in Example 1 (monodomain state), so that the liquid crystal molecules are axially symmetrically aligned. In addition, when the liquid crystal display device is manufactured in the same manner as in Example 1, the roughness is not visually observed in full screen. In addition, even when voltage is applied, no disclination occurs, and high contrast is obtained.

Example 6

A liquid crystal cell similar to that in Example 5 was prepared except that the following mixture was used: 0.05 g of R-684 (manufactured by Nippon Chemical Co., Ltd.); 1.9 g of liquid crystal material ZLI-4792 (manufactured by Merck: 0.4 wt% of S-811); Photopolymerization initiator (Irgacure651, Ciba-Geigy Co.) 0.0025 g. That is, a liquid crystal cell is manufactured using the mixture whose content of polymeric material is less than 5 weight%.

Next, ultraviolet rays are irradiated to the liquid crystal cell as in Example 2.

In the liquid crystal cell manufactured as described above, since a mixture having a low content of the polymerizable material is used, the polymer wall is not substantially formed, and as shown in FIG. 13, a polymer film is formed on the substrate surface, and the liquid crystal molecules are It is axially oriented with respect to all the pixels. In addition, the roughness is not visually observed at full screen, and the contrast at the time of voltage application is also satisfactory.

Example 7

The case where a recessed part is formed as a 3rd method is demonstrated. More specifically, by forming a film of photosensitive material on the substrate and exposing and patterning the film through a gradation mask in which the light transmittance is gradually changed, the main portion of the film (e.g., an inverted cone or an inverted ellipse) is formed. A case of forming a will be described.

The liquid crystal display element of this embodiment is manufactured as follows.

After dispersing the cell gap holding spacer (diameter: 4.5 mu m) at a density of about 40 pieces / mm 2 on the glass substrate provided with ITO, a photosensitive resist (OMR83: manufactured by Tokyo Chemical Co., Ltd.) is applied. Next, the resist is exposed and developed at an intensity of 15 mW / cm 2 through the photomask shown in FIG. 14 to obtain a rectangular pixel pattern.

Next, a negative photosensitive resist (V-259PA: manufactured by Shinil Iron Chemical Co., Ltd.) was applied to a thickness of 2 μm, and exposed and developed through a photomask having a gradation pattern having different transmittances as shown in FIG. 15. A substrate having elliptical recesses as shown in FIGS. 16A-16C is prepared. In the photomask having the gradation pattern, the central portion has a transmittance of 100%, and the portion corresponding to the pixel end has a transmittance of 0%, and the transmittance changes step by step in the middle portion. This photomask is produced step by step by etching.

Next, a target substrate is obtained by depositing ITO on the substrate on which the recess is formed.

Next, an alignment film is coated on the other substrate among the ones prepared before and after the above substrate production. The board | substrate which has this alignment film, and the board | substrate obtained as mentioned above are stuck.

Next, the same mixture as in Example 1 is injected between the attached substrates, and an ultraviolet ray of 3.0 mW / cm 2 is irradiated to polymerize the polymerizable material (monomer).

When the liquid crystal cell thus prepared is observed with a polarizing microscope, it is observed that the liquid crystal molecules are in an axisymmetric alignment state. In addition, the position of the alignment axis is fixed to the center of the pixel, and no large displacement of the position is observed in any pixel. Visually, roughness is not observed.

Comparative Example 1

A liquid crystal cell was produced in the same manner as in Example 1 except that no recess was formed in the substrate.

When the liquid crystal cell thus produced is observed with a polarizing microscope, it is observed that no axisymmetric alignment of liquid crystal molecules is formed. In addition, visually, the roughness of the screen is considerably observed.

Example 8

The case where two or more main parts (two in this embodiment) are provided in one pixel is demonstrated.

The liquid crystal display element of this embodiment is manufactured as follows.

In the same manner as in Example 7, a cell gap holding spacer (diameter: 4.5 mu m) was scattered on the glass substrate provided with ITO, and then a photosensitive resist (OMR83: manufactured by Tokyo Chemical Co., Ltd.) was applied to the photo substrate and subjected to photosensitive and patterning.

Next, a photosensitive resist (V-259PA, manufactured by Shin-Il Cheol Chemical Co., Ltd.) was applied to the substrate and exposed using a gradation photomask shown in FIG. 17 to have two inverted concave portions in one pixel (two in one pixel). Substrates having two axisymmetric centers.

Next, the substrate thus obtained and the counter substrate prepared before and after the above substrate production are attached.

Next, a liquid crystal cell having a uniform axisymmetric orientation is obtained by injecting the same mixture as in Example 1 between the attached substrates and heating and slow cooling.

When the liquid crystal cell thus obtained is observed with a polarizing microscope, it is confirmed that two axisymmetric alignments are uniformly formed in one pixel as shown in FIG.

Example 9

This embodiment describes the case where recesses are formed on the color filters in Examples 10-12 and Comparative Examples 2 and 3 below.

The color filter A of this embodiment is manufactured as follows.

As shown in Fig. 19A, a color layer corresponding to R, G, and B is formed on a predetermined pixel by using a color resist on a glass substrate (thickness of 1.1 mm). In addition, BM is formed in the nonaqueous water portion using the black resist.

Next, as shown in Fig. 19B, an overcoat agent containing a thermosetting resin (epoxy methacrylate in this embodiment) is applied to the substrate to form an overcoat layer, and a temperature lower than the curing temperature of the thermosetting resin (this embodiment In the example, the solvent contained in the overcoat agent is removed at 90 占 폚.

Next, as shown in Fig. 20A, a mold having conical protrusions is pressed against all the pixels on the substrate on which the overcoat layer is formed, and heated to a curing temperature (180 DEG C in this embodiment) in the pressurized state. Then, as shown in Fig. 20B, the mold is released. As a result, conical recesses are formed in the overcoat layer. In the present invention, workability is further improved by applying a material excellent in peelability to the mold. In this embodiment, a peelable material (manufactured by Asahi Glass Co., Ltd., Saito) is applied to the mold and solidified.

Next, as shown in Fig. 21, a transparent electrode made of ITO (a mixture of indium oxide and tin oxide, thickness 1000Å) is formed on the obtained substrate. Further, an insulating layer SiO ₂ is formed thereon (not shown).

Comparative Example 2

The color filter B of the comparative example 2 is manufactured as follows.

Instead of the mold used in Example 9, by using a glass substrate having a smooth surface (manufactured by Corning Corp .: 7059) as a mold, a color filter having a smooth surface was obtained. Such a color filter can be used for STN-LCD and the like which require smoothness. 22 shows a measurement example of the surface shape of the color filter of this embodiment.

Example 10

The non-pixel portion is the same as in Example 9 except that the mold having conical projections in the pixel portion is used, and the non-pixel portion is flat and the color filter C having the recessed portion in the pixel portion is obtained (Fig. 23).

Comparative Example 3

The conventional color filter D shown in Fig. 24 (where the pixel portion is flat and has a recess in the non-pixel portion (BM portion)) is used.

Example 11

A photosensitive resist (V-259PA, manufactured by Shin-Ilchul Chemical Co., Ltd.) used in Example 8 was used as the photocurable overcoat agent, and the same as in Example 9 except that the overcoat agent was cured by irradiating ultraviolet light by pressing a predetermined mold. The color filter E is manufactured.

Example 12

The color filter E of Example 12 was manufactured as follows.

The same as in Example 9 except that the overcoat agent (a solution of a predetermined concentration of polyphenylene oxide (PPO)) was applied and the overcoat layer was plasticized under pressure by pressing a predetermined mold and then solidified by cooling. To prepare the color filter (F).

On the other hand, TFT substrate G is manufactured as follows. A resist wall is formed on the periphery of the pixel using a resist material (OMR83: manufactured by Tokyo Chemical Co., Ltd.) on the substrate on which the TFT is formed. In this resist wall, beads are embedded so that the surface thereof does not protrude out of the resist so as to keep the cell thickness constant.

A substrate having the color filters (A), (C) and (E) obtained in Example 9-11, the color filter (D) obtained in Comparative Example 3, or the color filter (F) obtained in this example, and a TFT The substrate G is attached. Table 1 shows a combination of a substrate including a color filter and a TFT substrate.

TABLE 1

Next, between the five sets of attached substrates, the following mixture is injected to prepare five sets of liquid crystal cells: 0.1 g of R-684 (manufactured by Nippon Kayaku Co., Ltd.), 0.1 g of p-phenylstyrene, and the following formula (I). 10.06 g of the compound represented by the above), 3.74 g of a liquid crystal material ZLI-4792 (manufactured by Merck, Inc .: 0.4 wt%), and 0.02 g of a photopolymerization initiator (Irgacure 651).

Next, the cell is irradiated with ultraviolet rays, and the pixel region is shielded from the ultraviolet rays, and the injection hole is sealed with the photocurable resin.

Observing the thus obtained liquid crystal cell, it is observed that the axisymmetric alignment of the liquid crystal molecules is observed in the liquid crystal cell using the color filter of Example 9-12. However, in the liquid crystal cell using the color filter of Comparative Example 3, a random alignment state without axis symmetry is observed.

In addition, ultraviolet rays are irradiated for 30 minutes at an intensity of 2 mW / cm 2 by a high-pressure mercury lamp on the TFT substrate side to cure the resin.

When the liquid crystal cell manufactured as described above is observed with a polarization microscope, in the liquid crystal cell using the color filter of Example 9-12, the positions of the alignment axes of all sections are completely controlled as shown in FIG. That is, the alignment axis of axisymmetrical alignment in a pixel is not largely displaced, and roughness is not observed. However, in the liquid crystal cell using the color filter of the comparative example 3, there is no pixel in which axisymmetric orientation was demonstrated, and considerable roughness is shown. In particular, in the halftone state, considerable roughness is observed from the inclination angle.

Thus, when using a color filter having recesses as in the color filter of Example 9-12, by injecting a mixture of a liquid crystal material and a polymerized material (photocurable monomer), the axisymmetrical alignment is automatically performed without the need for voltage application. The state is obtained.

Further, in addition to the operation described in this embodiment, by performing an operation for obtaining a normal axis symmetry, a better axis symmetry can be obtained. For example, in addition to the operations described in this embodiment, better axisymmetric orientation can be obtained by heating the liquid crystal cell to a temperature at which the mixture exhibits an isotropic phase after the injection of the mixture, or by applying a predetermined voltage to the liquid crystal cell. have. The mechanisms, advantages, and problems of normal operation for obtaining a conventional axisymmetric orientation will be described in detail below.

When the mixture is heated to a temperature representing an isotropic phase (in which the mixture is thermally transferred from the liquid crystal phase to the isotropic phase), as shown in FIG. 26, the liquid crystal phase 19 is surrounded by the isotropic phase 18. This remains in the center of the pixel. When the operation for obtaining the axis symmetry is performed in this state, it is preferable that the axis of the axis symmetry alignment moves to the center of the pixel because it is most thermodynamically stable that the axis of the axis symmetry alignment becomes the center of the liquid crystal region. When cooled in this state, the liquid crystal region grows with the axis located at the center of the pixel, whereby the axis of axisymmetric alignment is easily arranged in the center of the pixel. As described above, in the operation for obtaining the normal axis symmetry, the position of the axis symmetry alignment axis can be positioned near the center portion, but it is difficult to precisely control the position of the axis. For this reason, in order to precisely control the position of the axis | shaft of an axisymmetric orientation to a predetermined position, a singular point is needed. Therefore, it is quite effective to manufacture the recessed portion at the predetermined position of the pixel center portion.

Example 13

As a fourth method, the case where the recess is formed in the color filter will be described. The method of this embodiment includes a step of forming a color filter color by photolithography technique using a color resist. In this step, the light resist is irradiated through the photomask so as not to harden the portion corresponding to the pixel center portion of the color resist, thereby forming a V-shaped recess for forming a predetermined recessed portion in the pixel center portion of the colored layer. do. With reference to FIGS. 27A-27D, the method of forming a recess is demonstrated. For comparison, FIG. 28 shows a mask used in a conventional manufacturing process.

First, as shown in Fig. 27A, a colored layer is formed on a substrate using a color resist. Next, as shown in FIG. 27B, light irradiation is performed through a photomask to form a V-shaped recess on the colored layer. In the case where a positive resist is used for the colored layer, the portion of the photomask corresponding to the outside of the pixel and the center of the pixel (the portion for forming the V-shaped recess) becomes the light receiving portion, and the other portion is the light shielding portion. Used. On the other hand, when a negative resist is used for the colored layer, a portion corresponding to the outside of the pixel and the center of the pixel is used as the light shielding portion, and the other portion is used as the light receiving portion. Such a photomask is applied to a film adhesion method, a color resist method, and the like.

The shape of the portion corresponding to the pixel center portion (the portion for forming the V-shaped recess) of the photomask is not particularly limited, and various types of shapes are employed. Preferably, the shape of the portion is a circle or a shape close to a circle (for example, a polygon such as a hexagon or an octagon whose angle is not sharp) or the like. As for the size of the part, for example, when the shape is almost circular, its maximum hole is preferably 10 µm or less. If the size is larger than 10 mu m, there is a fear that the color purity is lowered because the recess penetrates through the colored layer and light passes through the colored layer. In the case of using such a photomask, a photomask can be provided close to the colored layer to match the size of the recess and the shape of the hole with the portion of the photomask corresponding to the pixel center portion. It is preferable that the depth of the recess does not penetrate the colored layer and is formed in a dimension smaller than the thickness of the colored layer.

Next, as shown in Fig. 27C, BM is formed as a light shielding layer. The BM is formed so that its surface is higher than the colored layer. In order to form BM in such a state, it is preferable to use organic materials, such as black resist, as a material of BM. You may form any of BM and a colored layer first. In the case of forming the BM after the colored layer is formed, the number of the photomasks can be reduced by forming the BM by the back exposure method using the first formed colored layer as a mask.

Next, as shown in FIG. 27D, an overcoat agent is applied to form an overcoat layer having recesses, and the contained solvent is removed as necessary. Subsequently, a transparent electrode is formed on the overcoat layer. If necessary, an insulating layer is formed. The overcoat layer is as described above.

It is preferable that the shape of the overcoat layer formed in this way is higher in the portion above BM than in the portion above the colored layer, and the upper portion of the recess formed in the colored layer corresponds to the bowl-shaped lower portion. The lower part acts as a singularity.

According to the conventional method using the photomask shown in FIG. 28, two processes of forming a colored layer and forming a recess thereon are required. On the other hand, in this Example, formation of a colored layer and formation of a recess can be performed simultaneously. Therefore, by using a photomask having a desired shape without increasing the number of steps, a desired cross-sectional recess can be obtained, whereby the method of this embodiment has high industrial use value.

The present invention provides a structure necessary for precisely positioning the alignment axis of one axisymmetric alignment, and is not intended to form one axisymmetric alignment in one pixel. That is, as in the eighth embodiment, a plurality of axisymmetric alignments may be formed in one pixel of the substrate, and a plurality of axisymmetric alignments may be formed in one pixel of the color filter. In this case, the photomask for forming the colored layer must use a light shielding part and a light receiving part to form a plurality of recesses in one pixel.

Example 14

Example 13 will be described in more detail.

Color layers of R, G, and B are formed on the glass substrate (1.1 mm thickness) by using negative color resists (CG2000, CR2000, CB2000: manufactured by Fuji Hunt Electronics Technology Co., Ltd.) corresponding to each pixel. When the colored layer is formed, the photomask has a light shielding portion at the non-pixel portion and the pixel center portion, and a photomask having a diameter of 5 mu m is used for the light shielding portion at the pixel center portion. The recess of a V-shaped cross section is formed in the upper part of the colored layer obtained in this way.

Next, BM is formed in a non-pixel portion on the substrate by using a negative black resist (CKS142: manufactured by Fuji Hunt Electronics Co., Ltd.). The BM is formed to be 0.4 µm higher than the colored layer.

An overcoat agent (V259PA: manufactured by Shin-Ilchul Chemical Co., Ltd.) is applied onto the substrate on which the colored layer and the BM are formed. Next, a transparent electrode having a thickness of 1000 m 3 was formed thereon of ITO (a mixture of indium oxide and tin oxide). Thus, the board | substrate with a color filter which has recessed part is manufactured.

On the other hand, the counter substrate is manufactured as follows. On the glass substrate, a resist wall is formed around the pixel with a resist material (OMR83: manufactured by Tokyo Co., Ltd.). In the resist wall, beads for keeping the cell thickness constant are embedded so that the bead surface does not come out of the resist wall.

A liquid crystal cell was prepared by adhering the opposite substrate to the substrate having the color filter and injecting the following mixture between the attached substrates: 0.1 g of R-684 (manufactured by Nippon Kayaku); 0.1 g p-phenylstyrene; 0.06 g of the compound represented by the following formula (I); 3.74 g of liquid crystal material ZLI-4792 (manufactured by Merck, containing 0.4 wt% of S-811); 0.02 g photopolymerization initiator (Irgacure 651).

Next, a predetermined temperature operation and a voltage operation are performed on the mixture in the cell to form an axisymmetric alignment state. Further, the mixture is cooled to a temperature at which the liquid crystal phase is diffused to the entire region of the pixel, and then irradiated with ultraviolet light of 3 mW / cm 2 for 40 minutes under a high pressure mercury lamp to cure the resin.

Example 15

A liquid crystal cell was produced in the same manner as in Example 14 except that the photomask having the diameter of the light blocking portion of the pixel center portion was 10 mu m.

[Comparative Example 4]

A liquid crystal cell was produced in the same manner as in Example 14 except that a photo mask having no light shielding portion was used in the pixel center portion.

[Comparative Example 5]

A liquid crystal cell was produced in the same manner as in Example 14 except that a photomask having a diameter of the light shielding portion of the pixel center portion of 12 mu m was used.

Comparative Example 6

A liquid crystal cell was produced in the same manner as in Example 14 except that a photomask having a diameter of the light shielding portion of the pixel center portion of 15 µm was used.

The liquid crystal cells of Examples 14 and 15 and Comparative Examples 4-6 were observed with a polarizing microscope. As a result, in the liquid crystal cells of Examples 14 and 15, the axial position with respect to all the pixels is completely controlled, and the pixel in which the orientation axis of axial symmetry is largely displaced is not observed. On the other hand, in the liquid crystal cell of the comparative example 4, the axis position of axisymmetric orientation was not controlled, and considerable roughness was observed in the display. In addition, in the liquid crystal cells of Comparative Examples 5 and 6, recesses in the central pixel portion penetrate the colored layer, thereby decreasing color purity.

In this way, according to the fourteenth embodiments and the fifteenth embodiments, it is possible to precisely control the position of the axes in the axisymmetric orientation. As a result, the roughness observed when changing the vision can be reduced, and it is possible to provide the liquid crystal display device of the wide viewing mode with high contrast uniformly. Such a liquid crystal display device can be simply manufactured without increasing the conventional manufacturing process, so the cost ratio performance is very excellent.

The shape of the recess formed in the color filter is obtained in the shape as described above for the substrate. Thus, for example, the shapes shown in FIGS. 29A, 29B, 30A, and 30B are included. Moreover, also in the formation method of a recessed part, it is obtained by the method as mentioned above with respect to a board | substrate. For example, in Example 14, the fourth method is shown. In FIGS. 29A, 29B, 30A, and 30B, the second method is shown, but the first method and the third method may also be used.

The cross-sectional shape of the recess is described in detail. 29A and 29B show the case where the sign of the second derivative of the curved line denoting the main part in the vertical section through the lowermost part is denied. 30A and 30B show a case in which the quadratic derivative has a positive part and a negative part in the outlined curve defining the main part in the vertical section through the lowermost part. In order to form the recessed portion shown in Fig. 29B, for example, as shown in Fig. 29A, it is preferable to lower the height of the top of the stepped convex portion. On the other hand, in order to form the recessed part shown in FIG. 30B, as shown, for example in FIG.

FIG. 31 shows a cell manufactured by using a substrate having recesses shown in FIG. 29B on one side and a substrate having a resist convex portion used for phase separation of a liquid crystal and a photocurable resin on top of a transparent electrode as the other substrate. Is a cross-sectional view schematically.

In the cells thus produced, as in each of the embodiments described above, the axis position of the axisymmetrical alignment is precisely controlled to obtain a favorable alignment state without roughness or contrast.

29A, 29B, 30A, and 30B show the case where the sign of the second derivative is denied, and both cases of the government are included, but the present invention is not limited thereto and is applicable to the case where the sign of the second derivative is positive and zero. Can be.

In addition, as in the case described above, of course, in addition to the operations described in Levels 4 and 15, by performing an operation for obtaining an ordinary axisymmetric alignment, a better axisymmetric alignment can be obtained. For example, in addition to the operations described in Levels 4 and 15, after the mixture is injected, by heating the liquid crystal cell containing the mixture to a temperature at which the mixture exhibits an isotropic phase, or by applying a predetermined voltage to the liquid crystal cell, Axisymmetric orientation is obtained.

As described above, according to the present invention, the axis position of the axisymmetric alignment is precisely controlled to obtain a liquid crystal display element in a uniform display state without roughness. Further, since the axisymmetric orientation can be formed without applying a voltage, the cost can be greatly reduced in industrial production.

The above-mentioned liquid crystal display element is used for flat panel displays, such as a personal computer, a word processor, amusement equipment, a television set, etc., and is applied to a display board, a window, a door, a wall, etc. using a shuttering effect.

Those skilled in the art will be able to readily make various modifications without departing from the scope and spirit of the invention. Accordingly, the scope of the appended claims should not be limited to what is described herein, but rather should be construed broadly.

Claims (28)

A display medium containing at least liquid crystal between at least one pair of transparent substrates, At least one substrate of the pair of substrates includes a film having recesses on the display medium side, and the recesses have a bottom portion near the center of the recessed portion seen in the normal direction of the substrate, and the liquid crystal molecules contained in the display medium. Is axially symmetrical with respect to the bottom vicinity as an axis. The method of claim 1, The contour defining the recessed portion in the vertical plane through the bottom portion is a curve, and the sign of the second derivative of the curve is positive. The method of claim 1, A liquid crystal display device characterized in that the outline defining the recessed portion in the vertical plane through the bottom portion is a straight line. The method of claim 1, A contour defining the recessed portion in the vertical plane through the bottom portion is a curve, and the sign of the second derivative of the curve is negative. The method of claim 1, A contour defining the recess in the vertical plane through the bottom is a curve, and the curve is a portion where the second derivative of the curve is positive and the second derivative of the curve is negative. A liquid crystal display device having a portion. The method of claim 1, The board | substrate with a film | membrane which has the said recessed part, and the board | substrate with a film | membrane which have an iron part are arrange | positioned so that the bottom part of the said recessed part and the upper part of the said iron part may correspond, And the liquid crystal molecules contained in the display medium are axially symmetrical with the bottom and the top or the vicinity thereof as axes. The method of claim 1, And the display medium includes a liquid crystal region mainly comprising a liquid crystal and a polymer region surrounding the liquid crystal region. The method of claim 7, wherein The recess is formed by maximizing a cell gap at the center of the liquid crystal region and minimizing a cell gap at the end of the liquid crystal region, wherein an axisymmetric alignment axis of the liquid crystal molecules is located at the center of the liquid crystal region. Liquid crystal display device. The method of claim 7, wherein And the inclination of the surface of the film having the recess portion is continuously changed at the boundary between the pixel portion where the liquid crystal region exists and the non-pixel. The method of claim 1, A liquid crystal display device characterized in that the film having the recess is formed of a thermoplastic insulating material or a thermosetting insulating material. The method of claim 1, A film having the recessed portion is formed of a photosensitive insulating material. The method of claim 1, A transparent electrode is formed on a substrate having a film having the recessed portion. Forming a film for forming recesses in at least one of the pair of substrates; And And pressing the film with a mold having a predetermined concave-convex surface to form recesses having a predetermined shape at predetermined positions of the film. The method of claim 13, The uneven surface of the mold has a conical or elliptical cone, characterized in that the manufacturing method of the liquid crystal display device. Stacking a plurality of films on at least one of the pair of substrates so as to have a circular or elliptical shape in a normal direction of the substrate and having a larger area as the film closer to the substrate, thereby forming a convex portion whose periphery is stepped; And Forming a film to cover the convex portion to form a recess having a smooth surface and having a bottom portion between adjacent convex portions. Forming a film made of a photosensitive material on at least one of the pair of substrates; And And forming a recess in the film by exposing the film for patterning through a gradation mask in which light transmittance is changed gradationally. The method of claim 13, Injecting a mixture of a liquid crystal and a photopolymerizable compound between the pair of substrates; And And irradiating the mixture with ultraviolet rays to cure the photopolymerizable compound. The method of claim 1, And a color filter comprising a colored layer, a light shielding layer, and an overcoat layer covering the colored layer and the light shielding layer, wherein the recess is formed in the color filter. The method of claim 18, And the recessed portion is provided corresponding to the pixel portion, and a part of the color filter corresponding to the non-pixel portion is flat. The method of claim 18, And a transparent electrode is formed on the overcoat layer. The method of claim 18, The overcoat layer is formed of a material selected from the group consisting of a thermoplastic resin, a thermosetting resin and a photocurable resin. The method of claim 18, The colored layer has a recess formed by photolithography using a color resist and having an opening having a diameter of 10 μm or less, wherein the light shielding layer is formed higher than the colored layer, and the overcoat layer is an inorganic material or an organic material. Liquid crystal display device characterized in that formed. Forming a color filter and a light shielding layer at a predetermined position on the substrate, and then forming an overcoat layer covering the color layer and the light shielding layer to form a color filter; And And pressing the overcoat layer with a mold having a predetermined uneven surface to form recesses having a predetermined shape at predetermined positions of the overcoat layer. The method of claim 23, The overcoat layer is coated with an overcoat agent, and then formed by removing the solvent contained in the overcoat agent. The method of claim 23, And the mold has a convex portion or a projection at a position corresponding to the pixel. The method of claim 23, And the mold has a flat surface on a part thereof. Forming a colored layer of a color filter by photolithography using a color resist, and performing light irradiation through a photomask so as not to harden a portion corresponding to the pixel center portion of the color resist, wherein the colored layer Forming a recess for forming a predetermined recess in a pixel center portion of the liquid crystal display device. The method of claim 27, The recess of the recess portion has a diameter of 10 µm or less.