JP2000029007A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent liquid crystal display from being adversely affected even at the time of bringing components of the device into contact with a low- voltage-driven liquid crystal having strong dissolving power by forming a transparent protective layer(s) on colored layers of a color filter and using specific nematic liquid crystal. SOLUTION: In order to give colors to a liquid crystal display element, plural colored layers are formed on a substrate. Each of the colored layers is formed by patterning a resin contg. coloring materials, and as the coloring material, a pigment or dye is used. As the liquid crystal, although there is no special limitation other than that it be a nematic liquid crystal, fluorine-based liquid crystal is preferably used on account of its high voltage retention, excellent display characteristics, etc., wherein it is important that the saturation voltage is <=2V. By using liquid crystal having a <=2V saturation voltage value, nonuiformity in liquid crystal display is liable to occur even at the time of reducing a residual or residual film by intensifying the washing, or controlling the film quality of transparent electrically conductive film, however, by forming transparent protective film on the colored layers, or on the colored layers and a black matrix layer, this problem can be solved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which display unevenness hardly occurs.

[0002]

2. Description of the Related Art A color filter in which pixels of three colors R (red), G (green), and B (blue) are arranged in a line or mosaic on a transparent substrate to color a liquid crystal display device. Is used. For example, a TFT (thin film transistor) color liquid crystal display element that is widely used at present is composed of a transparent glass substrate on which a color filter is formed and a TFT.
It is composed of a panel in which liquid crystal is sealed between transparent glass substrates on which FT is formed, and a light source called a backlight. When light emitted from the backlight passes through the liquid crystal panel,
An image is displayed by controlling the transmittance by a voltage applied to the liquid crystal. Since each pixel needs to be similar to the chromaticity characteristics of the CRT phosphor, the pigments are selected to match the light transmission characteristics of the backlight and the liquid crystal display element, and two or more pigments are toned at a fixed ratio. Often used. For example, for the R (red) pixel of the color filter, two or more kinds of red, orange, and yellow pigments are selected and used at a fixed ratio. Similarly, the G (green) pixel is
Two or more kinds of green, orange, and yellow pigments are selected and toned. The pigment is selected in consideration of such required chromaticity characteristics, and ionic impurities are not considered. Generally, commercially available pigments generally contain many inorganic and organic ionic impurities including alkali metals such as sodium, potassium, calcium and barium. When these ionic impurities elute into the liquid crystal, they affect the alignment of the liquid crystal, causing display unevenness of the liquid crystal display element.

[0003] The liquid crystal display element is lightweight and thin, so that it is suitable for portable equipment such as a notebook computer. In portable equipment, reduction of power consumption is an important issue, and in liquid crystal display elements, a reduction in driving voltage of liquid crystal display elements is required. Further, a reduction in the driving voltage of the liquid crystal display element leads to a reduction in the size of the semiconductor device that drives the liquid crystal display element, and is effective in reducing the cost of the semiconductor device. The reduction in the liquid crystal drive voltage is also effective in reducing electromagnetic noise.

[0004] A lower driving voltage of a liquid crystal display element is achieved mainly by improving the physical properties of liquid crystal. That is, the improvement is made in the direction of increasing the dielectric constant difference between the major axis direction and the uniaxial direction of the liquid crystal molecules, but the absolute value of the dielectric constant in the major axis direction increases in order to increase the dielectric constant difference. Generally, a solvent having a large dielectric constant has a large dissolving power, and it is easy to dissolve impurities harmful to the liquid crystal display from a material in contact with the liquid crystal. The same applies to color filters, and particularly, elution of impurities from pigments is a problem.

A transparent protective layer is sometimes formed between a colored layer of a color filter and a transparent conductive film for the purpose of improving flatness and the like. When a color liquid crystal display device was commercialized, this transparent protective film was formed on almost all products.However, flattening was achieved without relying on the transparent protective layer. A technology that does not cause disturbance has been developed, and in recent years, in many cases, the transparent protective film has been omitted to reduce costs.

In the liquid crystal currently used, there is no problem due to the absence of the transparent protective film. However, as the driving voltage of the liquid crystal display element is reduced, the problem due to the absence of the transparent protective film is likely to occur. This has been clarified by the study of the present inventors.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a liquid crystal display having an adverse effect even when in contact with a low-voltage driven liquid crystal having strong dissolving power. An object of the present invention is to provide a liquid crystal display element having a structure that does not affect the above.

[0008]

The object of the present invention is achieved by the following constitution.

1) A liquid crystal display device provided with a color filter in which a plurality of coloring layers are arranged on a substrate, wherein a transparent protective layer is provided on the coloring layer of the color filter, and the saturation voltage is 2V. A liquid crystal display device comprising the following nematic liquid crystal.

(2) The liquid crystal display element according to (1), wherein a nematic liquid crystal having a saturation voltage of 1.8 V or less is used as the nematic liquid crystal.

(3) The liquid crystal display device as described in (1), wherein the transparent protective layer is formed outside the liquid crystal display area.

(4) The liquid crystal display device according to (1), wherein the transparent protective layer is at least one of an acrylic resin, an epoxy resin, a siloxane polymer, a silicone polyimide and a benzocyclobutene resin.

5) The thickness of the transparent protective layer is 0.03 μm.
The liquid crystal display element according to (1), wherein the thickness is from m to 3 μm.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a substrate used in the present invention, glass, plastic, metal and the like can be adopted, but glass is preferable in terms of heat resistance and dimensional stability. As the glass, non-alkali glass, low alkali glass, soda glass coated with a silica film or the like can be used. Examples of the plastic include resins having relatively high heat resistance, such as polyethylene terephthalate and polycarbonate. The thickness of the substrate ranges from 0.3 mm to 2 mm. Treatment of the substrate with an adhesion aid such as a silane coupling agent is appropriately permitted.

A color liquid crystal display device is manufactured by sandwiching a liquid crystal between at least two transparent substrates. Wirings and elements for driving the liquid crystal are formed on the substrate, and a plurality of coloring layers for coloring are arranged.

In active matrix driving,
A transistor or a diode is formed for each pixel, and a wiring and a pixel electrode connecting these active elements and a circuit of the liquid crystal display element are formed. As an active element,
A TFT (thin film transistor) using an amorphous silicon film or a polysilicon film as a channel layer, a TFD (thin film diode) including a metal film with an insulating film interposed therebetween, and the like are employed. When the active element is a TFT, the wiring connecting the active element and the circuit outside the liquid crystal display element includes a gate electrode wiring and a data electrode wiring, and is formed by patterning a thin film made of chromium, tantalum, aluminum, molybdenum, or an alloy thereof. It is formed. As the pixel electrode, an ITO thin film, which is a transparent conductive film, is used in a transmissive liquid crystal display device, and an aluminum thin film or a silver thin film having a high reflectance is used in a reflective liquid crystal display device.

In the passive matrix driving, parallel wirings are formed on a substrate, and the two substrates are bonded so that these wirings are orthogonal to each other. In a transmission type liquid crystal display element, wiring is formed by an ITO thin film which is a transparent conductive film. In a reflection type liquid crystal display element, an aluminum thin film or a silver thin film having high reflectivity is adopted for wiring on one substrate.

A plurality of colored layers formed on a substrate are used to color a liquid crystal display device. In order to realize a full-color liquid crystal display device, R (red), B (blue), G
A colored layer having three primary colors of (green) or M (magenta), C (cyan), and Y (yellow) is used. In the case of multicolor, a combination of colored layers having a complementary color relationship such as red and magenta is also possible. Further, a black matrix may be formed between the colored layers in order to improve contrast and prevent color mixing of the colored layers. These colored layers and black matrix are arranged corresponding to the pixels.

The coloring layer is formed by patterning a resin to which a dye is added. Pigments include pigments and dyes.
A method of patterning a resin in which a pigment or a dye is dispersed is referred to as a pigment dispersion method or a dye dispersion method, and the most important role of the resin is to disperse and hold the pigment or the dye.
The resin of the present invention has no particular problem as long as it is a resin that is usually used for a color filter paste. For example, acrylic resin, alkyd resin, melamine resin, polyvinyl alcohol, phenol resin, polyamide, polyamide imide, polyimide and the like can be used. When patterning a resin containing a pigment or a dye, it is preferable from an industrial viewpoint that an aqueous alkaline solution can be used instead of an organic solvent. Further, the resin may have photosensitivity itself, or may be non-photosensitive which is patterned by using a separate photoresist. Among the resins that can be patterned with an alkaline aqueous solution, a resin having a carboxyl group is preferably used, and specific examples include an acrylic resin and a polyimide. Among them, polyimide is excellent in solvent resistance. Polyimide is also excellent in that polyimide precursors function as a dispersant for the pigment. Further, from the viewpoint of heat resistance of the color filter, it is preferable to use polyimide.

The present invention is also effective for a so-called dyeing method in which a resin layer called a receiving layer is dyed corresponding to pixels. Patterning in the dyeing method includes a method of providing a stain-resistant layer to determine a dyed portion, and a method of selecting a dye supply position using an inkjet or the like. An acrylic resin or the like can be used as the receiving layer.

In the present invention, the term "polyimide precursor" refers to a polyamic acid or a product obtained by esterifying a part thereof. Polyimide precursor, by heat or chemical treatment,
Form an imide ring. The polyamic acid referred to here is represented by the following general formula (1).

[0022]

Embedded image Here, R ₁ is a tetravalent organic group having 2 to 22 carbon atoms, R _{2 is a} divalent organic group having 1 to 22 carbon atoms, and n is 1 and / or 2
And a polymer having a weight average molecular weight of at least 2,000.

The polyamic acid can be obtained by reacting a tetracarboxylic dianhydride with a diamine. As the tetracarboxylic dianhydride, for example, aliphatic or alicyclic ones can be used, and specific examples thereof include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,5-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-bicyclohexenetetracarboxylic dianhydride, 1,2,
4,5-cyclohexanetetracarboxylic dianhydride,
1,3,3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-C] furan-1,3-dione and the like. When an aromatic compound is used, a polyimide precursor composition that can be converted into a polyimide having good heat resistance can be obtained.
4'-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride Anhydride, 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3, 3 ', 4,4'-
Paraterphenyltetracarboxylic dianhydride, 3,3
', 4,4'-metaphenylphenyltetracarboxylic dianhydride. Also, if a fluorine-based material is used,
A polyimide precursor composition which can be converted into a polyimide having good transparency in a short wavelength region can be obtained, and specific examples thereof include 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride and the like. Is mentioned. The present invention is not limited to these, and one or more tetracarboxylic dianhydrides are used.

In the present invention, for example, aliphatic or alicyclic diamines can be used as the diamine, and specific examples thereof include ethylenediamine, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane,
4,4'-diamino-3,3'-dimethyldicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexyl and the like can be mentioned. When an aromatic compound is used, a polyimide precursor composition that can be converted into a polyimide having good heat resistance can be obtained. Specific examples thereof include 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether. '-Diaminodiphenyl ether, 4,4'
-Diaminodiphenylmethane, 4,4'-diaminobenzanilide, 3,3'-diaminodiphenylmethane,
4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,5-
Diaminotoluene, 2,6-diaminotoluene, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, o-tolidine, 4,4 ″ -diaminoterphenyl, 1,5-diaminonaphthalene, 3, 3 '
-Dimethyl-4,4'-diaminodiphenylmethane,
4,4'-bis (4-aminophenoxy) biphenyl,
2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [ 4- (3-aminophenoxy) phenyl] sulfone and the like. Also,
When a fluorine-based material is used, a polyimide precursor composition that can be converted into a polyimide having good transparency in a short wavelength region can be obtained. As a specific example, 2,2-bis [4- ( 4-aminophenoxy) phenyl] hexafluoropropane and the like.

When siloxane diamine represented by bis-3- (aminopropyl) tetramethylsiloxane is used, the adhesion to an inorganic substrate can be improved. Siloxane diamine is usually 1 to 1 in all diamines.
Used in an amount of 20 mol%. If the amount of siloxane diamine is too small, the effect of improving the adhesiveness will not be exhibited, and if it is too large, the heat resistance will decrease. The present invention is not limited to these, and one or more diamines are used.

The synthesis of polyamic acid is generally carried out by reacting a diamine with a tetracarboxylic dianhydride in a polar organic solvent. At this time, the degree of polymerization of the obtained polyamic acid can be controlled by the mixing ratio of the diamine and the tetracarboxylic dianhydride. In addition, the present invention is also applicable to derivatives such as the above-mentioned esterified products of polyamic acid. Amide polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide and N, N-dimethylformamide are used as the solvent. Polyamic acid is preferably synthesized in a solvent containing lactones as a main component or lactones alone in order to enhance the dispersing effect of the pigment. Here, the solvent containing a lactone as a main component or a lactone alone means that the lactone is contained in 50% by weight or more. Examples of the solvent other than the lactones include methyl cellosolve, ethyl cellosolve, methyl carbitol, ethyl carbitol and the like in addition to the amide-based polar solvent.

Lactones are aliphatic cyclic esters having 3 to 12 carbon atoms. As specific examples, β-propiolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-
Examples include, but are not limited to, caprolactone. Particularly, γ-butyrolactone is preferred in view of the solubility of polyamic acid.

As the dye used in the colored layer prepared by the pigment dispersion method of the present invention, an organic pigment can be suitably used. Examples of the pigment used include Pigment Red 9, 97, 122, 123, 149 and 16 as red.
8, 177, 180, 192, 215 and the like are generally used as pigment greens 7, 36 and the like as green, and as blue, pigment blue 15, 22, 60, 64 and the like are generally used. Addition of a yellow pigment or the like to adjust the color tone of green or red is appropriately permitted. Examples of yellow pigments include Pigment Yellow 13, 17, 20, 24, 83, 86, and 9
3, 95, 109, 110, 117, 125, 129,
137, 138, 139, 147, 148, 153, 1
54, 166, 168, 185, etc., but are not limited thereto.

In general, an additive for pigmentation and for improving dispersibility is added to the pigment product in addition to the pigment itself. Further, a surface treatment such as a rosin treatment, an acidic group treatment, and a basic treatment is performed. Further, impurities generated in the pigment manufacturing process are also included. Among these additives or impurities, those containing chlorine or bromine are easily dissolved in the liquid crystal and tend to cause display unevenness of the liquid crystal display element. In particular, ionic organic chlorine compounds and organic bromine compounds having a molecular weight of about several tens to 1,000 have a strong dissolving power in liquid crystal, and because of their large molecular weight, diffusion after ionization is slow, so that display unevenness is likely to become apparent. The green pigment is obtained by chlorinating or chlorinating / brominating copper phthalocyanine, and the effect of the present invention is particularly large because impurities harmful to the liquid crystal are easily generated in the production process. Some yellow pigments and red pigments also contain chlorine, and the effect of the present invention is great. Although blue pigment does not use chlorine in the manufacturing process, chlorine may be mixed as an impurity.

Green is a dye obtained by chlorinating or chlorinating or chlorinating copper phthalocyanine as the dye used in the dye dispersion method or the dyeing method. The present invention has the same effect as the pigment dispersion method. In the case of red, yellow and blue containing chlorine, impurities and dyes are easily dissolved in the liquid crystal, and the present invention is effective.

The colored layer of the present invention is mainly composed of a resin and a dye, and is manufactured in a range of resin: dye = 3: 7 to 8: 2 (weight ratio). In addition to the resin and the dye, a surfactant for improving dispersibility and coatability, and inorganic particles such as barium sulfate for adjusting hue and hardness may be added. The thickness of the coloring layer is 0.5
The range is from μm to 3 μm. When a gap control column is formed by color superposition, a colored layer having a thickness of 1.5 μm to 3 μm thicker than usual is used. If the thickness of the coloring layer is less than 0.5 μm, the coloring density is not sufficient, and if the thickness of the coloring layer is more than 3 μm, the flatness is impaired and the alignment of the liquid crystal is disturbed.

The black matrix disposed between the colored layers includes a black matrix composed of an inorganic thin film such as chromium and a black matrix composed of a resin layer composed of a black pigment and a resin. In the case of an inorganic thin film, it is effective to laminate chromium oxide and chromium or to continuously change the degree of oxidation of chromium in order to reduce the reflectance. Resin black matrices have been increasingly used because of their low reflectivity and environmental friendliness without using heavy metals. The resin black matrix is formed by dispersing a light shielding material in the same resin as the coloring layer. As the light-shielding agent, a mixture of carbon black, graphite, graphite, titanium oxide, titanium oxynitride, manganese oxide, and a pigment or dye such as blue, red, and purple can be adopted.
In order to adjust the color tone, a pigment or a dye is added to carbon black or the like. In addition, a black matrix of color superposition in which the transmittance is suppressed by superimposing colored layers can also be employed. These black pigments sometimes contain additives or impurities that are easily dissolved in the liquid crystal, and the present invention is effective. The thickness of the resin black matrix mainly composed of the resin and the light shielding agent is in the range of 0.5 μm to 3 μm. If the thickness is less than 0.5 μm, the light-shielding property is not sufficient,
If the thickness is larger than μm, the flatness is impaired, which causes disturbance of liquid crystal alignment.

The transparent protective layer of the present invention is provided on the colored layer or the colored layer and the black matrix layer. The transparent protective layer has an ability to planarize the surface of the color filter (planarization property), a substrate located under the transparent protective layer,
Coloring layer, adhesion to the black matrix, also to the transparent electrode located on the transparent protective layer, etc., adhesion to the sealant or sealing agent for constituting the liquid crystal cell, from the colored layer It has a wide range of properties, such as barrier properties of eluting substances, smoothness, light resistance, moisture and heat resistance, solvent resistance, chemical resistance, heat resistance, and pressure resistance and toughness in the substrate bonding process when manufacturing liquid crystal cells. Required.

Among these characteristics, when the saturation voltage of the nematic liquid crystal is low, it is important to have a high flatness of the surface of the color filter and to prevent elution of impurities from the color filter. Of particular importance are the flattening characteristics and the ability to block out elutes from the colored layer and the like.

As such a transparent protective layer, an acrylic resin, an epoxy-modified acrylic resin, an epoxy resin, a siloxane polymer, a silicone polyimide, a benzocyclobutene resin, or the like can be used, but from the viewpoint of excellent flattening characteristics. From, it is preferable to use an epoxy-modified acrylic resin or an epoxy resin, and
It is preferable to use a siloxane polymer or a silicone polyimide from the viewpoint of excellent blocking of pixel impurity components. In order to achieve both flattening characteristics and blocking properties of pixel impurities, it is preferable to use an epoxy-modified acrylic resin having a siloxane bond, an epoxy resin having a siloxane bond, and a benzocyclobutene resin having a siloxane bond.

The thickness of the transparent protective layer of the present invention is 0.02 μm.
To 3 μm. When the thickness is less than 0.02 μm, not only the effect of suppressing the elution from the colored layer or the black matrix layer to the liquid crystal is insufficient, but also the planarization is insufficient. When the transparent protective layer is thicker than 3 μm, it is good in terms of suppressing eluted substances, but bubbles are likely to remain during liquid crystal injection, and particles generated by drying the transparent protective layer reduce the production yield. It is not preferable because it lowers. The thickness of the transparent protective layer is more preferably in the range of 0.03 μm to 2 μm, and is preferably 0.04 μm.
Most preferably, it is in the range of m to 1.5 μm.

The transparent protective layer is formed in the display region of the liquid crystal display device on which the colored film and the black matrix are formed, but is preferably formed over the entire surface of the substrate including the outside of the display region. Although the coloring layer and the black matrix are present only in the display area, in a manufacturing process, unnecessary portions are generally removed after the coloring film and the black matrix layer are applied to the entire surface of the substrate. Unnecessary portions of the coloring layer and the black matrix layer are difficult to completely remove, and in many cases, a dye and a resin called a residue or a residual film remain. Through cleaning, alignment film coating, alignment film rubbing, and the like in a liquid crystal panel manufacturing process, a residue, a substance that dissolves in liquid crystal from the remaining film and causes display failure, may be transferred to a display region. Since the outside of the display region is not covered with the transparent conductive film, covering the outside of the display region with the transparent protective layer is particularly effective and preferable. However, during the glass cutting, particles are likely to be generated if the transparent protective layer is on the glass scribe line. Therefore, it is preferable that the transparent protective film is removed in a narrow region near the glass scribe line.

The present invention is effective even in the case of a so-called color filter on array in which the coloring layer is provided on the substrate side on which the liquid crystal driving element is formed. In the case of a color filter on array, a through hole for electrically connecting the transparent protective layer and the active element may be formed in the transparent protective layer in some cases. The through hole is formed by physical etching such as chemical etching or ion milling,
Since the chemical etching is excellent in terms of simplicity, it is desirable to use a resin soluble in an aqueous alkali solution for the transparent protective layer.

An electrode for driving a liquid crystal is formed on the transparent protective layer of the present invention. In the case of a transmissive liquid crystal display element, a transparent conductive film such as an ITO thin film is used for the electrodes. In the case of a reflective liquid crystal display device, a transparent conductive film or a thin film having a high reflectance is used depending on the structure. As the thin film having a high reflectance, an aluminum thin film or a silver thin film is preferable. Also,
When the liquid crystal driving element is a TFT and the coloring layer is formed on a different substrate from the liquid crystal driving element, the electrodes formed on the transparent protective layer may be continuous. When the driving element is a TFD, the electrodes on the transparent protective layer are patterned corresponding to the pixels even when the coloring layer is provided on a substrate on the other side of the liquid crystal driving element. When a colored layer is provided on the liquid crystal driving element side, the transparent electrode film or the thin film having a high reflectance on the transparent protective layer needs to be patterned corresponding to the pixel. In the case of matrix drive without a liquid crystal drive element, parallel wiring groups are formed by a transparent conductive film or a metal thin film having a high reflectance.
The transparent conductive film on the substrate opposite to the substrate on which the liquid crystal driving element is provided is usually just outside the display area in order to avoid a short circuit with wiring on the substrate on which the liquid crystal driving element is provided. It is formed only on a display portion inside a light-shielding portion called a frame.

The thickness of the transparent conductive film or the metal thin film is
The range is from 0.1 μm to 0.5 μm. When the thickness of the transparent conductive film or the metal thin film is smaller than 0.1 μm, the resistance value is not sufficiently low, and a time delay occurs in driving the liquid crystal and unevenness on a screen occurs. If the thickness of the transparent conductive film is larger than 0.5 μm, light transmittance, coloring and flatness are reduced, which is not preferable. If the thickness of the metal thin film is larger than 0.5 μm, the flatness is undesirably reduced.

The liquid crystal used in the liquid crystal display device of the present invention is a nematic liquid crystal. Liquid crystal alignment method is twisted nematic or electric field controlled birefringence (ECB)
The system can be adopted. In the twisted nematic method, when no voltage is applied to the liquid crystal driving electrode, the long axis alignment direction of the liquid crystal molecules is twisted by 90 ° between two substrates sandwiching the liquid crystal, that is, at the cell gap, and The polarizing directions of the polarizers arranged outside are orthogonally arranged corresponding to the major axis alignment of the liquid crystal molecules. This is a method in which the light transmittance is controlled by the long axis alignment of liquid crystal molecules rising in the direction perpendicular to the substrate surface in accordance with the application of a voltage to the liquid crystal drive electrode. In the ECB mode, when no voltage is applied to the liquid crystal drive electrode, the long axis of the liquid crystal molecules is parallel to the substrate surface, but is not twisted between the cell gaps. The polarizing directions of the polarizing plates outside the two substrates are arranged at a predetermined angle of 90 ° or less. In this method, the liquid crystal rises with respect to the substrate surface in accordance with the application of a voltage to the liquid crystal drive electrode to control the light transmittance. In the case of a reflective liquid crystal display device, a configuration in which only one polarizing plate on the side on which external light is incident is also possible.

The nematic liquid crystal of the present invention has a saturation voltage of 2 V
It is important that: The amount of light transmitted or reflected by the liquid crystal display element is measured. For a normally white mode liquid crystal display element, a sufficiently high voltage is applied by applying 100% of the amount of transmitted light or reflected light when no voltage is applied to the liquid crystal drive electrode. When the minimum transmitted light amount or the minimum reflected light amount at this time is set to 0%, the voltage applied to the liquid crystal drive electrode at the point where the transmitted light amount or the reflected light amount becomes 10% is defined as a saturation voltage. In a normally black mode liquid crystal display device, the amount of transmitted light or reflected light when no voltage is applied to the liquid crystal drive electrode is 0%, and the maximum transmitted light or reflected light when a sufficiently high voltage is applied is 100%. At this time, a voltage applied to the liquid crystal drive electrode at a point where the transmitted light amount or the reflected light amount becomes 90% is defined as a saturation voltage.

The lowering of the driving voltage of the liquid crystal display element is achieved mainly by improving the physical properties of the liquid crystal. That is, the improvement is made in the direction of increasing the dielectric constant difference between the major axis direction and the uniaxial direction of the liquid crystal molecules, but the absolute value of the dielectric constant in the major axis direction increases in order to increase the dielectric constant difference. Generally, a solvent having a large dielectric constant has a large dissolving power, and it is easy to dissolve impurities harmful to the liquid crystal display from a material in contact with the liquid crystal. The same applies to the coloring layer and the black matrix, and particularly, elution of impurities from the pigment is a problem. Many nematic liquid crystals used at present have a saturation voltage of 3.2 V to 3.5 V, and some liquid crystals have a saturation voltage of 2.1 V to 2.5 V. In the liquid crystal having a saturation voltage of 3.2 V to 3.5 V, the elution from the colored layer or the black matrix hardly caused the liquid crystal display unevenness. In the case of a liquid crystal having a saturation voltage of 2.1 V to 2.5 V, the remaining of the colored layer and the resin black matrix and the remaining film are reduced, and the quality of the transparent conductive film formed on these layers is increased. It was possible to prevent liquid crystal display unevenness. However, when a liquid crystal having a saturation voltage of 2 V or less is used, unevenness in the liquid crystal display is likely to occur due to fluctuations in production conditions even if the remaining film is reduced by controlling washing or the like and the film quality of the transparent conductive film is controlled. Was clarified by the study of the present inventors. That is, if the cleaning is strengthened, the colored layer portion and the transparent conductive film to be left are damaged, so that it is very difficult to completely remove the left and the remaining film, and a very small residue and the remaining film cause display failure. In order to elute a sufficient amount of impurities, the range in which the production conditions that can prevent liquid crystal display unevenness and the production conditions that satisfy other characteristics are compatible is narrow.
When the saturation voltage is 1.8 V or less, there is almost no range in which the production condition that can prevent the liquid crystal display unevenness and the production condition that satisfies other characteristics are compatible.

However, the above problem can be solved by providing the transparent protective film of the present invention.

Although the relationship between the saturation voltage of the liquid crystal and the relative permittivity has a certain range, the relative permittivity in the major axis direction of the liquid crystal having a saturation voltage of 3.2 V to 3.5 V is about 6.5. In a liquid crystal having a voltage of 2.1 V to 2.5 V, the relative dielectric constant in the major axis direction is about 9. When the liquid crystal has a saturation voltage of about 2 V, the relative dielectric constant in the major axis direction increases to about 13. If the saturation voltage is 1.
For a liquid crystal of about 8 V, the relative dielectric constant in the long axis direction is about 15.

The liquid crystal of the present invention is not particularly limited, except that it is a nematic liquid crystal. However, a fluorine-based liquid crystal is preferable in that it has a high voltage holding ratio, is excellent in display characteristics, and hardly contains water. The liquid crystal usually used for the liquid crystal display element is a mixture of about ten kinds of liquid crystals. In a liquid crystal having a low saturation voltage, the ratio of liquid crystal molecules having a large number of fluorine atoms at the ends of the liquid crystal molecules increases, and the number of fluorine atoms per liquid crystal molecule increases.

Hereinafter, an example of a method for manufacturing a liquid crystal display device of the present invention will be described, but the present invention is not limited thereto.

Polyimide is used as a resin component of the colored layer and the black matrix, and polyamic acid is used as a precursor thereof. A color paste composed of carbon black and polyamic acid is applied on a transparent substrate. As a method of applying the color paste on the substrate, a method of applying the substrate to the substrate by a spin coater, a bar coater, a blade coater, a roll coater, a die coater, a screen printing method, a method of immersing the substrate in the color paste, a method of color paste And various methods such as spraying on a substrate. After applying the color paste, air dry,
A polyimide precursor colored film is formed by semi-curing such as heat drying and vacuum drying. In the case of heat drying, use an oven, a hot plate, etc.,
The heat treatment is performed for seconds to 1 hour. Next, a positive photoresist is applied on the polyimide precursor colored film and dried to form a photoresist film. Subsequently, a photomask is placed on the photoresist film and irradiated with ultraviolet rays using an exposure device. After the exposure, the development of the photoresist film and the etching of the polyimide precursor coloring layer are simultaneously performed using an alkali developing solution. After the etching, the unnecessary photoresist film is stripped with a stripping solution. Thereafter, the polyimide precursor colored layer is converted into a polyimide colored layer by performing a heat treatment as a main cure. Heat treatment is usually
In air, nitrogen atmosphere, or vacuum, etc.
It is carried out continuously or stepwise at a temperature of 0 ° C. to 320 ° C. for 30 minutes to 2 hours. Thus, a resin black matrix is obtained.

On the substrate on which the resin black matrix is formed, a color paste composed of a green pigment and a yellow pigment and a polyamic acid is applied, and patterning is performed in the same manner as the black matrix to obtain a green colored layer. The coloring layer is disposed so as to fill the opening of the black matrix. Similarly, a blue coloring layer and a red coloring layer are formed.

After etching the colored layer, brush cleaning, U
Performing V cleaning and alkali cleaning has the effect of reducing the residue of the colored layer and the remaining film.

A transparent protective layer made of at least one of an acrylic resin, an epoxy resin, a siloxane polymer, a silicone polyimide and a benzocyclobutene resin is provided on the coloring layer. As a method of applying the transparent protective layer material on the substrate, a method of applying the material to the substrate by a spin coater, a bar coater, a blade coater, a roll coater, a die coater, a screen printing method, or the like, a method of dipping the substrate in a color paste A method similar to that for the coloring layer, such as spraying a color paste on a substrate, can be employed.
The transparent protective layer is applied on the entire surface of the substrate. If the acrylic resin is heated and dried in an oven, the temperature must be between 80 ° C and 180 ° C.
For 30 seconds to 1 hour at 200 ° C
Perform the present cure for 30 minutes to 2 hours at to 280 ° C.

On the transparent protective layer, a transparent conductive film of an ITO sputtered film is formed. The transparent conductive film is formed only in the display area and the surrounding area, which is a light-shielding part formed by a black matrix, up to a frame in order to prevent a short circuit with the substrate on which the liquid crystal driving element is formed. However, leads made of a transparent conductive film provided at the four corners of the display area for electrical connection with the liquid crystal drive element forming side substrate are usually formed beyond the frame.

Thus, a color filter substrate is obtained.

A chromium thin film is formed on a transparent substrate by a sputtering method. A positive photoresist is applied on the chromium thin film and dried to form a photoresist film. Subsequently, a photomask is placed on the photoresist film and irradiated with ultraviolet rays using an exposure device. After exposure, the photoresist film is developed with an alkaline developer. Next, the chromium thin film is etched with a chromium etchant to obtain a predetermined pattern including a gate electrode, a gate wiring, and an additional capacitor. After the chromium etching, the unnecessary photoresist film is stripped with a stripping solution. Plasma C on chromium thin film
A silicon nitride thin film and an amorphous silicon thin film are continuously formed by a VD method. A positive photoresist is applied on the amorphous silicon thin film and dried to form a photoresist film. Subsequently, a photomask is placed on the photoresist film and irradiated with ultraviolet rays using an exposure device. After exposure, the photoresist film is developed with an alkaline developer. Next, the amorphous silicon thin film and the silicon nitride thin film are etched by reactive ion etching to obtain a predetermined pattern. After reactive ion etching,
The unnecessary photoresist film is removed by ashing and a removing liquid. Next, a silicon nitride thin film is formed by a plasma CVD method. Patterning is performed using photoresist and reactive ion etching in the same manner as the amorphous silicon thin film so that the silicon nitride thin film remains in the channel portion of the transistor. An amorphous silicon thin film doped with boron is formed thereon and patterned using a photoresist and reactive ion etching to secure ohmic contacts between the channel layer and the source and drain electrodes. Further, plasma C
Forming a silicon nitride thin film by VD method and patterning using photoresist and reactive ion etching,
A through-hole is formed in the connection portion between the source electrode and the drain electrode. An aluminum thin film is formed by a sputtering method and is patterned using a photoresist and an aluminum etchant to form a source electrode and a data wiring. An ITO thin film is formed by a sputtering method, and is patterned using a photoresist and an ITO etchant to obtain a pixel electrode. A silicon nitride thin film is formed by a plasma CVD method, and is patterned using a photoresist and reactive ion etching to form a protective layer. The connection portion between the pixel electrode and the external signal line of the liquid crystal display element is removed by etching the protective layer. Thus, a substrate provided with a liquid crystal driving element composed of a thin film transistor is obtained.

An alignment agent made of polyimide is applied on the color filter substrate and the substrate provided with the liquid crystal driving element, dried at 80 ° C. for 10 minutes, and cured at 180 ° C. for 1 hour to obtain an alignment film. The alignment film is rubbed with a cotton cloth or a rayon cloth. In the twisted nematic method, the rubbing direction is selected such that the liquid crystal is twisted by 90 ° when the substrates on the color filter side and the liquid crystal drive element side are bonded.

The color filter substrate has a diameter of 2 μm to 7 μm.
Spray a spacer of μm polystyrene. On the other hand, an epoxy sealant mixed with a glass rod having a diameter of 2 μm to 7 μm is screen-printed on the substrate on which the liquid crystal drive element is formed. The sealant is disposed so as to be joined to the frame portion of the color filter, and a liquid crystal injection port is provided.

The color filter substrate and the substrate on which the liquid crystal driving elements are formed are positioned and subjected to heat treatment while applying pressure. The heat treatment is performed at 100 ° C. to 170 ° C. for 5 minutes to 2 hours, and the two substrates are fixed. A liquid crystal is injected into the cell thus obtained. First, the cell is placed under reduced pressure and sufficiently degassed. After the liquid crystal injection port provided in the sealant is immersed in the liquid crystal, the reduced pressure atmosphere is changed to a normal pressure or a pressurized atmosphere, and the liquid crystal is introduced into the cell. The liquid crystal injection port of the cell into which the liquid crystal has been injected is closed with an ultraviolet curable resin. The liquid crystal of the present invention has a saturation voltage of 2 V or less.

A polarizing film is attached to the outside of the substrate according to the rubbing direction. Thus, the liquid crystal display device of the present invention is obtained.

The saturation voltage of the liquid crystal display element is obtained by simultaneously opening all the gates of the liquid crystal display element and simultaneously writing data voltages to all pixels, that is, so-called panel collective lighting. It can be verified by measuring the relationship between the reflectance and the reflectance.

The color liquid crystal display device of the present invention can be used for displaying personal computers, word processors, engineering workstations, navigation systems, televisions, videos and the like, and can also be used as a light modulation device.

[0061]

EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

(Display unevenness observation) All gates of the liquid crystal display element are simultaneously opened, and data voltages are simultaneously applied to all pixels, so-called panel collective lighting, halftone display is performed at room temperature, and the display state is observed up to 500 hours. .

Reference Example 1 Synthesis of Polymer Dispersant 161.93 g of 4,4'-diaminobenzanilide,
3,3'-diaminodiphenyl sulfone 176.70
g, and 18.64 g of bis (3-aminopropyl) tetramethyldisiloxane with γ-butyrolactone 3266
g, N-methyl-2-pyrrolidone (622 g), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (439.09 g) was added, and the mixture was reacted at 70 ° C. for 3 hours. .22 g and then at 70 ° C.
For 1 hour and then a viscosity of 45 poise (25 ° C.)
A 17% solution (P-1) of a polymer dispersant was obtained.

Reference Example 2 Synthesis of oligomer dispersant 204.79 g of 3,3'-diaminodiphenyl sulfone
And 13.62 g of bis (3-aminopropyl) tetramethyldisiloxane were charged together with 3809 g of γ-butyrolactone, 59.98 g of pyromellitic dihydrate, 3,
295.6 g of 3 ', 4,4'-diphenylsulfonetetracarboxylic acid dihydrate was added and reacted at 60 ° C for 3 hours, and 98.22 g of 2-aminoanthraquinone was added.
Further, the reaction was carried out at 60 ° C. for 1 hour.
% Solution (O-1) was obtained.

Reference Example 3 Synthesis of Polyamic Acid 144.1 g of 3,3 ′, 4,4′-biphenyltetracarboxylic acid dihydrate was combined with 1095 g of γ-butyrolactone and N-
Charged with 209 g of methyl-2-pyrrolidone,
95.1 g of 4'-diaminodiphenyl ether and 6.20 g of bis (3-aminopropyl) tetramethyldisiloxane were added and reacted at 70 ° C. for 3 hours, and 2.96 g of phthalic anhydride was added. For 1 hour to obtain a 16% solution of polyamic acid (PAA1).

Reference Example 4 Synthesis of polyamic acid 372.4 g of 3,3′-diaminodiphenyl sulfone
146.0 g of paraphenylenediamine and bis (3
-Aminopropyl) tetramethyldisiloxane 32.3
g in 5750 g of N-methyl-2-pyrrolidone,
After adding 873.9 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and reacting at 70 ° C. for 3 hours, adding 5.88 g of maleic anhydride and further adding 70 ° C.
For 1 hour, and a 20% solution of polyamic acid (PAA
2) was obtained.

Example 1 A color filter substrate was manufactured in the following procedure.

46 g of carbon black, 240 g of a polyamic acid solution (PAA1) and 614 g of N-methyl-2-pyrrolidone were charged together with zirconia beads into a mill-type disperser, and dispersed at 7000 rpm for 30 minutes to obtain a black paste.

71.2 g of Pigment Green 36 and 12.6 g of Pigment Yellow 83 were weighed, and 4.41 each of a dispersing agent “SOLSPERS” 12000 manufactured by Zeneca Corporation.
g, 557 g of γ-butyrolactone, 3-methoxy-5
323 g of -methyl-1-butanol and 494 g of the polymer dispersant (P-1) were charged together with zirconia beads into a mill-type disperser, and dispersed at 3000 rpm for 2 hours to obtain a dispersion. 300 g of the dispersion and a polymer dispersant (P-1) 1
56.3 g was mixed with a solution obtained by diluting 198.3 g of γ-butyrolactone and 185.3 g of 3-methoxy-3-methyl-1-butanol to obtain a green paste.

Pigment Orange 38 (191.4 g)
Pigment Red 177, 138.6 g and γ-butyrolactone 3267 g, 3-methoxy-3-methyl-1
-1266 g of butanol, oligomer dispersant (O-1) 7
3.92 g, 562.95 g of polymer dispersant (P-1)
Was charged into a mill-type disperser and dispersed at 4000 rpm for 5 hours. Thus, a red dispersion having a pigment concentration of 6% was obtained. Polyamide acid solution (PAA1) 156.
A solution obtained by diluting 3 g with 108.3 g of γ-butyrolactone and 185.3 g of 3-methoxy-3-methyl-1-butanol was added and mixed to obtain a red paste.

Pigment Blue 15: 6 to 157.5
g, 337.5 g of polymer solution PAA2, 637.5 g of γ-butyl lactone and 367.5 g of N-methyl-2-pyrrolidone were charged into a mill-type disperser, and the mixture was supplied at 3000 rpm.
m for 2 hours. Thus, a blue dispersion having a pigment concentration of 10.5% was obtained. To 624 g of the blue dispersion, 702 g of a polymer solution PAA2, 374 g of γ-butyl lactone, N
836 g of -methyl-2-pyrrolidone and 415 g of 3-methoxy-3-methyl-butyl acetate were added and mixed to obtain a blue paste.

The above-mentioned black paste was applied on an alkali-free glass using a spinner and semi-cured in an oven at 135 ° C. for 20 minutes. A positive photoresist was applied on the black film with a spinner and dried at 90 ° C. for 10 minutes to obtain a 1.5 μm thick resist film. The grid pattern was exposed through a photomask. Using a 2.38% aqueous solution of tetramethylammonium hydroxide as a developing solution, the development of the photoresist and the etching of the black film were simultaneously performed. After the etching, the unnecessary photoresist layer was removed with acetone. Then in the oven 300
Curing was performed at 30 ° C. for 30 minutes to obtain a black matrix. The thickness of the black matrix layer is 0.9 μm
Met.

A red paste is applied on the glass substrate on which the black matrix is formed so as to have a thickness of 1.5 μm after the conversion of the polyimide, dried at 120 ° C. for 20 minutes, and a photoresist is applied thereon. For 10 minutes. The photoresist was exposed through a photomask patterned so as to fill every other opening of the grid arranged at a pitch of 100 μm of the black matrix. After the exposure, the film was immersed in a developing solution composed of a 2.38% aqueous solution of tetramethylammonium hydroxide to simultaneously develop a photoresist and etch a colored film of a polyimide precursor. After the etching, the unnecessary photoresist layer was removed with acetone. Further, the red coating film of the polyimide precursor was heat-treated at 240 ° C. for 30 minutes to convert to a polyimide. Thus, a red pixel was formed.

After the blue paste was applied to a glass substrate on which a black matrix was formed, the thickness was changed to 1.5 after polyimide conversion.
It was applied to a thickness of μm and dried at 120 ° C. for 20 minutes.
Thereafter, blue pixels were formed adjacent to the red pixels in the same manner as in the case of the red paste.

A green paste using the green pigment A obtained in Example 1 was applied to a glass substrate on which a black matrix was formed so as to have a thickness of 1.5 μm after polyimide conversion, and dried at 120 ° C. for 20 minutes. . Thereafter, a green pixel was formed adjacent to the red pixel in the same manner as in the case of the red paste.

40.8 g of methyltrimethoxysilane, 59.4 g of phenyltrimethoxysilane, 3,3 ′, 4
4'-benzophenonetetracarboxylic dianhydride 5.8
3 g was dissolved in 200 g of 3-methyl-3-methoxybutanol, and 34.2 g of distilled water was added with stirring at 30 ° C., and the mixture was heated and stirred for 1 hour to carry out hydrolysis and condensation. The temperature of the solution was gradually increased while stirring, and after 2 hours, the bath temperature was set to 135 ° C., and the generated alcohol and water were distilled off while stirring for another 2 hours to obtain 3,3 ′, 4,4′-.
An organosilsesquioxane oligomer solution containing benzophenonetetracarboxylic acid was obtained. Add this solution to 8
The mixture was cooled to 0 ° C, a mixture of 5.76 g of γ-aminopropylmethyldiethoxysilane and 57.3 g of 3-methyl-3-methoxybutanol was added, and the mixture was kept at 80 ° C with stirring for 2 hours. Thereafter, the mixture was cooled to room temperature to obtain a transparent protective film material composed of an organosilsesquioxane oligomer solution having a modified organic structure.

The transparent protective film material is spin-coated on the substrate on which the colored film is formed, dried at 100 ° C. for 5 minutes, and then heated at 290 ° C. for 1 hour to form a 1 μm thick transparent protective film made of silicone polyimide. A film was formed. The transparent protective film was formed on the entire surface of the substrate.

An ITO thin film having a thickness of 0.1 μm was formed on the transparent protective film by a sputtering method to obtain a color filter. At this time, the substrate temperature was 230 ° C., and the portion where the ITO thin film was attached was limited to the display region and the lead portion to the drive element substrate side using a mask.

A drive element substrate provided with a TFT array was manufactured in the following procedure.

A chromium thin film having a thickness of 0.2 μm was formed on an alkali-free glass by a sputtering method. A positive photoresist was applied on the chromium thin film and dried to form a photoresist film. Subsequently, a photomask was placed on the photoresist film and irradiated with ultraviolet rays using an exposure device.
After the exposure, the photoresist film was developed with an alkaline developer. Next, the chromium thin film is etched with a chromium etchant mixed in a ratio of potassium ferricyanide: sodium hydroxide: water = 1000: 350: 4365,
A pattern including a gate electrode, a gate wiring, and an additional capacitor was manufactured. After the chromium etching, the unnecessary photoresist film was stripped with a stripping solution. On the chromium thin film, a silicon nitride thin film having a thickness of 0.7 μm and an amorphous silicon thin film having a thickness of 0.08 μm were continuously formed by a plasma CVD method. A positive type photoresist was applied on the amorphous silicon thin film and dried to form a photoresist film. Subsequently, a photomask was placed on the photoresist film and irradiated with ultraviolet rays using an exposure device. After the exposure, the photoresist film was developed with an alkaline developer.
Next, the amorphous silicon thin film and the silicon nitride thin film were etched by a reactive ion etching method to form a channel portion. After the reactive ion etching, the unnecessary photoresist film was removed by ashing and a removing liquid. Next, a thickness of 0.5
A silicon nitride thin film of μm was formed. An etching stopper for protecting the channel portion was formed by patterning using photoresist and reactive ion etching in the same manner as the amorphous silicon thin film so that the silicon nitride thin film remained in the channel portion of the transistor. A boron-doped amorphous silicon thin film having a thickness of 0.2 μm is formed thereon by plasma CVD, and then patterned using a photoresist and reactive ion etching to form a channel layer and a source electrode and a drain electrode. Ohmic contact was secured. Further, a silicon nitride thin film having a thickness of 0.5 μm was formed by a plasma CVD method, and was patterned by using a photoresist and reactive ion etching, thereby forming a through hole at a portion where the source electrode and the drain electrode were connected. An aluminum thin film having a thickness of 0.2 μm is formed by a sputtering method, and is patterned using a photoresist and an aluminum etchant.
Source electrodes and data lines were formed. 0.1μ thickness
After forming an ITO thin film of m by a sputtering method, a pixel electrode was obtained by patterning using a photoresist and an ITO etchant. 0.5μm thickness by plasma CVD
Was formed and patterned using a photoresist and reactive ion etching to form a protective layer. The connection portion between the pixel electrode and the external signal line of the liquid crystal display element was removed by etching the protective layer.

Thus, a substrate provided with a liquid crystal drive element composed of a thin film transistor was obtained.

An alignment agent made of polyimide is applied on the above-mentioned color filter substrate and the substrate provided with the liquid crystal driving element, dried at 80 ° C. for 10 minutes, and cured at 180 ° C. for 1 hour to obtain an alignment having a thickness of 0.08 μm. A membrane was obtained. The alignment film was rubbed with a rayon cloth. The rubbing direction was selected such that the liquid crystal was twisted 90 ° counterclockwise when the substrates on the color filter side and the liquid crystal drive element side were bonded together.

A spacer made of polystyrene having a diameter of 4.2 μm was sprayed on the color filter substrate. On the other hand, an epoxy-based sealant mixed with a glass rod having a diameter of 4.5 μm was screen-printed on the substrate on which the liquid crystal drive element was formed. The sealant was disposed so as to be joined to the frame portion of the color filter, and a liquid crystal injection port was provided.

The color filter substrate and the substrate on which the liquid crystal driving elements were formed were aligned and subjected to heat treatment while applying pressure. The heat treatment was performed at 150 ° C. for 1 hour to cure the sealant and fix the substrate. A portion required for the liquid crystal display element in the used glass substrate was cut out with a glass scribe device.

The cell thus obtained is placed under reduced pressure and sufficiently degassed. After the liquid crystal injection port provided in the sealant was immersed in a liquid crystal having a saturation voltage of 1.84 V (MLC6424 manufactured by Merck), the reduced pressure atmosphere was returned to normal pressure, and the liquid crystal was introduced into the cell. The liquid crystal injection port of the cell into which the liquid crystal was injected was closed with an ultraviolet curable resin.

A polarizing film was attached to the outside of the substrate according to the rubbing direction. Thus, a liquid crystal display device of the present invention was obtained.

The ten liquid crystal display elements were turned on at room temperature at a time, and the display state was observed up to 500 hours in a halftone display.

Comparative Example 1 A liquid crystal display device was manufactured in the same manner as in Example 1 except that no transparent protective film was provided on the color filter substrate. The ten liquid crystal display elements thus obtained were turned on at room temperature at a time, and the display state was observed in a halftone display.
There were six liquid crystal display elements in which display unevenness occurred over time, which was defective.

Comparative Example 2 A transparent protective film was not provided on a color filter substrate, and after a photoresist was removed by patterning each color layer of the color filter, a 2.38% aqueous solution of tetramethylammonium hydroxide was supplied. A liquid crystal display device was produced in the same manner as in Example 1, except that the entire surface of the glass substrate was scrubbed with a disk brush while performing the above. The ten liquid crystal display elements thus obtained were lit at a time at room temperature, and the display state was observed up to 500 hours in a halftone display. As a result, there was no display unevenness, and the display was good. And the scratches appeared to shimmer.

Example 2 Example 1 except that a liquid crystal having a saturation voltage of 1.7 V was used.
In the same manner as in the above, a liquid crystal display element was manufactured. The ten liquid crystal display elements thus obtained were turned on at a time at room temperature, and the display state was observed up to 500 hours in a halftone display.

Comparative Example 3 A liquid crystal display device was manufactured in the same manner as in Example 2 except that no transparent protective film was provided on the color filter substrate. The thus obtained ten liquid crystal display elements were turned on at room temperature at a time, and the display state was observed in a halftone display. In 100 hours, display unevenness occurred in all the liquid crystal display elements, which was defective.

Comparative Example 4 A transparent protective film was not provided on a color filter substrate, and after a photoresist was removed by patterning each color layer of the color filter, a 2.38% aqueous solution of tetramethylammonium hydroxide was supplied. A liquid crystal display device was manufactured in the same manner as in Example 2, except that the entire surface of the glass substrate was scrubbed using a disk brush while performing. The ten liquid crystal display elements thus obtained were turned on at room temperature at a time, and the display state was observed in a halftone display.
At 0 hour, display unevenness was observed on three sheets. Also,
There were fine scratches in the colored film of the color filter, and some of the scratches appeared to shimmer.

Example 3 Example 1 was repeated except that an epoxy-modified acrylic material "Optomer" SS (manufactured by Nippon Synthetic Rubber Co., Ltd.) was used as the transparent protective film material, and a 1 μm thick transparent protective film was provided. A liquid crystal display device was produced in the same manner as in the above. The ten liquid crystal display elements thus obtained were turned on at room temperature at a time, and the display state was observed for up to 500 hours in halftone display.

Comparative Example 5 A liquid crystal display device was prepared in the same manner as in Example 1 except that a transparent protective film was not provided on the color filter substrate and a liquid crystal having a saturation voltage of 2.14 V (MLC2035 manufactured by Merck) was used. Was prepared. Liquid crystal display element 10 thus obtained
When the sheets were lit at room temperature and the display state was observed in a halftone display, no display unevenness occurred.

Example 4 A liquid crystal display device was manufactured in the same manner as in Example 1 except that the application conditions of the transparent protective film were changed and the thickness was changed to 0.01 μm. The ten liquid crystal display elements thus obtained were turned on at a time at room temperature, and the display state was observed in a halftone display.
There were three liquid crystal display elements in which display unevenness occurred in 100 hours, which was worse than Example 1, but improved compared to Comparative Example 1.

Example 5 A liquid crystal display device was manufactured in the same manner as in Example 1 except that the application conditions of the transparent protective film were changed and the thickness was changed to 4 μm. The 10 liquid crystal display elements thus obtained were turned on at room temperature at a time and the display state was observed in halftone display. No display unevenness was found, but bubbles were likely to remain in the cell gap when liquid crystal was injected. Yield decreased.

[0097]

According to the present invention, it is possible to provide a liquid crystal display element having a stable and good display quality even in a low voltage driving liquid crystal in which display unevenness is likely to occur.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H048 BB02 BB14 BB37 BB43 2H090 HB04X KA07 LA04 LA05 LA15 LA20 MB02 MB03 2H091 FA02X FA02Y FA02Z FA08X FA08Z FA14Z FA35Y FC01 GA13 GA16 HA09 LA16 2K009 AA15 BB02 CC02 CC02 CC24 CC24

Claims (5)

[Claims] 1. A liquid crystal display device comprising a color filter in which a plurality of coloring layers are arranged on a substrate, wherein a transparent protective layer is provided on the coloring layer of the color filter, and a saturation voltage is 2V. A liquid crystal display device comprising the following nematic liquid crystal. 2. The nematic liquid crystal has a saturation voltage of 1.
2. The liquid crystal display device according to claim 1, wherein a nematic liquid crystal of 8 V or less is used. 3. The liquid crystal display device according to claim 1, wherein said transparent protective layer is formed outside the liquid crystal display area. 4. The liquid crystal display device according to claim 1, wherein said transparent protective layer is at least one of an acrylic resin, an epoxy resin, a siloxane polymer, a silicone polyimide and a benzocyclobutene resin. 5. The transparent protective layer has a thickness of from 0.03 μm to 3 μm.
2. The liquid crystal display device according to claim 1, wherein the thickness of the liquid crystal display device is μm.