JPH11352500A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which exhibits fine light shielding property preventing any light leakage from appearing at its sealed part and utilizes a dark colored sealant having excellent insulating property, strength of adhesion and reliability for moisture resistance. SOLUTION: In a liquid crystal display device with a display element comprised of disposing a lower part transparent glass substrate SUB1 provided with thin film transistor TFT, transparent pixel electrodes ITO1 and image signal electrodes d2, d3 and an upper part transparent glass substrate SUB2 provided with a common transparent pixel electrode ITO2 to face oppositely with a specified gap width, bonding both substrates with a sealant SL colored with a coloring agent and provided in a shape of frame outside of a display region around a periphery of both substrates SUB1, SUB2 and sealing a liquid crystal layer LC between both substrates inside of the sealant SL, resistivity of the coloring agent is >=10<6> Ω.cm, secondary flocculation particle size of the coloring agent is <=10 μm and resistivity between the image signal electrodes d2, d3 and the common transparent pixel electrode ITO2 is >=10<9> Ω.cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, and more particularly to an active matrix type liquid crystal display device using a liquid crystal control element such as a thin film transistor.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device is provided with a non-linear element (liquid crystal control element, switching element, active element) corresponding to each of a plurality of pixel electrodes arranged in a matrix. . The liquid crystal in each pixel is theoretically always driven (duty ratio
1.0), so that it is more active than the so-called simple matrix system that employs a time-division driving system.
The matrix method has a good contrast and is becoming an indispensable technology especially for a color liquid crystal display device. As a typical liquid crystal control element, a thin film transistor (T
FT).

Incidentally, an active matrix type liquid crystal display device using thin film transistors is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-309921 or "1.
2.5-inch active matrix color liquid crystal display ", Nikkei Electronics, pp. 193-210, December 1986
March 15, published by Nikkei McGraw-Hill, Inc.

In a liquid crystal display device (ie, a liquid crystal display module), for example, a transparent electrode for display and a surface on which a laminated film such as an alignment film is formed face each other with a predetermined gap therebetween.
A transparent insulating substrate made of a piece of glass or the like is overlapped, and both substrates are bonded together by a liquid crystal sealing agent provided in a frame shape (a square shape) on a peripheral portion between the two substrates, and a part of the sealing agent is applied. A liquid crystal display element (that is, a liquid crystal display panel, an LCD) comprising a liquid crystal sealed inside a sealant between the two substrates from the provided liquid crystal inlet, and further provided with a polarizing plate outside the two substrates for transmitting only a certain amount of polarized light. : Liquid Crystal Display), a backlight that is disposed below the liquid crystal display element, emits light from the surface, supplies light to the liquid crystal display element, and serves as a light source for displaying an image, and a liquid crystal display element. A driving circuit board disposed outside the outer peripheral portion of, a liquid crystal display element and a plastic mold case for storing and holding a backlight, and storing each of the members,
It consists of a metal upper shield case with an open display window, a metal lower shield case, and the like.

In manufacturing a liquid crystal display device, a sealant is applied to the periphery of a glass substrate in a frame shape by a method such as dispenser application or screen printing, and is usually heated or flattened without heating ( Leveling), the upper and lower glass substrates are aligned with high precision using the alignment marks, and then the sealing agent is pressed to bond the upper and lower glass substrates.

A thermosetting epoxy resin is mainly used as a sealant, and amines, imidazoles, and hydrazides are used as a curing agent for the epoxy resin. However, a sealant using such a curing agent has a problem that the adhesiveness and the moisture resistance reliability are poor. As a method for solving this problem, Japanese Patent Application Laid-Open No.
In this method, a phenol novolak resin is used as a curing agent for an epoxy resin, a solvent is added, and a liquid that can apply the sealant is used in this method. , Which indicates that the sample is excellent in moisture resistance.

However, since this sealant is transparent or milky white, it is behind the liquid crystal display element (the side opposite to the display).
When the display is performed by irradiating light from the backlight with light, light leakage (bright line) occurs at the seal portion of the liquid crystal display element (that is, the peripheral portion of the display screen) through the sealant. When light leakage occurs, contrast is reduced at the peripheral portion, and display quality is significantly reduced. In particular, when displaying bright characters, figures, and the like on a dark display surface, there is a problem in that the display is greatly affected by the light leakage.

In order to solve this problem, a method has been devised in which carbon black or a black dye or the like is added to a sealant to make the sealant black and have a light-shielding function to prevent light leakage.

[0009] However, the sealing agent containing carbon black has a problem that the insulating properties are poor because the carbon black itself has conductivity. In addition, a sealant using a black dye to provide a light-shielding property is inferior to a light-shielding property, and has a problem of causing liquid crystal contamination and corrosion of an electrode made of a metal film due to impurity ions of the dye. Was. Therefore, a sealant having high insulation properties, high moisture resistance reliability, and high light-shielding properties has been demanded.

In recent liquid crystal display devices, a large number of electrodes and the like are formed on a large glass substrate, the upper and lower substrates are attached to each other, and then assembled, and then divided into individual liquid crystal display devices (a so-called “liquid crystal display device”). Although the multi-processing process is used, the number of processed glass substrates has been increasing from the conventional single-sheet processing to two-sheet processing, four-sheet processing, six-sheet processing and nine-sheet processing.

Further, in recent years, since the size of the liquid crystal display element itself has been further increased, the stress applied to the seal portion during the multi-machining process has become much larger than in the past. Further, the line width of the sealant has been reduced in order to increase the area of the display region and to narrow the so-called frame portion outside the display region of the liquid crystal display element. For this reason, there has been a problem in that the stress at the time of cutting the glass substrate during the multi-machining process causes peeling of the sealant. This includes
Although a sealant having excellent adhesiveness is required, conventional sealants using amines, imidazoles, and hydrazides as curing agents have poor adhesiveness and cannot respond to the enlargement of glass substrates and liquid crystal display elements. . In addition, as the length of the seal line is increased and the line width is reduced with the increase in the size of the liquid crystal display element, a sealant having more excellent moisture resistance reliability has been demanded.

[0012]

The portion to which the seal is applied has electrodes, but is insulated in some form. For example, a PAS (passivation) film is formed on the electrode by a CVD method or the like. However, a predetermined gap (2
There is a risk that the spacer (gap controlling material), which is essential for forming the (substrate spacing), breaks the PAS film, and the otherwise insulated portion becomes conductive. For example, there is conduction between the common transparent pixel electrode provided on each of the opposing surfaces of the two substrates and the video signal electrode. This danger increases as the gap becomes narrower and emerges as a problem. Also, CF
Also on the substrate (substrate on which the color filter is formed), for example, ITO
When sputtering (indium tin oxide) film, it is necessary to keep the mask in non-contact, and therefore, there is a high possibility that the ITO film may be present in the seal coating portion because it goes around the sputter mask. In particular, when an attempt is made to enlarge the display area, such as by reducing the size of the frame, the portion that cannot be covered by the sputter mask becomes large, and the problem of short-circuiting due to the conductors of the upper and lower substrates rises significantly.

An object of the present invention is to provide a liquid crystal display device using a dark sealant having a high light-shielding property for preventing light leakage at a seal portion of a liquid crystal display element, and having excellent insulation properties, adhesive strength and moisture resistance reliability. Is to provide.

[0014]

In order to solve the above-mentioned problems, the present invention relates to a first substrate provided with a liquid crystal control element, a pixel electrode and a signal electrode, and a second substrate provided with a common pixel electrode. Are disposed facing each other with a predetermined gap therebetween, are colored by a coloring agent, and are bonded to the two substrates by a sealing agent provided in a substantially frame shape around the edge between the two substrates, and the inside of the sealing agent is In a liquid crystal display device having a liquid crystal display element in which a liquid crystal is sealed between the two substrates, a specific resistance of the colorant is 10 ⁶ Ω · cm or more, and a secondary aggregation particle size of the colorant is 10 μm or less, A specific resistance between the signal electrode and the common pixel electrode is 10 ⁹ Ω · cm or more.

Further, the colorant is a titanium-based black pigment.

According to the present invention, by adopting the above-described structure, a dark sealing agent having a high light-shielding property for preventing light leakage at a sealing portion of a liquid crystal display element, and having excellent insulating properties, adhesive strength and moisture resistance reliability. Can be provided.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings described below, those having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

The black sealant used in the liquid crystal display element of the present embodiment is characterized by containing (a) an epoxy resin, (b) a novolak resin, (c) a curing accelerator, and (d) a titanium black pigment. And

Epoxy resin (a) used in the present embodiment
Is not particularly limited, and examples thereof include a bisphenol-type epoxy resin, N, N-diglycidyl-o-toluidine, N, N-diglycidylaniline, phenylglycidyl ether, resorcinol diglycidyl ether, and 1,6-hexanedioldiene. Glycidyl ether,
Trimethylolpropane triglycidyl ether, polypropylene glycol diglycidyl ether, (3,4
-Epoxycyclohexylmethyl) -3,4-epoxycyclohexanecarboxylate, epoxy resin of hexahydrophthalic anhydride diglycidyl ester, bisphenol S, 4,4-biphenylphenol, 2,2 ',
6,6'-tetramethyl-4,4'biphenylphenol, 2,2 ', 6,6'-tetramethyl-4,4'-biphenylphenol, 2,2-methylene-bis (4-methyl-6 tert-butylphenol), trishydroxyphenylmethane, pyrogallol, phenols having a diisopropylidene skeleton, phenols having a fluorene skeleton such as 1,1-di-4-hydroxyphenylfluorene, and polyphenol compounds such as phenolized polybutadiene. A polyfunctional epoxy resin which is a sidyl ether, phenol, cresols, ethyl phenols, butyl phenols, octyl phenols, bisphenol A, bisphenol F, bisphenol S, novolak resin made from various phenols such as naphthols, etc. Glycidyl etherified products of various novolak resins such as phenol novolak resin containing a rylene skeleton, phenol novolak resin containing a dicyclopentadiene skeleton, phenol novolak resin containing a fluorene skeleton, alicyclic epoxy resin having an aliphatic skeleton such as cyclohexane, isocyanuric ring, hydantoin Heterocyclic epoxy resin having a heterocyclic ring such as a ring, epoxy resin obtained by glycidylation of brominated phenols such as brominated bisphenol A, brominated bisphenol F, brominated bisphenol S, brominated phenol novolak, brominated cresol novolak, etc. And epoxy resins which are generally manufactured and sold. Preferred are bisphenol epoxy resins such as bisphenol A epoxy resin and bisphenol F epoxy resin. Resins, N, N-
Diglycidyl-o-toluidine, N, N-diglycidylaniline, (3,4-epoxycyclohexylmethyl)
-3,4-epoxycyclohexanecarboxylate,
Hexahydrophthalic anhydride diglycidyl ester, more preferably bisphenol A type epoxy resin and / or bisphenol F type epoxy resin. These epoxy resins may be used as a mixture of two or more.

The novolak resin (b) in the present embodiment is used as a curing agent. Novolak resin (b)
Examples thereof include bisphenol A, tetrabromobisphenol A, bisphenol F, bisphenol S,
4,4'-biphenylphenol, 2,2 ', 6,6'
-Tetramethyl-4,4'-biphenylphenol,
2,2'-methylene-bis (4-methyl-6-tert
-Butylphenol), trishydroxyphenylmethane, pyrogallol, phenols having a diisopropylidene skeleton, phenols having a fluorene skeleton such as 1,1'-di-4-4hydroxyphenylfluorene,
Polyphenol compounds such as phenolized polybutadiene, phenol, cresols, ethylphenols,
Novolak resins made from various phenols such as butylphenols, octylphenols, bisphenol A, brominated bisphenol A, bisphenol F, bisphenol S, naphthols, phenol novolak resins containing a xylylene skeleton, phenol novolak resins containing a dicyclopentadiene skeleton, and fluorene Phenolic novolak resins such as skeleton-containing phenol novolak resins can be mentioned, and preferably various phenols such as phenol, cresols, ethylphenols, butylphenols, octylphenols, bisphenol A, bisphenol F, bisphenol S, naphthols, etc. Novolak resin as raw material, phenol novolak resin containing xylylene skeleton, phenol novol containing dicyclopentadiene skeleton Click resin, a variety of novolak resins, such as a fluorene skeleton containing phenol novolak resin,
More preferred are various novolak resins such as novolak resins made from various phenols such as phenol, cresols, octylphenol, bisphenol A, bisphenol F, bisphenol S, and naphthols, and particularly preferred are phenol novolaks made from phenol. It is a novolak resin made from monophenols as a raw material, such as a cresol novolak resin made from a resin or cresols.

These novolak resins are used alone or in combination of two or more. The amount of the novolak resin used in the present embodiment is 0.6 to 1.4 chemical equivalents, preferably 0. 4 equivalents of the hydroxyl group in the novolak resin with respect to the epoxy equivalent of the epoxy resin in the sealant. 8 to 1.2 chemical equivalents. More preferably, 0.
9 to 1.1 chemical equivalents.

The curing accelerator (c) used in the present embodiment includes, for example, imidazoles, imidazoles and phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid,
Pyromellitic acid, naphthalenedicarboxylic acid, maleic acid, salts with polycarboxylic acids such as oxalic acid, amides such as dicyandiamide and amides and phenols,
Salts with the polycarboxylic acids or phosphinic acids, diasa compounds such as 1,8-diasa-bicyclo (5,4,0) undecene-7, and the diasa compounds and phenols, the polycarboxylic acids, or phosphine Examples thereof include salts with acids, phosphines such as triphenylphosphine and tetraphenylphosphonium tetraphenylborate, phenols such as 2,4,6-trisaminomethylphenol, and amine adducts.

The amount of the curing accelerator to be added is as follows:
0.5 to 20 parts by weight, preferably 1 to 0 parts by weight
15 parts by weight, more preferably 2 to 10 parts by weight.

It is preferable to use these curing accelerators in the form of a latent curing accelerator because they have the advantages of improving workability (extending the pot life time) and the like. Latent curing accelerators are solid at room temperature, dissolve when heated, and have the property of reacting as a curing accelerator for the first time. For example, a microcapsule-type curing accelerator in which these curing accelerators are microencapsulated And a solid dispersion hardening accelerator (for example, imidazoles) which is hardly dissolved in a solvent or an epoxy resin, and an amine adduct.

The titanium-based black pigment (d) used in the present embodiment means low-order titanium oxide, titanium oxynitride or the like. Of these, low order titanium oxide is disclosed, for example, in JP-A-49-5.
Described in 432 JP (Kokoku 52-12733 JP), Ti _n O _2n-1 titanium and metallic titanium dioxide powder in vacuum or a reducing atmosphere, which is obtained by heating at a temperature of from 550 to 1,100 ° C. ( n is a positive number) or a compound containing silicon, aluminum, niobium, tungsten, or the like, as described in JP-A-64-11572. Compounds obtained by heating in an inert atmosphere in the presence of the following sintering aid can be mentioned. Examples of titanium oxynitride include JP-A-60-65069 (JP-B-3-51645) and JP-A-60-200.
No. 827 (Japanese Patent Publication No. 2-42773), a black compound obtained by reducing titanium dioxide or titanium hydroxide powder at a temperature of about 550 to 950 ° C. in the presence of ammonia. Can be. In addition, JP-A-61-201610 (Japanese Patent Publication No. 3-29010)
Japanese Patent Application Laid-Open No. H10-216, the black compound obtained by adhering vanadium to titanium dioxide or the like and reducing it at 750 to 875 ° C. in the presence of ammonia. The volume resistivity of these titanium black pigments is 10 ⁵ Ω · c
m or more is preferable. As the titanium-based black pigment used for the black sealant of the present embodiment, a high insulating property is imparted, a higher light-shielding property is obtained, and a gap at the time of bonding two glass substrates at the time of manufacturing a liquid crystal display element is obtained. It is necessary that the particles be easily formed. For this purpose, the average particle size of the primary aggregated particles is preferably 4 μm or less, preferably 2 μm or less, and more preferably 1 μm or less. Average primary particle size is 4
If it exceeds μm, the insulating property of the sealant may be impaired, or the gap of the liquid crystal display element may not be formed properly. Furthermore, secondary aggregated particles exist even if the average particle size of the primary particles is 4 μm or less. That is, re-agglomeration occurs when exposed to air. Therefore, when kneading with the sealant, the particle size is preferably 2 μm or less. The secondary aggregate may be subjected to a heat treatment or a treatment such as extending the time for kneading. The amount used is 10 to 70% by weight, preferably 20 to 60% by weight, more preferably 30 to 50% by weight, based on the solid content of the black sealant excluding the organic solvent. The primary aggregation is aggregation before mixing the coloring agent into the sealant, and is usually 0.02 to 0.1 μm, and the secondary aggregation is aggregation when the liquid crystal display element is completed. When the colorant is mixed in the sealant, it is largely aggregated by moisture, oxidation and the like.

In the present embodiment, for example, an organic pigment and an inorganic pigment can be used as needed for the purpose of improving optical characteristics. Organic pigments include anthraquinones, phthalocyanines, benzimidazones, quinacridones, azochelates, azos, isoindolinones, pyranthrones, indanthrones, anthrapyrimidines, dibromoanzathrones, and flavanthrones. And perylene, perinone, quinophthalone, thioindigo, and dioxazine pigments. For details, those described in the organic pigment section of the Coloring Material Handbook (edited by the Coloring Material Association) can be used, but not limited thereto. Further, if necessary, they can be used alone or in combination of two or more.

The inorganic pigment which can be used in the present embodiment includes barium sulfate, zinc white, lead sulfate, titanium oxide, yellow lead, red iron oxide, ultramarine blue, navy blue, chromium oxide, antimony white, iron black, lead red, Metal oxides such as zinc sulfide, cadmium yellow, cadmium red, zinc, manganese purple, cobalt purple, barium sulfate, and magnesium carbonate;
Examples thereof include metal sulfides, sulfates, metal hydroxides, and metal carbonates. In addition, carbon-based inorganic pigments such as conventionally known carbon black and grafted carbon black may be used to the extent that the resistivity is not impaired.
For details, those described in the inorganic pigment section of the Coloring Material Optical Handbook (edited by the Coloring Material Association) can be used, but are not limited thereto. Further, if necessary, they can be used alone or in combination of two or more.

It is preferable to add a coupling agent to the black sealant used in the liquid crystal display device of the present embodiment. Commercially available coupling agents can be used, and among them, a silane coupling agent is preferable. The amount of the coupling agent to be added is 0.001% by weight to 10% by weight, preferably 0.01% by weight based on the solid content of the black sealant.
% By weight to 5% by weight.

The titanium black pigment used in the present embodiment,
The content of the total pigment of the organic pigment and the inorganic pigment is 10 to 70% by weight, preferably 20 to 60% by weight, more preferably 30 to 50% by weight in the solid content excluding the organic solvent of the black sealant.
The organic pigment and / or inorganic pigment can be used in an amount of 0 to 60% by weight, preferably 0 to 50% by weight. When the content of the total pigment is lower than 10% by weight, the light-shielding property is not sufficient, and when the content exceeds 70% by weight,
Since the content is too large, the pigment is hardly crushed, and the gap cannot be formed in the liquid crystal display element.

A filler may be added to the sealant of the present embodiment in order to improve the insulating properties, the adhesive strength, and the moisture resistance reliability of the sealant. As fillers, fused silica, crystalline silica, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, Examples include magnesium hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, and the like, preferably, fused silica, crystalline silica, and silicon nitride. , Boron nitride, calcium carbonate, barium sulfate, calcium sulfate,
Mica, talc, clay, alumina, aluminum hydroxide, calcium silicate, and more preferably fused silica, crystalline silica, and alumina. These fillers may be used as a mixture of two or more kinds, and particularly preferably when silica and alumina are used in combination. The addition amount of the filler is preferably 20% by weight or less based on the solid content excluding the organic solvent of the black sealant, as long as the workability and the light-shielding property are not impaired. The average particle size of the filler is preferably 4 μm or less, preferably 2 μm or less, and more preferably 1 μm or less. If the average particle size is 4 μm or more, it may be difficult to form a gap in the liquid crystal display element.

A solvent may be added to the sealant of the present embodiment in order to improve workability and to lower the viscosity. Examples of the solvent that can be used include alcohol solvents, ether solvents, and acetate solvents. One or more of these solvents may be used.
They can be used alone or in a mixture at any ratio.

The amount of the solvent used may be any amount necessary for adjusting the black sealant to, for example, 200 to 400 poise (25 ° C.), which can be applied by a method such as dispenser coating or screen printing. Usually, it is used so that the nonvolatile component in the black sealant is 70% by weight or more, preferably 85 to 95% by weight.

The black sealing agent used in the present embodiment is prepared by adding the above-mentioned epoxy resin and novolak resin to the mixture by adding a solvent if necessary, heating and mixing the mixture, and further dissolving the titanium black pigment, a curing accelerator, If necessary, a predetermined amount of an organic pigment and / or an inorganic pigment, a metal oxide, a filler, a coupling agent, an antifoaming agent, a leveling agent and the like are added, and a known mixing device, for example, a ball mill, a sand mill, three It can be manufactured by mixing with a roll or the like. The curing accelerator, the coupling agent, the defoaming agent, the leveling agent, and the like may be added after the pigment and the resin solution are mixed by a mixing device.

The black sealant used in the present embodiment preferably has a cured product having a volume resistivity of 10 ⁷ Ω · cm or more under the measurement conditions of a film thickness of 4 μm and a voltage of 30 V or less. Further, the optical density (OD value) of the cured product is preferably 2.0 or more, more preferably 2.5 or more, and further preferably 3.
0 or more.

In the liquid crystal display device of the present embodiment, in the case of the transmission type, the liquid crystal composition is held between a pair of transparent insulating substrates, and the peripheral edges of both plates are sealed with the sealant. An electrode or a liquid crystal control element is provided on at least one inner surface of the transparent insulating substrate. As a transparent insulating substrate,
A glass substrate, a quartz substrate, a plastic substrate, or the like can be used. As the liquid crystal control element, a known element for controlling the electro-optical effect of the liquid crystal can be used. For example, amorphous silicon TFT, polycrystalline silicon TFT, M
An IM, a diode, a single crystal MOSFET, and the like can be given. On the other hand, in the case of the reflection type, a silicon substrate can be used as one of the substrates. In addition, a color liquid crystal display device can be obtained by providing, for example, three primary color filters of red, green, and blue arranged in a matrix on a counter substrate.

As the liquid crystal composition used in the present embodiment, known liquid crystal compositions can be used. For example, fluorine-based, cyano-based, cyclohexane-based, phenylcyclohexane-based, biphenyl-based, Schiff-based, ferroelectric, And antiferroelectric liquid crystals.

In the liquid crystal display device of the present embodiment,
After the spacer is added to the black sealant, the substrate is coated on one edge of the substrate by a known method such as screen printing or dispenser application so as to leave an injection port for the liquid crystal composition. Examples of the spacer include glass fiber and glass beads. Although the diameter varies depending on the purpose, it is usually 2 to 10 μm, preferably 4 to 7 μm.
μm. The amount used is 0.05 to 4 parts by weight, based on 100 parts by weight of the black sealant of the present invention excluding the solvent.
Preferably 0.3 to 3 parts by weight, more preferably 0.1 to 3 parts by weight.
It is about 5 to 1.5 parts by weight. Then, for example, 100
The solvent is evaporated by heating at 10 ° C. for 10 minutes, and a spacer made of beads, for example, is dispersed by a known method such as dry dispersion or semi-dry dispersion so that a predetermined interval is obtained on the other substrate. The substrates of the liquid crystal control element are aligned so as to correspond to each other, and the two substrates are superimposed. Then, the upper and lower glass substrates are bonded and pressed to form a gap.
After curing for about 2 hours to prepare a liquid crystal cell, filling it with the liquid crystal composition from the injection port, and sealing the injection port with a known sealing agent to obtain a liquid crystal display element Can be. The liquid crystal display element thus obtained is excellent in adhesiveness and moisture resistance, and since a black sealant is used, light leakage from the seal portion can be prevented,
Excellent display characteristics.

[0038]

EXAMPLES Examples 1, 2, and 3 A method for measuring the specific resistance (that is, the resistivity) of a colorant for coloring a sealant for producing a liquid crystal display device will be described.

FIG. 2 is a schematic diagram showing an example of a measuring system of the measuring device for measuring the specific resistance of the coloring agent of the sealant.

S is a sample, A and A 'are electrodes, B is a measuring cell, C is a press, D is an insulating plate, and E is a resistance measuring instrument.

1) Into the measuring cell B, 3 g of the sample S of the sealant is put, and the sample S is held by the upper and lower electrodes A and A '.

2) The press C is operated to press the upper surface of the electrode A to compress the sample S.

3) The resistance value of the sample S in the excessively thick material and the thickness of the sample S are measured.

4) Powder specific resistance of sample S (Ω · cm) = resistance value × area of electrode A / thickness of sample S

The following Table 1 shows the secondary aggregation particle diameter (μm) and the specific resistance (Ω · cm) of the titanium black pigment used in Examples 1, 2, and 3 and Comparative Examples 1 and 2. Show.

[0046]

[Table 1]

The black sealant for the liquid crystal display element was adjusted by using a bisphenol A type epoxy resin having an epoxy equivalent of 480 (Epicoat 1001, manufactured by Yuka Shell).
g and 24 g of a phenol novolak resin (Tamanol 758, manufactured by Arakawa Chemical Industries) are dissolved in 58 g of propylene glycol monoethyl ether acetate as a solvent by heating. 80 g of the titanium black pigment used in Table 1 was mixed and dispersed in this resin solution by a sand mill, and the dispersion was treated with 2-ethyl-4-methylimidazole (2E4M) as a curing accelerator.
Z, Shikoku Chemicals) 1.3 g, N- as a coupling agent
9 g of phenyl-γ-aminopropyltrimethoxysilane
And make a mixture.

Further, 1 g of a glass fiber having a diameter of 4 μm for forming a gap was added to 100 g of the mixture to obtain several kinds of black sealants used in this example.

The specific resistance of these sealants after curing was also measured.
It is described in Table 1.

As a result, as is clear from Table 1, the sealing agent having a secondary aggregated particle size of 10 μm or less has a resistivity of 10 ⁷ Ω · cm or more even in a specific resistance measurement of a 4 μm gap, and has a very high insulating property. . On the other hand, the secondary aggregate particle size is 12 μm.
In the sealants of Comparative Examples 1 and 2, which are 20 μm and 20 μm, the specific resistance is small and the insulating property is low. The specific resistance of the colorant is 1
If 0 ⁶ Ω · cm or more, there is a conduction preventing effect it has been confirmed by the present inventors.

Example 4 A black sealant for a liquid crystal display element was prepared by adjusting 100 g of a bisphenol A type epoxy resin having an epoxy equivalent of 480 (Epicoat 1001, manufactured by Yuka Shell), and a phenol novolak resin (Tamanol 758, manufactured by Arakawa Chemical Industries). 24 g are heated and dissolved in 58 g of propylene glycol monoethyl ether acetate as a solvent. In this resin solution, 80 g of the titanium-based black pigment used in Example 1 was mixed and dispersed by a sand mill, and the dispersion was used as a curing accelerator,
1.3 g of ethyl-4-methylimidazole (2E4MZ, manufactured by Shikoku Chemicals), N-phenyl- as a coupling agent
9 g of γ-aminopropyltrimethoxysilane is added,
Make a mixture. Also, a diameter of 5 μm for gap formation
Was added to 100 g of the above mixture to obtain several kinds of black sealants used in this example.

Embodiments 5, 6, and 7 Hereinafter, embodiments in which the present invention is applied to an active matrix type color liquid crystal display device will be described.

FIG. 1 is a schematic sectional view of an essential part of an example of an active matrix type color liquid crystal display device using a thin film transistor according to the present invention (namely, an end near a seal portion where a pair of substrates is bonded). It is.

SUB1 is a lower transparent glass substrate, TFT is a thin film transistor, ITO1 is a transparent pixel electrode, SUB2
Is an upper transparent glass substrate, BM is a black matrix, F
IL (R) is a red color filter, FIL (G) is a green color filter, FIL (B) is a blue color filter,
PSV1 is a protective film, ITO2 (COM) is a common transparent pixel electrode, ORI1 and ORI2 are alignment films, SL is a sealant,
SP is a spacer, LC is a liquid crystal layer, and POL1 and POL2 are polarizing plates.

The present embodiment shown in FIG. 1 is characterized in that the black matrix BM is made of a black organic resin, and the black sealant SL is provided with a light shielding property. In addition,
The optical characteristics of the black sealant SL and the black matrix BM, that is, the light shielding properties are the same.

That is, the optical density (OD value) of the black sealant SL and the black matrix BM in the visible light range (380 nm to 780 nm) was 2.0 or more. For this optical density (OD value), the transmittance is measured at intervals of 5 nm between wavelengths of 380 nm to 780 nm using a spectroscopic spectrum measuring device, and the Y value is determined by an XYZ color system (CIE1931 standard color system). Y = 0.02) and the optical density (OD value) was calculated by the following equation.
3.7, indicating a sufficient light-shielding property.

Optical density (OD value) = log ₁₀ (100 / Y) As is clear from FIG. 1, when viewed from a direction perpendicular to the substrate display surface, the black sealant SL and the black matrix BM are: Some overlap.

In this embodiment, since the black matrix BM is formed of a low-reflection colored organic resin and the black sealant SL is formed of a light-shielding material, light leakage is prevented from occurring in the seal portion. Display quality is improved. Further, since the black sealant SL and the black matrix BM have substantially the same optical characteristics, light emitted from a backlight or the like is shielded to the same extent by the seal portion and the black matrix portion. Further, when a driving circuit or the like is attached to the liquid crystal display element to form a module, masking of a seal portion by a metal frame (refer to a symbol SHD in FIG. 8 described later) or the like covering the outer peripheral portion of the liquid crystal display element becomes unnecessary. ,
A small, large-screen color liquid crystal display device having a wide display area can be obtained.

That is, in this embodiment, first, on the transparent glass substrate SUB2 of FIG. 1, first, a black matrix BM made of an organic resin such as acryl, epoxy, or polyimide resin to which carbon black or a black organic pigment is added. Was formed in a predetermined pattern, and the color filters FIL (R), (G), and (B) were formed in a predetermined pattern thereon. The color filter FIL was formed by photolithography using a photocurable negative resist to which an organic pigment matched to each color tone was added. After that, in order to prevent the elution of impurities from the colored resin, and to ensure the surface flatness, a solution of acrylic, epoxy resin, or the like is applied by spin coating, roll coating, transfer printing, or the like, and is subjected to heat treatment and cured. The protective film PSV1 was formed on the black matrix BM and the color filter FIL. Next, a transparent conductive film containing indium oxide as a main component was formed thereon by a sputtering method to form a common transparent pixel electrode ITO2, thereby producing a color filter side substrate. Next, after an alignment film ORI2 was transferred and formed on the transparent pixel electrode ITO2 of the substrate by transfer printing, a heat treatment was performed at a temperature of 180 to 220 ° C. The same heat treatment was performed after the alignment film ORI1 was formed also on the substrate on which the thin film transistor TFT serving as the opposite substrate was formed. Next, after performing an alignment treatment on both substrates, a black sealant SL was formed on one of the substrates by a screen printing method, a dispenser application method, or the like. Thereafter, solvent drying is performed at 100 ° C. for 10 minutes, and a number of spacers SP for controlling the gap between the upper and lower substrates are dispersed over the entire surface of one substrate by a known method such as dry dispersion or semi-dry dispersion. And the upper and lower glass substrates are bonded together so that the pixels
Press to apply a load of 0.5 to 1.0 kg / cm ² to form a gap.
A heat treatment was performed for a time to cure the black sealant. Next, the substrate is cut into a predetermined size, liquid crystal LC is injected from a liquid crystal injection port provided in a part of the sealant, and the injection port is sealed using a known sealing agent. A color liquid crystal display device was obtained. The gap between the substrates in the seal portion was 5 to 7 μm, and the seal width was 0.1 mm.

The obtained Examples 5, 6, and 7 and Comparative Example 3,
Aggregation Particle Size (μm) of Titanium Black Pigment Used in Liquid Crystal Display Element No. 4 and Common Transparent Pixel Electrode ITO
2. The specific resistance (Ω · cm) between the video signal electrodes (see FIGS. 4A and 4C) was measured. Table 2 below shows the results.

[0061]

[Table 2]

It was found that the liquid crystal display element in which the specific resistance between the common transparent pixel electrode ITO2 and the video signal electrode was 10 ⁷ Ω · cm or more had no contact between the upper and lower substrates. In addition, no abnormality was observed in the external terminals, wiring patterns, and the like of the TFT, and it was confirmed that there was no problem with the insulating property of the sealant itself. On the other hand, the secondary aggregate particle size is 12 μm,
In the liquid crystal display elements of Comparative Examples 3 and 4 having a thickness of 20 μm, the specific resistance is small and the insulating property is low.

As long as the resistance between the common transparent pixel electrode ITO2 and the video signal electrode is 40 MΩ or more, the problem of conduction between them does not occur. It is 100 MΩ or more in anticipation of the safety coefficient. This is because the common transparent pixel electrode IT has a contact area of 0.8 cm × 0.8 cm and a gap of the seal portion of 6.7 μm.
The specific resistance between O2 and the video signal electrode is calculated. In this embodiment, the specific resistance of the sealing agent including the sealing agent and the coloring agent is, for example, 9.6 × 10 ⁶ Ω · cm. Even if the resistance between the common transparent pixel electrode ITO2 and the video signal electrode is 100 MΩ, the specific resistance of the sealant is 10 ⁷ . Specifically, it is calculated by a calculation formula of specific resistance ρ = resistance value R × (area S / gap L). Incidentally, when the gap is 4 μm, the specific resistance becomes 1.6 × 10 ⁷ . Therefore, since the sealant itself is an insulator, the specific resistance of the colorant in the sealant may be 10 ⁶ or more. It is more preferable that the colorant be larger than the specific resistance of the sealant. The specific resistance between the common transparent pixel electrode ITO2 and the video signal electrode is 1
If 0 ⁹ Ω · cm or more, there is a conduction preventing effect it has been confirmed by the present inventors.

Table 3 below shows the particle diameter (μm), specific surface area (m ² / g), specific gravity (g / cm ³ ), and specific resistance (Ω) of each pigment of titanium black, carbon black and iron black.・ C
m), safety, and liquid crystal contamination.

[0065]

[Table 3]

As described above, according to the above embodiment, since the light-shielding property of the black sealant SL can be improved, it is possible to prevent light leakage from occurring in the seal portion, and display quality is improved. In addition, masking of the seal portion by a metal frame or the like covering the outer peripheral portion of the liquid crystal display element can be eliminated,
A small-sized and large-screen liquid crystal display device having a wide display area can be provided. Further, since the sealant SL has a high insulating property, conduction in a seal portion between the common transparent pixel electrode ITO2 and the video signal electrode can be prevented. Therefore, the common pixel electrode IT
O2 can be formed by extending to the seal portion, and ITO can be formed.
The tolerance at the time of film sputter production can be improved.

Hereinafter, an active matrix type color liquid crystal display device to which the present invention is applicable will be described.

<< Outline of Matrix Unit >> FIG. 3 is a plan view showing one pixel of an active matrix type color liquid crystal display device to which the present invention is applied and the periphery thereof. FIG. 3 is a cross-sectional view taken along section line 4-4), a left side shows a section near a panel angle, and a right side shows a section near a video signal terminal DTM to which a video signal drive circuit is connected.

As shown in FIG. 3, each pixel has two adjacent scanning signal lines (gate signal lines or horizontal signal lines) GL.
And two adjacent video signal lines (drain signal lines or vertical signal lines) DL (in a region surrounded by four signal lines). Each pixel includes a thin film transistor TFT, a transparent pixel electrode ITO1, and a storage capacitor Cadd. The scanning signal lines GL extend in the left-right direction in the figure, and a plurality of scanning signal lines GL are arranged in the up-down direction. Video signal line DL
Extend in the up-down direction and are arranged in a plurality in the left-right direction.

As shown in FIG. 4, a thin film transistor TFT and a transparent pixel electrode ITO1 are formed on the lower transparent glass substrate SUB1 side with respect to the liquid crystal layer LC, and a color filter FIL and a light shielding element are formed on the upper transparent glass substrate SUB2 side. A black matrix pattern BM is formed. A silicon oxide film SIO formed by dipping or the like is provided on both surfaces of the transparent glass substrates SUB1 and SUB2.

A light shielding film BM and a color filter FI are provided on the inner surface (the liquid crystal LC side) of the upper transparent glass substrate SUB2.
L, protective film PSV2, common transparent pixel electrode ITO2 (CO
M) and an upper alignment film ORI2 are sequentially laminated.

FIG. 5 is a block diagram showing a TFT liquid crystal display element and circuits arranged on the outer periphery thereof. The drain driver section 103 is arranged only on the lower side of the TFT liquid crystal display element (TFT-LCD), and the liquid crystal display element (TFT-L) of the XGA specification composed of 800 × 3 × 600 pixels.
A gate driver unit 104, a controller unit 101, and a power supply unit 102 are arranged on a side surface of the CD).

As described above, the drain driver section 103 is formed by bending and mounting a multilayer flexible substrate, and has a sufficiently compact design.

Controller 101 and power supply 102
Is mounted on a multilayer printed circuit board PCB. The interface board PCB on which the controller unit 101 and the power supply unit 102 are mounted is arranged on the back side of the gate driver unit 104 arranged on the outer periphery of the short side of the liquid crystal element PNL. This is because the width of the information processing apparatus (apparatus) is limited, and it is necessary to reduce the width of the module MDL as a display unit as much as possible.

As shown in FIG. 5, the thin film transistor TF
T represents two adjacent drain signal lines D and two adjacent drain signal lines D.
The gate signal line G is arranged in an intersection area with the gate signal line G.

A drain electrode of the thin film transistor TFT,
The gate electrodes are connected to a drain signal line D and a gate signal line G, respectively.

Since the source electrode of the thin film transistor TFT is connected to the pixel electrode and a liquid crystal layer is provided between the pixel electrode and the common electrode, a liquid crystal capacitor CLC is equivalently connected to the source electrode of the thin film transistor TFT. Is done.

The thin film transistor TFT becomes conductive when a positive bias voltage is applied to the gate electrode, and becomes non-conductive when a negative bias voltage is applied to the gate electrode.

A storage capacitor Ca is provided between the source electrode of the thin film transistor TFT and the previous gate signal line.
dd is connected.

It should be understood that the source electrode and the drain electrode are originally determined by the bias polarity between them, and in the circuit of this liquid crystal display device, the polarities are inverted during the operation, so that the source electrode and the drain electrode are switched during the operation. . However, in the following description, for convenience, one is fixed as a source electrode and the other is fixed as a drain electrode.

<< Planar and Cross-Sectional Structure Near the Driver IC Chip Mounting Portion >> FIG. 6 shows an FCA (flip chip) type (ie, COG (chip-on-glass) type) liquid crystal display element, for example, a transparent insulating substrate made of glass. FIG. 3 is a plan view showing a state where a driving IC is mounted on SUB1. FIG. 7 is a cross-sectional view taken along the line AA. In FIG. 6, one transparent insulating substrate SUB2 is indicated by a dashed line, but is positioned above the transparent insulating substrate SUB1 so as to overlap the effective display portion (effective screen area) AR with the seal pattern SL (see FIG. 6). The liquid crystal LC is enclosed. The electrode COM on the transparent insulating substrate SUB1 is
Transparent insulating substrate SU via conductive beads or silver paste
This wiring is to be electrically connected to the common pixel electrode pattern on the B2 side. The wiring DTM (or GTM) is
The output signal from C is supplied to the wiring in the effective display part AR. The input wiring Td supplies an input signal to the driving IC. The anisotropic conductive film ACF has an elongated shape common to a plurality of driving IC portions arranged in a line. The anisotropic conductive film ACF has an elongated shape common to an input wiring pattern portion to the plurality of driving ICs. What became AC
Paste F1 separately. Although the passivation films (protective films) PSV1 and PSV are also shown in FIG. 7, the wiring portions are covered as much as possible to prevent electrolytic corrosion, and the exposed portions are covered with the anisotropic conductive film ACF1.

Further, the periphery of the side surface of the driving IC is filled with epoxy resin or silicone resin SIL (FIG. 7).
), Protection is multiplexed.

<< Overall Configuration of Liquid Crystal Display Module >> FIG.
FIG. 2 is an exploded perspective view of the FCA mode liquid crystal display module MDL.

SHD is a shield case (also called a metal frame) made of a metal plate, WD is a display window, SPC1
4 are insulating spacers, FPC1 and 2 are bent multilayer flexible circuit boards (FPC1 is a gate side circuit board, FPC2 is a drain side circuit board), PCB is an interface circuit board, and ASB is an assembled liquid crystal display with a drive circuit board. A liquid crystal display element (also referred to as a liquid crystal display panel) in which a driving IC is mounted on one of two superposed transparent insulating substrates, GC1 and G
C2 is a rubber cushion, PRS is a prism sheet (2
), SPS is a diffusion sheet, GLB is a light guide plate, RFS is a reflection sheet, MCA is a lower case (mold case) formed by integral molding, LP is a fluorescent tube, LPC is a lamp cable, and LCT is a connection for an inverter. Connector, G
B is a rubber bush that supports the fluorescent tube LP, and the members are stacked in a vertical arrangement as shown in the figure to assemble the liquid crystal display module MDL.

<< Information Processing Apparatus Mounted with Liquid Crystal Display Module MDL >> FIG. 9 is a perspective view of a notebook personal computer or a word processor mounted with the liquid crystal display module MDL of FIG. Here, a case is shown where the inverter IV is arranged in the display unit, that is, in the inverter storage unit MI of the liquid crystal display module MDL.

The CO on the liquid crystal display element PNL of the driving IC
By adopting a multi-layered flexible substrate as the G mounting and the peripheral circuit for the drain and gate driver in the outer peripheral portion and employing the bending mounting for the drain driver circuit, the outer size can be greatly reduced as compared with the conventional case. In this example, since the drain driver peripheral circuit mounted on one side can be arranged above the display unit above the hinge of the information processing device, compact mounting is possible.

First, a signal from the information processing device is transmitted from a connector located substantially at the center of the left interface board PCB to a display control integrated circuit element (TCON) in FIG.
And the display data converted here flows to the drain driver peripheral circuit. As described above, by using the FCA method and the multilayer flexible substrate, the restriction on the outer shape of the information processing device in the lateral width can be resolved, and a small-sized information processing device with low power consumption can be provided.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention. It is. For example, the present invention is applicable to other liquid crystal display devices such as a simple matrix type.

[0089]

As described above, according to the present invention,
Since the light-shielding property of the sealant can be improved, light leakage can be prevented from occurring in the seal portion, and the display quality is improved. Further, masking of the seal portion by the frame covering the outer peripheral portion of the liquid crystal display element can be eliminated, and a small-sized and large-screen liquid crystal display device having a wide display area can be provided. In addition, since the insulating property of the sealant is high, conduction in the seal portion between the common transparent pixel electrode and the signal electrode can be prevented, and the common pixel electrode can be formed so as to extend to the seal portion. The margin of time can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an end near a seal portion of an active matrix type color liquid crystal display element according to the present invention.

FIG. 2 is a schematic configuration diagram showing a measuring system of a measuring device for measuring a specific resistance of a coloring agent for coloring a sealing agent.

FIG. 3 is a main part plan view showing one pixel of an active matrix type color liquid crystal display element to which the present invention is applied and the periphery thereof;

FIG. 4 is a diagram showing a cross section near a panel angle on the left side and a vicinity of a video signal terminal to which a video signal driving circuit is connected on the right side, with the pixel portion of the matrix at the center;

FIG. 5 is a block diagram showing an equivalent circuit of an active matrix type liquid crystal display module.

FIG. 6 is a plan view showing a state in which a driving IC is mounted on a transparent insulating substrate SUB1 of an active matrix FCA type liquid crystal display element.

FIG. 7 is a sectional view taken along the line AA in FIG. 6;

FIG. 8 is an exploded perspective view of an active matrix FCA mode liquid crystal display module.

9 is a perspective view of a notebook personal computer or a word processor on which the liquid crystal display module of FIG. 8 is mounted.

[Explanation of symbols]

SUB1: lower transparent glass substrate, TFT: thin film transistor, ITO1: transparent pixel electrode, SUB2: upper transparent glass substrate, BM: black matrix, FIL (R)
Red color filter, FIL (G): green color filter, FIL (B): blue color filter, PSV1: protective film, ITO2 (COM): common transparent pixel electrode, ORI
1, ORI2: alignment film, SL: sealant, SP: spacer, LC: liquid crystal layer, POL1, POL2: polarizing plate, S:
Sample, A, A ': electrode, B: measuring cell, C: press, D
... insulating plate, E: resistance measuring instrument.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeru Matsuyama 3300 Hayano Mobara-shi, Chiba Pref. Hitachi, Ltd. Electronic Device Division

Claims (2)

[Claims] A first substrate provided with a liquid crystal control element, a pixel electrode, and a signal electrode, and a second substrate provided with a common pixel electrode are opposed to each other with a predetermined gap therebetween; A liquid crystal display element, which is colored and adheres the two substrates with a sealant provided in a substantially frame shape around the edge between the two substrates, and seals liquid crystal between the two substrates inside the sealant. Wherein the specific resistance of the colorant is 10 ⁶ Ω · cm or more, the secondary aggregation particle size of the colorant is 10 μm or less, and the specific resistance between the signal electrode and the common pixel electrode is 10 ⁹ Ω · cm. cm or more. 2. The liquid crystal display device according to claim 1, wherein said colorant is a titanium black pigment.