JPH10133160A - Defective pixel repairing method for liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To repair a pixel defect of a liquid crystal display element and improve the quality and yield by irradiating the defective pixel of the liquid crystal display element which is sealed between transparent substrates where liquid crystal alignment layers are formed of an organic high polymer substance, and aligning liquid crystal molecules on it at right angles to the substrate surfaces of the element. SOLUTION: The liquid crystal alignment layers are formed of the organic high polymer substance on transparent electrodes provided on the couple of transparent substrate, which are put opposite each other across spacers to charge a liquid crystal material. The defective pixel of the liquid crystal display element is irradiated with light to orient liquid crystal molecules on it at right angles to the substrate surfaces of the element and repair the defective pixel. Namely, the defective pixel 9 becomes a white defect when present in the display state of the liquid crystal display element 7 having all the pixels applied with a voltage. This defective pixel 9 is irradiated selectively with the light 12 to make the array of liquid crystal molecules perpendicular to the substrate, and the element is placed in the same state with normal pixel 8 applied with the voltage to eliminate the white defect. This state is held stably even after the light irradiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for repairing a defective pixel in a liquid crystal display device, which repairs the defective pixel by irradiating the defective pixel with light in the manufacture of the liquid crystal display device. More specifically, in the manufacture of a liquid crystal display device, a pixel exhibiting a display defect is selectively irradiated with light, and liquid crystal molecules on the defective pixel are vertically aligned with respect to a substrate of the liquid crystal display device, thereby causing a display defect. The present invention relates to a method for repairing defective pixels of a liquid crystal display element for repairing a defect.

[0002]

2. Description of the Related Art Liquid crystal display devices have a low driving voltage, are light in weight and have high image quality, and are therefore being actively introduced into the field of OA equipment such as personal computers and word processors. For these applications, a twisted nematic device (hereinafter abbreviated as a TN device) in which the arrangement direction of nematic liquid crystal molecules is twisted by 90 degrees on the surfaces of a pair of electrodes with electrodes on the upper and lower sides is widely used. This TN element is roughly classified into a normally white mode in which the polarization axes of two polarizing plates are perpendicular, and a normally black mode in which the polarization axes are in the same direction. Of these, normally white mode elements are mainly used because of their small wavelength dependence.

In recent years, in order to perform matrix display, color display, and the like, a thin film diode element (hereinafter abbreviated as a TFD element) having a structure in which a switching element is connected to each pixel electrode, a thin film transistor element (hereinafter abbreviated as a TFT).
Abbreviated as element. ) Has been actively developed. In these active matrix elements, the above-described normally white mode twisted nematic configuration is generally adopted. In particular, these elements are expected to be applied to moving image display and full color display due to their high display quality.

Toward the multimedia age, liquid crystal display devices are inevitably moving toward larger screens, more pixels, and higher definition, and the number of pixels or the pixel density in liquid crystal display elements is increasing year by year. Accordingly, the rate of occurrence of display defects in pixel units also increases, and the production yield of liquid crystal display elements tends to decrease. Typical display defects in pixel units are pixel defects such as line defects and point defects, such as white defects that cause light to escape during black display, and black defects that do not transmit light during white display. . The causes of this pixel defect include disconnection and short-circuit of electrodes due to electrostatic breakdown and stress of the multilayer film,
Alternatively, an operation failure of the active element is considered. Also, in the case where dust is mixed in the TFT substrate or cell assembling process, similarly, the elements of each pixel are destroyed or the electrode connection is poor. In order to remove the minute dust, a cleaning process using pure water or an organic solvent is performed, but it is difficult to completely remove the dust. Among them, those caused by electrostatic destruction and the materials used have been overcome to some extent by introducing an electrostatic removal process and improving the material design. Have difficulty.

[0005] As a precautionary measure for preventing pixel defects,
Generally, two redundant designs on a pixel configuration and a process are performed. The former is a method of dividing a TFT into a plurality or dividing a pixel into two, and if only one is alive, it is not regarded as a defect. However, redundant TFTs and wirings increase the number of defects and reduce the aperture ratio. On the other hand, as a countermeasure in the latter process, a method in which wirings and insulating films are formed in two layers is adopted.

As another method for solving the problem of the pixel defect, a laser repairing method for correcting the pixel defect using a high energy beam such as a laser has been proposed. Laser repairing is usually performed when the TFT substrate process is completed, in which a short-circuited portion is cut or a metal is locally deposited on a disconnected portion.

Among the methods for solving the above-mentioned pixel defects, the method for cutting the short-circuited portion mainly involves evaporating the short-circuited portion generated at the time of pattern formation by using a YAG laser or a glass laser. It can also be applied when there is garbage inside. It is also expected to correct defects by irradiating a laser beam to crush and remove dust. A method of locally depositing a metal on a disconnected portion is a CV method using laser light.
This is an application of the D (chemical vapor deposition) method. Specifically, a method of irradiating a laser beam to a disconnected portion on a substrate to decompose and deposit an organic metal such as Co, Cr, W, Al, and Pt to electrically connect the disconnected portion is used. It is technically difficult to adapt to mass production.

[0008] In addition, JP-A-5-232472,
JP-A-6-130390, JP-A-6-130395
JP-A-7-64087, JP-A-7-84261
JP-A-7-209650, JP-A-7-209965
No. 1, JP-A-7-209654 and JP-A-7-23
No. 0092 and the like have proposed many methods of controlling the alignment state of a liquid crystal material by irradiating a liquid crystal display element with light.
However, the alignment state of the liquid crystal material in the light irradiating part is changed to the state in the present invention (vertical alignment) by using a method instead of the rubbing treatment or by finely adjusting the pretilt angle of the liquid crystal in the light irradiating part. ) Is completely different.

[0009] Japanese Patent Application Laid-Open No. 7-64092 discloses that
A method of forming a vertical alignment region in a light-irradiated portion has been disclosed. However, this method forms a vertical alignment region by eroding and roughening the surface of an alignment film. It is difficult to control, and the application is to prevent the occurrence of disclination lines by forming a vertical alignment region between regions having different alignment states, and the display defect repairing method of the present invention is essentially Is different.

As described above, various methods have been tried to prevent pixel defects, but at present it is still not enough, and the pixel defects have not yet been sufficiently repaired. Was.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and is intended to repair a pixel defect of a liquid crystal display device and improve the quality and the yield of the liquid crystal display device. Is provided.

[0012]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, provided a transparent electrode on a pair of transparent substrates and provided a liquid crystal made of an organic polymer substance on the transparent electrode. After forming an alignment film and assembling the element substrate obtained in this way with a spacer interposed therebetween, in a liquid crystal display element in which a liquid crystal material is sealed, light is irradiated under strong conditions such that the liquid crystal alignment film evaporates. The present inventors have found that the liquid crystal in the light-irradiated portion is vertically aligned, that this vertical alignment state is stably maintained even after light irradiation, and that the vertical alignment can repair pixel defects, and have completed the present invention.

It is presumed that the mechanism of vertical alignment of liquid crystal molecules by light irradiation is as follows. In other words, when the liquid crystal alignment film made of an organic polymer substance is irradiated with light in the absorption wavelength region, the light energy absorbed by the liquid crystal alignment film is converted into heat energy, and the irradiated portion is heated, and in some cases, the photolysis reaction As a result, decomposed and scattered substances generated by explosively breaking the bonds of atoms and molecules constituting the liquid crystal alignment film adhere to the alignment film surface, thereby reducing the surface energy of the alignment film and the surface energy of the liquid crystal. It is presumed that the liquid crystal molecules become vertically aligned as the size becomes smaller. When the surface energy of the liquid crystal alignment film before and after light irradiation was measured, it was confirmed that the surface energy of the alignment film was reduced by light irradiation, confirming this estimation. It is empirically known that when the surface energy of the liquid crystal is larger than the surface energy of the alignment film, the liquid crystal is vertically aligned, and when the surface energy is small, the liquid crystal is horizontal.

The present invention comprises the following (1) to (4). (1) A transparent electrode is provided on a pair of transparent substrates, a liquid crystal alignment film made of an organic polymer substance is formed on the transparent electrodes, and the element substrates thus obtained are assembled by facing each other via a spacer. In a liquid crystal display element in which a material is sealed, a defect image of the liquid crystal display element is irradiated with light, and the liquid crystal molecules on the liquid crystal display element are repaired by aligning the liquid crystal molecules perpendicularly to a substrate surface of the element. A method for repairing defective pixels of a liquid crystal display device.

(2) The liquid crystal alignment film has the following general formula (1):
(2) and (3)

[0016]

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(Wherein X ₁ represents an aliphatic, alicyclic, aromatic or heterocyclic carbon residue which may have a halogen atom, and X ₂ represents an oxygen atom, a sulfur atom, a halogen atom or The liquid crystal display according to the above item (1), wherein the liquid crystal display is formed from a polymer compound having one or more structural units represented by the following formula (1) representing a carbon residue which may have a cyano group: A method for repairing defective pixels of an element.

(3) The liquid crystal material has the following general formula (4)

[0019]

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(Wherein Y ₁ and Y ₂ are each independently
A hydrogen atom, a halogen atom or an alkyl group having 1 to 20 carbon atoms, and a methylene group (—CH _2- ) in the alkyl group
Is a double bond, triple bond, oxygen atom, carbonyl group (-
CO—), a sulfur atom or a silicon atom, the hydrogen atom in the alkyl group may be replaced by a halogen atom, and Z ₁ , Z ₂ and Z ₃ each independently represent a covalent bond, Represents an alkylene group of 1 to 5, wherein a methylene group (—CH ₂ —) in the alkylene group is a double bond, a triple bond, an oxygen atom, a carbonyl group (—CO—),
It may be replaced by a carboxyl group (—COO—) or a sulfur atom, the hydrogen atom in the alkylene group may be replaced by a halogen atom, and the rings A ₁ , A ₂ , A ₃ and A ₄
Is independently a 1,4-phenylene ring in which one or more hydrogen atoms may be replaced by a halogen atom,
-A cyclohexylene ring, a 1,4-cyclohexenylene ring or a 1,3-dioxane-2,5-diyl ring;
m and n represent 1 to 0. The method for repairing defective pixels of a liquid crystal display device according to the above item (1), which is a liquid crystal composition containing at least one compound represented by the formula (1).

(4) The liquid crystal material is represented by the general formulas (5), (6),
(7), (8) or (9)

[0022]

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Wherein R ₁ represents an alkyl group having 1 to 10 carbon atoms, and Y ₃ represents a fluorine atom, a chlorine atom, OCF ₃ , OC
F ₂ H, CF ₃ , CF ₂ H or CFH ₂ , L ₁ ,
L ₂ , L ₃ and L ₄ independently represent a hydrogen atom or a fluorine atom, and Z ₄ and Z ₅ independently represent —CH
₂ CH ₂₋ , —CH ＝ CH—, —C≡C—, —COO— or a covalent bond, and a represents 1 or 2. )

[0024]

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(Wherein R ₂ and R ₃ each independently represent an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and any methylene group in the alkyl group or alkenyl group) May be substituted by an oxygen atom, but two or more methylene groups are not successively substituted by an oxygen atom, and ring B and ring C are each independently 1,4-cyclohexylene or Represents 1,4-phenylene, and Z ₆ represents —C≡C—, —COO—, —CH ₂ CH _{2 —} ,
—CH ＝ CH—C≡C— or a covalent bond, and Z ₇ represents —COO— or a covalent bond. )

[0026]

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(Wherein R ₄ and R ₅ are each independently an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms. In each case, any methylene group is an oxygen atom May be replaced by
Two or more methylene groups are not continuously substituted with oxygen atoms, ring D represents 1,4-cyclohexylene or 1,4-phenylene, and ring E represents 1,4-cyclohexylene or Represents 1,4-phenylene in which one or more hydrogen atoms may be substituted by a fluorine atom, and a ring F
Represents 1,4-cyclohexylene or 1,4-phenylene, and Z ₈ and Z ₉ are each independently —COO—,
Represents a 1,2-ethylene group or a covalent bond, and Z ₁₀ represents -C
H = CH—, —C≡C—, —COO— or a covalent bond, and b represents 0 or 1. The method for repairing defective pixels of a liquid crystal display device according to the above item (1), which is a liquid crystal composition containing at least one compound represented by the formula (1).

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to an example of a method for repairing a defective pixel of a TN element in a normally white mode.

The operation principle of the normally white mode TN device is schematically shown in FIG. FIG. 1A shows the state of the pixel when no voltage is applied, and FIG. 1B shows the state of the pixel when the voltage is applied, as a pixel 1 and a pixel 4, respectively. When no voltage is applied, the liquid crystal molecules 2 in the pixel 1 have an alignment in which the alignment direction is twisted by 90 degrees between the substrates, and the light incident through the first polarizing plate 3a follows the twist of the alignment of the liquid crystal molecules. Since the polarization plane is rotated by 90 degrees, the light passes through the second polarizing plate 3b, and the pixel 1 displays white. On the other hand, in the case of the pixel 4 to which a voltage higher than the threshold voltage is applied, the twist of the alignment of the liquid crystal molecules is released and the liquid crystal molecules 5 are distorted.
Are oriented almost perpendicular to the substrate. In this state, since the optical rotatory power of the liquid crystal molecules is almost lost, the incident light passing through the first polarizing plate 6a is cut off by the second polarizing plate 6b, and the pixel 4 performs black display. That is, a black pixel can be formed on a white background by applying a voltage to the pixel. However, in the case of a defective pixel, no voltage is applied, so that the arrangement of the liquid crystal molecules does not change, which causes a problem that the pixel does not become black. In the normally white mode, if there is a defective pixel, white light is emitted on a black background in this way, so that the pixel is conspicuous.

FIG. 2 schematically shows the display state of the liquid crystal display element as elements 7, 10, 13, and 16. For example,
A normal pixel, for example, the pixel 8 in the liquid crystal display element 7, which schematically shows the display state of the display element in which voltage is applied to all the pixels, performs black display, but if a defective pixel 9 exists, the voltage is applied to the pixel. Since the voltage is not applied, the light escapes and becomes a white defect. In the display element 10 to which no voltage is applied, the entire surface of the element including the defective pixel 11 becomes white display, and such a problem does not occur.

In the present invention, such a white defect is defined as
The problem can be solved by selectively irradiating the defective pixel 9 with light so that the alignment of the liquid crystal molecules is perpendicular to the substrate. That is, by irradiating the defective pixel with light, the arrangement of the liquid crystal molecules is brought into a state similar to that of a normal pixel to which a voltage is applied, and white defects can be eliminated. This state is stably maintained after light irradiation. In the element 13 in which the voltage is applied to all the elements after the repair, the pixel 14 irradiated with the light becomes black display like the normal pixel 15, and the white defect when the voltage is applied disappears. On the other hand, in the element 16 to which no voltage is applied after the repair, a black defect is generated in a portion of the pixel 17 to which light is irradiated, but compared with the white defect in the case of the element 7 to which the voltage before the repair is applied. Not so noticeable.

As described above, the display defect can be repaired by selectively irradiating the pixel showing the display defect with light and orienting the liquid crystal material in the light-irradiated portion vertically to the substrate.

As the light used in the present invention, ultraviolet light, visible light, infrared light, or the like can be used as long as the alignment film at the light irradiation portion evaporates, and is not particularly limited. As a light source, a pulse laser beam such as a CO ₂ laser beam, a YAG laser beam, an excimer laser beam, or a continuous laser beam can be used.
Excimer laser light of a rare gas halogen such as rF, KrF, XeF, or XeCl can be used. Instead of light irradiation, an energy beam such as an electron beam, an ion beam, or an X-ray can be used. The irradiation energy of these light or energy beams is 20 to 200 m
Preferably, the output power is J and the output can be controlled stably. However, the present invention is not limited to this. The number of light irradiation pulses is preferably 5 or more. More preferably, it is 10 to 20 pulses. 5 irradiation pulses
If it is less than 3, the effect of vertically aligning the liquid crystal may be reduced. The light irradiation distance is not particularly limited, but is usually adjusted to 50 mm or less, preferably 10 to
30 mm is appropriate.

The light irradiation in the present invention may be performed before or after the liquid crystal is sealed, as long as a pixel indicating a display defect can be specified. When light irradiation is performed after liquid crystal injection, bubbles may be generated around the light irradiation part depending on the material constituting the liquid crystal element and the conditions of light irradiation. In this case, since the alignment film is more likely to evaporate in the gas phase than in the liquid crystal, it is preferable to perform light irradiation under the condition that bubbles are generated, or to perform light irradiation again after the bubbles are generated. The generated bubbles disappear after a while, so there is no particular problem.

The repair effect of the present invention is as follows. The alignment film and the dissolution / diffusion of the decomposed / scattered substance into the liquid crystal are such that the decomposed / scattered substance is easily generated by light irradiation and the surface energy of the light-irradiated portion is reduced. In the case of a combination with a liquid crystal material having a low polarity, which is unlikely to occur, the thermal stability of the vertical alignment state of the light irradiation part is particularly high.

As the liquid crystal alignment film used in the liquid crystal display device of the present invention, a normal liquid crystal alignment film can be used, but the surface energy of a polypinyl alcohol (hereinafter abbreviated as PVA) film or the like is reduced. The effect is not obtained in the case of a liquid crystal alignment film that is difficult to generate decomposition and scattering by light irradiation, such as a water-soluble liquid crystal alignment film that is difficult or an obliquely deposited SiO film.

As a material for a liquid crystal alignment film that can be suitably used in the present invention, one or more structural units represented by formulas (1), (2) and (3) are used as structural units. And high molecular compounds such as polyimide, polyamic acid, and polyamide. The polyamic acid is preferably a polymer obtained by reacting a tetracarboxylic dianhydride with a diamino compound. The polyimide is preferably a polymer in which the polyamic acid is imidized by heat or the like, and a polymer in which the polyamic acid is partially imidized may be used. A composition comprising the polyimide, the polyamic acid and the polyamide may be used.

Among the above-mentioned high molecular compounds which can be suitably used in the present invention, polyamic acid is obtained by reacting a tetracarboxylic dianhydride with a diamino compound. The compounds can be specifically illustrated.

Pyromellitic dianhydride, 3,3 ', 4
4'-biphenyltetracarboxylic dianhydride, 2,
2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride 2,3,3 ', 4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-
Benzophenonetetracarboxylic dianhydride, bis (3,
4-dicarboxyphenyl) sulfonic acid dianhydride, 1,
2,5,6-naphthalenetetracarboxylic dianhydride,
2,3,6,7-naphthalenetetracarboxylic dianhydride, dianhydride of alicyclic tetracarboxylic acid having a ring such as cyclobutane, cyclopentane, cyclohexane, cyclooctane, bicyclooctane or n-butanetetracarboxylic acid Acid dianhydride and compounds represented by the following structural formula

[0040]

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The following compounds can be specifically shown as diamino compounds. 1,1-bis [4- (4-
Aminophenoxy) phenyl] cyclohexane, 1,1
-Bis [4- (4-aminophenoxy) phenyl] -4
-Methylcyclohexane, 1,1-bis [4- (4-aminophenoxy) phenyl] -4-ethylcyclohexane, 1,1-bis [4- (4-aminophenoxy) phenyl] -4-propylcyclohexane, 1-bis [4- (4-aminophenoxy) phenyl] -4-butylcyclohexane, 1,1-bis [4- (4-aminophenoxy) phenyl] -4-pentylcyclohexane,
1,1-bis [4- (4-aminophenoxy) phenyl] -4-hexylcyclohexane, 1,1-bis [4
-(4-aminophenoxy) phenyl] -4-heptylcyclohexane, 1,1-bis [4- (4-aminophenoxy) phenyl] -4-octylcyclohexane,

2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4
-(4-aminophenoxy) phenyl] pentane, 2,
2-bis [4- (4-aminophenoxy) phenyl] hexane, 2,2-bis [4- (4-aminophenoxy)
Phenyl] heptane, 2,2-bis [4- (4-aminophenoxy) phenyl] octane, 2,2-bis [4-
(4-aminophenoxy) phenyl] nonane, 2,2-
Bis [4- (4-aminophenoxy) phenyl] decane, 2,2-bis [4- (4-aminophenoxy) phenyl] dodecane, 1,1-bis [4- (4-aminobenzyl) phenyl] cyclohexane, 1,1-bis [4-
(4-aminobenzyl) phenyl] -4-methylcyclohexane, 1,1-bis [4- (4-aminobenzyl)
Phenyl] -4-ethylcyclohexane, 1,1-bis [4- (4-aminobenzyl) phenyl] -4-propylcyclohexane, 1,1-bis [4- (4-aminobenzyl) phenyl] -4-butyl Cyclohexane, 1,
1-bis [4- (4-aminobenzyl) phenyl] -4
-Pentylcyclohexane, 1,1-bis [4- (4-
Aminobenzyl) phenyl] methane,

4,4′-diaminophenyl ether,
4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, 4,4'-di (meth-aminophenoxy) diphenylsulfone, 4,4 '-(para-amino Phenoxy) diphenyl sulfone, ortho-phenylenediamine, meta-phenylenediamine, para-phenylenediamine, benzidine, 2,2′-diaminobenzophenone, 4,4′-diaminobenzophenone, 4,4′-
Diaminodiphenyl-2,2′-propane, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,
Aromatic diamino compounds such as 2-bis [4- (4-aminophenoxy) phenyl] hexamethylpropane and alicyclic diamino compounds such as 1,4-diaminocyclohexane and 4,4'-diaminodicyclohexylmethane;

These tetracarboxylic dianhydrides and diamino compounds may be used in combination of two or more kinds.

The polyamide as an example of the polymer compound used in the present invention can be obtained by reacting a dicarboxylic acid or a dicarboxylic acid halide as an acid component with a diamino compound. Examples of the dicarboxylic acid or dicarboxylic acid halide include the following compounds.

Terephthalic acid, terephthalic acid dichloride, isophthalic acid, isophthalic acid dichloride, O-phthalic acid, O-phthalic acid dichloride, 5-hydroxyterephthalic acid, 5-hydroxyterephthalic acid dichloride, 1,4-cyclohexanedicarboxylic acid, 4,4-cyclohexanedicarboxylic acid dichloride, 4,4'-diphenylmethane dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid dichloride, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid dichloride, 4,4 ' -Diphenylsulfone dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid dichloride, 4,4'-biphenyl dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid dichloride, 4,4'-terphenyl dicarbo Acid, 4,4'
Terphenyl dicarboxylic acid dichloride, 1,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid dichloride, 2,3-naphthalenedicarboxylic acid, 2,
3-naphthalenedicarboxylic acid dichloride, 1,8-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid dichloride, 2,6-naphthalenedicarboxylic acid,
2,6-naphthalenedicarboxylic acid dichloride and the like.

On the other hand, as the diamino compound, those used at the time of producing the amic acid can be similarly shown.

The above-mentioned acid component and diamino compound can be used in combination of two or more kinds. Polyamide amic acid and polyamide imide obtained by reacting tricarboxylic acid or tricarboxylic anhydride with a diamino compound can also be shown as examples of polyamide used in the present invention. The raw material of the polymer compound for an alignment film used in the present invention is the above-described tetracarboxylic dianhydride,
It is not limited to dicarboxylic acids, dicarboxylic acid halides and diamino compounds.

As the liquid crystal material used in the liquid crystal display element of the present invention, there are widely used liquid crystal materials used for ordinary display elements, such as ordinary nematic liquid crystal, liquid crystal added with dichroic dye, ferroelectric liquid crystal. However, a liquid crystal material having a high polarity such as a cyano-based liquid crystal is not preferable because the thermal stability of the alignment state of the light-irradiated portion is poor. As a liquid crystal material that can be used in the present invention, a liquid crystal composition containing at least one compound represented by the general formula (4) is preferable. As a liquid crystal material that can be more preferably used, a liquid crystal composition containing at least one compound represented by the above general formula (5), (6), (7), (8) or (9) can be given. .

The components of the liquid crystal material may be a single component or a mixture of a plurality of components, and compounds other than the above components may be used as long as the object of the present invention is not impaired.

In order to form a liquid crystal alignment film on a substrate, the above-mentioned polyimide, polyamic acid, polyamide and the like can be formed from N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP), dimethylacetamide (hereinafter DMAc). Dimethylformamide (hereinafter, D).
It may be abbreviated as MF. ), Dimethyl sulfoxide (hereinafter sometimes abbreviated as DMS), butyl cellosolve (hereinafter sometimes abbreviated as BC), ethyl carbitol, propylene glycol monobutyl ether, 3-methyl-3-methoxybutanol 0.1 to 30% by weight, more preferably 1 to 10% by weight
A solution is applied to the substrate. As a method of coating, a brush coating method, a dip coating method, a spin coating method, a spray method, a printing method, or the like can be used. After forming a coating film on the substrate, the solvent is evaporated at 50 to 150 ° C., preferably 80 to 120 ° C. to form a liquid crystal alignment film.

In the case where the polyamic acid applied on the substrate is imidized, the temperature is preferably 150 ° C. to 400 ° C., more preferably 18 ° C.
A heat treatment is performed at 0 ° C. to 280 ° C. to cause a dehydration ring closure reaction to provide a liquid crystal alignment film. If the adhesion of the obtained polymer film to the substrate is not good, after performing a surface treatment with a silane coupling agent on the substrate surface in advance, the adhesion is improved by forming the polymer film. be able to. After the organic polymer film is formed on the substrate surface in this manner, the coated surface is rubbed in a certain direction with a cloth or the like to form a liquid crystal alignment film.

In the repair of defective pixels according to the present invention, a display element having a transparent electrode, specifically, a transparent electrode such as ITO (indium oxide-tin oxide) formed on a substrate, and a switching element connected to the transparent electrode It can be suitably used for an active-type liquid crystal display element to be used. As the switching element, a thin film diode such as Ta—Ta ₂ O ₅ —Cr or amorphous Si, or a thin film transistor such as amorphous Si or polycrystalline Si can be used. In addition, the repair method according to the present invention can also be suitably used for an element in which an insulating film is formed under the transparent electrode for the purpose of preventing elution of alkali from the substrate. The present invention can also be suitably used for display elements having conventional components of the display element, for example, a polarizing plate, a color filter film, a light transmission preventing film, and the like.

[0054]

The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to these examples.

Reference Example 1 A change in surface energy due to light irradiation was confirmed by the following test. 4,4'-diaminophenyl ether 3.46
g, 4.36 g of pyromellitic dianhydride and 0.11 g of paraaminophenyl trimethoxysilane were polymerized to obtain a polyamic acid solution. In this solution, butyl cellosolve (BC) and N-methyl-2-pyrrolidone (NMP) are added.
A polyamic acid was diluted to 3% by weight by adding a mixed solution having a weight ratio of 1: 1 with the above, and then this solution was spin-coated on a transparent glass substrate provided with an ITO electrode on one side (spinner method).
Was applied. The application conditions were 3000 rpm for 15 seconds. After the coating film was dried at 100 ° C. for 10 minutes, the temperature was raised to 200 ° C. in an air oven for one hour, and 200 ° C.
For 90 minutes to form a polyimide film having a thickness of about 600 angstroms on the substrate. The obtained polyimide film was subjected to an orientation treatment using a rubbing cloth and subjected to the following tests.

Using the above substrate, a change in surface energy due to light irradiation was performed as follows. The polyimide film obtained by the above operation was irradiated with an excimer laser beam from a direction perpendicular to the film surface using an excimer laser processing unit (C4540) manufactured by Hamamatsu Photonics KK. The irradiation energy of the excimer laser light was 50 mJ, and the oscillation wavelength and the number of irradiation pulses were 351 nm and 10 pulses, respectively. Pure water and ethylene glycol were added dropwise to the irradiated and unirradiated portions of the irradiated film, and the surface energy of the alignment film was calculated from the value of the contact angle.
The surface energy values of the light-irradiated part and the light-irradiated part were 30.2 ergcm ⁻² and 34.7 er, respectively.
gcm ^-2 , confirming that the surface energy of the film was significantly reduced by light irradiation.

Example 1 The following test was conducted to examine the orientation of the liquid crystal material in the light-irradiated part. Using the same substrate as in Reference Example 1,
Rubbing direction is parallel and opposing each other, cell thickness 6
Assemble a micron liquid crystal cell and use the following compound

[0058]

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(In the formula, the numerical value on the right side of the chemical formula indicates the weight fraction of the compound.) A nematic liquid crystal material having a negative dielectric anisotropy was sealed. A specific pixel of the element was irradiated with excimer laser light from a direction perpendicular to the substrate surface using an excimer laser processing unit (C4540) manufactured by Hamamatsu Photonics KK. The irradiation energy of the excimer laser light was 50 mJ, the oscillation wavelength and the number of irradiation pulses were 351 nm and 10 pulses, respectively.
Air bubbles were generated around the light irradiation part, but disappeared after a while. After the bubbles disappeared, a heat treatment was performed at 110 ° C. for 30 minutes, and the mixture was gradually cooled to room temperature.

The polarization state of the light-irradiated part and the light-irradiated part was observed with a polarizing microscope. FIGS. 3 and 4 show observed images in a “bright” state and a “dark” state, respectively, observed by rotating the element under crossed Nicols when no voltage is applied. Since the light irradiation units 18 and 19 were black without depending on the rotation angle of the sample stage, it was confirmed that the liquid crystal was in a vertical alignment or an isotropic phase.

After applying voltage to all pixels of the device,
Similarly, the polarization states of the light-irradiated part and the light-unirradiated part were observed with a polarizing microscope. FIG. 5 and FIG.
The images observed by a polarizing microscope in the “bright” state and the “dark” state under crossed Nicols are shown. Light irradiation units 20 and 2 in FIGS. 5 and 6 showing a state where a voltage is applied to all of the elements.
It was confirmed that Sample No. 1 changed white in response to the electric field. Assuming that the liquid crystal is vertically aligned, it is considered that a nematic liquid crystal material having a negative dielectric anisotropy rearranges so as to be parallel to the substrate when a voltage is applied. On the other hand, assuming that the liquid crystal is isotropic,
Since the liquid crystal material should not respond to the electric field, it indicates that the liquid crystal is not isotropic but has a vertical alignment.

Example 2 A test for repairing a pixel defect in a normally white mode liquid crystal element was performed as follows. A liquid crystal cell having a twist angle of 90 ° and a cell thickness of 6 μm was assembled using a substrate prepared in the same manner as in Reference Example 1 except that a thin film transistor serving as a switching element was connected to each pixel electrode.

[0063]

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(Where the numerical value on the right-hand side of the chemical formula indicates the weight fraction of the compound). An excimer laser processing unit (C454) manufactured by Hamamatsu Photonics Co., Ltd.
Using 0), an excimer laser beam was irradiated from the direction perpendicular to the substrate surface. The irradiation energy of the excimer laser light was 50 mJ, and the oscillation wavelength and the number of irradiation pulses were 351 nm and 10 pulses, respectively. Air bubbles were generated around the light irradiation part, but disappeared after a while. After the bubbles disappeared, a heat treatment was performed at 110 ° C. for 30 minutes, and the mixture was gradually cooled to room temperature.

Two polarizing plates were arranged on the element prepared by the above operation so that the polarization axis was the same as the rubbing direction.
A normally white mode liquid crystal element was manufactured. When voltage was applied to all the pixels of the device, it was confirmed that the white defect at the light-irradiated portion had disappeared and the pixel defect was repaired.

Example 3 A test for repairing a pixel defect in a normally white mode liquid crystal element was performed as follows. Dehydrated and purified NMP50
Using g as a solvent, 7.41 g of 1,1-bis [4- (4-aminobenzyl) phenyl] -4-cyclohexane and 3.69 g of pyromellitic dianhydride were reacted while cooling. One hour later, 0.11 g of paraaminophenyltrimethoxysilane was added and reacted at 20 ° C. for 1 hour. Thereafter, the reaction solution was diluted with 51.1 g of NMP to obtain a clear solution of 10% by weight of polyamic acid. The viscosity of this solution at 25 ° C. was 1870 centipoise.

This solution was mixed with a mixed solvent of BC and NMP (1:
After dilution using 1) so that the polyamic acid concentration became 3% by weight, the solution was applied by a spin coating method (spinner method) on a transparent glass substrate provided with a pixel electrode to which a thin film transistor was connected. The application conditions were 4500 rpm for 15 seconds. After the coating was dried at 100 ° C. for 10 minutes, the temperature was raised to 200 ° C. in an air oven for 1 hour,
Heat treatment was performed at 00 ° C. for 90 minutes to obtain a polyimide film having a thickness of about 600 Å on the substrate. A liquid crystal cell having a twist angle of 90 ° and a cell thickness of 6 μm is assembled using the obtained polyimide film after performing an alignment treatment using a rubbing cloth.

[0068]

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(In the formula, the numerical value on the right side of the chemical formula indicates the weight fraction of the compound.) A liquid crystal material comprising the compound represented by the formula was sealed to obtain a liquid crystal element. Pixels indicating display defects of the obtained device were irradiated with excimer laser light from a direction perpendicular to the substrate surface using an excimer laser processing unit (C4540) manufactured by Hamamatsu Photonics KK. The irradiation energy of the excimer laser light was 50 mJ, and the oscillation wavelength and the number of irradiation pulses were 351 nm and 10 pulses, respectively. Air bubbles were generated around the light irradiation part, but disappeared after a while. After the bubbles disappeared, a heat treatment was performed at 110 ° C. for 30 minutes, and the mixture was gradually cooled to room temperature.

A normally white mode liquid crystal element was manufactured by arranging two polarizing plates so that the polarization axis was in the same direction as the rubbing direction. When current was applied to the entire surface of the device, it was confirmed that the white defect in the light-irradiated portion had disappeared and the pixel defect had been repaired.

Example 4 A test for repairing a pixel defect of a normally white mode liquid crystal element was performed as follows. 2,2-bis [4- (4
[Aminophenoxy) phenyl] propane (8.06 g), pyromellitic dianhydride (4.36 g), and paraaminophenyl trimethoxysilane (0.11 g) were polymerized to obtain a polyamic acid solution. Add butyl cellosolve and N
After adding a 1: 1 mixed solution with MP to dilute the polyamic acid concentration to 3% by weight, spin coating method (spinner method) on a transparent glass substrate provided with a pixel electrode to which a thin film transistor is connected. Was applied. Application condition is 3
000 rpm for 15 seconds. 10 at 100 ° C after coating
After drying for 200 minutes, take 200 hours in an air oven for 1 hour.
The temperature was raised to 200 ° C., and a heat treatment was performed at 200 ° C. for 90 minutes to obtain a polyimide film having a thickness of about 600 Å on the substrate. A liquid crystal cell having a twist angle of 90 ° and a cell thickness of 6 μm is assembled using the obtained polyimide film after performing an alignment treatment using a rubbing cloth.

[0072]

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(Where the numerical value on the right-hand side of the chemical formula indicates the weight fraction of the compound) to obtain a liquid crystal element. Pixels indicating display defects of the obtained device were irradiated with excimer laser light from a direction perpendicular to the substrate surface using an excimer laser processing unit (C4540) manufactured by Hamamatsu Photonics KK. The irradiation energy of the excimer laser light was 50 mJ, and the oscillation wavelength and the number of irradiation pulses were 351 nm and 10 pulses, respectively. Air bubbles were generated around the light irradiation part, but disappeared after a while. After the bubbles disappeared, a heat treatment was performed at 110 ° C. for 30 minutes, and the mixture was gradually cooled to room temperature.

A normally white mode liquid crystal element was manufactured by arranging two polarizing plates so that the polarization axis was in the same direction as the rubbing direction. When current was applied to the entire surface of the device, it was confirmed that the white defect in the light-irradiated portion had disappeared and the pixel defect had been repaired.

Comparative Example 1 A test for repairing a pixel defect in a normally white mode liquid crystal element was performed as follows. 3.46 g of 4,4′-diaminophenyl ether and pyromellitic dianhydride
36 g and paraaminophenyl trimethoxysilane 0.
11 g was polymerized to obtain a polyamic acid solution. To this solution was added a mixed solution of butyl cellosolve (BC) and N-methyl-2-pyrrolidone (NMP) at a weight ratio of 1: 1 to dilute the polyamic acid concentration to 3% by weight. Was coated on a transparent glass substrate provided with an ITO electrode by a spin coating method (spinner method). The application conditions were 3000 rpm for 15 seconds. After the coating is dried at 100 ° C. for 10 minutes, it is dried in an air oven for 1 hour.
The temperature was raised to 00 ° C., and a heat treatment was performed at 200 ° C. for 90 minutes to obtain a polyimide film having a thickness of about 600 Å on the substrate. After subjecting the obtained polyimide film to an alignment treatment using a rubbing cloth, a liquid crystal cell having a twist angle of 90 ° and a cell thickness of 6 μm is assembled using the rubbing cloth.

[0076]

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(In the formula, the numerical value on the right side of the chemical formula indicates the weight fraction of the compound.) A liquid crystal material comprising a cyano-based liquid crystal compound represented by the following formula was sealed to obtain a liquid crystal element. Pixels indicating display defects of the obtained device were irradiated with excimer laser light from a direction perpendicular to the substrate surface using an excimer laser processing unit (C4540) manufactured by Hamamatsu Photonics KK. The irradiation energy of the excimer laser light was 50 mJ, and the oscillation wavelength and the number of irradiation pulses were 3 m each.
51 nm and 10 pulses. Air bubbles were generated around the light irradiation part, but disappeared after a while. After the bubbles disappeared, a heat treatment was performed at 110 ° C. for 30 minutes, and the mixture was gradually cooled to room temperature. A normally white mode liquid crystal element was manufactured by arranging two polarizing plates so that the polarization axis was in the same direction as the rubbing direction. When a voltage was applied to all the pixels of this element, it was confirmed that a white defect occurred in the light-irradiated portion and the pixel defect was not repaired.

Comparative Example 2 A test for repairing a pixel defect of a normally white mode liquid crystal element was performed as follows. A 0.3% by weight aqueous solution of polyvinyl alcohol (PVA) was applied on a transparent glass substrate provided with an ITO electrode on one side by a spin coating method (spinner method). The application conditions were 3000 rpm for 15 seconds. The coated film was dried at 150 ° C. for 30 minutes to obtain a PVA film having a thickness of about 50 Å on the substrate. P obtained
After aligning the VA film using a rubbing cloth, a liquid crystal cell having a twist angle of 90 ° and a cell thickness of 6 microns is assembled using the VA film.

[0079]

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(Where the numerical value on the right side of the chemical formula indicates the weight fraction of the compound), and a liquid crystal material comprising a liquid crystal compound represented by the formula was sealed to obtain a liquid crystal element. Pixels indicating display defects of the obtained device were irradiated with excimer laser light from a direction perpendicular to the substrate surface using an excimer laser processing unit (C4540) manufactured by Hamamatsu Photonics KK. The irradiation energy of the excimer laser light was 50 mJ, and the oscillation wavelength and the number of irradiation pulses were 351 nm and 10 pulses, respectively. Air bubbles were generated around the light irradiation part, but disappeared after a while. 110 after bubbles disappear
Heat treatment was performed at 30 ° C. for 30 minutes, and the mixture was gradually cooled to room temperature.

A normally white mode liquid crystal element was manufactured by arranging two polarizing plates so that the polarization axis was in the same direction as the rubbing direction. When a voltage was applied to all the pixels of this element, white defects occurred in the light irradiation part,
It was confirmed that the pixel defect was not repaired.

Comparative Example 3 A test for repairing a pixel defect of a normally white mode liquid crystal element was performed as follows. On the ITO side of the transparent glass substrate provided with an ITO electrode on one side, an SiO film having a thickness of about 600 Å was obtained by oblique evaporation. The deposition time was 10 minutes, and the substrate temperature and the degree of vacuum were:
The temperature was 250 ° C. and 2.5 × 10 ⁻⁵ Torr, respectively. Using this, a liquid crystal cell with a twist angle of 90 ° and a cell thickness of 6 microns is assembled.

[0083]

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(In the formula, the numerical value on the right side of the chemical formula indicates the weight fraction of the compound.) A liquid crystal material comprising a liquid crystal compound represented by the formula was sealed to obtain a liquid crystal element. Pixels indicating display defects of the obtained device were irradiated with excimer laser light from a direction perpendicular to the substrate surface using an excimer laser processing unit (C4540) manufactured by Hamamatsu Photonics KK. The irradiation energy of the excimer laser light was 50 mJ, and the oscillation wavelength and the number of irradiation pulses were 351 nm and 10 pulses, respectively. Air bubbles were generated around the light irradiation part, but disappeared after a while. 110 after bubbles disappear
Heat treatment was performed at 30 ° C. for 30 minutes, and the mixture was gradually cooled to room temperature. A normally white mode liquid crystal element was manufactured by arranging two polarizing plates so that the polarization axis was in the same direction as the rubbing direction. When a voltage was applied to all the pixels of this element, it was confirmed that white defects occurred in the light-irradiated portions and the pixel defects were not repaired.

[0085]

As described above, a pixel which shows a display defect of a liquid crystal display element is selectively irradiated with light, and the liquid crystal material in the light irradiated portion is vertically oriented with respect to the substrate, thereby effectively displaying the image. Defects can be repaired to improve product quality and yield.

[0086]

[Brief description of the drawings]

1A and 1B show the operation principle of a normally white mode TN element. FIG. 1A shows a state when no voltage is applied, and FIG. 1B shows a state when a voltage is applied.

FIG. 2 shows a principle of repairing a pixel defect in the present invention.

FIG. 3 is a view showing a polarizing microscope observation image of a sample in a “bright” state under crossed Nicols when no voltage is applied according to an example of the present invention.

FIG. 4 is a view showing a polarizing microscope observation image of a sample in a “dark” state under crossed Nicols when no voltage is applied according to an example of the present invention.

FIG. 5 is a diagram showing a polarizing microscope observation image of a sample in a “bright” state under crossed Nicols when a voltage is applied, according to an example of the present invention.

FIG. 6 is a diagram showing a polarizing microscope observation image of a sample in a “dark” state under crossed Nicols when a voltage is applied according to an example of the present invention.

[Explanation of symbols]

 1 ... pixels when no voltage is applied 2, 5 ... liquid crystal molecules 3a, 6a ... first polarizing plate 3b, 6b ... second polarizing plate 4 ... when voltage is applied Pixel 7: Element when voltage is applied before restoration 8, 15 ... Normal pixel 9, 11 ... Defective pixel 10 ... Element when no voltage is applied before restoration 12 ... Light 13. ..Elements when voltage is applied after restoration 14, 17 ... Light irradiated pixel 16 ... Elements when no voltage is applied after restoration 18,19,20,21 ... Light irradiation part

Claims (4)

[Claims] 1. After a transparent electrode is provided on a pair of transparent substrates, a liquid crystal alignment film made of an organic polymer material is formed on the transparent electrodes, and the device substrates thus obtained are assembled by facing each other via a spacer. In a liquid crystal display device in which a liquid crystal material is sealed, the defect is repaired by irradiating light to defective pixels of the liquid crystal display device and aligning liquid crystal molecules on the defective pixel perpendicular to the substrate surface of the device. A defective pixel repair method for a liquid crystal display element. 2. A liquid crystal alignment film according to the following general formulas (1), (2) and (3): (Wherein, X ₁ represents an aliphatic, alicyclic, aromatic or heterocyclic carbon residue which may have a halogen atom, and X ₂ represents an oxygen atom, a sulfur atom, a halogen atom or a cyano group. 2. The defective pixel repair of a liquid crystal display device according to claim 1, wherein the compound is formed from a polymer compound having one or more structural units represented by the following formula: Method. 3. A liquid crystal material comprising the following general formula (4): (Wherein Y ₁ and Y ₂ each independently represent a hydrogen atom, a halogen atom or an alkyl group having 1 to 20 carbon atoms;
Methylene groups in the alkyl radical (-CH _2-) is double bond, triple bond, an oxygen atom, a carbonyl group (-CO-),
A sulfur atom or a silicon atom may be replaced, a hydrogen atom in the alkyl group may be replaced by a halogen atom, and Z ₁ , Z ₂ and Z ₃ each independently represent a covalent bond or a group having 1 to 5 carbon atoms. An alkylene group; a methylene group (—CH ₂₋ ) in the alkylene group is a double bond, a triple bond, an oxygen atom, a carbonyl group (—CO—), a carboxyl group (—COO—), or a sulfur atom. And the hydrogen atom in the alkylene group may be replaced by a halogen atom, and the ring A ₁ , A ₂ , A ₃ and A ₄ may each independently have one or more hydrogen atoms replaced by a halogen atom. 1,4-phenylene ring, 1,4-cyclohexylene ring, 1,4-cyclohexenylene ring or
Represents a 3-dioxane-2,5-diyl ring, m and n are 1
To 0. 2. The method for repairing a defective pixel of a liquid crystal display device according to claim 1, wherein the method is a liquid crystal composition containing at least one compound represented by the following formula: 4. A liquid crystal material represented by the following general formulas (5), (6),
(7), (8) and (9) (Wherein, R ₁ represents an alkyl group having 1 to 10 carbon atoms;
3 is a fluorine atom, a chlorine atom, OCF ₃ , OCF ₂ H, CF
₃ , CF ₂ H or CFH ₂ , L ₁ , L ₂ , L ₃ and L ₄ independently represent a hydrogen atom or a fluorine atom, and Z ₄ and Z ₅ independently represent —CH ₂ CH ₂ -,-
CH = CH—, C≡C, —COO— or a covalent bond, and a represents 1 or 2. ) (Wherein, R ₂ and R ₃ independently of one another have 1 to 10 carbon atoms)
Represents an alkyl group or an alkenyl group having 2 to 10 carbon atoms, and any methylene group in the alkyl group or the alkenyl group may be substituted by an oxygen atom. Ring B and ring C independently represent 1,4-cyclohexylene or 1,4-phenylene, and Z ₆ represents —C≡C—, —COO—, —CH ₂ CH _2- , -CH = C
It represents H—C≡C— or a covalent bond, and Z ₇ represents COO or a covalent bond. ) (Wherein, R ₄ and R ₅ independently of one another have 1 to 10 carbon atoms)
Or an alkenyl group having 2 to 10 carbon atoms. In any case, any of the methylene groups may be substituted by an oxygen atom, but two or more methylene groups are not successively substituted by an oxygen atom,
Ring D represents 1,4-cyclohexylene or 1,4-phenylene, and ring E represents 1,4-cyclohexylene or 1,4 or more hydrogen atoms on the ring in which one or more hydrogen atoms may be substituted with a fluorine atom. -Phenylene, ring F represents 1,4-cyclohexylene or 1,4-phenylene, Z ₈ and Z ₉ independently of one another represent -COO-, 1,2-ethylene or a covalent bond; Z ₁₀ is -CH = CH-,-
It represents C−C—, —COO— or a covalent bond, and b represents 0 or 1. 2. The method for repairing a defective pixel of a liquid crystal display device according to claim 1, wherein the liquid crystal composition comprises at least one compound represented by the formula (1).