JP2012181527A - Alignment control film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alignment control film having high sensitivity to exposure.SOLUTION: In the alignment control film including polyimide and a precursor of the polyimide, the polyimide and the precursor of the polyimide contain a cyclobutane tetracarboxylic acid dianhydride derivative represented by chemical formula (1) and aromatic diamine as raw materials, and are provided with alignment control power by optical alignment treatment. (Where, at least one of Zto Zis a substituent represented by -NR, -SR, -OH, -COR, -(CH)-COOR, -CN or -NO(R is each independently a hydrogen atom or an alkyl group having 1-4 carbon atoms, and n is an integer of 0-2.), and each of others is a hydrogen atom.)

Description

  The present invention relates to an alignment control film.

  As a conventional technique, Patent Document 1 has an object to provide a liquid crystal aligning agent having a high voltage holding ratio and a low image sticking property, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride derivative and 1,4- Diaminocyclohexane, bicyclo [2.2.1] heptane-2,6-bis (methylamine), 1,3-bis (aminomethyl) cyclohexane, isophorone, or alkyl substituents of these diamines are converted to tetracarboxylic dianhydrides. Of a liquid crystal aligning agent comprising a mixture of a polyamic acid obtained as at least part of a product and a diamine compound, an imidized polymer thereof, or a mixture with other imidized polymers, wherein the proportion of amic acid bond units is 5 to 80%. The provision is disclosed. The liquid crystal aligning agent disclosed in Patent Document 1 is provided with alignment regulating force by rubbing alignment treatment.

JP 2009-48174 A

  However, since the rubbing alignment treatment includes a step of physically rubbing the organic film and the cloth, unnecessary scraps may be generated on the surface of the formed alignment film. Since the shavings cause a display defect of the display device, it is necessary to establish a clean alignment processing method that can be changed to the rubbing alignment processing, for example, a photo alignment processing method.

  Photo-alignment treatment is a method of imparting alignment regulating force to the surface of the organic coating by irradiating the surface of the organic coating formed on the substrate surface with light that is polarized almost linearly. In order to use it, it is necessary to use a liquid crystal aligning agent having high sensitivity to exposure.

  An object of the present invention is to provide an alignment control film having high sensitivity to exposure. The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

  A liquid crystal display device according to the present invention is formed on at least one substrate of a pair of substrates, at least one of which is transparent, a liquid crystal layer disposed between the pair of substrates, and an electric field applied to the liquid crystal layer. In the liquid crystal display device including an electrode group for applying a voltage and an alignment control film disposed on at least one of the pair of substrates, the alignment control film is made of polyimide and a precursor of the polyimide, and the polyimide The polyimide precursor includes a cyclobutanetetracarboxylic dianhydride derivative represented by the following chemical formula (1) and an aromatic diamine as raw materials, and the alignment control film is imparted with an alignment regulating force by a photoalignment treatment. It is characterized by being.

（但し、Ｚ^１からＺ^４のうち少なくとも一つは、−ＮＲ_２、−ＳＲ、−ＯＨ、−ＣＯＲ、−（ＣＨ_２）_ｎ−ＣＯＯＲ、−ＣＮまたは−ＮＯ_２に示す置換基（Ｒはそれぞれ独立に水素原子もしくは炭素数１から４のアルキル基、ｎは０から２の整数。）であり、その他は水素原子である。）

(However, at least one of Z ¹ to Z ⁴ is a substituent represented by —NR ₂ , —SR, —OH, —COR, — (CH ₂ ) _n —COOR, —CN or —NO ₂ (R is And each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is an integer of 0 to 2.), and the others are hydrogen atoms.)

  The aromatic diamine may contain at least one aromatic diamine selected from the group of compounds represented by the following chemical formulas (101) to (110).

（但し、Ｘはそれぞれ独立に、次に示すいずれかの構造である。：−ＣＨ_２−、−ＣＯ−、−Ｏ−、−ＮＨ−、−ＣＯ−ＮＨ−、−Ｓ−、−ＳＯ−、−ＳＯ_２−）

(Wherein, X is independently, is any of the structures shown _{below: -. CH 2 -, -} CO -, - O -, - NH -, - CO-NH -, - S -, - SO- , —SO ₂ —)

  The aromatic diamine may include two or more different aromatic diamines selected from the group of compounds represented by the chemical formulas (101) to (110).

  The tetracarboxylic dianhydride used as a raw material for the polyimide and the polyimide precursor is a 1,2,3,4-cyclobutanetetracarboxylic dianhydride derivative represented by the chemical formula (1). It is good also as containing in the ratio of mol% or more and 100 mol% or less.

  Furthermore, in the liquid crystal display device according to the present invention, the polyimide and the polyimide precursor further include a 1,2,3,4-cyclobutanetetracarboxylic dianhydride derivative represented by the following chemical formula (2) as a raw material. It is good as well.

（但し、Ｙ^１からＹ^４のうち少なくとも一つはメチル基またはメトキシ基であり、その他は水素原子である。）

(However, at least one of Y ¹ to Y ⁴ is a methyl group or a methoxy group, and the other is a hydrogen atom.)

  In the liquid crystal display device according to the present invention, the polyimide precursor may include a polyamic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms. The electrode group may be formed on only one of the pair of substrates. The pretilt angle of the liquid crystal layer may be 1 degree or less.

In the chemical formula (1), at least two of Z ¹ to Z ⁴ are —NR ₂ , —SR, —OH, —COR, — (CH ₂ ) _n —COOR, —CN, or —NO _2. (R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is an integer of 0 to 2), and the others may be hydrogen atoms.

  Further, the polyimide and the polyimide precursor may contain, as a raw material, a cyclobutanetetracarboxylic dianhydride derivative represented by two or more chemical formulas (1) having different numbers of substituted substituents.

  According to the present invention, an alignment control film having high sensitivity to exposure can be provided.

4 is a schematic cross-sectional view of the vicinity of one pixel of the liquid crystal display device according to Embodiment 1. FIG. 3 is a schematic plan view of an active matrix substrate showing a configuration near one pixel of the liquid crystal display device according to Embodiment 1. FIG. FIG. 2B is a cross-sectional view taken along line 2B shown in FIG. 2A. 2C is a cross-sectional view taken along line 2C shown in FIG. 2A. 6 is a schematic cross-sectional view of the vicinity of one pixel of a liquid crystal display device according to Example 2. FIG. 6 is a schematic plan view of an active matrix substrate showing a configuration near one pixel of a liquid crystal display device according to Example 2. FIG. FIG. 4B is a cross-sectional view taken along line 4B shown in FIG. 4A. FIG. 4B is a cross-sectional view taken along line 4C shown in FIG. 4A. 6 is a schematic cross-sectional view of the vicinity of one pixel of a liquid crystal display device according to Example 3. FIG. 6 is a schematic cross-sectional view of the vicinity of one pixel of a liquid crystal display device according to Example 4. FIG. 6 is a schematic cross-sectional view of the vicinity of one pixel of a liquid crystal display device according to Example 5. FIG. FIG. 10 is a schematic plan view of an active matrix substrate showing a configuration near one pixel of a liquid crystal display device according to Example 5.

  As a rubbing-less alignment method for solving the problems of the rubbing alignment method, a photo-alignment method by light irradiation has been proposed and studied, but has the following problems in practice. In the polymer material system in which a photoreactive group is introduced into a polymer side chain represented by polyvinyl cinnamate, the thermal stability of orientation is not sufficient, and sufficient reliability is still obtained in terms of practicality. Not in.

  Further, in this case, since the structural site that develops the alignment of the liquid crystal is considered to be a side chain portion of the polymer, it is not necessarily preferable for aligning the liquid crystal molecules more uniformly and obtaining a stronger alignment. I can not say.

  In addition, when a low-molecular dichroic dye is dispersed in a polymer, the dye itself for aligning liquid crystals is a low-molecular substance, and there is a problem in terms of thermal or light reliability from a practical viewpoint. It is left.

  The photo-alignment method using photodecomposition of cyclobutane-based polyimide is a useful method with high alignment stability, but in recent years, there has been an increasing demand for stability of alignment. In conventional cyclobutane-based polyimide materials, It has become impossible to meet the required level. In addition, cyclobutane-based polyimide requires a large amount of light for the photoreaction, and thus has a problem of low production throughput.

  An object of the present invention is to provide a liquid crystal display device including an alignment control film having high sensitivity to exposure. This solves the problem that the manufacturing margin of the alignment process is narrow, reduces the occurrence of display defects due to fluctuations in the initial alignment direction, realizes stable liquid crystal alignment, and achieves high-quality image quality with an increased contrast ratio. A liquid crystal display device is provided.

  The alignment control film in the liquid crystal display device according to the present invention comprises a polyimide and a polyimide precursor, and the polyimide and the polyimide precursor are cyclobutanetetracarboxylic dianhydride derivatives and aromatic compounds represented by the following chemical formula (1) as raw materials. The alignment control film is provided with an alignment regulating force by a photo-alignment treatment.

（但し、Ｚ^１からＺ^４のうち少なくとも一つは、−ＮＲ_２、−ＳＲ、−ＯＨ、−ＣＯＲ、−（ＣＨ_２）_ｎ−ＣＯＯＲ、−ＣＮまたは−ＮＯ_２に示す置換基（Ｒはそれぞれ独立に水素原子もしくは炭素数１から４のアルキル基、ｎは０から２の整数。）であり、その他は水素原子である。）

(However, at least one of Z ¹ to Z ⁴ is a substituent represented by —NR ₂ , —SR, —OH, —COR, — (CH ₂ ) _n —COOR, —CN or —NO ₂ (R is And each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is an integer of 0 to 2.), and the others are hydrogen atoms.)

  R may be independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n may be an integer of 0 to 2. R may be independently a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and n may be an integer of 0 to 2. R may independently be a hydrogen atom or a methyl group, and n may be an integer from 0 to 2.

  The cyclobutanetetracarboxylic dianhydride derivative represented by the chemical formula (1) used as a raw material for the polyimide constituting the alignment control film according to the present invention and its precursor is represented by the following chemical formulas (B-1) to (B-18), for example. It is shown in the compound group B shown. The compounds shown in the compound group B are merely examples, and are not limited thereto.

（但し、化合物群Ｂに示される化合物中のＲ¹はそれぞれ独立に水素原子又は炭素数１から４のアルキル基であり、ｎは０から２の整数である。）

(However, R ¹ in the compounds shown in the compound group B is each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is an integer of 0 to 2.)

  Among the above compound group B, (B-1) (B-2) (B-3) (B-4) (B-5) (B-6) (B-7) (B-8) are photoreactions. In particular, (B-1), (B-2), and (B-3) are particularly effective because of their very high photoreactivity.

That is, in the compound represented by the chemical formula (1), at least one of Z ¹ to Z ⁴ is a substituent represented by —NR ₂ (R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. It is preferable that the others are hydrogen atoms. R may be independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n may be an integer of 0 to 2. R may be independently a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and n may be an integer of 0 to 2. R may independently be a hydrogen atom or a methyl group, and n may be an integer from 0 to 2.

In the compound represented by the chemical formula (1), at least one of Z ¹ to Z ⁴ is a substituent represented by —NHR (R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) Others may be hydrogen atoms. R may be independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n may be an integer of 0 to 2. R may be independently a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and n may be an integer of 0 to 2. R may independently be a hydrogen atom or a methyl group, and n may be an integer from 0 to 2.

In the compound represented by the chemical formula (1), at least one of Z ¹ to Z ⁴ may be a substituent represented by —NH ₂ , and the other may be a hydrogen atom.

  Moreover, the polyimide which comprises the orientation control film in the display apparatus which concerns on this invention, and the precursor of the said polyimide add the cyclobutane tetracarboxylic dianhydride derivative shown by following Chemical formula (2) as a raw material to the compound group B further. Inclusion is preferred.

（但し、化学式（２）中のＹ^１からＹ^４のうち少なくとも一つはメチル基またはメトキシ基であり、その他は水素原子である。）

(However, at least one of Y ¹ to Y ⁴ in chemical formula (2) is a methyl group or a methoxy group, and the other is a hydrogen atom.)

In addition, at least two of Y ¹ to Y ^{4 in} the chemical formula (2) may be a methyl group or a methoxy group, and the other may be a hydrogen atom. In addition, at least one of Y ¹ to Y ^{4 in} the chemical formula (2) may be a methyl group, and the other may be a hydrogen atom or a methoxy group. In addition, at least two of Y ¹ to Y ^{4 in} the chemical formula (2) may be methyl groups, and the others may be hydrogen atoms or methoxy groups.

  Specific examples of the cyclobutanetetracarboxylic dianhydride derivative represented by the chemical formula (2) are shown in the compound group C represented by the following chemical formulas (C-1) to (C-6). The compounds shown in Compound Group C are merely examples, and are not limited thereto.

  The inclusion of the cyclobutanetetracarboxylic dianhydride derivative shown in the compound group C is particularly effective because the liquid crystal alignment stability is increased.

  Moreover, the polyimide which comprises the orientation control film in the display apparatus which concerns on this invention, and the precursor of the said polyimide are at least among the aromatic diamines selected from the compound group shown by following Chemical formula (101) to (110) as a raw material. It is preferable to include one kind.

（但し、Ｘはそれぞれ独立に、次に示すいずれかの構造である。：−ＣＨ_２−、−ＣＯ−、−Ｏ−、−ＮＨ−、−ＣＯ−ＮＨ−、−Ｓ−、−ＳＯ−、−ＳＯ_２−）

(Wherein, X is independently, is any of the structures shown _{below: -. CH 2 -, -} CO -, - O -, - NH -, - CO-NH -, - S -, - SO- , —SO ₂ —)

  Specific structural examples of the polyimide constituting the alignment control film according to the present invention and the aromatic diamine which is a raw material of the precursor thereof are shown in the compound group A represented by the following chemical formulas (A-1) to (A-67). These structures show examples of specific chemical structures, and are not limited to these structures.

  Among the compound groups A, (A-1) (A-4) (A-8) (A-19) (A-21) (A-22) (A-28) (A-29) (A-30) ) (A-32), (A-47) and (A-53) are particularly preferred because of their good liquid crystal alignment.

  The polyimide precursor constituting the alignment control film according to the present invention is a polyamic acid and a polyamic acid alkyl ester. As described in the following technical document 1, the polyamic acid is obtained by stirring and polymerizing a diamine compound and tetracarboxylic dianhydride in an organic solvent.

  Technical Literature 1: Japan Polyimide Study Group Latest Polyimide Co., Ltd. Issued by NTS Corporation (2002)

  Specifically, the diamine compound is dissolved in a polar amide solvent such as NMP. When approximately equimolar tetracarboxylic dianhydride and diamine compound are added to this solution and stirred at room temperature, the ring-opening addition polymerization reaction proceeds with the diamine compound as the tetracarboxylic dianhydride dissolves, A high molecular weight polyamic acid is obtained. In the case of polyamic acid ester, diester dicarboxylic acid obtained by reacting tetracarboxylic dianhydride with alcohol is reacted with chlorinating reagent such as thionyl chloride to obtain highly reactive diester dicarboxylic acid chloride. A polyamic acid alkyl ester is obtained by reacting and polycondensing the diamine compound with this.

  At this time, a copolymer polymer in which a plurality of chemical species are polymerized in one polymer chain can be obtained by mixing a plurality of raw materials of diamine compound and tetracarboxylic dianhydride.

  By mixing plural kinds of aromatic diamine components as shown in the above compound group A, the absorption wavelength range of the produced polyimide is widened, so that the spectrum of the irradiating light source can be effectively utilized and effective.

  That is, the polyimide and its precursor constituting the alignment control film according to the present invention include two or more different aromatic diamines selected from the group of compounds represented by the chemical formulas (101) to (110). Inclusion is preferred.

  The diamine used as a raw material for the polyimide precursor constituting the alignment control film according to the present invention is 50 mol% of at least one aromatic diamine selected from the compound group represented by the chemical formulas (101) to (110). From 100 mol% to 100 mol%, more preferably from 70 mol% to 100 mol%, and particularly preferably from 80 mol% to 100 mol%. By adopting such a configuration, the photoreactivity is increased and the alignment stability of the liquid crystal is improved.

  In addition, the polyimide constituting the alignment control film according to the present invention and its precursor are represented by the chemical formula (1) as the raw material, and at least of the cyclobutanetetracarboxylic dianhydride derivatives as exemplified by the compound group B It is preferable to contain 70 mol% to 100 mol%, more preferably 80 mol% to 100 mol%, and particularly preferably 90 mol% to 100 mol%. By adopting such a configuration, the photoreactivity is increased and the alignment stability of the liquid crystal is improved.

In addition, a plurality of substituents among Z ¹ to Z ^{4 in} the chemical formula (1) are —NR ₂ , —SR, —OH, —COR, — (CH ₂ ) _n —COOR, —CN, or —NO ₂ . In the case of the substituents shown (R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is an integer of 0 to 2), the photoreactivity is further increased, and the alignment stability of the liquid crystal is improved. Improves.

That is, at least two of Z ¹ to Z ^{4 in} the chemical formula (1) are —NR ₂ , —SR, —OH, —COR, — (CH ₂ ) _n —COOR, —CN, or —NO ₂ . It is preferable that each of the substituents is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms and n is an integer of 0 to 2, and the others are hydrogen atoms.

In addition, a substituent represented by —NR ₂ , —SR, —OH, —COR, — (CH ₂ ) _n —COOR, —CN, or —NO ₂ (R is independently a hydrogen atom or a carbon number of 1 to 4 Alkyl group, n is an integer of 0 to 2.) The more substituted in the chemical formula (1), the higher the photoreactivity and the better the alignment stability of the liquid crystal.

  By the way, when a cyclobutanetetracarboxylic dianhydride derivative having a structure represented by the chemical formula (1) and exemplified in the compound group B is used alone, a structure having low ring-opening addition polymerization reactivity with a diamine. In such a case, the ring-opening addition polymerization reaction may not proceed sufficiently and a high molecular weight product may not be obtained.

  Although this cannot be generally stated because it varies depending on the reaction conditions of the ring-opening addition polymerization reaction, for example, depending on the combination of the number and type of substituents contained in the structure of the cyclobutanetetracarboxylic dianhydride derivative, the ring-opening addition is performed. This is probably because the polymerization reaction does not proceed sufficiently.

  If the ring-opening addition polymerization reaction does not proceed sufficiently, the molecular weight of the formed polyimide and its precursor may be lowered, resulting in poor film formability, and as a result, there may be a problem that unevenness occurs on the film surface. However, the above problem is that a sufficiently high molecular weight polyimide and polyimide precursor can be obtained by using a mixture of a plurality of cyclobutanetetracarboxylic dianhydride derivatives having different ring-opening addition polymerization reactivity with an aromatic diamine. can get.

  For example, it is preferable that the polyimide and the polyimide precursor contain, as a raw material, a cyclobutanetetracarboxylic dianhydride derivative represented by two or more chemical formulas (1) having different numbers of substituents. The polyimide and the polyimide precursor contain cyclobutanetetracarboxylic dianhydride derivatives represented by chemical formula (1) having different numbers of substituents as raw materials, so that photoreactivity and liquid crystal orientation stability A high orientation control film can be formed.

For example, as a raw material, a polyimide and a polyimide precursor are cyclobutanetetracarboxylic dianhydride derivatives represented by chemical formula (1) having one substituent (one of Z ¹ to Z ⁴ is —NR ₂ , —SR , —OH, —COR, — (CH ₂ ) _n —COOR, —CN or —NO ₂ , wherein R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is 0 to 2), and a cyclobutanetetracarboxylic dianhydride derivative represented by chemical formula (1) having 2, 3 or 4 substituents (one of Z ¹ to Z ⁴ is —NR ₂ , —SR _{, -OH, -COR, - (CH} 2) n -COOR, a substituent shown in -CN or -NO _2, alkyl groups R each independently represent a hydrogen atom or a C 1 -C 4, n is 0 Is an integer of al 2.) And, include a can form a photoreactive, and liquid crystal alignment stability with high alignment control film.

  The polyimide constituting the alignment control film according to the present invention is characterized in that it is obtained by advancing an imidation reaction by heating or chemical imidation of a precursor polyamic acid or polyamic acid ester. A plurality of polyimide precursors may be mixed, for example, a mixture of polyamic acid and polyamic acid ester may be used.

  In this case, the imidization reaction does not necessarily have to proceed 100%, preferably 50% to 100% of the whole, more preferably 60% to 95%, and even more preferably 70%. To 90%. The higher the degree of progress of the imidization reaction, the better the photoalignment and the higher the alignment stability of the liquid crystal. However, if it is too high, the specific resistance of the alignment control film increases, which is not preferable in terms of electrical characteristics.

  The alignment control film according to the present invention can be used by blending a material having a low specific resistance. At this time, the specific resistance of the orientation control film can be reduced, and it is effective because seizure hardly occurs. The material having a low specific resistance value may be another polymer having high electrical conductivity mixed with polyimide and its precursor, or the raw material of polyimide and its precursor may have a carbon number of 2 or more. An aromatic diamine having no chain component may be used.

  In addition, it is desirable that the molecular weight of the polyimide constituting the alignment control film is high, and polyamic acid alkyl ester is more preferable because it does not cause a decrease in molecular weight upon heating, unlike polyamic acid, and thus the alignment stability of liquid crystal is increased.

  When the cyclobutane-based polyimide is irradiated with light, the ring structure of cyclobutane is cleaved, and a photodecomposition reaction in which a maleimide terminal is generated occurs. The higher the reaction rate of this photodecomposition reaction, the more the reaction proceeds with a smaller amount of light.

  However, the conventional cyclobutane polyimide has a low photoreaction efficiency and is insufficient in the production process. The inventors have found that the photolysis reaction proceeds very quickly when certain substituents are introduced into the cyclobutane ring. The cyclobutane-based polyimide according to the present invention has the characteristics that the photoreaction efficiency is very high, so that the throughput is fast and the alignment stability is also excellent.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. An example of the alignment control film according to the present invention used in these examples is shown, and similar effects have been confirmed for other structures. Hereinafter, a substrate on which an active element such as a thin film transistor is formed is referred to as an active matrix substrate. In addition, when the counter substrate has a color filter, this is also referred to as a color filter substrate. In the present invention, the desired contrast as a target is 500: 1 or more, and the time required for eliminating the target afterimage is preferably within 5 minutes. The time for eliminating the afterimage is determined by a method defined in the following embodiment.

[Example 1]
FIG. 1 is a schematic cross-sectional view of the vicinity of one pixel of the liquid crystal display device according to the first embodiment. FIG. 2 is a schematic plan view of an active matrix substrate showing a configuration in the vicinity of one pixel of the liquid crystal display device according to the first embodiment. 2A is a schematic plan view of an active matrix substrate showing a configuration in the vicinity of one pixel of the liquid crystal display device according to Example 1. FIG. FIG. 2B is a cross-sectional view taken along line 2B shown in FIG. 2A. 2C is a cross-sectional view taken along line 2C shown in FIG. 2A. FIG. 1 corresponds to a part of a cross section taken along line 2B shown in FIG. 2A.

  2B and FIG. 2C schematically show the configuration of the main part, and do not correspond one-to-one to the cut portions of the 2B line and the 2C line in FIG. 2A. For example, in FIG. 2B, the semiconductor film 116 is not shown, and in FIG. 2C, only one through hole 118 that connects the common electrode 103 and the common wiring 120 is shown.

  In this embodiment, a scanning wiring (gate electrode) 104 and a common electrode wiring (common wiring) 120 made of Cr (chromium) are arranged on a glass substrate 101 as an active matrix substrate. A gate insulating film 107 made of silicon nitride is formed so as to cover 120.

  A semiconductor film 116 made of amorphous silicon or polysilicon is disposed on the gate electrode 104 through a gate insulating film 107 so as to function as an active layer of a thin film transistor (TFT) 115 as an active element. In addition, a signal wiring (drain electrode) 106 and a pixel electrode (source electrode) 105 made of Cr / Mo (chromium / molybdenum) are arranged so as to overlap a part of the pattern of the semiconductor film 116 and cover all of them. A protective insulating film 108 made of silicon nitride is formed.

  In addition, as shown in FIG. 2C, the common electrode 103 connected to the common wiring 120 through the through hole 118 formed through the gate insulating film 107 and the protective insulating film 108 is an overcoat layer (organic protective film) 112. Is placed on top. As shown in FIG. 2A, the common electrode 103 led out from the common wiring 120 through the through hole 118 is formed so as to face the pixel electrode 105 in the area of one pixel in plan view. Yes.

  In this embodiment, the pixel electrode 105 is arranged in a lower layer of the protective insulating film 108 below the organic protective film 112, and the common electrode 103 is arranged on the organic protective film 112. One pixel is configured in a region sandwiched between the plurality of pixel electrodes 105 and the common electrode 103. An alignment control film 109 is formed on the surface of the active matrix substrate in which the unit pixels configured as described above are arranged in a matrix, that is, on the organic protective film 112 on which the common electrode 103 is formed.

  On the other hand, as shown in FIG. 1, a color filter layer 111 is arranged on a glass substrate 102 constituting a counter substrate so as to be divided for each pixel by a light shielding film (black matrix) 113. The film 113 is covered with an organic protective film 112 made of a transparent insulating material. Further, an alignment control film 109 is also formed on the organic protective film 112 to constitute a color filter substrate.

  These alignment control films 109 are provided with liquid crystal alignment capability by irradiation with ultraviolet linearly polarized light extracted using a pile polarizer with a quartz plate laminated using a high-pressure mercury lamp as a light source.

  A glass substrate 101 constituting an active matrix substrate and a glass substrate 102 constituting a color filter substrate are arranged to face each other on the surface of the alignment control film 109, and a liquid crystal layer (liquid crystal composition) composed of liquid crystal molecules 110a therebetween. Layer) 110b is disposed. A polarizing plate 114 is formed on each of the outer surfaces of the glass substrate 101 constituting the active matrix substrate and the glass substrate 102 constituting the color filter substrate.

  As described above, an active matrix liquid crystal display device (TFT liquid crystal display device) using a thin film transistor (TFT) is configured. In this TFT liquid crystal display device, the liquid crystal molecules 110a constituting the liquid crystal composition layer 110b are aligned in substantially parallel to the surfaces of the glass substrates 101 and 102 that are arranged to face each other when no electric field is applied. Homogeneous alignment is performed in a state of being directed to the initial alignment direction.

  Here, when a voltage is applied to the gate electrode 104 to turn on the TFT 115, an electric field 117 is applied to the liquid crystal composition layer 110b due to a potential difference between the pixel electrode 105 and the common electrode 103, and the dielectric property of the liquid crystal composition layer 110b. The liquid crystal molecules 110a constituting the liquid crystal composition layer 110b change its direction to the electric field direction by the interaction between the anisotropy and the electric field. At this time, display can be performed by changing the light transmittance of the liquid crystal display device by the refractive anisotropy of the liquid crystal composition layer 110 b and the action of the polarizing plate 114.

  The organic protective film 112 may be made of a thermosetting resin such as an acrylic resin, an epoxy acrylic resin, or a polyimide resin that is excellent in insulation and transparency. In addition, a photocurable transparent resin may be used as the organic protective film 112, or an inorganic material such as a polysiloxane resin may be used. Furthermore, the organic protective film 112 may also serve as the alignment control film 109.

  As described above, according to the present embodiment, the liquid crystal alignment control ability of the alignment control film 109 is not a rubbing alignment process by directly rubbing with a buff cloth, but a non-contact photo-alignment method is used. Therefore, uniform alignment can be imparted over the entire display area.

  In general, in the IPS system, unlike the vertical electric field system represented by the conventional TN system, the interface tilt with the substrate surface is not necessary in principle, and it is known that the viewing angle characteristics are better as the interface tilt angle is smaller. In addition, a small interface tilt angle is desirable also in the photo-alignment control film, and in particular, by setting it to 1 degree or less, it is effective because the color change and brightness change due to the viewing angle of the liquid crystal display device can be greatly suppressed. .

Next, formation of an alignment control film using a rubbing-less alignment method for a liquid crystal alignment control film will be described as a method for manufacturing the liquid crystal display device of this embodiment. The flow of the alignment control film forming process according to this embodiment is as follows (1) to (4).
(1) Coating / formation of orientation control film (forms a uniform coating over the entire display area)
(2) Imidization firing of orientation control film (promotes removal of varnish solvent and high heat resistance polyimide)
(3) Liquid crystal alignment ability imparted by polarized irradiation (uniform orientation ability is imparted to the display area)
(4) Promotion / stabilization of alignment ability by (heating, infrared irradiation, far infrared irradiation, electron beam irradiation, radiation irradiation)

The alignment control film is formed through the above four-stage process, but is not limited to the order of the above processes (1) to (4). In the following cases (a) and (b) Further effects are expected.
(A) By processing the above (3) and (4) so as to overlap in time, the alignment control film can be formed more effectively by accelerating the provision of liquid crystal alignment ability and inducing a crosslinking reaction. It becomes.
(B) When heating (4) above, infrared irradiation, far-infrared irradiation, etc. are used, the above process (4) can be achieved by temporally overlapping (2), (3) and (4). It is also possible to serve as the imidization process (2), and an alignment control film can be formed in a short time.

  Next, a specific manufacturing method of this embodiment will be described. As the glass substrate 101 constituting the active matrix substrate and the glass substrate 102 constituting the color filter substrate, a glass substrate having a thickness of 0.7 mm and a polished surface is used. A thin film transistor 115 formed on the glass substrate 101 includes a pixel electrode (source electrode) 105, a signal wiring (drain electrode) 106, a scanning wiring (gate electrode) 104, and amorphous silicon 116.

  The scanning wiring 104, the common electrode wiring 120, the signal wiring 106, and the pixel electrode 105 were all formed by patterning a chromium film, and the distance between the pixel electrode 105 and the common electrode 103 was 7 μm. For the common electrode 103 and the pixel electrode 105, a chromium film having a low resistance and easy patterning is used. However, a transparent electrode can be formed by using an ITO film to achieve higher luminance characteristics. It is.

  The gate insulating film 107 and the protective insulating film 108 were made of silicon nitride, and the film thicknesses were each 0.3 μm. An acrylic resin was applied thereon, and a transparent and insulating organic protective film 112 was formed by heat treatment at 220 ° C. for 1 hour.

  Next, as shown in FIG. 2C, through holes 118 were formed up to the common electrode wiring 120 by photolithography and etching, and the common electrode 103 connected to the common electrode wiring 120 was formed by patterning.

  As a result, in the unit pixel (one pixel), as shown in FIG. 2A, the pixel electrode 105 is arranged between the three common electrodes 103, and the number of pixels is 1024 × 3 (R, G, (Corresponding to B) An active matrix substrate having 1024 × 3 × 768 pieces composed of signal wirings 106 and 768 scanning wirings 104 was formed.

  In this example, as the orientation control film 109, various polyamic acids 1 to 5 synthesized with the raw material compositions shown in Table 1 below were synthesized, and five liquid crystal display devices were produced using these orientation control films. Polyamic acid was prepared as a varnish having a resin concentration of 5% by weight, DMAC 60% by weight, γ-butyrolactone 20% by weight, and butyl cellosolve 15% by weight, printed on an active matrix substrate, imidized by heat treatment, and an imidization rate of about An orientation control film 109 made of dense polyimide and polyamic acid with a thickness of about 110 nm and 80% was formed.

Similarly, the same polyamic acid amide varnish is printed on the surface of the other glass substrate 102 on which ITO is formed, and an orientation control film 109 made of dense polyimide and polyamic acid having an imidization ratio of about 80% and about 110 nm is formed. Formed. In order to impart liquid crystal alignment ability to the surface, the alignment control film 109 was irradiated with polarized UV (ultraviolet) light. A high-pressure mercury lamp is used as a light source, UV light in the range of 240 nm to 320 nm is extracted through an interference filter, and is converted into linearly polarized light with a polarization ratio of about 10: 1 using a pile polarizer with a quartz substrate laminated. Irradiation was performed with an irradiation energy of 5 J / cm ² . As a result, it was found that the alignment direction of the liquid crystal molecules on the surface of the alignment control film was orthogonal to the polarization direction of the irradiated polarized UV light.

  Next, these two glass substrates 101 and 102 are opposed to each other with the surface having the alignment control film 109 having the liquid crystal alignment ability, and spacers made of dispersed spherical polymer beads are interposed therebetween, and the peripheral portion. A sealant was applied to the liquid crystal display panel, and a liquid crystal display panel (hereinafter also referred to as “cell”) to be a liquid crystal display device was assembled. The liquid crystal alignment directions of the two glass substrates 101 and 102 were substantially parallel to each other. This cell has a positive dielectric anisotropy Δε, a value of 10.2 (1 kHz, 20 ° C.), a refractive index anisotropy Δn of 0.075 (wavelength 590 nm, 20 ° C.), and a torsional elastic constant K2. Was 7.0 pN and nematic liquid crystal composition A having a nematic-isotropic phase transition temperature T (N-I) of about 76 ° C. was injected in a vacuum and sealed with a sealing material made of an ultraviolet curable resin. A liquid crystal panel having a liquid crystal layer thickness (gap) of 4.2 μm was produced.

  The retardation (Δn · d) of this liquid crystal display panel is about 0.31 μm. Δn · d is preferably in a range of 0.2 μm ≦ Δn · d ≦ 0.5 μm. If this range is exceeded, there is a problem that white display is colored. Further, a homogeneous alignment liquid crystal display panel was prepared using the same alignment control film and liquid crystal composition used in this panel, and the pretilt angle of the liquid crystal was measured using a crystal rotation method. Showed the degree. This liquid crystal display panel was sandwiched between two polarizing plates 114, and the polarizing transmission axis of one polarizing plate was set substantially parallel to the liquid crystal alignment direction, and the other was arranged so as to be orthogonal thereto. Thereafter, a drive circuit, a backlight, and the like were connected to form a module, and an active matrix liquid crystal display device was obtained. In this embodiment, the normally closed characteristic is such that dark display is performed at a low voltage and bright display is performed at a high voltage.

  Next, when the display quality of the five liquid crystal display devices according to this example was evaluated, a high-quality display with a contrast ratio of 500 to 1 was confirmed, and a wide viewing angle during halftone display was confirmed. The contrast ratio of the liquid crystal display device using the diamine compound (A-1) (A-19) (A-21) exceeded 600: 1, and the display quality was particularly good.

  In addition, in order to quantitatively measure image printing and afterimages of the five liquid crystal display devices according to this example, evaluation was performed using an oscilloscope combined with a photodiode. First, the window pattern is displayed on the screen at the maximum luminance for 10 hours, and then the halftone display in which the afterimage is most noticeable. Here, the entire surface is switched so that the luminance is 10% of the maximum luminance, and the edge of the window pattern is displayed. The time until the pattern disappeared was evaluated as the afterimage relaxation time. However, the afterimage relaxation time allowed here is 5 minutes or less. As a result, in the operating temperature range (0 ° C. to 50 ° C.), the afterimage relaxation time is 5 minutes or less, and even in visual image quality afterimage inspection, there is no image burn-in and display unevenness due to afterimage, and high display characteristics. was gotten.

[Comparative Example 1]
In the alignment control films 1 to 5, when the same liquid crystal display device was produced by using tetracarboxylic dianhydride as a raw material for the alignment control films 1 to 5, the irradiation energy exhibited the same display characteristics as in Example 1. 6 J / cm ² or more was required.

[Example 2]
FIG. 3 is a schematic cross-sectional view of the vicinity of one pixel of the liquid crystal display device according to the second embodiment. FIG. 4A is a schematic plan view of an active matrix substrate showing a configuration near one pixel of the liquid crystal display device according to the second embodiment. FIG. 4B is a cross-sectional view taken along line 4B shown in FIG. 4A. FIG. 4C is a cross-sectional view taken along line 4C shown in FIG. 4A.

  4A and 4B are schematic views of an active matrix substrate for explaining the configuration of the vicinity of one pixel of the liquid crystal display device according to the present embodiment. FIG. 4A is a plan view, and FIG. 4B is a cross section taken along line 4B shown in FIG. 4C shows a cross-sectional view along line 4C in FIG. 4A. 3 corresponds to a part of a cross section taken along line 4B shown in FIG. 4A.

  4B and FIG. 4C schematically show the main part configuration with emphasis, and do not correspond one-to-one with the cut portions of the 4B line and the 4C line in FIG. 4A. For example, the semiconductor film 116 is not shown in FIG. 4B.

  In the present embodiment, a gate electrode 104 made of Cr and a common electrode wiring 120 are arranged on a glass substrate 101 constituting an active matrix substrate, and a gate made of silicon nitride so as to cover the gate electrode 104 and the common electrode wiring 120. An insulating film 107 is formed. A semiconductor film 116 made of amorphous silicon or polysilicon is disposed over the gate electrode 104 with a gate insulating film 107 interposed therebetween, and functions as an active layer of the thin film transistor 115 which is an active element.

Further, a drain electrode 106 made of chromium / molybdenum and a source electrode (pixel electrode) 105 are arranged so as to overlap a part of the pattern of the semiconductor film 116, and a protective insulating film 108 made of silicon nitride is formed so as to cover all of them. Is formed. An organic protective film 112 is disposed on the protective insulating film 108. The organic protective film 112 is made of a transparent material such as an acrylic resin, for example. The pixel electrode 105 is composed of a transparent electrode such as ITO (In ₂ O ₃ : Sn). The common electrode 103 is connected to the common electrode wiring 120 through a through hole 118 that penetrates the gate insulating film 107, the protective insulating film 108, and the organic protective film 112.

  When an electric field for driving the liquid crystal is applied, the common electrode 103 that forms a pair with the pixel electrode 105 is formed so as to surround a region of one pixel in plan view. The common electrode 103 is disposed on the organic protective film 112. The common electrode 103 is disposed so as to hide the drain electrode 106, the scanning wiring 104, and the thin film transistor 115 which is an active element when viewed from above, and includes a light shielding layer that shields the semiconductor film 116 from light. Also serves as.

  On the surface of the glass substrate 101 constituting the active matrix substrate in which the unit pixels (one pixel) configured as described above are arranged in a matrix, that is, on the organic protective film 112 and the common electrode 103 formed thereon. The alignment control film 109 is formed. On the other hand, the alignment control film 109 is also formed on the organic protective film 112 formed on the color filter layer 111 on the glass substrate 102 constituting the counter substrate.

  Here, in the same manner as in Example 1, the alignment control film 109 is provided with liquid crystal alignment ability by irradiation with ultraviolet linearly polarized light extracted using a pile polarizer having a quartz plate laminated using a high-pressure mercury lamp as a light source. ing.

  And the glass substrate 101 and the opposing glass substrate 102 are opposingly arranged by the formation surface of the alignment control film 109, and the liquid crystal composition layer 110b comprised by the liquid crystal molecule 110a is arrange | positioned among these. A polarizing plate 114 is formed on each of the outer surfaces of the glass substrate 101 and the counter glass substrate 102.

  As described above, also in this embodiment, the pixel electrode 105 is disposed under the organic protective film 112 and the protective insulating film 108 as in the first embodiment described above. The common electrode 103 is arranged on the top. Further, when the electric resistance of the common electrode 103 is sufficiently low, the common electrode 103 can also serve as the common electrode wiring 120 formed in the lowermost layer. In that case, the formation of the common electrode wiring 120 arranged in the lowermost layer and the processing of the through hole 118 associated therewith can be omitted.

  In this embodiment, as shown in FIG. 4A, one pixel is formed by a region surrounded by a common electrode 103 formed in a lattice shape, and one pixel is divided into four regions together with the pixel electrode 105. Has been placed. In addition, the pixel electrode 105 and the common electrode 103 facing the pixel electrode 105 have a zigzag bent structure in which the pixel electrode 105 and the common electrode 103 are arranged in parallel with each other, and one pixel forms two or more subpixels. As a result, the color tone change in the plane is offset.

  Next, a method for manufacturing the liquid crystal display device according to this embodiment will be described. As the glass substrates 101 and 102, glass substrates having a thickness of 0.7 mm and polished surfaces are used. The thin film transistor 115 includes a pixel electrode (source electrode) 105, a signal wiring (drain electrode) 106, a scanning wiring (gate electrode) 104, and amorphous silicon 116. The scanning wiring 104 is patterned with an aluminum film, the common electrode wiring 120 and the signal wiring 106 are patterned with a chrome film, and the pixel electrode 105 is patterned with an ITO film. As shown in FIG. The electrode wiring pattern was bent in a zigzag pattern. At that time, the angle of bending was set to 10 degrees. The gate insulating film 107 and the protective insulating film 108 were made of silicon nitride, and the film thicknesses were each 0.3 μm.

  Next, as shown in FIG. 4C, through holes 118 are formed in a cylindrical shape having a diameter of about 10 μm up to the common electrode wiring 120 by photolithography and etching, and an acrylic resin is applied on the through holes 118 at 220 ° C. The organic protective film 112 having a dielectric constant of about 4 having a dielectric constant of about 4 was formed to a thickness of about 1 μm by heat treatment for 1 hour. The organic protective film 112 flattened the unevenness due to the step of the pixel electrode 105 in the display region, and flattened the unevenness of the step at the boundary portion of the color filter layer 111 between adjacent pixels.

  Thereafter, the through-hole 118 was etched again to a diameter of about 7 μm, and the common electrode 103 connected to the common electrode wiring 120 was formed by patterning the ITO film thereon. At that time, the distance between the pixel electrode 105 and the common electrode 103 was set to 7 μm. Further, the common electrode 103 is formed in a lattice shape so as to cover the upper part of the signal wiring 106, the scanning wiring 104, and the thin film transistor 115 so as to surround the pixel, and also serves as a light shielding layer.

  As a result, in the unit pixel, as shown in FIG. 4A, the pixel electrode 105 is arranged between the three common electrodes 103, and the number of pixels is 1024 × 3 (corresponding to R, G, B). As a result, an active matrix substrate having 1024 × 3 × 768 pieces of the signal wirings 106 and 768 scanning wirings 104 was obtained.

  In this example, as the alignment control film 109, various polyamic acid t-butyl esters 1 to 3 synthesized with the raw material composition shown in Table 2 below were synthesized, and three liquid crystal display devices were formed using these alignment control films. Produced. Polyamic acid t-butyl ester was prepared into a varnish having a resin content concentration of 5% by weight, DMAC 60% by weight, γ-butyrolactone 20% by weight, butyl cellosolve 15% by weight, printed on an active matrix substrate, imidized by heat treatment, An orientation control film 109 made of dense polyimide and polyamic acid t-butyl ester having an imidization ratio of about 90% and a film thickness of about 120 nm was formed.

As the alignment treatment method, the same polarized UV as in Example 1 was irradiated with an irradiation energy of 1.5 J / cm ² .

  Next, a sealant is applied to the peripheral portion of these two glass substrates 101 and 102 with the surfaces having the respective orientation control films facing each other and interposing spacers made of dispersed spherical polymer beads. The liquid crystal display panel was assembled. The liquid crystal alignment directions of the two glass substrates 101 and 102 were substantially parallel to each other.

  This liquid crystal display panel has a positive dielectric anisotropy Δε and a value of 10.2 (1 kHz, 20 ° C.), a refractive index anisotropy Δn of 0.075 (wavelength 590 nm, 20 ° C.), and a torsional elastic constant K2. Was 7.0 pN and nematic liquid crystal composition A having a nematic-isotropic phase transition temperature T (N-I) of about 76 ° C. was injected in a vacuum and sealed with a sealing material made of an ultraviolet curable resin. A liquid crystal panel having a liquid crystal layer thickness (gap) of 4.2 μm was produced. The retardation (Δnd) of this panel is about 0.31 μm.

  Further, a homogeneous alignment liquid crystal display panel was prepared using the same alignment control film and liquid crystal composition used in this liquid crystal display panel, and the pretilt angle of the liquid crystal was measured by using the crystal rotation method. . Showed 2 degrees. This panel was sandwiched between two polarizing plates 114, and the polarizing transmission axis of one polarizing plate was made substantially parallel to the liquid crystal alignment direction, and the other was arranged so as to be orthogonal thereto. Thereafter, a drive circuit, a backlight, and the like were connected to form a module, and an active matrix liquid crystal display device was obtained. In this embodiment, the normally closed characteristic is such that dark display is performed at a low voltage and bright display is performed at a high voltage.

  Next, when the display quality of the three liquid crystal display devices according to this example was evaluated, a high-quality display with a high aperture ratio and a contrast ratio of 500: 1 was confirmed as compared with the liquid crystal display device of example 1. In addition, a wide viewing angle during halftone display was also confirmed. The contrast ratio of the liquid crystal display device containing 60 mol% or more of the diamine compounds (A-1) and (A-19) exceeded 600: 1, and the display quality was particularly good. Further, in the same manner as in Example 1, when the image printing and afterimage relaxation time of this liquid crystal display device were quantitatively evaluated, the afterimage relaxation time was 5 minutes or less in the operating temperature range of 0 ° C to 50 ° C. Even in visual image quality afterimage inspection, no image burning or display unevenness due to afterimage was observed, and high display characteristics equivalent to those of Example 1 were obtained.

[Example 3]
FIG. 5 is a schematic cross-sectional view of the vicinity of one pixel of the liquid crystal display device according to the third embodiment. In the drawing, the same reference numerals as those in the drawings of the respective embodiments described above correspond to the same functional parts. As shown in FIG. 5, in this embodiment, the pixel electrode 105 disposed under the protective insulating film 108 is pulled up on the organic protective film 112 through the through hole 118 and disposed in the same layer as the common electrode 103. In this configuration, the voltage for driving the liquid crystal can be further reduced.

  In the TFT liquid crystal display device configured as described above, when no electric field is applied, the liquid crystal molecules 110a constituting the liquid crystal composition layer 110b are in a state substantially parallel to the surfaces of the glass substrates 101 and 102 that are arranged to face each other. Homogenous alignment is performed in a state in which the initial alignment direction defined by the alignment treatment is directed. Here, when a voltage is applied to the gate electrode 104 to turn on the thin film transistor 115, an electric field 117 is applied to the liquid crystal composition layer 110 b due to a potential difference between the pixel electrode 105 and the common electrode 103, and the dielectric property of the liquid crystal composition. Due to the interaction between the anisotropy and the electric field, the liquid crystal molecule 110a changes its direction in the electric field direction. At this time, display can be performed by changing the light transmittance of the liquid crystal display device by the refractive anisotropy of the liquid crystal composition layer 110 b and the action of the polarizing plate 114.

  Hereinafter, a method for manufacturing the liquid crystal display device according to this embodiment will be described. As the glass substrates 101 and 102, glass substrates having a thickness of 0.7 mm and polished surfaces are used. The thin film transistor 115 includes a pixel electrode (source electrode) 105, a signal wiring (drain electrode) 106, a scanning wiring (gate electrode) 104, and amorphous silicon 116. The scanning wiring 104 was formed by patterning an aluminum film, and the common electrode wiring 120, the signal wiring 106, and the pixel electrode 105 were formed by patterning a chromium film. The gate insulating film 107 and the protective insulating film 108 were made of silicon nitride, and the film thicknesses were each 0.3 μm. An acrylic resin was applied thereon, and a transparent and insulating organic protective film 112 having a dielectric constant of about 4 was formed to a thickness of about 1.0 μm by heat treatment at 220 ° C. for 1 hour. The organic protective film 112 flattened the unevenness due to the step of the pixel electrode 105 in the display area, and flattened the unevenness between the adjacent pixels.

  Next, as shown in FIG. 5, through holes 118 are formed in a cylindrical shape with a diameter of about 10 μm up to the source electrode 105 by photolithography and etching, and the pixel electrode 105 connected to the source electrode 105 is formed thereon. An ITO film was formed by patterning. The common electrode wiring 120 was also formed with a through hole in a cylindrical shape with a diameter of about 10 μm, and the ITO film was patterned thereon to form the common electrode 103. At that time, the interval between the pixel electrode 105 and the common electrode 103 was set to 7 μm, and the electrode wiring pattern other than the scanning wiring 104 was formed in a zigzag bent electrode wiring pattern. At that time, the angle of bending was set to 10 degrees. Further, the common electrode 103 is formed in a lattice shape so as to cover the upper portion of the signal wiring 106, the scanning wiring 104, and the thin film transistor 115 so as to surround the pixel, and also serves as a light shielding layer.

  As a result, except that two types of through holes are formed in the unit pixel, the pixel electrode 105 is arranged between the three common electrodes 103 in substantially the same manner as in the second embodiment. Formed 1024 × 3 × 768 (corresponding to R, G, B) signal wirings 106 and 768 scanning wirings 104 to form 1024 × 3 × 768 active matrix substrates.

  As described above, a liquid crystal display device was manufactured as shown in FIG. 5 in the same manner as in Example 2 except for the pixel structure and the alignment control film to be used.

  In this example, as the orientation control film 109, various polyamic acid ethyl esters 1 to 3 synthesized with the raw material composition shown in Table 3 below were synthesized, and three liquid crystal display devices were produced using these orientation control films. . Polyamide acid ethyl ester was prepared into a varnish of 5% by weight of resin content, 60% by weight of DMAC, 20% by weight of γ-butyrolactone and 15% by weight of butyl cellosolve, printed on an active matrix substrate, imidized by heat treatment, and imidized. An orientation control film 109 made of dense polyimide and polyamic acid ethyl ester having a rate of about 80% and a film thickness of about 140 nm was formed.

As the alignment treatment method, the same polarized UV as in Example 1 was irradiated with an irradiation energy of 1.5 J / cm ² .

  Next, when the display quality of the three liquid crystal display devices according to this example was evaluated, a high-quality display equivalent to that of the liquid crystal display device of Example 1 was confirmed, and a wide viewing angle at the time of halftone display was also obtained. confirmed. Further, in the same manner as in Example 1, when the image printing and afterimage relaxation time of the liquid crystal display device according to this example were quantitatively evaluated, the afterimage relaxation time was 5 minutes or less, and even in visual image quality afterimage inspection. No image unevenness due to image burning or afterimage was observed, and high display characteristics were obtained.

  As shown in FIG. 5, when the pixel electrode 105 directly connected to the TFT 115 is formed on the uppermost surface of the substrate and the thin alignment control film 109 is formed thereon, the normal rubbing alignment process is performed. Charging due to friction occurs, and in some cases, the TFT 115 may be damaged via the pixel electrode near the surface. In such a case, the rubbing-less photo-alignment treatment as in this embodiment is very effective.

[Example 4]
FIG. 6 is a schematic cross-sectional view of the vicinity of one pixel of the liquid crystal display device according to the fourth embodiment. In the drawing, the same reference numerals as those in the drawings of the respective embodiments described above correspond to the same functional parts. In this embodiment, a structure having a large step due to an electrode or the like is employed. In FIG. 6, the gate electrode 104 and the common electrode 103 of the thin film transistor 115 are formed in the same layer, and the liquid crystal molecules 110 a change the direction of the electric field due to the electric field 117 generated by the common electrode 103 and the pixel electrode 105.

  Further, in each of the above-described embodiments, a plurality of display areas each including the common electrode 103 and the pixel electrode 105 in one pixel can be provided. In this manner, by providing a plurality of sets, even when one pixel is large, the distance between the pixel electrode 105 and the common electrode 103 can be shortened, so that the voltage applied to drive the liquid crystal can be reduced.

  In each of the embodiments described above, the material of the transparent conductive film constituting at least one of the pixel electrode and the common electrode is not particularly limited, but considering the ease of processing, high reliability, and the like. It is desirable to use a transparent conductive film ion-doped with titanium oxide such as indium tin oxide (ITO) or ion-doped zinc oxide.

  In the method for manufacturing a liquid crystal display device according to this embodiment, glass substrates 101 and 102 are glass substrates having a thickness of 0.7 mm and polished surfaces. The thin film transistor 115 includes a pixel electrode (source electrode) 105, a signal wiring (drain electrode) 106, a scanning wiring (gate electrode) 104, and amorphous silicon 116. The scanning wiring 104, the common electrode wiring 120, the signal wiring 106, the pixel electrode 105, and the common electrode 103 were all formed by patterning a chromium film, and the distance between the pixel electrode 105 and the common electrode 103 was 7 μm. The gate insulating film 107 and the protective insulating film 108 were made of silicon nitride, and the film thicknesses were each 0.3 μm.

  In this example, as the orientation control film 109, various polyamic acids 1 to 5 synthesized with the raw material compositions shown in Table 4 below were synthesized, and five liquid crystal display devices were produced using these orientation control films. Polyamic acid was prepared as a varnish having a resin concentration of 5% by weight, DMAC 60% by weight, γ-butyrolactone 20% by weight, and butyl cellosolve 15% by weight, printed on an active matrix substrate, imidized by heat treatment, and an imidization rate of about An orientation control film 109 made of dense polyimide and polyamic acid with a thickness of about 110 nm and 80% was formed.

As the alignment treatment method, the same polarized UV as in Example 1 was irradiated with an irradiation energy of 1.5 J / cm ² . As a result, an active matrix substrate having 1024 × 3 × 768 pixels composed of 1024 × 3 (corresponding to R, G, and B) signal wirings 106 and 768 scanning wirings 104 was formed. .

  As described above, the liquid crystal display device of this example shown in FIG. 6 was manufactured in the same manner as Example 1 except for the pixel structure.

  Next, when the display quality of the three liquid crystal display devices according to this example was evaluated, a high-quality display equivalent to that of the liquid crystal display device of Example 1 was confirmed, and a wide viewing angle at the time of halftone display was also obtained. confirmed. The contrast ratio of the liquid crystal display device using the diamine compound (A-22) (A-53) exceeded 600: 1, and the display quality was particularly good. Further, in the same manner as in Example 1, when the image printing and afterimage relaxation time of the liquid crystal display device according to this example were quantitatively evaluated, the afterimage relaxation time was 5 minutes or less, and even in visual image quality afterimage inspection. No image unevenness due to image burning or afterimage was observed, and high display characteristics were obtained.

[Example 5]
FIG. 7 is a schematic cross-sectional view of the vicinity of one pixel of the liquid crystal display device according to the fifth embodiment. In the drawing, the same reference numerals as those in the drawings of the respective embodiments described above correspond to the same functional parts. In this embodiment, the pixel electrode 105 and the common electrode 103 are made of ITO, and the common electrode 103 is a solid electrode that covers almost the entire pixel. With this configuration, the electrode can be used as a transmission portion, and the aperture ratio can be improved. In addition, the distance between the electrodes can be shortened, and an electric field can be efficiently applied to the liquid crystal.

  FIG. 8 is a schematic plan view of an active matrix substrate showing a configuration in the vicinity of one pixel of the liquid crystal display device according to the fifth embodiment, and shows the structure of the thin film transistor 115, the common electrode 103, the pixel electrode 105, and the signal wiring 106.

  In the method for manufacturing a liquid crystal display device according to this example, a glass substrate having a thickness of 0.7 mm and a polished surface is used as the glass substrate 101. On the glass substrate 101, a gate insulating film 107 for preventing a short circuit between the common electrode 103, the pixel electrode 105, the signal wiring 106, and the scanning wiring 104, and protective insulation for protecting the thin film transistor 115, the pixel electrode 105, and the signal wiring 106. A film 108 is formed to form a TFT substrate.

  The thin film transistor 115 includes a pixel electrode (source electrode) 105, a signal wiring (drain electrode) 106, a scanning wiring (gate electrode) 104, and amorphous silicon 116. The scanning wiring (gate electrode) 104 is formed by patterning an aluminum film, the signal wiring (drain electrode) 106 is formed by patterning a chromium film, and the common electrode 103 and the pixel electrode 105 are formed by patterning ITO.

  The gate insulating film 107 and the protective insulating film 108 were made of silicon nitride, and the film thicknesses were 0.2 μm and 0.3 μm, respectively. The capacitor is formed to have a structure in which the gate insulating film 107 and the protective insulating film 108 are sandwiched between the pixel electrode 105 and the common electrode 103.

  The pixel electrode 105 is arranged so as to overlap the upper layer of the solid-shaped common electrode 103. The number of pixels is 1024 × 3 × 768 including 1024 × 3 (corresponding to R, G, and B) signal wirings 106 and 768 scanning wirings 104.

  On the glass substrate 102, the color filter layer 111 with the black matrix 113 was formed similarly to Example 1, and it was set as the counter color filter substrate.

  In this example, as the orientation control film 109, various polyamic acid methyl esters 1 to 5 synthesized with the raw material compositions shown in Table 5 below were synthesized, and three liquid crystal display devices were produced using these orientation control films. . Polyamide acid methyl ester was prepared into a varnish with a resin concentration of 5% by weight, DMAC 60% by weight, γ-butyrolactone 20% by weight, butyl cellosolve 15% by weight, printed on an active matrix substrate, imidized by heat treatment, and imidized. An orientation control film 109 made of dense polyimide and polyamic acid methyl ester having a rate of about 70% and a film thickness of about 130 nm was formed.

  Similarly, the same polyamic acid ethyl ester varnish is printed on the surface of the other glass substrate 102 on which ITO is formed and imidized by heat treatment, and an imidization ratio of about 80% and a dense polyimide and polyamide of about 110 nm are used. An alignment control film 109 made of acid methyl ester was formed.

As the alignment treatment method, the same polarized UV as in Example 1 was irradiated with an irradiation energy of 1.5 J / cm ² .

  The alignment directions of the alignment control film 109 on the TFT substrate and the color filter substrate are substantially parallel to each other. Polymer beads having an average particle diameter of 4 μm were dispersed as spacers between these substrates, and liquid crystal molecules 110a were sandwiched between the TFT substrate and the color filter substrate. The same liquid crystal composition A as in Example 1 was used as the liquid crystal molecules 110a.

  The two polarizing plates 114 sandwiching the TFT substrate and the color filter substrate were arranged in crossed Nicols. A normally closed characteristic is adopted in which a dark state is obtained at a low voltage and a bright state is obtained at a high voltage.

  Next, when the display quality of the liquid crystal display device according to the present example was evaluated, an aperture ratio was higher than that of the liquid crystal display device of example 1, and a high-quality display with a contrast ratio of 700: 1 was confirmed. A wide viewing angle was also confirmed during the tonal display. Further, in the same manner as in Example 1, when the image printing and afterimage relaxation time of this liquid crystal display device were quantitatively evaluated, the afterimage relaxation time was within 5 minutes in the operating temperature range of 0 ° C to 50 ° C. Even in visual image quality afterimage inspection, no image burning or display unevenness due to afterimage was observed, and high display characteristics equivalent to those of Example 1 were obtained.

[Example 6]
In this example, a liquid crystal display device was produced in the same manner as in Example 5 except that various polyamic acid methyl esters synthesized with raw material compositions shown in Table 6 below were used as the alignment control film 109.

  Next, when the display quality of the liquid crystal display device according to the present example was evaluated, an aperture ratio was higher than that of the liquid crystal display device of example 1, and a high-quality display with a contrast ratio of 800: 1 was confirmed. A wide viewing angle was also confirmed during the tonal display. Further, in the same manner as in Example 1, when the image printing and afterimage relaxation time of this liquid crystal display device were quantitatively evaluated, the afterimage relaxation time was within 2 minutes in the operating temperature range of 0 ° C to 50 ° C. Compared with Example 7, the liquid crystal alignment stability was high. Further, in visual image quality afterimage inspection, no image burn-in and display unevenness due to afterimage were observed, and high display characteristics equivalent to those in Example 1 were obtained.

  101, 102 glass substrate, 103 common electrode (common electrode), 104 scanning wiring (gate electrode), 105 pixel electrode (source electrode), 106 signal wiring (drain electrode), 107 gate insulating film, 108 protective insulating film, 109 orientation Control film, 110a liquid crystal molecule, 110b liquid crystal composition layer (liquid crystal layer), 111 color filter layer, 112 organic protective film (overcoat layer), 113 light shielding film (black matrix), 114 polarizing plate, 115 thin layer transistor (TFT) ), 116 Semiconductor film (amorphous silicon or polysilicon), 117 electric field (electric field direction), 118 through hole, 120 common electrode wiring (common wiring).

Claims (8)

Consisting of polyimide and a precursor of said polyimide,
The polyimide and the polyimide precursor include a cyclobutanetetracarboxylic dianhydride derivative represented by the following chemical formula (1) and an aromatic diamine as raw materials,
An alignment control film characterized in that an alignment regulating force is imparted by a photo-alignment treatment.

(However, at least one of Z ¹ to Z ⁴ is a substituent represented by —NR ₂ , —SR, —OH, —COR, — (CH ₂ ) _n —COOR, —CN or —NO ₂ (R is And each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is an integer of 0 to 2.), and the others are hydrogen atoms.) The alignment control film according to claim 1, wherein the aromatic diamine includes at least one aromatic diamine selected from a group of compounds represented by the following chemical formulas (101) to (110).

(Wherein, X is independently, is any of the structures shown _{below: -. CH 2 -, -} CO -, - O -, - NH -, - CO-NH -, - S -, - SO- , —SO ₂ —)   The alignment control film according to claim 2, wherein the aromatic diamine includes two or more different aromatic diamines selected from the group of compounds represented by the chemical formulas (101) to (110).   The tetracarboxylic dianhydride used as a raw material for the polyimide and the polyimide precursor is a cyclobutane tetracarboxylic dianhydride derivative represented by the chemical formula (1) at a ratio of 70 mol% to 100 mol%. The orientation control film according to claim 1, wherein the orientation control film is contained. The orientation according to any one of claims 1 to 3, wherein the polyimide and the polyimide precursor further include a cyclobutanetetracarboxylic dianhydride derivative represented by the following chemical formula (2) as a raw material. Control membrane.

(However, at least one of Y ¹ to Y ⁴ is a methyl group or a methoxy group, and the other is a hydrogen atom.)   The alignment control film according to claim 1, wherein the polyimide precursor includes a polyamic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms. At least two of Z ¹ to Z ^{4 in} the chemical formula (1) are represented by —NR ₂ , —SR, —OH, —COR, — (CH ₂ ) _n —COOR, —CN, or —NO ₂ . The substituents (R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is an integer of 0 to 2), and the others are hydrogen atoms. The alignment control film according to claim 1. The polyimide and the polyimide precursor include, as a raw material, a cyclobutanetetracarboxylic dianhydride derivative represented by two or more chemical formulas (1) having different numbers of substituents.
The alignment control film according to claim 1, wherein the alignment control film is a film.

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