JP2010191257A - Thin film transistor substrate, liquid crystal display element, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a TFT substrate capable of suppressing alignment treatment unevenness caused by level difference by a wiring line, an electrode and the like, reducing generation of an alignment defect and shortening charging time. <P>SOLUTION: The thin film transistor substrate includes a base material 2, a gate line formed on the base material, a gate insulating layer 4, an overcoat layer 6, a source line, a pixel electrode 8, and a TFT 10 having a gate electrode 13 connected to the gate line formed on the base material 2, a gate insulating layer 14 for the TFT, a semiconductor layer 15 formed on the gate insulating layer for the TFT, an overcoat layer 16 for the TFT formed on the gate insulating layer for the TFT and the semiconductor layer continuously to the overcoat layer, a source electrode 17 formed on the overcoat layer for the TFT, connected to the source line and connected to the semiconductor layer via a contact hole h1 for the source electrode and a transparent electrode 18 formed on the overcoat layer for the TFT, connected to the pixel electrode, and connected to the semiconductor layer via a contact hole h2 for the transparent electrode. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thin film transistor substrate used for a liquid crystal display element.

  An active matrix liquid crystal display device using an active element such as a thin film transistor (hereinafter, the thin film transistor may be referred to as a TFT) is widely used as a display device because of its thinness, light weight, high image quality, and the like. In an active matrix liquid crystal display device, a liquid crystal is sandwiched between a thin film transistor substrate having a TFT (hereinafter, the thin film transistor substrate may be referred to as a TFT substrate) and a counter substrate disposed opposite to the TFT substrate. A voltage is applied between the pixel electrode of the substrate and the common electrode of the counter substrate to drive the liquid crystal, and an incident light is modulated and emitted to form an image.

  In a TFT substrate, a gate line and a gate electrode connected to the gate line are usually formed on a base material, a gate insulating layer is formed to cover the gate line and the gate electrode, and a semiconductor layer is formed on the gate insulating layer. A source line is formed so as to cross the gate line, a source electrode and a drain electrode connected to the source line are formed on the semiconductor layer, and a pixel electrode connected to the drain electrode is formed. Further, in a TFT substrate used for a liquid crystal display device, an alignment film is formed so as to cover a semiconductor layer, a source electrode, a drain electrode, a pixel electrode, and the like.

  Since the TFT substrate is formed with wirings such as gate lines and source lines and electrodes such as pixel electrodes, there is a step in the alignment film formed so as to cover these wirings and electrodes. For this reason, when an alignment process such as a rubbing process or a photo-alignment process is performed when forming the alignment film, a uniform alignment process cannot be performed, resulting in uneven alignment process in the alignment film. As a result, alignment failure of the liquid crystal occurs, resulting in display unevenness of the liquid crystal display device.

  In particular, when a rubbing process is performed, if there is a step perpendicular to the rubbing process direction, the above-described alignment failure is noticeable, the contrast is lowered, the display is uneven, and the image quality is significantly lowered. . Therefore, for example, when the rubbing process is performed so that the rubbing process direction is parallel to the longitudinal direction of the source line, there is a step due to the gate line orthogonal to the rubbing process direction. Will occur.

  In order to solve the above problems, there are a method of grading the cross-sectional shape of the ends of the wirings and electrodes (for example, see Patent Document 1) and a method of reducing the thickness of the wirings and electrodes (for example, see Patent Document 2). Proposed. However, in the case of using a liquid crystal having a high molecular order and difficult alignment, such as a ferroelectric liquid crystal, alignment defects are likely to occur. Therefore, the above method is insufficient to suppress display unevenness. .

  Further, for the purpose of flattening a step due to wiring, electrodes, etc., a gate electrode 103 connected to the gate line 103 and the gate line 103 is formed on the base material 102 as illustrated in FIGS. 15 and 16. A gate insulating layer 106 is formed so as to cover the gate line 103 and the gate electrode 113, a semiconductor layer 117 is formed over the gate insulating layer 106, a source line 104 is formed so as to cross the gate line 103, and the semiconductor layer 117. A source electrode 114 connected to the source line 104 is formed thereon, an overcoat layer 108 is formed so as to cover the semiconductor layer 117, the source electrode 114, and the like, and the semiconductor layer 117 is formed over the overcoat layer 108 through a contact hole. A TFT substrate on which a pixel electrode 105 to be connected is formed has been proposed. 16 is a cross-sectional view taken along the line CC of FIG. 15, and the gate insulating layer and the like are omitted in FIG. However, in the above-described TFT substrate, the distance d1 between the gate electrode 113 and the source electrode 114 is short, so that there is a risk of leakage current.

Japanese Patent Laid-Open No. 11-295564 JP 2003-222903 A

  In the TFT substrate, in order to reduce the storage capacity and shorten the charging time, it is preferable that the distance between the gate electrode and the source electrode is long, and in order to easily apply a voltage to the gate electrode, the distance between the gate electrode and the semiconductor layer is Shorter is preferred.

  The present invention has been made in view of such various points, and can suppress alignment processing unevenness caused by steps due to wiring, electrodes, etc., reduce the occurrence of alignment failure, and further shorten the charging time. It is a main object to provide a thin film transistor substrate that can be used.

  In order to achieve the above object, the present invention provides a base material, a gate line formed on the base material, a gate insulating layer formed so as to cover the gate line, and a gate insulating layer formed on the gate insulating layer. An overcoat layer formed on the substrate, a source line formed on the overcoat layer so as to intersect the gate line, a pixel electrode formed on the overcoat layer, and the substrate. A gate electrode connected to a gate line; a gate insulating layer for a thin film transistor continuously formed on the gate insulating layer so as to cover the gate electrode; a semiconductor layer formed on the gate insulating layer for the thin film transistor; An overcoat layer for a thin film transistor formed continuously on the gate insulating layer and the semiconductor layer with the overcoat layer; A source electrode formed on the coat layer, connected to the source line, connected to the semiconductor layer via a contact hole for the source electrode, and formed on the overcoat layer for the thin film transistor and connected to the pixel electrode And a thin film transistor substrate having a transparent electrode connected to the semiconductor layer through a transparent electrode contact hole.

  Hereinafter, a thin film transistor may be referred to as a TFT, a thin film transistor substrate as a TFT substrate, a thin film transistor gate insulating layer as a TFT gate insulating layer, and a thin film transistor overcoat layer as a TFT overcoat layer.

  According to the present invention, the overcoat layer is formed on the gate line, the gate insulating layer, etc., and the TFT overcoat is continuously formed on the gate electrode, the TFT gate insulating layer, the semiconductor layer, etc. Since the layer is formed, when the alignment film is formed, the flatness of the alignment film forming layer for forming the alignment film can be improved, and the occurrence of unevenness in the alignment process can be suppressed. . In addition, since the TFT overcoat layer is formed on the gate electrode and the source electrode is formed on the TFT overcoat layer, the distance between the gate electrode and the source electrode can be made relatively long, and the storage capacitor The charging time can be shortened.

  The TFT substrate of the present invention is preferably used for a liquid crystal display element using a ferroelectric liquid crystal. Ferroelectric liquid crystals are difficult to align due to their higher molecular ordering than nematic liquid crystals, but in the present invention, it is possible to suppress the occurrence of alignment processing irregularities, so that alignment specific to ferroelectric liquid crystals is difficult. The occurrence of defects can also be suppressed.

  The TFT substrate of the present invention is preferably used for a liquid crystal display element driven by a field sequential method. In the present invention, since the charging time can be shortened, the time required for writing scanning and erasing scanning can be shortened, which is suitable for a liquid crystal display element driven by a field sequential method.

  Furthermore, in the present invention, it is preferable that a light shielding portion is formed on the semiconductor layer. As a result, when a liquid crystal display element is manufactured using the TFT substrate of the present invention, the semiconductor layer is irradiated with light from the backlight, thereby causing a malfunction and preventing a display defect due to the malfunction. Because it can.

  In the present invention, an alignment film is preferably formed on the source line, the pixel electrode, and the TFT. This is because, as described above, it is possible to suppress the occurrence of alignment processing unevenness.

  In the above case, the alignment film is preferably an alignment film subjected to rubbing treatment, and the rubbing treatment direction is preferably parallel to the longitudinal direction of the source line. When there is a step perpendicular to the rubbing processing direction, the rubbing unevenness becomes significant. However, in the present invention, the step due to the gate line can be greatly reduced, so On the other hand, by performing the rubbing process in parallel, it is possible to effectively suppress the occurrence of rubbing unevenness along the gate line.

  In the above case, it is also preferable that the alignment film is a photo-alignment film that has been subjected to a photo-alignment treatment, and the light irradiation direction is parallel to the longitudinal direction of the source line. In the case where there is a step perpendicular to the light irradiation direction, a portion where no light is irradiated may occur. However, in the present invention, the step due to the gate line can be significantly reduced, so that the source By irradiating light parallel to the longitudinal direction of the line, it is possible to effectively suppress the occurrence of uneven alignment treatment along the gate line.

  In the present invention, the second electrode and the second alignment film are sequentially stacked on the TFT substrate and the second base material, and the alignment film and the second alignment film face the TFT substrate. And a liquid crystal layer formed between the alignment film and the second alignment film. A liquid crystal display element is provided.

  According to the present invention, since the above-described TFT substrate is used, a liquid crystal display element having good display quality and high contrast can be obtained. Further, since the above-described TFT substrate is used, the storage capacity can be reduced and the charging time can be shortened.

  In the above invention, the liquid crystal layer preferably includes a ferroelectric liquid crystal, and the constituent materials of the alignment film and the second alignment film preferably have different compositions. Since the constituent materials of the alignment film and the second alignment film have different compositions, the polarities of the alignment film surface and the second alignment film surface can be made different depending on the respective materials. As a result, the polar surface interaction between the ferroelectric liquid crystal and the alignment film is different from the polar surface interaction between the ferroelectric liquid crystal and the second alignment film. This is because by appropriately selecting the material in consideration, it is possible to suppress the occurrence of alignment defects unique to the ferroelectric liquid crystal such as zigzag defects, hairpin defects, and double domains.

  Furthermore, the present invention provides a liquid crystal dropping step in which liquid crystal is dropped in a straight line on the alignment film of the TFT substrate, perpendicularly or parallel to the longitudinal direction of the source line, a TFT substrate on which the liquid crystal is dropped, And a substrate laminating step of laminating the counter substrate in which the second electrode and the second alignment film are sequentially laminated on the second base material, and arranging the liquid crystal filled between the TFT substrate and the counter substrate And a liquid crystal display element manufacturing method.

  According to the present invention, by using the TFT substrate described above, the occurrence of alignment processing unevenness is suppressed, and the liquid crystal is linearly aligned perpendicularly or parallel to the longitudinal direction of the source line depending on the type of alignment film. The dripping can suppress the occurrence of alignment disorder. Therefore, it is possible to obtain a liquid crystal display element with excellent display quality and high contrast.

  The present invention also includes a substrate bonding step of bonding the above-described TFT substrate, and a counter substrate in which a second electrode and a second alignment film are sequentially laminated on the second base material, the TFT substrate, and the counter substrate A liquid crystal injection step of injecting liquid crystal in parallel or perpendicular to the longitudinal direction of the source line, and a liquid crystal alignment step of aligning the liquid crystal filled between the TFT substrate and the counter substrate A method for manufacturing a liquid crystal display element is provided.

  According to the present invention, by using the above-described TFT substrate, the occurrence of alignment processing unevenness is suppressed, and liquid crystal is injected parallel or perpendicular to the longitudinal direction of the source line depending on the type of alignment film. The occurrence of orientation disorder can be suppressed. Therefore, it is possible to obtain a liquid crystal display element with excellent display quality and high contrast.

  In the present invention, since the occurrence of uneven alignment treatment can be suppressed, when the TFT substrate of the present invention is used for a liquid crystal display element, it is possible to prevent the occurrence of liquid crystal alignment failure, and display quality and contrast. There is an effect that can be increased.

It is a schematic plan view which shows an example of the TFT substrate of this invention. It is the sectional view on the AA line in FIG. It is the BB sectional view taken on the line in FIG. It is a schematic sectional drawing which shows the other example of the TFT substrate of this invention. It is a schematic sectional drawing which shows an example of TFT in the TFT substrate of this invention. It is a schematic sectional drawing which shows an example of TFT in the TFT substrate of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display element of this invention. It is a schematic diagram which shows the behavior of a liquid crystal molecule. It is the graph which showed the change of the transmittance | permeability with respect to the applied voltage of a ferroelectric liquid crystal. It is process drawing which shows an example of the manufacturing method of the liquid crystal display element of this invention. It is a schematic diagram which shows the other example of the manufacturing method of the liquid crystal display element of this invention. It is process drawing which shows the other example of the manufacturing method of the liquid crystal display element of this invention. It is process drawing which shows the other example of the manufacturing method of the liquid crystal display element of this invention. It is process drawing which shows the other example of the manufacturing method of the liquid crystal display element of this invention. It is a schematic plan view which shows an example of the conventional TFT substrate. It is CC sectional view taken on the line in FIG.

  Hereinafter, the TFT substrate, the liquid crystal display element, and the manufacturing method of the liquid crystal display element of the present invention will be described in detail.

A. TFT substrate First, the TFT substrate of the present invention will be described. The TFT substrate of the present invention includes a base material, a gate line formed on the base material, a gate insulating layer formed so as to cover the gate line, and an overcoat layer formed on the gate insulating layer. A source line formed on the overcoat layer so as to intersect the gate line, a pixel electrode formed on the overcoat layer, and formed on the base material and connected to the gate line. A gate insulating layer for TFT formed continuously over the gate insulating layer so as to cover the gate electrode, a semiconductor layer formed on the gate insulating layer for TFT, a gate insulating layer for TFT, and a semiconductor A TFT overcoat layer formed on the layer continuously with the overcoat layer, formed on the TFT overcoat layer, connected to the source line, and connected to the semiconductor layer. A source electrode connected via a contact hole for a source electrode, and a transparent electrode formed on the TFT overcoat layer, connected to the pixel electrode, and connected to the semiconductor layer via a contact hole for a transparent electrode And a TFT having an electrode.

  The TFT substrate of the present invention will be described with reference to the drawings. FIG. 1 is a schematic plan view showing an example of the TFT substrate of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. In FIG. 1, a gate insulating layer and the like are omitted for simplification.

  As illustrated in FIGS. 1 to 3, the TFT substrate 1 includes a base material 2, a gate line 3 formed on the base material 2, a gate insulating layer 4 formed so as to cover the gate line 3, An overcoat layer 6 formed on the gate insulating layer 4; a source line 7 formed on the overcoat layer 6 so as to intersect the gate line 3; and a pixel electrode 8 formed on the overcoat layer 6; And the TFT 10 formed on the substrate 2.

  The TFT 10 is formed on the base material 2 and is connected to the gate line 3. The TFT gate insulating layer 14 is formed continuously with the gate insulating layer 4 so as to cover the gate electrode 13. A semiconductor layer 15 formed on the TFT gate insulating layer 14; a TFT overcoat layer 16 formed continuously on the TFT gate insulating layer 14 and the semiconductor layer 15 with the overcoat layer 6; Formed on the TFT overcoat layer 16, connected to the source line 7, connected to the semiconductor layer 15 via the source electrode contact hole h 1, and formed on the TFT overcoat layer 16. And the transparent electrode 18 connected to the pixel electrode 8 and connected to the semiconductor layer 15 via the transparent electrode contact hole h2.

  According to the present invention, the overcoat layer is formed on the gate line, the gate insulating layer, etc., and the TFT overcoat is continuously formed on the gate electrode, the TFT gate insulating layer, the semiconductor layer, etc. Since the layer is formed, when the alignment film is formed, the flatness of the alignment film forming layer for forming the alignment film can be improved. That is, in the TFT substrate illustrated in FIGS. 1 to 3, when the alignment film forming layer is formed on the source line 7, the pixel electrode 8, and the TFT 10, unevenness on the surface of the alignment film forming layer is reduced. be able to. Therefore, the alignment film forming layer is formed with good flatness on the source line 7, the pixel electrode 8, and the TFT 10, and the alignment film forming layer is subjected to alignment treatment such as rubbing or photo-alignment treatment on the entire alignment film forming layer. It is possible to suppress the occurrence of unevenness of the alignment treatment. As a result, as illustrated in FIG. 4, a uniform alignment film 9 can be formed on the source line (not shown), the pixel electrode 8, and the TFT 10. 4 corresponds to a cross-sectional view taken along line BB in FIG.

  In particular, since the overcoat layer is formed so as to cover the gate line, the step due to the gate line can be significantly reduced. Therefore, in the example shown in FIG. 1, when the rubbing process is performed in parallel to the longitudinal direction 51 of the source line 7, there is almost no step due to the gate line orthogonal to the rubbing process direction. It is possible to effectively suppress the occurrence of rubbing unevenness along.

  In a liquid crystal display element using a TFT substrate having a uniform alignment film as described above, it is possible to suppress the occurrence of liquid crystal alignment failure, and to reduce display unevenness and contrast deterioration. That is, a liquid crystal display element with good display quality and high contrast can be obtained.

Further, according to the present invention, as illustrated in FIG. 2, the TFT overcoat layer 16 is formed on the gate electrode 13, and the source electrode 17 is formed on the TFT overcoat layer 16. The distance d1 between the gate electrode 13 and the source electrode 17 can be made relatively long, the storage capacity can be reduced, and the charging time can be shortened.
Furthermore, since the gate electrode 13, the TFT gate insulating layer 14, the semiconductor layer 15 and the TFT overcoat layer 16 are laminated in this order, the distance d2 between the gate electrode 13 and the semiconductor layer 15 can be made relatively short, A voltage can be easily applied to the gate electrode.

As described above, in the present invention, both the planarization of the alignment film and the shortening of the charging time can be achieved by adopting the above configuration.
Hereinafter, each structure in the TFT substrate of the present invention will be described.

1. Overcoat layer The overcoat layer in this invention is formed on a gate insulating layer. The overcoat layer is provided for leveling the surface of the base material on which the gate line, the gate insulating layer, etc. are formed, and for further flattening by eliminating the step due to the gate line. .

  The overcoat layer is not particularly limited as long as it has desired insulating properties and small optical anisotropy, and is generally used as an overcoat layer in a color filter for a liquid crystal display device. Things can be used. Examples of the material for forming such an overcoat layer include a photocurable resin and a thermosetting resin. Specifically, an acrylic resin, a phenolic resin, an epoxy resin, a cardo resin, a vinyl resin, Examples thereof include imide resins and novolac resins.

  The thickness of the overcoat layer may be any thickness that can flatten the step due to the gate line, and is preferably in the range of 0.5 μm to 2 μm.

  In addition, as a method for forming the overcoat layer, a coating liquid for forming an overcoat layer containing the above-described material is applied and formed by a method such as spin coating, roll coating, cast coating, and the like. In the case of heat curing, it may be heat-cured as necessary after ultraviolet irradiation, and in the case of a thermosetting resin, it may be heat-cured as it is after film formation.

2. TFT
The TFT used in the present invention includes a gate electrode formed on a substrate and connected to a gate line, a TFT gate insulating layer formed continuously with the gate insulating layer so as to cover the gate electrode, A semiconductor layer formed on the gate insulating layer for TFT, an overcoat layer for TFT formed continuously with the overcoat layer on the gate insulating layer and semiconductor layer for TFT, and the overcoat layer for TFT Formed on the source line, connected to the semiconductor layer via a source electrode contact hole, and formed on the TFT overcoat layer, connected to the pixel electrode, and connected to the semiconductor layer. And a transparent electrode connected through a transparent electrode contact hole.
Hereinafter, each configuration in the TFT will be described.

(1) TFT Overcoat Layer The TFT overcoat layer constituting the TFT in the present invention is formed continuously on the TFT gate insulating layer and the semiconductor layer with the overcoat layer.
Here, the TFT overcoat layer being formed continuously with the overcoat layer means that the TFT overcoat layer is formed integrally with the overcoat layer.
Note that the TFT overcoat layer is the same as the overcoat layer described above, and a description thereof will be omitted.

(2) Source electrode The source electrode constituting the TFT in the present invention is formed on the TFT overcoat layer, connected to the source line, and connected to the semiconductor layer through the source electrode contact hole. .

  The source electrode is not particularly limited as long as it is made of a material having desired conductivity, and a metal material generally used for a TFT can be used. Examples of such metal materials include conductive polymers such as Ag, Au, Ta, Ti, Al, Zr, Cr, Nb, Hf, Mo, Mo—Ta alloy, ITO, IZO, and PEDOT / PSS. be able to. Usually, the source electrode is made of the same material as a source line described later.

As a method of forming the source electrode so that the source electrode is connected to the semiconductor layer through the source electrode contact hole, first, the source electrode contact hole is formed in the TFT overcoat layer by using a photolithography method, and then Examples include a method of forming the metal material on the TFT overcoat layer in which the contact hole for the source electrode is formed by a sputtering method or the like, and then etching a film made of the metal material into a desired pattern. Usually, the source electrode is formed simultaneously with the source line described later.
The thickness of the source electrode can be, for example, about 50 nm to 500 nm.

(3) Transparent electrode The transparent electrode constituting the TFT in the present invention is formed on the TFT overcoat layer, connected to the pixel electrode, and connected to the semiconductor layer via the transparent electrode contact hole. .

  As a transparent electrode, what is generally used as a transparent electrode for liquid crystal display devices can be used, and among them, a transparent electrode made of indium oxide, tin oxide, indium tin oxide (ITO) is preferably used. It is done. Usually, the transparent electrode is made of the same material as the pixel electrode described later.

As a method of forming a transparent electrode so that the transparent electrode is connected to the semiconductor layer via the transparent electrode contact hole, first, a transparent electrode contact hole is formed on the TFT overcoat layer using a photolithography method, and then Examples include a method in which ITO or the like is formed on the TFT overcoat layer in which the transparent electrode contact hole is formed by a sputtering method or the like, and then a film made of ITO or the like is etched into a desired pattern. Usually, the transparent electrode is formed simultaneously with the pixel electrode described later.
The thickness of the transparent electrode can be set to, for example, about 50 nm to 500 nm.

(4) Gate electrode The gate electrode which comprises TFT in this invention is formed on a base material, and is connected to a gate line.

  The gate electrode is not particularly limited as long as it is made of a material having desired conductivity, and a metal material generally used for TFTs can be used. Examples of such metal materials include conductive polymers such as Ag, Au, Ta, Ti, Al, Zr, Cr, Nb, Hf, Mo, Mo—Ta alloy, ITO, IZO, and PEDOT / PSS. be able to. Usually, the gate electrode is made of the same material as a gate line described later.

Examples of a method for forming the gate electrode include a method in which the metal material is first formed by sputtering or the like, and then a film made of the metal material is etched. Usually, the gate electrode is formed simultaneously with the gate line described later.
The thickness of the gate electrode can be, for example, about 50 nm to 500 nm.

(5) Gate insulation layer for TFT The gate insulation layer for TFT constituting the TFT in the present invention is formed continuously with the gate insulation layer so as to cover the gate electrode.
Here, the TFT gate insulating layer being formed continuously with the gate insulating layer means that the TFT gate insulating layer is formed integrally with the gate insulating layer.

  The material used for the gate insulating layer for TFT is not particularly limited as long as it has a desired insulating property, and examples thereof include silicon oxide and silicon nitride.

Examples of a method for forming the gate insulating layer for TFT include a method of forming the above material by a sputtering method or the like.
The thickness of the TFT gate insulating layer can be, for example, about 400 nm to 600 nm.

(6) Semiconductor layer The semiconductor layer constituting the TFT in the present invention is formed on the TFT gate insulating layer.

  Examples of the semiconductor layer include hydrogenated amorphous silicon, hydrogenated amorphous silicon germanium, hydrogenated amorphous silicon carbide, microcrystalline silicon, polycrystalline silicon, mixed crystals of CdS, ZnS, CdS, and ZnS, An inorganic compound semiconductor material such as CdTe or Se can be used. For the semiconductor layer, for example, an organic semiconductor material such as a π-electron conjugated aromatic compound, a chain compound, an organic pigment, or an organic silicon compound can be used. Specific examples of the organic semiconductor material include pentacene, tetracene, thiophene oligomer derivatives, phenylene derivatives, phthalocyanine compounds, polyacetylene derivatives, polythiophene derivatives, and cyanine dyes.

(7) Light Shielding Part In the TFT used in the present invention, it is preferable that a light shielding part is formed on the semiconductor layer. As a result, when a liquid crystal display element is manufactured using the TFT substrate of the present invention, the semiconductor layer is irradiated with light from the backlight, thereby causing a malfunction and preventing a display defect due to the malfunction. Because it can.

  The light shielding part is not particularly limited as long as it is made of a material having a desired light shielding property, but is usually made of a metal material or a material made of a light shielding material and a resin.

  When the light shielding part is made of a metal material, the metal material is not particularly limited as long as it has a desired light shielding property, but a chromium material is generally used.

  On the other hand, when the light shielding part is composed of a light shielding material and a resin, examples of the light shielding material include light shielding particles such as carbon fine particles, metal oxides, inorganic pigments, and organic pigments. Examples of the resin include ethylene-vinyl acetate copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl copolymer, polystyrene, acrylonitrile-styrene copolymer, ABS resin, polymethacrylic acid resin, ethylene- Methacrylic acid resin, polyvinyl chloride resin, chlorinated vinyl chloride, polyvinyl alcohol, cellulose acetate propionate, cellulose acetate butyrate, nylon 6, nylon 66, nylon 12, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinyl acetal, poly Ether ether ketone, polyether sulfone, polyphenylene sulfide, polyarylate, polyvinyl butyral, epoxy resin, phenoxy resin, polyimide resin, polyamide resin De resins, polyamic acid resins, polyether imide resins, phenolic resins, and urea resins.

  Further, the formation position of the light shielding portion may be on the semiconductor layer, but when the light shielding portion is made of a metal material, the light shielding portion 21a is located on the semiconductor layer 15 as illustrated in FIG. It is preferably formed on the TFT overcoat layer 16 formed in the above. On the other hand, when the light shielding portion is made of a light shielding material and a resin, as illustrated in FIG. 6, the light shielding portion 21b is formed on the semiconductor layer 15, and a part of the TFT overcoat layer is formed. It is also preferable to serve as both.

  The thickness of the light shielding part can be, for example, about 200 nm to 500 nm when the light shielding part is made of a metal material. On the other hand, when the light shielding part is made of a light shielding material and a resin, the thickness of the light shielding part can be, for example, about 0.5 μm to 2 μm.

3. Alignment film In the present invention, an alignment film is preferably formed on the source line, the pixel electrode, and the TFT.

  The alignment film has an alignment regulating force for the liquid crystal material. The alignment film may be any film as long as it can align the liquid crystal. Among them, it is preferable that unevenness is likely to occur when unevenness exists on the surface of the alignment film forming layer. Examples of such an alignment film include a rubbing-processed alignment film and a photo-alignment-processed photo-alignment film.

  In the case of rubbing, if unevenness exists on the surface of the alignment film forming layer, uneven rubbing occurs due to the unevenness. In particular, when unevenness exists orthogonal to the rubbing treatment direction, the rubbing unevenness becomes significant. On the other hand, in the present invention, the level difference due to the gate line can be greatly reduced, so that rubbing treatment is performed in parallel with the longitudinal direction of the source line, thereby causing rubbing unevenness along the gate line. Can be effectively suppressed.

Further, in the case of photo-alignment treatment, light is often irradiated from an angle of about 0 ° to 45 ° with respect to the surface of the base material. It will occur and unevenness of alignment treatment will occur. On the other hand, in the present invention, the step due to the wiring, the electrode, and the like can be reduced, so that it is possible to suppress the occurrence of uneven alignment processing due to the step.
Hereinafter, the alignment film and the photo-alignment film that have been rubbed will be described separately.

(1) Oriented film subjected to rubbing treatment The material used for the oriented film subjected to rubbing treatment is not particularly limited as long as it can impart anisotropy to the film by rubbing treatment. Nylon, polyimide, polyamide, polyamideimide, polyetherimide, polyvinyl alcohol, polyurethane and the like can be mentioned. These may be used alone or in combination of two or more.

  In particular, when the TFT substrate of the present invention is applied to a liquid crystal display element using a ferroelectric liquid crystal, the rubbing-treated alignment film preferably contains nylon or polyimide. This is because the ferroelectric liquid crystal is easily aligned in the azimuth direction. That is, the ferroelectric liquid crystal is easily arranged in a certain direction.

As a rubbing treatment method, there can be used a method in which an anisotropy is imparted to the film by forming a film containing the above material and rubbing the film with a rubbing cloth in a certain direction.
As the rubbing cloth, for example, a cloth made of a fiber such as nylon resin, vinyl resin, rayon, or cotton can be used. For example, by rotating a drum wound with such a rubbing cloth and bringing it into contact with the surface of the film containing the above material, fine grooves are formed in one direction on the film surface, and anisotropy is imparted to the film. The

The rubbing treatment direction is preferably parallel to the longitudinal direction of the source line. As described above, since the step due to the gate line can be greatly reduced in the present invention, rubbing unevenness occurs along the gate line by performing the rubbing process in parallel to the longitudinal direction of the source line. It is because it can suppress effectively.
Note that the rubbing treatment direction being parallel to the longitudinal direction of the source line means that the angle formed by the rubbing treatment direction and the longitudinal direction of the source line is 0 ° ± 2 °.

  The thickness of the alignment film subjected to the rubbing treatment is set to about 1 nm to 1000 nm, and preferably in the range of 50 nm to 100 nm.

(2) Photo-alignment film A photo-alignment film is a film obtained by irradiating a substrate coated with a photo-alignment material, which will be described later, with light whose polarization is controlled to cause a photoexcitation reaction (decomposition, isomerization, dimerization). The liquid crystal molecules on the film are aligned by imparting anisotropy to the film.

  The photo-alignment material used in the present invention is not particularly limited as long as it has an effect of aligning liquid crystals (photoalignment) by irradiating light to cause a photoexcitation reaction. As such materials, there are large photoreactive materials that impart anisotropy to a film by causing a photoreaction, and photoisomerizable materials that impart anisotropy to a film by causing a photoisomerization reaction. And can be divided into In the following, description will be made separately for photoreactive materials and photoisomerizable materials.

(I) Photoreactive Material A photoreactive material is a material that imparts anisotropy to a film by causing a photoreaction. The photoreactive material used in the present invention is not particularly limited as long as it has such characteristics, but among these, the film is anisotropic by causing a photodimerization reaction or a photodecomposition reaction. It is preferable that the material imparts properties.

  Here, the photodimerization reaction is a reaction in which the reaction site oriented in the polarization direction by light irradiation undergoes radical polymerization and two molecules are polymerized. This reaction stabilizes the orientation in the polarization direction and makes the film anisotropic. Can be provided. The photodecomposition reaction is a reaction that decomposes molecular chains such as polyimide oriented in the polarization direction by light irradiation. This reaction leaves molecular chains oriented in the direction perpendicular to the polarization direction, and makes the film anisotropic. Can be provided. In the present invention, among these photoreactive materials, it is more preferable to use a material that imparts anisotropy to the photoalignment film by a photodimerization reaction because of high exposure sensitivity and a wide range of material selection. .

  The photodimerization type material used in the present invention is not particularly limited as long as it can impart anisotropy to the film by a photodimerization reaction, but has a radical polymerizable functional group, And it is preferable that the photodimerization reactive compound which has the dichroism which makes absorption differ with polarization directions is included. This is because radical polymerization of the reaction sites oriented in the polarization direction stabilizes the orientation of the photodimerization reactive compound and can easily impart anisotropy to the film.

  Examples of the photodimerization reactive compound having such characteristics include a dimerization reactive polymer having at least one reactive site selected from cinnamate ester, coumarin, quinoline, chalcone group and cinnamoyl group as a side chain. Can do.

  Among these, the photodimerization reactive compound is preferably a dimerization reactive polymer containing cinnamate, coumarin or quinoline as a side chain. This is because anisotropy can be easily imparted to the film by radical polymerization of α, β unsaturated ketone double bonds oriented in the polarization direction as reaction sites.

  The main chain of the dimerization reactive polymer is not particularly limited as long as it is generally known as a polymer main chain, but the reaction sites of the side chains such as aromatic hydrocarbon groups are not limited. It is preferable that it does not have a substituent containing a lot of π electrons that hinders the interaction.

  The weight average molecular weight of the dimerization reactive polymer is not particularly limited, but is preferably in the range of 5,000 to 40,000, and is preferably in the range of 10,000 to 20,000. Is more preferable. The weight average molecular weight can be measured by a gel permeation chromatography (GPC) method. If the weight average molecular weight of the dimerization reactive polymer is too small, it may not be possible to impart an appropriate anisotropy to the film. On the other hand, if it is too large, the viscosity of the coating solution at the time of forming the alignment film increases, and it may be difficult to form a uniform coating film.

  Examples of the dimerization reactive polymer are the same as those described in JP-A-2006-350322, JP-A-2006-323214, JP-A-2005-258429, JP-A-2005-258428, and the like.

  As the photodimerization reactive compound, various photodimerization reaction sites and substituents can be selected from the above compounds according to the required properties. Moreover, the photodimerization reactive compound can also be used individually by 1 type or in combination of 2 or more types.

  Further, the photodimerization type material may contain an additive in addition to the photodimerization reactive compound as long as the photoalignment of the alignment film is not hindered. Examples of the additive include a polymerization initiator and a polymerization inhibitor.

  The polymerization initiator or polymerization inhibitor may be appropriately selected from generally known compounds according to the type of the photodimerization reactive compound. The addition amount of the polymerization initiator or the polymerization inhibitor is preferably in the range of 0.001% by mass to 20% by mass, and in the range of 0.1% by mass to 5% by mass with respect to the photodimerization reactive compound. It is more preferable that This is because if the addition amount of the polymerization initiator or polymerization inhibitor is too small, the polymerization may not be started (prohibited), whereas if too large, the reaction may be inhibited.

  Examples of the photoreactive material utilizing photolysis reaction include polyimide “RN1199” manufactured by Nissan Chemical Industries, Ltd.

  The wavelength region of light that causes photoreaction of the photoreactive material is preferably in the range of ultraviolet light, that is, in the range of 10 nm to 400 nm, and more preferably in the range of 250 nm to 380 nm.

  Next, the photo-alignment processing method will be described. First, a photo-alignment film forming coating solution obtained by diluting the above-described photoreactive material with an organic solvent is applied and dried.

  The content of the photodimerization reactive compound in the coating liquid for forming a photoalignment film is preferably in the range of 0.05% by mass to 10% by mass, and in the range of 0.2% by mass to 2% by mass. It is more preferable that If the content is less than the above range, it will be difficult to impart an appropriate anisotropy to the film. Conversely, if the content is more than the above range, the viscosity of the coating solution will increase, and a uniform coating film will be formed. Because it becomes difficult to do.

  Examples of the coating method for forming the coating liquid for forming a photo-alignment film include spin coating, roll coating, rod bar coating, spray coating, air knife coating, slot die coating, wire bar coating, ink jet, and flexo. A printing method, a screen printing method, or the like can be used.

  The film obtained by applying the coating liquid for forming a photo-alignment film can impart anisotropy by causing a photoreaction by irradiating light with controlled polarization. The polarization direction is not particularly limited as long as it can cause a photoreaction.

The light irradiation direction is preferably parallel to the longitudinal direction of the source line. As described above, since the step due to the gate line can be greatly reduced in the present invention, the light is not irradiated along the gate line by irradiating the light in parallel to the longitudinal direction of the source line. This is because it is possible to prevent the occurrence of misalignment and effectively suppress the occurrence of unevenness in the alignment treatment.
Note that the light irradiation direction being parallel to the longitudinal direction of the source line means that the angle formed by the light irradiation direction and the longitudinal direction of the source line is 0 ° ± 2 °.

  The thickness of the photo-alignment film is preferably in the range of 1 nm to 1000 nm, more preferably in the range of 3 nm to 100 nm. If the thickness of the photo-alignment film is smaller than the above range, sufficient optical alignment may not be obtained. Conversely, if the thickness of the photo-alignment film is larger than the above range, the cost may be disadvantageous. is there.

(Ii) Photoisomerizable material A photoisomerizable material is a material that imparts anisotropy to a film by causing a photoisomerization reaction. The photoisomerization type material used in the present invention is not particularly limited as long as it imparts anisotropy to the film by causing a photoisomerization reaction, but the film is anisotropic by causing a photoisomerization reaction. It is preferable that the compound contains a photoisomerization-reactive compound that imparts properties. By including such a photoisomerization reactive compound, a stable isomer among a plurality of isomers is increased by light irradiation, whereby anisotropy can be easily imparted to the film. .

  The photoisomerization reactive compound is not particularly limited as long as it is a material having the above-mentioned characteristics, but has a dichroism that makes absorption different depending on the polarization direction, and can be irradiated by light irradiation. It is preferable that it causes an isomerization reaction. This is because anisotropy can be easily imparted to the film by causing isomerization of the reaction site oriented in the polarization direction of the photoisomerization reactive compound having such characteristics.

  Further, the photoisomerization reaction in which the photoisomerization reactive compound is generated is preferably a cis-trans isomerization reaction. This is because irradiation with light increases the isomer of either the cis-isomer or the trans-isomer, thereby imparting anisotropy to the film.

  Examples of such photoisomerization-reactive compounds include monomolecular compounds and polymerizable monomers that are polymerized by light or heat. These may be appropriately selected according to the type of liquid crystal used, but the anisotropy can be stabilized by polymerizing the film after applying anisotropy to the film by light irradiation. It is preferable to use a functional monomer. Among such polymerizable monomers, an acrylate monomer and a methacrylate monomer are preferable because anisotropy is imparted to the film and the polymer can be easily polymerized while maintaining the anisotropy in a good state.

  The polymerizable monomer may be a monofunctional monomer or a polyfunctional monomer. However, since the anisotropy of the alignment film due to polymerization becomes more stable, it is a bifunctional monomer. Preferably there is.

  Specific examples of such a photoisomerization-reactive compound include compounds having a cis-trans isomerization-reactive skeleton such as an azobenzene skeleton or a stilbene skeleton.

  In this case, the number of cis-trans isomerization reactive skeletons contained in the molecule may be one or two or more. It is preferable that

  The cis-trans isomerization reactive skeleton may have a substituent in order to further enhance the interaction with the liquid crystal molecules. The substituent is not particularly limited as long as it can enhance the interaction with the liquid crystal molecules and does not interfere with the orientation of the cis-trans isomerization reactive skeleton, and examples thereof include a carboxyl group and a sulfonic acid. A sodium group, a hydroxyl group, etc. are mentioned. These structures can be appropriately selected according to the type of liquid crystal used.

In addition to the cis-trans isomerization reactive skeleton, the photoisomerization reactive compound contains many π electrons such as aromatic hydrocarbon groups so that the interaction with the liquid crystal molecules can be further enhanced. It may have an included group, and the cis-trans isomerization reactive skeleton and the aromatic hydrocarbon group may be bonded via a bonding group. The bonding group is not particularly limited as long as it can enhance the interaction with the liquid crystal molecule. For example, —COO—, —OCO—, —O—, —C≡C—, —CH ₂ —CH _2- , —CH ₂ O—, —OCH ₂ — and the like can be mentioned.

  In addition, when using a polymerizable monomer as a photoisomerization reactive compound, it is preferable to have the said cis-trans isomerization reactive skeleton as a side chain. This is because by having the cis-trans isomerization reactive skeleton as a side chain, the effect of anisotropy imparted to the film becomes larger, and it is particularly suitable for controlling the alignment of liquid crystals. . In this case, the aromatic hydrocarbon group or bonding group contained in the molecule is contained in the side chain together with the cis-trans isomerization reactive skeleton so that the interaction with the liquid crystal molecule is enhanced. It is preferable.

  Further, the side chain of the polymerizable monomer may have an aliphatic hydrocarbon group such as an alkylene group as a spacer so that the cis-trans isomerization reactive skeleton can be easily oriented.

  Among the photoisomerization reactive compounds of the monomolecular compound or polymerizable monomer as described above, the photoisomerization reactive compound used in the present invention is preferably a compound having an azobenzene skeleton in the molecule. This is because the azobenzene skeleton contains a lot of π electrons and thus has a high interaction with liquid crystal molecules and is particularly suitable for controlling the alignment of liquid crystals.

  When the azobenzene skeleton is irradiated with linearly polarized ultraviolet light, the trans azobenzene skeleton with the molecular long axis oriented in the polarization direction is changed to a cis isomer as shown in the following formula.

  Since the cis isomer of the azobenzene skeleton is chemically unstable compared to the trans isomer, it thermally or absorbs visible light and returns to the trans isomer. Whether to become the right transformer body occurs with the same probability. Therefore, if the ultraviolet light is continuously absorbed, the ratio of the right-side trans isomer increases, and the average orientation direction of the azobenzene skeleton becomes perpendicular to the polarization direction of the ultraviolet light. In the present invention, this phenomenon is used to align the orientation direction of the azobenzene skeleton, impart anisotropy to the film, and control the alignment of liquid crystal molecules on the film.

Among the compounds having an azobenzene skeleton in the molecule, as monomolecular compounds, JP-A-2006-350322, JP-A-2006-323214, JP-A-2005-258429, JP-A-2005-258428, etc. Similar to those described.
Examples of the polymerizable monomer having an azobenzene skeleton as a side chain include those described in JP-A-2006-350322, JP-A-2006-323214, JP-A-2005-258429, JP-A-2005-258428, and the like. It is the same as that.

  In the present invention, various cis-trans isomerization reactive skeletons and substituents can be selected from such photoisomerization reactive compounds according to required characteristics. In addition, these photoisomerization reactive compounds can also be used individually by 1 type or in combination of 2 or more types.

  In addition to the photoisomerization reactive compound, the photoisomerization type material may contain an additive within a range that does not interfere with the photoalignment of the alignment film. When a polymerizable monomer is used as the photoisomerization reactive compound, examples of the additive include a polymerization initiator and a polymerization inhibitor.

  The polymerization initiator or polymerization inhibitor may be appropriately selected from generally known compounds according to the type of photoisomerization reactive compound. The addition amount of the polymerization initiator or polymerization inhibitor is preferably in the range of 0.001% by mass to 20% by mass, and in the range of 0.1% by mass to 5% by mass with respect to the photoisomerization reactive compound. More preferably, it is within. This is because if the addition amount of the polymerization initiator or polymerization inhibitor is too small, the polymerization may not be started (prohibited), whereas if too large, the reaction may be inhibited.

  The wavelength region of the light that causes the photoisomerization reaction of the photoisomerizable material is preferably in the ultraviolet light range, that is, in the range of 10 nm to 400 nm, and more preferably in the range of 250 nm to 380 nm. .

  Next, the photo-alignment processing method will be described. First, a photo-alignment film-forming coating solution obtained by diluting the above-described photoisomerizable material with an organic solvent is applied and dried.

  The content of the photoisomerization-reactive compound in the coating liquid for forming a photoalignment film is preferably in the range of 0.05% by mass to 10% by mass, and in the range of 0.2% by mass to 2% by mass. More preferably, it is within. If the content is less than the above range, it will be difficult to impart an appropriate anisotropy to the film. Conversely, if the content is more than the above range, the viscosity of the coating solution will increase, and a uniform coating film will be formed. Because it becomes difficult to do.

  Examples of the coating method for forming the coating liquid for forming a photo-alignment film include spin coating, roll coating, rod bar coating, spray coating, air knife coating, slot die coating, wire bar coating, ink jet, and flexo. A printing method, a screen printing method, or the like can be used.

  A film obtained by applying the coating liquid for forming a photo-alignment film can be imparted with anisotropy by causing a photoisomerization reaction by irradiating light with controlled polarization. The polarization direction is not particularly limited as long as it can cause a photoisomerization reaction.

The light irradiation direction is preferably parallel to the longitudinal direction of the source line. As described above, since the step due to the gate line can be greatly reduced in the present invention, the light is not irradiated along the gate line by irradiating the light in parallel to the longitudinal direction of the source line. This is because it is possible to prevent the occurrence of misalignment and effectively suppress the occurrence of unevenness in the alignment treatment.
Note that the light irradiation direction being parallel to the longitudinal direction of the source line means that the angle formed by the light irradiation direction and the longitudinal direction of the source line is 0 ° ± 2 °.

  Further, when a polymerizable monomer is used as the photoisomerization type material among the above photoisomerization reactive compounds, it is polymerized by heating after photoalignment treatment and applied to the alignment film. Anisotropy can be stabilized.

  The thickness of the photo-alignment film is preferably in the range of 1 nm to 1000 nm, more preferably in the range of 3 nm to 100 nm. If the thickness of the photo-alignment film is smaller than the above range, sufficient optical alignment may not be obtained. Conversely, if the thickness of the photo-alignment film is larger than the above range, the cost may be disadvantageous. is there.

4). Gate line The gate line in this invention is formed on a base material.
Since the gate line is the same as the gate electrode constituting the TFT, description thereof is omitted here.

5). Source Line The source line in the present invention is formed on the overcoat layer so as to intersect the gate line.
Since the source line is the same as the source electrode constituting the TFT, description thereof is omitted here.

6). Pixel Electrode The pixel electrode in the present invention is formed on the overcoat layer.
Note that the pixel electrode is the same as the transparent electrode that constitutes the TFT, and a description thereof is omitted here.

7). Gate Insulating Layer The gate insulating layer in the present invention is formed so as to cover the gate line.
Note that the gate insulating layer is the same as the TFT gate insulating layer constituting the TFT, and thus the description thereof is omitted here.

8). Base material The base material used in the present invention supports the gate line, source line, TFT, pixel electrode, and the like.
The substrate is not necessarily required to have transparency. That is, when a liquid crystal display element is produced using the TFT substrate of the present invention, the TFT substrate of the present invention is usually disposed on the side opposite to the image observation surface. Therefore, when a transmissive liquid crystal display element such as a backlight system is manufactured using the TFT substrate of the present invention, it is necessary that the substrate has transparency, but a reflective liquid crystal display element is manufactured. In some cases, it is not necessary to have transparency.

As a base material, what is generally used as a base material for liquid crystal display devices, such as a glass substrate and a resin film base material, can be used without a restriction | limiting in particular.
Examples of the resin film substrate include thermoplastic films such as polyethylene terephthalate (PET), polycarbonate (PC), and polyethersulfone (PES), crosslinkable resins such as epoxy resins, organic-inorganic composite materials, Polyimide (PI), polyamide, aromatic polyamide, polyethylene (PE), polypropylene (PP), polyester, polyolefin, polyacrylonitrile, ethylene vinyl acetate copolymer (EVA), cellulose triacetate (TAC), polyethylene naphthalate, The film which consists of polyphenylene sulfide (PPS), polyether ether ketone (PEEK), etc. can be mentioned.

Further, when the substrate is required to have transparency, the transmittance in the visible light region is preferably 80% or more, and more preferably 90% or more. This is because, when the transmittance is in the above range, it is possible to prevent the display luminance of the liquid crystal display element from being lowered when the liquid crystal display element is manufactured using the TFT substrate of the present invention.
In addition, the transmittance | permeability of a base material can be measured by JISK7361-1 (the test method of the total light transmittance of a plastic-transparent material).

9. Application The TFT substrate of the present invention is preferably used for a liquid crystal display element using a ferroelectric liquid crystal. Ferroelectric liquid crystals are difficult to align because they have higher molecular ordering than nematic liquid crystals. Therefore, if there is uneven alignment treatment, alignment defects called zigzag defects, hairpin defects, double domains, etc. are likely to occur. On the other hand, in the present invention, since the occurrence of alignment processing unevenness can be suppressed, the occurrence of alignment defects peculiar to the ferroelectric liquid crystal can also be suppressed. Therefore, the TFT substrate of the present invention is suitable for a liquid crystal display element using a ferroelectric liquid crystal. In the present invention, the unevenness due to the TFT and the gate line can be eliminated, so that it is suitable for the ferroelectric liquid crystal in which the alignment is easily disturbed by the unevenness.

  The TFT substrate of the present invention is preferably used for a liquid crystal display element driven by a field sequential method. In the present invention, since the charging time can be shortened, the time required for writing scanning and erasing scanning can be shortened, which is preferably applied to driving by a field sequential method.

B. Next, the liquid crystal display element of the present invention will be described. In the liquid crystal display element of the present invention, the above-described TFT substrate and the second electrode and the second alignment film are sequentially laminated on the second base material, and the alignment film and the second alignment film face the TFT substrate. And a liquid crystal layer formed between the alignment film and the second alignment film.

The liquid crystal display element of the present invention will be described with reference to the drawings. FIG. 7 is a schematic cross-sectional view showing an example of the liquid crystal display element of the present invention, and corresponds to a cross-sectional view taken along line BB in FIG.
In the liquid crystal display element illustrated in FIG. 7, a liquid crystal layer 30 is formed between the alignment film 9 of the TFT substrate 1 and the second alignment film 39 of the counter substrate 31.

As illustrated in FIGS. 1 and 7, the TFT substrate 1 includes a base material 2, a gate line 3 formed on the base material 2, a gate insulating layer 4 formed to cover the gate line 3, An overcoat layer 6 formed on the gate insulating layer 4; a source line 7 formed on the overcoat layer 6 so as to intersect the gate line 3; and a pixel electrode 8 formed on the overcoat layer 6; And the TFT 10 formed on the substrate 2.
In addition, as illustrated in FIG. 7, the TFT 10 is formed on the base 2 and is formed continuously with the gate electrode 13 connected to the gate line 3 and the gate insulating layer 4 so as to cover the gate electrode 13. The TFT gate insulating layer 14, the semiconductor layer 15 formed on the TFT gate insulating layer 14, and the overcoat layer 6 are continuously formed on the TFT gate insulating layer 14 and the semiconductor layer 15. TFT overcoat layer 16, source electrode 17 formed on TFT overcoat layer 16, connected to source line 7, connected to semiconductor layer 15 via source electrode contact hole h 1, and TFT A transparent electrode 18 formed on the overcoat layer 16, connected to the pixel electrode 8, and connected to the semiconductor layer 15 via a transparent electrode contact hole h 2; .

  On the other hand, in the counter substrate 31, as illustrated in FIG. 7, the second electrode 38 is formed on the second base material 32, and the second alignment film 39 is formed on the second electrode 38.

According to the present invention, since the above-described TFT substrate is used, occurrence of alignment processing unevenness can be suppressed, occurrence of liquid crystal alignment failure can be suppressed, and display unevenness and contrast deterioration can be reduced. That is, a liquid crystal display element with good display quality and high contrast can be obtained.
Further, since the above-described TFT substrate is used, the storage capacity can be reduced, the charging time can be shortened, and a voltage can be easily applied to the gate electrode.

  Since the TFT substrate has been described in detail in the section “A. TFT substrate”, description thereof is omitted here. Hereinafter, the other structure in the liquid crystal display element of this invention is demonstrated.

1. Liquid Crystal Layer The liquid crystal layer in the present invention is formed between the alignment film of the TFT substrate and the second alignment film of the counter substrate, and includes a liquid crystal material.

  The liquid crystal material used for the liquid crystal layer can be regularly arranged by the alignment regulating force of the alignment film of the TFT substrate and the second alignment film of the counter substrate, and can perform a switching function in the liquid crystal display element. The liquid crystal material is not particularly limited as long as it is used, and a liquid crystal material generally used for a liquid crystal display element can be used.

Among these, it is preferable to use a ferroelectric liquid crystal as the liquid crystal material. Ferroelectric liquid crystals are difficult to align because they have higher molecular ordering than nematic liquid crystals. Therefore, if there is uneven alignment treatment, alignment defects called zigzag defects, hairpin defects, double domains, etc. are likely to occur. On the other hand, in the present invention, since the occurrence of alignment processing unevenness can be suppressed, the occurrence of alignment defects peculiar to the ferroelectric liquid crystal can also be suppressed.
Hereinafter, the ferroelectric liquid crystal will be described.

Ferroelectric liquid crystal used in the present invention is not limited in particular as long as it expresses a chiral smectic C phase (SmC ^*). For example, the phase sequence changes in phase with a nematic phase (N) -cholesteric phase (Ch) -chiral smectic C phase (SmC ^* ) in the temperature lowering process, or a nematic phase (N) -chiral smectic C phase (SmC ^* ). , Nematic phase (N) -smectic A phase (SmA) -chiral smectic C phase (SmC ^* ), phase change, nematic phase (N) -cholesteric phase (Ch) -smectic A phase (SmA ) -Chiral smectic C phase (SmC ^* ) and the like.

  When the liquid crystal display element of the present invention is driven by a field sequential color system, it is preferable to use a ferroelectric liquid crystal that exhibits monostability. This is because by using a ferroelectric liquid crystal exhibiting monostability, gradation control can be performed by voltage modulation, and high-definition and high-quality display can be realized.

  As illustrated in FIG. 8, the ferroelectric liquid crystal rotates along a cone ridge line in which the liquid crystal molecules 30 a are inclined from the layer normal line z and have a bottom surface perpendicular to the layer normal line z. In such a cone, the tilt angle of the liquid crystal molecules 30a with respect to the layer normal z is referred to as a tilt angle θ.

  “Showing monostability” means a state in which the state of the ferroelectric liquid crystal when no voltage is applied is stabilized in one state. More specifically, as shown in FIG. 8, the liquid crystal molecules 30a can operate on a cone between two states tilted by a tilt angle ± θ with respect to the layer normal z. A state where 30a is stabilized in any one state on the cone.

Among ferroelectric liquid crystals exhibiting monostability, for example, as shown in FIG. 9, liquid crystal molecules operate only when a positive or negative voltage is applied, and half-V shaped switching (hereinafter referred to as half-V shaped switching). Particularly preferred are those exhibiting properties. Using a ferroelectric liquid crystal exhibiting such a half V-shaped switching characteristic, it is possible to take a sufficiently long opening time as a black and white shutter, thereby making it possible to display each color that is temporally switched brighter. This is because a bright color display liquid crystal display element can be realized.
The “half V-shaped switching characteristic” refers to an electro-optical characteristic in which the light transmittance with respect to an applied voltage is asymmetric.

  Such a ferroelectric liquid crystal can be variously selected from generally known liquid crystal materials according to required characteristics.

In particular, a liquid crystal material that exhibits an SmC ^* phase from the Ch phase without passing through the SmA phase is suitable as a material that exhibits a half V-shaped switching characteristic. Specifically, “R2301” manufactured by AZ Electronic Materials may be mentioned.

In addition, as the liquid crystal material that passes through the SmA phase, a material that expresses the SmC ^* phase from the Ch phase through the SmA phase is preferable because of a wide range of material selection. In this case, a single liquid crystal material exhibiting an SmC ^* phase can be used, but a non-chiral liquid crystal (hereinafter sometimes referred to as a host liquid crystal) having a low viscosity and easily exhibiting an SmC phase is used. By adding a small amount of an optically active substance that does not show large spontaneous polarization and an appropriate helical pitch, the liquid crystal material showing the phase sequence as described above has low viscosity and can realize faster response. preferable.

  The host liquid crystal and the optically active substance added to the host liquid crystal are described in JP 2006-350322 A, JP 2006-323214 A, JP 2005-258429 A, JP 2005-258428 A, and the like. Is the same as

  Specific examples of the ferroelectric liquid crystal passing through the SmA phase include “FELIXM4851-100” manufactured by AZ Electronic Materials.

  In addition to the ferroelectric liquid crystal, the liquid crystal layer may contain a compound having any function depending on the function required for the liquid crystal display element. Examples of the compound include a polymerized polymerizable monomer. By containing such a polymerizable monomer polymer in the liquid crystal layer, the alignment of the liquid crystal material is so-called “polymer stabilization”, and a liquid crystal display device excellent in alignment stability can be obtained.

  The polymerized monomer is the same as that described in JP-A-2006-323217.

  The thickness of the liquid crystal layer is preferably in the range of 1.2 μm to 3.0 μm, more preferably 1.3 μm to 2.5 μm, and still more preferably in the range of 1.4 μm to 2.0 μm. This is because if the thickness of the liquid crystal layer is too thin, the contrast may be lowered. Conversely, if the thickness of the liquid crystal layer is too thick, the liquid crystal may be difficult to align. The thickness of the liquid crystal layer can be adjusted by bead spacers, column spacers, partition walls, or the like.

2. Counter substrate In the present invention, the counter substrate is obtained by sequentially laminating the second electrode and the second alignment film on the second base material, and the alignment film and the second alignment film face the TFT substrate. It is arranged as follows.

  Since the second base material is the same as the base material in the TFT substrate, description thereof is omitted here. Hereinafter, another configuration of the counter substrate will be described.

(1) Second alignment film The second alignment film has an alignment regulating force for the liquid crystal material. The second alignment film may be any film that can align liquid crystal, for example, a rubbing alignment film, a photo-alignment film, a reactive liquid crystal alignment film for aligning reactive liquid crystals, and reactivity. Examples include a laminate of a fixed liquid crystal layer in which liquid crystal is fixed.
The alignment film and the optical alignment film that have been subjected to the rubbing treatment are the same as those described in the section of the alignment film of “A. TFT substrate”, and thus the description thereof is omitted here. Hereinafter, the composition of the constituent material of the alignment film for the reactive liquid crystal and the fixed liquid crystal layer, and the alignment film of the TFT substrate and the second alignment film of the counter substrate will be described.

(I) Reactive liquid crystal alignment film and immobilized liquid crystal layer The second alignment film is formed on the reactive liquid crystal alignment film formed on the second substrate and the reactive liquid crystal alignment film. It may consist of a fixed liquid crystal layer formed by fixing liquid crystal. When forming the fixed liquid crystal layer on the alignment film for reactive liquid crystal, the reactive liquid crystal is aligned by the alignment film for reactive liquid crystal, and the reactive liquid crystal is polymerized by irradiating ultraviolet rays, for example. The orientation state can be fixed. Therefore, it is possible to impart the alignment regulating force of the alignment film for reactive liquid crystal to the fixed liquid crystal layer, and the fixed liquid crystal layer can act as an alignment film for aligning the liquid crystal. Further, since the reactive liquid crystal is fixed, it has an advantage that it is not affected by temperature or the like. Furthermore, reactive liquid crystals are relatively similar in structure to the liquid crystals that make up the liquid crystal layer, and the interaction with the liquid crystals is stronger, so the alignment of the liquid crystals is more effective than when a single-layer alignment film is used. Can be controlled. Hereinafter, the description will be divided into the alignment film for reactive liquid crystal and the fixed liquid crystal layer.

(Fixed liquid crystal layer)
The fixed liquid crystal layer used in the present invention is formed on the alignment film for reactive liquid crystal and is formed by fixing reactive liquid crystal.

  The reactive liquid crystal used in the present invention preferably exhibits a nematic phase. This is because the nematic phase is relatively easy to control the alignment among the liquid crystal phases.

  The reactive liquid crystal preferably contains a polymerizable liquid crystal material. This is because the alignment state of the reactive liquid crystal can be fixed. As the polymerizable liquid crystal material, any of a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, and a polymerizable liquid crystal polymer can be used, and among them, a polymerizable liquid crystal monomer is preferably used. The polymerizable liquid crystal monomer can be aligned at a lower temperature than other polymerizable liquid crystal materials, that is, a polymerizable liquid crystal oligomer and a polymerizable liquid crystal polymer, and has high sensitivity in alignment, and can be easily aligned. Because you can.

  The polymerizable liquid crystal monomer is not particularly limited as long as it is a liquid crystal monomer having a polymerizable functional group, and examples thereof include a monoacrylate monomer and a diacrylate monomer. These polymerizable liquid crystal monomers may be used alone or in combination of two or more.

  Monoacrylate monomers and diacrylate monomers are the same as those described in JP-A-2006-350322, JP-A-2006-323214, JP-A-2005-258429, JP-A-2005-258428, and the like. .

  In the present invention, a diacrylate monomer is preferred among the polymerizable liquid crystal monomers. This is because the diacrylate monomer can be easily polymerized while maintaining the orientation state in a good state.

  The polymerizable liquid crystal monomer described above does not have to exhibit a nematic phase. These polymerizable liquid crystal monomers may be used as a mixture of two or more kinds as described above, because the composition in which these are mixed, that is, the reactive liquid crystal may exhibit a nematic phase. It is.

  Furthermore, in this invention, you may add a photoinitiator, a polymerization inhibitor, etc. to the said reactive liquid crystal as needed. For example, when polymerizing a polymerizable liquid crystal material by electron beam irradiation, a photopolymerization initiator may not be necessary, but in the case of polymerization by, for example, ultraviolet irradiation, usually photopolymerization is started. This is because the agent is used for promoting the polymerization. As the photopolymerization initiator, for example, a photopolymerization initiator described in JP-A-2005-258428 can be used. Moreover, it is also possible to add a sensitizer other than a photoinitiator in the range which does not impair the objective of this invention.

  The amount of the photopolymerization initiator added is generally 0.01 to 20% by mass, preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass. It can be added to the liquid crystal.

  The thickness of the fixed liquid crystal layer is appropriately adjusted according to the target anisotropy, and can be set, for example, within a range of 1 nm to 1000 nm, and preferably within a range of 3 nm to 100 nm. This is because if the fixed liquid crystal layer is too thick, anisotropy more than necessary occurs, and if the fixed liquid crystal layer is too thin, the predetermined anisotropy may not be obtained.

  Next, a method for forming the fixed liquid crystal layer will be described. The fixed liquid crystal layer is formed by applying a reactive liquid crystal composition containing the reactive liquid crystal on the alignment film for reactive liquid crystal, performing an alignment treatment, and fixing the alignment state of the reactive liquid crystal. Can do.

  Further, instead of applying the reactive liquid crystal composition, a method of forming a dry film or the like in advance and laminating the film on the reactive liquid crystal alignment film can also be used. From the viewpoint of the simplicity of the manufacturing process, it is possible to prepare a reactive liquid crystal composition by dissolving a reactive liquid crystal in a solvent, apply this onto a reactive liquid crystal alignment film, and use a method of removing the solvent. preferable.

  The solvent used in the reactive liquid crystal composition is not particularly limited as long as it can dissolve the reactive liquid crystal and the like and does not inhibit the alignment ability of the alignment film for reactive liquid crystal. As such a solvent, for example, a solvent described in JP-A-2005-258428 can be used. A solvent may be used independently and may use 2 or more types together.

  Further, if only a single kind of solvent is used, the solubility of the reactive liquid crystal or the like may be insufficient, or the reactive liquid crystal alignment film may be eroded as described above. In this case, this inconvenience can be avoided by using a mixture of two or more solvents. Among the above-mentioned solvents, hydrocarbons and glycol monoether acetate solvents are preferable as the sole solvent, and a mixed system of ethers or ketones and glycol solvent is preferable as the mixed solvent. It is.

  Although the concentration of the reactive liquid crystal composition depends on the solubility of the reactive liquid crystal and the thickness of the immobilized liquid crystal layer, it cannot be defined unconditionally, but is usually 0.1% by mass to 40% by mass, preferably 1% by mass. It adjusts in the range of% -20 mass%. If the concentration of the reactive liquid crystal composition is lower than the above range, the reactive liquid crystal may be difficult to align. Conversely, if the concentration of the reactive liquid crystal composition is higher than the above range, the viscosity of the reactive liquid crystal composition is low. It is because it becomes high and it may become difficult to form a uniform coating film.

  Furthermore, a compound such as that described in JP-A-2005-258428 can be added to the reactive liquid crystal composition as long as the object of the present invention is not impaired. The amount of these compounds added to the reactive liquid crystal is selected within a range that does not impair the object of the present invention. Addition of these compounds improves the curability of the reactive liquid crystal, increases the mechanical strength of the resulting fixed liquid crystal layer, and improves its stability.

  Examples of a method for applying such a reactive liquid crystal composition include spin coating, roll coating, printing, dip coating, die coating, casting, bar coating, blade coating, spray coating, and gravure. Examples thereof include a coating method, a reverse coating method, an extrusion coating method, an ink jet method, a flexographic printing method, and a screen printing method.

  In addition, the solvent is removed after the reactive liquid crystal composition is applied, and the removal of the solvent is performed by, for example, removal under reduced pressure or removal by heating, or a combination thereof.

  In the present invention, the reactive liquid crystal applied as described above is aligned by the alignment film for reactive liquid crystal so as to have liquid crystal regularity. That is, a nematic phase is developed in the reactive liquid crystal. This is usually performed by a method such as a method of performing a heat treatment below the NI transition point. Here, the NI transition point indicates the temperature at which the liquid crystal phase transitions to the isotropic phase.

  As described above, the reactive liquid crystal has a polymerizable liquid crystal material, and in order to fix the alignment state of such a polymerizable liquid crystal material, a method of irradiating active radiation that activates polymerization is used. . The active radiation as used herein refers to radiation capable of causing polymerization of the polymerizable liquid crystal material. If necessary, a photopolymerization initiator may be included in the polymerizable liquid crystal material.

  The actinic radiation is not particularly limited as long as it is a radiation capable of polymerizing the polymerizable liquid crystal material, but usually ultraviolet light or visible light is used from the viewpoint of the ease of the apparatus. Irradiation light having a wavelength of 150 nm to 500 nm, preferably 250 nm to 450 nm, more preferably 300 nm to 400 nm is used.

  In the present invention, a method of irradiating ultraviolet rays with active radiation to a polymerizable liquid crystal material in which the photopolymerization initiator generates radicals with ultraviolet rays and the polymerizable liquid crystal material undergoes radical polymerization is a preferable method. . This is because the method using ultraviolet rays as actinic radiation is an already established technique, and therefore it can be easily applied to the present invention including the photopolymerization initiator to be used.

  As the light source of this irradiation light, low pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), high pressure discharge lamp (high pressure mercury lamp, metal halide lamp), short arc discharge lamp (super high pressure mercury lamp, xenon lamp, mercury xenon) Lamp). In particular, the use of metal halide lamps, xenon lamps, high-pressure mercury lamps, etc. is recommended. The irradiation intensity is appropriately adjusted according to the composition of the reactive liquid crystal and the amount of photopolymerization initiator.

  Such irradiation with active radiation may be performed under a temperature condition in which the polymerizable liquid crystal material becomes a liquid crystal phase, or may be performed at a temperature lower than the temperature at which the liquid crystal phase is formed. This is because the alignment state of the polymerizable liquid crystal material once in the liquid crystal phase is not disturbed suddenly even if the temperature is lowered thereafter.

  As a method for fixing the alignment state of the polymerizable liquid crystal material, in addition to the method of irradiating the active radiation, a method of polymerizing the polymerizable liquid crystal material by heating can also be used. As the reactive liquid crystal used in this case, it is preferable that the polymerizable liquid crystal monomer contained in the reactive liquid crystal is thermally polymerized below the NI transition point of the reactive liquid crystal.

(Alignment film for reactive liquid crystal)
The reactive liquid crystal alignment film used in the present invention is not particularly limited as long as it can align the reactive liquid crystal and does not adversely affect the alignment state of the reactive liquid crystal. It is not something. As the alignment film for reactive liquid crystal, for example, the above-mentioned rubbing-treated alignment film, photo-alignment film, or the like can be used.

(Ii) Composition of the constituent materials of the alignment film of the TFT substrate and the second alignment film of the counter substrate The combination of materials used for the alignment film of the TFT substrate and the second alignment film of the counter substrate is not particularly limited. However, when a ferroelectric liquid crystal is used for the liquid crystal layer, it is preferable that the constituent materials of the alignment film and the second alignment film have different compositions. By forming the alignment film and the second alignment film using materials having different compositions, the polarities of the alignment film surface and the second alignment film surface can be made different depending on the respective materials. As a result, the polar surface interaction between the ferroelectric liquid crystal and the alignment film is different from the polar surface interaction between the ferroelectric liquid crystal and the second alignment film. This is because the occurrence of alignment defects such as zigzag defects, hairpin defects, and double domains can be suppressed by appropriately selecting materials in consideration.

  In particular, a ferroelectric liquid crystal having a phase sequence that does not pass through the SmA phase is likely to generate two regions (double domains) having different layer normal directions, but the constituent materials of the alignment film and the second alignment film are different from each other. By having, it is possible to effectively suppress the occurrence of double domains. As a result, a monodomain orientation can be obtained.

  In order to make the composition of the constituent materials of the alignment film and the second alignment film different, for example, one is a photo-alignment film and the other is a rubbing-treated alignment film, or the alignment film is a photo-alignment film or a rubbing process. The second alignment film may be formed by laminating the alignment film for reactive liquid crystal and the fixed liquid crystal layer. Also, both are rubbed alignment films and the composition of the constituent materials of the rubbed alignment film are different, or both are photo-alignment films and the composition of the constituent materials of the photo-alignment film are different. By doing so, the composition of the constituent materials of the alignment film and the second alignment film can be made different.

  When the alignment film and the second alignment film are photo-alignment films, for example, a photo-isomerization material is used for one photo-alignment film, and a photo-reactive material is used for the other photo-alignment film, thereby forming the photo-alignment film The composition of the materials can be different.

  When the alignment film and the second alignment film are photo-alignment films using a photo-isomerization type material, a cis-trans isomerization-reactive skeleton or substituent is selected from photo-isomerization-reactive compounds according to required characteristics. By selecting variously, the composition of the constituent material of the photo-alignment film can be made different. Furthermore, the composition can be changed by changing the amount of the additive added.

  When the alignment film and the second alignment film are photo-alignment films using a photoreactive material, the composition of the constituent material of the photo-alignment film can be changed by variously selecting a photodimerization reactive compound such as a photodimerization reactive polymer. Can be different. Furthermore, the composition can be changed by changing the amount of the additive added.

  As a combination of materials used for the alignment film and the second alignment film, among the above, one is a photo-alignment film using a photodimerization type material, and the other is a photo-alignment film using a photoisomerization type material. One is a photo-alignment film using a photodimerization-type material, the other is a rubbing-processed alignment film, one is a photo-alignment film using a photo-isomerization-type material, and the other is a rubbing-processed alignment film Alternatively, it is preferable that the alignment film is a photo-alignment film or a rubbing-treated alignment film, and the second alignment film is a laminate of a reactive liquid crystal alignment film and a fixed liquid crystal layer. Photo-alignment films using photodimerization materials tend to have a relatively positive polarity compared to photo-alignment films using photoisomerization-type materials. In addition, the spontaneous polarization negative electrode of the ferroelectric liquid crystal tends to face the photo-alignment film side using the photodimerization type material. A photo-alignment film using a photodimerization type material tends to have a relatively positive polarity relative to a rubbing-processed alignment film. Therefore, due to the polar surface interaction, the negative polarity of spontaneous polarization of the ferroelectric liquid crystal There is a tendency to face the photo-alignment film side using the quantification type material. Since the rubbing-treated alignment film tends to have a relatively positive polarity relative to the photo-alignment film using the photoisomerizable material, the negative polarity of the spontaneous polarization of the ferroelectric liquid crystal is caused by the polar surface interaction. There is a tendency to face the rubbing-treated alignment film side. Since the fixed liquid crystal layer tends to have a relatively positive polarity relative to the photo-alignment film or the alignment film subjected to the rubbing treatment, the negative polarity of the spontaneous polarization of the ferroelectric liquid crystal is fixed by the polar surface interaction. It tends to face the layer side. In the case of such a combination, the direction of spontaneous polarization of the ferroelectric liquid crystal can be controlled, and the occurrence of alignment defects can be effectively suppressed.

In particular, the alignment film is a photo-alignment film using a photodimerization material, the second alignment film is a photoalignment film using a photoisomerization material, and the alignment film is a photoalignment film using a photodimerization material. Preferably, the second alignment film is a rubbing-treated alignment film, or the alignment film is a rubbing-treated alignment film, and the second alignment film is a photo-alignment film using a photoisomerizable material.
When the ferroelectric liquid crystal is dropped on the alignment film of the TFT substrate when manufacturing the liquid crystal display element of the present invention, the spontaneous polarization of the ferroelectric liquid crystal is caused on the TFT substrate side on which the ferroelectric liquid crystal is dropped. The negative electrode tends to face. In addition, as described above, the photo-alignment film using the photodimerization type material tends to have a relatively positive polarity more than the photoalignment film using the photoisomerization type material. The photo-alignment film tends to have a stronger positive polarity than the alignment film subjected to the rubbing treatment, and the alignment film subjected to the rubbing process is relatively more than the photo-alignment film using the photoisomerization type material. There is a tendency for positive polarity to be strong. Therefore, in order to effectively suppress alignment defects, it is preferable that the combination of materials used for the alignment film and the second alignment film is as described above.

(2) Second electrode The second electrode is not particularly limited as long as it is generally used as an electrode of a liquid crystal display element. For example, indium oxide, tin oxide, indium tin oxide (ITO), or the like is used for the second electrode.
Examples of the method for forming the second electrode include chemical vapor deposition (CVD), physical vapor deposition (PVD) such as sputtering, ion plating, and vacuum deposition.

(3) Other configurations In the counter substrate, a colored layer may be formed on the second base material. When a colored layer is formed, a color filter type liquid crystal display element capable of realizing color display by the colored layer can be obtained.
The colored layer is not particularly limited as long as it is generally used as a colored layer of a color filter.
As a method for forming the colored layer, a method for forming a colored layer in a general color filter can be used. For example, a pigment dispersion method (color resist method, etching method), a printing method, an inkjet method, or the like can be used. it can.

The counter substrate may be arranged so that the alignment film and the second alignment film face the TFT substrate. Usually, the alignment direction of the liquid crystal molecules by the alignment process of the alignment film on the TFT substrate and the counter substrate It arrange | positions so that the orientation direction of the liquid crystal molecule by the orientation process of a 2nd orientation film may have a predetermined relationship. This predetermined relationship is appropriately selected according to the type of liquid crystal used.
For example, when nematic liquid crystal is used as the liquid crystal and the liquid crystal display element is driven in the twisted nematic (TN) mode, the alignment direction of the liquid crystal molecules by the alignment treatment of the alignment film on the TFT substrate and the second alignment film on the counter substrate The TFT substrate and the counter substrate are arranged so that the alignment direction of the liquid crystal molecules by the alignment treatment is perpendicular. In this case, specifically, the TFT substrate and the counter substrate are arranged so that the rubbing process direction on the TFT substrate and the rubbing process direction on the counter substrate are perpendicular to each other.
For example, when a ferroelectric liquid crystal is used as the liquid crystal, the alignment direction of the liquid crystal molecules by the alignment treatment of the alignment film on the TFT substrate is parallel to the alignment direction of the liquid crystal molecules by the alignment treatment of the second alignment film on the counter substrate. The TFT substrate and the counter substrate are arranged so as to be. In this case, specifically, the TFT substrate and the counter substrate are arranged so that the rubbing process direction on the TFT substrate and the rubbing process direction on the counter substrate are parallel to each other.

C. Next, a method for manufacturing a liquid crystal display element of the present invention will be described. The method for producing a liquid crystal display element of the present invention can be divided into two embodiments depending on the method for forming the liquid crystal layer. In the following, each embodiment will be described separately.

1. First Embodiment In a first embodiment of the method for producing a liquid crystal display element of the present invention, a liquid crystal is dropped in a straight line on the alignment film of the above-described TFT substrate, either perpendicularly or parallel to the longitudinal direction of the source line. A liquid crystal dropping step, a TFT substrate on which the liquid crystal is dropped, a substrate bonding step of bonding a counter substrate in which a second electrode and a second alignment film are sequentially laminated on the second base material, the TFT substrate, And a liquid crystal alignment step for aligning the liquid crystal filled between the counter substrates.

The manufacturing method of the liquid crystal display element of this embodiment is demonstrated referring drawings. FIG. 10 is a process diagram showing an example of a method for manufacturing a liquid crystal display element of this embodiment.
In the method for manufacturing a liquid crystal display element of this embodiment, first, an alignment film forming layer 19 is formed on a substrate on which the gate line 3, the source line 7, the pixel electrode 8, the TFT 10 and the like are formed. The film forming layer 19 is rubbed in parallel to the longitudinal direction 51 of the source line 7 (FIG. 10A, alignment film forming step). In this case, the longitudinal direction 51 of the source line 7 and the alignment treatment direction (rubbing treatment direction) 52a are parallel to each other.

  Next, on the alignment film 9 formed in the alignment film forming step, liquid crystal 30b in an isotropic phase is dropped in a continuous manner perpendicular to the longitudinal direction 51 of the source line 7 (FIG. 10 (b), liquid crystal dropping step). That is, the dropping direction 54 of the liquid crystal 30 b is set perpendicular to the longitudinal direction 51 of the source line 7.

Note that dropping the liquid crystal perpendicular to the longitudinal direction of the source line means that the angle formed by the longitudinal direction of the source line and the dropping direction of the liquid crystal is 90 ° ± 1 °.
Further, the liquid crystal dropping direction refers to a direction of scanning while dropping the liquid crystal.

  Next, after the liquid crystal is dropped, a sealing material 41 is formed in a frame shape on the TFT substrate 1 so as to surround the liquid crystal sealing region (FIG. 11). Next, although not shown, a TFT substrate in which liquid crystal is dropped and a sealing material is further formed, and a counter substrate in which a second electrode and a second alignment film are stacked in this order on a second base material, an alignment film and It arrange | positions so that a 2nd alignment film may oppose, fully pressure-reduces between a TFT substrate and a counter substrate, and a TFT substrate and a counter substrate are piled up under pressure reduction. At this time, liquid crystal is filled between the TFT substrate and the counter substrate. Next, the sealing material is heated and cured, and the TFT substrate and the counter substrate are bonded together (substrate bonding step).

  Next, the liquid crystal filled between the TFT substrate and the counter substrate is aligned by gradually cooling to room temperature (liquid crystal alignment step).

  When the rubbing treatment is performed, the liquid crystal molecules are aligned along the rubbing treatment direction. Therefore, as illustrated in FIG. 10B, the alignment direction 53a of the liquid crystal molecules by the alignment treatment (rubbing treatment) is the alignment treatment direction ( (Rubbing direction) 52a. In this case, when the liquid crystal 30b flows on the alignment film 9, it tends to flow perpendicularly to the dropping direction 54 of the liquid crystal 30b. That is, the flow direction 55 of the liquid crystal 30b is parallel to the alignment direction 53a of the liquid crystal molecules by the alignment process (rubbing process). Thereby, generation | occurrence | production of the alignment disorder resulting from the flow of a liquid crystal can be suppressed. As a result, it is possible to obtain a liquid crystal display element with no alignment disorder and high contrast.

  On the other hand, when the flow direction of the dropped liquid crystal and the alignment direction of the liquid crystal molecules by the alignment treatment do not match, alignment disorder occurs, and as a result, there is a possibility that contrast and display unevenness may occur.

In this embodiment, by using the above-described TFT substrate, the occurrence of alignment processing unevenness is suppressed, and the occurrence of alignment disorder is suppressed by dropping liquid crystal perpendicular to the longitudinal direction of the source line. Can do. Therefore, it is possible to obtain a liquid crystal display element with excellent display quality and high contrast.
Further, since the above-described TFT substrate is used, the storage capacity can be reduced, the charging time can be shortened, and a liquid crystal display element suitable for driving by a field sequential method can be obtained.

  In the above example, the case where the rubbing process is performed as the alignment process has been described, but the case where the optical alignment process is performed is also described.

First, a case where an optical alignment treatment is performed and an alignment film using a photodimerization type material is used and anisotropy is imparted to the film using a photodimerization reaction will be described. In this case, the alignment film forming layer 19 is first formed on the base material on which the gate lines 3, the source lines 7, the pixel electrodes 8, the TFTs 10 and the like are formed, as in the case of performing the rubbing process. The alignment film forming layer 19 is irradiated with light parallel to the longitudinal direction 51 of the source line 7 to perform a photo-alignment process (FIG. 10A, alignment film forming step). In this case, the longitudinal direction 51 of the source line 7 and the alignment treatment direction (light irradiation direction) 52a are parallel to each other.
Next, on the alignment film 9 formed in the alignment film forming step, the liquid crystal 30b in an isotropic phase is dropped in a continuous manner perpendicular to the longitudinal direction 51 of the source line 7 (FIG. 10). (b) Liquid crystal dropping step). That is, the dropping direction 54 of the liquid crystal 30 b is set perpendicular to the longitudinal direction 51 of the source line 7.
Next, after the liquid crystal is dropped, a sealing material 41 is formed in a frame shape on the TFT substrate 1 so as to surround the liquid crystal sealing region (FIG. 11). Subsequently, although not shown, the TFT substrate and the counter substrate are superposed under reduced pressure, the sealing material is heated and cured, and the TFT substrate and the counter substrate are bonded together (substrate bonding step).
Thereafter, the liquid crystal filled between the TFT substrate and the counter substrate is aligned by gradually cooling to room temperature (liquid crystal alignment step).

  When photo-alignment treatment is performed and an alignment film using a photo-dimerization type material is used and anisotropy is imparted to the film using a photo-dimerization reaction, the liquid crystal molecules Since they are aligned in parallel, as illustrated in FIG. 10B, the alignment direction 53a of the liquid crystal molecules by the alignment process (photo-alignment process) is parallel to the alignment process direction (light irradiation direction) 52a. In this case, when the liquid crystal 30b flows on the alignment film 9, it tends to flow perpendicularly to the dropping direction 54 of the liquid crystal 30b. That is, the flow direction 55 of the liquid crystal 30b is parallel to the alignment direction 53a of the liquid crystal molecules by the alignment process (photo-alignment process). Thereby, generation | occurrence | production of the alignment disorder resulting from the flow of a liquid crystal can be suppressed. As a result, it is possible to obtain a liquid crystal display element with no alignment disorder and high contrast.

Next, a case where photo-alignment treatment is performed and an anisotropy film using a photoisomerization type material is used and anisotropy is imparted to the film using a photoisomerization reaction will be described. In this case, first, an alignment film forming layer 19 is formed on a substrate on which the gate line 3, the source line 7, the pixel electrode 8, the TFT 10, and the like are formed, and the source line 7 is formed on the alignment film forming layer 19. A light alignment process is performed by irradiating light parallel to the longitudinal direction 51 (FIG. 12A, alignment film forming step). In this case, the longitudinal direction 51 of the source line 7 and the alignment treatment direction (light irradiation direction) 52b are parallel to each other.
Next, on the alignment film 9 formed in the alignment film forming step, liquid crystal 30b in an isotropic phase is dropped in a continuous manner in parallel to the longitudinal direction 51 of the source line 7 (see FIG. 12 (b), liquid crystal dropping step). That is, the dropping direction 54 of the liquid crystal 30 b is set parallel to the longitudinal direction 51 of the source line 7.

Note that dropping liquid crystal parallel to the longitudinal direction of the source line means that the angle formed by the longitudinal direction of the source line and the dropping direction of the liquid crystal is 0 ° ± 2 °.
Further, the liquid crystal dropping direction refers to a direction of scanning while dropping the liquid crystal.

Next, after the liquid crystal is dropped, a sealing material 41 is formed in a frame shape on the TFT substrate 1 so as to surround the liquid crystal sealing region (FIG. 11). Next, although not shown, the TFT substrate and the counter substrate are superposed under reduced pressure, the sealing material is heated and cured, and the TFT substrate and the counter substrate are bonded together (substrate bonding step).
Thereafter, the liquid crystal filled between the TFT substrate and the counter substrate is aligned by gradually cooling to room temperature (liquid crystal alignment step).

  When photo-alignment treatment is performed and an alignment film using a photoisomerization type material is used and anisotropy is imparted to the film using a photoisomerization reaction, the liquid crystal molecules are aligned in the light irradiation direction. As shown in FIG. 12B, the alignment direction 53b of the liquid crystal molecules by the alignment process (photo-alignment process) is perpendicular to the alignment process direction (light irradiation direction) 52b. Become. In this case, when the liquid crystal 30b flows on the alignment film 9, it tends to flow perpendicularly to the dropping direction 54 of the liquid crystal 30b. That is, the flow direction 55 of the liquid crystal 30b is parallel to the alignment direction 53b of the liquid crystal molecules by the alignment process (photo-alignment process). Thereby, generation | occurrence | production of the alignment disorder resulting from the flow of a liquid crystal can be suppressed. As a result, it is possible to obtain a liquid crystal display element with no alignment disorder and high contrast.

  Hereinafter, each process in the manufacturing method of the liquid crystal display element of this embodiment is demonstrated.

(1) Liquid crystal dropping step The liquid crystal dropping step in this embodiment is a step of dropping liquid crystal linearly on the alignment film of the TFT substrate described above in a direction perpendicular or parallel to the longitudinal direction of the source line.

  Since the TFT substrate has been described in detail in the section “A. TFT substrate”, description thereof is omitted here. Since the liquid crystal is described in detail in the section “B. Liquid crystal display element”, the description thereof is omitted here.

  The liquid crystal dropping direction may be perpendicular or parallel to the longitudinal direction of the source line. In particular, when the rubbing process is performed when forming the alignment film on the TFT substrate, the liquid crystal dropping direction is perpendicular to the longitudinal direction of the source line and also perpendicular to the rubbing process direction. It is preferable. In addition, when the alignment film of the TFT substrate is formed, when the photo-alignment process is performed using a photodimerization reaction, the liquid crystal dropping direction is perpendicular to the longitudinal direction of the source line, and the light It is preferable that it is also perpendicular to the irradiation direction. On the other hand, when forming the alignment film of the TFT substrate, when performing a photo-alignment process using a photoisomerization reaction, the liquid crystal dropping direction is parallel to the longitudinal direction of the source line, and It is preferably parallel to the light irradiation direction.

  The method for dropping liquid crystal is not particularly limited as long as a predetermined amount of liquid crystal can be dropped linearly. Generally, when dropping liquid crystal by one drop fill (OFD) method or the like. Can be used. Specific examples include an inkjet method in which liquid crystal is dropped using an inkjet head, and a dispenser method in which liquid crystal is dropped using a dispenser. Also, a coating method such as a bar coating method or a slot die coating method, a flexographic printing method, a gravure printing method, an offset printing method, a printing method such as a screen printing method, or the like can be used.

Among these, it is preferable to use an inkjet method. This is because by using the inkjet method, the amount of liquid crystal applied can be controlled in units of several tens of picoliters, and a small amount can be applied, so that the liquid crystal can be dropped in a continuous manner. By dropping the liquid crystal in a continuous manner, the liquid crystal can be prevented from flowing in the dropping direction of the liquid crystal, and can be promoted to flow in the alignment direction of the liquid crystal molecules by the alignment treatment.
The ink jet method can be the same as that generally used when liquid crystal is dropped by the ODF method or the like.

  Further, when the liquid crystal is dropped, it is preferable to drop the liquid crystal 30b in a continuous manner as illustrated in FIGS. 10B and 12B. As described above, by dropping the liquid crystal in a continuous manner, the liquid crystal can be prevented from flowing in the liquid crystal dropping direction, and can be promoted to flow in the alignment direction of the liquid crystal molecules by the alignment treatment. is there. Furthermore, although the reason is not clear, in the case where liquid crystal is dropped in the form of continuous dots compared to the case where liquid crystal is dropped in the form of discontinuous dots, alignment disorder is less likely to occur at the interface where the liquid crystal is in contact. .

  Furthermore, the position where the liquid crystal is dropped is not particularly limited as long as the liquid crystal is dropped in a predetermined amount that can be sealed.

(2) Substrate bonding step The substrate bonding step in this embodiment includes a TFT substrate on which the liquid crystal is dropped, and a counter substrate in which a second electrode and a second alignment film are sequentially laminated on a second base material. It is a process of bonding.

  The counter substrate has been described in the above section “B. Liquid crystal display element”, and a description thereof will be omitted here.

  The method for bonding the TFT substrate onto which the liquid crystal is dropped and the counter substrate is not particularly limited as long as the two substrates can be bonded together under a predetermined reduced pressure condition. Generally, a liquid crystal display element is used. In manufacturing, a method of bonding substrates can be used. Specifically, a method of forming a sealing material on at least one of the TFT substrate and the counter substrate and bonding the TFT substrate and the counter substrate through the sealing material can be used.

  Usually, the TFT substrate and the counter substrate are bonded together in a reduced pressure atmosphere. At this time, the degree of pressure reduction is such that bubbles are not enclosed between the two substrates after the TFT substrate and the counter substrate are bonded together. If it is, it will not specifically limit.

(3) Liquid crystal alignment step The liquid crystal alignment step in the present embodiment is a step of aligning the liquid crystal filled between the TFT substrate and the counter substrate.

  The method for aligning the liquid crystals is not particularly limited as long as the liquid crystals can be brought into a desired liquid crystal phase. As such a method, there is usually a method in which the liquid crystal is heated to a temperature at which the liquid crystal exhibits a nematic phase or an isotropic phase, and the encapsulated ferroelectric liquid crystal is cooled to obtain a desired liquid crystal phase state. Used.

When using a ferroelectric liquid crystal as the liquid crystal, the strength for ferroelectric liquid crystal are those fulfilling the switching function of the liquid crystal display device in the state of chiral smectic C (SmC ^*) phase, the present process is a ferroelectric liquid crystal SmC ^* phase It becomes the process of making it into this state.
In this case, the method of aligning the ferroelectric liquid crystal is not particularly limited as long as it is a method capable of bringing the ferroelectric liquid crystal into the SmC ^* phase state. Usually, the ferroelectric liquid crystal is replaced with the ferroelectric liquid crystal. Is heated to a temperature exhibiting a nematic phase or an isotropic phase, and the encapsulated ferroelectric liquid crystal is cooled to obtain a SmC ^* phase state.

(4) Other steps In addition to the liquid crystal dropping step and the substrate bonding step, the liquid crystal display element manufacturing method of the present embodiment includes a TFT substrate preparation step for preparing a TFT substrate and a counter substrate for preparing a counter substrate. You may have a preparation process.
The method for forming each member constituting the TFT substrate is described in detail in the section “A. TFT substrate”, and the method for forming each member constituting the counter substrate is described in “B. Liquid crystal display”. Since it was described in the section of “Element”, the description is omitted here.

2. Second Embodiment A second embodiment of the method for producing a liquid crystal display element according to the present invention includes the above-described TFT substrate and a counter substrate in which a second electrode and a second alignment film are sequentially laminated on a second base material. A substrate bonding step for combining, a liquid crystal injection step for injecting liquid crystal in parallel or perpendicular to the longitudinal direction of the source line between the TFT substrate and the counter substrate, and between the TFT substrate and the counter substrate And a liquid crystal aligning step for aligning the filled liquid crystal.

The manufacturing method of the liquid crystal display element of this embodiment is demonstrated referring drawings. FIG. 13 is a process diagram showing an example of a method for manufacturing a liquid crystal display element of this embodiment. In FIG. 13B, the counter substrate is omitted for simplification.
In the method for manufacturing a liquid crystal display element of this embodiment, first, an alignment film forming layer 19 is formed on a substrate on which the gate line 3, the source line 7, the pixel electrode 8, the TFT 10 and the like are formed. The film forming layer 19 is rubbed in parallel with the longitudinal direction 51 of the source line 7 (FIG. 13A, alignment film forming step). In this case, the longitudinal direction 51 of the source line 7 and the alignment treatment direction (rubbing treatment direction) 52a are parallel to each other.

  Next, although not shown, a sealing material is formed on the TFT substrate on which the alignment film has been formed in the alignment film forming step so as to surround the liquid crystal sealing region except for the portion serving as the injection port. Next, the TFT substrate and the counter substrate in which the second electrode and the second alignment film are laminated in this order on the second base material are arranged so that the alignment film and the second alignment film face each other. Bonding the substrates (substrate bonding step).

  Next, liquid crystal 30b in an isotropic phase is injected between the TFT substrate and the counter substrate in parallel to the longitudinal direction 51 of the source line 7 from the injection port (FIG. 13B, liquid crystal injection step). ). That is, the injection direction 56 of the liquid crystal 30 b is set parallel to the longitudinal direction 51 of the source line 7.

Note that “liquid crystal is injected parallel to the longitudinal direction of the source line” means that the angle formed by the longitudinal direction of the source line and the liquid crystal injection direction is 0 ° ± 2 °.
The liquid crystal injection direction refers to a direction in which liquid crystal is injected. Specifically, in FIG. 13B, there is an injection port below the drawing, and liquid crystal is injected from the bottom to the top of the drawing.

Next, although not shown, the inlet is sealed with an adhesive.
Thereafter, the liquid crystal sealed between the TFT substrate and the counter substrate is aligned by gradually cooling to room temperature (liquid crystal alignment step).

  When the rubbing process is performed, the liquid crystal molecules are aligned along the rubbing process direction. Therefore, as illustrated in FIG. 13B, the alignment direction 53a of the liquid crystal molecules by the alignment process (rubbing process) is the alignment process direction ( (Rubbing direction) 52a. In this case, since the liquid crystal 30b is injected in parallel to the longitudinal direction 51 of the source line 7 and the rubbing process is performed in parallel to the longitudinal direction 51 of the source line 7, the injection direction 56 of the liquid crystal 30b, that is, the liquid crystal flow The direction becomes parallel to the alignment direction 53a of the liquid crystal molecules by the alignment process (rubbing process). Thereby, generation | occurrence | production of the alignment disorder resulting from the flow of a liquid crystal can be suppressed. As a result, it is possible to obtain a liquid crystal display element with no alignment disorder and high contrast.

  On the other hand, when the liquid crystal injection direction, that is, the liquid crystal flow direction does not coincide with the alignment direction of the liquid crystal molecules by the alignment treatment, the alignment is disturbed, and as a result, there is a possibility that the contrast is lowered and the display is uneven.

In this embodiment, by using the above-mentioned TFT substrate, the occurrence of alignment processing unevenness is suppressed, and the occurrence of alignment disorder is suppressed by injecting liquid crystal in parallel to the longitudinal direction of the source line. Can do. Therefore, it is possible to obtain a liquid crystal display element with excellent display quality and high contrast.
Further, since the above-described TFT substrate is used, the storage capacity can be reduced, the charging time can be shortened, and a liquid crystal display element suitable for driving by a field sequential method can be obtained.

  In the above example, the case where the rubbing process is performed as the alignment process has been described, but the case where the optical alignment process is performed is also described.

First, a case where an optical alignment treatment is performed and an alignment film using a photodimerization type material is used and anisotropy is imparted to the film using a photodimerization reaction will be described. In this case, the alignment film forming layer 19 is first formed on the base material on which the gate lines 3, the source lines 7, the pixel electrodes 8, the TFTs 10 and the like are formed, as in the case of performing the rubbing process. The alignment film forming layer 19 is irradiated with light parallel to the longitudinal direction 51 of the source line 7 to perform a photo-alignment process (FIG. 13A, alignment film forming step). In this case, the longitudinal direction 51 of the source line 7 and the alignment treatment direction (light irradiation direction) 52a are parallel to each other.
Next, although not shown, a sealing material is formed on the TFT substrate on which the alignment film is formed in the alignment film forming step so as to surround the liquid crystal sealing region except for a portion serving as an injection port. The counter substrate is disposed so that the alignment film and the second alignment film face each other, and the TFT substrate and the counter substrate are bonded together (substrate bonding step).
Next, liquid crystal 30b in an isotropic phase is injected between the TFT substrate and the counter substrate in parallel to the longitudinal direction 51 of the source line 7 from the injection port (FIG. 13B, liquid crystal injection step). ). That is, the injection direction 56 of the liquid crystal 30 b is set parallel to the longitudinal direction 51 of the source line 7.
Next, although not shown, the inlet is sealed with an adhesive.
Thereafter, the liquid crystal sealed between the TFT substrate and the counter substrate is aligned by gradually cooling to room temperature (liquid crystal alignment step).

  When photo-alignment treatment is performed and an alignment film using a photo-dimerization type material is used and anisotropy is imparted to the film using a photo-dimerization reaction, the liquid crystal molecules Since they are aligned in parallel, as illustrated in FIG. 13B, the alignment direction 53a of the liquid crystal molecules by the alignment process (photo-alignment process) is parallel to the alignment process direction (light irradiation direction) 52a. In this case, since the liquid crystal 30b is injected in parallel to the longitudinal direction 51 of the source line 7 and light is irradiated in parallel to the longitudinal direction 51 of the source line 7, the injection direction 56 of the liquid crystal 30b, that is, the flow of the liquid crystal The direction becomes parallel to the alignment direction 53a of the liquid crystal molecules by the alignment process (photo-alignment process). Thereby, generation | occurrence | production of the alignment disorder resulting from the flow of a liquid crystal can be suppressed. As a result, it is possible to obtain a liquid crystal display element with no alignment disorder and high contrast.

Next, a case where photo-alignment treatment is performed and an anisotropy film using a photoisomerization type material is used and anisotropy is imparted to the film using a photoisomerization reaction will be described. In this case, first, an alignment film forming layer 19 is formed on a substrate on which the gate line 3, the source line 7, the pixel electrode 8, the TFT 10, and the like are formed, and the source line 7 is formed on the alignment film forming layer 19. A light alignment process is performed by irradiating light parallel to the longitudinal direction 51 (FIG. 14A, alignment film forming step). In this case, the longitudinal direction 51 of the source line 7 and the alignment treatment direction (light irradiation direction) 52b are parallel to each other.
Next, although not shown, a sealing material is formed on the TFT substrate on which the alignment film is formed in the alignment film forming step so as to surround the liquid crystal sealing region except for a portion serving as an injection port. The counter substrate is disposed so that the alignment film and the second alignment film face each other, and the TFT substrate and the counter substrate are bonded together (substrate bonding step).
Next, liquid crystal 30b in an isotropic phase is injected between the TFT substrate and the counter substrate from the injection port perpendicular to the longitudinal direction 51 of the source line 7 (FIG. 14B, liquid crystal injection step). ). That is, the injection direction 56 of the liquid crystal 30 b is set perpendicular to the longitudinal direction 51 of the source line 7.

Note that “liquid crystal is injected perpendicularly to the longitudinal direction of the source line” means that the angle formed by the longitudinal direction of the source line and the liquid crystal injection direction is 90 ° ± 1 °.
The liquid crystal injection direction refers to a direction in which liquid crystal is injected. Specifically, in FIG. 14B, an injection port exists on the left side of the drawing, and liquid crystal is injected from the left side to the right side of the drawing.

Next, although not shown, the inlet is sealed with an adhesive.
Thereafter, the liquid crystal sealed between the TFT substrate and the counter substrate is aligned by gradually cooling to room temperature (liquid crystal alignment step).

  When photo-alignment treatment is performed and an alignment film using a photoisomerization type material is used and anisotropy is imparted to the film using a photoisomerization reaction, the liquid crystal molecules are aligned in the light irradiation direction. As shown in FIG. 14B, the alignment direction 53b of the liquid crystal molecules by the alignment treatment (photo-alignment treatment) is perpendicular to the alignment treatment direction (light irradiation direction) 52b. Become. In this case, since the liquid crystal 30b is injected perpendicularly to the longitudinal direction 51 of the source line 7 and light is irradiated in parallel to the longitudinal direction 51 of the source line 7, the injection direction 56 of the liquid crystal 30b, that is, the liquid crystal flow The direction becomes parallel to the alignment direction 53b of the liquid crystal molecules by the alignment process (photo-alignment process). Thereby, generation | occurrence | production of the alignment disorder resulting from the flow of a liquid crystal can be suppressed. As a result, it is possible to obtain a liquid crystal display element with no alignment disorder and high contrast.

  Since the liquid crystal alignment process and other processes are the same as those in the first embodiment, description thereof is omitted here. Hereinafter, other steps in the method of manufacturing the liquid crystal display element of the present embodiment will be described.

(1) Substrate bonding step The substrate bonding step in the present embodiment is a step of bonding the above-described TFT substrate and a counter substrate in which a second electrode and a second alignment film are sequentially laminated on the second base material. is there.

The TFT substrate is described in detail in the section “A. TFT substrate”, and the counter substrate is described in the section “B. Liquid crystal display element”.
Further, the method for attaching the TFT substrate and the counter substrate is the same as that described in the first embodiment, and the description thereof is omitted here.

(2) Liquid crystal injection step The liquid crystal injection step in this embodiment is a step of injecting liquid crystal between the TFT substrate and the counter substrate in parallel or perpendicular to the longitudinal direction of the source line.

  Since the liquid crystal is described in detail in the section “B. Liquid crystal display element”, description thereof is omitted here.

  The liquid crystal injection direction may be parallel or perpendicular to the longitudinal direction of the source line. In particular, when the rubbing process is performed when forming the alignment film of the TFT substrate, the liquid crystal injection direction is parallel to the longitudinal direction of the source line and also to the rubbing process direction. It is preferable. When the alignment film of the TFT substrate is formed and the photo-alignment process is performed using the photodimerization reaction, the liquid crystal injection direction is parallel to the longitudinal direction of the source line, and the light It is preferable to be parallel to the irradiation direction. On the other hand, when forming the alignment film of the TFT substrate, when performing a photo-alignment process using a photoisomerization reaction, the liquid crystal injection direction is perpendicular to the longitudinal direction of the source line, and It is preferably perpendicular to the direction of light irradiation.

  The method for injecting the liquid crystal is not particularly limited as long as it is a method capable of sealing a predetermined amount of liquid crystal between the TFT substrate and the counter substrate, and a method capable of injecting the liquid crystal in a certain direction.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

EXAMPLES Hereinafter, an Example is shown and this invention is demonstrated more concretely.
[Example]
1. Fabrication of TFT substrate (Gate electrode and gate line formation process)
First, a metal mask having a gate electrode and a gate line-shaped opening was placed on the surface of a glass substrate having a size of 150 mm × 150 mm × 0.7 mm, and then a chromium film having a thickness of 100 nm was formed. Next, an aluminum film having a thickness of 200 nm was deposited to form a gate electrode and a gate line. The degree of vacuum at the time of vapor deposition was 1 × 10 ⁴ Pa, and the vapor deposition rate was about 1 kg / sec.

(Gate insulation layer formation process)
Next, a photoresist (acrylic negative resist) was spin-coated on the substrate as a gate insulating layer. The spin coating at this time was held at 800 rpm for 10 seconds. Thereafter, the substrate was dried at 80 ° C. for 3 minutes and then subjected to pattern exposure at 350 mJ / cm ² . Next, a development process was performed to remove portions other than the gate insulating layer located on the gate electrode and the gate line, and then the substrate was dried in an oven at 200 ° C. for 30 minutes.

(Semiconductor layer formation process)
After placing a metal mask having a semiconductor layer-shaped opening on the surface of the substrate on which the gate electrode and the gate line were formed, a semiconductor layer made of a silicon-based semiconductor having a thickness of 50 nm was deposited.

(Shading part forming process)
Next, BM photoresist (carbon negative resist) was spin-coated on the substrate as a light shielding part. The spin coating at this time was held at 800 rpm for 10 seconds. Thereafter, the substrate was dried at 80 ° C. for 3 minutes, and then subjected to pattern exposure at 100 mJ / cm ² . Next, a development step is performed to remove the resist other than the portion located on the semiconductor layer and the resist in the through hole portion for ensuring conduction to the source electrode and the pixel electrode, and then in an oven at 200 ° C. Dry for 30 minutes. At this time, the distance (channel length) of the through hole was 50 μm.

(Overcoat layer forming process)
Next, a photoresist (acrylic negative resist) was spin-coated on the substrate as an overcoat layer. The spin coating at this time was held at 800 rpm for 10 seconds. Thereafter, the substrate was dried at 80 ° C. for 3 minutes and then subjected to pattern exposure at 350 mJ / cm ² . Next, a development process was performed to remove the pattern of the resist located on the light-shielding part and the semiconductor layer, and then the film was dried in an oven at 200 ° C. for 30 minutes.

(Source electrode and source line formation process)
Next, a metal mask having a source electrode and a source line-shaped opening was placed on the substrate surface after the overcoat layer was formed, and then a 200 nm-thick chromium film was formed to form the source electrode and the source line. .

(Pixel electrode and transparent electrode formation process)
Next, after placing a metal mask having pixel electrode and transparent electrode-shaped openings on the substrate surface after forming the source electrode and the source line, an ITO film having a film thickness of 150 nm is formed, and the pixel electrode and the transparent electrode are formed. Formed.

2. Alignment film forming step An acrylic negative resist was spin-coated at 1500 rpm for 30 seconds on the cleaned TFT substrate, and then a columnar spacer having a height of 1.5 μm was formed by exposing and developing the columnar pattern.
Thereafter, a solution of SE510 (Nissan Chemical Industry Co., Ltd.) was spin-coated on the TFT substrate at a rotation speed of 1000 rpm for 30 seconds. After drying in an oven at 200 ° C. for 60 minutes, rubbing treatment was performed in the same direction as the direction of the source line.

3. Production of counter substrate A glass substrate coated with ITO was spin-coated with a 2 wt% ROP-103 solution (ROLIC TECHNOLOGY) dissolved in cyclopentanone at a rotation speed of 1000 rpm for 30 seconds. After drying in an oven at 180 ° C. for 10 minutes, polarized ultraviolet rays were exposed at 25 ° C. for 100 mJ / cm ² . Thereafter, a solution of 2% by weight of ROF-5101 (ROLIC TECHNOLOGY) dissolved in cyclopentanone was spin-coated at a rotation speed of 1000 rpm for 30 seconds, dried at 55 ° C. for 3 minutes, and then applied with non-polarized ultraviolet rays. The film was exposed to 1000 mJ / cm ² at 55 ° C.
Then, the board | substrate was assembled in the state parallel to the orientation process direction, the thermocompression bonding was performed, and the panel was produced. The liquid crystal is “R2301” (manufactured by AZ Electronic Materials), the liquid crystal is attached to the top of the injection port, and injection is performed at a temperature 10 ° C. to 20 ° C. higher than the nematic phase-isotropic phase transition temperature using an oven. Slowly returned to room temperature.
At that time, no light was observed near the source line, and the contrast was 400: 1.

[Comparative example]
Except not forming an overcoat layer, the panel was produced similarly to the Example and evaluated.
At that time, no light leakage was observed near the source line, but light was observed linearly near the gate line, and the contrast was 180: 1.

DESCRIPTION OF SYMBOLS 1 ... TFT substrate 2 ... Base material 3 ... Gate line 4 ... Gate insulating layer 6 ... Overcoat layer 7 ... Source line 8 ... Pixel electrode 9 ... Alignment film 10 ... TFT
DESCRIPTION OF SYMBOLS 13 ... Gate electrode 14 ... TFT gate insulating layer 15 ... Semiconductor layer 16 ... TFT overcoat layer 17 ... Source electrode 18 ... Transparent electrode 21a, 21b ... Light-shielding part 30b ... Liquid crystal 51 ... Longitudinal direction 52a, 52b of source line Alignment treatment direction 53a, 53b ... Alignment direction of liquid crystal molecules by alignment treatment 54 ... Dropping direction of liquid crystal 56 ... Injection direction of liquid crystal h1 ... Contact hole for source electrode h2 ... Contact hole for transparent electrode

Claims (11)

A substrate;
A gate line formed on the substrate;
A gate insulating layer formed to cover the gate line;
An overcoat layer formed on the gate insulating layer;
A source line formed on the overcoat layer so as to intersect the gate line;
A pixel electrode formed on the overcoat layer;
A gate electrode formed on the substrate and connected to the gate line, a gate insulating layer for a thin film transistor formed continuously with the gate insulating layer so as to cover the gate electrode, and on the gate insulating layer for the thin film transistor A thin film transistor overcoat layer formed continuously with the overcoat layer on the semiconductor layer formed, the thin film transistor gate insulating layer and the semiconductor layer, formed on the thin film transistor overcoat layer, and formed on the source line A source electrode connected to the semiconductor layer via a source electrode contact hole, and a thin film transistor overcoat layer formed on the thin film transistor overcoat layer, connected to the pixel electrode, and a transparent electrode contact hole formed in the semiconductor layer A thin film transistor having a transparent electrode connected via A thin film transistor substrate comprising:   2. The thin film transistor substrate according to claim 1, wherein the thin film transistor substrate is used for a liquid crystal display element using a ferroelectric liquid crystal.   3. The thin film transistor substrate according to claim 1, wherein the thin film transistor substrate is used for a liquid crystal display element driven by a field sequential method.   The thin film transistor substrate according to claim 1, wherein a light shielding portion is formed on the semiconductor layer.   5. The thin film transistor substrate according to claim 1, wherein an alignment film is formed on the source line, the pixel electrode, and the thin film transistor.   The thin film transistor substrate according to claim 5, wherein the alignment film is a rubbing alignment film, and a rubbing processing direction is parallel to a longitudinal direction of the source line.   6. The thin film transistor substrate according to claim 5, wherein the alignment film is a photo-alignment film that has been subjected to a photo-alignment process, and a light irradiation direction is parallel to a longitudinal direction of the source line.   A thin film transistor substrate according to any one of claims 5 to 7, and a second electrode and a second alignment film are sequentially stacked on a second base material, and the alignment film and the second alignment layer are stacked on the thin film transistor substrate. A liquid crystal display element, comprising: a counter substrate disposed so that the alignment films face each other; and a liquid crystal layer formed between the alignment film and the second alignment film.   The liquid crystal display element according to claim 8, wherein the liquid crystal layer includes a ferroelectric liquid crystal, and the constituent materials of the alignment film and the second alignment film have different compositions. A liquid crystal dropping step in which liquid crystal is dropped linearly on the alignment film of the thin film transistor substrate according to any one of claims 5 to 7 perpendicularly or parallel to the longitudinal direction of the source line;
A substrate laminating step of laminating the thin film transistor substrate onto which the liquid crystal is dropped, and a counter substrate in which a second electrode and a second alignment film are sequentially laminated on the second base material;
And a liquid crystal alignment step of aligning the liquid crystal filled between the thin film transistor substrate and the counter substrate. A substrate laminating step of laminating the thin film transistor substrate according to any one of claims 5 to 7 and a counter substrate in which a second electrode and a second alignment film are sequentially laminated on a second base material;
A liquid crystal injection step of injecting liquid crystal between the thin film transistor substrate and the counter substrate in parallel or perpendicular to the longitudinal direction of the source line;
And a liquid crystal alignment step of aligning the liquid crystal filled between the thin film transistor substrate and the counter substrate.

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