JP2008275699A - Liquid crystal display element and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a liquid crystal display element which suppresses a display defect caused by a rubbing defect, while suppressing reduction in the optical performance. <P>SOLUTION: A spacer 30 is provided to the first transparent substrate 12 out of a pair of first and second transparent substrates, a liquid crystal substance having negative dielectric anisotropy is included in a liquid crystal layer 50 having dielectric constant anisotropy, a first alignment layer 16 is a vertical alignment layer, and alignment processing for providing a pretilt angle to the liquid crystal substance is applied to the first alignment layer 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element in which a display defect due to a rubbing defect is suppressed, and a liquid crystal display device.

  Conventionally, an alignment process by rubbing (rubbing alignment process) has been widely used as an alignment process in liquid crystal display elements. The rubbing alignment treatment typically means a treatment for rubbing the alignment film applied to the substrate with a cloth (rubbing cloth) to impart alignment to the alignment film.

  On the other hand, the substrate on which the alignment film is applied is often not smooth. That is, a protrusion such as a post spacer (PS) or a black matrix (BM) is formed on the substrate.

  When the substrate provided with the protrusions is subjected to a rubbing alignment process, the protrusions obstruct the rubbing alignment process, and a rubbing failure region is generated in the vicinity of the protrusions. In this rubbing failure region, the alignment of the liquid crystal molecules is disturbed (alignment failure). As a result, for example, streak-like display unevenness occurs, resulting in a problem that display quality is deteriorated.

  In order to solve this problem, various techniques have been proposed.

(Patent Document 1)
For example, Patent Document 1 describes a technique in which a columnar spacer is shaped so that the resistance received by the hair of a rubbing cloth is reduced.

  Specifically, it is described that the shape of the columnar spacer (post spacer) is such that the portion of the rubbing cloth hitting the bristle has a vertex and has a taper.

(Patent Document 2)
Patent Document 2 describes a technique for setting a rubbing direction in a direction in which an alignment disorder region generated behind a columnar spacer does not substantially overlap with a pixel electrode.

  Specifically, a technique is described in which a columnar spacer is provided in the vicinity of a switching element, and a rubbing alignment process is performed in a direction from the columnar spacer toward the switching element.

(Patent Document 3)
Japanese Patent Application Laid-Open No. 2004-228688 describes a technique for making display unevenness difficult to see by appropriately setting a relative position between a columnar spacer and a pixel region, a rubbing direction, and the like.

Specifically, a technique for preventing alignment failure from occurring in a green pixel region having higher visibility than red and blue is described.
JP 9-73088 A (published on March 18, 1997) Japanese Patent Laid-Open No. 11-174467 (published July 2, 1999) JP 2002-214621 A (released July 31, 2002)

  However, the conventional configuration has a problem that the optical performance of the liquid crystal display element is deteriorated.

(Patent Document 1)
Specifically, in the technique described in Patent Document 1, for example, since the columnar spacer has a shape having a vertex, the tip portion thereof is particularly easily deformed by external stress, and as a result, the liquid crystal layer The thickness of the case may fluctuate. When the thickness of the liquid crystal layer fluctuates, the retardation (a value obtained by multiplying the birefringence difference of liquid crystal molecules and the optical path length (approximate to the thickness of the liquid crystal layer)) fluctuates, resulting in a decrease in optical performance. was there.

(Patent Document 2)
In the technique described in Patent Document 2, it is preferable to provide a columnar spacer on a gate wiring or the like, so that design parameters such as an aperture ratio are likely to be constrained, resulting in a decrease in optical performance. there were.

(Patent Document 3)
In the technique described in Patent Document 3, it is necessary to provide columnar spacers while avoiding green pixels among the three primary colors. For this reason, the arrangement of the pixels is likely to be restricted, and as a result, the optical property may be lowered.

  Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a liquid crystal display element in which a display defect due to a rubbing defect is suppressed while suppressing a decrease in optical performance, and a liquid crystal display. To implement the device.

  In order to solve the above problems, a liquid crystal display element of the present invention includes a pair of substrates having alignment films formed on surfaces facing each other, and a substance having dielectric anisotropy sandwiched between the pair of substrates. A liquid crystal display element provided with a layer, wherein at least one of the pair of substrates is provided with a protrusion, and the material layer having dielectric anisotropy has a negative A liquid crystalline material having dielectric anisotropy is included, the alignment film is a vertical alignment film, and the alignment film is subjected to an alignment treatment for giving a pretilt angle to the liquid crystalline material. It is characterized by being.

  According to the above configuration, it is possible to provide a liquid crystal display element in which display defects due to rubbing defects are suppressed while suppressing deterioration in optical performance even when projections are provided on the substrate. There is an effect. Hereinafter, it demonstrates in order.

(Poor rubbing)
First, the rubbing failure caused by the projection and the alignment failure caused thereby will be described with reference to FIG. 4 by taking a columnar spacer as an example of the projection. FIG. 4 shows a conventional technique and is a schematic diagram schematically showing the alignment state of the liquid crystal molecules 52.

  In the liquid crystal display element 1 shown in FIG. 4, a columnar spacer 30 is provided on the first transparent substrate 12. A first alignment film 16 is provided on the surfaces of the first transparent substrate 12 and the columnar spacers 30.

  Conventionally, a horizontal alignment film has been used as the first alignment film 16. Here, the horizontal alignment film means an alignment film having a property of aligning liquid crystal molecules so that the major axis direction thereof is parallel to the alignment film surface in a state where no voltage is applied to the liquid crystal molecules. To do. Therefore, in the liquid crystal display element 1 shown in FIG. 4, the liquid crystal molecules 52 are aligned in a direction parallel to the first transparent substrate 12 in a state where no voltage is applied (horizontal alignment).

  Corresponding to the fact that the first alignment film 16 is a horizontal alignment film, positive dielectric anisotropic liquid crystal molecules have been used as the conventional liquid crystal molecules 52.

  Here, the positive dielectric anisotropic liquid crystal molecule means a liquid crystal molecule having a property that, when a voltage is applied to the liquid crystal molecule, the major axis direction of the liquid crystal molecule is aligned in parallel to the electric field. To do.

  As described above, in the conventional liquid crystal display element 1 configured by the combination of the horizontal alignment film and the positive dielectric anisotropic liquid crystal molecules, the liquid crystal molecules 52 exhibit the following movements when a voltage is applied.

  That is, as shown in FIG. 4, when a voltage is applied, the liquid crystal molecules 52 tend to rise from a direction parallel to the first transparent substrate 12 to a direction perpendicular to the first transparent substrate 12. . In other words, it tries to shift from horizontal alignment to vertical alignment. Here, the arrows in FIG. 4 indicate the movement of the liquid crystal molecules 52 when a voltage is applied to the horizontally aligned liquid crystal molecules 52.

  Then, when the liquid crystal molecules 52 rise to the vertical alignment by voltage application, two directions can be considered depending on which end portion in the major axis direction of the liquid crystal molecules 52 rises. That is, the direction indicated by the arrow A in FIG. 4 and the direction indicated by the arrow B can be considered.

  Usually, this rising direction is defined by the pretilt angle θ given to the liquid crystal molecules 52 by the rubbing alignment treatment. Here, the pretilt angle means an angle formed by the substrate and the major axis direction of the liquid crystal molecules. This will be described below.

  That is, the liquid crystal molecules 52 to which the pretilt angle θ is given are perpendicular to the ends tilted from the first transparent substrate by giving the pretilt angle θ among the ends in the major axis direction of the liquid crystal molecules 52. Try to transition to orientation. That is, it rises in the direction indicated by arrow A in FIG.

  Here, in the case where the first transparent substrate 12 is provided with a protrusion, the first alignment film 16 has a region where the rubbing alignment process has been normally performed (rubbing normal area GA) and the rubbing alignment process is normal. In this case, a region that is not performed (rubbing failure region BA) occurs.

  This is because, for example, when the rubbing alignment treatment is performed in the direction indicated by the white arrow R in FIG. 4, the first alignment film 16 (rubbing failure) in the region (hatched region in FIG. 4) that is shaded by the columnar spacer (projection) 30 The first alignment film 16) in the region BA is not sufficiently rubbed, and as a result, no alignment film tilt is imparted to the first alignment film 16. Here, the alignment film tilt means a tilt angle given to molecules on the alignment film surface by rubbing alignment treatment or the like, for example, a tilt angle of a linear side chain.

  That is, the area that has not been sufficiently rubbed becomes the rubbing failure area BA, and is distinguished from the other rubbed normal area GA that is a sufficiently rubbed area.

  Further, since the alignment film tilt is not given to the first alignment film 16 in the rubbing failure area BA, the pretilt angle is not given to the liquid crystal molecules 52 in the rubbing failure area BA.

  As a result, regarding the liquid crystal molecules 52 in the rubbing failure area BA, it is not determined which one of the ends in the major axis direction of the liquid crystal molecules 52 rises when a voltage is applied to the liquid crystal molecules 52.

  In summary, the conventional liquid crystal display element 1 includes a region where the rubbing alignment treatment is normally performed (rubbing normal region GA) and a region where the rubbing alignment processing is not normally performed (rubbing failure region BA). Existed. The liquid crystal molecules 52 in contact with the first alignment film 16 in the normal rubbing area GA are given a pretilt angle θ, whereas the liquid crystal molecules 52 in contact with the first alignment film 16 in the defective rubbing area BA are provided. Is not given a pretilt angle θ.

  As a result, the liquid crystal molecules 52 in the normal rubbing region GA rise in a desired direction when a voltage is applied. On the other hand, the liquid crystal molecules 52 in the rubbing failure region BA have different directions in which the liquid crystal molecules 52 rise when a voltage is applied. As a result, poor orientation occurs (rubbing and disclination). This is because, for example, the liquid crystal molecules 52 rising not only in the direction indicated by the arrow A but also in the direction indicated by the arrow B in FIG. 4 are generated.

  Then, due to this poor orientation, a transmittance difference is generated between the rubbing normal region GA, and this transmittance difference becomes display unevenness, resulting in a decrease in display quality.

(Suppression of rubbing failure)
Compared to the above conventional liquid crystal display element, the liquid crystal display element of the present invention has a disclination in such a region even when an insufficiently aligned region occurs, thereby improving the display quality. Less likely to be damaged. This will be described below.

  Since the liquid crystal substance in the present invention uses a vertical alignment film, it is vertically aligned when no voltage is applied.

  Here, the vertical alignment film means an alignment film having a property of aligning the liquid crystalline substance in a state closer to vertical than parallel to the alignment film surface.

  Since the liquid crystalline material has negative dielectric anisotropy, when a voltage is applied, the vertically aligned liquid crystalline material is substantially parallel to the substrate. Fall down. Here, the liquid crystalline substance having negative dielectric anisotropy is a liquid crystalline substance having a property that the major axis direction of the liquid crystalline substance is perpendicular to the electric field when a voltage is applied to the liquid crystalline substance. Means.

  As described above, since the pretilt angle is given to the liquid crystalline material in the region where the alignment treatment is sufficiently performed, the direction in which the liquid crystalline material falls is defined as one direction as described above. .

  On the other hand, in a region where the alignment treatment is insufficient, since the pretilt angle is not given to the liquid crystalline material, various directions can be considered as directions in which the liquid crystalline material is tilted by application of voltage.

  However, in the liquid crystal display element of the present invention, if the direction in which the liquid crystalline material falls is defined in one direction in a region where the alignment treatment is sufficiently performed, accordingly, the alignment treatment is performed in a region where the alignment treatment is insufficient. The direction in which the liquid crystal material falls is also defined as one direction.

  That is, in the liquid crystal display element of the present invention, when a voltage is applied, the liquid crystalline material changes from vertical alignment to horizontal alignment. Therefore, when the liquid crystalline material is tilted from the vertical direction to the horizontal direction, the adjacent liquid crystal properties are It exerts a great influence on the material in the same direction.

  As a result, at the boundary between a region with sufficient alignment treatment and a region with insufficient alignment treatment, the liquid crystalline material in the region with insufficient alignment treatment is affected by the liquid crystalline material in the region with sufficient alignment treatment. As a result, it falls in the same direction as the liquid crystalline material in a sufficiently aligned region, and as a result, disclination hardly occurs.

  That is, the liquid crystalline material in a region where alignment processing is sufficient and the liquid crystalline material where alignment processing is insufficient are tilted in one direction in a so-called manner, so that the inclination of the liquid crystalline material becomes uniform and display defects occur. Hard to occur.

  In the above configuration, there are no restrictions on design items (design factors) that directly affect the optical performance of the liquid crystal display element, such as the aperture ratio and the wiring width.

  As a result, in the above configuration, it is possible to provide a liquid crystal display element in which display defects caused by rubbing defects are suppressed while suppressing deterioration in optical performance even when protrusions are provided on the substrate. There is an effect that can be done.

  The liquid crystal display element of the present invention is characterized in that the pretilt angle is 45 ° or more and less than 90 °.

  In the liquid crystal display element of the present invention, the pretilt angle is preferably 88 ° or less.

  According to the above configuration, since the pretilt angle is large, the change in the angle of the liquid crystalline substance that occurs when a voltage is applied is large. Therefore, it is possible to provide a liquid crystal display element in which the influence on adjacent liquid crystal substances is increased, and display defects due to rubbing defects are further suppressed.

  In the liquid crystal display element of the present invention, the protrusion may be a spacer for controlling the distance between the pair of substrates.

  According to the above configuration, since the protrusion is a spacer, the distance between the substrates can be controlled to a desired length. Accordingly, display defects due to in-plane differences in the distance between the substrates (liquid crystal cell thickness) can be suppressed, so that a liquid crystal display element with higher display quality can be provided.

  In the liquid crystal display element of the present invention, the liquid crystalline substance may exhibit a nematic liquid crystal phase.

  In the liquid crystal display element of the present invention, a chiral agent is added to the material layer having dielectric anisotropy, and the liquid crystal material has a rotational viscosity of 100 mPa · S or more and 250 mPa · S or less. Preferably there is.

  According to the above configuration, since the liquid crystalline material has a predetermined chiral pitch length and a desired rotational viscosity, a practical response speed of the liquid crystalline material when a voltage is applied and suppression of alignment failure. It becomes easy to achieve both.

  The nematic liquid crystal phase means a liquid crystal phase in which the center of gravity of the molecule is random and fluid, but the direction of the symmetry axis of the molecule is aligned in a certain direction and is macroscopically anisotropic.

  In the liquid crystal display element of the present invention, it is preferable that the alignment film contains a polyimide compound, and the imidization ratio of the polyimide compound is 50% or more and 80% or less.

  According to the above configuration, since the imidization ratio is within a desired range, a desired alignment film tilt can be easily realized by the alignment treatment.

  Here, the imidization rate means a ratio of dehydration and cyclization by imidization among amide groups and carboxyl groups of polyamic acid which is a precursor of a polyimide compound.

  In the liquid crystal display element of the present invention, it is preferable that the height of the protrusion is 4.5 μm or less.

  In the liquid crystal display element of the present invention, it is preferable that the protrusion has a columnar shape and the column has a diameter of 25 μm or less.

  According to the above configuration, since the size of the protrusion is small, the area of the region where the alignment process is insufficient can be reduced. That is, when performing the alignment process, particularly the rubbing alignment process, the alignment process is less likely to be inhibited by the protrusions, and as a result, display defects due to the rubbing defects can be further suppressed.

  In the liquid crystal display element of the present invention, the thickness of the alignment film on the surface of the protrusion is preferably 50% or less of the thickness of the alignment film on the surface of the substrate.

  Generally, when the thickness of the alignment film is reduced, the alignment regulating power with respect to the liquid crystalline substance is reduced.

  Therefore, according to the above configuration, since the alignment film on the protrusion is thin, the alignment film on the protrusion surface has an effect of reducing the alignment uniformity of the liquid crystalline substance, for example, various The influence of aligning liquid crystal molecules in the direction can be reduced.

  Moreover, the liquid crystal display element of this invention can provide the area | region in which the alignment film is not formed in the side surface of the said protrusion.

  According to the above configuration, since there is a region where the alignment film is not applied to the side surface of the protrusion, the influence of reducing the alignment uniformity of the liquid crystalline substance from the alignment film on the surface of the protrusion is reduced. be able to.

  In the liquid crystal display element of the present invention, the alignment treatment is a rubbing alignment treatment, and the length of the bristle of the rubbing cloth used for the rubbing alignment treatment is 2.0 mm or more and 5.0 mm or less. preferable.

  According to the above configuration, the alignment treatment is a rubbing alignment treatment, and the length of the hair of the rubbing cloth used for the rubbing alignment treatment is long. For example, the back side of the protrusion (behind the protrusion) The rubbing cloth is easy to reach the part.

  Therefore, the area of the region where the alignment treatment is insufficient can be reduced, and the rubbing state of the alignment film in the region where the alignment treatment is insufficient can be brought close to the rubbing state of the alignment film in the region where the alignment treatment is sufficient. . As a result, display defects can be further suppressed.

  In the liquid crystal display element of the present invention, the alignment treatment is preferably a rubbing alignment treatment, and a rubbing cloth used for the rubbing alignment treatment is preferably immersed in hydrogen peroxide water.

  According to the above configuration, since the rubbing cloth is softened by being immersed in the hydrogen peroxide solution, for example, the rubbing cloth can easily reach the back side of the projection (the portion behind the projection).

  Therefore, the area of the region where the alignment treatment is insufficient can be reduced, and the rubbing state of the alignment film in the region where the alignment treatment is insufficient can be brought close to the rubbing state of the alignment film in the region where the alignment treatment is sufficient. . As a result, display defects can be further suppressed.

  In the liquid crystal display device of the present invention, it is preferable that the protrusion is formed of a material containing at least a part of a compound containing a halogen atom.

  In the liquid crystal display device of the present invention, the halogen atom is preferably a fluorine atom.

  In the liquid crystal display device of the present invention, it is preferable that the protrusion is formed of a material containing at least a part of a compound containing a siloxane bond.

  In the liquid crystal display device of the present invention, it is preferable that the protrusion is formed of a material containing at least a part of an olefin compound.

  In the liquid crystal display device of the present invention, the olefin compound is preferably polyethylene, polystyrene, or polyethylene and polystyrene.

  In the liquid crystal display element of the present invention, it is preferable that the protrusion is formed of silica beads, glass fibers, or a material in which silica beads and glass fibers are mixed.

  In the liquid crystal display element of the present invention, it is preferable that the protrusion is formed of a material containing at least a part of a bisazide compound.

  According to the above configuration, the protrusion is formed of a material that easily repels the alignment film. Therefore, it is difficult to apply the alignment film on the surface of the protrusion, and the alignment regulating force that the liquid crystalline substance receives from the alignment film on the protrusion can be suppressed. As a result, display defects can be further suppressed.

  That is, as a force that reduces the alignment uniformity of the liquid crystal molecules (liquid crystalline substance), the liquid crystal molecules in the vicinity of the protrusions are different from the liquid crystal molecules in other regions when a voltage is applied due to the effect of a step due to the protrusions. Has the power to fall in different directions.

  Specifically, when the alignment film is applied to the surface of the protrusion, which is a surface different from the substrate, an alignment regulating force in a direction different from that of the alignment film on the substrate acts from the alignment film. And the alignment control force which worked in the direction different from the alignment film on this board | substrate reduces the uniformity of the alignment of a liquid crystal molecule.

  In this regard, according to the above configuration, the protrusion such as the spacer is a compound containing a halogen atom such as a fluorine atom, a compound containing a siloxane bond, an olefin compound such as polyethylene or polystyrene, silica beads or glass fiber. Etc. are formed by a mixed material, a bisazide compound or the like.

  Therefore, the protrusion easily repels the alignment film, and thus the alignment film is hardly formed on the surface of the protrusion. As a result, it is possible to reduce the influence that the liquid crystal molecules receive from the alignment film on the surface of the protrusion, which lowers the alignment uniformity of the liquid crystal molecules.

  As described above, by strengthening the repelling of the protrusion surface, the application of the alignment film itself to the protrusion surface is suppressed, and the force that reduces the alignment uniformity of the liquid crystal molecules can be suppressed. As a result, display defects can be further suppressed.

  The liquid crystal display device of the present invention preferably includes the liquid crystal display element.

  According to the above configuration, it is possible to provide a liquid crystal display device in which a decrease in optical performance is small and display defects are suppressed.

  In the liquid crystal display element and the liquid crystal display device of the present invention, a protrusion is provided on at least one of the pair of substrates, and a negative dielectric is provided on the material layer having dielectric anisotropy. A liquid crystalline material having anisotropy is included, the alignment film is a vertical alignment film, and the alignment film is subjected to an alignment treatment for giving a pretilt angle to the liquid crystalline material.

  As a result, there is an effect that it is possible to realize a liquid crystal display element and a liquid crystal display device in which display defects due to rubbing defects are suppressed while suppressing deterioration in optical performance.

  An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view showing a schematic configuration of a liquid crystal display element 1 of the present embodiment. FIG. 2 is a schematic view schematically showing the alignment state of the liquid crystal molecules 52 in the liquid crystal display element 1 of the present embodiment. FIG. 3 is a block diagram showing the configuration of the liquid crystal display device 100 of this embodiment together with an equivalent circuit and the like.

(overall structure)
As shown in FIG. 1, the liquid crystal display element 1 of the present embodiment includes a pair of light-transmitting substrates (a first substrate 10 and a second substrate 20) arranged to face each other, and the pair of these It has a cell structure in which a liquid crystal layer (a material layer having dielectric anisotropy) 4 is sandwiched between substrates.

  Specifically, the first substrate 10 is a so-called color filter substrate, which is a flat first transparent substrate 12 made of a light-transmitting material such as glass, a color filter layer (not shown), a first transparent electrode 14, and a first transparent electrode 14. 1 alignment film 16.

  On the other hand, the second substrate 20 is a so-called TFT (Thin Film Transistor) substrate, and, like the first substrate 10, a flat second transparent substrate 22 made of a translucent material such as glass and a TFT wiring layer ( (Not shown), a transparent electrode 24, and a second alignment film 26.

  The first substrate 10 and the second substrate 20 are bonded together via a spacer 30 for controlling the layer thickness of the liquid crystal layer 50 to form one cell.

  Hereinafter, each substrate will be described in more detail.

(Transparent electrode)
First, the first transparent electrode 14 is provided on the surface of the first transparent substrate 12 facing the second transparent substrate 22, while the second transparent electrode 24 is a first transparent electrode on the second transparent substrate 22. It is provided on the opposite surface of the substrate 12. That is, the first transparent electrode 14 and the second transparent electrode 24 are disposed to face each other.

  The first transparent electrode 14 and the second transparent electrode 24 are both formed on each transparent substrate (the first transparent substrate 12 and the second transparent substrate 22), for example, ITO (Indium Tin Oxide). ) Or the like is sputtered to form a film, and then patterned into an appropriate shape by photolithography.

  The first transparent electrode 14 and the second transparent electrode 24 are configured such that pixels are formed in portions where the patterns overlap each other, and an electric field is formed in the pixel portion by applying a potential from the outside, The liquid crystal molecules in the pixel portion are switched.

(spacer)
Next, the spacer 30 will be described. In the liquid crystal display element 1 of the present embodiment, the spacer 30 is provided on the first substrate 10 that is the color filter substrate. Specifically, a columnar spacer 30 having a substantially conical shape is provided on the first transparent electrode 14 on the first transparent substrate 12 constituting the first substrate 10.

  For example, a resin columnar spacer formed on the color filter can be used as the spacer 30. The spacer 30 can be formed in advance by a photolithography method using a photosensitive resin on a color filter.

  Moreover, it can also form as a black matrix in a color filter, or integral with a black matrix.

  Since the spacer 30 is a protrusion for controlling the layer thickness of the liquid crystal layer 50, its size, such as height, depends first on the design of the cell, but preferably its shape. Is a cylindrical shape, and the height of the cylinder is 4.5 μm. Moreover, it is preferable that the diameter of a cylinder is 25 micrometers or less.

(Alignment film)
In the first substrate 10, as shown in FIG. 1, the first alignment film 16 is provided on the first transparent electrode 14 and the columnar spacer 30.

  On the other hand, in the second substrate 20, as in the first substrate 10, a second alignment film 26 is provided on the second transparent electrode 24.

  That is, the first alignment film 16 is formed so as to cover the entire surface of the first substrate 10 on which the first transparent electrode 14 is formed, while the second alignment film 26 is formed on the second substrate 20. It is formed so as to cover the entire surface on the side where the two transparent electrodes 24 are formed. Accordingly, the first alignment film 16 and the second alignment film 26 are disposed to face each other.

(Alignment film material)
Here, a voltage is applied between the first substrate 10 and the second substrate 20 in the alignment films (first alignment film 16 and second alignment film 26) used in the liquid crystal display element 1 of the present embodiment. The orientation of the liquid crystal molecules 52 is controlled so that the major axis direction of the liquid crystal molecules 52 is substantially perpendicular to the substrate surfaces of the first substrate 10 and the second substrate 20 (a state closer to perpendicular than parallel). Is for. That is, the vertical alignment film is used in the liquid crystal display element 1 of the present embodiment.

  The first alignment film 16 and the second alignment film 26 are desirably organic films, improve the degree of alignment order of the liquid crystal molecules 52, and align the liquid crystal molecules 52 in a desired direction. It is necessary to make it.

  As the alignment film material having such characteristics, for example, polyimide, particularly soluble polyimide having an imidization ratio of 50% to 80% is preferable.

  By using an alignment film material having the property of aligning the liquid crystal molecules 52 in the vertical direction, for example, a rubbing alignment process is performed on a CF (color filter) substrate on which a resin BM (black matrix) and PS (photo spacer) are formed. In the normally black TN (Twisted-Nematic) liquid crystal display mode, the display unevenness can be reduced.

  In addition, as an alignment film (the 1st alignment film 16, the 2nd alignment film 26) material which has the said characteristic, a commercially available vertical alignment film can be used, for example, AL-60601 (brand name) by JSR Corporation. Can be used.

(Orientation treatment)
The first alignment film 16 and the second alignment film 26 are preliminarily subjected to a uniaxial alignment process (for example, a rubbing alignment process) for determining a direction in which the liquid crystal molecules 52 are inclined when an electric field is applied. ing.

  That is, in the present invention, not only the rubbing alignment process is performed on the second alignment film 26 on the side where the cell thickness control member for controlling the thickness of the liquid crystal layer 50 such as the spacer 30 is not provided, but also the spacer 30 is provided. The rubbing alignment treatment is also applied to the first alignment film 16 on the side where it is present.

  The rubbing alignment treatment imparts an alignment film tilt to the first alignment film 16 and the second alignment film 26. Here, the alignment film tilt means a tilt angle given to molecules on the surface of the alignment film by rubbing alignment treatment or the like.

  In this embodiment, a vertical alignment film is used as the alignment film material, and the average value of the pretilt angles is preferably 45 ° or more and less than 90 °. Furthermore, it is more preferable that it is 88 degrees or less. Here, the pretilt angle means an angle formed between the substrate (the first substrate 10 or the second substrate 20) and the major axis direction of the liquid crystal molecules 52.

  Hereinafter, the pretilt angle will be described in more detail.

(Pretilt angle)
Since the liquid crystal display element 1 according to the present embodiment includes the first alignment film 16 and the second alignment film 26 that have been subjected to the rubbing alignment process as described above, the liquid crystal molecules 52 are formed on the substrate surface when no electric field is applied. It is inclined so as to be at a certain angle with respect to.

  The initial inclination angle of the long axis (director) of the liquid crystal molecules 52 in the state where no voltage is applied to the first transparent substrate 12 and the second transparent substrate 22 (first alignment film 16 and second alignment film 26). Is called the pretilt angle.

  The pretilt angle is ideally the same over the entire surface of the first substrate 10 and the second substrate 20, but in reality, the liquid crystal molecules 52 having slightly different pretilt angles are distributed over the entire surface. It has become. That is, the pretilt angle varies over the entire substrate surface. This “variation in pretilt angle” means that the initial tilt angle (pretilt angle) of the director of the liquid crystal molecules differs at the molecular level or in a region close thereto (for example, in a region having a radius of about 10 μm).

  In the present embodiment, the range of such a pretilt angle variation is about α ± 3 °, where α is the median pretilt angle in the liquid crystal material in the display region. For example, in the present embodiment, since the first alignment film 16 is a vertical alignment film, the pretilt angle is about 87 ° ± 3 °. That is, in this case, liquid crystal molecules having a pretilt angle of 84 ° to 90 ° when no voltage is applied are distributed. The same applies to the second alignment film 26.

  However, since the spacer 30 as a protrusion is provided for the first alignment film 16, the rubbing with respect to the shadowed region of the spacer 30 becomes insufficient, and the pretilt angle in this region is approximately 90 °. (Rubbing failure area BA).

  A known technique can be used as the pretilt angle measurement method, and for example, a measurement method using a crystal rotation method can be used. The outline of the specific measurement principle is as follows.

  First, a test panel is disposed between two polarizing plates, and a laser beam is irradiated while rotating the test panel. Then, the amount of light transmitted through the analyzer can be measured while changing the incident angle of light.

  A fitting by a 2 × 2 matrix method is performed on the rotation angle versus transmittance curve of the obtained test panel to measure the pretilt angle. However, the method for measuring the pretilt angle is not limited to this, and other methods may be used for measurement.

(Liquid crystal layer)
Further, as described above, the liquid crystal layer (substance layer having dielectric anisotropy) 50 is sandwiched between the first substrate 10 and the second substrate 20. The liquid crystal layer 50 includes a liquid crystal material (liquid crystal substance) and a chiral agent.

(Liquid crystal material)
The liquid crystal material includes a large number of liquid crystal molecules 52.

  The liquid crystal material has a negative dielectric anisotropy (Δε) and a predetermined chiral pitch length.

  Here, the liquid crystal material usable in the present invention preferably has a physical property of a rotational viscosity of 100 mPa · S to 250 mPa · S.

  When the rotational viscosity is 250 mPa · S or more, the viscosity of the liquid crystal material is too high to obtain a practical liquid crystal response. On the other hand, when the rotational viscosity is 100 mPa · S or less, the liquid crystal molecules in the poor rubbing region This is because a problem arises in the orientation regulation of the present invention, and it becomes difficult to eliminate the nonuniformity defect of the present invention.

  As the liquid crystal material having negative dielectric anisotropy Δε used in the present embodiment, for example, MLC-6608 (trade name) manufactured by Merck & Co., Inc. can be used.

(Chiral agent)
The chiral agent is for imparting a predetermined chiral pitch length to the liquid crystal material. The chiral agent that can be used in the present invention is not particularly limited as long as it is appropriately changed according to the liquid crystal material and the degree of the chiral pitch length to be imparted.

  For example, a chiral agent S-811 (trade name) manufactured by Merck & Co., Inc. can be used as the chiral agent.

  In addition, the addition amount of the chiral agent may be a predetermined amount depending on the liquid crystal material and the length of the chiral pitch to be applied.

  The liquid crystal display element 1 according to the present embodiment has the above-described configuration, so that when an electric field is applied to the liquid crystal layer 50 through the first transparent electrode 14 and the second transparent electrode 24, the liquid crystal molecules 52 are twisted and fall down. In other words, a so-called twisted vertical alignment (TVA) mode is realized.

(Polarizer)
A first polarizing plate 41 and a second polarizing plate 42 are provided on the outside of the first substrate 10 and the second substrate 20, that is, on the surface opposite to the facing surfaces of the two substrates 10 and 20, respectively. ing.

  Here, the second polarizing plate 42 is arranged so that the polarization axis thereof coincides with the rubbing direction of the second alignment film 26, and the first polarizing plate 41 has the polarization axis of the second alignment film. 26 are arranged so as to be substantially orthogonal to the rubbing direction of 26. That is, the 1st polarizing plate 41 and the 2nd polarizing plate 42 are arrange | positioned so that each polarization axis may become a substantially orthogonal direction.

(Alignment of liquid crystal molecules)
Next, the alignment state of the liquid crystal molecules 52 in the liquid crystal display element 1 of the present embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram showing the alignment state of the liquid crystal molecules 52 in the liquid crystal display element 1 of the present embodiment as described above.

  As shown in FIG. 2, the first transparent substrate 12 of the present embodiment is provided with protrusions, specifically, columnar spacers 30.

  As described above, in the liquid crystal display element 1 of the present embodiment, the first alignment film 16 is provided after the spacer 30 is provided on the first transparent substrate 12.

  Therefore, the first alignment film 16 is formed on the side surface and the upper surface of the columnar spacer 30 in the same manner as the portion where the spacer 30 is not provided on the first transparent substrate. That is, the first alignment film 16 is also provided on the surface of the spacer 30.

  The first alignment film 16 is subjected to a rubbing alignment process in the direction indicated by the white arrow R in FIG.

  Here, when the rubbing alignment process is performed in the direction of the white arrow R in FIG. 2, the hatched area shown in FIG. 2 becomes a shadow of the spacer 30, so that the rubbing cloth hardly enters. As a result, since the rubbing cloth is difficult to contact the first alignment film 16 in the hatched area, rubbing may be insufficient (rubbing failure area: BA shown in FIG. 2).

  That is, the rubbing normal region (region GA shown in FIG. 2) in which the rubbing alignment treatment is normally performed on the first alignment film 16 of the first substrate 10 provided with the protrusions such as the spacers 30 and the rubbing failure region. BA may coexist.

(Conventional liquid crystal display device)
As described above, in the conventional liquid crystal display element 1 using the horizontal alignment film and the positive dielectric anisotropic liquid crystal molecules, disclination occurs in the rubbing failure area BA, and the display quality is deteriorated. It was.

  That is, in the rubbing failure area BA, since the alignment film tilt is not given to the first alignment film 16, the liquid crystal molecules 52 do not have a pretilt angle. Since the liquid crystal molecules 52 have no pretilt angle, that is, the major axis direction of the liquid crystal molecules 52 is substantially parallel to the first transparent substrate 12, the rising direction of the liquid crystal molecules 52 when a voltage is applied to the liquid crystal molecules 52. Will fall apart. Therefore, for example, when displaying black by applying a voltage, bright lines or the like are generated in the rubbing failure area BA, and the display quality is impaired (see FIG. 4).

(Liquid crystal display element of this embodiment)
On the other hand, in the liquid crystal display element 1 of the present embodiment, even when the rubbing alignment process is slightly insufficient, the display quality is not easily lowered.

  That is, as shown in FIG. 2, the liquid crystal molecules 52 in the present embodiment are vertically aligned in a state where no voltage is applied. Here, the vertical alignment means a state in which the major axis direction of the liquid crystal molecules 52 stands with respect to the first transparent substrate 12, more preferably a state in which the liquid crystal molecules 52 are aligned substantially vertically.

  When a voltage is applied to the liquid crystal molecules 52, the liquid crystal molecules 52 are tilted so that the major axis direction is substantially parallel to the first transparent substrate 12. That is, the liquid crystal molecules 52 are tilted in the direction indicated by the arrow C in FIG.

  This is because the liquid crystal display element 1 of the present embodiment differs from the conventional liquid crystal display element 1 in that a vertical alignment film is used as an alignment film material instead of a horizontal alignment film, and a positive dielectric difference is used as the liquid crystal material. This is because negative dielectric anisotropic liquid crystal molecules are used instead of isotropic liquid crystal molecules. The negative dielectric anisotropic liquid crystal molecule means a liquid crystal molecule having a property that the major axis direction of the liquid crystal molecule is perpendicular to the electric field when a voltage is applied to the liquid crystal molecule.

  Here, also in the liquid crystal display element 1 of the present embodiment, as in the conventional liquid crystal display element 1, a rubbing normal region in which the rubbing alignment treatment is normally performed on the first alignment film 16 (shown in FIG. 2). The region GA) and a rubbing failure region (region GA shown in FIG. 2) in which the rubbing alignment treatment has not been normally performed may coexist.

  However, in the present embodiment, even when the rubbing failure area BA occurs, disclination occurs in the rubbing failure area BA, and the display quality is rarely impaired thereby. This will be described below.

  As described above, the liquid crystal molecules 52 in the present embodiment are vertically aligned when no voltage is applied, and fall down in parallel with the first substrate 10 when a voltage is applied. As directions in which the liquid crystal molecules 52 are tilted when this voltage is applied, a direction indicated by an arrow C and a direction indicated by an arrow D in FIG.

  Here, the first alignment film 16 in the normal rubbing region GA is given an alignment film tilt by the rubbing alignment treatment. Accordingly, the liquid crystal molecules 52 in the normal rubbing region GA have a pretilt angle of about 87 ° as described above.

  As a result, the direction in which the liquid crystal molecules 52 in the normal rubbing region GA are tilted is defined as one direction. In the liquid crystal molecules 52 in the present embodiment, the liquid crystal molecules 52 are tilted in the direction indicated by the arrow C in FIG.

  In the liquid crystal molecules 52 in the present embodiment, when the direction in which the liquid crystal molecules 52 in the normal rubbing region GA are tilted is defined as one direction as described above, the direction of the liquid crystal molecules 52 in the rubbing defective region BA is also It is easy to be defined in one direction. This is because the liquid crystal molecules 52 in the present embodiment, unlike the liquid crystal molecules 52 in the conventional liquid crystal display element 1, change from vertical alignment to horizontal alignment when a voltage is applied. This will be described below.

  When the major axis direction of the liquid crystal molecule 52 in the present embodiment is inclined from the vertical to the horizontal with respect to the first substrate 10, the liquid crystal molecule 52 is adjacent to the first substrate 10 in the direction parallel to the first substrate 10. On the other hand, it exerts a great influence to tilt in the same direction.

  In the present embodiment, this is a state in which the liquid crystal molecules 52 are aligned in the direction parallel to the first substrate 10 while overlapping the major axis direction (a state in which the liquid crystal molecules 52 are spread in the plane). This is because some of the liquid crystal molecules 52 are inclined. The adjacent liquid crystal molecules 52 fall in one direction in a so-called shogi manner.

  Therefore, at the boundary between the rubbing normal area GA and the rubbing failure area BA, the liquid crystal molecules 52 in the rubbing failure area BA are affected by the liquid crystal molecules 52 in the adjacent rubbing normal area GA. Even if the force is weak, the liquid crystal molecules 52 fall in the same direction, and as a result, disclination hardly occurs.

(Summary)
As described above, the liquid crystal molecules 52 in the conventional liquid crystal display element 1 are different from each other in terms of how the liquid crystal molecules 52 are tilted when a voltage is applied. 52 was less affected.

  On the other hand, the liquid crystal molecules 52 in the liquid crystal display element 1 of the present embodiment are not affected by the liquid crystal molecules 52 in the rubbing failure area BA and the liquid crystals in the rubbing normal area GA in terms of how the liquid crystal molecules 52 fall when the voltage is applied. It tends to affect the molecule 52.

  As a result, the first alignment film 16 in the rubbing failure area BA is not sufficiently rubbed, and only the liquid crystal molecules 52 in the rubbing failure area BA have one way of tilting the liquid crystal molecules 52 when a voltage is applied. Even in the case where it is difficult to be defined, the tilt direction is the same as that of the periphery and the liquid crystal molecules 52, so that there is no difference in transmittance from the rubbing normal area GA and no unevenness occurs. For example, in the normally black mode, a desired white display is obtained, so that display quality is not easily lost.

(More detailed explanation)
In the liquid crystal display element 1 according to the present invention, as described above, the liquid crystal molecules 52 in the defective rubbing region BA are controlled to be inclined to the same degree (angle) in the same direction as the liquid crystal molecules 52 in the normal rubbing region GA. In the following, the force acting on the control and a specific method for increasing the control will be described with reference to FIG.

  The three forces indicated by the arrows X, Y, and Z in FIG. 2 are acting on the liquid crystal molecules 52. In order to control the liquid crystal molecules 52 as described above, it is necessary to control the three forces.

(Power of X)
First, the X force indicated by the arrow X causes the liquid crystal molecules 52 in the rubbing failure area BA to be rubbed in the normal rubbing area GA when a voltage is applied due to the effect of a step (columnar spacer 30 or black matrix) due to the protrusion. This indicates a force to tilt the liquid crystal molecules 52 in the opposite direction.

(The power of Y)
Next, the Y force indicated by the arrow Y is applied to the liquid crystal molecules 52 in the rubbing failure area BA, because the liquid crystal molecules 52 tend to fall apart in different directions due to the absence of a pretilt angle. Among them, a force for tilting in the direction opposite to the liquid crystal molecules 52 in the normal rubbing region GA is shown.

  The reason why the pretilt angle is not given is that, as described above, the second alignment film 26 in the rubbing failure area BA is behind the protrusion and is not sufficiently rubbed.

(The power of Z)
Further, the force of Z indicated by the arrow Z is the force that the liquid crystal molecules 52 in the rubbing failure area BA receive from the liquid crystal molecules 52 in the normal rubbing area GA, that is, the liquid crystal molecules 52 in the rubbing failure area BA are applied to the normal rubbing area GA. This shows the force to cause the liquid crystal molecules 52 to tilt in the same direction.

  In other words, the liquid crystal molecules 52 that fall regularly in the rubbing normal area GA show a force to defeat the adjacent liquid crystal molecules 52 in a shogi manner.

(Power relationship)
In order to cause the liquid crystal molecules 52 in the defective rubbing area BA to tilt in the same direction as the liquid crystal molecules 52 in the normal rubbing area GA, it is necessary to control the three forces to a force relationship of X + Y <Z. That is, it is necessary to reduce the X and Y forces while increasing the Z force. Hereinafter, each means will be described.

(The power of X)
First, in order to reduce the force of X, it is important to set the rotational viscosity of the liquid crystal material to a range of 100 mPa · S to 250 mPa · S and to use a vertical alignment film as the alignment film material.

  In addition, as a method for further reducing the force of X, for example, the following method can be considered.

(First method)
First, as a first method, a method of minimizing the shape of the step due to the protrusion is conceivable. Specifically, for example, a method of reducing the height of the step (4.5 μm or less) can be considered.

  Here, the height of the step means the height of the projection, and specifically, for example, when the projection is a spacer, it means the height of the spacer. In the case of a resin black matrix, it means the thickness of the resin black matrix (the step height of the black matrix).

  By reducing the height of the step in this way, the area of the region (rubbing failure area BA) that is not subjected to sufficient rubbing rubbing due to the shadow of the projection during the rubbing alignment treatment can be reduced. .

  In addition to reducing the height of the protrusion, a method of reducing the surface area of the protrusion is also conceivable. Specifically, for example, when the protrusion is a columnar spacer, it is conceivable to reduce the diameter of the column (25 μm or less).

  By reducing the surface area of the protrusions in this way, the liquid crystal molecules are affected by the alignment film on the surface of the protrusions that are not normally subjected to the rubbing alignment treatment, and the influence of reducing the uniformity of the alignment of the liquid crystal molecules, for example, The influence of aligning liquid crystal molecules in various directions can be reduced.

(Second method)
Next, the second method will be described.

  As a second method, a method of reducing the thickness of the alignment film applied to the protrusion may be considered.

  Specifically, for example, it is considered that the thickness of the alignment film on the protrusion is 50% or less of the alignment film of other portions (for example, the alignment film on the first transparent electrode 14 and the second transparent electrode 24). It is done.

  In general, as the alignment film becomes thinner, the alignment regulating force on the liquid crystal molecules decreases. Therefore, as described above, reducing the thickness of the alignment film on the protrusions can reduce the influence that the liquid crystal molecules receive from the alignment film on the surface of the protrusions, which lowers the alignment uniformity of the liquid crystal molecules. it can.

(Third method)
Next, the third method will be described.

  As a third method, for example, a method is conceivable in which the protrusion is formed into a special shape so that the alignment film is not applied to the side surface (step side surface) of the protrusion.

  Specifically, for example, when the protrusion is a columnar spacer, the shape of the spacer may be a mushroom shape.

  In this way, by preventing the alignment film from being applied to the side surfaces of the protrusions, it is possible to reduce the influence that the liquid crystal molecules receive from the alignment films on the side surfaces of the protrusions, which lowers the alignment uniformity of the liquid crystal molecules. Can do.

(The power of Y)
Next, a method for reducing the Y force will be described.

(First method)
First, as a first method, a method of reducing the area of the rubbing failure area BA can be considered.

  Specifically, for example, the area of the rubbing failure area BA (area without tilt control) in which the alignment film tilt is not imparted and the control of the pretilt angle with respect to the liquid crystal molecules is lowered is defined as the first transparent substrate 12 or It is conceivable to control the area of the second transparent substrate 22 to 20% or less.

  Further, as described in the X force, a method of reducing the height of the step of the projection (for example, 4.5 μm or less) is also effective.

(Second method)
Next, the second method will be described.

  As a second method, a method in which the rubbing state (alignment film tilt, alignment regulation force, etc.) of the alignment film in the defective rubbing region BA is as close as possible to the rubbing state of the alignment film in the normal rubbing region GA is conceivable. That is, the alignment film in the normal rubbing region GA should be able to provide even a slight pretilt angle even if the pretilt angle comparable to the alignment film in the defective rubbing region BA cannot be applied to the liquid crystal molecules. Can be considered.

  As specific means, first, a means for lengthening the hair of the rubbing cloth used in the rubbing alignment treatment (for example, 2.0 mm or more) can be considered.

  Further, as another means, a means for softening the rubbing cloth by treating the rubbing cloth with hydrogen peroxide solution can be considered.

  By using the above-mentioned means, the rubbing cloth can be easily applied to the back side of the projection (easy to reach). It can be made closer to the rubbing state of the normal area GA.

(Power of X and Y)
Next, a method for reducing both the X force and the Y force will be described.

  As a method for reducing the respective forces, it is conceivable to use a material that easily repels the alignment film as a material constituting the protrusion such as a spacer.

  Examples of the material include a material containing a halogen such as fluorine, a material having a siloxane bond, a material containing an olefin such as polyethylene or polystyrene, a material mixed with silica beads or glass fiber, or a bisazide compound. Materials and the like.

  Projections such as spacers made of these materials are easy to repel the alignment film, so that the alignment film is hardly formed on the surface of the protrusion. As a result, it is possible to reduce the influence that the liquid crystal molecules receive from the alignment film on the surface of the protrusion, which lowers the alignment uniformity of the liquid crystal molecules.

  As described above, by enhancing the repelling of the projection surface, the application of the alignment film itself to the projection surface is suppressed, and the X force and the Y force (the force acting due to the rubbing failure area BA) are weakened. Then, the other Z force (force caused by the rubbing normal area GA) can be relatively strengthened.

(The power of Z)
Next, a method for increasing the Z force will be described.

In order to increase the Z force, a method of increasing the alignment film tilt of the liquid crystal molecules 52 in the normal rubbing region GA can be considered. Specifically, for example, a method of setting the alignment film tilt or pretilt angle to 88 ° or less is conceivable. The lower limit of the alignment film tilt or pretilt angle at that time is preferably, for example, 75 ° or more.

  As a specific means, for example, the alignment film tilt imparted to the molecules on the alignment film surface is increased by strongly performing a rubbing alignment treatment or the like, thereby increasing the angle formed between the substrate and the major axis direction of the liquid crystal molecules. A means for increasing a certain pretilt angle is conceivable. Here, the alignment film tilt and the pretilt angle indicate an average value within a certain in-plane / region.

  By increasing the alignment film tilt or pretilt angle as described above, the force to tilt the liquid crystal molecules 52 in the rubbing normal area GA increases, and accordingly, the force to tilt the liquid crystal molecules 52 in the rubbing failure area BA increases. .

(Liquid crystal display device)
Next, the structure of the liquid crystal display device of this embodiment will be briefly described with reference to FIG. Here, FIG. 3 is a block diagram showing the configuration of the liquid crystal display device 100 of the present embodiment together with an equivalent circuit and the like.

  The liquid crystal display device 100 includes an active matrix including a source driver 80 as a data signal line driving circuit, a gate driver 82 as a scanning signal line driving circuit, the liquid crystal display element, a backlight unit (not shown), and the like. A display unit 84, a display control circuit 86 for controlling the source driver 80 and the gate driver 82, and a gradation voltage source 88.

  The display unit 84 in the liquid crystal display device 100 includes a plurality (m) of gate lines GL1 to GLm as a plurality (m) of scanning signal lines and a plurality (n) of the gate lines GL1 to GLm. Source lines SL1 to SLn as data signal lines, and a plurality (m × n) of pixel forming portions provided corresponding to the intersections of the gate lines GL1 to GLm and the source lines SL1 to SLn, including.

  These pixel formation portions are arranged in a matrix to form a pixel array, and each pixel formation portion has a gate terminal connected to a gate line GLj passing through a corresponding intersection and a source line SLi passing through the intersection. A TFT 90 as a switching element to which a source terminal is connected, a pixel electrode (second transparent electrode) connected to the drain terminal of the TFT 90, and an electrode (first transparent electrode) provided in common to the plurality of pixel formation portions Electrode) and a liquid crystal layer disposed in common between the plurality of pixel formation portions and disposed between the pixel electrode and the capacitor electrode as the first voltage application electrode.

  In FIG. 3, Cp is a pixel capacity, DA is a digital image signal, Dc is a control signal, Dv is a digital video signal, GCK is a gate clock signal, GOE is a gate driver output control signal, and GSP is a gate. The start pulse signal, HSY is a horizontal synchronization signal, SSP is a source start pulse signal, SCK is a source clock signal, VSY is a vertical synchronization signal, and Vcs is a capacitance electrode applied voltage.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  Since the display failure due to the rubbing failure is suppressed while suppressing the deterioration of the optical performance, it can be used for a large-screen high-quality liquid crystal display device in which the rubbing failure is conspicuous.

1, showing an embodiment of the present invention, is a schematic view showing an alignment state of liquid crystal molecules. FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, showing an embodiment of the present invention, is a schematic diagram schematically showing an alignment state of liquid crystal molecules in a liquid crystal display element. 1, showing an embodiment of the present invention, is a block diagram showing a configuration of a liquid crystal display device together with an equivalent circuit and the like. FIG. It is a schematic diagram showing a conventional technique and schematically showing the alignment state of liquid crystal molecules in a liquid crystal display element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 10 1st board | substrate 12 1st transparent substrate (board | substrate)
14 First transparent electrode 16 First alignment film (alignment film)
20 Second substrate 22 Second transparent substrate (substrate)
24 Second transparent electrode 26 Second alignment film (alignment film)
30 Spacer (projection)
41 First polarizing plate 42 Second polarizing plate 50 Liquid crystal layer (material layer having dielectric anisotropy)
52 Liquid Crystal Molecule 80 Source Driver 82 Gate Driver 84 Display Unit 86 Display Control Circuit 88 Gradation Voltage Source 90 TFT
100 LCD device GA rubbing normal area BA rubbing defective area

Claims (21)

A liquid crystal display device comprising a pair of substrates having alignment films formed on opposite surfaces, and a material layer having dielectric anisotropy sandwiched between the pair of substrates,
Projections are provided on at least one of the pair of substrates,
The material layer having dielectric anisotropy includes a liquid crystalline material having negative dielectric anisotropy,
The alignment film is a vertical alignment film,
The liquid crystal display element, wherein the alignment film is subjected to an alignment treatment for imparting a pretilt angle to the liquid crystalline substance.   The liquid crystal display element according to claim 1, wherein the pretilt angle is 45 ° or more and less than 90 °.   The liquid crystal display element according to claim 2, wherein the pretilt angle is 88 ° or less.   The liquid crystal display element according to claim 1, wherein the protrusion is a spacer for controlling a distance between the pair of substrates.   The liquid crystal display element according to claim 1, wherein the liquid crystalline substance exhibits a nematic liquid crystal phase. A chiral agent is added to the material layer having dielectric anisotropy,
The liquid crystal display element according to claim 5, wherein the liquid crystal substance has a rotational viscosity of 100 mPa · S or more and 250 mPa · S or less. The alignment film contains a polyimide compound,
The liquid crystal display element according to claim 1, wherein an imidization ratio of the polyimide compound is 50% or more and 80% or less.   The liquid crystal display element according to claim 1, wherein a height of the protrusion is 4.5 μm or less. The shape of the protrusion is a columnar shape,
The liquid crystal display element according to claim 1, wherein a diameter of the column is 25 μm or less.   The liquid crystal display element according to claim 1, wherein a film thickness of the alignment film on the surface of the protrusion is 50% or less of a film thickness of the alignment film on the surface of the substrate.   The liquid crystal display element according to claim 1, wherein a region where an alignment film is not formed is provided on a side surface of the protrusion. The alignment treatment is a rubbing alignment treatment;
The liquid crystal display element according to claim 1, wherein a length of a bristle of a rubbing cloth used for the rubbing alignment treatment is 2.0 mm or more and 5.0 mm or less. The alignment treatment is a rubbing alignment treatment;
The liquid crystal display element according to claim 1, wherein a rubbing cloth used for the rubbing alignment treatment is immersed in hydrogen peroxide water.   The liquid crystal display element according to claim 1, wherein the protrusion is formed of a material containing at least a part of a compound containing a halogen atom.   The liquid crystal display element according to claim 14, wherein the halogen atom is a fluorine atom.   The liquid crystal display element according to claim 1, wherein the protrusion is formed of a material containing at least a part of a compound containing a siloxane bond.   The liquid crystal display element according to claim 1, wherein the protrusion is made of a material containing at least a part of an olefin compound.   The liquid crystal display element according to claim 17, wherein the olefin compound is polyethylene, polystyrene, or polyethylene and polystyrene.   The liquid crystal display element according to claim 1, wherein the protrusion is made of silica beads, glass fibers, or a material in which silica beads and glass fibers are mixed.   The liquid crystal display element according to claim 1, wherein the protrusion is made of a material containing at least a part of a bisazide compound.   A liquid crystal display device comprising the liquid crystal display element according to claim 1.

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