KR20200065735A - Alignment layer having improved attachment, method of fabricating alignment layer and liquid crystal display device having alignment layer - Google Patents

Abstract

The present invention relates to an alignment film capable of preventing adhesion defects. The alignment film has: a first alignment film formed on a substrate; and a second alignment film formed on the first alignment film, wherein the first alignment film has a greater adhesion than the second alignment film, and the second alignment film has a larger alignment control force than the first alignment film.

Description

ALIGNMENT LAYER HAVING IMPROVED ATTACHMENT, METHOD OF FABRICATING ALIGNMENT LAYER AND LIQUID CRYSTAL DISPLAY DEVICE HAVING ALIGNMENT LAYER}

The present invention relates to an alignment film with improved adhesion, an alignment film manufacturing method with improved adhesion, and a liquid crystal display device having an alignment film.

In recent years, with the development of technology, the size of a flat panel display device that has been applied to various portable electronic devices such as mobile phones, PDAs, and notebook computers or televisions is gradually increasing. LCD (Liquid Crystal Display), PDP (Plasma Display Panel), and OLED (Organic Light Emitting Device Panel) are actively researched as such flat panel display devices, especially for reasons of mass production technology, ease of driving means, and realization of high image quality. A liquid crystal display (LCD) is widely used.

Since the liquid crystal display device is not a self-luminous display device, a light source that supplies light is required, and an image is realized by controlling the transmittance of light supplied from the light source. At this time, light transmittance is controlled by a liquid crystal layer and a polarizing plate. That is, an image is realized by controlling the transmittance of light passing through the liquid crystal layer and the polarizing plate by arranging two polarizing plates such that the transmission axis is parallel or perpendicular and controlling the arrangement direction of the liquid crystal molecules of the liquid crystal layer disposed therebetween.

The alignment control of the liquid crystal molecules is performed by an alignment film and a pair of electrodes. The alignment layer determines the initial alignment state of the liquid crystal molecules, and the pair of electrodes adjusts the alignment state of the liquid crystal molecules according to application of a signal to control light transmittance.

However, a liquid crystal display device having an alignment film has the following problems. The liquid crystal display device is composed of an upper and lower substrate bonded by a sealant and a liquid crystal layer therebetween, and an alignment layer is formed on each of the upper and lower substrates to orient the liquid crystal molecules in a predetermined initial direction.

On the other hand, the alignment film is formed by printing on the upper and lower substrates in a liquid state and then drying. However, due to the viscosity of the liquid alignment layer, limitations in printing technology, and process errors, the alignment layer is not formed accurately in the set region. For example, when the alignment layer is invaded into a region where the sealant is formed and the alignment layer overlaps with the sealant, adhesion strength of the sealant is lowered to cause adhesion defects in the display device, and the alignment layer is not applied to the entire set region and some areas are not applied. When applied only to light, light is leaked to an area where the alignment layer is not applied (for example, a border area of the display device) to generate a bright line in the area.

The present invention has been made in view of the above points, and an object of the present invention is to provide an alignment film and a liquid crystal display device capable of preventing adhesion defects by forming a sealant on an alignment film having relatively good adhesion properties.

Another object of the present invention is to provide an alignment layer and a liquid crystal display device capable of preventing light leakage from occurring through the outside by forming an alignment layer on the outer side of the display unit.

In order to achieve the above object, the alignment layer according to the present invention includes a first alignment layer formed on a substrate; A second alignment layer is formed on the first alignment layer, the first alignment layer has a greater adhesion than the second alignment layer, and the second alignment layer has a larger alignment control force than the first alignment layer.

The second alignment layer may be composed of a polyimide-based polymer or a polyamide-based polymer, and the first alignment layer may be composed of a polyamide-based polymer containing an additive that forms a photosensitive side chain. Further, the first alignment layer may be made of a polyamide-based polymer to which a crosslinking agent is added.

The first alignment layer includes a first hydrophilic region and a second hydrophobic region formed outside the first region, and the second alignment layer is arranged in a self-aligned manner over the first region of the first alignment layer.

In addition, the display device according to the present invention includes a first substrate and a second substrate including a display area and a pad area; A liquid crystal layer disposed between the first substrate and the second substrate; An alignment layer formed on the first substrate and the second substrate; It is formed between the first substrate and the second region of the alignment layer formed on the second substrate, and is composed of a sealant for bonding the first substrate and the second substrate.

And, the method of forming an alignment layer according to the present invention includes forming a hydrophobic first alignment layer formed on a substrate; Converting the hydrophilicity of the irradiated area by irradiating ultraviolet rays to the set area of the first alignment layer; Forming a second alignment layer self-aligned with a hydrophilic region on the first alignment layer by applying a liquid alignment material on the first alignment layer; And aligning the first alignment layer and the first alignment layer.

In the present invention, since the alignment layer is formed in a two-layer structure of an upper alignment layer having a strong alignment regulating force and a lower alignment layer having a good alignment regulating force and bonding strength, it is possible to prevent adhesion defects due to deterioration of the bonding force with the sealant as well as a border region. It is possible to prevent the frame defect caused by light leakage.

In addition, it is possible to effectively prevent a decrease in aperture ratio caused by forming a black matrix to block light leakage in the border area.

1 is a plan view schematically showing the structure of a liquid crystal display device according to the present invention.
2 is a cross-sectional view showing the structure of a liquid crystal display device according to the present invention.
3 is an enlarged cross-sectional view of the outer portion of FIG. 2.
4 is a view showing that the alignment material is applied to the substrate by a general coating method.
5A and 5B are enlarged cross-sectional views each showing a structure of a liquid crystal display device formed by a general coating method.
6 is a flowchart showing a method of manufacturing a liquid crystal display device according to the present invention.
7 is a flowchart showing a method for forming an alignment layer according to the present invention.
8A to 8E are views showing a method for forming an alignment film according to the present invention.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for describing the embodiments of the present invention are exemplary and the present invention is not limited to the illustrated matters. The same reference numerals refer to the same components throughout the specification. In addition, in the description of the present invention, when it is determined that detailed descriptions of related known technologies may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted. When'include','have','consist of', etc. mentioned in the specification are used, other parts may be added unless'~man' is used. When a component is expressed as a singular number, the plural number is included unless otherwise specified.

In interpreting the components, it is interpreted as including the error range even if there is no explicit description.

In the case of the description of the positional relationship, for example, when the positional relationship of two parts is described as'~top','~upper','~bottom','~side', etc. Alternatively, one or more other parts may be located between the two parts unless'direct' is used.

In the case of a description of a time relationship, for example,'after','following','~after','~before', etc. When a temporal sequential relationship is described,'right' or'direct' It may also include cases that are not continuous unless it is used.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are only used to distinguish one component from another component. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

Each of the features of the various embodiments of the present invention may be partially or wholly combined or combined with each other, technically various interlocking and driving is possible, and each of the embodiments may be independently performed with respect to each other or may be implemented together in an association relationship. It might be.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a plan view schematically showing the structure of a liquid crystal display device 100 according to the present invention.

As shown in FIG. 1, the liquid crystal display device 100 according to the present invention includes a display unit DA for realizing an image and a pad unit PA disposed on upper and left outer sides of the image display unit DA. It is composed.

A plurality of gate lines GL and a data line DL are vertically arranged in the display unit DA to define a plurality of pixels P, and the gate portions GL and data lines are respectively provided in the pad unit PA. A plurality of gate pads (g_pad) and data pads (d_pad) connected to (DL) are arranged. Although not shown in the drawing, a thin film transistor TFT connected to the gate line GL and the data line DL is disposed in each pixel P. The scan signal input through the gate pad (g_pad) is applied to the thin film transistor (TFT) through the gate line GL, and the image signal input through the data pad (d_pad) is a thin film transistor through the data line (DL). After being applied as (TFT), it is supplied to the pixel P.

A sealant 172 is applied to the outer periphery of the display unit DA to bond the first substrate 110 with a second substrate, that is, a color filter substrate (not shown). Although not shown in the drawings, an alignment layer is formed on each of the first substrate 110 and the second substrate, and a liquid crystal layer is provided therebetween, so that the liquid crystal molecules of the liquid crystal layer are aligned in a set direction by the regulating force of the alignment layer.

2 is a cross-sectional view showing the structure of a liquid crystal display device according to the present invention. The actual liquid crystal display device includes a plurality of pixels arranged in a matrix shape in the vertical and horizontal directions, but only one pixel is illustrated in the drawings for convenience of description.

2, the liquid crystal display device 100 according to the present invention is between the first substrate 110 and the second substrate 150, the first substrate 110 and the second substrate 150 It is composed of the liquid crystal layer 170 disposed. The first substrate 110 and the second substrate 150 may be made of a transparent and rigid material such as glass, and may be made of a transparent and flexible material such as plastic, but are not limited thereto.

A thin film transistor (TFT) is disposed on the first substrate 110. The thin film transistor (TFT) includes a gate electrode 122 disposed on the first substrate 110 and a gate insulating layer 112 stacked over the entire first substrate 110 on which the gate electrode 122 is formed, It is composed of a semiconductor layer 124 disposed on the gate insulating layer 112, a source electrode 125 and a drain electrode 126 on which the semiconductor layer 124 is formed.

The gate electrode 122 may be formed of a metal such as Cr, Mo, Ta, Cu, Ti, Al or Al alloy, and the gate insulating layer 112 is a single layer made of an inorganic insulating material such as SiO _x or SiNx. Or it may be made of an inorganic layer of a two-layer structure of SiO _x and SiNx.

The semiconductor layer 124 may be formed of an amorphous semiconductor material or crystalline semiconductor material. In addition, the semiconductor layer 124 may be formed of an oxide semiconductor such as Indium Gallium Zinc Oxide (IGZO).

The source electrode 125 and the drain electrode 126 may be formed of Cr, Mo, Ta, Cu, Ti, Al, or Al alloy, but are not limited thereto.

In the drawing, although a bottom gate method is disclosed in which a thin film transistor (TFT) is a gate electrode 122 is disposed below and a semiconductor layer 124 is disposed thereon, the thin film transistor (TFT) of the present invention is disclosed. Not limited to this structure, a top gate method in which the gate electrode 122 is disposed on the semiconductor layer 124 may be applied, and a thin film transistor (TFT) of another structure may also be applied.

A protective layer 114 is formed over the first substrate 110 on which the thin film transistor (TFT) is formed, and a first electrode 128 and a second electrode 129 are formed on the protective layer 114. .

The protective layer 114 may be formed of an organic material such as photoacrylic, but may also be composed of a plurality of layers made of an inorganic layer and an organic layer. A contact hole 114a is formed in the protective layer 114 on the drain electrode 126 of the thin film transistor (TFT), and the drain electrode 126 and the first electrode 128 are formed through the contact hole 114a. It is electrically connected.

Although not shown in the drawing, the first electrode 128 and the second electrode 129 are each configured in a strip shape having a set width and may be arranged in parallel along the gate line GL, and the gate line GL It may be arranged parallel to each other at a certain angle. In the drawing, the first electrode 128 and the second electrode 129 are disposed on the protective layer 114, respectively, but both the first electrode 128 and the second electrode 129 are gate insulating layers 112 or The first substrate 110 may be disposed, and the first electrode 128 and the second electrode 129 may be disposed on different layers 110, 112, and 114.

The first electrode 128 and the second electrode 129 may be made of a transparent metal oxide such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO), or a metal having good conductivity.

A black matrix (152) and a color filter layer (154) are formed on the second substrate (150). The black matrix 152 is formed in a non-display area in which an actual image is not displayed, such as a thin film transistor (TFT) formation area, a gate line, and a data line formation area. prevent. At this time, the black matrix 152 may be formed of an opaque metal such as CrO or CrOx or a black resin, but is not limited thereto.

The color filter layer 154 is for real color, and may be composed of R (Red), G (Green), and B (Blue) color filter layers.

A sealant 172 is applied to edge regions of the first substrate 110 and the second substrate 150 to bond the first substrate 110 and the second substrate 150. The sealant 172 may be printed on at least one of the first substrate 110 and the second substrate 150. The sealant 172 may be made of a thermosetting resin or a photocurable resin. For example, the sealant 172 may be made of an epoxy-based resin.

In addition, although not shown in the drawings, the first substrate 110 and the second substrate 150 are provided with ball-shaped or columnar spacers so that the first substrate 110 and the second substrate 150 are always constant. Try to keep a gap.

A liquid crystal layer 170 is formed between the bonded first substrate 110 and the second substrate 150. Liquid crystal molecules having anisotropic properties are distributed in the liquid crystal layer 170, and transmittance of light passing through the liquid crystal layer 170 is adjusted according to the arrangement of the liquid crystal molecules.

A first alignment layer 132 and a second alignment layer 134 are formed on the first substrate 110, and a third alignment layer 162 and a fourth alignment layer 164 are formed on the second substrate 150. The first alignment layer 132 and the second alignment layer 134 and the third alignment layer 162 and the fourth alignment layer 164 respectively determine an initial alignment direction of liquid crystal molecules in the liquid crystal layer 170. In this case, the alignment directions of the first alignment layer 132 and the second alignment layer 134 and the alignment directions of the third alignment layer 162 and the fourth alignment layer 164 may be perpendicular or parallel to each other.

The alignment direction of the alignment layer of the first substrate 110 (ie, the alignment direction of the first alignment layer 132 and the second alignment layer 134) and the alignment direction of the alignment layer of the second substrate 150 (ie, the third alignment layer) When the (162) and the fourth alignment layer 164 are aligned with each other, the liquid crystal molecules of the liquid crystal layer 170 are twisted at an angle of 90 degrees from the first substrate 110 side to the second substrate 15 side. do. In addition, when the alignment directions of the first alignment layer 132 and the second alignment layer 134 and the alignment directions of the third alignment layer 162 and the fourth alignment layer 164 are parallel to each other, liquid crystal molecules of the liquid crystal layer 170 Are all arranged in the same direction.

In the liquid crystal display device having such a configuration, when a scan signal is applied to the gate electrode 122 of the thin film transistor TFT through the gate line GL, the semiconductor layer 124 of the thin film transistor TFT is activated to activate the semiconductor layer. A channel layer is formed inside (124). At the same time, the image signal input through the data line DL is applied to the first electrode 128 through the channel layer formed in the thin film transistor TFT.

When an image signal is applied to the first electrode 128, an electric field is formed between the first electrode 128 and the second electrode 129, and the electric field is formed by the first and fourth alignment layers 132, 134, 162, and 164. The arrangement direction of the liquid crystal molecules of the arranged liquid crystal layer 170 is changed, and the transmittance of light passing through the liquid crystal layer 170 is changed by changing the arrangement direction of the liquid crystal molecules, thereby realizing an image.

As described above, in the liquid crystal display device 100 of the present invention, two layers of alignment films 132 and 134 and 162 and 164 are formed on the first substrate 110 and the second substrate 150, respectively. same.

FIG. 3 is a partially enlarged view of FIG. 2 and shows an outer region of the liquid crystal display device 100 bonded by the sealant 172. In this case, for convenience of explanation, only the substrates 110 and 150, the alignment layers 132, 134, 162, and 164, the liquid crystal layer 170, and the sealant 172 are illustrated in the drawings.

As shown in FIG. 3, a first alignment layer 132 and a second alignment layer 134 are formed on the first substrate 110, and a third alignment layer 162 and a fourth alignment layer 164 are formed on the second substrate 150. ) Is formed.

In the drawing, although the first alignment layer 132 and the third alignment layer 162 are formed directly on the first substrate 110 and the second substrate 150, respectively, referring to FIG. 2, the first alignment layer 132 is the first alignment layer 132. The protective layer 114 formed on the substrate 110, the first electrode 128 and the second electrode 129 are formed on the third alignment layer 162, and the black matrix 152 and the color filter layer 154 are formed. In addition, although not shown in the drawing, the third alignment layer 162 may be formed on the planarization layer formed on the black matrix 152 and the color filter layer 154.

The first alignment layer 132 and the third alignment layer 162 extend to the outer regions of the first substrate 110 and the second substrate 15, respectively, and a sealant 172 is formed on the upper alignment layer. 134) and the fourth alignment layer 164 are formed to be separated from the sealant 172 by a predetermined distance d1. At this time, the separation distance d1 is formed as small as possible, so that the sealant 172 does not overlap with the second alignment layer 134 and the fourth alignment layer 164, and the second alignment layer () is disposed in most areas of the display area DA. 134) and the fourth alignment layer 164 are preferably formed.

In this case, the first alignment layer 132 and the third alignment layer 162 are composed of first regions 132a, 162a and second regions 132b, 162b, respectively, and the first regions 132a, 162a are hydrophilic. In addition, the second regions 132b and 162b have hydrophobicity.

The first regions 132a and 162a of the first alignment layer 132 and the third alignment layer 162 are respectively formed in the central region of the first substrate 110 and the second substrate 150, that is, in regions corresponding to the display unit. The second regions 132b and 162b of the first alignment layer 132 and the third alignment layer 162 are formed along the outer edges of the first regions 132a and 162a, respectively.

That is, the first regions 132a and 162a of the first alignment layer 132 and the third alignment layer 162 are mainly formed on the display unit DA of the display device 100 and the second regions 132b and 162b are It is formed on the pad portion PA outside the display portion DA.

The sealant 172 is formed in the second regions 132b and 162b of the first alignment layer 132 and the third alignment layer 162, and the second alignment layer 134 and the fourth alignment layer 164 are respectively first. It is formed on the first regions 132a and 162a of the alignment layer 132 and the third alignment layer 162. In this case, the second alignment layer 134 and the fourth alignment layer 164 are formed to be aligned with the first regions 132a and 162a of the first alignment layer 132 and the third alignment layer 162, respectively. Although described later, the first regions 132a and 162a of the first alignment layer 132 and the third alignment layer 162 are formed to be hydrophilic, and thus the alignment material is formed when the second alignment layer 134 and the fourth alignment layer 164 are formed. It is applied only to the hydrophilic first regions 132a and 162a, but not to other regions. That is, the second alignment layer 134 and the fourth alignment layer 164 are self-aligned with the first regions 132a and 162a of the first alignment layer 132 and the third alignment layer 162, respectively, without separate patterning. ) To be patterned.

As described above, the reason for forming the alignment layer formed on the first substrate 110 and the second substrate 150 in a two-layer structure in the present invention can obtain the following effects.

In general, the alignment film is applied to the display area by a liquid coating material such as a spin coater (spin coater). The alignment material applied to the substrates 110 and 150 spreads over the entire substrates 110 and 150, and is dried to complete the alignment layer. However, the liquid oriented material is not accurately applied only to a desired area due to various reasons such as its own viscosity, limitation of accuracy of the coating device, misalignment of the substrate and the coating device, and defects of overcoating or uncoating occur.

4 is a view showing that a liquid alignment material is coated on a substrate by a general coating method.

As shown in FIG. 4, a display area DA is formed on the rectangular substrate 210, and the display area DA is also formed on the substrate 210 in a quadrangular shape that is almost the same shape as the substrate 210. . At this time, a sealant 272 is formed around the outer periphery of the display area DA to bond the two substrates.

When the liquid oriented material 239 is applied to the substrate 210 by the coating device, the liquid oriented material 239 spreads from the central region of the substrate 210 to the outer region, and the display area DA of the substrate 210 ) Is applied to the alignment material 239. At this time, the alignment film is preferably formed over the entire display area DA. For example, if an alignment layer is not formed in a portion of the display area DA, the initial alignment direction of the liquid crystal molecules cannot be controlled in this area, and the transmittance of light transmitted through the area cannot be controlled. . Therefore, an area in which the alignment layer is not formed in the display area DA becomes an area where light leaks and a bright point or a bright line occurs.

Of course, it is possible to block the leakage of light through this region by forming a black matrix in the region where the bright point or the bright line occurs, but in this case, there is a problem that the aperture ratio is lowered by the black matrix. Moreover, because the black matrix must be formed larger than the area where the actual light leaks due to adhesion errors or process errors, the formation of the black matrix is a major cause of deteriorating the aperture ratio of the liquid crystal display.

In particular, when the alignment material is applied, an area to which the alignment material is not applied is mainly formed outside the substrate, that is, near the sealant 272. Accordingly, a bright spot or a bright line due to the non-formation of the alignment film is mainly formed near the sealant 272. In the liquid crystal display device having such a defect, a bright line like a picture frame appears along the periphery of the screen.

Therefore, when applying the alignment material 239 on the substrate 210, if possible, the alignment material 239 should be applied as close as possible to the sealant 272 to minimize the area where the alignment film is not formed, so that bright spots and bright lines It is possible to minimize the generated area and prevent defects in which the aperture ratio is lowered.

However, due to the viscosity and surface tension of the liquid alignment material 239, when the alignment material 239 spreads to the outside of the substrate 210, the spreading speed toward the side region side of the alignment material 239 and the edge area Differences occur in the spread rate. In addition, it is impossible to accurately apply the alignment material 239 due to mechanical limitations of the coating device, misalignment of the substrate and the coating device, and coating tolerances.

Therefore, when the application of the alignment material 239 is finished, as shown in FIG. 4, the alignment material 239 is not formed into a completely rectangular shape such as an image of the display area DA, but has a rounded corner. The uncoated region and the alignment material 239 to which the alignment material 239 is not applied to the display area DA of the substrate 210 are spread on the outside of the display area DA. An overlap region in which the alignment material 239 overlaps the sealant 272 is formed.

The uncoated region of the alignment material 239 causes bright spots or bright lines to occur in the liquid crystal display device and causes a decrease in aperture ratio, and overlapping regions of the alignment material 239 and the sealant 272 fail to adhere to the liquid crystal display device. This is the cause.

5A and 5B are partially enlarged views of a liquid crystal display having a general structure formed by application of an alignment material.

As shown in FIG. 5A, when the alignment material 239 spreads outwardly of the display area DA, an insulating layer such as a protective layer of the first substrate 210 and an overcoat layer of the second substrate 250 A part of the sealant 272 to be formed is formed on the alignment films 232 and 262, or all of the sealant 272 is formed on the alignment films 232 and 262.

In general, the alignment films 232 and 262 composed of a polymer such as polyimide or polyamide have a large anchoring energy to constrain liquid crystal molecules, but the adhesion is an insulating layer such as a protective layer or an overcoat layer. Weak compared to. Accordingly, when the sealant 272 and the alignment layers 232 and 262 partially overlap or the whole overlaps, the adhesion force of the sealant 272 bonding the first substrate 210 and the second substrate 250 is reduced. , Due to the lowering of the bonding force, a bonding failure in which the first and second substrates 210 and 250 are separated even by a weak force occurs.

In order to prevent such a decrease in adhesion, the area in which the alignment material spreads is reduced so that the alignment material does not spread outwards of the display area DA, and the alignment material is applied only to the inside of the display area DA to form alignment films 232 and 262. And the sealant 272 may not overlap.

However, as illustrated in FIG. 5B, in the case of such a structure, the alignment layers 232 and 262 are formed to be spaced a predetermined distance d2 from the sealant 272. That is, an area in which alignment layers 232 and 262 are not formed along the inner circumference of the display area DA formed inside the sealant 272 occurs, and light leakage occurs through these areas to brighten the outer area of the display device. Frame failure occurs.

In addition, in order to prevent a frame defect, when forming a black matrix to block light leakage on the edge of the display device, an image is not displayed in this area, which causes a problem that the aperture ratio of the display device is lowered.

Referring to FIG. 3 again, in the present invention, in order to solve the problem of poor adhesion due to the alignment layer of the display device and the problem of defective frame and poor aperture ratio, the alignment layer is formed in a two-layer structure.

At this time, the top surface of the first substrate 110 and the second substrate 150, that is, the first alignment layer 132 and the third alignment layer 162 in direct contact with the first substrate 110 and the second substrate 150 are A material having good orientation regulating power and good adhesion to the sealant 172 is used. In addition, the second alignment layer 134 and the fourth alignment layer 164 formed on the first alignment layer 132 and the third alignment layer 162 and in direct contact with the liquid crystal layer have relatively poor adhesion, but the first alignment layer 132 ) And the third alignment layer 154 are made of a material having a larger orientation regulating force.

Therefore, the first alignment layer 132 and the third alignment layer 162 are formed to the outer edges of the first substrate 110 and the second substrate 150, so that the sealant 172 is the first alignment layer 132 and the third alignment layer. (162) Even if it is formed on the top, a decrease in bonding strength does not occur.

In addition, in the present invention, the second switching layer 134 and the fourth alignment layer 164 are formed on the first substrate 110 and the second substrate 150 in most of the areas of the display unit DA, respectively. In ), most of the liquid crystal layer 170 is in direct contact with the second alignment layer 134 and the fourth alignment layer 164, and only the liquid crystal layer 170 in the outer region of the display unit DA is the first alignment layer 132 and In contact with the third alignment layer 162.

Therefore, in most areas of the display unit DA, the light transmittance is controlled by the second alignment layer 134 and the fourth alignment layer 164, which have relatively strong alignment control forces, so that an image of good quality can be realized and the display unit DA ), the light transmittance is controlled by the first alignment layer 132 and the third alignment layer 162, which are relatively weak in orientation control, so the best quality image cannot be achieved, but even in this area, liquid crystal molecules are arranged according to the signal. Light leakage can be prevented.

As described above, in the present invention, since the alignment layer is formed in a two-layer structure of an upper alignment layer having a strong alignment control force and a lower alignment layer having a good alignment regulation force and bonding strength, adhesion defects due to a decrease in bonding force with the sealant 172 can be prevented. In addition, it is possible to prevent frame defects caused by light leakage into the border area. In addition, it is possible to effectively prevent the lowering of the aperture ratio caused by forming the black matrix to block light leakage in the border region.

As the second alignment layer 134 and the fourth alignment layer 164, an alignment material, for example, a polyimide-based polymer and a polyamide-based polymer may be used.

In addition, a polyamide-based polymer is mainly used as the first alignment layer 132 and the third alignment layer 162. In particular, the alignment materials of the first alignment layer 132 and the third alignment layer 162 may be made of a material in which an additive such as an epoxy group is added to the polyamide-based polymer. However, the additives of the alignment materials of the first alignment layer 132 and the third alignment layer 162 of the present invention are not limited to the epoxy group, but any material may be used if a photosensitive side chain can be formed on the polyamide-based polymer.

The epoxy group converts the hydrophobicity of the polyamide-based polymer to hydrophilicity when irradiated with light such as ultraviolet light, and forms a first linking film (crosslinking) with a sealant 172 made of an epoxy-based resin as light is irradiated. 132) and the third alignment layer 162 and the sealant 172 improve the bonding force.

In addition, the alignment materials of the first alignment layer 132 and the third alignment layer 162 may be configured by including a crosslinking agent and a photosensitive additive in a polyamide-based polymer. At this time, as the crosslinking agent, any material can be used as long as it can form a crosslink by heat or light. For example, additives comprising hydroxyl groups can be used as the crosslinking agent.

When irradiated with light such as ultraviolet light or heat is applied to the crosslinking agent, cross linking is formed between the crosslinking agent and the sealant 172 to form the first alignment layer 132 and the third alignment layer 162. The bonding force between the sealants 172 is improved. In addition, as light is irradiated to the photosensitive additive, the hydrophobicity of the polyamide-based polymer is converted to hydrophilicity.

In particular, the cross-linking agent can improve cross-linking between the polyamide-based polymer and the liquid crystal molecules, thereby improving the alignment control power of the first alignment layer 132 and the third alignment layer 162. Therefore, it is possible to control the liquid crystal molecules located near the sealant 172 in a desired direction to prevent light leakage in this region and display an image with better image quality.

As described above, in the present invention, the image of the display unit DA is formed by forming the alignment layer into a two-layer structure of a first alignment layer having a relatively high bonding force and a low alignment regulation force and a second alignment layer having a relatively high alignment regulation force. It is possible to prevent deterioration of the quality, improve adhesion with the sealant 172 and prevent frame defects caused by light leakage through the periphery of the sealant 172.

6 is a flowchart illustrating a method of manufacturing a liquid crystal display device according to the present invention, and a method of manufacturing the liquid crystal display device according to the present invention will be described in detail with reference to FIGS. 2 and 6.

As illustrated in FIG. 6, a plurality of gate lines GL and data lines DL defining a plurality of pixels are formed on the first substrate 110 by a TFT process, and the gate lines ( GL) and a thin film transistor TFT that is a driving element connected to the data line DL are formed (S101). In addition, the first electrode 128 and the second electrode 129 for applying an image signal are formed by being connected to the drain electrode 126 of the thin film transistor (TFT) through the TFT process.

The gate line GL and data line DL, the gate electrode 122 and the source electrode 125 and the drain electrode 126, the first electrode 128 and the second electrode 129 of the thin film transistor are It may be formed by a photolithography process using a mask. In addition, the gate insulating layer 112 and the semiconductor layer 124 may be formed by a chemical vapor deposition (CVD) method.

In addition, a black matrix 152 and R, G, and B color filter layers 154 that block light from being transmitted to the non-image area by the CF process are formed on the second substrate 150 (S104). The black matrix 152 may be formed by laminating and etching a metal oxide such as CrO or CrOx, or may be formed by applying and etching black resin. Also, the R, G, and B color filter layers 154 may be formed by laminating and patterning a color resin made of a pigment or the like.

Subsequently, a first alignment layer 132 and a second alignment layer 134 thereon are formed on the first substrate 110 and the first alignment layer 132 and the second alignment layer 134 are subjected to alignment treatment to improve alignment control power. Grant (S103). In addition, the third alignment layer 162 and the fourth alignment layer 164 thereon are formed on the second substrate 150 and the third alignment layer 162 and the fourth alignment layer 164 are subjected to alignment treatment to improve alignment control power. Grant (S104).

Thereafter, a sealant 172 is printed on the outer portion of the first substrate 110 and liquid crystal is dropped onto the first substrate 110 surrounded by the sealant 172 to form a liquid crystal layer 170 (S105, S106). In this case, the sealant 172 may be printed on the second substrate 150 instead of the first substrate 110 and the liquid crystal may be dropped on the second substrate 150.

Subsequently, by applying pressure in a state where the first substrate 110 and the second substrate 150 are aligned, the liquid crystal is adhered to the first substrate 110 and the second substrate 150 by the sealant 172. The display device can be completed (S107).

Although not shown in the drawings, when a plurality of the liquid crystal display devices are formed in units of a mother substrate, a plurality of liquid crystal display devices may be separated by cutting the bonded mother substrate after bonding of the mother substrate.

Meanwhile, formation of the liquid crystal layer 170 may be performed after bonding the first substrate 110 and the second substrate 150. That is, after the sealant 172 is printed, an injection hole through which liquid crystal is injected is formed, and after the first substrate 110 and the second substrate 150 are bonded, the liquid crystal is first and second liquid crystals 110 and second through the injection hole. The liquid crystal layer 170 may be formed by injecting between the substrates 150. In this way, when the liquid crystal is injected by forming the injection hole, the liquid crystal display device is completed by sealing the injection hole.

As described above, in the liquid crystal display device according to the present invention, the alignment layers 132,134,162,164 of the two layers are formed on the first substrate 110 and the second substrate 150, respectively, and the alignment control force is applied to the liquid crystal molecules of the liquid crystal layer 170. In addition to providing and improving the bonding strength with the sealant 172, a method of forming an alignment layer having a two-layer structure will be described in detail with reference to the accompanying drawings.

7 is a flowchart showing a method for forming an alignment film according to the present invention, and FIGS. 8A to 8E are views showing an actual method for forming an alignment film. At this time, the first alignment layer 132 and the second alignment layer 134 formed on the first substrate 110 and the third alignment layer 162 and the fourth alignment layer 164 formed on the second substrate 150 are the same method. Since it is formed by, only the method of forming the first alignment layer 132 and the second alignment layer 134 on the first substrate 110 will be described below.

As shown in FIGS. 7 and 8A, first, a first alignment material composed of a liquid polyamide-based polymer to which an additive such as epoxy is added or a liquid polyamide-based polymer to which a crosslinking agent is added is prepared, and then spin coating, etc. The first alignment material prepared by the coating method is coated on the first substrate 110 and cured to form a first alignment layer 132 (S201).

Meanwhile, the first alignment material may be formed by various methods, not only by a specific method such as spin coating. For example, the first alignment material may be applied on the first substrate 110 by various methods such as screen printing and dispensing. The first alignment material coated on the first substrate 110 spreads to the first substrate 110 and the first alignment material is applied on the substrate.

Subsequently, as shown in FIGS. 7 and 8B, in a state in which the outer region of the first alignment layer 132 is blocked by arranging a mask 180 of a rectangular frame having a width set on the first alignment layer 132. The first alignment layer 132 is irradiated with ultraviolet light (S202).

The first alignment layer 132 has hydrophobicity as a whole, and the surface of the first alignment layer 132 is modified by irradiation of the ultraviolet rays, thereby converting the hydrophobicity of the region irradiated with ultraviolet rays to hydrophilicity. That is, as shown in FIG. 8C, the first alignment layer 132 is irradiated with the ultraviolet rays, and the width is set along the outer periphery of the hydrophilic first region 132a and the first region 132a (mask 180 ), and the second region 132b of hydrophobicity.

Thereafter, as shown in FIGS. 7 and 8D, a second alignment material made of a polyimide-based polymer or a polyamide-based polymer is coated on the first alignment layer 132 by a method such as spin coating (S203).

Since the first alignment layer 132 is composed of a hydrophilic first region 132a and a hydrophobic second region 132b, when a liquid second alignment material is applied on the first alignment layer 132, the first alignment layer 132 is hydrophilic. The liquid second alignment material is applied only to the area 132a, and the second alignment material does not remain in the second area 132b. Therefore, in the present invention, the second alignment material is formed by self-aligning with the first region 132a of the first alignment layer 132 without a separate patterning process.

Thereafter, a second alignment layer 134 self-aligned is formed on the first region 132a of the first alignment layer 132 by applying heat to the coated second alignment material or irradiating with ultraviolet rays (S204). ).

Subsequently, as shown in FIGS. 7 and 8E, a rubbing roll 182 in which a rubbing cloth 184 is fitted over the first substrate 110 on which the first alignment layer 132 and the second switching layer 134 are formed. After positioning and contacting, the second region 132b and the second alignment layer of the first alignment layer 132 are moved by moving the rubbing roll 182 in a predetermined direction or by moving the first substrate 110 in a predetermined direction. The top surface of (134) is oriented (S205).

Meanwhile, the alignment treatment of the first alignment layer 132 and the second alignment layer 134 may be performed by irradiating light such as ultraviolet rays, not only by rubbing.

The second region 132b and the second alignment layer 134 of the first alignment layer 132 by rubbing the second alignment layer 132b and the second alignment layer 134 of the first alignment layer 132 have a set direction, that is, Continuous micro grooves are formed along the rubbing direction, and these micro grooves provide alignment control force to the liquid crystal molecules.

As described above, in the present invention, by forming a first alignment layer 132 and irradiating ultraviolet rays using a mask to the first alignment layer 132, a first region 132a on which a second alignment layer 134 is disposed, ). It is possible to form the second alignment layer 134 having a specific shape without a separate patterning process. At this time, since the patterning of the second alignment layer 134 is determined by the irradiation region of ultraviolet light, or, more precisely, the opening area of the mask, the second alignment layer 134 can control the formation area by adjusting the opening area of the mask.

In the present invention, since the liquid second alignment material is applied to the first alignment layer 132 only in the first hydrophilic region 132a and not at all in the hydrophobic second region, the viscosity of the liquid alignment layer, limitations and processes of printing technology There is no application error due to errors.

Accordingly, in the present invention, since the second alignment layer 134 can be accurately formed at a desired position at all times, the second alignment layer 134 having relatively weak adhesive strength extends to the lower portion of the sealant 172, and the adhesion force of the liquid crystal display device is extended. It is possible to prevent the weakening.

Further, in the present invention, since the second alignment layer 134 can be accurately formed at a desired position at all times, the second alignment layer 134 having a relatively strong alignment control force can be formed as close as possible to the sealant 172 without overlapping. Since (d1<d2), the second alignment layer 134 can be formed inside the sealant 172, that is, in most areas of the display unit, thereby improving the image quality displayed through the entire display unit.

Although many matters are specifically described in the above description, this should be interpreted as an example of a preferred embodiment rather than limiting the scope of the invention. Therefore, the invention should not be determined by the described embodiments, but should be determined by equivalents to the claims and claims.

110,150: substrate 132,134,162,164: alignment film
170: liquid crystal layer 172: sealant
180: Mask 182: Loving Roll
184: Loving cloth

Claims (15)

A first alignment layer formed on the substrate;
Comprising a second alignment layer formed on the first alignment layer,
The first alignment layer has an adhesive force greater than that of the second alignment layer, and the second alignment layer has an alignment control force greater than that of the first alignment layer. The alignment layer of claim 1, wherein the second alignment layer is made of a polyimide-based polymer or a polyamide-based polymer. The alignment layer of claim 1, wherein the first alignment layer comprises a polyamide-based polymer containing an additive that forms a photosensitive side chain. The alignment film of claim 1, wherein the first alignment film is made of a polyamide-based polymer to which a crosslinking agent is added. The alignment layer of claim 1, wherein the first alignment layer comprises a first hydrophilic region and a second hydrophobic region formed outside the first region. The alignment layer of claim 5, wherein the second alignment layer is disposed on the first region of the first alignment layer. The alignment layer of claim 5, wherein the second alignment layer is self-aligned with the first region of the first alignment layer. A first substrate and a second substrate including a display area and a pad area;
A first alignment layer formed in the display area and the pad area of the first substrate;
A second alignment layer formed on the display area on the first alignment layer;
A third alignment layer formed on the display area and the pad area of the second substrate;
A fourth alignment layer formed on the display area on the third alignment layer;
A liquid crystal layer disposed between the first substrate and the second substrate; And
It is disposed between the first alignment layer and the third alignment layer and includes a sealant for bonding the first substrate and the second substrate.
The first alignment layer and the third alignment layer have greater adhesion than the second alignment layer and the fourth alignment layer, respectively, and the second alignment layer and the fourth alignment layer are respectively larger than the first alignment layer and the third alignment layer. Regulatory display. The display device of claim 1, wherein the first alignment layer and the third alignment layer each include a hydrophilic first region and a second hydrophobic region formed outside the first region. 10. The method of claim 9, wherein the second alignment layer and the fourth alignment layer are disposed on the first region of the first alignment layer and the third alignment layer, respectively, and the sealant is the second alignment layer and the third alignment layer. A display device disposed over the area. The display device of claim 10, wherein the second alignment layer and the fourth alignment layer are spaced apart from the sealant. Forming a hydrophobic first alignment layer formed on the substrate;
Converting the hydrophilicity of the irradiated area by irradiating ultraviolet rays to the set area of the first alignment layer;
Forming a second alignment layer self-aligned with a hydrophilic region on the first alignment layer by applying a liquid alignment material on the first alignment layer; And
A method of forming an alignment layer comprising the steps of aligning the first alignment layer and the first alignment layer. The method of claim 12, wherein the forming of the first alignment layer comprises applying an alignment material composed of a liquid polyamide-based polymer to which an additive or a crosslinking agent to form a photosensitive side chain is added to a substrate. The method of claim 12, wherein irradiating the first alignment layer with ultraviolet rays.
Placing a mask on the first alignment layer; And
And irradiating ultraviolet rays while blocking the outer circumference of the first alignment layer by the mask. The method of claim 12, wherein the forming of the second alignment layer comprises curing the alignment material applied on the first region of the first alignment layer.

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