KR100864920B1 - Liquid Crystal Display Device - Google Patents

Abstract

The present invention is a first substrate and a second substrate; A liquid crystal layer formed between the first substrate and the second substrate; A plurality of gate lines and data lines formed vertically and horizontally on the first substrate to define pixel regions; A thin film transistor formed at an intersection point of the gate line and the data line; A pixel electrode connected to the thin film transistor and formed in the pixel area; A gate insulating film and a protective film formed in an area where the gate line, data line, and thin film transistor are formed; A common electrode formed on the second substrate; And a dielectric structure formed on the common electrode to correspond to the pixel region and the region where the gate line and the data line overlap with each other by a length equal to the distance between the first substrate and the second substrate. to provide.

Cell gap, dielectric protrusion

Description

Liquid Crystal Display Device

1A is a plan view of a unit pixel of a conventional liquid crystal display device.

FIG. 1B is a cross-sectional view of the A-A line of FIG. 1A.

2 is a plan view of a liquid crystal display device according to an exemplary embodiment of the present invention.

3A to 3C are cross-sectional views according to an embodiment of the B-B line of FIG. 2.

4A and 4B and 5A to 5D are plan views illustrating the shape of the dielectric structure according to the present invention.

6A and 6B are cross-sectional views of a lower substrate for a liquid crystal display device according to another exemplary embodiment of the present invention.

7A and 7B are cross-sectional views of a lower substrate for a liquid crystal display device according to another exemplary embodiment of the present invention.

<Description of Signs of Major Parts of Drawing>

12, 120: gate line 14, 140: data line

16, 160: gate insulating film 18, 180: protective film

26, 260: source electrode 28, 280: drain electrode

30, 300: pixel electrode 500a, 500: dielectric structure

600: auxiliary electrode 310: electric field induction window

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a stable texture and a uniform cell gap.

In general, the liquid crystal display device includes a lower substrate and an upper substrate facing each other at a predetermined interval, and a liquid crystal layer formed between the two substrates, and drives the liquid crystal layer by an electric field formed between the two substrates. It is an element which displays an image by adjusting the light transmittance through the driven liquid crystal layer.

Among the liquid crystal display devices, the vertical alignment mode liquid crystal display device uses a negative liquid crystal having a negative dielectric anisotropy. When no voltage is applied, the long axis direction of the liquid crystal molecules is perpendicular to the alignment layer plane. When the voltage is applied, the liquid crystal molecules are displayed at an angle by controlling the transmittance of light using the property of being oriented obliquely by the electric field.

Meanwhile, in the vertical alignment mode liquid crystal display device, in order to implement a wide viewing angle, it is necessary to compensate the viewing angle by aligning the liquid crystal molecules in various directions when an electric field is applied.

As a method of aligning the liquid crystal molecules in various directions as described above, a method of positioning the directors of the liquid crystal molecules in a desired direction by forming a dielectric protrusion (Rib) on the substrate and distorting the electric field applied to the liquid crystal layer has been proposed. It demonstrates with reference to drawings.

1A is a plan view of a unit pixel of a conventional liquid crystal display device, and FIG. 1B is a cross-sectional view of the A-A line of FIG. 1A.

1A and 1B, a plurality of gate lines 12 and data lines 14 are formed on the first substrate 10 vertically and horizontally to define a pixel area. At the intersection of the gate line 12 and the data line 14, the gate electrode 22, the gate insulating layer 16, the semiconductor layer 24, the ohmic contact layer, the source / drain electrodes 26 and 28, and A thin film transistor 20 formed of the passivation layer 18 is formed, and a pixel electrode 30 electrically connected to the drain electrode 28 is formed in the pixel region.

A light blocking layer 42 is formed on the second substrate 40 to block light leaking from the gate line 12, the data line 14, and the thin film transistor 20. The light blocking layer 42 is formed on the second substrate 40. The color filter layer 44 is formed on the common filter 46, and the common electrode 46 is formed on it. A dielectric protrusion 48 is formed on the common electrode 46 to distort the electric field.

In addition, a spacer 50 is formed between the first substrate 10 and the second substrate 40 to maintain a constant gap between the two substrates, that is, a cell gap. This is commonly referred to as a ball spacer, which is formed by mixing and dispersing the spacer 50 in a solvent on the first substrate 10 in the manufacture of the liquid crystal display device (wet dispersion method), or around the first substrate. It is formed by a method of keeping the ground state and charging the spacers to spread them (dry dispersion method).                         

However, the liquid crystal display device having the above structure causes the electric field to be distorted not only in the dielectric protrusion 48 formed on the common electrode 46, but also around the spacer 50. As a result, a foreground line may be generated between the dielectric protrusion 48 and the spacer 50, such that the texture becomes unstable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid crystal display device having a stable texture by using a dielectric protrusion formed on a common electrode as a spacer without separately forming a spacer for maintaining a cell gap. do.

In addition, an object of the present invention is to provide a liquid crystal display device which can easily control a cell gap between both substrates and maintain a uniform cell gap.

The present invention to achieve the above object, the first substrate and the second substrate; A liquid crystal layer formed between the first substrate and the second substrate; A plurality of gate lines and data lines formed vertically and horizontally on the first substrate to define pixel regions; A thin film transistor formed at an intersection point of the gate line and the data line; A pixel electrode connected to the thin film transistor and formed in the pixel area; A gate insulating film and a protective film formed in an area where the gate line, data line, and thin film transistor are formed; A common electrode formed on the second substrate; And a dielectric structure formed on the common electrode to correspond to the pixel region and the region where the gate line and the data line overlap with each other by a length equal to the distance between the first substrate and the second substrate. to provide.

That is, the liquid crystal display device according to the present invention forms a dielectric structure formed on the common electrode with a gap between the first substrate and the second substrate, that is, the length of the cell gap, in order to distort the electric field to implement the multidomain effect. The structure also serves as a spacer.

More specifically, the dielectric structure is formed in a region where the pixel region, the gate line and the data line overlap, and the dielectric structure formed in the pixel region distorts the electric field when an electric field is applied, and the gate line and the data line overlap. The dielectric structure formed in the region to be served serves to maintain the gap between the two substrates.

On the other hand, when the dielectric structure is formed with the length of the cell gap, the liquid crystal injection may not be performed smoothly due to the dielectric structure in the process of injecting the liquid crystal after bonding the first substrate and the second substrate, or in the process of bonding the liquid crystal after dropping. In view of this, the gate insulating film and / or the protective film are not formed in the predetermined pixel region, thereby providing a space in which the liquid crystal can move smoothly.

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

First embodiment

2 is a plan view of a liquid crystal display device according to a first embodiment of the present invention, and FIGS. 3A to 3C are cross-sectional views according to an embodiment of the B-B line of FIG. 2.

As shown in FIGS. 2 and 3A to 3C, first, the first substrate 100 and the second substrate 400 are disposed to face each other at a predetermined interval in the liquid crystal display according to the first embodiment of the present invention. .

In addition, a plurality of gate lines 120 and data lines 140 are formed on the first substrate 100 vertically and horizontally to define pixel regions, and the gate lines 120 and the data lines 140 are formed on the first substrate 100. At the intersection point, the gate electrode 220, the gate insulating film 160, the semiconductor layer 240, the ohmic contact layer (not shown), the source and drain electrodes 260 and 280, and the passivation layer 180 are sequentially stacked. The thin film transistor 200 is formed.

The pixel electrode 300 is connected to the drain electrode 280 of the thin film transistor 200 and formed in the pixel region.

In this case, the gate insulating layer 160 and the passivation layer 180 are formed only in an area in which the gate line 120, the data line 140, and the thin film transistor 200 are formed, as shown in FIG. 3A. It may not be formed in the 'region'.

3B, the gate insulating layer 160 and the passivation layer 180 are formed in the region where the gate line 120, the data line 140, and the thin film transistor 200 are formed. Only the gate insulating layer 160 may be formed, and as shown in FIG. 3C, the gate insulating layer 160 and the passivation layer 180 are formed in the region where the gate line 120, the data line 140, and the thin film transistor 200 are formed. Only the passivation layer 180 may be formed in other areas.

As such, the gate insulating layer 160 and / or the passivation layer 180 may be formed in a region other than the region where the gate line 120, the data line 140, and the thin film transistor 200 are formed. Since the pixel electrode 300 formed in the region has a recessed structure, the liquid crystal moves more smoothly when the liquid crystal is injected, and the liquid crystal is uniformly distributed without overdistributing to any specific region, so that the cell gap is uniform throughout the substrate. Will remain stable at.

In addition, although not shown in the drawing, the gate insulating film 160 and / or the passivation layer 180 may be formed thinner in the 'fall' area than other areas.

The gate insulating layer 120 and the passivation layer may be formed of an organic insulating layer such as BCB (BenzoCycloButene) or an acrylic resin, or an inorganic insulating layer such as SiNx or SiOx, and the pixel electrode 300 for high opening ratio. ) Is formed to overlap the data line 140, it is preferable to form an organic insulating film such as BCB to eliminate electrical interference between the two (300, 140).

In addition, the pixel electrode 300 may be made of indium tin oxide (ITO) or indium zinc oxide (IZO).

In addition, the light blocking layer 420, the color filter layer 440, and the common electrode 460 are sequentially formed on the second substrate 400. The color filter layer 440 protects the color filter layer 440 and flattens the substrate. ) And the common electrode 460 may be further formed overcoat layer.

In addition, dielectric structures 500a and 500 are formed on the common electrode 460.

In this case, the dielectric structures 500a and 500 are formed to have a length equal to the interval Δx between the first substrate 100 and the second substrate 400, and are formed in the pixel area (notation reference numerals). 500 and the gate line 120 and the data line 140 are also formed in the overlapping region (reference numeral 500a).

Accordingly, the dielectric structure 500 formed in the pixel region distorts an electric field to implement a multi-domain effect, and the dielectric structure 500a formed in the region where the gate line 120 and the data line 140 overlap each other maintains a cell gap. It plays a role.

As described above, the dielectric structure 500a formed in the region where the gate line and the data line overlap with each other serves to maintain the cell gap does not need to be formed per pixel, but at least one of the dielectric structures 500a is formed per pixel. Is preferred.

Accordingly, the cell gap can be easily controlled by the dielectric structure 500a, and the density of the cell gap can be easily controlled by forming one per four pixels.

In addition, the dielectric structure 500a formed in the region where the gate line and the data line overlap and the dielectric structure 500 formed in the pixel region may be formed to be connected to each other as shown in FIG. 4A, or not to be connected as shown in FIG. 4B. It may be formed.

In addition, the dielectric structures 500a and 500 may be formed in various shapes as shown in FIGS. 5A to 5D, but are not limited thereto. The dielectric structures 500a and 500 may be formed by changing the number of predetermined domains.

Such dielectric structures 500a and 500 preferably have a dielectric constant equal to or smaller than that of the liquid crystal, preferably 3 or less. In addition, the dielectric structures 500a and 500 are preferably made of a photosensitive material, more preferably made of acrylic resin (photoacrylate) or BCB (BenzoCycloButene).

In addition, a liquid crystal layer (not shown) is formed between the first substrate 100 and the second substrate 400, which is preferably formed by including a chiral dopant in the VA (Vertical Alignment) liquid crystal.

In addition, although not shown in the drawing, an alignment layer may be formed on the entire surface of at least one of the first substrate 100 and the second substrate 400.

The alignment layer may be formed by rubbing orientation treatment using a material such as a polyamide or polyimide compound, polyvinylalcohol (PVA), polyamic acid, or the like, or may be formed without orientation treatment. have.

In addition, the photoreaction may be formed using a photoreactive material such as PVCN (polyvinylcinnamate), PSCN (polysiloxanecinnamate), or CelCN (cellulosecinnamate) -based compound, or may be formed without orientation treatment. The light alignment treatment simultaneously determines the pretilt angle and the alignment direction by at least one light irradiation, wherein the light irradiation preferably uses light in the ultraviolet region. Any of unpolarized light, linearly polarized light, and partially polarized light may be used.

In addition, a retardation film may be formed on an outer surface of at least one of the first substrate 100 and the second substrate 400. The retardation film compensates for the viewing angle in the direction perpendicular to the substrate and the direction of the viewing angle change, thereby widening the region without gray inversion, and increasing the contrast ratio in the oblique direction. Although it may be formed as a negative uniaxial film or a negative biaxial film having two optical axes, a negative biaxial film is more preferable in terms of wide viewing angle.

The retardation film may be formed integrally with the polarizer.

Second embodiment

6A and 6B are cross-sectional views of a lower substrate for a liquid crystal display device according to a second embodiment of the present invention, which corresponds to the B-B line of FIG.

As shown in FIGS. 6A and 6B, the liquid crystal display according to the second exemplary embodiment of the present invention is provided on the lower substrate 100 so as to be surrounded by a layer different from the pixel electrode 300 so as to surround the pixel electrode 300. Except that the electrode 600 is formed, the structure of the upper substrate and the like is the same as the first embodiment described above. Therefore, the upper substrate is not shown, and given the same reference numerals.

In the liquid crystal display device according to the second exemplary embodiment of the present invention, the auxiliary electrode 600 is formed around the pixel electrode 300 to enhance electric field distortion in the region, thereby driving the liquid crystal more stably.

In this case, the auxiliary electrode 600 is formed only on the same layer as the gate line 120 in the drawing, but may also be formed on the same layer as the data line 140. In addition, although only the structure in which the gate insulating layer 160 (FIG. 6A) and the passivation layer 180 (FIG. 6B) are formed in the 'ga' region is shown in FIG. 3A, neither may be formed as shown in FIG. 3A.

In addition, the auxiliary electrode 600 may be formed to overlap a predetermined portion with the pixel electrode 300 or may not be overlapped.

The auxiliary electrode 600 is connected to the common electrode 460 of the second substrate 400 and is formed of indium tin oxide (ITO), Al, Mo, Cr, Ta, Ti, Cu, or an Al alloy. Can be.

Third embodiment

7A and 7B are cross-sectional views of a lower substrate for a liquid crystal display device according to a third embodiment of the present invention, which corresponds to the B-B line of FIG.

As shown in FIGS. 7A and 7B, in the liquid crystal display according to the third exemplary embodiment, an electric field induction window 310 is formed inside the pixel electrode 300, and the auxiliary electrode 600 is formed in a region corresponding thereto. ) Is the same as the second embodiment described above except that Therefore, the same reference numerals are given.

On the other hand, it is also possible to form only the electric field induction window 310, without forming the auxiliary electrode 600.

As such, the electric field induction window 310 or the auxiliary electrode 600 formed inside the pixel electrode 300 may be easily changed by those skilled in the art.

In the liquid crystal display device according to the present invention having the above structure, a stable texture can be secured by using a dielectric protrusion formed on the common electrode as a spacer.

In addition, the electric field distortion effect and the cell gap maintenance effect can be simultaneously realized by one process, thereby reducing the manufacturing process.                     

In addition, it is possible to control the density of the dielectric protrusions, thereby easily controlling the cell gap, and maintaining the uniform cell gap throughout the substrate.

Claims (13)

A first substrate and a second substrate; A liquid crystal layer formed between the first substrate and the second substrate; A plurality of gate lines and data lines formed vertically and horizontally on the first substrate to define pixel regions; A thin film transistor formed at an intersection point of the gate line and the data line; A pixel electrode connected to the thin film transistor and formed in the pixel area; A gate insulating film and a protective film formed in an area where the gate line, data line, and thin film transistor are formed; A common electrode formed on the second substrate; And A dielectric structure formed on the common electrode to correspond to the pixel region and the region where the gate line and the data line overlap with each other by the length of the gap between the first substrate and the second substrate; And regions other than regions where lines and thin film transistors are formed are non-formed regions of the gate insulating film and the protective film. delete The method of claim 1, And an auxiliary electrode formed on a layer different from the pixel electrode so as to surround the pixel electrode. The method of claim 1, And a field induction window formed in the pixel electrode. The method of claim 4, wherein And an auxiliary electrode formed on a layer different from the pixel electrode, surrounding the pixel electrode, and formed in an area corresponding to the electric field induction window. The method according to claim 3 or 5, And the auxiliary electrode is formed on the same layer as the gate line or the data line. The method according to claim 3 or 5, The auxiliary electrode is made of any one material selected from the group consisting of indium tin oxide (ITO), Al, Mo, Cr, Ta, Ti, Cu or Al alloy. The method of claim 1, And a dielectric structure formed to correspond to a region where the gate line and the data line overlap each other, and a dielectric structure formed in the pixel region. The method of claim 1, And a dielectric structure formed to correspond to a region where the gate line and the data line overlap each other, and a dielectric structure formed in the pixel region is not connected to each other. The method of claim 1, The liquid crystal of the liquid crystal layer is a liquid crystal display device, characterized in that the chiral dopant is included in the vertical alignment liquid crystal (VA). The method of claim 1, And an alignment layer formed on at least one of the first substrate and the second substrate, wherein the alignment layer is oriented or not. delete delete

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