KR20070025150A - In-plane-switching mode liquid crystal display device and the fabrication method thereof - Google Patents

Abstract

An in-plane switching mode LCD(Liquid Crystal Display) and a method of manufacturing the LCD are provided to block light leakage generated at the sides of electrodes in the LCD using a black matrix. An in-plane switching mode LCD includes a first substrate, a second substrate, a black matrix(131), and a liquid crystal layer. The first substrate includes a plurality of first electrodes(124) and a plurality of second electrodes(117). The first electrodes and the second electrodes are alternately arranged in a pixel region. The second substrate is arranged opposite to the first substrate. The black matrix is formed on the second substrate in an asymmetrical structure corresponding to the first electrodes or the second electrodes. The liquid crystal layer is interposed between the first and second substrates.

Description

Transverse electric field type liquid crystal display device and its manufacturing method {In-Plane-Switching mode Liquid Crystal Display Device and the fabrication method

1 is a plan view showing the structure of a two-domain transverse electric field type liquid crystal display device according to the prior art.

FIG. 2 is a voltage distribution diagram of a transverse electric field type liquid crystal display device on the line II ′ of FIG. 1.

3A and 3B are plan views of a transverse electric field type liquid crystal display device with and without voltage applied thereto.

3C is a sectional view showing an electrode step.

4 is a plan view showing the structure of a transverse electric field type liquid crystal display device according to one embodiment according to the present invention;

5 is a cross-sectional view of a transverse electric field type liquid crystal display device on the line II-II 'of FIG. 4;

6 shows a pattern of a black matrix according to the invention.

7A-7C schematically illustrate a portion of a black matrix according to the present invention.

<Description of Signs of Major Parts of Drawings>

101: array substrate 102: color filter substrate

112: gate wiring 115: data wiring

113: gate insulating film 116: protective film

117: pixel electrode 124: common electrode

131: black matrix 132: color filter layer

133: overcoat layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device (LCD), and more particularly to a transverse electric field type liquid crystal display device.

BACKGROUND ART Liquid crystal display devices, which have recently been in the spotlight as flat panel display devices, have been actively studied because of their high contrast ratio, suitable for gray scale display and moving image display, and low power consumption.

In particular, it can be manufactured with a thin thickness so that it can be used as an ultra-thin display device such as a wall-mounted TV in the future, and is light in weight and consumes significantly less power than a CRT CRT. It is being used as a next generation display device. In addition, since it is manufactured as a small panel and used as a mobile phone display, its use is various.

Such a liquid crystal display device has a variety of modes depending on the nature of the liquid crystal and the structure of the pattern.

Specifically, the TN mode (Twisted Nematic Mode) for arranging the liquid crystal directors to be twisted by 90 ° and then applying a voltage to the liquid crystal directors, and dividing one pixel into several domains to change the viewing angle of each domain to change the wide viewing angle. Multi-domain mode to implement, OCB mode (Optically Compensated Birefringence Mode) to compensate the phase change of light according to the direction of light by attaching the compensation film to the outer peripheral surface of the substrate, and two on one substrate In-Plane Switching Mode, which forms an electrode so that the directors of the liquid crystal are twisted in parallel planes of the alignment layer, and VA mode, in which the long axis of the liquid crystal molecules is vertically aligned with the alignment layer plane by using a negative liquid crystal and a vertical alignment layer. (Vertical Alignment), etc.

Among these, the transverse electric field type liquid crystal display device is usually composed of a color filter substrate and an array substrate disposed opposite to each other and having a liquid crystal layer therebetween.

That is, the color filter substrate is formed with a black matrix for preventing light leakage and a color filter layer of R, G, and B for implementing colors on the black matrix.

The array substrate includes gate wirings and data wirings defining unit pixels, switching elements formed at intersections of the gate wirings and data wirings, and a common electrode and a pixel electrode alternately crossing each other to generate a transverse electric field. .

Hereinafter, a transverse electric field type liquid crystal display device according to the prior art will be described in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing the structure of a two-domain transverse electric field liquid crystal display according to the prior art, and FIG. 2 is a voltage distribution diagram of a transverse electric field liquid crystal display on the line II ′ of FIG. 1.

Hereinafter, the array substrate of the transverse electric field type liquid crystal display device will be mainly described.

Specifically, as shown in FIG. 1, the array substrate is arranged and bent in a direction perpendicular to the gate wiring 12 to define the pixel region and the gate wiring 12 arranged in one direction on the substrate. A data line 15 having a structure, a thin film transistor TFT disposed at an intersection of the gate line 12 and the data line 15, and a common line disposed in the pixel to be parallel to the gate line 12. A plurality of common electrodes 24 having a structure which is branched and folded from the common wiring 25, and a thin film transistor TFT connected to the common electrode 24 between the common electrodes 24. A plurality of pixel electrodes 17 having a parallel bending structure and a capacitor electrode 26 extending from the pixel electrode 17 and overlapping the upper portion of the common wiring 25 are provided.

A gate insulating film (not shown) is further provided on the front surface including the gate wiring 12, and a protective film (not shown) is further provided on the front surface including the data wiring 15.

In this case, the common wiring 25 and the common electrode 24 are integrally formed, and the gate electrodes of the gate wiring 12 and the TFT are also integrally formed. The common wiring 25 and the common electrode 24 are also integrally formed. The electrode 24, the gate wiring 12, and the gate electrode are formed collectively in the same layer using a low resistance metal. However, the common electrode at the edge of the pixel among the common electrodes may be formed to overlap the data line to block light leakage generated at the data line.

In addition, the pixel electrode 17 may cross the common electrode 24 by using a transparent conductive metal having a relatively high transmittance of light such as indium-tin-oxide (ITO) as a material. It is formed in a plurality of branches so as to contact the drain electrode of the thin film transistor to receive a voltage.

Here, although the common electrode 24 and the pixel electrode 17 may cross each other in a straight line shape, as shown in FIG. 1, the common electrode 24 and the pixel electrode 17 may be formed in a zigzag form to arrange the liquid crystals in two directions. . In this way, the viewing angle is improved by dividing the domain in each pixel into two regions. The structure of the transverse electric field type liquid crystal display device forming a two-domain is called an S-IPS (Super-IPS) structure.

In addition, the capacitor electrode 26 overlapping the upper portion of the common wiring 25 forms a storage capacitor together with a gate insulating layer and a protective layer interposed therebetween to fill the liquid crystal layer in the turn-off period of the thin film transistor. Maintains voltage to prevent deterioration of image quality by parasitic capacitance

As described above, in the configured transverse electric field type liquid crystal display device, as shown in FIG. 2, when 5 V is applied to the common electrode 24 and 0 V is applied to the pixel electrode 17, the equipotential surface is directly connected to the electrode. In parallel, the equipotential plane is distributed close to the vertical in the region between the two electrodes.

Therefore, since the direction of the electric field is perpendicular to the equipotential surface, a horizontal electric field rather than a vertical electric field is present between the common electrode 24 and the pixel electrode 17, a vertical electric field rather than a horizontal electric field on each electrode, and horizontal and vertical electric fields at the electrode edges. This is formed complex.

The transverse electric field type liquid crystal display device uses the electric field to control the arrangement of liquid crystal molecules.

 3A and 3B are plan views of a transverse electric field type liquid crystal display device with and without voltage applied thereto, and FIG. 3C is a cross-sectional view showing an electrode stepped portion.

For example, as shown in FIG. 3A, when a sufficient voltage is applied to the liquid crystal molecules 32 initially oriented in the same direction as the transmission axis of any one polarizing plate, as shown in FIG. 3B, the liquid crystal molecules 32 may be separated. The long axes are arranged side by side in the electric field. If the dielectric anisotropy of the liquid crystal is negative, the short axis of the liquid crystal molecules is arranged side by side in the electric field.

Specifically, the first and second polarizing plates attached to the outer peripheral surfaces of the opposingly bonded thin film array substrate and the color filter substrate are arranged such that their transmission axes are perpendicular to each other, and the rubbing direction of the alignment layer formed on the lower substrate is transmitted through any one polarizing plate. Parallel to the axis makes it into a normally black mode.

That is, if no voltage is applied to the device, the liquid crystal molecules 32 are arranged as shown in FIG. 3A to display a black state, and if voltage is applied to the device, as shown in FIG. 3B, The liquid crystal molecules 32 are arranged side by side in the electric field to display a white state.

At this time, since the common electrode 24 and the pixel electrode 17 are formed to be bent, the liquid crystal molecules 32 are oriented in two directions to improve the viewing angle.

However, due to the step of the electrode structure when rubbing the alignment layer, the alignment is not well performed at the edge of the electrode, there is a problem that light leakage occurs in the electrode corner.

In particular, as shown in FIG. 3C, the common electrode 24 and the pixel electrode 17 have a bent structure, so that when the alignment layer is rubbed, the electrode electrode A is opposite to the direction in which rubbing occurs. Rubbing is not much better.

Therefore, there is a problem in that the image quality is deteriorated due to the generation of a discretization line in which light leakage occurs at the edge of the electrode.

An object of the present invention is to provide a transverse electric field type liquid crystal display device and a method of manufacturing the same, which blocks light leakage appearing irregularly at the edges of electrodes in a transverse electric field type liquid crystal display device using a black matrix.

According to an aspect of the present invention, there is provided a transverse electric field type liquid crystal display device comprising: a first substrate having a plurality of first electrodes and second electrodes intersected with each other in a pixel area; A second substrate formed to face the first substrate; A black matrix formed in an asymmetrical structure at a position corresponding to the first electrode or the second electrode on the second substrate; It characterized in that it comprises a liquid crystal layer formed between the first substrate and the second substrate.

A gate wiring and a common wiring formed on one side of the first substrate; A data line crossing the gate line; And a thin film transistor formed at an intersection point of the gate line and the data line.

In addition, in order to achieve the above object, a method of manufacturing a transverse electric field type liquid crystal display device according to the present invention includes the steps of forming a plurality of first electrodes and second electrodes alternately formed on a first substrate in which a pixel region is defined; Forming a black matrix formed in an asymmetrical structure at a position corresponding to the first electrode or the second electrode on a second substrate formed to face the first substrate; And forming a liquid crystal layer between the first substrate and the second substrate.

The first electrode and the second electrode is characterized in that formed in at least one bending structure.

The data line or the gate line has a curved structure.

And forming an alignment layer on the first substrate and the second substrate.

The black matrix is characterized in that the width of the position corresponding to the electrode edge on the side opposite to the rubbing direction is formed wider than the width of the position corresponding to the other electrode edge.

Hereinafter, a transverse electric field type liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a plan view illustrating a structure of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention, and FIG. 5 is a cross-sectional view of the transverse electric field type liquid crystal display device taken along line II-II ′ of FIG. 4.

Here, as an embodiment according to the present invention, a two-domain transverse electric field type liquid crystal display device has been described, but the present invention is not limited thereto and may be applied to a multi-domain structure.

As shown in FIG. 4, the array substrate 101 of the transverse electric field type liquid crystal display device according to the present invention includes the gate wiring 112 to define the gate wiring 112 and the pixel region arranged in one direction on the substrate. A thin film for switching voltage at the intersection of the data line 115 and the gate line 112 and the data line 115 to be arranged in a direction perpendicular to the direction of the cross-section. A plurality of common electrodes having a transistor TFT, a common wiring 125 receiving a common electrode signal outside the active region in parallel to the gate wiring 112, and having a structure branched off from the common wiring 125; A pixel electrode 117 connected to the drain electrode 115b of the thin film transistor TFT and having a structure that is bent in parallel with the common electrode 124, and extends from the pixel electrode 117. The capacitor electrode 126 overlapping the common wiring 125 is provided.

Accordingly, the thin film transistor TFT may include a gate insulating layer formed on the entire surface including the gate electrode 112a and the gate electrode 112a branched from the gate wiring 112, as illustrated in FIGS. 4 and 5. And a semiconductor layer 114 formed by sequentially depositing amorphous silicon (a-Si) and n + a-Si in which impurities are implanted into the amorphous silicon on the gate insulating layer 113 on the gate electrode 112a. ) And a source electrode 115a and a drain electrode 115b which are branched from the data line 115 and formed at both ends of the semiconductor layer 114, respectively, to turn on / off a voltage applied to a unit pixel. off).

On the other hand, a gate insulating film 113 is further provided on the front surface including the gate wiring 112 to insulate the gate wiring layer and the data wiring layer, and a protective film 116 is further provided on the front surface including the data wiring 115 to provide the data wiring layer. And the pixel electrode 117 are insulated.

In this case, the gate insulating layer 113 is formed by depositing an inorganic insulating material, such as silicon nitride (SiNx), silicon oxide (SiOx), by PECVD (plasmaenhanced chemical vapor deposition) method, and the protective film 116 is formed of silicon nitride ( It is formed by depositing an inorganic insulating material such as SiNx) or silicon oxide (SiOx) or by applying an organic insulating material such as benzocyclobutene (BCB) or an acrylic material.

The insulating film interposed between the capacitor electrode 126 of the storage capacitor and the common wiring 125 is the gate insulating film 113 and the protective film 116.

On the other hand, on the color filter substrate 102 facing the array substrate 101 configured as described above, the gate wiring 112, the data wiring 115, the common electrode 124, the thin film transistor TFT, and the capacitor electrode 126. A black matrix 131 is formed to prevent leakage of light from the light, and a color filter pattern of red, green, and blue is formed in the pixel area between the black matrix 131. The color filter layer 132 is formed.

An overcoat layer 133 is formed on the color filter layer 132 to planarize the surface and protect the color filter layer 132.

Although not shown, an alignment layer is further formed on the array substrate 101 and the color filter substrate 102.

6 is a view showing a pattern of a black matrix according to the present invention.

As shown in FIG. 6, in the 2-domain (A, B) structure, the black matrix patterns are formed in an asymmetrical structure with each other up and down, which is caused by poor alignment of the liquid crystal due to the folded structure of the electrode and the rubbing direction. It is to block the light leakage caused by.

In more detail, since the common electrode 124 and the pixel electrode 117 are formed to be bent, the liquid crystal molecules are oriented in two directions by rubbing in one direction.

However, due to the bending structure of the electrode and the step difference between the electrodes during rubbing of the alignment layer, the alignment is not well achieved at the corners of the electrodes, and particularly, light leakage occurs in the electrode corners opposite to the rubbing direction. According to the black matrix pattern is designed to further block the light leakage of the electrode edge portion opposite to the rubbing direction.

That is, in the two domain structure, the black matrix 131 of the first domain A and the second domain B is formed at a position corresponding to the common electrode 124, which is biased to the electrode part opposite to the rubbing direction. In order to prevent light leakage, the black matrix 131 at a position opposite to the electrode portion opposite to the rubbing direction is formed to be wider.

On the other hand, even when the bending structure of the electrode is made more than once, the black matrix is deformed to block the light leakage generated in the electrode edge portion opposite to the rubbing direction.

In the above, the gate wiring 112, the gate electrode 112a, the common wiring 125, and the common electrode 124 of the array substrate 101 are copper (Cu), aluminum (Al), and aluminum alloy (AlNd: Low-resistance metals such as Aluminum Neodymium, Molybdenum (Mo), Chromium (Cr), Titanium (Ti), Tantalum (Ta), and Molybdenum-Tungsten (MoW) are deposited and patterned by sputtering to collectively form the same layer. Form the enemy.

In addition, the pixel electrode 117 and the capacitor electrode 126 have relatively high light transmittances such as indium-tin-oxide (ITO) or indium zinc oxide (IZO). Excellent transparent conductive metals are deposited and patterned by the sputtering method and formed on the same layer in a batch.

The common electrode 124 and the pixel electrode 117 may be formed to be parallel to each other in a zigzag form, and may have a structure that is bent several times in a unit pixel, or may have a structure that is bent once in the middle of the unit pixel.

As shown in FIG. 5, the array substrate 101 includes red, green, and blue color filter layers arranged in a predetermined order to implement colors, and R, G, and B cells. A color filter substrate having a black matrix, which serves as a division between and light blocking, is opposed to each other, and a liquid crystal layer having dielectric anisotropy is formed between the two substrates to form a transverse electric field type liquid crystal display device.

The transverse electric field type liquid crystal display device applies a driving voltage to a plurality of thin film transistors to activate the same number of pixel electrodes, and arranges liquid crystals by a transverse electric field formed between the pixel electrode and the common electrode to adjust the light transmittance. Will be implemented.

In the above embodiment, the data wiring has a bending structure. However, the present invention can be applied even when the wiring structure crossing the data wiring has a structure that is not a bending structure. At this time, the common electrode and the pixel electrode

It is formed in parallel by bending to the side of the wiring line.

On the other hand, the gate wiring crossing the data wiring having the bending structure may also have the bending structure. In this case, the present invention can be applied. At this time, the common electrode and the pixel electrode are formed in parallel with each other by bending to one of the gate lines and the data lines.

The first and second polarizing plates attached to the outer bonded surfaces of the opposingly bonded array substrate and the color filter substrate are disposed such that their transmission axes are perpendicular to each other, and the rubbing direction of the alignment layer formed on the lower substrate is parallel to the transmission axis of any one polarizing plate. By doing so, it becomes a normally black mode.

7A to 7C are exemplary embodiments schematically showing a part of a black matrix according to the present invention.

Referring to FIG. 7A, light leakage is remarkably generated at an electrode edge portion opposite to the rubbing direction. The black matrix pattern according to the present invention may further block light leakage at the electrode edge portion opposite to the rubbing direction. Design a wider range.

7B and 7C, the protruding black matrix may be extended or cut out to form a smooth shape K to prevent light leakage at each domain boundary.

According to the present invention, a black matrix is formed to block a light leakage generation region due to poor rubbing not only in a multi-domain liquid crystal display device having a bent structure but also in an array substrate of a transverse electric field type liquid crystal display device having a straight electrode structure. can do.

Although the present invention has been described in detail with reference to specific examples, this is for describing the present invention in detail, and the transverse electric field type liquid crystal display device and the manufacturing method thereof according to the present invention are not limited thereto, and the present invention is not limited thereto. It is apparent that modifications and improvements are possible by those skilled in the art.

The present invention has the effect of improving the color contrast ratio and improving the image quality by blocking light leakage due to poor rubbing generated at the edges of the electrode along the rubbing direction in the transverse electric field type liquid crystal display device.

In addition, the present invention does not require a separate process and can achieve the maximum effect only by changing the design of the black matrix.

Claims (13)

A first substrate in which a plurality of first electrodes and second electrodes are crossed in the pixel region; A second substrate formed to face the first substrate; A black matrix formed in an asymmetrical structure at a position corresponding to the first electrode or the second electrode on the second substrate; And a liquid crystal layer formed between the first substrate and the second substrate. The method of claim 1, A gate wiring and a common wiring formed on one side of the first substrate; A data line crossing the gate line; And a thin film transistor formed at an intersection point of the gate wiring and the data wiring. The method of claim 1, And the first electrode and the second electrode have at least one bending structure. The method of claim 2, And the data line has a bending structure. The method of claim 2, And the gate wiring has a curved structure. The method of claim 1, And the first substrate and the second substrate further comprise an alignment layer. The method of claim 1, And the black matrix has a width of a position corresponding to an electrode edge opposite to a rubbing direction wider than a width of a position corresponding to another electrode edge. Staggering a plurality of first electrodes and second electrodes on a first substrate in which a pixel region is defined; Forming a black matrix formed in an asymmetrical structure at a position corresponding to the first electrode or the second electrode on a second substrate formed to face the first substrate; Forming a liquid crystal layer between the first substrate and the second substrate; manufacturing method of a transverse electric field type liquid crystal display device comprising a. The method of claim 8, Forming a gate wiring and a common wiring on one side of the first substrate; Forming a data line crossing the gate line; Forming a thin film transistor at an intersection point of the gate wiring and the data wiring; the manufacturing method of a transverse electric field type liquid crystal display device further comprising. The method of claim 8, The first electrode and the second electrode is a method of manufacturing a transverse electric field type liquid crystal display device, characterized in that formed at least once bent structure. The method of claim 9, The data line or the gate line has a curved structure, the manufacturing method of the transverse electric field type liquid crystal display device. The method of claim 8, And forming an alignment layer on the first substrate and the second substrate. The method of claim 8, And the black matrix has a width corresponding to an edge of the electrode opposite to the rubbing direction to be wider than a width corresponding to the edge of the other electrode.

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