KR20050055413A - Liquid crystal display - Google Patents

Abstract

The liquid crystal display according to the present invention includes a first insulating substrate, a plurality of gate lines formed on the first insulating substrate, a plurality of data lines crossing the gate lines, a plurality of thin films connected to the respective gate lines and the data lines, respectively. A thin film transistor array panel including a transistor, a plurality of pixel electrodes connected to each thin film transistor, a second insulating substrate facing the first insulating substrate, and an opposing display panel including a common electrode formed on the second insulating substrate; A red, green, and blue color filter for displaying color corresponding to the pixel electrode, and a liquid crystal filled between the thin film transistor array panel and the color filter display panel, wherein the pixel electrode and the common electrode are linear to cross each other by domain division means. It has a first and a second incision.

Description

Liquid crystal display

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having multiple domains.

The liquid crystal display is one of the most widely used flat panel displays, and includes an upper panel and a lower panel on which electrodes are formed, and a liquid crystal layer filled therebetween. A polarizer for polarizing light is attached to the outside of the display panel.

A thin film transistor (TFT) display panel used as a lower display panel is used as a circuit board for independently driving each pixel in a display device, and the like. A gate line for supplying a scan signal to the thin film transistor and a data line for supplying an image signal Wiring such as this is formed. The opposite display panel used as the upper display panel includes a color filter, a black matrix, and an opposite electrode for forming color.

The liquid crystal display may be classified into a TN mode, a VA mode, and an IPS mode according to the alignment characteristics of the filled liquid crystal.

TN mode liquid crystal display device is generally used twisted nematic (hereinafter referred to as TN) liquid crystal. The TN liquid crystal molecules have a thin long rod shape and are arranged in parallel to the substrate, have a constant pitch, and are twisted in a spiral from the lower substrate to the upper substrate so that the alignment direction of the long axis of the liquid crystal molecules is continuously changed. It has a twisted structure.

In a liquid crystal display device using a TN liquid crystal, the incident polarized light exhibits different optical viewing angle characteristics according to the arrangement of the long axis and the short axis of the molecule. Since the viewing angle of the liquid crystal display device is formed along the long axis of the liquid crystal molecules of the spiral structure, the long axis of the molecule changes according to the viewing angle. Such a liquid crystal display has a symmetrical viewing angle with respect to the horizontal direction and an asymmetrical viewing angle with respect to the vertical direction. In particular, a gray level phenomenon occurs in a direction in which the liquid crystal tilt direction and the viewing angle at the center of the cell coincide with each other. Therefore, the light transmittance is distributed relatively symmetrically with respect to the horizontal viewing angle, but the light transmittance is distributed asymmetrically with respect to the vertical direction, so that the image is inverted in the vertical viewing angle so that the viewing angle is narrow and the contrast ratio is lowered. It has a disadvantage.

In order to solve this problem, a liquid crystal display device having a wide viewing angle characteristic has been developed. For example, an in-plane-switching (hereinafter referred to as IPS) method and a vertically aligned mode (hereinafter referred to as VA) method are used. There is this.

The IPS scheme is a structure in which linear common electrodes and pixel electrodes are spaced apart from each other on the same substrate by a predetermined interval, and the liquid crystal molecules are aligned even when the viewing direction changes due to the arrangement of the liquid crystal molecules by the transverse electric field distributed between the pixel electrodes and the reference electrodes. Since the change in the refractive index is small, the viewing angle is improved. However, in the transverse electric field mode, since the reference electrode and the pixel electrode are simultaneously formed on a single pixel, the aperture ratio of the liquid crystal panel is reduced, the luminance characteristic is poor, and the response speed is slow.

In the VA mode, the liquid crystal molecules are oriented vertically with respect to the upper and lower substrates on which the counter electrode and the pixel electrode are formed, respectively. In order to realize a wide viewing angle, a constant incision pattern is formed or formed on the pixel electrode and the common electrode as the counter electrode. A patterned vertical alignment (PVA) mode is formed that divides the pixel into multiple domains.

However, in the PVA mode, the gamma curve of the front and the gamma curve of the side do not coincide with each other, resulting in inferior visibility in the left and right sides compared to the twisted nematic (TN) mode. For example, in the case of the PVA mode in which the domain is divided by means of division, the screen tends to appear brighter toward the side and the color tends to shift toward the white side.In severe cases, the picture is clumped because there is no gap between the bright gradations. It also happens.

Accordingly, an object of the present invention is to provide a liquid crystal display device which can realize a wide viewing angle and ensure visibility and can have a high contrast ratio.

The liquid crystal display according to the present invention for achieving the above-described paragraph is formed so that the cutouts of the upper and lower display panels intersect.

Specifically, the liquid crystal display according to the present invention is connected to a first insulating substrate, a plurality of gate lines formed on the first insulating substrate, a plurality of data lines intersecting the gate lines, respective gate lines and data lines, respectively. A thin film transistor array panel including a plurality of thin film transistors and a plurality of pixel electrodes connected to each thin film transistor, a second insulating substrate facing the first insulating substrate, and a counter including a common electrode formed on the second insulating substrate. A display panel, a red, green, and blue color filter for displaying color corresponding to each pixel electrode, and a liquid crystal filled between the thin film transistor array panel and the color filter display panel, wherein the pixel electrode and the common electrode cross each other by domain division means. Has linear first and second incisions.

It is preferable that a liquid crystal has negative dielectric anisotropy here.

The thin film transistor includes a gate electrode connected to a gate line, a semiconductor layer overlapping the gate electrode, a source electrode overlapping the semiconductor layer and a predetermined region, and a data electrode overlapping the data line, a semiconductor layer and a predetermined region overlapping the source electrode and the gate electrode. It includes a drain electrode opposed to the center.

In this case, the data line and the drain electrode having the source electrode may have the same planar pattern except for a predetermined region of the semiconductor layer.

In addition, at least two first and second cutouts are preferably formed, and the color filter is preferably formed on the first insulating substrate or the second insulating substrate.

In addition, the liquid crystal is preferably oriented perpendicular to the first and second insulating substrates in a state where a predetermined voltage is not applied to the common electrode and the pixel electrode.

In addition, it is preferable to divide and align the plurality of domains with a predetermined voltage applied to the common electrode and the pixel electrode.

In addition, the liquid crystal forming the domain is preferably oriented a twisted nematic structure.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is over another part, this includes not only the part directly above the other part but also another part in the middle. In contrast, when a part is just above another part, it means that there is no other part in between.

A thin film transistor array panel according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[First Embodiment]

1 is a layout view of a liquid crystal display according to an exemplary embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line II-II 'of FIG. 1, and FIG. 3 is a cross-sectional view taken along the line III-III' of FIG. 1. 4 is a layout view of an upper panel for forming the liquid crystal display shown in FIG. 1, and FIG. 5 is a layout view of a lower panel for forming the liquid crystal display shown in FIG. 1.

1 to 5, the liquid crystal display according to the present invention includes a lower display panel (or a thin film transistor array panel 100), an upper display panel (or opposing display panel 200), and a lower display panel 100 that face each other. The liquid crystal molecules (not shown) are filled between the upper panel 200 and vertically oriented with respect to the two display panels 100 and 200.

The lower panel 100 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) on the substrate 110 made of a transparent insulating material, and is disposed in each pixel, and the first cutout 191 A plurality of pixel electrodes 190 are formed, and each pixel electrode 190 is connected to a thin film transistor to receive an image signal voltage. In this case, the thin film transistor is connected to the gate line 121 for transmitting the scan signal and the data line 171 for transmitting the image signal, respectively, and turns on the image signal transmitted to the pixel electrode 190 according to the scan signal. Turn on / off.

The upper panel 2 defines a pixel area in a matrix form on the transparent insulating substrate 210, and a black matrix 220 is formed to prevent light leakage. The red, green, and blue color filters 230R, 230G, and 230B are formed on the pixel area, and the common electrode 270 is formed on the color filters 230R, 230G, and 230B.

The color filters 230R, 230G, and 230B may be formed (not shown) together with the thin film transistors on the lower panel. In this case, the edges of the color filter may be formed to overlap each other on the data line, thereby serving as a black matrix. Therefore, the black matrix may be left only in portions corresponding to the thin film transistors to improve the aperture ratio of the pixel region.

The common electrode 270 has a plurality of second cutouts 271 intersecting with the first cutouts 191 of the lower panel 100. In addition, an alignment layer 21 is formed on the common electrode 270, and the alignment layer is preferably rubbed in order to determine the arrangement direction or the pretilt angle of the liquid crystal molecules 3.

Liquid crystals filled between the liquid crystals 100 and 200 may have negative dielectric anisotropy and may have a predetermined pretilt angle according to the alignment directions of the alignment layers formed on the lower panel 100 and the upper panel 200. The liquid crystals according to the present invention are arranged in a vertical form with the substrates 100 and 200 in a state where no voltage is applied, and the alignment of the alignment layers formed on the display panels 100 and 200 cross each other.

In addition, a spacer (not shown) for maintaining a gap between the upper panel 200 and the lower panel 100 and a sealant (not shown) for sealing the liquid crystal 3 are further formed.

Hereinafter, the lower panel of the liquid crystal display device described above will be described in more detail.

As illustrated, the lower panel 100 according to the present invention has a plurality of gate lines 121 and a plurality of storage electrode lines 131 formed on the transparent insulating substrate 110. .

The gate line 121 transmits a gate signal, and a portion of each gate line 121 forms a gate electrode 124 of the thin film transistor, and the gate electrode 124 is deformed into various shapes to form a gate line. It may also be a protrusion.

The storage electrode line 131 is formed in the pixel area to increase the storage capacitance of the pixel, is separated from the gate line 121, and mainly extends in the horizontal direction. The storage electrode line 131 receives a predetermined predetermined voltage such as a common voltage applied to a common electrode (not shown) of another display panel (not shown).

The gate line 121 and the storage electrode line 131 may include a conductive film made of an aluminum-based metal such as aluminum (Al) or an aluminum alloy. In addition to the conductive film, other materials such as indium tin oxide (ITO) or IZO may be used. chromium (Cr), titanium (Ti), tantalum (Ta), molybdenum (Mo) and their alloys (eg, molybdenum-tungsten (MoW) alloys) with good physical, chemical and electrical contact with indium zinc oxide It can be formed into a multilayer film structure including another conductive film made of. An example of the combination of the lower layer and the upper layer is chromium / aluminum-neodymium (AlNd) alloy.

A gate insulating layer 140 made of silicon nitride (SiNx) is formed on the 121 and 131.

A plurality of linear semiconductor layers 151 made of hydrogenated amorphous silicon (amorphous silicon is abbreviated a-Si) and the like are formed on the gate insulating layer 140. The linear semiconductor layer 151 mainly extends in the vertical direction and has a plurality of extensions 154 extending therefrom to the gate electrode 124.

The linear semiconductor layer 151 has a portion that is not covered between the source electrode 173 and the drain electrode 175, which will be described later, and the width of the linear semiconductor layer 151 is smaller than the width of the data line 171.

On top of the semiconductor layers 151 and 154 a plurality of linear and island ohmic contacts 161 and 165 made of a material such as n + hydrogenated amorphous silicon doped with a high concentration of silicide or n-type impurities. Is formed. The linear ohmic contact layer 161 has a plurality of protrusions 163, and the protrusions 163 and the island contact layer 165 are paired and positioned on the protrusions 154 of the semiconductor layer 151.

The ohmic contacts 161 and 165 exist only between the semiconductor layers 151 and 154 below the data line 171 and the drain electrode 175 thereon, and serve to lower the contact resistance therebetween. The ohmic contacts 161 and 165 have the same planar pattern as the semiconductor layer 151 except for a predetermined region of the semiconductor layer 151. The predetermined region of the semiconductor layer 154 is a channel portion that forms a channel of the thin film transistor.

The semiconductor layer 151 may increase in width at the portion where the semiconductor layer 151 meets the gate line 121 to enhance insulation between the gate line 121 and the data line 171 (not shown). The portion of the linear semiconductor layer 151 under the data line 171 may not be formed according to the parasitic capacitance between the semiconductor layer 151 and the data line 171.

Sidewalls of the semiconductor layers 151 and 154 and the ohmic contacts 161 and 165 are formed to be tapered so that the layers formed thereon can be tightly adhered to each other.

A plurality of data lines 171 and a plurality of drain electrodes 175 are formed on the ohmic contacts 161 and 165 and the gate insulating layer 140, respectively.

The data line 171 is formed on the linear ohmic contact layer 161 and mainly extends in the vertical direction to cross the gate line 121 and transmit a data voltage. The drain electrode 175 is formed on the island resistive contact layer 165.

A plurality of branches extending from the data line 171 toward the drain electrode 175 forms a source electrode 173. The pair of source electrode 173 and the drain electrode 175 are separated from each other and positioned opposite to the gate electrode 124. The gate electrode 124, the source electrode 173, and the drain electrode 175 form a thin film transistor (TFT) together with the protrusion 154 of the semiconductor layer 151, and the channel of the thin film transistor The protrusion 154 is formed between the source electrode 173 and the drain electrode 175.

One end of the data line 171 may be wider than the width of the data line 171 to receive a signal transmitted from a data driving circuit (not shown). A portion of the drain electrode 175 connected to the pixel electrode 190 overlaps the storage electrode line 131. A constant voltage is applied to the storage electrode line 131 to form a storage capacitor between the storage electrode line and the storage electrode and the drain electrode.

The data line 171 and the drain electrode 175 may also include a conductive film made of a silver metal or an aluminum metal. In addition to the conductive film, chromium (Cr), titanium (Ti), and tantalum (Ta) may be used. , Molybdenum (Mo) and alloys thereof, and the like, and may be formed in a multilayer film structure including another conductive film.

The passivation layer 180 is formed on the substrate to cover the data line 171, the drain electrode 175, and the exposed semiconductor layer 154. The passivation layer 180 is a-Si: C: O, a-Si: O: F, which is formed of an organic material having excellent planarization characteristics and photosensitivity, and plasma enhanced chemical vapor deposition (PECVD). Low dielectric constant insulating materials such as silicon nitride or inorganic materials.

The passivation layer 180 may be formed of a low dielectric constant organic material having a dielectric constant of 4.0 or less. In this case, the thickness of the passivation layer 180 is thicker than that of the inorganic material, and thus the pixel electrode 190 and the data line 171 are formed. Since the coupling phenomenon does not occur, the edge of the pixel electrode 190, which will be described later, may overlap the data line 171 to maximize the aperture ratio of the pixel.

In the passivation layer 180, a plurality of contact holes 182 exposing an end portion of the data line 171 and a plurality of contact holes 185 exposing the drain electrode 175 are formed.

A plurality of pixel electrodes 190 and a plurality of contact assistants 82 formed of indium tin oxide (ITO) or indium zinc oxide (IZO) are formed on the passivation layer 180.

The pixel electrode 190 is physically and electrically connected to the drain electrode 175 through the contact hole 185 to receive a data voltage from the drain electrode 175. The pixel electrode 190 to which the data voltage is applied rearranges the liquid crystal molecules between the two electrodes by generating an electric field together with a common electrode (not shown) of another display panel.

When the passivation layer 180 is formed of an organic material having a low dielectric constant, the pixel electrode 190 may partially overlap the neighboring gate line 121 and the data line 171 to increase the aperture ratio.

The contact auxiliary member 82 is connected to one end of the data line 171 through the contact hole 182. When the end portion of the gate line 121 also has a structure for connecting with the driving circuit like the end portion of the data line 171, a gate contact auxiliary member is formed on the passivation layer 180.

The contact assisting member 82 is to compensate for adhesion to the outside, and is particularly necessary when the contact auxiliary member 82 is mounted on the substrate 110 or a fusible circuit board (not shown) in the form of a chip. If it is made of a thin film transistor or the like directly above, it is not formed.

Finally, an alignment layer 11 is formed on the pixel electrode 190, the contact auxiliary member 82, and the passivation layer 180. The alignment film 11 is subjected to a rubbing process for determining the alignment direction of the liquid crystal molecules.

Next, the operation of the liquid crystal display according to the present invention will be described with reference to FIGS. 6A to 9 attached to the cutouts formed in the electrodes.

6A and 6B schematically illustrate the arrangement of liquid crystal molecules in the Voff state, and FIGS. 7A and 7B schematically illustrate the alignment direction of the liquid crystal molecules in the Von state, and FIG. 8A is ab in FIG. 7B. A cross-sectional view of the liquid crystal molecules in the Von state as shown in the cross-sectional view of FIG. 8B. FIG. 8B is a cross-sectional view of the liquid crystal molecules in the state of V in FIG. 7A. 9 is a view showing a direction in which the liquid crystal is twisted in the Von state.

First, when no power is applied (Voff), as shown in FIGS. 6A and 6B, the liquid crystal molecules 3 are vertically arranged with respect to the upper and lower display panels 100 and 200. Here, the circle represents the director of the liquid crystal.

Subsequently, when power is applied (Von), as shown in FIGS. 7A and 7B, the cutout portion is affected by the fringe field formed through the cutouts 191 and 271 formed in the electrodes 190 and 270. Since adjacent liquid crystal molecules have negative dielectric anisotropy, the liquid crystal molecules are arranged to be inclined into the cutouts 191 and 271 facing in parallel and having an arbitrary angle with respect to the substrate.

At this time, as shown in FIGS. 8A and 8B, the liquid crystal 3 positioned near the substrate has an arbitrary angle with respect to the substrate 100 and 200 by a fringe field through the respective cutouts 191 and 271. While the substrates are arranged in succession, they are arranged perpendicular to the electric field formed on the two electrodes 190 and 270 facing each other as they move away from the substrates 100 and 200, and are arranged substantially horizontally with respect to the display panels 100 and 200.

However, the cutouts 191 and 271 formed on the electrodes facing each other are disposed to cross each other, and the liquid crystals are disposed at the centers of the two display panels except for the liquid crystals 3 adjacent to the upper and lower display panels 100 and 200. The molecules are continuously twisted in the direction in the direction as shown in FIG. 9, so that the liquid crystal molecules are arranged in a twisted structure in a twisted nematic (TN) manner and dividedly aligned in four regions (A, B, C, and D). For example, among the liquid crystals in the area A, the liquid crystals (white circles) adjacent to the lower panel are arranged in a horizontal direction due to the electric field by the cutout 191, but the incision formed on the upper panel is closer to the cutouts by the upper panel. It is twisted in the direction of the arrow under the influence of the electric field caused by the part 271. Herein, one region in each of four regions where the arrangement of liquid crystals is different is called a domain.

As described above, according to the exemplary embodiment of the present invention, a wide viewing angle is obtained by dividing and aligning the liquid crystal molecules into a plurality of domains by forming cutouts intersecting with each other in the common electrode and the pixel electrode formed on the upper and lower display panels, and at the same time, arrange the liquid crystal molecules in a TN manner. As a result, distortion of the gamma curve can be minimized, thereby ensuring visibility.

In addition, in the normally black mode, which is the initial arrangement direction, the liquid crystal molecules may be arranged perpendicularly to the substrate to obtain a high contrast ratio (C / R).

Second Embodiment

10 is a cross-sectional view of the liquid crystal display according to the second exemplary embodiment of the present invention, taken along the line II-II ′ of FIG. 1, and FIG. 11 is a cross-sectional view of the liquid crystal display according to the second exemplary embodiment of the present invention. 1 is a cross-sectional view taken along the line III-III 'of FIG. 1.

As shown, the data line 171, the source electrode 173 and the drain electrode 175 and the ohmic contact layers 161 and 165 of the second embodiment are formed in the same pattern. The ohmic contacts 161 and 165 are formed in the same pattern except for a predetermined region of the semiconductor layers 151 and 154. The predetermined region is a channel region that forms a channel between the source electrode 173 and the drain electrode 175. Except for the parts described above, they are formed in the same structure as in the first embodiment.

In the method of manufacturing the thin film transistor array panel according to the second exemplary embodiment of the present invention, the semiconductor layers 151 and 154, the ohmic contact layers 161 and 165, and the data line 171 and the drain electrode 175 have different thicknesses. It is formed by patterning together in a photolithography process using a photoresist pattern having a photoresist, wherein the photoresist pattern is formed by a photo process using a single photomask or two photomasks having a transmission region, a transflective region and a blocking region.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, when a liquid crystal display device having a TN structure having a plurality of domains is formed, the viewing angle and visibility are improved. In addition, since a high C / R value due to the vertical alignment can be obtained, a high quality liquid crystal display device can be provided.

1 is a layout view of a liquid crystal display according to a first exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II 'of FIG. 1,

3 is a cross-sectional view taken along the line III-III 'of FIG. 1,

4 is a layout view of an upper panel for forming the liquid crystal display shown in FIG. 1;

FIG. 5 is a layout view of a lower panel for forming the liquid crystal display shown in FIG. 1;

6A and 6B are diagrams schematically showing an arrangement direction of liquid crystal molecules in a Voff state,

7A and 7B schematically illustrate an arrangement direction of liquid crystal molecules in a Von state.

FIG. 8A is a cross-sectional view taken along line a-b of FIG. 7B and illustrates an arrangement of liquid crystal molecules in a Von state. FIG.

FIG. 8B is a cross-sectional view taken along the line C-D of FIG. 7A and illustrates the arrangement of liquid crystal molecules in a Von state. FIG.

9 is a diagram illustrating a direction in which liquid crystal molecules rotate in a Von state,

FIG. 10 is a cross-sectional view of the liquid crystal display according to the second exemplary embodiment of the present invention, taken along the line II-II ′ of FIG. 1.

FIG. 11 is a cross-sectional view of the liquid crystal display according to the second exemplary embodiment of the present invention, taken along the line III-III ′ of FIG. 1.

※ Explanation of symbols on main parts of drawing ※

11, 21: alignment film 110, 210: insulating substrate

140: gate insulating film 121: gate line

171: data line 175: drain electrode

180: protective film 190: pixel electrode

220: black matrix 270: common electrode

Claims (9)

A first insulating substrate, a plurality of gate lines formed on the first insulating substrate, a plurality of data lines intersecting the gate lines, a plurality of thin film transistors connected to the respective gate lines and the data lines, respectively A thin film transistor array panel including a plurality of pixel electrodes connected to the thin film transistors, An opposing display panel including a second insulating substrate facing the first insulating substrate and a common electrode formed on the second insulating substrate; Red, green, and blue color filters for displaying colors corresponding to the pixel electrodes; A liquid crystal filled between the thin film transistor array panel and the color filter panel; And the pixel electrode and the common electrode have linear first and second cutouts that cross each other by domain dividing means. In claim 1, The liquid crystal device has a negative dielectric anisotropy. In claim 1, The thin film transistor, A gate electrode connected to the gate line, A semiconductor layer overlapping the gate electrode; A source electrode overlapping the semiconductor layer with a predetermined region and connected to the data line; And a drain electrode overlapping the semiconductor layer with a predetermined region and facing the source electrode and the gate electrode. In claim 3, The data line and the drain electrode having the source electrode have the same planar pattern except for a predetermined region of the semiconductor layer. In claim 1, And at least two first and second cutouts. In claim 1, The color filter is formed on the first insulating substrate or the second insulating substrate. In claim 1, And the liquid crystal is oriented perpendicular to the first and second insulating substrates while a predetermined voltage is not applied to the common electrode and the pixel electrode. In claim 1, And a plurality of domains which are divided and aligned in a plurality of domains while a predetermined voltage is applied to the common electrode and the pixel electrode. In claim 8, The liquid crystal forming the domain is aligned a twisted nematic structure.