KR20000026198A - Multi domain lcd - Google Patents

Abstract

PURPOSE: A multi domain LCD is provided to increase an electric field distortion effect by forming a dielectric asperity at a lower plate and forming an electric field inducing window at an upper plate to distort an electric field. CONSTITUTION: A plurality of data lines and gate lines are horizontally and vertically formed on a first substrate(31) and divide the first substrate(31) into a plurality of pixel regions. A thin film transistor is formed to pixel regions and has a gate electrode(11), a gate insulating film(35), a semiconductor layer(5), an ohmic contact layer, and source/drain electrode(7,9). A protecting layer(37) is formed around the first substrate(31). A pixel electrode(13) is connected to the drain electrode(9) on the protecting layer(37) and is overlapped with the thin film transistor and/or data lines and gate lines. A dielectric asperity(41) controls an orientation direction of a liquid crystal molecule of a liquid crystal layer.

Description

Multi-domain liquid crystal display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a multi-domain liquid crystal display device for distorting an electric field by forming a dielectric protrusion on a lower plate and an electric field induction window on an upper plate.

Recently, a liquid crystal display device for driving a liquid crystal by side electrodes electrically insulated from the pixel electrode without aligning the liquid crystal has been proposed.

1 is a cross-sectional view of a unit pixel of the conventional liquid crystal display device described above.

In a conventional liquid crystal display device, a plurality of data wirings and gate wirings are vertically and horizontally formed on a first substrate to divide the first substrate into a plurality of pixel regions, and are formed in each of the pixel regions and include a gate electrode, a gate insulating film, and a semiconductor A thin film transistor (TFT) composed of a layer, a source electrode, a drain electrode, and the like applies an image signal transmitted from the data wiring to the pixel electrode 13 formed on the insulating layer 4. The side electrode 15 is formed on the gate insulating film so as to surround the pixel electrode 13, the insulating layer 4 is formed over the entire substrate, and a part of the pixel electrode 13 is described as the side electrode. It forms so that it may overlap with (15) (FIG. 1).

Alternatively, as another modification, a pixel electrode is formed on the gate insulating film, an insulating layer is formed over the entire substrate, and side electrodes are formed so as to overlap with a part of the pixel electrode. There is also proposed a structure for dividing the pixel region by etching the electrode into a specific shape.

The common electrode 17 is formed on the second substrate to apply an electric field to the liquid crystal layer made of liquid crystal molecules together with the pixel electrode 13. The side electrode 15 formed around the pixel electrode 13 and the slit 19 of the second substrate distort the electric field applied to the liquid crystal layer to variously drive the liquid crystal molecules in the unit pixel. This means that when a voltage is applied to the liquid crystal display, the dielectric energy due to the distorted electric field places the liquid crystal director in a desired direction.

The conventional liquid crystal display device has a homogeneous alignment in which the pretilt angle of the liquid crystal molecules adjacent to the alignment film is 0 °, and the tilt direction of the liquid crystal layer when voltage is applied is applied to the electric field induced by the side electrode 15. Is determined by

2A and 2B show a cross-sectional view and a plan view of another conventional liquid crystal display device. The liquid crystal display device does not form side electrodes as shown in FIG. 1, and forms the pixel electrode 13 of the first substrate smaller than the common electrode 17 of the second substrate, thereby inducing distortion of the electric field. As shown in FIG. 6B, the slits 19 are formed to divide the domains and are horizontally aligned.

However, the above-described liquid crystal display devices require a slit 19 on the pixel electrode 13 or the common electrode 17 for uniform driving of liquid crystal molecules, and drive the liquid crystal molecules more stably by increasing the area of the slit. You can. On the other hand, if there is no slit or the width of the slit is small, the electric field distortion necessary for domain division is weak. Therefore, the time required for the director of the liquid crystal to reach a stable state when a voltage higher than the threshold voltage (V _th ) is applied is determined. Relatively long. At this time, since a range of the liquid crystal director parallel to the transmission axis of the polarizer exists and a foreground occurs, a decrease in luminance due to this is also pointed out as a problem. In addition, depending on the surface state of the liquid crystal display device, the liquid crystal texture (texture) may have an irregular shape, and there is a disadvantage that it is limited to the liquid crystal display device having two domains.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide a multi-domain liquid crystal display device having a wide viewing angle characteristic due to a multi-domain effect and a high luminance characteristic due to stable movement of liquid crystal molecules when voltage is applied. do.

In order to achieve the above object, the multi-domain liquid crystal display device according to the present invention, the opposing first substrate and second substrate, the liquid crystal layer formed between the first substrate and the second substrate, and the first A plurality of gate wirings and data wirings formed vertically and horizontally on a substrate to define a pixel region, a pixel electrode formed in the pixel region, a dielectric protrusion for controlling the alignment direction of liquid crystal molecules of the liquid crystal layer, And a color filter layer formed on the second substrate, a common electrode formed on the color filter layer, and an alignment film formed on at least one of the first substrate and the second substrate.

The dielectric protrusion is patterned and formed around and / or inside the pixel region.

The common electrode and / or the pixel electrode is patterned to have an electric field guide window therein.

In addition, since the pixel region and the alignment layer are divided into at least two regions, the liquid crystal molecules of the liquid crystal layer exhibit different driving and alignment characteristics on each region, and the alignment layer is subjected to rubbing or photoalignment.

1 is a cross-sectional view of a conventional liquid crystal display device.

2A and 2B are a cross-sectional view and a plan view of another conventional liquid crystal display device.

3A, 3B, 3C, and 3D are cross-sectional views of multi-domain liquid crystal display elements according to the first, second, third, and fourth embodiments of the present invention.

4A, 4B, and 4C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention.

5A, 5B, and 5C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention.

6A, 6B, and 6C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention.

7A, 7B, and 7C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention.

8A, 8B, and 8C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention.

9A, 9B, and 9C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention.

10A, 10B, and 10C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

4: insulating layer 5: semiconductor layer

7 source electrode 9 drain electrode

11 gate electrode 13 pixel electrode

15: side electrode 17: common electrode

19: slit area 23: color filter layer

27: light shielding layer 29: overcoat layer

31: first substrate 33: second substrate

35 gate insulating film 37 protective film

39: contact hole 41: dielectric projection

43: field induction window 45: the first alignment film

47: second alignment film

Hereinafter, a multi-domain liquid crystal display device according to the present invention will be described in detail with reference to the drawings.

3A, 3B, 3C, and 3D are cross-sectional views of a multi-domain liquid crystal display device according to the first, second, third, and fourth embodiments of the present invention.

As shown in the above drawings, the multi-domain liquid crystal display device of the present invention is formed vertically and horizontally on the first substrate 31 and the second substrate 33 and the first substrate 31 to form a plurality of first substrates. A plurality of data wirings and gate wirings divided into pixel regions, and formed in each of the pixel regions on the first substrate 31, and include a gate electrode 11, a gate insulating layer 35, a semiconductor layer 5, and an ohmic contact layer. layer) and source / drain electrodes 7 and 9, a protective film 37 formed over the entire first substrate 31, and a thin film transistor connected to the drain electrode 9 on the protective film. And / or the pixel electrode 13 formed to overlap the data wiring and the gate wiring, and a dielectric protrusion 41 for controlling the alignment direction of the liquid crystal molecules of the liquid crystal layer.

The light blocking layer 27 blocking light leaking from the gate wiring, the data wiring, and the thin film transistor on the second substrate 33 and the color filter layer 23 formed on the light blocking layer 27. And the overcoat layer 29 formed on the color filter layer 23, the common electrode 17 formed on the overcoat layer 29, and between the first substrate 31 and the second substrate 33. It consists of a liquid crystal layer formed on.

In order to manufacture the liquid crystal display device having the above-described structure, first, the gate electrode 11, the gate insulating film 35, the semiconductor layer 5, the ohmic contact layer and the source / drain in each pixel region of the first substrate 31 are first manufactured. A thin film transistor consisting of electrodes 7 and 9 is formed. In this case, a plurality of gate wirings and data wirings which divide the first substrate 31 into a plurality of pixel regions are formed. The gate electrode 11, the gate / data wiring and the source / drain electrodes 7 and 9 are formed by sputtering a metal such as Al, Mo, Cr, Ta, or an Al alloy, and then patterning the same. The semiconductor layer 5 and the ohmic contact layer are formed by laminating and patterning a-Si and n ⁺ a-Si by a plasma chemical vapor deposition (CVD) method, respectively, and the gate insulating layer 35 is formed of SiN. _X or SiO _X is formed by laminating and patterning by plasma CVD. Subsequently, the protective film 37 is formed of a material such as BCB (BenzoCycloButene), an acrylic resin, a polyimide compound, SiN _X or SiO _X and the like, and the ITO (indium) is formed over the first substrate 31. A metal electrode 13 is formed by stacking a metal such as tin oxide), Al, or Cr by a sputtering method and then patterning the metal. In this case, the pixel electrode 13 is formed by patterning once with the same metal or twice with different kinds of metals, and the source / drain electrodes of the thin film transistor are formed as the contact holes (s) of the pixel electrode 13. Electrically connected via 39). In addition, after the photosensitive material is stacked on the pixel electrode 13, the dielectric projection 41 is formed around and inside the pixel region by patterning by photolithography. The material constituting the dielectric protrusion 41 is preferably equal to or smaller than the dielectric constant of the liquid crystal layer, preferably 3 or less, and may include a material such as acryl (photoacrylate) or BCB (BenzoCycloButene).

The light blocking layer 27 is formed on the second substrate 33, and the color filter layer 23 is formed such that R, G, and B (red, green, blue) elements are repeated for each pixel. The overcoat layer 29 is formed of a resin on the color filter layer 23, and the common electrode 17 is formed of a transparent electrode such as ITO, like the pixel electrode 13, and patterned to form the electric field induction window 43. Form. Then, the liquid crystal is injected between the first substrate 31 and the second substrate 33 to complete the multi-domain liquid crystal display element.

The dielectric protrusion 41 is formed on at least one of the first substrate and the second substrate, and the electric field induction window 43 is formed of at least one of the substrate or the counter substrate on which the dielectric protrusion 41 is formed. 7B and 7D, or may not be formed (FIGS. 7A and 7C), or may be formed on both substrates simultaneously with the dielectric protrusion.

4A, 4B, and 4C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention, and FIGS. 5A, 5B, and 5C are plan views of a multi-domain liquid crystal display device according to an embodiment of the present invention, and FIG. 6A. 6B and 6C are plan views of the multi-domain liquid crystal display device according to an exemplary embodiment of the present invention, and FIGS. 7A, 7B and 7C are plan views of the multi-domain liquid crystal display device according to an exemplary embodiment of the present invention.

As shown in the above drawings, the multi-domain liquid crystal display device of the present invention patterns stable dielectric alignment by patterning the dielectric protrusions 41 and the electric field induction window 43 into various shapes, and by performing alignment treatment on the alignment films. Implement

8A, 8B and 8C are plan views of a multi-domain liquid crystal display device according to an exemplary embodiment of the present invention, and FIGS. 9A, 9B and 9C are plan views of a multi-domain liquid crystal display device according to another exemplary embodiment of the present invention. 10A, 10B, and 10C show plan views of a multi-domain liquid crystal display device according to still another embodiment of the present invention, respectively.

As shown in the drawing, the dielectric protrusion 41 and the field induction window 43 are formed in two directions of the field induction window 43 and two orientation directions (solid arrow indicates the second substrate). The alignment direction and the dotted line arrow indicate the alignment direction of the first substrate, respectively) (Figs. 8A and 8B) to form a four-domain liquid crystal display element or a combination of two neighboring pixels to form an eight-domain liquid crystal. A display device may be formed (FIG. 8C) to implement a multi-domain effect.

The dielectric protrusion 41 may be formed only on the data wiring side or only on the gate wiring side as shown in FIG.

As shown in the drawing, the electric field induction window 43 has the effect of dividing into two domains by patterning the pattern horizontally, vertically, and diagonally in length, or by × shape, + shape, and not shown in the drawing. By simultaneously patterning the x and + shapes, the effect of dividing into 4 domains and multi-domains can be realized.

In addition, the multi-domain liquid crystal display device of the present invention forms the alignment films 47 and 45 over the entirety of the first substrate and / or the second substrate. At this time, a material such as polyamide or polyimide compound, PVA (polyvinylalcohol), polyamic acid or SiO ₂ is used as the alignment material constituting the alignment film. When the orientation direction is determined using the rubbing method, any material suitable for other rubbing treatments can be applied.

In addition, the alignment layer may be formed of a photoreactive material, that is, a material such as PVCN (polyvinylcinnamate), PSCN (polysiloxanecinnamate), or CelCN (cellulosecinnamate) -based compound to form a photoalignment film, and other optical alignment treatment Any material suitable for is applicable. The photo-alignment film is irradiated with light at least once so that the alignment angle, alignment direction, and pretilt angle of the liquid crystal molecules are formed, and the pretilt angle direction. angle direction) is determined at the same time, thereby ensuring the orientation stability of the liquid crystal. As for the light used for the optical alignment, light in the ultraviolet region is suitable, and any light among non-polarized light, linearly polarized light, and partially polarized light may be used.

The rubbing method or the photo-alignment method may be applied only to any one of the first substrate or the second substrate, or may be treated on both substrates, or different alignment treatments may be performed on both substrates.

In addition, by performing the above-described alignment process, a multi-domain liquid crystal display device divided into at least two regions may be formed so that the liquid crystal molecules of the liquid crystal layer may be differently aligned on each region. That is, the multi-domain effect is realized by dividing each pixel into four regions, such as + or × characters, or by dividing them into horizontal, vertical, or diagonal lines, and by forming different alignment processes or orientation directions in each region and each substrate. do. It is also possible to make at least one of the divided areas into an unoriented area.

The multi-domain liquid crystal display device of the present invention forms a dielectric protrusion on the lower plate and forms an electric field induction window on the upper plate to distort the electric field, thereby increasing the electric field distortion effect, thereby realizing a wide viewing angle.

In addition, it is possible to obtain a fast response time and a stable liquid crystal structure by pretilt and anchoring energy formed by the alignment treatment. As a result, the foreground is removed, thereby obtaining an effect of increasing luminance.

Claims (24)

Opposing first and second substrates, A liquid crystal layer formed between the first substrate and the second substrate; A plurality of gate wirings and data wirings formed vertically and horizontally on the first substrate to define pixel regions; A pixel electrode formed in the pixel region, A dielectric protrusion for controlling the alignment direction of the liquid crystal molecules of the liquid crystal layer; A color filter layer formed on the second substrate; A common electrode formed on the color filter layer; A multi-domain liquid crystal display device comprising an alignment film formed on at least one of the first substrate and the second substrate. The multi-domain liquid crystal display device according to claim 1, wherein the dielectric protrusion is patterned. The multi-domain liquid crystal display device according to claim 1, wherein the common electrode has an electric field induction window therein. 4. The multi-domain liquid crystal display device according to claim 3, wherein the common electrode is formed by patterning. The multi-domain liquid crystal display device according to claim 1, wherein the pixel electrode has an electric field induction window therein. 6. The multi-domain liquid crystal display device according to claim 5, wherein the pixel electrode is formed by patterning. The multi-domain liquid crystal display device according to claim 1, wherein the dielectric protrusion is formed around the pixel area. The multi-domain liquid crystal display device according to claim 1, wherein the dielectric protrusion is formed inside the pixel region. The multi-domain liquid crystal display device according to claim 1, further comprising an overcoat layer on the color filter layer. The multi-domain liquid crystal display of claim 1, wherein the material constituting the pixel electrode is selected from the group consisting of indium tin oxide (ITO), Al, and Cr. A multi-domain liquid crystal display device according to claim 1, wherein the dielectric constant of said dielectric is equal to or less than that of said liquid crystal layer. The multi-domain liquid crystal display device according to claim 1, wherein the dielectric protrusion is made of a photosensitive material. The multi-domain liquid crystal display device of claim 1, wherein the dielectric protrusion is made of a material selected from the group consisting of acryl (photoacrylate) and BCB (BenzoCycloButene). The multi-domain liquid crystal display of claim 1, wherein the material constituting the common electrode is made of indium tin oxide (ITO). The multi-domain liquid crystal display device according to claim 1, wherein the pixel region is divided into at least two regions so that the liquid crystal molecules of the liquid crystal layer exhibit different driving characteristics on each region. The multi-domain liquid crystal display device according to claim 1, wherein the alignment film is divided into at least two regions so that the liquid crystal molecules of the liquid crystal layer exhibit different alignment characteristics on each region. 17. The multi-domain liquid crystal display device according to claim 16, wherein at least one of the areas of the alignment film is aligned. 17. The liquid crystal display device according to claim 16, wherein at least one of the regions of the alignment layer is rubbed. 19. The method of claim 18, wherein the material constituting the alignment layer is selected from the group consisting of polyimide and polyamide-based compounds, polyvinylalcohol, polyamic acid, and SiO ₂ . A liquid crystal display device characterized by the above-mentioned. 17. The multi-domain liquid crystal display device according to claim 16, wherein at least one of the regions of the alignment layer is optically aligned. The multi-domain liquid crystal display device according to claim 20, wherein the material constituting the alignment layer is selected from the group consisting of polyvinylcinnamate (PVCN), polysiloxanecinnamate (PSCN), and cellulosecinnamate (CelCN) -based compounds. 21. The multi-domain liquid crystal display device according to claim 20, wherein the optical alignment uses light in an ultraviolet region. 21. The multi-domain liquid crystal display device according to claim 20, wherein the optical alignment irradiates light at least once. The multi-domain liquid crystal display device according to claim 1, wherein the liquid crystal constituting the liquid crystal layer is a liquid crystal having positive dielectric anisotropy.