GB2367374A

GB2367374A - Multi domain liquid crystal device

Info

Publication number: GB2367374A
Application number: GB0119163A
Authority: GB
Inventors: Kyeong Jin Kim; Do Hee Kwon; Jang Jin Yoo; Yun Bok Lee; Sung Joon Bae; Jae Yoon Lee
Original assignee: LG Philips LCD Co Ltd
Current assignee: LG Display Co Ltd
Priority date: 1998-10-19
Filing date: 1999-10-19
Publication date: 2002-04-03
Anticipated expiration: 2019-10-19
Also published as: GB0119163D0; GB2367374B

Abstract

Gate bus lines and data bus lines are arranged on the surface of a substrate (31) separated from another substrate (33) by a layer of liquid crystal so as to define a plurality of pixel regions each containing a pixel electrode (13). A common electrode (17) is formed on the facing substrate. Dielectric frames (41) control the alignment direction of the molecules in the liquid crystal layer.

Description

A MULTI-DOMAIN LIQUID CRYSTAL DISPLAY DEVICE

The present invention relates to a liquid crystal display device (LCD), and more particularly, to a liquid crystal display device having dielectric frames on one substrate and electric field inducing window on the same or on the other substrate.

Recently, a LCD has been proposed where the liquid crystal is not aligned, and the liquid crystal is driven by common electrode 17 having open areas 19. Fig. 1 is a sectional view of pixel unit of a conventional LCD.

Regarding conventional LCDs, a plurality of gate bus lines arranged in a first direction on a first substrate and a plurality of data bus lines arranged in a second direction on the first substrate divide the first substrate into a plurality of pixel regions.

A thin film transistor (TFT) applies image signal delivered from the data bus line to a pixel electrode 13 on a passivation layer 4. The TFT is formed on each pixel region and comprises a gate electrode, a gate insulator, a semiconductor layer, an ohmic contact layer, a source electrode, and a drain electrode, etc.

Alternatively, a side electrode 15 is formed to surround the pixel region on the gate insulator, a passivation layer 4 is formed over the whole first substrate, and pixel electrode 13 is formed to overlap the side electrode 15 and is connected to the drain electrode thereon.

On a second substrate, a light shielding layer is formed to shield any light leakage from gate and data bus lines, and the TFT, a color filter layer is formed on the light shielding layer, an overcoat layer is formed on the color filter layer, a common electrode 17 is formed to have open area 19 on the overcoat layer, and a liquid crystal layer is formed between the first and second substrates.

Pixel electrode 13 and open area (slit) 19 in the common electrode 17 distort the electric field applied to the liquid crystal layer. Then, liquid crystal molecules are driven variously in a unit pixel. This means that when voltage is applied to the LCD, dielectric energy due to the distorted electric field arranges the liquid crystal directors in needed or desired positions.

Fig. 2 is a sectional view of the other liquid crystal display device in the related art. The liquid crystal display device has a smaller pixel electrode 13 than common electrode 17, which induces the distortion of electric field.

In the LCDs, however, open area 19 in common electrode 17 or pixel electrode 13 is necessary, and the liquid crystal molecules could be driven stably when the open area is wider.

If the electrodes do not have an open area or the width of the open area is narrow, the electric field distortion needed to divide the pixel region becomes weak.

And, disclination occurs from the area where the liquid crystal directors are parallel with a transmittance axis of the polarizer, which results in a decrease in brightness.

Further, according to the surface state of LCDs, the liquid crystal texture has an irregular structure.

Accordingly, the present invention is directed to a LCD that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a multi-domain LCD having wide viewing angle by multi-domain and high brightness by stable arrangement of liquid crystal molecules.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, a multi-domain liquid crystal display device comprises first and second substrates facing each other, a liquid crystal layer between the first and second substrates, a plurality of gate bus lines arranged in a first direction on the first substrate and a plurality of data bus lines arranged in a second direction on the first substrate to define a pixel region, a pixel electrode in the pixel region, a dielectric frame controlling alignment direction of liquid crystal molecules in the liquid crystal layer, a color filter layer on the second substrate, a common electrode on the color filter layer, and an alignment layer on at least one substrate between the first and second substrates.

The common electrode and/or pixel electrode has an electric field inducing window in the inner part thereof.

The dielectric frame is formed surrounding the pixel region or in the pixel region. And, the dielectric constant of the dielectric frame is equal to or lower than dielectric constant of the liquid crystal layer. The dielectric frame includes photosensitive materials, such as photoacrylate and BCB (BenzoCycloButene).

It is to be understood that both the foregoing general description and the following detailed description are

exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

For a better understanding of the present invention, embodiments will now be described by way of example, with reference to the accompanying drawings, in which: Figs. 1 and 2 are sectional views of the liquid crystal display devices in the related art; Figs. 3A, 3B, 3C, and 3D are sectional views of the multi-domain liquid crystal display devices according to the first, second, third, and fourth embodiment of the present invention; Figs. 4A, 4B, and 4C are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention; Figs. 5A, 5B, and 5C are plan views of the multi-demain liquid crystal display devices according to embodiments of the present invention; Figs. 6A, 6B, and 6C are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention; Figs. 7A, 7B, and 7C are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention; Figs. 8A, 8B, and BC are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention; Figs. 9A, 9B, and 9C are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention; Figs. 10A, 10B, and 10C are plan views of the multidomain liquid crystal display devices according to embodiments of the present invention;

Figs. llA, llB, and 11C are plan views of the multidomain liquid crystal display devices according to embodiments of the present invention; Figs. 12A, 12B, 12C, and 12D are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention; Figs. 13A, 13B, and 13C are plan views of the multidomain liquid crystal display devices according to embodiments of the present invention; Figs. 14A and 14B are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention.

Figs. 15A and 15B are plan and sectional view of the multi-domain liquid crystal display device according to the fifth embodiment of the present invention; Figs. 16A and 16B, 16C are plan and sectional views of the multi-domain liquid crystal display devices according to the sixth embodiment of the present invention; Figs. 17A and 17B, 17C are plan and sectional views of the multi-domain liquid crystal display devices according to the seventh embodiment of the present invention;

Figs. 18A and 18B, 18C, 18D, 18E, 18F, 18G are plan and sectional views of the multi-domain liquid crystal display devices according to eighth embodiment of the present invention ; Figs. 19A, 19B, 19C, 19D, 19E, 19F, and 19G are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention; Figs. 20A, 20B, 20C, 20D, 20E, 20F, and 20G are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention;

Figs. 21A, 21B, 21C, 21D, 21E, 21F, 21G, 21H, 211, 21J, 21K, 21L, and 21M are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention ; Figs. 22A, 22B, 22C, and 22D are plan views of the multi-domain liquid crystal display devices according to embodiments of the present invention; Figs. 23A, 23B, and 23C are plan views of the multidomain liquid crystal display devices according to embodiments of the present invention; and Figs. 24A, 24B, and 24C are plan views of the multidomain liquid crystal display devices according to embodiments of the present invention.

Figs. 25A, 25B, 25C, and 25D are sectional views of the multi-domain liquid crystal display devices according to the ninth embodiment of the present invention ; Figs. 26A, 26B, and 26C are sectional views of the multi-domain liquid crystal display devices according to the tenth embodiment of the present invention ; Figs. 27A, 27B, 27C, and 27D are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention; Figs. 28A, 28B, 28C, and 28D are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention ; Figs. 29A, 29B, 29C, and 29D are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention ;

Figs. 30A, BOB, 30C, and 30D are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention; Figs. 31A, 31B, 31C, 31D, 31E, and 31F are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention; Figs. 32A, 32B, and 32C are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention; Figs. 33A, 33B, and 33C are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention; Figs. 34A, 34B, 34C, 34D, 34E, and 34F are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention; Figs. 35A, 35B, 35C, 35D, 35E, and 35F are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention; Figs. 36A, 36B, 36C, 36D, 36E, 36F, 36G, and 36H are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention; Figs. 37A and 37B are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to an embodiment of the present invention ;

Figs. 38A and 38B are plan and sectional views of the multi-domain liquid crystal display device according to the eleventh embodiment of the present invention.

Hereinafter, the multi-domain liquid crystal display device of the present invention is explained in detail by accompanying the drawings.

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

As shown in the figures, the display device comprises first and second substrates 31,33, a plurality of gate bus lines arranged in a first direction on the first substrate and a plurality of data bus lines arranged in a second direction on the first substrate, a TFT, a passivation layer 37 on the whole first substrate 31, a pixel electrode 13, dielectric frames 41, and a first alignment layer on the whole first substrate 31.

On the second substrate 33, a light shielding layer 25 is formed to shield any light leakage from gate and data bus lines, and the TFT, a color filter layer 23 is formed on the light shielding layer, an overcoat layer 29 is formed on the color filter layer 23, a common electrode 17 is formed on the overcoat layer, a second alignment layer on the whole second substrate 33, and a liquid crystal layer is formed between the first and second substrates 31,33.

The data bus lines and gate bus lines divide the first substrate 31 into a plurality of pixel regions. The TFT is formed on each pixel region and comprises a gate electrode 11, a gate insulator 35, a semiconductor layer 5, an ohmic contact layer, and source/drain electrodes 7,9. Passivation

layer 37 is formed on the whole first substrate 31, and pixel electrode 13 is coupled to drain electrode 9.

The dielectric frame 41 is controlling alignment direction of liquid crystal molecules of the liquid crystal layer. This is formed on the pixel electrode 13 or the common electrode 17, and it is possible to form the dielectric frame on both substrates.

To manufacture the multi-domain LCD, in each pixel region on the first substrate 31, a TFT is formed comprising gate electrode 11, gate insulator 35, semiconductor layer 5, ohmic contact layer 6 and source/drain electrodes 7,9. At this time, a plurality of gate bus lines and a plurality of data bus lines are formed to divide the first substrate 31 into a plurality of pixel regions.

Gate electrode 11 and gate bus line are formed by sputtering and patterning a metal such as Al, Mo, Cr, Ta, Al alloy, etc. Alternatively, it is possible to form the gate electrode and gate bus line as a double layer, the double layer is formed from different materials.

The gate insulator 35 is formed by depositing SiNx or SiOx using PECVD (Plasma Enhancement Chemical Vapor Deposition) thereon. Semiconductor layer 5 and the ohmic contact layer are formed by depositing with PECVD and patterning amorphous silicon (a-Si) and doped amorphous silicon (n+ a-Si), respectively. Also, SiNx or SiOx and a-Si, n a-Si are formed by depositing with PECVD, the gate insulator 35 is formed and the semiconductor layer 5 and the ohmic contact layer 6 are formed by patterning.

Data bus line and source/drain electrodes 7,9 are formed by sputtering and patterning a metal such as Al, Mo, Cr, Ta, Al alloy, etc. Alternatively, it is possible to form

the data bus line and source/drain electrodes as a double layer, the double layer is formed from different materials.

A storage electrode (not shown in the figures) is formed to overlap gate bus line and to connect to the pixel electrode 13 at the same time, the storage electrode makes a storage capacitor with the gate bus line 1.

Subsequently, passivation layer 37 is formed with BCB (BenzoCycloButene), acrylic resin, polyimide based material, SiNx or SiOx on the whole first substrate 31. Pixel electrode 13 is formed by sputtering and patterning a metal such as ITO (Indium Tin Oxide), Al or Cr. A contact hole 39 is formed to connect the pixel electrode 13 to the drain and storage electrodes by opening and patterning a part of the passivation layer 37 on drain electrode 9.

On the second substrate 33, a light shielding layer 25 is formed to shield any light leakage from gate and data bus lines, and the TFT. A color filter layer 23 is formed R, G, B (red, green, blue) elements to alternate on the light shielding layer 25. On the color filter layer 23, overcoat layer 29 is formed with resin. A common electrode 17 is formed with ITO on the overcoat layer.

And, a liquid crystal layer is formed by injecting liquid crystal between the first and second substrates 31, 33. The liquid crystal layer may include liquid crystal molecules having positive or negative dielectric anisotropy.

Also, the liquid crystal layer may include chiral dopants.

A dielectric frame 41 is formed by depositing photosensitive material on the common electrode 17 or pixel electrode 13 and patterning in various shapes using photolithography. The dielectric frame 41 includes material of which dielectric constant is same or smaller than that of the liquid crystal, and the dielectric constant thereof is

preferably below 3, for example, photoacrylate or BCB (BenzoCycloButene).

Furthermore, the dielectric frame 41 is formed on at least one substrate between the first and second substrates 31, 33 (refer to Figs. 3A, 3B and 3C, 3D). And, an electric field inducing window 43 is formed on at least one substrate between the first and second substrates 31, 33 (refer to Figs. 3B and 3D).

At this time, the dielectric frame 41 and electric field inducing window 43 are formed on same substrate together.

The electric field inducing window 43 is formed by patterning the common electrode 17 or pixel electrode 13.

As shown in Figs. 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14 are plan views showing the various dielectric frames 41 and electric field inducing windows 43 of the multi-domain liquid crystal display devices according to embodiments of the present invention. The solid lined-arrow represents the alignment direction of the second substrate, and the dotted lined-arrow represents the alignment direction of the first substrate.

As shown in the Figures, the dielectric frame 41 and the electric field inducing window 43 are patterned in various shapes, which obtains multi-domain effect. The electric field inducing window 43 may be a slit or hole. Furthermore, neighboring two pixels and two alignment directions are associated, which obtains multi-domain effect.

From forming electric field inducing window 43, the multi-domain is obtained by dividing each pixel into four domains such as in a"+","x", or"double Y"shape, or dividing each pixel horizontally, vertically, and/or diagonally, and differently alignment-treating or forming alignment directions on each domain and on each substrate.

On at least one substrate, a compensation film 29 is formed with polymer. The compensation film 29 is a negative uniaxial film, which has one optical axis, and compensates the phase difference of the direction according to viewingangle. Hence, it is possible to compensate effectively the right-left viewing-angle by widening the area without gray inversion, increasing contrast ratio in an inclined direction, and forming one pixel to multi-domain.

In the present multi-domain liquid crystal display device, it is possible to form a negative biaxial film as the compensation film 29, which has two optical axes and has wider viewing-angle characteristics as compared with the negative uniaxial film. The compensation film 29 could be formed on both substrates or on one of them.

After forming the compensation film 29, polarizer is formed on at least one substrate. At this time, the compensation film 29 and polarizer are preferably composed as one.

In the present LCD, the liquid crystal layer includes liquid crystal molecules having negative dielectric anisotropy, which applies a homeotropic alignment where liquid crystal molecules in the liquid crystal layer are aligned homeotropically to surfaces of the first and second substrates.

In the multi-domain LCD an alignment layer (not shown in the figure) is formed over the whole first and/or second substrates. The alignment layer includes a material such as polyamide or polyimide based materials, PVA (polyvinylalcohol), polyamic acid or SiO2. When rubbing is used to determine an alignment direction, it should be possible to apply any material suitable for the rubbing treatment.

Moreover, it is possible to form the alignment layer with a photosensitive material such as PVCN (polyvinylcinnamate), PSCN (polysiloxanecinnamate), and CelCN (cellulosecinnamate) based materials. Any material suitable for the photo-aligning treatment may be used.

Irradiating light once on the alignment layer determines the alignment or pretilt direction and the pretilt angle. The light used in the photo-alignment is preferably a light in a range of ultraviolet light, and any of unpolarized light, linearly polarized light, and partially polarized light can be used.

In the rubbing or photo-alignment treatment, it is possible to apply one or both of the first and second substrates, and to apply different aligning-treatment on each substrate.

From the aligning-treatment, a multi-domain LCD is formed with at least two domains, and LC molecules of the LC layer are aligned differently one another on each domain.

That is, the multi-domain is obtained by dividing each pixel into four domains such as in a"+"or"x"shape, or dividing each pixel horizontally, vertically, and/or diagonally, and differently alignment-treating or forming alignment directions on each domain and on each substrate.

It is possible to have at least one domain of the divided domains unaligned. It is also possible to have all domains unaligned.

Consequently, the multi-domain LCD forms dielectric frames of which dielectric constant is different from that of liquid crystal, and electric field inducing window to distort electric field, thereby wide viewing angle is obtained.

Furthermore, in the case of conducting an alignmenttreatment, a high response time and a stable LC structure can be obtained by a pretilt angle and an anchoring energy.

Figs. 15A and 15B are plan and sectional view of the multi-domain liquid crystal display device according to the fifth embodiment of the present invention, Figs. 16A, and 16B, 16C are plan and sectional views of the multi-domain liquid crystal display devices according to the sixth embodiment of the present invention, Figs. 17A and 17B, 17C are plan and sectional views of the multi-domain liquid crystal display devices according to the seventh embodiment of the present invention, and Figs. 18A and 18B, 18C, 18D, 18E, 18F, 18G are plan and sectional views of the multidomain liquid-crystal display devices according to eighth embodiment of the present invention.

As shown in the figures, the display device comprises first and second substrates 31,33, a plurality of gate bus lines arranged in a first direction on the first substrate and a plurality of data bus lines arranged in a second direction on the first substrate, a TFT, a passivation layer 37 on the whole first substrate 31, a pixel electrode 13, and a first alignment layer 53 on the whole first substrate.

On a second substrate, a light shielding layer 25 is formed to shield any light leakage from gate and data bus lines, and the TFT, a color filter layer 23 is formed on the light shielding layer, a common electrode 17 is formed on the color filter layer, a dielectric frame 57 to distort electric field on the common electrode 17, a second alignment layer 55 on the whole second substrate, and a liquid crystal layer is formed between the first and second substrates.

Data bus lines and gate bus lines divide the first substrate 31 into a plurality of pixel regions. The TFT is

formed on each pixel region and comprises a gate electrode 11, a gate insulator 35, a semiconductor layer 5, an ohmic contact layer, and source/drain electrodes 7,9. Passivation layer 37 is formed on the whole first substrate and pixel electrode 13 is coupled to drain electrode 9.

To manufacture the multi-domain LCD, in each pixel region on the first substrate 31, a TFT is formed comprising gate electrode 11, gate insulator 35, semiconductor layer 5, ohmic contact layer and source/drain electrodes 7,9. At this time, a plurality of gate bus lines and a plurality of data bus lines are formed to divide the first substrate 31 into a plurality of pixel regions.

Gate electrode 11 and gate bus line are formed by sputtering and patterning a metal such as Al, Mo, Cr, Ta, Al alloy, etc. The gate insulator 35 is formed by depositing SiNx or SiOx using PECVD (Plasma Enhancement Chemical Vapor Deposition) thereon. Semiconductor layer 5 and the ohmic contact layer are formed by depositing with PECVD and patterning amorphous silicon (a-Si) and doped amorphous silicon (n'a-Si), respectively. Also, SiNx or SiOx and a-Si, n+ a-Si are formed by depositing with PECVD, the gate insulator 35 is formed and semiconductor layer 5 and the ohmic contact layer 6 are formed by patterning. Data bus line and source/drain electrodes 7,9 are formed by sputtering and patterning a metal such as Al, Mo, Cr, Ta, Al alloy, etc.

A storage electrode (not shown in the figures) is formed to overlap gate bus line and to connect to the pixel electrode 13 at the same time, the storage electrode makes a storage capacitor with the gate bus line.

Subsequently, passivation layer 37 is formed with BCB (BenzoCycloButene), acrylic resin, polyimide based material,

SiNx or SiOx on the whole first substrate 31. Pixel electrode 13 is formed by sputtering and patterning a metal such as ITO (indium tin oxide). A contact hole 39 is formed to connect the pixel electrode 13 to the drain and storage electrodes by opening and patterning a part of the passivation layer 37 on drain electrode 9.

On the second substrate 33, a light shielding layer 25 is formed to shield any light leakage from gate and data bus lines, and the TFT. A color filter layer 23 is formed R, G, B (red, green, blue) elements to alternate on the light shielding layer. A common electrode 17 is formed with ITO on the color filter layer. A dielectric frame 57 is formed by depositing photosensitive material on the common electrode 17 or pixel electrode 13 and patterning in various shapes using photolithography. And, a liquid crystal layer is formed by injecting liquid crystal between the first and second substrates.

The dielectric frame 57 includes material of which dielectric constant is same or smaller than that of the liquid crystal, and the dielectric constant thereof is preferably below 3, for example, photoacrylate or BCB (BenzoCycloButene).

Furthermore, the dielectric frame 57 is also used as a spacer (refer to Figs. 15B, 16C, 17C, 18C, 18E, and 18G).

Dielectric frame 57 is formed on at least one substrate between the first and second substrates. In these embodiments, a spacer dispersing process could be omitted and the gap uniformity of liquid crystal cell is enhanced, therefore, the yield is improved.

And, an electric field inducing window 43 is formed on at least one substrate between the first and second substrates (refer to Figs. 17B and 18F, 18G). At this time,

the dielectric frame and electric field inducing window are formed on same substrate together. The electric field inducing window 43 is formed in various shapes by patterning hole or slit in the common electrode 17 or pixel electrode 13.

As an embodiment in multi-domain LCD of the present invention, an auxiliary electrode 27 is additionally formed in an area except the pixel region. (refer to Figs. 16A and 18A) The auxiliary electrode 27 is formed on a layer whereon the pixel electrode 17 or gate electrode 11 is formed, and electrically connected to the common electrode 17. (refer to Figs. 16B, 16C and 18D, 18E) The auxiliary electrodes 27 is formed by sputtering and patterning a metal such as ITO (indium tin oxide), Al, Mo, Cr, Ta, Ti or Al alloy. At this time, it is possible to form the auxiliary and pixel electrodes 27,13 by patterning the same metal once or by patterning different metals twice.

As shown in Figs. 20,22, 23, and 24, the auxiliary electrode 27 can be formed as surrounding the pixel electrode 13, in the side of data bus line and/or in the side of gate bus line.

Fig. 18 shows that the light shielding layer 25 is formed on the first substrate 31, Figs. 18D and 18E show that the auxiliary electrode 27 is formed on a layer whereon the pixel electrode 17 is formed. In these embodiments, the light shielding layer is formed to adjust exactly the pixel region, hence, the lamination margin is reduced and the aperture ratio is enhanced than the light shielding layer is formed on the second substrate.

On at least one substrate, a compensation film 29 is formed with polymer. The compensation film is a negative uniaxial film, which has one optical axis, and compensates

the phase difference of the direction according to viewingangle. Hence, it is possible to compensate effectively the right-left viewing-angle by widening the area without gray inversion, increasing contrast ratio in an inclined direction, and forming one pixel to multi-domain.

In the present multi-domain liquid crystal display device, it is possible to form a negative biaxial film as the compensation film 29, which has two optical axes and has wider viewing-angle characteristics as compared with the negative uniaxial film. The compensation film could be formed on both substrates or on one of them.

After forming the compensation film 29, polarizer is formed on at least one substrate. At this time, the compensation film and polarizer are preferably composed as one.

In the Figs. 19A to 19G, the dielectric frame 57 is patterned in various shapes, which obtains multi-domain effect.

In the Figs. 20A to 20G, the auxiliary electrode 27 is formed surrounding pixel electrode 13, and the dielectric frame 57 is patterned in various shapes, which obtains multidomain effect.

In the Figs. 21A to 21M, the electric field inducing window 43 is formed, and the dielectric frame 57 is patterned in various shapes, which obtains multi-domain effect. The electric field inducing window 43 may be a slit or hole.

In the LCD in Figs. 19 to 21, the liquid crystal layer includes liquid crystal molecules having negative dielectric anisotropy, which applies a homeotropic alignment where liquid crystal molecules in the liquid crystal layer are aligned homeotropically to surfaces of the first and second substrates.

In the Figs. 22A, 22B, 22C, and 22D, the auxiliary electrode 27 is formed, and the dielectric frame 57 is patterned in various shapes, which obtains multi-domain effect. Although not shown in the figures, there are embodiments that do not form the auxiliary electrode 27.

The solid lined-arrow 63 presents the rubbing direction of the second substrate 33 and the dotted lined-arrow 61 presents the rubbing direction of the first substrate 31.

In the Figs. 23A, 23B, and 23C, the auxiliary electrode 27 is formed, and the dielectric frame 57 is patterned in various shapes. Furthermore, neighboring two pixels and two alignment directions are associated, which obtains multidomain effect. Although not shown in the figures, there are embodiments that do not form the auxiliary electrode 27.

The solid lined-arrow 67 presents the alignment direction of the second substrate 33 and the dotted linedarrow 65 presents the alignment direction of the first substrate 31.

In the Figs. 24A, 24B, and 24C, the auxiliary electrode 27 is formed, and the dielectric frame 57 is patterned in various shapes. Furthermore, neighboring two pixels and two alignment directions are associated being different from that in the Fig. 23, which obtains multi-domain effect. Although not shown in the figures, there are embodiments that do not form the auxiliary electrode 27.

In the LCD in Figs. 22 to 24, the liquid crystal layer includes liquid crystal molecules having positive dielectric anisotropy, which applies a homogeneous alignment where liquid crystal molecules in the liquid crystal layer are aligned homogeneously to surfaces of the first and second substrates.

From forming the electric field inducing window or dielectric frame, the multi-domain is obtained by dividing each pixel into four domains such as in a"+","x", or "double Y"shape, or dividing each pixel horizontally, vertically, and/or diagonally, and differently alignmenttreating or forming alignment directions on each domain and on each substrate.

Furthermore, in the multi-domain LCD, the first and second alignment layers are formed over the whole first and/or second substrates. The alignment layer includes a material such as polyamide or polyimide based materials, PVA (polyvinylalcohol), polyamic acid or Si02. When rubbing is used to determine an alignment direction, it should be possible to apply any material suitable for the rubbing treatment.

Moreover, it is possible to form the alignment layer with a photosensitive material such as PVCN (polyvinylcinnamate), PSCN (polysiloxanecinnamate), and CelCN (cellulosecinnamate) based materials. Any material suitable for the photo-aligning treatment may be used. Irradiating light once on the alignment layer determines the alignment or pretilt direction and the pretilt angle. The light used in the photo-alignment is preferably a light in a range of ultraviolet light, and any of unpolarized light, linearly polarized light, and partially polarized light can be used.

Consequently, the multi-domain LCD forms dielectric frames of which dielectric constant is different from that of liquid crystal, and auxiliary electrode or electric field inducing window to distort electric field, thereby wide viewing angle is obtained.

Also, the dielectric frame is patterned as a spacer, which can leave out the spacer process in the conventional LCD processes.

Figs. 25A, 25B, 25C, and 25D are sectional views of the multi-domain liquid crystal display devices according to the ninth embodiment of the present invention and Figs. 26A, 26B, and 26C are sectional views of the multi-domain liquid crystal display devices according to the tenth embodiment of the present invention.

As shown in the figures, the display device comprises first and second substrates 31,33, a plurality of gate bus lines 1 arranged in a first direction on a first substrate and a plurality of data bus lines 3 arranged in a second direction on the first substrate, a TFT, a passivation layer 37, and a pixel electrode 13.

On the second substrate 33, a light shielding layer 25 is formed to shield the light leaked from gate and data bus lines 1, 3, and the TFT, a color filter layer 23 is formed on the light shielding layer, a common electrode 17 is formed on the color filter layer, a dielectric frame in a region other than the pixel region, and a liquid crystal layer is formed between the first and second substrates.

Data bus lines 3 and gate bus lines 1 divide the first substrate 31 into a plurality of pixel regions. The TFT is formed on each pixel region and comprises a gate electrode 11, a gate insulator 35, a semiconductor layer 5, an ohmic contact layer 6, and source/drain electrodes 7,9.

Passivation layer 37 is formed on the whole first substrate 31. Pixel electrode 13 is coupled to the drain electrode 9.

To manufacture the multi-domain LCD, in each pixel region on the first substrate 31, a TFT is formed comprising gate electrode 11, gate insulator 35, semiconductor layer 5, ohmic contact layer 6 and source/drain electrodes 7,9. At this time, a plurality of gate bus lines 1 and a plurality of data bus lines 3 are formed to divide the first substrate 31 into a plurality of pixel regions.

Gate electrode 11 and gate bus line 1 are formed by sputtering and patterning a metal such as Al, Mo, Cr, Ta, Al alloy, etc. Alternatively, it is possible to form the gate electrode and gate bus line as a double layer, the double layer is formed from different materials.

The gate insulator 35 is formed by depositing SiNx, SiOx, or BCB (BenzoCycloButene), acrylic resin using PECVD thereon. Semiconductor layer 5 and the ohmic contact layer 6 are formed by depositing with PECVD (Plasma Enhancement Chemical Vapor Deposition) and patterning amorphous silicon (a-Si) and doped amorphous silicon (n+ a-Si), respectively.

Also, SiNx or SiOx and a-Si, n+ a-Si are formed by depositing with PECVD, the gate insulator 35 is formed and the semiconductor layer 5 and the ohmic contact layer 6 are formed by patterning.

Data bus line 3 and source/drain electrodes 7,9 are formed by sputtering and patterning a metal such as Al, Mo, Cr, Ta, Al alloy, etc. Alternatively, it is possible to form the data bus line and source/drain electrodes as a double layer, the double layer is formed from different materials.

A storage electrode (not shown in the figures) is formed to overlap gate bus line 1, the storage electrode makes a storage capacitor with gate bus line 1.

Subsequently, passivation layer 37 is formed with BCB (BenzoCycloButene), acrylic resin, polyimide based material, SiNx or SiOx on the whole first substrate. Pixel electrode 13 is formed by sputtering and patterning a metal such as ITO (indium tin oxide). A contact hole 39 is formed to connect the pixel electrode 13 to the drain 9 and storage electrodes by opening and patterning a part of the passivation layer 37 on drain electrode 9.

On the second substrate 33, a light shielding layer 25 is formed to shield any light leakage from gate and data bus lines 1, 3, and the TFT. A color filter layer 23 is formed R, G, B (red, green, blue) elements to alternate on the light shielding layer 25.

A common electrode 17 is formed with ITO on the color filter layer 23, and a liquid crystal layer is formed by injecting liquid crystal between the first and second substrates. The liquid crystal layer may include liquid crystal molecules having positive or negative dielectric anisotropy. Also, the liquid crystal layer may include chiral dopants.

On at least one substrate between the first and second substrates, a dielectric frame 53 is formed by depositing photosensitive material in a region other than a region where the pixel electrode 13 is formed and patterning in various shapes using photolithography.

The dielectric frame 53 includes material of which dielectric constant is same or smaller than that of the liquid crystal, and the dielectric constant thereof is preferably below 3, for example, photoacrylate or BCB (BenzoCycloButene).

As an embodiment, the dielectric frame could include mixture of polyimide and carbon black or mixture of acrylic resin and carbon black. And then, the dielectric frame shields light leakage from an area except the pixel region and distorts the electric field applied to the liquid crystal layer. In this case, the dielectric constant of the liquid crystal layer is about 4, preferably the dielectric constant of the dielectric frame is below 3.5.

On the other hand, as shown in the figures 26A, 26B, and 26C, the dielectric frame is also used as a spacer to maintain uniformly gap between the first and second substrates.

Furthermore, the dielectric frame 53 is formed on at least one substrate between the first and second substrates.

And, an electric field inducing window 51 is formed on at least one substrate between the first and second substrates.

At this time, the dielectric frame 53 and electric field inducing window 51 could be formed on same substrate together. The electric field inducing window 51 is formed by patterning the common electrode 17 or pixel electrode 13.

On at least one substrate, a compensation film 29 is formed with polymer. The compensation film is a negative

uniaxial film, which has one optical axis, and compensates the phase difference of the direction according to viewing angle. Hence, it is possible to compensate effectively the right-left viewing-angle by widening the area without gray inversion, increasing contrast ratio in an inclined direction, and forming one pixel to multi-domain.

In the present multi-domain liquid crystal display device, it is possible to form a negative biaxial film as the compensation film, which has two optical axes and wider viewing-angle characteristics as compared with the negative uniaxial film. The compensation film could be formed on both substrates or on one of them.

After forming the compensation film, polarizer is formed on at least one substrate. At this time, the compensation film and polarizer are preferably composed as one.

In the multi-domain LCD, the aperture ratio is enhanced by an optimum structure design of a n-line"thin film transistor (USP 5,694, 185) so as to reduce power consumption, increase luminance, and lower reflection, thus improving contrast ratio. Aperture ratio is increased by forming the TFT above the gate line and providing a"n-line"TFT. The parasitic capacitor, occurring between the gate bus line and the drain electrode, can be reduced when a TFT having the same channel length as the symmetrical TFT structure is manufactured due to effect of channel length extension.

The multi-domain LCD has a dielectric frame 53 on the pixel electrode and/or common electrode, or an electric field inducing window 51 like a hole or slit in the pixel electrode, passivation layer, gate insulator, color filter layer, and/or common electrode by patterning, thereby electric field distortion effect and multi-domain are obtained.

That is, from forming electric field inducing window 51 or dielectric frame 53, the multi-domain is obtained by dividing each pixel into four domains such as in a"+","x", or"double Y"shape, or dividing each pixel horizontally, vertically, and/or diagonally, and differently alignmenttreating or forming alignment directions on each domain and on each substrate.

Figs. 27,28, 29,30, 31,32, 33,34, 35, 36, and 37 are plan views showing various electric field inducing window and dielectric frame of the multi-domain liquid crystal display devices according to embodiments of the present invention.

In the figures, the solid lined-arrow represents an alignment direction of the second substrate, and the dotted lined-arrow represents an alignment direction of the first substrate.

Further, the dielectric frame 53 and at least one electric field inducing window 51 are patterned in various shapes, which obtains multi-domain effect. The electric field inducing window may be a slit or hole. Furthermore, neighboring two pixels and two alignment directions are associated, which obtains multi-domain effect.

As shown in the figures, the eleventh embodiment of the present invention has a plurality of dielectric frames 53 having a zigzag shape in a pixel on one substrate between the first and second substrates. And a plurality of electric field inducing windows 51 are formed in various shapes on the first and second substrate. In addition, a plurality of auxiliary electrodes 27 were formed corresponding to the electric field inducing windows 51 of the pixel electrode 13 on the same layer where the gate bus lines were formed.

In multi-domain LCD, an alignment layer (not shown in the figure) is formed over the whole first and/or second substrates. The alignment layer includes a material such as polyamide or polyimide based materials, PVA (polyvinylalcohol), polyamic acid or SiO2. When rubbing is used to determine an alignment direction, it should be possible to apply any material suitable for the rubbing treatment.

That is, the multi-domain is obtained by dividing each pixel into four domains such as in a"+"or"x shape, or dividing each pixel horizontally, vertically, and/or diagonally, and differently alignment-treating or forming alignment directions on each domain and on each substrate.

Consequently, since the multi-domain LCD forms the dielectric frame in a region except the pixel region and the electric field inducing window in the pixel region, electric field is distorted and multi-domain effect is obtained.

Moreover, the dielectric frame is used as a light shielding layer or spacer, which could obtain simplify of manufacturing processes and a high aperture ratio.

Also, in the case of conducting an alignment-treatment, a high response time and a stable LC structure can be obtained by a pretilt angle and an anchoring energy.

Moreover, the disclination is thus removed to thereby improve the brightness.

It will be apparent to those skilled in the art that various modifications can be made in the liquid crystal display device of the present invention without departing from the sprit or scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A multi-domain liquid crystal display device comprising : first and second substrates facing each other; a liquid crystal layer between said first and second substrates; a plurality of gate bus lines arranged in a first direction on said first substrate and a plurality of data bus lines arranged in a second direction on said first substrate to define a pixel region; a pixel electrode electrically charged through said data bus line in said pixel region; a color filter layer on said second substrate; a common electrode on said color filter layer; dielectric frames in said pixel region; an auxiliary electrode in an area except said pixel region; and an alignment layer on ac least one substrate between said first and second substrates.

2. The multi-domain liquid crystal display device according to claim L, wherein said auxiliary electrode is on a layer on which said pixel electrode is formed.

3-The multi-domain liquid crystal display device according to claim 1 or 2, wherein said auxiliary electrode is on a layer on which said gate bus lines are formed.

4-The multi-domain liquid crystal display device according to any one of claims 1 to 3 wherein said auxiliary electrode is electrically connected to said common electrode.

5. The multi-domain liquid crystal display device according to any one of'claims. 1 to 4, wherein said auxiliary electrode includes a material selected from the group consisting of ITO (indium tin oxide), aluminum, molybdenum, chromium, tantalum, titanium, and an alloy thereof.

6. The multi-domain liquid crystal display device according to any one of claims 1 to 5, wherein said common electrode has an electric field inducing window inside of itself.

7. The multi-domain liquid crystal display device according to any one of claims 1 to 6, wherein said pixel electrode has an electric field inducing window inside of itself.

8. The multi-domain liquid crystal display device according to any one of claims 1 to 7, wherein said pixel region is divided into at least two portions, liquid crystal molecules in said liquid crystal layer in each portion being driven differently from each other.

9. The multi-domain liquid crystal display device according to any one of claims 1 to 8, wherein said alignment layer is divided into at least two portions, liquid crystal molecules in said liquid crystal layer in each portion being aligned differently from each other.

10. The multi-domain liquid crystal display device according to any one of claims 1 to 9, wherein said dielectric frame is a spacer.

11. The multi-domain liquid crystal display device according to anyone of claims 1 to 10, further comprising: a light shielding layer on said first substrate.

12. A multi-domain liquid crystal display device comprising : first and second substrates facing each other ; a liquid crystal layer between said first and second substrates ; a plurality of gate bus lines arranged in a first direction on said first substrate and a plurality of data bus lines arranged in a second direction on said first substrate to define a pixel region ; a pixel electrode electrically charged through said data bus line in said pixel region ; a light shielding layer in an area except said pixel region on said first substrate ; a color filter layer on said second substrate ; a common electrode on said color filter layer ; dielectric frames in said pixel region ; and an alignment layer on at least one substrate between said first and second substrates.

13. The multi-domain liquid crystal display device according to claim 12, further comprising : an auxiliary electrode in an area except said pixel region.

14. The multi-domain liquid crystal display device according to claim 12 or 13, wherein said common electrode has an eleccric field inducing window inside of itself.

15. The multi-domain liquid crystal display device according to claim 12,13 or 14, wherein said pixel electrode has an electric field inducing window inside of itself.

16. The multi-domain liquid crystal display device according to claim 12,13, 14 or 15, wherein said dielectric frame is a spacer.

17-A multi-domain liquid crystal display device comprising: first and second substrates facing each other ; a liquid crystal layer between said first and second substrates ; a plurality of gate bus lines arranged in a first direction on said first substrate and a plurality of data bus lines arranged in a second direction on said first substrate to define a pixel region; a pixel electrode electrically charged through said data bus line in said pixel region ; a color filter layer on said second substrate; a common electrode on said color filter layer ; dielectric frames in said pixel region; an electric field inducing window in said pixel region; and an alignment layer on at least one substrate between said first and second substrates.

18. The multi-domain liquid crystal display device according co claim 12, further comprising :

an auxiliary electrode in an area except said pixel region.

19. The multi-domain liquid crystal display device according to claim 17 or 18, wherein said dielectric frame is a spacer.

20. The multi-domain liquid crystal display device according to claim 17,18 or 19, further comprising: a light shielding layer in an area except said pixel region on said first substrate.

21. A multi-domain liquid crystal display device comprising: first and second substrates facing each other; a liquid crystal layer between said first and second substrates ; a plurality of gate bus lines arranged in a first direction on said first substrate and a plurality of data bus lines arranged in a second direction on said first substrate to define a pixel region; a pixel electrode electrically charged through said data bus line in said pixel region; a color filter layer on said second substrate; a common electrode on said color filter layer; dielectric frames in said pixel region as a spacer ; and an alignment layer on at least one substrate between said first and second substrates.

22. The mti-domain liquid crystal display device according to claim, 21, wherein said common electrode has an electric field inducing window inside of itself.

23. The multi-domain liquid crystal display device according to claim 21 or 22, wherein said pixel electrode has an electric field inducing window inside of itself.

24. The multi-domain liquid crystal display device according

to claim 21, 22 or 23, further comprising : an auxiliary electrode in an area except said pixel region.

25. The multi-domain liauid crystal display device according to claim 21,22, 23 or 24, further comprising: a light shielding layer in an area except said pixel region on said first substrate.

26. A multi-domain liquid crystal display device comprising: a plurality of data bus lines in which data signal is provided; a plurality of gate bus lines crossed said data bus lines to define a pixel region; a pixel electrode driving a liquid crystal layer; dielectric frames in said pixel region; and a light shielding layer in an area except said pixel region.

27. The multi-domain liquid crystal display device according to claim 26, further comprising: an auxiliary electrode in an area except said pixel region.

28. The multi-domain liquid crystal display device according to claim 26, further comprising : an electric field inducing window in said pixel region.