KR20170132025A - Liquid crystal display device including light valve panel - Google Patents

Abstract

The present invention relates to a liquid crystal display apparatus. According to the present invention, an upper alignment layer of a light valve panel including dichroic dyes is formed to be directly contact with a lower polarizing plate of the liquid crystal panel or formed on an upper part thereof while interposing a common electrode therebetween, thereby having an improved contrast ratio and minimizing a thickness increase.

Description

[0001] The present invention relates to a liquid crystal display device including a light valve panel,

The present invention relates to a liquid crystal display device, and more particularly to a thin liquid crystal display device including a light valve panel and having a high contrast ratio.

Generally, the driving principle of a liquid crystal display device utilizes the optical anisotropy and polarization properties of a liquid crystal. Since the liquid crystal has a long structure, it has a directionality in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal.

Therefore, when the molecular alignment direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light is refracted in the molecular alignment direction of the liquid crystal by optical anisotropy, so that image information can be expressed.

An active matrix liquid crystal display (AM-LCD: hereinafter referred to as liquid crystal display) in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner has been attracting attention due to its excellent resolution and video realization capability .

The liquid crystal display device includes a liquid crystal panel and a backlight unit positioned below the liquid crystal panel to supply light.

The liquid crystal panel includes a liquid crystal layer, a pixel electrode for driving the liquid crystal layer, and a common electrode.

For example, in a transverse electric field type liquid crystal display device, the pixel electrode and the common electrode are formed on the same substrate, and the liquid crystal layer is driven by a horizontal electric field therebetween. Therefore, a liquid crystal display device having a wide viewing angle can be realized.

However, in a transverse electric field type liquid crystal display device, a light leakage occurs in a black state, and a contrast ratio is lowered.

SUMMARY OF THE INVENTION The present invention aims to solve the low contrast ratio problem of a liquid crystal display device.

According to an aspect of the present invention, there is provided a liquid crystal display device including a light valve panel disposed between a liquid crystal panel and a backlight unit, the liquid crystal layer including a dichroic dye and the upper alignment layer contacting a lower polarizer of the liquid crystal panel. Device.

The present invention also provides a liquid crystal display device including a light valve panel positioned between a liquid crystal panel and a backlight unit, wherein the liquid crystal layer includes a dichroic dye and the upper alignment layer is positioned below a lower polarizer of the liquid crystal panel through a common electrode. Lt; / RTI >

The liquid crystal display of the present invention includes a light valve panel capable of shielding light between a liquid crystal panel and a backlight unit. In a black state, light from the backlight unit is blocked by the light valve panel, thereby improving the contrast ratio.

In addition, since the liquid crystal layer of the light valve panel functions as a polarizing filter including a dichroic dye, the polarizing plate of the light valve panel can be omitted.

Further, the upper substrate of the light valve panel can be omitted by forming the upper alignment film of the light valve panel directly on the lower polarizer plate of the liquid crystal panel or through the common electrode by the low-temperature process.

Therefore, the present invention can provide a thin liquid crystal display device including a light valve panel and having a high contrast ratio.

1 is a schematic cross-sectional view of a liquid crystal display device including a light valve panel according to a first embodiment of the present invention.
2 is a schematic cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention.
3A and 3B are schematic cross-sectional views for explaining light transmission and blocking of the light valve panel.
4 is a schematic cross-sectional view of a liquid crystal display device according to a third embodiment of the present invention.
5 is a schematic cross-sectional view of a liquid crystal display device according to a fourth embodiment of the present invention.

The present invention provides a liquid crystal display device comprising first and second substrates facing each other with a first liquid crystal layer interposed therebetween, a first polarizing plate positioned outside the first substrate and having a first absorption axis, And a second polarizing plate having a second absorption axis perpendicular to the first absorption axis, a backlight unit positioned below the liquid crystal panel, and a liquid crystal panel located between the liquid crystal panel and the backlight unit, 3 pixel electrodes and common electrodes alternately arranged on the substrate; A second alignment layer disposed on the third substrate, a second liquid crystal layer positioned on the first alignment layer and including liquid crystal molecules and a dichroic dye, and a second alignment layer disposed on the second liquid crystal layer and in contact with the first polarizer, And a light valve panel including the light valve panel.

According to another aspect of the present invention, there is provided a liquid crystal display comprising: first and second substrates facing each other with a first liquid crystal layer interposed therebetween; a first polarizing plate located outside the first substrate and having a first absorption axis; And a second polarizer having a second absorption axis perpendicular to the first absorption axis, a backlight unit positioned below the liquid crystal panel, and a third polarizer positioned between the liquid crystal panel and the backlight unit, A pixel electrode on the third substrate; A second alignment layer on the second alignment layer; and a second alignment layer on the second alignment layer, the second alignment layer being disposed on the first alignment layer, the second alignment layer being disposed on the second alignment layer, And a light valve panel including a common electrode which is in contact with the first polarizing plate.

In the liquid crystal display device of the present invention, the long axis of the dichroic dye and the long axis of the liquid crystal molecule may be arranged parallel to each other.

In the liquid crystal display device of the present invention, the long axis of the dichroic dye and the first absorption axis may be perpendicular to each other on the same plane.

In the liquid crystal display device of the present invention, the third substrate may directly face the backlight unit.

In the liquid crystal display device of the present invention, the second alignment layer may be formed of a polyimide in which adjacent nitrogen elements are bonded by a C10-C30 chain alkyl group.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a schematic cross-sectional view of a liquid crystal display device including a light valve panel according to a first embodiment of the present invention.

1, a liquid crystal display device 1 includes a liquid crystal panel 10, a backlight unit (not shown) located under the liquid crystal panel 10, a liquid crystal panel 10, And a light valve panel (30) located between the light valve panel (30).

The liquid crystal panel 10 includes first and second substrates 12 and 14 facing each other and first and second substrates 12 and 14 disposed between the first and second substrates 12 and 14, A liquid crystal layer 16 and first and second polarizers 20 and 22 located outside the first and second substrates 12 and 14, respectively.

Though not shown, a thin film transistor, a pixel electrode connected to the thin film transistor, and a common electrode spaced apart from the pixel electrode are formed on the first substrate 12. In addition, a black matrix and a color filter layer are formed on the second substrate 14.

First and second alignment films are formed on the first and second substrates 12 and 14 so as to be in contact with the first liquid crystal layer 16. The first and second alignment films are formed on the first and second substrates 12 and 14, The initial arrangement of the liquid crystal molecules 18 is determined. An antistatic layer may be formed between the second substrate 14 and the second polarizing plate 22 or outside the second polarizing plate 22.

The light valve panel 30 includes third and fourth substrates 32 and 34 facing each other and a second liquid crystal layer 38 disposed between the third and fourth substrates 32 and 34 and containing the second liquid crystal molecules 38. [ A second liquid crystal layer 36, and a third polarizer 40 positioned outside the third substrate 32.

The absorption axis of the first polarizing plate 20 is perpendicular to the absorption axis of the second and third polarizing plates 22 and 40.

Although not shown, a thin film transistor, a pixel electrode connected to the thin film transistor, and a common electrode spaced apart from the pixel electrode are formed on the third substrate 32. Third and fourth alignment films are formed on the third and fourth substrates 32 and 34, respectively, in contact with the second liquid crystal layer 36. The third and fourth alignment films form the second The initial arrangement of the liquid crystal molecules 38 is determined.

The liquid crystal panel 10 and the light valve panel 30 are attached to each other by an adhesive layer 50. That is, the first polarizer 20 of the liquid crystal panel 10 and the fourth substrate 34 of the light valve panel 30 are attached to each other by the adhesive layer 50.

In such a liquid crystal display device 1, since the light from the backlight unit (not shown) located under the light valve panel 30 is selectively transmitted or blocked by driving the light valve panel 30, The contrast ratio of the liquid crystal display device 1 including the electric field type liquid crystal panel 10 can be improved.

However, since the light valve panel 30 of the liquid crystal display device 1 according to the first embodiment of the present invention includes the two substrates 32 and 34 and the polarizing plate 40, the thickness of the liquid crystal display device 1 There arises a problem that a large increase in the amount of water is caused.

2 is a schematic cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention.

2, the liquid crystal display 100 of the present invention includes a liquid crystal panel 110, a backlight unit 142 positioned below the liquid crystal panel 110, a liquid crystal panel 110, And a light valve panel 130 positioned between the backlight unit 142 and selectively transmitting or blocking light from the backlight unit 142.

The liquid crystal panel 110 includes first and second substrates 112 and 114 facing each other and first and second substrates 112 and 114 that are disposed between the first and second substrates 112 and 114, A first liquid crystal layer 116 and first and second polarizers 120 and 122 located outside the first and second substrates 112 and 114, respectively. The first and second polarizing plates 120 and 122 have absorption axes perpendicular to each other.

Although not shown, a thin film transistor, a pixel electrode connected to the thin film transistor, and a common electrode spaced apart from the pixel electrode are formed on the first substrate 112. In addition, a black matrix and a color filter layer are formed on the second substrate 114.

First and second alignment layers are formed on the first and second substrates 112 and 114 to be in contact with the first liquid crystal layer 116. The first and second alignment layers are formed by the first and second alignment layers, The initial arrangement of the liquid crystal molecules 118 is determined. An antistatic layer may be formed between the second substrate 114 and the second polarizing plate 122 or outside the second polarizing plate 122.

The light valve panel 130 includes third and fourth substrates 132 and 134 facing each other and second liquid crystal molecules 138 positioned between the third and fourth substrates 132 and 134, And a second liquid crystal layer 136 including a liquid crystal layer 139.

The dichroic dye 139 is arranged in parallel with the second liquid crystal molecules 138 and blocks linearly polarized light in a specific direction. That is, the dichroic dye 139 has a long axis and a short axis, and the long axis thereof is arranged parallel to the long axis of the second liquid crystal molecules 138. At this time, the direction of the long axis of the initial alignment of the dichroic dye 139 and the absorption axis of the first polarizer 120 are perpendicular to each other on the same plane. Accordingly, the polarizing plate (40 in Fig. 1) of the light valve panel can be omitted.

Though not shown, a thin film transistor, a pixel electrode connected to the thin film transistor, and a common electrode spaced apart from the pixel electrode are formed on the third substrate 132. Third and fourth alignment layers are formed on the third and fourth substrates 132 and 134 to be in contact with the second liquid crystal layer 136. The third and fourth alignment layers The initial arrangement of the liquid crystal molecules 138 and the dichroic dye 139 is determined.

The liquid crystal panel 110 and the light valve panel 130 are attached to each other by an adhesive layer 140. That is, the first polarizer 120 of the liquid crystal panel 110 and the fourth substrate 134 of the light valve panel 130 are attached to each other by the adhesive layer 150.

In the liquid crystal display device 100 of the present invention, the light valve panel 130 does not include a polarizer. That is, the third substrate 132, which is the lower substrate of the light valve panel 130, directly faces the backlight unit 142.

3A and 3B are schematic cross-sectional views for explaining light transmission and blocking of the light valve panel.

3A, in the OFF state of the light valve panel 130 where no electric field is formed between the pixel electrode 144 and the common electrode 146, the first and second alignment films 145 and 147 The longitudinal axes of the second liquid crystal molecules 138 and the dichroic dye 139 are arranged perpendicular to the direction of the light provided from the backlight unit 142 (FIG. 2).

The first linearly polarized light L1 of the light from the backlight unit 142 is blocked by the dichroic dye 139 and the second linearly polarized light L2 passes through the second liquid crystal layer 136, 2) 110 and is blocked by the first polarizing plate (120 in Fig. 2) having an absorption axis which is the same as the polarization direction of the second linearly polarized light (L2). That is, in the off state, the light valve panel 130 functions to block light.

3B, in the ON state of the light valve panel 130 in which an electric field is formed between the pixel electrode 144 and the common electrode 146, the second liquid crystal molecules 138 and the dichroic The long axis of the dye 139 is arranged parallel to the direction of light provided from the backlight unit (142 in Fig. 2).

Therefore, the first linearly polarized light L1 of the light from the backlight unit 142 is absorbed by the second liquid crystal layer 136 and the liquid crystal panel (110 of FIG. 2) and perpendicular to the polarization direction of the first linearly polarized light L1 And the second linearly polarized light L2 passes through the second liquid crystal layer 136 and then passes through the first polarizer plate 120 having the same absorption axis as the polarization direction of the second linearly polarized light L2, (120). That is, in the off state, the light valve panel 130 serves as a light transmission.

In other words, the light valve panel 130 of the present invention selectively transmits or blocks light without the polarizing plate (40 in FIG. 1) by the liquid crystal layer 136 including the dichroic dye 139. Accordingly, the liquid crystal display 100 of the present invention can include the light valve panel 130 to have an improved contrast ratio and reduce the thickness increase thereof.

4 is a schematic cross-sectional view of a liquid crystal display device according to a third embodiment of the present invention.

4, the liquid crystal display 200 according to the present invention includes a liquid crystal panel 210, a backlight unit 142 (see FIG. 2) positioned below the liquid crystal panel 210, And a light valve panel 310 disposed between the backlight unit 142 and the backlight unit 142 and selectively transmitting or blocking light from the backlight unit 142.

The liquid crystal panel 210 includes first and second substrates 212 and 214 facing each other and first and second substrates 212 and 214 that are located between the first and second substrates 212 and 214, A first liquid crystal layer 216 and first and second polarizers 220 and 222 located outside the first and second substrates 212 and 214, respectively. The first and second polarizing plates 220 and 222 have absorption axes perpendicular to each other.

A thin film transistor Tr, a pixel electrode 260, a common electrode 262, and a first alignment layer 264 are formed on the first substrate 212.

More specifically, a gate electrode 232 is formed on the first substrate 212 and a gate insulating film 234 covering the gate electrode 232 is formed on the entire surface of the first substrate 212. Further, a gate wiring (not shown) connected to the gate electrode 232 and extending in a first direction is formed.

The gate electrode 232 and the gate wiring may be made of a low resistance metal material such as copper, aluminum, molybdenum, or an alloy thereof, and the gate insulating film 234 may be made of an inorganic insulating material such as silicon oxide or silicon nitride .

A semiconductor layer 236 is formed on the gate insulating layer 234 in correspondence with the gate electrode 232. The semiconductor layer 236 may be made of silicon oxide. Alternatively, the semiconductor layer 236 may comprise an active layer of pure amorphous silicon and an ohmic contact layer of impurity amorphous silicon.

On the semiconductor layer 236, a source electrode 240 and a drain electrode 242 which are spaced apart from each other are formed. Data lines (not shown) connected to the source electrode 240 and extending in the second direction are formed on the gate insulating layer 234. The gate wiring and the data wiring cross each other to define a pixel region which is a display unit.

The gate electrode 232, the semiconductor layer 236, the source electrode 240, and the drain electrode 242 constitute a thin film transistor Tr.

A protective layer 250 having a drain contact hole 252 covering the thin film transistor Tr and exposing the drain electrode 242 is formed. The passivation layer 250 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride, or an organic insulating material such as photoacrylic or benzocyclobutene.

A pixel electrode 260 connected to the drain electrode 242 through the drain contact hole 252 and a common electrode 262 alternately arranged with the pixel electrode 260 are formed on the passivation layer 250 do. That is, the pixel electrode 260 and the common electrode 262 are bar-shaped and arranged alternately to form a horizontal electric field.

Alternatively, one of the pixel electrode 260 and the common electrode 262 may have a plate shape and the other may have at least one opening to form a fringe field.

Each of the pixel electrode 260 and the common electrode 262 may be formed of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) Lt; / RTI >

A first alignment layer 264 is formed on the pixel electrode 260 and the common electrode 262.

A black matrix 270 for covering a non-display region, such as the thin film transistor Tr, is formed on a second substrate 214 facing the first substrate 212. That is, the black matrix 270 has a lattice shape including openings corresponding to the pixel regions. A color filter layer 272 is formed corresponding to the opening of the black matrix 270, that is, the pixel region, and an overcoat layer 274 is formed to eliminate steps caused by the color filter layer 272.

On the overcoat layer 274, a second alignment layer 276 is formed.

A first liquid crystal layer 216 including first liquid crystal molecules 218 is formed between the first and second substrates 212 and 214 and more precisely between the first and second alignment films 264 and 276 And the initial alignment of the first liquid crystal molecules 218 is determined by the first and second alignment films 264 and 276. Each of the first and second alignment layers 264 and 276 may be formed of polyimide.

The first and second polarizers 220 and 222 located outside the first and second substrates 212 and 214 have absorption axes perpendicular to each other and are made of polyvinyl alcohol (PVA).

The light valve panel 310 located below the liquid crystal panel 210 includes a third substrate 312, a thin film transistor Tr sequentially stacked on the third substrate 312, a pixel electrode 360, A third alignment layer 364, a second liquid crystal layer 336, a fourth alignment layer 376 and a common electrode 380. The common electrode 380 is formed of a liquid crystal material, 1 polarizer plate 220 in the same manner.

That is, the light valve panel 310 of the liquid crystal display device 200 according to the third embodiment of the present invention does not include the fourth substrate (134 in FIG. 2), and the common electrode 380 and the fourth alignment film 376 Are sequentially formed on the first polarizer 220 of the liquid crystal panel 210. [

The thin film transistor Tr includes a gate electrode 332, a semiconductor layer 336, a source electrode 340 and a drain electrode 342. A gate insulating film (gate electrode) 332 is formed between the gate electrode 332 and the semiconductor layer 336 334 are interposed. Further, gate wirings (not shown) and data wirings (not shown) extending in different directions are formed with a gate insulating film 334 therebetween.

A protective layer 350 having drain contact holes 352 covering the thin film transistor Tr and exposing the drain electrodes 342 is formed on the passivation layer 350. The passivation layer 350 is formed on the passivation layer 350 through the drain contact hole 352, A pixel electrode 360 having a plate shape is formed.

The third alignment layer 364 covers the pixel electrode 360 and corresponds to the front surface of the third substrate 312.

The fourth alignment layer 376 is disposed apart from the third alignment layer 364 and the second liquid crystal molecules 338 and the second liquid crystal molecules 339 including the dichroic dye 339 are disposed between the third and fourth alignment layers 364 and 376, The liquid crystal layer 336 is located. The initial alignment of the second liquid crystal molecules 338 and the dichroic dye 339 is determined by the third and fourth alignment layers 364 and 376, and their long axes are arranged in the same direction.

A common electrode 380 is disposed on the rear surface of the fourth alignment layer 376 and a vertical electric field is formed between the pixel electrode 360 and the common electrode 380 to form the second liquid crystal molecules 338 and the dichroic dye 339, .

At this time, the common electrode 380 is formed by a room temperature deposition process, and the fourth alignment layer 376 is formed by coating an amic acid represented by the following chemical formula, followed by a sintering process and an alignment process.

In the above formula, R 1 may be a C 4 or higher cyclic group. For example, R1 may be cyclobutane or benzene.

Further, the R2 is a C10 to C30 or more chain alkyl. Accordingly, in the polyimide formed by polymerization of the amic acid represented by the above formula, adjacent nitrogen (N) atoms are bonded by C10 or more chain alkyl, and the firing process for polymerization of amic acid proceeds at a temperature of 200 ° C or lower .

Generally, the alignment film requires a firing step at 230 DEG C or higher. Therefore, when such an alignment film is formed on or above the polarizing plate, the polarizing plate is damaged by the high-temperature process.

However, since the fourth alignment layer 376 of the present invention includes the C10 or higher chain alkyl and is formed by the polymerization of amic acid, the low temperature baking process can be performed, and the fourth alignment layer 376 May be formed on the first polarizing plate 220.

Since the first to third alignment films 376 are not formed on or above the polarizing plate, the alignment process temperature is not limited. Accordingly, the first to third alignment layers 376 may be composed of polyimide in which adjacent nitrogen atoms are bonded by a C10-C30 chain alkyl group or C5-C6 chain alkyl group.

Since the second alignment film 376 of the light valve panel 310 is directly formed on the first polarizer 220 of the liquid crystal panel 210 in the liquid crystal display device 200 according to the third embodiment of the present invention, The light valve panel 30 of the liquid crystal display (1 of FIG. 1) and the light valve panel 130 of the liquid crystal display (100 of FIG. 2) according to the second embodiment of the present invention according to the first embodiment of the present invention It is possible to omit the fourth substrate 34, 134 which is required in the first embodiment.

3A and 3B, since the second liquid crystal layer 336 of the light valve panel 310 includes the dichroic dye 339, the liquid crystal display according to the first embodiment of the present invention The polarizer 40 required in the light valve panel 30 of the apparatus (1 in Fig. 1) can also be omitted.

Accordingly, the liquid crystal display device 200 according to the third embodiment of the present invention may include the light valve panel 310 to minimize an increase in the thickness thereof with an improved contrast ratio.

4, the third substrate 312 of the light valve panel 310 does not include the polarizing plate (40 of FIG. 1) and the third substrate 312 of the light valve panel 310 faces the backlight unit . Alternatively, a polarizer may be disposed outside the third substrate 312. That is, the polarizer may be positioned between the third substrate 312 of the light valve panel 310 and the backlight unit 142 (see FIG. 2).

5 is a schematic cross-sectional view of a liquid crystal display device according to a fourth embodiment of the present invention.

5, a liquid crystal display 400 according to the present invention includes a liquid crystal panel 410, a backlight unit 142 (see FIG. 2) positioned below the liquid crystal panel 410, And a light valve panel 510 disposed between the backlight unit 142 and the backlight unit 142 and selectively transmitting or blocking light from the backlight unit 142.

The liquid crystal panel 410 includes first and second substrates 412 and 414 facing each other and first and second substrates 412 and 414 disposed between the first and second substrates 412 and 414, A first liquid crystal layer 416 and first and second polarizers 420 and 422 located outside the first and second substrates 412 and 414, respectively. The first and second polarizing plates 420 and 422 have absorption axes perpendicular to each other.

A thin film transistor (Tr in FIG. 4), a pixel electrode 460, a common electrode 462, and a first alignment film 464 are formed on the first substrate 412. That is, the pixel electrode 460 and the common electrode 462 are positioned above the first substrate 412 with the gate insulating film 434 and the protective layer 450 interposed therebetween.

On the other hand, a black matrix (270 in FIG. 4), a color filter layer 472, and an overcoat layer 474 are formed on the second substrate 414 facing the first substrate 412. A second alignment layer 476 is formed on the overcoat layer 474.

A first liquid crystal layer 416 including first liquid crystal molecules 418 is formed between the first and second substrates 412 and 414 and more precisely between the first and second alignment layers 464 and 476 And the initial alignment of the first liquid crystal molecules 418 is determined by the first and second alignment layers 464 and 476. Each of the first and second alignment layers 464 and 476 may be formed of polyimide.

The first and second polarizers 420 and 422 located on the outer sides of the first and second substrates 412 and 414 respectively have absorption axes perpendicular to each other and are made of polyvinyl alcohol (PVA).

The light valve panel 510 located below the liquid crystal panel 410 includes a pixel electrode 560 and a third substrate 512 having a common electrode 562 and a third alignment layer 564 formed thereon. The pixel electrode 560 and the common electrode 562 are arranged in the same layer above the third substrate 512 via the gate insulating layer 534 and the protective layer 550. Alternatively, one of the pixel electrode 560 and the common electrode 562 may have a plate shape and the other may have at least one opening.

The fourth alignment layer 576 is formed on the third alignment layer 564 of the third substrate 512 in such a manner that a second liquid crystal layer 536 and a fourth alignment layer 576 are sequentially formed on the third alignment layer 564, Of the first polarizing plate 420.

That is, the light valve panel 510 of the liquid crystal display device 400 according to the fourth embodiment of the present invention does not include the fourth substrate (134 in FIG. 2), and the fourth alignment film 576 does not include the liquid crystal panel 410 Of the first polarizing plate 420 of the first polarizing plate 420.

As described above, the fourth alignment film 576 is formed of a polyimide in which adjacent nitrogen (N) atoms are bonded by C10 or more chain alkyl. Since such a polyimide can be formed by a sintering process at 200 DEG C or less The fourth alignment layer 576 can be formed on the first polarizing plate 420 without damaging the first polarizing plate 420.

Since the second alignment film 576 of the light valve panel 510 is directly formed on the first polarizing plate 420 of the liquid crystal panel 410 in the liquid crystal display device 400 according to the fourth embodiment of the present invention, The light valve panel 30 of the liquid crystal display (1 of FIG. 1) and the light valve panel 130 of the liquid crystal display (100 of FIG. 2) according to the second embodiment of the present invention according to the first embodiment of the present invention It is possible to omit the fourth substrate 34, 134 which is required in the first embodiment.

3A and 3B, since the second liquid crystal layer 536 of the light valve panel 510 includes the dichroic dye 539, the liquid crystal display according to the first embodiment of the present invention The polarizer 40 required in the light valve panel 30 of the apparatus (1 in Fig. 1) can also be omitted.

Accordingly, the liquid crystal display device 400 according to the fourth embodiment of the present invention can include the light valve panel 510 to have an improved contrast ratio and minimize the thickness increase.

In the liquid crystal display device 400 according to the fourth embodiment of the present invention, since the common electrode 562 of the light valve panel 510 is formed on the same layer as the pixel electrode 560, A separate process for forming the common electrode (380 in Fig. 4) can be omitted in comparison with the liquid crystal display device 400. [

5, the light valve panel 510 does not include the polarizer 40 (see FIG. 1) and the third substrate 512 of the light valve panel 510 is directly opposed to the backlight unit . Alternatively, a polarizer may be disposed outside the third substrate 512. That is, the polarizer may be positioned between the third substrate 512 of the light valve panel 510 and the backlight unit 142 (see FIG. 2).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It can be understood that

1, 100, 200, 400: liquid crystal display device 10, 110, 210, 410: liquid crystal panel
30, 130, 310, 510: light valve panel 142: backlight unit
12, 14, 32, 34, 112, 114, 132, 134, 212, 214, 312, 412, 414,
16, 36, 116, 136, 216, 336, 416, 536:
18, 38, 118, 138, 218, 338, 418, 538: liquid crystal molecules
119, 339, 539: dichroic dyes
145, 147, 264, 276, 364, 376, 464, 476, 564, 576:
20, 22, 40, 120, 122, 220, 222, 420, 422: polarizer

Claims (6)

A liquid crystal display device comprising: first and second substrates facing each other with a first liquid crystal layer interposed therebetween; a first polarizer disposed on the outer side of the first substrate and having a first absorption axis; A second polarizing plate having a second absorption axis perpendicular to the first polarizing plate;
A backlight unit positioned below the liquid crystal panel;
A pixel electrode and a common electrode which are located between the liquid crystal panel and the backlight unit and are alternately arranged on the third substrate, the third substrate, A second alignment layer disposed on the third substrate, a second liquid crystal layer positioned on the first alignment layer and including liquid crystal molecules and a dichroic dye, and a second alignment layer disposed on the second liquid crystal layer and in contact with the first polarizer, And a light valve panel
And the liquid crystal display device.
A liquid crystal display device comprising: first and second substrates facing each other with a first liquid crystal layer interposed therebetween; a first polarizer disposed on the outer side of the first substrate and having a first absorption axis; A second polarizing plate having a second absorption axis perpendicular to the first polarizing plate;
A backlight unit positioned below the liquid crystal panel;
A third substrate, a pixel electrode on the third substrate, the pixel electrode being located between the liquid crystal panel and the backlight unit; A second alignment layer on the second alignment layer; and a second alignment layer on the second alignment layer, the second alignment layer being disposed on the first alignment layer, the second alignment layer being disposed on the second alignment layer, A light valve panel including a common electrode in contact with the first polarizer plate,
And the liquid crystal display device.
3. The method according to claim 1 or 2,
Wherein the long axis of the dichroic dye and the long axis of the liquid crystal molecule are arranged in parallel to each other.
3. The method according to claim 1 or 2,
Wherein the long axis of the dichroic dye and the first absorption axis are perpendicular to each other on the same plane.
3. The method according to claim 1 or 2,
And the third substrate directly faces the backlight unit.
3. The method according to claim 1 or 2,
Wherein the second alignment layer comprises a polyimide in which adjacent nitrogen elements are bonded by C10 to C30 chain alkyl groups.

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