KR20160127856A - Fringe - Field Switching Liquid Crystal Displays and method of preparing the same - Google Patents

Abstract

The present invention relates to a fringe field switching liquid crystal displaying device and a method for manufacturing the same capable of implementing high image quality by preventing a penetration ratio interference phenomenon between pixel areas. The FFS liquid crystal displaying device is provided to form a polymer network between pixel areas, thereby preventing distortion of light in device driving by maintaining a dark state without moving liquid crystal between the pixel areas after applying driving voltage. The liquid crystal displaying device shortens process time generated for BM manufacture and installation; saves process costs; and improves a process yield by minimizing or not using BM of an upper substrate.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a fringe field switching liquid crystal display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fringe field switching liquid crystal display and a method of manufacturing the same, and more particularly, to a fringe field switching liquid crystal display capable of preventing a transmittance interference phenomenon between a pixel region and a pixel region, .

Currently, twisted nematic (TN) mode is a liquid crystal mode that is widely applied to small and medium sized liquid crystal display devices such as a monitor, a notebook computer, and a mobile phone. TN mode is widely applied not only for high optical efficiency but also for high process yield. However, TN mode has a disadvantage that the viewing angle is narrow because the liquid crystal molecules move in the vertical direction when voltage is applied. An in-plane switching (IPS) mode and a fringe field switching (FFS) mode using a horizontal electric field have been developed to solve the narrow viewing angle problem.

Both modes have better viewing angles than the TN mode because the liquid crystal molecules rotate in one direction parallel to the substrate. However, in the case of the IPS mode, the liquid crystal molecules are not rotated at the upper portion of the electrode, thereby lowering the light efficiency, the driving voltage is high, and the color shift problem due to the viewing angle. In order to solve various problems of the IPS mode, an FFS mode has been proposed. FIG. 1 is a graph showing a conventional FFS mode, FIG. 2 is a graph showing a transmittance interference phenomenon in a conventional FFS mode, and FIG. 3 is a 3D simulation of a transmittance interference phenomenon in the conventional FFS mode. 1, the FFS mode is a mode in which the lower polarizer 10, the lower substrate 20, the organic film 30, the common electrode 50, and the pixel electrode 70 are sandwiched by the transparent electrode structure The horizontal gap between the common electrode and the pixel electrode is narrower than the cell gap between the upper and lower substrates to form a strong fringe electric field between the common electrode and the pixel electrode so that the liquid crystal molecules And exhibits high optical efficiency, low voltage driving, and wide viewing angle characteristics. However, in spite of these advantages, as shown in FIG. 2 and FIG. 3, in the FFS mode, a noise voltage is undesirably applied between the data signal electrode and the pixel electrode, and since the liquid crystal reacts with this voltage, . To solve this problem, the width of the black matrix 100, which can cover the area, must be widened, and as a result, the aperture ratio is reduced.

[Prior Art]

1. Open Patent 10-2012-21373; Fringe Field Switching Liquid Crystal Display

The present invention provides an FFS mode liquid crystal display capable of solving a transmittance interference phenomenon.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and a method for preventing a black matrix formed on an upper substrate or preventing a high transmittance interference phenomenon that minimizes its use.

One aspect of the present invention is

A lower substrate, an upper substrate, and a liquid crystal layer interposed between the substrates,

Wherein each pixel region is defined by gate lines and data lines formed in a direction crossing each other on the lower substrate, a thin film transistor (TFT) is disposed at an intersection of the gate lines and the data lines,

Wherein a common electrode is formed on an upper surface of the lower substrate with an organic film interposed therebetween, and a pixel electrode is formed over the common electrode with an insulating film interposed therebetween,

The pixel electrodes are formed in the red, green, and blue pixel regions, respectively, and a polymer network is formed in the liquid crystal layer between the pixel region and the pixel region, so that the liquid crystal is not driven.

In another aspect,

A lower substrate, an upper substrate, and a liquid crystal layer interposed between the substrates, Wherein the pixel region is defined by gate lines and data lines formed in a direction intersecting with the lower substrate and a thin film transistor (TFT) is disposed at an intersection of the gate lines and the data lines, In the production method of the present invention,

Forming a plurality of TFT wirings over the lower substrate;

Forming an organic film on the lower substrate and the TFT wiring;

Forming a common electrode on the organic layer;

Forming an insulating film on the common electrode;

Forming a pixel electrode in the pixel region above the insulating film;

Attaching the lower substrate and the upper substrate;

Injecting a liquid crystal mixture comprising the liquid crystal, photo-curable monomers and photoinitiator between the lower substrate and the upper substrate; And

And a method of manufacturing a fringe field switching liquid crystal display device that irradiates ultraviolet light only to an area between the pixel area and the pixel area.

 The FFS type liquid crystal display device of the present invention forms a polymer network between the pixel region and the pixel region so that the liquid crystal does not move between the pixel region and the pixel region after the application of the driving voltage and maintains a dark state, It can prevent the phenomenon. Further, since the BM of the upper substrate is used for half or less of the width of the data line (TFT wiring) or the BM is not used, the liquid crystal display of the present invention can reduce the process time and manufacturing cost, Can be improved.

1 shows a conventional FFS mode.
2 is a graph showing the transmittance interference phenomenon in the conventional FFS mode.
3 is a 3D simulation of the transmittance interference phenomenon of the conventional FFS mode.
FIG. 4 shows a liquid crystal display of a fringe field switching mode, which is an embodiment of the present invention.
5 is a top view of the fringe field switching mode of the present invention.
6 shows the formation of a polymer network between the pixel region and the pixel region.

The present invention can be all accomplished by the following description. The following description should be understood to describe preferred embodiments of the present invention, but the present invention is not necessarily limited thereto.

FIG. 4 shows a liquid crystal display of a fringe field switching mode, which is an embodiment of the present invention. 5 is a top view of the fringe field switching mode of the present invention. 4 and 5, the liquid crystal display of the present invention includes a lower substrate 210, an upper substrate 290, and a liquid crystal layer 270 interposed between the substrates.

In the lower substrate 210, pixel regions are defined by gate lines 320 and data lines 310 formed in mutually intersecting directions, and thin film transistors (TFT) are formed at intersections of the gate lines and the data lines. . That is, each pixel region is surrounded by the gate line 320 and the data line 310, and a plurality of pixel electrodes are arranged in the pixel region.

A common electrode 240 is formed on the lower substrate 210 with an organic layer 220 interposed therebetween and a pixel electrode 260 is formed on the common electrode with an insulating layer 270 therebetween. A lower polarizer is formed below the lower substrate 210.

A data line (also referred to as TFT line) 230 of the thin film transistor (TFT) is formed between the pixel region and the pixel region. The data lines 230 and the pixel electrodes 260 are formed at regular intervals.

  The pixel electrode 260 is formed in the red, green, and blue pixel regions A, B, and C, and a polymer network 272 is formed in the liquid crystal layer space D between the pixel region and the pixel region, (271) is not driven.

 The polymer network 272 is formed on the liquid crystal layer above the data line 230 of the thin film transistor TFT.

The polymer network is formed by curing a liquid crystal compound having a polymerizable group, and the liquid crystal is trapped and fixed in the polymer network.

Referring to FIG. 5, a polymer network 272 is formed along the upper side of the data lines 230 and 310, and liquid crystal 271 is trapped and fixed in the polymer network.

The liquid crystal display of the present invention can maintain the dark state without driving the liquid crystal 271 trapped in the polymer network even when power is applied to the liquid crystal layer and can prevent the distortion of the light when driving the device. Therefore, in the liquid crystal display device of the present invention, a black matrix provided to prevent a transmittance interference phenomenon between the pixel region and the pixel region is not used or used as half of the data line width.

In another aspect, the present invention relates to a method of manufacturing a fringe field switching liquid crystal display device. The liquid crystal display of the present invention includes a lower substrate 210, an upper substrate 290, and a liquid crystal layer 270 interposed between the substrates. In the lower substrate 210, pixel regions are defined by gate lines 320 and data lines 310 formed in mutually intersecting directions, and thin film transistors (TFT) are formed at intersections of the gate lines and the data lines. .

First, a plurality of data lines 230 are formed on the lower substrate 210, and an organic layer 220 is formed on the lower substrate and the data lines. The organic film may also be formed between the lower substrate and the data line 230.

A common electrode 240 is formed on the organic layer 220, and an insulating layer 250 is formed on the common electrode 220.

A pixel electrode 260 is formed in the pixel regions A, B, and C on the insulating layer 250. And the upper substrate 290 and the lower substrate 210 to which the color filter 280 is attached.

The manufacturing method of the present invention includes the step of injecting a liquid crystal mixture containing a liquid crystal, a photo-curable monomolecule and a photoinitiator into a liquid crystal layer between the lower substrate and the upper substrate.

There is no limitation on the method of providing the liquid crystal mixture in the liquid crystal layer in the above step. For example, the liquid crystal mixture may be injected onto the lower substrate on which the spacers are formed, and then the upper substrate may be bonded to the lower substrate. After bonding the upper substrate and the lower substrate, a liquid crystal mixture may be injected between the substrates.

The photo-curable monomer is a liquid crystal material including an end group capable of being polymerized by an ultraviolet ray reaction of a photoinitiator. The term " photo-curable monomers " used in the present invention includes a liquid crystal phase containing a mesogen group capable of exhibiting liquid crystallinity and a terminal group capable of photopolymerization, and a monomer molecule capable of being photopolymerized by a photoinitiator . Thus, photocurable monomers can be represented as reactive liquid crystal monomers in more general terms. As the mesogens, calamitic mesogens expressing a nematic liquid crystal phase or discotic mesogens in the form of a plate capable of expressing a discotic liquid crystal phase can be used. As the polymerizable terminal group, an acrylic group or methacrylic group which is generally easy to radical polymerization can be used. For example, the photo-curable monomers usable in the present invention include RM257, EHA, and the like.

As the photoinitiator, trimethylopropane triacrylate or the like may be used.

The liquid crystal mixture may contain 0.01 to 50 parts by weight, preferably 0.1 to 15 parts by weight, of a photopolymerizable monomer per 100 parts by weight of the liquid crystal.

6 shows the formation of a polymer network between the pixel region and the pixel region.

When a liquid crystal mixture is injected, liquid crystal and photo-curable monomers are uniformly dispersed in the liquid crystal layer as shown in FIG.

As shown in FIG. 6B, the present invention irradiates the ultraviolet rays only to the region between the pixel region and the pixel region using the mask 330. FIG. That is, the present invention irradiates the ultraviolet rays to the liquid crystal layer above the thin film transistor (TFT) wiring. As shown in FIG. 6C, when ultraviolet rays are irradiated on the liquid crystal layer, the photopolymerizable monomers move toward the surface on which the ultraviolet light is incident, and polymerization occurs. That is, due to the phase separation phenomenon in the liquid crystal layer due to ultraviolet rays passing through the mask, a polymer network is formed in a space between the pixel region and the pixel region.

The size of the polymer network can be controlled by adjusting the transmission region of the mask. The polymer network may be formed to have a width larger than the transmission area of the mask.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (9)

A lower substrate, an upper substrate, and a liquid crystal layer interposed between the substrates,
Wherein each pixel region is defined by gate lines and data lines formed in a direction crossing each other on the lower substrate, a thin film transistor (TFT) is disposed at an intersection of the gate lines and the data lines,
Wherein a common electrode is formed on an upper surface of the lower substrate with an organic film interposed therebetween, and a pixel electrode is formed on an upper surface of the common electrode with an insulating film interposed therebetween,
Wherein the pixel electrodes are formed in red, green, and blue pixel regions, respectively, and a polymer network is formed in the liquid crystal layer between the pixel region and the pixel region, so that the liquid crystal is not driven. The FFS mode liquid crystal display of claim 1, wherein the polymer network is formed on a liquid crystal layer above a thin film transistor (TFT) line. The FFS mode liquid crystal display of claim 1, wherein the polymer network is formed by curing a liquid crystal compound having a polymerizable group, and the liquid crystal is trapped and fixed in the polymer network. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a black matrix for preventing a transmittance interference phenomenon between a pixel region and a pixel region from being half or less of a data line width, The FFS mode liquid crystal display device. A lower substrate, an upper substrate, and a liquid crystal layer sandwiched between the substrates, wherein each pixel region is defined by gate lines and data lines formed in a direction crossing each other, and the gate lines and data A method of manufacturing a fringe field switching liquid crystal display device in which a thin film transistor (TFT) is disposed at an intersection of lines,
Forming a plurality of TFT wirings over the lower substrate;
Forming an organic film on the lower substrate and the TFT wiring;
Forming a common electrode on the organic layer;
Forming an insulating film on the common electrode;
Forming a pixel electrode in the pixel region above the insulating film;
Attaching the lower substrate and the upper substrate;
Injecting a liquid crystal mixture comprising the liquid crystal, photo-curable monomers and photoinitiator between the lower substrate and the upper substrate; And
Wherein the ultraviolet light is irradiated only to the region between the pixel region and the pixel region. 6. The FFS mode liquid crystal display according to claim 5, wherein the photo-curable monomers are polymerized in a liquid crystal layer between a pixel region and a pixel region to be irradiated with ultraviolet rays to form a polymer network. 6. The FFS mode liquid crystal display as claimed in claim 5, wherein the liquid crystal mixture comprises 0.5 to 15 parts by weight of a photo-curable monomolecule and 0.001 to 5 parts by weight of a photoinitiator, based on 100 parts by weight of the liquid crystal. 6. The FFS mode liquid crystal display of claim 5, wherein the ultraviolet light irradiation step controls the size of the polymer network by adjusting a transmission region of the mask. 6. The FFS mode liquid crystal display according to claim 5, wherein the width of the black matrix is less than 1/2 of the TFT wiring width below the upper substrate.

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