KR20070002465A - Liquid crystal display and fabricating method thehrof - Google Patents

Abstract

An LCD and a manufacturing method are provided to allow liquid crystals to return to an initial orientation state without an alignment layer by forming a liquid crystal layer of a mixture of a liquid crystal layer and a liquid crystal type monomer that forms a liquid crystal network by reacting to an emitted ultraviolet ray. A lower array substrate(170) faces an upper array substrate(160) and is bonded with the upper array substrate. A liquid crystal layer(152) is injected between the bonded upper and lower array substrates, and is initially aligned by a share force applied to the upper and lower array substrates from the outside. A liquid crystal network(200) allows the liquid crystal layer to maintain an initial alignment state. The liquid crystal layer is formed of a mixture of a liquid crystal(152a) having light transmittance controlled by a voltage applied to the upper and lower array substrates, and a liquid crystal type monomer forming the liquid crystal network by an ultraviolet ray.

Description

Liquid crystal display and its manufacturing method {LIQUID CRYSTAL DISPLAY AND FABRICATING METHOD THEHROF}

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

2A and 2B are views showing an alignment film printing apparatus and a rubbing device for forming an alignment film of a conventional liquid crystal display device.

3 shows formation of an alignment film of a liquid crystal display device using an ion beam.

4A to 4C are diagrams for explaining driving of liquid crystals of a liquid crystal display device not having an alignment film.

5 is a diagram in which an electric field is removed after driving a liquid crystal of a liquid crystal display device without an alignment film.

6 illustrates a liquid crystal display according to an exemplary embodiment of the present invention.

7A to 7C are views for explaining a method of manufacturing a liquid crystal display device according to an exemplary embodiment of the present invention step by step.

8A and 8B are views for explaining driving of liquid crystals of an LCD according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

2: upper substrate 4: black matrix

6 color filter 8 upper alignment layer

9 gate electrode 14 semiconductor layer

16 pixel electrode 18 common electrode

32: lower substrate 38: lower alignment layer

40: source electrode 42: ohmic contact layer

44 gate insulating film 47 drain electrode

50: protective film 52: liquid crystal

60, 160: upper array substrate 70, 170: lower array substrate

104: printing roller 106: orientation mask

108: anilox roll 110: dispenser

112: doctor roll 115: ion beam irradiation apparatus

116: Loving Roller 118: Loving Can

120: polarizing plate 152: liquid crystal layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly, to a liquid crystal display device and a method for manufacturing the same, which do not include an alignment layer for maintaining the initial alignment of the liquid crystal, but which allow the liquid crystal to find an initial alignment state after driving the liquid crystal. will be.

In general, a liquid crystal display (LCD) displays an image by adjusting the light transmittance of the liquid crystal according to a video signal. To this end, the liquid crystal display includes a liquid crystal display panel in which liquid crystal cells are arranged in a matrix, and a driving circuit for driving the liquid crystal display panel.

The liquid crystal display is roughly classified into a twisted nematic (TN) mode using a vertical electric field and an in plan switch (IPS) mode using a horizontal electric field according to the electric field driving the liquid crystal.

The TN mode is a mode in which a liquid crystal is driven by a vertical electric field between a pixel electrode and a common electrode disposed to face the upper substrate. The TN mode has a large aperture ratio and a narrow viewing angle. On the other hand, the IPS mode is a mode for driving the liquid crystal by a horizontal electric field between the pixel electrode and the common electrode disposed side by side on the lower substrate has a large viewing angle has a disadvantage of small aperture ratio.

1 is a cross-sectional view showing a conventional TN mode liquid crystal display panel.

Referring to FIG. 1, the liquid crystal display panel of the conventional TN mode includes a black matrix 4, a color filter 6, a common electrode 18, and an upper alignment layer 8 that are sequentially formed on the upper substrate 2. An upper array substrate (or color filter array substrate), a TFT formed on the lower substrate 32, a lower array substrate composed of a pixel electrode 16 and a lower alignment layer 38, an upper array substrate and a lower array substrate It is provided with a liquid crystal (not shown) injected into the internal space therebetween.

Meanwhile, in the IPS mode liquid crystal display panel, the common electrode 18 is formed on the lower substrate 32, and a planarization layer (not shown) is formed on the upper substrate 2 to compensate for the step difference of the color filter 6.

In the upper array substrate, the black matrix 4 is formed on the upper substrate 2 in correspondence with the TFT region of the lower array substrate and the region of the gate lines and data lines not shown, and the color filter 6 is formed. Provide a cell area. The black matrix 4 prevents light leakage and absorbs external light to increase contrast. The color filter 6 is formed over the cell region separated by the black matrix 4 and the black matrix 4. The color filter 6 is formed for each of R, G, and B to implement R, G, and B colors. The common electrode 18 is supplied with a common voltage for controlling the movement of the liquid crystal.

In the lower array substrate, the TFTs overlap with the gate electrode 9 formed on the lower substrate 32 together with the gate line, and the semiconductor layers 14 and 42 overlapping the gate electrode 9 and the gate insulating film 44 therebetween. ) And source / drain electrodes 40 and 47 formed together with data lines (not shown) with semiconductor layers 14 and 42 interposed therebetween. This TFT supplies the pixel signal from the data line to the pixel electrode 16 in response to the scan signal from the gate line. The pixel electrode 16 is a transparent conductive material having a high light transmittance and is in contact with the drain electrode 47 of the TFT with the passivation layer 50 interposed therebetween. The upper and lower alignment layers 8 and 38 for liquid crystal alignment are formed by applying an alignment material such as polyimide and then performing a rubbing process.

2A and 2B are views illustrating an alignment film printing apparatus and a rubbing device for forming an alignment film of a conventional liquid crystal display device.

Referring to FIG. 2A, a conventional alignment film printing apparatus includes an anilox roll 108 to which an alignment material such as polyimide is applied, and an orientation for transferring the alignment material applied to the surface of the anilox roll 108. A printing table 104 having a mask 106 attached thereto, and a printing table 1 on which an upper substrate 2 or a lower substrate (not shown) to be printed is mounted is shown below the printing roller 104. Loaded by an unloading device.

In the anilox roll 108, the alignment material is separated from the dispenser 110 disposed above. The doctor roll 112 is installed adjacent to the surface of the anilox roll 108 so that the alignment material is uniformly applied to the alignment mask 106.

The printing roller 104 transfers the alignment material applied to the anilox roll 108 to the groove (not shown) of the alignment mask 106 attached while being rotated by the rotation force, and prints the upper substrate 2 by printing it on the upper substrate 2. The alignment material is printed in 2).

Referring to FIG. 2B, the conventional alignment layer rubbing device includes a rubbing roller 116 to which a rubbing cloth 118 is attached.

The rubbing roller 116 rotates on the upper substrate 2 and uses a rubbing cloth 118 attached to the rubbing roller 116 to provide a uniform pressure and speed to the upper alignment layer 8 printed on the upper substrate 2. The polymer chains on the surface of the upper alignment layer 8 are aligned in a predetermined direction by rubbing with a. As a result, the liquid crystal molecules are arranged in a predetermined direction on the surface of the upper alignment layer 8.

However, the formation of the upper alignment layer 8 using the rubbing process has a problem in that static electricity is generated on the surface of the upper alignment layer 8 due to friction generated when the rubbing cloth 118 and the upper alignment layer 8 are in contact with each other. In particular, the static electricity has a disadvantage in that the yield of the liquid crystal display device is reduced by remaining in the liquid crystal display device, causing damage to the thin film transistor, the signal line, and the driving circuits.

In addition, when rubbing material such as polyimide remains on the upper substrate 2 when rubbing using the rubbing cloth 118 attached to the rubbing roller 116, an alignment substance such as polyimide remaining on the upper substrate 2 This causes a problem such as bright spots in the liquid crystal display.

In addition, due to the limitation of manufacturing a printing roller and a rubbing roller in a large sized liquid crystal display device, and the impact of the printing roller and a rubbing roller on a flexible liquid crystal display device in a flexible liquid crystal display device, The formation of the alignment film using a printing roller and a rubbing roller raises its limitations.

As a countermeasure, an ion beam irradiation device 115 and a polarizing plate 120 are used on an upper substrate 2 or a lower substrate (not shown) on which an alignment material is printed as shown in FIG. 3. A method of rubbing the upper alignment layer 8 and the lower alignment layer (not shown) in a predetermined direction has been proposed.

However, the rubbing of the upper alignment layer 8 using the ion beam irradiator 115 and the polarizing plate 120 is not fully developed in the current research stage, and further development of equipment for the alignment layer printing process is required. There is a problem such as being.

4A to 4C are diagrams for explaining the driving of the liquid crystal of the liquid crystal display device without the alignment layer.

Referring to FIG. 4A, an LCD having no alignment layer includes an upper array substrate 60 and a lower array substrate 70 bonded together to face each other with the liquid crystal 52 therebetween.

Here, the liquid crystal 52 injected between the upper array substrate 60 and the lower array substrate 70 has no liquid crystals 52 because the alignment layers for initial liquid crystal alignment are not formed on the upper and lower array substrates 60 and 70. ) Initial orientation is not made on the molecules.

Referring to FIG. 4B, the molecules of the liquid crystal 52 that are not initially aligned may be oriented by a shear force applied to the upper and lower array substrates 60 and 70 after the liquid crystal 52 is injected. When an electric field is applied to the upper and lower array substrates 60 and 70 of the liquid crystal display, the liquid crystal 52 is driven by an applied electric field as shown in FIG. 4C.

Orientation of the liquid crystal using such a share force can eliminate the disadvantages of the formation of the alignment film using the above-described printing roller and rubbing roller.

However, the initial orientation of the liquid crystal 52 using such a share force causes the initial alignment of the liquid crystal 52 using the share force, and applies the electric field to the upper and lower array substrates 60 and 70. If the electric field applied to the upper and lower array substrates 60 and 70 of the liquid crystal display is removed after driving the liquid crystal 52 by applying, the liquid crystal 52 initially oriented by the share force loses its orientation again. As shown in FIG. 5, there is a disadvantage in that there is no initial orientation.

Further, a liquid crystal display device using a ferroelectric liquid crystal polymer capable of initial alignment of liquid crystals using the aforementioned share force has been further proposed.

A liquid crystal display using ferroelectric liquid crystal polymer initially aligns the liquid crystal using share force, applies an electric field to the liquid crystal display to drive the liquid crystal, and then removes the electric field on the Smectic C of the ferroelectric liquid crystal. There is a characteristic that the initial alignment is not disturbed by the characteristic that the liquid crystal returns to the initial alignment position.

However, as described above, even when the liquid crystal is initially oriented using the share force, and the electric field is removed after driving the liquid crystal, the characteristics of the liquid crystal finding and returning to the initial alignment position are limited only when the ferroelectric liquid crystal polymer is used. .

Accordingly, an object of the present invention is to provide a liquid crystal display device and a method of manufacturing the same, which does not include an alignment layer for maintaining the initial alignment of the liquid crystal, but allows the liquid crystal to find the initial alignment state after driving the liquid crystal.

In order to achieve the above object, a liquid crystal display panel according to an embodiment of the present invention includes an upper array substrate and a lower array substrate that is bonded to face the upper array substrate; A liquid crystal layer injected between the bonded upper and lower array substrates and initially oriented by a share force applied externally to the upper and lower array substrates; The liquid crystal layer includes a liquid crystal network for maintaining an initial alignment state, wherein the liquid crystal layer forms the liquid crystal network by liquid crystal and ultraviolet light whose light transmittance is controlled by voltages applied to the upper and lower array substrates. A liquid crystalline monomer is mixed and formed.

The amount of the liquid crystalline monomer incorporated into the liquid crystal layer is 1 to 10 wt%.

The upper array substrate includes a common electrode for applying a reference voltage, which is a reference for driving the liquid crystal, to the liquid crystal.

The lower array substrate includes a common electrode for applying a reference voltage, which is a reference for driving the liquid crystal, to the liquid crystal.

Method of manufacturing a liquid crystal display device according to an embodiment of the present invention comprises the steps of bonding the upper array substrate and the lower array substrate facing each other; Injecting a liquid crystal layer between the bonded upper and lower array substrates; Initial orientation of the liquid crystal layer by applying a share force to the outside of the upper and lower array substrates into which the liquid crystal layer is injected; Irradiating ultraviolet rays to the initially oriented liquid crystal layer; And forming a liquid crystal network in which the liquid crystal layer maintains an initial alignment state in response to the irradiated ultraviolet rays, wherein the liquid crystal layer is a liquid crystal whose light transmittance is controlled by voltages applied to the upper and lower array substrates. And a liquid crystalline monomer that forms the liquid crystal network by the ultraviolet rays.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 6 to 8B.

6 is a cross-sectional view schematically illustrating a liquid crystal display device according to an exemplary embodiment of the present invention.

Referring to FIG. 6, an LCD according to an exemplary embodiment of the present invention may include an upper array substrate 160 and a lower array substrate 170 and an upper array substrate bonded together to face each other with the liquid crystal layer 152 therebetween. A liquid crystal network 200 is formed between the lower array substrate 170 and the initial aligned liquid crystal layer 152 to maintain the initial alignment state.

The liquid crystal layer 152 injected between the upper array substrate 160 and the lower array substrate 170 is formed by mixing a liquid crystal 152a and a liquid crystalline monomer (not shown). The content of the liquid crystal monomer mixed in the liquid crystal layer 152 is 1 to 10 wt%.

When a voltage is applied to the upper array substrate 160 and the lower array substrate 170, the liquid crystal 152a adjusts light transmittance according to the applied voltage so that an image is displayed on the liquid crystal display.

When the liquid crystal monomer is irradiated with ultraviolet (UV) light, the liquid crystal monomer forms a liquid crystal network 200 in response to the irradiated ultraviolet light (UV).

In the liquid crystal display according to the embodiment of the present invention, the initial alignment of the liquid crystal display without the alignment layer is lost by maintaining the initial alignment state of the liquid crystal layer 152 that is initially aligned by using the characteristics of the liquid crystal monomer. Can be removed.

In addition, the liquid crystal display according to the exemplary embodiment of the present invention does not form alignment layers on the upper and lower array substrates 160 and 170, thereby eliminating the problem of forming the alignment layer of the conventional liquid crystal display.

Hereinafter, a manufacturing method of a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to FIGS. 7A to 7D.

First, an LCD device according to an exemplary embodiment of the present invention includes an upper array substrate 160 having a black matrix, a color filter, a common electrode formed on an upper substrate, a lower array substrate formed of a TFT, and a pixel electrode formed on the lower substrate. 170) is provided as a separate process.

At this time, in the IPS mode liquid crystal display panel, a common electrode is formed on the lower substrate, and a planarization layer is formed on the upper substrate to compensate for the step difference of the color filter.

Referring to FIG. 7A, a method of manufacturing a liquid crystal display according to an exemplary embodiment of the present invention may be bonded to the upper and lower array substrates 160 and 170 provided as separate processes, and bonded to the upper and lower array substrates 160. The liquid crystal layer 152 is injected between the 170.

At this time, the liquid crystal layer 152 injected between the upper and lower array substrates 160 and 170 has no alignment layer for initial liquid crystal alignment, and thus the liquid crystal 152a molecules and liquid crystal monomers of the liquid crystal layer 152 are not formed. (152b) The molecule is in a state where the initial orientation is not achieved.

Referring to FIG. 7B, the molecules of the liquid crystal 152a of the liquid crystal layer 152 and the liquid crystal may be formed on the upper and lower array substrates 160 and 170 of the liquid crystal display having the liquid crystal layer 152 having no initial alignment. Shear force is applied to align the molecules of the active monomer 152b in a predetermined direction, and the liquid crystal layer 152 is oriented by the shear force applied.

Subsequently, as shown in FIG. 7C, ultraviolet rays (UV) are irradiated onto the liquid crystal layer 152 which is oriented by the share force. Then, the liquid crystalline monomer 152b of the liquid crystal layer 152 forms the liquid crystal network 200 in response to irradiated ultraviolet rays (UV), and at the same time, the liquid crystal 152a mixed between the liquid crystalline monomers 152b The liquid crystal monomer 152b is positioned inside the liquid crystal network 200.

When an electric field is applied to the upper and lower array substrates 160 and 170 of the liquid crystal display device on which the liquid crystal network 200 is formed, the liquid crystal layer 152 including the liquid crystal 152a and the liquid crystal network 200 formed of the liquid crystal monomer. Is driven by an applied electric field as shown in FIG. 8A, and then the initial orientation of the liquid crystal layer 152 as shown in FIG. 8B even if the electric field applied to the upper and lower array substrates 160 and 170 is removed. Is restored to the initial alignment state by the liquid crystal network 200 formed by the liquid crystal monomer.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention mixes the liquid crystal monomer 152b, which forms a network in response to the irradiated ultraviolet rays when the ultraviolet rays are irradiated, with the liquid crystal 152a. By forming the reference numeral 152, the liquid crystal layer 152 may seek the initial alignment after driving the liquid crystal layer 152 without providing the alignment layer.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention and a method of manufacturing the same according to an embodiment of the present invention mix liquid crystal monomers that form a liquid crystal network in response to the irradiated ultraviolet rays to form a liquid crystal network. By forming the liquid crystal layer, the liquid crystal layer may find the initial alignment after driving the liquid crystal display by applying an electric field to the liquid crystal without providing the alignment layer.

In addition, the liquid crystal display device and the method of manufacturing the same according to the embodiment of the present invention can eliminate the problem caused by the formation of the alignment layer of the conventional liquid crystal display device by not forming the alignment film on the upper and lower array substrate.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (8)

A lower array substrate facing and bonded to the upper array substrate and the upper array substrate; A liquid crystal layer injected between the bonded upper and lower array substrates and initially oriented by a share force applied externally to the upper and lower array substrates; A liquid crystal network for maintaining the initial alignment state of the liquid crystal layer, And the liquid crystal layer is formed by mixing liquid crystal monomers forming the liquid crystal network by liquid crystal and ultraviolet rays whose light transmittance is controlled by voltages applied to the upper and lower array substrates. The method of claim 1, The liquid crystal display device, characterized in that the content of the liquid crystal monomer is mixed in the liquid crystal layer is 1 ~ 10wt%. The method of claim 1, And the upper array substrate includes a common electrode for applying a reference voltage, which is a reference for driving the liquid crystal, to the liquid crystal. The method of claim 1, And the lower array substrate includes a common electrode for applying a reference voltage, which is a reference for driving the liquid crystal, to the liquid crystal. Bonding the upper array substrate and the lower array substrate to face each other; Injecting a liquid crystal layer between the bonded upper and lower array substrates; Initial orientation of the liquid crystal layer by applying a share force to the outside of the upper and lower array substrates into which the liquid crystal layer is injected; Irradiating ultraviolet rays to the initially oriented liquid crystal layer; Forming a liquid crystal network in response to the irradiated ultraviolet rays to maintain the initial alignment state of the liquid crystal layer, The liquid crystal layer is formed by mixing a liquid crystal whose light transmittance is controlled by voltages applied to the upper and lower array substrates, and a liquid crystal monomer forming the liquid crystal network by the ultraviolet rays. . The method of claim 5, The amount of the liquid crystal monomer is mixed in the liquid crystal layer is a manufacturing method of the liquid crystal display device, characterized in that 1 to 10wt%. The method of claim 5, The upper array substrate may include a common electrode configured to apply a reference voltage, which is a reference for driving the liquid crystal, to the liquid crystal. The method of claim 5, The lower array substrate may include a common electrode configured to apply a reference voltage, which is a reference for driving the liquid crystal, to the liquid crystal.

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