KR20030087696A - Liquid Crystal Display and Method of Fabricating the same - Google Patents

Abstract

PURPOSE: A liquid crystal display and a method for fabricating the liquid crystal display are provided to maintain an appropriate cell gap using an ink jet. CONSTITUTION: A liquid crystal display includes an upper substrate on which a common electrode is formed, and a lower substrate(1) on which a pixel electrode(22) and a thin film transistor are formed. The liquid crystal display further includes spacers(58) for maintaining a gap between the upper and lower substrates. The spacers are sprayed on one of the upper and lower substrates using an ink jet. The ink jet(50) is located under the substrates and sprays the spacers on one of the substrates in the direction opposite to gravity. The ink jet is composed of a container(52) in which the spacers are contained, and an ink jet head including a nozzle(56) for spraying the spacers from the container.

Description

Liquid Crystal Display and Method of Manufacturing the Same {Liquid Crystal Display and Method of Fabricating the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a method of manufacturing the same, in which a height of a spacer can be formed high so as to maintain an appropriate cell gap using an inkjet method.

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

Referring to FIG. 1, a typical liquid crystal display device includes a top plate including a black matrix 20, a color filter 16, a common electrode 14, and an alignment layer 12 sequentially formed on an upper substrate 11. A TFT formed sequentially on the lower substrate 1, a lower plate composed of the pixel electrode 22 and the alignment layer 10, a spacer 24 formed between the upper and lower plates, and an interior between the upper and lower plates 24. A liquid crystal (not shown) injected into the space is provided.

In the lower panel, the TFT is connected to the pixel electrode 22 through the gate electrode 25 protruding from the gate line (not shown), the source electrode 28 protruding from the data line (not shown), and the contact hole 23. Drain electrode 30 is provided. In addition, the TFT is formed by the gate insulating film 6 for insulating the gate electrode 25, the source electrode 28, and the drain electrode 30, and the source electrode 28 by the gate voltage supplied to the gate electrode 25. The semiconductor layers 26 and 27 are further provided to form a conductive channel between the drain electrodes 30. This TFT selectively supplies the data signal from the data line to the pixel electrode 22 in response to the gate signal from the gate line. The liquid crystal rotates by the voltage difference between the data signal supplied through the TFT and the common voltage Vcom supplied to the common electrode 14, and the light transmittance is determined according to the degree of rotation of the liquid crystal. The pixel electrode 22 is formed of a transparent conductive material having a high light transmittance and positioned in a cell region divided by a data line and a gate line. The pixel electrode 22 is formed on the passivation layer 8 applied on the entire lower substrate 1, and is electrically connected to the drain electrode 30 through the contact hole 23 formed in the passivation layer 8. After the alignment layer 10 is coated on the lower substrate 1 on which the pixel electrode 22 is formed, a rubbing process is performed to complete the lower plate.

The upper plate forms a black matrix 20 corresponding to the TFT forming region on the upper substrate 11 to form a cell region in which the color filter 16 is to be formed. The black matrix 20 prevents light leakage and absorbs external light to increase contrast. The color filter 16 is formed in an area separated by the black matrix 20. The color filter 16 selectively transmits light having a specific wavelength to implement R, G, and B colors. The common electrode 14 is supplied with a common voltage Vcom for controlling the movement of the liquid crystal, and the upper plate is completed by forming the alignment layer 12 on the common electrode 14.

In this way, the spacer 24 is formed on any one of the upper and lower substrates separately made. Subsequently, the upper and lower plates are bonded to each other, and then the liquid crystal is injected and sealed to complete the liquid crystal display.

Here, the spacer 24 is formed in an ink-jet method.

First, as illustrated in FIG. 2A, the inkjet 40 is aligned to correspond to the position where the spacer 24 is to be formed on the lower plate, and then the spacer 24 is ejected. In FIG. 2A, the spacer 24 is sprayed on the lower plate, but may be sprayed on the upper plate.

The inkjet method is a piezoelectric method in which ink is injected from a nozzle by a thermal method and a pressure difference, and a piezo method is mainly used. The piezo inkjet 40 is composed of a container 42 containing a substance to be jetted, and an ink jet head 44 for jetting the substance from the container 42 to the outside.

The container 42 is filled with a spacer 24, and the inkjet head 44 has a piezoelectric element and a nozzle 46 for injecting a substance contained in the container 42. When a voltage is applied to the piezoelectric element, a physical pressure is generated to cause a capillary phenomenon in which a flow path between the container 42 and the nozzle 46 contracts and relaxes. By this capillary phenomenon, the spacer 24 is ejected through the nozzle 46.

The spacer 24 is ejected through the nozzle 46 of the inkjet 40 as shown in FIG. 2B, and is formed to have a predetermined width W and a height H on the lower plate. Thereafter, the spacer 24 is hardened while going through the firing process.

When the spacer 24 is formed by the inkjet method, when the spacer 24 having a low viscosity is sprayed on the upper or lower plate, the spacer 24 falls to the upper or lower plate and is subjected to gravity. Accordingly, the spacers 24 are formed to be widely spread on the upper plate or the lower plate. When the spacer 24 is formed so as to spread widely, the spacer 24 is formed to be lower than the minimum height of the spacer 24 to maintain the gap between the upper and lower plates. As a result, the desired height of the spacer 24 cannot be obtained even after the firing step. If the height of the spacer 24 that maintains the proper cell gap is not obtained, luminance and contrast may not be obtained properly, resulting in poor image quality.

Accordingly, an object of the present invention is to provide a liquid crystal display device and a method of manufacturing the same, which can increase the height of a spacer so as to maintain an appropriate cell gap using an inkjet method.

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

2A and 2B illustrate a method of manufacturing a spacer using a conventional inkjet method.

3A and 3B illustrate a method of manufacturing a spacer for a liquid crystal display device using the inkjet method according to the present invention.

FIG. 4 shows the spacer shown in FIG. 3B in detail. FIG.

<Description of Symbols for Main Parts of Drawings>

1: lower substrate 2: sealant

6: gate insulating film 8: protective film

10, 12: alignment layer 11: upper substrate

14 common electrode 16 color filter

22 pixel electrode 23 contact hole

24, 58: spacer 25: gate electrode

26, 27: semiconductor layer 28: source electrode

30: drain electrode 40, 50: inkjet

In order to achieve the above object, the liquid crystal display device according to the present invention comprises a liquid crystal display device having an upper plate on which a common electrode is formed, and a lower plate on which a pixel electrode and a thin film transistor are formed; A spacer sprayed on at least one of the upper and lower plates to maintain a gap between the upper and lower plates; And an inkjet positioned below the substrate to eject the spacer onto the substrate in a direction opposite to gravity.

The inkjet is characterized in that the inkjet head including a container containing the spacer and a nozzle for ejecting the spacer from the container to the outside.

The manufacturing method of the liquid crystal display device which concerns on this invention is a manufacturing method of the liquid crystal display device provided with an upper board and a lower board; Aligning the ink jet under at least one of the upper and lower substrates; Spraying spacers on the substrate in a direction opposite to gravity.

Firing a spacer sprayed on the substrate.

The spacer may be sprayed through the nozzle of the inkjet.

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. 3A and 4.

Referring to FIG. 3A, a bottom plate of the liquid crystal display according to the exemplary embodiment of the present invention is positioned above the inkjet 50. In other words, the inkjet 50 is positioned under the lower plate, and the spacer 58 filled in the container 52 of the inkjet 50 is injected from the bottom upward through the nozzle 56. Here, the spacer 58 injected into the inkjet 50 may be formed on the top plate (not shown).

The lower plate of the liquid crystal display device is composed of a TFT sequentially formed on the lower substrate 1, the pixel electrode 22, and the alignment layer 10.

The ink jet 50 is used to form the spacers 58 on the lower plate. Subsequently, the upper and lower plates are bonded to each other, and then the liquid crystal is injected and sealed to complete the liquid crystal display.

After aligning the inkjet 40 on the lower plate to correspond to the position where the spacer should be formed, the spacer 58 is ejected. Here, the inkjet 50 is composed of a container 52 containing the material to be sprayed, and an inkjet head 54 for ejecting the material from the container 52 to the outside.

The container 52 is filled with a spacer 58, and the inkjet head 54 is formed with a piezoelectric element and a nozzle 56 for injecting a substance contained in the container 52.

When a voltage is applied to the piezoelectric element, a physical pressure is generated to cause a capillary phenomenon in which a flow path between the container 52 and the nozzle 56 contracts and relaxes. The spacer 58 is injected through the nozzle 56 by the force caused by the capillary phenomenon. In this case, since the inkjet 50 is positioned below the lower plate, the spacer 58 is injected in a direction opposite to the force of gravity, and thus the spacer 58 does not receive the force of gravity. As a result, as shown in FIG. 3B, the spacer 58 does not spread wider than that of a conventional spacer and has a high height. In other words, in contrast to the prior art, the spacer 58 in the present invention is formed such that the width W 'is narrower and the height H' is higher than the conventional art. That is, as shown in FIG. 4, since the contact angle θ depends on the width W ′ and the height H ′ of the spacer 58, the width W ′ is reduced and the height H ′ is reduced. When () increases, the contact angle (θ) increases.

The spacer 58 is formed on a region or TFT other than the pixel electrode 22 which is an opening. When the spacer 58 is formed on the upper plate, the spacer 58 is formed in a region corresponding to the black matrix 20.

Thereafter, the spacer 58 is hardened through the firing process.

After the spacers 58 are formed on the upper or lower plate in this manner, the upper and lower plates are aligned and bonded to each other, and the liquid crystal is injected and sealed to complete the liquid crystal display device.

As such, when the ink jet 50 is positioned below the lower plate to eject the spacer 58, the height H ′ of the spacer 58 may be formed to match the height of an appropriate cell gap between the upper and lower plates of the liquid crystal display. have.

As described above, the liquid crystal display and the manufacturing method thereof according to the present invention align the inkjet under the upper plate or the lower plate. When the inkjet is positioned below the upper or lower plate, the spacer is ejected in the direction opposite to gravity. Accordingly, the spacer is formed on the upper plate or the lower plate without being affected by gravity, so that the spacer has a narrower width and a higher height than before. Therefore, the liquid crystal display device and the method of manufacturing the same according to the present invention can have a spacer height suitable for an appropriate cell gap height and can properly obtain luminance and contrast, which have been a problem in the related art, and thus can improve image quality.

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 (10)

A liquid crystal display device comprising: an upper plate on which a common electrode is formed, and a lower plate on which pixel electrodes and thin film transistors are formed; A spacer sprayed on at least one of the upper and lower plates to maintain a gap between the upper and lower plates; And an inkjet positioned under the substrate to inject spacers on the substrate in a direction opposite to gravity. The method of claim 1, The inkjet is a container containing the spacer, And an inkjet head including a nozzle for ejecting the spacer from the container to the outside. A manufacturing method of a liquid crystal display device having an upper plate and a lower plate; Arranging an ink jet under at least one of the upper and lower substrates; And spraying spacers on the substrate in a direction opposite to gravity. The method of claim 3, wherein And firing the spacers injected onto the substrate. The method of claim 3, wherein And the spacer is sprayed through the nozzle of the inkjet. The method of claim 3, wherein On the top plate Forming a black matrix on the upper substrate; Forming a color filter on the area separated by the black matrix; Forming a common electrode on the color filter; The method of manufacturing a liquid crystal display device, further comprising the step of forming an alignment layer on the common electrode. The method of claim 3, wherein In the lower plate Forming a thin film transistor on the lower substrate; Forming a protective film to cover the thin film transistor; And forming a pixel electrode on the passivation layer to be electrically connected to the thin film transistor. The method of claim 6, And the spacer is formed in a region corresponding to the black matrix. The method of claim 7, wherein And the spacer is formed in a region other than the pixel electrode. The method of claim 7, wherein And the spacer is formed on the thin film transistor.