Spacer distributing apparatus for fabricating liquid crystal display device

A spacer distributing apparatus for fabricating a liquid crystal display (hereinafter, as LCD) device for improving the yield of product, which includes a chamber, a table positioned at the chamber accommodating a substrate, a spacer supply unit installed outside the chamber, a nozzle unit having a dust cover, the dust cover being installed at the upper portion of the chamber and formed as stepped structure to extend along the shape of the nozzle and the nozzle supporter, and the contact surface of the nozzle and the nozzle supporter, a SUS pipe for connecting the spacer supply unit and the nozzle unit, a bearing disposed between the nozzle and the nozzle supporter and a driving unit freely moving the table or the nozzle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a spacer distributing apparatus used in fabricating a liquid crystal display device (hereinafter, as LCD) and particularly, to a distributing apparatus capable of preventing a spacer from being contaminated and adversely affecting the distribution of the spacer.

2. Description of the Related Art

Currently, the range of application of the liquid crystal display device is enlarged due to the rapid development of the liquid crystal display device and the liquid crystal display device is installed in most portable electronic devices due to its light weight. Accordingly, developing the manufacturing technology with a reduced cost and improved productivity is an essential criteria.

Generally, as shown inFIG. 1, a liquid crystal display apparatus includes an upper substrate30in which a color filter is formed, a lower substrate10in which a thin film transistor array is formed and a liquid crystal layer22which is disposed between the two substrates10and30.

On the outer surface of the two substrates10and30, polarizers11and31, for linearly polarizing visible rays, are respectively attached. That is, the polarizer31is attached to a surface of the upper substrate30and a color filter32and a common electrode33are formed on the opposite surface where the polarizer is not attached. Also, a polarizer11is attached to a surface of the lower substrate10. On the opposite surface where the polarizer is not attached, a TFT array, including a plurality of gate bus lines12, a plurality of data bus lines13, a switching device A, a pixel electrode16and the like is formed.

The TFT includes three electrodes including a gate, source and drain, an amorphous-Si for forming a conductive channel which has a current flow between the source electrode and drain electrode caused by an electric field when a positive voltage is applied to the gate electrode, and a passivation layer for protecting the device.

The LCD device with the above composition is formed by attaching the lower substrate which is composed of the TFT and the pixel electrode, and the upper substrate which is a color substrate having a liquid crystal disposed therebetween. An orientation film is formed on opposing surfaces through which the upper and lower substrates face each other, and a sealant is formed on the upper substrate. On the lower substrate, the spacer is formed and then the two substrates are attached.

FIG. 2is a cross-sectional view showing an LCD device which is formed by attaching an upper substrate and a lower substrate.

On the opposing surfaces of the upper substrate30in which the color filter is formed, and a lower substrate10in which the TFT array is formed, an alignment layer36is printed. Also, the sealant38which is printed in a non-active region forms a gap between the two substrates, and prevents leakage of liquid crystal (not shown) which is injected between the two substrates. Also, circular spacer40is uniformly distributed between the two substrates so that the two substrates maintain a predetermined interval.

Also, to maintain a proper thickness of the liquid crystal layer in an LCD device, the spacer is distributed to control the gap between the two substrates, and prevent display spots and degradation of visuality, caused by a nonuniformity of the thickness of the liquid crystal layer.

Recently, the LCD device requires a high performance, such as a high contrast ratio, an expansion of the viewing angle field, and a high resolution that enables a uniform display without a display defection over the whole device. To insure high performance of the LCD device, it is necessary to control the interval between the substrates as a predetermined value, and to insure high resolution, it is necessary to control the interval between the substrates to be uniform in the whole device. Therefore, to improve display performance, it is very important that a spacer is uniformly distributed in the whole area of the substrate.

In the LCD device, as the spacer, 10 to 2000 particles having a uniform diameter of from several microns to several tens of microns are uniformly distributed or spread in 1 mm2as a single step to form an interval, so that the liquid crystal can be injected between the glass substrates or between plastic (organic glass) substrates, or between the plastic substrate and the glass substrate. As the spacer for the liquid crystal, various plastic particles or silica particles can be used.

Generally, as the method for distributing the spacer, there are the wet distribution method and the dry distribution method. The wet distribution method suspends the spacer for the liquid crystal in a solution such as Fron under a colloidal condition and uniformly distributes the resultant product on the substrate in a liquid state. Then, a predetermined amount of spacer is uniformly distributed on the substrate as a single step by vaporizing the solution. However, since the usage of Fron is limited due to environmental problems, the following dry distribution method is commonly used.

The dry distribution method is performed by distributing the spacer without, so-called lumps by charging it positively or negatively. As an example, when a high voltage is generated in an electrode at the end of the nozzle and the air at the circumference thereof is ionized, the spacer carried by the air collides with the negative ions in the air and is negatively ionized. The negatively ionized spacers are led to a substrate on the supporter which is grounded so that they repel each other. The spacers which are negatively ionized on the substrate are positioned at regular intervals by the repulsive force among each other.

FIG. 3is a view showing an example of a general spacer distributing apparatus.

As shown in the drawing, in the spacer distributing apparatus for a liquid crystal, a stage or table41which is grounded, is positioned within the lower portion of a hermetically sealed chamber40and a substrate51which is a distributed material which is applied to the table is grounded so that the spacer which is a charged fine powder is precisely attached to the grounded substrate51.

A nozzle unit42which freely moves in the left and right directions and front and rear directions on a flat panel is installed at the upper portion of the chamber40. The nozzle unit42is connected to a spacer supply unit43by a SUS pipe44to discharge the spacer for the liquid crystal. The spacer is carried with an air stream of gas, such as air or nitrogen, from the spacer supply unit43to distribute the spacer on the substrate51.

FIG. 4is an enlarged view showing the nozzle unit42. The nozzle unit42which is installed at the upper center portion of the chamber40, includes a nozzle46which is composed of a hollow pipe, a supporter45for supporting the nozzle46, a ball bearing47which is inserted between the nozzle46and supporter45so that the nozzle46can be freely moved in the left and right directions and front and rear directions, a driving unit (for instance, a motor) for driving the nozzle46in the multiplicity of directions, and a cover49which covers the nozzle46.

The cover49is attached to prevent the introduction of foreign materials or dust into the inside of the chamber40between the nozzle46and the supporter45when the spacer is distributed to the substrate51as the nozzle46is moved in the left and right directions and the front and rear directions. The cover49is called a dust cover.

However, when the cover49is used for a long time, tearing of the cover49occurs in the connection between the nozzle46and cover49due to the frequent movement of the nozzle46. Therefore, foreign materials can penetrate through the tearing crevice whereby the inside of the chamber40becomes polluted.

When the cover49becomes torn due to the continuous rotation of the nozzle46, the spacer which was distributed and lumped in the torn part (A) falls onto the substrate, causing a serious defect in the surface of the LCD.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a spacer distributing apparatus, capable of preventing tearing of a cover to be uniformly positioned on a substrate without producing lumps of the spacer material, by constructing the structure of a dust cover to prevent the introduction of foreign materials into the nozzle unit. The dust cover has stepped configuration.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a spacer distributing apparatus for fabricating a liquid crystal display device, including a chamber, a table positioned inside the chamber, a spacer supply unit installed outside the chamber, a nozzle having a dust cover, the dust cover being installed at the upper portion of the chamber, and a SUS pipe connecting the nozzle unit with the spacer supply unit. The nozzle unit includes a nozzle supporter for supporting the nozzle and the dust cover, which has stepped configuration, is utilized to protect the nozzle unit.

The table is positioned in the lower portion inside the chamber. Also, the table is grounded so that the substrate disposed on the table is also grounded to precisely attach the spacer for the liquid crystal, which is a charged fine powder.

The spacer supply unit is installed outside the chamber and supplies the spacer to the nozzle unit.

In the method of supplying the spacer, a gas such as air or nitrogen is supplied from the outside to the spacer supply unit and the pressure inside the spacer supply unit is increased. Therefore, the spacer for the liquid crystal is carried with the air stream of the gas and is supplied to the nozzle unit through the SUS pipe. The spacer, which is supplied to the nozzle unit, is distributed on the substrate through the nozzle of the nozzle unit.

In the nozzle unit which is composed of the nozzle supporter, nozzle, bearing, and stepped cover, the supporter supports the nozzle and the bearing which is installed between the nozzle and the nozzle supporter enabling the nozzle to freely move in the X and Y directions. The movement of the nozzle is performed by the driving unit which is installed on the nozzle supporter.

The cover which is attached to the center of rotation of the nozzle prevents the introduction of foreign materials into the chamber and has stepped structure for flexibly coping with the rotation of the nozzle.

It is desirable that the spacer distributing apparatus, in accordance with the present invention, is applied to the dry distribution method but it can also be applied to the wet distribution method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 5is a view showing a spacer distributing apparatus for fabricating a liquid crystal display device in accordance with the present invention.

As shown in the drawing, the spacer distributing apparatus for fabricating the liquid crystal display device in accordance with the present invention includes a chamber40, a table41which is positioned inside the chamber40, a spacer supply unit43for supplying the spacer to the chamber40, a nozzle unit42which is installed in the upper portion of the chamber40for spraying the spacer which is supplied from the spacer supply unit43to the stage41, and a SUS pipe44for connecting the spacer of the spacer supply unit43with the nozzle unit42.

The nozzle unit42includes a nozzle46, a nozzle supporter45for supporting the nozzle46, and a dust cover49which covers the connection of the nozzle46and the nozzle supporter45. The dust cover has a dual stepped structure which accommodates the shape of the nozzle46and the nozzle supporter45.

The dust cover49prevents the inflow of dusts or foreign materials through the contact surface of the nozzle46and the nozzle supporter45. Also, according to the frequent movement of the nozzle, the dust cover49is formed in a dual stepped structure along the shape of the nozzle46and the nozzle supporter45to prevent damage such as the tearing of the dust cover49.

The table or stage41is grounded and positioned inside the lower portion of the chamber40and precisely attaches the spacer which is distributed through the nozzle46on a grounded substrate51by grounding the substrate51on the stage.

In the upper portion of the chamber40, the nozzle unit42and the spacer supply unit43, which can freely fluctuate in the left and right directions and the front and rear directions on a flat substrate, are connected to the SUS pipe44, thus distributing the spacer on the substrate51by discharging the spacer, which is carried with a stream of gas such as air or nitrogen from the spacer supply unit43, through the nozzle46of the nozzle unit42.

The spacer supply unit43is provided outside and separate from the chamber40and supplies the spacer to the nozzle unit42. By following the method for supplying the spacer, when the pressure inside the spacer supply unit43is increased due to the inflow of a gas, such as air or nitrogen, from the outside to the spacer supply unit43, the spacer supply unit43supplies the spacer for the liquid crystal, which is carried with the air stream of gas, through the SUS pipe44connecting the spacer supply unit43and the nozzle unit42, to the nozzle unit42and the nozzle46to be distributed on the substrate51.

Hereinafter, the nozzle unit42including the nozzle46, the nozzle supporter45and the dust cover49will be described with reference toFIGS. 6aand6bshowing in detail an enlarged view of the nozzle unit42.

As shown in theFIG. 6a,the nozzle unit42includes the nozzle supporter45, the nozzle46and the cover49. A driving unit48for freely moving the nozzle46in the front and rear directions and in the left and right directions is positioned beside the nozzle unit42.

The nozzle supporter45supports and fixes the nozzle46to the chamber and a bearing47is installed between the nozzle46and the nozzle supporter45so that the nozzle46can be freely moved in the front and rear directions and the left and right directions. The movement of the nozzle46is controlled by the driving unit48which is installed on the chamber40.

The dust cover49which is attached to the nozzle46reduces the adverse effects caused by the collection of foreign material thereby minimizing the deformation of the shape caused by the movement of the nozzle46. The dust cover is formed in a dual stepped structure50which flexibly copes with the rotation of the nozzle46.

Generally, the nozzle46is moved in the left and right directions and in the front and rear directions to distribute spacer on the substrate. At this time, the foreign material collecting portion of the cover49, as shown inFIG. 4, is torn by frequent movement of the nozzle46. To prevent this, the cover49is formed as a dual stepped structure50.

The cover49formed as above, prevents the inflow of foreign material into the chamber40. Since it is made of rubber or a urethane material, free movement of the nozzle46can be flexibly accommodated and since it is formed as a dual stepped structure50, the shape of the cover49is hardly changed, in spite of the fluctuations of the nozzle46.

Therefore, since the cover49is not torn, even if the nozzle46is used for a long period of time, the conventional problems whereby foreign materials penetrate through the torn cover, are avoided. Also, a spacer which otherwise may collect around the torn cover and eventually fall on the substrate, can also be eliminated.

FIG. 6bshows a nozzle portion having a dust cover49awhich is formed in a triple stepped structure50a.An identical reference numeral is given to the identical part as in the first embodiment (FIG. 6A), and different points will be described. As described above, in case the dust cover49ais formed in the triple stepped structure50a,it could not smoothly cope with frequent movement of the nozzle, compared with the dual stepped structure50.

In the present invention, the structure of the dust cover is not limited as the dual or triple stepped structure. That is, the shape of the dust cover can be changed according to the shapes of the nozzle, supporter and the like, which are covered by the dust cover.

The distribution process of the spacer by the spacer distributing apparatus can be described as follows.

Firstly, the spacer which, is stored in the spacer supply unit43, passes through the SUS pipe44to the nozzle46and is sprayed through the nozzle46. At this time, the pressure of the gas, e.g., air or nitrogen, in the spacer supply unit43is increased and accordingly, the spacer which is carried with the stream of gas is supplied to the nozzle46. When the spacer is supplied to the nozzle46, the nozzle46evenly distributes the spacer onto the substrate51by moving in the front and rear/left and right directions, namely, X and Y directions, using the driving unit48which is installed in the upper potion of the chamber40.

In the method of distributing the spacer on the substrate51, either the stage on which the substrate is positioned is fixed and the nozzle46is moved, or the stage41on which the substrate51is positioned is moved and the nozzle46is fixed. Also, the nozzle46and the stage41can be simultaneously moved.

FIG. 7is a pattern diagram showing a zigzag shape or serpentine configuration of the scanning locus of the spacer distributed on the substrate due to the movement of the nozzle46or the stage41in the left and right/front and rear directions. It can be seen that the scanning locus is the locus of the extension line of the center axis line of the nozzle46for distributing the spacer, and its intersection point on the substrate surface. The scanning locus is enabled by controlling the distributing of the spacer on the substrate46using the driving unit48.

As the nozzle46moves in the X and Y directions, and the movements of the nozzle in the X and Y directions are synthesized, the spacer is distributed on the substrate51in the path shown inFIG. 7.

At this time, to prevent the introduction of foreign material into the chamber40and in the bearing47which is positioned at the rotation center of the nozzle46, a cover49, which is formed in stepped construction, is attached, in part, to the nozzle46, and accordingly, there is no deformation of the shape of the cover49in spite of the free movement of the nozzle46.

As described above, in accordance with the present invention, by reducing the radius of the foreign material collecting area and by forming a cover which is attached to the nozzle center portion of the nozzle, the spacer distributing apparatus for liquid crystal, which requires the free movement of the nozzle, can be effectively accommodated and the problem whereby the cover is torn by the movement of the nozzle, permitting the introduction of foreign material into the chamber, can be avoided.

Also, the defection in the distribution of the spacer on the substrate can be prevented by preventing the spacer from becoming lumped around the torn cover and falling onto the substrate as the nozzle moves.