KR101131249B1 - Apparatus and method of dispensing liquid crystal - Google Patents

Abstract

The liquid crystal dropping apparatus of the present invention includes a container filled with a liquid crystal, a discharge pump for sucking and discharging the liquid crystal filled in the container, a nozzle for dropping the liquid crystal discharged from the discharge pump onto a substrate, and provided near the nozzle. It consists of a sensing means for detecting the liquid crystal agglomeration of the nozzle surface. When the liquid crystals are agglomerated on the nozzle surface, the liquid crystals agglomerated on the nozzle surface can be removed by detecting a drop by the sensing means and performing a dummy drop or cleaning the nozzle by a cleaning device.

Liquid crystal dropping, discharge pump, nozzle, liquid crystal agglomeration, sensor, dropping, cleaning device

Description

Liquid crystal dropping device and dropping method {APPARATUS AND METHOD OF DISPENSING LIQUID CRYSTAL}

1 is a cross-sectional view of a general liquid crystal display device.

2 is a flowchart showing a conventional method for manufacturing a liquid crystal display device.

3 is a view showing liquid crystal injection of a conventional liquid crystal display device.

4 is a view showing a liquid crystal display device manufactured by the liquid crystal dropping method according to the present invention.

5 is a flowchart illustrating a method of manufacturing a liquid crystal display device by the liquid crystal dropping method.

6 is a view showing a basic concept of the liquid crystal dropping method.

7 is a perspective view showing the structure of the liquid crystal droplets according to the present invention.

8 is an exploded perspective view showing the structure of the liquid crystal droplets according to the present invention.

Figure 9 (a) is a perspective view showing the structure of the liquid crystal discharge pump of the liquid crystal drop according to the present invention.

Figure 9 (b) is an exploded perspective view showing the structure of the liquid crystal discharge pump.

10 is a view showing a state in which the liquid crystal discharge pump is fixed to the fixed portion.

11 (a) to 11 (d) are views showing the operation of the liquid crystal discharge pump.                 

12 is a view showing a structure of a liquid crystal discharge pump having a fixed angle increased.

FIG. 13 is a graph showing liquid crystal aggregation on the nozzle surface; FIG.

14 is a view showing a control system of the liquid crystal dropping apparatus according to the present invention.

15 shows a cleaning apparatus according to the present invention.

16 is a flowchart showing a liquid crystal dropping method according to the present invention.

Explanation of symbols on the main parts of the drawings

120: liquid crystal drop 122: liquid crystal container

123: Case 128: Pin

131,133: motor 134: liquid crystal volume adjusting member

136: rotation axis 137: control lever

140: liquid crystal discharge pump 142: cylinder

145: piston 145a: groove

147: liquid crystal suction opening 148: liquid crystal discharge opening

149: fixing part 150: nozzle

154, 162: sensor 200: control unit

205: motor driver 206: substrate driver

209: dummy loading execution unit 210: cleaning device drive unit

220: cleaning device

The present invention relates to a liquid crystal dropping device, and more particularly, to a liquid crystal dropping device and a dropping method capable of accurately dropping a liquid crystal by detecting and efficiently removing a liquid crystal when the liquid crystals are agglomerated in the nozzle by having sensors on both sides of the nozzle.

Recently, with the development of various portable electronic devices such as mobile phones, PDAs, and notebook computers, there is a growing demand for flat panel display devices for light and thin applications. Such flat panel displays are being actively researched, such as LCD (Liquid Crystal Display), PDP (Plasma Display Panel), FED (Field Emission Display), VFD (Vacuum Fluorescent Display), but mass production technology, ease of driving means, Liquid crystal display devices (LCDs) are in the spotlight for reasons of implementation.

LCD is a device for displaying information on the screen using the refractive anisotropy of the liquid crystal. As shown in FIG. 1, the LCD 1 is composed of a lower substrate 5 and an upper substrate 3 and a liquid crystal layer 7 formed between the lower substrate 5 and the upper substrate 3. The lower substrate 5 is a drive element array substrate. Although not shown in the figure, a plurality of pixels are formed on the lower substrate 5, and a driving element such as a thin film transistor (hereinafter referred to as TFT) is formed in each pixel. The upper substrate 3 is a color filter substrate, and a color filter layer for real color is formed. In addition, a pixel electrode and a common electrode are formed on the lower substrate 5 and the upper substrate 3, respectively, and an alignment film for aligning liquid crystal molecules of the liquid crystal layer 7 is coated.

The lower substrate 5 and the upper substrate 3 are bonded by a sealing material 9, and a liquid crystal layer 7 is formed therebetween by a driving element formed on the lower substrate 5. Information is displayed by controlling the amount of light passing through the liquid crystal layer by driving the liquid crystal molecules.

The manufacturing process of the liquid crystal display device can be largely divided into a driving element array substrate process of forming a driving element on the lower substrate 5, a color filter substrate process of forming a color filter on the upper substrate 3, and a cell process. However, the process of the liquid crystal display will be described with reference to FIG. 2.

First, a plurality of gate lines and data lines arranged on the lower substrate 5 to define a pixel region are formed by a driving element array process, and the gate line and the gate line are formed in each of the pixel regions. A thin film transistor which is a driving element connected to the data line is formed (S101). In addition, the pixel electrode is connected to the thin film transistor through the driving element array process to drive the liquid crystal layer as a signal is applied through the thin film transistor.

In addition, the upper substrate 3 is formed with a color filter layer and a common electrode of R, G, B to implement the color by the color filter process (S104).

Subsequently, an alignment layer is applied to the upper substrate 3 and the lower substrate 5, respectively, and then the alignment control force or surface fixing force (ie, the liquid crystal molecules of the liquid crystal layer formed between the upper substrate 3 and the lower substrate 5). The orientation film is rubbed to provide a pretilt angle and orientation direction (S102 and S105). Subsequently, a spacer is disposed on the lower substrate 5 to maintain a constant cell gap, and a sealing material 9 is applied to an outer portion of the upper substrate 3, and then the lower substrate 5 is disposed. And the upper substrate 3 by applying pressure (S103, S106, S107).

On the other hand, the lower substrate 5 and the upper substrate 3 is made of a large area glass substrate. In other words, a plurality of panel regions are formed on a large area glass substrate, and a TFT and a color filter layer, which are driving elements, are formed in each of the panel regions. Must be processed (S108). Thereafter, the liquid crystal is injected into the liquid crystal panel processed as described above through the liquid crystal inlet, and the liquid crystal inlet is encapsulated to form a liquid crystal layer. Then, the liquid crystal display is manufactured by inspecting each liquid crystal panel (S109 and S110). .

The liquid crystal is injected through the liquid crystal inlet formed in the panel. At this time, the injection of the liquid crystal is made by the pressure difference. 3 shows an apparatus for injecting liquid crystal into the liquid crystal panel. As shown in FIG. 3, a container 12 filled with liquid crystal is provided in a vacuum chamber 10, and a liquid crystal panel 1 is positioned on an upper portion thereof. The vacuum chamber 10 is connected to a vacuum pump to maintain a set vacuum state. In addition, although not shown in the drawing, an apparatus for moving the liquid crystal panel is installed in the vacuum chamber 10 to move the liquid crystal panel 1 from the upper part of the container 12 to the container, and thus the injection hole 16 formed in the liquid crystal panel 1. ) Is brought into contact with the liquid crystal 14 (this method is referred to as a liquid crystal dipping injection method).                         

As described above, when nitrogen (N ₂ ) gas is supplied into the vacuum chamber 10 while the injection port 16 of the liquid crystal panel 1 is in contact with the liquid crystal 14, the vacuum degree of the chamber 10 is reduced. The liquid crystal 14 is injected into the panel 1 through the injection hole 16 by the pressure difference between the pressure inside the liquid crystal panel 1 and the vacuum chamber 10 and the liquid crystal is completely filled in the panel 1. The liquid crystal layer is formed by sealing the injection hole 16 with a sealing material (this method is called vacuum injection of liquid crystal).

However, the method of forming the liquid crystal layer by injecting liquid crystal through the injection hole 16 of the liquid crystal panel 1 in the vacuum chamber 10 as described above has the following problems.

First, the liquid crystal injection time to the panel 1 is long. In general, the distance between the driving element array substrate and the color filter substrate of the liquid crystal panel is very narrow, such as several μm, so that only a very small amount of liquid crystal is injected into the liquid crystal panel per unit time. For example, when manufacturing a liquid crystal panel of about 15 inches takes about 8 hours to completely inject the liquid crystal, the liquid crystal panel manufacturing process is lengthened by the long-term liquid crystal injection, the manufacturing efficiency is lowered.

Second, the liquid crystal consumption rate is high in the liquid crystal injection method as described above. Of the liquid crystals 14 filled in the container 12, the amount injected into the liquid crystal panel 1 is a very small amount. Meanwhile, when the liquid crystal is exposed to the atmosphere or a specific gas, the liquid crystal not only deteriorates by reacting with the gas, but also deteriorates due to impurities introduced upon contact with the liquid crystal panel 1. Therefore, even when the liquid crystal 14 filled in the container 12 is injected into the plurality of liquid crystal panels 1, the liquid crystal 14 remaining after the injection must be discarded. This leads to an increase in manufacturing cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object thereof is to provide a liquid crystal dropping apparatus and a dropping method capable of always dropping an accurate amount of liquid crystal onto a substrate by dropping the liquid crystal by a liquid crystal discharge pump.

Another object of the present invention is to provide a liquid crystal dropping device and a dropping method for installing a sensor that senses agglomeration of liquid crystals around a nozzle to prevent a liquid crystal dropping failure due to the liquid crystal agglomeration of the nozzle surface.

It is still another object of the present invention to provide a liquid crystal dropping device and a dropping method capable of preventing a liquid crystal dropping failure by providing a means for removing liquid crystals agglomerated on the nozzle surface.

In order to achieve the above object, the liquid crystal dropping apparatus according to the present invention is to drop the container filled with the liquid crystal, the discharge pump for sucking and discharging the liquid crystal filled in the container, and the liquid crystal discharged from the discharge pump to the substrate And a sensing means installed near the nozzle to sense liquid crystal agglomeration on the nozzle surface.

The discharge pump includes a cylinder, a piston which is inserted into the cylinder and has a groove formed in a predetermined lower portion thereof to suck and discharge the liquid crystal as it rotates and moves up and down, and a suction port through which the liquid crystal is sucked and discharged as the piston moves. It consists of a discharge port.                         

In addition, the liquid crystal dropping device includes a motor driving part for driving a motor to operate a discharge pump, a substrate driving part for driving a substrate to align the dropping position of the liquid crystal with the nozzle, and a liquid crystal in the dummy area when the liquid crystal is agglomerated on the nozzle surface. And a dummy execution unit to drop the liquid crystal, and a control unit to stop the dropping of the liquid crystal when the liquid crystal aggregation is detected by the sensing means, and then to operate the dummy execution unit to remove the liquid crystals, and to remove the liquid crystal aggregated on the nozzle surface. It may further comprise means.

In addition, the liquid crystal dropping method according to the present invention comprises the steps of detecting the liquid crystal agglomeration on the nozzle surface of the liquid crystal dropping liquid crystal dropping the liquid crystal panel to the liquid crystal panel formed on the substrate, and stopping the liquid crystal dropping when the liquid crystal agglomeration is detected And dropping the liquid crystal accumulated on the nozzle surface by dummy dropping, and advancing the liquid crystal dropping.

In order to overcome the shortcomings of the conventional liquid crystal injection method such as the liquid crystal dipping method or the liquid crystal vacuum injection method, a method proposed in recent years is a liquid crystal layer forming method by the liquid crystal dropping method. The liquid crystal dropping method does not inject the liquid crystal by the pressure difference between the inside and the outside of the panel, but directly drops and dispenses the liquid crystal onto the substrate, and uniformly spreads the liquid crystal dropped by the bonding pressure of the panel. The liquid crystal layer is formed by distribution. Since the liquid crystal dropping method directly drops the liquid crystal onto the substrate for a short time, the liquid crystal layer formation of the large area liquid crystal display device can be performed very quickly, and only the required amount of liquid crystal is directly dropped onto the substrate. Since it is possible to minimize the consumption of the liquid crystal display device has the advantage that can significantly reduce the manufacturing cost.

4 is a view showing a basic concept of the liquid crystal dropping method. As shown in the figure, in the liquid crystal dropping method, before the lower substrate 105 and the upper substrate 103 on which the driving element and the color filter are formed, respectively, the liquid crystal 107 is droplet-shaped on the lower substrate 105. Dropping The liquid crystal 107 may be dropped on the substrate 103 on which the color filter is formed. In other words, the substrate to be the liquid crystal dropping method in the liquid crystal dropping method may be either a TFT substrate or a CF substrate. However, when the substrates are bonded, the substrate on which the liquid crystal is dropped must be placed at the bottom.

In this case, a sealing material 109 is applied to the outer region of the upper substrate 103 to apply pressure to the upper substrate 103 and the lower substrate 105 so that the upper substrate 103 and the lower substrate 105 are bonded together. At the same time, droplets of the liquid crystal 107 are spread out by the pressure to form a liquid crystal layer having a uniform thickness between the upper substrate 103 and the lower substrate 105. In other words, the biggest feature of the liquid crystal dropping method is that the liquid crystal 107 is previously dropped on the lower substrate before the panel 101 is bonded, and then the panel is bonded by the sealing material 109.

The liquid crystal display device manufacturing method to which the above liquid crystal dropping method is applied is shown in FIG. 5. As shown in the figure, TFT and color filter layers, which are driving elements, are formed on the lower substrate 150 and the upper substrate 103 through the TFT array process and the color filter process (S201 and S202). The TFT array process and the color filter process are the same as those of the conventional manufacturing method shown in FIG. In particular, since the liquid crystal dropping method is applied in the manufacturing method, it can be usefully used in a larger glass substrate, for example, a large area glass substrate having an area of 1000 × 200 mm ² or more compared with the conventional manufacturing method.

Subsequently, after the alignment film is applied to the lower substrate 105 on which the TFT is formed and the upper substrate 103 on which the color filter layer is formed, rubbing is performed (S202 and S205), the liquid crystal panel region of the lower substrate 105 is formed. 107 is dropped and a sealing material 109 is applied to the liquid crystal panel outer region of the upper substrate (S203, S206).

Thereafter, pressure is applied while the upper substrate 103 and the lower substrate 105 are aligned, and the upper substrate 105 and the lower substrate 103 are bonded together by a sealing material 109 and at the same time the application of pressure is applied. The liquid crystal 107 dropped by this is spread evenly over the whole panel (S207). Through this process, a plurality of liquid crystal panels having a liquid crystal layer are formed on glass substrates (lower substrates and upper substrates) having a large area. The glass substrates are processed and cut and separated into a plurality of liquid crystal panels. By inspecting, a liquid crystal display device is produced (S208, S209).

Comparing the difference between the method of manufacturing the liquid crystal display device to which the liquid crystal drop method shown in FIG. 5 is applied and the method of manufacturing the liquid crystal display device to which the conventional liquid crystal injection method shown in FIG. 2 is applied, the difference between the vacuum injection and the liquid crystal drop of the liquid crystal and In addition to the difference in the processing time of the large-area glass substrate it can be seen that there are other differences. That is, in the manufacturing method of the liquid crystal display device to which the liquid crystal injection method shown in FIG. 2 is applied, the injection hole must be sealed with an encapsulant after the liquid crystal is injected through the injection hole, but in the manufacturing method to which the liquid crystal drop method is applied, the liquid crystal is directly dropped on the substrate. This eliminates the need for sealing of these inlets. In addition, although not shown in FIG. 2, in the manufacturing method to which the liquid crystal injection method is applied, since the substrate contacts the liquid crystal when the liquid crystal is injected, the outer surface of the panel is contaminated by the liquid crystal, thus requiring a process for cleaning the contaminated substrate. In the manufacturing method in which the liquid crystal dropping method is applied, since the liquid crystal is directly dropped on the substrate, the panel is not contaminated by the liquid crystal, and as a result, the cleaning process is unnecessary. As described above, the manufacturing method of the liquid crystal display device by the liquid crystal dropping method is made of a simple process by the manufacturing method by the liquid crystal injection method, so that not only the manufacturing efficiency can be improved but also the yield can be improved.

In the manufacturing method of the liquid crystal display device in which the liquid crystal dropping method is introduced as described above, the most important factors for accurately forming the liquid crystal layer to a desired thickness are the position of the liquid crystal to be dropped and the amount of liquid crystal dropping. In particular, since the thickness of the liquid crystal layer has a close relationship with the cell gap of the liquid crystal panel, the accurate dropping position and the dropping amount of the liquid crystal are very important factors for preventing defects of the liquid crystal panel. Therefore, there is a need for an apparatus for dropping the correct amount of liquid crystal at the correct position, and the present invention provides such liquid crystal droplets.

6 is a view showing a basic concept of dropping the liquid crystal 107 on the substrate (large area glass substrate) 105 using the liquid crystal drop according to the present invention. As shown in the figure, the liquid crystal droplets 120 are provided on the substrate 105. Although not shown in the figure, the liquid crystal is filled in the liquid crystal dropper 120 to fill a predetermined amount on the substrate.                     

Typically, the liquid crystal is dropped onto the substrate in the form of droplets. Since the substrate 105 moves at a set speed in the x and y directions, and liquid crystals discharge liquid crystals at set time intervals, the liquid crystals 107 dropped on the substrate 105 are spaced at regular intervals in the x and y directions. Is placed. Of course, the liquid crystal dropping substrate 105 may be fixed and the liquid crystal dropping 120 may move in the x and y directions to drop the liquid crystal at a predetermined interval. However, in this case, since the droplet-shaped liquid crystals are shaken by the movement of the liquid crystal dropping 120, an error may occur in the dropping position and the dropping amount of the liquid crystal. Therefore, the liquid crystal dropping 120 is fixed and the substrate 105 is moved. It is desirable to.

FIG. 7 is a perspective view showing the structure of the liquid crystal dropper 120 according to the present invention, and FIG. 8 is a perspective exploded view of the liquid crystal dropper 120. As illustrated in FIGS. 7 and 8, in the liquid crystal dropper 120, a cylindrical liquid crystal container 122 is accommodated in the case 123. The liquid crystal container 122 is made of polyethylene, and the liquid crystal 107 is filled therein, and the case 123 is made of stainless steel so that the liquid crystal container 122 is formed therein. It is stored. In general, polyethylene is mainly used as the liquid crystal container 122 because it is easy to form a container having a desired shape because of its excellent moldability and does not react with the liquid crystal when the liquid crystal 107 is filled. However, since the polyethylene is weak in strength, the polyethylene is easily deformed by a weak external shock. In particular, when polyethylene is used as the liquid crystal container 122, the container 122 may be deformed to drop the liquid crystal 107 in the correct position. Since it is not present, it is stored in a case 123 made of stainless steel with high strength, and used.                     

On the other hand, although not shown in the figure, a gas supply pipe is connected to the upper portion of the liquid crystal container 122 is supplied with a gas such as nitrogen from the outside. This gas supply prevents the pressure drop in the region where the liquid crystal is not filled in the liquid crystal container 122 when the liquid crystal is dropped, thereby preventing the liquid crystal dropping.

The liquid crystal container 122 may be formed of a metal such as stainless steel. In this case, since the liquid crystal container 122 is not deformed by an external impact, the outer case 123 is not necessary. Therefore, the manufacturing cost of the liquid crystal dropper 120 can be reduced. As such, when the liquid crystal container 122 is formed of a metal, it is preferable to apply a fluorine resin film therein to prevent the filled liquid crystal 107 from causing a chemical reaction with the metal.

The liquid crystal discharge pump 140 is disposed below the liquid crystal container 122. The liquid crystal discharge pump 140 discharges a predetermined amount of liquid crystal of the liquid crystal container 122 and drops the liquid on the substrate. The liquid crystal is discharged as the liquid crystal discharge pump 140 is connected to the liquid crystal container 122. The liquid crystal suction opening 147 and the liquid crystal suction opening 147 are formed opposite to each other, and the liquid crystal discharge pump 140 operates to discharge the liquid crystal.

As shown in FIG. 8, the first connection pipe 126 is coupled to the liquid crystal suction opening 147. Although the liquid crystal suction opening 147 is inserted and coupled to the first connection pipe 126 in the drawing, the liquid crystal suction opening 147 and the first connection pipe 126 may be coupled by a coupling means such as a screw. One side of the first connecting tube 126 is formed with a pin 128 through which the inside is perforated, such as a needle, and the lower portion of the liquid crystal container 122 that leaks liquid crystal into the first connecting tube 126. And pads (not shown) made of a material having strong shrinkage and sealing properties such as butyl rubber series. The pin 128 is inserted into the liquid crystal container 122 through a pad and flows the liquid crystal 107 of the liquid crystal container 122 into the liquid crystal suction opening 147. Since the pad is strongly contracted into the pin 128 when the pin 128 is inserted, the liquid crystal 107 may be prevented from leaking into the insertion region of the pin 128. As such, since the liquid crystal suction opening 147 and the liquid crystal container 122 are fastened by the pins and the pads, the fastening structure is simplified, and as a result, the fastening and detaching can be easily performed.

The liquid crystal suction opening 147 and the first connection pipe 126 may be integrally formed. In this case, the pin 128 is formed in the liquid crystal suction opening 147 and inserted directly into the liquid crystal container 122 through a pad to leak the liquid crystal of the liquid crystal container 122, thereby simplifying the structure.

The nozzle 150 is installed below the liquid crystal discharge pump 140. The nozzle 150 is connected to the liquid crystal discharge port 148 of the liquid crystal discharge pump 140 through the second connection pipe 160 to drop the liquid crystal 107 discharged from the liquid crystal discharge pump 150 on a substrate. .

The second connection pipe 160 may be formed of an opaque material, but may be formed of a transparent material. As described above, the reason for forming the second connection tube 160 made of a transparent material is as follows.

Generally, bubbles are contained in the liquid crystal 107 when the liquid crystal is dropped, and the drop amount of the liquid crystal 107 dropped on the substrate cannot be accurately controlled. Therefore, bubbles must be removed when the liquid crystal 107 is dropped. Meanwhile, bubbles are already contained in the liquid crystal 107 filled in the liquid crystal container 122. Although bubbles in the liquid crystal 107 can be removed by the bubble removing device, it is virtually impossible to remove all bubbles even in this case. In addition, bubbles may occur when the liquid crystal 107 is introduced into the liquid crystal discharge pump 140 from the liquid crystal container 122. As a result, it is almost impossible to completely remove bubbles from the dropped liquid crystal 107. Therefore, when bubbles are generated, removing bubbles by discontinuing the operation of the liquid crystal droplets may be the best way to prevent defects.

The second connecting tube 160 is formed of a transparent material to easily detect bubbles included in the liquid crystal container 122 or bubbles generated in the liquid crystal container 122 to prevent defects. At this time, the discovery of the bubble may be made by the operator's naked eye, but the first sensor 162 such as a photo coupler on both sides of the second connecting tube 160 to automatically detect the bubble. It will more reliably prevent failure.

Protection portions 152 are installed on both side surfaces of the nozzle 150 into which the liquid crystal discharged through the second connection pipe 160 flows, thereby preventing the nozzle 150 from being damaged by an external force.

On the other hand, the liquid crystal discharge pump 140 is inserted into the rotating member 157, the rotating member 157 is fixed to the fixing portion 155. The rotating member 157 is connected to the first motor 131. As the first motor 131 operates, the rotating member 157 rotates, and the liquid crystal discharge pump 140 fixed to the rotating member 157 operates.

The liquid crystal discharge pump 140 is in contact with one side of the liquid crystal volume adjusting member 134 having a shape such as a bar. The other side of the liquid crystal volume adjustment member 134 is formed with a hole, the rotating shaft 136 is inserted into the hole. A screw is formed around the hole of the liquid crystal volume adjusting member 134 and the rotating shaft 136, and is screwed together. In addition, one end of the rotating shaft 136 is connected to the second motor 133, the other end is connected to the control lever 137.

The amount of liquid crystal discharged from the liquid crystal container 122 through the liquid crystal discharge pump 140 depends on the angle fixed to the rotating member 157. That is, the liquid crystal volume of the liquid crystal discharge pump 140 varies according to the fixed angle fixed to the rotating member 157. When the second motor 133 connected to the rotary shaft 136 is driven (automatically adjusted) or the control lever 137 is operated (manually adjusted), the rotary shaft 136 is rotated, thus rotating screw 136 and the screw One end of the combined liquid crystal volume adjustment member 134 is moved back and forth (straight line) along the rotation axis 136. As such, the force applied to the liquid crystal discharge pump 140 is changed as one end of the liquid crystal volume adjusting member 134 moves, and as a result, the fixed angle of the liquid crystal discharge pump 140 is changed.

As described above, the first motor 131 operates the liquid crystal discharge pump 140 to discharge the liquid crystal of the liquid crystal container 122 to drop the liquid onto the substrate, and the second motor 133 is fixed to the rotating member 157. The fixed angle of the liquid crystal discharge pump 140 is controlled to control the amount of liquid crystal discharged from the liquid crystal discharge pump 140.

Meanwhile, the one-time dropping amount of the liquid crystal dropped onto the substrate through the liquid crystal discharge pump 140 is a very fine amount, and thus the amount of change of the liquid crystal discharge pump 140 controlled by the second motor 133 is also a minute amount. . This means that the inclination angle of the liquid crystal discharge pump 140 must be adjusted very finely in order to control the discharge amount of the liquid crystal discharge pump 140. For such fine adjustment, the second motor 133 uses a step motor operated by a pulse input value.

9 (a) and 9 (b) are diagrams showing the structure of the liquid crystal discharge pump 140, (a) is a perspective view and (b) is an exploded perspective view.

9 (a) and 9 (b), the liquid crystal discharge pump 140 has a case 141 in which a liquid crystal suction opening 147 and a liquid crystal discharge opening 148 are formed, and an opening is formed in an upper portion thereof. A cap 144 coupled to the case 141, a cylinder 142 inserted into the case 141 to suck liquid crystal, a sealing means 143 for sealing the cylinder 142, and the cap ( O-ring (144a) is located on the upper to prevent the leakage of the liquid crystal and the liquid crystal suction opening 147 by being inserted into the cylinder 142 through the opening of the cap 144 to move up and down It consists of a piston 145 for sucking and discharging the liquid crystal 107 through the liquid crystal discharge port 148. A head 146a fixed to the rotating member 157 is provided at an upper portion of the piston 145, and a bar 146b is installed at the head 146a. The bar 146b is inserted into and fixed to a hole (not shown) formed in the rotating member 157 so that the piston 145 rotates when the rotating member 157 is rotated by the force of the first motor 131. ) To rotate.

On the other hand, as shown in Figure 9 (b), the groove 145a is formed at the end of the piston 145. The groove 145a is formed to have an area of about 1/4 (or less) in the circular cross section of the piston 145 so that the piston 145 rotates (ie, moves up and down) and the liquid crystal suction opening 147. And opening and closing the liquid crystal discharge opening 148 to suck and discharge the liquid crystal through the liquid crystal suction opening 147 and the liquid crystal discharge opening 148.

Referring to the operation of the liquid crystal discharge pump 140 in detail as follows.

10 is a view showing a state in which the liquid crystal discharge pump 140 is fixed to the rotating member 157. As shown in the figure, the piston 145 is fixed to the rotating member 157 at an angle α, and the bar 146b formed on the piston head 146a is a hole formed in the inner surface of the rotating member 157. The piston 145 and the rotary member 157 are inserted into the 159. Although not shown in the drawing, since the bearing is provided inside the hole 159, the bar 146b of the piston 145 inserted into the hole 159 can move back, forth, left, and right. When the first pump 131 operates, the rotating member 157 rotates, and as a result, the piston 145 coupled with the rotating member 157 (that is, fixed) rotates.

At this time, assuming that the fixed angle α of the liquid crystal discharge pump with respect to the rotating member 157, that is, the fixed angle α of the piston 145 with respect to the rotating member 157 is 0, the piston 145 rotates only. Only rotational movement is performed along the member 157. However, since the fixed angle α is not substantially zero (that is, fixed at a constant angle), the piston 145 rotates along the rotational movement of the rotating member 157 and simultaneously moves up and down. Will be.

During the movement of the piston 145, when the piston 145 is rotated by a certain angle to move upwards, an empty space is created inside the cylinder 142, the liquid crystal is sucked into the space through the liquid crystal suction port 147, Thereafter, as the piston 145 further rotates, the piston 145 moves downward, and the liquid crystal sucked in the cylinder 142 is discharged through the liquid crystal discharge port 148. At this time, the groove 145a formed in the piston 145 serves to open and close the liquid crystal suction opening 147 and the liquid crystal discharge opening 148 during the suction and discharge of the liquid crystal by the rotation of the piston 145.

Hereinafter, the operation of the liquid crystal discharge pump 140 as described above will be described in more detail with reference to FIGS. 11A to 11D.

As illustrated in FIGS. 11A to 11D, the liquid crystal discharge pump 140 discharges the liquid crystal 107 of the liquid crystal container 122 to the nozzle 150 through four strokes. 11 (a) and 11 (c) are cross strokes. FIG. 11B illustrates a suction stroke through the liquid crystal suction port 147 and FIG. 11D illustrates a liquid crystal discharge stroke through the liquid crystal discharge port 148.

As illustrated in FIG. 11A, the piston 145 fixed to the rotating member 157 at an angle α rotates as the rotating member 157 rotates. At this time, the liquid crystal suction opening 147 and the liquid crystal discharge opening 148 are closed by the piston 145.

As the rotating member 157 rotates about 45 °, the piston 145 also rotates, so that the liquid crystal suction opening 147 is opened by the groove 145a of the piston 145 as shown in FIG. . Meanwhile, the bar 146b of the piston 145 is inserted into the hole 159 of the rotating member 157 to couple the rotating member 157 and the piston 145. Accordingly, the piston 145 rotates as the rotating member 157 rotates, and the bar 146b rotates along the rotational surface.                     

Since the piston 145 is fixed to the rotating member 157 at an angle and the bar 146b rotates along the rotating surface, the piston 145 is raised as the rotating member 145 rotates. In addition, since the cylinder 141 is fixed, a space is created in the cylinder 141 under the piston 145 as the rotating member 145 rotates. Therefore, the liquid crystal is sucked into the space through the liquid crystal suction opening 147 opened by the groove 145a.

The suction of the liquid crystal is carried out after the suction stroke starts (that is, after the liquid crystal suction opening 147 is opened) until the rotation member 157 rotates about 45 ° to start the suction stroke as shown in FIG. 11 (c). It continues (until the liquid crystal suction opening 147 is closed).

Thereafter, as shown in FIG. 11 (d), as the rotary member 157 is further rotated, the liquid crystal discharge port 148 is opened and at the same time the piston 145 starts to descend and the space in the cylinder 141. The liquid crystal sucked in is discharged through the liquid crystal discharge port 148 (discharge stroke).

As described above, the liquid crystal discharge pump 140 repeats four strokes consisting of a first cross stroke, a suction stroke, a second cross stroke, and a discharge stroke, thereby discharging the liquid crystal 107 filled in the liquid crystal container 122 through the nozzle 150. To be discharged.

At this time, the discharge amount of the liquid crystal depends on the vertical movement range of the piston 145. However, the vertical movement range of the piston 145 varies depending on the angle of the liquid crystal discharge pump 140 fixed to the rotating member 157.

12 is a view showing that the liquid crystal discharge pump 140 is fixed to the rotating member 157 at an angle β. Compared to FIG. 10, in which the liquid crystal discharge pump 140 is fixed to the rotating member 157 at an angle of α (<β), the liquid crystal discharge pump 140 of FIG. 12 allows the piston 145 to move higher in the upward direction. do. This means that as the angle fixed to the rotating member 157 increases, the amount of the liquid crystal 107 sucked into the cylinder 142 during the movement of the piston 145 increases, which is fixed to the rotating member 157. It means that the discharge amount of the liquid crystal can be controlled by adjusting the angle.

Meanwhile, as shown in FIG. 7, the angle of the liquid crystal discharge pump 140 fixed to the rotating member 157 is controlled by the liquid crystal volume adjusting member 134, and the liquid crystal volume adjusting member 134 is provided as a second. As the pump 133 is driven, it moves. In other words, the angle of the liquid crystal discharge pump 140 can be adjusted by controlling the second pump 133.

Of course, the operator may manually adjust the fixed angle of the liquid crystal discharge pump 140 by the angle adjusting lever 137, but in this case, accurate adjustment is not possible and time consuming and stops the liquid crystal discharge pump during the operation. There is also a disadvantage. Therefore, it is preferable that the fixed angle of the liquid crystal discharge pump 140 is adjusted by the second pump 133.

In this case, the fixed angle of the liquid crystal discharge pump 140 is measured by a sensor 139 such as a linear variable differential transformer, and when the fixed angle exceeds the set angle, an alarm is issued to the liquid crystal discharge pump 140. ) To prevent damage.

As described above, in the liquid crystal dropping apparatus according to the present invention, after the fixed angle of the liquid crystal discharging pump 140 is changed by the second pump 133 to set the drop amount of liquid crystal, the first pump 131 is operated to operate the liquid crystal. By driving the discharge pump 140, the liquid crystal is dropped onto the substrate through the nozzle 150.

However, the liquid crystal set on the substrate may not drop even when the actual liquid crystal is dropped after setting the correct amount of dropping amount as described above. Such a case may be caused by various causes such as an external environment, but the biggest cause among them is a phenomenon in which liquid crystals aggregate on the surface of the nozzle 150.

The nozzle 150 is typically made of metal, such as stainless steel. Such metals have a low contact angle with respect to the liquid crystal. In general, the contact angle refers to the angle formed when the liquid is in thermodynamic equilibrium at the solid surface. This contact angle is a measure of the wettability of a solid surface. Therefore, since the metal has high wettability (i.e., hydrophilicity) and high surface energy, the liquid tends to spread to the metal surface. As a result, when the liquid crystal is dropped through the nozzle 150 made of a metal, the liquid crystal does not have a drop shape at the end of the nozzle 150 (to achieve such a drop shape, which means that the contact angle is high). Spread out to the surface of the liquid crystal, and as the liquid crystal drop is repeated, as shown in FIG. 13, the liquid crystal agglomeration, that is, the remaining liquid crystal 107a is formed on the surface of the nozzle 150.

The spreading of the liquid crystal onto the surface of the nozzle 150 makes accurate liquid crystal dropping impossible. Even when the amount of liquid crystal dropped through the nozzle 150 is controlled by adjusting the fixed angle of the liquid crystal discharge pump 140, some of the dropped liquid crystal spreads to the nozzle surface. It becomes smaller than the amount dropped through. Of course, it is possible to control the amount dropped in consideration of the amount of the liquid crystal spread to the surface of the nozzle 150, but it is impossible to calculate the amount of the liquid crystal substantially spread to the surface of the nozzle 150.

In addition, the liquid crystal 107a aggregated in the nozzle 150 by the repetition of the liquid crystal drop may be added to the amount discharged through the nozzle 150 and thus more liquid crystals may be dropped onto the substrate. In other words, in the nozzle 150 made of metal, the amount of liquid crystal dropped by the low contact angle, which is a property of the metal, becomes irregular.

In order to prevent the liquid crystals from agglomerating on the surface of the nozzle 150 as described above, a fluorine resin film having a high contact angle is coated on the surface of the nozzle 150 by dipping or spraying, or the nozzle 150 itself. The liquid crystal 107 which is discharged through the nozzle 150 by the low wettability (hydrophobicity) and the low surface energy of the fluorine resin is formed by using a single-use (of course, dropping the liquid crystal onto the set number of substrates) made of fluorine resin. It is possible to achieve a complete droplet form without spreading to the nozzle 150 surface. However, even when the fluorine resin film is applied to the surface of the nozzle 150 or the nozzle 150 is formed of the fluorine resin as described above, as the liquid crystal drop is repeated, a small amount of liquid crystal spreads through the nozzle 150 to cause the liquid crystal to aggregate. It cannot be completely avoided.

As shown in Fig. 7 (a) and 7 (b), in the present invention is provided on both sides of the nozzle 150 is provided in the protection unit 152 for preventing the nozzle 150 from being damaged from external force, etc. By providing the two sensors 154, liquid crystal agglomeration is detected on the surface of the nozzle 150. In this case, the second sensor 154 may be formed as a photocoupler like the first sensor 162, but may be configured as another type of sensor.

As shown in FIG. 13, the second sensor 154 is connected to the controller. When the signal is input from the second sensor 154 and the liquid crystal is agglomerated on the surface of the nozzle 150, the controller determines and measures this.

As shown in FIG. 14, the signal detected by the second sensor 154 is input to the controller 200 through the input unit 202, and the controller 200 based on the input signal is used to detect the second sensor ( It is determined whether the liquid crystal is agglomerated on the surface of 154. On the other hand, the control unit 200 outputs a control signal to the motor driving unit 205 to operate the first motor 131 and the second motor 133 to control the discharge amount of the liquid crystal discharge pump 140 and the liquid crystal discharge pump ( 140 is discharged. In addition, the controller 200 operates the substrate driver 206 to move the substrate so that the nozzle 150 and the liquid crystal position on the substrate coincide. In this case, the liquid crystal droplets may move directly on the substrate instead of the substrate (in this case, the name of the substrate driver may have to be changed to the droplet moving portion).

When it is determined that the liquid crystal is agglomerated on the surface of the nozzle 150, the controller 200 determines that a defect occurs in the liquid crystal drop when performing further liquid crystal drop, and outputs a control signal to the motor driver 205. In response to the control signal, the motor driving unit 205 stops driving of the first pump 131 to stop liquid crystal dropping. At this time, the control unit 200 displays the current state of the liquid crystal agglomeration of the surface of the nozzle 150 on the output unit 208 to inform the operator.

As described above, when the liquid crystals are agglomerated in the nozzle 150, a worker who detects the liquid crystal may separate the nozzle 150 from the liquid crystal dropping device and then remove the liquid crystal agglomerated in the nozzle 150, but the dummy drop execution unit 209 as follows. The liquid crystal may be automatically removed by outputting a signal to the cleaning device driver 210.

When the liquid crystal is agglomerated on the surface of the nozzle 150, the dummy dropping execution unit 209 removes the liquid crystal formed on the surface of the nozzle 150 by performing a dummy drop of the liquid crystal according to a signal input from the controller 200. A dummy drop is a measuring cup provided for measuring a dropping amount of a liquid crystal in another region, for example, a region where a liquid crystal panel on a substrate is not formed or a liquid crystal dropping position in a liquid crystal dropping position on an actual substrate. By measuring the weight of the liquid crystal dropped into the liquid crystal and detecting whether the actual amount of liquid crystal dropping is the same as the set dropping amount, and correcting the dropping amount of the liquid crystal by the deviation if it is not the same), or dropping the liquid crystal into a dummy dropping container. Means that. At this time, instead of dropping the set amount of liquid crystals in the dummy dropping, the liquid crystals are dropped so that a larger amount of liquid crystals are dropped, that is, all of the liquid crystals agglomerated on the surface.

By the liquid drop of the liquid crystal, all the liquid crystals agglomerated on the surface of the nozzle 150 can be removed. Then, the motor driving unit 205 and the substrate driving unit 206 are driven again to perform normal dropping of the liquid crystal.

In addition, when the liquid crystal is agglomerated on the surface of the nozzle 150, the cleaning device driver 210 drives the cleaning device according to a signal input from the controller 200 to clean the surface of the nozzle 150. Of course, the liquid crystal stuck to the nozzle 150 may be removed by performing a dummy drop, but in this case, since it is very difficult to remove all the liquid crystal remaining on the surface of the nozzle 150, the cleaning apparatus may be used to remove the liquid crystal. It is to remove all the liquid crystal.

Both the dummy loading function and the cleaning function by the cleaning device may be provided in the liquid crystal dropping device. For example, the liquid crystals on the surface of the nozzle 150 may be removed by carrying out a dummy drop in a short period of time, and the liquid crystals on the surface of the nozzle 150 may be removed by a cleaning device after a long period of time (after performing a certain number of dummy drops). Could be. However, in the liquid crystal dropping apparatus of the present invention, only one of the dummy loading function and the cleaning function by the cleaning device may be provided. Of course, even in this case, the liquid crystals agglomerated on the surface of the nozzle 150 may be effectively removed.

As shown in FIG. 15, the nozzle cleaning device 220 includes a main body 222 and a suction pipe 226 formed on the main body 222, and a vacuum pump 228 is connected to the suction pipe 226. . In cleaning the nozzle 150, the suction pipe 226 is substantially aligned with the outlet of the nozzle 150. The reason for this is to increase the efficiency of cleaning by aligning the outlet and the suction pipe 226 because the liquid crystals 107a which are aggregated on the surface of the nozzle 150 are mainly distributed around the outlet.

Cleaning of the nozzle 150 is repeated periodically. When the set number of liquid crystal drops is finished, the nozzle cleaner 220 is moved toward the nozzle 150 by a motor (not shown) so that the outlet of the nozzle 150 and the suction pipe 226 are aligned. At this time, since the support 224 is installed on the main body 222 to support the main body 222 and the nozzle 150, the outlet and the suction pipe 226 when the outlet of the nozzle 150 and the suction pipe 226 are aligned. It forms a certain space between them. As described above, the suction pipe 226 formed in the main body 222 is vacuumed as the vacuum pump 228 operates while the nozzle cleaning device 220 moves and the outlet of the nozzle 150 is aligned with the suction pipe 226. As a result, the liquid crystal 107a around the nozzle 150, particularly around the discharge port, is sucked into the suction pipe 226, thereby removing the liquid crystal 107a on the surface of the nozzle 150.

Although not shown in the drawing, the nozzle cleaning device 220 may be provided with a storage tank for accommodating the liquid crystal 107a. The liquid crystal 107a sucked into the suction pipe 226 by the operation of the vacuum pump 228 arrives at the vacuum pump 228 by being accommodated in a storage tank installed between the main body 222 and the vacuum pump 228 by gravity. You will not. In the case where the liquid crystal storage tank is installed as described above, the liquid crystal 107a may be disposed by separating the storage tank from the nozzle cleaning device 220, thereby simplifying the processing of the collected liquid crystal.

As described above, in the liquid crystal dropping apparatus of the present invention, a second sensor 154 is installed around the nozzle 150 to detect the liquid crystal lump, and the liquid crystal is removed while removing the liquid crystal lumped on the surface of the nozzle 150 in real time. This is briefly described as follows.

As shown in FIG. 16, as the liquid crystal drop begins, the second sensor 154 starts to detect liquid crystal agglomeration on the surface of the nozzle 150 (S301). The signal output from the second sensor 154 is input to the controller 200, and when the aggregation of the liquid crystal is not detected according to the signal input from the second sensor 154, the drop of the normal liquid crystal is normal. It is determined that the state of the liquid crystal is continued to drop (S302).

When the liquid crystal is detected on the surface of the nozzle 150 by the second sensor 154 while the liquid crystal is in progress, the controller 200 outputs a control signal to the motor driving unit 205 to stop the first motor 131 and The dripping is stopped (S303).

At the same time, the control unit 200 drives the motor driving unit 205 and the substrate driving unit 206 to provide an empty area of the substrate (ie, an area where no liquid crystal panel is formed), a measuring cup, or a separate container (dummy container). The liquid crystal is added dropwise (dummy drop) to remove the liquid crystal aggregated on the surface of the nozzle 150 (S304). In addition, instead of performing a dummy drop, a control signal may be output to the cleaning device driver 210 to drive the cleaning device 220 to remove liquid crystals agglomerated on the surface of the nozzle 150 (S305). At this time, the liquid crystals on the surface of the nozzle 150 may be removed by cleaning by the dummy dropping and washing apparatus (dummy drop cleaning).

As described above, in the present invention, it is possible to effectively remove the liquid crystals agglomerated on the surface of the nozzle. The present invention may be applied to any liquid crystal dropping device having any structure provided that a nozzle for dropping liquid crystals is provided. In addition, since the sensor for detecting the liquid crystal aggregation can be provided regardless of the structure of the nozzle, it may be applied to nozzles of various structures. Moreover, it may be used not only for the nozzle made of stainless steel, but also for the disposable nozzle made of fluorocarbon resin.

As described above, in the present invention, as described above, in the present invention, a sensor is installed around the nozzle to detect liquid crystals agglomerating on the surface of the liquid crystal, and thus, the liquid crystals can be removed by a dummy or cleaning device. Therefore, the dropping failure may be effectively prevented by the liquid crystal on the nozzle surface.

Claims (27)

A container filled with liquid crystal; A discharge pump for sucking and discharging the liquid crystal filled in the container; A nozzle for dropping the liquid crystal discharged from the discharge pump onto a substrate; A motor driving unit driving the motor to operate the discharge pump; A substrate driver for driving the substrate to align the dropping position of the liquid crystal with the nozzle; A dummy execution unit operated by the control unit to drop the liquid crystal onto the dummy area when the liquid crystals are accumulated on the nozzle surface; Sensing means installed near the nozzle to detect liquid crystal agglomeration on the nozzle surface; And And a control unit configured to remove the liquid crystals by stopping the dropping of the liquid crystals by operating the dummy execution unit when the liquid crystals are detected by the sensing means. The method of claim 1, wherein the discharge pump, cylinder; A piston which is inserted into the cylinder and has a groove formed in a predetermined region of the lower portion to suck and discharge the liquid crystal as the rotary and vertical movements occur; And a suction port and a discharge port through which the liquid crystal is sucked and discharged as the piston moves. The liquid crystal dropping device of claim 2, further comprising a fixing part to which the discharge pump is fixed. The liquid crystal dropping apparatus of claim 3, wherein the fixing unit includes a rotating member to which the piston of the discharge pump is fixed to rotate the piston. The liquid crystal dropping apparatus of claim 4, wherein a bar is formed in the piston, and a hole is formed in the rotating member, and the piston is fixed to the rotating member as the bar and the hole are coupled to each other. The liquid crystal dropping apparatus according to claim 5, wherein the bar is rotatably inserted into the hole. The liquid crystal dropping apparatus according to claim 4, wherein the liquid crystal volume of the discharge pump varies depending on an angle at which the piston is fixed to the rotating member. The liquid crystal dropping apparatus according to claim 1, further comprising a liquid crystal volume adjusting member for contacting the discharge pump to change a fixed angle of the discharge pump to adjust the discharge amount of the liquid crystal. The method of claim 8, A motor for driving the liquid crystal volume adjusting member; And And a rotating shaft which is screwed with the liquid crystal volume adjusting member and rotates as the motor is driven to linearly move the liquid crystal volume adjusting member. The liquid crystal dropping apparatus according to claim 1, wherein the sensing means is a photocoupler. delete The liquid crystal dropping apparatus of claim 1, wherein the dummy region is a region in which a liquid crystal panel is not formed on a substrate. The liquid crystal dropping apparatus according to claim 1, wherein the dummy region is a drop measuring cup. The liquid crystal dropping apparatus according to claim 1, further comprising cleaning means for removing liquid crystals agglomerated on the nozzle surface. The method of claim 14, wherein the cleaning means, main body; And And a suction pipe connected to a vacuum pump to be in a vacuum state as the vacuum pump operates to suck liquid crystals agglomerated on the nozzle surface. 16. The liquid crystal dropping apparatus according to claim 15, wherein the cleaning means further includes a storage tank connected to the suction pipe to accommodate liquid crystal sucked into the suction pipe. A container filled with liquid crystal; A discharge pump for sucking and discharging the liquid crystal filled in the container; A nozzle for dropping the liquid crystal discharged from the discharge pump onto a substrate; A motor driving unit driving the motor to operate the discharge pump; A substrate driver for driving the substrate to align the dropping position of the liquid crystal with the nozzle; Sensing means installed near the nozzle to detect liquid crystal agglomeration on the nozzle surface; A cleaning means driving unit for driving cleaning means for cleaning the nozzle surface when the liquid crystals stick to the nozzle surface; And And a control unit configured to remove the liquid crystal by outputting a signal to the cleaning means driving unit after stopping the dropping of the liquid crystal when the liquid crystal aggregation is detected by the sensing means. 18. The liquid crystal dropping apparatus according to claim 1 or 17, wherein the nozzle is made of stainless steel. 18. The liquid crystal dropping apparatus according to claim 1 or 17, wherein the nozzle is disposable. 20. The liquid crystal dropping apparatus according to claim 19, wherein the nozzle is made of a fluorine resin. Detecting liquid crystal agglomeration on the nozzle surface of the liquid crystal dropping when the liquid crystal is dropped onto the liquid crystal panel formed on the substrate; Stopping liquid crystal dropping when agglomeration of liquid crystals is detected; Performing a dripping to remove the liquid crystal aggregated on the nozzle surface; And Liquid crystal dropping method comprising the steps of proceeding the liquid crystal dropping. The method of claim 21, wherein the liquid crystal A container filled with liquid crystal; A discharge pump for sucking and discharging the liquid crystal filled in the container; A nozzle for dropping the liquid crystal discharged from the discharge pump onto a substrate; And And a sensing means installed near the nozzle and configured to detect liquid crystal agglomeration on the nozzle surface. The method of claim 21, wherein the step of dummy loading, Aligning the nozzle with a region where the liquid crystal panel of the substrate is not formed; And Liquid crystal dropping method comprising the step of dropping the liquid crystal. The method of claim 21, wherein the step of dummy loading, Aligning the nozzle and the container for liquid crystal storage; And Liquid crystal dropping method comprising the step of dropping the liquid crystal. 22. The liquid crystal dropping method according to claim 21, further comprising the step of removing liquid crystal on the nozzle surface with cleaning means. The method of claim 25, wherein the cleaning means, main body; And And a suction tube connected to a vacuum pump to be in a vacuum state as the vacuum pump operates to suck liquid crystals agglomerated on the nozzle surface. Detecting liquid crystal agglomeration on the nozzle surface of the liquid crystal drop by a photocoupler when the liquid crystal is dropped onto the liquid crystal panel formed on the substrate; Stopping liquid crystal dropping when agglomeration of liquid crystals is detected; Removing the liquid crystal on the nozzle surface by the cleaning means consisting of a suction pipe which is connected to the main body and the vacuum pump and the vacuum pump is operated to suck the liquid crystal agglomerated on the nozzle surface; and Liquid crystal dropping method comprising the steps of proceeding the liquid crystal dropping.

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