Patent Document

[0001]    The present application claims the benefit of Korean Patent Application Nos. 7151/2002 and 7772/2002 respectively filed in Korea on Feb. 7, 2002 and Feb. 9, 2002, which are both hereby incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a liquid crystal dispensing apparatus, and more particularly, to a liquid crystal dispensing apparatus for preventing scatter of the liquid crystal resulting from damage to the nozzle from which the liquid crystal is discharged and dropped from the liquid crystal dispensing apparatus. In addition, the present invention relates to a liquid crystal dispensing apparatus for preventing the liquid crystal from being lumped around the nozzle.  
           [0004]    2. Description of the Related Art  
           [0005]    Recently, various portable electric devices such as mobile phones, personal digital assistants (PDA), and notebook computers have been developed, and therefore, needs for a flat panel display device used in small, light weight, and power-efficient devices for such portable devices are correspondingly increasing. To meet the needs, the flat panel display device such as a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), a and vacuum fluorescent display (VFD) have been actively researched. Of these flat panel display devices, the LCD is highlighted due to current mass production, efficient driving schemes, and superior image quality.  
           [0006]    The LCD is a device for displaying information on a screen using refractive anisotropy of liquid crystal. As shown in FIG. 1, the LCD  1  comprises a lower substrate  5 , 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 driving device array substrate. A plurality of pixels (not shown) are formed on the lower substrate  5 , and a driving device such as a thin film transistor (TFT) is formed on the each pixel. The upper substrate  3  is a color filter substrate, and a color filter layer for reproducing real color is formed thereon. Further, a pixel electrode and a common electrode are formed on the lower substrate  5  and the upper substrate  3  respectively. An alignment layer is formed on the lower substrate  5  and the upper substrate  3  to align liquid crystal molecules of the liquid crystal layer  7  uniformly.  
           [0007]    The lower substrate  5  and the upper substrate  3  are attached by a sealing material  9 , and the liquid crystal layer  7  is formed therebetween. In addition, the liquid crystal molecules are reoriented by the driving device formed on the lower substrate  5  to control the amount of light transmitted through the liquid crystal layer, thereby displaying information.  
           [0008]    Fabrication processes for a LCD device can be divided into a driving device array substrate process for forming the driving device on the lower substrate  5 , a color filter substrate process for forming the color filter on the upper substrate  3 , and a cell process. These processes will be described with reference to FIG. 2 as follows.  
           [0009]    At first, a plurality of gate lines and data lines are arranged on the lower substrate to define a pixel area by the driving device array process and the thin film transistor connected to the both gate line and the data line is formed on the each pixel area (S 101 ). Also, a pixel electrode, which is connected to the thin film transistor to drive the liquid crystal layer according to a signal applied through the thin film transistor, is formed by the driving device array process.  
           [0010]    At the same time, R (Red), G (Green), and B (Blue) color filter layers for reproducing the color and a common electrode are formed on the upper substrate  3  by the color filter process (S 104 ).  
           [0011]    In addition, the alignment layer is formed on the lower substrate  5  and the upper substrate  3  respectively, and then the alignment layer is rubbed in order to induce an surface anchoring (that is, a pretilt angle and alignment direction) to the liquid crystal molecules of the liquid crystal layer between the lower substrate  5  and the upper substrate  3  (S 102  and S 105 ). Thereafter, a spacer for maintaining the cell gap constant and uniform is dispersed on the lower substrate  5 . Then, the sealing material is applied on an outer portion of the upper substrate  3  to attach the lower substrate  5  to the upper substrate  3  by compression (S 103 , S 106 , and S 107 ).  
           [0012]    On the other hand, the lower substrate  5  and the upper substrate  3  are made from a glass substrate of larger area. That is, the large glass substrate includes a plurality of unit panel areas in which the driving device such as TFT and the color filter layer are formed on. To fabricate the individual liquid crystal unit panel, the assembled glass substrate should be cut into unit panels (S 108 ). Thereafter, the liquid crystal is injected into the empty individual liquid crystal unit panel through a liquid crystal injection opening (S 109 ). The liquid crystal unit panel filled with the liquid crystal is completed by sealing the liquid crystal injection opening, and each liquid crystal unit panel is inspected (S 110 ).  
           [0013]    As described above, liquid crystal is injected through the liquid crystal injection opening. At that time, the injection of the liquid crystal is induced by pressure difference. FIG. 3 shows a device for injecting the liquid crystal into the liquid crystal panel. As shown in FIG. 3, a container  12  in which the liquid crystal is contained is placed in a vacuum chamber  10 , and the liquid crystal panel is located on an upper portion of the container  12 . The vacuum chamber  10  is connected to a vacuum pump to maintain a vacuum state. Further, a liquid crystal panel moving device (not shown) is installed in the vacuum chamber  10  to move the liquid crystal panel from the upper part of the container  12  to the surface of the liquid crystal to contact an injection opening  16  of the liquid crystal panel  1  with the liquid crystal  14  (this method is called as liquid crystal dipping injection method).  
           [0014]    When the vacuum in the chamber  10  is released by introducing nitrogen gas (N2) into the vacuum chamber  10  so that the injection opening of the liquid crystal panel  1  contacts the liquid crystal, liquid crystal  14  is injected into the panel through the injection opening by the pressure difference between the pressure in the liquid crystal panel and the pressure of the vacuum chamber. After the liquid crystal is entirely filled into the panel  1 , the injection opening  16  is sealed by a sealing material to seal the liquid crystal layer (this method is called as vacuum injection method of liquid crystal).  
           [0015]    However, there are several problems in the liquid crystal dipping injection method and/or vacuum injection method as follow.  
           [0016]    First, time for the liquid crystal injection into the panel  1  is increased. Generally, a gap thickness between the driving device array substrate and the color filter substrate in the liquid crystal panel is very narrow as order of magnitude of micrometers, and therefore, a very small amount of liquid crystal is injected into the liquid crystal panel per unit time. For example, it takes about 8 hours to inject the liquid crystal completely in fabrication process of the 15 inches-liquid crystal panel  15 , the liquid crystal fabrication process time is increased due to the liquid crystal injection of long time, thereby reducing fabricating efficiency.  
           [0017]    Second, the liquid crystal consumption is increased in the above liquid crystal injection method. A small amount of liquid crystal of the liquid crystal contained in the container  12  is injected into the liquid crystal panel  10 . On the other hand, when the liquid crystal is exposed to atmosphere or to a certain gas, the liquid crystal is contaminated by reaction with the gas. Therefore, the remaining liquid crystal should be discarded after the injection when the liquid crystal  14  contained in the container  12  is injected into a plurality of liquid crystal panels  10 , thereby increasing the liquid crystal panel fabrication cost.  
         SUMMARY OF THE INVENTION  
         [0018]    Accordingly, the present invention is directed to a liquid crystal dispensing apparatus with a nozzle protecting device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.  
           [0019]    An object of the present invention is to provide a liquid crystal dispensing apparatus for dropping the liquid crystal directly onto a glass substrate of larger area including at least one unit liquid crystal panel area.  
           [0020]    Another object of the present invention is to provide a liquid crystal dispensing apparatus to prevent a dropping amount of the liquid crystal from being changed or to prevent the liquid crystal from being dropped onto another area caused as a result of distortion or breakdown of the nozzle by an external force.  
           [0021]    Still another object of the present invention is to provide a nozzle structure for a liquid crystal dispensing apparatus to prevent damage by an external force and to prevent a liquid crystal lumping phenomenon.  
           [0022]    Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
           [0023]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a liquid crystal dispensing apparatus for dispensing liquid crystal onto a substrate comprises a liquid crystal container for containing the liquid crystal to be dispensed onto the substrate; a nozzle disposed on a lower portion of the liquid crystal container, the nozzle including a main body portion, a discharging portion projecting from a lower surface of the main body portion for dispensing liquid crystal, and a protecting portion projecting from the lower surface of the main body portion for protecting the discharging portion, wherein the protecting portion projects from the lower surface of the main body portion at least as much as the discharging portion.  
           [0024]    In another aspect, a nozzle structure for a liquid crystal dispensing apparatus comprises a main body portion; a discharging portion projecting from a surface of the main body portion through which liquid crystal is dispensed; and a protecting portion projecting from the surface of the main body portion to protect the discharging portion, wherein the protecting portion projects from the surface of the main body portion at least as much as the discharging portion.  
           [0025]    In another aspect, a liquid crystal dispensing apparatus for dispensing liquid crystal onto a substrate comprises means for containing the liquid crystal to be dispensed onto the substrate; means for dispensing the liquid crystal onto the substrate as liquid crystal drops; protecting means for protecting the dispensing means from damage.  
           [0026]    In another aspect, a liquid crystal dispensing apparatus for dispensing liquid crystal onto a substrate comprises a liquid crystal container for containing the liquid crystal to be dispensed onto the substrate; a case in which the liquid crystal container is disposed; a nozzle disposed on a lower portion of the liquid crystal container; the nozzle including a main body portion, a discharging portion projecting from a lower surface of the main body portion for dispensing liquid crystal, a protecting wall formed around the discharging portion and projecting from the lower surface of the main body portion by a distance greater than the discharging portion to protect the discharging portion, and a fluorine resin formed on at least a surface of the discharging portion; a needle sheet disposed between the liquid crystal container and the nozzle, the needle sheet having a discharging hole through which the liquid crystal is discharged; a needle member disposed in the liquid crystal container, the needle member being moveable between a down position where an end of the needle member contacts the needle sheet to block flow of the liquid crystal through the discharging hole of the needle sheet and an up position where the needle is separated from the needle sheet; a spring member to bias the needle member toward the down position; a solenoid system to generate a magnetic force to move the needle member to the up position when the solenoid system is actuated; and a gas supply to provide a gas pressure to drive the liquid crystal through the nozzle when the needle member is in the up position.  
           [0027]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:  
         [0029]    [0029]FIG. 1 is a cross-sectional view showing a general LCD;  
         [0030]    [0030]FIG. 2 is a flow chart showing a conventional method for fabricating the LCD;  
         [0031]    [0031]FIG. 3 is a view showing liquid crystal injection in the conventional method for fabricating the LCD;  
         [0032]    [0032]FIG. 4 is a view showing an exemplary LCD fabricated using a method for dropping liquid crystal according to the present invention;  
         [0033]    [0033]FIG. 5 is a flow chart showing an exemplary method for fabricating the LCD according to the liquid crystal dropping method;  
         [0034]    [0034]FIG. 6 is a view showing basic concept of the liquid crystal dropping method;  
         [0035]    [0035]FIGS. 7A and 7B are views showing a structure of an exemplary liquid crystal dispensing apparatus according to the present invention;  
         [0036]    [0036]FIG. 8 is a view showing a structure of the liquid crystal dispensing apparatus of FIGS. 7A and 7B when the liquid crystal is dropped according to the present invention;  
         [0037]    [0037]FIGS. 9A and 9B are views showing a nozzle structure for the exemplary liquid crystal dispensing apparatus of FIGS. 7A and 7B according to the present invention; and  
         [0038]    [0038]FIG. 10 is a view showing another exemplary nozzle structure for a liquid crystal dispensing apparatus according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0040]    In order to solve the problems of the conventional liquid crystal injection methods such as a liquid crystal dipping method or liquid crystal vacuum injection method, a liquid crystal dropping method has been introduced recently. The liquid crystal dropping method is a method for forming a liquid crystal layer by directly dropping the liquid crystal onto the substrates and spreading the dropped liquid crystal over the entire panel by pressing together the substrates during the assembling procedure of the substrates, rather than by injecting the liquid crystal into the empty unit panel by the pressure difference between the inner and outer sides of the panel. According to the above liquid crystal dropping method, the liquid crystal is directly dropped onto the substrate in a short time period so that the liquid crystal layer in the LCD of larger area can be formed quickly. In addition, the liquid crystal consumption can be minimized due to the direct dropping of the liquid crystal as much as required amount, and therefore, the fabrication cost can be reduced.  
         [0041]    [0041]FIG. 4 is a view showing basic concept of the liquid crystal dropping method. As shown, in the liquid crystal dropping method, the liquid crystal is dropped onto a lower substrate  105  before assembling the lower substrate  105  and an upper substrate  103  having a driving device and a color filter respectively. Alternatively, the liquid crystal  107  may be dropped onto the substrate  103  on which the color filter is formed. That is, the liquid crystal may be formed either on a TFT (thin film transistor) substrate or on a CF (color filter) substrate. However, the substrate on which the liquid crystal is dropped should preferably be located on lower part when the substrates are assembled.  
         [0042]    At that time, a sealing material  109  is applied on an outer part of the upper substrate  103 , and therefore, the upper substrate  103  and the lower substrate  105  are attached as the upper substrate  103  and the lower substrate  105  are compressed. At the same time, the liquid crystal drop  107  spreads out by the pressure, thereby forming a liquid crystal layer of uniform thickness between the upper substrate  103  and the lower substrate  105 . That is, with the liquid crystal dropping method, the liquid crystal  107  is dropped onto the lower substrate  105  before the panel  101  is assembled, and subsequently the upper substrate  103  and the lower substrate  105  are attached by the sealing material  109 .  
         [0043]    [0043]FIG. 5 shows a method for fabricating the LCD by applying the above liquid crystal dropping method. As shown, the driving devices such as the TFT and the color filter layers are formed on the upper substrate and on the lower substrate with the TFT array process and the color filter process, respectively (S 201  and S 202 ). The TFT array process and the color filter process are generally similar to those of the conventional processes shown in FIG. 2. These processes are proceeded on the glass substrate having a plurality of the unit panel areas. Applying the liquid crystal dropping method to a manufacturing of the LCD, in particular, we can use effectively a glass substrate of large area having 1000×1200 mm 2  or more, which is much larger than that of the conventional fabrication method.  
         [0044]    On the lower and upper substrates on which the TFT and the color filter layer are respectively formed, the alignment layers are formed and rubbed (S 202  and S 205 ). The liquid crystal is dropped onto the liquid crystal unit panel area of the lower substrate and the sealing material is applied onto the outer portion area of the liquid crystal unit panel area on the upper substrate (S 203  and S 206 ).  
         [0045]    Thereafter, the upper and lower substrates are disposed facing each other and compressed to attach to each other using the sealing material. By this compression, the liquid crystal drops spread out on entire panel evenly (S 207 ). By this process, a plurality of liquid crystal unit panel areas, on which the liquid crystal layers are formed, are disposed on the assembled large glass substrates (the attached lower and upper substrates). Then, the assembled glass substrates are processed and cut into a plurality of liquid crystal unit panels (S 208 ). The resultant liquid crystal unit panels are inspected, thereby finishing the LCD panel process (S 208  and S 209 ).  
         [0046]    The difference between the method for fabricating the LCD by applying the liquid crystal dispensing method shown in FIG. 5 and the method for fabricating the LCD by applying the conventional liquid crystal injection method shown in FIG. 2 will be described as follows. First, there is the difference between the dropping and injecting of the liquid crystal as well as the difference in the fabricating time of a larger area LCD. Moreover, in the injection method for fabricating the LCD of FIG. 2, the liquid crystal is injected through an injection opening and then the injection opening is sealed with a sealing material. However, with the dropping method of fabricating the LCD of FIG. 5, the liquid crystal is dropped directly onto the substrate so that the sealing process of an injection opening is not needed. In addition, in the injection method of FIG. 2, the panel is contacted with the liquid crystal contained in the container during the liquid crystal injection process, thereby contaminating the outer surface of the panel. Thus, a cleaning process of the substrate is necessary. However, with the liquid crystal dispensing method of FIG. 5, the liquid crystal is directly dropped onto the substrate. Therefore, the panel is not contaminated by the liquid crystal, and the cleaning process is not needed. Accordingly, the method for fabricating LCD by the liquid crystal dispensing method is simpler than that by the liquid injection method, thereby improving efficiency and yield.  
         [0047]    In the method for fabricating LCD adopting the liquid crystal dispensing method, the dropping position of the liquid crystal and the dropping amount of the liquid crystal should be controlled to form the liquid crystal layer with a desired thickness. Since the thickness of the liquid crystal layer is closely related to the cell gap of the liquid crystal panel, the dropping position and the dropping amount of the liquid crystal should be carefully controlled to prevent the inferiority of the liquid crystal panel. Therefore, the present invention provides a dispensing apparatus for dropping specific amount of liquid crystal at a predetermined position.  
         [0048]    [0048]FIG. 6 shows a generalized arrangement for dropping the liquid crystal  107  onto the substrate  105  (glass substrate of larger area) using the liquid crystal dispensing apparatus  120  according to the present invention. As shown, the liquid crystal dispensing apparatus  120  is installed above the substrate  105 . Although not shown in FIG. 6, liquid crystal to be dropped onto the substrate is contained in the liquid crystal dispensing apparatus  120 .  
         [0049]    Generally, the liquid crystal  107  is dropped onto the substrate as drops. The substrate  105  moves in the x and y-directions at a predetermined speed while the liquid crystal dispensing apparatus  120  discharges the liquid crystal at a predetermined time intervals. Therefore, the liquid crystal  107  dropping onto the substrate  105  is generally arranged toward x and y direction with predetermined intervals therebetween. Alternatively, the substrate  105  may be fixed, while the liquid crystal dispensing apparatus  120  is moved in the x and y directions to drop the liquid crystal  107  with a predetermined interval. However, the liquid crystal drop shape may be trembled by the movement of the liquid crystal dispensing apparatus  120 , so errors in the dropping position and the dropping amount of the liquid crystal may occur. Therefore, it is preferable that the liquid crystal dispensing apparatus  120  be fixed and that the substrate  105  move.  
         [0050]    [0050]FIG. 7A is a cross-sectional view showing an exemplary liquid crystal dispensing apparatus according to the present invention, and FIG. 7B is an exploded perspective view. The liquid crystal dispensing apparatus  120  according to the present invention will now be described in detail.  
         [0051]    As shown, a cylindrical liquid crystal container  124  is enclosed in a case  122  of the liquid crystal dispensing apparatus. The liquid crystal container  124  containing the liquid crystal  107  may be made of polyethylene. Further, the case  122  is made of a stainless steel to enclose the liquid crystal container  124  therein. Generally, because the polyethylene has superior plasticity, it can be easily formed in the desired shape. Since polyethylene does not react with the liquid crystal  107  when the liquid crystal  107  is contained therein, the polyethylene can be used for the liquid crystal container  124 . However, the polyethylene has a weak strength so that it can be easily distorted by external shocks or other stresses. For example, when the polyethylene is used as the liquid crystal container  124 , the container  124  may become distorted so that the liquid crystal  107  cannot be dropped at the exact position. Therefore, the container  124  should be enclosed in the case  122  made of the stainless steel or other material having greater strength. Although not shown, a gas supply tube connected to an exterior gas supply unit may be formed on an upper part of the liquid crystal container  124 . An inert gas, such as nitrogen, is provided through the gas supply tube from the gas supply unit to fill the portion where the liquid crystal is not filled. Thus, the gas pressure compresses the liquid crystal to be dispensed.  
         [0052]    On the lower portion of the case  122 , an opening  123  is formed. When the liquid crystal container  124  is enclosed in the case  122 , a protrusion  138  formed on a lower end portion of the liquid crystal container  124  is inserted into the opening  123  so that the liquid crystal container  124  is connected to the case  122 . Further, the protrusion  138  is connected to a first connecting portion  141 . As shown, a nut (female threaded portion) is formed on the protrusion  138 , and a bolt (male threaded portion) is formed on one side of the first connecting portion  141  so that the protrusion  138  and the first connecting portion  141  are interconnected by the nut and the bolt. Of course, it should be recognized that in this description and in the following description other connection types or configurations may be used.  
         [0053]    A nut is formed on the other side of the first connecting portion  141  and a bolt is formed on one side of a second connection portion  142 , so that the first connecting portion  141  and the second connecting portion  142  are interconnected. A needle sheet  143  is located between the first connecting portion  141  and the second connecting portion  142 . The needle sheet  143  is inserted into the nut of the first connecting portion  141 , and then the needle sheet  143  is combined between the first connecting portion  141  and the second connecting portion  142  when the bolt of the second connecting portion  142  is inserted and bolted. A discharging hole  144  is formed on the needle sheet  43 , and the liquid crystal  107  contained in the liquid crystal container  124  is discharged through the discharging hole  144  passing through the second connecting portions  142 .  
         [0054]    A nozzle  145  is connected to the second connecting portion  142 . The nozzle  145  is used to drop the liquid crystal  107  contained in the liquid crystal container  124  as much as a small amount. The nozzle  145  comprises a supporting portion  147  including a bolt connected to the nut at one end of the second connecting portion  142  to connect the nozzle  145  with the second connecting portion  142 , a discharging opening  146  protruded from the supporting portion  147  to drop a small amount of liquid crystal onto the substrate as a drop, and a protecting wall  148  formed on an outer portion of the supporting portion  147  to protect the discharging opening  146 .  
         [0055]    A discharging tube extended from the discharging hole  144  of the needle sheet  143  is formed in the supporting portion  147 , and the discharging tube is connected to the discharging opening  146 . Generally, the discharging opening  146  of the nozzle  145  has very small diameter to finely control the liquid crystal dropping amount, and the discharging opening  146  protrudes from the supporting portion  147 . Therefore, the nozzle  145  may be affected by external forces when the nozzle  145  is connected to the second connecting portion  142  or separated from the second connecting portion  142 . For example, if the discharging opening  146  is distorted or damaged, when the nozzle  145  is connected to the second connecting portion  142 , the diameter and the direction of the discharging opening  146  is changed. As a result, the liquid crystal dropping onto the glass substrate cannot be controlled precisely. In addition, the liquid crystal may be sputtered through damaged portion so that the liquid crystal is dropped into unwanted position. Even the liquid crystal may not be able to be dropped at all due to a breakdown of the discharging opening  146 . Especially, if the liquid crystal drops are sputtered toward the sealing area (the area on which the sealing material is applied and the upper substrate and the lower substrate are attached thereby) due to the damage of the discharging opening  146 , the sealing material is broken around the area where the liquid crystal is sputtered when both substrates are attached, thereby causing a defect on the liquid crystal panel.  
         [0056]    The protecting wall  148  for protecting the discharging opening  146  prevents the discharging opening  146  of the nozzle  145  from being damaged. That is, as shown, the protecting wall  148  of predetermined height is formed around the discharging opening  146 , to prevent external forces from damaging the discharging opening  146 .  
         [0057]    A needle  136  is inserted into the liquid crystal container  124 , and one end part of the needle  136  is contacted with the needle sheet  143 . Especially, the end part of the needle  136  contacted with the needle sheet  143  is conically formed to be inserted into the discharging hole  144  of the needle sheet  143  to close the discharging hole  144 .  
         [0058]    Further, a spring  128  is installed on the other end of the needle  136  located in an upper case  126  of the liquid crystal dispensing apparatus  120  to bias the needle  136  toward the needle sheet  143 . A magnetic bar  132  and a gap controlling unit  134  are connected above the needle  136 . The magnetic bar  132  is made of magnetic material such as a ferromagnetic material or a soft magnetic material, and a solenoid coil  130  of cylindrical shape is installed on outer side of the magnetic bar  132  to be surrounded thereof. The solenoid coil  130  is connected to an electric power supplying unit (not shown in figure) to supply electric power thereto, thereby generating a magnetic force on the magnetic bar  132  as the electric power is applied to the solenoid coil  130 .  
         [0059]    The needle  136  and the magnetic bar  132  are separated with a predetermined interval (x). When the electric power is applied to the solenoid coil  130  from the electric power supplying unit  150  to generate the magnetic force on the magnetic bar  132 , the needle  136  contacts the magnetic bar  132  as a result of the generated magnetic force. When the electric power supplying is stopped, the needle  136  is returned to the original position by the elasticity of the spring  128 . By the movement of the needle in up-and-down direction, the discharging hole  144  formed on the needle sheet  143  is opened or closed. The end of the needle  136  and the needle sheet  143  repeatedly contact each other according to the supplying status of the electric power to the solenoid coil  130 . Thus, the part of the needle  136  and the needle sheet  143  may be damaged by the repeated shock caused by the repeated contact. Therefore, it is desirable that the end part of the needle  136  and the needle sheet  143  are preferably formed by using a material which is strong to shock, for example, the hard metal to prevent the damage caused by the shock. Also, the needle  136  should be formed of a magnetic material in this exemplary configuration to be magnetically attracted to the magnetic bar  132 .  
         [0060]    [0060]FIG. 8 shows the liquid crystal dispensing apparatus  120  in which the discharging hole  144  of the needle sheet  143  is opened by the moving of the needle  136  in the upper direction. As the discharging hole  144  of the needle sheet  143  is opened, the gas (preferably N 2  gas) supplied to the liquid crystal container  124  compresses the liquid crystal  107  to start the dropping of the liquid crystal  107  through the nozzle  145 . The dropping amount of the liquid crystal  107  is dependant upon the opening time of the discharging hole  144  and the pressure compressed onto the liquid crystal  107 . The opening time is determined by the distance (x) between the needle  136  and the magnetic bar  132 , the magnetic force of the magnetic bar  132  generated by the solenoid coil, and the elastic force of the spring  128  installed on the needle  136 . The magnetic force of the magnetic bar  132  can be controlled according to the winding number of the solenoid coil  130  installed around the magnetic bar  132  or the magnitude of the electric power applied to the solenoid coil  130 . The distance x between the needle  136  and the magnetic bar  132  can be controlled by the gap controlling unit  134 .  
         [0061]    Also, although not shown, the solenoid coil  130  may be installed around the needle  136  instead of the magnetic bar  132 . In this case, the needle  136  is made of the magnetic material, and therefore, the needle  136  is magnetized when the electric power is applied to the solenoid coil  130 . Consequently, the needle  136  moves in the upper direction to contact with the bar  132  because the bar  132  is fixed and the needle  136  moves in the up-and-down direction.  
         [0062]    [0062]FIGS. 9A and 9B provide enlarged views of portion A in FIG. 7A. Here, FIG. 9A is a perspective view, and FIG. 9B is a cross-sectional view. As shown, the protecting wall  148  is formed around the discharging opening  146  of the nozzle  145  to be the same or higher height than that of the discharging opening  146 . In an exemplary configuration, the discharging opening  146  projects a distance of about 0.8 times the distance of the protecting wall  148 . Therefore, the distortion or damage of the discharging opening  146  due to the devices such as a tool for connecting when the nozzle  145  is connected or separated can be prevented.  
         [0063]    Also, the size (diameter) of the nozzle  145  is beneficially increased due to the large protecting wall  145 . Generally, the size of the nozzle  145  is very small. Thus, it is very difficult to handle when the nozzle  145  is connected to or separated from the second connecting portion  142 . However, if the size of the nozzle  145  is increased by forming the protecting wall  148  as in the present invention, the workability of the nozzle  145  is improved thereby facilitating connection and separation of the nozzle  145 .  
         [0064]    Though the protecting wall  148  may be formed using any material that can protect the discharging opening  146  from the external force. However, the stainless steel or other hard metal with high strength is preferred.  
         [0065]    Further, as shown in FIG. 9B, a material having higher contact angle for the liquid crystal such as a fluorine resin  150  is applied around the discharging opening  146  of the nozzle  145 . The contact angle is an angle defined when liquid makes a thermodynamic balance on a surface of solid material. The contact angle of the liquid is a measure representing a wettability on the surface of the solid material. Generally, the nozzle  145  is made of the metal having the low contact angle. However, the metal has high wettability (that is, high hydrophilic property) and high surface energy. Thus, the liquid crystal very easily spreads out onto metal. In addition, if the liquid crystal is dropped through the nozzle  145  made of the metal, the liquid crystal is not disposed as drops (a drop shape means that the contact angle is high) at the end part of the discharging opening  146  on the nozzle  145 , but instead spreads out on the surface of the nozzle  145 . As the liquid crystal dropping is repeated, the liquid crystal spreads onto the surface of the nozzle  145  and lumps.  
         [0066]    The phenomenon of the liquid crystal spreading out onto the surface of the nozzle  145  makes the exact liquid crystal dropping impossible. If the amount of liquid crystal discharged through the discharging opening  146  of the nozzle  145  is controlled by controlling the opening time of the discharging opening and the gas pressure compressing the liquid crystal, some of the liquid crystal spreads out onto the surface of the nozzle  145 . Therefore, the actual dropping amount of liquid crystal is smaller than the amount of the liquid crystal discharged through the discharging opening  146 . Of course, the discharged amount may be controlled considering the amount of the liquid crystal spread out on the surface. However, it is not possible to calculate the amount of the liquid crystal spread out on the surface of the nozzle  145 .  
         [0067]    Also, since the liquid crystal lumped on the nozzle  145  by the repeated dropping operations may later be added to the amount of the liquid crystal being discharged through the discharging opening  146 , a larger dropping amount than expected may be dropped onto the substrate. That is, the dropping amount of the liquid crystal is irregular or unpredictable due to the low contact angle characteristic of the metal—liquid crystal interface.  
         [0068]    In contrast, if a fluorine resin film  150  having higher contact angle is formed on the nozzle  145 , especially, around the discharging opening  146  of the nozzle  145 , the liquid crystal  107  discharged through the discharging opening  146  makes a nearly perfect drop shape instead of being spread out on the surface of the nozzle  145 . Consequently, the liquid crystal can be dropped onto the substrate precisely as amount expected.  
         [0069]    The fluorine resin film  150  is a teflon coating film. Three basic forms of teflons, that is, polytetrafluoro ethylene (PTFE), fluorinated ethylene prophylene (FEP), and polyfluoroalkoxy (PEA) can preferably be used. Also, an organic compound can be added to the basic forms. The fluorine resin film  150  is formed on the surface of the nozzle  145  by a dipping or spraying method. In FIG. 9B, the fluorine resin film  150  is formed only around the discharging opening  146 , but it may be applied to entire nozzle  145  including the protecting wall  148 . The fluorine resin has high contact angle, and also, has various excellent characteristics such as abrasion resistance, heat resistance, and chemical resistance. Therefore, the application of the fluorine resin film  150  is able to prevent the distortion and damage of the nozzle  145  by the external forces effectively.  
         [0070]    Of course it should be recognized that the dispensing apparatus or nozzle configuration can be varied in accordance with the present invention. For example, a nozzle with a sloped discharging opening as shown in FIG. 10 can be used. Also, a container without a case can be used as disclosed in Korean Patent Application Nos. 9122/2002 and 10617/2002 which are hereby incorporated by reference.  
         [0071]    As described above, in the present invention, the protecting wall is installed and the fluorine resin film is formed on the nozzle of the liquid crystal dispensing apparatus, and therefore, following effects can be gained. First, the protecting wall is formed around the discharging opening of the nozzle, and therefore the distortion and the damage of the discharging opening can be prevented when the nozzle is connected or separated. In addition, the inferiority of the liquid crystal dropping caused by the distortion or the damage of the discharging opening can be prevented. Second, the phenomena that the liquid crystal is sputtered to the sealing area by the distortion of the discharging opening and the sealing area is broken by the sputtered liquid crystal when the upper substrate and the lower substrate are attached can be prevented by the protecting wall. Third, the fluorine resin film is formed around the discharging opening of the nozzle, thereby permitting an exact amount of liquid crystal to be dropped on the substrate. Fourth, the fluorine resin film is formed around the discharging opening and on the entire nozzle to increase the strength of the nozzle, and thereby the nozzle is not affected by the external forces.  
         [0072]    It will be apparent to those skilled in the art that various modifications and variations can be made in the liquid crystal dispensing apparatus with nozzle protecting device of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Technology Category: 7