Patent Publication Number: US-2007095468-A1

Title: Sealant dispensing apparatus, liquid crystal display panel manufactured using the same and method of manufacturing liquid crystal display panel

Description:
BACKGROUND OF THE INVENTION  
      1. Technical Field  
      The present disclosure relates to a sealant dispensing apparatus, a liquid crystal display panel manufactured using the sealant dispensing apparatus, and a method of manufacturing the liquid crystal display panel. More particularly, the present disclosure relates to a sealant dispensing apparatus, wherein curing agents having different natures are simultaneously dispensed at the inner and outer sides to prevent leakage of the liquid crystal  
      2. Discussion of the Related Art  
      A liquid crystal displays (LCD) device, when compared with a conventional cathode ray tube (CRT) is lightweight, thin and can include a large display window. The LCD device can function as a fiat display device, and has been used as a display device of, for example, a cellular phone, PDA, digital camera and camcorder, and has also been used as a monitor for a desktop computer and a larger scale display device. That is, the application range of the LCD device has been rapidly increased. An LCD device produces a high quality image including such features as high definition, high brightness and large display area while maintaining a lightweight and compact construction and low power consumption.  
      A liquid crystal panel of an LCD device includes a lower substrate having pixel electrodes and thin film transistors in a liquid crystal region and an upper substrate including common electrodes and color filters in the liquid crystal region. Liquid crystal is charged and sealed between the two substrates. The substrates are, in turn, are bonded with each other.  
      Conventionally, a liquid crystal injection method in which two substrates are bonded with each other and liquid crystal is then injected between the substrates has been employed. For example, an epoxy-based sealant is first coated along edges of the liquid crystal regions in the lower and upper substrates in such a manner that the sealant is not coated in a liquid crystal injection hole region through which the liquid crystal is injected. Then, the two substrates are overlapped and aligned and pressed at a temperature of above about 200° C. such that the epoxy-based sealant can be cured to form a sealing pattern for bonding the substrates with each other. At this time, due to the sealing pattern, a desired cell gap is provided between the upper and lower substrates. Next, the cell gap is vacuumed and liquid crystal is then injected between the upper and lower substrates using the capillary phenomenon and pressure difference. After injecting the liquid crystal, the liquid crystal injection hole is sealed to complete the liquid crystal display panel.  
      In the above conventional method, since liquid crystal should be injected through a small liquid crystal injection hole, there the liquid crystal slowly penetrates into the panel and thus productivity is decreased. In a case where the liquid crystal injection hole is expanded in order to improve the productivity, the sealing effect obtained by the epoxy-based sealant is deteriorated.  
      Therefore, a liquid crystal drop method has been proposed. In the liquid crystal drop method, liquid crystal is dropped on a substrate when forming a sealing pattern and the substrates are then bonded to each other.  
      The epoxy-based sealant has a thermosetting property, and should be pressed at a high temperature such that it can be cured. For example, when an epoxy-based sealant is coated on the substrate and liquid crystal is then dropped thereon, the two substrates are stacked one above another and then pressed at a high temperature to form a sealing pattern for sealing a liquid crystal region. Then, liquid crystal is charged and sealed in the liquid crystal region within the sealing pattern. In a case where a thermosetting epoxy-based sealant is used in the conventional liquid crystal drop method, the electrical and optical properties of the liquid crystal may be lost  
      Accordingly, research for using an acrylic-based sealant having a photocurable property instead of using the epoxy-based sealant has been performed. For example, an acrylic-based sealant is coated on a substrate and liquid crystal is then dropped thereon. Then, the two substrates are stacked one above another and the acrylic-based sealant is cured by means of ultraviolet (UV) light to form a sealing pattern, in which the liquid crystal is charged. It is known to mix an epoxy-based thermosetting sealant with the acrylic-based photocurable sealant since sufficient adhesive strength has not been obtained only with the acrylic-based photocurable sealant.  
      Where the acrylic-based photocurable sealant is employed, uncured acrylic-based photo curable sealant contacts and reacts with the liquid crystal. As a result, foreign substances and contaminants are produced, which can produce a defective device. For example, in a liquid crystal drop process, two substrates with liquid crystal dropped thereon are stacked and pressed, and light is then irradiated to cure the sealant. At this time, the liquid crystal is spread due to the pressing of the substrates. When the sealant, which has not completely cured, is brought into contact with the spreading liquid crystal, the foreign substances and contaminants are produced. In addition, such foreign substances and contaminants can result in defects such as, for example, residual images on the LCD device and stains in the display area.  
      Furthermore, a UV shielding film can exist in the liquid crystal display panel such that UV cannot be irradiated over a sufficient area. Therefore, the acrylic-based sealant remains in the sealing pattern in a state where it is not completely cured. If the temperature of the liquid crystal panel is increased to thermally cure the sealant, the molecular motion of the acrylic-based sealant is promoted to thereby cause a risk of diffusing the sealant into the liquid crystal layer.  
     SUMMARY OF THE INVENTION  
      In accordance with embodiments of the present invention, there is provided a sealant dispensing apparatus, a liquid crystal display panel manufactured using the sealant dispensing apparatus, and a method of manufacturing the liquid crystal display panel, in which inner and outer sides adjacent to a liquid crystal region are coated with sealants having different properties to prevent bursting of liquid crystal dropping the liquid crystal and to prevent the generation of by-products due to a reaction between the liquid crystal and uncured sealant. The different sealants can be simultaneously coated on the inner and outer sides.  
      According to an embodiment of the present invention, a sealant dispensing, apparatus comprises a body having an injection nozzle, a partition plate for dividing the interior of the body into at least two spaces, and an injection pressure application section for applying an injection pressure to the spaces divided by the partition plate.  
      The interior of the body can be divided into first and second spaces by the partition plate.  
      The sealant dispensing apparatus may further comprise a sealant mixing ratio control member for controlling a mixing ratio of sealants in the mixed sealant. The sealant mixing ratio control member may include a barrier installed in the injection nozzle. Further, the barrier may be rotatably installed and the mixing ratio of sealants in the mixed sealant may vary, with an angle defined by the barrier and the partition plate. Furthermore, the sealant mixing ratio control member may include an injection pressure controller for controlling the injection pressure of the injection pressure application section.  
      When a width of the injection nozzle is defined as one (1), a width of the first space of the injection nozzle is within a range of about 0.01 to about 0.8, a width of the second space of the injection nozzle is within a range of about 0.01 to about 0.8.  
      The partition plate may extend from an upper end of the injection nozzle to an upper portion of the body.  
      The sealant dispensing apparatus may further comprise a rotating member for rotating the body.  
      According to another embodiment of the present invention, there is provided a liquid crystal display panel, which comprises upper and lower substrates positioned opposite to each other, a sealing pattern formed along edges of the opposite upper and lower substrates, and liquid crystal interposed inward of the sealing pattern, wherein the sealing pattern comprises at least two sealants whose mixing ratio is changed in a widthwise direction of the sealing pattern.  
      Inner and outer sides of the sealing pattern can be provided with first and second sealants  203  having different curing rates, respectively. The first and second sealants may have different curing rates based on temperature. The first and second sealants may have different curing rates based on light polymerization. The first sealant may be an acrylic-based or epoxy-acrylic hybrid based sealant, and the second sealant may be an epoxy-based sealant.  
      A mixed sealant of the epoxy-based sealant or epoxy-acrylic hybrid based sealant and the acrylic-based sealant may be formed on an interface of the two sealants.  
      When a width of the sealing pattern is defined as one (1), a width of the first sealant is within a range of about 0.01 to about 0.8, a width of the second sealant is within a range of about 0.01 to about 0.8, and a width of the mixed sealant is no more than about 0.95.  
      A color filter substrate with a color filter formed thereon may be used as the upper substrate and a TET substrate with a TFT pattern formed thereon may be used as the lower substrate.  
      According to another embodiment of the present invention, a method of fabricating a liquid crystal display panel, comprises the steps of preparing a lower substrate with a pixel pattern formed thereon and an upper substrate with a color filter pattern formed thereon; forming a sealing pattern along edges of at least one of the lower and upper substrates, the sealing pattern comprising a first sealant provided on an inner side thereof and a second sealant provided on an outer side thereof; dropping liquid crystal inside of the sealing pattern; bonding the lower and upper substrates in such a manner that the color filter pattern and the pixel pattern are aligned to each other, and irradiating LV onto the substrates to cure the second sealant provided in the outer side of the sealing pattern; and performing heat treatment to cure the uncured sealant of the sealing pattern  
      The step of forming the sealing pattern may comprise the steps of securely placing the lower or upper substrate on a movable and rotatable stage; and coating a sealant onto edges of the lower or upper substrate using a sealant dispensing apparatus while moving and rotating the stage, wherein the sealant dispensing apparatus includes first and second spaces in which first and second sealants are accommodated, respectively.  
      The first and second sealants may, have different curing rates based on temperature and light polymerization, and the first sealant may be an acrylic-based sealant or epoxy-acrylic hybrid based sealant, and the second sealant may be an epoxy-based sealant.  
      The step of forming the sealing pattern may comprise securing the lower or upper substrate on a movable stage: coating the first and second sealants onto the edges of the lower or upper substrate using a sealant dispensing apparatus while laterally moving the stage, the sealant dispensing apparatus including first and second spaces for accommodating the first and second sealants, respectively; and rotating the sealant dispensing apparatus such that the first sealant is coaled inward of the second sealant. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Exemplary embodiments of the present invention can be understood in more detail from the following description taken in conjunction with the accompanying drawings, in which:  
       FIG. 1  is a perspective view of a liquid crystal display panel according to an embodiment of the present invention;  
       FIG. 2  is a sectional view taken along line A-A of  FIG. 1 ;  
       FIG. 3   a  is a graph showing a curing time of an epoxy-based sealant as a function of molecular weight;  
       FIG. 3   b  is a graph showing a curing time of an acrylic-based sealant as a function of molecular weight;  
       FIGS. 4 and 5  show a sealant dispensing apparatus according to an embodiment of the present invention;  
       FIG. 6  shows a composition ratio of a sealant coated on a substrate by the sealant dispensing apparatus according to an embodiment of the present invention;  
       FIG. 7  shows nozzle regions of the sealant dispensing apparatus according to an embodiment of the present invention;  
       FIG. 8  shows composition ratios of a sealant coated on a substrate according to an embodiment of the present invention; and  
      FIGS.  9  to  11  are perspective views illustrating a method of manufacturing a liquid crystal display panel according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS  
      Exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein.  
       FIG. 1  is a perspective view of a liquid crystal display panel according to an embodiment of the invention and  FIG. 2  is a sectional view taken along line A-A of  FIG. 1 .  
       FIG. 3   a  is a graph showing a curing time of an epoxy-based sealant, and  FIG. 3   b  is a graph showing a curing time of an acrylic-based sealant.  
      Referring to  FIGS. 1 and 2 , the liquid crystal display (LCD) device includes upper and lower substrates  120  and  110  of an LCD panel, a sealing pattern  130  formed along edges of the opposite upper and lower substrates  120  and  110 , and liquid crystal  140  interposed between the upper and lower substrates and inward of the sealing pattern  130 .  
      A color filter substrate with a color filter formed thereon may be used as the upper substrate  120 , and a thin-film transistor (TFT) substrate with a TFT pattern formed thereon is used as the lower substrate  110 . On the lower substrate  110  are formed a plurality of gate lines arranged at regular intervals in one direction, a plurality of source lines arranged at regular intervals perpendicular to the gate lines, a plurality of pixel electrodes  118  formed in a matrix form on a pixel region defined by the gate lines and source lines intersecting each other, and a plurality of thin film transistors which are switched by gate line signals to transmit source line signals to the respective pixel electrodes. Each of the thin film transistors includes a gate electrode ll 1 , a gate insulation film  112 , an active layer  113  and ohmic contact layer  114 , a source electrode  115  and a drain electrode  116 . A protective layer  117  is further provided for insulation between the thin film transistor and the pixel electrode  118 . In addition, on the upper substrate  120  are formed a black matrix layer  121  for blocking light from portions other than the pixel region, an R/G/B color filter layer  122  for displaying a color image, an overcoat layer  123  for protecting the color filter layer  122 , and a common electrode  124  for implementing an image.  
      In addition, the sealing pattern  130  comprises at least two kinds of sealant having different compositions. The sealants may be coated simultaneously, using a single sealant dispensing apparatus, which will be described further below. An area to be brought into contact with the liquid crystal  140  is coated with a sealant not reacting with the liquid crystal  140 , and the remaining areas are coated with a sealant having a higher curing rate.  
      As illustrated in  FIG. 1 , the sealing pattern  130  is formed in a band form along the edges of the opposite upper and lower substrates  120  and  110 . The inner and outer sides of the sealing pattern  130  are coated with sealants having different curing rates Sealants having different curing rates due to heat and/or light polymerization may be used as the sealants having the different curing rates.  
      The sealing pattern  130  is formed in such a manner that an epoxy-based thermosetting sealant  131  is provided at the inner side thereof and an acrylic-based photocurable sealant  133  is provided it the outer side thereof. Alternatively, an epoxy-acrylic hybrid based sealant may be provided at the inner side of the sealing pattern  130 , instead of the epoxy-based thermosetting sealant  13 l.  
      The epoxy-based sealant  131  is a thermosetting resin and causes condensation polymerization. As shown in  FIG. 3   a,  therefore, the epoxy-based sealant has a lower polymerization rate than the acrylic-based sealant  133  but exhibits good adhesive strength and lower absorption. In addition, the epoxy-based sealant  131  has low reactivity with a liquid crystal  140 , and thus, foreign substances and contaminants are not produced. Therefore, the epoxy-based sealant  131  is coated onto the area brought into contact with the liquid crystal  140  to avoid the chemical reaction with the liquid crystal  140 . The acrylic-based sealant  133  is a UV-curable resin and causes chain polymerization. As shown in  FIG. 3   b  therefore, the acrylic-based sealant has a higher polymerization rate than the epoxy-based sealant  131 , but provides relatively lower adhesive strength. In addition the acrylic-based sealant  133  reacts with the liquid crystal before it is cured. Therefore, an acrylic-based sealant  133  is disposed outwards of an epoxy-based sealant  131  such that the acrylic-based sealant can be rapidly cured to prevent the liquid crystal  140  from leaking to the outside when the two substrates are pressed. An epoxy-acrylic hybrid sealant exhibits hybrid properties of the epoxy-based sealant  131  and the acyclic-based sealant  133 . The acrylic-based sealant can be cured by heat, but the epoxy-based sealant cannot be cured by UV.  
      As described above, the high curing rate of the acrylic-based sealant  133  provides an improved hardness of the sealing pattern  130 , thereby preventing bursting of the sealing pattern  130  due to the diffused liquid crystal. The epoxy-based sealant  131  has a lower curing rate but has a good curing rate due to heat and adhesive strength as compared to the acrylic-based sealant  133 . Thus, uncured acrylic-based sealant  133  can be prevented from diffusing into the liquid crystal region and the adhesive strength between the two substrates  110  and  120  can be improved. Furthermore, the generation of foreign substances and contaminants due to reaction with the liquid crystal can be avoided. The epoxy-based sealant and the acrylic-based sealant are simultaneously coated to take advantage of the properties of both sealants.  
      Hereinafter, a sealant dispensing apparatus capable of simultaneously coating sealants having different characteristics to form the aforementioned sealing pattern will be explained.  
       FIGS. 4 and 5  are views illustrating a sealant dispensing apparatus according to an embodiment of the present invention.  
      Referring to  FIGS. 4 and 5 , the sealant dispensing apparatus  200  includes a body  220  having an injection nozzle  210 , a partition plate  230  for dividing the interior of the body  220  into at least two spaces, and an injection pressure application section  240  for applying injection pressure to the two spaces  231  and  232  divided by the partition plate  230 . The body  220  is divided into the first and second spaces  231  and  232  by the partition plate  230 . The first and second spaces  231  and  232  are accommodated with first and second sealants having different curing rates, respectively. Sealants having the different curing rates due to heat and/or light polymerization are used as the first and second sealants. For example, the first space  231  includes the epoxy-based sealant  131  and the second space  232  includes the acrylic-based sealant  133 .  
      The partition plate  230  extends from an upper end of the injection nozzle  210  to an upper portion of the body  220 . Thus, the epoxy-based sealant  131  and the acrylic-based sealant  133  can be separated from each other in the body  220  in such a state where they remain unmixed with each other. The body  220  may be either evenly divided or unevenly divided by the partition plate  230  depending on the injection pressure and the amount of sealant injected.  
      The injection pressure application section  240  is configured in such a manner that the epoxy-based sealant  131  and the acrylic-based sealant  133  in the first and second spaces  231  and  232  can be injected out of the apparatus  200  at a uniform pressure through the injection nozzle  210 . Different injection pressures may be applied to the first and second spaces  231  and  232 . The injection pressure application section  240  may, for example, employ a mechanical means such as a piston or apply air pressure to the first and second spaces  231  and  232  to inject the sealants  131  and  133  to the outside.  
      In addition, as shown in  FIG. 5 , the sealant dispensing apparatus  200  can apply the sealants onto substrates  110  and  120  while the substrates are moving, and the sealant dispensing apparatus is fixed to a shaft  300 .  
      For example, in order to apply a sealant along the edge of the rectangular glass substrates  110  and  120 . the sealant is continuously coated while changing the direction of the movement of the glass substrates  10  and  120  laterally by 90 degrees at the corner area thereof without rotation and at the same time the sealant dispensing apparatus  200  should rotate by 90 degrees.  
      A rotating member  250  for rotating the sealant dispensing apparatus  200  is further provided. That is, in a case where the direction of the movement of the substrates  100  and  120  is changed laterally without rotation the body  220  of the sealant dispensing apparatus  200  is also preferably rotated by 90 degrees. By means of the rotating member  250 , the inner sides of the edges of the rectangular substrates  110  and  120  can be coated with the epoxy-based sealant  131  and the outer sides thereof can also be coated with the acrylic-based sealant  133 .  
      When an injection pressure is applied to the first and second spaces  231  and  232  divided by the partition plate  230  through the injection pressure application section  240 , the epoxy-based sealant  131  in the first space  231  and the acrylic-based sealant  133  in the second space  232  are injected through the injection nozzle  210 . At this time, the two sealants which have been separated by the partition plate  230  are brought into contact with each other within the injection nozzle.  
       FIG. 6  is a graph showing the composition ratio of sealants coated by the sealant dispensing apparatus according to an embodiment of the present invention.  
      As shown in  FIG. 6 , in a case where two different sealants are coated onto the substrates  110  and  120  by means of the sealant dispensing apparatus  200  for simultaneously injecting the two sealants, the acrylic-based sealant  131  and the epoxy-based sealant  133  are mixed within the injection nozzle  210  of the sealant dispensing apparatus  200 . Accordingly, the sealant layer coated on the substrates  110  and  120  is composed of an epoxy-based sealant  131  at its inner side, an acrylic-based sealant  133  at its outer side, and a mixed sealant  132  at an intermediate region corresponding to an interface of the inner and outer sides.  
      Referring to  FIG. 6 , the relationship between the width of the epoxy-based sealant  131 , the acrylic-based sealant  133 , and the mixed sealant is defined. For example, if the total width M of the whole sealant layer formed on the substrate is one (1), the width J of the epoxy-based sealant  131  is within a range of about 0.05 to about 0.8, for example, within a range of about 0.05 to about 0.5. In addition, the width L of the acrylic-based sealant  133  is within a range of about 0.01 to about 0.8, for example, within a range of about 0.05 to about 0.5. The width can vary with the degree of spreading of the liquid crystal  140  between two substrates  110  and  120 , the magnitude of pressing force exerted on the substrates  110  and  120 , the curing characteristics of the sealants, and the injection pressure of the sealant dispensing apparatus  200 . The widths of the epoxy-based sealant  131  and the acrylic-based sealant  133  represent the widths of regions, respectively, where pure acrylic-based and epoxy,-based sealant compositions exist.  
      In addition, for example, the mixed sealant  132  has a width K of no more than about 0.95. The two different sealants can be mixed with each other at their interface when they are brought into contact with each other. The mixing degree of the sealants can vary with the coating conditions as well as the characteristics of the sealants. Here. the width of the mixed sealant  132  is a width of a region occupied by the mixture of the acrylic-based sealant  133  and the epoxy-based sealant  131 . Depending on the characteristics of the two sealants to be mixed, the mixed sealant  132  may not be formed at all or may be slightly formed.  
      The sealant dispensing apparatus according to an embodiment of the present invention may further include a sealant mixing ratio controller for controlling the mixing ratio of the mixed sealant. Hereinafter, an embodiment of the present invention in which a barrier is included in the injection nozzle as the sealant mixing controller will be explained. It is to be understood that the present invention is not limited to the following description but may employ a variety of members capable of controlling the mixing ratio of the mixed sealant. For example, an injection pressure controller for controlling the injection pressure of sealants may be used as the sealant mixing controller.  
       FIG. 7  shows nozzle regions of a sealant dispensing apparatus according to an embodiment of the present invention.  FIG. 8  shows the mixing ratios of a resultant sealant coated on the substrate based on different orientations of a mixing controller, according to an embodiment of the present invention.  
      Referring to  FIGS. 7 and 8 , a sealant dispensing apparatus  200  includes a barrier capable of rotating in the injection nozzle  210 . The barrier  260  serves to adjust the widths of the epoxy-based sealant  131 , the mixed sealant  132 , and the acrylic-based sealant  133 . Accordingly, the mixing ratio of the resultant sealant layer coated on the substrates  110  and  120  can be adjusted as desired by using the vortex phenomenon of fluid and the injection pressure, as shown in  FIG. 7 . As shown in  FIG. 7  ( a ), if the injection pressure is increased while adjusting the barrier  260  in a vertical direction, the epoxy-based sealant  131  and the acrylic-based sealant  131  in the first and second spaces  231  and  232  of the body  220  are coated on the substrates  110  and  120  without generating the vortex. In addition, as shown in  FIG. 7  ( b ) and  FIG. 7  ( c ), if the rotating angle of the barrier  260  is adjusted, the vortex phenomenon occurs, and thus, the amount of the mixed sealant in which the epoxy-based sealant  131  and the acrylic-based sealant  133  are mixed varies in a central area of the coated sealant layer. That is, as shown in the figures, as the vortex becomes stronger, the sealants are more smoothly mixed in the injection nozzle.  
      As described above, by means of the barrier  260  provided in the injection nozzle  210 , the width of the epoxy-based sealant  131  placed at the inner side, the width of the acrylic-based sealant  133  provided at the outer side, and the width of the mixed sealant  132  disposed between the inner and outer sides can be adjusted, as illustrated in  FIG. 8 . Although it has been shown in some of the drawings that the widths of the epoxy-based sealant  131  and the acrylic-based sealant  133  are the same, the present invention is not limited thereto. That is, the widths may vary, depending on the processing conditions. For example, in a case where the leakage of liquid crystal is detected after the upper and lower substrates  120  and  110  are bonded and irradiated with UV, the width of the acrylic-based sealant  133  can be increased such that more sufficient sealing effect can be obtained. Further, in a case where foreign substances and contaminants are produced in the liquid crystal after the heat treatment, the uncured acrylic-based sealant  133  can be sufficiently sealed by increasing the width of the epoxy-based sealant  131 .  
      Hereinafter, a method of manufacturing a liquid crystal display panel using the sealant dispensing apparatus will be described.  
      FIGS.  9  to  11  are perspective views illustrating a method of manufacturing a liquid crystal display panel according to an embodiment of the present invention.  
      Referring to  FIG. 9 , a lower substrate  110  and an upper substrate  120  are fabricated. That is, a thin film transistor, a gate line, a source line, a pixel electrode and a holding line are formed on the lower substrate  110 . Further, a black matrix, a color filter and a common electrode are formed on the upper substrate  120 .  
      A sealing pattern  130  is formed along the edges of the lower and upper substrates  110  and  120  by using the sealant dispensing apparatus  200  such that an epoxy-based sealant  131  is disposed on the inner side of the sealing pattern  130  and an acrylic-based sealant  133  is disposed on the outer side thereof. Further, liquid crystal  140  is dropped on the lower substrate  110 .  
      In order to form the sealing pattern  130 , the substrates  110  and  120  are mounted on a movable and rotatable stage (not shown). Then, the epoxy-based  131  and the acrylic-based sealant l 33  are simultaneously coated on the substrates  110  and  120  through a single nozzle of the sealant dispensing apparatus  200  fixed to a fixing shaft according to an embodiment of the present invention. The substrates  110  and  120  are moved in fore-and-aft and left-and-right directions and rotated by 90 degrees at the vertex or corner region. The sealant dispensing apparatus  200  is also rotated by 90 degrees in accordance with the rotation of the substrates  110  and  120 . Thus, a sealing pattern in the form of a rectangular band is formed along the edges of the substrate such that the epoxy-based sealant  133  is coated on the inner side of the sealing pattern  130  and the acrylic-based sealant  133  is coated on the outer side of the sealing pattern  130 . As described above, the two sealants l 31  and  133  having different properties can be coated on the substrates  110  and  120  at the same time, and thus, the process of bonding the substrates and scaling the liquid crystal can be simplified. In addition, the liquid crystal is dropped in the liquid crystal region corresponding to a region inside of the sealing pattern  130 , by means of a liquid crystal dropping device.  
      Although it has been illustrated in the figures that the sealing pattern  130  is formed along the edges of both the lower and upper substrates  110  and  120 , the present invention is not limited thereto. Alternatively, the sealing pattern  130  may be formed on any one of the lower and upper substrates  110  and  120 . Further, although it has been illustrated that the liquid crystal  140  is dropped only on the lower substrate  110 , the present invention is not limited thereto. Alternatively, the liquid crystal may be dropped either on the upper substrate  120  or on both the lower and upper substrates  110  and  120 .  
      Referring to  FIG. 10 , the lower and upper substrates  110  and  120  are aligned and bonded and then irradiated with UV to thereby cure the acrylic-based sealant  133  provided on the outer side of the sealing pattern  130 .  
      The lower substrate  110  and the upper substrate  120  are bonded with each other such that the color filter pattern formed on the upper substrate  120  and the pixel electrode pattern formed on the lower substrate are aligned. The bonded substrates are irradiated with UV to faster cure the acrylic-based sealant  133  provided on the outer side of the sealing pattern  130 . In addition, when the upper and lower substrates  120  and  110  are bonded with each other, the liquid crystal  140  dropped on the lower substrate  110  is spread outward as shown in  FIG. 10 . At this time, the liquid crystal  140  dropped in an area adjacent to the sealing pattern  130  is spread toward the sealing pattern  130  but not leaked to the outside of the sealing pattern  130  since the acrylic-based  133  provided on the outer side of the sealing pattern  130  has been already cured by UV. Furthermore, since the epoxy-based sealant  131  is provided between the acrylic-based sealant  133  and the liquid crystal  140 , it is possible to prevent the liquid crystal  140  from chemically reacting with the uncured acrylic-based sealant  133 .  
      A spacer (not shown) in the form of a post is provided in a part of the sealing pattern formed between two substrates  110  and  120 . Thus, when bonding the two substrates  110  and  120 , it is possible to prevent the sealing patterns formed on the opposite substrates from being damaged and to maintain a certain gap between the two substrates  110  and  120 . Further, when the two bonded substrates  110  and  120  are pressed, the liquid crystal dropped in a space between the two substrates  110  and  120  can be uniformly distributed due to the sealing pattern  130 .  
      Referring to  FIG. 11 , the heat treatment is performed to cure the uncured sealant of the sealing pattern  130  such that a finished LCD panel can be manufactured.  
      The bonded substrates  110  and l 20  in which the acrylic-based photocurable sealant  133  provided on the outer side of the sealing pattern  130  has been cured, is loaded into a heating furnace. Then, the substrates are heat treated for about 30 minutes to about 2 hours at a temperature of about 100° C. to about 150° C. to cure the epoxy-based thermosetting sealant  131  provided on the inner side of the sealing pattern  130  and the acrylic-based photocurable sealant  133  that may have been left uncured by the previous UV irradiation. The epoxy-based thermosetting sealant  13 l having good adhesive strength is cured through this heat treatment, and thus, the adhesive strength between the upper and lower substrates  120  and  110  can be improved. The heat treatment is preferably performed such that the liquid crystal  140  cannot be damaged due to the heat treatment temperature and the uncured acrylic-based sealant  133  and epoxy-based sealant  131  can be sufficiently cured. During the heat treatment, the substrates  110  and  120  can be continuously pressed to improve the spreading characteristic of the liquid crystal. Even though the uncured acrylic-based photocurable sealant  133  provided on the outer side of the sealing pattern  130  can be cured and its molecular motion is increased during the above heat treatment process, the epoxy-based thermosetting sealant provided on the inner side of the sealing pattern  130  is cured to prevent the acrylic-based photocurable sealant  133  from being penetrated into the liquid crystal region.  
      A single LCD panel or a plurality of LCD panels may be formed on a large mother substrate and incorporate the sealing pattern comprising the acrylic-based sealant and the epoxy-based sealant in accordance with embodiments of the present invention.  
      According to the embodiments of the present invention. a sealant not reacting with liquid crystal and a sealant having a good curing rate can be simultaneously coated on the inner and outer sides of the liquid crystal region respectively by using a single sealant dispensing apparatus.  
      Further, the acrylic-based optical sealant used as the outer sealant can be cured faster through the UV irradiation to thereby prevent bursting of liquid crystal, and the epoxy-based thermosetting sealant used as the inner sealant can prevent a chemical reaction between the acrylic-based sealant and the liquid crystal.  
      In addition, since the inner and outer sealants can be simultaneously coated on the substrate, the process of bonding the substrate and sealing the liquid crystal can be simplified.  
      Furthermore, since a partition plate is provided in the sealant dispensing apparatus, sealants having different properties can be stored without being mixed with each other.  
      Moreover, since a barrier is further provided in an injection nozzle of the sealant dispensing apparatus, the mixing ratio of sealants to be coated on the substrate can be adjusted as desired.  
      Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments. and that various other changes and modifications may be affected therein by one of ordinary skill in the related art without departing from the scope or spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as defined by the appended claims.