Patent Publication Number: US-2005117107-A1

Title: In-line system and a method for manufacturing a liquid crystal display

Description:
BACKGROUND OF THE INVENTION  
      (a) Field of the Invention  
      The present invention relates to a system and method for manufacturing liquid crystal displays.  
      (b) Description of the Related Art  
      A liquid crystal display (LCD) is structured having liquid crystal material injected between two substrates. The two substrates have electrodes formed on an inner surface thereof and are joined using a sealant. A plurality of spacers are provided between the substrates to maintain a predetermined cell gap. The liquid crystal material sandwiched between the substrates is dielectrically anisotropic such that, when a voltage of a different potential is applied to electrodes of the substrates to form an electric field, the alignment of liquid crystal molecules of the liquid crystal material is varied. Accordingly, the transmittance of incident light is controlled to enable the display of images.  
      To manufacture the LCD, orientation layers for orienting the liquid crystal molecules of the liquid crystal material are first provided on the substrates, and an orientation process is performed. Next, spacers are dispersed on one of the substrates, then the sealant is applied to outer edges of the substrates. The sealant is provided with a hole through which the liquid crystal material is to be injected. Following this step, the substrates are aligned then attached through a hot press process. Next, liquid crystal material is injected through the hole of the sealant, after which the hole is sealed.  
      In the LCD manufacturing process, a plurality of liquid crystal cells, each for producing a single LCD, are formed from a single mother glass. Before the injection of the liquid crystal material, the mother glass is divided into 4, 6 or 8 liquid crystal cells (but not yet cut into these divisions), after which the process is continued on the individual liquid crystal cells.  
      A serious drawback of the conventional LCD manufacturing process is that it is time-consuming. In particular, the injection of the liquid crystal material must be performed when the space between the substrates is kept vacuum. Both keeping vacuum while maintaining the cell gap, , and injecting the liquid crystal material through the small injection hole require substantial amounts of time. Further, since the time required for each individual process may vary according to, for example, the drive method used for a particular LCD, and since there occurs a switch during production from processes performed on the mother glass to those performed on the individual liquid crystal cells, it becomes difficult to provide production equipment for the specific processes in an in-line configuration or to automate manufacture. This substantially limits the productivity improvement. Also, while injecting the liquid crystal material, the spacers become re-positioned by the forces generated from the flow of the liquid crystal material, thereby making it difficult to obtain a uniform cell gap.  
     SUMMARY OF THE INVENTION  
      The present invention has been made in an effort to solve the above problems.  
      It is an object of the present invention to provide an in-line system for manufacturing a liquid crystal display and a method for manufacturing liquid crystal displays.  
      It is another object of the present invention to simplify a method for manufacturing a liquid crystal display, and to minimize manufacturing costs and reduce the time required for manufacturing.  
      The in-line system comprises a spacer-dispersing unit for dispersing spacers on one of two substrates of a mother glass, the mother glass having at least one liquid crystal cell region; a sealant-applying unit for depositing a sealant on one of the two substrates; a liquid crystal depositing unit for depositing liquid crystal material on the substrate on which the sealant is deposited; and a substrate-attaching unit for receiving the two substrates from the sealant-applying unit or the liquid crystal depositing unit, then conjoining the substrates in a vacuum state to complete a liquid crystal display panel.  
      The method for manufacturing a liquid crystal display panel is also provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention, where:  
       FIG. 1  is a plan view of a liquid crystal panel produced using an in-line system according to a preferred embodiment of the present invention;  
       FIG. 2  is a sectional view taken along line II-II′ of  FIG. 1 ;  
       FIG. 3  is a schematic block diagram of an in-line system for manufacturing liquid crystal displays according to a preferred embodiment of the present invention;  
       FIGS. 4A and 4B  are sectional views of a spacer according to a preferred embodiment of the present invention;  
       FIGS. 5A and 5B  are plan views of a substrate for showing the formation of a sealant when manufacturing a liquid crystal display according to a preferred embodiment of the present invention;  
       FIGS. 6A, 6B  and  6 C are sectional views showing the sequential steps involved in hardening a sealant when manufacturing a liquid crystal display according to a preferred embodiment of the present invention;  
       FIGS. 7A and 7B  are views for describing the deposition of liquid crystal material when manufacturing a liquid crystal display according to a preferred embodiment of the present invention;  
       FIGS. 8A, 8B ,  8 C,  9 A, and  9 B are views for describing the adhesion of a substrate on a pressure plate when manufacturing a liquid crystal display according to a preferred embodiment of the present invention;  
       FIGS. 10, 11  and  12  are views showing a structure of a substrate-attaching unit in an in-line system according to different embodiments of the present invention;  
       FIGS. 13A, 13B ,  13 C,  13 D,  13 E and  13 F are plan views of a compression plate in a substrate-attaching unit according to a preferred embodiment of the present invention; and  
       FIG. 14  is a schematic view of an in-line system having a plurality of substrate-attaching units according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.  
       FIG. 1  shows a plan view of a liquid crystal panel produced using an in-line system according to a preferred embodiment of the present invention, and  FIG. 2  shows a sectional view taken along line II-II′ of  FIG. 1 .  
      A liquid crystal panel  100 , which is made from a single mother glass that has undergone liquid crystal injection and substrate-attachment processes, includes a plurality of liquid crystal cells. For example, four liquid crystal cell regions  111 ,  121 ,  131  and  141  are formed in the liquid crystal panel  100 . The liquid crystal panel  100  includes insulation substrates  110  and  120  opposing each other and a liquid crystal layer  130 , which is formed of liquid crystal material injected between the substrates  110  and  120 . Spherical spacers  140  are mixed in with the liquid crystal layer  130 . The spacers  140  maintain a predetermined cell gap between the substrates  110  and  120  such that the substrates  110  and  120  are substantially parallel. Further, a sealant  150  is formed around edges of each liquid crystal cell such that the liquid crystal layer  130  is sealed between the substrates  110  and  120 . Spacers may also be mixed in with the sealant  150 .  
      As described above, the liquid crystal layer  130  is injected before the liquid crystal panel  100  is divided into liquid crystal cells. The liquid crystal cells are divided along cut lines a and b, and only after completing both liquid crystal injection and substrate-attachment processes.  
      Wiring for transmitting electrical signals such as scanning signals and image signals may be formed on the substrates  110  and  120  of the liquid crystal panel  100 . The wirings intersect to define pixel regions. Thin film transistors are formed as switching devices for controlling image signals. Pixel electrodes and a common electrode are laid to form an electric field to drive liquid crystal molecules of the liquid crystal material. And an RGB color filter is formed for displaying images.  
       FIG. 3  shows a schematic block diagram of an in-line system for manufacturing liquid crystal displays according to a preferred embodiment of the present invention.  
      As shown in the drawing, an in-line system for manufacturing liquid crystal displays according to a preferred embodiment of the present invention includes a first loading unit  1000 , a spacer-dispersing unit  2000 , a sealant-applying unit  3000 , a sealant heat-treating unit  4000 , a liquid crystal depositing unit  5000  having a liquid crystal depositer  5100 , a substrate-combination unit  6000 , a second loading unit  7000 , a substrate-attaching unit  8000 , and an unloading unit  9000 . Provided between the first loading unit  1000 , the spacer-dispersing unit  2000 , the sealant-applying unit  3000 , the sealant heat-treating unit  4000 , the liquid crystal depositing unit  5000 , the substrate-combination unit  6000 , the substrate-attaching unit  8000 , and the unloading unit  9000  are in-line conveying units  1110 ,  1120 ,  1130 ,  1140 ,  1150 ,  1170  and  1180  for conveying the substrates  110  and  120  from one process to the next. The second loading unit  7000  is connected to the substrate-combination unit  6000  through an in-line conveying unit  1160 . Since the substrates  110  and  120  are attached at the substrate-attaching unit  8000  in a vacuum state between the substrates  110  and  120 , the in-line conveying units  1170  and  1180  may include vacuum chamber connecting means.  
      Manufacturing a liquid crystal display using the in-line system above will now be described.  
      First, the substrate  110 , which is loaded on the first loading unit  1000 , is transported to the spacer-dispersing unit  2000  via the in-line conveying unit  1110 . The spacers  140  are dispersed at a predetermined density on an inner face of the substrate  110  at the spacer-dispersing unit  2000 . At this time, it is preferable that the spacers  140  be spherical or cylindrical and have a diameter that is 10-30% greater than the desired cell gap between the substrates  110  and  120 . Further, if the spacers  140  are simply dispersed without securing them to the substrate  110 , external shocks or vibrations during manufacture or the flow of the liquid crystal material may displace the spacers  140  from their intended positions. This results in a non-uniform cell gap between the substrates  110  and  120 . Accordingly, it is preferable that the spacers  140  are adhered to the substrate  110  after being dispersed.  
      With reference to  FIG. 4A , according to the present invention, the spacers  140  are coated with an adhesive  142 , which is made from an epoxy group polymer. Next, infrared rays are irradiated onto the substrate  100  and the spacers  140  dispersed thereon such that the adhesive  142  on an upper portion of the spacers  140  melts down to fully surround a lower portion of the spacers  140 , as shown in  FIG. 4B . Accordingly, the spacers  140  are fixed to their positions on the substrate  110 . Instead of dispersing the spacers  140  in this manner, it is possible to form the spacers  140  through a photolithography process. This may also include the formation of the spacers  140  in the sealant. Such an alternative process is particularly advantageous for large substrates.  
      Following the above, the substrate  110  is transported from the spacer-dispersing unit  2000  to the sealant-applying unit  3000  via the in-line conveying unit  1120 . The sealant  150  is deposited on the substrate  110  at the sealant-applying unit  3000 . The sealant  150  is formed in a closed configuration, that is, the sealant  150  does not include a liquid crystal injection hole as in the prior art. Also, the sealant  150  may formed of a heat-hardening material or an infrared ray-hardening material, and may include spacers for better maintaining the cell gap between the substrates  110  and  120 .  
      Since there is no liquid crystal injection hole formed in the sealant  150 , the amount of liquid crystal material provided between the substrates is difficult to control. Too much liquid crystal material leads to damage to the sealant  150 , while an insufficient amount of liquid crystal material results in areas that are not fully filled with the liquid crystal material. To solve this problem, it is preferable that a buffer region(s) is formed in the sealant  150  such that liquid crystal material fully fills display portions and any excess liquid crystal material flows into the buffer region(s). With reference to  FIG. 5A , at least one buffer region  151  is formed in the sealant  150 . When the amount of liquid crystal material provided to the substrate  110  surpasses that needed to fill a display region c, the excess liquid crystal material flows into the buffer region  151 . As another example, with reference to  FIG. 5B , buffer regions  152 , which allow the inflow of excess liquid crystal material, are formed around a circumference of the display region c. It is preferable that the amount of liquid crystal material deposited during a subsequent liquid crystal depositing process is in excess of an amount needed to fill the display region c and less than a volume defined by the sealant  150 .  
      Next, the substrate  110  is transported from the sealant-applying unit  3000  to the sealant heat-treating unit  4000  by the in-line conveying unit  1130 . It is preferable that a reaction prevention layer is formed on a surface of the sealant  150  through an exposure or heat-treating process such that no reaction takes place between the liquid crystal layer  130  and the sealant  150 . For this purpose, it is preferable that an infrared ray-hardening material is used for the sealant  150 . During a first hardening process, the sealant  150 , with reference to  FIG. 6A , is divided into a portion  155  that is hardened and is comprised of the reaction prevention layer, and a portion  157  that has not been hardened.  
      During an initial stage of a substrate-attachment process, which is to be performed at a later point in the production process, with reference to  FIG. 6B , the reaction prevention layer of the portion  155  on the surface of the sealant  150  is pressed by the conjoining of the substrates  110  and  120 . Further, during a second hardening process with reference to  FIG. 6C , infrared rays are irradiated onto the substrates  110  and  120  such that the sealant  150  is fully hardened, thereby completing the attachment of the substrates  110  and  120 .  
      Before the attachment of the substrates  110  and  120 , however, the substrate  110  is transported to the liquid crystal depositing unit  5000  from the sealant heat-treating unit  4000  via the in-line conveying unit  1140 . Next, using the liquid crystal depositer  5100 , predetermined amounts of the liquid crystal material are deposited such that the liquid crystal layer  130  is formed to correspond to the sizes of the liquid crystal cell regions  111 ,  121 ,  131  and  141 . As shown in  FIG. 7A , the liquid crystal depositer  5100  may be a syringe-type device such that liquid crystal material  132  is provided in specific areas, that is, in the liquid crystal cell regions  111 ,  121 ,  131  and  141 . The liquid crystal depositer  5100  may also be a spray-type device, which includes a jig  5110  and a nozzle  5120  connected to the jig  5110 , which is able to provide the liquid crystal material  132  over an entire surface of the liquid crystal cell regions  111 ,  121 ,  131  and  141  as shown in  FIG. 7B .  
      The syringe-type liquid crystal depositor device is advantageous when the liquid crystal panel  100  of the mother glass is produced into a single liquid crystal cell. With this configuration, it is preferable that the substrate  110  is rotated at approximately 30-60 rpm to reduce the time required to deposit the liquid crystal material  132 . However, the spray-type liquid crystal depositor has an advantage in adjusting the liquid crystal material  132  deposition. That is, the number of nozzles  5120  as well as an application length (d) may be controlled such that the spray-type liquid crystal depositor can be used for various sizes of liquid crystal cells.  
      In the prior art, liquid crystal material is injected using a liquid crystal injection hole by keeping each of the liquid crystal cells vacuum. However, in the present invention, since the liquid crystal material  132  is either dispersed or deposited while the substrate  110  is being rotated, the manufacturing time is substantially. Further, various time periods for liquid crystal injection in the prior art as the size of the liquid crystal cells, or the characteristics of the liquid crystal material change, which is typical depending on the drive method of the liquid crystal molecules. significantly deters overall control of the production. In the present invention, on the other hand, the time for supplying the liquid crystal material  132  to the substrate  110  can be fixed regardless of liquid crystal cell size and characteristics of the liquid crystal material  132 , since because the liquid crystal material  132  is deposited or dispersed.  
      Following the processes performed in the liquid crystal depositing unit  5000 , the substrate  110  is transported to the substrate-combination unit  6000  via the in-line conveying unit  1150 . At the same time, the substrate  120  loaded on the second loading unit  7000  is transported to the substrate-combination unit  6000  through the in-line conveying unit  1160 .  
      Next, the two substrates  110  and  120  are transported to the substrate-attaching unit  8000 , which is a vacuum chamber, via the in-line conveying unit  1170 . The substrates  110  and  120  are attached to one another in a vacuum state in the substrate-attaching unit  8000 , thereby completing the liquid crystal panel  100 . The substrate-attaching unit  8000  includes a first compression plate  8100  and a second compression plate  8200 , as shown in  FIG. 3 . The substrates  110  and  120  are mounted to the compression plates  8100  and  8200 , respectively, such that they are aligned in parallel. Next, the compression plates  8100  and  8200  apply a uniform force toward each other such that the substrates  110  and  120  are pressed together. As a result of this force, the spacers  140  (see  FIG. 2 ) dispersed on the substrate  110  (and provided in the sealant  150  in some cases) are deformed. Also resulting from the compression force, the liquid crystal material deposited on the substrate  110  is spread over the entire area of the liquid crystal cell regions  111 ,  121 ,  131  and  141  (see  FIG. 1 ) to form the liquid crystal layer  130  (see  FIG. 2 ).  
      Subsequently, after a force is applied by the compression plates  8100  and  8200  such that the desired gap is obtained between the substrates  110  and  120 , an exposure unit (not shown) is used to irradiate infrared rays onto the substrates  110  and  120  for a second hardening process such that the sealant  150  is fully hardened. Accordingly, the substrates  110  and  120  are conjoined as shown in  FIG. 6 . It is preferable that the substrates  110  and  120  be precisely aligned either during the process of compressing the substrates  110  and  120  or when performing the second hardening process. Also, it is preferable that an air pressurization method be used in order to apply an even pressure to the substrates  1   10  and  120 .  
      In order to mount the substrates  110  and  120  respectively to the first and second compression plates  8100  and  8200 , a point vacuum adhesion method or a planar vacuum adhesion method may be used. When the point vacuum adhesion method is used, with reference to  FIGS. 8A, 8B  and  8 C, pipes  8110  mounted to the first and second compression plates  8100  and  8200  at areas corresponding to corner portions of the substrates  110  and  120  are pressed against the substrates  110  and  120 , then a vacuum is formed in an inside area  8111  of the pipes  8110 . Accordingly, the substrates  110  and  120  are attached to the  8100  and  8200  as long as the vacuum is maintained.  
      When the substrates are attached, center portions  112  and  122  respectively of the substrates  110  and  120  may become deformed as shown in  FIG. 8B , making it difficult to align the substrates  110  and  120  precisely. To prevent this, it is preferable that a vacuum hole be formed in the compression plates  8100  and  8200  as shown in  FIG. 8C  to keep the space between the compression plates  8100  and  8200  and the substrates  110  and  120  vacuum by pumping the air out therebetween.  
      If a planar vacuum adhesion method is used, with reference to  FIGS. 9A and 9B , a planar suction mechanism  8220  is provided on the compression plates  8100  and  8200 . The planar suction mechanism  8220  includes a plurality of openings  8221 , which can be formed in a variety of shapes over the entire area of the planar suction mechanism  8220 . After contacting the planar suction mechanism  8220  to the substrates  110  and  120 , air is drawn inwardly through the openings  8221  to adhere the substrates  110  and  120  to the compression plates  8100  and  8200 . The planar vacuum adhesion method is preferred over the point vacuum adhesion method for a variety of reasons. The substrates  110  and  120  are supported over an entire area. It can be easily applied to a variety of sizes of substrates. It can prevent substrate deformation problems. Also it can attach the substrates  110  and  120  more rigidly to the compression plates  8100  and  8200 .  
      After the above step, the conjoined substrates  110  and  120  (i.e., the completed liquid crystal panel  100 ) are transported to the unloading unit  9000  from the substrate-attaching unit  8000  through the in-line conveying unit  1180 . Next, the liquid crystal panel  100  is transported to a cutting unit (not shown) where the liquid crystal panel  100  is cut into portions corresponding to the liquid crystal cells  111 ,  121 ,  131  and  141 .  
      In the manufacturing method of the present invention described above, a vacuum must be formed in order to attach the substrates  110  and  120  to one another. The time required for forming the vacuum is greater than that needed to disperse the spacers  140 , deposit the sealant  150  or liquid crystal material, or in the actual conjoining of the substrates  110  and  120 . Overall productivity is reduced as a result. To solve this problem, a plurality of vacuum chambers may be used. Also, a method may be used that can minimize the occasions wherea vacuum must be formed. This will be described in detail with reference to the drawings.  
       FIGS. 10, 11  and  12  are views showing a structure of a substrate-attaching unit in an in-line system according to different embodiments of the present invention. Like reference numerals will be used for elements identical to those of the above embodiment.  
      First, with reference to  FIG. 10 , a substrate-attaching unit  8000  according to another embodiment includes first, second, third and fourth vacuum chambers  8300 ,  8400 ,  8500  and  8600 ; connecting units  8010 ,  8020  and  8030 , which interconnect the vacuum chambers  8300 ,  8400 ,  8500  and  8600 ; a substrate-attaching vacuum chamber  8700 ; and a connecting unit  8040  connecting the substrate-attaching vacuum chamber  8700  to the fourth vacuum chamber  8600 .  
      With this structure, the substrates  110  and  120  are moved in sequence through the first, second, third and fourth vacuum chambers  8300 ,  8400 ,  8500  and  8600 , which generate an increasingly higher vacuum, such that the substrates  110  and  120  arrive at the substrate-attaching vacuum chamber  8700  in a desired vacuum state. The substrates  110  and  120  are aligned and conjoined in the substrate-attaching vacuum chamber  8700  using the methods described previously. As a result, the vacuum chamber is not any more a bottleneck of the entire process in the in-line system, allowing the substrates  110  and  120  to keep moving through the system. This improves the productivity dramatically. Further, this structure can provide more prcise control because the number of vacuum chambers can be manipulated to correspond to a unit of time at each vacuum chamber that matches the time used in the other processes of the in-line system.  
      According to yet another embodiment, with reference to  FIG. 11 , a substrate-attaching unit  8000  includes, like the previous embodiment, first, second, third and fourth vacuum chambers  8300 ,  8400 ,  8500  and  8600 ; and a substrate-attaching vacuum chamber  8700 . However, the first, second, third and fourth vacuum chambers  8300 ,  8400 ,  8500  and  8600  are provided in parallel and are connected to the substrate-combination unit  6000  via the connecting units  1171 ,  1172 ,  1173  and  1174 , respectively, and to the substrate-attaching vacuum chamber  8700  via the connecting units  1191 ,  1192 ,  1193  and  1194 , respectively.  
      With this structure, a desired vacuum state is formed in each of the vacuum chambers  8300 ,  8400 ,  8500  and  8600 , and the substrates  110  and  120  are supplied to the vacuum chambers  8300 ,  8400 ,  8500  and  8600  from the substrate-combination unit  6000  in sequence, then they are also supplied in sequence to the substrate-attaching vacuum chamber  8700 . Accordingly, sufficient time is provided for each of the vacuum chambers  8300 ,  8400 ,  8500  and  8600  to provide the desired vacuum state, thereby preventing any back-up in the in-line system. In this embodiment also, the number of vacuum chambers may be adjusted as needed.  
      Referring now to  FIG. 12 , a substrate-attaching unit  8000  can be structured to perform a variety of processes on the substrates  110  and  120 . That is, the substrate-attaching unit  8000  includes first and second compression plates  8100  and  8200 , which have at least one vacuum hole  8900 , and a support tube  8800  provided between the compression plates  8100  and  8200 , and which seals the space therebetween.  
      With this configuration, the substrates  110  and  120  are first attached to the inner faces of the compression plates  8100  and  8200  using the methods described with reference to  FIGS. 8A, 8B ,  8 C or  9 A and  9 B, then air between the compression plates  8100  and  8200  is exhausted through the vacuum hole  8900  until a vacuum of 0.1 Torr or less is formed between the compression plates  8100  and  8200 . Next, the air within the support tube  8800  is slowly exhausted to decrease the interval between the compression plates  8100  and  8200  until the desired cell gap between the substrates  110  and  120  is obtained. Infrared rays are then irradiated onto the substrates  110  and  120  to harden the sealant  150 , thereby completing the liquid crystal panel  100  of  FIG. 1 .  
      During the formation of a vacuum between the compression plates  8100  and  8200  by exhausting air from the vacuum hole  8900 , if the liquid crystal material  132  gathers at edges of the substrate  110 , an uneven cell gap between the substrates  110  and  120  may result. To solve this problem, it is preferable that a plurality of vacuum holes  8900  be provided in specific areas of the first and second compression plates  8100  and  8200 , and the air is pupmped out in sequence from the vacuum holes  8900  to create the vacuum state. The vacuum holes  8900  may be formed at corners of the compression plates  8100  and  8200  as shown in  FIG. 13A , at center portions of side edges of the compression plates  8100  and  8200  as shown in  FIG. 13B , or both at the corners and in center portions of the side edges of the compression plates  8100  and  8200  as shown in  FIG. 13C . In addition, the vacuum holes  8900  may be formed as slits along sides of the compression plates  8100  and  8200  as shown in  FIG. 13D , as slits around corners of the compression plates  8100  and  8200  as shown in  FIG. 13E , or as slits both along the sides and the corners of the compression plates  8100  and  8200  with predetermined distances therebetween as shown in  FIG. 13F .  
      When exhausting air through the vacuum holes  8900  to form the vacuum between the compression plates  8100  and  8200 , it is preferable that the vacuum holes  8900  be used in a sequence that is suitable for the viscosity of the liquid crystal material  132 . The vacuum holes  8900  described in the various shapes and positions above can be provided in both or only one of the compression plates  8100  and  8200 .  
      In the in-line system and manufacturing method of an LCD using the in-line system described above, the majority of the processes are performed on one of the substrates  110  and  120 , after which the substrates  110  and  120  are attached together. That is, the spacers are dispersed, the sealant is formed, and the liquid crystal material is deposited on only the substrate  110 . However, it is possible to disperse the spacers on one substrate then form the sealant and deposit the liquid crystal material on the other substrate. If this alternative method is used, the spacer-dispersing unit  2000  of  FIG. 3  is connected between the second loading unit  7000  and the substrate-combination unit  6000  through in-line conveying units.  
      Further, the in-line system described above is designed with a single substrate-attaching unit  8000  having vacuum chambers. However, it is possible to provide a plurality of substrate-attaching units. This will be described in detail with reference to  FIG. 14 .  
       FIG. 14  shows a schematic view of an in-line system having a plurality of substrate-attaching units according to another embodiment of the present invention.  
      As shown in the drawing, the in-line system includes (a) a substrate-combination unit  6100  that is provided with the first substrate  110 , on which are deposited the sealant  150  and the liquid crystal material  132 , and the second substrate  120 , on which the spacers  140  are dispersed; and (b) a plurality of substrate-attaching units  8001 ,  8002  and  8003 , which are each provided with a pair of substrates  110  and  120  for assembly from the substrate-combination unit  6100 . The number of substrate-attaching units can be adjusted as needed. With this configuration, the in-line system can keep operating without delays due to the relatively slow processes involved in the substrate-attaching units.  
      Although preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims.