Abstract:
Techniques for successively fabricating liquid crystal cells at low cost, using two resinous substrates wound on their respective rolls. A color filter and an electrode pattern are formed by printing techniques. Furthermore, an orientation film is printed. These manufacturing steps are carried out successively by rotating various rolls.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a method of fabricating liquid-crystal electrooptical devices using flexible film substrates and also to a system for fabricating such liquid-crystal electrooptical devices using flexible film substrates.  
           [0003]    2. Description of the Related Art  
           [0004]    A liquid-crystal electrooptical device is known as a thin, small-sized, lightweight display device. The liquid-crystal electrooptical device comprises a pair of substrates spaced several micrometers from each other and a liquid crystal material held between the substrates. The substrates are required to transmit visible light and so glass substrates are generally used as the substrates. The glass substrates have the required optical characteristics. In addition, they are inexpensive.  
           [0005]    The liquid-crystal electrooptical device must meet the following technical requirements: (1) It is small in size and lightweight; and (2) the cost of fabricating the liquid-crystal electrooptical device is reduced and its productivity is improved.  
           [0006]    Of these requirements, the requirement (1) is that the liquid-crystal electrooptical device is made thinner and lighter in weight. A known configuration which satisfies these requirements uses resinous substrates (generally known also as plastic substrates) transmitting light.  
           [0007]    Where resinous substrates are employed, reductions in size and weight can be accomplished. Since the substrates themselves have flexibility, a physical stress can be applied to them, or they can be used in a curved state. These kinds of usage can further extend the application of the liquid-crystal electro-optical device.  
           [0008]    However, where resinous substrates are used, a reduction in fabrication cost and an improvement in the productivity are not accomplished.  
         SUMMARY OF THE INVENTION  
         [0009]    It is an object of the present invention to provide techniques for fabricating liquid-crystal electrooptical devices, using flexible substrates, at low cost and with high productivity.  
           [0010]    A system for fabricating liquid crystal cells according to the present invention comprises a first roll on which a first flexible substrate has been wound, a second roll on which a second flexible substrate has been wound, means for forming a liquid crystal material layer on the surface of the first substrate, and means for bonding together the first and second substrates  206 , 201 .  
           [0011]    A specific example of the structure of the above-described system is shown in FIG. 1, where a first flexible substrate  206  has been wound on a first roll  119 . A second flexible substrate  201  has been wound on a second roll  101 . A dripping device  135  acts to drip a liquid crystal material onto the surface of the first substrate  206 . A set of rolls,  137  and  138 , is the means for bonding together the first and second substrates  206 , 201 .  
           [0012]    The flexible substrates can be made from PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PES (poly-ethylene sulfite), polyimide, or PAR (polyarylate).  
           [0013]    A method of fabricating liquid crystal cells according to the present invention consists of preparing a first flexible substrate wound on a first roll, preparing a second flexible substrate wound on a second roll, and squeezing a liquid crystal material between the first and second substrates to form an elongated liquid crystal cell.  
           [0014]    Another method of fabricating liquid crystal cells according to the present invention consists of winding a flexible substrate on a roll, printing an orientation film on the substrate, orienting molecules of the orientation film, spraying spacers on the orientation film, and printing a sealing material. These manufacturing steps are effected successively.  
           [0015]    A specific example of the above-described method is illustrated in FIG. 1. An orientation film  209  is formed on the flexible substrate  206  by rolls  127  and  128 , the substrate  206  being wound on the roll  119 . Spacers  211  are sprayed. A sealing material (not shown) is printed.  
           [0016]    Other objects and features of the invention will appear in the course of the description thereof, which follows. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0017]    [0017]FIG. 1 is a schematic diagram of a system for fabricating liquid-crystal electrooptical devices according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    The present example is a production system capable of producing liquid-crystal electrooptical devices in succession, each electrooptical device using flexible resinous substrates. This fabrication system is schematically shown in FIG. 1 and intended to produce the flexible resinous substrates wound on rolls  101  and  119 , for constructing each liquid-crystal electrooptical device.  
         [0019]    First, a manufacturing step regarding resinous substrates wound around the roll  119  is described. In this example, resinous substrate coiled around the roll  119  consist of film of PET (polyethylene terephthalate). A three-colored (R, G, and B) filter  203  is printed on the surface of the RET film  200  drawn out of the roll  112 . This PET film acts as a base in forming the color filter  203 . The color filter  203  is formed by means of three sets of rolls  113 . Where the manufactured liquid crystal display is a monochrome display, these three sets of rolls are not necessary.  
         [0020]    After forming the color filter  203 , a protective film  205  wound on a roll  115  is formed so as to cover the color filter  203  previously formed. A self-adhesive film  204  wound on a roll  116  is stuck on the rear side of the base, i.e., on the opposite side of the surface on which the colored filter is formed. This series of manufacturing steps is performed, using a pair of pressure rolls,  117  and  118 .  
         [0021]    Then, another PET film  206  which is wound on the roll  119  and forms a base is stuck via the self-adhesive film  204  by means of a set of pressure rolls,  120  and  121 . Subsequently, the protective film  205  is peeled off by a roll  123  and wound on a roll  122 .  
         [0022]    Thereafter, an overcoat film  207  is printed by a set of rolls,  123  and  124 , to flatten the irregularities created by the formation of the color filter  203 . This overcoat film  207  is made from a resinous material transparent to light.  
         [0023]    A required electrode pattern  208  is printed, using a set of rolls,  125  and  126 . The electrode pattern  208  is made from a conductive ink.  
         [0024]    Then, an orientation film  209  is printed by the use of a set of rolls,  127  and  128 . The orientation film  209  is passed through a heating furnace  129  to bake it. As a result, a solidified orientation film  210  is obtained.  
         [0025]    The orientation film  210  is passed between rolls  130  and  131  to rub the surfaces of the orientation film  210 . In this way, the molecules of the film are oriented. Then, spacers are sprayed from a spacer dispenser  132  to place the spacers  211 -on the oriented film  210 .  
         [0026]    Thereafter, a sealing material (not shown) is printed to bond together opposite substrates and to prevent the liquid crystal material from leaking from the spacing between the substrates.  
         [0027]    Subsequently, the liquid crystal material is dripped, using the liquid crystal material-dripping device  135 , to form a liquid crystal material layer  212 . In this manner, one substrate is completed. The manufacturing steps described thus far are successively carried out by rotating the various rolls.  
         [0028]    The other substrate is manufactured in the manner described below. A desired electrode pattern  213  is formed on the PET film  201  drawn out of the roll  101  by a pair of rolls  102  and  103 . Then, an orientation film  214  is printed through the use of a pair of rolls  104  and  105 . The film is baked by a heating furnace  108 , so that a solidified orientation film  215  is formed. Thereafter, the substrate is passed between a pair of rolls  109  and  110  and guided to the rolls  137  and  138  to form a cell.  
         [0029]    The liquid crystal cell is formed on the PET film pair by the steps described thus far. This PET film pair is passed between a pair of rolls  137  and  138  to bond together the films, using a sealing material.  
         [0030]    Then, heating is done within a heating furnace  139  to cure the sealing material, thus completing bonding of the substrates. The resulting substrate assembly is cut into desired size with a cutter  150 . In this way, a liquid crystal cell is completed.  
         [0031]    The manufacturing steps described thus far are performed in succession by rotating the various rolls. By cutting the substrate assembly with the cutter  150 , liquid crystal cells are successively fabricated.  
         [0032]    In the present example, passive liquid crystal cells are manufactured. It is also possible to fabricate active liquid crystal cells by fabricating nonlinear devices and TFTs simultaneously by printing techniques.  
         [0033]    In the present example, liquid crystal cells are formed on PET films which are industrially often used like magnetic tape. Besides PET, PEN (polyethylene naphthalate), PES (polyethylene sulfite), polyimide, and PAR (polyarylate) can be used.  
         [0034]    Where PET or PES film is used, birefringence may take place, in which case the image displayed on the device may be adversely affected. On the other hand, neither PES film nor PAR film induces birefringence and they satisfy the optical characteristics which every display device must meet.  
         [0035]    In the present invention, when flexible liquid crystal cells are manufactured, flexible substrates wound on rolls are used. Consequently, liquid crystal cells can be manufactured in succession.