Patent Publication Number: US-2003230468-A1

Title: Conveyor for liquid crystal panel

Description:
[0001] This application claims the benefit of the Korean Application No. P2002-033500 filed on Jun. 15, 2002, which is hereby incorporated by reference for all purposes as if fully set forth herein.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to a conveyor system for conveying liquid crystal panels, more particularly the present invention relates to a conveyor system capable of automatically adjusting a width between supporting ends of rotating rollers.  
       [0004] 2. Discussion of the Related Art  
       [0005] Generally, liquid crystal displays are devices that display images using liquid crystal cells arranged in a matrix pattern. Data signals, representative of image information, may be used to selectively control the light transmittance of each of the liquid crystal cells.  
       [0006] Liquid crystal displays are fabricated by forming a plurality of thin film transistor (TFT) substrates within a first substrate, forming a plurality of color filter substrates within a second substrate, bonding the first and second substrates to each other, and cutting the bonded first and second substrates into a plurality of liquid crystal panels, wherein each liquid crystal panel includes a TFT substrate bonded to a color filter substrate.  
       [0007] The TFT substrates are fabricated according to a process including deposition, photolithography, and etching to form an array of TFTs. The color filter substrates are fabricated according to a color filter fabricating process. The liquid crystal panels are fabricated according to a liquid crystal cell fabricating process.  
       [0008] Each of the TFT substrates include a plurality of gate lines arranged at fixed intervals along a first direction, and a plurality of data lines arranged at fixed intervals along a second direction, perpendicular to the first direction. Pixel areas, located at crossings of the gate and data lines, include a plurality of thin film transistors (TFTs) and pixel electrodes.  
       [0009] In order to prevent leakage of liquid outside the pixel areas of each of the color filter substrates, the color filter fabricating process includes a step of forming a black matrix layer in regions of the color filter substrate that do not correspond to the pixel areas. The color filter fabricating process further includes steps of forming red, green, and blue color filters, and an ITO (indium tin oxide) common electrode layer.  
       [0010] After the arrays of TFTs are formed, and after the color filter fabrication process is executed, the liquid crystal cell fabricating process is performed on the first and second substrates as follows.  
       [0011] Referring to FIG. 1, after an alignment material has been coated on the TFT and color substrate portions of the first and second substrates, respectively, an alignment process (IS) is performed on the coated alignment material to uniformly align liquid crystal material to be injected into the cell gap. The alignment process (IS) is performed by pre-cleaning each of the first and second substrates, printing the alignment layer on the TFT and color substrate portions of the first and second substrates, respectively, plasticizing the alignment layers, inspecting the alignment layers, and rubbing the alignment layers.  
       [0012] After the alignment process IS is completed, a gap formation process is then performed. During the gap formation process, the first and second substrates are cleaned ( 2 S), spacers are dispensed on the first substrate so as to ensure uniformity of the cell gap ( 3 S), sealant is dispensed on each color filter substrate within the second substrate and a liquid crystal injection inlet is formed at an edge portion of each liquid crystal panel ( 4 S), and the first and second substrates are pressed and bonded together ( 5 S).  
       [0013] The bonded first and second substrates are then cut and processed into a plurality of liquid crystal panel ( 6 S).  
       [0014] Subsequently, liquid crystal material is injected through the liquid crystal injection inlet into the cell gap of each of the liquid crystal panels and the liquid crystal injection inlet is then sealed ( 7 S).  
       [0015] Lastly, cut surfaces of the first and second substrates are then polished, and an exterior and electrical failure inspection is performed ( 8 S).  
       [0016] The liquid crystal injection process will now be described in greater detail.  
       [0017] In injecting liquid crystal material, liquid crystal material is provided within a liquid crystal container, the liquid crystal container is loaded into a vacuum chamber, and pressure in the vacuum chamber is reduced, thereby creating a vacuum within the vacuum chamber so that any moisture adhered to the inner surface of the liquid crystal container or any air bubbles in the liquid crystal material are removed.  
       [0018] While maintaining the vacuum within the vacuum chamber, the liquid crystal injection inlet of an empty LC cell contacts, or is dipped into, the liquid crystal material in the liquid crystal container. The pressure of the vacuum chamber is then increased and, due to the pressure difference between the interior of the empty LC cell and the interior of the vacuum chamber, liquid crystal material is injected through the liquid crystal injection inlet into the cell gap.  
       [0019]FIG. 2 illustrates the TFT and color filter substrates  100  and  200 , respectively. A plurality of gate lines  50  arranged at fixed intervals along a first direction and a plurality of data lines  60  arranged at fixed intervals along a second direction, perpendicular to the first direction, are formed on the TFT substrate. A plurality of thin film transistors (TFTs) and pixel electrodes are formed in pixel areas  70  defined by the crossing of the gate and data lines  50  and  60 , respectively. A plurality of pixel areas  70  generally define an image display area  80 . While not shown in FIG. 2, each of the TFTs includes gate and source electrodes formed in respective pixel areas  70  that are connected to corresponding gate and data lines  50  and  60 , respectively. Drain electrodes of the TFTs are connected to corresponding to pixel electrodes arranged in corresponding pixel areas  70 .  
       [0020] A plurality of the gate and data lines  50  and  60 , respectively, are connected to gate pads and data pads  90  and  110 , respectively, arranged at a periphery of the array substrate  100 .  
       [0021] A shorting bar is provided to facilitate the inspection of the liquid crystal panels to determine if any defective characteristics were imparted to the panel during any of the aforementioned fabricating processes. The shorting bar is removed after fabrication of the liquid crystal device is complete. The shorting bar includes first to fourth sub-shorting bars  120  to  123  that are used to separately inspect odd and even data and gate lines  50  and  60 , respectively. The first to fourth sub-shorting bars  120  to  123  extend toward ends of the TFT substrate such that they may couple to external terminals (not shown).  
       [0022] The color filter substrate  200  is slightly smaller than the TFT substrate. A black matrix layer  210  is formed on the color filter substrate  200  for preventing leakage of light in regions outside pixel areas  70 . A color filter layer (not shown), common electrode (not shown), column-type spacers (not shown) may also be formed on color filter substrates used in large liquid crystal displays.  
       [0023] The column-type spacers arranged in correspondence with gate and data lines of the TFT substrate. A black matrix rim  220  is provided to prevent leakage of light outside the display area  80 .  
       [0024] The TFT and color filter substrates  100  and  200 , respectively, are bonded to each other using a sealant (not shown) made of photo-hardening or thermo-hardening resin.  
       [0025] The substrates (e.g., bonded TFT and color filter substrates, bonded first and second substrates, unbonded first and second substrates, etc.) are transported between various fabricating processes (e.g., grinding processes, cleaning processes, etc.) via a variable width conveyor system.  
       [0026] Conveyors systems, such as those illustrated in FIG. 3, include a plurality of rotating rollers  300  having supporting ends  300 A spaced apart from each other by a predetermined width. The rotating rollers  300  rotate to convey substrates  100 A from one location to another. Edges of the substrates  100 A are arranged on and contact supporting ends  300 A of the rotating roller  300 . The substrates  100 A are transported according to the electrical characteristics of the panel area of liquid crystal panels. Static electricity may be generated due to friction caused by contact between the liquid crystal panels and the supporting ends  300 A. Accordingly, supporting ends  300 A are arranged to contact edges of the liquid crystal panels that include the gate pads or data pads  90  or  110 , respectively, and the black matrix rim  220  to thereby minimize the risk of generating static electricity.  
       [0027] Conveyor systems such as those illustrated in FIG. 3, however, are disadvantageous for the following reasons.  
       [0028] During the liquid crystal cell fabricating process, the width between the supporting ends  300 A must be optimally adjusted to efficiently transport liquid crystal panels. To adjust the width between the supporting ends  300 A, a screw (not shown) is manually turned. In manually turning the screw, the efficiency of the conveyor system is reduced.  
       [0029] Moreover, upon manually turning the screw, the width may be incorrectly adjusted and one of the supporting ends  300 A may contact the unit liquid crystal panels in a manner capable of generating static electricity. Static electricity damages the alignment layer and degrades the injected liquid crystal material.  
       SUMMARY OF THE INVENTION  
       [0030] Accordingly, the present invention is directed to a conveyor system for liquid crystal panels that substantially obviates one or more problems due to limitations and disadvantages of the related art.  
       [0031] An advantage of the present invention provides a conveyor for liquid crystal panels capable of automatically adjusting a width between supporting ends of rotating rollers.  
       [0032] Additional advantages and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. These and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
       [0033] To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a conveyor system for a liquid crystal panel includes rotating rollers having a pair of supporting ends arranged along a direction and separated by a predetermined width and least one motor for receiving data related to the liquid crystal panel and for automatically adjusting the predetermined width.  
       [0034] In one aspect of the present invention, the predetermined width may be adjusted such that edge areas of the liquid crystal panel are continuously arranged on the supporting ends of the rotating rollers.  
       [0035] In another aspect of the present invention, the edge areas of the liquid crystal panel may include pads and black matrix areas.  
       [0036] In yet another aspect of the present invention, the motor may include a servo-motor.  
       [0037] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0038] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention.  
     [0039] In the drawings:  
     [0040]FIG. 1 illustrates a flowchart of a liquid crystal display fabrication method incorporating liquid crystal injection technique;  
     [0041]FIG. 2 illustrates a schematic view of a liquid crystal panel;  
     [0042]FIG. 3 illustrates a perspective view of a conveyor system for conveying a liquid crystal panel; and  
     [0043]FIG. 4 illustrates a front view of a conveyor system for conveying a liquid crystal panel according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS  
     [0044] Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
     [0045]FIG. 4 illustrates a front view of a conveyor of a conveyor system for conveying a liquid crystal panel, according to the present invention.  
     [0046] Referring to FIG. 4, a a liquid crystal panel  500 , including TFT and color filter substrates bonded to each other, may be arranged on a rotating roller  700  of a conveyor system.  
     [0047] In one aspect of the present invention, the liquid crystal panel may prepared by injecting liquid crystal material between first and second substrate including TFT and color filter substrates, respectively, and cutting the injected first and second substrates (e.g., using a cutting wheel).  
     [0048] In one aspect of the present invention, the cutting wheel may comprise a material having a hardness higher than that of glass (e.g., diamond) and include blades may formed along a periphery of front and rear faces.  
     [0049] The cutting wheel may be closely held to the bonded substrates using a uniform pressure. Upon rotating, the cutting wheel forms a groove in the bonded substrates to predetermined depth. After the groove has been formed, a crack may be propagated downward by impacting the bonded substrates. Accordingly, a plurality of liquid crystal panels  500  may thereby be formed from the bonded substrates.  
     [0050] Referring to FIG. 4, the liquid crystal panel  500  may be transported using a conveyor system that includes at least one rotating roller  700 . Accordingly, the rotating roller may be used to convey the liquid crystal panel  500  to a location where an inspection may be performed to evaluate the presence of burrs, or other imperfections, on sides of the liquid crystal panel  500  (e.g., the side including the data pad, the side including gate pad, or any other sides).  
     [0051] In one aspect of the present invention, the rotating roller  700  may include a plurality of supporting ends  710  arranged along one direction and separated by a width, d, to transport the liquid crystal panel  500 . The width, d, may be adjusted in accordance with requirements of the liquid crystal panel  500  such that edges of the liquid crystal panel  500  continuously contact the supporting ends  710 .  
     [0052] Accordingly, adjustment of the width, d, may be required and automatically achieved using at least one servomotor  800  arranged at a side of the rotating roller  700 . In one aspect of the present invention, the servo-motor  800  may receive data related to the liquid crystal panel and logically and numerically determine the orientation of the supporting ends  710 .  
     [0053] In one aspect of the present invention, the servomotor  800  may automatically adjust the position, direction, orientation, and the like, of the each of the supporting ends  710  in proportion to a random variance of an input target value. The servo system may include a high-precision servo-mechanism such as a numerical controller of an operation machine, a data floater of a digital calculator output, and the like.  
     [0054] In one aspect of the present invention, the servomotor  800  may be coupled to the rotating roller  700  to improve the operational productivity of the rotating roller  700  and thus conveyor system. Accordingly, the servo-motor may reduce time required for retooling, maintaining a continuous conveyance of liquid crystal panels, and simplify various fabricating processes (e.g., grinding, cleaning cut sides of panels, etc.) that are involved in conveyance of the liquid crystal panel.  
     [0055] According to the principles of the present invention, the rotating roller  700  facilitating the conveyance of liquid crystal panels is advantageous for the following reasons.  
     [0056] The present invention may include a servo-motor arranged at a side of the conveyor for numerically and logically calculating the dimensions of liquid crystal panels, thereby enabling the automatic adjustment of the width between supporting ends or rotating rollers. By automatically adjusting the width of the supporting ends, the supporting ends  710  may be provided to continuously contact edge portions of the liquid crystal panels. As the edge portions include gate pad, data pad, and black matrix structures, the risk of generating static electricity in the liquid crystal panel, upon conveyance of the liquid crystal, may be minimized.  
     [0057] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.