Abstract:
A method for curing sealant of a liquid crystal display and peripheral circuits thereof are described. In the method, a first glass substrate and a second glass substrate are first provided. A black matrix is formed on the first glass substrate and peripheral circuits are formed on the second glass substrate. A sealant, which is a light-cured sealant, adheres the first glass substrate to the second glass substrate. The peripheral circuits further include a hollow area to allow a light radiating from the second glass substrate through the hollow area to the sealant so as to increase light exposure of the sealant. A liquid crystal display sealant curing apparatus is utilized to accomplish the method for curing sealant of a liquid crystal display. The apparatus includes a first light-generating device disposed above the liquid crystal display and/or simultaneously includes a second light-generating device disposed under the liquid crystal display.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a method for curing sealant of a liquid crystal display, and especially, to peripheral circuits of a liquid crystal display to improve the sealant hardening efficiency for the liquid crystal display.  
         BACKGROUND OF THE INVENTION  
         [0002]    Recently, liquid crystal displays (LCD) have been widely applied in electrical products, due to the rapid progress of optical technology and semiconductor technology. Moreover, with the advantages of high image quality, compact size, light weight, low driving voltage, and low power consumption, LCDs have been introduced into portable computers, personal digital assistants, color televisions, and gradually replaced the cathode ray tubes (CRT) used for conventional displays. LCDs are becoming a mainstream display apparatus.  
           [0003]    The main part of an LCD is a liquid crystal (LC) unit composed of two parallel transparent substrates with LC sealed therein. The main trend in LCDs is the thin film transistor (TFT) LCD. The fabrication processes of a TFT-LCD can be divided into four parts: TFT array process, color filter (CF) process, LC cell assembly process, liquid crystal module (LCM) process.  
           [0004]    The TFT array process is used to fabricate a TFT substrate. Each TFT respectively aligns with one pixel electrode. The CF process is used to fabricate a color filter substrate. A color filter layer composed of different color filter sheets is located on the color filter substrate, and a black matrix layer surrounds each color filter sheet. The black matrix layer is utilized to cover the TFT array, metal lines connecting different TFTs and peripheral circuits close to the display area.  
           [0005]    The LC cell assembly process is used to parallel-assemble TFT substrate and CF substrate. Bead spacers are spread between the TFT substrate and the CF substrate to maintain a fixed distance, i.e. a cell gap, therebetween. LC is injected into the cell gap and then the injection opening is sealed.  
           [0006]    Conventional LC injection is a complicated procedure in the TFT-LCD fabrication process. The one drop fill (ODF) process can simplify the fabrication processes. In the ODF process, an ultraviolet-type sealant is used to seal the TFT substrate and the CF substrate. In practical fabrication process, the ultraviolet-type sealant may pollute the liquid crystal if the ultraviolet-type sealant is not cured very well. Therefore, the yield rate and the quality of the liquid crystal display are reduced and a manufacturing bottleneck is generated.  
         SUMMARY OF THE INVENTION  
         [0007]    It is an object of the present invention to provide a method for curing sealant of a liquid crystal display to improve the hardening result of the sealant.  
           [0008]    It is another object of the present invention is to provide a method for curing sealant of a liquid crystal display to prevent sealant pollution of liquid crystal.  
           [0009]    It is yet another object of the present invention is to provide improved peripheral circuits to increase the amount of light exposure on the sealant.  
           [0010]    It is still another object of the present invention is to provide a sealant curing apparatus to enhance the hardening status of the sealant.  
           [0011]    To accomplish the above objectives, the present invention provides a method for curing sealant of a liquid crystal display. The method includes the following steps. A first glass substrate is provided and a black matrix is formed thereon. A second glass substrate is provided and circuits are formed thereon. The circuits further include a first hollow area. The hollow area is a transparent area formed by transparent material and the metal circuits bypass the hollow area. The first glass substrate and the second glass substrate are sealed with a sealant. The sealant is an ultraviolet-type sealant, a laser-type sealant or an infrared-type sealant.  
           [0012]    Subsequently, the sealant is cured by light corresponding to the type of sealant. A first incident light hardens the sealant from the first glass substrate and the second incident light hardens the sealant from the second glass substrate through the first hollow area.  
           [0013]    The first glass substrate is a color filter substrate and the second glass substrate is a thin film transistor substrate. The first hollow area is preferably under a partial sealant, covered by the black matrix, of the sealant. The first hollow further comprises a plurality of interlaced openings and a plurality of interlaced segments.  
           [0014]    The second incident light is constructed by a reflected light of the first incident light such where, for example, the first incident light is reflected by a mirror surface under the second glass substrate to form the second incident light. The circuits can further include a second hollow area to transmit the first incident light through the second hollow area whereupon the first incident light is reflected by the mirror surface. The reflected first incident light becomes the second incident light to expose the sealant by way of the first hollow area so as to harden the sealant.  
           [0015]    The second incident light can be also generated by a light-generating device inside a support bench to expose the sealant to the through the first hollow area. Otherwise, the method for curing sealant of a liquid crystal display according to the present invention can also be achieved to reverse the liquid crystal display after the sealant is exposed to the first incident light. Subsequently, the first incident light transmits through the first hollow area to form the second incident light so as to harden the sealant.  
           [0016]    In another aspect, the present invention provides a liquid crystal display. The liquid crystal display includes a thin film transistor substrate, circuits, a color filter substrate, a black matrix, and a sealant.  
           [0017]    The sealant adheres the thin film transistor substrate to the color filter substrate. The circuits further includes a first hollow area under a part, covered by the black matrix, of the sealant to expose the sealant to a second incident light transmitted through the first hollow area. A first incident light directly hardens the sealant from the color filter substrate above the liquid crystal display.  
           [0018]    In still another aspect, the present invention provides a liquid crystal display sealant curing apparatus. The liquid crystal display sealant curing apparatus includes a first light-generating device above the liquid crystal display to harden the sealant with a first predetermined angle and a second light-generating device under the liquid crystal display to harden the sealant with a second predetermined angle. The liquid crystal display further includes a first hollow area under a part, covered by the black matrix, of the sealant to expose the sealant to a second incident light transmitted through the first hollow area.  
           [0019]    The first predetermined angle and/or the second predetermined angle are about 15 to 60 degrees to a normal direction of the color filter substrate, preferably about 30 to 45 degrees, and optimally about 30 degrees or about 45 degrees.  
           [0020]    The method for curing sealant of a liquid crystal display of the present invention can effectively increase the hardening quality of the sealant and the quality and yield rate of the liquid crystal display can therefore be increased. The present invention also provides the circuit layout and the sealant curing apparatus for hardening the sealant. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    The foregoing aspects and many of the attendant advantages of this invention are more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0022]    [0022]FIG. 1 is a schematic, cross-sectional view of a first preferred embodiment for illustrating the method for curing sealant of a liquid crystal display according to the present invention;  
         [0023]    [0023]FIG. 2 is a schematic, cross-sectional view of a second preferred embodiment for illustrating the method for curing sealant of a liquid crystal display according to the present invention;  
         [0024]    [0024]FIG. 3 is a schematic, cross-sectional view of a third preferred embodiment for illustrating the method for curing sealant of a liquid crystal display according to the present invention; and  
         [0025]    [0025]FIG. 4 is a schematic, cross-sectional view of a fourth preferred embodiment for illustrating the method for curing sealant of a liquid crystal display according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]    The following description is of the best presently contemplated mode of carrying out the present invention. This description is not to be taken in a limiting sense but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be determined by referencing the appended claims.  
         [0027]    [0027]FIG. 1 is a schematic, cross-sectional view of a first preferred embodiment for illustrating the method for curing sealant of a liquid crystal display according to the present invention. A liquid crystal display includes an upper substrate  100 , a lower substrate  110 , a black matrix  170 , circuits  180 , and sealant  140 . The sealant  140  seals a gap  130  between the upper substrate  100  and the lower substrate  110  around the liquid crystal display so that the liquid crystal can be sealed up therein. The gap  130  is about 3-5 microns.  
         [0028]    Generally, the upper substrate  100  is a color filter (CF) substrate and the lower substrate  110  is a thin film transistor (TFT) substrate. The sealant  140  is preferably an ultraviolet-type sealant. However, the upper substrate  100  and the lower substrate  110  can be also in a reverse manufacture direction. The sealant  140  can be any kind sealant material hardened by light, such as, for example, a laser-type sealant, an infrared-type sealant or a visible light-type sealant.  
         [0029]    The method for curing sealant of a liquid crystal display of the liquid crystal display according to the present invention uses a new design for the circuits  180  that provides the sealant with greater light exposure to harden the sealant well, and the light corresponds to the type of the sealant. The present invention further utilizes a curing apparatus with a support bench  120  to harden the sealant  140  with more light exposure.  
         [0030]    The support bench  120  has a mirror surface that provides almost total reflection to reflect most of the energy of incident light  150  to the sealant  140  so as to increase the light exposure of the sealant  140 .  
         [0031]    The support bench  120  for the method for curing sealant of a liquid crystal display according to the present invention can also use a table having therein a light-generating device, such as a lamp, and the liquid crystal display is disposed on the table to harden the sealant with additional light from the light-generating device of the table so as to increase the light exposure of the sealant  140 .  
         [0032]    Furthermore, the support bench  120  can combine the mirror surface and the light-generating device to expose the sealant  140  with additional light reflected and generated by the support bench  120  to increase the light exposure of the sealant  140 .  
         [0033]    The method for curing sealant of a liquid crystal display according to the present invention can also expose the sealant  140  of the liquid crystal display via the upper substrate  100  and then reverse the liquid crystal display to expose the sealant  140  to light via the lower substrate  120 . Therefore, the method for curing sealant of a liquid crystal display is not limited by the support bench  120  of the sealant curing apparatus.  
         [0034]    A detailed description describes the new design of circuits  180  of the liquid crystal display and how to increase light exposure of the sealant  140 . Referring to FIG. 1 again, a partial sealant of the sealant  140  and black matrix  170  are overlapped. Therefore, the partial sealant covered by the black matrix  170  is difficult to cure by the incident light  150  from the upper substrate  100  because the partial sealant covered by the black matrix  170  is not directly exposed to the incident light  150  from the upper substrate  100 . Hence, the partial sealant needs more time to be hardened; otherwise the partial sealant is not hardened well and can pollute the liquid crystal.  
         [0035]    The circuits  180  of the liquid crystal display include a hollow area  160  in the lower substrate  110  and the hollow area  160  is under the sealant. Therefore, the incident light  150  can reach the mirror surface of the support bench  120  and then is reflected by the mirror surface of the support bench  120  so that the partial sealant is exposed to the reflected incident light  150 . The partial sealant can also be exposed to another light generated by a light-generating device, such as a lamp, inside the support bench  120 . However, the partial sealant can also be hardened with the incident light  150  from the upper substrate  100  and then with the incident light  150  from the lower substrate  110  by reversing the liquid crystal display.  
         [0036]    A incident angle of the incident light  150  is about 15 to 60 degrees to the normal direction of the upper substrate  100 , is preferably about 30 to 45 degrees, and is optimally about 30 degrees or about 45 degrees to expose efficiently the sealant  140  to the incident light  150  and the reflected incident light  150 . In particular, the hollow areas  160  and the circuits  180  are designed more conveniently when the incident angle is about 30 degrees or about 45 degrees.  
         [0037]    [0037]FIG. 2 is a schematic, cross-sectional view of a second preferred embodiment for illustrating the method for curing sealant of a liquid crystal display according to the present invention. The liquid crystal display includes an upper substrate  200 , a lower substrate  210 , a black matrix  270 , circuits  280 , and a sealant  240 . The sealant  240  seals a gap  230  between the upper substrate  200  and the lower substrate  210  to isolate the liquid crystal therein. The second preferred embodiment illustrates the circuits  280  on the lower substrate  210  to form a suitable hollow area  260  thereon when the hollow area  260  is smaller than the hollow area  160  of FIG. 1 due to limitations on the layout of circuits  280 . Therefore, the method for curing sealant of a liquid crystal display according to the present invention can still achieve the advantage of increasing the light exposure of the sealant  240  if the hollow area  260  can be suitably disposed under the black matrix  270 ; e.g., the hollow area  260  is directly under a partial sealant, covered by the black matrix  270 , of the sealant  240 .  
         [0038]    [0038]FIG. 3 is a schematic, cross-sectional view of a third preferred embodiment for illustrating the method for curing sealant of a liquid crystal display according to the present invention. The liquid crystal display has an upper substrate  300 , a lower substrate  310 , a black matrix  370 , circuits  380 , and a sealant  340 . The sealant  340  seals a gap  330  between the upper substrate  300  and the lower substrate  310  around the liquid crystal display to isolate the liquid crystal therein. The third preferred embodiment is particular to utilization on the circuits  380  which cannot be formed with an entire hollow area as the hollow area  160  of FIG. 1 or the hollow area  260  of FIG. 2. A hollow area  360  is formed with interlaced openings for transmitting reflected incident light  350  and interlaced segments for laying out the circuits  380 . The reflected incident light  350  can efficiently transmit through the hollow area  360  with interlaced openings and irradiate the sealant  340 . Therefore, the hollow area  360  with interlaced openings can also efficiently increase the light exposure amount on the sealant  340 . The hollow area  360  preferably occupies at least 50% of the area of a partial sealant, covered by the black matrix  370 , of the sealant  340 .  
         [0039]    [0039]FIG. 4 is a schematic, cross-sectional view of a fourth preferred embodiment for illustrating the method for curing sealant of a liquid crystal display according to the present invention. In the fourth preferred embodiment, the liquid crystal display has an upper substrate  400 , a lower substrate  410 , a black matrix  470 , circuits  480 , and a sealant  440 . The sealant  440  seals a gap  430  between the upper substrate  400  and the lower substrate  410  around the liquid crystal display to isolate the liquid crystal therein. The fourth preferred embodiment is particular to utilization on the circuits  480  which have complicated peripheral circuits  480  beyond the sealant  440  around the liquid crystal display. Therefore, the incident light  450  cannot directly transmit through the lower substrate  410  and then reflect to the sealant  440 . Hence, the circuits  480  are preferably designed to have a first hollow area  460  and a second hollow area  490  so that the incident light  450  can transmit through the second hollow area  490 , reach the mirror surface of the support bench  420 , and then reflect to the sealant  440  via the first hollow area  460 . Accordingly, the light exposure amount of the sealant  440  can be also efficiently increased.  
         [0040]    In this preferred embodiment, the sealant  440  can be cured better if the support bench  420  has a light-generating device to generate a second light to cure the sealant  440  and design of the circuits  480  can also be simplified.  
         [0041]    The method for curing sealant of a liquid crystal display of the liquid crystal display according to the present invention can effectively harden the sealant so as to increase quality and yield rate of the liquid crystal display. With some practical experiments, the method for curing sealant of a liquid crystal display according to the present invention can distinctly and effectively improve the quality of the sealant. Therefore, the method for curing sealant of a liquid crystal display according to the present provides an apparent improvement in the manufacture of the liquid crystal display.  
         [0042]    As is understood by a person skilled in the art, the foregoing preferred embodiments of the present invention are illustrative of the present invention rather than limiting of the present invention. It is intended that various modifications and similar arrangements be included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures.