Patent Publication Number: US-2006008744-A1

Title: Device and method for curing sealant of liquid crystal display panel

Description:
FIELD OF THE INVENTION  
      The present invention generally relates to a sealant curing device used in the manufacture of LCD (liquid crystal display) panels, and a related method for curing a sealant.  
     GENERAL BACKGROUND  
      An LCD panel generally comprises two glass substrates, a peripheral sealant, and a multiplicity of liquid crystal molecules. The sealant is used for adhering the glass substrates together and thus forming a space therebetween. The liquid crystal molecules are filled in the space.  
      As shown in  FIG. 4 , a conventional liquid crystal display panel  1  includes a first substrate  10 , a sealant  70 , liquid crystal  50 , and a second substrate  20 . A plurality of photoresists  40  and a black matrix  30  are arranged on an inner surface of the first substrate  10 .  
      During a processing for fabricating the liquid crystal display panel  1 , the sealant  70  is coated on the second substrate  20 , the liquid crystal  50  is dropped onto the second substrate  20 , and the first and second substrates  10 ,  20  are pressed together. Then a process of curing the sealant  70  is performed, to secure the first and second substrates  10 ,  20  to each other.  
      Referring to  FIG. 5 , the liquid crystal display panel  1  is arranged on a worktable  80 . Ultraviolet light of an ultraviolet light source is applied to irradiate the sealant  70  so as to cure the sealant  70 . However, a region A of the sealant  70  is blocked by the black matrix  30 . Thus, the sealant  70  cannot be completely cured. The liquid crystal  50  may be contaminated by the uncured sealant  70 , thereby adversely affecting the display quality of the liquid crystal display panel  1 .  
      Further, even if the ultraviolet light is applied incident from an underside of the second substrate  20 , circuits arranged on the second substrate  20  may also block the ultraviolet light from reaching portions of the sealant  70 .  
      What is needed, therefore, is a device and a method for curing sealant that overcomes the above-described deficiencies.  
     SUMMARY  
      In a preferred embodiment, a sealant curing device, for a liquid crystal display panel having a black matrix, sealant, and liquid crystal. The sealant curing device includes a worktable having a reflecting surface which reflects ultraviolet light to the sealant so as to cure it, and a plurality of supporting members disposed on the worktable to support the liquid crystal display panel. The ultraviolet light is reflected by the reflecting surface to irradiate portions of the sealant shielded by the black matrix.  
      In another preferred embodiment, a method for curing sealant includes the steps of: providing a worktable having a reflector and a plurality of supporting members; arranging a liquid crystal display panel with a black matrix on the supporting members; curing the sealant by directly irradiating ultraviolet to the sealant which is not overlapped by the black matrix; and completely curing the sealant by reflecting ultraviolet at the reflector to irradiate to the sealant that is overlapped by the black matrix.  
      The ultraviolet light may be reflected by the reflector to irradiate the sealant covered by the black matrix. Heights of the supporting members can be adjusted to change the angles of incidence of the ultraviolet light, thereby helping ensure that the sealant is completely cured. A side reflector is also provided. In this way, the entire sealant can be completely cured, and the liquid crystal cannot be contaminated by uncured sealant. This can improve the display quality and efficiency of manufacture.  
      Other advantages and novel features of preferred embodiments will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a simplified, schematic, side cross-sectional view of part of a sealant curing device according to a first embodiment of the present invention, together with one substrate of a liquid crystal display panel mounted on the sealant curing device;  
       FIG. 2  is similar to  FIG. 1 , but showing the entire sealant curing device according to the first embodiment together with the entire liquid crystal display panel mounted on the sealant curing device, and showing one stage in a method for curing a sealant of the liquid crystal display panel according to an exemplary embodiment of the present invention;  
       FIG. 3  is similar to  FIG. 2 , but showing a different liquid crystal display panel having a different configuration of sealant;  
       FIG. 4  is a simplified, schematic, side cross-sectional view of a conventional liquid crystal display panel; and  
       FIG. 5  is a schematic, side cross-sectional view showing one stage in a method for curing a sealant of the liquid crystal display panel of  FIG. 4  using a conventional sealant curing device. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       FIG. 1  shows a cross-sectional view of part of a sealant curing device  9  according to a preferred embodiment of the present invention, together with one substrate  200  (of a liquid crystal display panel  2 ) mounted on the sealant curing device  9 .  FIG. 2  is similar to  FIG. 1 , but shows the entire sealant curing device  9  together with the entire liquid crystal display panel  2  mounted on the sealant curing device  9 . The sealant curing device  9  includes a worktable  800 , a reflecting surface  801  formed on the worktable  800 , and a plurality of supporting members  600  arranged on the worktable  800 . Referring also to  FIG. 2 , the supporting members  600  can cooperatively support the liquid crystal display panel  2 . A height of each supporting member  600  is adjustable. The reflecting surface  801  has a high reflectance.  
      As shown in  FIG. 2 , a preferred method for curing a sealant  700  of the liquid crystal display panel  2  includes the steps of: placing the liquid crystal display panel  2  on the supporting members  600  of the worktable  800 ; and applying ultraviolet light to irradiate the sealant  700  so as to cure the sealant  700 . In the illustrated embodiment, a radiant intensity of the ultraviolet light is preferably in the range from 20000 to 40000 J/m 2 .  
      When directly applying the ultraviolet light to irradiate the sealant  700 , parts of the sealant  700  are irradiated via a color filter  400  of the liquid crystal display panel  2 . However, other parts of the sealant  700  are shielded by a black matrix  300  of the liquid crystal display panel  2 , and such parts of the sealant  700  cannot be completely cured by the ultraviolet light. Accordingly, a reflector  150  is disposed at a side of the worktable  800 . Respective portions of the ultraviolet light are incident on the reflector  150  and on the reflecting surface  801 , and are reflected by the reflector  150  and the reflecting surface  801 . The reflected ultraviolet light is then incident on the sealant  700 , including the parts of the sealant  70  that are shielded by the black matrix  300 . Further, other portions of the ultraviolet light directly irradiate the parts of the sealant  700  that are not shielded by the black matrix  300 . Thus overall, the entire sealant  700  is completely cured.  
      The heights of the supporting members  600  can be adjusted so as to correspondingly adjust incident angles of the ultraviolet light and thereby ensure that the sealant can be completely irradiated and cured. Further, the reflector  150  may be flat or concave. Accordingly, the sealant  700  can be cured completely, and contamination of liquid crystal  500  of the liquid crystal display panel  2  by the sealant  700  can be avoided. This in turn improves the efficiency of mass production of the liquid crystal display panel  2 .  
       FIG. 3  is similar to  FIG. 2 , but showing a different liquid crystal display panel  3  having a different configuration of sealant  710 . The sealant  710  is located on a bottom substrate  210  of the liquid crystal display panel  3 , and does not contact a top substrate of the liquid crystal display panel  3 . Parts of the sealant  710  are shielded by a black matrix  310  of the liquid crystal display panel  3 . The sealant  710  can still be completely cured, with the aid of ultraviolet light reflected by the reflecting surface  801  of the worktable  800  and ultraviolet light reflected by the reflector  150  disposed at a side of the liquid crystal display panel  3 .  
      It is to be understood, however, that even though numerous characteristics and advantages of the embodiments have been set out in the foregoing description, together with details of the functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.