Abstract:
A sealing structure for a field emission display (FED) device and a method of manufacturing the same is provided. The sealing structure includes an upper substrate, a lower substrate, spacers, and a frit, wherein at least one exhaust outlet is formed in the frit. The method of manufacturing the sealing structure of the FED device prepares a lower substrate and an upper substrate, installs a frit having at least one exhaust outlet between the lower substrate and the upper substrate, and heats the lower substrate and the upper substrate while arranging the upper substrate on the lower substrate at a predetermined temperature to melt the frit in order to seal the space between the lower substrate and the upper substrate. Inner gas can be easily exhausted and the inside of the FED is reliably sealed while preventing damages of the spacers.

Description:
CLAIM OF PRIORITY 
   This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application for SEALING STRUCTURE OF A FILED EMISSION DISPLAY DEVICE, AND A MANUFACTURING METHOD OF THE SAME, earlier filed in the Korean Intellectual Property Office on the 23 rd  of February, 2005 and there duly assigned Serial No. 10-2005-0015053. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a field emission display (i.e., “FED”) device, and more particularly, to a sealing structure of a FED device and a method of manufacturing the same. 
   2. Description of the Related Art 
   In general, a field emission display (i.e., a “FED”) device is one of flat panel display devices, and formed of a tip-shaped or wedge-shaped cathode and an anode on which a fluorescent substance is coated. When electrons emitted from a predetermined portion of the cathode collide with the fluorescent substance, the fluorescent substance illuminates to visually display desired patterns, characters, or signs. The FED device can display high resolution and high luminance color patterns while consuming minimum electrical power. 
   Such a FED device forms a micro-tip shaped cathode in order to focus an electric field, forms a gate for inducing the electric field, and forms an anode on which a fluorescent substance is coated. Electrons are emitted from a plurality of micro-tips, and the electrons collide with the fluorescent substance of the anode having a transparent conductive film; thus the fluorescent substance is stimulated and the outermost electrons of the fluorescent substance are excited and transited. Then, the light generated by the excitement and transition is used to visually display desired images. Studies about such a FED device have been performed for a long time. 
   A substrate assembly for a FED device is manufactured during a packaging process, in which an upper substrate and a lower substrate having an anode and a cathode, respectively, are aligned and heated in a firing furnace at a temperature of 400° C. 
   In such a packaging process described above, however, carbon nano-tubes are easily oxidized in high temperature process due to the oxygen remaining in the firing furnace. In fact, during the packaging process, a large number of the carbon nano-tubes are oxidized, and the emission characteristic of carbon nano-tubes seriously deteriorates. In order to solve such problems, oxygen is completely removed from the firing furnace, and the baking process is performed after injecting an inert gas, such as nitrogen, into the firing furnace. 
   SUMMARY OF THE INVENTION 
   The present invention provides a sealing structure of a field emission display (FED) device for preventing the deterioration of an emission characteristic of carbon nanotubes, and reducing a process time and a number of steps in a high temperature process by improving the shape and manufacturing method of a frit which seals the FED device, and a method of manufacturing the same. 
   According to an aspect of the present invention, there is provided a sealing structure of an FED device, constructed with an upper substrate, a lower substrate separated from the upper substrate by a predetermined distance, spacers for maintaining the distance between the upper substrate and the lower substrate, and a frit for sealing the space between the upper substrate and the lower substrate, wherein at least one exhaust outlet is formed in the frit. 
   The exhaust outlet may be formed as a groove in the frit. The exhaust outlet may be formed as a hole in the frit. The frit may have connections for connecting the frit to other frits. The connections may be formed at both ends of the frit. 
   The frit may further include getter combining grooves for installing getters that absorb inner gas produced in the space between the upper substrate and the lower substrate. 
   The frit may be manufactured by forming at least two separate members and combining the separate members. The separate members may be formed by any one of molding and injection molding. 
   The frit may have at least two sub-frits connected to each other. The sub-frits may be connected to each other at a predetermined angle. The sub-frits may be identical. 
   A vacuum exhaust pipe may be formed in any one of the lower substrate and the upper substrate. 
   According to another aspect of the present invention, there is provided a method of manufacturing a sealing structure of an FED device, by preparing a lower substrate and an upper substrate, installing a frit which has at least one exhaust outlet, between the lower substrate and the upper substrate, and heating the lower substrate and the upper substrate while arranging the upper substrate on the lower substrate at a predetermined temperature to melt the frit in order to seal the space between the lower substrate and the upper substrate. 
   The method may install spacers separated from the frit by a predetermined distance before the heating of the lower substrate and the upper substrate. 
   According to still another aspect of the present invention, there is provided a method of manufacturing a sealing structure of an FED device by arranging a lower substrate and an upper substrate, forming spacers between the lower substrate and the upper substrate, forming a frit, which is longer than the spacer by a predetermined length, separated from the spacer by a predetermined distance, and heating the lower substrate and the upper substrate while arranging the upper substrate on the lower substrate to reduce the height of the frit in order for the spacers to contact the lower substrate and the upper substrate. 
   The frit may include at least one exhaust hole. According to the sealing structure of the FED device, the inner gas can be easily exhausted because the frit includes exhaust grooves or exhaust holes. 
   In addition, the sealing structure of the FED device manufactured according to the principles of the present invention can reliably seal the inside of the FED device while preventing the damage of the spacers. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
       FIG. 1  shows a photo of carbon nano-tubes before firing in a packaging process; 
       FIG. 2  shows a photo of carbon nano-tubes of  FIG. 1  after firing in the packaging process; 
       FIG. 3  is a perspective view of a sealing structure of a field emission display (FED) device; 
       FIG. 4  is a perspective view of a frit for a sealing structure of a FED device constructed as a first embodiment of the present invention; 
       FIG. 5  is a perspective view of a frit for a sealing structure of a FED device constructed as a second embodiment of the present invention; 
       FIG. 6  is a perspective view illustrating an example of combined frits of  FIG. 5 ; 
       FIG. 7  is a perspective view illustrating another example of combined frits of  FIG. 5 ; 
       FIG. 8  is a perspective view of a frit for a sealing structure of a FED device constructed as a third embodiment of the present invention; 
       FIG. 9  is a perspective view of a frit for a sealing structure of a FED device constructed as a fourth embodiment of the present invention; 
       FIG. 10  is a perspective view of a frit for a sealing structure of a FED device constructed as a fifth embodiment of the present invention; 
       FIG. 11  is a perspective view illustrating members of the frit shown in  FIG. 8  before assembly; 
       FIG. 12  is a perspective view illustrating members of the frit shown in  FIG. 8  after assembly; 
       FIG. 13  is a perspective view illustrating members of the frit shown in  FIG. 9  before assembly; 
       FIG. 14  is a perspective view illustrating members of the frit shown in  FIG. 9  after assembly; and 
       FIGS. 15A through 15D  are cross-sectional views illustrating a method of manufacturing a sealing structure of an FED device performed according to the principles of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As described above, carbon nano-tubes are easily oxidized during firing in the packaging process. Such a problem can be observed in a texture of carbon nano-tubes as shown in  FIGS. 1 and 2 .  FIG. 1  shows a photo of carbon nano-tubes before firing in the packaging process, and  FIG. 2  shows a photo of carbon nano-tubes of  FIG. 1  after firing in the packaging process. Referring to  FIGS. 1 and 2 , the number of carbon nano-tubes is significantly reduced after the firing in the packaging process. In the experiment counting carbon nano-tubes shown in  FIGS. 1 and 2 , it is found that the number of carbon nano-tubes is reduced by 87% after firing in the packaging process. 
   The sealing structures of field emission display devices and methods of manufacturing the same according to embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals refer to the same or comparable components. 
     FIG. 3  is a perspective view illustrating a sealing structure of a field emission display (FED) device according to the present invention. 
   Referring to  FIG. 3 , the sealing structure  10  of the FED device includes a lower substrate  20 , an upper substrate  30 , and a frit  40  arranged between the lower substrate  20  and the upper substrate  30 . 
   Each of the lower substrate  20  and the upper substrate  30  has an anode and a cathode. In addition, a plurality of carbon nano-tubes for emitting electrons are formed on the lower substrate  20 . 
   On the other hand, a vacuum exhaust pipe (not shown) penetrates the upper substrate  30  or the lower substrate  20 . In the sealing structure  10  of the FED device according to the present invention, the number of vacuum exhaust pipes can be reduced, since separate exhaust outlets for exhausting inner gas are formed on the frit  40 . 
     FIG. 4  is a perspective view of a frit for a sealing structure of a FED device according to a first embodiment of the present invention. Referring to  FIG. 4 , the frit  40 A includes a base  41 , convex units  42  formed on the base  41  with predetermined intervals, and concave units  43  formed between the convex units  42 . In this case, the concave units  43  operate as exhaust grooves to exhaust inner gas from the FED device. Multiple concave units  43  may be formed with predetermined intervals in order to increase an amount of exhaust through the frit  40 A. 
   When an inert gas such as nitrogen is injected into the FED device in a firing furnace as a substitute for the inner gas in the FED device, the exhausting speed and the amount of inner gas exhausted from the FED device are improved, because the frit  40 A includes the convex units  42  and the concave units  43 . Therefore, the inner gas in the FED device can be easily exhausted from the FED device. 
     FIG. 5  is a perspective view of a frit for a sealing structure of a FED device according to a second embodiment of the present invention. Referring to  FIG. 5 , the frit  40 B includes a base  41 , convex units  42  and concave units  43  formed on the base  41 , and connection units  44  formed at both ends of the base  41 . Since the frit  40 B includes the connection units  44 , the frit  40 B can be easily connected with another frit  40 B. 
     FIG. 6  is a perspective view illustrating an example of a combination of the frits  40 B from  FIG. 5  to complete a frit  40 . Referring to  FIG. 6 , the frits  40 B are combined by having a connection unit  44  of a frit  40 B engage with connection unit  44  of another frit  40 B. In this case, the frits  40 B can be combined while forming a predetermined angle therebetween, for example, a right angle. 
   The angle between the frits  40 B can be easily controlled. Accordingly, the combination angle of the frits  40 B can be controlled based on the sealing structure of the FED device. Therefore, a frit  40  having a required structure can be manufactured by combining sub-frits  40 B. 
     FIG. 7  is a perspective view of another example of a combination of the frits  40 B of  FIG. 5  to complete a frit  40 . Referring to  FIG. 7 , frits  40 B can be connected into a shape of a straight line by having a frit  40 B engage with another frit  40 B through the connection units  44  of the frits  40 B. Accordingly, a length of a frit  40  increases by connecting multiple frits  40 B through the connection units  44 . Since the length of the frit  40  can be controlled this way, a frit  40  with the predetermined length required by the sealing structure of the FED device can be easily realized. 
   Regarding  FIGS. 6 and 7 , the frit  40  can be made with various types of frits  40 B or with identical type of frits  40 B to provide more flexibility in manufacturing of a sealing structure of a FED device. For example, frits  40 B with different lengths could be combined to make a frit  40  with a predetermined length required by the sealing structure of the FED device. Each frit  40 B included in the frit  40  may be produced by a method of molding or injection molding to have a predetermined shape. 
     FIG. 8  is a perspective view of a frit for a sealing structure of an FED device according to a third embodiment of the present invention. Referring to  FIG. 8 , the frit  40 C includes a body unit  45  and exhaust holes  46  formed in the body unit  45 . A plurality of exhaust holes  46  may be formed while having predetermined intervals in order to increase an amount of exhaust through the frit  40 C. 
   Since the exhaust holes  46  are formed in the body unit  45  of the frit  40 C, the frit  40 C can exhaust inner gas of the FED device, even without directly contacting another member, for example, an upper substrate  30  or a lower substrate  20 . Accordingly, the arrangement of the frit  40 C is not limited, and can be optimally selected to realize a required sealing structure of the FED device. 
     FIG. 9  is a perspective view of a frit for a sealing structure of an FED device according to a fourth embodiment of the present invention. Referring to  FIG. 9 , the frit  40 D includes a body unit  45 , exhaust holes  46  formed in the body unit  45 , and connection units  47  formed at both ends of the body unit  45 . The exhaust holes  46  operate as passages for exhausting the inner gas of the FED device. A plurality of exhaust holes  46  may be formed at predetermined intervals to increase an amount of the exhausted gas. In this case, the arrangement of the frits  40 D can be freely selected to realize a required sealing structure of the FED device, and a length of a complete frit can be easily controlled by connecting multiple frits  40 D through the connection units  47 . 
     FIG. 10  is a perspective view of a frit for a sealing structure of a FED device according to a fifth embodiment of the present invention. Referring to  FIG. 10 , the frit  40 E includes a body unit  45 , exhaust holes  46  formed in the body unit  45 , connection units  47  formed at both ends of the body unit  45 , and getter combination grooves  48 . 
   In this case, getters are installed in the getter combination grooves  48  to absorb the inner gas of the FED device during the manufacture of the sealing structure. Since the inner gas of the FED device is absorbed through the getters that are installed in the getter combining grooves  48 , the inner gas can be easily exhausted. 
     FIG. 11  is a perspective view illustrating members of the frit  40 C shown in  FIG. 8  before assembly, and  FIG. 12  is a perspective view illustrating members of the frit  40 C shown in  FIG. 8  after the assembly. Referring to  FIGS. 11 and 12 , the frit  40 C can be manufactured by combining an upper member  50   a  and a lower member  50   b , both of which have convex units  51  and concave units  52 . The convex units  51  and the concave units  52  of the upper member  50   a  and the lower member  50   b  are first manufactured, and then the upper member  50   a  and the lower member  50   b  are assembled. Therefore, the exhaust holes  46  can be easily formed. 
     FIG. 13  is a perspective view illustrating members of the frit  40 D shown in  FIG. 9  before assembly, and  FIG. 14  is a perspective view illustrating members of the frit  40 D shown in  FIG. 9  after the assembly. Referring to  FIGS. 13 and 14 , the frit  40 D can be manufactured by combining a lower member  50  having convex units  51  and concave units  52  and an upper member  53  having a flat surface that is being attached to the lower member  50 . Since the convex units  51  and the concave units  52  are formed on the lower member  50  only, the process for forming the exhaust holes  46  is simplified, and the frit  40 D can be more easily manufactured. 
     FIGS. 15A through 15D  are cross-sectional views illustrating a method of manufacturing a sealing structure of a FED device according to the present invention. Referring to  FIG. 15A , a lower substrate  20  and an upper substrate  30 , which is separated from the lower substrate  20  by a predetermined distance, are prepared. 
   Referring to  FIG. 15B , spacers  60  having a predetermined height are installed on the lower substrate  20 . 
   Referring to  FIG. 15C , frits  40  are installed between the upper substrate  30  and the lower substrate  20 . In this case, frits  40  are installed at the outside of the spacers  60  while maintaining a predetermined distance from the spacers  60 . The height of frits  40  is larger than the height of the spacers  60 . 
   Referring to  FIG. 15D , the lower substrate  20  and the upper substrate  30  are heated in a firing furnace at a predetermined temperature, while the spacers  60  and the frits  40  are arranged between the lower substrate  20  and the upper substrate  30 . As the frits  40  melt, the height of the frits  40  decreases, and thus the heights of the frits  40  and the spacers  60  become almost equal. In addition, the frits  40  adhere to both of the upper substrate  30  and the lower substrate  20  to seal the space between the upper substrate  30  and the lower substrate  20 . 
   When the sealing structure of the FED device is formed according to the present invention, the space between the upper substrate  30  and the lower substrate  20  can be reliably sealed while preventing the damage of the spacers  60 . 
   According to the sealing structure of the FED device according to the present invention, the exhaust grooves or the exhaust holes are formed in the frit that forms the sealing structure, and thus the inner gas can be easily exhausted. 
   While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.