Abstract:
Disclosed is a front substrate of a plasma display panel and fabricating method thereof, by which color temperature, color purity, and contrast of PDP are enhanced. The present invention includes an upper dielectric layer containing a colorant therein. And, the present invention includes the step of forming an upper dielectric layer having a colorant added thereto.

Description:
[0001]     This application is a Continuation Application of U.S. application Ser. No. 10/747,211, filed Dec. 30, 2003. The entire disclosure of the prior application is considered as being part of the disclosure of the accompanying application and is hereby incorporated by reference therein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a plasma display panel (hereinafter abbreviated PDP), and more particularly, to a front substrate of a plasma display panel and fabricating method thereof.  
         [0004]     2. Description of the Background Art  
         [0005]     Lately, a next generation multimedia display device plays a great important role as a visual information transfer means according to development and popularization of information processing systems. Specifically, as CRT (cathode ray tube) is inappropriate for the recent target of providing a large-sized and planarized screen, many efforts are made to study and develop such a flat panel display as LCD (liquid crystal display), FED (field emission display), PDP, ELD (electroluminescent display), etc.  
         [0006]     The PDP is a self-emission display device using plasma gas discharge, and has such various advantages as facilitation of size increment, excellent image quality, and fast video response speed. Moreover, the PDP as well as LCD is used as a wall-hanging display. A discharge cell of a three electrode AC surface discharge type PDP is explained by referring to  FIG. 1  as follows.  
         [0007]      FIG. 1  is a cross-sectional view of a discharge cell of a three electrode AC surface discharge type PDP according to a related art.  
         [0008]     Referring to  FIG. 1 , a discharge cell of the PDP is formed by combining a front substrate  110  and a back substrate  120  and by injecting discharge gas between the front and back substrates  110  and  120 .  
         [0009]     The front substrate  110  consists of an upper glass substrate  100 , a transparent electrode  101  and bus electrode  102  formed on the upper glass substrate  100 , an upper dielectric layer  103  formed on the upper glass substrate  100  including the transparent and bus electrodes  101  and  102  formed thereon, and a protection layer  104  formed on the upper dielectric layer  103 .  
         [0010]     In this case, the upper dielectric layer  103  restricts plasma discharge current and accumulates wall charges on plasma discharge.  
         [0011]     The back substrate  120  consists of a lower glass substrate  109 , an address electrode  108  formed on the lower glass substrate  109 , a lower dielectric layer  107  formed on the lower glass substrate  109  including the address electrode  108 , a barrier rib  106  formed on the lower dielectric layer  107 , and a phosphor  105  formed on the lower dielectric layer  107  and the barrier rib  106 .  
         [0012]     An operational principle of the related art PDP is explained as follows.  
         [0013]     First of all, a discharge sustain voltage is applied to the transparent and bus electrodes  101  and  102  to accumulate electric charges on the upper dielectric layer  103 , and a discharge starting voltage is applied to the address electrode  108  so that the discharge gas injected in the discharge cells of the PDP such as He, Ne, Xe, and the like is separated into electrons and ions to be in a plasma state.  
         [0014]     The phosphor  105  is excited by UV-rays generated from the reunion of the electrons and ions to emit visible rays that represent characters or graphics. In doing so, the PDP uses Ne having a relatively heavy atomic weight as a major component of the discharge gas to prevent thermal deformation, which is caused by collision of accelerated gas ions, of the phosphor or dielectric layer.  
         [0015]     Yet, the discharged Ne gas radiates an orange visible ray (585 nm), thereby degrading color purity and contrast of the PDP.  
         [0016]     To overcome such a problem, a color filter layer or a black stripe layer is added to the upper substrate of the PDP.  
         [0017]      FIG. 2  is a cross-sectional view of a front substrate of PDP according to a related art.  
         [0018]     Referring to  FIG. 2 , a front substrate of PDP according to a related art consists of an upper glass substrate  100 , a transparent electrode  101  and bus electrode  102  formed on the upper glass substrate  100 , an upper dielectric layer  103  formed on the upper glass substrate  100  including the transparent and bus electrodes  101  and  102  formed thereon, a color filter layer  103 A formed on the upper dielectric layer  103 A, and a protection layer  104  formed on the color filter layer  103 A. In this case, the color filter layer  103 A enables to adjust optical transmittance and to prevent surface reflection by an external light.  
         [0019]     The above-constructed PDP according to the related art controls the optical transmittance of a color filter by the color filter layer to enhance the color purity of the PDP and prevents the surface reflection by the external light to enhance the contrast of the PDP.  
         [0020]     However, the related art PDP needs to form the color filter layer on the upper dielectric layer, whereby a fabricating method thereof becomes complicated.  
         [0021]     Moreover, in the related art PDP, the optical transmittance of a blue visible ray B is lower than that of a red or green visible ray R or G, whereby a color temperature of the PDP is about 6,000K. In order to compensate for the low color temperature, an input signal corresponding to R, G, or B is adjusted, barrier ribs are formed asymmetrical, or optical transmittance or dye of the color filter layer is adjusted. Yet, by adopting such a compensation, brightness of the PDP is reduced despite the compensation for the color temperature.  
         [0022]     On the other hand, the color filter layer can be replaced by the black stripe layer. Yet, an aperture plane of the black stripe layer is small, whereby emission efficiency of the PDP is reduced.  
         [0023]     As mentioned in the foregoing explanation, the related art PDP needs to form the color filter layer on the upper dielectric layer, whereby the fabricating method thereof becomes complicated.  
         [0024]     Moreover, the optical transmittance of the blue visible ray B is lower than that of the red or green visible ray R or G, whereby the color temperature of the PDP is low.  
       SUMMARY OF THE INVENTION  
       [0025]     Accordingly, the present invention is directed to a front substrate of a plasma display panel and fabricating method thereof that substantially obviates one or more problems due to limitations and disadvantages of the related art.  
         [0026]     An object of the present invention is to provide a front substrate of a plasma display panel and fabricating method thereof, by which a color temperature of PDP is enhanced by forming an upper dielectric layer containing a colorant amounting to a predetermined ratio for adjusting optical transmittance.  
         [0027]     Another object of the present invention is to provide a front substrate of a plasma display panel and fabricating method thereof, by which a color purity of PDP is enhanced by forming an upper dielectric layer containing a colorant amounting to a predetermined ratio for adjusting optical transmittance.  
         [0028]     Another object of the present invention is to provide a front substrate of a plasma display panel and fabricating method thereof, by which a contrast of PDP is enhanced by forming an upper dielectric layer containing a colorant amounting to a predetermined ratio for adjusting optical transmittance.  
         [0029]     Another object of the present invention is to provide a front substrate of a plasma display panel and fabricating method thereof, by which PDP fabrication is simplified by forming an upper dielectric layer containing a colorant amounting to a predetermined ratio for adjusting optical transmittance.  
         [0030]     Additional advantages, objects, 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. The objectives 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.  
         [0031]     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a front substrate of a plasma display panel according to the present invention includes an upper dielectric layer containing a colorant amounting to a predetermined ratio.  
         [0032]     In another aspect of the present invention, a method of fabricating a front substrate of a plasma display panel including the step of forming an upper dielectric layer to which a colorant is added as much as a predetermined ratio. 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  
       [0033]     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. In the drawings:  
         [0034]      FIG. 1  is a cross-sectional view of a discharge cell of a three electrode AC surface discharge type PDP according to a related art;  
         [0035]      FIG. 2  is a cross-sectional view of a front substrate of PDP according to a related art;  
         [0036]      FIG. 3  is a cross-sectional view of a front substrate of PDP according to the present invention;  
         [0037]      FIG. 4  is a flowchart of a method of fabricating a front substrate of PDP according to the present invention;  
         [0038]      FIG. 5  is a flowchart of forming an upper dielectric layer in  FIG. 3 ; and  
         [0039]      FIG. 6  is a graph of experimental optical transmittance of PDP according to the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0040]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0041]      FIG. 3  is a cross-sectional view of a front substrate of PDP according to the present invention.  
         [0042]     Referring to  FIG. 3 , a front substrate of PDP according to the present invention includes an upper glass substrate  100 , a transparent electrode  101  and bus electrode  102  formed on the upper glass substrate  100 , a colorant-added upper dielectric layer  103 B formed on the upper glass substrate  100  including the transparent and bus electrodes  101  and  102  formed thereon, and a protection layer  104  formed on the upper dielectric layer  103 .  
         [0043]     A method of fabricating the above-constructed front substrate according to the present invention is explained by referring to  FIG. 4  as follows.  
         [0044]      FIG. 4  is a flowchart of a method of fabricating a front substrate of PDP according to the present invention.  
         [0045]     Referring to  FIG. 4 , a method of fabricating a front substrate of PDP according to the present invention includes the steps of forming an upper glass substrate (S 41 ), forming a transparent electrode  101  and bus electrode  102  on the upper glass substrate  100  (S 42 ), forming an upper dielectric layer  103 B, to which a colorant amounting to a predetermined ratio is previously added, on the upper glass substrate  100  including the transparent and bus electrodes  101  and  102  formed thereon (S 43 ), and forming a protection layer  104  on the upper dielectric layer  103  (S 44 ).  
         [0046]     The method of fabricating the front substrate of PDP according to the present invention is explained in detail as follows.  
         [0047]     First of all, after the upper substrate  100  has been prepared (S 41 ), the transparent and bus electrodes  101  and  102  are formed on the upper glass substrate  100  (S 42 ).  
         [0048]     The upper dielectric layer  103 B, to which a colorant amounting to a predetermined ratio is previously added, is then formed on the upper glass substrate  100  including the transparent and bus electrodes  101  and  102  formed thereon. A method of forming the upper dielectric layer of the PDP is explained by referring to  FIG. 5  as follows.  
         [0049]      FIG. 5  is a flowchart of forming the upper dielectric layer in  FIG. 3 .  
         [0050]     Referring to  FIG. 5 , a method of forming the upper dielectric layer of the PDP according to the present invention includes the steps of forming glass powder to which the colorant amounting to the predetermined ratio is added (S 51 ), forming a dielectric paste by mixing the glass powder, a binder, and a solvent with each other (S 52 ), forming a dielectric paste layer by coating a front surface of the upper glass substrate, on which the transparent and bus electrodes are formed, with the dielectric paste (S 53 ), and plasticizing the dielectric paste layer to form the upper dielectric layer (S 54 ).  
         [0051]     The method of forming the upper dielectric layer of the PDP according to the present invention is explained in detail as follows.  
         [0052]     First of all, the colorant for adjusting an optical transmittance is mixed with a parent glass as much as the predetermined ratio to prepare a glass. The prepared glass is then pulverized to form the glass powder having a predetermined particle size each (S 51 ). In this case, the predetermined particle ratio is a weight ratio of the colorant vs. the mother parent. Preferably, the predetermined ratio is equal to or smaller than 5 wt % and the predetermined particle size lies 1˜5 μm.  
         [0053]     The mother glass includes the components shown in one of Table  1  (PbO-B 2 O 3-SiO   2-Al   2 O 3 -BaO based glass), Table 2 (P 2 O 5 -B 2 O 3 -ZnO based glass), and Table 3 (ZnO-B 2 O 3 -RO based glass). In this case, each component unit is wt % (weight %).  
                                                         TABLE 1                                   PbO wt %   B 2 O 3  wt %   SiO 2  + Al 2 O 3  wt %   BaO wt %                                        35.0   35.0   20.0   10.0           40.0   30.5   15.0   14.5           45.0   25.0   10.0   20.0           50.0   27.0   5.0   18.0           60.0   30.0   0.0   10.0                      
 
         [0054]    
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
               
               
                 B 2 O 3  wt % 
                 ZnO wt % 
                 P 2 O 5  wt % 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0.0 
                 46.2 
                 53.8 
               
               
                 3.3 
                 44.7 
                 52.0 
               
               
                 6.8 
                 43.1 
                 50.1 
               
               
                 10.4 
                 41.4 
                 48.2 
               
               
                 14.1 
                 39.7 
                 46.2 
               
               
                 18.0 
                 37.9 
                 44.1 
               
               
                 22.0 
                 36.1 
                 41.9 
               
               
                   
               
             
          
         
       
     
         [0055]    
       
         
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
               
               
                 ZnO wt % 
                 B 2 O 3  wt % 
                 RO wt % 
               
               
                   
               
             
             
               
                 19.8 
                 42.4 
                 37.8 
               
               
                 24.6 
                 37.9 
                 37.5 
               
               
                 29.3 
                 33.4 
                 37.3 
               
               
                 34.0 
                 29.0 
                 37.0 
               
               
                   
               
             
          
         
       
     
         [0056]     RO as a component of the mother glass in Table 3 is selected from the group consisting of BaO, SrO, La 2 O, Bi 2 O 3 , MgO, and ZnO. Preferably, a substance used as the colorant is at least one of CuO, CoO, Nd 2 O 3 , NiO, Cr 2 O 3, Pr   2 O 3 , and Fe 2 O 3 .  
         [0057]     After forming the glass powder including the mother glass and the colorant, the glass powder and ethylcellulose binder are mixed in the solvent dissolving the binder such as α-terpineol, BCA (butyl cabitol acetate), BC (butyl cabitol), and TX (texanol) to form the dielectric paste (S 52 ).  
         [0058]     The dielectric paste is coated on the upper glass substrate having the transparent and bus electrodes formed thereon by screen-printing or thick film coating to form the dielectric paste layer (S 53 ).  
         [0059]     The dielectric paste layer is plasticized for 10˜30 minutes at 550˜600° C. to form the upper dielectric layer of the PDP (S 54 ).  
         [0060]     Thereafter, the protection layer is formed on the upper dielectric layer to complete the front substrate of the PDP. An experimental result of optical transmittance of PDP according to the present invention is explained by referring to  FIG. 6  as follows.  
         [0061]      FIG. 6  is a graph of experimental optical transmittance of PDP according to the present invention.  
         [0062]     Referring to  FIG. 6 , optical transmittance of a blue visible ray (454 nm)B is higher than that of a red or green visible ray (611 nm or 525 nm) R or G. It is expected that color temperature, color purity, and contrast of the PDP will be remarkably enhanced according to the test result. In this case, it is expected that the color temperature of the PDP is enhanced over about 1,000K.  
         [0063]     Accordingly, the front substrate of the PDP and fabricating method thereof according to the present invention has the following advantages or effects.  
         [0064]     First of all, the colorant amounting to the predetermined ratio is added to the upper dielectric layer to adjust the optical transmittance, whereby the color impurity of the PDP is enhanced.  
         [0065]     Secondly, the colorant amounting to the predetermined ratio is added to the upper dielectric layer to adjust the optical transmittance, whereby the color temperature of the PDP is enhanced.  
         [0066]     Thirdly, the colorant amounting to the predetermined ratio is added to the upper dielectric layer to adjust the optical transmittance, whereby the optical transmittance of the blue visible ray B is increased to enhance the contrast of the PDP.  
         [0067]     Finally, the colorant amounting to the predetermined ratio is added to the upper dielectric layer to adjust the optical transmittance, whereby an additional filter layer needs not to be formed to simplify the fabricating method of the PDP.  
         [0068]     The forgoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.