Abstract:
A plasma display panel capable of achieving a reduction in the reflectance of the panel and a method for manufacturing the same are disclosed. The plasma display panel includes a lower substrate, a discharge cell space defined by a plurality of barrier ribs on the lower substrate, a phosphor layer formed in the discharge cell space, and a functional film formed over the phosphor layer.

Description:
[0001]    This application claims the benefit of Korean Patent Application No. 10-2006-0028934, filed on Mar. 30, 2006, which is hereby incorporated by reference as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a plasma display panel, and more particularly to a plasma display panel capable of achieving a reduction in the reflectance of the panel and a method for manufacturing the same. 
         [0004]    2. Discussion of the Related Art 
         [0005]    Plasma display panels are well known as an emissive device which displays an image using a discharge phenomenon. Such a plasma display panel (PDP) is being highlighted as a display for an image display device having a large screen because the PDP has many advantages of simple manufacture, large screen size, and rapid response speed in that it is unnecessary to provide active elements for respective cells. 
         [0006]    As shown in  FIG. 1 , such a PDP has a structure in which an upper panel  10  and a lower panel  20  are assembled such that they face each other. The upper panel  10  includes a transparent substrate  11 , and a pair of sustaining electrodes  12  arranged on an inner surface of the transparent substrate  11 . Typically, the sustaining electrodes  12  are divided into a transparent electrode and a bus electrode. 
         [0007]    The sustaining electrodes  12  are coated with a dielectric layer  13  for AC driving. A protection film  14  is formed over the dielectric layer  13 . 
         [0008]    On the other hand, the lower panel  20  includes a lower substrate  21 , and address electrodes  22  arranged on an inner surface of the lower substrate  21 . A dielectric layer  23  is formed over the address electrodes  22 . Stripe or well type barrier ribs  24  are formed on the dielectric layer  23 , to isolate discharge cells from one another. Red, blue, green phosphor layers  26  for color display are coated over the cells defined by the barrier ribs  24 , to form sub pixels. 
         [0009]    The barrier ribs  24  define the discharge cells  25  for respective sub pixels. A discharge gas is sealed in each discharge cell  25 . Three different sub pixels constitute one pixel. 
         [0010]    However, the PDP has a structure in which the phosphor layers  26  exhibiting high reflectance are exposed to the eyes of the user through the transparent upper panel  10 , as shown in  FIG. 2 . For this reason, external light may be reflected by the phosphor layers  26 . 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, the present invention is directed to a plasma display panel and a method for manufacturing the same that substantially obviate one or more problems due to limitations and disadvantages of the related art. 
         [0012]    An object of the present invention is to provide a plasma display panel having an optical filter function such as an electromagnetic wave shield function or a color correction function, and a method for manufacturing the same. 
         [0013]    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. 
         [0014]    To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a plasma display panel comprises: a lower substrate; a discharge cell space defined by a plurality of barrier ribs on the lower substrate; a phosphor layer formed in the discharge cell space; and a functional film formed over the phosphor layer. 
         [0015]    In another aspect of the present invention, a plasma display panel comprises: an upper substrate; a dielectric layer covering sustaining electrodes formed on the upper substrate; and a functional layer arranged on the dielectric layer, the functional layer being made of MgO and a material having a refractive index different from MgO. 
         [0016]    In another aspect of the present invention, a plasma display panel comprises: an upper substrate; a lower substrate; and an anti-reflection layer arranged between the upper substrate and the lower substrate, the anti-reflection layer comprising two or more layers having different refractive indexes. 
         [0017]    In another aspect of the present invention, a method for manufacturing a plasma display panel comprises: forming a phosphor layer in a discharge cell space defined by a plurality of barrier ribs on a lower substrate; and forming an anti-reflection film over the phosphor layer. 
         [0018]    In still another aspect of the present invention, a method for manufacturing a plasma display panel comprises: forming a dielectric layer covering sustaining electrodes formed on an upper substrate; and forming a functional layer over the dielectric layer, the functional layer comprising a first layer made of MgO and a second layer made of a material having a refractive index different from MgO. 
         [0019]    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 
         [0020]    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: 
           [0021]      FIG. 1  is a perspective view illustrating an example of a general plasma display panel; 
           [0022]      FIG. 2  is a sectional view illustrating the general plasma display panel; 
           [0023]      FIG. 3  is a sectional view illustrating a plasma display panel according an exemplary embodiment of the present invention; and 
           [0024]      FIG. 4  is a sectional view illustrating a plasma display panel according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    The present invention now will be described more fully hereinafter with reference to the accompanying figures, in which embodiments of the invention are shown. 
         [0026]    This invention may, however, be embodied in many alternate forms and should not be construed as limited to the embodiments set forth herein. Accordingly, while the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims. 
         [0027]    Like numbers refer to like elements throughout the description of the figures. In the drawings, the thickness of layers and regions are exaggerated for clarity. 
         [0028]    It will be understood that when an element such as a layer, region or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. It will also be understood that if part of an element, such as a surface, is referred to as “inner,” it is farther to the outside of the device than other parts of the element. 
         [0029]    In addition, relative terms, such as “beneath” and “overlies”, may be used herein to describe one layer&#39;s or region&#39;s relationship to another layer or region as illustrated in the figures. 
         [0030]    It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. Finally, the term “directly” means that there are no intervening elements. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0031]    It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. 
         [0032]    These terms are only used to distinguish one region, layer or section from another region, layer or section. Thus, a first region, layer or section discussed below could be termed a second region, layer or section, and similarly, a second region, layer or section may be termed a first region, layer or section without departing from the teachings of the present invention. 
       First Embodiment 
       [0033]    Referring to  FIG. 3 , a plasma display panel (PDP) according to an exemplary embodiment of the present invention is shown. As shown in  FIG. 3 , the PDP includes an upper panel  100 , a lower panel  200 , and a functional film  300  formed in a discharge cell space  260  defined between the upper panel  100  and the lower panel  200 . 
         [0034]    The upper panel  100  includes an upper substrate  110 , a sustaining electrode pair  120  arranged on the upper substrate  110 , and a first dielectric layer  130  covering the sustaining electrode pair  120 . The upper panel  100  also includes a protection film  140 . 
         [0035]    On the other hand, the lower panel  200  includes a lower substrate  210 , an address electrode  220  formed on the lower substrate  210 , and a second dielectric layer  230  covering the address electrode  220 . 
         [0036]    The sustaining electrode pair  120  and address electrode  220  intersect each other. That is, the sustaining electrode pair  120  and address electrode  220  extend while forming an angle of 90° therebetween. However, in  FIG. 3 , the sustaining electrode pair  120  and address electrode  220  are illustrated as extending in the same direction, for the convenience of the illustration. 
         [0037]    A plurality of barrier ribs  240  are formed on the second dielectric layer  230  of the lower panel  200 , to define discharge cell spaces  260 . Phosphor layers  250  are formed in the discharge cell spaces  260  defined by the barrier ribs  240 . 
         [0038]    A functional film  300  having an anti-reflection function is formed over the phosphor layer  250  formed in each discharge cell space  260 . 
         [0039]    The functional film  300  may have a single-layer structure or a multilayer structure. The functional film  300  may be formed of a material substantially having a refractive index of 1 to 3. 
         [0040]    Where the functional film  300  has a multilayer structure, it may be formed by alternately laminating a first film  310  and a second film  320  having different refractive indexes, as shown in  FIG. 3 .  FIG. 3  illustrates a multilayer structure in which the first film  310  and second film  320  are alternately laminated two times. Of course, an increased number of films may be laminated. 
         [0041]    The structure of the functional film  300  formed in accordance with a repeated film lamination can shield reflection light generated from the phosphor layer  250  or in the inner structure of the PDP in accordance with a light multi-interference phenomenon. 
         [0042]    It is preferred that the functional film  300  be made of a material having sufficiently-high band-gap energy because it should not absorb visible rays or ultraviolet rays generated in the discharge cell space  260 . Accordingly, the material of the functional film  300  may be selected such that the band-gap energy thereof is higher than the energy corresponding to blue light. 
         [0043]    Materials suitable for the first film  310  and second film  320  of the functional film  300  and the refractive index and transmission wavelength ranges of the materials are shown in the following Table 1. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Transmission 
               
               
                   
                 Material 
                   
                 Refractive Index 
                 Wavelength Range 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Al 2 O 3   
                 1.63 
                 550 nm 
                 200–5,000 
                 nm 
               
               
                   
                 CeF 3   
                 1.63 
                 500 nm 
                 300–5,000 
                 nm 
               
               
                   
                 Na 3 AlF 6   
                 1.33 
                 500 nm 
                 250–14,000 
                 nm 
               
               
                   
                 HfO 2   
                 2.0 
                 500 nm 
                 230–7,000 
                 nm 
               
               
                   
                 ITO 
                 2.0 
                 500 nm 
                 400–800 
                 nm 
               
               
                   
                 CaF 2   
                 1.35 
                 550 nm 
                 150–12,000 
                 nm 
               
               
                   
                 MgF 2   
                 1.38 
                 550 nm 
                 130–7,000 
                 nm 
               
               
                   
                 MgO 
                 1.7 
                 500 nm 
                 200–8,000 
                 nm 
               
               
                   
                 SiO 2   
                 1.46 
                 550 nm 
                 200–2,000 
                 nm 
               
               
                   
                 Ta 2 O 5   
                 2.1 
                 500 nm 
                 400–7,000 
                 nm 
               
               
                   
                 TiO 2   
                 2.3 
                 500 nm 
                 400–12,000 
                 nm 
               
               
                   
                 ZrO 2   
                 2.05 
                 500 nm 
                 300–7,000 
                 nm 
               
               
                   
                 BaF 2   
                 1.4 
                 10,600 nm   
                 220–11,000 
                 nm 
               
               
                   
                 ZnS 
                 2.4 
                 1,200 nm   
                 400–14,000 
                 nm 
               
               
                   
                 PbF 2   
                 1.7 
                 500 nm 
                 220–9,000 
                 nm 
               
               
                   
                   
               
             
          
         
       
     
         [0044]    As shown in Table 1, materials exhibiting a refractive index of 1 to 3 with respect to a wavelength band of about 500 nm can be used. Such materials may include various materials such as oxides, fluorides, and semiconductors including Al 2 O 3 , CeF 3 , Na 3 AlF 6 . HfO 2 , indium tin oxide (ITO), CaF 2 , MgO, SiO 2 , Ta 2 O 5 , TiO 2 , ZrO 2 , BaF 2 , ZnS, and PbF 2 . 
         [0045]    When one material is selected for the first film  310 , another material having a refractive index different from the material of the first film  310  may be selected for the second film  310 . 
         [0046]    Where the functional film  300  has a single-layer structure, it can perform a desired anti-reflection function and other desired functions. However, when the first film  310  and second film  320  having different refractive indexes are alternately formed such that the functional film  300  has a multilayer structure, light beams reflected from the multilayer structure due to the refractive index difference of the films in the multilayer structure generate offset interference. As a result, it is possible to reduce the phenomenon that light incident to the interior of the PDP through the upper panel  100  is externally reflected. 
         [0047]    Thus, the functional film  300  performs a function for preventing external light from being reflected from the discharge cell space  260  formed with the highly-reflective phosphor layer  250  after being incident to the discharge cell space  260 , and thus, preventing the contrast of the panel from being reduced. 
         [0048]    The formation of the functional film  300  may be achieved using a sputtering process, which is a dry process, or a spin coating process, which is a wet process. Of course, other methods may be used. 
         [0049]    The functional film  300  may be formed at any position between the upper panel  100  and the lower panel  200  because it can achieve a desired function as long as it is arranged over the phosphor layer  250  in the discharge cell space  260 . 
         [0050]    If necessary, the functional film  300  may be arranged in the upper panel  100  or on the upper panel  100 . 
       Second Embodiment 
       [0051]      FIG. 4  illustrates a PDP having a structure in which a functional layer  150  is arranged on the lower surface of an upper panel  100 . 
         [0052]    In this structure, the upper panel  100  includes an upper substrate  110 , and a first dielectric layer  130  covering sustaining electrode pairs  120  formed on an upper substrate  110 . The functional layer  150  is arranged on the first dielectric layer  130 . The functional layer  150  includes a layer made of MgO, and a layer made of a material having a refractive index different from MgO. 
         [0053]    The functional layer  150  may have a multilayer structure including two or more layers. The functional layer  150  may have a protection film function for protecting the upper panel  100  from discharge occurring in the PDP, and an anti-reflection film function for preventing light incident to the PDP through the upper panel  100  from being reflected. 
         [0054]    The functional layer  150  may include a first layer  151  made of MgO, and a second layer  152  made of a material other than MgO. 
         [0055]      FIG. 4  illustrates a structure in which the first layer  151  of the functional layer  150  is formed over the first dielectric layer  130 . Of course, the second layer  152  of the functional layer  150  may be formed over the first dielectric layer  150 . 
         [0056]    Although MgO is most generally used as the protection film of the PDP, a material other than MgO may also be used for the first layer  151 . 
         [0057]    The first layer  151  or second layer  152  may be selected from various materials such as oxides, fluorides, and semiconductors including Al 2 O 3 , CeF 3 , Na 3 AlF 6 , HfO 2 , indium tin oxide (ITO), CaF 2 , SiO 2 , MgO, Ta 2 O 5 , TiO 2 , ZrO 2 , BaF 2 , ZnS, and PbF 2 . 
         [0058]    The formation of the functional film  150  may be achieved using a sputtering process, which is a dry process, or a spin coating process, which is a wet process. Of course, other methods may be used. 
         [0059]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. 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.