Abstract:
A flat panel display device has a conductive layer formed between a substrate and a polarization plate to prevent static electricity from appearing between the substrate and the polarization plate, thereby improving screen display quality. The flat panel display device includes: a flat display panel including a substrate having an image display unit, a display element arranged on the image display unit of the substrate, and a sealing unit for sealing the display element; a polarization member arranged on at least one of the substrate and the sealing unit; and a shielding member arranged at a portion that does not correspond to the image display unit of the substrate in order to prevent the appearance of static electricity between the substrate and the polarization member.

Description:
CLAIM OF PRIORITY  
       [0001]     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for FLAT PANEL DISPLAY DEVICE earlier filled in the Korean Intellectual Property Office on Nov. 18, 2004 and there duly assigned Serial No. 10-2004-0094507.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Technical Field  
         [0003]     The present invention relates to a flat panel display device and, more particularly, to an organic light emitting diode (OLED) having a unit for preventing formation of static electricity between a polarization plate and a substrate.  
         [0004]     2. Related Art  
         [0005]     In general, active-matrix organic light-emitting diodes (AMOLEDs) include a plurality of pixels arranged on a substrate. Each of the pixels includes at least one switching thin film transistor, one driving thin film transistor, a capacitor, and an organic electroluminescence (EL) element. An organic EL element is a self emission element which is driven by a thin film transistor. The organic EL element includes an anode electrode, an organic layer having a light emitting layer, and a cathode electrode, and it emits light from the light emitting layer of the organic layer according to voltages applied between the anode electrode and the cathode electrode.  
         [0006]     Since the thin film transistor and the capacitor that form an OLED include an electrode made of a metallic material and an interconnection, external light is reflected by the metal electrode and interconnection so that the contrast of the OLED is greatly degraded.  
         [0007]     The contrast of a flat panel display device, such as an OLED, is greatly reduced according to the intensity of external light. Thus, in the conventional OLED, a polarization plate is attached to a substrate so as to prevent reduction of contrast caused by external light.  
         [0008]     An organic electroluminescence display device includes an organic electroluminescence (EL) display panel, a polarization plate, and a bracket for supporting the organic EL display panel. The organic EL display panel includes an upper substrate and a lower substrate. The organic EL display panel further includes an organic EL element formed between the upper substrate and the lower substrate.  
         [0009]     In the organic electroluminescence display device having the above structure, static electricity induced between the polarization plate and the substrate causes malfunction of the organic EL element or affects the electrostatic capacity of a capacitor so that picture quality is lowered. In addition, due to the static electricity induced between the polarization plate and the substrate, an image display region is destroyed so that a desired image cannot be displayed.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention provides a flat panel display device in which appearance of static electricity is prevented by using a conductive layer between a substrate and a polarization plate.  
         [0011]     According to an aspect of the present invention, a flat panel display device includes: a flat display panel including a substrate having an image display unit, a display element arranged on the image display unit of the substrate, and a sealing unit for sealing the display element; a polarization member arranged on at least one of the substrate and the sealing unit; and a shielding member arranged at a portion that does not correspond to the image display unit of the substrate in order to prevent appearance of static electricity between the substrate and the polarization member.  
         [0012]     The shielding member includes a shielding film arranged at an outline of the polarization member that does not correspond to the image display unit. The shielding member may be arranged at the substrate or the sealing unit in which the polarization member is arranged, and may include a shielding film arranged at an outline of the polarization member that does not correspond to the image display unit. The shielding member may be formed in a closed loop shape.  
         [0013]     The shielding member includes a conductive film selected from a conductive metallic film and a conductive nonmetallic film. The shielding member may include a conductive film selected from a transparent conductive film and an opaque conductive film.  
         [0014]     The flat display panel is an electroluminescence (EL) display panel.  
         [0015]     According to another aspect of the present invention, a flat panel display device includes: a flat panel display panel including a substrate having an image display unit, a display element arranged on the image display unit of the substrate, and a sealing unit for sealing the display element; a polarization member arranged on at least one of the substrate and the sealing unit; and a shielding member arranged at a portion that corresponds to the image display unit of the substrate in order to prevent appearance of static electricity between the substrate and the polarization member.  
         [0016]     The shielding member includes a shielding film arranged at a portion of the polarization member that corresponds to the image display unit. The shielding member may be arranged at the substrate or the sealing unit in which the polarization member is arranged, and may include a shielding film arranged at a portion of the polarization member that corresponds to the image display unit. The shielding member may be formed in a mesh shape.  
         [0017]     The shielding member includes a conductive film selected from a conductive metallic film and a conductive nonmetallic film. The shielding member may include a transparent conductive film.  
         [0018]     The flat display panel is an electroluminescence (EL) display panel. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     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:  
         [0020]      FIG. 1  is an exploded perspective view of an organic electroluminescence display device;  
         [0021]      FIG. 2  is an exploded perspective view of an organic electroluminescence display device according to an embodiment of the present invention;  
         [0022]      FIG. 3  is a cross-sectional view of an organic electroluminescence (EL) panel of the organic electroluminescence display device shown in  FIG. 2 ;  
         [0023]      FIG. 4  is an exploded perspective view of an organic electroluminescence display device according to another embodiment of the present invention;  
         [0024]      FIG. 5  is a plan view of a shielding member for preventing appearance of static electricity in the organic electroluminescence display device shown in  FIG. 2 ; and  
         [0025]      FIG. 6  is a plan view of a shielding member for preventing appearance of static electricity in the organic electroluminescence display device shown in  FIG. 4 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]      FIG. 1  is an exploded perspective view of an organic electroluminescence display device. Referring to  FIG. 1 , the organic electroluminescence display device  100  includes an organic electroluminescence (EL) display panel  120 , a polarization plate  130 , and a bracket (not shown) for supporting the organic EL display panel  120 . The organic EL display panel  120  includes an upper substrate  125  and a lower substrate  121 . Although not shown, the organic EL display panel  120  further includes an organic EL element formed between the upper substrate  125  and the lower substrate  121 . In  FIG. 1 , reference numeral  129  denotes a driving IC.  
         [0027]     In the organic electroluminescence display device having the above structure, static electricity induced between the polarization plate  130  and the substrate  125  causes malfunction of the organic EL element or affects the electrostatic capacity of a capacitor so that picture quality is lowered. In addition, due to the static electricity induced between the polarization plate  130  and the substrate  125 , an image display region is destroyed so that a desired image cannot be displayed.  
         [0028]      FIG. 2  is an exploded perspective view of an organic electroluminescence display device according to an embodiment of the present invention. Referring to  FIG. 2 , the organic electroluminescence display device  200  includes an organic electroluminescence (EL) display panel  220 , a bracket  210  for supporting the organic EL display panel  220 , and a polarization member  230  which intercepts external light incident on the organic EL display panel  220 .  
         [0029]     The bracket  210  supports the organic EL display panel  220 , is formed in a plate shape having a size corresponding to the organic EL display panel  220 , and has an open side barrier rib  210   a . The bracket  210  shown in  FIG. 2  is not limited to the above structure, and may be formed in a variety of structures for supporting the organic EL display panel  220 .  
         [0030]     The polarization member  230  prevents external light from reaching a sealing unit  225  of the organic EL display panel  220 . As the polarization member  230 , a polarization plate may be used as shown in  FIG. 2 , or a polarization material layer may be coated on the sealing unit  225 .  
         [0031]      FIG. 3  is a cross-sectional view of the organic electroluminescence (EL) display panel of the organic electroluminescence display device shown in  FIG. 2 , which is a cross-sectional view of one unit pixel. Referring to  FIG. 3 , the organic EL display panel  220  includes a lower substrate  221  and a sealing unit (for example, an upper substrate  225 ) for sealing the lower substrate  221  using a sealant  227 . The lower substrate  221  includes an image display unit  201  which displays a desired image.  
         [0032]     The image display unit  201  displays an image using light emitted from an organic EL element (not shown). A plurality of pixels  224  are arranged on the image display unit  201  of the lower substrate  221  in a matrix shape, and each of the pixels  224  includes an organic electroluminescence (EL) element  223  and a thin film transistor  222  which is a driving element for driving the organic EL element  223 .  
         [0033]     The image display unit  201  of the lower substrate  221  is sealed by the sealing unit  225  using a sealant  227  so as to protect the image display unit  201  from the outside. Since the organic electroluminescence display device shown in  FIGS. 2 and 3  has a front emission structure in which light emitted from the organic EL element  223  is emitted toward the sealing unit  225 , a polarization member  230  for intercepting external light is arranged on the exterior of the sealing unit  225 .  
         [0034]     In the organic electroluminescence display device  200  shown in  FIG. 2 , the organic EL display panel  220  is not limited to the structure of  FIG. 3 , and the organic electroluminescence (EL) element and the thin film transistor for driving the organic EL element may have a variety of structures.  
         [0035]     In the embodiment shown in  FIG. 2 , the polarization member  230  is attached to the outside of the sealing unit  225  of the organic EL display panel  220 . The present invention is not limited to this, and the polarization member  230  may be arranged at the interior of the sealing unit  225  according to the type of the polarization member  230 .  
         [0036]     The organic electroluminescence display device  200  shown in  FIG. 2  further includes a shielding member  235 , which is disposed between the sealing unit  225  of the organic EL panel  220  and the polarization member  230 , and which prevents static electricity. As seen in  FIG. 5 , the shielding member  235  is arranged to correspond to an outline  232  of the polarization member  230 , excluding a portion  231  that corresponds to the image display unit  201  of the organic EL display device  200 . The shielding member  235  may be formed in a closed loop shape.  
         [0037]     The shielding member  235  of  FIG. 2  for preventing the appearance of static electricity can be made of a variety of types of conductive materials, such as a conductive metallic film, a conductive nonmetallic film, a transparent conductive film, and an opaque conductive film.  
         [0038]     The shielding member  235  may be formed in various shapes, such as that of a conductive plate, a conductive film, or a conductive thin film. The shielding member  235  may be separated from the polarization member  230  and arranged between the polarization member  230  and the sealing unit  225 , or it may be attached to the polarization member  230  or formed by various methods, such as patterning or coating on the polarization member  230 .  
         [0039]     The shielding member  235  of  FIG. 2  has a frame shape as shown in  FIG. 5 , but it is not limited to that shape. The shielding member  235 , having a variety of shapes for preventing the appearance of static electricity, may be arranged at the outline  232  ( FIG. 5 ) of the polarization member  230  ( FIG. 2 ). In addition, the shielding member  235  may be arranged at an outline of the sealing unit  225  of the organic EL display panel  220 . In  FIG. 2 , reference numeral  229  denotes a driving IC.  
         [0040]      FIG. 4  is an exploded perspective view of the organic electroluminescence display device according to another embodiment of the present invention. Referring to  FIG. 4 , the organic electroluminescence display device  300  includes an organic electroluminescence (EL) display panel  320 , a bracket  310  for supporting the organic EL display panel  320 , and a polarization member  330  which intercepts external light incident or the organic EL display panel  320 , as in  FIG. 2 .  
         [0041]     The bracket  310  supports the EL display panel  320 , is formed in a plate shape having a size corresponding to the organic EL display panel  320 , and has an open side barrier rib  310   a . In addition, as in  FIG. 2 , the polarization member  330  prevents external light from reaching a sealing unit  325  of the organic EL display panel  320 . A polarization plate may be used as the polarization member  330 , or a polarization material layer may be coated on the sealing unit  325 .  
         [0042]     The organic EL display panel  320  has a cross-sectional structure as shown in  FIG. 3 . That is, the organic EL display panel  320  includes a lower substrate  321  having an image display unit  201 , and a sealing unit (for example, an upper substrate  325 ) for sealing the lower substrate  321  using a sealant  227 .  
         [0043]     The image display unit  201  displays an image using light emitted from the organic EL element (not shown). As shown in  FIG. 3 , a plurality of pixels  224  are arranged on the image display unit  201  in a matrix shape, and each of the pixels  224  includes an organic electroluminescence (EL) element  223  and a thin film transistor  222  which is a driving element for driving the organic EL element  223 . In  FIG. 4 , reference numeral  329  denotes a driving IC.  
         [0044]     Since the organic electroluminescence display device shown in  FIG. 4  has a front emission structure in which light emitted from the organic EL element  223  is emitted toward the sealing unit or upper substrate  325 , a polarization member  330  for intercepting external light is arranged at the exterior of the sealing unit or upper substrate  325 .  
         [0045]     The organic electroluminescence display device  300  shown in  FIG. 4  further includes a shielding member  335 , which is disposed between the sealing unit  325  of the organic EL display panel  320  and the polarization member  330 , and which prevents the appearance of static electricity therebetween.  
         [0046]     The shielding member  335  is arranged at a portion  331  (see  FIG. 6 ) that corresponds to the image display unit  201  ( FIG. 3 ) of the organic EL display panel  320  ( FIG. 4 ) of the polarization member  330 . The shielding member  335  may be formed in a mesh shape.  
         [0047]     Unlike in  FIG. 2 , since the shielding member  335  of  FIG. 4  for preventing the appearance of static electricity is arranged not at an outline  332  ( FIG. 6 ) of the polarization member  330 , but at a portion  331  corresponding to the image display unit  201  ( FIG. 3 ), the shielding member  335  of  FIG. 4  may include a transparent conductive material through which light emitted from the organic EL element  223  is transmitted.  
         [0048]     The shielding member  335  of  FIG. 4  may be made of a variety of conductive materials, such as a conductive metallic film or a conductive nonmetallic film, and may be formed in various shapes, such as that of a conductive plate, a conductive film, or a conductive thin film.  
         [0049]     The shielding member  335  may be separated from the polarization member  330  and arranged between the polarization member  330  and the sealing unit  325 , or it may be attached to the polarization member  330  or formed by various methods, such as patterning or coating on the polarization member  330 .  
         [0050]     In the embodiment shown in  FIG. 4 , the shielding member  335  for preventing the appearance of static electricity is arranged in a mesh shape at the portion  331  ( FIG. 6 ) that corresponds to the image display unit  201  ( FIG. 3 ) of the polarization member  330  of  FIG. 4 , but the present invention is not limited to that arrangement. The shielding member  335  having a variety of shapes may be arranged at the central portion  331  ( FIG. 6 ) of the polarization member  330  of  FIG. 4 . In addition, the shielding member  335  may be arranged at a portion that corresponds to the image display unit  201  ( FIG. 3 ) of the sealing unit  325  ( FIG. 4 ) of the organic EL display panel  320 .  
         [0051]     In the embodiment of the present invention, in the organic electroluminescence display device having a front emission structure in which light emitted from the organic EL display panel is emitted in a direction opposite to that of the substrate, that is, toward the sealing unit, the polarization member is attached to the exterior of the sealing unit so as to prevent external light from being incident on the sealing unit, and a conductive film shown in  FIG. 5  or  6  for preventing the appearance of static electricity is arranged between the sealing unit of the organic EL panel and the polarization plate. However, the present invention is not limited to this, and may be applied to an organic electroluminescence display device having a rear emission structure or to an electroluminescence display device having a both-side emission structure.  
         [0052]     That is, in the organic electroluminescence display device having the rear emission structure in which light emitted from the organic EL panel is emitted in the direction of the substrate, a polarization member for preventing external light from reaching the substrate is attached to the exterior of the substrate, and a conductive film shown in  FIG. 5  or  6  for preventing the appearance of static electricity may be arranged between the substrate and the polarization member.  
         [0053]     In the organic electroluminescence display device having the both-end emission structure in which light emitted from the organic EL panel is emitted toward both sides of the substrate and the sealing unit, which is a direction opposite to that of the substrate, upper and lower polarization members for preventing external light incident on the substrate and the sealing unit are attached to the exteriors of the substrate and the sealing unit, and a conductive film shown in  FIG. 5  or  6  for preventing the appearance of static electricity may be arranged between the substrate and the lower polarization member, and between the sealing unit and the upper polarization member.  
         [0054]     In the organic electroluminescence display device, the shielding member for preventing the appearance of static electricity between the substrate and the polarization plate is formed on the polarization plate or the substrate, but the present invention is not limited to such an arrangement, and may be applied to a flat panel display device using a polarization plate, such as a liquid crystal display (LCD).  
         [0055]     Although the present invention illustrates active-matrix organic light emitting diodes (AMOLEDs) in which an organic EL element forming pixels is driven by a thin film transistor, it may be applied to passive-matrix organic light-emitting diodes (PMOLEDs).  
         [0056]     In the organic electroluminescence display device, the conductive film is formed between the substrate and the polarization member so that the appearance of static electricity between the substrate and the polarization member is prevented, and screen display quality can be improved.  
         [0057]     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 detail may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.