Patent Publication Number: US-7583024-B2

Title: Double-faced plasma display panel

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to double-faced display devices, and more particularly to a kind of double-faced plasma display panel. 
     2. Prior Art 
     A plasma display panel is a thin flat screen display device having a large screen size. In use, electrons are accelerated by an electric field so that the accelerated electrons collide with a discharge gas. This causes excitation of the discharge gas and subsequent remission. The remission process causes radiation of ultraviolet rays. The ultraviolet rays irradiate a fluorescent material, whereby the ultraviolet rays are converted into visible light. 
       FIG. 5  is an isometric view of part of a conventional plasma display panel  1 . The plasma display panel  1  comprises a transparent substrate  11  and an opaque substrate  12 . A plurality of scanning electrodes  14  and a plurality of displaying electrodes  13  are alternately arranged on an inner surface of the transparent substrate  11 , and are each aligned in a first horizontal direction. A transparent dielectric layer  15  covers the scanning electrodes  14  and the displaying electrodes  13 , so that the scanning electrodes  14  and the displaying electrodes  13  are embedded in the transparent dielectric layer  15 . A protection layer  16  covers the transparent dielectric layer  15 . A plurality of addressing electrodes  17  are arranged on an inner surface of the opaque substrate  12 , and are each aligned in a second horizontal direction. The second horizontal direction is perpendicular to the first horizontal direction, and the inner surface of the opaque substrate  12  is opposite to the inner surface of the transparent substrate  11 . An opaque dielectric layer  18  covers the addressing electrodes  17 , so that the addressing electrodes  17  are embedded in the opaque dielectric layer  18 . A plurality of separation walls  19  extend up from the opaque dielectric layer  18 , the separation walls  19  each being aligned in the second horizontal direction. Each separation wall  19  generally separates two adjacent addressing electrodes  17 . A fluorescent layer  10  is coated on exposed regions (not labeled) of the opaque dielectric layer  18  and side faces (not labeled) of the separate walls  19 . The fluorescent layer  10  comprises three primary colors, such as red, green and blue. A discharge gas is filled within a discharge space  168  defined between the protection layer  16  and the opaque dielectric layer  18 . 
     When a voltage applied between the displaying electrodes  13  and the scanning electrodes  14  is more than the starting voltage, the discharge gas in the discharge space  168  discharges and generates ultraviolet rays. The ultraviolet rays irradiate the fluorescent layer  10 , and the fluorescent layer  10  luminesces in accordance with the three primary colors. Thus visible light is emitted from an outer surface of the transparent substrate  11 . 
     U.S. Pat. No. 6,703,772 discloses a similar kind of plasma display panel. In such plasma display panel, an image is only displayed on an outer surface of the transparent substrate, and cannot be displayed on an outer surface of the opaque substrate. However, in certain applications, the plasma display panel is required to simultaneous display images at two opposite sides thereof. Generally, a pair of such plasma display panels are adopted to form a double-faced plasma display panel assembly. The opaque substrates of the plasma display panels are engaged with each other. In such kind of double-faced plasma display panel assembly, two driving systems are needed. Furthermore, the structure of the double-faced plasma display panel assembly is complicated. Thus, the double-faced plasma display panel assembly is bulky and expensive. 
     A double-faced plasma display panel which overcomes the above-mentioned problems is desired. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a double-faced plasma display panel having a simple structure, a small size, and a low cost. 
     To achieve the above-mentioned object, the present invention provides a double-faced plasma display panel comprising two parallel viewing screens and a discharge structure located between the viewing screens. Each viewing screen comprises a transparent substrate with a plurality of transparent scanning electrodes, a plurality of transparent displaying electrodes, a transparent dielectric layer and a protection layer formed at an inner surface of the transparent substrate. The scanning electrodes and the displaying electrodes are alternately arranged on the inner surface of the transparent substrate, and are each aligned in a first horizontal direction. The transparent dielectric layer covers the transparent scanning electrodes and the transparent displaying electrodes. The protection layer covers the transparent dielectric layer. 
     The discharge structure comprises an opaque insulative substrate having two opposite surfaces. Each surface generally faces the corresponding viewing screen. A plurality of addressing electrodes, an opaque dielectric layer, a plurality of separation walls and a fluorescent layer are formed at each surface of the opaque insulate substrate. The addressing electrodes are arranged on the surface, and are each aligned in a second horizontal direction, which is perpendicular to the first horizontal direction. The opaque dielectric layer covers the addressing electrodes. The separation walls are formed at the opaque dielectric layer and are each aligned in the second horizontal direction. Each separation wall generally separates two adjacent addressing electrodes. The fluorescent layer is coated on exposed regions of the opaque dielectric layer and side faces of the separate walls. The fluorescent layer comprises three primary colors, such as red, green and blue. 
     Each protection layer and the corresponding opaque dielectric layer cooperatively define a discharge space. A discharge gas is filled within discharge spaces. The discharge gas is selected from the group consisting of helium gas, neon gas, xenon gas, argon gas, and any mixture thereof. 
     When the scanning electrodes and the displaying electrodes are regarded as the row electrodes, the addressing electrodes are regarded as the column electrodes. Conversely, when the addressing electrodes are regarded as the row electrodes, the scanning electrodes and the displaying electrodes are regarded as the column electrodes. Each pair of row electrodes which are symmetrical to the opaque insulative substrate are electrically interconnected. Each pair of column electrodes which are axially symmetrical to a center of the opaque insulate substrate are electrically interconnected. Furthermore, a single driving system is applied in the plasma display panel to achieve simultaneous display images at the two viewing screens. 
     Compared with a conventional plasma display panel, the plasma display panel of the present invention adopts a pair of viewing screens and a single driving system to simultaneously display same images at the two viewing screens. Therefore, the plasma display panel has a simple structure, a small size, and a low cost. This enables the plasma display panel to be advantageously applied in traffic signal boards, large-scale display boards, surround cinemas and so on. 
     Other objects, advantages and novel features of the invention 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 an enlarged, isometric view of part of a double-faced plasma display panel of the present invention; 
         FIG. 2  is essentially a schematic side plan view of the plasma display panel of  FIG. 1 ; 
         FIG. 3  is essentially a schematic, side plan diagram of an opaque insulative substrate and addressing electrodes of the plasma display panel of  FIG. 1 , showing these parts tilted to a vertical orientation, and showing connections of the addressing electrodes when they are regarded as row electrodes; 
         FIG. 4  is essentially a schematic, side plan diagram of the opaque insulative substrate, protection layers and displaying electrodes of the plasma display panel of  FIG. 1 , showing connections of the displaying electrodes when they are regarded as column electrodes; and 
         FIG. 5  is an isometric view of part of a conventional plasma display panel. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a double-faced plasma display panel (not labeled) of a display panel assembly of the present invention comprises two parallel viewing screens  20 ,  20 ′, and a discharge structure  30  located between the viewing screens  20 ,  20 ′. The viewing screen  20  comprises a transparent substrate  21 , with a plurality of transparent scanning electrodes  24 , a plurality of transparent displaying electrodes  23 , a transparent dielectric layer  22 , and a protection layer  25  formed at an inner surface (not labeled) of the transparent substrate  21 . The scanning electrodes  24  and the displaying electrodes  23  are alternately arranged on the inner surface of the transparent substrate  21 , and are each aligned in a first horizontal direction. The transparent dielectric layer  22  covers the transparent scanning electrodes  24  and the transparent displaying electrodes  23 , so that the transparent scanning electrodes  24  and the transparent displaying electrodes  23  are embedded in the transparent dielectric layer  22 . The protection layer  25  covers the transparent dielectric layer  22 . 
     The viewing screen  20 ′ has substantially the same structure as that of the viewing screen  20 . The viewing screen  20 ′ comprises a transparent substrate  21 ′, with a plurality of transparent scanning electrodes  24 ′, a plurality of transparent displaying electrodes  23 ′, a transparent dielectric layer  22 ′, and a protection layer  25 ′ formed at an inner surface (not labeled) of the transparent substrate  21 ′. The scanning electrodes  24 ′ and the displaying electrodes  23 ′ are alternately arranged on the inner surface of the transparent substrate  21 ′, and are each aligned in the first horizontal direction. The transparent dielectric layer  22 ′ covers the transparent scanning electrodes  24 ′ and the transparent displaying electrodes  23 ′, so that the transparent scanning electrodes  24 ′ and the transparent displaying electrodes  23 ′ are embedded in the transparent dielectric layer  22 ′. The protection layer  25 ′ covers the transparent dielectric layer  22 ′. 
     The discharge structure  30  located between the viewing screens  20 ,  20 ′ comprises an opaque insulative substrate  31  as a central plane thereof. The opaque insulative substrate  31  comprises two opposite surfaces  310 ,  310 ′. Each surface  310 ,  310 ′ generally faces the corresponding viewing screen  20 ,  20 ′. A plurality of addressing electrodes  37 , an opaque dielectric layer  38 , a plurality of separation walls  39  and a fluorescent layer  40  are formed at the surface  310  of the opaque insulative substrate  31 . The addressing electrodes  37  are arranged on the surface  310 , and are each aligned in a second horizontal direction, which is perpendicular to the first horizontal direction. The opaque dielectric layer  38  covers the addressing electrodes  37 , so that the addressing electrodes  37  are embedded in the opaque dielectric layer  38 . The separation walls  39  extend up from the opaque dielectric layer  38 , and are each aligned in the second horizontal direction. Each separation wall  39  generally separates two adjacent addressing electrodes  37 . That is, each addressing electrode  37  is positioned under a gap (not labeled) defined between two adjacent separation walls  39 . The fluorescent layer  40  is coated on exposed regions (not labeled) of the opaque dielectric layer  38  and side faces (not labeled) of the separate walls  39 . The fluorescent layer  40  comprises three primary colors, such as red, green and blue. 
     Similarly, a plurality of addressing electrodes  37 ′, an opaque dielectric layer  38 ′, a plurality of separation walls  39 ′ and a fluorescent layer  40 ′ are formed at the surface  310 ′ of the opaque insulative substrate  31 . The addressing electrodes  37 ′ are arranged on the surface  310 ′, and are each aligned in the second horizontal direction. The opaque dielectric layer  38 ′ covers the addressing electrodes  37 ′, so that the addressing electrodes  37 ′ are embedded in the opaque dielectric layer  38 ′. The separation walls  39 ′ extend down from the opaque dielectric layer  38 ′, and are each aligned in the second horizontal direction. Each separation wall  39 ′ generally separates two adjacent addressing electrodes  37 ′. That is, each addressing electrode  37 ′ is positioned above a gap (not labeled) defined between two adjacent separation walls  39 ′. The fluorescent layer  40 ′ is coated on exposed regions (not labeled) of the opaque dielectric layer  38 ′ and side faces (not labeled) of the separation walls  39 ′. The fluorescent layer  40 ′ comprises three primary colors, such as red, green and blue. 
       FIG. 2  is essentially a schematic side plan view of the double-faced plasma display panel shown in  FIG. 1 . The protection layer  25  and the opaque dielectric layer  38  cooperatively define a discharge space  258 , and the protection layer  25 ′ and the opaque dielectric layer  38 ′ cooperatively define a discharge space  258 ′. Because of the opaque dielectric layer  38  and the opaque dielectric layer  38 ′, the discharge space  258  and the discharge space  258 ′ are independent of each other. A discharge gas is filled within the discharge space  258  and the discharge space  258 ′. The discharge gas is selected from the group consisting of helium gas, neon gas, xenon gas, argon gas, and any mixture thereof. Furthermore, four side walls  41  are mounted between four opposite side extremities of the protection layers  25 ,  25 ′. The side walls  41  are used to support the protection layers  25 ,  25 ′, and maintain the protection layers  25 ,  25 ′ a certain distance apart. 
     For the viewing screen  20 , there are two kinds of configurations for the electrodes  23 ,  24 ,  37 . The first configuration is as follows. The addressing electrodes  37  are regarded as row electrodes, and the scanning electrodes  24  and the displaying electrodes  23  are regarded as column electrodes. The second configuration is as follows. The scanning electrodes  24  and the displaying electrodes  23  are regarded as row electrodes, and the addressing electrodes  37  are regarded as column electrodes. The interconnections of the electrodes  23 ,  24 ,  37  in the two configurations are similar. In the preferred embodiment, the first configuration is adopted. Similarly, for the viewing screen  20 ′, a configuration analogous to the first configuration is adopted for the electrodes  23 ′,  24 ′,  37 ′. 
       FIG. 3  is a schematic diagram showing connections of row addressing electrodes  37 ,  37 ′. The addressing electrodes  37 ,  37 ′ at a first row are labeled as  371 ,  371 ′, and the addressing electrodes  37 ,  37 ′ at a second row are labeled as  372 ,  372 ′. The addressing electrodes  371 ,  371 ′ are electrically interconnected, and the addressing electrodes  372 ,  372 ′ are electrically interconnected. Similarly, other addressing electrodes  37 , 37 ′ at same rows are electrically interconnected.  FIG. 4  is a schematic diagram showing connections of column displaying electrodes  23 ,  23 ′, and similar connections of column scanning electrodes  24 ,  24 ′ are not shown. Regarding the column displaying electrodes  23 ,  23 ′, a first pair of column displaying electrodes  23 ,  23 ′ which are axially symmetrical to a center of the opaque insulative substrate  31  are labeled as  231 ,  231 ′, and a second pair of column displaying electrodes  23 ,  23 ′ which are axially symmetrical to the center of the opaque insulative substrate  31  are labeled as  232 ,  232 ′. The displaying electrodes  231 ,  231 ′ are electrically interconnected, and the displaying electrodes  232 ,  232 ′ are electrically interconnected. Similarly, other pairs of column displaying electrodes  23 ,  23 ′ which are axially symmetrical to the center of the opaque insulative substrate  31  are electrically interconnected. 
     A single driving system  50  is applied in the plasma display panel. The addressing electrodes  37 ,  37 ′, the displaying electrodes  23 ,  23 ′, and the scanning electrodes  24 ,  24 ′are electrically connected to the single driving system  50  respectively. When a voltage applied between the displaying electrodes  23  and the scanning electrodes  24  is more than the starting voltage, the discharge gas in the discharge space  258  discharges and generates ultraviolet rays. The ultraviolet rays irradiate the fluorescent layer  40 , and the fluorescent layer  40  luminesces in accordance with the three primary colors thereof. Thus visible light is emitted from an outer surface of the transparent substrate  21 , and a first image is displayed on the viewing screen  20 . 
     Similarly, the discharge gas in the discharge space  258 ′ discharges and generates ultraviolet rays. The ultraviolet rays irradiate the fluorescent layer  40 ′, and the fluorescent layer  40 ′ luminesces in accordance with the three primary colors thereof. Thus visible light is emitted from an outer surface transparent substrate  21 ′, and a second image the same as the first image is displayed on the viewing screen  20 ′. 
     Compared with a conventional plasma display panel, the plasma display panel of the present invention adopts a pair of viewing screens  20 ,  20 ′, and a single driving system to simultaneously display same images at the two viewing screens  20 ,  20 ′. Therefore, the plasma display panel has a simple structure, a small size, and a low cost. This enables the plasma display panel to be advantageously applied in traffic signal boards, large-scale display boards, surround cinemas, and so on. 
     It is to be understood that the above-described apparatus is intended to illustrate rather than limit the invention. Variations may be made to the apparatus without departing from the spirit of the invention. It is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.