Plasma display panel and method of fabricating the same

A plasma display panel that includes a front substrate, a rear substrate positioned in parallel to the front substrate, a plurality of address electrodes between the front and rear substrates, a plurality of display electrodes positioned perpendicularly to the plurality of address electrodes, and a plurality of barrier ribs between the front and rear substrates, the barrier ribs defining a plurality of discharge cells, and wherein each barrier rib includes at least one longitudinal portion positioned at an obtuse angle with respect to the rear substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasma display panel. More particularly, the present invention relates to a plasma display panel having improved structure of discharge cells.

2. Description of the Related Art

In general, a plasma display panel (PDP) refers to a flat display device capable of displaying images using gas discharge phenomenon, thereby providing superior display characteristic, such as high brightness and contrast, lack of residual image, and wide viewing angles.

The conventional PDP may include two substrates with a plurality of discharging electrodes therebetween, i.e., a first substrate having a plurality of pairs of scan and sustain electrodes and a second substrate having a plurality of address electrodes, a plurality of pixel units having phosphorescent layers, and barrier ribs between the two substrates to separate the plurality of phosphorescent layers. When a predetermined amount of electricity is applied to the electrodes, a sustain discharge may be generated to trigger ultraviolet (UV) emission and, thereby, to excite the phosphorescent layers to emit visible light and form images.

More specifically, the barrier ribs of the conventional PDP may define discharge cells therebetween, such that each discharge cell may be formed between a sustain electrode and a scan electrode. Each discharge cell may be coated with a phosphorescent layer emitting red, green, or blue light, such that three adjacent discharge cells having three different colors may form one pixel unit. Accordingly, a matrix of pixel units may be formed between the plurality of address electrodes and the plurality of pairs of sustain and scan electrodes, i.e., between the two substrates, such that one address electrode may overlap with one discharge cell of a pixel unit. The arrangement and structure of pixel units may improve resolution in a PDP. Accordingly, attempts have been made to increase the pixel unit density.

However, increase of pixel unit density may increase the number of required address electrodes in a PDP. An increased number of address electrodes may reduce the distance therebetween and, therefore, increase the capacitance and the power consumption. Additionally, increase of pixel unit density may affect the geometric shape of each discharge cell, e.g., reduce the volumetric capacity of each discharge cell, thereby reducing the deposition area of each phosphorescent layer and, subsequently, deteriorating color tone and luminance of the PDP.

Accordingly, there exists a need to improve the structure of the PDP in order to provide improved pixel unit density, while maintaining a low power consumption and high luminance efficiency.

SUMMARY OF THE INVENTION

The present invention is therefore directed to a plasma display panel which substantially overcomes one or more of the disadvantages of the related art.

It is therefore a feature of an embodiment of the present invention to provide a plasma display panel capable of providing increased pixel unit density, while reducing the number of address electrodes.

It is another feature of an embodiment of the present invention to provide a plasma display panel capable of providing increased pixel unit density, while maintaining low power consumption and high luminance efficiency.

It is yet another feature of an embodiment of the present invention to provide a plasma display panel capable of providing increased pixel unit density, while maintaining sufficient deposition area for phosphorescent layers in each discharge cell.

At least one of the above and other features and advantages of the present invention may be realized by providing a plasma display panel, including a front substrate, a rear substrate positioned in parallel to the front substrate, a plurality of address electrodes between the front and rear substrates, a plurality of display electrodes positioned perpendicularly to the plurality of address electrodes, and a plurality of barrier ribs between the front and rear substrates, such that the barrier ribs may define a plurality of discharge cells, and wherein each barrier rib may include at least one longitudinal portion positioned at an obtuse angle with respect to the rear substrate. The display electrodes may include pairs of scan and sustain electrodes, such that a ratio of the address to scan electrodes may be about 8:3.

The plurality of barrier ribs may be positioned in a direction parallel to a direction of the plurality of address electrodes. Each three discharge cells of the plurality of discharge cells may form one pixel unit. The discharge cells may be arranged in a triangular shape. Two of the three discharge cells may be adjacent to one another along a direction parallel to the direction of the address electrodes. Additionally, the two adjacent discharge cells may overlap with one common address electrode. Further, an extension line of a boundary between the two adjacent discharge cells may pass a center of a third discharge cell of the three discharge cells.

Alternatively, the plurality of barrier ribs may be positioned in a direction perpendicular to a direction of the plurality of address electrodes. Each three discharge cells of the plurality of discharge cells may be arranged in a triangular shape to form one pixel unit, and two of the three discharge cells may be adjacent to one another along a direction parallel to the direction of the barrier ribs. Each pixel unit may be positioned to form a color array, wherein each color array may overlap with one address electrode.

Each discharge cell of the three discharge cells may emit a different color of light. Additionally, each discharge cell may have a first top width and a first bottom width, the first top width being greater than the first bottom width. Further, each discharge cell may have a second top width and a second bottom width, the second top width being smaller than the second bottom width. Each discharge cell may have a hexagonal plane shape.

DETAILED DESCRIPTION OF THE INVENTION

Korean Patent Application No. 10-2005-0112217 filed on Nov. 23, 2005 in the Korean Intellectual Property Office, and entitled: “Plasma Display Panel and Method of Fabricating the Same,” is incorporated by reference herein in its entirety.

It will further be understood that when an element is referred to as being “on” another element or substrate, it can be directly on the other element or substrate, or intervening elements may also be present. Further, it will be understood that when an element is referred to as being “under” another element, it can be directly under, or one or more intervening elements may also be present. In addition, it will also be understood that when an element is referred to as being “between” two elements, it can be the only element between the two elements, or one or more intervening elements may also be present. Like reference numerals refer to like elements throughout.

An exemplary embodiment of a plasma display device (PDP) according to the present invention is more fully described below with reference toFIGS. 1-2. As illustrated inFIGS. 1-2, a PDP, e.g., a delta-type PDP, according to an embodiment of the present invention may include a rear substrate10, a front substrate30, a plurality of pixel units120, a plurality of address electrodes15, a plurality of display electrodes35, and a plurality of barrier ribs23.

The rear substrate10and the front substrate30may be formed parallel to one another and at a predetermined distance from one another, such that additional layers, e.g., electrodes, dielectric layers, protective layers, pixel units and so forth, may be formed therebetween, as will be discussed in more detail below.

Each pixel unit120of the PDP according to an embodiment of the present invention may include three sub-pixels. In particular, as illustrated inFIG. 2, each pixel unit120may include a first sub-pixel120G emitting green (G) visible light, a second sub-pixel120R emitting red (R) visible light, and a third sub-pixel120B emitting blue (B) visible light.

The first, second and third sub-pixels120G,120R and120B of each pixel unit120may be arranged in a triangular structure, i.e., connection of center points O of each respective sub-pixel120R,120G, and120B, as illustrated inFIG. 2, may form a triangle, to form the one pixel unit120. Additionally, each first, second and third sub-pixels120G,120R and120B of each pixel unit120may include a discharge cell18having a hexagonal plane shape. A discharge gas, e.g., xenon (Xe), neon (Ne), or mixtures thereof, may fill each discharge cell18.

Each three discharge cells18corresponding to one pixel unit120may be arranged in two adjacent parallel lines along the y-axis, such that two discharge cells18may be formed in one line and one discharge cell18may be formed in an adjacent parallel line, as illustrated inFIG. 2. Further, each two adjacent pixel units120along the y-axis may have an alternating orientation. In other words, if one pixel unit120has two discharging cells18in a first line and one discharging cell18in a second line, the adjacent pixel unit120may have one discharging cell18in the first line and two discharging cells18in the second line, such that the two adjacent pixel units120may form a uniform structure of two parallel lines along the y-axis. Accordingly, an extension of a boundary line between a pair of adjacent discharge cells18in the first line, e.g., a boundary extension along the x-axis between two discharge cells18of one pixel unit120, may pass a center of a discharge cell18in the second line, e.g., a center O of a third discharge cell18of the same pixel unit120.

In this respect, it should be noted that “lines” may refer to a direction along the y-axis, as illustrated inFIGS. 1-2. This orientation may be parallel to a direction of the address electrodes15. However, other orientations are not excluded from the scope of the present invention. It should further be noted that terminology such as “first” and “second” with respect to lines is employed to distinguish the lines and indicate their sequence.

The plurality of address electrodes15of the PDP according to an embodiment of the present invention may be formed in a stripe-like structure on the rear substrate10. In particular, the plurality of address electrodes15may be parallel to one another and disposed in a direction parallel to the y-axis, as illustrated inFIG. 1. The plurality of address electrodes15may be formed such that each pixel unit120may overlap with two address electrodes15, such that at least two of the sub-pixels120R,120G, and120B of each pixel120may be driven by one common address electrode15.

The display electrodes35of the PDP according to an embodiment of the present invention may include a plurality of pairs of sustain and scan electrodes32and34, respectively, disposed in a same plane on the front substrate30in a direction parallel to the x-axis, as illustrated inFIG. 1. In particular, the plurality of sustain and scan electrodes32and34may be disposed in an alternating pattern, such that each scan electrode34may be positioned between two sustain electrodes32. The alternating pattern of the sustain and scan electrodes32and34may provide a discharge gap therebetween, i.e., a discharge cell18may be formed therebetween. Accordingly, each discharge cell18may be driven by a pair of display electrodes35positioned along the x-axis in one plane and an address electrode15positioned along the y-axis in another plane, such that application of voltage to the scan electrode34and the address electrode15may facilitate selection of the discharge cell18, while application of voltage to the sustain electrode32and the scan electrode34of the selected discharge cell18may facilitate discharge therein.

Each of the sustain and scan electrodes32and34may include a bus electrode32aand34a, respectively, and a transparent electrode32band34b, respectively. In particular, each bus electrode32aand34amay be formed of metal and disposed along a corresponding barrier rib23, i.e., around half a perimeter of each discharge cell18in one line. More specifically, as illustrated inFIGS. 1-2, each bus electrode32aand34amay form a zigzag pattern along the x-axis. For example, as illustrated inFIG. 2, the bus electrode34aof a scan electrode Yn+1may have a horizontal structure between the first sub-pixel120G and the third sub-pixel120B, a half-hexagonal structure surrounding the second sub-pixel120R, and so forth. The bus electrodes32aand34amay have reduced widths, i.e., distances as measured along the y-axis, such that the bus electrodes32aand34amay overlap only with the barrier ribs23to minimize interference with the emission of visible light from the discharge cells18.

Each transparent electrode32band34bmay be formed of a transparent material, e.g., indium-tin-oxide (ITO), and be in contact with the bus electrode32aand34a, respectively, such that each transparent electrode32band34bmay extend across the corresponding bus electrode32aand34a, respectively, to overlap with at least two adjacent discharge cells18along the y-axis. Accordingly, each discharge cell18may overlap with a pair of transparent electrodes32band34b. In particular, the pair of transparent electrodes32band34bdisposed in a respective discharge cell18may be placed across from one another at a predetermined distance, as further illustrated inFIG. 2.

Accordingly, application of voltage to each of the scan electrodes34or sustain electrodes32may trigger voltage in each respective bus electrode32aand34aand respective transparent electrode32band34b, such that each display electrode35may supply voltage to two adjacent discharge cells18positioned along the y-axis, as illustrated inFIG. 2. As such, the alternate arrangement of the scan and sustain electrodes34and32may control operation of a pair of adjacent discharge cells18. Accordingly, a configuration of sixteen pixel units120, i.e., four pixel units in each row and column as illustrated inFIGS. 1-2, may require twelve transparent scan electrodes34bfor proper operation of the PDP. Therefore, a ratio of the number of the transparent scan electrodes34bto pixel units120according to an embodiment of the present invention may be 3:4, i.e., ¾ of the scan electrodes34may correspond to each pixel unit120.

Similarly, since two address electrodes15and ¾ scan electrodes34may correspond to each pixel unit120, i.e., eight address electrodes15and three scan electrodes34may correspond to the sixteen pixel units120illustrated inFIG. 2, the number of the address electrodes15and the number of the scan electrodes34may satisfy the relationship NA:NS=8:3, wherein NA is the number of address electrodes and NS is the number of scan electrodes.

Since only eight address electrodes15may be required to drive sixteen pixel units120in the PDP of the present embodiment, as compared to twelve address electrodes required in a comparable conventional PDP, i.e., a PDP having sixteen pixel units, the PDP of the present embodiment exhibits a reduced number of address electrodes, while maintaining the same number of pixel units120.

The barrier ribs23of the PDP according to an embodiment of the present invention may be disposed between the rear and front substrates10and30to separate the pixel units120and to define the discharge cells18therein. In particular, the barrier ribs23of the present invention will be described in more detail with respect toFIGS. 3-6below.

The barrier ribs23may be formed of a mixture paste containing a main material, a volatile solvent, an additive agent, and a binder by any method known in the art, e.g., sandblasting process, etching process, and so forth. Subsequently, the mixture paste may be deposited on the rear substrate10in hourglass-like structures, as illustrated by the solid line inFIG. 3, to form sidewalls of the barrier ribs23along the direction of the y-axis in order to define respective discharge cells18, i.e., each hourglass structure may correspond to one discharge cell18. In particular, each hourglass structure may be formed to have a first center width d3and a first edge width d4, such that the first center width d3may be smaller than the first edge width d4, as further illustrated inFIG. 3.

Next, the hourglass-like structures may be baked in a baking furnace, such that the mixture paste may contract as the volatile solvent is vaporized. The contraction of the mixture paste along a direction of the x-axis may be greater than its contraction along the y-axis. In particular, as illustrated inFIG. 3, portions p4may contract along a direction illustrated by the arrows, thereby triggering contraction of portions p3, as further illustrated by the arrows. Contraction of the portions p3and p4may trigger contraction of portions p1and p2toward the portion p3, such that center portions of the hourglass structures may expand, e.g., portion A may expand along the x-axis, and transform to have a hexagonal plane shape, as illustrated by the dotted line inFIG. 3.

However, it should be noted that the contraction and expansion of the barrier ribs23structures may occur mainly at upper portions thereof because lower portions of the barrier ribs23may be fixed to the rear substrate10. Accordingly, a bottom portion of each discharge cell18may have the first central and edge widths d3and d4, while an upper portion of each discharge cell18may have a second central width d2and a second edge width d1, wherein the second central width d2may be greater than the second edge width d1. In other words, the upper portion of each discharge cell18may expand to have a hexagonal plane shape, while the bottom portion of each discharge cell18may hardly change, i.e., portions p1and p2that correspond to edges of each discharge cell18may hardly be affected by the contraction during baking.

Therefore, each barrier rib23may include a first longitudinal portion23aand a second longitudinal portion23b, as illustrated inFIG. 4-6. In particular, the first longitudinal portion23amay correspond to a sidewall of the barrier rib23that is adjacent to the center of a respective discharge cell18, and the second longitudinal portion23bmay correspond to a sidewall of the barrier rib23that is adjacent to the edge of the respective discharge cell18. Further, the first longitudinal portion23amay have a trapezoidal cross-section, such that an outer surface231of the first longitudinal portion23amay form an obtuse angle θ with a bottom of the discharge cell18, as illustrated inFIG. 5, due the expansion of an upper portion thereof during baking. On the other hand, the second longitudinal portion23bmay have a rectangular or inverted trapezoidal cross-section that may form a straight or an acute angle with a bottom of the discharge cell18, as illustrated inFIGS. 4 and 6, due to its minor structural changes during baking.

Without intending to be bound by theory, it is believed that the above-described barrier ribs23may be advantageous in providing increased discharge volumetric space in highly integrated structures. In particular, since the upper portion of each discharge cell18may be expanded during baking, the overall volume in the discharge cell18may be increased. Further, the inclined sidewalls of a center part of each discharge cell18, i.e., first longitudinal portions23aforming an obtuse angle with the rear substrate10, may provide increased deposition area for phosphorescent material, thereby increasing color and luminance efficiency.

The PDP according to an embodiment of the present invention may further include phosphorescent layers25. Each phosphorescent layer25may be applied to a respective red, green, and blue sub-pixel120R,120G, and120B to emit a respective red, green, and blue light. In particular, each phosphorescent layer25may be applied to a bottom surface of each discharge cell18and a sidewall of a barrier rib23, such that two adjacent sub-pixel may emit different colors.

Additionally, the PDP according to an embodiment of the present invention may also include a first dielectric layer12. The first dielectric layer12may be formed between the rear substrate10and the barrier ribs23. In particular, the address electrodes15may be positioned between the rear substrate10and the first dielectric layer12, such that the address electrodes15may be separated from the barrier ribs23. The PDP according to an embodiment of the present invention may also include a second dielectric layer (not shown) deposited on the front substrate30to separate the display electrodes35from the barrier ribs23and a passivation layer (not shown) formed of magnesium-oxide (MgO) on the second dielectric layer.

In another embodiment of the present invention, as illustrated inFIG. 7, a PDP may be similar to the PDP described with respect toFIG. 1, with the exception that each of the plurality of pixel units71therein may be arranged to have each of first, second and third sub-pixels71G,71R and71B emit a different color of visible light and positioned to form a color array in each line along the x-axis. In other words, each unit pixel71may be arranged such that respective sub-pixels emitting a same color of visible light may be positioned in a same line along the x-axis. For example, a first column of pixel units71may be arranged such that each pixel unit71may have a sub-pixel71B positioned as a right-most sub-pixel, thereby forming a column of blue light-emitting sub-pixels71B. Accordingly, color arrays of identical light-emitting sub-pixels may be formed and arranged in an alternating pattern, e.g., blue light-emitting column, green light-emitting column, red light-emitting column, and so forth. It should be noted that a corresponding phosphorescent layer, i.e., corresponding color of light-emitting layer, may be applied to each such column.

The color array arrangement of the present embodiment may provide a structure, such that each color array may overlap with one address electrode75, i.e., each column of sub-pixels may overlap with one address electrode75that may be positioned in a direction parallel to the x-axis. However, it should be noted that in the embodiment described with respect toFIG. 7the barrier ribs23may be formed in a direction parallel to the direction of the display electrodes35, i.e., perpendicularly to the address electrode75.

The structure of the PDP described with respect toFIG. 7exhibits the same advantages with respect to improved barrier rib23structure and increased discharge space and efficiency as the PDP described with respect toFIGS. 1-6.