Plasma display panel having sustain electrode arrangement

A plasma display panel. The plasma display panel includes a first substrate made of a transparent material, a second substrate opposite to the first substrate, a first barrier rib being arranged between the first substrate and the second substrate, defining discharge cells together with the first and second substrates, and being made of a dielectric material, upper discharge electrodes being arranged within the first barrier rib and surrounding the discharge cells, lower discharge electrodes being arranged within the first barrier rib, separated from the upper discharge electrodes by a predetermined gap, and respectively being vertically symmetrical with the upper discharge electrodes, and a phosphor layer being arranged in the discharge cells.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for PLASMA DISPLAY PANEL earlier filed in the Korean Intellectual Property Office on 1 May 2004 and thereby duly assigned Serial No. 2004-30840.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a design for a plasma display panel (PDP) capable of realizing an image using a gas discharge.

2. Description of the Related Art

A plasma display panel (PDP) has a large screen and excellent characteristics such as high picture-quality, ultra-slim size, light-weight, and wide viewing angle. The PDP can be manufactured in a simpler manner than other flat panel display devices, and the size of the PDP can be easily increased. Thus, the PDP has been important as a next-generation flat panel display device.

PDPs are categorized into DC PDPs, AC PDPs, and hybrid PDPs depending on an applied discharge voltage. PDPs are also categorized into discharge PDPs and surface discharge PDPs depending on a discharge structure. Recently, the AC PDP having an AC, three-electrode, surface-discharge structure has been widely used.

However, PDPs suffer from the problem in that the visible light must travel through a front substrate to be seen by the viewer. Because the electrodes, a dielectric layer and a protective layer are found in the front substrate, a large percentage of the visible light gets absorbed before it can be seen. As a result, the emission efficiency is low. Also, when displaying an image for a long time, the ions in the plasma tend to sputter the phosphor layers, etching in a permanent image into the display. What is needed is an improved design for a PDP that improves on emission efficiency and reduces the image burn in effect.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an improved design for a PDP.

It is also an object of the present invention to provide a design for a PDP that improves on the emission efficiency.

It is further an object of the present invention to provide a design for a PDP that results in less image burn in.

It is yet another object of the present invention to provide a design for a PDP that improves discharge stability.

These and other objects may be achieved by a plasma display panel that includes a first substrate made of a transparent material, a second substrate opposite to the first substrate, a first barrier rib being located between the first substrate and the second substrate defining discharge cells together with the first and second substrates, and being made of a dielectric material, upper discharge electrodes being located in the first barrier rib and surrounding the discharge cells, lower discharge electrodes being located in the first barrier rib, separated from the upper discharge electrodes by a predetermined gap, and respectively being vertically symmetrical with the upper discharge electrodes, and a phosphor layer located in the discharge cells.

The upper discharge electrodes may include upper discharge portions surrounding each of the discharge cells and upper connection portions connecting the upper discharge portions to one another, and the lower discharge electrodes may include lower discharge portions surrounding each of the discharge cells and respectivelybeing vertically symmetrical with the upper discharge portions and lower connection portions connecting the lower discharge portions to one another. The upper discharge electrodes may extend in one direction, and the lower discharge electrodes may extend along a direction perpendicular to the direction in which the upper discharge electrodes extend.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the figures,FIG. 1illustrates an AC, three-electrode, surface-discharge PDP10. The PDP10ofFIG. 1includes a first substrate11and a second substrate21opposite the first substrate11. Common electrodes12and scan electrodes13forming a discharge gap with the common electrodes12are formed on a lower surface of the first substrate11. The common electrodes12and the scan electrodes13are buried by a first dielectric layer14. A protective layer15is formed on a lower surface of the first dielectric layer14.

Address electrodes22are formed on an upper surface of the second substrate21to overlap with the common electrodes12and the scan electrodes13. The address electrodes are buried by a second dielectric layer23. Barrier walls24are formed on an upper side of the second dielectric layer23to be separated from one another by a predetermined gap so that discharge spaces25are partitioned off. A phosphor layer26is formed in each of the discharge spaces25, and a discharge gas is sealed in the discharge spaces25.

In the discharge spaces25of PDP10, ultraviolet rays are emitted from plasma generated by discharge. These ultraviolet rays excite the phosphor layer26, and visible light is emitted from the excited phosphor layer26so that a visible image is displayed.

However, due to a structure in which the electrodes12and13, the first dielectric layer14and the protective layer15are sequentially formed on the lower surface of the first substrate11, approximately 40% visible light emitted from the phosphor layer26is absorbed, which prevents improvement of the emission efficiency. Furthermore, when displaying the same image for a long time, charged particles of the discharge gas ion-sputter the phosphor layer26by an electric field, which results in the formation of a permanent image forming and thus reducing the life-span of the PDP.

Turning now toFIGS. 2 through 5,FIGS. 2 through 5show a plasma display panel (PDP)100according to an embodiment of the present invention. Referring toFIG. 2, a PDP100includes a first substrate111and a second substrate121opposite to the first substrate111. The first substrate111and the second substrate121are made of a transparent material such as glass. In particular, since an image is displayed through the first substrate111, preferably, the first substrate111has a high transmissivity.

A first barrier rib112and a second barrier rib122are formed between the first substrate111and the second substrate121in the form of a predetermined pattern. In other words, as shown inFIG. 2, the first barrier rib112and the second barrier rib122are closed-type barrier ribs having a matrix shape of rectangular cross-sections. A lower side of the first barrier rib112corresponds to an upper side of the second barrier rib122so that a space defined by the first barrier rib112corresponds to a space defined by the second barrier rib122.

However, the first barrier rib112and the second barrier rib122may be barrier ribs having a variety of patterns, for example, closed-type barrier ribs such as waffle or delta, or closed-type barrier ribs having cross-sections of circular shapes or elliptical shapes or polygonal shapes such as triangular or pentagonal shapes as well as rectangular shapes. In addition, the first barrier rib112may be a closed-type barrier rib, and the second barrier rib122may be an open-type barrier rib such as stripes.

The first barrier rib112and the second barrier rib122divide the space between the two substrates into a plurality of discharge cells. Each discharge cell114corresponds to either a red subpixel, a green subpixel, and a blue subpixel, each constituting a unit pixel, so as to realize a color image, together with the first and second substrates111and121. The barrier ribs112and122also serve to prevent discharge errors caused by optical cross-talk between the discharge cells114. As shown inFIG. 2, the first barrier rib112and the second barrier rib122may be separate elements or formed of the same material and a single body.

A phosphor layer123is excited by ultraviolet rays generated during a sustain-discharge causing visible light to be emitted. The phosphor layer123is located in each discharge cell114. As shown inFIG. 2, the phosphor layer123is formed in a space defined by the second barrier rib122, that is, on an upper surface of the second substrate121and on a side surface of the second barrier rib122.

The phosphor layer123includes phosphor, which is excited by ultraviolet rays generated during a discharge. When excited, the phosphor layer123emits red, green, and blue visible light depending on the color of phosphor layer deposited in the discharge cell. For example, a red phosphor layer formed in a discharge cell corresponding to a red subpixel includes phosphor such as Y(V,P)O4:Eu, a green phosphor layer formed in a discharge cell corresponding to a green subpixel includes phosphor such as Zn2SiO4:Mn and YBO3:Tb, and a blue phosphor layer formed in a discharge cell corresponding to a blue subpixel includes phosphor such as BAM:Eu.

The phosphor layer123is formed in the space defined by the second barrier rib122, and thus is separated by a gap from a main area of the first barrier rib112where a plasma discharge occurs. By designing the PDP with the plasma discharge area separate from where the phosphor layer is located, the phosphor layer123can be prevented from being ion-sputtered by charged particles of the plasma. This results in an extended life-span of the PDP100and prevents the formation of a permanent image, even when the same image is realized for a long time.

A discharge gas is sealed in the discharge cell114in which the phosphor layer123is located. Xe, Ne, or the like, and a mixed gas thereof may be used as the discharge gas.

Meanwhile, upper discharge electrodes131and lower discharge electrodes141are located12within the first barrier rib112between the two substrates. First barrier rib112partitions off the discharge cells114together with the second barrier rib122, in a vertical direction. The upper discharge electrodes131and the lower discharge electrodes141overlap each other and cause a discharge in the discharge cells114. Here, the upper discharge electrodes131are located on an upper side of first barrier rib112close to the first substrate111, and the lower discharge electrodes141are located on a lower side of the first barrier rib112and are closer to the second substrate121than the upper discharge electrodes131. The upper discharge electrodes131and the lower discharge electrodes141, respectively, may be made of a conductive metal such as aluminum, copper, or silver. Since the metallic electrodes have a lower resistance than electrodes made of indium tin oxide (ITO), a discharge response speed can be faster than PDPs that use ITO electrodes.

The first barrier rib112, formed around both the upper discharge electrodes131and the lower discharge electrodes141, is made of a dielectric material. By having the first barrier rib112made out of a dielectric material, electricity can be prevented from flowing directly between the upper discharge electrodes131and the lower discharge electrodes141. Also, by using a dielectric material for the first barrier rib112, the upper discharge electrodes131and the lower discharge electrodes141can be prevented from being damaged by direct collision with charged particles of the plasma. Also, by forming the first barrier ribs112of a dielectric material, charged particles can be induced so that wall charges can easily accumulate on the first barrier ribs112. The dielectric material used in forming the first barrier rib112may be PbO, B2O3, or SiO2.

An MgO layer113having a predetermined thickness is further formed on a side surface of the first barrier rib112. As such, owing to the MgO layer113, the charged particles generated during a discharge can be prevented from directly colliding with the first barrier rib112. Thus, the first barrier rib112can be prevented from being damaged by ion sputtering of the charged particles generated in the plasma. In addition, when the charged particles collide with the MgO layer113, secondary electrons, which contribute to a discharge, can be emitted from the MgO layer113so that low driving voltage can be performed and an emission efficiency can be increased.

The upper discharge electrodes131and the lower discharge electrodes141, which are located in the first barrier rib112in the above manner, will now be described in greater detail. The upper discharge electrodes131are located in an upper side portion of the first barrier rib112and are separated from each other by a predetermined gap and extend in one direction. As shown inFIG. 2, one upper discharge electrode131surrounds four sides of each discharge cell114arranged along the direction in which the upper discharge electrodes131extend. In other words, the upper discharge electrodes131arranged in one line includes upper discharge portions132which surround four sides of each discharge cell114and contribute to a discharge, and upper connection portions133which connect together the upper discharge portions132.

In this case, the upper discharge portions132are formed to have a predetermined width in the form of a rectangular band (e.g. a rectangular frame or rectangular rim), respectively located in the first barrier rib112and thus surround four sides of each discharge cell114. In addition, preferably, the upper connection portions133connecting together the upper discharge portions132are formed to have a minimum width, so as to minimize an effect on a discharge. The width of each upper connection portion133is approximately the same as the width of each upper discharge portion132, but the width of the upper connection portion133may be smaller than the width of the upper discharge portion132.

The upper discharge electrodes131are separated from one another by a predetermined gap along a direction perpendicular to the direction in which the upper discharge electrodes131extend. As such, the spaces between the upper discharge portions132are separated from one another by a predetermined gap. The separated portions of the upper discharge portions132form one group and are located together in one first barrier rib112formed along the direction in which the upper discharge electrodes131extend.

The lower discharge electrodes141located below the upper discharge electrodes131are separated from one another by a predetermined gap and respectively extend in a direction perpendicular to the upper discharge electrodes131. As shown inFIG. 2, the lower discharge electrodes141, like the upper discharge electrodes131, have a structure in which one lower discharge electrode141surrounds four sides of each discharge cell114arranged along the direction in which the lower discharge electrodes141extend. As such, the lower discharge electrodes141arranged in one line includes lower discharge portions142which surround four sides of each discharge cell114and contribute to a discharge, and lower connection portions143which connect together the lower discharge portions142.

In this case, the lower discharge portions142are formed to a predetermined width in the form of a rectangular band, respectively located in the first barrier rib112and thus surround four sides of each discharge cell114. Like in the upper connection portions133, preferably, the width of each lower connection portion143is approximately the same as the width of each lower discharge portion142, but the width of the lower connection portion143may instead be smaller than the width of the lower discharge portion142.

The lower discharge electrodes141are separated from one another by a predetermined gap along a direction perpendicular to the direction in which the lower discharge electrodes141extend. The separated portions of the lower discharge portions142form one group and are located together in one first barrier rib112formed along the direction in which the lower discharge electrodes141extend.

As illustrated inFIGS. 3 through 5, in the upper discharge electrodes131and the lower discharge electrodes141having the above structure, spaces between the upper discharge portion132and the lower discharge portion142located in each discharge cell114are vertically symmetrical with one another. Vertically symmetrical means the portions surrounding each of the discharge cells of the lower discharge electrode141are respectively symmetrical to the portions surrounding each of the discharge cells of the upper discharge electrode131with respect to the horizontal plane. Here, process errors generally occur in a process of manufacturing the upper discharge portions132and the lower discharge portions142. Thus, only when the upper discharge portions132and the lower discharge portions142are manufactured within a predetermined range of errors, can it be regarded that the upper discharge portions132and the lower discharge portions142are symmetrical with one another.

As illustrated inFIG. 3, the upper discharge portions132and the lower discharge portions142are formed to a width in which they are vertically symmetrical with one another. A distance w1between the upper discharge electrodes131is the same as a distance w4between the lower discharge portions142, which are separated from one another and between which the lower connection portions143are located. In addition, a distance w3between the lower discharge electrodes141is the same as a distance w2between the upper discharge portions132, which are separated from one another and between which the upper connection portions133are located.

Turning now toFIG. 4,FIG. 4is a cross section of the PDP100ofFIG. 2taken allong IV—IV. As shown inFIG. 4, the width and height of the upper discharge portion132are the same as those of the lower discharge portion142. In addition, a distance w2between the upper discharge portions132is the same as a distance w3between the lower discharge portions142, as described above, so that the spaces between the upper discharge portions132and the lower discharge portions142are symmetrical with one another based on a transverse axis indicated by a horizontal dotted line inFIG. 4.

Turning now toFIG. 5,FIG. 5is a cross section of PDP100ofFIG. 2taken along line V—V. As illustrated inFIG. 5, the width and height of the upper discharge portion132are the same as the width and height respectively of the lower discharge portion142. In addition, a distance w1between the upper discharge portions132is the same as a distance w4between the lower discharge portions142, as described above, so that the spaces between the upper discharge portions132and the lower discharge portions142are symmetrical with one another based on a transverse axis indicated by a horizontal dotted line inFIG. 5.

Thus, any one of the upper discharge electrode131and the lower discharge electrode141having the above structure acts as an address and sustain electrode, and the other one acts as a scan and sustain electrode. For example, when the upper discharge electrode131acts as the address and sustain electrode and the lower discharge electrode141acts as the scan and sustain electrode, if an address voltage is applied to the upper discharge electrode131and a scan voltage is applied to the lower discharge electrode141, an address discharge occurs in the discharge cell114corresponding to a cross point between the upper discharge electrode131and the lower discharge electrode141. After the address discharge occurs, if a sustain voltage is alternately applied between the upper discharge electrode131and the lower discharge electrode141, the charged particles move in a vertical direction and a sustain discharge occurs.

In this discharge, the spaces between the upper discharge electrodes131and the lower discharge electrodes141are symmetrical with one another based on the transverse axis so that a stable electric field can be formed. Thus, a discharge can be stably performed in a discharge mechanism in which a discharge starts from a discharge gap and occurs diffusely in all of the discharge cells114along a discharge electrode.

As shown inFIG. 4, the sustain discharge that occurs between the upper discharge electrodes131and the lower discharge electrodes141having the above structure is essentially concentrated on an upper side of the discharge cell114and on all sides by which the discharge cell114is defined in a vertical direction. In addition, the sustain discharge that has occurred on all sides of the discharge cell114occurs gradually on a central side of the discharge cell114.

Thus, a discharge area becomes larger than that of the PDP10ofFIG. 1. The size of an area in which a sustain discharge occurs is increased, and space charges in a discharge cell that are ordinarily not used can contribute to emission in the PDP100. As such, the amount of plasma generated during a discharge can be increased so that low-voltage driving can be achieved. Meanwhile, ultraviolet rays are emitted from a discharge gas by the sustain discharge and a phosphor layer located in the discharge cell is excited by the ultraviolet rays so that visible light can be generated from the excited phosphor layer and a visible image can then be realized.

As described above, the PDP according to the present invention has the following advantages. First, the upper discharge electrodes and the lower discharge electrodes are vertically symmetrical with respect to one another and are both located in the first barrier rib allowing for a stable electric field to form. As such, a discharge stability can be guaranteed. Second, since electrodes and dielectric layers are not on or in the first substrate through which visible light must pass, an aperture ratio becomes higher resulting in improved visible light transmission characteristics of the first substrate. In addition, since a discharge occurs on all sides of the discharge cell, a discharge area is remarkably enlarged such that low-voltage driving can be achieved. Third, since the phosphor layer located in a lower portion of the discharge cell is separated by a large gap from a main area in which a sustain discharge occurs, phosphor layer is less apt to be ion-sputtered by the plasma resulting in a longer life-span for the PDP.