Patent Grant
7852001
This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 10-2006-0048821 filed in Korea on May 30, 2006 the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a plasma display apparatus, and more particularly, to a panel provided in a plasma display apparatus.
2. Description of the Conventional Art
In a plasma display panel, a barrier rib formed between an upper substrate and a lower substrate constitute one unit cell, and an inert gas containing a main discharge gas such as neon (Ne), helium (He), or a mixed gas (Ne+He) of neon and helium and a small amount of xenon is charged within each cell. When a discharge is generated by a high frequency voltage, an inert gas generates vacuum ultraviolet rays and allows a phosphor formed between barrier ribs to emit light, thereby embodying an image. Because such a plasma display panel is formed to be thin and light, it has been spotlighted as a future generation display device.
As shown in
The upper panel 100 is formed in pairs of the scan electrode 102 and the sustain electrode 103 having transparent electrodes 102a and 103a made of transparent Indium Tin Oxide (ITO) and bus electrodes 102b and 103b. The scan electrode 102 and the sustain electrode 103 are covered with an upper dielectric layer 104, and a protective layer 105 is formed on the upper dielectric layer 104.
The lower panel 110 includes barrier ribs 112 for partitioning discharge cells. Further, the plurality of address electrodes 113 is arranged parallel to the barrier ribs 112. R (Red), G (Green), B (Blue) phosphors 114 are coated on the address electrode 113. A lower dielectric layer 115 is formed between the address electrode 113 and the phosphor 114.
The transparent electrodes 102a and 103a constituting a conventional scan electrode 102 or sustain electrode 103 of the plasma display panel are made of expensive ITO. The transparent electrodes 102a and 103a increase a production cost of a plasma display panel. Accordingly, recently, a plasma display panel that can provide satisfactory visible characteristics and driving characteristics to a user while decreasing a production cost is required.
The present invention has been made in an effort to solve the above problems, and one embodiment of the present invention is directed to provide a plasma display apparatus that can reduce a production cost of a panel and improve flicker and luminescent spot generation of a display image by removing a transparent electrode made of ITO in the panel provided in the plasma display apparatus.
According to an aspect of the present invention, there is provided a plasma display apparatus including an upper substrate; a plurality of first electrodes and second electrodes formed in the upper substrate; a lower substrate arranged to be opposite to the upper substrate; and a plurality of third electrodes and barrier ribs formed in the lower substrate, including: a black matrix formed in the upper substrate to be overlapped with the barrier ribs; and a fourth electrode formed on the black matrix to intersect the third electrodes, wherein at least one of the plurality of first and second electrodes is formed in one layer.
According to another aspect of the present invention, there is provided a plasma display apparatus including an upper substrate; a plurality of first electrodes and second electrodes formed in the upper substrate; a lower substrate arranged to be opposite to the upper substrate; and a plurality of third electrodes and barrier ribs formed in the lower substrate, including: a black matrix formed in the upper substrate to be overlapped with the barrier ribs; a fourth electrode formed on the black matrix to intersect the third electrode; a line unit formed to intersect the third electrode; and a protruded unit protruded from the line unit, wherein at least one of the plurality of first and second electrodes is formed in one layer.
The embodiment of the invention will be described in detail with reference to the following drawings in which like numerals refer to like elements.
a to 3c are cross-sectional views schematically illustrating exemplary embodiments of an upper panel structure of a plasma display panel according to the present invention;
a and 17b are cross-sectional views illustrating an eleventh exemplary embodiment of an electrode structure of a plasma display panel according to the present invention.
Hereinafter, a plasma display apparatus according to the present invention will be described in detail with reference to the attached drawings.
As shown in
In the plasma display panel according to the present invention, the sustain electrode pair 11 and 12 is composed of only an opaque metal electrode, unlike a conventional sustain electrode pair shown in
For example, it is preferable that each of the sustain electrodes 11 and 12 according to an exemplary embodiment of the present invention is made of silver, and the silver has a property of photosensitivity. Further, each of the sustain electrode pair 11 and 12 according to an exemplary embodiment of the present invention has a color darker than an upper dielectric layer 13 formed in the upper substrate 10 and has lower light transmittance and high absorbance.
The upper dielectric layer 13 and a protective film 14 are stacked in the upper substrate 10 in which the scan electrode 11 and the sustain electrode 12 are formed in parallel to each other. Charged particles in which a discharge ionization gas (plasma) is generated are stacked in the upper dielectric layer 13. The protective film 14 protects the upper dielectric layer 13 from sputtering of charged particles generated at a gas discharge and increases emission efficiency of secondary electron. Further, magnesium oxide (MgO) is generally used in the protective film 14.
The address electrode 22 is formed to intersect the scan electrode 11 and the sustain electrode 12. Further, a lower dielectric layer 24 and a barrier rib 21 are formed on the lower substrate 20 in which the address electrode 22 is formed.
A phosphor layer 23 is formed on the surface of the lower dielectric layer 24 and the barrier rib 21. In the barrier rib 21, a vertical barrier rib 21a and a horizontal barrier rib 21b are formed in a closed type, and the barrier rib 21 physically partitions a discharge cell, thereby preventing ultraviolet rays and visible light generated by a discharge from being leaked to an adjacent discharge cell.
The phosphor layer 23 emits light by ultraviolet rays generated at a gas discharge and emits any one of red (R), green (G), or blue (B) visible light. An inert mixed gas such as He+Xe, Ne+Xe, and He+Ne+Xe for a discharge is injected in a discharge space provided between the upper/lower substrate 10 and 20 and the barrier rib 21.
The discharge cell may have a symmetrical structure in which a pitch of each of the R, G, and B phosphor layers 23 is equal or an asymmetrical structure in which a pitch thereof is different.
Each of the R, G, and B phosphor layers 23 may have a substantially equal width or different width. When a width of the phosphor layers 23 is different from each other in each of the R, G, and B discharge cells, a width of the phosphor layer 23 in the G or B discharge cell can be thicker than that of the phosphor layer 23 in the R discharge cell.
Further, black matrixes (BM) 15, 16, and 17 for performing a light intercepting function for reducing reflection and a function of improving purity and contrast of the upper substrate 10 by absorbing external light generated from the outside are arranged on the upper substrate 10.
The first black matrix 15 is formed in a position overlapped with the horizontal barrier rib 21b formed in the lower substrate 20 and the second black matrixes 16 and 17 are formed between the upper substrate 10 and the sustain electrodes 11 and 12. As shown in
In a forming process, the black matrix may be physically connected to the black layer by being formed with a black layer at the same time point and may not be physically connected to the black layer by being formed with a black layer at the different time point. Further, when the black matrix and the black layer are formed to be physically connected to each other, the black matrix and the black layer are made of the same material, but when the black matrix and the black layer are formed to be physically separated from each other, the black matrix and the black layer are made of a different material.
Further, a barrier rib structure of the panel shown in
Further, an exemplary embodiment of the present invention may have a barrier rib structure having various shapes as well as a barrier rib structure shown in
In an exemplary embodiment of the present invention, the R, G, and B discharge cells are arranged in the same line, but may be arranged in a different shape. For example, the R, G, and B discharge cells may have delta shape arrangement in which they are arranged in a triangle shape. Further, the discharge cells may have various polygonal shapes such as a quadrangle, a pentagon, and a hexagon.
Further, a pitch of the vertical barrier rib 21a and that of the horizontal barrier rib 21b may be different, and the width of the barrier rib may be a wide width or a narrow width. Further, it is preferable that a width of the horizontal barrier rib 21b is 1.0 to 5.0 times than that of the vertical barrier rib 21a.
A pitch of the R, G, and B discharge cells in a plasma display panel according to an exemplary embodiment of the present invention may be substantially equal and may be different in order to adjust a color temperature in the R, G, and B discharge cells. In this case, entire pitches may be different in each of the R, G, and B discharge cells, but only a pitch of the discharge cell that expresses one color of the R, G, and B discharge cells may be different. For example, a pitch of the R discharge cell is smallest, and a pitch of the G and B discharge cells may be larger than that of the R discharge cell.
Further, the address electrode formed on the lower substrate 20 may have substantially the same pitch or width, but a pitch or a width within the discharge cell may be different from that outside the discharge cell. For example, a pitch or a width within the discharge cell may be wider or thicker than that outside the discharge cell.
It is preferable that a material of the barrier rib 21 does not use lead (Pb) or includes 0.1 wt % of a total weight of a plasma display panel or 1000 PPM (Parts Per Million) or less even though the material of the barrier rib 21 uses lead.
When a total content of a lead component is 1000 PPM or less, a content of lead to a weight of the plasma display panel becomes 1000 PPM or less.
Otherwise, a content of a lead component in a specific element of the plasma display panel may become 1000 PPM or less. For example, a content of a lead component of a barrier rib, a lead component of a dielectric layer, or a lead component in an electrode may become 1000 PPM or less to a weight of each component (a barrier rib, a dielectric layer, and an electrode).
Further, each content of a lead component of entire elements such as a barrier rib, a dielectric layer, an electrode, and a phosphor layer of a plasma display panel may become 1000 PPM or less to a weight of the plasma display panel. The reason why an entire content of a lead component is set to 1000 PPM or less is that the lead component has a bad influence on a human body.
As shown in
If a voltage higher than a predetermined voltage is supplied between the floating electrode 18 and the sustain electrodes 11 and 12 adjacent to the floating electrode 18, a discharge is generated between the two electrodes. By a discharge using the floating electrode 18, electric charges are stacked in the sustain electrodes 11 and 12 adjacent to the floating electrode 18, so that a discharge of the sustain electrodes 11 and 12 is facilitated.
Because an ITO transparent electrode does not exist in a plasma display panel according to the present invention, it is preferable that an interval between the sustain electrode Z and the scan electrode Y constituting one discharge cell is long in order to compensate the decrease of brightness due to nonexistence of the ITO transparent electrode. When an interval between the sustain electrode Z and the scan electrode Y is lengthened, an initial discharge firing voltage increases between the two electrodes.
Accordingly, electric charges are stacked by generating a discharge between the floating electrode 18 and the sustain electrode Z and the scan electrode Y adjacent thereto before generating a sustain discharge between the sustain electrode Z and the scan electrode, whereby a discharge firing voltage for generating a sustain discharge between the sustain electrode Z and the scan electrode Y can be decreased.
It is preferable that the floating electrode 18 is formed to be overlapped with the horizontal barrier rib 21b. Further, it is preferable that a width of the floating electrode 18 is smaller than that of the first black matrix 15 and a difference in a width of the floating electrode 18 and the first black matrix 15 is 10 to 20 μm.
The floating electrode 18 may be floated or grounded in order to prevent a cross-talk between electrodes. Further, the floating electrode 18 may be positioned at the center of the discharge cell.
The structure shown in
a to 3c are cross-sectional views schematically illustrating exemplary embodiments of an upper panel structure of a plasma display panel according to the present invention.
As shown in
It is preferable that a pitch of the floating electrodes 340 and 345 is smaller than that of the first black matrixes 305 and 320. It is preferable that a pitch of the floating electrodes 340 and 345 is smaller by 10 or 20 μm than that of the first black matrixes 305 and 320 and by absorbing external light generated from the outside due to a difference in the width, transmittance can be reduced and contrast of an image can be improved.
If a voltage higher than a predetermined voltage is supplied between the floating electrode 340 and the scan electrode (Y) 330, a discharge is generated between two electrodes 330 and 340 and thus electric charges are stacked in the scan electrode (Y) 330. A discharge firing voltage between the scan electrode (Y) 330 and the sustain electrode 350 decreases by the stacked electric charges.
In the description, a discharge generated between the floating electrode 340 and the scan electrode (Y) 330 is exemplified, but a discharge may be generated by supplying a voltage higher than a predetermined voltage between the floating electrode 340 and the sustain electrode (Z) 335.
It is preferable that a distance between the floating electrodes 340 and 345 and the scan electrode 330 or the sustain electrodes (Z) 335 and 350 is 30 to 60 μm and in this case, an initial discharge is stably generated between the floating electrodes 340 and 345 and the sustain electrodes 330, 335, and 350, whereby electric charges can be stacked in the sustain electrodes 330, 335, and 350.
A method of forming the black matrixes 305, 310, 315, 320, and 325, the sustain electrodes (Z) 350 and 325, the scan electrode (Y) 330, and the floating electrodes 340 and 345 having a structure shown in
b illustrates a case in which two floating electrodes 370, 375, 380, and 385 are formed in each of the first black matrixes 305 and 320 on the upper substrate 300, and descriptions described in
As shown in
It is preferable that a distance between the floating electrodes 370, 375, 355, 385 and sustain electrodes 365, 355, and 360 adjacent thereto is 30 to 60 μm and in this case, an initial discharge between the floating electrodes 370, 375, 355, and 385 and the sustain electrode 365, 355, and 360 adjacent thereto is stably generated, whereby electric charges can be stacked in the sustain electrodes 365, 355, and 360.
As shown in
The electrode arrangement shown in
In
In order to represent a time division gray scale display, a unit frame can be divided into a predetermined number, e.g. 8 subfields SF1 to SF8. Further, each of the subfields SF1 to SF8 is divided into a reset period (not shown), an address period A1 to A8, and a sustain period S1 to S8.
In each of the address periods A1 to A8, a display data signal is supplied to the address electrode X and the corresponding scan pulses are sequentially supplied to each scan electrode Y.
In each of the sustain periods S1 to S8, sustain pulses are alternately supplied to the scan electrode Y and the sustain electrode Z, and in the address periods A1 to A8, a sustain discharge is generated in discharge cells in which wall electric charges are formed.
Brightness of the plasma display panel is in proportional to the number of sustain discharge pulses within sustain discharge periods S1 to S8 that occupy a unit frame. When one frame constituting one image is expressed with 8 subfields and 256 gray scales, the number of different sustain pulses can be allocated in each subfield with a ratio of 1, 2, 4, 8, 16, 32, 64, and 128 in order. In order to obtain brightness having 133 gray scales, a sustain discharge is performed by addressing cells during a subfield 1 period, a subfield 3 period, and a subfield 8 period.
The number of sustain discharges allocated to each subfield can be variably determined by a weight of subfields according to a step of Automatic Power Control (APC). That is, in
Further, in view of gamma characteristics or panel characteristics, the number of sustain discharges allocated to each subfield can be variously changed. For example, a gray scale level allocated to subfield 4 can be decreased from 8 to 6 and a gray scale level allocated to subfield 6 can be increased from 32 to 34.
Referring to
Further, by providing a pre-reset period before a reset period, enough formation of wall charges is assisted, and by applying a waveform for gradually decreasing a voltage value of a scan electrode Y before a reset period and applying a positive voltage to a sustain electrode Z, a pre-reset discharge is generated. It is preferable that in view of a driving margin, the pre-reset period exists only in a first subfield SF1.
In an address period, scan signals are sequentially applied to each of the scan electrode Y and a positive data signal synchronizing with a scan signal applied to the scan electrode Y is applied to the address electrode X. As a wall voltage generated during a reset period is added to a voltage difference between the scan signal and the data signal, an address discharge is generated within a discharge cell and thus wall charges for a sustain discharge are formed.
In a sustain period, a sustain signal is alternately applied to the scan electrode Y and the sustain electrode Z and whenever each sustain signal is applied, a sustain discharge, that is, a display discharge is generated in a discharge cell selected by an address discharge.
Waveforms shown in
A polarity and voltage level of driving signals shown in
It is preferable that the sustain electrodes 202 and 203 within one discharge cell are formed in a plurality of electrode lines. That is, it is preferable that the first sustain electrode 202 is formed in two electrode lines 202a and 202b, and the second sustain electrode 203 is symmetrically arranged to the first sustain electrode 202 based on the center of the discharge cell and is formed in two electrode lines 203a and 203b. It is preferable that the first and second sustain electrodes 202 and 203 are a scan electrode and a sustain electrode, respectively. This is because an aperture ratio and discharge diffusion efficiency are considered by using an opaque sustain electrode pair 202 and 203. That is, in view of an aperture ratio, an electrode line having a narrow pitch is used, and in view of discharge diffusion efficiency, a plurality of electrode lines is used. It is preferable that in view of an aperture ratio and discharge diffusion efficiency at the same time, the number of electrode lines is determined.
It is preferable that each of the scan electrode 11 and the sustain electrode 12 shown in
As shown in
The electrode lines 202a and 202b, 203a, and 203b intersect a discharge cell and are extended in one direction of a plasma display panel. The same driving pulse is supplied to a discharge cell positioned on the same electrode line. The electrode line according to the first embodiment of the present invention has a narrow width to improve an aperture ratio. Further, it is preferable that a plurality of electrode lines 202a and 202b, 203a, and 203b are used to improve discharge diffusion efficiency and in view of an aperture ratio, the number of the electrode lines is determined.
It is preferable that the projection electrodes 202c and 203c are connected to the electrode lines 202a and 203a nearest from the center of the discharge cell within one discharge cell and are projected in a center direction of the discharge cell. When a plasma display panel is driven, the projection electrodes 202c and 203c lower a discharge firing voltage. As the number of the electrode line increases, a distance between the electrode lines 202a and 203a adjacent to the center of the discharge cell is extended. As a distance between the electrode lines 202a and 203a is extended, a discharge firing voltage increases, so that the first embodiment of the present invention include the projection electrodes 202c and 203c connected to each of the electrode lines 202a and 203a. Because a discharge is started even in a low discharge firing voltage between nearly formed projection electrodes 202c and 203c, a discharge firing voltage of the plasma display panel can be lowered. Here, the discharge firing voltage is a voltage level in which a discharge is started when a pulse is supplied to at least one electrode of the sustain electrode pair 202 and 203.
Because such a projection electrode has a very small size, due to a positional difference in a production process, a width W1 of a part substantially connected to the electrode lines 202a and 203a of the projection electrodes 202c and 203c can be formed wider than a width W2 of the tip of the projection electrode. Further, a width of the tip can be widened as needed.
The bridge electrodes 202d and 203d are connected to the electrode lines of each sustain electrode. That is, the first bridge electrode 202d connects the electrode lines 202a and 202b of the first sustain electrode 202 to each other. The second bridge electrode 203d connects electrode lines 203a and 203b of the second sustain electrode 203 to each other. The bridge electrodes 202d and 203d assist a discharge started through a projection electrode to be easily diffused to the electrode lines 202b and 203b far from the center of a discharge cell.
In this way, an electrode structure according to the first embodiment of the present invention can improve an aperture ratio by adjusting the number of electrode lines. Further, a discharge firing voltage can be lowered by forming a projection electrode. Further, discharge diffusion efficiency can be increased by a bridge electrode and an electrode line far from the center of a discharge cell. Light emitting efficiency of a plasma display panel can be entirely improved. That is, because brightness of the plasma display panel can be equal to or brighter than that of a conventional plasma display panel, an ITO electrode cannot be used.
The electrode lines 402a, 402b, 403a, and 403b intersect the discharge cell and are extended in one direction of a plasma display panel. The electrode line according to the second embodiment of the present invention has a narrow width in order to improve an aperture ratio. A width W1 of the electrode line has preferably 20 um to 70 um to improve an aperture ratio and smoothly generate a discharge.
As shown in
The first projection electrodes 402c and 403c are connected to the electrode lines 402a and 403a near the center of the discharge cell within one discharge cell and are projected in a center direction of the discharge cell. Preferably, the first projection electrode is positioned at the center of the electrode lines 402a and 403a. The first projection electrodes 402c and 403c is positioned to the center of the electrode line to correspond to each other to more effectively lower a discharge firing voltage of a plasma display panel.
The bridge electrodes 402d and 403d connect electrode lines of each sustain electrode. The bridge electrodes 402d and 403d assist to easily diffuse a discharge started through the projection electrode to the electrode lines 402b and 403b far from the center of the discharge cell. Here, the bridge electrodes 402d and 403d are positioned within a discharge cell, but the bridge electrodes 402d and 403d may be formed on a barrier rib 412 for partitioning a discharge cell as needed.
The second projection electrodes 402e and 403e are connected to the electrode lines 402b and 403b far from the center of the discharge cell within one discharge cell and are projected in a direction opposite to a center direction of the discharge cell. Accordingly, in the second embodiment of an electrode structure of a plasma display panel according to the present invention, a discharge can be diffused to a space between the electrode lines 402b and 403b and the barrier rib 412. That is, light emitting efficiency of a plasma display panel can be improved by increasing discharge diffusion efficiency.
The second projection electrodes 402e and 403e can be extended to the barrier rib 412 for partitioning a discharge cell. Further, if an aperture ratio is fully compensated from another part, the second projection electrodes 402e and 403e can be partly extended on the barrier rib 412 in order to further improve discharge diffusion efficiency. In the second exemplary embodiment of the present invention, it is preferable to uniformly diffuse a discharge in a surrounding part of a discharge cell by positioning the second projection electrodes 402e and 403e at a mid point of the electrode lines 402b and 403b.
Descriptions described in
As shown in
An area of a sustain electrode in the center of a discharge cell is increased by forming two first projection electrodes in each of the sustain electrode. Accordingly, before a discharge starts, many space charges are formed within a discharge cell and thus a discharge firing voltage is further lowered and a discharge speed becomes fast. Further, after a discharge is started, a wall charge amount increases and thus brightness increases, whereby a discharge is uniformly diffused in an entire discharge cell.
Descriptions described in
As shown in
The first projection electrodes 702c and 703c are connected to the electrode lines 402a and 403a near the center of a discharge cell within one discharge cell and are projected in a center direction of a discharge cell. Preferably, any one of the first projection electrodes is formed in a mid point of the electrode lines and the remaining two first projection electrodes are formed to be symmetrical to each other based on a mid point of the electrode line. By forming three first projection electrodes in each of the sustain electrode, a discharge firing voltage becomes much lower than that of
As described above, by increasing the number of the first projection electrode, an area of a sustain electrode increases from the center of a discharge cell, so that a discharge firing voltage is lowered and brightness increases. In the center of the discharge cell, the strongest discharge is generated and the brightest discharge light is emitted. That is, it is preferable that as the number of the first projection electrode increases, light emitted from the center of the discharge cell is intercepted and thus the emitted light is remarkably decreased and a structure of a sustain electrode is designed by selecting the best number in view of a discharge firing voltage and brightness efficiency at the same time.
Intervals c1, c2, and c3 between four electrode lines for constituting each sustain electrode can be equal to or different from each other, and widths d1, d2, d3, and d4 of the electrode lines can be also equal to or different from each other.
Each of bridge electrodes 1020, 1030, 1040, 1050, 1060, and 1070 connects two electrode lines. The bridge electrodes 1020, 1030, 1040, 1050, 1060, and 1070 allow a started discharge to easily diffuse to an electrode line far from the center of a discharge cell. As shown in
a and 17b are cross-sectional views illustrating an eleventh exemplary embodiment of an electrode structure of a plasma display panel according to the present invention, where first projection electrodes 1420a, 1420b, 1430a, and 1430b projected in the center direction of the discharge cell and second projection electrodes 1440, 1450, 1460, and 1470 projected in a center direction or an opposite direction of the discharge cell are formed in each of electrode lines 1400 and 1410.
As shown in
In a panel provided in a plasma display apparatus according to the present invention having the described configuration, a production cost of a plasma display panel can be reduced by removing a transparent electrode consisting of ITO, a discharge firing voltage can be lowered and discharge diffusion efficiency can be improved within a discharge cell by forming projection electrodes projected in a center direction or an opposite direction of a discharge cell from a scan electrode or sustain electrode line. Further, a discharge can be generated between a floating electrode and a sustain electrode by forming a floating electrode on a black matrix formed to be overlapped in a barrier rib, whereby an initial discharge firing voltage of a sustain discharge between sustain electrodes can be lowered.
The embodiment of the invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
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| 20070279321 A1 | Dec 2007 | US |
