Patent Grant
7679287
This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 10-2006-0055475 filed in Korea on Jun. 20, 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 to a plasma display apparatus.
2. Description of the Background Art
In a plasma display panel, a barrier rib formed between an upper substrate and a lower substrate forms one unitary cell. Main discharge gas such as neon (Ne), helium (He) or a mixture (He+Ne) of neon and helium and inert gas containing a small amount of xenon (Xe) are filled in each cell. When a discharge is induced using a high frequency voltage, the inert gas generates vacuum ultraviolet rays and excites phosphors provided between the barrier ribs, thereby embodying an image. The plasma display panel is attracting attention as a next generation display apparatus due to its slimness and lightweightness.
As shown in
The upper panel 100 includes the scan electrode 102 and the sustain electrode 103 having including transparent electrodes 102a and 103a formed of transparent indium-tin-oxide (ITO) and bus electrodes 102b and 103b formed of metal. The scan electrode 102 and the sustain electrode 103 are covered with an upper dielectric layer 104. A protective layer 105 is formed on the upper dielectric layer 104.
The lower panel 110 includes a barrier rib 112 for partitioning a discharge cell. A plurality of address electrodes 113 is arranged in parallel with the barrier rib 112. Red (R), green (G), and blue (B) 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 the scan electrode 102 or the sustain electrode 103 of the plasma display panel are formed of expensive ITO. The transparent electrodes 102a and 103a cause an increase of a manufacturing cost of the plasma display panel. Accordingly, a great attention is drawn to manufacturing a plasma display panel reducing a manufacture cost and guaranteeing a visual characteristic and a driving characteristic enough for user's viewing.
Accordingly, the present invention is to solve at least the problems and disadvantages of the background art.
The present invention is to provide a plasma display apparatus from which a transparent ITO electrode is eliminated, thereby reducing a manufacturing cost of a plasma display panel, and improving flickering of a display image and generation of a bright defect.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a plasma display apparatus including an upper substrate, a plurality of first electrodes and second electrodes formed over the upper substrate, a lower substrate disposed facing the upper substrate, and a plurality of third electrodes formed over the lower substrate.
At least one of the plurality of first electrodes and second electrodes may be formed as one layer, and the first electrodes or the second electrodes may be sequentially formed in at least one portion.
In another aspect of the present invention, there is provided a plasma display apparatus in which at least one of a plurality of first electrodes and second electrodes is formed as one layer, and at least one of a plurality of third electrodes is up/down separated.
In a further another aspect of the present invention, there is provided a plasma display apparatus in which at least one of the plurality of first electrodes and second electrodes is formed as one layer, and the first electrodes or the second electrodes are sequentially formed in at least one portion, and in which at least two discharge cells emitting lights of colors different from each other among a plurality of discharge cells are different in pitch from each other.
The invention will be described in detail with reference to the following drawings in which like numerals refer to like elements.
Preferred embodiments of the present invention will be described in a more detailed manner with reference to the drawings.
Referring to
The upper panel 200 includes the sustain electrode pair 202 and 203 formed on an upper substrate 201 by pair. The sustain electrode pair 202 and 203 is classified into a scan electrode 202 and a sustain electrode 203 depending on its function. The sustain electrode pair 202 and 203 is covered with an upper dielectric layer 204 for limiting a discharge current and insulating between the electrode pair. A protective layer 205 is formed on the upper dielectric layer 204. The protective layer 205 protects the upper dielectric layer 204 from sputtering of charged particles generated at the time of gas discharge, to enhance an emission efficiency of secondary electrons.
The lower panel 210 includes the barrier rib 212a and 212b for partitioning a plurality of discharge spaces, that is, discharge cells. The address electrode 213 is arranged in the direction of intersecting with the sustain electrode pair 202 and 203. A phosphor layer 214 is coated on the lower dielectric layer 215 and the barrier rib 212a and 212b. The phosphor layer 214 is excited by ultraviolet rays generated in the gas discharge, and generates visible rays.
The barrier rib 212a and 212b includes a vertical barrier rib 212a formed in parallel with the address electrode 213, and a horizontal barrier rib 212b formed in the direction of intersecting with the address electrode 213. The barrier rib 212a and 212b physically distinguishes the discharge cells, and prevents the ultraviolet rays and the visible rays generated by the discharge from leaking to an adjacent discharge cell.
In the plasma display panel according to an exemplary embodiment of the present invention, the sustain electrode pair 202 and 203 are formed of only opaque metal unlike a conventional sustain electrode pair 102 and 103 shown in
For example, in an exemplary embodiment of the present invention, it is desirable that each of the sustain electrode pair 202 and 203 is formed of silver (Ag) having a photosensitive property. In an exemplary embodiment of the present invention, it is desirable that each of the sustain electrode pair 202 and 203 has a property of darker color and lower light transmission than those of the upper dielectric layer 204 formed on the upper substrate 201.
It is desirable that electrode lines 202a, 202b, and 203a, 203b have thicknesses of about 2 μm to 8 μm. The electrode lines 202a, 202b, and 203a, 203b having thicknesses of the above range can provide a resistance range and an aperture ratio making a normal operation of the plasma display panel possible. Thus, the electrode lines can be prevented from blocking lights reflected and coming out from a front surface of the plasma display apparatus, and decreasing a luminance. A capacitance of the plasma display panel does not greatly increase. It is desirable that the electrode lines 202a, 202b, and 203a, 203b have resistances of about 50Ω to 65Ω, having thicknesses of about 2 μm to 8 μm.
The respective red (R), green (G), and blue (B) phosphor layers 214 can be equal to or different from each other in width. When the phosphor layers 214 of the R, G, B discharge cells are different from each other in width, the phosphor layer 214 of the G or B discharge cell can is greater in width than the phosphor layer 214 of the R discharge cell.
As shown in
This considers the aperture ratio and a discharge diffusion efficiency according to the use of the opaque sustain electrode pair 202 and 203. In other words, the first and second sustain electrodes 202 and 203 use the electrode lines of narrower widths considering the aperture ratio, and use the electrode lines in plural considering the discharge diffusion efficiency. It is desirable that the number of the electrode lines is decided, considering the aperture ratio and the discharge diffusion efficiency at the same time.
Each of the electrode lines 202a, 202b, and 203a, 203b can be formed on a predetermined black layer (not shown), not in direct contact with the upper substrate 201. In other words, the black layer can be formed between the upper substrate 201 and the respective electrode lines 202a, 202b, and 203a, 203b, thereby improving a discoloration phenomenon of the upper substrate 201, which is caused by a direct contact between the upper substrate 201 and the respective electrode lines 202a, 202b, and 203a, 203b.
The structure of the plasma display panel of
In formation, the black matrix can be formed together with the black layer at the same time and can physically connect with the black layer, or can be formed at a different time and cannot physically connect with the black layer. Physically connected and formed, the black matrix and the black layer are formed using the same material. However, physically separated and formed, they can be formed using different materials.
A barrier rib structure of the plasma display panel shown in
In an exemplary embodiment of the present invention, it is possible to provide a barrier rib structure having a variety of shapes in addition to the barrier rib structure of
In an exemplary embodiment of the present invention, it is shown to arrange the respective R, G, B discharge cells on the same line, but it is also possible to arrange them in a different shape. For example, it is also possible to provide a delta shape arrangement in which the R, G, B discharge cells are arranged in a triangle shape. It is possible to provide the discharge cell in a rectangular shape, a pentagonal shape, and a hexagonal shape.
A width of the vertical barrier rib 212a and a width of the horizontal barrier rib 212b can be different. The width of the barrier rib can be a top width or a bottom width. It is desirable that the width of the horizontal barrier rib 212b is about one to five times of the width of the vertical barrier rib 212a.
In the plasma display panel according to an exemplary embodiment of the present invention, the R, G, B discharge cells can have substantially the same pitch. However, they can also have different pitches to adapt a color temperature adapted in the R, G, and B discharge cells. The R, G, B discharge cells can all have different pitches, but only the discharge cell expressing one color among the R, G, B discharge cells can have a different pitch. For example, it is possible that the R discharge cell have the smallest pitch, and the G and B discharge cells have greater pitches than the R discharge cell.
The address electrode formed on the lower substrate 211 can be substantially constant in width or thickness. However, a width or thickness of the address electrode within the discharge cell can be different from that of the outside of the discharge cell. For example, its width or thickness within the discharge cell can be greater than that of the outside of the discharge cell.
It is desirable that the barrier rib 212a and 212b does not use lead (Pb), or contains, though any, less lead (Pb) of 0.1 weight % or less of a total weight of the plasma display panel, or 1000 parts per million (PPM) or less.
When a total percentage of a lead component is 1000 PPM or less, a lead percentage versus the weight of the plasma display panel can be 1000 PPM or less.
Alternately, it is also possible to provide a percentage of the lead component of a specific constituent element of the plasma display panel, by 1000 PPM or less. For example, a lead percentage of the barrier rib, a lead percentage of the dielectric layer, or a lead percentage of the electrode versus each weight of the constituent elements (the barrier rib, the dielectric layer, and the electrode) can be 1000 PPM or less.
It is also possible to provide lead percentages of all constituent elements of the barrier rib, the dielectric layer, and the phosphor layer of the plasma display panel versus the weight of the plasma display panel, by 1000 PPM or less. The reason why a total percentage of a lead component is set to 1000 PPM or less as above is that the lead component can have a bad influence on a human body.
In each address period (A1, . . . , A8), a display data signal is supplied to the address electrode (X), and a corresponding scan pulse is sequentially supplied to each scan electrode (Y).
In each sustain period (S1, . . . , S8), a sustain pulse is alternately to the scan electrode (Y) and a sustain electrode (Z), and a sustain discharge is induced in the discharge cells where wall charges are formed in the address period (A1, . . . , A8).
A luminance of the plasma display panel is proportional to the number of sustain discharge pulses within a sustain discharge period (S1, . . . , S8) of the unit frame. In case where one frame forming one image is expressed by eight subfields and 256 gray levels, the number of the sustain charge pulses different from each other can be sequentially assigned in a ratio of 1:2:4:8:16:32:64:128 in each subfield. In order to obtain a luminance of 133 gray levels, the discharge cells are addressed during the subfield 1, the subfield 3, and the subfield 8, and the sustain discharge is performed.
The number of the sustain discharges assigned in each subfield can be variably decided depending on weight values of the subfields based on an automatic power control (APC) step. In other words,
It is possible to variously change the number of the sustain discharge pulses assigned in each subfield in consideration of a gamma characteristic or a panel characteristic. For example, a gray level assigned in the subfield 4 can decrease from 8 to 6, and a gray level assigned in the subfield 6 can increase from 32 to 34.
Each subfield includes a pre reset period for forming positive wall charges on the scan electrodes (Y) and forming negative wall charges on the sustain electrodes (Z); a reset period for initializing the discharge cells of a whole screen using a distribution of the wall charges formed during the pre reset period; an address period for selecting the discharge cell; and a sustain period for sustaining a discharge of the selected discharge cell.
The reset period is comprised of a setup period and a setdown period. In the setup period, a ramp-up waveform is simultaneously supplied to all the scan electrodes, thereby inducing a minute discharge in all the discharge cells and thus, generating the wall charges. In the setdown period, a ramp-down waveform falling at a positive voltage lower than a peak voltage of the ramp-up waveform is simultaneously supplied to all the scan electrodes (Y), thereby inducing an erase discharge in all the discharge cells and thus, erasing unnecessary ones of the wall charges and space charges generated by a setup discharge.
In the address period, a negative scan signal is sequentially supplied to the scan electrode and at the same time, a positive data signal is supplied to the address electrode (X). By a voltage difference between the scan signal and the data signal, and a wall voltage generated during the reset period, the address discharge is induced and the cell is selected. During the setdown period and the address period, a signal sustaining a sustain voltage (Vs) is supplied to the sustain electrode.
In the sustain period, the sustain pulse is alternately supplied to the scan electrode and the sustain electrode, and the sustain discharge is induced between the scan electrode and the sustain electrode in a surface discharge type.
In
As shown in
As shown in
As described above, the scan electrodes (Y1 and Ym) are all arranged in the upper and lower outermosts of the plasma display panel, thereby preventing an abnormal discharge from being caused by accumulated charged particles as the sustain electrode (Z) is disposed in the outermost.
In case where the address electrodes (X1 to Xn) are up/down separated as shown in
In a method for separating the address electrodes (X1 to Xn) at the center of the plasma display panel, it is desirable to separate the address electrodes (X1 to Xn) by the horizontal barrier rib 212b at the center of the plasma display panel, or separate each of the address electrodes (X1 to Xn) at the time of forming the address electrodes. In other words, there is not the dielectric layer on the address electrode separated by the horizontal barrier rib 212b at the center of the plasma display panel whereas, there is the dielectric layer on a separated portion of the address electrode in case where the address electrode is separated at the time of forming the address electrode.
It is desirable that a gap between the address electrodes separated at the center of the plasma display panel is about 70 μm to 220 μm. The separated gap of about 70 μm to 220 μm between the two address electrodes is desirable for improving an erroneous discharge and improving a bright defect. The address electrode can have an angular shape at its terminal of the separated portion, but can have a curved shape to have a predetermined curvature so as to improve the erroneous discharge.
The above description is made for the electrode arrangement of the plasma display panel according to the present invention on the basis of an exemplary structure in which each of the address electrodes (X1 to Xn) is separated into two electrodes. However, each of the address electrodes (X1 to Xn) can be also separated into three or more electrodes.
In the plasma display panel according to an exemplary embodiment of the present invention, one or more dummy cell lines can be formed outside the effective region for displaying a screen. The dummy cell line can be formed in a horizontal direction or in a vertical direction. A dummy electrode having a shape equal to or different from that of the discharge cell formed in the effective region can be formed in a dummy cell, and a predetermined voltage can be supplied to the dummy cell.
It is desirable that the width (b) of the portion of the address electrode (X) intersecting with the scan electrode (Y) or the sustain electrode (Z) is 1.2 times or 1.5 times of the width (a) of the other portions thereof. The above range can improve an efficiency of an address discharge.
As shown in
The electrode lines 202a and 202b, and 203a and 203b cross the discharge cell, and extend in one direction of the plasma display panel. According to the first exemplary embodiment of the present invention, the electrode line is narrowed in width to improve an aperture ratio. A plurality of the electrode lines 202a, 202b, and 203a, 203b is used for improving a discharge diffusion efficiency. It is desirable to decide the number of the electrode lines in consideration of the aperture ratio.
It is desirable that the protrusion electrodes 202c and 203c connect to the electrode lines 202a and 203a closest to the center of the discharge cell within one discharge cell, and protrude in the direction of the center of the discharge cell. The protrusion electrodes 202c and 203c reduce a discharge initiation voltage when the plasma display panel is driven. By a distance (C) between the electrode lines 202a and 203a, the discharge initiation voltage increases and therefore, each of the electrode lines 202a and 203a has the protrusion electrode 202c or 203c connecting thereto in the first exemplary embodiment of the present invention. The discharge is initiated owing to even a low discharge initiation voltage between the protrusion electrodes 202c and 203c provided closely and therefore, the discharge initiation voltage of the plasma display panel can be lowered. The discharge initiation voltage refers to a voltage level where the discharge is initiated when a pulse is supplied to any one of the sustain electrode pair 202 and 203.
Since the protrusion electrodes 202c and 203c are of a very small size, a width (W1) of a protrusion electrode portion connecting with the electrode line 202a or 203a may be substantially greater than a width (W2) of a protrusion electrode end portion by a manufacture tolerance. According to need, it is also possible to provide the width (W2) of the protrusion electrode end portion greater.
The bridge electrodes 202d and 203d connect the two electrode lines 202a, 202b, and 203a, 203b constituting each of the sustain electrodes 202 and 203. The bridge electrodes 202d and 203d help the discharge initiated by the protrusion electrodes 202c and 203c to easily diffuse to the electrode lines 202b and 203b distant away from the center of the discharge cell.
As above, the electrode structure according to the first exemplary embodiment of the present invention can suggest the number of the electrode lines, thereby improving the aperture ratio. The protrusion electrodes 202c and 203c can be formed, thereby lowering the discharge initiation voltage. By the bridge electrodes 202d and 203d and the electrode lines 202b and 203b distant away from the center of the discharge cell, the discharge diffusion efficiency can increase, thereby totally improving a light emission efficiency of the plasma display panel. In other words, the inventive plasma display panel can be equal to or brighter than a conventional plasma display panel and thus, is possible not to use a transparent ITO electrode.
As shown in
The electrode lines 402a, 402b, and 403a, 403b cross the discharge cell, and extend in one direction of the plasma display panel. It is desirable that the sustain electrode line is narrowed in width to improve the aperture ratio according to the second exemplary embodiment of the present invention. It is desirable that the electrode line has a width (W1) of about 20 μm to 70 μm, thereby improving the aperture ratio and smoothly inducing the discharge.
As shown in
The first protrusion electrodes 402c and 403c connect to the electrode lines 402a and 403a closest to the center of the discharge cell within one discharge cell, and protrude in the direction of the center of the discharge cell. It is desirable that the first protrusion electrode is formed at the center of the electrode line 402a or 403a. The first protrusion electrodes 402c and 403c can be formed correspondingly to each other at the centers of the electrode lines 402a and 403a, thereby more effectively lowering the discharge initiation voltage of the plasma display panel.
The bridge electrodes 402d and 403d connect the two electrode lines 402a, 402b, and 403a, 403b constituting each of the sustain electrodes 402 and 403. The bridge electrodes 402d and 403d help the discharge initiated by the protrusion electrodes to easily diffuse to the electrode lines 402b and 403b distant away from the center of the discharge cell. The bridge electrodes 402d and 403d are positioned within the discharge cell, but can be also formed on a barrier rib 412 partitioning the discharge cell according to need.
Accordingly, in the sustain electrode structure of the plasma display panel according to the second exemplary embodiment of the present invention, the discharge can be diffused even to a space between the electrode lines 402b and 403b and the barrier rib 412. Thus, the discharge diffusion efficiency can increase, thereby improving the light emission efficiency of the plasma display panel.
As shown in
In the sustain electrode structure according to the second exemplary embodiment of the present invention, it is desirable that the second protrusion electrodes 402c and 403c are formed on the center of the electrode lines 402b and 403b, thereby uniformly diffusing the discharge to the peripheral part of the discharge cell.
As shown in
The two first protrusion electrodes 602a and 603a are formed at the sustain electrodes 602 and 603, respectively, thereby increasing an electrode area at the center of the discharge cell. Accordingly, before the discharge is initiated, space charges are much formed within the discharge cell, thereby more reducing a discharge initiation voltage and making a discharge speed fast. After the discharge is initiated, an amount of wall charges increases, thereby increasing a luminance and uniformly diffusing the discharge in a whole discharge cell.
It is desirable that intervals (a1 and a2) between the first protrusion electrodes 602a and 603a, that is, intervals (a1 and a2) between two protrusion electrodes in the direction of intersecting with the electrode lines 602 and 603 are about 15 μm to 165 μm. Critical meanings of an upper limit value and a lower limit value of the interval between the protrusion electrodes are the same as those described with reference to
As shown in
The first protrusion electrodes 702a and 703a connect to an electrode line close to a center of a discharge cell, and protrude in the direction of the center of the discharge cell. It is desirable that any one first protrusion electrode is formed at the center of the electrode line, and other two first protrusion electrodes are formed in symmetry with each other on the basis of a middle of the electrode line. The three first protrusion electrodes 702a and 703a are formed at the sustain electrodes 702 and 703, respectively, thereby reducing a discharge initiation voltage more than in
The number of the first protrusion electrodes is increased as above, thereby increasing an electrode area at the center of the discharge cell, lowering the discharge initiation voltage, and increasing the luminance. It should be considered that the strongest discharge is induced and the brightest discharge light is emitted at the center of the discharge cell. In other words, it is desirable that the number of the first protrusion electrodes is optimally selected and the sustain electrode structure is designed, considering, together with the discharge initiation voltage and the luminance efficiency, that the light emitted from the center of the discharge cell is much blocked and remarkably reduced as the number of the first protrusion electrodes increases.
It is desirable that the electrode lines 800a, 800b, 800c, and 810a, 810b, 810c of a sustain electrode pair have thicknesses of about 3 μm to 7 μm. Intervals (a1 and a2) between the three electrode lines constituting each of the sustain electrode can be equal to or different from each other. Even widths (b1, b2, and b3) of the electrode lines can be equal to or different from each other. Critical meanings of an upper limit value and a lower limit value of the thickness of the electrode line is the same as those described with reference to
Intervals (c1, c2, and c3) between the four electrode lines constituting each sustain electrode can be equal to or different from each other. Widths (d1, d2, d3, and d4) of the electrode lines can be equal to or different from each other.
Bridge electrodes 1020, 1030, 1040, 1050, 1060, and 1070 connect two electrode lines, respectively. The bridge electrodes 1020, 1030, 1040, 1050, 1060, and 1070 enable an initiated discharge to easily diffuse to the electrode line distant away from a center of the discharge cell. As shown in
It is desirable that the protrusion electrodes 1220 and 1230 have line widths (W1 and W2) of about 35 μm to 45 μm. In case where the protrusion electrodes 1220 and 1230 have the line widths (W1 and W2) of the above range, an aperture ratio of the plasma display panel can be sufficiently guaranteed. Accordingly, a luminance of an image can be prevented from reducing because lights reflected and coming out from a front surface of a plasma display apparatus is blocked off by the protrusion electrodes.
As shown in
In the above-described plasma display panel of the plasma display apparatus according to the present invention, the transparent electrode formed of ITO can be eliminated, thereby reducing a manufacturing cost of the plasma display panel. The protrusion electrodes protruding from the scan electrode or sustain electrode line in the direction of the center of the discharge or in the opposite direction thereof can be formed, thereby reducing the discharge initiation voltage and enhancing the discharge diffusion efficiency. The address electrode is separated at the center of the plasma display panel and the plasma display panel is divided, thereby stably keeping the discharge and making image data processing smooth in the plasma display panel. The scan electrode or the sustain electrode can be sequentially arranged at the center of the separated plasma display panel, thereby preventing the abnormal discharge from occurring by a concentration of the charges.
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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