This application claims priority to and the benefit of Korean Patent Application No. 10-2004-0096208 filed in the Korean Intellectual Property Office on Nov. 23, 2004, the entire content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates generally to a plasma display panel, and more particularly, to a plasma display panel that can operate with a low driving voltage and high luminance.
2. Description of the Related Art
Generally, a plasma display panel (PDP) is a display device in which vacuum ultraviolet rays emitted from plasma by gas discharge excite phosphors to generate visible light, thereby creating images. Such a plasma display panel has been spotlighted as a next-generation thin display device since it has high resolution and a large screen.
A conventional plasma display panel generally uses a three-electrode surface-discharge type structure. The three-electrode surface-discharge type structure includes a front substrate having two display electrodes formed thereon and a rear substrate which is spaced from the front substrate at a predetermined distance and has address electrodes formed thereon. The space between both substrates is divided into a plurality of discharge cells by barrier ribs, and a phosphor layer is formed in the discharge cell on the rear substrate. Also, a discharge gas is injected into each discharge cell.
Whether discharge occurs or not determined by the address discharge between the address electrode and one of the display electrodes, and sustain discharge for displaying luminance occurs using the display electrodes located on the same surface. Thus, in a conventional plasma display panel, the address discharge is generated by an opposed discharge, and the sustain discharge is generated by surface discharge.
The distance between the display electrode and the address electrode is greater than the distance between two display electrodes, but the breakdown voltage of the address discharge is lower than that of the display discharge. This is because the address discharge is induced by the opposed discharge and thus has the breakdown voltage lower than that of the sustain discharge induced by the surface discharge. Accordingly, if an improved plasma display panel could induce sustain discharge by opposed discharge it would have higher efficiency than that of the conventional plasma display panel.
On the other hand, the plasma discharge within the plasma display panel is affected by a sheath region and a positive column region. The sheath region is a region that consumes most of the voltage in a non-emitting region surrounding a dielectric layer or an electrode, and the positive column region is a region that can actively generate plasma discharge at a very low voltage. Accordingly, the efficiency of the plasma display panel can be improved by increasing the size of the positive column region. The length of the sheath region is not related to the discharge gap, and the positive column region can be enlarged by enlarging the discharge length. However, if the discharge gap is increased to enlarge the discharge length, the breakdown voltage increases.
Also, the efficiency of the discharge gas charged in each discharge cell improves as the partial pressure of Xe gas increases. However, if the partial pressure of Xe gas increases, the breakdown voltage is reduced.
Accordingly, in the conventional plasma display panel, there is a problem in that a low breakdown voltage and high efficiency cannot be simultaneously achieved.
The present invention provides a plasma display panel that induces a sustain discharge by an opposed discharge to reduce a breakdown voltage and that also enlarges a discharge length to achieve a high luminous efficiency.
According to an aspect of the invention, an improved plasma display panel includes first and second substrates that face each other with a space therebetween. The space is divided into a plurality of discharge cells. Address electrodes extend along a first direction on the first substrate, and phosphor layers are formed in the discharge cells. First electrodes and second electrodes extending along a second direction that intersects the first direction in the space between the first substrate and the second substrate correspond to the discharge cells. The first and second electrodes expand from the first substrate to the second substrate and face each other with an interval therebetween. Each of the address electrodes includes first portions that correspond to a discharge space of each discharge cell and a second portion that electrically connects the first portions along the first electrode. The width of the first portion is different from that of the second portion.
According to another aspect of the invention, a plasma display panel includes first and second substrates that face each other with a space therebetween. The space is divided into a plurality of discharge cells. Address electrodes extend along a first direction on the first substrate, and phosphor layers are formed in the discharge cells. First electrodes extending along a second direction that intersects the first direction in the space between the first substrate and the second substrate. Second electrodes extend along the second direction between a pair of the first electrodes. The first electrodes and the second electrodes expand from the first substrate to the second substrate and face each other with an interval therebetween. Each of the first electrodes has a first portion that is formed along the second direction and a second portion that protrudes from the first portion to the second electrode.
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings.
Preferred embodiments of the present invention will now be described with reference to the drawings.
Referring to
In the discharge cell 38, red, green and blue phosphor layers 19 and 29 for absorbing ultraviolet rays and emitting visible rays are formed along a barrier rib surface and a bottom surface, and discharge gas (for example, a gas mixture containing xenon Xe, neon Ne, etc.) is injected into each discharge cell 38. When electronically charged, the gas forms a plasma that emits ultraviolet rays. These ultraviolet ray impinge the phosphor layers 19 and 29, which emit visible rays of light.
Now, the plasma display panel will be described in detail.
First, on one surface of the rear substrate 10 opposing the front substrate 20, address electrodes 12 are formed along a direction (y axis direction), and a dielectric layer 14 is formed on the entire inner surface of the rear substrate 10 to cover the address electrodes 12. The address electrodes 12 are spaced from each other at predetermined intervals. The address electrodes 12 will be described in detail with reference to
Barrier ribs 16 and 26 for dividing the discharge cell 38 are formed in the space between the first substrate 10 and the second substrate 20. The barrier ribs 16 and 26 include a first barrier rib layer 16 (hereinafter, referred to as “a rear barrier rib”) protruding toward the front substrate 20 adjacent to the rear substrate 10 and a second barrier rib layer 26 (hereinafter referred to as “a front barrier rib”) protruding toward the rear substrate 10 adjacent to the front substrate 20.
The rear barrier rib 16 is formed on the dielectric layer 14 formed on the rear substrate 10. The rear barrier rib 16 includes first barrier rib members 16a arranged in a direction (y axis direction) parallel with the address electrode 12 and second barrier rib members 16b which are formed in a direction (x axis direction) intersecting the barrier rib member 16a, and divides each rear discharge cell 18 into independent discharge spaces on the rear substrate 10.
Also, the front barrier rib 26 includes third barrier rib members 26a having shapes corresponding to those of the first barrier rib members 16a and fourth barrier rib members 26b having shapes corresponding to those of the second barrier rib members 16b. That is, the third barrier rib members 26a and the fourth barrier rib members 26b are formed on the front substrate 20 along the directions which cross each other to form the front discharge cell 28 corresponding to the rear discharge cell 18.
The rear discharge cell 18 divided by the rear barrier rib 16 and the front discharge cell 28 divided by the front barrier rib 26 combine to substantially form a single discharge cell 38.
Although the rear barrier rib 16 and the front barrier rib 26 include the barrier rib members 16a, 16b, 26a, 26b which cross each other in the present embodiment, the present invention is not so limited. That is, barrier ribs having various shapes can be used and are included in the scope of the present invention. Also, although both the rear barrier rib 16 and the front barrier rib 26 are formed in the present embodiment, the present invention is not limited thereto.
A first phosphor layer 19 is formed in the rear discharge cell 18. A second phosphor layer 29 is formed in the front discharge cell 28. The first phosphor layer 19 is formed at the lateral surfaces of the barrier rib members 16a and 16b forming the rear barrier rib 16 and the bottom surface adjacent to the rear substrate 10. The second phosphor layer 29 is formed at the lateral surfaces of the barrier rib members 26a and 26b forming the front barrier rib 26 and the bottom surface adjacent to the front substrate 20.
Each of the first and second phosphor layers 19 and 29 absorbs vacuum ultraviolet rays in the rear discharge cell 18 and the front discharge cell 28 and generates visible light toward the front substrate 20. Because the second phosphor layer 29 transmits visible light, the second phosphor layer 29 can be formed thinner than the first phosphor layer 19 in order to minimize the loss of the vacuum ultraviolet rays.
Since the rear discharge cell 18 formed by the rear barrier rib 16 and the front discharge cell 28 formed by the front barrier rib 26 substantially form one discharge cell 38, the first phosphor layer 19 and the second phosphor layer 29 preferably emit the same visible light by collision of vacuum ultraviolet rays generated by gas discharge.
Forming the phosphor layers 19 and 29 on either sides of the discharge cell 38 improves the luminance of the PDP.
The present invention however, is not limited to this. In another embodiment, a single phosphor layer can be formed on the rear substrate 10 or the front substrate 20, and this is also included in the scope of the present invention.
The first phosphor layer 19 can be formed by forming a dielectric layer (not shown) and the rear barrier rib 16 on the rear substrate 10, and then coating a phosphor on the dielectric layer. The second phosphor layer 29 can be formed by forming a dielectric layer (not shown),and the front barrier rib 26 on the front substrate 20, and then coating a phosphor on the dielectric layer. Alternatively, the second phosphor layer 29 can be formed by forming the front barrier rib 26 on the front substrate 20 and then coating the phosphor thereon without forming a dielectric layer on the front substrate 20 as shown in the drawing.
Also, the first phosphor layer 19 and the second phosphor layer 29 can also be formed by etching the rear substrate 10 and the front substrate 20 to have the shape corresponding to that of the rear discharge cell 18 and front discharge cell 28 and coating the phosphor layers thereon, respectively. In this embodiment, the rear barrier rib and the rear substrate may be integrally formed of the same material, and the front barrier rib and the front substrate may be integrally formed of the same material.
Also, dielectric layers 34 and 35 should be disposed between the rear barrier rib 16 and the front barrier rib 26, so that first electrodes 31 and second electrodes 32 can be formed in the dielectric layers 34 to intersect and extend through dielectric layers 35. Together, the dielectric layers 34 and 35 insulate the electrodes 31 and 32 and store wall charges generated by the discharge.
The first electrodes 31 and the second electrodes 32 may have stripe shapes that extend along a direction intersecting the address electrode 12 at both sides of the discharge cell 38. The first electrodes 31 and the second electrodes 32 may be disposed in parallel between the second barrier rib member 16b and the fourth barrier rib member 26b while intersecting the first barrier rib member 16a and the third barrier rib 26a.
Referring to
In the present embodiment, since the first electrodes 31 and the second electrodes 32 are disposed on the side of the discharge cell 38 having substantially low contribution to the display, the metal electrode having excellent conductivity can be used.
In one embodiment, the first electrode 31 selects the discharge cell 38 which will be turned on when a scan pulse voltage is applied during the address period together with the address electrode 12, and the second electrode 32 participates in the discharge of the sustain period to display an image together with the first electrode 31. However, since the roles of the electrodes can vary with an applied signal voltage, the present invention is not limited to this.
The first electrode 31, the second electrode 32, and the dielectric layers 34 and 35 surrounding the electrodes can be manufactured with a thick film ceramic sheet (TFCS) method. That is, the dielectric layers 34 and intersecting dielectric layers 35 having the first electrode 31 and the second electrode 32 therein can be separately manufactured and then connected between the rear barrier rib 16 and the front barrier rib 26.
Also, a MgO protecting film 36 can be formed on the surfaces of the dielectric layers 34 and 35. Additionally, the MgO protecting film 36 can be formed on a portion which is exposed to the plasma discharge generated in the discharge space within the discharge cell 38. In the present embodiment, since the first electrode 31 and the second electrode 32 are disposed on a portion having substantially low contribution to the display between the substrates 10 and 20, the MgO protecting film 36 coated on the dielectric layer 34 for covering the first electrode 31 and the second electrode 32 can be composed of MgO having visible-light transmission characteristics. The visible-light non-transmission MgO has a secondary electron emission coefficient higher than that of visible-light transmission MgO, and thus the breakdown voltage can be reduced even more.
Hereinafter, the address electrode 12 will be described in detail with reference to
Referring to
In one embodiment, the widths of the first portion 12a and the second portion 12b are different from each other. In detail, the width WA1 of the central first portion 12a can be greater than the width WA2 of the end second portion 12b. Here, the widths of the first portion 12a and the second portion 12b are measured along a direction (x axis direction) intersecting the longitudinal direction of the address electrode 12.
The first portion 12a of the address electrode 12 is formed in the discharge space of the discharge cell 38 to generate the address discharge with the first electrodes 31. Accordingly, in the present embodiment, by increasing the width WA1 of the first portion 12a, the breakdown voltage of the address discharge is reduced and an amount of wall charges are stored in the dielectric layer 34 and 35 surrounding the first electrode 31 and the second electrode 32.
By reducing the width WA2 of the second portion 12b which has a low contribution to the address discharge, the current flowing in the address electrode 12 can be reduced. Accordingly, the power consumption can be reduced.
As viewed from the front surface of the substrates 10 and 20, the first portion 12a of the address electrode 12 and the first electrode 31 are spaced from each other as much as a first interval d1, and the first portion 12a and the second electrode 32 are spaced from each other as much as a second interval d2. Because the first portion 12a of the address electrode 12 and the first electrode 31 participate in the address discharge, the breakdown voltage of the address discharge can be efficiently reduced by allowing the first interval d1 to be smaller than the second interval d2, that is, by forming the first portion 12a close to the first electrode 31. Also, the first interval d1 and the second interval d2 can be substantially equal to each other.
On the other hand, as shown in
Hereinafter, modified embodiments of the first embodiment of the present invention will be described in detail. Since the modified embodiments of the first embodiment have the same basic structure as the first embodiment, the same components as the first embodiment are indicated by the same reference numerals.
Referring to
Referring to the modified embodiment of
This arrangement is possible because adjacent first electrodes 43 are spread apart and insulted from each other and because adjacent second electrodes 44 are also spaced apart and insulated from each other. Additionally, the use of matrix-shaped dielectric layers prevents cross-talk between adjacent discharge cells 38.
Referring to
Referring to
By forming the black layer 47 on the front substrate 20, external light is prevented from being reflected and thus bright room contrast can be improved. By forming the black layer 47 in a portion in which a first electrode 31 and second electrode 32 are formed, the visible light generated by the discharge is not blocked and thus bright room contrast can be improved.
Referring to
Hereinafter, a plasma display panel according to a second embodiment of the present invention will be described in detail. Since the basic structure of the second embodiment of the present invention is identical with or similar to the first embodiment, the description of the identical or similar structure will be omitted.
Referring to
In other words, in the present embodiment, the rear barrier rib 116 includes a first barrier rib member 116a which is formed in a direction (y axis direction) parallel with an address electrode 112, a second barrier rib member 116b which is formed in a direction (x axis direction) intersecting the first barrier rib member 116a and divides each rear discharge cell 118 formed on the rear substrate 110 into independent spaces, and a fifth barrier rib member 116c which is formed between the second barrier rib members 116b in a direction (x axis direction) parallel with the second barrier rib members 116b and divides the rear discharge cell 118 into two discharge spaces 118a and 118b.
The front barrier rib 126 includes the third barrier rib member 126a which is formed in a shape corresponding to that of the first barrier rib member 116a and the fourth barrier rib member 126b which is formed in a shape corresponding to that of the second barrier rib member 116b to form a front discharge cell 128 which corresponds to the discharge cell 118 on a front substrate 120.
The rear discharge cell 118 divided by the rear barrier rib 116 and the front discharge cell 128 divided by the front barrier rib 126 may form one discharge cell 138.
In addition, matrix-shaped dielectric layers 134 and 135 are arranged between the front barrier rib 116 and the rear barrier rib 126. A pair of electrodes that includes a first electrode 131 and a second electrode 132, which participates in the discharge of each discharge cell 138, formed in the dielectric layers 134 and 135. A MgO protecting film 136 can be formed on the surface of each of the dielectric layers 34 and 35.
The second electrode 132 selects the discharge cell 138 which will be turned on when a scan pulse voltage is applied during an address section together with the address electrode 112, and the first electrode 131 participates in the discharge of the sustain section together with the second electrode 132 to display an image. However, since the function of each of the electrodes may vary depending on an applied signal voltage, the function described above may be removed.
The first electrodes 131 are formed in a direction (x axis direction) intersecting the address electrode 112 at both sides of each discharge cell 138. Since the first electrodes 131 are arranged along the x axis direction between the second barrier rib member 116b and the fourth barrier rib member 126b therebetween, they can be a reference for dividing the discharge cells 138 which are adjacent to each other in a direction (y axis direction) parallel with the address electrode 112.
The second electrode 132 is formed between a pair of the first electrodes 131 along a direction (x axis direction) that parallels with the first electrodes 131 while intersecting each discharge cell 138 Accordingly, the first electrode 131 and the second electrode 132 are spaced from and face each other in each discharge cell 138.
In the present embodiment, a discharge gap of the sustain discharge which is generated between the first electrode 131 and the second electrode 132 is reduced and thus a breakdown voltage can be reduced even more. That is, since the discharge is generated between the second electrode 132 intersecting the discharge cell 138 and a pair of the first electrodes 131 which are disposed at both side of the discharge cell, the discharge gap between the first electrode 131 and the second electrode 132 which participate in the discharge sustaining is reduced by half. Accordingly, the driving occurs using a low breakdown voltage.
In the present embodiment, since the first electrodes 131 are formed at an area of the discharge cell 138 that contributes little to the display discharge, they can be made of a metal electrode having excellent conductivity. Also, the second electrodes 132 can be made of a metal electrode having excellent conductivity. When the first electrodes 131 and the second electrodes 132 are formed into an opaque metal electrode, bright room contrast can be improved.
The structures of the first electrode 131 and the second electrode 132 will be described in detail with reference to
In the present embodiment, the address electrodes 112 formed along a direction (y axis direction) in the front substrate 110 have a uniform line width.
Referring to
In the present embodiment, the first portion 131a is shared by a pair of the discharge cells 138 which are adjacent to each other in a direction (y axis direction) parallel with the address electrode 112, and the second portion 131b is shared by a pair of the discharge cells 138 which are adjacent to each other in a direction (x axis direction) intersecting the address electrode 112. In such a configuration, the second portion 131b has a uniform line width.
The second portions 131b of a pair of the first electrodes 131 are symmetrically formed at both sides of the discharge cell 138 and face each other across gaps separating them from the second electrode 132 that divides each discharge cell 138. The first electrode 131 having the above-mentioned structure can be formed to surround three sides of each discharge cell 138. That is, in two discharge spaces forming each discharge cell 138, the first electrodes 131 are disposed at three sides of the discharge cell and the second electrode 132 is disposed at one side thereof and thus discharge space of the sustain discharge generated between the first electrode 131 and the second electrode 132 can be used more efficiently.
With this structure, as shown in
Accordingly, the sustain discharge generated between the first electrode 131 and the second electrode 132 is initiated at the short gap G1 of the edge portion of the discharge cell 138 and is diffused into the long gap G2 of the central portion of the discharge cell 138. The sustain discharge is initiated at the short gap G1 so as to reduce the breakdown voltage and main discharge is sustained at the long gap G2 having a relatively long discharge length so as to improve the discharge efficiency.
Also, since the breakdown voltage can be efficiently reduced in the present embodiment, solves a longstanding conventional problem, which could not efficiently increase the partial pressure of Xe gas. That is, in the present embodiment, the partial pressure of Xe gas can be increased, and thus the discharge efficiency can be improved.
Hereinafter, the third through fifth embodiments will be described in detail. The basic structures of the third through fifth embodiments may be identical with or similar to that of the second embodiment.
First electrodes 141 are formed in a direction (x axis direction) intersecting an address electrode 112 at both sides of each discharge cell 138, and second electrodes 142 are formed between the first electrodes 141 while passing through the discharge cell 138.
Each of the first electrodes 141 includes a first portion 141a which is formed along a direction (x axis direction) intersecting the address electrode 112, and second portions 141b which are formed at both sides of the discharge cell 138 along a direction (y axis direction) parallel with the address electrode 112 and face each other. Accordingly, the first electrode 141 surrounds three sides of the discharge cell 138 and thus the discharge space can be used efficiently.
Referring to
In the present embodiment, the sustain discharge generated between the first electrode 141 and the second electrode 142 is initiated at the short gap of the edge portion of the discharge cell 138 and is diffused into the long gap of the central portion of the discharge cell, and thus the efficiency can be improved while reducing the breakdown voltage.
First electrodes 151 are formed in a direction (x axis direction) intersecting an address electrode 112 at both sides of each discharge cell 138, and second electrodes 152 are formed between the first electrodes 151 while passing through the discharge cell 138. The first electrodes 151 and the second electrode 152 face each other and thus the sustain discharge can be induced by the opposed discharge to reduce the breakdown voltage.
At this time, each of the first electrodes 151 includes a first portion 151a which is formed along a direction (x axis direction) intersecting the address electrode 112, and second portions 151b which are formed at both sides of the discharge cell 138 along a direction (y axis direction) parallel with the address electrode 112 and face each other. Accordingly, the first electrode 151 surrounds three sides of the discharge cell 138 and thus the discharge space can be used efficiently.
Referring to
In operation, the sustain discharge is initiated at the short gap between the protrusion 152a and the first electrode 151 located at the edge portion of the discharge cell 138, and thus the breakdown voltage can be reduced.
Referring to
Although the preferred embodiments of the invention have been described hereinabove, the invention is not limited to the embodiments. It should be understood that various modified embodiments, which may be made within the scope of the invention read on the appended claims, the detailed description of the invention, and the accompanying drawings, will still fall within the spirit and scope of the invention.
Number | Date | Country | Kind |
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10-2004-0096208 | Nov 2004 | KR | national |