This application claims priority to and the benefit of Korean Patent Application No. 10-2004-0033392, filed on May 12, 2004 in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a plasma display panel (PDP) and, in particular, to display electrodes of the PDP.
2. Description of the Related Art
A plasma display panel (PDP) is generally a display device in which vacuum ultraviolet (VUV) rays from plasma generated by gas discharge excite phosphors to emit red, green, blue visible lights for producing an image. Such a PDP can achieve a large screen display with a size over 60 inches (˜152.4 cm) while keeping its thickness within 10 cm. As an emissive display device like a cathode ray tube, the PDP has features of excellent color reproduction and no distortion along viewing angle. Compared to a liquid crystal display (LCD) device, the PDP has an advantage of a simple manufacturing process resulting in a good productivity and low cost. As a result, the PDP has emerged as a promising flat display device for home and industry.
In a typical alternating current (AC) PDP, as shown in
On a first surface of a front substrate 111 facing the rear substrate 101, formed along one direction crossing the address electrode are X and Y electrodes 113, 115, i.e., display electrodes, each including one of a pair of transparent electrodes 113a, 115a and one of a pair of bus electrodes 113b, 115b. A dielectric layer 117 and a MgO protective layer 119 in turn are formed on the entire front substrate 111 covering the X and Y electrodes 113, 115.
Discharge cells 121R, 121G, 121B are formed at locations where the address electrodes 103 of the rear substrate 101 cross a pair of the X and Y electrodes 113, 115 of the front substrate 111.
Such an AC PDP has millions of discharge cells arranged in a matrix pattern and adopts a driving method using memory characteristics to drive such a large number of discharge cells simultaneously.
As for the driving method, a voltage difference over a certain value is necessary to start a discharge between the X electrode 113 (a sustain electrode) and the Y electrode 115 (a scan electrode), both composing a pair of the display electrodes. A threshold voltage having the certain value is called a firing voltage (Vf). When an address voltage (Va) is applied between the Y electrode 115 and the address electrode 103, the discharge starts. The plasma is generated by the discharge in the discharge cell, and the electrons and ions in the plasma move toward the electrodes having the opposite polarity. As a result, the electrical current flows.
Since the dielectric layer 105 or 117 is coated on each electrode 103, 113, 115 of the AC PDP, most of the moving space charge is deposited on the dielectric layer 105 or 117 with the opposite polarity. Therefore, the net voltage difference across the gap between the Y electrode 115 and the address electrode 103 becomes smaller than the initial address voltage (Va), and that causes the discharge to be weak and disappear eventually. At this time, the dielectric layer 117 on the Y electrode collects a relatively large amount of the ions, compared to the dielectric layer 117 on the X electrode 113. The accumulated charges on the dielectric layer 117 over the X and Y electrodes 113, 115 are called the wall charge (Qw). Also, the voltage across the space between the X and Y electrodes 113, 115 is called the wall voltage (Vw).
For the case where a certain voltage (Vs; discharge sustain voltage) is applied between the X electrode 113 and the Y electrode 115 successively, the discharge starts in the discharge cell 121R, 121G, 121B when the sum (Vs+Vw) of the discharge sustain voltage (Vs) and the wall voltage (Vw) exceeds the firing voltage (Vf). The vacuum ultraviolet ray generated at this moment excites the corresponding phosphor layer 109R, 109G, 109B so that visible lights are emitted, and the transparent front substrate 111 transmits the visible light to show an image.
In the PDP with the barrier ribs 107 and the display electrodes 113, 115 formed in a stripe pattern as shown in
The U.S. Pat. No. 5,640,068 discloses a plasma display panel for solving the aforementioned problem. In addition to barrier ribs formed in a stripe pattern, its structure includes a pair of transparent electrodes of display electrodes formed, in each discharge cell, protruding from each bus electrode and facing each other. Even this structure may not prevent the misdischarge from happening in the direction along the barrier ribs.
A PDP with barrier ribs, formed in a matrix pattern by horizontal and vertical barrier ribs is provided to solve the problem as well as to enhance the luminous efficiency by increasing the phosphor area in each discharge cell. Further, in a PDP with partially modified barrier ribs in the structure, misdischarge in a non-discharge area may occur because bus electrodes of the display electrodes placed in the neighboring discharge cells are exposed to the non-discharge area. Thus, the misdischarge in the non-discharge area may cause the degradation in color purity due to a neon (Ne) light-discharge and in PDP efficiency due to unwanted power consumption.
A feature in exemplary embodiments of the present invention is to provide a plasma display panel that can prevent misdischarge in a non-discharge region.
In an exemplary embodiment according to the present invention, a plasma display panel includes a first substrate, a second substrate facing the first substrate, a plurality of display electrodes formed extending on the first substrate, and a plurality of address electrodes formed extending on the second substrate and crossing the display electrodes. The plasma display panel also includes barrier ribs including a plurality of barrier rib members. The barrier ribs are positioned between the first substrate and the second substrate, and form a plurality of discharge cells and non-discharge regions. A phosphor is formed inside each of the discharge cells. Each of the non-discharge regions includes one of exposure regions where a part of one of the display electrodes is exposed, the exposure regions being placed alternately in an extending direction of the display electrodes.
Each of the exposure regions may be formed at one side of one of the barrier rib members that extend in the extending direction of the display electrodes.
The exposure regions may be formed alternately at one side of one of the barrier rib members that extend in the extending direction of the display electrodes and at an opposing side of an adjacent one of the barrier rib members that extend in the extending direction of the display electrodes.
The exposure regions may be formed adjacent to the barrier rib members that are at two diagonal positions of each of the discharge cells.
The exposure regions may be formed at alternating locations in a zigzag pattern in the extending direction of the display electrodes.
The exposure regions may be formed alternately between an X electrode of one discharge cell and a Y electrode of an adjacent discharge cell among the plurality of discharge cells, the X electrode and the Y electrode composing the display electrodes.
Each of the plurality of the display electrodes may consist of a bus electrode and a transparent electrode, and a part of the bus electrode of each of the display electrodes may be exposed to at least one of the exposure regions.
A part of the bus electrode corresponding to one of the discharge cells may be exposed to a corresponding one of the exposure regions and another bus electrode corresponding to an adjacent one of the discharge cells may be blocked by one of the barrier rib members that extends in an extending direction of the bus electrode.
The barrier rib members may include first barrier rib members formed in the extending direction of the address electrodes and placed parallel to each other, second barrier rib members formed in a direction crossing the first barrier rib members and placed parallel to each other, and third barrier rib members connecting the first and second barrier rib members with an incline at two diagonal corners of each of the discharge cells.
The second barrier ribs may be interconnected by fourth barrier rib members, each of which is positioned between the second barrier rib member of one of the discharge cells and the adjacent second barrier rib member of an adjacent one of the discharge cells.
Each of the discharge cells may be formed asymmetrically about an extending direction of the address electrodes and/or the extending direction of the display electrodes.
Both sides of each of the discharge cells in an extending direction of the address electrodes may be formed narrower than a center of the discharge cell.
In both sides of each of the discharge cells in an extending direction of the address electrodes, one corner may be formed with a right angle and the other corner may be formed inclined so that a discharging region becomes narrower as it moves from a center of the discharge cell to the sides.
In another exemplary embodiment according to the present invention, a plasma display panel includes a first substrate, a second substrate facing the first substrate, and a plurality of display electrodes formed extending in a first direction on the first substrate. The plasma display panel also includes a plurality of address electrodes formed on the second substrate, and extending in a second direction, which is substantially perpendicular to the first direction. Barrier ribs are positioned between the first and second substrates, and form a plurality of discharge cells and non-discharge regions. A phosphor is formed inside each of the discharge cells. Each of the display electrodes is exposed to every other one of the non-discharge regions in the first direction.
As shown in
Corresponding to the discharge cells 7R, 7G, 7B, display electrodes 11, 13 are formed on the first substrate 1, extending in the x-direction and placed parallel to each other with a pitch of the discharge cells 7R, 7G, 7B in the y-direction. Address electrodes 15 are formed on the second substrate 3, extending in the direction (y-direction) crossing the display electrodes 11, 13 and placed parallel to each other with a pitch of the discharge cells 7R, 7G, 7B in the x-direction.
The display electrodes 11, 13 include X electrodes 11 and Y electrodes 13 that are placed parallel to each other and correspond to each of the discharge cells 7R, 7G, 7B. The X electrodes 11 and Y electrodes 13 are formed on the first substrate 1 and covered by a dielectric layer 17 and a MgO protective layer 19, in turn.
The X and Y electrodes 11, 13 include a transparent electrode 11a or 13a and a bus electrode 11b or 13b, respectively. The X and Y electrodes 11 and 13 may alternatively include only the transparent electrodes 11a, 13a or the bus electrodes 11b, 13b, respectively. The transparent electrodes 11a and 13a serve to cause surface discharge inside the discharge cells 7R, 7G, 7B and are made of transparent indium-tin oxide (ITO) to obtain a high opening ratio and a high transmittance for visible light. The bus electrodes 11b and 13b should be made of a metallic material such as aluminum to obtain high conductance by compensating high resistance of the transparent electrodes 11a, 13a. A pair of bus electrodes 11b, 13b corresponding to each of the discharge cells 7R, 7G, 7B, extends in the x-direction and is placed parallel to each other with a gap in the y-direction. Like the bus electrodes 11b, 13b, the transparent electrodes 11a, 13a may be formed in a stripe pattern along the x-direction. However, the transparent electrodes 11a, 13a of the present embodiment may be formed protruding, respectively, from the bus electrodes 11b, 13b toward the center of each of the discharge cells 7R, 7G, 7B. Also, the bus electrodes 11b, 13b may be formed meanderingly to follow the shape of the barrier rib 5.
The address electrodes 15 are formed on the second substrate 3, extend in the direction (y-direction) crossing the X and Y electrodes 11, 13 and placed parallel to each other with a pitch in the x-direction. The address electrodes 15 are covered with a dielectric layer 21.
The barrier ribs 5 are formed between the front substrate 1 having the X and Y electrodes 11, 13 and the rear substrate 3 having the address electrodes 15, and define the independent discharge cells 7R, 7G, 7B for the plasma discharge.
A non-discharge region A is formed outside the barrier ribs 5 in the space between the neighboring discharge cells 7R, 7G, 7B in the extending direction (y-direction) of the address electrodes 15, and a discharge region is the inside of each of the discharge cells 7R, 7G, 7B. In other words, the barrier ribs 5 form the closed discharge cells 7R, 7G, 7B in the x-y coordinate plane between the front substrate 1 and the rear substrate 3. The discharge cells 7R, 7G, 7B are directly attached to each other in the x-direction and coupled to each other in the y-direction through the non-discharge regions A that separate the neighboring discharge cells in the y-direction. The non-discharge regions A are placed generally in the x-direction crossing the address electrodes 15.
The discharge cells 7R, 7G, 7B are filled with a discharge gas and provide the space where gas discharge occurs under an address or a sustain voltage applied therein. The non-discharge region A is a space or a region where discharge or light emission is not planned and where a voltage is not intentionally applied.
The non-discharge region A includes an exposure region B where the display electrode 11 or 13 is partially exposed. The exposure regions B are placed alternately in the extending direction (x-direction) of the display electrodes 11, 13.
In the present invention, therefore, the discharge cells 7R, 7G, 7B are asymmetrical about both the extending direction (x-direction) of the display electrodes 11, 13 and the extending direction (y-direction) of the address electrodes 15. Due to the asymmetrical discharge cells 7R, 7G, 7B and the bus electrodes 11b, 13b formed in a stripe pattern, a part of the bus electrodes 11b, 13b is exposed to the non-discharge region A at the position where the barrier rib does not coincide with the bus electrode 11b, 13b.
If both the bus electrodes 11b, 13b are exposed to one non-discharge region A, misdischarge may occur even in the non-discharge region A, and that may cause a serious degradation in color purity and luminous efficiency of the PDP. Therefore, to prevent the misdischarge in the non-discharge region A, the exposure regions B included in the non-discharge regions A are formed alternately along the extending direction (x-direction) of the display electrodes 11, 13.
The shape of the non-discharge regions A including the exposure regions B are defined by the arrangement of the barrier ribs 5. To begin with, the arrangement of the non-discharge regions A and the exposure regions B are explained in the x-y plane.
As aforementioned, the non-discharge regions A are arranged along the direction (x-direction) crossing the address electrode 15 and therefore, placed between the neighboring discharge cells 7R, 7G, 7B in the y-direction. Each exposure region B is formed inside a corresponding one of the non-discharge regions A in a manner where the exposure regions B are placed alternately along the x-direction.
As shown in
Therefore, a part of the X and Y electrodes 11, 13 including the transparent electrodes 11a, 13a and the bus electrodes 11b, 13b is exposed to the exposure regions B. Specifically, a local surface of the bus electrodes 11b, 13b is exposed to each exposure region B.
Even in this case, as shown in
The barrier ribs 5 may be formed in a variety of arrangements to fulfill the role of the non-discharge region A and the exposure region B. However, the present embodiment shows first, second and third barrier rib members 5a, 5b, 5c. Also, a fourth barrier rib member 5d is included in the embodiment illustrated in
The first barrier rib members 5a are formed in the extending direction (y-direction) of the address electrodes 15 and placed parallel to each other with a pitch of the discharge cells 7R, 7G, 7B in the x-direction. The separated first barrier rib members 5a form the independent discharge cells 7R, 7G, 7B. The second barrier rib members 5b are formed in the direction (x-direction) crossing the first barrier rib members 5a and placed parallel to each other with a pitch of the discharge cells 7R, 7G, 7B in the y-direction. The second barrier rib members 5b are formed separately to connect each two neighboring discharge cells in the x-direction. Therefore, the first barrier rib members 5a and the second barrier rib members 5b join at two diagonal corners of the discharge cell 7R, 7G, 7B and form a right angle. At other two diagonal corners, each end of the first barrier rib members 5a and the second barrier rib members 5b is connected to an inclined third barrier rib member 5c. Therefore, other two corners of the discharge cell 7R, 7G, 7B except two right-angled corners are formed with an inclination.
In other words, each of the discharge cells 7R, 7G, 7B is formed in an asymmetrical structure having two diagonal corners with a right angle and two diagonal corners with an inclination. Therefore, both sides of the discharge cell 7R, 7G, 7B in the extending direction (y-direction) of the address electrodes 15 are formed narrower than the center of the discharge cell 7R, 7G, 7B. To be specific, in both sides of the discharge cell 7R, 7G, 7B in the extending direction (y-direction) of the address electrode, one corner is formed with a right angle and the other corner is formed inclined so that the discharging region becomes narrower as it moves from the center of the discharge cell to the sides.
The discharge cells 7R, 7G, 7B are formed to substantially minimize or reduce the discharging regions that contribute little to the improvement in its sustain discharge and luminance. Both sides of the discharge cell 7R, 7G, 7B in the extending direction (y-direction) are formed narrower than the center of the discharge cell 7R, 7G, 7B as it moves away from the center. In one side of the discharge cell 7R, 7G, 7B, one corner is formed with a right angle and the other corner is formed with an inclination. This is done to prevent the misdischarge in the non-discharge region A between the bus electrodes 11b, 13b by blocking one of the bus electrodes 11b, 13b using the barrier rib 5.
In addition, the barrier rib 5 shown in
Hereinafter, the non-discharge region A and the exposure region B are described in detail.
The exposure region B is formed at one side of the first barrier rib member 5a placed in the extending direction (y-direction) of the address electrodes 15. In the discharge cells 7R, 7G, 7B arranged in the x-direction, the exposure regions B are formed at one side of the first barrier rib member 5a and at the opposing side of the adjacent first barrier rib member 5a thereto. Therefore, the exposure regions B are formed at the diagonal positions of two first barrier rib members 5a in each discharge cell 7R, 7G, 7B and placed in a zigzag pattern in the extending direction (x-direction) of the display electrodes 11, 13. That means that the locations of the exposure regions B are alternating between the positions of the X electrode 11 in one discharge cell 7R, 7G, 7B and the Y electrode 13 in the neighboring discharge cell 7R, 7G, 7B.
In the plasma display panel of the present invention, as explained hereinabove, the exposure regions where the display electrode, i.e., a part of the bus electrode is exposed are arranged alternately in the extending direction of the display electrode. While one bus electrode is partially exposed to the exposure region, the other bus electrode of the neighboring discharge cell is blocked by the barrier rib. This effectively prevents misdischarge in the non-discharge regions between two adjacent bus electrodes.
Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be understood that many variations and/or modifications of the basic inventive concept taught therein will still fall within the spirit and scope of the present invention, as defined in the appended claims and equivalents thereof.
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