The present invention relates to a plasma display panel used for a display device.
A plasma display panel (PDP) is configured with two glass plates adhering to each other, and displays an image with discharge light emitted in a space formed between the glass plates. A cell corresponding to a pixel of the image is a self-luminescence type and coated with phosphors which emit visible lights of red, green and blue under ultraviolet rays emitted by the discharge.
A three-electrode structure PDP displays an image by generating sustain discharge between an X-electrode and Y-electrode. A cell to generate the sustain discharge (cell to be lighted) is selected by selectively generating address discharge, for example, between the Y-electrode and an address electrode.
In a typical PDP, the X-electrode and the Y-electrode are disposed on a front glass plate and the address electrode is disposed on a back glass plate. In addition, there has been recently proposed a PDP in which the three electrodes of the X-electrode, the Y-electrode, and the address electrode are disposed on the front glass plate (refer to Patent document 1, for example).
Patent document 1: Japanese Unexamined Patent Application Publication No. 2003-257321
In the PDP of Patent document 1, the Y-electrodes of the adjacent cells (one row electrode of row electrode pair) are disposed on both sides of the address electrode (column electrode). Accordingly, when the address discharge is generated between one side of the Y-electrodes adjacent to the address electrode and the address electrode, there is a probability that erroneous discharge is generated between the other side of the Y-electrodes adjacent to the address electrode and the address electrode. That is, when the cell to be lighted and the cell not to be lighted neighbor each other, there is a probability that the erroneous discharge is generated in the cell not to be lighted. In particular, in the case that the position of the address electrode is misaligned from the center of a barrier rib provided on the back glass plate to the opposite side of the corresponding Y-electrode because of an assembly error when adhering the glass plates, the generation probability of the erroneous discharge becomes higher between the address electrode and the Y-electrode in the adjacent cell.
A proposition of the present invention is to prevent the erroneous discharge in the adjacent cell when the address discharge is carried out in the PDP having the three electrodes on the front glass plate.
A plasma display panel includes a first plate and a second plate facing each other via a discharge space. On the first plate, a first bus electrode and a second bus electrode are provided which extend in a first direction and are disposed at intervals. On the second plate, a plurality of two of the first barrier ribs adjacent to each other are provided which extend in a second direction perpendicular to the first direction and are disposed at intervals. Further, a cell is formed in a region surrounded by the first bus electrode, the second bus electrode and the first barrier ribs.
In the cell, a first display electrode is provided which is coupled to the first bus electrode and extends from the first bus electrode toward the second bus electrode. Further, in the cell, a second display electrode is provided which is coupled to the second bus electrode, extends from the second bus electrode toward the first bus electrode, and includes an opposed part of the first display electrode along a second direction. In addition, on the first plate, a dielectric layer is provided which covers the first bus electrode, the second bus electrode, the first display electrode and the second display electrode, and on the dielectric layer, a plurality of address electrodes are provided which are disposed at respective positions facing the first barrier ribs. The first display electrode and the second display electrode are disposed on both sides of one of the address electrodes adjacently, respectively, along the first direction.
Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
The front panel part 12 has an X-bus electrode Xb (first bus electrode) and a Y-bus electrode Yb (second bus electrode) which are formed on a glass base FS (first plate) (lower side in the drawing) in parallel to the first direction D1 and disposed alternately along the second direction D2, for generating the discharge repeatedly. The X-bus electrode Xb is coupled with an X-transparent-electrode Xt (first display electrode) which extends from the X-bus electrode Xb toward the Y-bus electrode Yb in the second direction D2. Further, the Y-bus electrode Yb is coupled with a Y-transparent-electrode Yt (second display electrode) which extends from the Y-bus electrode Yb toward the X-bus electrode Xb in the second direction D2.
Here, the X-bus electrode Xb and the Y-bus electrode Yb are opaque electrodes made of a metal material or the like, and the X-transparent-electrode Xt and the Y-transparent-electrode Yt are transparent electrodes which are made of ITO films or the like and transmit light. The transparent electrodes Xt and Yt are sometimes disposed over the whole areas between the respectively adhering bus electrodes Xb and Yb and the glass base FS. Further, the transparent electrodes Xt and Yt may be formed integrally with the bus electrodes Xb and Yb using the same material (metal material or the like) as that of the bus electrodes Xb and Yb. Then, an X electrode XE (sustain electrode) is configured with the X-bus electrode Xb and the X-transparent-electrode Xt, and a Y electrode YE (scan electrode) is configured with the Y-bus electrode Yb and the Y-transparent-electrode Yt.
The electrodes Xb, Xt, Yb and Yt are covered by a dielectric layer DL1. For example, the dielectric layer DL1 is a silicon dioxide film (film of SiO2, film of silicon dioxide) formed by a CVD method. Then, on the dielectric layer DL1 (lower side in the drawing) is provided a plurality of address electrodes AE which extend in the direction perpendicular to the bus electrodes Xb and Yb (second direction D2). The address electrodes AE are covered by a dielectric layer DL2 and the surface of the dielectric layer DL2 is covered by a protective layer PL such as an MgO film or the like.
The back plate part 14, which faces the front plate part 12 via the discharge space DS, includes first barrier ribs BR1 formed on a glass base RS (second plate) in parallel to each other. The barrier rib BR1 extends in the direction perpendicular to the bus electrodes Xb and Yb (second direction D2) and faces the address electrode AE. In other words, the address electrode AE is disposed at a position facing the barrier rib BR1. The barrier rib BR1 forms a side wall of a cell. Further, on the side of the barrier rib BR1, and on the glass base RS between the barrier ribs adjacent to each other, phosphors PHr, PHg, and PHb are coated which emit visible lights of red (R), green (G), and blue (B) respectively, by the excitation of the ultraviolet ray.
One pixel of the PDP 10 is configured with three cells which emit the red, green, and blue light, respectively. Here, one cell (pixel of one color) is formed in the discharge space DS defined by the bus electrodes Xb and Yb and the barrier ribs BR1. In this manner, the PDP 10 has the cells disposed in a matrix for displaying an image and also configured with alternately disposed plural kinds of cells which emit light with colors different from each other. While not illustrated particularly in the drawing, a display line is configured with the cells formed along the bus electrodes Xb and Yb.
The PDP 10 is made up by adhering the front plate part 12 and the back plate part 14 together so that the protective layer PL and the barrier rib BR1 contact each other, and encapsulating discharge gas such as Ne, Xe, etc. into the discharge space DS.
When viewed from the image display surface side, the address electrode AE is provided at a position overlapping the barrier rib BR1. As described above, the cell C1 is formed in the region surrounded by the bus electrodes Xb and Yb and the barrier ribs BR1 (region surrounded by the bold broken line in
The X-transparent-electrode Xt and the Y-transparent-electrode Yt are provided for each cell C1 and face each other along the second direction D2. Further, the transparent electrode Yt faces the corresponding address electrode AE (positioned in the left thereof in the drawing) via the dielectric layer DL1. Accordingly, by applying a voltage between the address electrode AE and the transparent electrode Yt, it is possible to generate address discharge in the discharge space DS of the focused cell C1. At this time, the barrier rib BR1 works as a part of the dielectric layer and an electric field is generated in the discharge space DS between the address electrode AE and the transparent electrode Yt.
Further, the transparent electrodes Xt and Yt disposed along the display line DSL are disposed alternately along the first direction D1. Accordingly, in a pair of the cells C1 adjacent to each other in the first direction D1 sandwiching the address electrode AE, the transparent electrode Yt (scan electrode) in one of the cells C1 neighbors the address electrodes AE on one side in the first direction D1 (right side in the drawing), and the transparent electrode Xt (sustain electrode) of the other cell C1 neighbors the address electrode AE on the other side in the first direction D1 (left side in the drawing). In other words, in the pair of cells C1 adjacent to each other in the first direction D1 sandwiching the address electrode AE, the address electrode AE faces only the transparent electrode Yt on one side.
Accordingly, when generating the address discharge between the address electrode AE and the transparent electrode Yt of the focused cell C1 (address period), it is possible to prevent the erroneous discharge from occurring in the adjacent cell C1. Thereby, even in the case that the position of the address electrode AE is shifted from the center of the barrier rib BR1 to the opposite direction of the corresponding transparent electrode Yt (to the side of the transparent electrode Xt) when the front plate part 12 and the back plate part 14 are put together, the erroneous discharge is not generated in the adjacent cell C1. Accordingly, a higher assembly accuracy is not necessary for making the front plate part 12 and the back plate part 14 to adhere to each other in the PDP having three electrodes on the glass base FS (front glass plate), and it is possible to simplify the assembly process.
The control unit CNT selects a subfield to be used according to image data R0-7, G0-7, and B0-7, and outputs control signals YCNT, XCNT, and ACNT to the drivers YDRV, XDRV, and ADRV, respectively. Here, the subfield is a field divided from one filed for displaying one screen of the PDP 10, and the number of times of sustain discharge is determined for each subfield. Then, a multiple gradation image is displayed by selection of the subfield to be used for each cell C1 composing the pixel.
First, in the reset period RST, a gradually decreasing negative voltage (slope pulse) is applied to the sustain electrode XE (bus electrode Xb and transparent electrode Xt), and a positive voltage is applied to the scan electrode YE (bus electrode Yb and transparent electrode Yt) (
In the address period ADR, a scan voltage which becomes anode in the address discharge is applied to the sustain electrode XE, a scan pulse which becomes cathode in the address discharge is applied to the scan electrode YE, and an address pulse (voltage Vsa) which becomes anode in the address discharge is applied to the address electrode AE which corresponds to the cell to be lighted (
The second address pulse shown in the waveform at the address electrode AE is applied for selecting a discharge cell in another display line (
In the sustain period SUS, negative and positive sustain pulses are applied to the sustain electrode XE and the scan electrode YE, respectively (
In the erase period ERS, a negative pre-erase pulse and a positive high voltage pre-erase pulse are applied to the sustain electrode XE and the scan electrode YE, respectively, to generate discharge (
As described above, in the first embodiment, the transparent electrodes Xt and Yt are disposed alternately along the first direction D1 (direction perpendicular to the address electrode AE). That is, in the cells adjacent to each other in the first direction D1 via the address electrode AE, the transparent electrodes Yt of both cells C1 do not neighbor on the both sides of one address electrode AE. As a result, it is possible to prevent the erroneous discharge in the cell C1 adjacent via the address electrode AE.
Further, even in the case that the position of the address electrode AE is shifted from the center of the barrier rib BR1 to the opposite side of corresponding transparent electrode Yt (transparent electrode Xt side), the erroneous discharge is not generated between the address electrode AE and the transparent electrode Xt, and thereby a higher assembly accuracy is not necessary for making the front plate part 12 and the back plate part 14 to adhere to each other, resulting in simplifying the assembly process.
Further, since the back plate part 14 is not provided with the address electrode AE, the barrier rib BR1 can be formed by the direct engraving of the glass base RS. Thereby, it is possible to reduce the production cost of the PDP 10 because the baking process is not necessary for forming the barrier rib BR1.
The projection part Ap is formed integrally with the address electrode AE, projecting from the address electrode AE between an end of the transparent electrode Yt and the bus electrode Xb. That is, the projection part Ap is disposed on the discharge space DS of the cell C1 corresponding to the address electrode AE via the dielectric layer DL2 and the protective layer PL. Since the projection part Ap is formed on the discharge space DS, the firing voltage can be reduced in generating the discharge between the projection part Ap and the transparent electrode Yt. That is, the voltage applied between the address electrode AE and the transparent electrode Yt, for example, the voltage Vsa shown in
As described above, also in the second embodiment, it is possible to obtain the same effect as that of the first embodiment. Further, in this embodiment, since the discharge is generated between the projection part Ap formed on the discharge space DS and the transparent electrode Yt, it is possible to reduce the voltage to be applied during the address period, for example, the voltage Vsa shown in
The projection part Ap2 is formed integrally with the address electrode AE projecting from the address electrode AE between the end of the transparent electrode Yt and the bus electrode Xb. Further, a part of the projection part Ap2 is disposed at a position which overlaps the end of the transparent electrode Yt with the dielectric layer DL1 (broken line part in
As described above, also in the third embodiment, it is possible to obtain the same effect as that of the above first and second embodiments. Further, it is possible to further reduce the voltage to be applied between the address electrode AE and the transparent electrode Yt, for example, the above voltage Vsa shown in
The address electrode AE is disposed nearer to the transparent electrode Yt side in relation to the center of the barrier rib BR1. For example, a part of the address electrode AE is disposed so as to protrude from the barrier rib BR1 to the transparent electrode Yt side. The address electrode AE may be disposed nearer to the transparent electrode Yt side without protruding from the barrier rib BR1 to the transparent electrode Yt side. Thereby, the distance between the address electrode AE and the transparent electrode Yt can be reduced and the firing voltage can be reduced when the discharge is generated between the address electrode AE and the transparent electrode Yt.
As described above, also in the fourth embodiment, it is possible to obtain the same effect as that of the above first embodiment. Further, in this embodiment, the firing voltage can be reduced and thereby it is possible to obtain the same effect as that of the above second embodiment.
In an intersection area CA where the electrode Xb or Yb and the electrode AE intersect with each other, the address electrode AE is formed with a narrower line width than that of the part excluding the intersection area CA. That is, the bus electrodes Xb and Yb are formed with the same line widths as those in the first embodiment, and only the address electrode AE is formed with a narrower line width in the intersection area CA than that of the part excluding the intersection area CA of the address electrode AE. The bus electrode Xb or Yb may be formed with a narrower line width in the intersection area CA than the line width of the part excluding the intersection area CA. Since the intersection area CA is formed with the narrower line width, it is possible to reduce a wiring capacitance formed between the electrode Xb or Yb and the electrode AE.
As described above, also in the fifth embodiment, it is possible to obtain the same effect as that of the above first embodiment. Further, since the wiring capacitance formed between the electrode Xb or Yb and the electrode AE is smaller in this embodiment, it is possible to save the driving force of the driver circuits for the electrodes Xb and Yb and the electrode AE (e.g. drivers XDRV, YDRV, and ADRV shown in
The second barrier ribs BR2 are formed on the glass base RS in the first direction D1 and face the bus electrodes Xb and Yb. The side walls of the cell are formed by the barrier ribs BR1 and BR2. That is, the discharge spaces DS of the cells are separated from each other by the barrier ribs BR1 and BR2. Thereby, it is possible to prevent the erroneous discharge in the cell adjacent in the second direction D2.
When viewed from the image display surface side, the bus electrodes Xb and Yb are provided at positions overlapping the barriers BR2. The cell C1 is formed in a region surrounded by the barrier ribs BR1 and BR2 (region surrounded by the bold broken line in
The barrier ribs BR1 and BR2 are formed by the direct engraving of the glass base RS by the sandblast method or the like. That is, the barrier rib BR2 is formed integrally with the barrier rib BR1.
As described above, also in the sixth embodiment, it is possible to obtain the same effect as that of the above first embodiment. Further, since the cells C1 are separated from each other by the barrier ribs BR1 and BR2 in this embodiment, it is possible to prevent the erroneous discharge in each of the cells adjacent in the four directions.
Note that the above embodiments describe the examples in which one pixel is configured with three cells (red (R), green (G), and blue (B)). The present invention is not limited to such embodiments. For example, one pixel may be configured with four or more cells. Alternatively, one pixel may be configured with cells which emit colors except red (R), green (G) and blue (B), and also may include a cell which emits a color except red (R), green (G), and blue (B).
The above second and third embodiments describe the examples in which the projection parts Ap and Ap2 are formed integrally with the address electrode AE, respectively. The present invention is not limited to such embodiments. For example, the projection parts Ap and Ap2 may be formed by transparent electrodes coupled to the address electrode AE. Also in this case, it is possible to obtain the same effect as that of the above second or third embodiment. Further, since the projection parts Ap and Ap2 are formed by the transparent electrodes, it is possible to widen the light transmission region in each cell.
As described above, the present invention has been described in detail, but the above embodiments and modification examples thereof are only examples of the invention and the present invention is not limited thereto. It is obvious that modification is possible in the range without departing from the present invention.
The many features and advantages of the embodiments are apparent from the detailed specification and, thus it is intended by the appended claims to cover all such features and advantages of the embodiments that fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the inventive embodiments to exact construction and operation illustrated and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope thereof.
This application is a U.S. National Stage application claiming the benefit or prior filed International Application No. PCT/JP2007/000319, filed on Mar. 28, 2007, the entire contents of which are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2007/000319 | 3/28/2007 | WO | 00 | 9/24/2009 |