Patent Application
20090135097
This application claims priority to Korean patent application 10-2007-0116680, filed on Nov. 15, 2007, Korean patent application 10-2007-0116681, filed on Nov. 15, 2007 and Korean patent application 10-2007-0116682, filed on Nov. 15, 2007, the disclosure of which is incorporated by reference herein.
1. Technical Field
The present invention is directed to a plasma display panel device, and more specifically to a structure of electrodes included in a plasma display panel of a plasma display panel device.
2. Discussion of Related Art
In general, a plasma display panel includes an upper substrate and a lower substrate. Barrier ribs are positioned between the upper substrate and the lower substrate, and each of the barrier ribs defines a unit cell. An inert gas is injected in each unit cell, which consists of a primary discharge gas and a small amount of Xe, wherein the primary discharge gas includes any one of Ne, He, and a mixture of Ne and He. The inert gas emits vacuum ultraviolet rays when being discharged by a high frequency voltage, and the emitted vacuum ultraviolet rays excite phosphors formed in the barrier ribs to display an image. This plasma display panel may be made thinner and lighter, and therefore, it gains popularity as a next generation display.
In a general plasma display panel, a scan electrode and a sustain electrode are formed on the upper substrate, and these scan electrode and sustain electrode, respectively, have a structure in which a transparent electrode and a bus electrode that are made of expensive ITO (Indium Tin Oxide) are stacked on each other in order to ensure high aperture ratio of the panel.
Recently, a plasma display panel is developed, which is capable of providing viewers with sufficient visual perception and driving characteristics as well as saving manufacturing costs.
Therefore, there is a need of a plasma display panel device capable of improving the brightness of a displayed image as well as reducing manufacturing costs of the panel by removing necessity of transparent electrodes made of ITO.
An exemplary embodiment of the present invention provides a plasma display panel device including an upper substrate; a first electrode and a second electrode formed on the upper substrate; a lower substrate arranged to face the upper substrate; and a third electrode formed on the lower substrate, wherein the first electrode is formed in a single layer, and the first electrode includes an electrode line to cross the third electrode and a protruding electrode that extends from the electrode line toward the second electrode, wherein the breadth of a lower end of the protruding electrode located near the electrode line is about 0.7 times to about 4.5 times the breadth of an upper end of the protruding electrode.
The present invention will become more apparent by describing in detail exemplary embodiments thereof with references to the attached drawings, in which:
Hereinafter, exemplary embodiments of the present invention will be described with reference to accompanying drawings.
Referring to
The upper panel 10 includes an upper substrate 11 on which a maintaining electrode pair 12 and 13 is formed that includes a scan electrode 12 and a sustain electrode 13, each of which is separated from the other depending on its functions. The maintaining electrode pair 12 and 13 is covered with an upper dielectric layer 14 which limits a discharge current and insulates one maintaining electrode pair from another. A protection layer 15 is arranged on the upper dielectric layer 204 to protect the upper dielectric layer 14 from sputtering of charged particles created upon gas discharge and raises emission efficiency of secondary electrons.
A discharge gas is injected in a discharge space partitioned by the upper substrate 11, a lower substrate 21, and a barrier rib 22. The discharge gas may contain Xe more than 10%. In a case where Xe is contained in the discharge gas by the above mixing ratio, the discharge/emission efficiency and brightness of the plasma display panel may be improved.
The lower panel 20 includes a lower substrate 21 on which the barrier rib 22 is formed to define the discharge space, i.e. discharge cell. An address electrode 23 is formed on the lower substrate 21 to cross the maintaining electrode pair 12 and 13. A phosphor layer 24 is applied on the surface of the lower dielectric layer 25 and the barrier rib 22. The phosphor layer 24 is excited by ultraviolet rays generated upon gas discharge to emit visible rays.
The barrier rib 22 includes a vertical barrier rib 22a, which is arranged in parallel with the address electrode 23, and a horizontal barrier rib 22b, which is arranged to cross the address electrode 23. The barrier rib 22 physically defines the discharge cell and prevents ultraviolet rays and visible rays generated by discharge from leaking to neighboring discharge cells.
In the plasma display panel according to an exemplary embodiment of the present invention, the maintaining electrode pair 12 and 13 is made only of an opaque metal. For instance, the maintaining electrode pair may be made not of ITO (Indium Tin Oxide), which is conventionally used for a transparent electrode, but of Ag, Cu, or Cr, which is conventionally used for a bus electrode. That is, the maintaining electrode pair 12 and 13 is formed in a single bus electrode layer without the conventional ITO electrode.
For example, the maintaining electrode pair 12 and 13 may be made of Ag that may be photosensitive. The maintaining electrode pair 12 and 13 may be darker in color and lower in transmittance than the upper dielectric layer 14 or lower dielectric layer 14. The phosphor layers 24 applied in red, green, and blue discharge cells may be equal or different in pitch to/from each other. In case that the phosphor layers 24 are different in pitch from each other, the pitch of the green discharge cell may be larger than the pitch of the red discharge cell, and smaller than the pitch of the blue discharge cell.
As shown in
The first and second sustain electrodes 12 and 13 may be a scan electrode and a sustain electrode, respectively, taking into consideration aperture ratio and discharge diffusion efficiency according to usage of the opaque maintaining electrode pair 12 and 13. That is, an electrode line whose width is narrow is used considering aperture ratio, and plural electrode lines are used considering discharge diffusion efficiency. At this time, the number of electrode lines may be determined considering both of aperture ratio and discharge diffusion efficiency.
The structure of the plasma display panel shown in
Although the barrier rib shown in
The array of electrodes shown in
In accordance with an exemplary embodiment of the present invention, a reset period may be omitted from at least one of the plural subfields. For example, the reset period may exist only within the first subfield, or only within the first subfield and a subfield positioned between the first subfield and the last subfield.
During each address period A1 to A8, a display data signal is applied to the address electrode X and its corresponding scan pulse is sequentially applied to each scan electrode Y.
During each sustain period S1 to S8, a sustain pulse is alternately applied to the scan electrode Y and the sustain electrode Z, so that sustain discharge occurs in the discharge cells in which wall charges are generated during the address period A1 to A8.
The brightness of the PDP is in proportion to the number of sustain discharge pulses generated during the sustain periods S1 to S8 occupying a unit frame. In a case where one frame embodying one image is represented as eight subfields and 256 gray scales, the number of sustain pulses may be differently assigned to each subfield in the ratio of 1, 2, 4, 8, 16, 32, 64, and 128. The brightness of 133 grays scales may be achieved by causing a sustain discharge while addressing cells during subfields SF1, SF3, and SF8.
The number of sustain discharges assigned to each subfield may be determined according to weight value of subfields in an automatic power control (APC) stage. Although a case has been described in
Also, the number of sustain discharges assigned to each subfield may change variously considering gamma properties or panel characteristics. For example, the degree of gray scale assigned to subfield SF4 may be lowered from 8 to 6, and the degree of gray scale assigned to subfield 6 may be raised from 32 to 34.
Referring to
A reset period includes a set-up period and a set-down period. During the set-up period, a ramp-up waveform is simultaneously applied to the overall scan electrodes to cause a tiny discharge in the whole discharge cells, and as a consequence, wall charges are generated. During the set-down period, a ramp-down waveform, which falls from a positive voltage whose peak is lower than that of the ramp-up waveform, is simultaneously applied to the whole scan electrodes Y to cause an erase discharge in the overall discharge cells, and accordingly, unnecessary charges are erased from space charges and wall charges generated by set-up discharge.
During the address period, a scan signal having a negative scan voltage Vsc is sequentially to the scan electrodes, and at the same time, a positive data signal is applied to the address electrode X. An address discharge occurs by the voltage differential between the scan signal and the data signal and wall charges generated during the reset period, and therefore, a cell is selected. Meanwhile, a sustain bias voltage Vzb may be applied to the sustain electrode during the address period to raise the efficiency of address discharge.
During the address period, the plural scan electrodes Y may be grouped into two or more, and scan signals may be sequentially applied to the scan electrode groups. And, each scan electrode group may be divided again into two or more sub groups, and scan signals may be sequentially supplied to the sub groups. For example, the plural scan electrodes Y may be divided into a first group and a second group, and scan signals are sequentially supplied to scan electrodes included into the first group and then to scan electrodes included into the second group.
In accordance with an exemplary embodiment of the present invention, the plural scan electrodes Y may be divided into a first group including even-numbered scan electrodes and a second group including odd-numbered scan electrodes. In addition, the plural scan electrodes Y may be divided into a first group including scan electrodes located in an upper part of the panel and a second group including scan electrodes located in a lower part of the panel with respect of a central axis of the panel.
The scan electrodes included in the first group may be divided again into a first sub group including even-numbered scan electrodes and a second sub group including odd-numbered scan electrodes, or a first sub group including scan electrodes located in an upper part and a second sub group including scan electrodes located in a lower part with respect to a central line of the first group.
During the sustain period, a sustain pulse having a sustain voltage Vs is alternately applied to the scan electrode and the sustain electrode to cause a sustain discharge in a surface-discharge type between the scan electrode and the sustain electrode.
Out of plural sustain signals alternately supplied to the scan electrode and sustain electrode in the sustain period, the first sustain signal or the last sustain signal may be larger in pulse width than the other sustain signals.
After the sustain discharge, the subfield may further include an erase period to erase wall charges remaining on the scan electrode and the sustain electrode of On-state cells selected during the address period by causing a weak discharge between the scan electrode and the sustain electrode.
The erase period may be included in the overall subfields or some subfields, and an erase signal for causing a weak discharge may be applied to an electrode to which the last sustain pulse is not applied during the sustain period.
The erase signal may include a gradually rising ramp signal, a low voltage wide pulse, a high voltage narrow pulse, an exponential signal, or a half-sinusoidal pulse.
Plural pulses may be sequentially applied to the scan electrode and the sustain electrode to cause a weak discharge.
The driving waveforms shown in
Referring to
The sustain electrode 110 may further include a connection electrode 113 that connects the electrode line 111 to the electrode line 112. The sustain electrode 120 may further include a connection electrode 123 that connects the electrode line 121 to the electrode line 122.
The electrode lines 111, 112, 121, and 122 intersect the discharge cell and extend in a direction of the plasma display panel. Each of the electrode lines may be formed to have narrow width to improve aperture ratio of the discharge cell. Also, plural electrode lines, for example such as the electrode lines 111, 112, 121, and 122, are used to improve discharge diffusion efficiency. In this case, the number of the electrode lines may be determined considering the aperture ratio.
The protruding electrodes 114, 115, 124, and 125 lower a discharge start voltage upon driving of the plasma display panel. More specifically, since the protruding electrodes 114 and 115 are located near the protruding electrodes 124 and 125, respectively, that is, the interval between the protruding electrodes 114 and 124 or between the protruding electrodes 115 and 125 is small, a discharge may easily initiate even with a low discharge start voltage, and therefore, the discharge start voltage may be lowered. The discharge start voltage may refer to a voltage which permits a discharge to initiate when a pulse is supplied to at least one of the sustain electrodes 110 and 120.
The connection electrodes 113 and 123 help a discharge created by the protruding electrodes 114, 115, 124, and 125 to easily spread toward the electrode lines 111 and 122, respectively, which are located far from the horizontal central line of the discharge cell.
As described above, the discharge start voltage may be lowered by the protruding electrodes 114, 115, 124, and 125, and discharge diffusion efficiency may be improved by the plural electrode lines 111, 112, 121, and 122. A consequence is improvement in emission efficiency of the plasma display panel. Accordingly, the ITO transparent electrodes may be removed without reduction in brightness of the plasma display panel.
Referring to
Table 1 shows variation in discharge start voltage according to the distances d1 and d2.
Referring to Table 1 and
However, when the distance d1 is more than 1.8 times the distance d2, as the distance d2 increases, the discharge start voltage abruptly increases, for example more than 187V.
Therefore, when the distance d1 ranges from more than about 1.8 times to about 4.6 times the distance d2, the discharge start voltage may be stably decreased less than about 180V.
In addition, the distance d1 may be about 2.1 times to about 2.8 times the distance d2 in order to ensure aperture ratio of the panel to prevent lowering in brightness of the panel and permit discharge to be uniformly created in the entire areas of the discharge cell.
Assuming the length of the protruding electrodes 114 and 124 is 50 um to 100 um, it can be seen from Table 1 that when the distance d1 is about 0.6 times to about 1.5 times the distance d4 between the two different electrode lines 112 and 121, the discharge start voltage may be stably reduced less than about 180V.
Assuming the distance d2 is constant, the distance d1 may be in inverse-proportion to the distance between the electrode line 111 and the barrier rib 100. As described above, as the distance d1 increases, the discharge occurring area may increase, but the discharge diffusion efficiency may decrease.
In a case where a discharge takes place only in part of the discharge cell, deterioration in image quality, for example, spots may occur in an image displayed on the panel.
Accordingly, when the distance d1 is about 1 time to about 1.7 times the distance d3, a discharge may occur in the entire areas of the discharge cell, and this may prevent deterioration in image quality occurring in an image displayed on the panel.
Referring to
In a case where the amount of wall charges created by an address discharge is different at the electrode line 111 and the electrode line 112, the amount of light emitted by a sustain discharge may be different according to location of the two electrode lines 111 and 112, and accordingly, deterioration in image quality, for example, spots may occur in an image displayed on the panel.
For example, wall charges are created at the electrode line 111, which is located far from the horizontal central line out of the two electrode lines 111 and 112, by spreading of discharge, and therefore, the amount of wall charges created at the electrode line 111 may be smaller than the amount of wall charges created at the electrode line 112, which is located near the horizontal central line. Accordingly, the amount of wall charges created at the electrode line 111 may be similar to the amount of wall charges created at the electrode line 112 by having the breadth b1 larger than the breadth b2.
As described above, a discharge may uniformly occur in the entire areas of the discharge cell by having the amount of wall charges created at the electrode line 111 similar to the amount of wall charges created at the electrode line 112, and this may reduce deterioration in image quality that may take place in an image displayed on the panel.
Table 2 shows the brightness and incidence of spots in an image displayed on the panel according to variation in the breadths b1 and b2.
Referring to Table 2, when the breadth b1 is more than 44 um, deterioration in image quality, such as spots, does not occur in a displayed image. In a case where the breadth b1 is more than 80 um, however, the brightness of the displayed image abruptly decreases less than 460 cd/m2.
Accordingly, when the breadth b1 is about 1.1 times to about 2 times the breadth b2, deterioration in image quality of the displayed image may be prevented and the improvement in brightness may be improved.
In addition, the breadth b1 may be about 1.15 times to about 1.5 times the breadth b2 so that the amount of wall charges created at the electrode line 111 may be similar to the amount of wall charges created at the electrode line 112 by increasing the amount of wall charges created at the electrode line 111 without greatly reducing the discharge diffusion efficiency.
As described above with reference to Table 1, the distance d1 may be about 180 um to about 230 um, and as described above with reference to Table 2, the breadth b1 may be about 44 um to about 80 um, and therefore, the distance d1 may be about 2.25 times to about 5.2 times the breadth b1.
By the above reasons, the breadth c1 of the electrode line 121 and the breadth c2 of the electrode line 122 may be different from each other within the above range.
Referring to
The protruding electrodes 214, 215, 224, and 225 thusly configured may increase surface area by which a discharge may take place between the protruding electrodes 214 and 215, and the protruding electrodes 224 and 225, and this may lead to improvement in discharge efficiency.
Table 3 shows the incidence of damage to electrode and the incidence of spots in a displayed image according to variation in the width w1 of the lower end of the protruding electrode 214.
Referring to Table 3, when the width w1 is 20 um, there does not occur any damage to the protruding electrode due to external pressure. In a case where the width w1 is more than 135 um, the distance between two adjacent protruding electrodes 214 and 224 is uneven, so that there may occur longitudinal stripe patterns on the displayed image.
Accordingly, when the width w1 is about 0.7 times to about 4.5 times the width w2, it can be possible to prevent any damage to the protruding electrode and reduce deterioration in image quality on the displayed image.
In addition, the width w1 may be about two times the width w2 to reduce the discharge start voltage and improve the discharge diffusion efficiency.
When the distance between the lower end of the protruding electrode 214 and the lower end of the protruding electrode 215 is about 0.9 times to about 2 times the width w1, it can be possible to ensure aperture ratio of the panel and uniformly create a discharge in the entire areas of the discharge cell.
Referring to
Referring to
The width a1 may be more than about 0.5 times the width a2 to improve contrast ratio as well as aperture ratio of the panel.
Referring to
The number of protruding electrodes 414, 415, 416, 424, 425, and 426 may be six or more, which are extended from electrode lines 412 and 421 that are located near the horizontal central axis of the discharge cell.
As described above, the plasma display panel device according to exemplary embodiments of the present invention may reduce manufacturing costs of the plasma display panel by removing necessity of transparent electrodes that are made of ITO, and reduce the incidence of uneven discharge between the scan electrode and the sustain electrode, which in turn may improve image quality of the panel, by having the ratio in width between the upper end and the lower end of the protruding electrode range from about 0.7 to about 4.5.
The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the foregoing embodiments is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2007-0116680 | Nov 2007 | KR | national |
| 10-2007-0116681 | Nov 2007 | KR | national |
| 10-2007-0116682 | Nov 2007 | KR | national |
