Front substrate of plasma display panel

Abstract

Provided is a front substrate of a plasma display panel. The front substrate includes a front glass substrate; a number of pairs of first electrodes which are formed in parallel with each other on the front glass substrate, and are made of a transparent conductive material; a number of pairs of second electrodes which are formed in parallel with each other on the front glass substrate, and are made of a material whose specific resistance is relatively smaller than that of the material of the first electrode; and a number of auxiliary electrodes which electrically connects the first electrodes with the second electrodes, to thereby make an area of the first electrode contribute to brightness and to thus raise a contrast ratio and improve a luminous efficiency greatly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of the present invention will become more apparent by describing the preferred embodiment thereof in more detail with reference to the accompanying drawings in which:

FIG. 1 is a perspective view showing a part of a conventional plasma display panel;

FIG. 2 is a plan view showing an electrode structure which is formed on the front substrate of the plasma display panel illustrated in FIG. 1;

FIGS. 3A through 4B are plan views and cross-sectional views showing a front substrate structure in which a black stripe is added in the conventional plasma display panel, respectively;

FIG. 5 is a plan view showing structure of the front substrate of a plasma display panel according to a first exemplary embodiment of the present invention;

FIG. 6 is a plan view showing a modified exemplary embodiment in which position of auxiliary electrodes are changed in the front substrate of the plasma display panel shown in FIG. 5;

FIG. 7 is a plan view showing a modified exemplary embodiment in which the number of auxiliary electrodes is changed in the front substrate of the plasma display panel shown in FIG. 5;

FIGS. 8A and 8B are plan views showing a modified exemplary embodiment in which shapes of the first electrodes are changed in the front substrate of the plasma display panel shown in FIG. 5;

FIGS. 9A and 9B are a plan view and a cross-sectional view showing a front substrate structure in which a black stripe is added in the plasma display panel according to a second exemplary embodiment of the present invention, respectively; and

FIGS. 10A and 10B are graphical views showing a luminous efficiency and a brightness characteristic of the plasma display panel according to the present invention through experiments, respectively.

DETAILED DESCRIPTION OF THE INVENTION

A front substrate of a plasma display panel according to respective embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 5 is a plan view showing structure of the front substrate of a plasma display panel according to a first exemplary embodiment of the present invention.

Referring to FIG. 5, the front substrate of the plasma display panel according to the first exemplary embodiment of the present invention includes a front glass substrate (not shown), a number of scanning electrodes 50 which are formed in parallel with each other on the front glass substrate, and a number of sustain electrodes 60 which are formed in parallel with each other on the front glass substrate, and are formed in opposition to the number of scanning electrodes 50 so that discharge can occur between the number of scanning electrodes 50 and the number of sustain electrodes 60.

Here, as illustrated in FIG. 5, plasma discharge occurs in discharge gas by a voltage difference between the scanning electrodes 50 and the sustain electrodes 60. The scanning electrodes 50 and the sustain electrodes 60 are made of first electrodes 20 and second electrodes 10, in which the first electrodes 20 are respectively made of a transparent material, for example, indium tin oxide (ITO) or SnO₂, and the second electrodes 10 are respectively made of a material whose specific resistance is relatively smaller than that of the first electrodes 20, for example, a conductive material having one selected from the group consisting of Ag, Al, Cr, and Cu as a main ingredient. Here, the second electrodes 10 are bus electrodes on which a number of auxiliary electrodes 30 are extensively formed so that the second electrodes 10 are formed in parallel with each other adjacent to the first electrodes 20 and electrically connected with the first electrodes 20 in respective cells.

Here, the second electrodes 10 are arranged at the outside of the first electrodes 20. This is because there is no need to have the lines of the second electrodes 10 on the first electrodes 20 as in the conventional art, due to the auxiliary electrodes 30 which are connected with the second electrodes 10 and electrically contact the first electrodes 20.

In addition, as illustrated in FIG. 5, main electrodes which are horizontally arranged from the second electrodes 10 may be formed to have a certain gap “A” while adjoining with the first electrodes 20. Although it is not shown in the drawing, part of the second electrodes 10 may be overlapped over the first electrodes 20.

Therefore, according to the present invention, since the first electrodes 20 need not be located below the second electrodes 10, the first electrodes 20 are disposed at a distance from the second electrodes 10, or part of the first electrodes 20 are disposed to overlap the second electrodes 10. Accordingly, an area of the first electrodes 20 may contribute in brightness more effectively.

FIG. 6 is a plan view showing a modified exemplary embodiment in which position of auxiliary electrodes are changed in the front substrate of the plasma display panel shown in FIG. 5.

First, positions of the auxiliary electrodes 30 can be located in discharge cells 20A, as shown in FIG. 5, or can be located in portions crossing barrier ribs 40 as illustrated in FIG. 6.

Thus, if the auxiliary electrodes 30 are located at portions crossing the barrier ribs 40, as illustrated in FIG. 6, an area of light transmittance cells 20B widens relatively in comparison with the discharge cells 20A illustrated in FIG. 5, to thereby improve an aperture ratio.

Here, it is preferable that the length of each auxiliary electrode 30 is not protruded from the respective first electrodes 20, in order to avoid inferiority of electric short-circuit, etc.

FIG. 7 is a plan view showing a modified exemplary embodiment in which the number of auxiliary electrodes is changed in the front substrate of the plasma display panel shown in FIG. 5. The auxiliary electrodes 30A can be located for respective cells 20A as shown in FIG. 5, as well as can be located one by one for several cells 20A as illustrated in FIG. 7.

FIGS. 8A and 8B are plan views showing a modified exemplary embodiment in which shapes of the first electrodes are changed in the front substrate of the plasma display panel shown in FIG. 5. Even in the case of the respective transparent electrodes where the first electrodes 25 and 25a are segment type, respectively, the auxiliary electrodes 30 can be connected with the respective cells as shown in FIGS. 8A and 8B.

FIGS. 9A and 9B are a plan view and a cross-sectional view showing a front substrate structure in which a black stripe is added in the plasma display panel according to a second exemplary embodiment of the present invention, respectively.

First, a plasma display panel includes: a front glass substrate; a number of pairs of first electrodes 20 and 20a which are formed in parallel with each other on the front glass substrate, and are made of a transparent conductive material in which plasma discharge is performed in discharge gas filled in respective cells; a number of pairs of second electrodes 10 and 10a which are formed in parallel with each other on the front glass substrate, and are made of a material whose specific resistance is relatively smaller than that of the material of the first electrodes 20 and 20a, in which the second electrodes are formed in parallel with the first electrodes so as to partially overlap with or adjoin at a certain distance from the first electrodes 20 and 20a; and a number of auxiliary electrodes 30 and 30′ which are extensively formed from the second electrodes 10 and 10a, to thus electrically connect the first electrodes 20 and 20a with the second electrodes 10 and 10a.

Here, in the case that gaps between the first electrodes 20 and 20a and the second electrodes 10 and 10 are too big, the line width of the transparent electrodes required for discharge cannot be secured sufficiently. Thus, it is preferable that the gaps between the first electrodes 20 and 20a and the second electrodes 10 and 10 are limited to 200 μm or less which is half of the line width of the first electrodes 20 and 20a being the transparent electrodes.

Referring to FIGS. 9A and 9B, in order to improve a contrast ratio, black stripes 70 which are located down to the lower portions of the second electrodes 10 and 10a are formed between a pair of the first electrodes 20 and a neighboring first electrode 20a. The black stripes 70 are formed adjacent to the first electrodes 20 and 20a including the lower portions of the second electrodes 10 and 10a, to thus further improve a contrast ratio.

According to the present invention, this is because the second electrodes 10 and 10a which are the bus electrodes are separated from the first electrodes 20 and 20a which are the transparent electrodes, and the first electrodes 20 and 20a and the second electrodes 10 and 10a are connected through the auxiliary electrodes 30, to thereby enlarge an area even at the lower portions of the second electrodes 10 and 10a and to thus dispose the black stripes 70 having no electric conductivity.

That is, in the case of the conventional art shown in FIGS. 3A, 3B, 4A and 4B, the second electrodes 10 and 10a should be detached from the black stripes 70. But, in the present invention, the areas of the black stripes 70 can be extended and connected to the lower portions of the second electrodes 10 and 10a.

Thus, the present invention can greatly widen an area that black color occupies in the whole area of the PDP panel, through an extended black stripe area and can use a material having a sufficient black color degree with no electrical conductivity as a material of the black stripes 70, so as to be formed thick, to thereby greatly heighten a black color degree and a contrast ratio of a plasma display device.

Here, since the auxiliary electrodes 30 should contact the first electrodes 20 and 20a, it is advantageous that the auxiliary electrodes 30 are made of only a conductive material such as Ag. However, the lower layers of the auxiliary electrodes 30 may be made of a black color material having electric conductivity, in order to further heighten a black color degree.

In addition, the auxiliary electrodes 30 may have a function of electrically connecting between the first electrodes 20 and 20a and the second electrodes 10 and 10a. Accordingly, the auxiliary electrodes 30 need not correspond to all cells 20A and 20B on a one-to-one basis as shown in FIGS. 5 and 6. As a result, an electrically conductive material is applied only to part of the auxiliary electrodes 30, and a black color material having no electric conductivity is applied to the other parts of the auxiliary electrodes 30.

Meanwhile, in the front substrate of the plasma display panel having the above-described structure, the positions and structures between the first electrodes 20 and 20a, the second electrodes 10 and 10a, and the auxiliary electrodes 30 influence upon the characteristics of the plasma display panel. The characteristics of the plasma display panel are changed according to how the positions and structures between the first electrodes 20 and 20a, the second electrodes 10 and 10a, and the auxiliary electrodes 30 are designed.

Here, in the present invention, an experiment has been executed to optimize the characteristics of the plasma display panel. An example of designing the first electrodes 20 and 20a, the second electrodes 10 and 10a, and the auxiliary electrodes 30 is illustrated in the following Table 1. The characteristics depending upon the design values are illustrated in FIGS. 10A and 10B as well as the following Table 2.

First, referring to FIG. 5, “A” denotes a gap between the second electrode 10 and the first electrode 20, “B” denotes a protruded length of the auxiliary electrode 30, “C” denotes the line width of the auxiliary electrode 30, and “D” denotes the relative position between the auxiliary electrode 30 and the barrier ribs 40, in which their design values are illustrated in the following Table 1.

	TABLE 1
	Conventional art	Present invention
Width of 1st electrode	320 μm	270 μm
Gap between 1st	80 μm	80 μm
electrodes
Width of 2nd electrode	100 μm	100 μm
Auxiliary electrode	—	A: 0 μm	B: 200 μm
		C: 70 μm	D: 0 μm
Width of barrier ribs	70 μm	70 μm

Characteristics of a luminous efficiency and a contrast ratio of the plasma display panel according to the present invention will be described comparing with the conventional technology.

First, the characteristics of the luminous efficiency and brightness of the plasma display panel which has been manufactured according to the above-described structure of the present invention and the conventional plasma display panel are illustrated in FIGS. 10A and 10B.

Referring to FIGS. 10A and 10B, when the graph (-◯-) showing the characteristics of the luminous efficiency and brightness of the plasma display panel according to the present invention is compared with the graph (-♦-) of the conventional art, it can be seen that the present invention has been improved more than about 10% than the conventional art.

In Table 2, a contrast ratio of the plasma display panel according to the present invention is compared with the conventional plasma display panel.

Referring to Table 2, the contrast ratio of the plasma display panel which has been manufactured according to the present invention is much higher than that of the conventional plasma display panel.

	TABLE 2
	Reflected luminance	Display luminance	Contrast ratio
Conventional	15 cd/m2	432 cd/m2	29:1
art
Present	12 cd/m2	529 cd/m2	44:1
invention

Therefore, in the front substrate of the plasma display panel according to the present invention of the above-described structure, a number of the auxiliary electrodes 30 and 30′ which electrically connect the second electrodes 10 and 10a and the first electrodes 20 and 20a are extensively formed with respect to the second electrodes 10 and 10a. Accordingly, the whole area of the second electrodes are placed on the first electrodes in the conventional art, but only the extreme part of the second electrodes 10 and 10a is placed on the first electrodes 20 and 20a in the present invention. As a result, the present invention can reduce an ineffective power consumption by a portion which is hidden by the second electrodes 10 and 10a, to thereby improve a luminous efficiency, that is, brightness per unit power consumption. As being the case, all the area of the first electrodes 20 and 20a can contribute 100% in brightness without being screened by the second electrodes 10 and 10a, to thereby heighten a contrast ratio and greatly improve a luminous efficiency which is the biggest solution subject of the plasma display panel.

Thus, the present invention can greatly widen an area that black color occupies in the whole area of the PDP panel, through an extended black stripe area and can use a material having a sufficient black color degree with no electrical conductivity as a material of the black stripes 70, so as to be formed thick, to thereby greatly heighten a black color degree and a contrast ratio of a plasma display device.

As described above, according to the present invention, the transparent electrodes and the bus electrodes are electrically connected with each other, and the auxiliary electrodes of a form which are arranged vertically with respect to the transparent electrodes, so that the area of the transparent electrodes can contribute in brightness more effectively, to thus greatly improve a luminous efficiency, and to thus greatly improve a black color degree and a contrast ratio of the PDP panel through an extended black stripe area.

As described above, the present invention has been described with respect to particularly preferred embodiments. However, the present invention is not limited to the above embodiments, and it is possible for one who has an ordinary skill in the art to make various modifications and variations, without departing off the spirit of the present invention and within the equivalent to the scope of the following claims.

Claims

1. A front substrate of a plasma display panel comprising: a front glass substrate;a number of pairs of first electrodes which are formed in parallel with each other on the front glass substrate, and are made of a transparent conductive material in which plasma discharge is performed in discharge gas filled in respective cells;a number of pairs of second electrodes which are formed in parallel with each other on the front glass substrate, and are made of a material whose specific resistance is relatively smaller than that of the first electrodes, in which the second electrodes are formed in parallel with the first electrodes so as to partially overlap with or adjoin to the first electrodes; anda number of auxiliary electrodes which electrically connects the first electrodes with the second electrodes.

2. The front substrate of a plasma display panel according to claim 1, wherein the auxiliary electrodes are formed so that they are not projected to the outside of the first electrodes to thereby prevent a short-circuit.

3. The front substrate of a plasma display panel according to claim 1 or 2, wherein the first electrodes are respectively made of indium tin oxide (ITO) or SnO2, and the second electrodes are respectively made of a conductive material having one selected from the group consisting of Ag, Al, Cr, and Cu as a main ingredient.

4. The front substrate of a plasma display panel according to claim 1, wherein the first electrodes are a bar type or a segment type with a number of projections, respectively.

5. The front substrate of a plasma display panel according to claim 1, wherein a number of the auxiliary electrodes do not correspond to the first electrodes on a one-to-one basis necessarily in every discharge cell, respectively but correspond to the first electrodes while jumping over a number of the discharge cells, respectively.

6. The front substrate of a plasma display panel according to claim 1, wherein a part of the number of the auxiliary electrodes are made of an electrically conductive material and the other parts are made of a black color material.

7. The front substrate of a plasma display panel according to claim 1, wherein a black stripe is further formed between the first electrode pair and the neighboring first electrode pair for improvement of a contrast ratio, and the black stripe is widely formed extensively to an area including the lower portion of the second electrode pair.