KR101065397B1 - Plasma display panel - Google Patents

Abstract

A plasma display panel, comprising: a first substrate and a second substrate disposed to face each other; A plurality of address electrodes formed on one surface of the first substrate; A first dielectric layer formed on a first substrate while covering the address electrodes; A partition wall disposed in a space between the first substrate and the second substrate and formed to partition a plurality of discharge cells; A phosphor layer formed in the discharge cell; A plurality of display electrodes arranged on one surface of the second substrate opposite to the first substrate in a direction crossing the address electrodes; A second dielectric layer formed on the second substrate while covering the display electrodes; A first passivation layer coating the second dielectric layer and including a low work function material; And a second passivation layer formed on the first passivation layer, the second passivation layer including a high work function material, wherein the second passivation layer is at least partially removed from a portion corresponding to the display electrode where a discharge occurs.

Plasma display panel of the present invention, while using a high-efficiency material as a protective film for protecting the dielectric layer, and further using a separate protective film for suppressing the reactivity of the high-efficiency material, it is possible to economically high brightness and low power consumption.

Protective film, SrCaO, Dielectric layer, PDP

Description

Plasma Display Panel {PLASMA DISPLAY PANEL}

The present invention relates to a plasma display panel.

In general, a plasma display panel (PDP) is a display device that realizes an image by using visible light generated by vacuum ultraviolet (VUV) radiation emitted from a plasma formed by gas discharge to excite a phosphor layer. The plasma display panel has a high resolution and large screen configuration, and has been spotlighted as a next generation thin display device.

The general structure of the plasma display panel is a three-electrode surface discharge type structure. The three-electrode surface discharge structure includes a front substrate on which a display electrode composed of two electrodes is formed and a back substrate on which an address electrode is formed at a predetermined distance from the substrate, wherein the display electrode is covered with a dielectric layer. Have The space between the front substrate and the rear substrate is partitioned into a plurality of discharge cells by partition walls, discharge gas is injected into the discharge cells, and a phosphor layer is formed on the rear substrate side.

In addition, due to the impact of positive ions during discharge, the dielectric layer formed on the front substrate is etched away and at this time, a metal material such as Na may short-circuit the electrode. To form a protective film. As the passivation layer, a MgO passivation layer that is resistant to the impact of (+) ions and has a high secondary electron emission coefficient and lowers the discharge start voltage is mainly used.

However, since the effect of lowering the discharge start voltage by the MgO protective film is not satisfactory, and the hygroscopicity of MgO is high, there is a possibility that the chromaticity of the phosphor is changed by discharge sputtering. Recently, studies for replacing MgO have been conducted.

One embodiment of the present invention to provide a plasma display panel capable of high brightness, low power consumption.

According to one embodiment of the invention, the first substrate and the second substrate disposed opposite to each other; A plurality of address electrodes formed on one surface of the first substrate; A first dielectric layer formed on a first substrate while covering the address electrodes; A phosphor layer disposed in a space between the first substrate and the second substrate and formed in the discharge cell to partition a plurality of discharge cells; A plurality of display electrodes disposed on one surface of the second substrate facing the first substrate in a direction crossing the address electrodes; a second dielectric layer formed on the second substrate while covering the display electrodes; A first passivation layer coating the second dielectric layer and including a low work function material; and a second passivation layer formed on the first passivation layer, the second passivation layer including a high work function material; The present invention provides a plasma display panel in which at least a portion is removed from a portion corresponding to the display electrode where the discharge occurs.

Other specific details of embodiments of the present invention are included in the following detailed description.

Plasma display panel according to an embodiment of the present invention is economical high brightness and low power consumption by using a high-efficiency material as a protective film for protecting the dielectric layer, and further using a separate protective film for suppressing the reactivity of the high-efficiency material. .

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

The present invention relates to a protective film formed to protect a dielectric layer in a plasma display panel.

Conventionally, MgO is used as a protective film covering the dielectric layer to protect the dielectric layer. However, as the research for reducing power consumption of the plasma display panel is further progressed, research for replacing MgO is being conducted.

One such material, such as SrCaO, has been studied. However, this material has high efficiency but has high reactivity with H ₂ O or CO _2, and loses good membrane properties at the time of exposure to the atmosphere during the process. One way to solve this problem is to deposit the protective film, and then perform the subsequent processes such as sealing and evacuation in a vacuum or inert atmosphere, which is difficult to implement in a production line and is too expensive to implement. There was a problem that practical application is impossible.

In the present invention, the problem due to the reactivity of SrCaO can be solved by a simple method using an additional protective film, and a plasma display panel showing high efficiency and low power consumption can be provided.

A plasma display panel according to a first embodiment of the present invention includes a first substrate and a second substrate facing each other; A plurality of address electrodes formed on one surface of the first substrate; A first dielectric layer formed on a first substrate while covering the address electrodes; A partition wall disposed in a space between the first substrate and the second substrate and formed to partition a plurality of discharge cells; A phosphor layer formed in the discharge cell; A plurality of display electrodes arranged on one surface of the second substrate opposite to the first substrate in a direction crossing the address electrodes; A second dielectric layer formed on the second substrate while covering the display electrodes; A first passivation layer coating the second dielectric layer and including a low work function material; and a second passivation layer formed on the first passivation layer, the second passivation layer including a high work function material; At least a portion of the portion corresponding to the display electrode where the discharge is generated is removed.

The second passivation layer may be removed at all portions corresponding to the display electrodes on the first passivation layer, and may be formed only at portions corresponding to the gaps between the display electrodes and the display electrodes. A part of the second passivation film may exist at a portion that intersects the partition wall. If the second protective film is formed on all of the corresponding portions on the display electrode, that is, covers all of the first protective film, the low voltage characteristic performance is difficult to develop, which is not preferable.

The second passivation layer is formed to cover the first passivation layer as a whole in the same process as the first formation layer during the manufacture of the second substrate, that is, the upper plate of the plasma display panel. Subsequently, the discharge sputtering is generated in the process of assembling, sealing off, and then aging the plasma display panel using a first substrate (lower plate) and a second substrate (top plate) in a conventional manner. By this discharge sputtering, the second protective film is removed, so that only the portion corresponding to the gap between the display electrode and the display electrode remains. If the second passivation film also remains on the display electrode, since the first passivation film is not exposed to the discharge space, the low voltage discharge characteristic performance is difficult to develop, which is not preferable.

The low work function material for forming the first passivation layer may be preferably one having a work function of 1 to 4 eV. These low work function materials include Sr _1-x Ca _x O (0 <x <1), SrO, BaO, CsO, CaO, ZnO, calcium aluminate And combinations thereof may be selected from the group consisting of. The low work function material has an advantage of very excellent life characteristics.

The thickness of the first protective film is preferably 300 to 1000 nm, more preferably 500 to 800 nm. When the thickness of the first passivation layer is thinner than 300 nm, the lower dielectric layer is exposed by the ion bombardment during discharge, causing a discharge failure, and when the thickness of the first passivation layer is larger than 1000 nm, cracks may occur in the passivation layer due to thin film stress, and the deposition time of the equipment is increased. It becomes long and there is a problem that mass productivity falls, and it is unpreferable.

The work function difference between the low work function material and the high work function material is preferably 1 eV or more, and more preferably 1 ev to 5 eV.

In addition, it is preferable that the adsorption amount of water (H ₂ O, OH ₋ ) or CO ₂ is different from each other, and the adsorption amount of the low work function material is more preferably two times or more. In particular, since the low work function material is highly reactive, it can react well with other materials, and has excellent adsorption capacity to moisture or CO ₂ . Therefore, it is preferable that the adsorption amount of the low work function material is two times or more higher than the adsorption amount of the high work function material, and more preferably two times to 500 times higher.

High work function materials having such work function differences include SiO ₂ , TiO ₂ , Ta ₂ O ₅ , ZrO ₂ , Al ₂ O ₃ , MoO ₂ , SiON, Si, Si ₃ N ₄ , a-SiO: H, a -SiN _x : H, a-Si: H, MgO, AlF ₃ , BaF ₂ , B ₂ O ₃ , CaF ₂ , CaSiO ₃ , CeF ₃ , Na ₅ Al ₃ F ₁₄ , Na ₃ AlF ₆ , LiF, Li ₂ One selected from the group consisting of O, MgF ₂ , KF, Sc ₂ O ₃ , NaCN, V ₂ O ₅ , YF 3, GeO ₂ , Y ₂ O _3, and a combination thereof can be preferably used. The high work function material is a single crystal growth material, and can effectively cap a low work function material for polycrystal growth, and can be effectively capped in comparison with MgO for polycrystalline growth, which is widely used as a protective film. have. The high work function material has a higher sputtering yield than MgO, which is widely used as a protective film. Therefore, the high work function material constituting the second passivation layer may be effectively removed at portions corresponding to the display electrodes when the plasma display apparatus is operated. In addition, since the high work function material has a high work function, it has low reactivity, excellent visible light transmittance, thin film deposition, and low thin film density. In addition, the high work function material is a material having a low secondary electron emission coefficient, typically having a high discharge voltage, and capable of inhibiting discharge. A second passivation layer formed of the high work function material is formed between the display electrode and the display electrode. When only present in the portion corresponding to the interval, the discharge is not spread to the unnecessary portion, the current is reduced, the efficiency can be increased.

By using a low work function material between the dielectric layer and the second passivation layer using the high work function material, secondary electrons may be emitted to reduce the discharge start voltage.

In the present invention, the second protective film preferably has a thickness of 5 to 300 nm, more preferably 10 to 100 nm. When the thickness of the second passivation layer is thinner than 5 nm, the first passivation layer may not be capped, and when the thickness of the second passivation layer is greater than 300 nm, the second passivation layer may not be removed at the portion to be removed during the discharge of the plasma display panel, and thus the performance of the first passivation layer may not be achieved. Is not desirable.

The plasma display panel may further include a third passivation layer having a high work function material formed under the first passivation layer to cover the dielectric layer. As such, when the third passivation layer is further included, a heat sealing process performed after the passivation layer is usually performed at a high temperature of about 480 ° C., so that contaminants such as residual carbon components or impurities generated in the dielectric layer contaminate the first passivation layer. Although there is a problem, since the third passivation layer is formed under the first passivation layer, it is possible to prevent such a contamination problem, and also has an effect of improving the adhesion between the first passivation layer and the dielectric layer and reducing the thin film stress of the first passivation layer. Do.

Preferably, the third passivation layer has a thickness of 10 to 3000 nm, and when the thickness of the third passivation layer is included in the above range, it is possible to prevent contamination from the dielectric layer and peel off the thin film due to stress without lowering productivity during mass production. This is preferable because it does not cause a problem such as a change in the discharge voltage.

In the present invention, the first passivation layer has a higher secondary electron emission coefficient than the second or third passivation layer, the difference is more preferably 0.1 to 0.6 when accelerated Ne ⁺ ions to 150eV. When the difference in the secondary tank emission coefficient is in the range of 0.1 to 0.6, the discharge voltage is lowered, and the amount of vacuum ultraviolet radiation can be increased.

The second protective film of the present invention is formed by covering the first protective film as a whole in the same process as the first protective film forming step. The formed second passivation layer is removed by sputtering during the aging process of the plasma display panel so that the second passivation layer exists only in the region between the display electrodes.

In this case, the material forming the second passivation layer may penetrate into the first passivation layer, and as a result, the first passivation layer formed on the portion of the first passivation layer corresponding to the display electrode may further include a high work function material. In addition, at this time, as the temperature is raised by ion bombardment in the discharge process of the plasma display panel, the material forming the second protective film penetrating into the first protective film and the material forming the first protective film react with each other to form a compound. It may be present at the interface between the first and second protective films. In addition, such a compound may be formed at the interface between the first and second protective films in the heat sealing process.

In addition, during the aging process, a portion of the first passivation layer formed on the portion of the first passivation layer corresponding to the display electrode may be removed to a thickness height, and thus may be thinner than the first passivation layer formed under the second passivation layer. . In this case, the thickness of the first passivation layer may be 5 to 500 nm.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 and 2 illustrate rear views of the upper plate of the plasma display panel according to the first embodiment of the present invention.

As shown in FIG. 1, when the first protective film is formed, the second protective film is formed while covering the first protective film, and the aging of the plasma display panel is performed, sputtering is performed only at a portion corresponding to the display electrode where discharge occurs. 2 In the portion where the protective film is removed to correspond to the bus electrode and the transparent electrode, the first protective film 5 is exposed, and a portion other than that, i.e., a portion corresponding to the gap between the display electrode including the bus electrode and the transparent electrode and the display electrode It can be seen that the first passivation layer is not exposed, and only the second passivation layer 7 is visible.

The structure of only the first and second passivation layers is shown in FIG. 2 in order to more clearly indicate the positions of the first and second passivation layers according to the first embodiment. As shown in FIG. 2, the second passivation layer 7 is formed on the first passivation layer 5, and the second passivation layer is removed in the region a, which is the first passivation layer formed in the portion corresponding to the electrode. It can be seen that 5) is exposed. In this case, the thickness of the second protective film is preferably 5 to 300 nm, and the thickness of the first protective film is preferably 300 to 1000 nm. Since the thickness of the second passivation layer is thinner than the thickness of the first passivation layer, electrons emitted from the first passivation layer may be smoothly supplied to the discharge space.

3 is a cross-sectional view of the upper plate of the plasma display panel according to the second embodiment of the present invention. As shown in FIG. 3, in the second embodiment of the present invention, display electrodes 31 including a pair of transparent electrodes 31a and a bus electrode 31b are formed on the front substrate 30. The dielectric layer 33 is positioned on the entire front substrate 30 while covering the electrodes 31. In addition, a second passivation layer 37 is formed on the first passivation layer 35 while not covering the dielectric layer 33 and is not formed in the gap between the display electrode 31 and the display electrode. The third passivation layer 39 is formed while covering the dielectric layer 33 under the 35.

4 illustrates a structure of only the first to third passivation layers in order to more clearly indicate the positions of the first to third passivation layers according to the second embodiment. As shown in FIG. 4, the second passivation layer 38 is positioned above the first passivation layer 37, and the third passivation layer 39 is positioned below the first passivation layer 37. The thickness of the first protective film is preferably 300 to 1000 nm, the thickness of the second protective film is preferably 5 to 300 nm, and the thickness of the third protective film is preferably 10 to 3000 nm.

5 illustrates a structure of the first to third protective films of the plasma display panel according to the third embodiment of the present invention. As shown in FIG. 5, in the third embodiment of the present invention, the second passivation layer 53 is positioned on the upper portion of the first passivation layer 50, and the third passivation layer 55 is positioned on the lower portion of the first passivation layer 50. A portion of the first passivation layer 50 is removed. That is, a portion of the first passivation layer 50 positioned on the display electrodes is removed, and the thickness b of the removed first passivation layer 50 is 5 to 500 nm.

Of course, the thickness of the first passivation layer 50 under the second passivation layer 53 is 300 to 1000 nm.

6 illustrates a structure of the first to third passivation layers of the plasma display panel according to the fourth embodiment of the present invention. As shown in FIG. 6, in the fourth embodiment of the present invention, the second passivation layer 63 is positioned on the upper portion of the first passivation layer 60, the third passivation layer 65 is positioned on the lower portion of the first passivation layer 60, and a part of the first passivation layer is disposed. In the form of the material constituting the second protective film. That is, the region 67 includes a mixture of materials constituting the second passivation layer in the first passivation layer formed at a portion corresponding to the display electrode.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.

(Example 1)

A transparent electrode was formed on the front substrate made of soda-lime glass using an indium tin oxide conductor material, and a bus electrode was formed on the transparent electrode by using a composition for forming a bus electrode containing Ag. A display electrode composed of a bus electrode was formed by a conventional method.

Subsequently, the dielectric layer-forming composition including the glass powder of PbO-B ₂ O ₃ -SiO ₂ was coated over the entire surface of the front substrate on which the display electrode was formed and baked to form a dielectric layer.

Sr _1-x Ca _x O (x = 0.38) was deposited on the dielectric layer to form a first passivation layer having a thickness of 800 nm. Subsequently, SiO 2 was deposited on the first protective film by electron beam evaporation to form a second protective film having a thickness of 30 nm. At this time, the work function of Sr _1-x Ca _x O (x = 0.38) was 1.5 eV, the secondary electron emission coefficient was 0.5, the work function of SiO ₂ was 5 eV, and the secondary electron emission coefficient was 0.1.

The relative strength of each element was measured from the SiO ₂ of the second protective layer on the surface to the depth direction by using the SIMS (Secondary Ion Mass Spectrometry) method. As a result, Sr _1-x Ca _x O (x = 0.38) was obtained. The strength of OH obtained in the first protective film was about 300 times higher than that obtained in the second protective film of SiO ₂ , and the strength of C was about 10 times higher. As the result, the amount of water adsorption in the first protective film of _{Sr 1-x Ca x O (} x = 0.38) was higher by about 300-fold compared to the water absorption amount in the second protective layer of SiO _2, for the CO ₂ It can be seen that the adsorption power is about 10 times better.

In addition, the water solubility of the Sr _1-x Ca _x O (x = 0.38) was 3.8 g / 100 ml, and SiO ₂ was about 0.012 g / 100 ml.

(Comparative Example 1)

A transparent electrode was formed on the front substrate made of soda-lime glass using an indium tin oxide conductor material, and a bus electrode was formed on the transparent electrode by using a composition for forming a bus electrode containing Ag. A display electrode composed of a bus electrode was formed by a conventional method.

Subsequently, the dielectric layer-forming composition including the glass powder of PbO-B ₂ O ₃ -SiO ₂ was coated over the entire surface of the front substrate on which the display electrode was formed and baked to form a dielectric layer.

(Comparative Example 2)

The same process as in Example 1 was carried out except that a protective film having a thickness of 800 nm was formed by depositing Sr _1-x Ca _x O (x = 0.38) on the dielectric layer by electron beam deposition.

(Comparative Example 3)

Except for depositing Sr _1-x Ca _x O (x = 0.38) on the dielectric layer by electron beam evaporation to form a first passivation layer having a thickness of 800 nm, and depositing MgO by electron beam evaporation to form a second passivation layer having a thickness of 30 nm. It carried out similarly to Example 1 above.

The emission efficiency was measured while changing the sustain voltage of the plasma display panel manufactured according to Example 1 and Comparative Examples 1 to 2, and the results are shown in FIG. 7. As shown in Fig. 7, the plasma display panel having the dielectric layer, the first and the second passivation layer of Example 1 exhibits high luminous efficiency even at a low holding voltage, and thus it can be expected that low voltage discharge is possible. On the other hand, in the case of Comparative Example 2 having only an Sr _1-x Ca _x O (x = 0.38) protective film, it was found that the luminous efficiency was lower than that of Comparative Example 1 without a protective film.

SEM photographs of the protective films formed in Example 1 and Comparative Examples 2 to 3 are shown in Fig. 8, respectively (b), (a) and (c). As shown in (a) of FIG. 8, the Sr _1-x Ca _x O (x = 0.38) protective film formed in Comparative Example 2 had a rough surface, that is, a surface having a large surface roughness because it exhibits a polycrystalline growth surface. Able to know.

In the case of Example 1 in which the SiO ₂ second protective film is formed on the Sr _1-x Ca _x O (x = 0.38) first protective film, the surface roughness of the first protective film is changed as SiO ₂ is a thin film that performs amorphous growth. That is, since the step coverage is excellent and the surface of the first passivation layer is uniformly capped, it can be predicted that the first passivation layer can be effectively suppressed from directly reacting with external moisture or CO ₂ .

In contrast, as shown in FIG. 8C, when the MgO second protective film is formed in the Sr _1-x Ca _x O (x = 0.38) first protective film, the first protective film is formed by MgO also growing polycrystalline. It can be seen that it is not possible to cap the irregular surface of the uniformly, thus still showing a rough surface. Accordingly, it can be predicted that the first protective film cannot be effectively inhibited from directly reacting with external moisture or CO ₂ .

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

1 is a view showing a top structure after aging of a plasma display panel according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the plasma display panel shown in FIG. 1. FIG.

3 is a cross-sectional view schematically showing only the structures of the first and second passivation layers of the plasma display panel according to the first embodiment of the present invention.

4 is a cross-sectional view schematically showing the structure of the first and second protective film according to the second embodiment of the present invention.

5 is a cross-sectional view schematically showing the structure of the first and second protective film according to the third embodiment of the present invention.

6 is a cross-sectional view schematically showing the structure of the first and second protective film according to the fourth embodiment of the present invention.

7 is a graph showing the measurement of the luminous efficiency of the plasma display panel manufactured according to Example 1 and Comparative Examples 1 to 2 of the present invention.

8 is a SEM photograph of the protective film formed in Example 1 and Comparative Examples 2 to 3 of the present invention.

Claims (16)

A first substrate and a second substrate disposed to face each other; A plurality of address electrodes formed on one surface of the first substrate; A first dielectric layer formed on a first substrate while covering the address electrodes; A partition wall disposed in a space between the first substrate and the second substrate and formed to partition a plurality of discharge cells; A phosphor layer formed in the discharge cell; A plurality of display electrodes arranged on one surface of the second substrate opposite to the first substrate in a direction crossing the address electrodes; A second dielectric layer formed on the second substrate while covering the display electrodes; A first passivation layer coating the second dielectric layer and including a low work function material having a work function of 1 eV to 4 eV; And A second passivation layer formed on the first passivation layer, the second passivation layer including a high work function material; At least a portion of the second passivation layer is removed from a portion corresponding to the display electrode where the discharge is generated. And a work function difference between the low work function material and the high work function material is 1 to 5 eV. The method of claim 1, And the second passivation layer is formed on a portion corresponding to a gap between the display electrode and the display electrode. delete The method of claim 1, The low work function material is selected from the group consisting of Sr _1-x Ca _x O (0 <x <1), SrO, BaO, CsO, CaO, ZnO, calcium aluminate, and combinations thereof. The method of claim 1, And a third passivation layer under the first passivation layer, the third passivation layer including a high work function material having a work function 1 to 5 eV higher than the low work function material. 6. The method according to claim 1 or 5, The high work function material is SiO ₂ , TiO ₂ , Ta ₂ O ₅ , ZrO ₂ , Al ₂ O ₃ , MoO ₂ , SiON, Si, Si ₃ N ₄ , a-SiO: H, a-SiN _x : H, a-Si: H, MgO, AlF ₃ , BaF ₂ , B ₂ O ₃ , CaF ₂ , CaSiO ₃ , CeF ₃ , Na ₅ Al ₃ F ₁₄ , Na ₃ AlF ₆ , LiF, Li ₂ O, MgF ₂ , KF , Sc ₂ O ₃ , NaCN, V ₂ O ₅ , YF ₃ , GeO ₂ , Y ₂ O ₃ and a combination thereof. delete delete 6. The method according to claim 1 or 5, The adsorption amount of water or CO ₂ of the low work function material is 2 to 500 times higher than the adsorption amount of the high work function material. delete The method of claim 1, The first protective film has a thickness of 300 to 1000nm. The method of claim 1, The second passivation layer is a plasma display panel having a thickness of 5 to 300nm. The method of claim 5, The third passivation layer has a thickness of 10 to 3000nm. The method of claim 1, And the first passivation layer has a higher secondary electron emission coefficient than the second passivation layer. The method of claim 5, And the first passivation layer has a higher secondary electron emission coefficient than the third passivation layer. The method of claim 1, And a portion of the first passivation layer formed on a portion of the first passivation layer corresponding to the display electrode is removed.

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