JP4282885B2 - Low melting point glass for electrode coating and plasma display device - Google Patents

Description

【００５８】
【表２】

【００５９】
【発明の効果】
本発明のガラスを用いることにより、ガラス基板上の透明電極を被覆するガラス層の透明性を高くできる。また、前記ガラス層中の炭素含有不純物残存量が減少しＰＤＰにおける輝度低下が起りにくくなる。さらに、ガラス基板上の銀電極を被覆するガラス層の銀発色現象を抑制できる。また、電極を被覆するガラス層の比誘電率を小さくできる。
【００６０】
本発明のＰＤＰにおいては、その前面基板の透過率が高く、画質が優れている。また、輝度低下が起りにくい。さらに、前面基板の銀電極を被覆するガラス層の銀発色現象を抑制でき、この点でも画質が向上する。また、消費電力も低減できる。
【図面の簡単な説明】
【図１】本発明のプラズマディスプレイ装置を示す断面図。
【符号の説明】
１ａ：ガラス基板
１ｂ：ガラス基板
２：透明電極
３：ガラス層
４：蛍光体層
５：アドレス用電極
６：隔壁
７：放電空間
１０：前面基板
２０：背面基板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low-melting glass suitable for insulatingly coating a transparent electrode such as ITO (indium oxide doped with tin) or tin oxide, and a plasma display device.
[0002]
[Prior art]
In recent years, thin flat panel color display devices have attracted attention. In such a display device, an electrode must be formed in each pixel in order to control the display state in the pixel forming the image. In order to prevent deterioration in image quality, a transparent electrode is used as the electrode. As the transparent electrode, an ITO or tin oxide thin film formed on a glass substrate is often used. As used herein, tin oxide includes tin oxide doped with fluorine, antimony, or the like.
[0003]
The transparent electrode formed on the surface of the glass substrate used as the display surface of the display device is processed into a thin line shape in order to realize a fine image. And in order to control each pixel independently, it is necessary to ensure the insulation between such finely processed transparent electrodes. However, when moisture is present on the surface of the glass substrate or when an alkali component is present in the glass substrate, a slight current may flow through the surface of the glass substrate. In order to prevent such a current, it is effective to form an insulating layer between the transparent electrodes. Further, in order to prevent deterioration of the image quality due to the insulating layer formed between the transparent electrodes, the insulating layer is preferably transparent.
[0004]
Various insulating materials for forming such an insulating layer are known. Among them, glass materials that are transparent and highly reliable insulating materials are widely used.
In a plasma display device (hereinafter referred to as PDP), which has recently been expected as a large flat color display device, cells are typically defined by a front substrate, a rear substrate and a partition wall used as a display surface. An image is formed by generating a plasma discharge in the cell. A transparent electrode is formed on the surface of the front substrate. In order to protect the transparent electrode from plasma, it is essential to cover the transparent electrode with glass having excellent plasma durability.
[0005]
[Problems to be solved by the invention]
The glass used for such electrode coating is usually used as a glass powder. That is, if necessary, a filler or the like is added to the glass powder to form a paste, and the glass paste thus obtained is applied to a glass substrate on which the transparent electrode is formed and baked to cover the transparent electrode. To do.
[0006]
In addition to electrical insulation, such an electrode coating glass has a softening point of, for example, 650 ° C. or less, a linear expansion coefficient of, for example, about 80 × 10 ⁻⁷ / ° C., and is obtained by firing. The transparency of the electrode-coated glass layer is required, and various glasses have been proposed. For example, JP-A-11-180726 discloses PbO + Bi ₂ O ₃ : 52 to 68%, B ₂ O ₃ : 14 to 28%, SiO ₂ : 0 to 5%, ZnO: 6 to 23 in terms of mass percentage. %, Al ₂ O ₃ : 0 to 8%, CeO ₂ : 0 to 5%, SnO ₂ : 0 to 5%.
[0007]
However, in recent years, there has been a demand for further improvement in image quality in the PDP, and accordingly, the transparency of the electrode-coated glass layer is required to be further increased.
An object of this invention is to provide the low melting glass for electrode coating and plasma display apparatus for solving this subject.
[0008]
[Means for Solving the Problems]
The present invention is expressed in mass percentage based on the following oxides, and is substantially PbO 25-85%, B ₂ O ₃ 10-60%, SiO ₂ 2-40%, Al ₂ O ₃ 0-25%, Bi ₂ O ₃ 0-35%, MgO 0-40%, CaO 0-40%, SrO 0-40%, BaO 0-40%, ZnO 0-4%, Li ₂ O 0-20%, Na ₂ O 0 _{~20%, K 2 O 0~20%} , CuO 0.2~0.9%, made a MgO + CaO + SrO + BaO 0 to 40% low-melting glass for covering electrodes, which do not contain any Mo and Sb, the provide.
[0009]
The present invention also provides a plasma display device having a front substrate, wherein a transparent electrode on a glass substrate constituting the front substrate is coated with the low-melting glass for electrode coating.
[0010]
The present inventor presumed that one of the causes of the decrease in the transparency of the electrode-coated glass layer in the PDP was the remaining carbon-containing impurities described below in the electrode-coated glass layer, leading to the present invention.
The low melting point glass for electrode coating is usually used in the form of powder. The low melting point glass powder for electrode coating is made into a glass paste using an organic vehicle or the like for imparting printability, and this glass paste is applied onto an electrode formed on a glass substrate and fired to coat the electrode. .
[0011]
The electrode-coated glass layer obtained by firing is often colored brown or black even when it does not contain a coloring component such as a transition metal. This phenomenon is considered to be a phenomenon in which carbon-containing impurities contained in the organic vehicle or the like remain in the electrode-coated glass layer, and the carbon-containing impurities color the electrode-coated glass layer. Note that the brown coloration typically reduces the transmittance of light having a wavelength of 400 nm.
This carbon-containing impurity reacts with water or the like present in the electrode-coated glass layer and is released from the electrode-coated glass layer as carbon dioxide gas when plasma is generated in the PDP, thereby reducing the brightness of the PDP. I think that.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The low melting point glass for electrode coating of the present invention (hereinafter simply referred to as the glass of the present invention) is usually used in the form of powder. The glass powder of the present invention is made into a glass paste using an organic vehicle or the like for imparting printability, and this is applied onto an electrode formed on a glass substrate and fired to coat the electrode. Here, the organic vehicle is obtained by dissolving a binder such as ethyl cellulose in an organic solvent such as α-terpineol. The glass of the present invention is typically lead glass or lead borate glass.
In the PDP, the glass of the present invention is suitably used for coating the transparent electrode of the front substrate.
[0013]
The average particle size of the powder is preferably 0.5 μm or more. When the thickness is less than 0.5 μm, there is a risk that the number of bubbles in the electrode-coated glass layer obtained by firing increases and the transparency is lowered, and there is a possibility that the time required for making the powder is remarkably increased. More preferably, it is 0.7 μm or more.
[0014]
The maximum particle size of the powder is preferably 35 μm or less. The thickness of the electrode-coated glass layer in the PDP is usually 40 μm or less. However, if the maximum particle size exceeds 35 μm, the surface of the electrode-coated glass layer may be uneven and the PDP image may be distorted. The maximum particle size is more preferably 20 μm or less.
[0015]
The softening point of the glass of the present invention is preferably 450 to 650 ° C. The reason is described below.
As the glass substrate, one having a glass transition point of 550 to 620 ° C. is usually used. In this case, in order to avoid deformation of the glass substrate, the baking of the glass paste is performed at 620 ° C. or lower. In order to perform baking at 620 ° C. or lower, the softening point of the glass of the present invention is preferably 650 ° C. or lower. In addition, the softening point is 650 ° C. or less in order to prevent deterioration of the electrical characteristics of the electrode during firing by the glass of the present invention softening and flowing in the early stage of firing and completely covering the electrode. Is preferred. More preferably, it is 640 degrees C or less, Most preferably, it is 630 degrees C or less.
[0016]
On the other hand, on the front substrate of the PDP, when the electrical resistance is too high with only a transparent electrode such as ITO or tin oxide, a metal layer such as Ag, Al, or a three-layer structure Cr—Cu—Cr is formed on these transparent electrodes (hereinafter, This metal layer may be referred to as a metal electrode). When these metal electrodes are covered with glass having a softening point of less than 450 ° C., the metal electrode may be eroded or the erosion of the transparent electrode through the metal electrode may be accelerated. In particular, when firing is performed at 520 ° C. or higher, when the metal electrode is covered with glass having a softening point of less than 450 ° C., the erosion of the transparent electrode becomes significant. Further, in this case, when the metal electrode is covered with glass having a softening point of 450 ° C. or higher and lower than 520 ° C., the erosion of the transparent electrode is eliminated, but bubbles in the electrode-coated glass layer increase during firing, and the transmittance of the electrode-coated glass layer is increased. Decrease.
[0017]
The softening point of the glass of the present invention is more preferably 500 ° C. or higher. More preferably, it is 520 degreeC or more, Most preferably, it is 550 degreeC or more, Most preferably, it is 580 degreeC or more.
[0018]
If the softening point is 450 ° C. or higher, the organic vehicle in the glass paste is completely volatilized before the softening flow of the glass starts, and a large amount of carbon-containing impurities in the organic vehicle remains in the electrode-coated glass layer. Further, it is expected to prevent a decrease in transmittance of the electrode-coated glass layer. Actually, a mixed powder obtained by mixing ethyl cellulose used as a binder, which is a component of an organic vehicle, and glass powder having a softening point of 600 ° C. and an average particle diameter of 3 μm in a mortar, When the temperature was raised at 10 ° C. and the relationship between the weight reduction rate and the temperature was examined, the weight reduction rate was zero at 450 ° C.
[0019]
Furthermore, if a softening point is 520 degreeC or more, an electrode covering glass layer can be made into a single layer structure. On the other hand, if the softening point is less than 520 ° C., it becomes difficult to form a single layer structure due to the erosion phenomenon of the transparent electrode, and the upper layer is made of glass having a softening point of less than 520 ° C., and the softening point is, for example, 520 ° C. or more. There is a possibility that a non-single layer structure having a glass having a high softening point as a lower layer must be formed. The lower layer here is a layer in direct contact with the transparent electrode.
[0020]
As the glass substrate, those having an average linear expansion coefficient at 50 to 350 ° C. of 80 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C. are usually used. Therefore, in order to match the expansion characteristics with such a glass substrate and prevent the glass substrate from being warped or reduced in strength, the average linear expansion coefficient of the glass of the present invention is 60 × 10 ^{−7 to} 90 × 10 ^−7. / ° C. is preferable, and 70 × 10 ^{−7 to} 85 × 10 ⁻⁷ / ° C. is more preferable. In addition, the average linear expansion coefficient in 50-350 degreeC is only called an expansion coefficient below.
[0021]
The specific resistance in the range from room temperature to 400 ° C. of the glass of the present invention, more typically the specific resistance in the range from room temperature to 300 ° C., is the specific resistance in the temperature range of the glass used for the glass substrate. It is preferably 0.1 times or more. If this condition is not satisfied, there is a risk of insufficient electrical insulation.
The specific resistance at 150 ° C. of the glass used for the glass substrate is typically about 10 ¹¹ Ω · cm. Therefore, the specific resistance of the glass of the present invention at 150 ° C. is preferably 10 ¹⁰ Ω · cm or more, and more preferably 10 ¹¹ Ω · cm or more.
[0022]
The relative dielectric constant of the glass of the present invention is preferably 18 or less. If it exceeds 18, the capacitance of the cell of the PDP becomes too large, and the power consumption of the PDP may increase. More preferably, it is 12 or less, Especially preferably, it is 10.5 or less, Most preferably, it is 10 or less.
[0023]
The glass of the present invention is preferably not crystallized during firing. From this viewpoint, the crystallization temperature T _c of the glass of the present invention is preferably higher than the firing temperature. More preferably, it is higher by 80 ° C. than the firing temperature. The crystallization temperature here is a crystallization peak temperature obtained by differential thermal analysis (DTA), and when no crystallization peak is observed, T _c = ∞.
[0024]
The _Tc is preferably 700 ° C. or higher. If it is less than 700 degreeC, there exists a possibility that glass may crystallize and the transparency may fall in the baking by 500-620 degreeC performed normally. More preferably, it is 750 degreeC or more.
[0025]
Glass of the present invention does not contain any Mo and Sb, Cu is contained as an essential component. When the Cu content (hereinafter referred to as CuO content) converted to CuO in terms of mass percentage is less than 0.2%, the transmittance of the electrode-coated glass layer is lowered. Preferably it is 0.3% or more. If it exceeds 0.9%, coloring due to Cu becomes too dark. Preferably it is 0.8% or less, More preferably, it is 0.7% or less. In the following, the content is expressed as a percentage by mass.
[0026 ]
[0027 ]
[0028]
[0029 ]
[0030 ]
[0031]
It will now be described the set formed of the glass of the present invention. Incidentally, it omitted noted For previously Cu O.
PbO is essential because it has the effect of lowering the softening point and increasing the expansion coefficient. If it is less than 25%, the effect is too small. Preferably it is 30% or more. If it exceeds 85%, the relative dielectric constant becomes too large, or the yellow coloring becomes too dark. Preferably it is 83.8% or less, More preferably, it is 75% or less.
[0032]
B ₂ O ₃ is essential. In order to stabilize the glass, or to increase the glass fluidity at the time of firing and to reduce the residual bubbles in the electrode-coated glass layer to increase the transmittance, it may be contained up to 60%. If it exceeds 60%, the softening point may be too high, or the glass may cause phase separation. Preferably it is 55% or less. B ₂ O ₃ is contained in an amount of 10% or more, more preferably 11% or more, and most preferably 23% or more. The size of the remaining bubbles is typically 30 μm.
[0033]
SiO ₂ is essential. In order to stabilize the glass or suppress the silver coloring phenomenon, it may be contained up to 40%. The silver coloring phenomenon here means that when a silver-containing bus electrode formed on the glass substrate of the PDP front substrate is coated with glass, silver diffuses into the glass and the glass is colored brown, and the image quality of the PDP deteriorates. It is a phenomenon. SiO ₂ is considered to have an effect of suppressing the diffusion of the silver. If the SiO ₂ content exceeds 40%, the glass fluidity at the time of firing is lowered, the residual bubbles in the electrode-coated glass layer are increased, and the transmittance may be lowered. The SiO ₂ content is more preferably 35% or less, still more preferably 15% or less, and most preferably 12% or less.
[0034]
When it is desired to particularly suppress the silver coloring phenomenon, the SiO ₂ content is preferably 5% or more. More preferably, it is 6.6% or more. In this case, the PbO content is preferably 83.8% or less and the B ₂ O ₃ content is preferably 11% or more.
[0035]
Al ₂ O ₃ is not essential, but may be contained up to 25% in order to stabilize the glass. If it exceeds 25%, the glass may be devitrified. More preferably, it is 15% or less, and particularly preferably 10% or less.
[0036]
Bi ₂ O ₃ is not essential, but may be contained up to 35% in order to lower the softening point. If it exceeds 35%, the glass may be colored yellow, or the relative dielectric constant may be too large. More preferably, it is 30% or less, and particularly preferably 5% or less.
[0037]
MgO, CaO, SrO and BaO are not essential, but may be contained up to 40% in order to increase the water resistance of the glass or to suppress the phase separation of the glass. In addition, it is preferable to contain MgO when it is particularly desired to lower the relative dielectric constant of the glass. If the content of each of these components exceeds 40%, crystallization during firing becomes remarkable, and the transmittance may be lowered. More preferably, it is 35% or less, and particularly preferably 30% or less.
[0038]
Note that MgO is most preferably 5% or less. If it exceeds 5%, the glass fluidity at the time of firing is lowered, the residual bubbles in the electrode-coated glass layer are increased, and the transmittance may be lowered.
The total content of MgO, CaO, SrO and BaO is preferably 40% or less. More preferably, it is 35% or less.
[0039]
ZnO is not essential, but is up to 4% in order to lower the softening point.
[0040]
Li ₂ O, Na ₂ O and K ₂ O are not essential, but may be contained up to 20% in order to lower the softening point. If it exceeds 20%, the water resistance of the glass may decrease, or the expansion coefficient may become too large. More preferably, each is 5% or less.
The total content of Li ₂ O, Na ₂ O and K ₂ O is preferably 20% or less. More preferably, it is 5% or less.
The glass of the present invention is preferably substantially composed of the above components, but other components may be contained up to 10% within a range not to impair the object of the present invention.
[0041]
In the front substrate of the plasma display device of the present invention (hereinafter referred to as the PDP of the present invention), a transparent electrode is formed on the glass substrate, and the surface of the glass substrate on which the transparent electrode is formed is the surface of the present invention. It is covered with glass.
The thickness of the glass substrate used for the front substrate is usually 2.8 mm, (hereinafter referred to as T _550.) Transmittance of light with a wavelength of 550nm of the glass substrate itself is typically 90%. The turbidity is typically 0.4%.
[0042]
Further, the transparent electrode has, for example, a band shape having a width of 0.5 mm, and is formed so that the respective band electrodes are parallel to each other. The distance between the strip electrode center lines is, for example, 0.83 to 1.0 mm. In this case, the ratio of the transparent electrode to the surface of the glass substrate is 50 to 60%.
[0043]
For the front substrate of the PDP of the present invention, T ₅₅₀ is preferably 77% or more. If it is less than 77%, the image quality of the PDP may be lowered. More preferably, it is 79% or more, and particularly preferably 80% or more. The turbidity is preferably 21% or less. If it exceeds 21%, the image quality of the PDP may deteriorate. More preferably, it is 20% or more, and particularly preferably 15% or less.
[0044]
If the PDP of the present invention is of an AC system, for example, it is manufactured as follows.
As shown in FIG. 1, after forming the patterned transparent electrode 2 and bus line (not shown) on the surface of the glass substrate 1a, the glass layer 3 is formed by applying and baking the glass powder of the present invention. Finally, a magnesium oxide layer (not shown) is formed as a protective film to form the front substrate 10. On the other hand, after the patterned address electrodes 5 are formed on the glass substrate 1b, the barrier ribs 6 are formed in stripes, and the phosphor layer 4 is printed and fired to form the back substrate 20.
[0045]
A sealant (not shown) is applied to the peripheral edges of the front substrate 10 and the rear substrate 20 with a dispenser, assembled so that the transparent electrode 2 and the address electrode 5 face each other, and then fired to obtain a plasma display device. Then, the inside of the plasma display device is exhausted, and a discharge gas such as Ne or He—Xe is sealed in the discharge space 7.
Although the above example is an AC type, the present invention can also be applied to a DC type.
[0046]
【Example】
The raw materials were prepared and mixed so as to have a composition represented by mass percentage in the columns from PbO to Sb ₂ O _{3 in the} table, and then melted for 1 hour using a platinum crucible in an electric furnace at 1300 ° C. And then pulverized with a ball mill to obtain glass powder. Examples 1 to 3 and 6 to 10 are examples, and examples A1 to A7 are comparative examples.
[0047]
With respect to these glass powders, the softening point (unit: ° C.), the expansion coefficient (unit: 10 ⁻⁷ / ° C.) and the relative dielectric constant were measured as described below. The results are shown in the table. The relative dielectric constant was measured for Examples 3, 4, A2, 7, 8, and A5.
Softening point: Measured using a differential thermal analyzer.
Expansion coefficient: After forming the glass powder, the fired body obtained by firing for 10 minutes at the firing temperature (unit: ° C.) shown in the table is processed into a cylindrical shape having a diameter of 5 mm and a length of 2 cm, and 50 to 350 with a thermal dilatometer. The average coefficient of linear expansion at 0 ° C. was measured.
Relative permittivity: The fired body was processed to 50 mm × 50 mm × thickness 3 mm, an electrode was deposited on the surface, and the relative permittivity at a frequency of 1 MHz was measured.
[0048]
Further, these glass powder and ethyl cellulose were weighed and mixed so as to have a mass ratio of 100: 5, and 2 g of the obtained mixture was put into a cylindrical mold having a diameter of 12 mm to form a cylindrical sample. This cylindrical sample was baked for 30 minutes at the softening point of the glass powder to obtain a disk-shaped fired body. The color of this fired body is shown in the table. When the color of the fired body is brown or black, the amount of carbon-containing impurities in the fired body is considered to be large. Therefore, it is considered that the amount of carbon-containing impurities in the fired bodies of Examples A2, A3, A5, A6, and A7 is large.
[0049]
Furthermore, 100 g of these glass powders were kneaded with 25 g of an organic vehicle to produce a glass paste. The organic vehicle is obtained by dissolving 7 to 18% of ethyl cellulose in diethylene glycol monobutyl ether monoacetate or α-terpineol in terms of mass percentage.
[0050]
Next, a glass substrate having a size of 10 cm × 10 cm and a thickness of 2.8 mm is prepared, and an ITO transparent electrode having a thickness of 200 nm and a width of 0.5 mm is formed on the surface of the glass substrate. A large number of lines were formed in parallel so that the distance between the lines was 1.0 mm. The glass substrate has a composition expressed by mass percentage of SiO ₂ : 58%, Al ₂ O ₃ : 7%, Na ₂ O: 4%, K ₂ O: 6.5%, MgO: 2%, CaO: 5%, SrO: 7%, BaO: 7.5%, ZrO ₂ : 3%, made of glass having a glass transition point of 626 ° C. and an expansion coefficient of 83 × 10 ⁻⁷ / ° C. The ITO transparent electrode is formed on one side of the glass substrate.
[0051]
The glass paste was uniformly screen-printed on a 30 mm × 30 mm portion where the ITO transparent electrode was formed, and then dried at 120 ° C. for 10 minutes. This glass substrate was heated at a heating rate of 10 ° C./min until the firing temperature shown in the table was reached, and further maintained at that temperature for 30 minutes for firing. The thickness of the glass layer covering the transparent electrode was 30 μm.
[0052]
About the glass substrate after the said baking, the transmittance | permeability (unit:%) and turbidity (unit:%) of light with a wavelength of 550 nm were measured as described below. The results are shown in the table.
Transmittance: The transmittance of light having a wavelength of 550 nm was measured using a self-recording spectrophotometer U-3500 (integrating sphere type) manufactured by Hitachi, Ltd. The state with no sample was taken as 100%.
Turbidity: A haze meter (C light source using a halogen bulb) manufactured by Suga Test Instruments Co., Ltd. was used. The light from the halogen sphere was converted into parallel rays through the lens, made incident on the sample, and the total light transmittance T _t and the diffuse transmittance T _d were measured with an integrating sphere. Turbidity is
Turbidity (%) = (T _d / T _t ) × 100
Calculated by
[0053]
Example 1, 2 and Example A1, Examples 3, 4, 5 and Example A2, Example 6 and Example A3, Example 7 and Example A4, Example 8 and Example A5, Example 9 and Example A6, Example 10 and Example A7 Then, it turns out that the transmittance | permeability becomes high and turbidity falls by containing CuO in 0.1 to 0.9% of range.
[0054]
Further, Examples 3, 4, A2, 7, 8, and A5 were examined for silver coloring phenomenon as follows.
Screen printing silver paste is uniformly applied to a 45 mm × 45 mm portion on a glass substrate having a size of 50 mm × 75 mm and a thickness of 2.8 mm made of the same glass as the previously used glass substrate, and then at 120 ° C. for 10 minutes. Dried. This glass substrate was heated to 580 ° C. at a temperature rising rate of 10 ° C./min, and further kept at that temperature for 15 minutes and fired to form a 5 μm thick silver fired body.
[0055]
A glass paste was screen printed so as to cover the entire surface of the silver fired body formed on the glass substrate, dried and fired to form a glass layer having a thickness of 30 μm. The drying and firing conditions were the same as those for the glass paste described above.
[0056]
For a sample in which a silver fired body is formed on a glass substrate, and a glass layer is further formed on the glass substrate, the light reflectance R ₅₅₀ (unit:%) and the wavelength are set so that light is incident on the glass layer side. The reflectance R ₄₃₀ (unit:%) of light at 430 nm was measured by the self-recording spectrophotometer. R ₅₅₀ -R ₄₃₀ (unit:%) is shown in the silver color column of the table. The reason why the wavelength of 430 nm is selected is that it corresponds to the absorption peak of the silver colloid that causes silver coloring, whereas the wavelength of 550 nm is selected because it is sufficiently far from the absorption peak of the silver colloid. .
When R ₅₅₀ -R ₄₃₀ is 20% or more, the silver coloring phenomenon is remarkable, which is not preferable. More preferably, it is 15% or less, and particularly preferably 5% or less.
[0057]
[Table 1]

[0058]
[Table 2]

[0059]
【The invention's effect】
By using the glass of the present invention, the transparency of the glass layer covering the transparent electrode on the glass substrate can be increased. In addition, the residual amount of carbon-containing impurities in the glass layer is reduced, so that the luminance in the PDP is hardly lowered. Furthermore, the silver coloring phenomenon of the glass layer which coat | covers the silver electrode on a glass substrate can be suppressed. In addition, the dielectric constant of the glass layer covering the electrode can be reduced.
[0060]
In the PDP of the present invention, the transmittance of the front substrate is high and the image quality is excellent. In addition, the luminance is unlikely to decrease. Furthermore, the silver coloring phenomenon of the glass layer covering the silver electrode of the front substrate can be suppressed, and the image quality is also improved in this respect. In addition, power consumption can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a plasma display device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a: Glass substrate 1b: Glass substrate 2: Transparent electrode 3: Glass layer 4: Phosphor layer 5: Address electrode 6: Partition 7: Discharge space 10: Front substrate 20: Rear substrate

Claims (6)

In mass percentage display based on the following oxides,
PbO 25-85%,
B ₂ O ₃ 10-60%,
SiO ₂ 2~40%,
Al ₂ O ₃ 0-25%,
Bi ₂ O ₃ 0-35%,
MgO 0-40%,
CaO 0-40%,
SrO 0-40%,
BaO 0-40%,
ZnO 0-4%,
Li ₂ O 0-20%,
Na ₂ O 0-20%,
K ₂ O 0-20%,
CuO 0.2-0.9%,
A low-melting glass for electrode coating, comprising MgO + CaO + SrO + BaO in an amount of 0 to 40% and containing neither Mo nor Sb. PbO is 83.8% or less, SiO ₂ is 5% or more and B ₂ O ₃ is 11% or more in the low-melting glass for covering electrodes according to claim 1. The low melting point glass for electrode coating according to claim 1 or 2 , wherein the softening point is in the range of 450 to 650 ° C. The low melting point glass for electrode coating according to claim 1 , 2 or 3 , wherein an average linear expansion coefficient at 50 to 350 ° C is in a range of 60 × 10 ^{-7 to} 90 × 10 ^-7 / ° C. The dielectric constant is 12 or less, The low melting point glass for electrode coating according to any one of claims 1 to 4 . A plasma display device having a front substrate, wherein a transparent electrode on a glass substrate constituting the front substrate is coated with the low-melting glass for electrode coating according to any one of claims 1 to 5 .

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