JPH11233033A - Substrate glass for plasma display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image with high brightness and high contrast by lowering the light transmissivity at the wavelength of bluish green color, which is an intermediate color of blue and green and at the wavelength of yellow color relatively to the light transmissivity at each wavelength of red, green, and blue colors which are fluorescent colors of phosphors of substrate glass. SOLUTION: Light transmissivity of a substrate glass for a plasma display panel at wavelength of 530 nm and of 586 nm is lowered than that at wavelength of 460 nm, 550 nm, and 620 nm by at least 3%, preferably about at least 5%, and more preferably about at least 10%. A high strain point glass having a composition containing 50-65 wt.% SiO2 , 0.5-15 wt.% Al2 O3 , 10-27 wt.% MgO+CaO+SrO+BaO, 7-15 wt.% Li2 O+Na2 +K2 O, 0-9 wt.% ZrO2 , 0-5 wt.% TiO2 , 0-1 wt.% Cl, and 0-1 wt.% SO2 is preferable for the substrate. Desired light transmissivity is obtained by adding 0.1-10 wt.% Nd2 O3 . If necessary, a prescribed amount of NiO2 or CoO may be added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate glass used for a front glass substrate of a color plasma display.

[0002]

2. Description of the Related Art In a color plasma display, red, green and blue phosphors are excited by ultraviolet rays generated at the time of discharge to emit visible light, and an image formed by the emission is projected through a front glass substrate. The emission wavelength of each phosphor is 620 nm for red, 550 nm for green, and 460 for blue.
nm.

[0003] The color plasma display is thin and can be made large in size, and is expected as a large-sized television replacing a CRT. However, at present, there is a problem that the contrast and the brightness are lower than those of the CRT, and the contrast of the image is significantly reduced due to external light such as sunlight or fluorescent light.

In order to improve the contrast of an image by absorbing external light, it has been studied to use a front glass substrate which is colored by adding a small amount of NiO or CoO and has a reduced transmittance.

[0005]

SUMMARY OF THE INVENTION However, NiO
Coloring with CoO or CoO reduces the transmittance almost uniformly over the entire visible wavelength range, so that the light emitted from the red, green, and blue phosphors is also absorbed, resulting in an undesired result in that the brightness of the image is reduced.

An object of the present invention is to provide a substrate glass for a plasma display capable of obtaining a high-luminance and high-contrast color image.

[0007]

As a result of various studies, the present inventors have found that the transmittance of light having a wavelength other than the emission colors of the red, green, and blue phosphors, specifically, 530 nm, which is between blue and green, is measured. The inventors have found that the luminance can be increased by lowering the light transmittance in the vicinity [blue-green] and in the vicinity of 586 nm [yellow] between red and green, and propose the present invention.

That is, the substrate glass for a plasma display of the present invention has a light transmittance at wavelengths of 530 nm and 586 nm of 460 nm, 5
It is characterized by being at least 3% lower than each light transmittance at wavelengths of 50 nm and 620 nm.

[0009]

The substrate glass for a plasma display of the present invention has the lowest light transmittance (the lowest transmittance of the phosphor wavelength) of the light transmittance of the wavelength (phosphor wavelength) corresponding to the emission color of each phosphor, and 530 nm. And 586 nm wavelength (intermediate wavelength)
The difference in transmittance of the highest one of the light transmittances (the highest transmittance at the intermediate wavelength) is 2.8 mm in thickness, 3% or more, preferably 5% or more, more preferably 10% or more. It is characterized by. If the transmittance difference is less than 3%, a high-luminance plasma display cannot be manufactured.

In the present invention, in order to impart the above properties to the substrate glass, it is preferable to include Nd ₂ O ₃ in the glass composition. When Nd ₂ O ₃ is contained in glass, the glass exhibits high transmittance for light having wavelengths of 460 nm, 550 nm and 620 nm, and exhibits sharp absorption for light having wavelengths of 530 nm and 586 nm. Therefore, when Nd ₂ O ₃ is contained in the substrate glass of the color plasma display, it has high transmittance for light corresponding to each of red, green and blue phosphors, and has high transmittance for yellow light and blue-green light. It is possible to provide a selective permeation / absorption ability having absorbency.

When Nd ₂ O ₃ is used for the above purpose, it is preferable to contain Nd ₂ O ₃ in an amount of 0.1% or more, particularly 0.6% or more, in order to obtain a sufficient effect. However, more than 6%, especially 10%
%, It is not preferable because devitrification tends to occur and raw material cost increases.

In the present invention, soda lime glass used as architectural window glass may be used as the base glass containing Nd ₂ O ₃ or the like, but SiO ₂ is used as a percentage by weight.
₂ 50-65% (preferably 52-62%), Al ₂ O
₃ 0.5-15% (preferably 3-13%), MgO +
CaO + SrO + BaO 10 to 27% (preferably 1
_{2~25%), Li 2 O +} Na 2 O + K 2 O 7~15
% (Preferably 8 to 14%), ZrO ₂ 0 to 9% (preferably 1 to 8%), TiO ₂ 0 to 5% (preferably 0 to 0%)
3%), Cl 0-1% (preferably 0-0.5%),
SO ₃ 0 to 1% (preferably 0 to 0.5%) it is desirable to use a high strain point glass having the composition. In other words, soda lime glass has a drawback that it has a low strain point and thus easily shrinks during high-temperature treatment when baking electrodes and insulating pastes, and has a low volume resistivity and the electrical resistance of the electrode material tends to change. . On the other hand, the high strain point glass having the above composition has a coefficient of thermal expansion of 75 to 95 × 10 ⁻⁷ / ° C. and has a high strain point, so that it does not easily shrink during heat treatment. Moreover, it has a characteristic that the volume resistivity is higher than that of soda lime glass.

The reason why the composition of the high strain point glass is limited as described above will be described below.

SiO ₂ is a glass network former. When the content of SiO ₂ is less than 50%, the glass has a low strain point and tends to be thermally shrunk, and when the content is more than 65%, the thermal expansion coefficient becomes too small, which is not preferable.

Al ₂ O ₃ is a component for increasing the strain point of glass. If the content of Al ₂ O ₃ is less than 0.5%, no effect is obtained, and if it is more than 15%, the thermal expansion coefficient becomes too small.

MgO, CaO, SrO and BaO are all components for facilitating the melting of glass and controlling the coefficient of thermal expansion. If the combined amount is less than 10%, the coefficient of thermal expansion tends to be small. If the combined amount is more than 27%, the glass tends to be devitrified and molding is difficult. Note that Mg
The preferred ranges of O, CaO, SrO and BaO are 0-5%, 0-8%, 0-10% and 0-10%, respectively.

Li ₂ O, Na ₂ O and K ₂ O are all components for controlling the coefficient of thermal expansion. If the total amount is less than 7%, the coefficient of thermal expansion tends to be small, and
%, The strain point becomes lower. Note that Li ₂ O, Na ₂ O
And K ₂ O are preferably in the range of 0 to 0.5%,
8% and 2-10%.

ZrO ₂ has the effect of improving the chemical durability, but if it exceeds 9%, the coefficient of thermal expansion becomes too small, and devitrified matters are easily formed when the glass is melted, making molding difficult.

TiO ₂ is a component for preventing the glass from being colored by ultraviolet rays, but if it exceeds 5%, the glass is apt to be devitrified and molding becomes difficult.

Both Cl and SO ₃ can be added as fining agents, but if each component is more than 1%, it is not preferable because it causes bubbles.

The glass having the above composition has a light transmittance (at a thickness of 2.8 mm) at each wavelength of 83% or more (preferably 85% or more) at the minimum transmittance of the phosphor wavelength.
If the light transmittance at a wavelength of 0 nm is 80% or less (preferably 78% or less) and the light transmittance at a wavelength of 586 nm is 60% or less (preferably 50% or less), the plasma having sufficiently high brightness and contrast is obtained. A display can be made.

In addition to the above composition, one or more of NiO and CoO can be contained for fine control of chromaticity and light transmittance. When these components are added, the added amount is 10 to 2000 ppm of NiO, CoO 1
It is preferably in the range of 0 to 500 ppm.

When one or more of NiO and CoO are added,
Its appearance is gray and transparent. At this time, the light transmittance (at a thickness of 2.8 mm) at each wavelength is 68% or more (preferably 70% or more) at the minimum phosphor wavelength, and the light transmittance at a wavelength of 530 nm is 67% or less (preferably). 65%
Below), and light transmittance at a wavelength of 586 nm is 52
% Or less (preferably 40% or less).

Further, in the present invention, since the absorption capacity of Nd ₂ O ₃ is slightly weaker at around 530 nm than at around 586 nm, Er ₂ O ₃ , Cr ₂ O ₃ and Pr ₆ O ₁₁ are combined in 6% in total. You may add up to. Further, Fe ₂ O ₃ may be contained at 1% or less.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a substrate glass for a plasma display of the present invention will be described based on embodiments.

Tables 1 and 2 show examples of the present invention (sample Nos.
1 to 8) and conventional examples (Sample Nos. 9 and 10).

[0027]

[Table 1]

[0028]

[Table 2]

Each sample was prepared as follows.

First, raw materials were prepared so as to have the glass composition shown in the table, put in a platinum crucible, and then placed in an electric furnace at 1450.
It was melted at a temperature of 温度 1550 ° C. for 4 hours, and the molten glass was poured out onto a carbon table and formed into a plate shape.

The obtained plate glass is optically polished on both sides,
The sample is cut into a size of × 30 × 2.8mm,
The light transmittance was measured using a Model 228 spectrophotometer manufactured by Hitachi, Ltd. Note that FIG. The light transmittance curves of 1, 9 and 10 are shown. 460 nm, 530 n of each sample
The light transmittance at m, 550 nm, 586 nm and 620 nm is shown in the table.

As is clear from FIG. 1 and the table, the sample No. Nos. 1 to 8 show high transmittance with respect to light of the phosphor wavelength, and show large absorption at an intermediate wavelength corresponding to blue-green light of 530 nm and yellow light of 586 nm. 3% or more lower than the minimum transmittance of the phosphor wavelength.

On the other hand, the sample No. 9 and 10
Has almost no absorption at the intermediate wavelength, and conversely, the highest transmittance at the intermediate wavelength is higher than the lowest transmittance at the phosphor wavelength.

Next, each sample was used as a front glass substrate for 4 hours.
A 2-inch color plasma display panel was manufactured, and the contrast was evaluated. Contrast is sample N
o. The evaluation was visually made based on a rating of 10, and ○ was given when the contrast was better, ◎ was given when the contrast was particularly good, and × was given when the contrast was inferior. The results are shown in the table.

As a result, it was found that the color plasma display panel manufactured using the substrate glass of the present invention had high contrast.

[0036]

As described above, the substrate glass for a plasma display of the present invention has a selective light transmission / absorption characteristic, so that a plasma display with high brightness and high contrast can be manufactured. Therefore, it is suitable for a front glass substrate of a color plasma display.

[Brief description of the drawings]

FIG. 1 is a graph showing a light transmittance curve of a substrate glass at a thickness of 2.8 mm.

[Explanation of symbols]

 1 Sample No. 1 light transmittance curve 2 Sample No. 1 No. 9 light transmittance curve 3 Sample No. 9 10 light transmittance curves

Claims (8)

[Claims] A light transmittance at wavelengths of 530 nm and 586 nm is 460 nm,
A substrate glass for a plasma display, wherein the substrate glass has a transmittance of 3% or more lower than each light transmittance at wavelengths of 550 nm and 620 nm. 2. The substrate glass for a plasma display according to claim 1, wherein Nd ₂ O ₃ is contained in the glass composition. _3. The substrate glass for a plasma display according to claim 2, wherein the content of Nd ₂ O ₃ is 0.1 to 10% by weight. 4. When the thickness is 2.8 mm, 460 nm
The light transmittance at the wavelengths of 550 nm and 620 nm is 83% or more, and the light transmittance at the wavelength of 530 nm is 80% or less, and the light transmittance at the wavelength of 586 nm is 60% or less. The substrate glass for a plasma display according to claim 3, wherein 5. The plasma display substrate glass according to claim 3, wherein the glass composition contains at least one of NiO and CoO. 6. The content of NiO and CoO is NiO 1
The substrate glass for a plasma display according to claim 5, wherein the content is 0 to 2000 ppm and CoO is 10 to 500 ppm. 7. When the thickness is 2.8 mm, 460 nm
The light transmittance at the wavelengths of 550 nm and 620 nm is 68% or more, and the light transmittance at the wavelength of 530 nm is 66% or less, and the light transmittance at the wavelength of 586 nm is 50% or less. The substrate glass for a plasma display according to claim 6, wherein 8. SiO ₂ 50-65% by weight, A
l ₂ O ₃ 0.5 to 15%, MgO + CaO + SrO + B
_{aO 10~27%, Li 2 O +} Na 2 O + K 2 O 7
_{~15%, ZrO 2 0~9%,} TiO 2 0~5%, Cl
0~1%, SO ₃ 0~1% of the plasma display substrate glass according to claim 1, characterized in that it comprises a composition.