KR20000042497A - Panel glass for color cathode ray tube - Google Patents

Abstract

PURPOSE: A panel glass for a cathode ray tube is provided to reduces the dichroism. CONSTITUTION: A panel glass for a cathode ray tube has good contrast, brightness and range of realizing color and reduces the chroma and also reduces the dichroism according to a light source, by containing Nd2O3 and Ho2O3 in a basic composition of the panel glass. The Nd2O3 is added to reduce the chroma of the panel glass and to reduce the dichroism of the glass containing Nd2O3. The panel glass contains SiO2 55-75wt%, Al2O3 0-5wt%, CaO0-4wt%, MgO 0-3wt%, Li2O 0-4wt%, Na2O 5-15wt%, K2O 5-10wt%, CeO2 0-3wt%, TiO2 0-2wt%, Sb2O3 0-0.5wt%, NiO 0-0.025wt%, Co3O4 0-0.025wt%, SrO + BaO + ZrO2 10-25wt%, Na2O + K2O 10-20wt%, Nd2O3 0.1-5.0 wt% and Ho2O3 0.01-3.0wt%.

Description

Panel Glass for Color Cathode Ray Tube

The present invention relates to a panel glass for colored cathode rays.

Panel glass for colored cathode ray tubes forms a fluorescent surface by a plurality of phosphors of three colors, red, green, and blue, and emits light by an electron beam emitted from an electron gun. . At this time, the image composed of the emitted color is displayed on the screen through the panel glass. However, the image of the color cathode ray tube has a problem that the contrast is lowered by external light such as sunlight or fluorescent lamps.

To solve this problem, a small amount of NiO, Co ₃ O ₄ , which is a colorant, was added to the panel glass. However, since the transmittance of all or part of the visible wavelength range is reduced, the light emitted from the red, green, and blue phosphors is also absorbed to improve the brightness of the image. Lowers. Therefore, there is a need for the development of glass exhibiting optical characteristics that sufficiently transmit red, green, and blue light emitted from phosphors and absorb light of other wavelengths.

This can be obtained by adding Nd ₂ O ₃ which is a specific component to the panel glass for color cathode ray tubes. As shown in FIG. 1, it exhibits high transmittance at red, green, and blue wavelengths at which the phosphor emits light, and at yellow wavelength (580 nm). (Special office 45-21342) However, in glass containing Nd ₂ O ₃ , the color emitted by the phosphor passes through the panel glass and changes in color depending on the external light source (fluorescent lamp, C-light source, etc.). Dichroism).

The present invention is to solve the above problems, by containing Nd ₂ O ₃ and Ho ₂ O ₃ in the basic composition of the panel glass for color cathode ray tube, not only excellent contrast, brightness and color reproduction range but also lower saturation Nd _It is an object of the present invention to provide a panel glass for color cathode rays which reduces dichroism according to a light source, which is a problem when only ₂ O ₃ is added.

1 is a transmittance curve according to emission spectra and additives of a phosphor.

<Description of the code | symbol about the principal part of drawing>

1: Red (Red)

2: Green

3: Blue

4: addition of Nd ₂ O ₃

5: addition of Nd ₂ O ₃ and Ho ₂ O ₃

Panel glass for color cathode ray tubes of the present invention,

SiO ₂ 55-75wt%, Al ₂ O ₃ 0-5wt%, CaO 0-4wt%, MgO 0-3wt%, Li ₂ O 0-4wt%, Na ₂ O 5-15wt%, K ₂ O 5-10wt %, CeO ₂ 0-3 wt%, TiO ₂ 0-2 wt%, Sb ₂ O ₃ 0-0.5 wt%, NiO 0-0.025 wt%, Co ₃ O ₄ 0-0.025 wt%, SrO + BaO + ZrO ₂ 10 To 25 wt%, Na ₂ O + K ₂ O 10 to 20 wt%, Nd ₂ O ₃ 0.1 to 5.0 wt%, and Ho ₂ O ₃ 0.01 to 3.0 wt%.

If described in more detail for each component constituting the panel glass of the present invention as follows.

SiO ₂ contains 55 to 75 wt% of an oxide forming a glass. If the SiO ₂ content is more than 75 wt%, it is difficult to dissolve and form, and if it is less than 55 wt%, the coefficient of thermal expansion is too large and the chemical durability of the glass is deteriorated.

Al ₂ O ₃ is a component that improves the chemical durability of the glass. When it exceeds 5 wt%, the meltability of the glass is deteriorated.

CaO and MgO are components that improve the chemical durability of the glass, CaO is more than 4wt% or MgO is more than 3wt% devitrification phenomenon is likely to occur.

Li ₂ O is a component that improves the meltability of the glass, and if it exceeds 4wt%, the thermal expansion coefficient is too large.

Na ₂ O and K ₂ O improve the meltability of the glass and are effective for controlling the coefficient of thermal expansion, but Na ₂ O exceeds 15wt% and K ₂ O exceeds 10wt%, respectively, or the total content of Na ₂ O and K ₂ O If it exceeds 20wt%, chemical durability will worsen. In addition, when Na ₂ O is less than 5% and K ₂ O is less than 5wt%, or the total content of Na ₂ O and K ₂ O is less than 10%, meltability deteriorates and devitrification is likely to occur.

CeO ₂ is added in an amount of 3wt% or less to prevent discoloration of the glass by X-rays or electron beams.

TiO ₂ is added at 2% or less to prevent discoloration by ultraviolet rays.

Sb ₂ O ₃ is added at 0.5% or less as a clarifier to remove bubbles generated during melting of the glass.

NiO and Co ₃ O ₄ are added in an amount of 0.025 wt% or less to obtain light transmittance control and desired color coordinates.

SrO, BaO and ZrO ₂ are components added to the glass to have high X-ray absorption, and the sum thereof is preferably 10 to 25 wt%.

Nd ₂ O ₃ is a very effective component for selectively absorbing and transmitting red, green, and blue wavelength light emitted from a phosphor, and is added in an amount of 0.1 to 5 wt% to improve contrast, brightness, and color gamut. However, as shown in FIG. 1, the Nd ₂ O ₃ added panel glass exhibits dichroism due to the absorption of wavelengths around 580 nm. To solve this problem, saturation is similar to that of general panel glass of clear, tint, and dark tint series. It should be close to achromatic without color.

Ho ₂ O ₃ , the biggest feature of the present invention, is added to lower the saturation mentioned above, and serves to reduce the dichroism of the glass containing Nd ₂ O ₃ . Ho ₂ O ₃ is added in the range of 0.01 to 3.0wt%, but less than 0.01% of the above effect is insufficient, and when more than 3% is added, the saturation is increased to cause adverse effects on dichroism inhibition.

On the other hand, the present invention in the CIELAB (L * a * b *) color coordinate system recommended by the Commission International de I'Eclairage (CIE) in 1976 in order to evaluate the dichroism that changes color depending on the external light source Chroma of was used. CIELAB (L * a * b *) color coordinate system is an approximate uniform color space that represents the magnitude of color perception based on complementary color theory, and is evaluated to be closer to Munsell color coordinate system, the color system closest to human eyes. have. In the CELAB (L * a * b *) color coordinate system, the saturation (C * ab) is calculated from Equation 1 below.

Where the L *, a *, b * Cartesian coordinate system for each sample is calculated from the original X, Y, Z tristimulus measurements of the sample, and the Xn, Yn, Zn values are fully diffuse reflectors under the specified light source and observer. It represents the tristimulus value of (perfect refledcting diffuser).

In the present invention, the dichroism was determined through the aforementioned saturation (C * ab), and as the reason that the colorless general panel glass does not exhibit dichroism, the smaller the saturation value, the dichroicity according to the light source. It can be judged to decrease.

Such a present invention will be described in detail based on examples.

Examples 1-5, Comparative Example

Next, the ingredients were weighed and mixed so as to be 700 g per batch according to the composition ratio of Table 1, and then put into a 900 cc platinum crucible and melted at 1450 to 1550 ° C. for 3 hours using an electric furnace. Next, the molten glass material was poured into a graphite mold to be molded, and then cooled by slow cooling after holding at 540 ° C. for 2 hours to prepare a panel glass for a cathode ray tube.

Experimental Example

In order to evaluate the optical properties of the panel glass prepared in Examples 1 to 5 and Comparative Examples, the specimen was prepared with 1.5 × 3.5 cm and polished the surface, and then a UV-VIS scanning photometer (UV-2101PC). ) And the spectral transmittance in the wavelength range of 400 ~ 750nm was measured and shown graphically in FIG. The CIE X, Y, and Z tristimulus values for each light source were calculated using the transmittance data obtained at 10 nm intervals, the fluorescent light at 2 ° viewing angle, and the tristimulus function of each C light source, followed by the saturation (C * ab) in the CIELAB color coordinate system. ) Was obtained by the following equation.

Thus, the composition used in the examples and the saturation calculated through the experimental example are shown in Table 1 below.

As can be seen from Table 1, the saturation of Examples 1 to 5 in which Nd ₂ O ₃ and Ho ₂ O ₃ were added according to the present invention showed a significantly lower value than that of Comparative Example in which only Nd ₂ O ₃ was added. This means that dichroism is dramatically reduced.

As described above, the panel glass for color cathode ray tube manufactured according to the present invention adds Nd ₂ O ₃ and Ho ₂ O ₃ to the basic composition of the panel glass, thereby providing excellent contrast, luminance and color reproduction range, The dichroism according to the light source, which is a problem when only Nd ₂ O _{3 was} added, could be drastically reduced.

Claims (1)

In the panel glass for colored cathode ray tubes, SiO ₂ 55-75wt%, Al ₂ O ₃ 0-5wt%, CaO 0-4wt%, MgO 0-3wt%, Li ₂ O 0-4wt%, Na ₂ O 5-15wt%, K ₂ O 5-10wt %, CeO ₂ 0-3 wt%, TiO ₂ 0-2 wt%, Sb ₂ O ₃ 0-0.5 wt%, NiO 0-0.025 wt%, Co ₃ O ₄ 0-0.025 wt%, SrO + BaO + ZrO ₂ 10 -25 wt%, Na ₂ O + K ₂ O 10-20 wt%, Nd ₂ O ₃ 0.1 to 5.0wt%, Ho ₂ O ₃ 0.01 to 3.0wt% containing panel glass for color cathode ray tube characterized in that it contains.