JPS603355B2 - Pigment coated europium activated yttrium oxysulfide phosphor - Google Patents

Description

[Detailed description of the invention] The present invention relates to a backlight for a color cathode ray tube.

In conventional color televisions, various methods have been proposed to reduce the reflection of light on the front surface of the cathode ray tube in order to improve the brightness and contrast of the screen under external light. Among these measures, glass with low light transmittance is generally used as the front glass panel.

Alternatively, there are two methods in which the portion of the front glass panel that is not coated with the photoluminescent layer is made black. However, in the former case, the transmittance of the light emitted by the crab phosphor layer also decreases, resulting in a dark screen, and in the latter case, the area where the crab phosphor layer is not coated is a proportion of the total area. Because of the small amount of light, the reflection of external light was not sufficiently reduced.

Furthermore, a color cathode ray tube including a red light-emitting phosphor coated with a red pigment has been proposed.

A color cathode ray tube having such a structure can reduce the reflection of color components other than the emission color of the total light body itself, and is therefore quite effective in reducing the reflection of external light. it is conceivable that. Until now, it has been known to coat a red light-emitting crab light body, a green light-emitting crab light body, and a blue light-emitting halo body, respectively, with a green-blue pigment. In cathode ray tubes using pigments, the degree of contrast strongly depends on the spectral reflectance of the pigment, so the selection of the pigment is important. As for red pigments, substances such as cadmium sulfoselenide and lead matrix are known which exhibit a bright red color under natural light, but they are not suitable for use in cathode ray tubes due to their toxicity.

For this reason, pengara (iron oxide) is used as a red pigment, but this material is insufficient in terms of color, and there has been a desire to develop a pigment that has a bright red color and is not toxic. The present invention was made to solve these conventional problems, and uses indium sulfide, a new red pigment that is non-toxic and has a higher reflectance at wavelengths of 60 cm or more than conventional red pigments. The present invention aims to provide a red light-emitting crab luminous material coated with a red light emitting crab.

Examples of the present invention will be described in detail below. Example 1 25 ml of europium-activated yttrium oxysulfide (average particle size approximately 7 Buddhas) of red luminescent phosphor are suspended in 2500 ml of deionized water.

10 parts of an aqueous indium chloride solution (each containing 0.2 ln30) is added and mixed into this crab-photon suspension. While slowly stirring, adjust the pH of the suspension to about 2.2 (1-3.6 is acceptable) by adding an acid such as hydrochloric acid. Next, about 200 g of Z, an aqueous solution containing 1.7 g of sodium sulfide, is added dropwise while stirring.
This mixture is allowed to mature for at least one hour while being submerged, so that substantially all of the indium present is precipitated as indium sulfide particles on the crab phosphor particles. Next, the solid matter with indium sulfide attached to the surface of the crab light body is allowed to settle, the supernatant is filtered, the settled solid matter is purified with deionized water, and the solid matter is dried at about 125 minutes. Thoroughly mix about 7.5 scales of sulfur with 250 nails of dry solids. Next, this mixture is placed in a quartz crucible and heated at 900° C. for 30 minutes in a mildly reducing atmosphere. The spectral reflectance of the product obtained as described above is shown in FIG. In FIG. 1, the axis shows wavelength (nm) and the vertical axis shows spectral reflectance.

In the figure, line A-A is a red light-emitting crab light body coated with indium sulfide of the present invention, line B-B is a red light-emitting crab light body coated with conventional pengara, and line C-C is a red light-emitting light body that is not coated with pigment. Showing crab photophores. As is clear from this figure, the indium sulfide-coated crab light of the present invention has a higher reflectance at longer wavelengths of 60 or more than the conventional pengara-coated crab light, and has a higher reflectance at shorter wavelengths of 60 or more. It can be seen that the ratio is low and the contrast is significantly improved. In the above example, indium sulfide was precipitated together with the phosphor, but even if only indium sulfide was produced and coated on the phosphor with an appropriate binder (e.g. zinc acetate), the same could be said of the above example. It is possible to obtain a pigment-coated crab phosphor having a spectral reflectance similar to that of .

Example 2 Indium chloride 10 μl in deionized water 250 μl
Kite [dissolves in]

A portion of the indium ions present in the aqueous solution is precipitated as indium sulfide particles by passing hydrogen sulfide into this aqueous solution at a rate of 1 minute per minute for 3 hours. The solids are then allowed to settle, the supernatant is removed, the precipitated solids are washed with deionized water, and the solids are dried at about 100°C. The dried solid material has a reddish color. Thoroughly mix 3 gr of sulfur with 100 gr of the above solid material. Next, this mixture was placed in a quartz crucible and fired for 30 minutes at 500 pm using weakly reducing air. This fired product consists of red indium sulfide particles having a particle size of 0.5 to 1#. Next, 1g of the above indium sulfide particles and europium-activated yttrium oxysulfide 1008 are suspended in about 500cc of water. While slowly pouring over this suspension, water glass K20. Add 1 part of $i02 aqueous solution (25 mol%).

[Brief explanation of drawings]

FIG. 1 is a diagram showing the spectral reflectance of the phosphor of the present invention and a conventional phosphor. Figure 1

Claims (1)

[Claims] 1 Pigment coated europium activated yttrium oxysulfide phosphor coated with indium sulfide.