JPH06322363A - Fluorescent substance for cathode ray tube - Google Patents

Abstract

PURPOSE:To obtain a fluorescent substance, having a high brightness with long afterglow, capable of readily carrying out the fogging check by irradiation of ultraviolet rays and suitable as cathode ray tubes, etc., by coating the surfaces of specific manganese-activated zinc phosphate fluorescent substance particles with particles capable of emitting light by irradiation of the ultraviolet rays. CONSTITUTION:The objective fluorescent substance is obtained by coating the surfaces of manganese-activated zinc phosphate fluorescent substance particles expressed by the chemical formula Zn3(PO4)2: Mn with preferably 1-10wt.% particles, composed of a europium-activated rare earth oxide fluorescent substance and capable of emitting light by irradiation of ultraviolet rays.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor suitable for a cathode ray tube, particularly a cathode ray tube for a display.

[0002]

2. Description of the Related Art Generally, it is desired to use a cathode ray tube having high resolution and no flicker on the screen for a display (terminal display device) of a computer or a display device of a word processor on which precise characters and figures are displayed. . Therefore, it is desirable that the phosphor screen (phosphor film) of these cathode ray tubes is made of a phosphor having a long afterglow time and high emission brightness.

Conventionally, as a phosphor having a long afterglow, for example, ZnS: Ag, Ga may be used as a blue light emitting phosphor. As the green-emitting phosphor, Zn ₂ SiO ₄ : Mn,
As (P39 phosphor), and Zn ₂ SiO ₄ : Mn, In (manganese and indium activated zinc silicate phosphor) that does not contain As, which is a pollutant, recently proposed by the present inventors are used. As a red-emitting phosphor, Zn ₃ (PO ₄ ) ₂ : Mn
(Manganese-activated zinc phosphate phosphor) is used.

However, depending on the required specifications of the cathode ray tube,
Often, these long afterglow phosphors alone are insufficient in luminance, in which case, ZnS: Ag of blue phosphor which is a conventional short afterglow phosphor and ZnS of green phosphor: Cu, Al and ZnS: Cu, Au, Al or red phosphor Y ₂ O ₂ S: Eu
And a mixed phosphor of the long afterglow phosphor described above is used. Furthermore, the green long afterglow phosphor Zn ₂ SiO ₄ : Mn, In is
Conventional green short afterglow phosphor ZnS: Cu, Al or ZnS: Cu, A
Since the bluish color is stronger than the emission colors of u and Al, Zn ₂ SiO ₄ : Mn, In may be mixed with Y ₂ O ₂ S: Eu of a red phosphor to form a green phosphor component. Here, the phosphors of the three colors are applied to the inner surface of the panel of the cathode ray tube in a dot matrix form so that the respective colors are adjacent to each other in order, as shown in FIG.
Are formed. That is, the phosphor is dispersed in a polyvinyl alcohol aqueous solution to which a suitable photosensitizer is added to form a slurry, which is applied to the inner surface of the panel of the cathode ray tube, and then exposed and developed in a dot pattern using a shadow mask to form dots. The dot matrix phosphor screen 1 shown in FIG. 1 is obtained by forming the phosphor screen 1 of the matrix and repeating this three times for each of the red, green and blue phosphors. The symbols R, G, and B in the dots represent the colors red, green, and blue, respectively.

[0005]

By the way, as a problem in the manufacturing technology of the above-mentioned phosphor screen, for example, when the red phosphor applied later on the blue dot remains, the blue emission color tone deteriorates. However, there is a problem that the yield of the cathode ray tube decreases. Such a defect of the fluorescent screen is called fogging, and the pursuit of a manufacturing method in which the fogging does not occur as much as possible is a major problem in manufacturing the fluorescent screen. In particular, in recent years, the resolution of cathode ray tubes has been increased, and the pitch of the dot matrix on the phosphor screen has become smaller and smaller, so that the specifications for fogging have become stricter.

Usually, the fogging state on the phosphor screen is checked by applying phosphors of each of the three colors, irradiating the phosphor screen with ultraviolet rays to emit light, and observing the dot pattern with a microscope. As a result of such observations, those with severe fogging are removed without being passed through the subsequent steps.

However, since the manganese-activated zinc phosphate phosphor, which is a long-afterglow red phosphor, emits almost no light when irradiated with ultraviolet rays, it is not possible to perform a fogging check, which is a major problem in manufacturing a cathode ray tube. Was becoming.

The present invention has been made under such circumstances, and an object of the present invention is to provide a phosphor for a cathode ray tube which has a long afterglow and a high brightness and which can easily perform a fogging check by irradiation of ultraviolet rays. I am trying.

[0009]

Means and Actions for Solving the Problems In order to achieve the above object, the present inventors have conducted various experiments on manganese-activated zinc phosphate phosphor, and as a result, the particle surface of this phosphor was exposed to ultraviolet rays. It was found that by covering the phosphor particles that emit light, the fogging state can be checked by irradiating the phosphor screen with ultraviolet light.

The present invention was made on the basis of the above findings. The phosphor for a cathode ray tube according to the present invention is a manganese-activated zinc phosphate fluorescent compound represented by the chemical formula: Zn ₃ (PO ₄ ) ₂ : Mn. It is characterized in that the surface of the body particles is coated with particles that emit light when irradiated with ultraviolet rays.

Examples of the particles used in the present invention that emit light upon irradiation with ultraviolet rays include those composed of europium-activated rare earth oxide phosphors. In the phosphor of the present invention, the phosphor particles coated on the surface of the manganese-activated zinc phosphate phosphor particles must be a substance that efficiently emits light upon irradiation with ultraviolet rays, and also the manganese-activated zinc phosphate phosphor. Since it is a red-emitting phosphor, it is required to emit red light. The europium-activated rare earth oxide phosphor is most suitable for such a requirement. Lanthanum, yttrium, gadolinium and the like are suitable as the rare earth element in the europium-activated rare earth oxide phosphor.

Further, the coating amount of such a europium-activated rare earth oxide phosphor is preferably in the range of 1 to 10% by weight based on the weight of the manganese-activated zinc phosphate phosphor. If the coating amount of this phosphor is less than 1% by weight, the effect of the coating does not appear, and if the coating amount exceeds 10% by weight,
Fogging check of the obtained phosphor becomes easy,
The afterglow time is shortened, and in any case, it is not preferable as a high-resolution cathode ray tube phosphor.

The europium-activated rare earth oxide phosphor as described above is manufactured, for example, as follows. That is, first, 2 to 5 europium oxide is added to an oxide of a rare earth element such as yttrium oxide or gadolinium oxide.
The powder mixed at a mol% ratio is dissolved in an aqueous nitric acid solution, and then oxalic acid or methyl oxalate is added thereto to precipitate in the form of an oxalate salt. Then, the obtained oxalate salt is filtered and washed, and then charged into a quartz crucible, and 1300 to 15
By firing in air at a temperature of 00 ° C for 3 to 5 hours, europium-activated rare earth oxide phosphor particles can be obtained. In order to attach such phosphor particles to the manganese-activated zinc phosphate phosphor particles, it is appropriate to use an inorganic binder such as zinc hydroxide or an organic binder such as an acrylic resin emulsion.

Further, in the present invention, the organic fluorescent pigments shown below can be used as the particles that emit ultraviolet rays. That is, the particles covering the surface of the manganese-activated zinc phosphate phosphor particles emit light efficiently by irradiation with ultraviolet rays, and it is desirable that the emission color is red.
In the case of an organic material, it must be completely burned and removed in the baking step of removing the organic binder after the fluorescent screen of the cathode ray tube is formed. As an organic fluorescent pigment that satisfies such requirements, there is, for example, a reddish fluorescent pigment manufactured by Shin Loihi Co., Ltd. This fluorescent pigment is obtained by coloring melamine resin particles of several microns with a fluorescent dye of the rotamin system, and since the particle size is almost the same as the manganese-activated zinc phosphate phosphor particles to be coated, it is preliminarily ball milled. It is desirable to crush it to a suitable size before use. Further, in order to attach the organic fluorescent pigment particles thus pulverized to the manganese-activated zinc phosphate phosphor particles, it is appropriate to use an inorganic binder such as zinc hydroxide or an organic binder such as an acrylic resin emulsion. .

The coating amount of the above-mentioned organic fluorescent pigment is preferably in the range of 1 to 10% by weight with respect to the weight of the manganese-activated zinc phosphate phosphor. Coverage of organic fluorescent pigment is 1
If it is less than 10% by weight, the effect due to coating hardly appears, and if it exceeds 10% by weight, it becomes difficult to completely remove it in the organic binder removal step.

[0016]

EXAMPLES Examples of the present invention will be described below.

Example 1 50 g of europium-activated yttrium oxide (Y ₂ O ₃ : Eu) phosphor obtained by the above-mentioned method was added to 500 cc of pure water,
This was mixed with a ball mill for 24 hours to disperse the phosphor particles. Next, after removing the balls from this dispersion liquid, pure water was further added to bring the total volume to 5 liters. Then, 1000 g of manganese-activated zinc phosphate phosphor was added to this, and the mixture was stirred for about 30 minutes, and then a 1 mol / l zinc hydroxide aqueous solution 10
cc was added with stirring. Then, stirring was continued for 15 minutes, then an aqueous sodium hydroxide solution was added little by little until the pH reached 8.0, and stirring was further continued for 30 minutes, and then the dispersion liquid was allowed to stand. Then, after discarding the supernatant liquid and repeating washing three times with pure water, the dispersion liquid was filtered, dried and sieved to obtain a phosphor of the present invention.

When the phosphor thus obtained was irradiated with ultraviolet rays having a wavelength of 254 nm using a mercury lamp, it was confirmed that red light was emitted. In addition, using this phosphor,
The fluorescent screen of the cathode ray tube manufactured by a conventional method emitted good light when irradiated with ultraviolet rays, and the fogging check could be performed very easily.

Example 2 50 g of the europium-activated gadolinium oxide (Gd ₂ O ₃ : Eu) phosphor obtained by the above-described method was added to 500 cc of pure water, and this was mixed in a ball mill for 24 hours to obtain the above phosphor. The particles were dispersed. Next, after removing the balls from this dispersion liquid, pure water was further added to bring the total volume to 5 liters. Then, the manganese-activated zinc phosphate phosphor 100
After adding 0 g and stirring for about 30 minutes, 10 cc of polyacrylic ester emulsion (0.5 g in terms of solid matter) was added little by little while stirring. Then, stirring was further continued for 30 minutes, and then the dispersion liquid was allowed to stand. Next, after discarding the supernatant, washing with pure water was repeated 3 times, and then the dispersion was filtered, dried,
After screening, the phosphor of the present invention was obtained.

When the phosphor thus obtained was irradiated with ultraviolet rays having a wavelength of 254 nm using a mercury lamp, it was confirmed that red light was emitted. In addition, using this phosphor,
The fluorescent screen of the cathode ray tube manufactured by a conventional method emitted good light when irradiated with ultraviolet rays, and the fogging check could be performed very easily.

Example 3 50 g of organic fluorescent pigment FA-001 (trade name, manufactured by Shin Loihi Co., Ltd .; pigment particle size = 3 to 5 μm) was added to 500 cc of pure water, and this was ball-milled for about 7 days. Then, the size of the above fluorescent pigment is crushed to 1 μm or less, the balls are removed from this dispersion, and pure water is added to make the total amount 5
I made it to liters. Next, 1000 g of manganese-activated zinc phosphate phosphor was added to this dispersion, and the same operation as in Example 1 was added to obtain a phosphor of the present invention.

The phosphor thus obtained has an orange body color, and when it is irradiated with ultraviolet rays of 365 nm wavelength using a black light fluorescent lamp, it emits orange light. Was confirmed. In addition, the fluorescent surface of a cathode ray tube manufactured by a conventional method using this phosphor,
It emitted good light when irradiated with ultraviolet rays, and it was possible to perform fogging check very easily. Further, in the baking step after forming the fluorescent screen during the production of such a cathode ray tube, the organic fluorescent pigment attached to the manganese-activated zinc phosphate phosphor is completely burned and removed, and the characteristics of the obtained cathode ray tube are improved. Had no effect.

Example 4 The organic fluorescent pigment FA-001 was pulverized in the same manner as in Example 3 and pure water was added to make a total of 5 liters. Then, after adding 1000 g of manganese-activated zinc phosphate phosphor to this dispersion,
The same operation as in Example 2 was performed to obtain the phosphor of the present invention.

The phosphor thus obtained has a red body color, and it was confirmed that when it was irradiated with ultraviolet rays having a wavelength of 365 nm using a black light fluorescent lamp, red light was emitted. It was In addition, the phosphor screen of the cathode ray tube manufactured by a conventional method using this phosphor emits a good light when irradiated with ultraviolet rays, and the fogging check could be performed extremely easily. Furthermore, the organic fluorescent pigment adhering to the manganese-activated zinc phosphate phosphor is completely burned and removed in the baking step after forming the fluorescent screen of such a cathode ray tube, and there is no influence on the characteristics of the obtained cathode ray tube. There was no

As is clear from the above examples, the coated phosphor according to the present invention emits excellent light when irradiated with ultraviolet rays,
It is extremely useful for checking the fogging of the fluorescent screen. Further, manganese-activated zinc phosphate phosphor is known to be chemically slightly unstable in the slurry, but by coating with europium-activated rare earth oxide phosphor or organic fluorescent pigment Improves body stability.

[0026]

As described above, according to the present invention, it is possible to obtain a red light-emitting phosphor which exhibits a long afterglow and a high emission luminance and is easy to perform a fogging check by irradiation with ultraviolet rays.
By using this phosphor as a red light emitting component, it becomes possible to realize a cathode ray tube with high light emission brightness and no flicker on the screen, which greatly contributes to yield improvement and stabilization in the manufacture of cathode ray tubes and the like. .

[Brief description of drawings]

FIG. 1 is a diagram showing a state in which three color phosphors are applied in a dot matrix form on the panel inner surface of a cathode ray tube.

[Explanation of symbols]

 1 ... Phosphor screen

Claims (4)

[Claims] 1. A cathode ray, characterized in that the surface of manganese-activated zinc phosphate phosphor particles represented by the chemical formula: Zn ₃ (PO ₄ ) ₂ : Mn is coated with particles that emit light by ultraviolet irradiation. Tube phosphor. 2. The phosphor for a cathode ray tube according to claim 1, wherein the particles that emit light when irradiated with ultraviolet rays are a europium-activated rare earth oxide phosphor. 3. The cathode ray tube phosphor according to claim 2, wherein the coating amount of the europium-activated rare earth oxide phosphor is
1 to the weight of the manganese-activated zinc phosphate phosphor
A phosphor for a cathode ray tube, which is in the range of 10% by weight. 4. The phosphor for a cathode ray tube according to claim 1, wherein the particles that emit light when irradiated with ultraviolet rays are organic fluorescent pigments.