JPH10212473A - Cathode-ray tube and phosphor therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phosphor capable of preventing the charge-up of electron beams when used in especially a cathode-ray tube and remarkably improving the luminance by sticking a specific amount of fine tin oxide particles to surfaces of phosphor grains. SOLUTION: This phosphor is obtained by sticking fine tin oxide particles (SnO2 ) having <=0.5μm, preferably 0.01-0.1μm particle diameter in an amount of 0.05-0.5wt.% based on the weight of the phosphor grains to surfaces of the phosphor grains. For example, ZnS:Ag, Cl which is a blue light emitting substance or Y2 O2 S:Eu that is a red light emitting phosphor is cited as the phosphor grains. The objective phosphor is obtained by uniformly dispersing the phosphor grains in pure water, then adding the SnO2 particles powder to the resultant dispersion, further adding a polyacrylamide solution as an adhesive for fixing the phosphor grains to the SnO2 particles, stirring the prepared mixture for 1-2hr, then washing the dispersed phosphor grains, subsequently drying the washed grains at 100-200 deg.C and finally sieving the resultant massive phosphor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a phosphor for a cathode ray tube,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor layer and a cathode ray tube using the same, and particularly to a phosphor for a cathode ray tube, a phosphor layer, which can prevent charge-up of an electron beam when used in a cathode ray tube and can greatly improve emission luminance. The present invention relates to a cathode ray tube using the same.

[0002]

2. Description of the Related Art A cathode ray tube (CRT) used as a cathode ray tube for a color television or a computer terminal display generally has a structure as shown in FIGS. That is, the cathode ray tube for a color television cathode ray tube is formed by forming red (R), green (G), and blue (B) light emitting phosphor films 2 serving as three primary colors in a stripe shape or a dot shape on an inner surface of a face plate (panel) 1. A BC layer 3 made of carbon black is formed between the light emitting phosphor films 2 as shown in FIG.

[0003] Of the phosphors constituting each of the light-emitting phosphor films 2, as the blue light-emitting phosphor, zinc sulfide phosphor (ZnS: Ag, Cl) activated with silver and chlorine, and activated with silver and aluminum. Zinc sulfide phosphor (ZnS: Ag,
Al) is used, and as a green light-emitting phosphor, a zinc sulfide phosphor (ZnS:
Cu, Al), zinc sulfide phosphor activated by copper, gold and aluminum (ZnS: Cu, Au, Al) and manganese activated zinc silicate phosphor (Zn ₂ SiO ₄ : Mn) are used, and further red light emission is used. As the phosphor, europium-activated yttrium oxysulfide phosphor (Y ₂ O ₂ S: Eu), manganese-activated zinc phosphate phosphor (Zn ₃ (PO ₄ ) ₂ : Mn)
Etc. are widely used.

The above-mentioned various phosphors may be used as they are to form a phosphor film, or may be phosphor particles coated with filter particles for the purpose of improving contrast characteristics. The following are examples of the filter particles that cover the phosphor particles. That is,
Specific examples of the filter particles coated with the blue light-emitting phosphor particles include cobalt aluminate and ultramarine, while the filter particles that cover the red light-emitting phosphor particles include:
Bengala, cadmium sulfate selenide, etc. have been put to practical use.

[0005] As shown in FIG. 3, each phosphor film 2 and BC layer 3 are formed of an aluminum vapor-deposited film from the inside of the face plate 1 in order to prevent charge-up occurring when the phosphor is excited by an electron beam. 4 is covered. The aluminum vapor-deposited film 4 is bonded to the surface of the phosphor film 2 via a resin film such as a lacquer film, and is formed so as to cover the phosphor film 2 by evaporating a resin component by a baking process.

Then, in three electron guns 5 corresponding to the phosphors of each emission color (B, G, R), an electron beam 6 accelerated by a constant voltage of about 20 to 30 kV by an electron lens 7. The beam is converged, and the path is bent by the deflection yoke 8. Then, the three electron beams 6 passing through the shadow mask 9 are selectively irradiated to the phosphor film 2 to cause excitation light emission, and a color image composed of all colors is reproduced by additive color mixing of the respective light emissions. ing.

A cathode ray tube such as a cathode ray tube for a color television as described above is generally manufactured by the following method. First, after a resist is applied to the face plate of the cathode ray tube, a portion to which the phosphor is applied is irradiated with ultraviolet rays through a shadow mask to be exposed in stripes or dots. Next, the exposed portion is developed, and a slurry containing carbon black is applied and dried to form a BC layer. Next, the obtained face plate is subjected to a chemical treatment, and the resist resin cured in a stripe or dot pattern is dissolved and dried, and then the process proceeds to the next phosphor coating step.

[0008] In the phosphor coating step, a phosphor slurry is applied to a BC layer having stripe-shaped or dot-shaped holes, dried and exposed, and a process cycle of development and drying is performed on the phosphor corresponding to each of the three primary colors. By repeating the process three times, stripe-shaped or dot-shaped phosphor films made of red, green, and blue light-emitting phosphors are sequentially formed.

The thus formed phosphor film and BC
An aluminum vapor-deposited film is formed on the layer via a lacquer film, and the lacquer film component is volatilized by baking at a temperature of 400 to 500 ° C.,
Metal back processing is performed so that the phosphor film and the BC layer are covered with the aluminum vapor-deposited film.
By performing the sealing step, a cathode ray tube such as a cathode ray tube for color television is manufactured.

Factors for determining and evaluating the characteristics of the color cathode ray tube as described above include luminance, contrast, definition of image quality, and the like. In particular, the luminance is extremely important in evaluating the characteristics of the current cathode ray tube. It is a factor. Therefore, in order to improve the brightness of the color cathode ray tube from the past, to develop a high-luminance phosphor, to study a special filter to cover the phosphor particles, to adopt a face plate with high transmittance, Various improvements have been made, such as by reviewing the method of manufacturing a cathode ray tube.

[0011]

However, in the above-mentioned conventional color cathode ray tube, there is no escape route for electrons in the phosphor particles, which are insulators, and charges due to electron beams are accumulated, so that a so-called charge-up phenomenon is likely to occur. In addition, there is a problem that many portions do not emit light even when the phosphor film is irradiated with an electron beam, and the luminance of the cathode ray tube is greatly reduced.

[0012] In order to solve the above-mentioned problem, a phosphor screen of a color cathode ray tube is conventionally formed, and then a phosphor film surface is formed on the phosphor screen.
A countermeasure has been taken to prevent the charge-up phenomenon caused by the electron beam excitation by forming an aluminum vapor-deposited film serving as an escape path for electrons.

However, the above-mentioned aluminum vapor-deposited film is generally formed on the surface of the phosphor film via a resin film such as a lacquer film, and the resin component is volatilized by a subsequent baking treatment. There was a disadvantage that the adhesion to the deposited film was insufficient. Therefore, there is a problem that conduction between the two is insufficient, it is difficult to completely prevent the charge-up phenomenon, and the effect of improving the luminance of the cathode ray tube is small.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is particularly intended for a cathode ray tube capable of preventing charge-up of an electron beam when used in a cathode ray tube and capable of greatly improving emission luminance. An object of the present invention is to provide a phosphor, a phosphor layer, and a cathode ray tube using the same.

[0015]

Means for Solving the Problems In order to achieve the above object, the present inventors prepare a phosphor by attaching various fine particles to the surface of the phosphor particles, and use the phosphor for a color cathode ray tube. A phosphor film was formed, and the effects of the type and amount of the fine particles and the particle size on the emission luminance of the phosphor film were comparatively investigated.

As a result, it was found that when a predetermined amount of fine tin oxide (SnO ₂ ) particles were attached to the surface of the phosphor particles, the emission luminance of the cathode ray tube was greatly improved. Also,
The SnO ₂ particles are not adhered to the surface of the phosphor particles, and the Sn film is formed on the surface of the phosphor film previously formed with ordinary phosphor particles.
It has been found that a cathode ray tube having high emission luminance can be obtained even when a conductive film made of O ₂ particles is integrally formed. The present invention has been completed based on the above findings.

That is, in the phosphor for a cathode ray tube according to the present invention, tin oxide (SnO ₂ ) fine particles having a particle diameter of 0.5 μm or less are added to the phosphor particle surface in an amount of 0.05 to 0.05 wt.
It is characterized in that it is deposited in the range of 0.5% by weight.
Also, the particle diameter of the tin oxide fine particles is preferably in the range of 0.01 to 0.1 μm.

Further, in the cathode ray tube according to the present invention, tin oxide (SnO ₂ ) having a particle size of 0.5 μm or less is provided on the surface of the phosphor particles.
A phosphor layer comprising a phosphor for a cathode ray tube having fine particles adhered in a range of 0.05 to 0.5% by weight based on the weight of the phosphor particles is formed on the inner surface of the face plate.

The phosphor layer according to the present invention is characterized in that a conductive film made of tin oxide (SnO ₂ ) is integrally formed on a surface of a phosphor film made of a phosphor for a cathode ray tube.

Further, the cathode ray tube according to the present invention is characterized in that a conductive film made of tin oxide (SnO ₂ ) fine particles is formed on the surface of the fluorescent film formed on the inner surface of the face plate of the cathode ray tube.

Here, the phosphor particles used in the present invention are not particularly limited, and the following blue light-emitting phosphor, green light-emitting phosphor and red light-emitting phosphor corresponding to the three primary colors can be exemplified. That is, as the blue light-emitting phosphor, ZnS: Ag, Cl, ZnS: Ag, Al, cobalt aluminate pigment-coated ZnS: Ag, Cl, Zn
S: Ag, Al, ultramarine pigment coated ZnS: Ag, Cl, Z
nS: Ag, Al and the like.
ZnS: Cu, Al, ZnS: Cu, Au, Al, (Z
n, Cd) S: Cu, Al and the like. As the red light emitting phosphor, Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, Y
VO ₄ : Eu, and manganese pigment coated Y ₂ O ₂ S: Eu.

Further, tin oxide (SnO ₂ ) fine particles are chemically stable oxides having conductivity, and by adhering to the surface of the phosphor particles, the conductivity between the phosphor particles can be ensured, and the fluorescence can be reduced. When the body film is formed, it is possible to effectively prevent a charge-up phenomenon due to the electron beam irradiated to each phosphor particle.

On the other hand, by integrally forming a conductive film made of tin oxide having conductivity on the surface of the fluorescent film of the cathode ray tube, conduction between the fluorescent film and the aluminum vapor-deposited film disposed behind the fluorescent film is improved. Escape route is secured,
A cathode ray tube in which the charge-up phenomenon of electrons can be effectively prevented and emission luminance is improved can be obtained.

The tin oxide (SnO ₂ ) fine particles are attached in a range of 0.05 to 0.5% by weight based on the weight of the phosphor particles. When the amount of the tin oxide fine particles is less than 0.05% by weight, the effect of improving the emission luminance of the phosphor is insufficient. It is considered that since the ratio of tin oxide to the entire phosphor film becomes excessive, the emission luminance is rather lowered.

The particle size of tin oxide (SnO ₂ ) fine particles also has a large effect on the emission luminance.
The following SnO ₂ fine particles are used. If the particle size exceeds 0.5 μm, the effect of improving luminance is lost. Note that the particle size is 0.
Even when the thickness is less than 01 μm, the effect of improving luminance is small. A more preferred particle size range is from 0.01 to 0.1 μm.

The phosphor for a cathode ray tube according to the present invention is manufactured, for example, by the following procedure. That is, after the phosphor particles are put into pure water and uniformly dispersed, a predetermined amount of tin oxide particle powder is added, and a polyacrylamide solution for fixing the phosphor particles and the tin oxide particles is further used as an adhesive. And stir for 1-2 hours. The dispersed phosphor particles are washed several times with pure water to remove impurity ions and the like, and then filtered, and the residue is dried at a temperature of 100 to 200 ° C. Then, the phosphor according to the present invention is obtained by sieving the massive phosphor obtained after drying through a sieve.

According to the phosphor for a cathode ray tube having the above-described structure, since tin oxide fine particles having conductivity adhere to the surface of the phosphor particles, when the phosphor film is formed, the conductive particles between the phosphor particles are not electrically conductive. And the charge-up phenomenon of the electron beam can be effectively prevented. Further, when a conductive film made of tin oxide is formed on the surface of the fluorescent film of the cathode ray tube, an escape path for the irradiated electron beam is secured, and the charge-up phenomenon does not occur. Therefore, a cathode ray tube with improved light emission luminance can be obtained.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be specifically described with reference to the following examples.

Example 1 After 500 g of silver-activated zinc sulfide phosphor (ZnS: Ag) particles were dispersed in 1 liter of pure water, a conductive tin oxide (SnO ₂ ) fine particle having a particle size of 0.02 μm was fluoresced. It was added at a ratio of 0.2% by weight based on the body particle weight.
Further, 5 cc of a 0.1% polyacrylamide solution was added as an adhesive for more firmly attaching the tin oxide fine particles to the phosphor particle surfaces, and the mixture was stirred for 1 hour. The obtained phosphor was washed with pure water, dried and sieved to prepare a phosphor for a cathode ray tube according to Example 1.

Example 2 In Example 1, the amount of the tin oxide fine particles added was set to 0.
A phosphor for a cathode ray tube according to Example 2 was prepared by treating under the same conditions as in Example 1 except that the content was changed to 4% by weight.

Example 3 In Example 1, the amount of the tin oxide fine particles added was set to 0.
A phosphor for a cathode ray tube according to Example 3 was prepared by treating under the same conditions as in Example 1 except that the content was changed to 05% by weight.

Example 4 Copper and aluminum activated zinc sulfide phosphor (ZnS: C
u, Al) particles are dispersed in 1 liter of pure water, and then conductive tin oxide (SnO ₂ ) fine particles having a particle size of 0.1 μm are dispersed at a ratio of 0.05% by weight to the phosphor particles. It was added so that it might become. Further, 2 cc of a zinc nitrate solution having a concentration of 0.8 mol / liter was added, and the pH of the dispersion was adjusted to 9.0 with aqueous ammonia, followed by stirring for 1 hour. The obtained phosphor was washed with pure water, dried and sieved to prepare a cathode ray tube phosphor according to Example 4.

Example 5 In Example 4, the amount of tin oxide fine particles added was set to 0.
A phosphor for a cathode ray tube according to Example 5 was prepared by treating under the same conditions as in Example 4 except that the amount was changed to 1% by weight.

Example 6 The procedure of Example 4 was repeated except that the amount of the tin oxide fine particles added was set to 0.
A phosphor for a cathode ray tube according to Example 6 was prepared by treating under the same conditions as in Example 4 except that the content was changed to 3% by weight.

Using the phosphors for cathode ray tubes according to Examples 1 to 6 prepared as described above, a phosphor film 2 is formed on the inner surface of the face plate 1 of the cathode ray tube as shown in FIG. Manufactured. The emission luminance of each cathode ray tube was measured. The light emission luminance is based on the light emission luminance of a cathode ray tube formed using phosphor particles to which conductive tin oxide fine particles are not adhered as a reference value (1).
00%) as a relative value. Table 1 shows the measurement results.
Shown in

Example 7 A three-color phosphor film was formed on the inner surface of the face plate of a cathode ray tube by a conventional method. Next, by spin-coating a 0.2% dispersion of conductive tin oxide having a particle size of 0.02 μm on the surface of the phosphor film and then drying, a tin oxide (SnO 2 ₂ ) A phosphor layer 11 integrally formed with the conductive film 10 was formed. Further, the color cathode ray tube according to the seventh embodiment as shown in FIGS. 1 and 2 was manufactured through a normal cathode ray tube manufacturing process such as forming an aluminum vapor deposition film 4 on the inner surface side of the phosphor layer 11. .

Example 8 A three-color phosphor film was formed on the inner surface of the face plate of a cathode ray tube by a conventional method. Next, a 0.2% dispersion of conductive tin oxide having a particle size of 0.1 μm is spin-coated on the surface of the phosphor film and then dried to form tin oxide (SnO 2) as shown in FIG. ₂ ) A phosphor layer 11 integrally formed with the conductive film 10 was formed. 1 and 2 through a normal cathode ray tube manufacturing process such as forming an aluminum vapor-deposited film 4 on the inner surface side of the phosphor layer 11.
The color cathode ray tube according to Example 8 shown in FIG.

The emission luminance of the cathode ray tubes according to Examples 7 and 8 was measured. In addition, each light emission luminance was shown as a relative value, using the light emission luminance of a cathode ray tube without a conductive film made of conductive tin oxide as a reference value (100%). The measurement results are shown in Table 1 below.

[0039]

[Table 1]

As is clear from the results shown in Table 1 above,
In the cathode ray tubes using the phosphors of Examples 1 to 6 in which tin oxide (SnO ₂ ) fine particles are adhered to the surface of the phosphor particles in a predetermined amount, the conduction of electrons is improved by the conductive tin oxide particles. In addition, it was confirmed that the emission luminance was effectively improved to about 2 to 8% as compared with the case where a phosphor which did not cause a charge-up phenomenon and did not adhere to tin oxide was used.

In addition to the case where tin oxide fine particles are adhered to the surface of the phosphor particles as described above, as shown in Examples 7 and 8, a conductive film made of tin oxide is formed on the surface of the phosphor film formed in advance. Even when integrally formed, the conduction between the phosphor film and the aluminum vapor-deposited plate provided on the back side thereof is improved, so that the electron beam charge-up phenomenon does not occur, and the emission luminance of the cathode ray tube is reduced as described above. It has been found that this is greatly improved by 7 to 10% as compared with the case where the conductive film is not formed.

FIG. 4 shows a cathode ray tube in which tin oxide (SnO ₂ ) particles having a particle size of 0.02 μm are attached in a range of 0 to 0.6% by weight based on the weight of the silver-activated zinc sulfide phosphor particles. 5 is a graph showing relative luminance.

In FIG. 4, the amount of SnO ₂ particles deposited is 0.
The effect of improving luminance is small in a range as small as less than 05% by weight, but the luminance increases as the amount of adhesion increases to 0.05% by weight or more, and peaks when the amount of adhesion is in the range of 0.1 to 0.2% by weight. On the other hand, the brightness tends to decrease as the content exceeds 0.2% by weight. The above decreasing tendency of the brightness is
It is considered that the ratio of non-light-emitting substances such as tin oxide occupying the surface of the phosphor particles increases.

In place of the conductive tin oxide particles, non-conductive particles such as silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ) and titanium oxide (TiO ₂ ) are replaced with phosphor particles. The luminance characteristics were compared by attaching to the surface. As a result, when the amount of adhesion increases, the luminance decreases as in the case of tin oxide, but the amount of adhesion is 0.1.
In the range of from 02 to 0.5% by weight, the effect of improving luminance unlike tin oxide was not obtained.

The reason why the brightness of the cathode ray tube can be improved when tin oxide is used is that the phosphor surface is coated (adhered) with conductive tin oxide fine particles, so that the phosphor film and the back thereof are covered. It is considered that conduction with the deposited aluminum deposited film is improved, and charge-up is less likely to occur.

[0046] Also FIG. 5, the relationship between the adhesion amount and the relative luminance of the SnO ₂ particles to adhere to the surfaces of phosphor particles, SnO ₂
4 is a graph showing a particle diameter d of a particle as a parameter.
That is, there is an adhesion amount range in which the luminance can be improved when the particle diameter d of the SnO ₂ particles is finer than 0.5 μm, and when the particle diameter d is 0.5 μm or more, the luminance is improved in the entire adhesion amount range. Will not be recognized.

[0047]

As described above, according to the phosphor for a cathode ray tube according to the present invention, since tin oxide fine particles having conductivity adhere to the surface of the phosphor particles, when the phosphor film is used as the phosphor film, Conductivity can be secured between the body particles, and the charge-up phenomenon of the electron beam can be effectively prevented. Further, when a conductive film made of tin oxide is formed on the surface of the fluorescent film of the cathode ray tube, an escape path for the irradiated electron beam is secured, and the charge-up phenomenon does not occur. Therefore, a cathode ray tube with improved light emission luminance can be obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a main part of a cathode ray tube according to the present invention.

FIG. 2 is a sectional view showing a schematic configuration of a cathode ray tube.

FIG. 3 is an enlarged sectional view of a portion III in FIG. 2, showing a fluorescent screen of a conventional cathode ray tube.

FIG. 4 is a graph showing the relationship between the amount of tin oxide particles attached and relative luminance.

FIG. 5 is a graph showing the relationship between the amount of tin oxide particles attached and the relative luminance, with the diameter of the tin oxide particles as a parameter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Face plate (panel) 2 Phosphor film (phosphor film) 3 BC layer 4 Aluminum vapor deposition film 5 Electron gun 6 Electron beam 7 Electron lens 8 Deflection yoke 9 Shadow mask 10 Conductive film 11 Phosphor layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09K 11/82 CQA C09K 11/82 CQA 11/84 CPD 11/84 CPD H01J 29/20 H01J 29/20 29/28 29/28

Claims (5)

[Claims] 1. The method according to claim 1, wherein tin oxide (SnO ₂ ) fine particles having a particle size of 0.5 μm or less are attached to the surface of the phosphor particles in a range of 0.05 to 0.5% by weight based on the weight of the phosphor particles. Characteristic phosphor for cathode ray tubes. 2. The tin oxide fine particles having a particle size of 0.01 to 0.1.
2. The phosphor for a cathode ray tube according to claim 1, wherein the thickness is in a range of 1 [mu] m. 3. A cathode ray tube having tin oxide (SnO ₂ ) fine particles having a particle size of 0.5 μm or less adhered to phosphor particle surfaces in a range of 0.05 to 0.5% by weight based on the weight of the phosphor particles. A cathode ray tube wherein a phosphor layer made of a phosphor is formed on an inner surface of a face plate. 4. A phosphor layer wherein a conductive film made of tin oxide (SnO ₂ ) is integrally formed on a surface of a phosphor film made of a phosphor for a cathode ray tube. 5. A cathode ray tube wherein a conductive film made of tin oxide (SnO ₂ ) fine particles is formed on a surface of a fluorescent film formed on an inner surface of a face plate of the cathode ray tube.