JP2000136382A - Red-emitting phosphor for cathode-ray tube, and cathode- ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the fineness of a fluorescent film formed by using a red- emitting phosphor for cathode ray tubes and thus enhance the luminance of the fluorescent film. SOLUTION: This red-emitting phosphor for cathode-ray tubes having a phosphor powder comprises yttrium oxysulfide as a phosphor matrix and has such particle size distribution that the medium-particle-size red-emitting phosphor consists of a 15% or lower fraction having a particle size larger than 4.0 μm, a 75% or higher fraction having a particle size of 4.0 μm or larger and smaller than 8.0 μm, and a 10% or lower fraction having a particle size of 8.0 μm or larger and that the large-particle-size red-emitting phosphor consists of a 20% or less fraction having a particle size smaller than 5.04 μm, a 70% or more fraction having a particle size of 5.04 μm or larger and smaller than 10.079 μm, and a 10% or less fraction having a particle size of 10.079 μm or larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a red light emitting phosphor used for forming a fluorescent film of a cathode ray tube such as a color cathode ray tube, and a cathode ray tube using the same.

[0002]

2. Description of the Related Art A fluorescent film of a color cathode ray tube is generally manufactured as follows. That is, first, a phosphor is dispersed in an aqueous solution containing polyvinyl alcohol (PVA), ammonium bichromate, and a surfactant to prepare a phosphor slurry. This is applied to a glass panel to form a phosphor coating film. Next, the phosphor coating film is irradiated with ultraviolet rays through a shadow mask, and the irradiated portion PV is irradiated.
A is cured. The fluorescent film other than the portion cured by development is removed. Thus, a stripe-like or dot-like fluorescent film is formed.

When a phosphor film is formed by applying the above-described coating method, the phosphor is required to have the following characteristics. (1) A dense stripe-shaped or dot-shaped fluorescent film can be formed. (2) No color mixing occurs. (3)
Strong adhesion to panel. (4) A sufficient fluorescent film thickness can be obtained. Further, the pigment-attached phosphor is required to be free from pigment peeling in the slurry solution.

Conventionally, various improvements and developments have been made by applying a surface treatment to the phosphor in order to satisfy the above-mentioned required properties of the phosphor. For example, Japanese Patent Laid-Open No. 54-10
JP-A-2299 and JP-B-59-8310 describe a treatment method for improving the dispersibility by bringing a pigment-attached phosphor into contact with a water-soluble organic compound solution.

Also, Japanese Patent Publication No. Sho 60-21675, Japanese Patent Publication No. Sho 61-4
JP-A-6512 and JP-B-62-39186 describe a method for improving the dispersibility of a phosphor by attaching an inorganic compound to the phosphor surface. Further, Japanese Patent Application Laid-Open No. 2-178387 describes a method for improving the sedimentability of a phosphor in a slurry solution by attaching an inorganic compound and an organic compound to the surface of the phosphor.

[0006]

As described above, the quality of the phosphor film has been improved to some extent by the surface treatment of attaching an inorganic compound or an organic compound to the phosphor. However, with the recent expansion of the computer market, color cathode ray tubes are required to have higher performance for computer displays, and the fluorescent films used therein are also required to have higher quality. In particular, there is a strong demand for higher contrast. Further, in a cathode ray tube for a color television, in order to increase the area and the definition, a high quality of the fluorescent film, particularly, a high contrast is required.

One method of achieving high contrast is to improve the light emission luminance of the fluorescent film. In order to improve the light emission luminance of the phosphor film, it is conceivable to improve the light emission luminance of the phosphor itself or to form a more dense phosphor film to improve the light emission luminance of the phosphor film.

Here, the present inventors have paid attention to the improvement of the emission luminance based on the densification of the fluorescent film and the enhancement of the contrast of the color cathode ray tube, and have investigated in detail the quality of the conventional fluorescent film for a color cathode ray tube. As a result, it was found that the density of the film made of the red light-emitting phosphor was significantly lower than that of the films made of the green and blue light-emitting phosphors. The low density of the film due to the red light-emitting phosphor is not related to the order of applying the three color phosphors.

As described above, by improving the density of the phosphor film made of the red light-emitting phosphor, it is possible to improve the luminance of the red light-emitting phosphor film and to realize a high contrast of the color cathode ray tube. It becomes possible. However, conventional red light-emitting phosphors cannot achieve such densification of the fluorescent film.

Japanese Patent Application Laid-Open No. 3-220286 discloses a particle size of 8.
Red light-emitting phosphor (particles based on yttrium oxysulfide) with a particle size distribution of coarse particles of 01 μm or more of 10% or less
Is described. Thus, the density of the red light emitting phosphor film cannot be sufficiently increased only by reducing the ratio of the coarse particles.

Japanese Patent Application Laid-Open No. 8-41453 discloses a method for producing a rare earth oxysulfide phosphor in which a rare earth oxide raw material is mixed with an alkali metal carbonate, an aluminum compound and a sulfur raw material, and the mixture is fired. Have been. The embodiment of this _{publication, -log (d 84 / d 50} ) and _{+ log (d 16 / d 50} ) is described as a particle size distribution. However, the red light-emitting phosphor having the particle size distribution shown here cannot sufficiently increase the film density.

The present invention has been made to address such a problem, and an object of the present invention is to provide a red light emitting phosphor for a cathode ray tube, which is capable of obtaining a highly dense fluorescent film with good reproducibility. It is another object of the present invention to provide a cathode ray tube in which the luminance of a phosphor film is improved by using such a red light emitting phosphor and, as a result, a high contrast is realized.

[0013]

According to a first aspect of the present invention, there is provided a red light emitting phosphor for a cathode ray tube, comprising a phosphor powder containing yttrium oxysulfide as a base. A phosphor, wherein the phosphor powder has a particle size
15% or less of components less than 4.0μm, particle size 4.0μm or more 8.0
75% or more of components less than μm and components with a particle size of 8.0 μm or more
It is characterized by having a particle size distribution of 10% or less.

The first red light emitting phosphor for a cathode ray tube is, for example, a medium particle type red light emitting phosphor having a cumulative particle size distribution having a 50% D value of, for example, not less than 5.0 μm and not more than 6.5 μm. It defines the particle size distribution of the body.
Such a medium particle type red light emitting phosphor is suitable for a cathode ray tube for a computer display.

The second red light emitting phosphor for a cathode ray tube according to the present invention is a red light emitting phosphor for a cathode ray tube comprising a phosphor powder containing yttrium oxysulfide as a base, In the phosphor powder, components having a particle size of less than 5.04 μm have a particle size distribution of 20% or less, components having a particle size of 5.04 μm to less than 10.079 μm have a particle size distribution of 70% or more, and components having a particle size of 10.079 μm or more have a particle size distribution of 10% or less. It is characterized by.

The second red light emitting phosphor for a cathode ray tube is a large particle type red light emitting phosphor having a cumulative particle size distribution having a 50% D value of, for example, 6.5 μm or more and 8.0 μm or less. It defines the particle size distribution of the body.
Such a large particle type red light emitting phosphor is suitable for a cathode ray tube for color television.

According to a thirteenth aspect of the present invention, there is provided a first cathode ray tube, comprising: a panel constituting an envelope; and a red color for the first cathode ray tube of the present invention formed on an inner surface of the panel. It is characterized by comprising a phosphor film containing a light emitting phosphor and an electron source for irradiating the phosphor film with an electron beam. The first cathode ray tube of the present invention is suitable for a computer display, for example.

According to a second aspect of the present invention, there is provided a second CRT for a cathode ray tube formed on an inner surface of the panel. It is characterized by comprising a phosphor film containing a light emitting phosphor and an electron source for irradiating the phosphor film with an electron beam. The second cathode ray tube of the present invention is suitable for, for example, color television.

In the present invention, the particle size distribution of the red light-emitting phosphor for a cathode ray tube having yttrium oxysulfide as a base is optimized. That is, as a result of investigating the relationship between the particle size distribution of the phosphor and the denseness of the phosphor film, it was found that the sharpness of the particle size distribution of the red light-emitting phosphor significantly improved the denseness of the phosphor film. By using the red light-emitting phosphor of the present invention whose particle size distribution has been optimized based on such knowledge, it is possible to greatly improve the denseness of the phosphor film.

As described above, the film made of the conventional red light-emitting phosphor was significantly inferior in density to the films made of green and blue light-emitting phosphors. The denseness of the film by such a red light emitting phosphor can be greatly improved by optimizing the particle size distribution. According to the cathode ray tube having the dense fluorescent film, the luminance can be improved. Therefore, it is possible to provide a high-contrast, high-quality cathode ray tube.

[0021]

Embodiments of the present invention will be described below.

The red light emitting phosphor for a cathode ray tube according to the present invention is based on yttrium oxysulfide. A typical example is europium-activated yttrium oxysulfide (Y ₂
O ₂ S: Eu) phosphor. In addition to europium (Eu), Tb, P
A rare earth element such as r, Er, or Sm may be contained as a co-activator, and may further contain W, Sb, or the like.

Eu as an activator is preferably contained in the range of 3 to 8% by weight. 3% by weight of Eu
If it is less than 3, the emission color becomes orange, and the characteristics as a red emission component deteriorate. On the other hand, the Eu content is 8 weight
%, The brightness may be reduced. Tb,
Other rare earth elements such as Pr, Er, Sm, and also W, S
When using a coactivator such as b, 0.0001 to 1 weight
%.

The phosphor material for emitting red light in the present invention is not limited to the above-described europium-activated yttrium oxysulfide phosphor, and various phosphors based on yttrium oxysulfide may be used. it can.

The first red-light-emitting phosphor for a cathode ray tube according to the present invention has a particle size distribution of the red-light-emitting phosphor based on yttrium oxysulfide as described above.
15% or less, 75% of components with a particle size of 4.0μm or more and less than 8.0μm
As described above, the composition is such that the component having a particle size of 8.0 μm or more is 10% or less. The particle size distribution in the present invention is a value measured by the Coulter counter method.

The first red light emitting phosphor for a cathode ray tube is a medium particle type red light emitting phosphor having a 50% D value of, for example, not less than 5.0 μm and not more than 6.5 μm. Here, the 50% D value is the particle size when the cumulative particle size distribution is 50%. Among the medium-particle type red light-emitting phosphors, a type in which the 50% D value of the cumulative particle size distribution is, for example, less than 5.0 μm tends to have a lower luminance, and depending on the application, there is a possibility that the quality of the product may be reduced. The medium particle type red light emitting phosphor is used, for example, in a cathode ray tube for a computer display.

In the medium-particle type red light-emitting phosphor powder, relatively coarse particles having a particle diameter of 8.0 μm or more particularly cause a reduction in the density of the phosphor film. Shall be 10% or less. The ratio of components having a particle size of 8.0 μm or more is particularly preferably 8% or less. On the other hand, the particle size
Relatively fine particles having a size of less than 4.0 μm cause a reduction in luminous efficiency and, similarly to coarse particles, cause a reduction in denseness of the phosphor film. Therefore, the abundance ratio in the phosphor powder is
15% or less. 10% of components with particle size less than 4.0μm
It is more preferable to set the following.

In other words, a particle size of 4.0 μm or more that is suitable for forming a dense fluorescent film and has excellent luminous efficiency.
By sharpening the particle size distribution of the medium-particle type red light emitting phosphor so that the component less than 8.0 μm is 75% or more, it is possible to greatly improve the denseness of the phosphor film using it. Become. More preferably, the proportion of the components having a particle size of 4.0 μm or more and less than 8.0 μm is 82% or more.

The second red light-emitting phosphor for a cathode ray tube according to the present invention has a particle size distribution of the red light-emitting phosphor based on yttrium oxysulfide as described above in which a component having a particle diameter of less than 5.04 μm is included.
20% or less, components with particle size of 5.04μm or more and less than 10.079μm
The composition is such that 0% or more and components with a particle size of 10.079 μm or more are 10% or less.

The second red light emitting phosphor for a cathode ray tube is a large particle type red light emitting phosphor having a 50% D value of, for example, 6.5 μm or more and 8.0 μm or less. For a large particle type red light emitting phosphor, the 50% D value of the cumulative particle size distribution is, for example,
Types exceeding 8.0 μm tend to have poor film quality. The large particle type red light emitting phosphor is used, for example, in a cathode ray tube for color television.

In the large-particle-type red light-emitting phosphor powder, relatively coarse particles having a particle diameter of 10.079 μm or more particularly cause a reduction in the density of the phosphor film. Shall be 10% or less. The proportion of components having a particle size of 10.079 μm or more is particularly preferably 8% or less. On the other hand, relatively fine particles having a particle size of less than 5.04 μm cause a decrease in luminous efficiency and, similarly to coarse particles, cause a decrease in denseness of the phosphor film. For this reason, the content ratio in the phosphor powder should be 20% or less. The ratio of components with particle size less than 5.04μm is 1
More preferably, it is 5% or less.

In other words, a particle size of 5.04 μm or more that is suitable for forming a dense fluorescent film and has excellent luminous efficiency.
By sharpening the particle size distribution of the large particle type red light emitting phosphor so that the component less than 0.079 μm is 70% or more, it is possible to greatly improve the denseness of the phosphor film using it. Become. Particle size 5.04μm or more 10.079μm
It is further preferable that the proportion of the component less than 75% is 75% or more.

In the conventional red light emitting phosphor for a cathode ray tube, a component having a very small emission efficiency of 2 μm or less in particle size and a component having a particle size of 20 μm or more, which is liable to become defective when a phosphor film is formed, are used as much as possible. Only the removal process has been taken, and the regulation and control of the particle size distribution as in the present invention have not been implemented.

According to the present invention, as a result of investigating the relationship between the particle size distribution of the phosphor and the denseness of the phosphor film, it was found that the sharpness of the particle size distribution of the red light emitting phosphor improves the denseness of the phosphor film. Based on this, the particle size distribution as described above is adopted. In the present invention, the particle size distribution is defined corresponding to the medium particle type and large particle type red light emitting phosphors, respectively. By using the red light emitting phosphor for a cathode ray tube of the present invention having such a particle size distribution, it is possible to greatly improve the density of a phosphor film made of the red light emitting phosphor.

The red light emitting phosphor for a cathode ray tube of the present invention can be prepared, for example, by the following method.

That is, first, a red light-emitting phosphor such as a europium-activated yttrium oxysulfide phosphor is put in pure water and sufficiently stirred. Next, stirring of the phosphor slurry is stopped, and the phosphor is allowed to settle for a certain time. Thereafter, the upper slurry up to a predetermined height is removed by siphon. The fine particle component can be removed by such means. If necessary, water glass or the like may be previously added to the slurry. Further, the same operation is performed to remove the lower slurry up to a predetermined height. by this,
Coarse particle components can be removed.

By removing the fine particle component and the coarse particle component in this manner, the medium particle type
75% or more of components with a size of 4.0μm or more and less than 8.0μm, 70% of components with a particle size of 5.04μm or more and less than 10.079μm for large particle type
The red light-emitting phosphor of the present invention having a very sharp particle size distribution as described above for a cathode ray tube can be prepared. The particle size distribution for each type can be obtained by controlling the height of the slurry when removing the fine particle component and the coarse particle component, respectively.

The red light emitting phosphor for a cathode ray tube of the present invention can be similarly prepared by classifying or screening a commercially available red light emitting phosphor for a cathode ray tube. It is also important to appropriately select a flux, a firing container, firing conditions, and the like in the process of synthesizing the red light-emitting phosphor. Thereby, a red light-emitting phosphor having a particle size distribution suitable for the purpose can be prepared.

The cathode ray tube of the present invention is provided with a phosphor film containing the above-mentioned red light emitting phosphor for a cathode ray tube of the present invention. FIG. 1 is a sectional view showing a configuration of a main part of a color cathode ray tube according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a panel portion having a fluorescent film 2 formed on the inner surface. The fluorescent film 2 has a dot shape or a stripe shape. The dot-shaped fluorescent film is effective for a cathode ray tube (CDT) for a computer display. The stripe-shaped fluorescent film is effective for a cathode ray tube (CPT) for color television.

Inside the panel section 1, a shadow mask 3 is arranged to face the fluorescent film 2 formed on the inner surface thereof with a predetermined gap. The shadow mask 3 has a large number of pores or slits not shown. The panel part 1 has a neck part 5 via a funnel part 4.
Is connected. An electron gun 6 is provided on the neck 5. The electron beam emitted from the electron gun 6 is applied to the fluorescent film 2 through the fine holes and slits of the shadow mask 3.

In the color cathode ray tube shown in FIG.
The first or second red light-emitting phosphor for a cathode ray tube according to the present invention is used as the red light-emitting phosphor of the phosphor film 2 which emits light upon irradiation with an electron beam from the light source. Here, as a phosphor other than the red light-emitting phosphor when forming the color cathode ray tube, for example, a known phosphor that is conventionally used can be used as a green light-emitting phosphor or a blue light-emitting phosphor. For example, as a green light emitting phosphor, ZnS: Cu, Al, Z
nS: Cu, Au, Al or the like is used. As the blue light emitting phosphor, ZnS: Ag, ZnS: Ag, Cl, or the like is used.

The cathode ray tube of the present invention has a phosphor film containing a red light-emitting phosphor (medium particle type or large particle type) whose particle size distribution is sharply regulated. Here, in the conventional cathode ray tube, the denseness of the phosphor film made of the red light emitting phosphor was remarkably inferior to that of the phosphor film made of the green and blue light emitting phosphors. In view of such a point, in the present invention, by optimizing the particle size distribution, the denseness of the film made of the red light-emitting phosphor is greatly improved, so that a very dense dot-shaped or striped fluorescent film is formed. Can be obtained. As a result, it is possible to improve the brightness of a color cathode ray tube having such a fluorescent film, and to provide a high-contrast, high-quality color cathode ray tube.

[0044]

EXAMPLES Next, specific examples of the present invention and evaluation results thereof will be described.

Example 1 First, europium-activated yttrium oxysulfide phosphor 1 kg
Was dispersed in 8 L (liter) of pure water. 3.3 cc of water glass (containing 25% of Si) was added to the dispersion, and the mixture was stirred for 30 minutes. After stirring, the mixture was allowed to stand for 60 minutes, and 6 L of the slurry was removed from the top of the phosphor slurry with a siphon.

Further, 6 L of pure water was added and stirred for 30 minutes. Thereafter, the mixture was allowed to stand for 15 minutes, and 6 L of the slurry was taken out from the lower part of the phosphor slurry with a siphon. The phosphor slurry thus treated was washed with pure water, filtered and dried. After sufficiently drying, the mixture was sieved with a 400 mesh sieve to obtain a first red light-emitting phosphor (medium particle type) of the present invention.

The particle size distribution of the red light-emitting phosphor thus obtained was measured by the Coulter counter method. Table 1 shows the results. 50% of the cumulative particle size distribution of this red phosphor
The D value was 5.8 μm.

Comparative Example 1 in Table 1 is a conventional red light-emitting phosphor, in which only components having a very low luminous efficiency and having a particle size of 2 μm or less, and components having a particle size of 15 μm or more, which are liable to cause bumpiness, are removed. It adopts a process that does Comparative Example 2 shows a conventional red light-emitting phosphor (JP-A-8-41453).
This is a process that removes only components having a particle size of 10 μm or more.

[0049]

[Table 1]

FIG. 2 shows the particle size distributions of the red light emitting phosphors of Example 1, Comparative Example 1 and Comparative Example 2. As is clear from FIG. 2, the red light-emitting phosphor of Example 1 has a sharper particle size distribution than Comparative Examples 1 and 2.
Particle size that contributes to densification of fluorescent film and improvement of luminous efficiency
It can be seen that the ratio of components having a size of 4.0 μm or more and less than 8.0 μm is extremely high.

Using each of the red light-emitting phosphors of Example 1, Comparative Example 1 and Comparative Example 2 described above, phosphor slurries were prepared in the usual manner. These were applied on a panel for a color cathode-ray tube by an ordinary method to form fluorescent films. The state of each fluorescent film thus formed was observed with an optical microscope. As a result, it was confirmed that the fluorescent film using the red light-emitting phosphor of Example 1 was more dense than the fluorescent films using the red light-emitting phosphor of Comparative Examples 1 and 2.

FIGS. 3 and 4 show the measurement results of the transmittance of each fluorescent film according to Example 1 and Comparative Example 1. FIG. FIG. 3 shows the transmittance of the fluorescent film according to Example 1, and FIG. 4 shows the transmittance of the fluorescent film according to Comparative Example 1. Assuming that the average transmittance of the phosphor film according to Comparative Example 1 is 100, the average transmittance of the phosphor film according to Example 1 is
90, which indicates that the compactness has been improved by 10%. The improvement in the denseness was also apparent from the SEM observation of the fluorescent film. In particular, removal of large particle components of 8 μm or more was effective.

Further, the emission luminance of each fluorescent film (red single color)
Of the phosphor film of Comparative Example 1
The light emission luminance of the phosphor film of Example 1 was 110. The light emission luminance of the phosphor film of Comparative Example 2 was 102. Since the denseness of the red light-emitting phosphor film was improved, the aluminum film-forming property was also improved. As a result, the luminance of green and blue was improved by 5% and 2%, respectively, and the luminance of white was also improved by 7%. As described above, by using the medium particle type red light emitting phosphor of the present invention, the light emission luminance of the phosphor film can be improved. This greatly contributes to higher contrast and higher quality of the color cathode ray tube.

Example 2 First, europium-activated yttrium oxysulfide phosphor 1 kg
Was dispersed in 8 L of pure water. This dispersion was mixed with water glass (Si
Was added, and the mixture was stirred for 30 minutes. After stirring 1
After leaving still for 20 minutes, 6 L of the slurry was removed from the top of the phosphor slurry with a siphon.

Further, 6 L of pure water was added and stirred for 30 minutes. Thereafter, the mixture was allowed to stand for 15 minutes, and 6 L of the slurry was taken out from the lower part of the phosphor slurry with a siphon. The phosphor slurry thus treated was washed with pure water, filtered and dried. After sufficiently drying, the mixture was sieved with a 400 mesh sieve to obtain a first red light-emitting phosphor (medium particle type) of the present invention.

The particle size distribution of the obtained red light emitting phosphor was measured by the Coulter counter method. Table 2 shows the results. The 50% D value of the cumulative particle size distribution of this red phosphor is
It was 5.6 μm.

[0057]

[Table 2]

Using the red light-emitting phosphor of Example 2 described above, a phosphor slurry was prepared by an ordinary method. This was applied on a panel for a color cathode-ray tube by an ordinary method to form a fluorescent film. When the transmittance of the obtained fluorescent film was measured, assuming that the average transmittance of the fluorescent film according to Comparative Example 1 was 100, the average transmittance of the fluorescent film according to Example 2 was 88, which was also the same as in Example 1. It was confirmed that the compactness was improved.

Further, when the emission luminance of the fluorescent film according to Example 2 was measured, it was found that the luminance was monochromatic red and 8% higher than that of the fluorescent film according to Comparative Example 1. It was also confirmed that the white luminance was improved by 7%.

Examples 3 to 6 Red light-emitting phosphors having various particle size distributions were prepared in the same manner as in Examples 1 and 2. Table 3 shows the particle size distribution of each red light emitting phosphor according to Examples 3 to 6, and the results of evaluating the luminance of each phosphor film using the same. In each of the phosphor films, a 5 to 10% improvement in luminance over the phosphor film of Comparative Example 1 was observed.

[0061]

[Table 3]

Example 7 First, europium-activated yttrium oxysulfide phosphor 1 kg
Was dispersed in 8 L (liter) of pure water. 3.3 cc of water glass (containing 25% of Si) was added to the dispersion, and the mixture was stirred for 30 minutes. After stirring, the mixture was allowed to stand for 90 minutes, and 6 L of the slurry was removed from the top of the phosphor slurry with a siphon.

Further, 6 L of pure water was added and stirred for 30 minutes. Thereafter, the mixture was allowed to stand for 10 minutes, and 6 L of the slurry was taken out from the lower part of the phosphor slurry with a siphon. The phosphor slurry thus treated was washed with pure water, filtered and dried. After sufficiently drying, the resultant was sieved with a 400 mesh sieve to obtain a second red light-emitting phosphor (large particle type) of the present invention.

The particle size distribution of the red light-emitting phosphor thus obtained was measured by the Coulter counter method. Table 4 shows the results. 50% of the cumulative particle size distribution of this red phosphor
The D value was 7.0 μm. Comparative Example 3 in Table 4 is a conventional red light-emitting phosphor, and has a particle diameter with extremely low luminous efficiency.
Ingredients of 2μm or less, and particle size of 20
It adopts a process that removes only components of μm or more.

[0065]

[Table 4]

Using each of the red light-emitting phosphors of Example 7 and Comparative Example 3 described above, phosphor slurries were prepared in the usual manner. These were applied on a panel for a color cathode-ray tube by an ordinary method to form fluorescent films. The state of each fluorescent film thus formed was observed with an optical microscope. As a result, the fluorescent film using the red light emitting phosphor of Example 7 was superior in denseness to the fluorescent film using the red light emitting phosphor of Comparative Example 3. When the transmittance of the phosphor film was measured, the average transmittance of the phosphor film according to Comparative Example 3 was calculated.
Assuming 100, the average transmittance of the phosphor film according to Example 7 is 90
And it was confirmed that the compactness was improved.

Further, the emission luminance of each phosphor film was measured. As a result, the phosphor film of Example 7 was monochromatic red and obtained 10% higher luminance than the phosphor film of Comparative Example 3. It was also confirmed that the white luminance was improved by 5%. By using the large particle type red light emitting phosphor of the present invention, the emission luminance of the phosphor film can be improved. This greatly contributes to higher contrast and higher quality of the color cathode ray tube.

[0068]

As described above, according to the red light emitting phosphor for a cathode ray tube of the present invention, the denseness of the phosphor film using the same can be greatly improved. Therefore, the cathode ray tube of the present invention having such a fluorescent film is excellent in light emission luminance and can realize high contrast.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic structure of a color cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a diagram showing a particle size distribution of a red light-emitting phosphor (medium particle type) according to Example 1 of the present invention in comparison with a conventional medium-particle red light-emitting phosphor (Comparative Examples 1 and 2).

FIG. 3 is a diagram showing the transmittance of a phosphor film formed using a red light-emitting phosphor (medium particle type) according to Example 1 of the present invention.

FIG. 4 is a diagram showing the transmittance of a phosphor film formed using a conventional medium particle type red light-emitting phosphor (Comparative Example 1).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Panel part 2 ... Fluorescent film 4 ... Funnel part 5 ... Neck part 6 ... Electron gun

Continued on the front page (72) Inventor Satoshi Kanno 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Yokohama Office (72) Inventor Hiroyasu Yashima 7-1 Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa Toshiba Electronics Engineering Co., Ltd. (72) Inventor Yohei Shimizu 7-1, Nisshin-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Electronic Engineering Co., Ltd. (72) Inventor Go Koyanatsu 1-9-2 Hara-cho, Fukaya-shi, Saitama Prefecture Co., Ltd. Inside Toshiba Fukaya Plant (72) Inventor Kei Mikami 1-9-2 Hara-cho, Fukaya City, Saitama Prefecture Inside Toshiba Fukaya Plant

Claims (20)

[Claims] 1. A red light-emitting phosphor for a cathode ray tube, comprising a phosphor powder containing yttrium oxysulfide as a base, wherein the phosphor powder contains 15% or less of a component having a particle size of less than 4.0 μm, 75% or more of components from 4.0 μm to less than 8.0 μm,
A red light-emitting phosphor for a cathode ray tube, wherein a component having a particle size of 8.0 μm or more has a particle size distribution of 10% or less. 2. The red light-emitting phosphor for a cathode ray tube according to claim 1, wherein the phosphor powder has a 50% D value of 5.0 μm or more and 6.5 μm or less. 3. The cathode ray tube according to claim 1, wherein the phosphor powder contains the component having a particle size of less than 4.0 μm in a range of 10% or less. Red light emitting phosphor for tubes. 4. The red light emitting phosphor for a cathode ray tube according to claim 1, wherein the phosphor powder contains the component having a particle size of 4.0 μm or more and less than 8.0 μm in a range of 82% or more. Red light emitting phosphor for a cathode ray tube. 5. The red light emitting phosphor for a cathode ray tube according to claim 1, wherein the phosphor powder contains the component having a particle size of 8.0 μm or more in a range of 8% or less. Red light emitting phosphor for tubes. 6. The cathode ray tube according to claim 1, wherein said red light emitting phosphor is made of a Y ₂ O ₂ S: Eu phosphor. Red light emitting phosphor for tubes. 7. A red light-emitting phosphor for a cathode ray tube comprising a phosphor powder containing yttrium oxysulfide as a base, wherein the phosphor powder contains 20% or less of a component having a particle size of less than 5.04 μm and a particle size of 20% or less. A red-light-emitting phosphor for a cathode ray tube, wherein a component having a particle size of 5.04 μm or more and less than 10.079 μm has a particle size distribution of 70% or more, and a component having a particle size of 10.079 μm or more has a particle size distribution of 10% or less. 8. The red light emitting phosphor for a cathode ray tube according to claim 7, wherein the phosphor powder has a 50% D value of 6.5 μm or more and 8.0 μm or less. 9. The red light emitting phosphor for a cathode ray tube according to claim 7, wherein the phosphor powder contains the component having a particle size of less than 5.04 μm in a range of 15% or less. Red light emitting phosphor for tubes. 10. The red light emitting phosphor for a cathode ray tube according to claim 7, wherein the phosphor powder contains the component having a particle size of 5.04 μm or more and less than 10.079 μm in a range of 75% or more. Red light emitting phosphor for a cathode ray tube. 11. The red light emitting phosphor for a cathode ray tube according to claim 7, wherein the phosphor powder contains the component having a particle size of 10.079 μm or more in a range of 8% or less. Red light emitting phosphor for tubes. 12. The red light-emitting phosphor for a cathode ray tube according to claim 7, wherein the red light-emitting phosphor is made of a Y ₂ O ₂ S: Eu phosphor. Red light emitting phosphor for tubes. 13. A panel constituting an envelope; a phosphor film formed on an inner surface of the panel, the phosphor film including the red light emitting phosphor for a cathode ray tube according to claim 1; A cathode ray tube, comprising: an electron source for irradiating the phosphor film with an electron beam. 14. The cathode ray tube according to claim 13, wherein the phosphor film further includes a blue light emitting phosphor and a green light emitting phosphor. 15. The cathode ray tube according to claim 13, wherein the fluorescent film has a dot shape. 16. The cathode ray tube according to claim 13, wherein the cathode ray tube is used for a computer display. 17. A panel constituting an envelope, a phosphor film including a red light-emitting phosphor for a cathode ray tube according to claim 7, formed on an inner surface of the panel; An electron source for irradiating a fluorescent film with an electron beam. 18. The cathode ray tube according to claim 17, wherein the fluorescent film further includes a blue light emitting phosphor and a green light emitting phosphor. 19. The cathode ray tube according to claim 17, wherein the fluorescent film has a stripe shape. 20. The cathode ray tube according to claim 17, wherein the cathode ray tube is used for a color television.