JPH07188653A - Fluorescencer and colored cathode ray tube using the same - Google Patents

Abstract

PURPOSE:To obtain a green-emitting fluorescencer with improved current saturation characteristics. CONSTITUTION:A fluorescencer is represented virtually by the compsn. formula ZnS:Cua, Aub, Mc, Xd or ZnS:Cua, AubMc, Cee, Xd (wherein M indicates at least one element selected from Pr and Tb; X indicates at least one element selected from 3B-group elements and halogens; and 0<a<10<-3>, 0<b<10<-3>, 0<c<10<-1>. 0<d<10<-2>, and 0<e<10<-1>).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green light emitting phosphor having excellent current characteristics suitable for a color cathode ray tube and the like, and a color cathode ray tube using this phosphor.

[0002]

2. Description of the Related Art As the information-oriented society advances, color televisions are becoming highly functional as high-definition televisions and computer terminal displays. Even in the case of home color television, as a multimedia information terminal, there has been a great deal of progress in high performance such as large size, high contrast, and multi-functionality. Under such circumstances, the development and practical use of color televisions have been promoted in the direction of emphasizing the color reproduction range and the importance of white balance.

For example, as the green light emitting phosphor used in the former case, a copper and gold activated zinc sulfide phosphor (ZnS: Cu, Al) having a high y value of CIE chromaticity is used. On the other hand, copper, gold and aluminum activated zinc sulfide phosphors (ZnS: Cu, Au, Al) are used as the green light emitting phosphors that emphasize white balance. In order to adjust the white balance, the more uniform the cathode current distribution among the three electron guns is, the better. Therefore, a phosphor having a large x value of CIE chromaticity is used as the green component.

It goes without saying that, in addition to these value-added characteristics, the luminance characteristics of the color television are emphasized. The recent increase in the screen size and the increase in contrast have a disadvantageous effect on the luminance characteristics of color televisions. That is, as the screen size increases, the irradiation electron dose per single area decreases, and the high contrast also absorbs effective light emission.
For this reason, in a large-sized CRT, a method of compensating for such a decrease in brightness is adopted by increasing the acceleration voltage and the irradiation electron dose.

[0005]

By the way, as is well known, the relationship between the irradiation electron dose and the emission intensity of the phosphor is preferably a linear relationship. That is, it is a desirable property to obtain the emission intensity proportional to the electron dose applied to the phosphor. However, even if the phosphor has a proportional relationship at a low electron dose, it causes a so-called current saturation phenomenon at a high electron dose. Such a current saturation phenomenon is caused by the zinc sulfide phosphor, especially ZnS:
It is known that it appears remarkably in Cu, Au, and Al green light emitting phosphors. When a phosphor having a poor current saturation characteristic is used, not only the expected brightness cannot be obtained even if the irradiation electron dose is increased, but also the white balance is greatly adversely affected.

For example, when adjusting the cathode currents of green, blue, and red in order to display a white screen having a certain color temperature, the closer the current ratio is to 1.0, that is, the cathode current with which each phosphor is irradiated. Is preferably uniform. For this reason, ZnS:
In a color television using Ag and Y ₂ O ₂ S: Eu as a red light emitting component, ZnS: Cu, Au,
Al phosphors have been used as the green emission component. Particularly, for practical reasons, the cathode current ratio of red and green is emphasized. However, conventional ZnS: Cu, A
Since the u and Al phosphors have significant current saturation in the high current region as described above, a color television using such a phosphor has a high brightness white even if white adjustment is performed with a certain cathode current. When is displayed, the cathode current ratio will deviate from the initial setting. For this reason, in the conventional color television as described above, the correction by the internal circuit is necessary.

With the recent trend toward larger screens, higher quality, higher resolution, etc., the irradiation current of a color television is
Since there is a tendency to increase more and more, the emergence of green-emitting phosphors with improved current saturation characteristics is strongly desired.

The present invention has been made in order to solve the above problems, and it is a green light emitting phosphor having improved current saturation characteristics, and a green light emitting fluorescent light having improved luminous efficiency while satisfying the above conditions. The purpose is to provide the body,
Another object of the present invention is to provide a color cathode ray tube which is excellent in luminance characteristics and excellent in white balance from a low luminance side to a high luminance side by using such a phosphor.

[0009]

Means for Solving the Problems As a result of various studies conducted by the present inventors to achieve the above-mentioned object,
S: Cu, Au based on at least one selected from the elements belonging to Group 3B of the Periodic Table and halogen elements.
The composition ratio of the co-activator containing Cu and at least one element selected from Pr and Tb as the co-activator is further added to the system in which one kind of element is added as the co-activator. It was found that the current saturation characteristic is improved when the range is selected and set. Further, they have found that by adding at least one element selected from Pr and Tb in addition to a proper amount of Ce as a co-activator, the current saturation characteristics can be improved and the luminous efficiency can be increased. .

The present invention has been made on the basis of the above-mentioned findings. The first phosphor of the present invention has a composition formula of ZnS: Cu _a , Au _b , M _c , X _d. (Wherein M is at least 1 selected from Pr and Tb)
X represents at least one element selected from 3B group elements and halogen elements in the periodic table, and a, b,
c and d are 0 <a <10 ^-3 , 0 <b <10 ^-3 , 0 respectively
<C <10 ⁻¹ , 0 <d <10 ⁻² is shown as a numerical value).

Further, the second phosphor has a composition formula of ZnS: Cu _a , Au _b , M _c , Ce _e , X _d (2) (wherein M is at least 1 selected from Pr and Tb).
X represents at least one element selected from 3B group elements and halogen elements in the periodic table, and a, b,
c, d and e are 0 <a <10 ^-3 and 0 <b <1 respectively
^{0 -3, 0 <c <10} -1, is ^{0 <d <10 -2, 0} < , wherein substantially represented that by e <10 shows the values that satisfy ^-1).

Further, the color cathode ray tube of the present invention comprises a green light-emitting phosphor, a red light-emitting phosphor made of Eu-activated rare earth oxysulfide, and a blue-light-emitting phosphor made of Ag-activated zinc sulfide. In the color cathode ray tube provided as a surface, as the green light emitting phosphor, the above (1) formula or (2)
It is characterized by using a phosphor whose composition is substantially represented by the formula.

In the green-emitting phosphor according to the present invention,
The X element in the composition formulas represented by the above formulas (1) and (2) is an element that forms a so-called donor level in the ZnS crystal, and includes, for example, halogen elements such as F, Cl, Br, and I,
Elements of Group 3B of the periodic table such as Al, Ga and In are used. These can be used in combination.

In the above composition formula, the value of a representing the activation amount of Cu, the value of b representing the activation amount of Au, and the value of d representing the amount of X element are 0 <a <10, respectively. ^-3 , 0 <b
It shall be selected from the range of <10 ⁻³ , 0 <d <10 ⁻² . Furthermore, the ratio a / d between the value of a and the value of d is set to 1/1 to 1/5.
It is desirable to select the degree. By satisfying the above-mentioned ranges of the amounts of Cu, Au and X activating components, high brightness can be achieved and E as a red light emitting component can be achieved.
When the u-activated rare earth oxysulfide phosphor and the Ag-activated zinc sulfide phosphor as the blue light emitting component are used, the cathode current can be made uniform when displaying a white screen.

In the phosphor of the present invention, at least one element selected from Pr and Tb is contained as a co-activator together with each of the above-mentioned activator components, and the function of Pr and Tb. As a result, the current saturation characteristic can be improved. The value of c representing the amount of Pr or Tb is selected from the range of 0 <c <10 ^-1 . If the value of c exceeds 10 ^-1 , the brightness will decrease.
^-1 or less.

In the phosphor of the present invention, the above P
It is preferable to contain an appropriate amount of Ce as a coactivator together with r and Tb. Thus, by including Ce as a co-activator, the current saturation characteristics are improved, and
It is possible to increase the luminous efficiency. The value of e representing the amount of Ce is selected from the range of 0 <e <10 ^-1 . On the contrary, when the value of e exceeds 10 ^-1 , the brightness is lowered.

The phosphor of the present invention can be obtained, for example, by the usual manufacturing method as shown below. That is, a zinc compound such as copper sulfate and an Au such as chloroauric acid are added to zinc sulfide powder.
Compounds, compounds containing Pr or Tb such as praseodymium oxide and terbium oxide, compounds containing X element such as aluminum nitrate, and Ce such as cerium oxide
Is added at a predetermined composition ratio, and if necessary, an aqueous solution of a halide of an alkali metal, an alkaline earth metal, ammonium, or the like as a crystal growth auxiliary is added, and the mixture is thoroughly mixed and dried. Then, the above mixture is placed in a quartz crucible or the like and placed in a neutral or reducing atmosphere.
Bake at a temperature of 900-1050 ° C. Thereafter, the phosphor represented by ZnS: Cu, Au, M, (Ce), X of the present invention is obtained by passing through ordinary post-treatment steps such as dispersion treatment and washing treatment.

The activator element Pr may be replaced by praseodymium oxide and replaced with praseodymium compounds such as praseodymium oxalate, praseodymium chloride and praseodymium nitrate.
Further, Tb is replaced with terbium oxide, for example, a terbium compound such as terbium iodide, terbium chloride, and terbium nitrate, and Ce is replaced with cerium oxide.
For example, it can be added as a cerium compound such as cerium oxalate, cerium chloride, and cerium nitrate. further,
The activator may be added by any method such as a so-called wet method or dry method.

In the color cathode ray tube of the present invention, the phosphor of the present invention as described above is used as a green light emitting component, an Eu-activated rare earth oxysulfide phosphor is used as a red light emitting component, and Ag is used as a blue light emitting component. The phosphor has a phosphor screen using an activated zinc sulfide phosphor, and each phosphor is coated with a slurry in which each phosphor is dispersed together with PVA, a surfactant, pure water, etc. by a usual manufacturing method. It is obtained by

[0020]

The phosphor of the present invention exhibits excellent current saturation characteristics and emission brightness. Here, the results of measuring the γ value as an index of the current saturation characteristic of the phosphor of the present invention are shown in Table 1 and Table 2.
Shown in. The γ value is a value obtained as a gradient of the relationship between the emission current and the emission luminance as a logarithmic relationship. If the γ value is 1.0, it means that the emission brightness proportional to the applied current is obtained, and if it is less than 1.0, the current is saturated.

Table 1 shows that Cu concentration is 1.5 with respect to ZnS 1g.
× 10 ^-4 g, Au concentration 1.5 × 10 ^-4 g, Al concentration 1.5 × 10 ^-4
In a system fixed to g, the γ value and relative emission brightness of various phosphors prepared by changing the Pr content concentration, and Table 2 show the γ values of various phosphors prepared by changing the Tb content concentration. The values and the relative emission brightness are shown. The emission brightness was measured by irradiating a monochromatic fluorescent screen with an electron beam having a raster size of 8 × 8 cm ² .

[Table 1]

[Table 2] As is clear from Tables 1 and 2, it can be seen that the addition of Pr or Tb improves the γ value, that is, the current saturation characteristic. However, if Pr or Tb is added in a too large amount, the luminous efficiency will decrease. Therefore, the concentration (as c value) of Pr or Tb added to ZnS: Cu, Au, X (Al) is set to 1 × 10 ^-1 or less.

FIG. 1 shows that for ZnS 1g, the Cu concentration is 1.5 × 10 ⁻⁴ g, the Au concentration is 1.5 × 10 ⁻⁴ g, and the Al concentration is
Current of the phosphor according to the present invention (Phosphor A) obtained by adding 1.0 × 10 ⁻³ g of Pr to the phosphor of 1.5 × 10 ⁻⁴ g and the conventional phosphor (Phosphor B) not containing Pr. -Shows emission luminance characteristics. As is clear from FIG. 1, by coexisting Pr as a co-activating component, the current saturation characteristic is improved, and even when the electron beam is irradiated with a high current to obtain high brightness, the relative intensity of the emission brightness is changed. It can be significantly increased to 4-6% or more. Similar results are obtained when Tb is added instead of Pr.

Further, in FIG. 2, with respect to ZnS 1g, the Cu concentration is 1.5 × 10 ⁻⁴ g, the Au concentration is 1.5 × 10 ⁻⁴ g, the Tb concentration is 1.0 × 10 ⁻³ g, and the Al concentration is 1.5 × 10 ^−. the phosphor was ⁴ g, Ce to 1.0 × 10 ^-3 g added with phosphor (phosphor C)
Shows the current-luminance luminance characteristics of a phosphor that does not contain Ce (phosphor D). As is clear from FIG. 2, the improvement of luminous efficiency is recognized by coexisting Ce as a co-activating component. Further, this effect is maintained even when the electron beam is irradiated with a high current in order to obtain high brightness. Similar results are obtained in a system in which Pr is added instead of Tb. In addition, the Cu concentration is set to ZnS 1g.
1.5 × 10 ^-4 g, Au concentration 1.5 × 10 ^-4 g, Tb concentration 1.
Ce was added to a system with 0 × 10 ^-3 g and Al concentration of 1.5 × 10 ^-4 g.
FIG. 3 shows the results of measuring the emission brightness of the phosphors prepared by changing the content concentration of. As is clear from FIG.
The luminous efficiency increases with the addition of e, but when Ce is added in a too large amount, the luminous efficiency decreases conversely. Therefore, the concentration of Ce added to ZnS: Cu, Au, M (Tb), and X (Al) (as an e value) is 1 × 10 ⁻¹ or less.

The color cathode ray tube using the above-mentioned phosphor as a green light emitting component is excellent in current saturation characteristics as compared with the color cathode ray tube using the conventional phosphor, so that the white balance can be improved. Becomes

[0025]

EXAMPLES Examples of the present invention will be described below.

Example 1 Per 1 g of zinc sulfide powder (ZnS), copper sulfate (CuSO 4
_{4 · 5H 2 O) 5.90 ×} 10 -4 g, chloroauric acid ((HAuCl
₄ ) ・ 4H ₂ O) 3.14 × 10 ^-4 g, praseodymium oxide (P
r ₆ O ₁₁ ) 1.22 × 10 ⁻³ g, aluminum nitrate (Al (N
_{O 3) 3 · 9H 2 O} ) 2.78 × 10 -3 g, and potassium iodide (KI) 1.0 × 10 ^-3 g was added, after mixing with the slurry and dried. Next, the dried mixture was placed in a quartz crucible and baked in a reducing atmosphere of hydrogen sulfide at a temperature of 980 ° C. for 100 minutes to produce a green-emitting zinc sulfide-based phosphor.

The luminescent material thus obtained had a γ value of 0.94 when it was made to emit light by electron beam excitation. On the other hand, as a comparison with the present invention, a zinc sulfide-based phosphor was produced in the same manner as in the above-mentioned example except that Pr was not added, and the γ value of the phosphor of this comparative example was 0.89. Also,
The emission brightness at a current density of 60 μA / cm ² was 107% for the green-emitting phosphor according to the example when the emission brightness for the comparative example was 100%.

Further, europium-activated yttrium oxysulfide phosphor as a red-emitting phosphor, silver-activated zinc sulfide phosphor as a blue-emitting phosphor, and each zinc sulfide-based phosphor according to the above Examples and Comparative Examples as a green-emitting phosphor. Each body was used to form a phosphor screen by an ordinary slurry coating method, and a color cathode ray tube was constructed. Regarding the phosphor screen of these color cathode ray tubes, when white is displayed with an electron beam having an excitation voltage of 25 kV and a cathode current of 1 mA, the cathode current ratio of red and green is the color cathode ray tube using the green light emitting phosphor of the above example. , A good value of 0.99 was obtained, whereas the color cathode ray tube using that of the above comparative example was 1.13.
Met.

Example 2 In the above Example 1, 1.9% praseodymium oxalate was replaced with praseodymium oxalate (Pr ₂ (C ₂ O ₄ ) ₃ · 10H ₂ O).
A green-emitting zinc sulfide-based phosphor was prepared under the same conditions as in Example 1 except that 4 × 10 ⁻³ g was added. This green light emitting phosphor had a γ value of 0.92 when emitted by electron beam excitation, and the green light emitting phosphor to which praseodymium was not added as a comparative example had a γ value of 0.89. Also, the current density is 50μ
The emission luminance at A / cm ² was 105% of that of the comparative example.

Example 3 8.02 × 10 ^-4 g of copper sulfate, 5.33 × 10 ^-4 g of chloroauric acid, 6.10 × 10 ^-4 g of praseodymium oxide and 4.20 × of ammonium chloride (NH ₄ Cl) per 1 g of zinc sulfide powder. 10 ⁻³ g and 1.0 × 10 ⁻³ g of potassium iodide were added to form a slurry and mixed, and then dried. Next, the dried mixture was placed in a quartz crucible and baked in a reducing atmosphere of hydrogen sulfide at a temperature of 980 ° C. for 100 minutes to produce a green-emitting zinc sulfide-based phosphor.

The green light emitting phosphor thus obtained had a γ value of 0.92 when it was made to emit light by electron beam excitation. On the other hand, as a comparative example, the γ value of the zinc sulfide-based phosphor produced in the same manner as in the above-mentioned example except that Pr was not added
It was 0.87. The emission brightness of the green light emitting phosphor of this example at a current density of 60 μA / cm ² was 107% of that of the phosphor of the comparative example.

Regarding the phosphor screen of each color cathode ray tube produced in the same manner as in Example 1, when white was displayed by an electron beam with an excitation voltage of 25 kV and a cathode current of 1 mA, the cathode current ratio of red and green was In the color cathode ray tube using the green light emitting phosphor of the example, a good value of 1.02 was obtained, while in the color cathode ray tube using that of the above comparative example.
It was 1.18.

Example 4 5.90 × 10 ^-4 g of copper sulfate, 5.33 × 10 ^-4 g of chloroauric acid, and praseodymium chloride (PrCl ₃ ) 2.65 per 1 g of zinc sulfide powder.
× 10 ^-3 g, sodium chloride (NaCl) 1.0 × 10 ^-3 g,
And 1.0 × 10 ⁻³ g of potassium iodide were added to form a slurry and mixed, and then dried. Next, the dried mixture was placed in a quartz crucible and baked in a reducing atmosphere of hydrogen sulfide at a temperature of 980 ° C. for 100 minutes to produce a green-emitting zinc sulfide-based phosphor.

The green light emitting phosphor thus obtained had a γ value of 0.91 when it was made to emit light by electron beam excitation. On the other hand, as a comparative example, the γ value of the zinc sulfide-based phosphor produced in the same manner as in the above-mentioned example except that Pr was not added
It was 0.87. The emission brightness of the green light emitting phosphor of this example at a current density of 60 μA / cm ² was 105% of that of the phosphor of the comparative example.

Regarding the phosphor screen of each color cathode ray tube produced in the same manner as in Example 1, when white was displayed with an electron beam having an excitation voltage of 25 kV and a cathode current of 1 mA, the cathode current ratio between red and green was as described above. In the color cathode ray tube using the green light emitting phosphor of the example, a good value of 1.04 was obtained, while in the color cathode ray tube using that of the above comparative example.
It was 1.19.

Example 5 5.90 × 10 ⁻⁴ g of copper sulfate, 3.14 × 10 ⁻⁴ g of chloroauric acid, and 1.22 × terbium oxide (Tb ₄ O ₇ ) per 1 g of zinc sulfide powder.
10 ⁻³ g, aluminum nitrate 2.78 × 10 ⁻³ g, and potassium iodide 1.0 × 10 ⁻³ g were added, and the mixture was slurried and mixed, and then dried. Then, the mixture after drying was placed in a quartz crucible, and in a reducing atmosphere with hydrogen sulfide,
By firing at a temperature of 980 ° C for 100 minutes, a green-emitting zinc sulfide-based phosphor was prepared.

The thus obtained phosphor had a γ value of 0.94 when emitted by electron beam excitation. On the other hand, as a comparative example, the γ value of the zinc sulfide-based phosphor produced in the same manner as in the above-described example except that Tb was not added was 0.89. Also, the current density of the green-emitting phosphor according to this example
The emission luminance at 60 μA / cm ² was 107% of that of the phosphor of Comparative Example.

Regarding the phosphor screen of each color cathode ray tube produced in the same manner as in Example 1, when white was displayed with an electron beam having an excitation voltage of 25 kV and a cathode current of 1 mA, the cathode current ratio of red and green was In the color cathode ray tube using the green light emitting phosphor of the example, a good value of 0.99 was obtained, whereas in the color cathode ray tube using it of the comparative example above.
It was 1.13.

Example 6 In the above Example 5, terbium oxalate (Tb ₂ (C ₂ O ₄ ) ₃ · 10H ₂ O) was added in place of terbium oxide (1.94 ×).
A green-emitting zinc sulfide-based phosphor was prepared under the same conditions as in Example 5, except that 10 ⁻³ g was added. This green-emitting phosphor has a γ value of 0.92 when it is made to emit light by electron beam excitation,
The γ value of the green light emitting phosphor to which Tb was not added as a comparative example was 0.89. Further, the emission luminance at a current density of 50 μA / cm ² was 105% with respect to the phosphor of Comparative Example.

Example 7 8.02 × 10 ⁻⁴ g of copper sulfate, 5.33 × 10 ⁻⁴ g of chloroauric acid, 6.10 × 10 ⁻⁴ g of terbium oxide, 4.20 × 10 ⁻³ g of ammonium chloride, per 1 g of zinc sulfide powder. And potassium iodide 1.0 ×
10 ⁻³ g was added, and the mixture was slurried and mixed, and then dried. Next, the dried mixture was placed in a quartz crucible and baked in a reducing atmosphere of hydrogen sulfide at a temperature of 980 ° C. for 100 minutes to produce a green-emitting zinc sulfide-based phosphor.

The green light emitting phosphor thus obtained had a γ value of 0.92 when it was made to emit light by electron beam excitation. On the other hand, as a comparative example, the γ value of the zinc sulfide-based phosphor produced in the same manner as in the above example except that Tb is not added is
It was 0.87. The emission brightness of the green light emitting phosphor of this example at a current density of 60 μA / cm ² was 107% of that of the phosphor of the comparative example.

Regarding the phosphor screen of each color cathode ray tube produced in the same manner as in Example 1, when white was displayed by an electron beam with an excitation voltage of 25 kV and a cathode current of 1 mA, the cathode current ratio of red and green was as described above. In the color cathode ray tube using the green light emitting phosphor of the example, a good value of 1.02 was obtained, while in the color cathode ray tube using that of the above comparative example.
It was 1.18.

Example 8 Per 1 g of zinc sulfide powder, 5.90 × 10 ⁻⁴ g of copper sulfate, 3.14 × 10 ⁻⁴ g of chloroauric acid, 1.22 × 10 ⁻³ g of terbium oxide and 2.25 × 10 of cerium oxide (CeO ₂ ). ^-3 , aluminum nitrate 2.78
× 10 ^-3 g, and potassium iodide 1.0 × 10 ^-3 g was added,
The mixture was slurried and mixed, and then dried. Next, the dried mixture was placed in a quartz crucible and baked in a reducing atmosphere of hydrogen sulfide at a temperature of 980 ° C. for 100 minutes to produce a green-emitting zinc sulfide-based phosphor.

The thus obtained phosphor had a γ value of 0.94 when emitted by electron beam excitation. In addition, the emission luminance at a current density of 20 μA / cm ² was compared with a zinc sulfide-based phosphor (γ value: 0.94) to which Ce was not added.
When the emission brightness of the phosphor to which Ce was not added was 100%, the green emission phosphor according to the example was 107%.

Further, europium-activated yttrium oxysulfide phosphor was used as the red-emitting phosphor, silver-activated zinc sulfide phosphor was used as the blue-emitting phosphor, and each zinc sulfide-based phosphor was used as the green-emitting phosphor. Then, a phosphor screen was formed by a usual slurry coating method to form a color cathode ray tube. Regarding the phosphor screen of this color cathode ray tube, when white was displayed by an electron beam with an excitation voltage of 25 kV and a cathode current of 1 mA, a good red-green cathode current ratio was obtained.

Example 9 In Example 8, 3.43 × 10 ⁻³ g of cerium oxalate (Ce (C ₂ O ₄ ) ₂ .3H ₂ O) was used in place of cerium oxide.
A green-emitting zinc sulfide-based phosphor was produced under the same conditions as in Example 8 except that the phosphor was added. This green-emitting phosphor had a γ value of 0.93 when it was made to emit light by electron beam excitation. Also,
Green light emitting phosphor with no Ce added and current density 20 μA /
A comparison of the luminescence brightness at cm ² was 105%.

Example 10 Per 1 g of zinc sulfide powder, 8.02 × 10 ⁻⁴ g of copper sulfate, 5.33 × 10 ⁻⁴ g of chloroauric acid, 2.05 × 10 ⁻³ g of terbium oxide, 6.10 × 10 ⁻⁴ g of cerium oxide, Ammonium chloride 4.20 x 10 ^-3 g,
And 1.0 × 10 ⁻³ g of potassium iodide were added to form a slurry and mixed, and then dried. Next, the dried mixture was placed in a quartz crucible and baked in a reducing atmosphere of hydrogen sulfide at a temperature of 980 ° C. for 100 minutes to produce a green-emitting zinc sulfide-based phosphor.

The green-emitting phosphor thus obtained had a γ value of 0.92 when it was made to emit light by electron beam excitation. Moreover, a zinc sulfide-based phosphor to which Ce is not added (γ value: 0.
92) was compared with the emission brightness at a current density of 20 μA / cm ² , the emission brightness of the green-emitting phosphor according to the example was 10
It was 7%.

Example 11 Copper sulphate 5.90 × 10 ^-4 g, chloroauric acid 5.33 × 10 ^-4 g, terbium oxide 2.65 × 10 ^-3 g, and cerium chloride (CeCl ₄ ) 1.88 × 10 5 per 1 g of zinc sulfide powder. ^-3 g, sodium chloride
1.0 × 10 ^-3 g, and potassium iodide 1.0 × 10 ^-3 g was added, after mixing with the slurry and dried. Next, the dried mixture was placed in a quartz crucible and baked in a reducing atmosphere of hydrogen sulfide at a temperature of 980 ° C. for 100 minutes to produce a green-emitting zinc sulfide-based phosphor.

The green-emitting phosphor thus obtained had a γ value of 0.92 when emitted by electron beam excitation. Moreover, a zinc sulfide-based phosphor to which Ce is not added (γ value: 0.
92) was compared with the emission brightness at a current density of 60 μA / cm ² , the emission brightness of the green-emitting phosphor according to the example was 10
It was 5%.

[0051]

As described above, the green light emitting phosphor of the present invention is excellent in both emission brightness and current saturation characteristics, and can obtain a good γ value even in a high current region. Therefore, by using such a green light emitting phosphor, it is possible to provide a color cathode ray tube having high brightness characteristics and excellent white balance.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an irradiation electron dose and an emission brightness according to an example of a green light emitting phosphor of the present invention in comparison with a conventional example.

FIG. 2 is a diagram showing a relationship between an irradiation electron dose and a light emission brightness of a system to which Ce is added and a system to which Ce is not added.

FIG. 3 is a diagram showing a relationship between Ce content and emission luminance according to an example of the green light emitting phosphor of the present invention.

Continued Front Page (72) Inventor Hiromi Morikawa, 7-1, Nisshin-cho, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Toshiba Electronic Engineering Co., Ltd.

Claims (3)

[Claims] 1. A composition formula of ZnS: Cu _a , Au _b , M _c , X _d (wherein M is at least 1 selected from Pr and Tb).
X represents at least one element selected from 3B group elements and halogen elements in the periodic table, and a, b,
c and d are 0 <a <10 ^-3 , 0 <b <10 ^-3 , 0 respectively
<C <10 ⁻¹ , 0 <d <10 ⁻² is shown), and the phosphor is substantially represented. 2. The composition formula is ZnS: Cu _a , Au _b , M _c , Ce _e , X _d (wherein M is at least 1 selected from Pr and Tb).
X represents at least one element selected from 3B group elements and halogen elements in the periodic table, and a, b,
c, d and e are 0 <a <10 ^-3 and 0 <b <1 respectively
^{0 -3, 0 <c <10} -1, 0 <d <10 -2, 0 < phosphor, wherein the substantially represented by e <10 shows the values that satisfy ^-1). 3. A color cathode ray tube comprising a coating film of a green light emitting phosphor, a red light emitting phosphor composed of Eu-activated rare earth oxysulfide, and a blue light emitting phosphor composed of Ag-activated zinc sulfide as a phosphor screen. A color cathode ray tube using the phosphor according to claim 1 or 2 as the green-emitting phosphor.