JPS6350398B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to phosphors. More specifically, the present invention relates to a phosphor that exhibits a sublinear current density-emission brightness relationship as the current density of a stimulating electron beam increases.

Recently, multicolor cathode ray tubes have come into practical use as terminal display devices for computers, display devices for aircraft control systems, and the like. This multicolor cathode ray tube uses a phosphor that exhibits a superlinear excitation energy-emission brightness relationship as the energy of the stimulating electron beam increases, and a phosphor that exhibits a sublinear excitation energy-emission brightness relationship as the energy of the stimulating electron beam increases. This is a cathode ray tube that has a fluorescent film made up of two types of phosphors that emit light in different colors, and the color of the light emitted by the fluorescent film can be changed by changing the energy of the stimulating electron beam. By changing the color, a multicolor display can be performed.

The multicolor cathode ray tubes are classified into two types depending on the method of changing the energy of the stimulating electron beam. In other words, the energy of the stimulating electron beam is changed by changing the accelerating voltage, and the energy of the stimulating electron beam is changed by changing the current density. It is called a cathode ray tube, and the latter is called a current modulated multicolor cathode ray tube. For example, regarding voltage modulated multicolor cathode ray tubes, see pages 106-117 of the July 2, 1973 issue of Nikkei Electronics.
Regarding the current modulation type multicolor cathode ray tube, please refer to Japanese Patent Publication No. 52-5225.

Current-modulated multicolor cathode ray tubes have the advantage that the electron gun structure, electron gun control circuit, etc. are significantly simpler than voltage modulation multicolor cathode ray tubes. Despite this, most of the multicolor cathode ray tubes currently being put into practical use are voltage modulated multicolor cathode ray tubes. This is a phosphor suitable for use in current-modulated multicolor cathode ray tubes, that is, a phosphor that exhibits a sufficiently superlinear or sublinear current density-emission brightness relationship as the current density of the stimulating electron beam increases. This is because it is not well known.

Conventionally, copper- and aluminum-coated phosphors containing an appropriate amount of at least one metal selected from iron, cobalt, and nickel have been used as phosphors that exhibit a superlinear current density-emission brightness relationship when the current density of the stimulating electron beam increases. Activated zinc sulfide green-emitting phosphor (ZnS: Cu, Al) and silver-activated zinc sulfide cadmium green-blue to red-emitting phosphor containing an appropriate amount of at least one metal selected from iron, cobalt and nickel [ (Zn, Cd)S:Ag, as is well known, this phosphor emits green to red light in response to changes in the molar ratio of ZnS and CdS]. Additionally, a manganese-activated zinc silicate green-emitting phosphor (Zn ₂ SiO ₄ :Mn) is known as a phosphor that exhibits a sublinear current density-emission brightness relationship when the current density of the stimulating electron beam increases. .

In multi-color cathode ray tubes, in order to widen the range of display color change, generally (i) red-emitting phosphors exhibiting a super-linear excitation energy-emission brightness relationship and green-emitting phosphors exhibiting a sub-linear excitation energy-emission brightness relationship are used; or (ii) a combination of a green-blue or green-emitting phosphor that exhibits a superlinear excitation energy-emission brightness relationship and a color-emitting phosphor that exhibits a sublinear excitation energy-emission brightness relationship. The fluorescent film is composed of: From this point of view, current modulating multicolor cathode ray tubes use (Zn, Cd)S containing at least one metal among the above iron, cobalt, and nickel:
Ag red-emitting phosphor (showing a super-linear current density-emission brightness relationship) and the above Zn ₂ SiO ₄ :Mn
A combination with a green-emitting phosphor (which exhibits a sublinear current density-emission brightness relationship) is being considered; A green-emitting phosphor or a (Zn, Cd)S:Ag green-blue to green-emitting phosphor containing at least one metal selected from the above-mentioned iron, cobalt, and nickel (both superlinear current density-emission brightness) There has been no known red-emitting phosphor that exhibits a sublinear current density-emission brightness relationship that should be combined with the above relationship. Therefore, there is a strong need for a red-emitting phosphor that exhibits a sufficiently sublinear current density-emission brightness relationship as the current density of the stimulating electron beam increases.

The present invention was made under the above-mentioned circumstances, and provides a phosphor, in particular a red-emitting phosphor, which exhibits a sufficiently sublinear current density-emission brightness relationship when the current density of a stimulating electron beam increases. The purpose is to provide.

A europium-activated rare earth oxysulfide phosphor with the compositional formula (Ln, Eu) ₂ O ₂ S (Ln is at least one of yttrium, gadolinium, lanthanum, and ruthenium) is exposed to electron beam excitation. It is well known that it exhibits high-intensity yellow to red light emission in response to changes in the amount of Eu activation. For example, one of these phosphors,
A Y ₂ O ₂ S:Eu phosphor with a relatively large amount of Eu activation is currently in practical use as a phosphor for the red light emitting component of color television cathode ray tubes.

(Ln, Eu) ₂ O ₂ S phosphors are known to exhibit a slightly sublinear current density-emission brightness relationship as the current density of the stimulating electron beam increases, as illustrated in Figure 1. There is. Since the (Ln, Eu) ₂ O ₂ S phosphor emits light at a high luminance at a practical level, the present inventors developed the (Ln, Eu) ₂ O ₂ S phosphor in order to achieve the above object of the present invention. Various studies have been conducted to improve the sublinearity of the current density-emission brightness relationship exhibited by a light body. As a result, when cerium (Ce) is used in a specific range as a coactivator for Eu, the current density-emission brightness relationship exhibited by the (Ln, Eu) ₂ O ₂ S phosphor becomes sublinear. The present inventors have discovered that the sublinearity can be increased, and that the sublinearity can be significantly increased in a specific range of the Ce coactivation amount, leading to the completion of the present invention.

The phosphor of the present invention has a compositional formula of (Ln _1-xy , Eu _x , Ce _y ) ₂ O ₂ S (Ln is at least one of yttrium, gadolinium, lanthanum, and lutetium, and x and y are respectively 10 ^-4 ≦x≦9×10 ^-2
and 10 ^-6 ≦y≦2×10 ^-3 ). When the current density of the stimulating electron beam increases, this phosphor (Ln,
Eu) ₂ O ₂ S phosphor shows a current density-emission luminance relationship with higher sublinearity than that of the phosphor, especially when the Ce coactivation y value is in the range of 2×10 ^-6 ≦y≦10 ^-3 The phosphor in the figure shows a current density-emission brightness relationship with extremely high sublinearity.

Japanese Patent Publication No. 47-3321 and Japanese Patent Publication No. 47-3322 have the composition formula M′ _(2-x) M″ _x O ₂ S (where M′ is yttrium, gadolinium, or lanthanum, and M″ is at least one lanthanide element. A lanthanide element-activated rare earth oxysulfide phosphor is disclosed, where x is a number satisfying the condition 0.0002<x<0.2. A portion of the phosphor of the present invention is included in this lanthanide element-activated rare earth oxysulfide phosphor. However, the above-mentioned publication does not describe any phosphor using Eu as an activator and Ce as a co-activator, and even more
There is no suggestion that phosphors using specific ranges of amounts of Ce and Ce as activators and coactivators, respectively, exhibit a sublinear current density-emission brightness relationship as the current density of the stimulating electron beam increases. .

The phosphor of the present invention is manufactured by the manufacturing method described below.

First, as raw materials for the phosphor, (i) a first material consisting of yttrium oxide (Y ₂ O ₃ ), gadolinium oxide (Gd ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), and lutetium oxide (Lu ₂ O ₃ ); Compounds such as nitrates, sulfates, carbonates, oxalates, hydroxides, etc. are easily converted into Y ₂ O ₃ , Gd ₂ O ₃ ,
at least one compound selected from the second compound group consisting of yttrium compounds, gadolinium compounds, lanthanum compounds, and ruthenium compounds that can be converted into La ₂ O ₃ and Lu ₂ O ₃ ; (ii) europium oxide ( _Eu2O3 ) and _nitrates ,
at least one compound selected from the group consisting of europium compounds that can be easily converted to Eu ₂ O ₃ at high temperatures, such as sulfates, carbonates, oxalates, and hydroxides; (iii) cerium oxide (CeO ₂ ); and at least one compound selected from the group consisting of cerium compounds that can be easily converted into oxides at high temperatures such as nitrates, sulfates, carbonates, oxalates, and hydroxides, (iv) sulfur (S), and ( v) Fluxing agents such as alkali metal salts commonly used in the manufacture of oxysulfide phosphors such as sodium carbonate (Na ₂ CO ₃ ), potassium phosphate (K ₃ PO ₄ ), etc. are used. The above (i) and (iv) are the base raw materials, the above (ii) is the Eu activator raw material, and the above (iii) is the Ce
It is a co-activator raw material. The above (i), (ii) and (iii) have the stoichiometric compositional formula (Ln _1-xy , Eu _x , Ce _y ) ₂ O ₂ S (where Ln is one of yttrium, gadolinium, lanthanum and ruthenium). at least one of
species, and x and y are each 10 ^-4 ≦x≦9
x10 ^-2 and 10 ^-6 ≦y≦2×10 ^-3 ). The above (iv) is 30 to 60% of the above mixed oxide.
(v) is used in an amount corresponding to 5 to 50% by weight of the mixed oxide. The required amount of each phosphor raw material is weighed and thoroughly mixed to obtain a phosphor raw material mixture.

Next, the obtained phosphor raw material mixture is filled into a heat-resistant container such as an alumina crucible or a quartz crucible, and fired. Firing takes place in air at temperatures of 900 to 1500°C. The firing temperature varies depending on the amount of the phosphor raw material mixture filled in the heat-resistant container, the firing temperature used, etc., but is generally 0.5 to 5 hours.
After firing, the obtained fired product is washed and dried to obtain the phosphor of the present invention.

When the current density of the stimulating electron beam increases, the phosphor of the present invention exhibits a sublinear current density-emission brightness relationship. The sublinearity of the current density-emission brightness relationship exhibited by the phosphor of the present invention is the same for the amount of Eu activation (Ln, Eu) ₂ O ₂ S The current density exhibited by the phosphor -Higher than the sublinearity related to luminance.

FIG. 2 is a graph illustrating the current density-emission brightness relationship exhibited by the phosphor of the present invention,
(Y _0.94999 , Eu _0.05 , Ce _0.00001 ) This shows the current density-emission brightness relationship exhibited by the ₂ O ₂ S ₂ phosphor. In FIG. 2, the luminance on the vertical axis is expressed as a specific luminance, with the luminance of the (Y _0.95 , Eu _0.05 ) ₂ O ₂ S phosphor at each current density value taken as 100%.

The following can be understood from Figure 2. That is, since the (Y _0.95 , Eu _0.05 ) ₂ O ₂ S phosphor exhibits a slightly sublinear current density-emission brightness relationship as shown in Figure 1, it is clear that (Y _0.94999 , Eu _0.05 , Ce _0.00001 ) ₂ O ₂ S phosphor exhibits a sublinear current density-emission brightness relationship, and the sublinearity of the current density-emission brightness relationship is
This is higher than the sublinearity of the current density-emission brightness relationship exhibited by a ₂ O ₂ S phosphor with the same amount of Eu activation (Y _0.95 , Eu _0.05 ).

In the present invention, the sublinearity of the current density-emission brightness relationship exhibited by the phosphor is a function of the amount of Ce coactivation (y value). For example, the luminance of the (Y _0.95-y , Eu _0.05 , Ce _y ) ₂ O ₂ S phosphor when the current density of the stimulating electron beam is 0.1 μA/cm ² and 2.0 μA/ ^cm 2 is A ₁ , respectively. and B ₁ , the sublinearity of the current density-emission brightness relationship exhibited by this phosphor is expressed as B ₁ /A ₁ (of course
The smaller the value of B ₁ /A ₁ is, the higher the sublinearity is), and this sublinearity changes depending on the amount of Ce coactivation.

Figure 3 shows (Y _0.95-y , Eu _0.05 , Ce _y ) ₂ O ₂ S phosphor.
2 is a graph showing the relationship between the amount of Ce coactivation and the sublinearity of the current density-emission brightness relationship exhibited by this phosphor. Note that in FIG. 3, the vertical axis representing sublinearity is indicated by the value of B ₁ A ₂ /A ₁ B ₂ . Here, A ₂ and B ₂ each have the same Eu activation amount as (Y _0.95-y , Eu _0.05 , Ce _y ) ₂ O ₂ S phosphor (Y _0.95 , Eu _0.05 ) ₂ O ₂ S phosphor. This is the luminance at body current densities of 0.1 μA/cm ² and 2.0 μA/cm ² . The fact that the value of B ₁ A ₂ /A ₁ B ₂ is smaller than 1 means that (Y _0.95-y , Eu _0.05 , Ce _y ) ₂ O ₂ S phosphor has a relationship between current density and luminance. This means that the sublinearity (Y _0.95 , Eu _0.05 ) ₂ O ₂ S phosphor is higher than the sublinearity of the current density-emission brightness relationship, and conversely B ₁ A ₂ /A ₁ B ₂
A value greater than 1 means the opposite.

As is clear from Figure 3, (Y _0.95-y , Eu _0.05 ,
The sublinearity of the current density-emission brightness relationship exhibited by the Ce _y ) ₂ O ₂ S phosphor changes depending on the amount of Ce coactivation. Furthermore, as is clear from Fig. 3, the sublinearity of the current density-emission brightness relationship exhibited by the (Y _0.95-y , Eu _0.05 , Ce _y ) ₂ O ₂ S phosphor depends on the amount of Ce coactivation. When the y value is in the range of 10 ^-6 ≦ y ≦ 2 × 10 ^-3 (Y _0.95 , Eu _0.05 ) ₂ O ₂ S phosphor, the current density-emission brightness relationship is more sublinear. It gets expensive. In the present invention, the y value is
It is based on this knowledge that the range of 10 ^-6 ≦y≦2×10 ^-3 is specified. Especially when the y value is 2×10 ^-6
When it is in the range of ≦y≦10 ^-3 (Y _0.95-y , Eu _0.05 ,
Ce _y ) ₂ O ₂ S phosphors appear to exhibit a significantly high current density-emission brightness relationship with sublinearity.

Figure 4 shows (Y _0.95-y , Eu _0.05 , Ce _y ) ₂ O ₂ S phosphor.
It is a graph showing the relationship between the amount of Ce coactivation and the luminance of this phosphor. In Fig. 4, the vertical axis representing the luminance is the luminance of the phosphor where y=0, that is, the (Y _0.95 , Eu _0.05 ) ₂ O ₂ S phosphor, which is 100%.
It is expressed as a relative value. In addition, the luminance shown in Figure 4 depends on the current density of the stimulating electron beam.
The luminance is 0.5 μA/cm ² .

As is clear from FIG. 4, as the amount of Ce coactivation increases, the luminance gradually decreases. That is, Ce has only a negative effect on the luminance of the phosphor of the present invention. However, Ce
The phosphor of the present invention, which has a small coactivation amount y value, maintains sufficiently high luminance.

Note that Figures 2 to 4 show data when the rare earth element Ln constituting the matrix is Y, but Ln
is Gd, La or Lu, and Ln is Y,
Results similar to those shown in FIGS. 2 to 4 were obtained when two or more of Gd, La, and Lu were used.

In the present invention, the Eu activation amount (x value) is defined in the range of 10 ^-4 ≦x≦9×10 ^-2 from the viewpoint of luminance and the like. The phosphor of the present invention having an x value within the above range emits yellow to red light in response to changes in the x value.
In particular, a phosphor having an x value in the range of 10 ^-2 ≦x≦8×10 ^-2 emits red light with good color purity. Note that Eu has almost no effect on the sublinearity of the current density-emission brightness relationship exhibited by the phosphor.
Furthermore, Ce has almost no effect on the emission spectrum (emission color) of the phosphor. That is, the emission spectrum of the phosphor of the present invention is almost the same as that of the (Ln, Eu) ₂ O ₂ S phosphor having the same amount of Eu activation.

As described above, the present invention provides a phosphor that exhibits a sublinear current density-emission brightness relationship as the current density of a stimulating electron beam increases. Among the phosphors of the present invention, the Eu activation amount x value is particularly
A phosphor in the range of 10 ^-2 ≦ x ≦ 8 × 10 ^-2 emits red light with good color purity, and therefore ZnS containing at least one metal from the above iron, cobalt, nickel, and vanadium. : Cu, Al green-emitting phosphor or (Zn, Cd) S:Ag green-blue to green-emitting phosphor containing at least one metal from the above iron, cobalt, nickel, and vanadium (both super linear It is suitable for constructing a fluorescent film of a current modulation type multicolor cathode ray tube in combination with a current density-emission luminance relationship (showing a current density-emission brightness relationship). The phosphor of the present invention can also be used in electronic excitation display tubes other than the current modulated multicolor cathode ray tubes described above.

Next, the present invention will be explained with reference to Examples.

Example 1 Yttrium oxide Y ₂ O ₃ 214.5g Europium oxide Eu ₂ O ₃ 17.6g Cerium oxide CeO ₂ 0.0034g Sulfur S 120g Sodium carbonate Na ₂ CO ₃ 80g Potassium phosphate K ₃ PO ₄・3H ₂ O 20g Each of the above fireflies Thoroughly mix the photomaterial raw materials, fill the resulting mixture into an aluminium crucible, and heat it in air at 1200℃.
It was baked at a temperature of 2 hours. After firing, the obtained fired product was thoroughly washed with water and dried. In this way, a (Y _0.94999 , Eu _0.05 , Ce _0.00001 ) ₂ O ₂ S phosphor was obtained. When the current density of the stimulating electron beam increases, this phosphor exhibits a sublinear current density-emission brightness relationship, and as shown in Figure 3, the sublinearity of the current density-emission brightness relationship is (Y _0.95 ,
Eu _0.05 ) was higher than that of ₂ O ₂ S phosphor.

Example 2 Yttrium oxide Y ₂ O ₃ 219.0g Europium oxide Eu ₂ O ₃ 10.6g Cerium nitrate CeO (NO ₃ ) ₃・6H ₂ O 0.0087g Sulfur S 120g Sodium carbonate Na ₂ CO ₃ 80g Potassium phosphate K ₃ PO ₄ - 20 g of 3H ₂ O A (Y _0.96999 , Eu _0.03 , Ce _0.00001 ) ₂ O ₂ S phosphor was obtained in the same manner as in Example 1 using each of the above-mentioned phosphor raw materials.
When the current density of the stimulating electron beam increases, this phosphor exhibits a sublinear current density-emission brightness relationship, and the sublinearity of the current density-emission brightness relationship is (Y _0.97 , Eu _0.03 ) ₂ O ₂ S It was higher than the phosphor.

Example 3 Yttrium oxide Y ₂ O ₃ 158.0g Gadolinium oxide Gd ₂ O ₃ 79.8g Europium oxide Eu ₂ O ₃ 28.2g Cerium oxide CeO ₂ 0.034g Sulfur S 120g Sodium carbonate Na ₂ CO ₃ 80g Potassium phosphate K ₃ PO ₄ - 20 g of 3H ₂ O A (Y _0.6999 , Gd _0.22 , Eu _0.08 , Ce _0.00001 ) ₂ O ₂ S phosphor was obtained in the same manner as in Example 1 using each of the above-mentioned phosphor raw materials. When the current density of the stimulating electron beam increases, this phosphor exhibits a sublinear current density-emission brightness relationship, and the sublinearity of the current density-emission brightness relationship is (Y _0.7 , Gd _0.22 , Eu _0.08 ) _{2 O2S}
It was higher than the phosphor.

[Brief explanation of drawings]

FIG. 1 is a graph illustrating the very slightly sublinear current density-emission brightness relationship exhibited by the (Ln, Eu) ₂ O ₂ S phosphor. FIG. 2 is a graph illustrating the sublinear current density-emission brightness relationship exhibited by the phosphor of the present invention. FIG. 3 is a graph illustrating the relationship between the Ce coactivation amount of the phosphor of the present invention and the sublinearity of the current density-emission luminance relationship exhibited by this phosphor. FIG. 4 is a graph illustrating the relationship between the amount of Ce coactivation of the phosphor of the present invention and the luminance of this phosphor.

Claims (1)

[Claims] 1. Compositional formula (Ln _1-xy , Eu _x , Ce _y ) ₂ O ₂ S (Ln is at least one of yttrium, gadolinium, lanthanum, and lutetium, and x and y are each 10 ^-4 ≦x≦9×10 ^-2
and 10 ^-6 ≦y≦2×10 ^-3 ), and exhibits a sublinear current density-emission brightness relationship as the current density of a stimulating electron beam increases. 2 Claim 1, wherein the above y is a number satisfying the condition 2×10 ^-6 ≦y≦10 ^-3
Fluorescent substance described in Section 2. 3. Claim 1, wherein x is a number satisfying the condition 10 ^-2 ≦x≦8×10 ^-2
The phosphor according to item 1 or 2.