JPH0521159B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phosphor. 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.

[Prior Art] Recently, multicolor cathode ray tubes have come into practical use as end display devices for computers, display devices for aircraft control systems, and the like. This multicolor cathode ray tube consists of 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 phosphor film composed of two types of phosphors that emit light in different colors.The emitted light color of the phosphor film is changed by changing the energy of the stimulating electron beam. This system is designed to perform multicolor display.

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, please refer to pages 106-117 of the July 2, 1973 issue of "Nikkei Electronics" for voltage modulation type multicolor cathode ray tubes, and to Japanese Patent Publication No. 52-5225 for current modulation type multicolor cathode ray tubes.

Current modulated multicolor cathode ray tubes have the advantage that the structure of the electron gun, electron gun control circuit, etc. are significantly simpler than voltage modulated 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 indicates that there are few phosphors suitable for use in current-modulated multicolor cathode ray tubes, ie, phosphors that exhibit a sufficiently superlinear or sublinear current density-luminance relationship as the current density of the stimulating electron beam increases. This is because they have not been

Conventionally, copper and aluminum containing an appropriate amount of at least one metal selected from iron, cobalt, nickel, and vanadium 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 iron,
A silver-activated zinc sulfide cadmium blue-green to red-emitting phosphor [(Zn, Cd)S:Ag, as is well known, contains a suitable amount of at least one metal selected from cobalt, nickel, and vanadium.
It is known to emit blue-green to red light in response to changes in the molar ratio of ZnS and CdS. In addition, a manganese-activated zinc silicate green-emitting phosphor (Zn ₂ SiO ₄ :
Mn) is known.

In multicolor cathode ray tubes, in order to widen the range of display color change, a combination of a red-emitting phosphor that exhibits a superlinear excitation energy-emission brightness relationship and a green-emitting phosphor that exhibits a sublinear excitation energy-emission brightness relationship is generally used. or a combination of a blue-green to green-emitting phosphor exhibiting a super-linear excitation energy-emission brightness relationship and a red-emitting phosphor exhibiting a sub-linear excitation energy-emission brightness relationship, the phosphor film is constructed by Ru. From this point of view, current modulating multicolor cathode ray tubes contain at least one metal selected from the above-mentioned iron, cobalt, nitrite, and vanadium (Zn,
Cd) S:Ag red light-emitting phosphor (shows super-linear current density-emission brightness relationship) and the above
A combination of Zn ₂ SiO ₄ :Mn with a green-emitting phosphor (which exhibits a sublinear current density-emission brightness relationship) is being considered; Contains ZnS: Cu, Al green-emitting phosphor or at least one metal selected from the above iron, cobalt, nickel, and vanadium (Zn,
Cd) S:Ag When combined with a blue-green to green-emitting phosphor (all exhibiting a superlinear current density-emission brightness relationship), the current density becomes sufficiently sublinear as the current density of the stimulating electron beam increases. A red-emitting phosphor that exhibits a luminance relationship is strongly desired.

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

Compositional formula Ln ₂ O ₂ S: Eu (However, Ln is yttrium, gadolinium,
At least one of lanthanum and lutetium
It is well known that the europium-activated rare earth oxysulfide phosphor represented by the following species exhibits high-intensity yellow to red light emission in response to changes in the amount of Eu activation under electron beam excitation. For example, one of these phosphors,
Y ₂ O ₂ S:Eu phosphor, which has a relatively large amount of Eu activation, is currently in practical use as a red-emitting component phosphor for color television cathode ray tubes.

It is known that the Ln ₂ O ₂ S:Eu phosphor exhibits a very slightly sublinear current density-emission brightness relationship as the current density of the stimulating electron beam increases, as illustrated in FIG. It is also known that sublinearity increases when Ce is co-activated in Ln ₂ O ₂ S:Eu phosphor (Japanese Patent Laid-Open No. 17189/1989).

In order to achieve the above object of the present invention, the present inventors have conducted various studies to improve the sublinearity of the current density-emission brightness relationship exhibited by Ln ₂ O ₂ S:Eu,Ce phosphors. Ta. As a result, when using a specific range of calcium (Ca) together with cerium (Ce) as a coactivator for Eu,
Ln ₂ O ₂ S: It is possible to increase the sublinearity of the current density-emission luminance relationship exhibited by Eu, Ce phosphors, and also to increase the sublinearity in the co-activation amount range of Ce and Ca. It was discovered that the above-mentioned sublinearity was significantly increased, and a stable and good phosphor could be obtained, leading to the completion of the present invention.

[Means for Solving the Problems] The phosphor of the present invention has a composition formula of Ln ₂ O ₂ S: Eu _x Ce _y Ca _z (Ln is yttrium, gadolinium,
At least one of lanthanum and lutetium
species, and x, y, and z are each 2×
^{Europium , cerium and _} It is a calcium-activated rare earth oxysulfide phosphor. When the current density of the stimulating electron beam increases, this phosphor
Ln ₂ O ₂ S: Shows a current density-emission brightness relationship with higher sublinearity than Eu and Ce phosphors, and in particular, the y and z values of Ce and Ca coactivation are 4 × 10 ^-6, respectively. ≦y≦2×10 ^-3 and 1×10 ^-4
Phosphors in the range of ≦z≦3×10 ^-2 exhibit a significantly high current density-emission luminance relationship with sublinearity.

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

First, as raw materials for the phosphor, a first compound group 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 ), and nitrates, sulfates, carbonates, oxalates, hydroxides, etc. easily at high temperatures such as 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 lutetium compounds that can be converted into La ₂ O ₃ and Lu ₂ O 3 2 Europium oxide (Eu ₂ O ₃ ) and nitrate ,
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; 3. cerium oxide (CeO ₂ ) and nitrate; At least one compound selected from the group consisting of cerium compounds that can be easily converted into oxides at high temperatures, such as sulfates, carbonates, oxalates, and hydroxides; 4. Calcium oxide (CaO), carbonates, and hydroxides; At least one compound selected from the group consisting of calcium compounds that can be easily converted to CaO at high temperatures such as nitrates, nitrates, etc. 5. Sulfur 6. Sodium carbonate (Na ₂ CO ₃ ), potassium phosphate (K ₃ PO ₄ ), etc. A flux such as an alkali metal salt commonly used in the production of oxysulfide phosphors is used.

The above 1) and 5) are the base raw materials, the above 2) is the Eu activator raw material, and the above 3) is the Ce
This is a raw material for a co-activator, and 4) is a raw material for a Ca co-activator. The above 1), 2), 3), and 4) have the stoichiometric compositional formula Ln ₂ O ₃ :Eu _x Ce _y Ca _z (However, Ln is yttrium, gadolinium,
At least one of lanthanum and lutetium
species, and x, y, and z are each 2×
10 ^-4 ≦x≦0.18, 2×10 ^-6 ≦y≦4×10 ^-3 and 1×10 ^-5 ≦z≦6×10 ^-2 ) used in such proportions as obtained. The above 5) is 30 to 30% of the above mixed oxide.
It is used in an amount corresponding to 60%, and 6) is used in an amount corresponding to 5 to 50% by weight of the mixed oxide. Weigh out the required amount of each phosphor raw material and mix thoroughly 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 time 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 that the amount of Eu activation and the amount of co-activation of Ce are the same.
Ln ₂ O ₂ S: Higher than the sublinearity of the current density-emission brightness relationship exhibited by Eu and Ce phosphors.

FIG _. 1 is a graph illustrating the _current density _- emission brightness relationship exhibited by a _cathode ray tube manufactured using _the phosphor of the present invention. This shows the current density-emission brightness relationship expressed by . In Figure 1, the luminance on the vertical axis is the luminance of the Y ₂ O ₂ S:Eu _0.1 , Ce _0.00001 phosphor at each current density value.
It is expressed as specific luminance with 100%.

The following can be understood from Figure 1. In other words, since the Y ₂ O ₂ S: Eu _0.1 , Ce _0.00001 phosphor shows a sublinear current density-emission brightness relationship, it is clear that
Y ₂ O ₂ S: Eu _0.1 , Ce _0.00001 , Ca _0.001 phosphors exhibit a sublinear current density-emission brightness relationship, and the sublinearity of the current density-emission brightness relationship is
Eu activation amount and Ce coactivation amount are the same
Y ₂ O ₂ S: higher than the sublinearity of the current density-emission luminance relationship exhibited by the Eu _0.1 , Ce _0.00001 phosphor.

The sublinearity of the current density-emission brightness relationship exhibited by the phosphor of the present invention is a function of the amount of Ca coactivation. For example, if the current density of the stimulating electron beam is
_Y2O2S at 0.1μA/ ^cm2 and _2.0μA / ^cm2 :
If the luminance of the Eu _0.1 , Ce _0.00001 , and Ca _z phosphors is A ₁ and B ₁ , the sublinearity of the current density-emission luminance relationship exhibited by these phosphors is expressed as B ₁ /A ₁ (Of course, the smaller the value of B ₁ /A ₁ is, the higher the sublinearity is.) However, this sublinearity changes depending on the amount of Ca co-activation.

Figure 2 shows the Ca co-activation of Y ₂ O ₂ S:Eu _0.1 , Ce _0.00001 , Ca _z phosphor and the sub-current density-emission luminance relationship shown by a cathode ray tube manufactured using this phosphor. It is a graph showing the relationship with linearity. In FIG. 2, 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 are respectively Y ₂ O ₂ S: Eu _0.1 ,
At current densities of _0.1 μA/cm 2 and 2.0 μA/cm ² for Y ₂ O ₂ S: Eu _0.1 , Ce _0.00001 phosphor with the same Eu activation amount and Ce coactivation amount as the Ce 0.00001 , Ca _z phosphor ^, This is luminance. The fact that the value of B ₁ A ₂ /A ₁ B ₂ is smaller than 1 means that the sublinearity of the current density-emission luminance relationship exhibited by Y ₂ O ₂ S: Eu _0.1 , Ce _0.00001 , Ca _z phosphors is is higher than the sublinearity of the current density-emission brightness relationship exhibited by the Y ₂ O ₂ S: Eu _0.1 , Ce _0.00001 phosphor;
A value of B ₁ A ₂ /A ₁ B ₂ greater than 1 means the opposite.

As is clear from Figure 2, Y ₂ O ₂ S: Eu _0.1 ,
The sublinearity of the current density-emission brightness relationship exhibited by Ce _0.00001 and Ca _z phosphors changes depending on the amount of Ca coactivation. Furthermore, as is clear from Fig. 2, the sublinearity of the current density-emission brightness relationship exhibited by Y ₂ O ₂ S: Eu _0.1 , Ce _0.00001 , Ca _z phosphor depends on the Ca coactivation amount z value. 1×10 ^-5 ≦z≦
Y ₂ O ₂ S: Eu _0.1 when in the range of 6 × 10 ^-2 ,
This is higher than the sublinearity of the current density-emission brightness relationship exhibited by the Ce _0.00001 phosphor. This means that the Ce coactivation amount (y value) is 2×10 ^-6 ≦y≦
It is effective when it is in the range of 4×10 ^-3 . It is based on this knowledge that the y value and the z value are defined in the range of 2×10 ^-6 ≦y≦4×10 ^-3 and 1×10 ^-5 ≦z≦6×10 ^-2 in the present invention, respectively. It is. Especially when the y value is 4
×10 ^-6 ≦y≦2×10 ^-3 and z value is 1×10 ^-4 ≦z
Y ₂ O ₂ S: Eu _0.1 when it is in the range of ≦3 × 10 ^-2 ,
Ce _y and Ca _z phosphors have high sublinearity, and exhibit a current density-emission luminance relationship with significantly high sublinearity particularly in the range of 1×10 ⁻³ ≦z≦3×10 ⁻² .

Note that Figures 1 and 2 are data when the rare earth element Ln constituting the matrix is Y.
Results similar to those in FIGS. 1 and 2 were also obtained when Ln was Gd, La, or Lu, and when Ln was two or more of Y, Gd, La, and Lu.

In the present invention, the Eu activation amount (x value) is defined in the range of 2×10 ⁻⁴ ≦x≦0.18 from the viewpoint of luminance. The phosphor of the present invention whose x value is within the above range is x
It emits yellow to red light in response to changes in value. In particular, a phosphor having an x value in the range of 2×10 ⁻² ≦x≦0.16 emits red light with good color purity. Note that the amount of Eu has almost no effect on the sublinearity of the current density-emission brightness relationship exhibited by the phosphor.
Furthermore, Ce and Ca have little 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 ₂ O ₂ S:Eu phosphor with the same amount of Eu activation.

As explained above, according to the present invention, a phosphor that exhibits a good and stable sublinear current density-emission luminance relationship when the current density of the stimulating electron beam increases is obtained. Of the phosphors of the present invention, especially Eu
A phosphor with an activation amount x value in the range of 2×10 ^-2 ≦x≦0.16 emits red light with good color purity, and therefore, it is preferable to use at least one metal selected from the above-mentioned iron, cobalt, nickel, and vanadium. ZnS contained: Cu,
Al green emitting phosphor or above iron, cobalt,
at least one of nickel and vanadium
In combination with a (Zn, Cd) S:Ag blue-green to green-emitting phosphor containing certain metals (all of which exhibit a superlinear current density-emission brightness relationship), the phosphor film of a current-modulated multicolor cathode ray tube can be fabricated. suitable for configuring. Furthermore, the phosphor of the present invention can also be used in electron beam excitation display tubes other than the above-mentioned current modulated multicolor cathode ray tube.

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

Example 1: Yttrium oxide Y ₂ O ₃ 225.8g Europium oxide Eu ₂ O ₃ 17.6g Cerium oxide CeO ₂ 0.0017g Sulfur S 120g Sodium carbonate Na ₂ CO ₃ 80g Potassium phosphate K ₃ PO ₄・3H ₂ O 20g Calcium carbonate CaCO ₃ 0.1g The above phosphor raw materials were thoroughly mixed, the resulting mixture was filled into an aluminum crucible, and heated to 1200℃ in air.
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 ₂ O ₂ S: Eu _0.1 , Ce _0.00001 , Ca _0.001 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 Figures 1 and 2, the sublinearity of the current density-emission brightness relationship is Y ₂ O ₂ S: higher than Eu _0.1 , Ce _0.00001 phosphor.

Example 2: Yttrium oxide Y ₂ O ₃ 225.8g Europium oxide Eu ₂ O ₃ 10.6g Cerium nitrate Ce (NO ₃ ) ₃・6H ₂ O 0.0044g Calcium nitrate Ca (NO ₃ ) ₂・4H ₂ O 0.24g Sulfur S 120g Sodium carbonate Na ₂ CO ₃ 80g Potassium phosphate K ₃ PO ₄・3H ₂ O 20g In the same manner as in Example 1 using each of the above phosphor raw materials.
Y ₂ O ₂ S: Eu _0.06 , Ce _0.00001 , Ca _0.001 phosphor was obtained.
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 ₂ O ₂ S: Eu _0.06 , Ce _0.00001 fluorescence. It was taller than my body.

Example 3: Yttrium oxide Y ₂ O ₃ 158.1g Gadolinium oxide Gd ₂ O ₃ 108.8g Europium oxide Eu ₂ O ₃ 28.2g Cerium oxide CeO ₂ 0.0017g Calcium oxide CaO 0.06g Sulfur S 120g Sodium carbonate Na ₂ CO ₃ 80g Potassium phosphate K ₃ PO ₄ .3H ₂ O 20 g A (Y _0.7 Gd _0.3 ) ₂ O ₂ S: Eu _0.16 , Ce _0.00001 , Ca _0.001 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 _0.3 ) ₂ O ₂ S: Eu _0.16 ,
Ce _0.00001 was higher than that of the phosphor.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 1 Compositional formula Ln ₂ O ₂ S: Eu _x Ce _y Ca _z (However, Ln is yttrium, gadolinium,
At least one of lanthanum and lutetium
species, and x, y and z are each 2×
10 ^-4 ≦x≦0.18, 2×10 ^-6 ≦y≦4×10 ^-3 and 1×10 ^-5 ≦z≦6×10 ^-2 ). A rare earth phosphor that exhibits a sublinear current density-emission brightness relationship as the beam current density increases. 2. Claim No. 2, characterized in that y is a number satisfying the following conditions: 4×10 ^-6 ≦y≦2×10 ^-3 and z is a number satisfying the following conditions: 1×10 ^-4 ≦z≦3×10 ^-2 The phosphor according to item 1. 3. Claim 1, wherein x is a number that satisfies the condition 2×10 ^-2 ≦x≦0.16
The phosphor according to item 1 or 2.