JPS6046149B2 - Fluorescent material for slow electron beam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phosphor for low-speed electron beams that emits blue light, and more specifically to a conductive metal oxide (In) having a specific particle size distribution.

O. , SnO. , ZnO) and at least one specific blue phosphor in appropriate amounts. Conventionally, indium oxide (In.

O0) and a silver-activated zinc sulfide phosphor (ZnS:Ag) in a weight ratio of 1:9 to 9:1 (see Japanese Patent Publication No. 52-23911), and an oxidized zinc(
A luminescent composition prepared by mixing ZnO) and ZnS:Ag at a weight ratio of 1:9 to 9:1 (Japanese Patent Publication No. 53-257M and In.O. or S having a specific particle size distribution)
nO. , ZnOI■, ZnS1Ag from 1/99 to 1/
Luminescent composition (Japanese Unexamined Patent Application Publication No. 1986-23)
106) is known. These light-emitting compositions emit blue light under slow electron beam excitation at an accelerating voltage of IKV or less, particularly 100V or less, but from a practical standpoint, further improvement in luminance is desired. In the present invention, the accelerating voltage is I
The object of the present invention is to provide a blue light-emitting composition that improves luminescence brightness under slow electron beam excitation of KV or less, particularly 100V or less.Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. .

The present inventors believe that in order to increase the luminance of a blue light-emitting composition formed by mixing a phosphor and a conductive metal oxide, it is preferable that the particle size of the conductive metal oxide be as small as possible. From this point of view, we focused on the conventionally known blue-emitting composition (see Japanese Patent Application No. 55-23106), which is a mixture of a conductive metal oxide with a specific particle size distribution and a blue-emitting phosphor, and various conducted research on

As a result, we found that it is necessary to improve not only the particle size but also the quality of conductive metal oxide particles to create a material that has high luminous efficiency even under low-speed electron beam excitation. Conventional methods for obtaining conductive metal oxides include using general reagents as they are, or by calcining general reagents or commercially available carbonates, sulfates, oxalates, hydroxides, etc. containing metal ions in air. It's a method.

In these methods, impurities contained in general reagents and commercially available carbonates, sulfates, oxalates, hydroxides, etc. containing metal ions are mixed into the process of producing these compounds, resulting in conductive metal oxides. The purity of the product decreased and it was not possible to increase the purity. The present inventors dissolved a general reagent in nitric acid or hydrochloric acid, etc., prepared an oxalic acid compound or hydroxyl compound with oxalic acid or aqueous ammonia, washed with water, dried, and then calcined this compound in air. Highly pure conductive metal oxides were obtained by processing in a clean room and prototyping a special electric furnace.

That is, Irl having high purity and a specific particle size distribution.
It has been discovered that when a suitable amount of 2O3 or ZnO is used, a luminescent composition with improved luminance can be obtained, and furthermore, this effect is not limited to In2O3 and ZnO, but also when tin oxide (SnO2) oxide is used instead of these. Titanium (TiO2)
, tungsten oxide (WO3), niobium oxide (Nb,O
Zinc sulfide phosphor (ZnS:A
g), silver- and aluminum-activated zinc sulfide phosphor (ZnS:Ag,.Al), silver-activated zinc sulfide selenide phosphor [Zn(SlSe):Ag], silver- and aluminum-activated sulfur Zinc selenide phosphor [Zn(S..Se):A
glN], it was discovered that the same effect as above can be obtained, and the present invention was made based on the results of this research. The conductive metal oxide used in the conductive substance that is a component of the luminescent composition of the present invention includes:
In2O3, ZnO. ．． snO2, TlO2, WO3,
NY) 205 and the like.

In particular, Irl2O3, from the viewpoint of luminescence brightness of the resulting composition,
SnO2 and ZnO are more preferred. In addition, In2
Comparing O3 and SnO2, if the blue emitting phosphor is the same, generally if the acceleration voltage is 60V or less, In
The composition using 2O3 has higher luminance than the composition using SnO2, and the opposite is true when the acceleration voltage is higher than 60V. These conductive metal oxides used have a particle size distribution with a median value of 0.1 to 2.4 μ and a standard deviation value (hereinafter all standard deviations refer to 10 gσ) of 0.7 or less.

Particle size distributions in which the median value is outside the above range and the standard deviation value is greater than 0.7 are unsuitable for use due to the low luminance of the resulting composition. A more preferable median value range varies depending on the type of blue-emitting phosphor mixed with the conductive material, but is generally 0.4 to 0.9 μ. Further, when the median value is constant, the standard deviation value is preferably as small as possible, and is generally preferably 0.5 or less. Conductive metal oxides with the above particle size distribution are prepared by dissolving general reagents in nitric acid or hydrochloric acid, etc., creating oxalic acid compounds and hydroxyl compounds with oxalic acid or aqueous ammonia, washing with water, drying, and then calcining in air. The metal oxide obtained by the method of the present invention is obtained by the method of the present invention compared to the conventional metal oxide. This is because the metal oxide obtained by the method of the present invention is of much higher purity and has a uniform particle size. It is possible to obtain a luminescent composition with higher luminous efficiency and better stability than when using a metal oxide prepared by a known method.On the other hand, the blue color, which is another component of the luminescent composition of the present invention, can be obtained. ZnS:Ag phosphor used for luminescent component phosphor, ZnS:Ag,.A
l phosphor, Zn(SlSe):Ag phosphor, Zn(SlSe)
．． Se): Ag. The Al phosphor was manufactured by a conventionally known manufacturing method.

These phosphors generally have a particle size distribution with a median of 1 to 20 microns and a standard deviation of 0.7 or less. Particularly preferred in the present invention are those with a median value of 3μ to 10μ. Among these phosphors, ZnS:Ag phosphor, ZnS:Ag. ．． Al
Preferably, a phosphor is used. The luminescent composition of the present invention can be obtained by combining the above-mentioned conductive substance and blue luminescent phosphor in a mortar, ball mill, mixer mill, or the like.

For both, the value of conductive material/blue emitting phosphor is 1/14 to 1
The value of the conductive material mixed at a weight ratio of 4/1 is 1/1.
When it is less than 4, the effect of preventing charge-up by the conductive material cannot be obtained, and therefore the composition has properties close to those of a blue-emitting phosphor and does not emit light under excitation with a slow electron beam. On the other hand, the value of conductive material/blue emitting phosphor is 14/1
When it is larger, the resulting composition will have very weak luminescence. This is considered to be because, although the charge-up prevention effect is sufficient, the light emission from the phosphor is blocked by the conductive material. The luminescent composition obtained according to the present invention is set in a low-speed electron beam excitation device 1 as shown in FIG. A line can produce sufficiently bright light.

FIG. 2 is a graph showing the relationship between the In2O3 content (wt%) in a luminescent composition prepared by mixing In2O3 and a ZnS:Ag phosphor and the luminescence brightness of the composition.
and c are the cases using Irl2O3 whose standard deviation values are 0.4, but whose median values are 0.3μ, 0.6μ, and 1.5μ, respectively.

In FIG. 2, the luminance (vertical axis) is expressed as a relative value with the maximum luminance on the curve as 100%. Second
As is clear from the figure, the smaller the median value of In2O3, the more Irl2 required to obtain the maximum luminance.
O3 content becomes smaller. That is, I
If n2O3 is used, high-brightness light emission can be obtained with a lower In2O3 content than when In2O3, which has a larger median value, is used. Furthermore, as is clear from Figure 2, when comparing the maximum luminance at each median value, In2O
When the median value of 3 is 0.6μ, the maximum luminance is the highest.
Figure 3 shows the median value of In2O3 and the composition when the standard deviation is constant (10gσ = 0.4) in a luminescent composition in which In2O3 and ZnS:Ag phosphor are mixed as in Figure 2. There is a graph showing the relationship with maximum luminance.

In FIG. 3, the maximum luminance (vertical axis) has a median value of 1.
It is expressed as a relative value with the maximum luminance of a composition using In2O3 having a particle diameter of 5μ as 100%. As is clear from Figure 3, the smaller the median value is until the median value is approximately 0.5μ, the higher the maximum luminance is, and the maximum luminance is reached at approximately 0.5 to 0.6μ. If the value is further reduced, the maximum brightness tends to start to decrease.

Irl2O3 prepared by conventional methods is usually 20μ
This In2O3 has a median value of ~30μ and poor purity.
Considering the luminance of the luminescent composition using the luminescent composition as a standard, the median value of the metal oxide produced by the method of the present invention is 0.
．． It can be seen that when 1f03 of 1 to 2.4 μm is selectively used, a luminescent composition with improved luminance can be obtained. In particular, when In2O3 having a median value of 0.4 to 0.9μ is used, a composition with significantly improved luminance can be obtained. Note that the standard deviation value also affects the luminance of the composition.

That is, in the median range of 0.1 to 2.4p, the luminance tends to decrease as the standard deviation value increases. This is because the larger the standard deviation value is, the more large particles and small particles that have a low contribution to luminance are included. From this point, the standard deviation value is determined to be 0.7 or less. More preferably 0.
5 or less. Note that Figures 2 and 3 show In2O3 and Zn.
This is a graph of luminescent compositions mixed with S:Ag phosphor, but when other conductive powders are used instead of In2O3, Amon Rui or ZnS:Ag phosphor is used instead of other blue light emitting compositions. The same tendency as in FIGS. 2 and 3 was obtained when a fluorescent substance was used.

In the luminescent composition of the present invention, the conductive metal oxide is limited to having a particle size distribution with a median value of 0.1 μ to 2.4 μ and a standard deviation value of 0.7 or less, and the conductive metal oxide It is based on the above-mentioned knowledge that the mixing weight ratio of blue phosphor and blue phosphor is limited to 14/1 to 1/14. As described above, the present invention provides a blue light-emitting composition with improved luminance under slow electron beam excitation at an accelerating voltage of 1K or less, particularly 100 or less, and has great industrial utility value. Next, specific examples of the present invention will be described.

Example 1 Dissolve 1Rl2O3 reagent, add ammonia water to precipitate hydroxide, and wash with water. After over-drying, 1200'
After firing in air at C for 1 hour, pulverizing, and then classifying, 36g of In2O had a particle size distribution with a median of 1.5μ and a standard deviation of 0.4, and 36g of In2O with a median of 6μ produced by a normal manufacturing method. , and a ZnS:Ag phosphor 4f having a particle size distribution with a standard deviation value of 0.35 were thoroughly mixed using a mortar, and then 30 mg of the mixture was taken and placed in the apparatus shown in FIG.

The mounting was carried out by providing the composition 5 on the anode 6 on the insulating substrate 7 placed in the vacuum chamber 1. After evacuating the inside of this device to below 1×10-9T0rr,
When the oxide-coated filament 2 was activated and thermionic electrons 3 were generated with a filament current of 0.09rr1.A, and a voltage of O~150cm was applied between the grid 4 and the anode 6, blue light emission was observed from around 15V. , 70F' at 30V
T. A brightness of L was obtained. Example 2 In2O3 prepared in the same manner as in Example 1 was classified to obtain I having a particle size distribution with a median value of 0.6μ and a standard deviation of 0.4.
n2O33V and the same ZnS:Ag phosphor 7 as in Example 1
y were mixed using a mortar.

When the obtained composition was excited with a slow electron beam in the same manner as in Example 1, blue light emission was observed from around 15V.
120F'T. at 30V. A brightness of L was obtained. Example 3 SnO2 produced in the same manner as in Example 1 was classified to obtain Sn having a particle size distribution with a median of 0.5μ and a standard deviation of 0.4.
O23y and the same ZnS:Ag phosphor 7y as in Example 1 were mixed using a mortar.

When the obtained composition was excited with a slow electron beam in the same manner as in Example 1, blue light emission was observed from around 18V.
90Ft. A brightness of L was obtained. Therefore, the present invention has the effect of improving the luminance of the blue light-emitting composition under low-speed electron beam excitation.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing a demountable device for excitation with low-speed electron beams, Figure 2 is a diagram showing the luminescence intensity with respect to the mixing weight ratio of In2O3 and ZnS:Ag, and Figure 3 is a diagram showing ・In2O3.
2 is a graph showing the relationship between the median value of In2O3 and the maximum luminance of the composition when the standard deviation is kept constant in a luminescent composition in which ZnS:Ag and ZnS:Ag phosphor are mixed.

Claims (1)

[Claims] 1. The median value is 0.1 μ to 2.4 μ, the standard deviation (log θ
) at least one of conductive metal oxides (In_2O_3, SnO_2, ZnO) having a particle size distribution of 0.7 or less, and a silver-activated zinc sulfide phosphor (ZnS: Ag), silver and aluminum activated phosphor (ZnS:Ag,Al), silver activated zinc sulfur selenide phosphor [Zn(S,Se):Ag], silver and aluminum activated zinc sulfate selenide phosphor Light body [Zn (S, Se):Ag)
A phosphor for low-speed electron beams, which is formed by mixing at least one of Al] with a weight ratio of 14:1 to 1:14. 2. The phosphor for low-speed electron beams according to claim 1, wherein the blue-emitting phosphor has a median value of 3 μ to 10 μ.