JPH0326781A - Fluorescent substance - Google Patents

Abstract

PURPOSE:To obtain a fluorescent substance useful for cathode ray tube, display tube, etc., having excellent electrical conductivity and emission luminance by coating the surface of fluorescent substance with a complex electroconductive substance prepared by sticking electroconductive fine particles to the surface of electroconductive large particles. CONSTITUTION:The surface of fluorescent substance particles is coated with preferably 0.1-15wt.% complex electroconductive particles prepared by sticking (A) electroconductive fine particles 1 having preferably 0.0001-0.1mum average particle diameter and containing one or more of Al, Au, Ag and Cu to (B) the surface of electroconductive large particles 2 having preferably 0.01-2mum average particle diameter and containing one or more of SnO2, Sb2O3 ZnO, In2O3, O3, TiO2, Bi2O3, Nb2O5, CdS and MoO3 to give the aimed fluorescent substance.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a phosphor excited by an electron beam and a method for manufacturing the same. In particular, the present invention relates to a phosphor used in cathode ray tubes, display tubes, etc., and a method for manufacturing the same.

[Conventional technology and problems]

Phosphors that emit light when excited by the irradiation beam are required to have electrical conductivity. Phosphors with low conductivity cannot quickly release the negative charge of the excited electron beam to the ground. Therefore, negative charges are accumulated in the fluorescent film. A fluorescent film with accumulated negative charges repels negatively charged electron beams. That is, the electron beam cannot effectively excite the fluorescent film, resulting in a decrease in luminance. In particular, the brightness of small cathode ray tubes, which are beginning to be used in the hallways of homes and telephones, and display tubes, which are widely used in cars, audio and video devices, is susceptible to a decrease in brightness due to this phenomenon. This is because the acceleration voltage of the electron beam that excites the fluorescent film is low. An electron beam with a low acceleration voltage has low energy and is easily repelled from the fluorescent film due to its negative charge. A fluorescent display tube excites a phosphor to emit light using a low-speed electron beam of several to several tens of volts emitted from a linear, needle-shaped, or planar filament. A small cathode ray tube excites a phosphor with a medium-speed electron beam of several hundred volts to several kilovolts. The phosphors used in these applications are excited by electron beams whose acceleration voltage is significantly lower than that of ordinary color cathode ray tubes. Therefore, electrical conductivity is particularly important for phosphors used in these applications. This is because the phosphor is excited by a low-voltage driven electron beam, so the current density is higher and the phosphor emits brighter light than a normal color cathode ray tube which is excited by a high-speed electron beam of IOKV or higher. The reason is that because the phosphor layer is continuously excited with a negatively charged electron beam, negative charges accumulate in the phosphor layer, which has poor conductivity, repelling the electron beam and causing it to no longer emit light. It is. Furthermore, color televisions for consumer use are becoming increasingly larger, and currently 25 to 37 inches are the mainstream. As the size increases, the driving conditions such as electron beam accelerating voltage and current density have changed from 25 to 27 KV to 31 to 35 KV, and 0. 0
5-0. 1 μmA/cm2 to 0. 2 to 5
．． The voltage and current are increasing to 0 μmA/cm2, and the conditions are becoming stricter for phosphors. Some phosphors are semiconductors, but most are insulators. In order for these to exhibit excellent performance under high current conditions, it is necessary to impart conductivity to the surface of the phosphor crystal to prevent negative electrons from accumulating. ZnO/Zn self-activating phosphors are well known as phosphors with excellent conductivity. However, this phosphor has a bluish-white color tone, and cannot produce an emission color that is preferable as a green component for color cathode ray tubes. The following are preferably used as green, blue, and red emitting phosphors.■ As green emitting phosphors, ZnS/Cu, A9, ZnS/Cu 9 A IJ + k,
■ As blue-emitting phosphors, ZnS/Ag, A, ZnS/Ag, C, ■ As red-emitting phosphors, (Zn-Cd)S/Ag, (Al, Y2O3, ZnO, In2O2S:Eu, etc.) are used. These phosphors have the disadvantage of low conductivity.For this reason, they cannot be used with electron beams with high current density and low voltage acceleration.
Cannot emit light with sufficiently high brightness. In order to improve the conductivity of these phosphors, a method has been developed in which indium oxide (In2O3, ZnO, In2O3) is mixed with the phosphors (Japanese Patent Publication No. 52-2391).
Publication No. 1, Special Publication No. 52-23913, Special Publication No. 52
-2391 No. 6). However, by mixing indium oxide with the phosphor, sufficiently satisfactory conductivity cannot be achieved. When mixing In2O3, ZnO, and In2Oa to improve the conductivity of the phosphor, a large amount of In2O3, ZnO, and I
It is necessary to mix n2O3. In fact, in order to improve the conductivity of the phosphor by mixing In2o3, it is necessary to mix as much as 15 to 25% by weight. When such a large amount of non-luminescent material is added, In2O3,
Brightness decreases due to ZnO and In2O3. This invention was developed with the aim of solving these conventional drawbacks, and an important purpose of this invention is to improve the conductivity of the phosphor and provide a phosphor that can increase luminance. It is in.

[Means to solve conventional problems]

The present inventors have reduced the amount of adhesion by attaching a unique form of composite conductive material to the surface of the phosphor.
We succeeded in improving the conductivity of phosphors. The composite conductive material is made by attaching conductive fine particles, which are finer than the large conductive particles, to the surface of the conductive large particles. The amount of the composite conductive material deposited is specified to be 0.1 to 15% by weight based on the phosphor. FIGS. 2 and 3 show the luminance of the phosphor with respect to the amount of the composite conductive material deposited. In these figures, the solid line shows the characteristics of the phosphor of the present invention, and the chain line shows the characteristics of the non-staining phosphor. As shown in these figures, the phosphor of the present invention has a coating amount of the composite conductive material of 0. When the content is 1 to 15% by weight, excellent light emitting properties are exhibited. However, the curve in Figure 2 shows that the phosphor is ZnS/Ag, AQ.
A phosphor is used, and the composite conductive material adhering to the surface of the phosphor of the present invention uses SnO2 adsorbed with Ag fine particles, while the conductive large particles adhering to the surface of the conventional phosphor include SnO2.
2 is used. Furthermore, the characteristics shown in Fig. 3 indicate that the phosphor contains ZnS/Au, A
△ A phosphor is used, and the composite conductive material attached to the surface of the phosphor of the present invention includes adsorption of Au fine particles ■n2O3, ZnO
, In2O3 are used, and In2O3, ZnO, and In2O3 are used as conductive large particles that adhere to the surface of conventional phosphors. The purpose of the present invention is to increase conductivity and reduce the amount of coating on the phosphor by coating the phosphor with a composite conductive material in which conductive fine particles are adsorbed onto the surface of conductive oxide particles or compound particles. This problem can be solved by fully utilizing the efficiency of the phosphor. Further, the phosphor of the present invention preferably has the following configuration. (a> The conductive fine particles preferably include A△, Au
, Ag, and Cu. However, conductive fine particles include lithium (Li),
Beryllium (Be), sodium (Na), magnesium (Mg), potassium (K), calcium (Ca),
Iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), rubidium (Rb), molybdenum (Mo
), rhodium (Rh), palladium (Pd), cadmium (cd), indium (In), tin (Sn), tungsten (W), osmicum (Os), iridium (Ir
), platinum (Pt), scandium (Sc), titanium (T
i), vanadium (V), chromium (Cr), manganese (
Mn), gallium (Ga), germanium (Ge), styrontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), technetium (Tc)
), ruthenium (Ru), antimony (Sb), cesium (Cs), barium (Ba), hafnium (Hf),
tantalum (Ta), rhenium (Re), mercury (lig),
Thallium (T△), lead (Pb), bismuth (B i),
Fine particles of metals such as boronium (P o), lanthanium group, actinium group, etc. can also be used. (b) The average particle size of the conductive fine particles is 0.0001 to 0.0001.
Adjust to a range of 0.1-0.171m. (c) The amount of adhered conductive fine particles is in the range of 1 to 50% by weight based on the conductive large particles. (d) Conductive oxide particles or conductive compound particles are used as the conductive fine particles. (f) The average particle size of the conductive large particles is 0.01 to 2μ.
Let it be m. (g) SnO++, Sb2O3, conductive large particles,
ZnO, In2O3, Zno, In2O3, ZnO
, In2O3, Wo3, Ti○2, B l2O3,
ZnO, In2O3, Nb2O3, ZnO, In2O
5. Particles containing at least one of C d S and M o 03 are used. By the way, this invention is characterized by using a unique composite conductive material to which the phosphor is attached. Therefore, this invention does not specify the phosphor to which the composite conductive material is attached. The phosphor to which the composite conductive substance is attached can be applied to all electron beam-excited phosphors, such as color phosphors and monochrome phosphors. For example, the following phosphors can be used: ■ ZnS, (Zn, Cd)S, CdS, ZnS-Se
1 (Zn-cd)S-Se, CdS, Se as a matrix, at least one of Ag, Cu, Au, Zn as an activator, C△, Br, F, I, AQ, Ga%In,
Sulfide-based phosphor containing at least one of Li, Pb, As, Bi, Eu, and Sn as a coactivator, ■ ZnO/Zn, Y2O3, ZnO, In2O3/E
Oxide-based phosphor such as n, Zn○2/EU, ■ La
P Oa/ C e, T b, (Zn-Ca)3(
PO4) 2Mn, C d SCQ (POa) 3
/Mn and other phosphate phosphors, ■ Y2S i Os/ T b, Y2S i Os
/C e, Znsi○4/MnSCaS iO3/Mn
Silicate phosphors such as ■ Y3AQ+2O3, ZnO, In2Os/Tb, Y
Aluminate-based phosphors such as 3AQ+2O3, ZnO, In2O5/Ce, ■ Y2O3, ZnO, In2O2/
Ell, Gd2O3, ZnO, In2O2S/Tb, Y
Oxysulfide phosphors such as 2O3, ZnO, In2O2S/Tb, etc. Furthermore, these phosphors have an average particle size of 1 to 12 μm.

[Effects of this invention]

This invention improves the conductivity of the phosphor by attaching a unique composite conductive material to the surface of the phosphor particles. The composite conductive material used is a unique material in which conductive fine particles are attached to the surface of conductive large particles. This composite conductive material can increase the conductivity several times compared to conventional conductive materials attached to the phosphor surface. Therefore, the amount of coating on the phosphor can be reduced to a fraction of that of the conventional method, and the same conductivity can be achieved. For example, aluminum (AM), gold (Au), silver (Ag), m
(Cu) etc., the conductivity of these is 2. ．． 6 5 X 10-6S/cm, A u is 2. 4X 10-6S/cm, Ag is 1.59X
10-”S/cm, Cu is 1, 6 7 X 1 0-6
S/cm, which is extremely low. On the other hand, the conductivity of conventional conductive oxide particles attached to the surface of the phosphor for the purpose of improving conductivity is
In2O3, ZnO, In2O3 is 8. 3 7 X
IO-'S/cm, Sna2 is 1 1. OX
1 0-6S/c+n, ZnO is 5.9X 1 0
-65/CIll, WO3 is 5. 6 5 X l
O-6S/cm, TIO2 is 42X10-8S/cm
, CdS is as high as 6.83X10-65/am. It is also conceivable to improve the conductivity of the phosphor by attaching conductive metal fine particles having low conductivity instead of conventional conductive substances. However, in reality, attaching conductive metal fine particles to the surface of a phosphor requires a fairly sophisticated technique. Conductive metal particles have very high reactivity because they are submicron particles, and for example, S on the surface of a ZnS crystal.
This is because if there is enough water, it will react rapidly and become sulfide. Metal oxide particles are chemically stable substances with poor conductivity but low reactivity. This invention realizes an excellent phosphor by simultaneously satisfying the advantages of both stable conductive large particles and conductive metal fine particles with excellent conductivity. That is, as shown in FIG. 1, the phosphor of the present invention is
The phosphor is coated with conductive large particles 2 having conductive fine particles 1 attached to their surfaces. The conductive fine particles 1 rarely come into direct contact with the phosphor, but are attached to the surface of the phosphor via the conductive large particles 2. For this reason, conductive fine particles 1
Most of them do not come into direct contact with the phosphor. The conductive fine particles l that do not come into contact with the phosphor particles improve the conductivity of the phosphor, but are less likely to react with the phosphor component. By the way, a composite conductive material in which 25% by weight of Ag fine particles with an average particle size of 0.08 μm are adsorbed onto 1.2 Bm Sn02 particles is SnO+, which does not have Ag fine particles attached.
Compared to particles, the electrical conductivity was reduced by half to 6 x 10-6 S/cm. Therefore, in the phosphor of the present invention, the amount of the composite conductive material deposited can be reduced to half that of the conventional SnO2, and the conductivity of the phosphor can be kept the same. Since the composite conductive material attached to the surface of the phosphor is a non-luminescent material, it is desirable to keep the amount of the composite conductive material in a small amount. The phosphor of the present invention, which can improve conductivity with a small amount of composite conductive material, has the advantage of increasing brightness.

[Preferred example]

Examples will be described below. [Example 1] A phosphor having a composite conductive material attached to its surface is manufactured in the following steps. ■ As conductive large particles, S with an average particle size of 1.27zm
n02 particles (use 30g, add them to a beaker containing 300cc of water and stir. ■ Conductive large particles are mixed into the water, and conductive fine particles are mixed and stirred. has an average particle size of 0.08
Ag fine particles 2O3, ZnO, and In2Og having a diameter of μm are used. Ag fine particles are produced by spray cooling molten Ag. The water containing the conductive fine particles and the conductive large particles is stirred for 30 minutes using a magnetic stirrer. In this process, Ag
A composite conductive material with particles adsorbed thereon is obtained. When the composite conductive material obtained in this step was separated from water and the conductivity was measured, it was found to be 6 x 10-6S/cm.
It was ● ■ Z n S/Ag-All phosphor 1 kg, 2
．． Add to 2△ water and stir, and pour the slurry obtained in ① into this. ■ Roughly, as an adhesive A Q 2 S i O 3
1 g of the composite conductive material is added to the surface of the phosphor particles. ■ The phosphor was separated, dried, and finished through a 300 mesh sieve. When the brightness of the obtained phosphor was measured using a phosphor brightness measurement demantaple device at an accelerating voltage of 50 V and a current density of 1 mA/CITl2, the brightness was compared to that of a conventional mixture of SnO2 at 16% by weight based on the phosphor. , 2O3, ZnO
, In2O% also had higher brightness. [Example 2] (2) Add conductive large particles to 300 cc of water and stir. The conductive large particles have an average particle size of 0. 5Jim's I
50 g of n2O3, ZnO, In2O3 particles are used. (2) Add conductive fine particles to the water in (2) and stir. The conductive fine particles include A u-2 with an average particle size of 0.003 μm.
30 g of c2oid fine particles are used. These conductive fine particles are produced by stirring HAuCΔ3 in an aqueous solution containing formaldebit. The water to which the conductive fine particles and conductive large particles have been added is stirred for 30 minutes using a magnetic stirrer. In this process, In2O3, ZnO, In2O3 particles,
A. A composite conductive material adsorbed with u colloid fine particles is obtained. The conductivity of the composite conductive material obtained in this step is 5X1
It was 0-6S/cm. (2) 1 kg of ZnS/Au-AQ phosphor is added to 262△ water and stirred, and the composite conductive material dispersion slurry obtained in (2) is poured into the water. Zn as an adhesive
Add 1 g of 2SiO3 to attach the composite conductive material to the surface of the phosphor. ■ The phosphor with the composite conductive material attached to its surface is separated, dried, and finished using a 300 mesh sieve. The phosphor obtained in this step was measured using a brightness measurement demantaple device at an acceleration voltage of 50 V and a current density of 1 mA.
When I measured the brightness at / cm2, In2O3, Z
Compared to a conventional phosphor containing nO and In2O3 in an amount of 18% by weight based on the phosphor, the brightness was 25% higher. [Example 3] 15 g of A magazine fine particles with an average particle size of 0.037 zm were used as the conductive fine particles, and 0.03 g of A magazine fine particles with an average particle size of 0.037 zm were used as the conductive large particles. 8 μm I
n2snos (Sn dove mo-i mole) 6
A composite conductive material was obtained in the same manner as in Example 1 using 0 g. As the conductive fine particles, A△ fine particles produced by spray cooling AQ molten metal are used. The obtained composite conductive material has a conductivity of 4.5×10−
'S/cm. This composite conductive material is (Zn-cd)S/Ag-CM
It is applied to 1 kg of phosphor using the same process as in Example 1. The brightness of the phosphor obtained in this step was measured in the same manner as in the previous example, and it was found that [n2S
Compared to the case where 12% by weight of n05 was attached to the surface of the phosphor, the brightness was 23% higher. [Example 4] Conductive fine particles were produced by spraying and cooling Cu melt,
25 g of Cu fine particles with an average particle size of 0.005 μm were used, and S n S with an average particle size of 1 μm was added to the conductive large particles.
A composite conductive material was obtained in the same manner as in Example 1 except that 0 g of b2O3, ZnO, and In2Os3 were used. The conductivity of this composite conductive material is 6×10-6S/
It was cm. This composite conductive material was processed into Z
A phosphor is produced by adhering it to 1 kg of n S/Cu u-AQ phosphor. The brightness of the obtained phosphors was measured in the same manner as in the previous example, and it was found that SnSb2O3, ZnO,
Compared to a conventional phosphor with 10% by weight of In2O5 attached, the brightness was 18% higher.

[Brief explanation of drawings]

Figure 1 is an enlarged plan view showing the phosphor particles of the present invention, Figure 2 is an enlarged plan view showing the phosphor particles of the present invention.
The figure and FIG. 3 are graphs showing the brightness of the phosphor with respect to the amount of the composite conductive material deposited. 1... Conductive fine particles, 2... Conductive large particles.

Claims (2)

[Claims] (1) A phosphor having the following configuration. (a) A composite conductive material is attached to the surface of the phosphor. (b) A composite conductive material is one in which conductive fine particles are attached to the surface of conductive large particles. (c) The average particle diameter of the conductive fine particles is smaller than the average particle diameter of the conductive large particles. (d) The amount of adhesion of the composite conductive material is 0.0% relative to the phosphor.
It is 1 to 15% by weight. (2) The phosphor according to claim 1, having the following configuration. (a) The conductive fine particles contain at least one of Al, Au, Ag, and Cu. (b) The average particle diameter of the conductive fine particles is 0.0001 to 0.000.
It is 1 μm. (c) The adhesion amount of the conductive fine particles is 1 to 50% by weight based on the conductive large particles. (d) The conductive fine particles are conductive oxide particles or conductive compound particles. (e) The average particle size of the conductive large particles is 0.01 to 2 μm. (f) The conductive large particles are SnO_2, Sb_2O_3,
ZnO, In_2O_3, WO_3, TiO_2, Bi
Contains at least one of _2O_3, Nb_2O_5, CdS, and MoO_3.