JPS62146980A - Fluorescent material for low-velocity electron beam - Google Patents

Abstract

PURPOSE:To obtain a color fluorescent material which does not contain any sulfide and emits light by irradiation with a low-velocity electron beam without the need of adding a conductive substance, by doping matrix represented by (In1-xBx)2O3 with a rare earth element as activator. CONSTITUTION:In2O3 is mixed with H3BO3 and 0.1-20atm% rare earth metal oxide, and this mixture is baked to give a fluorescent material for a low-velocity electron beam of the formula (In1-xBx)2O3:R (wherein R is at least one of rare earth elements such as Sm, Eu, Tb, and Tm; 0.05<x<0.4).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] Color display devices of red, green, blue, etc. are used in various electronic devices, home appliances, computer terminals, front panels of cars, and the like. Fluorescent display tubes have come into widespread use as light-emitting elements in color display devices, as they can be driven at low voltages, consume less power, and are self-luminous, providing bright, easy-to-see displays. It's coming.

When trying to perform multicolor luminescent display with this fluorescent display tube,
The phosphor for emitting light is a phosphor for low-speed electron beams that emits light at a low accelerating voltage of several volts to several tens of volts.

The present invention relates to this phosphor for slow electron beams, and particularly to a rare earth-activated phosphor that is a color phosphor that does not contain sulfides.

[Prior art]

Conventionally, color phosphors for low-speed electron beams used in color fluorescent display tubes are excited by the impact of electron beams accelerated by high voltages of several hundred to several thousand volts used in well-known color CRTs. and emits light.

Phosphors for high-speed electron beams have been mixed with conductive substances such as Im, 03, SnO2, etc. to improve conductivity and have been used as phosphors for low-speed electron beams. For example, the following phosphors for slow electron beams are known.

For blue light emission, ZnS:Ag+In, O; for green light emission, ZnS:Cu, A Q +In,
03 phosphor for lemon color emission, ZnS:Au, A
Q +In2O, for phosphor yellow light emitting, (Zn,, 9Cdo, 1)S:A
u, A Q +In.

03 phosphor for yellow-orange emission, (Znn, Cd,)S:Ag+
'In,03 phosphor for orange light emission is ZnS: Mn+ In2O,
For red light emitting phosphor, (zn,,2cd.,)S
:Ag+rn7. Oq Phosphors However, all of the color phosphors already in use contain sulfur S in their matrix.

Therefore, these phosphors are collectively called sulfide-based phosphors. When this sulfide-based phosphor is used in a fluorescent display tube, color display is possible, but since it contains sulfide, it has been desired to further improve the lifespan.

This is because if the phosphor used in the fluorescent display tube contains sulfide, the following effects will occur when the fluorescent display tube is turned on.

A fluorescent display tube consists of a filament-shaped cathode that emits electrons into an envelope maintained in a high vacuum, an anode made of a phosphor layer and an anode conductor that emit light when the emitted electrons collide with each other. It is composed of a control electrode that accelerates and controls the electrons as necessary.

To explain the filament-shaped cathode in more detail, oxides of alkaline earth metals such as Ba, Sr, and Ca are formed on the surface of the tungsten wire (Ba, Sr, Ca)O.
The electron-emitting material layer is deposited in the form of a solid solution shown in FIG. When a voltage is applied to the tungsten wire, it generates heat, and when electrons are emitted from the electron-emitting material layer on the surface, these electrons are accelerated by the control electrode and collide with the phosphor layer of the anode. The phosphor is excited and emits light, but at the same time, part of the surface of the sulfide phosphor decomposes and sulfide gases such as s, so, so2, and 1128 are released. Since this sulfide-based gas is unlikely to be adsorbed by the getter film provided on the inner wall of the envelope, it gradually accumulates in the envelope as the lighting time is accumulated. When this sulfide-based gas adheres to the filamentary cathode, it reacts with the alkaline earth metal of the electron-emitting material layer to form sulfide, thereby significantly deteriorating the emission characteristics of the cathode. As a result, fewer electrons impinge on the anode, the anode current decreases, and the luminance of the phosphor layer drops sharply, resulting in a shortened lifespan of the fluorescent display tube.

In addition, the known color phosphors have improved conductivity by adding various conductive substances to the phosphor for high-speed electron beams, but these conductive substances do not emit light by themselves, so they are not suitable for mice. If it is added in excess of a certain amount, it has the effect of blocking the luminescence of the fluorescent bodies. Therefore, the luminance decreases by one point due to a decrease in the light emitting area, which is not preferable.

Furthermore, since the conductive materials are not evenly mixed, it is difficult to obtain uniform light emission. Therefore, it is necessary to take measures such as making the conductive material into ultrafine particles, resulting in problems such as an increase in the cost of the phosphor.

[Purpose of the invention]

Therefore, the present invention was made to solve the above-mentioned problems, and the present invention was made to solve the above-mentioned problems.
However, focusing on the phosphor expressed by O<x≦0.6),
In place of Y2O3 in this phosphor, B20. The object of the present invention is to provide a color phosphor containing no sulfide and emitting light with a slow electron beam without adding a conductive substance.

[Structure of the invention]

In order to achieve the above object, the present invention provides that the general formula is CI
n1-x Bx) 20a :R (However, R is Sm, 'E
The present invention is characterized in that it is a phosphor for a slow electron beam expressed by 0,05<x<0.4), which selects at least one of rare earth elements such as u, Tb, and Tm.

Here, the amount of activator R is the parent (In1-XBX)2
0.03 compared to 0.03. It is preferably 1 to 20 atm%.

[For production]

The low-speed electron beam phosphor of the present invention is a known (In□-XY
x) Focusing on 203: Eu phosphor, indium In that constitutes the matrix is a group 3B element, but yttrium Y is a group 3A element, so instead of yttrium Y, the same group 3B element as indium In is used. A certain boron B was dissolved in solid solution. A phosphor for low-speed electron beams according to the present invention was obtained by doping a rare earth element as an activator into the matrix of C"x -x Ill X) 203.

This phosphor for low-speed electron beams does not contain sulfides, so even when used in fluorescent display tubes, it will not cause deterioration of the cathode emission characteristics, and since it does not contain conductive substances, there will be no reduction in brightness. , has the effect of preventing non-uniform light emission, etc.

[Example 1] Embodiments of the present invention will be described below with reference to the drawings.

(Xnx-xBX) zo3: Eu (however, O<x
<0.4), rEu was selected from rare earth elements as the activator, 1 stm% was fixed relative to the weight of the base material, and boron oxide B20. Various types of indium oxide In, 03 were mixed at a ratio of (1'-x) moles to X moles of In, 03, and the mixture was placed in a furnace in an air atmosphere and fired at 1300° C. for about 3 hours to form a solid solution.

The specific blending ratio is as follows.

When x=0.05, H, BO3---0,15
4gIn2O,...6.59g Eu,O,...
Weigh and mix 0.044g.

When x = 0.1, H3BO,' ”-0,3
09gIn203-6.25g Eu2O,=・0.
044 g and mix.

When x = 0.2, 83BO3---0,61
8gIn203...5.56g Eu2O,...
Weigh and mix 0.044g.

When x=0.3, H, BO3-・-0,927
gIn, 03”・4.86g Eu2O,”・0.0
Weigh out 44g and mix.

When x=o, '4, H, BO, ""1.236
gIn203"・4.166g Eu2O3...
Weigh and mix 0.044g.

The materials mixed at the above ratio were fired at 1300° C. for about 3 hours to synthesize five types of phosphors, and each of them was applied to the anode conductor of the anode substrate to form a fluorescent display tube and emit light. The brightness was measured when the cathode voltage was 1.7V and the anode voltage was varied from 0 to 150V. FIG. 1 shows the above I
It is a graph showing the relationship between wh polar voltage and relative brightness when five types of phosphors with different molar ratios of n2O3 and B2O3 are emitted. In the figure, the A1111 line is when x=0.05, that is, (Inn,, JS'nn-11s
)203 Ni-Eu phosphor, which emits red light when the anode voltage is below IOV, but the relative brightness is 1 even at 40V, which is the value of a practical 1-peracid.

The 8 curves in the figure are calculated when x = 0.1, that is, (I
nn, s Bol) 203: Eu phosphor. The emitted light color was red, and the relative brightness was 20 when the anode voltage was 50 V, so that a practical level of light emission was obtained.

Curve C in the figure is calculated when x = 0.2, that is, (I
no, s Bo, = )203: Eu phosphor. The emission color is as shown in the emission spectrum diagram in Figure 3.
The peak value is around 590 nm, and since it has a peak on the longer wavelength side, it emits red light. , m degree is 5
It is the highest among the types, with an anode voltage of 50V, ranking 60th, and has sufficient brightness for practical use.

The curve in the figure is shown when x = 0.3, that is, (
Inn, □Bo, a) 203: Eu phosphor. The luminescent color is red because the activator is Eu.

The brightness was 20th relative brightness at an anode type = 8-voltage of 70V, and a practical level of light emission was obtained.

The 8th curve in the figure is the phosphor when x=0.4, that is, the (In., s Bo, 4) 20a : Eu phosphor. The emitted light color is red, but the relative brightness is low.
This is the minimum practical brightness.

From these data, the range of X is 0 for low-speed electron beams.
．． It can be seen that 05<x<0.4 is suitable.

That is, it is contained in a larger amount than Inti-B to impart conductivity. Preferably, 0 containing a large amount of In
, 1≦X≦0.3, and the brightness is also within a sufficient range.

[Example 2] The amount of In2O3 and 113BO, that is, the matrix is x = 0
．． 3 was fixed, and four types of phosphors were synthesized using Eu, Tb, Tm, and Sm selected from rare earth elements as activators in this matrix. The specific mixing ratio is as follows.

The parent body is (Ino, 7Bo, a)*O'a, and In
, O, is 4.86 g and l+3[103 is 0.927
g, europium Eu, terbium Tb, and thulium Tm are selected from the rare earth elements as activators, and terbium oxide Tb2O3 is 1 stm% 0.46
A phosphor was synthesized by mixing 2 g of phosphor and 0.0483 g of 1 stm% thulium oxide TlI2O3. The manufacturing method is the same as in Example 1, so the explanation will be omitted.

The activator was doped with terbium Tb at 1 atm% (I
na, t Bo, a ) z O3: The emission spectrum of the Tb phosphor is green light having a peak around 540 nm, as shown in FIG.

In addition, thulium Tm was used as an activator (Inn, t[11
1, 3) 20a: Tm phosphor is 3 as shown in Figure 5.
It is a blue-emitting phosphor with a peak around 80 to 500 nm. Similarly, a phosphor using samarium Sm as an activator emitted red light. Since europium Eu was explained in the first embodiment, it will be omitted here. By changing the activator in this way, samarium Sm, europium E11
emits red light, terbium Tb emits green light, thulium T+
It is possible for u to emit blue light and change the emitted color.

Therefore, it can be used as a color phosphor.

Furthermore, FIG. 2 is a graph showing the anode voltage and relative brightness when a fluorescent display tube is formed using three types of phosphors with different activators and lit.

The F curve in the figure shows that terbium Tb is used as an activator at a ratio of 1 to the base material.
atm% doped (Ina,tBa,a)2
03: Tb phosphor with the highest sphericity among the three types. Green light emission starts when the anode voltage is about 20V, and about 4
A practical brightness with a relative brightness of 10 at 0V was obtained.

Curve 6 in the figure shows the activator doped with europium Eu at 1 atm% relative to the matrix (Ina4 Be, a)20
a: Eu phosphor, which started emitting red light at an anode voltage of about 22 V, and a practical luminance of relative luminance of 6 was obtained at about 60 V.

In the figure, the H curve indicates that thulium Tm is used as an activator and 1
atm% doped CIno7Bo, i) 20a
: It is a Tm phosphor and starts emitting blue light at an anode voltage of about 25V, and practical brightness was obtained when raised to about 50V or more.

Next, in order to find out the appropriate amount of activator for the red-emitting phosphor of (In, IBX) 203:Eu, (Inn, IIBo, z
) to the parent body of zoa, europium Eu was used as an activator.
0. Various types of phosphors were synthesized when added at 1 to 20 atm%, and the luminance was measured using them in fluorescent display tubes. FIG. 6 is a graph showing the relationship between the concentration of Eu activator-11= and relative luminance.

Relative luminance is the peak value of the luminance measured above by 100.
This is the value expressed as .

As can be seen from this graph, when Hu was 0.1 atm %, the relative luminance was in the 50th place, which was a sufficiently usable brightness. However, when the concentration is 0.1 atm % or less, the doping effect is small and no light is emitted. Therefore, the minimum limit for activator is 0.
It can be said that it is 1stm%.

As the concentration of the activator increases, the relative luminance also increases and reaches a peak at about 2 atm%.

If the concentration is increased beyond that, it will gradually decrease.

When the concentration of the activator becomes 20 atm%, the relative luminance is 4
The luminance reaches the 0th position, which is the lowest luminance for use, and if the concentration of the activator is increased beyond this level, the luminance decreases and becomes unusable. Therefore, the amount of activator is 0. l~20atm%
The usable range is 0.2 to 1, preferably 0.2 to 1.
The range is 0 atm%, and the brightness is also in a sufficiently high range.

In addition to europium Eu, samarium 5I11, terbium Tb, and thulium Tm had similar trends.

〔effect〕

As explained above, the present invention has a general formula (InlL-X
By) zoa :R (However, R is Ss, Eu, Tb
, a color phosphor for low-speed electron beams that does not contain sulfides expressed by 0.05<X<0.4) and is not mixed with conductive substances, which selects at least one of rare earth elements such as Tm, etc. A fluorescent display tube using the low-speed electron beam phosphor of the present invention has excellent emission characteristics and has the effect of providing a long-life display tube.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between anode voltage and relative brightness when the phosphor for slow electron beams of the present invention is emitted, and Figure 2 is a graph showing the relationship between the anode voltage and relative brightness when the phosphor for slow electron beams of the present invention is activated. Graphs showing the relationship between anode voltage and relative brightness when changed, Figures 3 and 4
5 is a graph showing the emission spectrum of the phosphor for slow electron beams of the present invention, and FIG. 6 is a graph showing the relationship between activator concentration and relative luminance of the phosphor for slow electron beams of the present invention. It is a graph.

Claims (2)

[Claims] (1) The general formula is (In_1_−_xBx)_2O_3
:R (However, R is at least one rare earth element such as Sm, Eu, Tb, Tm, etc., 0.05<x<0.
4) A phosphor for slow electron beams represented by: (2) The amount of the activator R is 0. l~20a
The phosphor for slow electron beam according to claim 1, which is tm%.