JPS6155186A - Fluorescent substance - Google Patents

Abstract

PURPOSE:A fluorescent substance capable of effecting multi-color lightemission with a single particle, containing CaS, Ce, Eu, and an alkali metal. CONSTITUTION:A fluorescent substance of the formula (where X is Li, Na or K). The content of an alkali metal X is preferably 10<-5>-10<-1>mol per mol of CaS. This fluorescent substance produces luminescent color which can be changed by changing the acceleration voltage under cathode-ray excitation, and is suitable as a fluorescent substance for a penetration-type cathode-ray tube. For exmple, for a fluorescent substance of the formula containing 0.002mol of Li, the curve 1 in the figure shows an emission spectrum under an acceleration voltage excited with cathode ray of 3kV, and the curve 2 shows an emission spectrum under an acceleration voltage of 20kV. These luminescent colors (chromaticity values) are continuously variable by varying the acceleration voltage, thus effecting luminescent colors from red to green.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to calcium sulfide phosphors containing Ce, Eu and alkali metals.

[Technical background of the invention and its problems]

When recognizing information visually, a single color (e.g. black and white)
A colored display is much better than a complex image provided by a multi-layered display (which can be read and judged instantly, i.e. color 1); It is more intuitive (i.e., easier to recognize and attract attention) than the content that is expressed.This advantage is useful in fields where instantaneous judgment is required amidst ever-changing information, such as aviation. There is a large demand for it in areas such as air traffic control, production management, and medical diagnosis.

Devices capable of color display are usually color cathode ray tubes. Its basic configuration is a dot-shaped three-color screen and a shadow mask for color image regeneration.

Consists of three electron guns. Due to this basic structure, there are two major problems: low resolution as the display device required in the above field.

A cathode ray tube that has been developed to solve this problem is the so-called penetration cathode ray tube. Usually, this cathode ray tube consists of a single electron gun, and its accelerating voltage is appropriately changed to enable multicolor display. The fluorescent screen, for example, consists of two phosphor layers that emit red and green light. That is, when the accelerating voltage of the electron beam is low, only the red phosphor in the first layer emits light, and when the accelerating voltage is high, the electron beam that has passed through the first layer reaches the second layer and emits green light. Emits light. As a result, red to green light emission can be obtained by increasing the acceleration voltage from a low voltage to a high voltage. However, due to its structure (2), the electron beam scattered in the first layer and the red light emitted from the first layer affect the second layer, making it difficult to achieve the desired resolution. In a penetration-based cathode ray tube, when the accelerating voltage is increased, it is necessary for the electrons passing through the first layer to excite the second layer.In addition, it is necessary to apply a thin phosphor layer. Moreover, it has the disadvantage that it must be applied uniformly over the entire screen.

Due to this problem in coating the phosphor film, studies have recently been underway on penetration-based cathode ray tubes in which the phosphor is subjected to special processing so that the phosphor can explode by coating only one layer. For example, using two types of fluorophores, one fluorophore can be
Only the surface layer of the phosphor particles is a phosphor that emits red light,
Another phosphor is a green phosphor whose surface layer is ridged with a non-emissive layer. When a mixture of these two types of phosphors is irradiated with an electron beam at a low accelerating voltage, red light emission, in which the human face layer is active, becomes the main light emission. When the accelerating voltage is further increased, the light emitted from the deep part of the phosphor, that is, the green light becomes the main light emitted, and a penetration cathode ray tube is realized. It is obvious that this method has a great advantage in manufacturing cathode ray tubes because the phosphor layer is one layer, but the two types of phosphors each require special processing, and the two types of phosphors Because it is a physical mixture of , it cannot avoid the drawbacks such as uneven spatial distribution.

The present inventors have attempted to overcome the manufacturing difficulties of the two-layer fluorescent film coating process as described above, or the disadvantages of coating film roughness due to the physical mixing of two types of particles. Various efforts have been made to realize a phosphor with a multilayer structure. Conventionally, calcium sulfide phosphors are known to emit green and red (highly efficient) light by introducing Cel or Eu, respectively.It is also well known that alkali metals can be introduced as co-activators. It is.

The inventors have developed a calcium sulfide phosphor co-activated with Ce and Eu (by containing Ni-alkaline phosphor), Eu
The present invention was achieved as a result of various studies focusing on the fact that the light emission caused by this phenomenon can be suppressed.

[Purpose of the invention]

This invention provides a phosphor that can realize multicolor luminescence in a single particle C2 by incorporating Co, nu, and an alkali metal into calcium sulfide.

[Summary of the invention]

The phosphor according to this invention includes Ce, Eu and alkali 9T.
It is a calcium sulfide phosphor containing the t-genus, and has the effect of being able to vary the color of emitted light depending on the accelerating voltage during cathode ray excitation.

FIG. 1 shows an example of a phosphor according to the present invention, in which Li is 0.0.
FIG. 2 is a diagram showing the emission spectrum of a Cab:Ce, Flu, Ll phosphor containing 0.002 mol by cathode ray excitation. The horizontal axis of the figure represents the emission wavelength in 7 meters, and the vertical axis represents the relative emission intensity. In the figure, curve 1 is the emission spectrum when the accelerating voltage for cathode ray excitation is 3 KV, and curve 2 is the emission spectrum when the accelerating voltage is 20 KV. As shown in the figure (the change of luminescent color with two accelerating voltages is obvious. C, 1, E of curve 1 and curve 2, the chromaticity values are respectively X = 0.681. Y = 0.842
and X = 0.221, Y = 0.668. These changes in luminescent color (chromaticity value) are continuously variable depending on the accelerating voltage, and luminescent colors from red to green can be realized by changing the accelerating voltage of the cathode ray.

The content of Li that brings about this effect is preferably 10-5 to 10-1 mole per mole of calcium sulfide matrix.

When Li is less than this range, almost no light is emitted. If the amount is too high, only green light will be emitted and red light will be almost weak.

From the viewpoint of luminous efficiency, it is desirable to contain 10 to 10 moles of Ll per 21 moles of calcium sulfide.

In addition to Ll, the alkali 9Tt genus that produces this effect includes Na and K. For example, Fig. 2 shows the changes in C, 1, E, and chromaticity values of CaS:Ce containing 0.001 mol of Na, when irradiated with electron beams of 3 Kv and 20 KV. , point 1 has an accelerating voltage of 8 Kv (Cab excited from two: Ce, gu, N
a phosphor C, L E, chromaticity value TE, mata, point 2 is 2
C, I, IV, and chromaticity are 1 m when excited with an accelerating voltage of 0'v. The variability of the emission color due to the pressure change (2) due to the acceleration of the electron beam is obvious.
C, 1, E, chromaticity values when 0 mushrooms are irradiated with electron beam are 3rd
In the figure, point 1 is the C,1,E, chromaticity value of the C a S e Ce, Bu + K phosphor excited from the accelerating voltage of 8 KV (2), and point 2 is the chromaticity value of the C a S e Ce, Bu + K phosphor excited from the accelerating voltage of 8 KV (2 C, 1, El is the chromaticity value for the case.As shown in the figure, the variability of the emitted light color due to the acceleration voltage liquefaction of the two-electron beam is obvious.

The content of Na and K is 1 mole of calcium sulfide (2 to 1
0 to 10 moles is good.

As described above, the calcium sulfide phosphor containing Ce, Eu, and alkali metals according to the present invention can be produced by changing the accelerating voltage under cathode ray excitation. It is the body.

[Embodiments of the invention]

The present invention will be explained below with reference to Examples.

Example (1) CaCO31%/l/ containing 0.01% mol of Ce and 0.05% mol of Ey and Lt, Co, 0.01
%/l/ and 2 moles of sulfur by physical means: more thoroughly (;; after mixing in a reducing atmosphere (two times % 1200 t
Bake for 3 hours at l'. This first fired product is thoroughly washed with pure water and dried. 2L of NH, C-e for 1oo 1i' of dry raw material! - and sulfur were added at 20 F and physically mixed, then heated again at 900 F in a reducing atmosphere.
Ca S whose L1 content is 0.002 mol per 1 mol of calcium sulfide when fired for 20 minutes at t:':
A Car Eu, Ll fluorophore was obtained.

This phosphor has a current density xrf'A/'c! ! C0I, E, and chromaticity values are shown in Table 1 (2) when excited with an electron beam of 1 and acceleration voltages of 3 KV and 20 KV.

Example (2) CaC containing 0.01% mol of Ce and 0.05 thymol Eu, 0.1%/L/ and NatCOs o,o
After thoroughly mixing 2 moles of sulfur and 2 moles of sulfur by physical means, the mixture is calcined at 1100 C for 8 hours in a reducing atmosphere. Thoroughly wash this first fired product with pure water,
dry. NH,C for 1005'l of dried raw material
2y- for J and 20 for sulfur? After addition and physical mixing, calcining was performed at 900 C for 20 minutes in a reducing atmosphere (at 900° C.).
001 mol of CaS:Ce, Fiu, Na phosphor was obtained. Table 1 shows the C, 1, & chromaticity values when this phosphor was excited with an electron beam at a current density of 10 μ and the accelerating voltage was SKY and 20 KV.

Example (flm) 0.1 mol of CaC containing 0.01 mol of Ce and 0.05% mol of Bu was thoroughly mixed with 0.05 mol of Co and 2 mol of sulfur by physical means.
Calcinate in a reducing atmosphere (second time at 1200 C for 8 hours). This first fired product is thoroughly washed with pure water (second time) and dried.

2y- of NH, CJ for the dried raw material 1009-
and 20 sulfur? After addition and physical mixing, calcining for 20 minutes at 900C in a reducing atmosphere again yields a Cab:Ce, Eu, K phosphor with a K content of 1 mol of calcium sulfide (0.0015 mol for 2). When this phosphor was excited with an electron beam at a current density of 10 1/cnt and the accelerating voltages were 3 KV and 20 KV (7) C, 1,
&The chromaticity values are shown in Table 1.

Table 1 [Effects of the Invention] As described above, the calcium sulfide phosphor containing E Ce, Ru, and an alkali metal has the characteristic that the acceleration voltage can be changed under cathode ray excitation (secondarily, the emission color can be varied; It is suitable for use as a phosphor for penetration cathode ray tubes.

[Brief explanation of the drawing]

FIG. 1 shows the CaS:Ca, Eu, Ll phosphor of the present invention at accelerating voltages of 5KY (curve 1) and 20KVC curve 2.
Figure 2 shows the emission spectrum diagram of the Cab:Ce, Eu, Na phosphor of the present invention when excited with an electron beam at an acceleration voltage of 3KY (point 1) and 20KV (point 2). The C, 1, E, chromaticity diagram of the luminescent colors, Fig. 8 shows the CaS:Ce, 11Xu, K phosphor of the present invention by electron beam excitation at an accelerating voltage of 8KY (point 1) and 20Kv (point 2). C,1,Fi of emitted light color. It is a chromaticity diagram. Representative Patent Attorney Kensuke Chika (and 1 other person) No. 1
Figure 3 "[' ・1 0.6 ・/

Claims (2)

[Claims] (1) A calcium sulfide phosphor represented by the general formula CaS:Ce, Eu, X, in which the alkali metal X is at least one of Li, Na, and K. (2) The phosphor according to claim 1, wherein the content of alkali metal X is 10^-^5 to 10^-^1 mole per mole of calcium sulfide.