JPS60257039A - Producing method for cathode-ray tube phosphor screen - Google Patents

Abstract

PURPOSE:To form a phosphor screen which has an almost duplicated structure, by making a difference in the sedimentation velocity between two kinds of phosphors, so as to make the phosphor layer formed sedimentarily, to be unhomogeneous. CONSTITUTION:When two kinds of phosphors whose specific gravities are indicated as PA, PB and mean grain diameters are indicated as dA, dB, are mixed and laid in a sedimentation method, the sedimentation velocities of respective component phosphors are made to be different with each other, as (PA-1)dA<2>/ (PB-1)dB<2>>=3.0. In this way, a phosphor screen which has a phosphor layer of almost duplicated structure, can be formed relatively easily, and it becomes possible to produce a long-lived cathode-ray tube of high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a fluorescent surface of a cathode ray tube that reduces deterioration of luminous efficiency due to electron beams.

[Prior art]

FIG. 1 shows a schematic cross-sectional view of a fluorescent surface (7) of a cathode ray tube. Face plate 1) constituting the fluorescent surface (7)
A phosphor layer (2) is formed on the inside of the phosphor layer (2) by a method such as a precipitation method, and a high voltage electrode and a metal back film (3) as a light reflecting film are formed on the upper surface of the phosphor layer (7). I'm making it. In this state, the metal back film (
3) The phosphor layer (2) is heated by the energy of the electron beam (4) emitted from an electron gun (not shown) placed opposite to the inner surface of the side.
is excited, and a fluorescent surface emission output can be obtained.

Depending on the type and purpose of #R cathode ray tubes, such as projection type cathode ray tubes and cathode ray tubes for light sources, the energy of the electron beam (4) added to the fluorescent surface may be excessive. Normally, if the phosphor layer (2) is continuously excited with excessive energy for a long time, the luminous efficiency of the phosphor decreases. This is an irreversible reaction, and once the luminous efficiency of the phosphor has decreased, it does not return to its original level, and this phenomenon is called deterioration of the phosphor. Although there are still many aspects of the deterioration mechanism of phosphors that are not well understood, it is empirically known that deterioration progresses in proportion to the amount of charge of the electron beam (4) that excites the phosphor. There is. Further, even under the same conditions, the degree of deterioration varies depending on the type of phosphor. In other words, there are actually phosphors that are resistant to deterioration by electron beams and phosphors that are weakly resistant to deterioration by electron beams.

In FIG. 1, the electron beam (4) is
) When the phosphor particles pass through the metal back film (3), which is a vapor-deposited film, and enter the phosphor M (2), the phosphor particles in the part of the metal back film (3) are accelerated and powerful. However, the electron beam that hits phosphor particles located deeper than this consists of many scattered electrons and transmitted electrons, and the received electron beam energy decreases with depth. Therefore, deterioration of the phosphor progresses faster in the portion of the phosphor # (2) that is normally closer to the metal back film (3).

Based on the above-mentioned empirical knowledge of deterioration, a phosphor surface structure as shown in FIG. 2 has been proposed as a method of reducing the deterioration of the phosphor surface due to electron beams. That is, the phosphor surface (7) in this case has a phosphor layer with a two-spring structure, consisting of a phosphor layer (6) that is less likely to be degraded by electron beams and a phosphor layer (5) that is more likely to be degraded by electron beams. There is. Taking a green-emitting projection cathode ray tube as an example, (
La006: '['b (lanthanum oxy chloride: terbium) phosphor layer is very bright as a phosphor layer in 5), but has some drawbacks in electron beam degradation. Y3Al5O12:Tb(Y
AG (terbium) fluorescer is considered to be optimal. A Y3Al5O12:'I'b phosphor with less deterioration due to electron beams is placed on the metal back film (3) side of the phosphor surface (7), and a Y3Al5O12:'I'b phosphor with less deterioration due to electron beams is arranged to compensate for the brightness performance of this phosphor. La, OO6 with excellent brightness performance in areas where it is difficult to produce:
By disposing Tb, it is intended to compensate for the drawbacks of both while bringing out the advantages of both.

A method for actually forming a phosphor layer with such a two-spring structure on a phosphor surface will be explained with reference to FIG. First, as in (b),
After thoroughly cleaning the inner surface of the glass bulb (8), which serves as the vacuum envelope of the cathode ray tube, the inner surface 1'r, which constitutes a part of the glass bulb (8), and the face plate (on which the phosphor layer is formed) are removed. 1) Place the part face down and inject an electrolyte solution (9) such as barium acetate into the glass pulp (8) at a constant current. Next, as shown in (→), the phosphor 0
A first suspension liquid 0.0 in which η is well dispersed in an aqueous water glass solution is injected into the glass bulb (8) containing the electrolyte solution (9) of (a). After that, (c)
When left standing for a while, the phosphor 0υ, which is susceptible to electron beam deterioration, gradually settles and accumulates on the face plate (1) of the glass bulb (8),
) to carry out silicic acid polymerization. When the sedimentation is almost complete as shown in (e), gradually add the second suspension liquid α, which is a water glass aqueous solution containing a phosphor that does not easily deteriorate with electron beams, well dispersed in the glass bulb as shown in (e). (8) Inject inside. After that, as shown in (f), if you leave it for a while,
The phosphor (2), which is less susceptible to electron beam deterioration, gradually settles and deposits on the formed phosphor layer (5), which is more susceptible to electron beam deterioration. When the dispersion is discharged after the sedimentation is almost completed as shown in (G), a two-layer structure of fireflies as shown in Figure 2 is formed on the inner surface of the face plate (1) of the glass pulp (3), as shown in (G). A light layer can be formed.

Forming a phosphor layer with a two-layer structure by such a method requires a very long and complicated process. Since the Sanubvention solution for each layer is injected, there is a drawback that unevenness tends to occur in the first phosphor layer during this injection.

[Summary of the invention]

This invention was developed in view of the complexity of the process that occurs when forming a phosphor layer with a two-layer structure, and the problem that unevenness tends to occur on the phosphor surface. A fluorescent surface with almost a two-layer structure can be formed with almost the same amount of effort, and there is no unevenness at all! This provides a method for manufacturing GLL.

[Embodiments of the invention]

In this invention, when forming a two-layered phosphor layer, instead of depositing and coating each phosphor layer separately as in the conventional method,
Two types of phosphors are mixed from the beginning and applied by precipitation, and the sedimentation speed of both phosphors is differentiated to make the phosphor layer formed by precipitation non-uniform, resulting in a two-layer TM structure. The aim is to form a fluorescent surface close to . In the case of microparticles with an average particle size of several μm to 20 μm, such as fluorescent materials, the sedimentation velocity in a liquid is given by the formula 8TOKE8. That is, 18 η V: Sedimentation velocity p: Specific gravity of particles po: Specific gravity of liquid η:
Viscosity resistance of liquid g Acceleration of double force d: Particle size. Therefore, when two types of phosphors A and B are mixed and a fluorescent surface is coated by the sedimentation method, if the sedimentation speed V A I V B of each component phosphor is different, it will be non-uniform and 2
A phosphor layer can be formed close to the phosphor surface of the layered structure.

As for the specific method of forming a fluorescent surface, first, see Figure 4 (I).
), after thoroughly cleaning the inner surface of the glass bulb (8) that serves as the vacuum envelope of the cathode ray tube, a part of the glass bulb (8) is purchased and the face on which the phosphor layer is formed on the inner surface is purchased. Place the plate (1) face down and place the glass bulb (8)
A certain amount of an electrolyte solution (9) such as barium acetate is injected into the chamber. Next, (as shown in Q, the constant voltage of the A phosphor, which is a phosphor αη that easily causes electron beam deterioration, and the B phosphor, which is a phosphor that does not easily cause electron beam deterioration, 0) is set to a good value in an aqueous solution of water glass. The dispersed suspension liquid 0→ is injected into the glass bulb (8) containing the electrolyte solution of ψ). After that, as shown in @), when the two phosphors are allowed to stand still for a while, the two phosphors, which have different sedimentation speeds, gradually settle in a non-uniform state and are deposited on the face plate (1) of the glass bulb (8). 1) Perform silicic acid polymerization with.

As shown in (S), at the stage when the sedimentation is almost completely completed,
Even if the two phosphor layers are not completely separated,
The phosphor layer αQ, which has more electron beam deterioration, and the phosphor layer αQ, which has less electron beam deterioration, each change continuously for 2J.
It is formed in a state close to that of an ill-built structure. Thereafter, as shown in CI'), when the dispersion is discharged, phosphor layers Q and 0 having a nearly two-layer structure are formed on the inner surface of the glass bulb (8).

Also, how much difference should be given to the sedimentation speeds VA and VB of two types of phosphor particles to make the phosphor layer on the phosphor surface 2.
Experiments were conducted on a mixture of phosphors with various specific gravity and average particle size to determine whether the speed would be close to the N structure, and it was found that at least one of the phosphors should be made 8 times faster than the other.

In other words, Vmu/VB≧8.0, that is becomes.

〔Effect of the invention〕

As described above, according to the present invention, a phosphor surface having a phosphor layer close to a two-layer structure can be formed relatively easily, and this can be used to reduce deterioration of the phosphor due to electron beams. This makes it possible to manufacture a fluorescent surface using a simple manufacturing process that is not much different from conventional methods. As a result, it is possible to provide a cathode ray tube with a long life and high quality.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the fluorescent surface of a cathode ray tube, FIG. A) to (A) are two-layered structures (11-Figures explaining the method of actually forming the phosphor layer on the fluorescent surface, Figure 4 ψ) to al') are the two-layer structure according to the present invention. FIG. 3 is a diagram illustrating a method of forming a phosphor layer close to a phosphor surface. (1)...face plate, (2)...phosphor layer, (3)-9, metal back film, (4)...electron beam,
(5)...phosphor layer that is often degraded by electron beams, (6)...
Fluorescent layer with little electron gun deterioration, (7)...fluorescent surface, (
8)...Glass bulb, (11)...phosphor that is susceptible to electron beam deterioration, phosphor that is unlikely to undergo electron beam deterioration,
Q time...phosphor layer with less electron beam deterioration, 0...
・The phosphor layer is more susceptible to electron beam deterioration. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa

Claims (1)

[Claims] (]) When two types of fluorophores having a specific gravity of T)A, a pH of 1, and an average particle size of dA and dB are mixed and applied by a sedimentation method. A method for manufacturing the fluorescent surface of a cathode ray tube. (2) Fluorophore of (pA, (1*) and (pB * (i
Claim 1, characterized in that among the phosphors n), the phosphor (pB ldB ) is composed of a phosphor that is relatively less degraded by electron beam stimulation. A method of manufacturing a fluorescent surface for a cathode ray tube.