JPS6152192B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a fluorescent film, and particularly to a method for forming a fluorescent film suitable for projection cathode ray tubes that require high brightness.

An example of a projection cathode ray tube will be explained with reference to FIG. 1. Reference numeral 1 denotes a concentric meniscus-shaped face plate, and a metal back film 2 in which a metal such as aluminum is formed by vapor deposition and a fluorescent film 3 are formed at the center of the convex spherical inner surface. The target 4 is formed by laminating the two layers.
Reference numeral 5 designates an end plate having a through hole 6 formed in the center and a neck portion 7 extending outward, and a concave spherical mirror 8 formed on the inner surface. 9 is a cylindrical member;
A face plate 1 and an end plate 5 are airtightly sealed on both end surfaces with a target 4 and a mirror 8 facing each other. Reference numeral 10 indicates an electron gun housed within the network portion 7 and supplying an electron beam to the target 4.

In operation of this cathode ray tube, first, an electron beam emitted from an electron gun 10 is scanned over a target 4 using a focusing/deflecting means (not shown) to draw an image. This image light is reflected and expanded by the mirror 8, transmitted through the face plate 1, and the spherical aberration corrector (not shown) placed in front of the face plate 1 corrects the spherical aberration caused by the mirror 8, and is placed further in front of the face plate 1. image on a screen (not shown).

In order to improve the brightness on the screen, the brightness on the target 4 needs to be several to several tens of times higher than that of the commonly used cathode ray tube for receiving television broadcasts, and it is necessary to operate at a high beam current. It was hot.

However, when the fluorescent film 3 was formed by a commonly used precipitation method, the following problems occurred and it could not be put to practical use.

That is, the commonly used precipitation method involves injecting a solution in which a phosphor is suspended in a potassium silicate solution (water glass) into a cushioning solution such as a barium nitrate solution, uniformly dispersing it, and allowing it to precipitate and become wet. After draining the supernatant liquid, it is dried and left to dry, but strong alkaline content remains in the fluorescent film 3, which corrodes the metal back layer 2 and reduces the brightness of the fluorescent film. Glass had the problem of film burnout during high beam current operation.

The present invention was proposed in view of the above problems, and
Provided is a method for forming a fluorescent film that improves brightness and reduces film burning.

That is, in the present invention, after a metal back layer is formed at a predetermined position on a face plate as a substrate, a mixture containing a phosphor and an electrolyte at a ratio of 0.001 to 0.1 g per 600 c.c. of pure water is formed on the metal back layer. A fluorescent film is formed by precipitating a fluorescent film with a liquid, and after drying this fluorescent film, spraying an atomized potassium silicate solution and firing it to improve the binding strength between the phosphors and with the metal back layer. A method is disclosed.

The mixed solution used in the phosphor precipitation step is prepared by dissolving an electrolyte in the range of 0.001 to 0.1 g in 600 c.c. of pure water, and then stirring the phosphor in the pure water. In addition to the case where the liquid is mixed with the phosphor, the electrolytic substance may be added in an amount within a predetermined range to the liquid in which the phosphor is stirred. Further, potassium silicate for improving binding strength is used in a concentration range of 0.1 to 3%, for example, a low concentration of about 1%.

Hereinafter, specific embodiments of the present invention will be applied to the target 4 of the cathode ray tube shown in FIG.
This will be explained from the diagram. First, the face plate (substrate)
A removable film 11, such as an ester resin material, is coated on the inner surface of the film 1, and a window 12 is formed by peeling off the portion where the target is to be formed, as shown in FIG. Then, as shown in FIG. 3, a metal back layer 13 is formed at least on the window 12 by vapor deposition. Next, the frame 14 is brought into close contact with the inner surface of the face plate 1. The inner surface area of face plate 1 is 175
cm ² and the area of the window 12 is 40 cm ² inside the frame 14.
As shown in Figure 4, add an electrolyte to 600 c.c. of pure water, such as aluminum nitrate [Al( _{NO 3} ) 3.9H ₂ O] 0.01
Inject a solution containing 1.6 g to 1.8 g of phosphor in 300 c.c. of pure water, then inject into solution A and let stand for about 5 hours to precipitate the phosphor. . After precipitation, the supernatant liquid is gently drained, the frame 14 is removed, and the wet phosphor is dried to form a phosphor film 15 on the metal back layer 13 as shown in FIG. Then, dilute the stock solution of potassium silicate (K ₂ SiO ₃ ) about 100 times with pure water to make an aqueous solution with a concentration of about 1%, atomize it by a spray method or an ultrasonic vibration method, and spray it onto the fluorescent film 15. wear. Thereafter, the film 11 is peeled off and the undesired portions of the metal back layer 13 and the fluorescent film 15 are removed by air blowing or the like, so that the metal back layer 13 and the fluorescent film 15 are formed in the center of the face plate 1, as shown in FIG. A target 16 is formed by sequentially laminating the following layers. Furthermore, the drying strength can be improved by baking this face plate at, for example, 400° C. for 20 minutes or more.

Since potassium silicate is not present when the phosphor is precipitated, there is no corrosion of the metal back layer 13, and by atomizing low concentration potassium silicate and spraying it onto the phosphor, potassium silicate is deposited into the phosphor. Aluminum silicate [Al ₂
(SiO ₂ ) ₃ ], which improves the binding strength between the phosphors and the binding strength to the metal back layer 13. Note that potassium nitrate produced at the same time is decomposed by firing, and remaining potassium can be removed by washing with water.

Therefore, during operation of the cathode ray tube, the metal back layer 13 is not corroded, the phosphor film 15 is electrically insulated, and deterioration in brightness can be prevented, and the binding between phosphor particles is improved, and the phosphor Since it is in close contact with the face plate 1 via the metal back layer 13, heat dissipation is good and brightness deterioration can be reduced even when continuously operated at a high beam current. Furthermore, by using potassium silicate at a low concentration, film burning can also be improved.

In the above examples, the appropriate amounts of the phosphor and aluminum nitrate are 6 to 8 mg/cm ² in terms of dry weight per unit area for the phosphor, and 0.001 g to 0.1 g of aluminum nitrate (600 c. of pure water). c. hit) was suitable. If the thickness of the phosphor film is less than 6 mg/cm ² , pinholes will occur in the phosphor film, and if it exceeds 8 mg/cm ² , the brightness will be saturated in the high beam current region. Furthermore, if the amount of aluminum nitrate was less than 0.001 g, the drying power was poor, and if it exceeded 0.1 g, the phosphor was not dispersed but condensed, making it impossible to form a uniform precipitate.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, a low concentration electrolytic substance may be injected into the stirring liquid of the phosphor to precipitate it. Further, the fluorescent film 15 may be formed not only on the metal back layer 13, but also directly on the face plate (substrate) 1, or on a metal substrate such as aluminum. Furthermore, it goes without saying that the present invention can be applied not only to projection type cathode ray tubes but also to ordinary cathode ray tubes for receiving television broadcasting images. Furthermore, aluminum salt can be used as the electrolyte.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an example of a projection type cathode ray tube, and FIGS. 2 to 6 are side sectional views of a face plate illustrating a method of forming the present invention applied to the target of the cathode ray tube shown in FIG. be. 1... Substrate (face plate), 13... Metal back layer, 15... Fluorescent film.

Claims (1)

[Claims] 1 Form a metal back layer at a predetermined position on the substrate,
Phosphor and pure water per 600 c.c. on this metal back layer
A fluorescent film is precipitated using a mixed solution containing an electrolyte in a proportion of 0.001 to 0.1 g, and after drying the precipitated fluorescent film, an atomized potassium silicate solution is sprayed to form a layer between the phosphors and the metal back layer. A method for forming a fluorescent film, characterized in that it is fired to improve its binding strength.