JPS5835860A - Crt for light source - Google Patents

Abstract

PURPOSE:To suppress the light output reduction of a light source CRT by using a blue luminous material with a large particle size to produce a phosphor screen. CONSTITUTION:The inner surface of a glass tube body 1 is washed with caustic soda, fluorine acid, then pure water. Next, an aqueous solution of barium acetate of 0.05% is injected. Furthermore, a suspension which a blue luminous material (ZnS:Ag) 3 with an average particle size of 16mu is dispersed at 8mg/cm<2> relative to the face area in water glass with a SiO2 density of 0.7% is injected, and it is left tranquil for 15-20min to allow a phospor 3 to precipitate. Next, after the phosphor 3 has precipitated, the supernatant fluid 11 is discharged by an inclination of the tube body 1, and the phosphor 3 is dried with the dehumidified air to complete its coating. A subsequent process is quite the same as the conventional method. The light output reduction of the blue luminous material (ZnS:Ag) with a large particle size thus coated as mentioned above is suppressed to about 30% in 1000hr compared with that of conventional ones.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube for a light source used in display devices and the like.

With the diversification of displays, various giant display devices have been developed. Nine methods suitable for color display and video reproduction include replacing each picture element of the three primary colors with a single cathode ray tube, using tens of thousands to hundreds of thousands of cathode ray tubes. Such a cathode ray tube is called a light source cathode ray tube, and can also be described as a light emitting element. An example of its structure is shown in FIG.

In the figure, a face portion (2) of a cylindrical glass tube body (1) is coated with one type of phosphor (3) that emits green, real or red light. The phosphor (3
) is coated with a vapor-deposited aluminum film (4) called a metal back, and is further coated with a graphite film (5) as an internal coating film for the purpose of electrical conduction. (6) is a fluorescent material <a) that emits electrons in response to a signal.
This is an electron gun for emitting light.

Next, the manufacturing method of such a cathode ray tube for light source is shown in Figure 2 (
, k) to (9).

First, the inner surface of the tube body a) on which the phosphor (3) is attached is cleaned using a hydrofluoric acid aqueous solution, a sodium hydroxide aqueous solution, and pure water. After that, for example, after injecting a predetermined amount of an aqueous solution of barium acetate as an electrolyte, a suspension of a predetermined phosphor (8) dispersed in an aqueous solution of water glass as an adhesive is injected, and the mixture is allowed to stand for a predetermined period of time. to precipitate the phosphor (3). After the phosphor (3) is precipitated, the tube body α) is tilted as shown in Fig. 2) to drain the supernatant liquid (II), dried with a dehumidifying air, and the phosphor (3) is deposited. ) completes the deposition.

Such a method is generally called a sedimentation method.

After the phosphor (3) has been deposited, the metal backing is performed, but since a continuous vapor-deposited film is not formed when the phosphor (3) is vapor-deposited with aluminum, it is called filming. After forming a very thin organic film on the light body (3), aluminum is vapor-deposited.

That is, first, the fluorescent surface is wetted with pure water, etc., and most of the fluorescent material (3) is covered with a water film (7) as shown in No. z@CB).
If you spray an organic solvent lacquer such as toluene or ethyl acetate whose main component is acrylic resin, a water film (7
) on which a very thin lacquer film (8) is formed. Next, remove the lacquer film (8) from unnecessary areas as shown in Figure 2 (
C) Removed by pure water Q□ flowing out from the nozzle (9) at a constant pressure as shown in K. This is because when the lacquer skin ME (8) is formed on the area where the phosphor (3) is not coated, the aluminum film deposited on this area will blister during the subsequent baking process. . Next, the fluorescent surface is dried using dehumidifying air or the like, and a graphite film (5) is applied to a predetermined area and dried in the same manner. Finally, aluminum is vapor-deposited to form an aluminum vapor-deposited film (4).
After forming the fluorescent surface, the organic material used in forming the fluorescent surface is decomposed and removed by baking at about 400° C. to complete the formation of the fluorescent surface.

An electron gun (
6) is welded and sealed, and then the inside of the tube body is evacuated to activate the electron gun (6), resulting in the finished product shown in FIG.

The phosphor of cathode ray tubes for light sources conventionally manufactured by this method is a silver-activated zinc sulfide phosphor, and the light output at this time is 113
As shown in Figure 11a, there is a decrease of about 60% in 1000 hours.

Now, suppose that a blue-emitting cathode ray tube is installed in a gigantic display device, but the light output of this blue light source cathode ray tube will decrease significantly over time compared to green and red ones. The balance of the reproduced colors becomes unbalanced. Naturally, an operation is performed to restore the original correct color tone, that is, the original light output. The method is an electron gun (
This increases the amount of electron irradiation from 6). In such a method, the light output decreases at an even faster rate due to the increase in the amount of stimulation, and eventually only the cathode ray tube for the blue light source from the color giant display device needs to be replaced at an early stage, i.e., compared to the conventional one. However, this cathode ray tube had the most important drawback as a light source: a decrease in light output.

The present invention has been made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a cathode ray tube for a light source with less reduction in optical output.

In other words, to summarize this invention, the particle size of the blue light emitter is increased to produce a fluorescent surface, thereby reducing the drop in light output of a cathode ray tube for a light source.The inventors have developed a cathode ray tube for a blue light source. The deterioration of the optical output of the cathode ray tube is due to its characteristics as a cathode ray tube, namely, that it is stimulated by the static beam of the scanning table at a relatively low accelerating voltage of about 8 KV, and that the temperature of the fluorescent surface decreases due to the high current density. As a result of various experiments on the characteristics of the silver-activated zinc sulfide phosphor as a fluorescent surface and its adhesion method, we finally decided to change the particle size of the phosphor from that of conventional ones. It has been found that the deterioration of optical output can be alleviated by making it extremely large. The average particle size of the conventional phosphor (3) was approximately 10μ, and the amount of coating was t.
Regarding isIIP/d, in the present invention, a value of about 20μ was good. However, depending on the yield of the manufacturing process and the quality of the finished tube, it is desirable that the coating amount be about 16 μm and the coating amount should be 811 F/d. Further, the effects of this invention can be explained as follows. In other words, in the case of this type of light source cathode ray tube used at relatively low voltage, the phosphor (
3) Since electron energy is consumed on the surface, the characteristics of the surface are important. On the other hand, as the particle size of the phosphor (3) increases, the crystallinity of the phosphor (3) and the characteristics near the p1 surface, which have fewer defects near the surface, become suitable for the usage conditions, resulting in a decrease in light output. It is thought that the situation will change for the better.

Hereinafter, one embodiment of the present invention will be described in detail.

Although the method for manufacturing the fluorescent surface is almost the same as the conventional method, it will be explained in more detail step by step with reference to FIG. First, the inner surface of the glass tube body (1) is cleaned using caustic soda, hydrofluoric acid, and pure water. Next, add an aqueous solution of barium acetate to 0
．． Inject it to 05% so that it groans. Further 810. A blue luminescent material (Zn8: mg) (3) with an average particle size of 16 μm is added to an aqueous solution of water glass, such as Orca Seal (manufactured by Tokyo Ohkatai), whose concentration is adjusted to 0.7%, relative to the face area.
Disperse 8wIg/d amount and inject nine suspensions for 15 to 20 minutes.
Let stand for a minute to precipitate the phosphor (3). This state is as shown in Figure 2). Next, after the phosphor (3) is precipitated, the supernatant liquid (b) is discharged by tilting the tube body (1) and dried with dehumidifying air to complete the deposition of the phosphor (3). . Below are the lacquer filling process and aluminum packing process.

The baking treatment process is exactly the same as the conventional method.
As shown in the curve in FIG. 3, the decrease in optical output of n8:mg) was reduced to about 30% in 1000 hours compared to the conventional one.

This example describes the sedimentation method for a cylindrical tube body (1) with a diameter of 1 inch, but it can also be applied to other deposition methods using a slurry liquid containing a photosensitive binder or simply a slurry liquid containing an organic binder. By using the phosphor according to the present invention, that is, the phosphor consisting of 13μ to 20μ Zn8:mug, it is possible to reduce the decrease in light output.

Of course, it can be used regardless of the size of the area of the fluorescent surface.

As described above, according to the cathode ray tube for light source according to the present invention, the decrease in the light output of the blue light emitter is reduced, and when used in a large color display, etc., the color balance of the image is not disrupted and the image is stable for a long time. It has excellent effects such as reducing the frequency of replacing defective pipes and reducing maintenance costs.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an example of a cathode ray tube for a light source, and Figure 2 (
G) to (C) are explanatory diagrams of a method of manufacturing a cathode ray tube for a light source, and FIG. 3 is a rounded characteristic diagram comparing the light output of a conventional cathode ray tube for a light source and a cathode ray tube for a light source according to the present invention. (1)...Pipe body, (2)...Face part, (3)
...phosphor layer, (6) ...electron gun. In the figures, the same reference numerals indicate the same or similar parts. Agent Makoto Kuzuno (1 other person) @Figure 2 (A)

Claims (1)

[Claims] (X> In a cathode ray tube for a light source, which has a fluorescent surface on at least the face of a glass tube body constituting a vacuum envelope and has an electron gun sealed inside, the actual color of the fluorescent surface A cathode ray tube for a light source, characterized in that the main component of the light emitting layer is silver-activated zinc sulfide light material, and the average particle diameter thereof is set to 13μ or more and 20μ or less.