JPH02230630A - Manufacture of fluorescent screen of cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent a fluorescent screen from being burnt even when reproducing letter display and still image for a long time, and not to generate the coloring of the fluorescent screen by applying alkaline non-crystalline colloidal silica solution, after forming a phosphor layer, and before forming a metal thin film. CONSTITUTION:To a panel 1 of a color image receiving tube, a green phosphor, a predetermined % of PVA aqueous solution, water, ammonium dichromate, a predetermined % of surface active agent aqueous solution, acrylic emulsion aqueous solution are determined by specific ratios, while a phosphor slurry is prepared as a suspended substance, so as to form a single-colored film of a green phosphor layer at a predetermined position, on which, for example, 5% of alkaline non-crystalline colloidal silica solution is applied, and after dried up, a silica coating film is formed. A thin film composed of an alkali resin is then formed by lacquer spray method, and an Al thin film is deposited and baked as a metal back, incinerating and removing the resin in the phosphor layer and an acrylic resin thereupon, so as to manufacture a color image receiving tube.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for forming a phosphor screen of a cathode ray tube.

(Prior Art) Generally, a color picture tube has a glass bulb 3 constructed by joining a funnel-shaped funnel 2 to a rectangular panel 1, as shown in FIG. A phosphor screen 4 is formed on the inner surface of the phosphor screen 4, which is composed of a striped or dot-shaped phosphor layer made of three-color phosphors of blue, green, and red, and a black light absorption layer that fills the gap between each phosphor layer. Further, a shadow mask 5 is disposed opposite to the phosphor screen 4, and has a large number of electron beam passage holes formed inside the shadow mask 5.

Inside the neck part 6 of the funnel 2, three electron beams 7 are arranged in parallel on the horizontal axis (long sleeve) of the panel 1-.
An electron gun 8 that emits .

When forming the phosphor screen 4 of such a color picture tube,
First, a light absorption layer of a predetermined shape is formed at a predetermined position on the inner surface of a glass panel 1, and then a photosensitive binder, such as a solution containing polyvinyl alcohol (PVA) and ammonium dichromate as main components, is added to a predetermined layer. A phosphor slurry in which phosphors are suspended is applied to the inner surface of the panel 1 and dried, and then exposed to light through a shadow mask 5 as a color selection electrode by an exposure device and developed to produce a black color. phosphor stripes or phosphor dots are formed at predetermined positions between the light absorption layers. This treatment is performed on three types of phosphor slurries: blue, green, and red, to form a phosphor layer on the inner surface of the panel 1.

Then, an organic film is formed on this phosphor layer by a lacquer spray method, etc., a thin film of aluminum is vapor-deposited as a metal back, and in step 2, the photosensitive binder and organic film are sintered by thermal decomposition. I'm leaving.

Incidentally, in recent years, with the proposal of high-definition color television systems, there has been an increase in the trend toward higher quality and higher definition of color picture tubes, and the use of color picture tubes has also increased to display text and still images. Ta.

That is, on the phosphor screen 4 of the color picture tube, for a long time,
Since a certain portion is always irradiated with the electron beam 7 and another portion is not irradiated with the electron beam 7 at all, there is a slight difference in the degree of phosphor screen burn between the two. This difference is difficult to discern under normal image display conditions, but when observed with the color picture tube switched off,
The electron beam irradiated area is colored browner than the non-irradiated area, resulting in poor appearance.

For example, without shadow mask 5, ZnS:CuAl
A 19-inch color picture tube with a phosphor screen 4 made only of phosphors was manufactured, and a television set was assembled using it.
Adjusted in the usual manner, the wind pattern 12 was formed in the screen 11 at an average current density of 1.35 μA, as shown in FIG.
/cd for 500 hours, and the characteristics before and after electron beam irradiation were checked at measurement point 13 in window pattern 12. Table 2 shows the results.

(See next page) Table 2 Body color was measured using a Minolta colorimeter CR-100 under the C light source, and the color difference was expressed in NBS units (N
alionxl Bgrexu of Standard
d).

(Problems to be Solved by the Invention) As mentioned above, in the conventional case, film burning (browning) phenomenon occurs on the fluorescent screen of cathode ray tubes such as color picture tubes.
Film burn (
(browning) phenomenon appears significantly, resulting in problems such as poor appearance.

The present invention was made in view of the above points, and is aimed at preventing film burning (
This is intended to improve the browning phenomenon.

[Structure of the invention]

(Means for Solving the Problems) The present invention involves applying a suspension of a phosphor containing a photosensitive resin to the inner surface of a panel, and forming a phosphor layer through exposure and development.
In a method for forming a phosphor screen of a cathode ray tube in which a metal thin film is formed on the phosphor layer and then the photosensitive resin is burned off, after the phosphor layer is formed and before the metal thin film is formed, alkaline Amorphous colloidal silica solution is applied.

(Function) In the method for forming a phosphor screen of a cathode ray tube of the present invention, when the photosensitive resin of the phosphor layer is burned off, the colloidal silica film having hydroxyl groups acts as a source of oxygen and hydrogen, and the photosensitive resin is This promotes the burning off of the plastic resin.

(Example) An example of the method for forming a phosphor screen of a cathode ray tube according to the present invention will be described.

In order to investigate the cause of the browning phenomenon of the phosphor screen, firstly, after 500 hours of continuous playback using the window pattern 12, the portions of the phosphor screen that were irradiated with the electron beam and those that were not irradiated were analyzed using X-ray photoelectron spectroscopy. The narrow spectra of carbon, carbon, and oxygen were compared in detail.

As a result, there is a difference in the carbon peak, and in the unirradiated area, C
-0 bond and C-C bond peaks were detected, while a C-C bond peak was detected in the irradiated area, indicating that the cause of browning is carbonization of organic matter remaining in the phosphor layer. I was able to guess what happened.

Therefore, when removing the resin in the phosphor layer by incineration, it was found that if the resin was sufficiently removed by incineration, the browning phenomenon could be improved. They came up with the idea of using an inorganic substance that can supply oxygen, hydrogen, etc., and invented the use of colloidal silicate particles.

That is, in general, in an alkaline solution, silanol groups on the surface of colloidal silica particles are bonded to hydroxide ions (OH-), as shown in FIG. A film obtained by applying this aqueous solution and drying it has the following properties.

First, water adsorption and desorption occurs reversibly up to a firing temperature of 150°C, and then, at temperatures between 150°C and 350°C, irreversible dehydration of water and silanol groups within the silica particles occurs.
Then, at 350''C to 750C, the silanol group continues to dehydrate and transforms into a siloxanoic acid bond.

Therefore, when the resin in the phosphor layer is burned, the colloidal silica film can act as a supply source of oxygen and hydrogen.

Next, specific examples will be described.

First, a phosphor slurry as a suspension of phosphor having the following composition is prepared.

Green phosphor 500g 8.5% PVA
Aqueous solution 426g water
5 8 7 g Ammonium dichromate 3 g 5% surfactant aqueous solution 30
a+1 acrylic emulsion aqueous solution 2 0 Gil
Next, the phosphor slurry having the above composition was applied to the panel 1 of a 19-inch color picture tube as shown in FIG.
A monochromatic film of a green phosphor layer was formed at a predetermined position using a conventional method.

Then add a 5% alkaline non-quality colloidal silica solution (for example, Ludo from Du POII1)
x AM diluted 6 times) was applied and dried to form a silica film.

After that, a thin film made of acrylic resin is formed using a lacquer spray method in the usual manner, and a thin film of aluminum is then deposited as a metal back, followed by firing to burn out the resin in the phosphor layer and the acrylic resin above it. I removed it and created a color picture tube.

In addition, as a comparative example, a color picture tube was manufactured using the same method without applying the colloidal silica solution.

Note that in both Examples and Comparative Examples, the shadow mask was removed in order to conduct a forced test.

In order to confirm the effects of the present invention, a television set was assembled using two types of color picture tubes, an example and a comparative example, and adjusted in the usual manner, as shown in FIG. The wind pattern 12 was continuously reproduced for 500 hours in the imager 11 at an average current density of 1.35 μA/ear, and the characteristics before and after electron beam irradiation were checked at 13 measurement points in the wind pattern 12. The results are shown in Table 1.

(See next page) As shown in Table 1 and above, it can be seen that the color picture tube according to the present invention has only a very slight difference in color, has almost no coloring, and has minimal reduction in brightness.

The particle size of the silica particles used in the present invention is preferably 20 mμ or less; if larger than this, the dead voltage value of the phosphor screen increases and brightness decreases.
Undesirable.

FIG. 2 is a graph showing how the brightness changes when the particle size of silica is changed and a 5% by weight aqueous solution is applied.

Moreover, the concentration of the coating liquid is preferably 0.05% by weight to 30% by weight. If it is less than 0.05% by weight, the desired film burn prevention effect cannot be obtained, and if it is more than 30% by weight, the dead voltage value increases and brightness decreases, which is not preferable.

FIGS. 3 and 4 are graphs showing changes in brightness when the concentration is changed using colloidal Siri force with an average particle size of 14 rnμ.

For reference, the following is a prior art technique for forming a silica film on a phosphor layer.

First, JP-A-51-100675 discloses a technique for forming a layer of a silane compound on a phosphor.

This technology prevents the water-soluble polymer from seeping into the phosphor layer by first forming a silane compound layer when forming the water-soluble polymer layer on the phosphor as an auxiliary layer for the metal back. This is to prevent

However, this technique not only has a different purpose than the present invention, but also uses a so-called silane coupling agent in the silane compound, so organic substances are present in the film, and the organic substances are removed to form a film on the phosphor screen. This is incompatible with the present invention, which aims to prevent burns, and as a matter of course, the effects of the present invention cannot be achieved.

Next, JP-A-56-141149 discloses a technique of coating silica particles on a phosphor.

This technique forms a layer of silica particles as a non-emissive layer in order to increase the dead voltage value of the phosphor screen.

Therefore, with this technique, brightness decreases, and the effect of the present invention, which prevents burnt film on the phosphor screen by removing organic substances, cannot be achieved.

〔Effect of the invention〕

As described above, according to the present invention, when forming a phosphor screen of a cathode ray tube, after forming a phosphor layer, an alkaline amorphous colloidal silica solution is applied, and a colloidal silica solution containing hydroxide ions is formed. When the photosensitive resin of the phosphor layer is burned off, the colloidal silica film acts as a source of oxygen and hydrogen, accelerates the burning of the photosensitive resin, and removes organic matter. can be sufficiently incinerated and removed, so even if characters or still images are played back for a long time, the phosphor screen will not burn out and the phosphor screen will not be colored.

[Brief explanation of the drawing]

Figure 1 is a structural diagram of colloidal silica particles used in the method for forming a phosphor screen of a cathode ray tube of the present invention, Figure 2 is a graph showing changes in brightness when the silica particle size is varied and the concentration is kept constant; Figures 3 and 4 are graphs showing the change in brightness when the silica particle size is constant and the concentration is changed, Figure 5 is a cross-sectional view of a color picture tube, and Figure 6 is a method for measuring phosphor screen burn. It is an explanatory diagram. 1. Panel, 4. Fluorescent screen.

Claims (1)

[Claims] (1) A suspension of phosphor containing a photosensitive resin is applied to the inner surface of the panel, exposed and developed to form a phosphor layer, and a thin metal film is formed on this phosphor layer. A method for forming a phosphor screen of a cathode ray tube in which a photosensitive resin is burned off, characterized in that after the phosphor layer is formed and before the metal thin film is formed, an alkaline amorphous colloidal silica solution is applied. A method for forming a phosphor screen in a cathode ray tube.