JPS62108424A - Manufacture of color picture tube - Google Patents

Abstract

PURPOSE:To prevent the manufacturing of a defective product whose fluorescent surface of graphite surface has a defect, by performing washing with a processing liquid which dissolves only a frit and a sintered material of the frit, so that the frit and the sintered material clinging to a panel are removed therefrom. CONSTITUTION:A shadow mask 7 is detached from a panel 1. The panel 1 is immersed in an aqueous solution 12 of 8% of nitric acid and subjected to ultrasonic washing in an ultrasonic washing vessel 13. After that, a fluorescent screen is manufactured. The liquid for the ultrasonic washing does not dissolve the panel 1 made of silicate glass but dissolves only a frit 10 of lead glass or the like so that the frit and a sintered material of the frit, which are clinging to the panel 2, are removed. A fluorescent surface and a graphite surface are thus prevented from becoming defective.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of manufacturing a color picture tube having a shadow mask.

[Technical size of the invention and its problems] Generally, a shadow mask type color picture tube is constructed as shown in FIG. It is composed of a funnel-shaped funnel 2 and a neck 3.

The inner surface of the panel 1 is provided with, for example, a striped phosphor screen 4 for red, green and blue respectively, while the net 3 is provided with red, green and blue screens arranged in a row along the horizontal axis of the panel 1. Also, a so-called in-line type electron gun 6 that emits three electron beams 5 corresponding to blue is built in. Further, a shadow mask 7 is disposed on the phosphor screen 4 and has a main surface with a large number of through holes that are adjacent to each other. The peripheral portion of the shadow mask 7 is supported and fixed by a mask frame 8, and the mask frame 8 is further engaged with a pin 9 embedded in the inner wall of the panel 1.

In such a color picture tube, the three electron beams 5 emitted from the electron gun 6 are polarized by a polarizer (not shown) placed outside near the funnel 2, and are polarized by a substantially rectangular panel. The colors are sorted through the holes in the shadow mask 7 so as to scan a rectangular range corresponding to 1, and the colors are projected onto the phosphor screen of each color in the correct manner to produce a color image.

Here, the effective amount of electron beams passing through the holes in the shadow mask 7 is less than 1/3 due to its structure, and the remaining electron beams impinge on the shadow mask 7 and are converted into thermal energy, sometimes exceeding 80 The shadow mask 7 is heated to about .degree.

The shadow mask 7 is generally formed from a thin plate with a thickness of 011 mm to 0.3 stripes made of so-called cold rolled steel whose main component is iron, which has a large coefficient of thermal expansion at 0 to 100° C. of 1.2×10 −5 /′C. The mask frame 8 supporting the periphery of the shadow mask 7 is also made of cold-rolled steel with a thickness of 1 mTn@t and subjected to a strong cross-sectional blackening treatment. Therefore, the heated shadow mask 7 easily undergoes thermal expansion, but the surrounding area
Since it is in contact with the mask frame 8 which has been blackened and has a large heat capacity, heat moves from the shadow mask 7 to the mask frame 8 by radiation and conduction, and the temperature around the shadow mask 7 becomes lower than that at the center. Therefore, a temperature difference is generated between the central portion and the peripheral portion of the shadow mask 7, and a so-called doming phenomenon occurs in which the central portion is relatively heated and expanded. As a result, the distance between the shadow mask 7 and the phosphor screen 4 changes, disturbing the accurate landing of the electron beam 5, and causing deterioration of color purity. This phenomenon is particularly noticeable in the early stages of operation of a color picture tube. Furthermore, when forming a locally high-luminance image, a local doming phenomenon also occurs in the shadow mask 7.

Many proposals have been made to improve the doming phenomenon of color picture tubes. For example, in Japanese Patent Application No. 148843/1984, the main surface of the shadow mask 5 is made of ceramic, crystalline solder glass, or lead boron. It has been proposed and put into practical use to prevent this doming phenomenon by forming a layer of a sintered body mainly composed of glass such as acid salt glass.

As shown in FIG. 4, a method of forming a layer of sintered body on the main surface of a shadow mask is as follows: The frit 10 sprayed on the shadow mask 7 is then sintered by spraying it onto the shadow mask 7 using the spray 11 (a), and then incorporating the shadow mask 7 into the panel 1 and firing the frit 10 sprayed on the shadow mask 7. Forms the layers of the body (mouth).

Then, it is sent to the next step, a phosphor screen forming step (c).

In addition to spray coating, various methods such as electrostatic spray electrophoresis have been proposed and put to practical use in the process of applying the frit to the shadow mask 5.

However, in the conventional color picture tube manufacturing method described above, the frit 10 adheres to the inner surface of the panel 1, and the frit 10 and the sintered body of the frit 10 are sent to the next step, a phosphor screen forming step. This is often the case.

The glass used for the panel 1 here is generally silicate glass, and the frit is made of glass that does not contain silicic acid, such as lead glass.

Therefore, if the frit 10 and the sintered body of the frit 10 are sent to the phosphor screen forming process with the frit 10 and the sintered body of the frit 10 still attached to the inner surface of the panel 1, cleaning with hydrofluoric acid or the like performed first in the phosphor screen forming process will cause Only the inner surface of the panel 1 melted and the frit 10 attached
The sintered body of the frit 10 remains in a slag state as shown in Fig. 5, and if a phosphor screen is formed in this state, a defective color picture tube with missing phosphor and graphite surfaces will be manufactured. There is a problem that the yield is reduced.

OBJECT OF THE INVENTION] The present invention has been made in response to the above-mentioned conventional situation, and it is possible to prevent the phosphor screen or graphite surface from missing due to the frit and the sintered body of the frit that are scattered from the shadow mask and adhered to the inner surface of the panel. It is an object of the present invention to provide a method for manufacturing color picture tubes that can prevent the production of defective products and improve yield.

[Summary of the Invention] That is, the method for manufacturing a color picture tube of the present invention includes a step of applying a sintering composition mainly composed of glass to the main surface of a shadow mask, and a step of applying a sintering composition containing glass as a main component to the main surface of a shadow mask. A step of firing the composition with the shadow mask incorporated so as to face the inner surface of the panel, and depositing a layer of a sintered body mainly composed of glass on the main surface, and after removing the shadow mask from the panel. , a step of dissolving and removing the sintered body or composition mainly composed of glass that has adhered to the inner surface of the panel up to the firing step by bringing it into contact with a treatment liquid that dissolves the glass, such as a solution containing nitric acid or acetic acid. By doing so, it is possible to prevent the production of defective products in which the phosphor screen or the graphite surface is missing, and to improve the yield.

[Embodiment of the Invention] Hereinafter, details of the method of the present invention will be explained with reference to the drawings for one embodiment.

FIG. 1 shows the steps of a method for manufacturing a color picture tube according to an embodiment of the method of the present invention. In the method of this embodiment, first, a frit 10 is dispersed in a certain kind of solvent in a shadow mask 7. After spraying with the spray 11, the shadow mask 7 is assembled into the panel 1 and the shadow mask 7 is removed.
The sprayed frit 10 is fired to form a layer of sintered body (B). Next, the shadow mask 7 is removed from the panel 1, and the panel 1 is immersed in, for example, an 8% nitric acid aqueous solution 12, and subjected to ultrasonic cleaning in an ultrasonic cleaning tank 13 (C), followed by a corresponding rephosphor screen forming process ( D).

That is, in the method of this embodiment described above, the panel 1 made of silicate glass is not melted, but the panel 1 is cleaned with a treatment liquid that dissolves only the frit 10 made of lead glass or the like.
Since the frit 10 attached to the panel 1 and the sintered body of the frit 10 are dissolved and removed, the frit 10 attached to the inner surface of the panel 1 is removed.
The sintered body of 0 and the frit 10 can prevent the phosphor screen and the graphite surface from being chipped.

In this example, ultrasonic cleaning was performed using an 8% nitric acid aqueous solution for the following reasons. The graph shown in FIG. 2 shows the difference in the solubility of the frit 10 due to the concentration of the nitric acid aqueous solution and the cleaning method. In the graph, the vertical axis shows the frit solubility, the horizontal axis shows time, and the solid lines S1, S2 are 8% each,
Showing the results of ultrasonic cleaning using a 15% concentration nitric acid aqueous solution, dotted lines T1, T2, and T3 indicate 8% and 8%, respectively.
The results are shown when spray cleaning was performed using 15% and 3% nitric acid aqueous solutions. As can be seen from this graph, the cleaning method using ultrasonic cleaning using an 8% concentration nitric acid aqueous solution has the shortest cleaning time and is efficient.

Further, in this example, a nitric acid aqueous solution was used as the treatment liquid, but the present invention is not limited to such an example. For example, an acetic acid solution that cannot dissolve the panel 1 made of silicate glass, Of course, any treatment liquid that dissolves only 10 may be used.

[Effects of the Invention] As described above, in the method for manufacturing a color picture tube of the present invention, the frit and the sintered body of the frit are cleaned with a treatment liquid that dissolves only the frit, and the frit and the sintered body of the frit attached to the panel are removed. Since it is removed by melting, it is possible to prevent the generation of defective products in which the phosphor screen or graphite surface is missing due to frits and frit sintered bodies that are scattered from the two shadow masks and adhered to the inner surface of the panel, thereby improving yield. be able to.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the steps of an embodiment of the method for manufacturing a color picture tube of the present invention, FIG. 2 is a graph showing differences in frit dissolution time due to differences in cleaning method and nitric acid aqueous solution concentration, and FIG. FIG. 4 is an explanatory diagram showing a conventional method of manufacturing a color picture tube; FIG. 5 is a longitudinal sectional view showing a frit and a panel to which a sintered body of the frit is attached. . 1... Panel 7... Shadow mask 10... Frit 11... Spray 12... ... Nitric acid aqueous solution 13 ... ... Ultrasonic cleaning tank Applicant: Toshiba Corporation Patent attorney Sa Suyama - [)11 [)11 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) The step of applying a sintering composition mainly composed of glass to the main surface of the shadow mask, and the step of applying the composition to the main surface of the shadow mask, and installing the shadow mask coated with this composition so as to face the inner surface of the panel. A process of firing the composition and depositing a layer of a sintered body mainly composed of glass on the main surface, and after removing the shadow mask from the panel, removing mainly the glass that had adhered to the inner surface of the panel by the firing process. A method for manufacturing a color picture tube, comprising the step of bringing a sintered body or a composition as a component into contact with a treatment liquid for dissolving the glass and dissolving and removing it.