JPS61179036A - Manufacture of shadow mask - Google Patents

Abstract

PURPOSE:To prevent the distortion and the deformation of a shadow mask by applying powder consisting of heavy metal as a main component to the shadow mask from the large diameter portion side of an electron beam passing hole in the shadow mask by means of an electrostatic spray method, and forming a surface treated layer in the side on which an electron beam impinges. CONSTITUTION:A shadow mask 13 used in a color cathode ray tube is formed by providing a number of electron beam passing holes 15 which are a middle diameter portion 15b, a small diameter portion 15c and a large diameter portion 15a from the side on which an electron beam impinges, and treating its surface with black rust so as to prevent the distortion due to thermal expansion. At this time, in addition to the black rust, powder consisting of heavy metal as a main component which is charged is applied to the shadow mask with spray from the large diameter portion side of the passing holes 15 to form an electrostatic powder layer 5 in the entire surface. Next, the layer 5 in the large diameter portion side is scattered by an air gun and the like to leave the layer 5 from the small diameter portion 15c to the middle diameter portion 15b. Accordingly, it is possible to improve the heat radiation property to restrain the distortion generated even when the plate thickness of the shadow mask is thin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a shadow mask, which is a color selection electrode built into a color cathode ray tube.

[Conventional technology]

Regarding the manufacturing method of shadow masks for color cathode ray tubes, please refer to Sanpo Co., Ltd.'s Denshi Kagaku 1964 V o L
14/A9t pages 36 and 39-40
It is shown on page n.

By the way, as shown in Fig. 4, a cathode ray tube generally consists of a panel αq, which is a dish-shaped glass container, and a funnel-shaped funnel 0a, which houses an electron gun (111') that emits the entire electron beam. A shadow mask aj serving as a color selection electrode is interposed between the panel αq and the funnel αυ, and is held by a support portion 1 on the panel.

The shadow mask serving as the color selection electrode a3 is made of iron plate base α4 of 0.15 to 0.2511@ as shown in FIG.
In order to form an rc round or rectangular electron beam passage hole, the iron plate, which had a flat shape in the initial process, was heat-treated (heated to 700°C in a hydrogen atmosphere to prevent the inner surface of the panel αq from becoming spherical. 920℃) and then press processing, and then surface treatment 1 to obtain black rust on the surface.
It is manufactured by applying.

The process to obtain this black rust is called surface blackening.
). This treatment can be done by first completely degreasing the oil that adhered during press working, and then immersing it in alkaline molten salt to generate black rust, or by using steam or carbon dioxide gas to generate black rust. be. The black rust obtained by this process is a process used to prevent the formation of red rust due to oxidation of the shadow mask base Q4, which is heated at around 400°C in an air atmosphere during the process of manufacturing color cathode ray tubes. It is something.

On the other hand, when the color cathode ray tube is in operation, nearly 80% of the electron beam emitted from the electron gun αυ collides with the shadow mask α3, and the kinetic energy of the electron beam is converted into thermal energy. causes thermal expansion and distortion deformation. Making the above black rust reduces the emissivity to 0.
．． By making it about 75, it also serves to improve heat dissipation and reduce distortion caused by heat.

[Problem that the invention seeks to solve]

This black rust has an emissivity of about 0.75 for Fe3O4, and it is impossible to obtain a higher emissivity from the material of the shadow mask. However, with recent color cathode ray tubes, from the perspective of faithful reproduction of images, it is necessary to flatten the panel surface, increase the amount of information per unit screen, and make the image quality brighter and clearer. ing. To meet these demands, it is necessary to reduce the diameter and pitch of the electron beam passage hole, which determines the amount of information per unit surface area. The minimum value of the hole diameter based on processing technology is determined by the plate thickness of the shadow mask base α→.If the hole diameter is 0.150 m, the plate thickness will be as thin as approximately 0.1501 m. The rate at which the kinetic energy of the electron beam is converted into thermal energy depends on the thickness of the plate, so if the plate thickness becomes thinner, black rust as described above cannot be used as a preventive measure against distortion of the shadow mask. is insufficient.

〔problem? Means to solve]

A method for manufacturing a shadow mask according to the present invention includes providing a surface treatment layer on the surface of a shadow mask base to prevent thermal distortion caused by electron beam impact. That is, a surface treatment layer is formed on the substrate by spraying electrostatic powder from the large-diameter side of the electron beam passage hole.

[Effect]

In this invention, a layer of electrostatic powder is formed in addition to black rust on the surface of the shadow mask base, so that distortion is suppressed even when the plate thickness is reduced.

〔Example〕

FIG. 1 is a configuration diagram of a powder coating apparatus applied to the method of manufacturing a shadow mask according to the present invention.

In the figure, (1) is a spray gun for electrostatic powder coating. The spray gun (1) for the electrostatic powder (5) includes:
A powder supply pipe (2) and a high voltage conductor (4) supplied from a high voltage generator (3) are connected. (6) is a hanger for the shadow mask base α→, one end of which is grounded.

Next, a method for forming a surface treatment layer using the apparatus having the above configuration will be explained.

An oxide film of Fe3O4, which is black rust, has already been formed on the surface of the shadow mask substrate α, which is a color selection electrode, by a well-known manufacturing method. The illustration of this textured pattern is omitted. First, the shadow mask base (14) is coated by spraying the electrostatic powder (5) from the large diameter part (15a) of the electron beam passage hole αυ all around with the spray gun (1). That is, Spray gun (1) IC is a lead borate glass [M8F-13] sent by high pressure air.
07B: Pb0 (74.9wt%), B2O3 (8
,6wt%), Zn0 (12,6wt%), 8i02
(2, Owt%), BgO (1,9wt%), Co −
Fe-Mn 5pinel (1, Owt%)]
A high voltage generator (3) is applied to the powder (5) having a chemical composition of
More guidance or about 100! / is charged with electricity, and the large diameter part (
15a) Spray from side. The fine particles of static powder (5) discharged by the spray gun (1) are deposited on the surface of the shadow mask base cA4, as well as on the large diameter part (15a), as shown in Figure 2.
) The particles pass through the small diameter portion (15C) and the medium diameter portion (15b), and are deposited on the surface of the shadow mask base α fathom on the medium diameter portion (15b) side.

Next, move around the entire circumference of the air gun (not shown) to the large diameter part (15a) of the shadow mask base α◆.
The powder layer (5) on the surface from 5a) to the small diameter portion (15c) is completely scattered and removed as shown in Figure 113.

Next, the powder (5) is charged and deposited on the surface of the shadow mask base σ4)rc from the small diameter part (tSC) to the middle diameter ffl (15b), and the temperature is increased to 440°C.
Complete baking process at °C for about 30 minutes, Shadow Mask Q3
form. A color cathode ray tube is manufactured by using this shadow mask head to form picture elements that reproduce images.

Here, the electrostatic powder (5) is the shadow mask base α◆
Because it is spray-coated onto the surface of the plate, distortion caused by the slow energy of the electron beam is reliably prevented regardless of the plate thickness. Moreover, since the powder (5) is sprayed from the large diameter part (15a) side of the electron beam passage hole αQ,
The powder (5) directed from the small diameter part (15C) to the medium diameter part (15b) is 4% of the large diameter of the spray gun (1) (
(tea) It is deposited satisfactorily on the electron beam collision surface side, regardless of what is scattered by the electron beam. In this example, after applying the powder, the large diameter part (X6a) is
Powder (5) accumulated on the side and small diameter part (15c)
) is removed, the powder (5) can be entirely deposited only on the surface of the substrate σ that the electron beam collides with.

Of course, even if the powder (5) is left as is, it can contribute to the prevention of the above-mentioned distortion.

〔Effect of the invention〕

As described above, the present invention uses electrostatic spraying to apply electrostatic powder from the large-diameter side of the electron beam passage hole formed in the shadow mask base, so that even if the shadow mask base is thin, the electron It is possible to obtain a shadow mask that is free from distortion due to beam interlocking energy.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic configuration diagram of a powder coating device applied to a method for manufacturing a shadow mask according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a shadow mask substrate coated with powder. 3 is an enlarged sectional view of a portion of the shadow mask substrate before firing, FIG. 4 is a schematic configuration diagram of a color cathode ray tube, and FIG. 5 is an enlarged sectional view of a portion of a conventional shadow mask substrate. It is an enlarged sectional view. (1) is a spray gun, (3) is a high voltage generator, (5)
α4 is the powder, α4 is the shadow mask base, (G) is the electron beam passage hole, (X6a) is the large diameter part, (15b) is the medium diameter part, and (ISC) is the small diameter part.゛ In the figures, the same reference numerals indicate all the same or equivalent parts.

Claims (4)

[Claims] (1) A shadow mask as a color selection electrode with a large number of electron beam passage holes is constructed of a metal base and a surface treatment layer, and is divided into a medium diameter part, a small diameter part, and a large diameter part from the side where the electron beam collides. A method for manufacturing a shadow mask, characterized in that powder is applied to the substrate from the large diameter side of the electron beam passage hole by electrostatic spraying, and the applied layer constitutes the surface treatment layer. (2) The method for manufacturing a shadow mask according to claim 1, wherein the coating layer on the surface of the large diameter portion formed by spray coating using the electrostatic spray method is removed using air spray. (3) The method for manufacturing a shadow mask according to claim 1, wherein the powder spray-applied by the electrostatic spraying method contains heavy metals as a main component. (4) The method for manufacturing a shadow mask according to claim 1, wherein the powder sprayed by the electrostatic spraying method has a specific gravity of 6 or more.