JPS63211544A - Flat mask for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To make an effective screen nearly a rectangular shape and attain the design improvement by forming the effective contour line of a flat mask into a curved line shape recessed toward the center of the effective section in advance. CONSTITUTION:The contour line 4b having apertures of a flat mask 13 is formed into a so-called pin cushion type curved line shape recessed toward the center O of a section 4a having holes. If such a flat mask 13 is used, the shape of the contour line 4b is somewhat deformed to a barrel shape when it is press-molded, thus each side of the contour line 4b of a shadow mask 3 after it is formed can be made a straight line. Accordingly, the shape of an effective screen can be made nearly a rectangular shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement of a flat mask used in a color cathode ray tube, which is a state before formation of a shadow mask.

[Prior art]

FIG. 1 shows a sectional view of a panel portion of a shadow mask type color cathode ray tube.

In the figure, (1) is a glass panel that constitutes a part of the vacuum container, and is formed into an almost spherical shape with a convex curved surface facing outward.The inner surface of the panel is covered with a fluorescent layer (2). have. (3) is a shadow mask arranged at a predetermined distance from the fluorescent layer (2), and has a curved surface part (8a) and a skirt part (3b), and the curved surface part (3a) has many transparent parts. Holes (4) are formed in a regular array. In addition,
The shadow mask (3) is held inside the panel (1) by a holding mechanism (not shown).

In the above configuration, the fluorescent layer (2) is formed on the inner surface of the panel (1).
The area where the through holes (4) are formed is referred to as the perforated screen (2a), and the area where the through holes (4) are formed in the curved surface portion (3a) of the shadow mask (3) is referred to as the perforated portion (4a). Then, the effective screen (2a) forms a type of projection enlargement shape of the perforated portion (4a). That is, during the operation of the color cathode ray tube, the electron beam travels straight from a virtual point approximately called the deflection center, and as shown by the two-dot chain line in FIG. Perforated link line (4
The light passing through b) is arranged to form a fluorescent layer link line (2b) that borders the periphery of the effective screen (2a).

Ru. The curved surface portion (3a) and the skirt portion (3b) of the shadow mask (3) are integrally formed by press-molding a thin flat plate made of metal, generally referred to as a flat mask. FIG. 3 shows an example of such a flat mask. The flat mask α3 has a substantially rectangular perforated portion (4a) in which a large number of through holes (4) are regularly arranged, and the periphery of this perforated portion (4a) is formed by a perforated line. (4b) is formed. In addition, a non-porous portion (1ab) in which the through hole (4) is not provided is located at the periphery of the perforated portion (4a).
have.

When press-molding this flat mask (to) to obtain a shadow mask (3) shown in FIG.
It would be fine if the perforated link line (4b) of No. 3 becomes the perforated link line (4b) of the shadow mask (3), but in reality, it is possible to create a flat mask (to) by press molding.
Usually, the shapes of the two do not match perfectly due to the change in the plane of the shape to a curved surface and the elongation of the material during press molding.

By the way, recently, as shown in FIG. 4, the shape of the effective screen (2a), that is, the fluorescent layer link lines (2b
), but when observed from a sufficiently far distance from the front, a color cathode ray tube was created that had an almost perfect rectangular shape, with each side of the rectangle having almost perfect straight lines. In manufacturing such a color cathode ray tube, a flat mask in which each side of the perforated link wire is a straight line has conventionally been used.

However, when such a flat mask (to) is press-molded, as described above, the perforated link lines (4b) of the flat mask (6) and the perforated links (lines (4b) of the shadow mask (3) after press-molding are 4b), and as shown in FIG. (3)
In color cathode ray tubes using
2b) also does not have a perfect rectangular shape but has a barral shape, which impairs the design value.

[Purpose of the invention]

This invention was made in order to eliminate the above-mentioned drawbacks, and by making the perforated link lines of the flat mask into a curved shape concave toward the center of the perforated portion in advance, the shadow mask after forming is The idea is to make the perforated link lines straight and make the effective screen closer to a rectangle, thereby increasing the design several times.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 shows a flat mask according to an embodiment of the invention. As is clear from the figure, the perforated link wire (4
b) has a so-called bottle cushion-shaped curved shape that is concave toward the center O of the perforated portion (4a). If such a flat mask αj is used, when it is press-molded, the shape of the perforated link lines (4b) will be slightly deformed into a barrel shape, so that the perforated link lines of the shadow mask (3) after forming In (4b), each side can be a straight line.

However, as explained in Figure 1, the fluorescent layer link line (2
b) is the perforated link line (4b) of the shadow mask (3)
This is a kind of projection enlargement, but the inner shape of panel (1),
and curved parts of panel (1) and shadow mask (3) (
Generally, the shape of the perforated link line (4b) of the shadow mask (3) is not enlarged in a similar manner due to the distance between the shadow mask (3) and f3a).

Therefore, in order to make each side of the fluorescent layer link line (2b) of a completed color cathode ray tube a perfect straight line when viewed from a sufficiently far distance from the front, it is necessary to deform it by the above-mentioned projection enlargement. It is necessary to design a flat mask taking this into account. However, even considering the possibility of such deformation, the final fluorescent layer linkage line (
In order to make the shape of 2b) so that each side is a straight line when viewed from a distance from the front, it is preferable to make the perforated link line (4b) of the flat mask (toward) into a bottle cushion shape as described above. This has been experimentally confirmed.

Note that the flat mask (to) is symmetrical vertically and horizontally, so as shown in Figure 6, the longitudinal center line passing through the center O is the X axis, and passing through the center O is the X axis. Patented perforated link line (4b) featuring orthogonal center lines
The short side and long side of are expressed by the functions x=f(y) and y=g (x), respectively.

Now, considering only the quadrant where X≧0 and y≧0, the condition for the shape of the perforated link wire (4b) to be a bottle cushion shape is that y on the short side is O or around this. So, d2f / d y2) 0 For the short side, when X is O or around this, d2g /
It can be expressed as dx2>0.

In the above-mentioned embodiment, the perforated link wire (4b) is shaped like a pink john on both the short side and the long side, but either one may be symmetrical. When applied to the short side, the outermost row of through holes (4) should be arranged so that the outermost row of the through holes (4) on the short side draws an appropriate curve along the perforated link line (4b). ). In this case, at X-0, the through hole (4)
Since the arrangement direction of the through holes (4) should coincide with the y-axis, it is preferable that the arrangement of the through holes (4) approaches a straight line as one approaches the center 0 sequentially from the outermost row. The same can be said about the long side.

〔Effect of the invention〕

As described above, according to the present invention, at least one pair of opposing sides of the perforated linkage line of the flat mask has a curved shape concave toward the center of the perforated portion, so that the shadow mask after formation is The perforated link wire becomes straight,
As a result, the shape of the effective screen can be approximated to a rectangular shape, thereby making it possible to improve the design.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the panel portion of a shadow mask type color cathode ray tube, Figure 2 is a three-sided view of the shadow mask, Figure 3 is a front view of the flat mask, and Figure 4 is a diagram of the panel with a rectangular effective screen. A front view, FIG. 5 is a diagram showing the shape of perforated link lines after formation of a conventional flat mask, and FIG. 6 is a front view of a flat mask in an embodiment of the present invention. (4)...Through hole, (4a)...Perforated part, (4b)...
・・Perforated link wire, α [with] ・・Flat mask,
0...Center of the perforated part. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) In a flat mask before formation, which is made of a thin metal plate and has a substantially rectangular perforated part in which a large number of through holes are formed in a regular arrangement, a perforated link line that borders the periphery of the perforated part is formed. A flat mask for a color cathode ray tube, characterized in that at least one pair of opposing sides has a curved shape concave toward the center of a perforated part.