JPH0474818B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a shadow mask installed in a color cathode ray tube, and more particularly to a slot mask having rectangular pores through which electron beams pass. FIG. 1 is a partially cutaway side view of a conventional color cathode ray tube. In this figure, reference numeral 1 denotes a glass bulb. A fluorescent film 2 is formed on the inner surface of a panel portion 1a of the glass bulb 1, and an electron gun 3 is enclosed within a neck portion 1b. A deflection yoke 4 deflects the electron beam emitted from the electron gun 3, and is provided on the outer periphery of the neck portion 1b on the funnel portion 1c side. Reference numeral 5 denotes a slot mask disposed opposite to the fluorescent film 2. A peripheral skirt portion of the slot mask 5 is supported by a mask frame 6, and the mask frame 6 is supported by a spring clip 7.
It is supported by a panel pin 8 provided on the inner surface of the skirt portion of the panel portion 1a. As shown in FIG. 2, the slot mask 5 has a large number of rectangular pores 9 through which the electron beam passes. In FIG. 2, X and Y are the mask horizontal and vertical axes. 3 shows a partially enlarged view of the slot mask 5, FIG. 4 shows a sectional view taken along the line AA in FIG. 3, and FIG. 5 shows a sectional view taken along the line BB in FIG. 3. Fourth
As can be seen from FIG. 5, the opening 9a of the pore 9 on the fluorescent film side is larger than the opening 9b on the electron gun side. This is to ensure that the electron beam is properly irradiated onto the fluorescent film without being blocked, regardless of the deflection angle of the electron beam. 3 and 5, 10 is a vertical bridge between the pores 9 and 9;
In FIG. 4, 11 is a horizontal bridge between the pores 9, 9. In the above configuration, the minimum opening width of the pore 9 is D
(Fig. 3, Fig. 4), and the vertical bridge width is W (Fig. 3, Fig. 4).
(Fig. 5), normally D=0.150~0.20mm, W
= 0.08 to 0.130 mm, and its dimensions are either constant over the entire slot mask, or, in the case of a 14-inch slot mask, have a slight grade to suppress landing errors at the periphery, as shown in Table 1. (For example, Japanese Patent Application Laid-Open No. 1983-
Publication No. 99760, Japanese Unexamined Patent Publication No. 118956/1983, Koiaki Jitsue
53-49331, Utility Model Publication No. 54-3639).

[Table] The slot mask 5 is press-molded to have a predetermined spherical surface, and is supported at a predetermined position inside the glass bulb 1 via a mask frame 6, spring clips 7, and panel pins 8, as shown in FIG. Conventionally, the glass bulb has had the following drawbacks not only during press molding but also after being installed inside the glass bulb 1. That is, due to the characteristics of press molding, the amount of elongation at the periphery of the slot mask 5 is larger than that at the center, and this is particularly noticeable at the outermost periphery at both ends of the mask horizontal axis X (FIG. 2). In order to suppress landing errors in the peripheral area,
Even if the minimum opening width at the periphery is slightly narrower than that at the center to give it a grade,
A crack occurs in the vertical bridge 10 (Fig. 3) of this part, and as a result, the minimum opening width D (Fig. 3) of the pore 9 is abnormally enlarged, leading to a reduction in material yield due to poor pressing. It was dangerous. For example, as shown in FIG. 7, the minimum opening width after pressing has an elongation at its outermost circumference that is more than five times that of the third and fourth rows. This is difficult to solve by adjusting the mold during pressing, and is an extremely difficult technique. Furthermore, when the completed slot mask 5 is engaged with the panel pin 8 and installed inside the glass bulb 1 through various processes, the slot mask 5, which is formed into a predetermined spherical surface, loses its shape due to various impacts during the process. It was not possible to retain the color sufficiently, which caused color shift, especially at the periphery of the color cathode ray tube screen. This invention solves the above-mentioned drawbacks and eliminates pressing defects and
The purpose of the present invention is to provide a slot mask for a color cathode ray tube with less color shift. Hereinafter, an embodiment of the present invention will be described based on FIG. 6. FIG. 6 is a partially cutaway front view of a slot mask 5 for a color cathode ray tube according to an embodiment of the present invention. In this figure, parts corresponding to those shown in FIG. 3 are given the same reference numerals.
In FIG. 6, the vertical bridge width W2 from the mask horizontal axis X end of the slot mask 5 to the second row from the outermost periphery of the perforated portion is increased relative to the vertical bridge width W1 in the direction of the center of the adjacent mask, and the pores 9 are The minimum opening width D2 was reduced by 5μ from the same D1, and a 14-inch slot mask was constructed with dimensions as shown in Table 2.

[Table] In this slot mask 5, there is no cracking of the vertical bridge 10 during normal press molding, and the elongation of the minimum opening width D2 of the pore 9 is approximately the same as that of the peripheral area, and it is Also, there was little color shift around the screen, and sufficient spherical strength was obtained. FIGS. 8a, b, and c are graphs showing the state before and after pressing of the slot mask for a color cathode ray tube according to another embodiment of the present invention from the outermost periphery to the fourth row. A shows the state before and after pressing when the outermost periphery of the minimum opening width before pressing is made 5μ smaller than the second row from the outermost periphery. In this graph, the second to fourth columns have approximately the same minimum opening width. b is the outermost periphery of the minimum opening width before pressing, 10μ from the second row from the outermost periphery
The state before and after pressing is shown when the width is reduced. c is the minimum opening width before pressing, with the outermost periphery being 10 μ smaller than the third and fourth rows, and 2
The state before and after pressing is shown when the rows are made 5μ smaller than the third and fourth rows. From this result, as shown in Figure 8a, the minimum opening width before pressing and the minimum opening width after pressing, the outermost one is about three times that of the third or fourth row. This can be suppressed by elongation, and the difference in minimum opening width between the outermost periphery after pressing and the rows in its vicinity can be approximately 10 μm. This level of elongation prevents vertical bridging from breaking and can suppress color shift at the periphery of the screen to an inconspicuous level. Furthermore, in FIGS. 8b and 8c, the difference between the minimum opening widths between the outermost periphery after pressing and the other rows is smaller than that in FIG. 8a, and color shift in the peripheral area of the screen can be further reduced. However, the above-mentioned minimum opening width operation is performed 5 times from the outermost periphery.
If this is done beyond the rows, there is a problem in that the left and right edges of the screen on the color cathode ray tube become extremely dark, making the image difficult to see and reducing the product value. Based on the above experimental results, the present invention can change the minimum opening width D2 of the pores 9 from the outermost periphery of the perforation part at both ends of the horizontal axis By reducing the opening width D1 by 5μ or more, in other words, in order to suppress landing errors at the periphery, as shown in the conventional example above, the minimum opening width D at the periphery is reduced from that at the center. By narrowing the minimum opening width D2 of the 1st to 5th rows including at least the 1st row from the outermost periphery of the perforation, there is no cracking of the vertical bridge during molding. It has been found that the initial objective of suppressing landing errors can be achieved. As explained above, according to the present invention, pressing defects of the slot mask are prevented, so the material yield is greatly improved, and the strength of the peripheral area of the mask is increased, so the mask shape is sufficiently maintained and color shift is prevented. You can get an excellent color cathode ray tube with less color.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of a conventional color cathode ray tube, Fig. 2 is a simplified configuration diagram of a conventional slot mask, Fig. 3 is a partially enlarged view of a conventional slot mask, and Fig. 4 is a side view of Fig. 3. A sectional view, FIG. 5 is a BB sectional view in FIG. 3, FIG. 6 is a partial front view of a slot mask for a color cathode ray tube according to an embodiment of the present invention, and FIG. Figures 8a, b, and c are diagrams showing the conditions before and after press molding of a slot mask for a color cathode ray tube according to another embodiment of the present invention. 2... Fluorescent film, 3... Electron gun, 5... Slot mask, 9... Pore, 9a... Fluorescent film side opening,
9b...Electron gun side opening, D...Minimum opening width, W
... Vertical bridge width, X ... Mask horizontal axis. In addition,
In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. On the surface facing the fluorescent film formed on the inner surface of the panel portion of the glass bulb, there are a number of rectangular pores through which the electron beam passes, making the opening on the fluorescent film side larger than the opening on the electron gun side, and The minimum opening width of the pores is gradually decreased from the center of the mask toward the periphery, and the pores extend from the periphery of the opposing surface and are bent toward the side opposite to the phosphor screen. In a color cathode ray tube slot mask having a skirt portion, the minimum opening width of the pores located at the ends of the 1st to 5th rows including at least the 1st row from the outermost periphery of the perforations at both ends of the horizontal axis of the mask is defined as A slot mask for a color cathode ray tube, characterized in that the minimum opening width of the pores located at the ends of the mask is reduced by 5μ or more from the minimum opening width of the pores adjacent to the center of the mask.