JPH02172142A - Shadow mask structure - Google Patents

Abstract

PURPOSE:To lower dislocation of apertures by putting an aperture on another one, welding a pore having part and a pore-free part of a mask in a prescribed condition, and then press-molding into a prescribed shape. CONSTITUTION:Flat masks 21, 22 are so mounted on a positioning jig 27 that positioning pins 28 formed in the jig are inserted into positioning holes 25. The masks 21, 22 are pushed by a pressure jig 29 so as not to have a gap between the masks and to be pinched, and a laser with a beam diameter limited by a laser welding head is radiated to form a welded point 50 and weld. Welding is carried out successively so as to form two circular welded point groups A, B in a pore having part 23 and one circular welded point group C in a pore-free part 24 and to weld the masks 21, 22. The welded masks 21, 22 are formed into a shadow mask through press-molding process.

Description

[Detailed description of the invention]

(Field of Application of RM, L) This invention relates to a shadow mask structure for a shadow mask type color cathode ray tube. (Prior Art) A shadow mask type color P3 pole ray tube (hereinafter referred to as rCRTJ) has a funnel-shaped funnel (1) and a panel sealed to the open end of the funnel (1), as shown in Section 7v4. (2), a fluorescent screen (3) formed on the inner surface of the panel (2), a plurality of bins (4) provided on the side wall of the panel (2), and a fluorescent screen (3) arranged opposite to each other. shadow mask structure (5) supported on the bin (4).
). The shadow mask horizontal body (5) includes an electron beam (6A),
A perforated part (23) in which a large number of apertures (13) are formed for selectively passing +6Bl, (6C), and a non-perforated part (24) connected to the periphery of this (1 hole part) are connected to the panel (2).
) is formed into a spherical surface that is almost the same as the inner surface shape of , a frame (9) welded at predetermined intervals, and a bimetal (1o) welded to this frame (9) to compensate for thermal expansion of the shadow mask (7) that occurs during operation of the color picture tube. and a spring (11) which is welded to this bimetal (10) and engages with the pin (4) to hold the shadow mask (7) in a position facing the panel (2). ':lCl?' having the shadow mask structure (5) configured in this way. i' is electric gun (+2A), (120
), <12c), j:f) 19. The emitted letter beams (6A), (6B), and (6C) pass through the shadow mask (Moon's Birthday?' (+3)) and form red and green lights on the fluorescent screen (3). , 1!? The electrons collide with the phosphor to emit light. Usually, the total area of the apertures (13) of the shadow mask (7) is about 15% to 25% of the surface area of the shadow mask (7), and the electrons Most of the beam collides with the shadow mask (7) and heats the shadow mask (7).For example, the temperature of the shadow mask structure (5) of a 21-inch CRT is measured under the conditions of a high voltage of 28 Kv and a beam current of 1 mA. The results showed the temperature upper limit characteristics as shown in Figure 8. In other words, the shadow mask (7
) is the temperature at the center of the hole i during the first 5 minutes, as shown in characteristic curve (14) - L t? , the temperature rose to about 40℃ in 30 minutes, h! tL/ was saturated. On the other hand, the frame (5) with a large heat capacity of 7 t gradually reached its temperature limit as shown in the characteristic curve (15) and reached a saturated state in about - hours. The shadow mask (7) thermally expands due to this temperature upper limit, and as shown in FIGS.
Displaced to position C). For this reason, the aperture (13)
The electron beams (6A), (6B), (
The protruding point of the phosphor screen (3)--2 of 6C) moves toward the center of the face surface by a distance T, causing adjacent phosphors of other colors to emit light, causing color shift. This color shift phenomenon appears over the entire screen. When this movement 1jtT was measured on a 21-inch CR' in which the radius of the inner surface in the diagonal axis direction of the panel is 1350 mm, it was found that it was on the long axis (hereinafter referred to as E
0.05 to 0.08
Moved mm. Then, when the 4-degree field of the frame (9) approaches the saturation state, the frame (9) is displaced to the position of a small point (9^) in FIG. 10 due to thermal expansion. For this reason, the frame (9
) is the shadow mask (7) joined to (7B)
Displaced to the position. As a result, the position of the electric r beam that passes through the aperture (13) and impinges on the phosphor screen moves outward from the center point by a distance aS, which is opposite to the color shift phenomenon that appears at the beginning of CRT operation. Color shift occurs in the direction of . This latter color shift phenomenon continues to occur if the CRT continues to operate. Bimetal (+01
(Illustrated in Figure 7) is for correcting this color shift.
9-4 A due to the upper limit of the temperature of the frame (9),
In order to bring the shadow mask (7) closer to the panel (2), the frame (9) is displaced to the position ('18) shown in FIG. The latter color shift is corrected by shifting to the position (7B) shown in FIG. 10 so that the impact point of the electric r beam hits a predetermined phosphor Q-. However, in the conventional shadow mask structure (5). When a locally high-brightness screen is projected, it is difficult to expect a temperature rise in the bimetal (1G), so it has not been possible to correct color shift due to local thermal deformation of the shadow mask. To solve this problem, the Journal of the Television Society (+9
77, Vol. 31, No. 6, P46-52) [Theoretical Study on Local Doming Phenomenon of Shadow Masks], it has been shown that increasing the thickness of the shadow mask (7) is effective. Theoretically proven. However, the aperture (13) of the shadow mask (7) is generally manufactured by the etching method disclosed in, for example, Japanese Patent Publication No. 51-9264. According to this manufacturing method, the plate thickness t and the size S of the aperture (13)
There is a relationship between W and the following formula % formula %.
) is impossible to form. In order to improve the resolution of CRT, it is necessary to reduce the pitch of the 5 apertures (13);
), and for this purpose, it is necessary to reduce the thickness of the shadow mask (7). In this way, there is a contradictory relationship between increasing the thickness of the shadow mask (7) to prevent color shift due to thermal deformation and decreasing the size of the aperture (13) to increase resolution. In order to solve this problem, for example, JP-A-57-1
A method using a plurality of thin shadow masks produced by the shadow mask production method disclosed in Japanese Patent No. 38746 has been considered. The method for manufacturing this shadow mask is shown in FIG. 11(a),
As shown in (b), the non-porous part (24) around the perforated part (23) of two thin flat masks (21) and (22) is spot-welded (50) at appropriate intervals. Or, after seam welding (51) L, before press forming into a predetermined shape, aperture (13) due to slippage between the two shadow masks that occurs during press forming and variation in elongation.
As shown in Fig. 12 (bl), the aperture (13) is filled with, for example, polyamide resin (16), dried with hot air and cured to obtain sufficient strength. The shadow mask (7) shown in FIG. 12(d) was press-molded as shown in FIG. 12(C), and the filled resin (16) was then removed by chemical means.
It is intended to be used as is. [Problem to be solved by the invention] However, the shadow mask (7) produced by this method has
It is difficult to completely remove the hardened resin that has penetrated between the two thin plates (21) and (22), and this residual resin is cr? -r is heated during operation and gradually releases impure gas into the tube, shortening the lifespan of the CRT, and residual resin may fall into the tube due to vibrations during assembly and the vibrations of television set speakers. , there is a risk that the particles may adhere to the electron gun and generate sparks, damaging the CRT. In addition, since this shadow mask is made of two thin plates stacked on top of each other, after press molding, residual strain causes a rebound phenomenon, resulting in a large misalignment of the aperture (13). It wasn't something I could do. This invention was made in order to solve the above-mentioned problems, and is a shadow mask formed by joining a plurality of flat masks, which has a shadow mask with a small aperture misalignment. The purpose is to obtain a structure.

[Means to solve the problem]

In the shadow mask structure according to the present invention, a plurality of thin flat masks are brought into close contact with each other with their apertures aligned to form at least a double annular array of welding points within the perforated area. A shadow mask is provided in which the spherical surface part and the skirt part are formed by press molding after welding and joining the non-porous part on the outer periphery of the perforated part at an appropriate interval. [Function] Since the shadow mask of the present invention is made by joining together a plurality of thin flat masks, it can be formed to have a thickness sufficient to prevent color shift due to thermal deformation. Also, since each flat mask is thin, an aperture of the size necessary to obtain the desired resolution can be formed. Furthermore, before press forming, at least double annular welding point arrays are formed and joined in the perforated area, and the non-perforated area is welded and joined at appropriate intervals before press forming. Therefore, the positional deviation of each aperture can be made extremely small. [Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a plan view of the joined flat mask before press molding of this embodiment, FIG. 2 is a diagram showing a shadow mask formed by press molding this flat mask, and FIGS. 3 to 6
This figure is a diagram for explaining the bonding process of the flat mask shown in FIG. 1. Hereinafter, a 21-inch CRT will be explained as an example. First, the configuration of the flat mask will be explained. FIG. 5 is a partially enlarged cross-sectional view of the joined flat mask of this embodiment, showing the part to the welding point row on the left side X-axis -L when facing the direction of FIG. The flat mask on the side (22) is the flat mask on the electron gun side, the plate thickness is t+ = 0.25 mm, L20.20 mm, and the aperture (13) formed by chemical etching method is used.
The pitch 1) of a) and (13b) is 0.65 mm, and the cross-sectional shape has a width Sw of the narrowest part on the electric gun side of 150 mm.
, each dimension from the small line Q is b lf
3w+ is 160μm, 8w2 is 120um,
Owl is 160 μm, 01□ is 120 ALm,
Ows is 250 μm, Omm is 170 μm,
In order to eliminate variations in the electron beam passing area due to misalignment during bonding of the flat masks (211, +221), the width of the aperture (13a) is made wider than the aperture ++3bl. In this 21 inch CR”r, the center point is 0.
The dimension from to the end on the X axis is l 95mm, center point O
The distance from the end on the Y axis is 155 mm. (
24) Hapu! Hole portions (25) are positioning holes, which are provided at three locations in this example. Next, we will explain the flat mask bonding process.6 As shown in Figure 3, the flat mask (21>, 122) is positioned in the alignment bin (28) planted in the alignment jig (27). The hole (25) is inserted and placed 1η, and as shown in Fig. 4, a gap is created between the flat mask (211° (z2)) by pressing with a presser jig (29) at 4 kg/cm”. For example, 0.6 to 0
．． Y of 8 joules/pulse, pulse width of about 10m5ec
The AG laser is irradiated with a beam diameter of about 0.1 to 0.15 mm to form a welding point (50) as shown in FIG. 6 for welding. As shown in Figure 5, the size of this welding point is that the surface diameter 1- is approximately 0.3 mm, the diameter L48 of the welded portion is approximately 0.1 mm, and the flat mask (22)
The penetration depth of the melt was approximately 0.1 mm. By sequentially welding in this way, as shown in FIG. 2 flat masks +211. (22) is joined. Among these, the position to the annular welding point row is 130 mm from the center point of the perforated part (23) (which coincides with the tube axis when attached to Cr?T), and 130 mm on the Y axis. The r method is I 05 mm, the welding pitch 1) is 10 mm, and the welding point row [1] position is 175 mm along the X axis.
, Y-axis t・r method is 140 mm, welding pitch P is l O
The position of the welding point row C is 5 mm from the outer periphery of the T-hole (23), and the welding pitch [) is 10 mm. After this bonding process, the flat masks (211, +221) that were bonded without any gaps are formed into a shadow mask (7) shown in Fig. 2 through a normal press molding process. Shadow mask (7) 2
As a result of measuring the positional deviation of the two apertures (13a) and (13b), the maximum position was at the four corners of the perforated part (23) at X = 190 mm and Y = 150 mm.
The size was 10 μm, which was a value that could be used for practical purposes. Next, set the welding pitch P of each welding point row A, B, and C to 5 mm.
, aperture (13a) as 20mm. The results of measuring the maximum positional deviation amount of (+3b) were as shown in the table below. From this result, welding point pitch is smaller than 20mm.
It is desirable that the thickness be less than mm. In addition, in the above embodiment, the inside of the perforated part (23) is
10 is joined with the current welding point row A, 13, and the non-porous part (24
) is shown as an example in which the area is joined by some annular welding point rows C, but one or more annular welding point rows may be added to each of these examples, and each part may be spot welded as appropriate. You can. In addition, in Example 41, the position in of the innermost annular welding point row was set to about 2/3 of the dimension from the center point O to the outside line, but it may also be placed inside, and the center point 0 to I
It was effective within the perforated hole area outside of /3. In addition, in the above embodiment, the welding point array C formed in the non-porous region
to the welding point array formed in the perforated area,
Although the pitch is the same as B, it does not necessarily have to be the same pitch, and may be joined at an appropriate interval. Next, examples of experiments conducted to arrive at this invention will be described as comparative examples. (Comparative Example 1) Maximum amount of aperture deviation △ of a shadow mask (7) obtained by press-molding flat panels (21), +22) joined by applying only the annular welding point array C shown in Fig. 1 p is the four corners of the perforated portion (23), and its value was 150 μm. From this result, it is clear that the aperture misalignment that occurs when two joined flat masks are press-molded is determined not only by the difference in the length of the neutral line between the two flat masks, but also by the difference in the length of the neutral line between the two flat masks. This means that it varies greatly depending on the mechanical strength determined by the width of the bridge of the flat mask, etc. (Comparative Example 2) In addition to the annular welding point row C shown in Fig. 1, the flat panels (21) and (22) are press-formed by applying and joining an annular welding point row with a pitch of 5 welding points of 5 mm. The maximum positional deviation of the aperture of the shadow mask (7) obtained by
Similar to Comparative Example 1, these were generated at the four corners of the perforated portion (23), and the value was 55 μm, which was not practical. This invention was completed through a large number of experimental prototypes of the above-mentioned comparative examples. In addition, in the above embodiment, the side in which two flat panels are bonded and press-formed is explained, but a structure in which three or more thin flat panels are bonded may also be used, and the size of the aperture can be further reduced. It is possible to improve the resolution and the heat resistance characteristics. [Effects of the Invention] As described above, according to the present invention, a plurality of flat masks whose apertures are aligned and aligned are brought into close contact with each other to form at least a double annular array of welding points within the perforated area. Δ
, B are formed and joined, and the non-porous region is welded and joined at appropriate intervals, and then the first spherical part and the skirt part are formed by press molding. Because of this, the desired plate thickness has good heat resistance and the positional deviation of each aperture is small (
This has the effect of providing a shadow mask structure with good resolution.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a joined flat mask before press molding according to an embodiment of the present invention, FIG. 2 is a diagram showing the positional deviation of the aperture of the shadow mask of this embodiment, and FIGS. 3 to 6 is an explanatory diagram of the bonding process in this embodiment, and FIG. 7 is an explanatory diagram of the bonding process in this embodiment.
FIG. 8 is a temperature upper limit characteristic diagram of the shadow mask structure of this conventional example, and FIGS. 9 and 10 are parts for explaining color shift that occurs in this conventional example. The enlarged cross-sectional view, FIGS.
FIG. 2 is an explanatory diagram of a shadow mask forming method disclosed in Japanese Patent No. 138746. (5)...Shadow mask structure, (7)...Shadow mask, (+3a), (13b)...Aperture, (21), (22) -, -Flat mask, (
23)...Joining hole part, (24)...No hole part, (25)
...Positioning hole, (30)--Welding point, Δ, n, c
... Annular welding point array, 0 ... Center point of perforated part, 1)
...Welding pitch. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A shadow mask placed opposite the phosphor screen on the inner surface of the panel, a frame that holds the outer peripheral surface of this shadow mask fixed, and a shadow mask that is fixed to this frame to compensate for thermal expansion that occurs during operation. A shadow mask structure having a thermal correction mechanism for the purpose of The area of the perforated part of the flat mask is welded to form at least a double ring-shaped welding point array, and the area of the non-perforated part is further welded at appropriate intervals along the outer periphery of the perforated part. A shadow mask structure comprising a shadow mask which is press-molded into a predetermined shape after being bonded.