JP2002042676A - Shadow mask structural body and color cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shadow mask structural body capable of solving such problems that the tension of a shadow mask is increased due to the rise in temperature of the shadow mask structural body to approx. 60 deg.C when a color cathode-ray tube is used and the shadow mask is deformed from a cylindrical surface to a flat surface, and thus a Q value is increased, the displacement of landing of electron beams is caused, and the purity of color is lowered. SOLUTION: This shadow mask structural body 10 comprises a thermal expansion restricting material 13 connecting the long sides 11A of a mask frame additionally. To be more specific, an invar alloy tape is suitable for the thermal expansion restricting material 13. Since the increase in tension acting on the shadow mask 12 is less even if the short sides 11B of the mask frame are thermally expanded and the recess of the shadow mask 12 is reduced to one-several parts of a conventional one, the displacement of landing also becomes one-several parts to come into a value causing no problem in practical use. Thus, this color cathode-ray tube having the shadow mask structural body 10 mounted thereon does not cause lowering of the purity of color even if the temperature of the shadow mask structural body 10 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color CRT shadow mask structure and a color CRT mounting the same.

[0002]

2. Description of the Related Art In recent years, color CRTs having a flat glass panel surface have been increasing and are called flat color CRTs. However, even in a flat color CRT, the inner surface of the glass panel is not a flat surface but a part of a cylinder. The first reason is that if the thickness of the glass panel is uniform, the pressure resistance of the glass bulb is low and there is a risk of implosion, and the second is that if the thickness of the glass panel is uniform, the image is depressed. This is because it looks unnatural. The glass panel has a cylindrical concave lens shape with a thin center and thick periphery to prevent implosion and make the image look natural.

[0003] In order to keep the distance between the inner surface of the glass panel and the shadow mask (generally called the Q value) almost constant irrespective of location, the shadow mask is also made of glass corresponding to the fact that the inner surface of the glass panel forms part of a cylinder. It is made on a cylindrical surface with almost the same radius as the inner surface of the panel. FIG. 6 shows an example 50 of a conventional shadow mask structure for a 19-inch flat color CRT. The approximate dimensions are 360 mm long, 2 short.
70 mm and 43 mm in height. As shown in the figure, on the long side 51A end face of the mask frame 51 having a substantially rectangular frame shape,
The longer side 52A of the substantially rectangular shadow mask 52 is seam-welded (shaded). Mask frame long side 51A
Is elastically deformed inward, and the shadow mask long side 52
To weld A, a predetermined tension is always applied to the shadow mask 52 after welding. Since the long side 52A of the shadow mask is a circular arc and the short side 52B of the shadow mask is a straight line, the shadow mask 52 forms a part of a cylindrical surface as a whole. The shadow mask 52 and the mask frame long side 51A are made of Invar alloy, and the mask frame short side 5
1B is made of 13 chrome stainless steel. The reason why the mask frame long side 51A is made of an expensive Invar alloy is to prevent the shadow mask 52 from being distorted when the mask frame 51 thermally expands by making the thermal expansion coefficient of the shadow mask 52 and the mask frame long side 51A the same. .

[0004]

When a color CRT is used, more than half of the accelerated electron beam collides with the shadow mask 52, so that the shadow mask structure 50 is
Temperature rises to about ° C. Since the thermal expansion coefficient of the Invar alloy is about 1.2 ppm / ° C. and that of 13 chromium stainless steel is about 12 ppm / ° C., the short side of the mask frame 5
1B has a coefficient of thermal expansion approximately 10 times larger than that of the shadow mask 52. FIG. 7 shows that the shadow mask structure 50 has a temperature of 25 ° C. to 60 ° C.
4 schematically shows the shape change of the mask frame 51 and the shadow mask 52 when the temperature rises. In the figure, the solid line is 2
When the temperature is 5 ° C., the dotted line indicates the temperature at 60 ° C. As shown, the mask frame short side 51 which was like a solid line at 25 ° C.
When B is 60 ° C., thermal expansion is large as shown by a dotted line. As a result, the tension of the shadow mask 52 greatly increases from a predetermined tension, and the shadow mask 52 is deformed from a cylindrical surface (solid line) to approach a flat surface. As a result, the shadow mask 52 has a shape in which the center of the cylindrical surface is depressed as indicated by a dotted line, and the amount of the depression is about 100 μm at the center. That is, the Q value increases over the entire screen, and the maximum increase amount is 100% at the center of the screen.
μm. The landing deviation of the electron beam due to this depends on the location of the screen, but is about 20 μm at the largest location.
m. 20 μm because the phosphor pitch is 83 μm
The landing deviation of m is so large that the decrease in color purity cannot be ignored.

[0005] Landing deviation is caused by the short side 5 of the mask frame.
Since the thermal expansion of 1B is larger than that of the shadow mask 52, the landing deviation does not occur if the mask frame short side 51B is also made of Invar alloy. However, since the Invar alloy is expensive, this structure is
The cost of (1) rises, which is not desirable.

SUMMARY OF THE INVENTION An object of the present invention is to realize a shadow mask structure for preventing occurrence of a landing deviation while avoiding an increase in the cost of a mask frame. Another object of the present invention is to realize a color CRT having excellent color purity by mounting the above-mentioned shadow mask structure.

[0007]

SUMMARY OF THE INVENTION In order to solve the problems of the conventional shadow mask structure, a thermal expansion restricting material which connects the long sides of the mask frame is added to the shadow mask structure of the present invention. Specifically, an invar alloy tape is suitable as the thermal expansion regulating material. The thermal expansion restricting material is added immediately next to the short side of the shadow mask, or is added by removing a part of the non-porous portion on the short side of the shadow mask. The latter is particularly easy to weld and space efficient. Since the shadow mask structure of the present invention has a thermal expansion restricting material, even if the short side of the mask frame thermally expands, the increase in tension acting on the shadow mask is considerably smaller than that of the conventional shadow mask structure. As a result, the recess of the shadow mask is reduced to a fraction of the conventional size, so that the landing deviation is reduced to a fraction and the size is not a problem in practical use. As a result, in a color cathode ray tube equipped with the shadow mask structure of the present invention, a decrease in color purity is not visually recognized even when the temperature of the shadow mask structure increases.

According to a first aspect of the present invention, there is provided a shadow mask structure comprising a substantially rectangular frame-shaped mask frame and a substantially rectangular shadow mask having a pair of long sides stretched over the mask frame. A shadow mask structure comprising a thermal expansion restricting material connecting the long sides of the shadow mask.

According to a second aspect of the present invention, in the shadow mask structure of the first aspect, the thermal expansion restricting material is provided at a position of a non-porous portion on the short side of the shadow mask. It is a structure.

According to a third aspect of the present invention, in the shadow mask structure according to the first or second aspect, the coefficient of thermal expansion of the thermal expansion regulating material is substantially the same as the coefficient of thermal expansion of the shadow mask. It is a shadow mask structure.

According to a fourth aspect of the present invention, there is provided the shadow mask structure according to the third aspect, wherein the shadow mask and the thermal expansion regulating material are made of an Invar alloy.

According to a fifth aspect of the present invention, there is provided a shadow mask structure comprising a substantially rectangular frame-shaped mask frame and a substantially rectangular shadow mask, wherein a pair of mask supports are provided on long sides of the mask frame. A shadow mask structure comprising: a long side stretched over the mask support; and a thermal expansion restricting material that connects the pair of long sides of the mask frame or the pair of mask supports.

According to a sixth aspect of the present invention, in the shadow mask structure according to the fifth aspect, the thermal expansion restricting material is provided at a position of a non-porous portion on the short side of the shadow mask. It is a structure.

According to a seventh aspect of the present invention, in the shadow mask structure according to the fifth or sixth aspect, the thermal expansion coefficient of the thermal expansion restricting material, the thermal expansion coefficient of the shadow mask, and the thermal expansion coefficient of the mask support are different. This is a shadow mask structure characterized by being substantially the same.

According to an eighth aspect of the invention, there is provided the shadow mask structure according to the seventh aspect, wherein the shadow mask, the thermal expansion restricting material, and the mask support are made of an Invar alloy. .

According to a ninth aspect of the present invention, there is provided a color cathode ray tube on which the shadow mask structure according to any one of the first to eighth aspects is mounted.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a shadow mask structure according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a first embodiment 10 of the shadow mask structure of the present invention. The first embodiment 10 of the shadow mask structure of the present invention is for a 19-inch flat color cathode-ray tube, and its approximate dimension is 360 m long.
m, short side is 270 mm, and height is 43 mm. As shown, the long side 12A of the substantially rectangular shadow mask 12 is fixed to the end face of the long side 11A of the substantially rectangular frame-shaped mask frame 11 by seam welding (shaded portion). Since the shadow mask long side 12A is welded while the mask frame long side 11A is elastically deformed inward, a predetermined tension is always applied to the shadow mask 12 after welding. Since the long side 12A of the shadow mask is an arc and the short side 12B of the shadow mask is a straight line, the shadow mask 12 forms a part of a cylindrical surface as a whole. Shadow mask 1
Reference numeral 2 denotes an Invar alloy having a thickness of 100 μm, the long side 11A of the mask frame is made of an Invar alloy having a thickness of 2.2 mm, and the short side 11B of the mask frame is made of a 13 chrome stainless steel having a thickness of 2.2 mm. The feature of the first embodiment 10 of the shadow mask structure of the present invention is that the long side 11A of the mask frame is connected above the short side 11B of the mask frame and directly below the short side 12B of the shadow mask. At both ends (hatched portion). Invar alloy tape 13 measures 15 mm in width and 270 in length
mm and a thickness of 1 mm. The inside of the two-dot chain line 12C in the shadow mask 12 is a shadow mask perforated portion 12D,
The outside is the shadow mask non-porous portion 12E.

FIG. 2 shows that in the first embodiment 10 of the shadow mask structure of the present invention, the electron beam (not shown) collides with the shadow mask 12 to raise the temperature of the shadow mask structure 10 from 25 ° C. to 60 ° C. The shape change at the time is schematically shown. In the figure, the solid line indicates the case at 25 ° C., and the dotted line indicates the case at 60 ° C. Similar to the conventional shadow mask structure, the short side 11B of the mask frame tends to expand, but the shadow mask 1
The portion close to 2 hardly expands because the Invar alloy tape 13 restricts expansion of the short side 11B of the mask frame. For this reason, the central recess of the shadow mask 12 is about 1/3 of the conventional shadow mask structure, that is, 30 μm. That is, although the Q value increases in the entire screen, the maximum increase amount is 30 μm at the center of the screen. The landing deviation of the electron beam due to this varies depending on the location of the screen, but is about 8 μm at the largest location. The conventional landing deviation of 20 μm is such that the decrease in color purity cannot be ignored.
The landing deviation of 8 μm is not a problem because it is almost invisible. Accordingly, in the color cathode ray tube equipped with the shadow mask structure of the first embodiment 10 of the present invention, the color purity does not decrease even if the temperature of the shadow mask structure increases. That is, the same effect as when the short side 11B of the mask frame is made of Invar alloy can be obtained. Moreover, since the cost increase factor is only the Invar alloy tape 13, the cost increase is much less than when the short side 11B of the mask frame is made of Invar alloy, which is practical.

FIG. 3 is a perspective view of a shadow mask structure according to a second embodiment of the present invention. The difference from the first embodiment is that a part of the shadow mask non-porous portion 22E on the short side 22B side of the shadow mask 22 is removed, and the mask frame 2 is removed.
That is, both ends of the Invar alloy tape 23 are welded (hatched portions) so as to connect one long side 21A. This configuration facilitates the welding operation and has good space efficiency compared to the first embodiment. As in the first embodiment, the cost increase is small and the color purity is not reduced.

FIG. 4 is a perspective view of a third embodiment 30 of the shadow mask structure of the present invention. The difference from the first embodiment is that both the long side 31A and the short side 31B of the mask frame 31 are made of 13 chrome stainless steel, and the mask frame long side 31A is provided with a pair of mask supports 34. That the long side 32A of the shadow mask 32 is seam-welded to the mask support 34;
Are welded (hatched portions) at both ends of the thermal expansion regulating material (Invar alloy tape 33). Mask support 34
Is an Invar alloy having a thickness of 3 mm and a width of 15 mm. The upper end surface of the mask support 34 is located at the upper end surface and surface position of the long side 31A of the mask frame.

The feature of the third embodiment 30 of the shadow mask structure of the present invention is that the mask frame long side 31A is made of 13 chrome stainless steel, which is less expensive than the Invar alloy. This is much cheaper than the first embodiment. The effect that the color purity does not decrease is the same as that of the first embodiment.

FIG. 5 is a perspective view of a fourth embodiment 40 of the shadow mask structure of the present invention. The difference from the third embodiment 30 is that a part of the shadow mask non-porous portion 42E on the short side 42B side of the shadow mask 42 is removed and the mask frame 4 is removed.
That is, both ends of the Invar alloy tape 43 are welded (hatched portions) so as to connect one long side 41A. This configuration facilitates the welding operation and has good space efficiency as compared with the third embodiment. The third embodiment is similar to the third embodiment in that the cost is low and the color purity does not decrease.

[0023]

According to the shadow mask structure of the present invention, a thermal expansion restricting material connecting the long sides of the mask frame is added, so that even if the short side of the mask frame thermally expands, the increase in the tension acting on the shadow mask is more than that of the conventional shadow mask structure. Less. This reduces the shadow mask dent by a fraction
Therefore, the landing deviation is reduced to a fraction, and the size does not pose a practical problem. As a result, in the color cathode ray tube equipped with the shadow mask structure of the present invention, the color purity does not decrease even if the temperature of the shadow mask structure increases.

[Brief description of the drawings]

FIG. 1 is a first embodiment of a shadow mask structure according to the present invention.
0 perspective view

FIG. 2 is a first embodiment of a shadow mask structure according to the present invention;
0 is a schematic diagram showing a shape change when the temperature of the shadow mask structure 10 increases at 0

FIG. 3 is a second embodiment of the shadow mask structure of the present invention.
0 perspective view

FIG. 4 is a third embodiment of the shadow mask structure of the present invention.
0 perspective view

FIG. 5 is a fourth embodiment of the shadow mask structure of the present invention.
0 perspective view

FIG. 6 is a perspective view of an example 50 of a conventional shadow mask structure.

FIG. 7 is a schematic diagram showing a shape change when the temperature of the shadow mask structure 50 increases in an example 50 of a conventional shadow mask structure.

[Explanation of symbols]

 Reference Signs List 10 shadow mask structure 11 mask frame 11A mask frame long side 11B mask frame short side 12 shadow mask 12A shadow mask long side 12B shadow mask short side 12D shadow mask perforated portion 12E shadow mask non-perforated portion 13 Invar alloy tape 20 shadow mask structure DESCRIPTION OF SYMBOLS 21 Mask frame 21A Mask frame long side 22 Shadow mask 22B Shadow mask short side 22E Shadow mask non-porous part 23 Invar alloy tape 30 Shadow mask structure 31 Mask frame 31A Mask frame long side 32 Shadow mask 32A Shadow mask long side 33 Invar alloy tape 34 mask support 40 shadow mask structure 41 mask frame 41A long side of mask frame 42 shadow mask 42B shadow mask Side 42E shadow mask imperforate portion 43 Invar alloy tape 50 a shadow mask structure 51 mask frame 51A mask frame long sides 51B mask frame short side 52 shadow mask 52A shadow mask long side 52B shadow mask short side

Claims (9)

[Claims] A mask frame having a substantially rectangular frame shape;
A shadow mask structure comprising a substantially rectangular shadow mask having a pair of long sides stretched over the mask frame, wherein a thermal expansion restricting material connecting the pair of long sides of the mask frame is provided. Structure. 2. The shadow mask structure according to claim 1, wherein said thermal expansion restricting material is provided at a position of a non-porous portion on the short side of said shadow mask. 3. The shadow mask structure according to claim 1, wherein a coefficient of thermal expansion of the thermal expansion regulating material is substantially equal to a coefficient of thermal expansion of the shadow mask. 4. A shadow mask structure according to claim 3, wherein said shadow mask and said thermal expansion restricting material are made of an Invar alloy. 5. A shadow mask structure comprising a substantially rectangular frame-shaped mask frame and a substantially rectangular shadow mask, wherein a long side of the mask frame is provided with a pair of mask supports, and the long side of the shadow mask is the mask. A shadow mask structure, comprising a thermal expansion restricting member stretched on a support and connecting the pair of long sides of the mask frame or the pair of mask supports. 6. The shadow mask structure according to claim 5, wherein said thermal expansion restricting material is provided at a position of a non-porous portion on the short side of said shadow mask. 7. The shadow mask structure according to claim 5, wherein the thermal expansion coefficient of the thermal expansion regulating material, the thermal expansion coefficient of the shadow mask, and the thermal expansion coefficient of the mask support are substantially the same. Characteristic shadow mask structure. 8. The shadow mask structure according to claim 7, wherein said shadow mask, said thermal expansion restricting material and said mask support are made of an Invar alloy. 9. A color CRT equipped with the shadow mask structure according to claim 1.