JP3060643B2 - Color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube,
In particular, the present invention relates to a mask structure in which the color selection electrodes are formed by stretching a number of strip-shaped grid elements.

[0002]

2. Description of the Related Art As a color selection electrode of a color picture tube, there is one having a structure using a large number of strip-shaped grid elements 20, for example, as shown in FIG. This is because a large number of electron beam passing slits extending in one direction, that is, generally in a vertical direction, are formed in a low carbon steel thin plate by etching (a strip-shaped grid body 20 is formed between each slit), and color selection is performed. It is an electrode. This strip-shaped grid body 20 is
The mask structure is formed on a frame structure 23 including a pair of substantially L-shaped bar-shaped support portions 21 opposed to each other and a substantially U-shaped elastic support portion 22 supported at or near the vessel point. .

In this case, when attaching to the frame structure 23, an external force is applied (pressurized) in a direction to draw the rod-shaped support portions 21 together so that the strip-shaped grid body 20 is stretched with a required tension. The belt-shaped grid body 20 is fixed by resistance welding or laser welding in this state. Thereafter, a so-called turnbuckle system is employed in which the tension is applied to the strip-shaped grid body 20 by the restoring force of the frame structure 23 by releasing the pressurization.
In general, the pressure points in the turnbuckle system are relatively left and right, one at each of the left and right sides of the rod-shaped support portion 21. However, in a large frame structure 23 such as a large pipe, a plurality of pressure points are required. By doing so, local stress concentration was avoided.

[0004]

In the conventional mask structure, in the direction perpendicular to the extending direction of the strip-shaped grid body in a state where the pressure is released, that is, in the left and right end portions in the horizontal direction, the strip-shaped grid is compared with the center portion. Since the element body tends to sag, the amount of pressurization and the point of pressurization of the rod-shaped support portion are determined so that the tension at both left and right sides is greater than the tension at the center. In the case of a large frame structure such as a large tube, the tension at the left and right ends reaches near the elastic region limit of the strip-shaped grid body.

[0005] This mask structure passes through a heating process such as a blackening process, a sealing process between the panel and the funnel, and an exhausting process. At this time, the thermal expansion of the frame structure causes the extension of the strip-shaped grid body. If the amount of dimensional enlargement in the direction is larger than the amount of dimensional enlargement of the strip-shaped grid body itself, the tension of the strip-shaped grid body will increase during the process as a result. Therefore, in regions where the tension is originally high, such as the left and right end portions, the elastic deformation of the strip-shaped grid body is exceeded and plastic deformation occurs, and there has been a problem that a predetermined tension distribution cannot be obtained after the completion of the heating step. Further, there is a problem that wrinkles (phenomenon that a fixed curved surface does not appear) and pitch unevenness occur due to local irregularities in tension.

[0006]

The color picture tube according to the present invention comprises a frame structure in which the bottom surface of a substantially L-shaped rod-shaped support portion is made of a metal material having a different coefficient of thermal expansion. In this atmosphere, the tension applied to the strip-shaped grid body is small, and wrinkles and pitch unevenness are prevented from being generated on the stretched strip-shaped grid body surface.

In the bottom surface of the substantially L-shaped support, the coefficient of thermal expansion at the inner opening end is smaller than the coefficient of thermal expansion at the bent portion.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a mask structure according to one embodiment of the present invention. On the bottom portion 12 of the substantially L-shaped rod-shaped support portion 11,
The frame member 16 is made of a metal material having a lower thermal expansion coefficient on the inner opening end 13 side than the thermal expansion coefficient on the bent portion 14 side, and is supported by an elastic supporting portion 15 supported at or near the Bessel point of the rod-shaped supporting portion. Is composed. When a mask structure formed by stretching a color selection electrode composed of a strip-shaped grid element 17 having a tension distribution in which the tension on the left and right ends is higher than the center by a turnbuckle method is put into a heating process, the frame assembly 16 and the strip-shaped grid Although the element body 17 thermally expands, the rod-shaped support portion 11 constituting the frame structure has an open end 1 at an inner side from the bent portion 14 side of the bottom surface.
Since the expansion coefficient is smaller on the third side, the center portion of the opposing rod-shaped support portion 11 moves away, and the left and right end portions approach each other, that is, the rod-shaped support portion 11 is displaced so as to have a smaller radius of curvature.

The displacement of the rod-shaped support portion 11 acts in a direction to suppress the dimensional expansion of the strip-shaped grid body 17 in the extending direction due to the thermal expansion of the frame structure 16 at both left and right ends.
For example, in the case of a 20-inch class color picture tube, assuming that the linear thermal expansion coefficient α of the strip-shaped grid element 17 is α × 12 × 10 ⁻⁶ / ° C., the grid dimension l is 280 mm, and the temperature rise ΔT is 450 ° C., The thermal expansion amount Δl of No. 17 is Δl
= Α · ΔT · l = 1.512 mm. On the other hand, the amount of thermal expansion of the frame structure 16 cannot be formulated because it differs depending on the structure thereof, but is usually a value larger than the band-shaped grid body 17. Here, the thermal expansion amount of the strip-shaped grid body 17 is 2
The case where the number is double will be described as an example. In order to eliminate the change in tension due to the difference in the amount of thermal expansion, the frame structure 16 may be curved in the opposite direction by an amount corresponding to the difference.

The strip-shaped grid body 17 and the frame structure 16
The difference in the amount of thermal expansion in the extension direction of the strip-shaped grid body 17 is 1.512 mm. Since the rod-shaped support portion 11 is fixed to the elastic support portion 15, its thermal displacement can be regarded as being equivalent to the tension at both ends. The amount of displacement of the bimetal supported at both ends is expressed by the following equation.

D = K · ΔT · L ² / 4t (1) where D is a displacement amount, K is a curvature coefficient, ΔT is a temperature change, L
Is the operating length (length of the support point), and t is the thickness of the bimetal. By transforming equation (1), the curvature constant K can be expressed as K = 4t · D / ΔT · L ² (2) Now D = 1.512 mm, ΔT = 450
C, L = 215 mm, and when the plate thickness of the bimetal, that is, the length t of the bottom surface of the substantially L-shaped bar-shaped support portion 11 is 20 mm, the required bending constant is K = 5.815 × 1 according to the equation (2).
0 ^-6 / ° C.

The bending constant when two different metals are joined is generally expressed by the following equation.

[0013]

Here, Δa is the difference between the coefficients of thermal expansion, m is the ratio of the thickness or width of each material, and n is the ratio of the elastic coefficients of each material. Now, in forming the substantially L-shaped rod-shaped support portion, a fernico material (thermal expansion coefficient: 5.5 × 10 ⁻⁶ / ° C., elastic coefficient: 14) is formed as a low thermal expansion material on the inner opening end side of the bottom portion.
100 kg / mm ² ) and the bent portion side is made of an iron material (thermal expansion coefficient: 14 × 10 ⁻⁶ / ° C., elastic modulus: 20000 kg)
/ Mm ² ), solving equation (3) for m gives
m = 0.6545. That is, a predetermined curvature constant can be obtained by setting the region of the iron material to the region of the fernico = 1: 0.6545. On the low thermal expansion side, another material, for example, 42 alloy (thermal expansion coefficient: 6.7 × 10 ⁻⁶ / ° C., elastic modulus:
When using 14800 kg / mm ² ), the maximum value of the obtained bending constant is K = 5.475 × 10 ⁻⁶ / ° C., (m =
1.17), which is slightly less than the predetermined value, but can be used practically without any problem.

[0015]

As described above, according to the present invention, in the substantially L-shaped rod-shaped support portion, the metal material whose thermal expansion coefficient on the inner opening end side of the bottom surface is smaller than the thermal expansion coefficient on the bent portion side is used. When a mask structure in which a color selection electrode composed of a strip-shaped grid element having a tension distribution in which the tension on both the left and right ends is higher than that of the center part by a turnbuckle method is put into a heating process, the rod-shaped support part has a radius of curvature. Therefore, the difference in the amount of expansion between the frame structure and the strip-shaped grid body in the extension direction of the strip-shaped grid body due to thermal expansion is reduced at both left and right sides of the rod-shaped support portion. Therefore,
Since the heat process passes through the heating process without changing or increasing the tension at the left and right ends of the rod-shaped support portion having a high original tension, plastic deformation of the strip-shaped grid body can be prevented as a result. Tension distribution can be maintained. In addition, there is an effect of suppressing generation of wrinkles and pitch unevenness.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a conventional mask structure.

[Explanation of symbols]

 11, 21 rod-shaped support portion 15, 22 elastic support portion 17, 20 strip-shaped grid body 12 bottom portion 13 inner open end 14 bent portion 16, 23 frame structure

Claims (2)

(57) [Claims] 1. A mask structure in which a large number of strip-shaped grid bodies stretched along one direction are fixed to a frame structure composed of opposing substantially L-shaped rod-shaped support portions and substantially U-shaped elastic support portions by welding. Wherein the bottom surface of the substantially L-shaped rod-shaped support portion is made of a material having a different coefficient of thermal expansion between the inner opening end side and the bent portion side. 2. The color picture tube according to claim 1, wherein a thermal expansion coefficient at an inner opening end side is smaller than a thermal expansion coefficient at a bent portion side at a bottom surface of the substantially L-shaped rod-shaped support portion.