JP2776141B2 - Frame for 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 frame for a color picture tube, and more particularly to a frame for a color picture tube of a shadow mask type.

[0002]

2. Description of the Related Art In a shadow mask type color picture tube, color purity is deteriorated due to a beam landing deviation caused by a shadow mask doming phenomenon caused when a high current is supplied from an electron gun to increase luminance. Has been a concern in the past, and various improvements have been proposed.

The most effective measure among them is to use a shadow mask using an invar material (36% Ni-Fe alloy) having a low coefficient of thermal expansion. Very expensive compared to
Because the processing is also difficult and costs increase,
It is only used for some high-end models.

[0004] The history of doming will be described with reference to FIGS. 4 and 5.

A large amount of electron beams impinge on the perforated surface of the shadow mask 3 to generate heat, causing the perforated surface to rise in temperature and expand. However, the skirt portion 3A of the shadow mask 3 not exposed to the electron beam. Does not expand until the temperature rises due to heat conduction, so the perforated surface of the shadow mask 3 expands with its surroundings suppressed in the initial stage,
It is included in a dome shape. Thereafter, the skirt portion 3A of the shadow mask 3 also rises in temperature due to heat conduction and expands. However, the welding point is fixed to the side wall portion 8B of the frame 8, and the frame 8 having a larger heat capacity than the shadow mask 3 has a lower temperature. Because it does not rise suddenly, it does not expand immediately,
The welding point of the shadow mask 3 is pulled by the frame 8. Even if the temperature rises due to heat conduction, the temperature of the skirt portion 3A of the shadow mask 3 is lower than that of the perforated surface portion, so that the perforated surface portion, which changes, is suppressed from the surroundings. Therefore, the doming does not disappear immediately, and the beam landing continues to change until the frame 8 rises to a certain temperature. This phenomenon is called thermal drift.

As a method of alleviating the constraint at the welding point, as shown in FIG. 6, a deep cut is made on the left and right of the welding point 4 of the skirt 3A of the shadow frame 3 to form a tongue piece 3B. However, there is also an example in which the perforated portion of the shadow mask 3 can be more freely expanded (JP-A-49-7397).
0 and JP-A-49-24218). However, the method of making a cut in the vicinity of the welding point 4 of the skirt portion 3A of the shadow mask 3 immediately reduces the strength of the shadow mask 3, which leads to a sharp mechanical action during the manufacturing process or even after the product is manufactured. Another drawback is that the shock is easily deformed when applied to the shadow mask 3.

Recently, as shown in FIG. 7, there is a shadow mask frame structure having a structure in which the shadow mask 3 is incorporated inside the side wall portion 8B of the frame 8. In this case, when the skirt portion 3A of the shadow mask 3 is tightly fitted to the side wall portion 8B of the frame 8, the thermal expansion of the skirt portion 3A is suppressed by the side wall portion 8B of the frame 8 and the skirt portion 3A cannot expand freely. Doming is not eliminated.

An appropriate space is provided between the skirt portion 3A and the side wall portion 8B of the frame 8, and the opening of the bottom portion 8A of the frame 8 is made to correspond to the skirt portion 3A of the shadow mask 3.
If the electron beam is widened so as to impinge on it, the skirt portion 3A of the shadow mask 3 expands during shadow mask doming, so that doming can be reduced. However, the time required for the thermal drift to stabilize depends on the heat capacity of the frame 8, and such a structure cannot shorten the time. In addition, the method in which the shadow mask 3 is inserted into the side wall portion 8B of the frame 8 and fixed by welding is harder to perform than the method of FIG. However, there is a disadvantage that the effective hole of the shadow mask 3 is also narrowed.

[0009]

In the case of a shadow mask structure in which a shadow mask is placed on the frame 8 used in the related art shown in FIG. 4 so that the mask skirt portion is outside the side wall portion 8B, the shadow mask skirt portion is not provided. Since most of the shadows of the frame 8 are shadowed, even when an overscan such as an NTSC signal is performed, most of the overscanned electron beam collides with the side wall 8B or the bottom surface 8A of the frame 8. As a result, there is a problem that the temperature rise of the skirt portion is slower than that of the hole portion of the shadow mask, and the amount of doming increases.

In the conventional frame 8, the opening of the bottom portion 8A is made small so that no shadow is formed on the screen so that unnecessary beams can be cut off at the bottom portion 8A.
The side wall portion 8B has a shape that rises up to about 2 to 3 mm from the bent portion of the shadow mask to prevent deformation of the shadow mask due to external force as much as possible. For this reason, the surface area of the frame 8 was large and the heat capacity was also large. At present, the automation of the color picture tube manufacturing process has been greatly advanced, and the chance that humans touch the mask structure has been greatly reduced compared to before, so the frame 8 has been strengthened more than necessary to make the shadow mask structure robust. Although the necessity of the fabrication is reduced, the weight of the frame 8 can be reduced, that is, the heat capacity can be reduced. However, there is a problem that the doming is not sufficiently reduced and the thermal drift is not sufficiently stabilized at an early stage.

An object of the present invention is to provide a color picture tube frame capable of reducing doming and stabilizing thermal drift at an early stage.

[0012]

According to the present invention, there is provided a frame for a color picture tube of a shadow mask type for holding a shadow mask. (1) A plurality of projections for fixing the shadow mask in parallel with the tube axis are formed on the bottom surface. I do.

(2) A reinforcing bent portion is provided in the direction perpendicular to the bottom portion over the outer periphery of the bottom portion, and a plurality of projections for fixing the shadow mask in parallel with the tube axis are formed in the reinforcing bent portion. I do.

(3) A spring fixing projection to be attached to the panel is formed between the plurality of projections for fixing the shadow mask.

[0015]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a first embodiment of the present invention in which a shadow mask is mounted.

In the first embodiment, as shown in FIG. 1, a skirt 3 of a shadow mask 3 is provided on the bottom 1A of the frame 1.
A plurality of protrusions 2 for welding A are set up perpendicular to the bottom surface 1A. The size of the opening in the bottom portion 1A is set to a size such that the electron beam collides with most of the skirt portion 3A of the shadow mask 3 but does not pass through the lower portion of the skirt portion 3A. Thus, when an overscan of an NTSC signal or the like is performed, the electron beam also impinges on the skirt portion 3A of the shadow mask 3, so that the shadow mask 3
Is not only the perforated surface, but also the skirt portion 3A simultaneously raises the temperature, and only the perforated surface does not partially expand.
Since the skirt 3A also expands at the same time, the doming becomes very small. Even if the skirt portion 3A expands, the bent portion of the shadow mask 3 expands within the elastic range of the skirt portion 3A because the skirt portion 3A is pressed by the welding point 4, but the skirt portion is only heated by the conduction heat from the perforated surface. Unlike the case where the temperature of 3A rises, both the direct electron beam bombardment and the temperature rise of the receiving skirt portion 3A become higher than before, so that the bending portion expands and as a result, the beam landing deviation due to doming decreases.

Further, since the heat capacity of the frame 1 is reduced, the time required for stabilizing the thermal drift is reduced in proportion to the weight as compared with the conventional case. In this case, frame 1
The spring for attaching the frame to the panel is welded at the bottom 1A of the frame 1.

FIG. 2 is a perspective view of a second embodiment of the present invention.

In the second embodiment, as shown in FIG. 2, a reinforcing bent portion 5B shorter than the claw-shaped projection 2 is formed around the bottom surface 5A of the frame 5 to increase the strength of the frame 5. I do. This makes it possible to suppress the variation in beam landing more than in the frame 1 of the first embodiment shown in FIG.

FIG. 3 is a perspective view of a third embodiment of the present invention.

In the third embodiment, as shown in FIG. 3, a spring welding projection 7 for welding a spring for attaching the frame 6 to the panel is reinforced between the projections 2 of the second embodiment shown in FIG. It is provided in the bending part 5B for use. As a result, the spring used conventionally can be used, and it is not necessary to weld the spring to the frame bottom portion 6A as in the first and second embodiments. This has the effect of reducing costs.

The same effect can be obtained by providing a spring welding projection 7 in the vertical direction on the bottom surface 1A between the projections 2 of the first embodiment shown in FIG.

[0024]

As described above, the present invention has a structure in which the frame is made lighter and the electron beam collides with most of the skirt portion of the shadow mask. And has the effect of shortening the stabilization time of the thermal software.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention in which a shadow mask is mounted.

FIG. 2 is a perspective view of a second embodiment of the present invention.

FIG. 3 is a perspective view of a third embodiment of the present invention.

FIG. 4 is a perspective view of an example of a conventional frame.

FIG. 5 is a sectional view of an example of a conventional combination structure of a shadow mask and a frame.

FIG. 6 is a partially enlarged cross-sectional view of a combination portion of a shadow mask and a frame for explaining an example of a mask cutout of a conventional frame.

FIG. 7 is a cross-sectional view of another example of a conventional combination structure of a shadow mask and a frame.

[Explanation of symbols]

 1, 5, 6, 8 Frame 1A, 5A, 6A, 8A Bottom part 2 Projection 3 Shadow mask 3A Skirt part 3B Tongue piece 4 Welding point 5B, 6B Reinforcing bent part 7 Spring welding projection 8A Bottom part 8B Side wall Department

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 29/07 H01J 29/02

Claims (3)

(57) [Claims] 1. A bottom portion having an opening, and from the bottom portion
And a side wall extending substantially vertically.
A color picture tube tube fixing the skirt of the shadow mask
In the frame, the side wall portion is substantially perpendicular to the bottom surface portion.
Formed by a plurality of projections extending straight,
The feature is that the skirt of the shadow mask is fixed at the beginning
For a color picture tube. 2. A bottom portion having an opening and a distance from the bottom portion.
And a side wall extending vertically.
Frame for color picture tube to fix skirt of dough mask
Wherein the side wall portion is substantially perpendicular to the bottom surface portion.
And a reinforcing fold that extends
Formed by a plurality of projections,
The skirt of the dough mask is fixed.
Frame for color picture tube. 3. A frame is mounted on a panel between a plurality of projections for fixing a skirt portion of the shadow mask.
Color picture tube frame according to claim 1 or 2, wherein the forming the spring fixing projections.