KR20040057087A - Mask Frame Assembly with a Plate of Low Expansion Rate attatched to Frame - Google Patents

Abstract

PURPOSE: A mask frame assembly with a plate of low expansion rate attached to frame is provided to weaken a thermal expansion of a frame corner part in order to compensate again a landing error of a corner part or a diagonal of a mask. CONSTITUTION: A mask frame assembly with a plate of low expansion rate attached to frame comprises a shadow mask(11) including a porous part(11a) having a plurality of hole and a skirt part(11b) bent and extended from the edge of the porous part; a supporting frame(12) for fixing the shadow mask; and a plurality of sticking plates(21) adhered at a corner part of the frame and constituted with a material having a low expansion coefficient than the frame.

Description

Mask Frame Assembly with a Plate of Low Expansion Rate attatched to Frame}

The present invention relates to a shadow mask assembly for a cathode ray tube, and more particularly to a structure of an adjustable shadow mask support frame that can adjust the local and the total thermal dilift amount of the shadow mask.

In general, a cathode ray tube is a display device that realizes an image by exciting three phosphor beams emitted from an electron gun against R, G, and B phosphors in a phosphor film screen to excite the phosphors.

To this end, the cathode ray tube includes a panel having a fluorescent screen on its inner surface, an electron gun for emitting an electron beam toward the fluorescent screen, a neck portion for mounting the electron gun therein, a trumpet-shaped funnel connecting the panel and the neck portion, and a fluorescent film And a shadow mask frame assembly including a shadow mask mounted in parallel with the screen.

The shadow mask frame assembly is a component having a color screening function that separates and lands an electron beam emitted from an electron gun into a corresponding phosphor, which is disposed in parallel with a fluorescent screen on an inner surface thereof, and supports shadow masks and shadow masks that perform color screening. And a plurality of spring members or the like for fixing the frame to the panel.

1 is a perspective view of a shadow mask frame assembly. As shown in Fig. 1, the shadow mask frame assembly installed inside the panel extends a predetermined length from the edge of the perforated portion 11a and the edge of the perforated portion 11a in which a plurality of electron beam passing apertures H are formed. And a frame 12 supporting the shadow mask 11 by welding the shadow mask 11 having the skirt portion 11b bent at a right angle and the skirt portion 11b of the shadow mask 11 by welding. It consists of. The frame 12 is a frame for fixing the shadow mask, and the support portion 12a coupled with the skirt portion 11b of the shadow mask 11 and the flange portion 12b extending in a predetermined length inward to the lower end of the support portion 12a. It is composed of The shadow mask frame assembly is coupled to a spring (not shown) fixed to the side of the frame 12 and a stud pin (not shown) fixed to the inner side of the panel, so that the shadow mask is spaced apart from the fluorescent film by a predetermined distance. do.

However, the shadow mask is formed by forming a plurality of beam passing apertures in a very thin thickness of aluminum-kilted (AK) steel or INVAR steel by a known photolithography process, and then drawing and finalizing The shape is completed. These shadow masks are extremely thin in comparison to a large area and have hundreds of thousands of apertures for beam passing. Therefore, the shadow masks are extremely weak and can be turned off by external impact or by continuous scanning of the electron beam. Thermal expansion causes what is called a doming phenomenon.

As such, when the shadow mask is deformed or a doming phenomenon occurs, the position of the beam passing aperture is changed to prevent accurate color separation of the electron beam, thereby degrading the color purity of the screen. In order to reduce the doming phenomenon or thermal drift, the shadow mask frame assembly is formed using a frame made of a material having a coefficient of thermal expansion that can correspond to the thermal expansion of the shadow mask.

When the frame is made of carbon steel having a high coefficient of thermal expansion, the deformation of the mask occurs abruptly at the beginning of the tube operation, and the frame also expands over time to compensate for landing errors due to the expansion of the mask. However, when time reaches the ballast, the diagonal expansion of the mask is overcorrected, and the landing error of the diagonal portion is deteriorated by the expansion of the frame. Overcompensation by such a frame cannot be recalibrated even by a spring provided on the side of the frame.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and aims to weaken the degree of thermal expansion of the frame corner portion in order to recalibrate the landing error of the diagonal to corner portions of the mask caused by excessive expansion of the frame in the ballast.

1 is a perspective view of a shadow mask frame assembly;

2 is a plan view of a mask frame assembly with low expansion carbon steel attached outside the corners of the frame;

FIG. 3 is an enlarged view of a corner part in enlarged view of portion A of FIG. 2.

Explanation of symbols on the main parts of the drawing

11: shadow mask 11a: perforation

11b: skirt portion 12: frame

12a: support portion 12b: flange portion

21: attachment plate 31: welding point

In order to achieve this object, the present invention provides a mask frame assembly that can reduce the thermal expansion of the corner portion by attaching carbon steel of a material having a smaller coefficient of thermal expansion than the frame body by welding or the like to the corner portion of the frame.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a plan view of a mask frame assembly with low expansion carbon steel attached to the outside of the corners of the frame. As shown in Fig. 2, the skirt portion 11b formed by bending the long side and the short side of the shadow mask 11 is coupled to the inside of the frame by welding or the like. The skirt part 11b of the shadow mask 11 is bent at substantially right angle with the hole part surface 11a of the shadow mask.

An attachment plate 21 made of carbon steel or the like having a low expansion coefficient is attached to the outer surface of the corner portion of the frame 12 having a high expansion coefficient. The attachment plate 21 is attached to both the long side and the short side about the corner of the frame. Since the purpose of the attachment plate 21 is to increase the corner expansion coefficient of the frame 12, the coupling of the frame 12 and the attachment plate 21 is formed so that the frame 12 and the attachment plate 21 are integrated. It is preferable to make it. Thus, the frame 12 and the attachment plate 21 are joined by welding.

The ratio of the thermal expansion coefficient of the frame 12 and the attachment plate 21 is appropriately selected in consideration of the material and thermal expansion coefficient of the shadow mask 11 and the frame 12 and the width of the attachment plate 21.

FIG. 3 is an enlarged view of a corner part in enlarged view of portion A of FIG. 2. As shown in FIG. 3, the attachment plate 21 is attached to both the long side and the short side at the lower end of the corner of the frame 12. As shown in FIG. In order to reduce the weight of the mask frame assembly and sufficiently absorb thermal expansion of the mask, the length of the direction of the frame 12 of the attachment plate 21 is preferably within 25% of the long side and the short side of the frame. When the expansion coefficient difference of the frame 12 is larger, it is preferable to form within 10%.

On the other hand, the skirt portion 11b of the shadow mask is usually coupled to the inner surface of the frame 12 by two welding points 31 on one side. This combination of the skirt portion 11b and the frame 12 transfers the thermal expansion of the shadow mask to the frame, where the frame 12 absorbs the thermal expansion transferred by thermal expansion. Therefore, the width of the attachment plate 21 will vary depending on the length of the attachment plate 21, but it is preferable to place it below the portion where the skirt portion 11b and the frame 12 are welded. This is so that the attachment plate 21 extending to the long and short sides of the frame does not prevent the frame from effectively absorbing the thermal expansion transmitted from the mask.

In Fig. 3, part B is a portion which does not enter the ballast due to thermal expansion of the frame even when the thermal expansion of the mask enters the ballast due to thermal expansion of the frame, thereby degrading the image quality of the corner portion of the screen. However, the thermal expansion of the frame is prevented by the low expansion coefficient attachment plate attached to the corner portion of the frame, whereby the thermal expansion in the diagonal direction of the mask is prevented, in harmony with the stability of the other part of the mask.

According to the mask frame assembly having a frame attachment plate having such a structure and action, landing errors in the diagonal to corner portions of the mask caused by excessive expansion of the frame when it comes out of the initial operation of the tube and reaches the ballast can be prevented. It is possible to effectively prevent the deterioration of the corner portion.

Claims (4)

In the shadow mask frame assembly for holding and fixing the shadow mask of the cathode ray tube, A shadow mask having a perforated portion having a plurality of holes and a skirt portion bent at an edge of the perforated portion; A frame configured to support the shadow mask by fixing the skirt part while being welded therein; And A mask frame assembly having a low-expansion attachment plate in the frame, characterized in that it comprises a plurality of attachment plates attached to the corner portion of the frame, made of a material having a coefficient of thermal expansion less than the frame. The method of claim 1, wherein the attachment plate Mask frame assembly having a low-expansion attachment plate in the frame, characterized in that integrally coupled to the frame by welding. According to claim 2, wherein the length of the mounting plate A mask frame assembly having a low-expansion attachment plate in the frame, characterized in that formed within 20% of the long side and short side length of the frame. The method of claim 3, wherein the attachment plate is A mask frame assembly having a low-expansion attachment plate in a frame, characterized in that the width is determined to be located below the point of engagement of the frame and the skirt portion.