KR20020095376A - Shadow mask for color cathode-ray tube - Google Patents

Abstract

PURPOSE: A shadow mask for a color cathode ray tube is provided to improve the color purity by decreasing a value, which adds lengths of first and second bent-up portions, from a center of each side to both corners to prevent the magnification of a mask slot at four corners. CONSTITUTION: A bead(12) is comprised of first and second bent-up portions. The first bent-up portion is provided between an effective portion and a frame welding portion and bent-up in an opposite direction of the panel. The second bent-up portion is bent-up and extended to a direction of the panel. A value that lengths of the first and second are added is gradually decreased from a center of each side of a shadow mask to both corners. The length of the second bent-up portion is gradually decreased while the length of the first bent-up portion is constant. The length of the first bent-up portion is gradually decreased while the length of the second bent-up portion is constant.

Description

Shadow mask for color cathode ray tube {SHADOW MASK FOR COLOR CATHODE-RAY TUBE}

The present invention relates to a color cathode ray tube, and more particularly to a structure of beads formed along edges to reinforce the rigidity of the shadow mask for the color cathode ray tube.

As shown in FIG. 1, a general color cathode ray tube includes a panel 1 having a red, green, and blue (R, G, B) fluorescent film 2 coated on its inner surface side and a rear end of the panel 1. Fused to the electron gun (6) and the electron gun (6) encapsulated in the neck (4) of the funnel (3) and the funnel (3) to keep the interior in a vacuum state and radiate the electron beam (5). It consists of a shadow mask 7 having a color selection function of an electron beam, and a frame 8 for fixing and supporting the shadow mask 7. Here, the state before the shaping of the shadow mask 7, which serves as the color selection of the electron beam, is a state in which a myriad of holes 11 are bored as shown in FIG.

In addition, since the shadow mask is a thin plate of only 0.15 mm, the first bent portion is bent and extended in the opposite direction to the panel side between the effective portion and the invalid portion so as to reinforce rigidity to maintain its shape after molding, and the tube axis direction. A bead 12 is formed, which consists of a second bent portion which is bent and extended back toward the adjacent frame vertically. At this time, the length of the first bent portion and the second bent portion is constant.

However, in the process of forming the bead portion as described above, a local stretching phenomenon (a phenomenon in which the width and length increase at the same time) is generated around the shadow mask bead, and in particular, the stretching phenomenon is rapidly increasing toward the corners as shown in FIG. 3. Get up.

Accordingly, the mask hole adjacent to the corner of the bead is enlarged compared to the hole located at the center so that the electron beam passing through the mask hole adjacent to the corner overlaps with another electron beam from the adjacent hole or reduces the margin for color purity. It caused the color purity defect and color purity to fall, for example, a color other than the said color will emit light.

Accordingly, the present invention has been made to solve the above problems, an object of the present invention is the value of the length (H) of the first bent portion and the length (W) of the second bent portion at the center of each side of the shadow mask. It is to provide a color cathode ray tube which improves the color purity in the vicinity of the corner by preventing the enlargement of the mask hole near the corner by gradually reducing in both corner directions.

1 is a schematic view of a conventional cathode ray tube comprising a bead consisting of a first bend and a second bend;

2 is a front view of the shadow mask.

3 is an enlarged view of a portion A of FIG. 2;

4A to 4C are plan views showing a bead structure in the center portion and the corner portion of the side;

Fig. 5 is a cross sectional view showing a bead structure in the center portion and the corner portion of the side;

<Description of Symbols for Major Parts of Drawings>

7: shadow mask 11: mask hole

12: Bead

In order to achieve the above object, the present invention is a rectangular panel (1) having a fluorescent surface (2) formed on the inner surface, is disposed at a predetermined distance from the fluorescent surface of the inner surface of the panel 1 is incident toward the inner fluorescent surface (2) In a color cathode ray tube comprising a shadow mask (7) having a color discriminating function of an electron beam (5), and a frame (8) for fixing and supporting the shadow mask, the shadow mask has an electron beam through hole to compensate for the intensity. And a bead 12 including a first bent portion bent and extended in the opposite direction to the panel side between the formed effective portion and the frame welded portion, and a second bent portion extended and bent back toward the frame. A value obtained by adding the length H of the part and the length W of the second bent part is gradually reduced in both corner directions at the center of each side of the shadow mask.

In an embodiment, in a state in which the length H of the first bent portion is constant, the length W of the second bent portion may be gradually reduced, and in a state in which the length W of the second bent portion is constant, The length H of the bent portion may be gradually reduced, and the length H of the first bent portion and the length W of the second bent portion may be simultaneously reduced.

Preferably, the sum of the length (H) of the first bent portion and the length (W) of the second bent portion is characterized by being less than (H + W) / 2 near four corners, more preferably, the length is 2a. On the long side of the shadow mask, the length (H) of the first bent portion and the length (W) of the second bent portion are equal to or less than (H + W) / 2 from the point at which a / 2 is at the corner, and the length is 2b. At the short side of the shadow mask, a value obtained by adding the length (H) of the first bent portion and the length (W) of the second bent portion is characterized by being less than (H + W) / 2 from the point where it is b / 2 at the corner. .

Hereinafter, the configuration of the present invention described above with reference to the accompanying drawings as follows.

The present invention relates to a structure of beads formed along edges to reinforce the rigidity of the shadow mask for color cathode ray tubes. However, since the corner portion of the bead is where the sides are concentrated, the degree of deformation is inevitably larger than that of each side, so that the mask holes located near each corner also have a large deformation rate, thereby causing poor color purity. Thus, the length of the first bent portion and the length of the second bent portion are gradually reduced from the center of each side toward both corner directions to minimize the degree of deformation of the mask hole located near the corners.

4A to 4C are plan views illustrating the structure of the beads at the center portion and the corner portion of the side, and show embodiments of a method for minimizing deformation of the mask hole located at the corner portion. 4A shows that the length of the first bent portion is constant and the length of the second bent portion gradually decreases toward both corner portions. 4C shows that the length of the first bent portion and the second bent portion is gradually reduced in both corner directions at the same time.

5 is a cross-sectional view showing the structure of the bead consisting of the first bent portion and the second bent portion at the center portion and the corner portion of the shadow mask side, and the length H _C and the second bend portion at the corner portion of the side. The length W _C of the portion is smaller than the length H _J of the first bend portion and the length W _J of the second bend portion in the center portion in order to suppress the enlargement of the mask hole in the corner portion. Here, the bead structure may be two or more stages in pairs of the first bent portion and the second bent portion.

Such embodiments should not be individually understood from the technical spirit or the prospect of the present invention, and the modified embodiments should fall within the claims appended to the present invention.

As described above, in the case of the shadow mask including a bead having a first bent portion and a second bent portion having a predetermined length, the mask slot is enlarged near four corners, resulting in poor color purity. Thus, by gradually decreasing the length H of the first bent portion and the length W of the second bent portion from the center of each side to both corner portions, it is possible to suppress the enlargement of the mask slot at the four corner portions to improve color purity.

Claims (7)

A rectangular panel having a fluorescent surface formed on an inner surface thereof, a shadow mask having a color discrimination function of an electron beam incident toward an inner fluorescent surface disposed at a predetermined distance from the fluorescent surface of the inner surface of the panel, and a frame for fixing and supporting the shadow mask; In the color cathode ray tube, The shadow mask is a first bent portion bent and extended in the opposite direction to the panel side of the shadow mask between the effective portion in which the electron beam passing hole is formed and the frame welding portion to compensate for the strength, and the second bend extended and bent toward the frame again. A bead consisting of portions; The length of the first bent portion (H) and the length of the second bent portion (W) is a color cathode ray tube, characterized in that gradually decreases in both corner directions at the center of each side of the shadow mask. The method of claim 1, A color cathode ray tube, characterized in that the length (W) of the second bent portion gradually decreases while the length (H) of the first bent portion is constant. The method of claim 1, A color cathode ray tube, characterized in that the length (H) of the first bent portion gradually decreases while the length (W) of the second bent portion is constant. The method of claim 1, The length (H) of the first bent portion and the length (W) of the second bent portion are gradually smaller at the same time, characterized in that the color cathode ray tube. The method of claim 1, And a length (H) of the first bent portion and the length (W) of the second bent portion is equal to or less than (H + W) / 2 near four corners. The method of claim 1, On the long side of the shadow mask having a length of 2a, the sum of the length (H) of the first bend and the length (W) of the second bend becomes (H + W) / 2 or less from the point a / 2 at the corner. Color cathode ray tube characterized by the above-mentioned. The method of claim 1, On the short side of the shadow mask having a length of 2b, the sum of the length (H) of the first bend and the length (W) of the second bend becomes less than (H + W) / 2 from the point a / 2 at the corner. Color cathode ray tube characterized by the above-mentioned.