KR20020019216A - Shadow mask with impact strength improved - Google Patents

Abstract

PURPOSE: A shadow mask with improved impact strength is provided to improve an impact strength of the shadow mask when a drop test by properly changing a curvature shape of the shadow mask. CONSTITUTION: A shadow mask(20) has curvature which is defined as a quartic having three vertexes. A sharp rise part(22) is formed with curvature upwardly at the center. A sink part(24) is formed with curvature downwardly at the outside of the sharp rise part(22). The shadow mask(20) is made of Invar steel. A plurality of mask holes(20a) is formed for an electron beam to pass at an entire face of the shadow mask. And therefore, the shadow mask has larger area contacted to a press than a shadow mask having a single curvature.

Description

Shadow mask with impact strength improved

The present invention relates to a shadow mask frame assembly of a cathode ray tube, and more particularly, a shadow mask of an anode ray tube with improved impact strength to prevent plastic deformation of a shadow mask and to minimize deformation when an external shock is applied to the cathode ray tube. Relates to a frame assembly.

Cathode ray tube is one of the most common display devices, and a device that implements a screen by striking an electron beam to a phosphor in a state where the inside is high-pressure vacuum, and the electron beam selectively strikes a phosphor of R, G, B to implement a color screen do.

A schematic structure of a conventional cathode ray tube is shown in cross section in FIG.

Referring to the drawings, it can be seen that the appearance of the cathode ray tube is largely made of a funnel-type funnel 2 and a face panel 4. An electron gun 6 is positioned at the opposite end of the face panel 4, which emits a heated electron beam at the cathode and has several electrodes, so that the electron beam passing through the electrode is focused and accelerated. To reach the face panel 4 where the anode electrode is formed.

The neck of the funnel 2 is equipped with a deflection yoke 8 around the periphery of which the deflection yoke 4 serves to deflect the electron beam having a straightness to be suitable for the area of the face panel 4. . Since the electron beam is influenced by the geomagnetism while proceeding to the face panel 4, an inner shield 10 is installed to correct the influence of the geomagnetism.

The mask frame 14 to which the shadow mask 12 is welded is coupled to the face panel 4, and the shadow mask 12 is applied to the face panel 4 by the electron beam emitted from the electron gun 6. As a color screening mechanism capable of selectively striking the R, G, and B phosphors, a myriad of mask holes 12a are formed in a thin plate within 1 mm in thickness.

The mask hole 12a has a stripe type and a dot type. In recent years, a stripe type mask hole 12a is applied. The shadow mask frame assembly 16 in which the shadow mask 12 is welded to the mask frame 14 is assembled inside the face panel 4 and seals and bands the funnel 2 and the face panel 4.

Cathode ray tubes consisting of the devices are manufactured and subjected to various reliability tests. During this test, there is a drop test, in which the cathode ray tube is dropped at a certain height to test whether the shadow mask 12 is deformed. The shadow mask 12 is most deformed during the drop test when the electron gun 6 is installed downward of the cathode ray tube and the face panel 4 is dropped upward.

If the impact force is weak during the drop test, the shadow mask 12 immediately returns to its original state even if a slight deformation occurs, but if the impact force is large, the shadow mask 12 vibrates violently in the up and down direction, and part of the surface is crushed. You will not be able to return to normal. There are many reasons for this, but it is also related to the shape of the shadow mask.

FIG. 6 illustrates a long side portion of the shadow mask 12 of the conventional cathode ray tube. Referring to the drawings, the shadow mask 12 has a curvature formed on the face panel 4 side and is generally symmetrical with one vertex at the center and a single spherical curvature. As described above, the shadow mask 12 having a single peak has a structural weak point against vertical vibration.

As a result, when plastic deformation occurs in the shadow mask 12, the electron beam emitted from the electron gun 6 may not hit the phosphor of the face panel 4 properly, resulting in a poor screen, resulting in a decrease in productivity.

The present invention is a new invention proposed to solve the above-mentioned problems of the prior art, an object of the present invention is to provide a shadow mask that can improve the impact strength during the drop test by appropriately changing the curved shape of the shadow mask.

In order to achieve the above object, the shadow mask having improved impact strength according to the present invention has a configuration in which the curvature has a curvature defined by a polynomial.

The cross-section curvature of the long side or short side direction of the shadow mask is characterized in that at least two vertices.

As described above, if the shadow mask has at least two vertices while having an aspherical surface, the contact area is widened during press molding, which facilitates the manufacturing process, and the mask is structurally improved in strength so that the plastic deformation can be subjected to excessive impact forces during drop tests. It can be prevented.

1 is a perspective view showing a preferred embodiment of the shadow mask of the cathode ray tube according to the present invention.

FIG. 2 is a side cross-sectional view of the long side of the shadow mask of FIG. 1;

3 and 4 are side cross-sectional views showing other embodiments of the shadow mask according to the present invention.

Figure 5 is a side cross-sectional view schematically showing a conventional cathode ray tube.

Figure 6 is a side cross-sectional view showing a conventional shadow mask.

** Description of symbols for the main parts of the drawing **

2: funnel 4: face panel

20,30,40: shadow mask 22,32,42: ridge

24,34,44: depression

The structure of this invention is demonstrated in detail, referring an accompanying drawing. For reference, prior to describing the configuration of the present invention, in order to avoid duplication of description of the prior art reference will be referred to the same reference numerals.

1 and 2 illustrate a preferred embodiment in which the impact strength is improved by the present invention, but in FIG. 1 is a perspective view, and FIG. Since the cathode ray tube in which the shadow mask is installed has been described in the related art, a detailed description thereof will be omitted.

Referring to the side cross-section shown in FIG. 2, the shadow mask 20 has a curvature defined by a quadratic polynomial having three vertices. That is, in the center, the curvature is formed upwardly and the raised ridge 22 is formed, and the ridge 22 is formed in the recessed portion 24 and the curvature is formed downward.

The shadow mask 20 is made of Invar steel, and a plurality of mask holes 20a are formed on the front surface of the shadow mask 20 so that the electron beam can pass therethrough. In order to manufacture such a shadow mask 20, a mold is usually formed by a press. When the curvature has a plurality of curvatures as described above, an area in contact with the press is wider than a shadow mask having a single curvature. The press, shadow mask and contact rate increase proportionally by forming a large number of curvatures.

As described above, when the area in contact with the press is widened, the spring back phenomenon to return to the original shape after molding into the press is reduced, thereby improving moldability and facilitating the manufacturing process.

3 and 4 show side cross-sectional views of other embodiments 30 and 40 of a shadow mask according to the present invention.

Referring to the cross-sections of the shadow masks 30 and 40 shown in FIGS. 3 and 4, the shadow masks 30 and 40 have a plurality of ridges 32, 42 and depressions 34 ( 44) is formed. As described above, the shadow masks 30 and 40 in which the plurality of ridges 32 and 42 and the depressions 34 and 44 are formed may be manufactured flatter than the shadow mask formed in the conventional single curvature, and doming phenomenon Can also be reduced.

When a plurality of ridges 22, 32, 42 and depressions 24, 34, 44 are formed in the shadow masks 20, 30, and 40, the boundary that is bent during molding with a bead is formed. bead), which enhances the structure, making the shadow mask flat. In addition, the shadow mask 20, 30, 40 is the majority of the electron beam emitted from the electron gun hits the shadow mask to heat the shadow mask, which causes the shadow mask is thermally expanded to rise to a certain height toward the face panel. It is called the doming phenomenon. If the shadow masks 20, 30 and 40 are configured to have a plurality of curvatures, the depressions 24, 34 and 44 having curvatures formed in the opposite direction to the face panel can suppress the doming phenomenon. do.

Since the shadow mask can be manufactured flatter than a conventional shadow mask having a single curvature, a face panel in which the inner curvature is determined by the shadow mask can also be manufactured more flatly. In other words, since the recent cathode ray tube aims at flattening, the outer surface of the face panel, that is, the surface viewed by the user, is made almost flat. However, the inner surface of the face panel adjacent to the shadow mask is formed to be the same as the curvature of the shadow mask.

Like the shadow mask of the present invention, a plurality of curvatures are made so that the height of the shadow mask is slightly flattened, so that an additional effect of reducing the thickness of the face panel can be obtained.

In the above-described shadow mask, the boundary surface formed with a plurality of curvatures acts like a bead, thereby improving the strength of the shadow mask, thereby improving impact strength during drop impact.

When the long-side curvature of the shadow mask is formed to be a curvature defined by the polynomial, the press maskability of the shadow mask is improved, which makes it easier to manufacture, to bring it flatter than the conventional shadow mask having a single curvature, and ultimately the impact strength Therefore, plastic drop deformation of the shadow mask can be prevented during the drop test.

The present invention is not limited to the above-described specific preferred invention, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims. .

Claims (2)

A shadow mask of a cathode ray tube having a mask hole for selectively passing an electron beam emitted from an electron gun, A shadow mask of a cathode ray tube, characterized in that the curvature is formed so that the cross-section curvature of the long side direction or short side direction has a curvature defined by the polynomial, and has at least two vertices. The shadow mask of claim 1, wherein the shadow mask has an aspherical curvature.