KR20020082962A - shadow mask in a color CRT - Google Patents

Abstract

PURPOSE: A shadow mask for a color cathode ray tube is provided to improve picture quality by generating uniformly tension without lowering of the tension in one directional tension type shadow mask. CONSTITUTION: A frame is formed with a couple of long side portions and a couple of short side portions. The frame is coupled with an inner wall of a panel. A plurality of electron beam passing holes are formed in a shadow mask. A slit-shaped half etching portion(31) is formed at a peripheral portion(2) of the shadow mask. The slit-shaped half etching portion(31) has the same pitch, width, and height as of a final slit(11) of an effective area(1). The slit-shaped half etching portion(31) is connected with an upper portion and a lower portion by a bridge(32).

Description

Shadow mask for a color cathode ray tube {shadow mask in a color CRT}

The present invention relates to a shadow mask for color cathode ray tube, and more particularly, to a shadow mask for color cathode ray tube, which can be uniformly generated without lowering the tension force in a one-way tension type shadow mask and can improve image quality. .

The shadow mask is a component in which the three R, G and B beams emitted from the electron gun hit the phosphor applied to the front panel of the screen to emit light. Since the conventional shadow mask is formed of a very thin sheet of 0.1 ~ 0.3mm unit has no self-shape holding power is molded to have a predetermined curvature, then bonded to the frame and assembled into a mask-frame assembly. In the conventional shadow mask, as the operating temperature of the cathode ray tube is raised, the mask surface is convexly protruding. The tension shadow mask-frame assembly of the cathode ray tube is developed to prevent the doming. The tension shadow mask-frame assembly is to tension the shadow mask externally, or to compress the frame to fix the shadow mask to the frame, and then the tension acts on the shadow mask by a restoring force. Forces act and tension forces act in both directions and in both directions.

The shadow mask having such a function is generally composed of an effective surface 1, a peripheral portion 2, and a skirt portion 3, as shown in the cross-sectional view of FIG. 1, and in the case of a tension shadow mask, a skirt after welding and fixing Since the part 3 is cut out, it is common to consist of the effective surface 1 and the peripheral part 2 in an assembled state.

The shape of the periphery 2 of the conventional press-type or tension-type shadow mask is a shadow mask material without any treatment or is half-etched into a small circular shape as shown in FIGS. 2 and 5B. Divide by what you put.

In addition, there are two types of tensions, one-axis tension pulling only in the slit direction and two-axis tension applying tension in the slit direction and the slit vertical direction.

The most important management point in the tension mask is the tension distribution, the general distribution of which is shown in FIG. In FIG. 3, due to the structural characteristics of the frame, it is the lowest at the center of the screen and increases parabolically toward the periphery (a curve).

However, the strength of the periphery 2 in the case where the periphery 2 is no treatment or a circular treatment (as disclosed in the Utility Model Application Publication No. 999-36690 and for the purpose of dealing with springback, and the purpose is different) is the same. Rather, it is stronger than the mask intensity of the effective surface 1, so that the tension of the effective surface 1 in front of the peripheral portion 2 tends to decrease (b curve).

This decrease in tension may be a major cause of image blur when the color receiver is mounted on a TV set due to the influence of sound waves from surrounding speakers.

In an attempt to solve such a problem, the shadow mask disclosed in Japanese Patent Application Laid-Open No. 1998-51545 is provided to provide a mask for reducing stress, and the rail is fixed at a predetermined interval around the rail. Half etching is performed to the peripheral portions between the effective surfaces as in the prior art. While the stress applied to the shadow mask is increased by such a configuration, the stress concentration is dispersed to evenly distribute the force for deformation to the front surface, but such a configuration alone does not solve the above-mentioned problem correctly.

Accordingly, the present invention is to solve the above-described problems, in the shadow mask of one-way tension type to provide a shadow mask for color cathode ray tube that can be generated uniformly without lowering the tension force to improve the image quality There is a purpose.

1 is a schematic cross-sectional view showing the structure of a conventional shadow mask for a color cathode ray tube;

2 is a partial plan view of FIG.

3 is a tension distribution diagram of a conventional shadow mask for color cathode ray tubes;

4 is an explanatory diagram for explaining a state in which tension is applied;

5a and 5b are partial cross-sectional views showing the effective surface and the cross section of the periphery,

6a and 6b are a cross-sectional view and a plan view of the peripheral portion according to an embodiment of the present invention.

<Explanation of symbols about main part of drawing>

1: Effective plane 2: Peripheral

3: Skirt 21: Round Half Etching

31: Slit-shaped half etching part

In order to achieve the above object, a shadow mask for a color cathode ray tube according to an embodiment of the present invention comprises a pair of long sides and a pair of short sides and a frame detachably mounted on an inner wall of the panel, and with tension applied thereto. In the tension shadow mask-frame assembly of a one-way tension type color cathode ray tube having a shadow mask having end portions of the long sides fixed to the long sides of the frame and having a plurality of electron beam through holes formed therein: Slit-shaped half-etched portion is half-etched with the same pitch, width and height as the final slit of the surface, and the slit-shaped half-etched portion is preferably connected up and down through a bridge. .

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

4 is an explanatory diagram for explaining a state in which the tension is applied, Figures 5a and 5b is a partial cross-sectional view showing a cross section of the effective surface and the peripheral portion, Figure 6a and 6b is an embodiment of the present invention A cross-sectional view and a plan view of a periphery according to an example are shown.

As shown in FIG. 4, as the tension is applied, one side extension length of the shadow mask may be represented as ΔL.

The difference in the distribution of the tension force as shown in FIG. 3 is due to the imbalance of the force acting per unit area. As a method of applying the tension to the shadow mask, as shown in FIG. 4, the long side portion of the frame is compressed by ΔL (dotted line), and the shadow mask is welded, and then the force is removed, and the tension is applied by the force of the short side of the frame. This tensile force acts almost the same on the effective surface 1 and the peripheral part 2 when the rigidity of the long side part of a frame is large. Therefore, the nonuniformity of tension is caused by the cross-sectional area difference.

First, the cross-sectional area of the effective surface is examined as shown in FIG. 5.

The left and right surfaces on which the electron beam is incident are referred to as Δ1 and Δ2. In general, it is assumed that they vary depending on the distance but are the same (Δ1 = Δ2). Further, assuming that the inclinations μ1 and μ2 of the slits on the plane where the electron beam is incident are also the same, the forces acting per unit area are as follows.

Effective area (Ae) = (Ph-D) t-(2Δ1 t / 3 + μ1 t / 3)

Force acting per unit area (Je) = Fe / Ae

Where Ph is the horizontal pitch between the slits, D is the shortest width of the slit opening, and t is the thickness of the shadow mask.

Next, let's find out the force per unit area acting on the periphery (2). In FIG. 5B, σf = Ff / Af in the left view (porous processing). d is the force per unit area, Ff is the force acting on the periphery 2, and Af is the cross-sectional area of the periphery 2. Since Ff = Fe, there is a difference in the force acting as much as the difference between the cross-sectional areas Af and Ae. That is, since the width of the cross-sectional area of the periphery 2 is 15 to 20 times the pitch of the effective portion, it is Af # 20Ae, which is σf # 20σe.

In addition, even when the circular half-etching is performed, it can be confirmed that the force per unit area is 13 to 15 times larger than that of Je.

However, when the actual tension is applied, the force per unit area at the boundary between the periphery 2 and the effective surface 1 is only 5 to 8 times larger than the periphery 2. Therefore, if more than this force will be affected the tension of the effective surface (1).

In order to improve this, in the present invention, the shape of the peripheral portion 2 is precisely etched as follows so as not to affect the tension of the effective surface 1.

First, looking at the cross section, as shown in Fig. 6a, the half-etched cross section has the same structure as the effective surface, and the pitch Ph is designed to be the same as the final slit of the effective surface and half-etched only the hatched portions. As a result, only the dotted line portion of FIG. 6A becomes larger in area than the effective surface.

Calculating this, An = tD / 3 + tu / 3 = t (D + u) / 3, where D has a value of (0.25 to 0.28) Ph in relation to Ph and u typically has a value of t / 5. , An = 0.2t (0.25 to 0.28) / 3.

The thickness t of the currently used shadow mask is 0.1mm and the peripheral pH is 0.93, and it can be seen that An> 1.072Ae.

Therefore, sigma n> 1.072σe becomes possible to create a periphery that can protect the effective surface without affecting the tension.

It is also most effective to make the shape the same as the slit and the half-etching must be connected so that there is no short circuit of force (Figure 6b).

According to the configuration and operation of the shadow mask for color cathode ray tube according to the embodiment of the present invention described above, when the shadow mask of the present invention is mounted for tension, the cross-sectional area of the peripheral portion is similar to the effective surface (5 to 8% difference). Not only can the tension of the effective surface be sufficiently applied, but also the deformation due to external impact is similar, which has the effect of having strength in shock and vibration.

Claims (2)

A frame consisting of a pair of long sides and a pair of short sides and detachably mounted to the inner wall of the panel, and end portions of each long side are fixed to the long sides of the frame with tension applied, and a plurality of electron beam through holes are formed. In a tension shadow mask-frame assembly of a one-way tension type color cathode ray tube having a shadow mask that is: The slit-shaped half-etching portion 31 is half-etched with the same pitch, width and height as the final slit 11 of the effective surface 1 on the peripheral portion 2 of the shadow mask. Shadow mask for color cathode ray tubes. The shadow mask for a color cathode ray tube according to claim 1, wherein said slit-shaped half etching portion (31) is connected up and down through a bridge (32).