KR20010090984A - Mask frame for CRT - Google Patents

Abstract

PURPOSE: A mask frame for CRT is provided to reduce cost and thickness of CRT by improving the shape of stiffening member and reducing the height of shadow mask frame. CONSTITUTION: A mask frame for supporting a shadow mask(4) applied with a tensile force, and which is installed inside of a panel with a support spring attached to the mask frame, comprises support members(16,16') to be coupled with the shadow mask, and which have L-shaped cross sections; and stiffening members(18,18') coupled to each end of supporting members, in such a manner that stiffening members are pressed in axial direction and bent to have a predetermined curvature in the direction parallel with the support members. The shadow mask has a plurality of openings(4a) for passage of electron beam emitted from an electron gun of CRT.

Description

Mask frame of cathode ray tube {Mask frame for CRT}

The present invention relates to a mask frame of a cathode ray tube, and more particularly to a mask frame of a cathode ray tube having an improved mounting structure of a shadow mask.

In the cathode ray tube, the electron beam emitted from the electron gun has a color discrimination function, and is landed on the fluorescent film through the electron beam through hole of the shadow mask which is spaced apart from the fluorescent film by a predetermined distance, thereby exciting the fluorescent film to form an image.

The screen surface of the conventional cathode ray tube forming the image as described above is designed to have a predetermined curvature in consideration of the deflection trajectory of the electron beam when the electron beam emitted from the electron gun is deflected by the deflection yoke, and thus the shadow mask screen surface It is designed to have a curvature that corresponds to the curvature of. In the conventional cathode ray tube, a shadowing mask is heated by an electron beam, ie, hot electrons, emitted from the electron gun, and a swelling phenomenon occurs in the panel side. This doming phenomenon causes the electron beam not to land on the fluorescent film accurately, and is formed to have a predetermined curvature on the screen surface, so that the viewing angle is narrowed and the image is distorted at the edge of the screen surface.

In order to solve the problems as described above, the planar cathode ray tube having a flat screen surface is formed on a flat plate with a fluorescent film formed thereon and fixed to the panel in a state where a predetermined tensile force is applied to the shadow mask. In this state, the panel is fixed with a funnel equipped with an electron gun and a deflection yoke.

4 shows an example of a mask frame assembly in which a shadow mask is mounted in such a planar cathode ray tube. The shadow mask frame having the above structure is a model mainly applied to US 5426380, US 5532546 and US 5702280 filed by Sony of Japan.

In the figure, the shadow mask frame assembly 2 of the conventional planar cathode ray tube is largely divided into the shadow mask 4, the support members 6, 6 'and the rigid members 8, 8'. The supporting members 6 and 6 'are simple beams having an approximately L-shaped cross section, and the material mainly uses an alloy such as chromium-molybdenum steel. An approximately U-shaped rigid member 8, 8 'is welded to the lower ends of both ends of the support members 6, 6'.

The rigid members 8 and 8 'have a hollow square tube shape and are curved at a predetermined distance from the welded ends of the supporting members 6 and 6'. The rigid members 8, 8 'are usually made of a material which is elastic and does not have a high coefficient of thermal expansion.

The shadow mask 4 is attached to the upper surface of the supporting members 6 and 6 ', and the long side end 4a of the shadow mask is welded and attached. At this time, the shadow mask 4 is applied a tensile force in the axial direction of the short side and the rigid member (8) (8 ') is to support the tensile force.

However, when the rigid members 8 and 8 'are normally shaped to support the tension of the shadow mask 4 and assembled to the face panel of the cathode ray tube, the rigid members 8 and 8' are out of the face panel. In order to solve this problem, the face panel has to be thick, the production cost increases, and the appearance of the CRT becomes poor.

The present invention devised to solve the above-mentioned problems of the prior art is to improve the rigid member of the shadow mask frame of the planar cathode ray tube to a single beam of simple (-) shape to reduce the height of the shadow mask frame shadow of the cathode ray tube It is an object of the present invention to provide a mask frame and a method of manufacturing the same.

In the mask frame of the cathode ray tube for achieving the object of the present invention supports the shadow mask is applied a tension of a predetermined pressure, in the mask frame of the cathode ray tube suspended in the panel via a support spring, the shadow mask is And a rigid member coupled to an end of the supporting member, wherein the rigid member is pressurized in the axial direction so that the rigid member is bent to have a predetermined curvature in a direction parallel to the supporting member. .

The bending radius of curvature of the rigid member is in the range of 10,000 to 50,000 mm, has a yield stress of 600 to 800 mPa, and a shear stress of 700 to 800 mPa.

The Poisson's ratio B / A = 0.25 to 0.35 with respect to the compressive force B of the support member and the elastic force A of the rigid member, wherein the rigid member is made of a material having a smaller coefficient of thermal expansion than the shadow mask.

The shadow mask frame of the planar cathode ray tube manufactured by the above-described configuration and method can be easily assembled to the face panel because the height of the mask frame is greatly reduced, and the side depth of the face panel surrounding the mask frame can also be reduced. It can reduce the thickness and improve productivity.

1 is an exploded perspective view showing a mask frame of a cathode ray tube according to the present invention.

2 is a view showing a form of pressing the rigid member before attaching the shadow mask to the mask frame.

3 is a view showing a mask frame in which a rigid member has a predetermined amount by pressing the rigid member;

4 is a view showing a state in which a shadow mask is attached to the mask frame of FIG.

5 is a perspective view illustrating a mask frame to which a tensile force is applied;

Figure 6 is an exploded perspective view showing the separation of the cathode ray tube to which the mask frame of the present invention is applied.

7 is a perspective view showing a mask frame of a conventional cathode ray tube.

** Explanation of symbols for main parts of drawings **

4: shadow mask 16,16 ': support member

18,18 ': Rigid member 20: Mask frame assembly

20a: spring 30: cathode ray tube

32: fluorescent film 34: face panel

36: Inner Shield 38: Funnel

39: deflection yoke 68: mask frame

EMBODIMENT OF THE INVENTION The structure of this invention is demonstrated in detail based on attached drawing. For reference, prior to the description of the present invention will be referred to the same reference numerals as for the parts corresponding to the conventional drawings.

1 illustrates a preferred embodiment of a mask frame assembly 20 in which a shadow mask is attached and supported to a mask frame 68 of a cathode ray tube according to the present invention.

Referring to the drawings, the shadow mask frame assembly 20 is welded to two support members 16 and 16 'having an approximately L-shaped cross section and both end surfaces of the support members 16 and 16'. And a mask frame 68 composed of two rigid members 18 and 18 having a shape, and a shadow mask 4 welded to an upper end of the support members 16 and 16 '.

The shadow mask 4 is a flat plate-like thin plate and has a generally rectangular structure, and a plurality of holes 4a are formed on the inner side except for a part of the edge. The hole 4a is an electron beam passing hole 4a through which an electron beam emitted from an electron gun (not shown) of the cathode ray tube passes, and is formed in a dot or slit shape according to the purpose of manufacturing the cathode ray tube.

The support members 16 and 16 'are usually made of chromium-molybdenum steel and other alloy steels, and the long side end of the shadow mask 4 is welded to the upper surface thereof, and the supporting force of the rigid members 18 and 18' is applied. The shadow mask 4 is supported by this.

The rigid members 18, 18 'are located on the same plane as the support members 16, 16' and are generally tubular in order to reduce weight. The shadow mask 4 is welded to the upper surface of the support member 16, 16 ′, and the rigid member 18, 18 ′ is bent by applying a predetermined force from both sides in the axial direction and then the shadow mask 4. Attach the long side of the.

The bending radius of curvature of the rigid member is in the range of 10,000 to 50,000 mm. The rigid member has a yield stress of 600 to 800 mPa and a shear stress of 700 to 800 mPa.

Poisson's ratio (B / A) with respect to the compressive force (B) of the support member and the elastic force (A) of the rigid member is in the range of 0.25 to 0.35. In addition, the rigid member is preferably a material having a smaller coefficient of thermal expansion than the shadow mask.

The shadow mask 4 of FIG. 1 is attached to the mask frame 68 by applying a tensile force to the shadow mask 4 with reference to FIGS. 2 and 3.

FIG. 2 illustrates a state in which an axial direction of the rigid members 18 and 18 ′ is applied to the mask frame 68 before the shadow mask 4 is attached, and FIG. 68 is a view showing.

Referring to the drawings, the rigid members 18 and 18 'which are welded to both ends of the support members 16 and 16' are applied in the axial direction of the rigid members 18 and 18 '. By the applied pressure, the rigid members 18, 18 'are bent while forming a weak curvature toward the outside of the supporting members 16, 16 side, and the supporting members 16, 16' are supported by the pressure. The distance between the members 16 and 16 'is close to each other.

At this time, the amount of pressure to be applied is pressed up to the yield stress of the rigid members 18 and 18 ', and the radius of curvature of the rigid members 18 and 18' formed by the pressing force is about 10,000 to 50,000. It should fall within the range of mm.

FIG. 4 shows a state in which the shadow mask 4 prepared in the mask frame 68 pressed in the axial direction of the rigid members 18 and 18 'is welded as described above.

As shown in the drawing, when welding the shadow mask 4, the shadows are formed on the upper surfaces 16a and 16a 'of the support members 16 and 16' while both ends of the rigid members 18 and 18 'are pressed. The long side portion 4b of the mask 4 is welded. The welding method is preferably resistance welding or laser welding.

FIG. 5 illustrates a shape in which the shadow mask 4 welded to the mask frame 68 receives a tensile force while the rigid members 18 and 18 ′ of the mask frame 68 are restored as described above.

The rigid members 18, 18 ', which have been pressed to the previous stage of yield stress, are restored to their original form by their restoring forces. As the rigid members 18 and 18 'are restored, the distance between the supporting members 16 and 16', which has been reduced by a certain amount by the pressing force, increases to its original position, thereby welding the supporting members 16 and 16 '. The shadow mask 4, which has been used, also generates tension in the short side direction.

5 shows the cathode ray tube 30 to which the shadow mask frame assembly 20 according to the present invention is applied.

As shown in the drawing, the cathode ray tube 30 has a face panel 34 having a flat screen surface having a fluorescent film 32 formed therein, and a stud pin 34a fixed to an inner surface of the face panel 34. ). In addition, a mask frame assembly 20 is installed on the inner surface of the face panel 34 so as to be spaced apart from the fluorescent film 32 by a predetermined distance.

The mask frame assembly 20 may include a mask frame 68 having a spring 20a mounted on an outer circumferential surface thereof and coupled to the stud pins 34a, respectively, and the support members 16 and 16 'of the mask frame 68. It includes a shadow mask (4) fixed to the upper surface. The shadow mask 4 is attached to the support members 16, 16 ′ of the mask frame 68 with tensile force applied by the rigid members 18, 18 ′ of the mask frame 68.

An inner shield 36 and a funnel 38 are assembled on the rear surface of the mask frame assembly 20 including the shadow mask 4, and a circumference of the neck portion 38a is formed on the neck portion 38a of the funnel 38. A deflection yoke 39 is mounted to deflect the electron beam of the electron gun (not shown).

The electron beam emitted from the electron gun is deflected by the deflection yoke 39 to pass through the electron beam through hole 4a of the shadow mask 4 and to be landed on the fluorescent film 32 to realize a desired image.

The shadow mask 4 is mounted on the mask frame 68 in a state in which tensile force is applied, so that the shadow mask 4 is expanded by high temperature during the blackening process. The blackening is to form a blackening film (Fe3O4) on the surface of the shadow mask (4), the mask frame 68 and the inner shield 36 to prevent diffuse reflection, heat absorption and diffuse reflection of the exposure beam during the process.

However, since the thermal expansion coefficients of the rigid members 18 and 18 'are lower than the thermal expansion coefficient of the shadow mask 4, the expansion of the shadow mask is suppressed by the rigid members 18 and 18' during the blackening process, and thus the same tension as before the blackening process. Will be maintained.

Also, the electron beam emitted from the electron gun passes through the shadow mask 4 to about 20% of the total electron beam and the remaining about 80% of the electron beam impinges on the shadow mask 4. As such, the electron beam impinging on the shadow mask 4 heats the shadow mask 4, and thus the shadow mask 4 undergoes thermal deformation, thereby causing a dominant phenomenon. When the shadow mask 4 has a tensile force applied thereto, The occurrence of the phenomenon can be suppressed.

The mask frame 68 of the cathode ray tube according to the above-described configuration can improve the rigid members 18 and 18 'into a simple beam shape having a single (-) shape, thereby significantly reducing the height of the mask frame 68. Accordingly, the manufacturing process of the cathode ray tube 30 is also simplified, and thus the effect of reducing cost and improving productivity can be obtained.

By improving the shape of the rigid member to a simple beam form, it is possible to significantly reduce the height of the mask frame, thereby reducing the depth of the face panel can reduce the cost and the thickness of the cathode ray tube.

Claims (7)

In a mask frame of a cathode ray tube which supports a shadow mask to which a tension of a predetermined pressure is applied and is suspended inside a panel via a support spring, And a support member to which the shadow mask is coupled, and a rigid member coupled to an end of the support member, wherein the rigid member is pressed in an axial direction and coupled in a bent state to have a predetermined curvature in a direction parallel to the support member. Mask frame of the cathode ray tube, characterized in that. The mask frame of claim 1, wherein the rigid member is disposed on the same plane as the support member. The mask frame of a cathode ray tube according to claim 1, wherein the bending radius of curvature of said rigid member is in the range of 10,000 to 50,000 mm. The mask frame of a cathode ray tube according to claim 1, wherein the rigid member has a yield stress of 600 to 800 mPa. The mask frame of a cathode ray tube according to claim 1, wherein the rigid member has a shear stress of 700 to 800 mPa. The mask frame of a cathode ray tube according to claim 1, wherein the Poisson's ratio B / A = 0.25 to 0.35 with respect to the compressive force (B) of the support member and the elastic force (A) of the rigid member. The mask frame of a cathode ray tube according to claim 1, wherein the rigid member has a coefficient of thermal expansion smaller than that of a shadow mask.