GB2228364A

GB2228364A - Support for tensioned shadow mask of flat panel colour tube

Info

Publication number: GB2228364A
Application number: GB8929340A
Authority: GB
Inventors: Jae-Ho Lee
Original assignee: Samsung Electron Devices Co Ltd
Current assignee: Samsung SDI Co Ltd
Priority date: 1988-12-31
Filing date: 1989-12-29
Publication date: 1990-08-22
Also published as: GB8929340D0; FR2641415A1; NL8903035A

Abstract

A supporting structure for a shadow mask (3) of a flat panel type colour picture tube is disclosed which is characterized in that: the peripheral portions (1a) of the panel (1) are bent rearwardly to form a flange portion, and a plurality of stud pins (7) are provided to this flange portion; the shadow mask is coupled with a frame (4) in a state with a tension of a certain level applied between them so as for a shadow mask assembly to be formed; a plurality of springs (5) having coupling holes are provided along the periphery of the shadow mask assembly at the positions corresponding to the above mentioned stud pins; and the stud pins of the panel and the springs of the shadow mask assembly are coupled each other, in such a manner that the shadow mask assembly should be elastically supported to the panel. Thus manufacture is simplified and detaching and reassembly of the shadow mask assembly are facilitated. <IMAGE>

Description

SUPPORTING STRUCTURE FOR SHADOW MASK OF FLAT PANEL TYPE COLOR PICTURE TUBE The present invention relates to a supporting structure for a shadow mask of a flat panel type color picture tube, and particularly to a supporting structure for a tension type shadow mask.

The flat panel type color picture tube is superior in its visual characteristics over the usual parabolic surface type color picture tube, owing to the fact that the amount of the light rays reflected from its panel is smaller than that of the latter. Meanwhile, as this flat panel type color picture tube has a flat panel, its shadow mask has also to be flat. But such a flat shadow mask can produce thermal deformations such as doming and twisting due to the radiation of the election beams, and therefore, the shadow mask for a flat panel type color picture tube has been used in the form of the so-called tension type mask which is coupled with the frame in a state with a certain level of tension applied.

Figure 1 illustrates an example of the conventional color picture tube provided with a tension type mask, which is disclosed in U.S. Patent publication No. 4,701, 666.

This picture tube is constituted such that a shadow mask 13 is secured to a frame 14 in a state with a certain level of tension applied, thereby forming a shadow mask assembly 12. This shadow mask assembly 12 is disposed between a funnel 6 and a panel 11 coated with a phosphor layer 11a and the like, and is secured by spreading a thermosetting crystalline powdered glass F which is generally called frit, and by carrying out a baking.

However, such a conventional supporting structure for the shadow mask permanently and unitedly fixes the shadow mask assembly with the panel and the funnel, and therefore, various problems as described below are accompanied.

That is, the shadow mask assembly has to be attached to the panel coated with a phosphor layer, and therefore, contaminations of the phosphor layer are liable to occur due to the foreign materials introduced during the attaching process, thereby making the product defective. In the case where such a defect is found, it is impossible to detach the shadow mask assembly from the panel and to re-assemble them although it was wished to remove the defect-causing factor.

Further, in the case where defects such as the blockings of the holes of the shadow mask or defects of phosphor layer are occurred, the expensive panel and shadow mask assembly have all to be discarded because they can not be salvaged.

Further, in its manufacturing process, additional steps such as the spreading of frit and the baking are involved which are absent in the manufacturing process for the conventional parabolic surface type color picture tube, thereby requiring the installation of additional production facilities. Further, the natures of the additional works are of heterogeneous kinds, and therefore, particularly skilled workers and special jigs are required, thereby increasing the manufacturing cost.

Therefore, it is an object of the present invention to provide a supporting structure for a shadow mask of a flat panel type color picture tube, in which detachings and assembling can be easily carried out.

It is another object of the present invention to provide a supporting structure for a shadow mask of a flat panel type color picture tube, in which the assembling is possible on the production line which is same as that for the parabolic surface type color picture tube.

In achieving the above objects, the supporting structure for a shadow mask of a flat panel type color picture tube is constituted such that: the peripheral portions of the panel are bent rearwardly to form a flange portion, and a plurality of stud pins are provided to this flange portion; the shadow mask is coupled with a frame in a state with a tension of a certain level applied to it so as for a shadow mask assembly to be formed; a plurality of springs having coupling holes are provided along the periphery of the shadow mask assembly at the positions corresponding to the above mentioned stud pins; and the stud pins of the panel and the springs of the shadow mask assembly are coupled each other, in such a manner that the shadow mask assembly should be elastically supported to the panel.

The above objects and other advantages of the present invention will become more apparent by describing in detail the preferred embodiment of the present invention with reference to the attached drawings in which: Figure 1 is a sectional view showing the structure of a conventional flat panel type color picture tube, with a portion of it enlarged; Figure 2 is a sectional view showing the structure of the flat panel type color picture tube provided with the supporting structure for shadow mask according to the present invention, with a portion of it enlarged; and Figure 3 is a perspective view showing a part of the shadow mask frame and the springs attached on it.

The supporting structure for the shadow mask of a flat panel type color picture tube according to the present invention illustrated in Figure 2 is provided with a flange portion la which is formed by being bent at the periphery of the face plate of a panel 1 toward a funnel 6, and the flange portion la is provided on the inner face thereof with a plurality of stud pins 7 preferably in the number of four in such a manner that the stud pins 7 should be directed inwardly.

Meanwhile, a shadow mask assembly 2 which is a combination of a frame 4 and a shadow mask 3 is provided with a plurality of springs 5 made of an elastic material and having coupling holes 5a for being coupled with the stud pins 7, the springs 5 being disposed along the periphery of the assembly 2 at the positions corresponding to the positions of the stud pins 7, as shown in Figure 3.

The shadow mask assembly 2 should be the so-called pretensed shadow mask in which the shadow mask 3 is coupled with the frame 4 in a state with a tension of a certain level applied between them. The shadow mask assembly particularly suitable for carrying out the present invention is that which is disclosed in Korea Patent Application No.

88-11691 which is invented by the present inventor and assigned to the present applicant, and this shadow mask assembly is manufactured by pre-heating the shadow mask to a temperature of 150"C , and by coupling this pre-heated shadow mask to a frame in such a manner that a tension should be formed during the cooling of them, thereby providing a property of withstanding against thermal deformations such as doming and the like during use.

Meanwhile, the springs 5 which are attached on the shadow mask assembly 2 may be made of a simple elastic material, but they also can be made of a bimetal. In the case where the springs 5 are made of a bimetal material, thermal deformations will be compensated both by the tensed mask and by the springs.

The supporting structure for shadow mask according to the present invention constituted as above can be assembled in such a manner that the springs 5 attached to the external surface of the shadow mask assembly 2 are pressed and are positioned so as for the coupling holes 5a to be mated with the stud pins 7 of the panel 1, and then, the pressure applied to the springs 5 are released, so that the coupling holes 5a and the stud pins 7 should be coupled each other, and that shadow mask assembly 2 should be supported by the panel 1.

The shadow mask assembly assembled as described above can be disassembled or re-assembled from and the the panel according to the need such as cleaning or salvaging, by applying a reverse procedure of the above described assembling procedure.

The adoption of the shadow mask supporting structure according to the present invention enables that only the panel can be discarded upon finding of a defect on the panel, and in the cases of cleaning, salvaging or holeblockings of the shadow mask, the shadow mask assembly can be conveniently disassembled.

Meanwhile, in its manufacturing process also, a heterogeneous process which is not seen in the conventional parabolic surface type color picture tube is not included, and therefore, no additional facility or particularly skilled man power is required, with the result that the same production line as that for the conventional parabolic surface type picture tube can be used to produce the device of the present invention, thereby greatly contributing to improving the productivity and to saving the manufacturing cost.

Claims

CLAIMS:

1. A supporting structure for a shadow mask of a flat panel type color picture tube, comprising a tensed shadow mask supported to a panel, characterized in that the peripheral portions of said panel are bent rearwardly to form a flange portion, and a plurality of stud pins are provided to said flange portion; a shadow mask is coupled with a frame in a state with a tension of a certain level applied between them so as for a shadow mask assembly to be formed; a plurality of springs having coupling holes are provided along the periphery of said shadow mask assembly at the positions corresponding to the positions of said stud pins; and said stud pins of said panel and said springs of said shadow mask assembly are coupled each other, in such a manner that said shadow mask assembly should be elastically supported to said panel.

2. A color picture tube having a shadow mask disposed behind the front panel of the tube, wherein said shadow mask is pretensioned and is peripherally attached to a peripheral support frame, said frame having mounting means cooperable with corresponding mounting means on the inside of the tube for detachably mounting said support frame behind said front panel.

3. A supporting structure for a shadow mask of a flat panel type color picture tube, substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings.