Flat cathode ray tube

Details Flat cathode ray tube Flat cathode ray tube

2001-04-09

2003-06-10

Day, Michael H. (Department: 2879)

Electric lamp and discharge devices

Cathode ray tube

Shadow mask, support or shield

C313S402000

Reexamination Certificate

active

06577051

ABSTRACT:

CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for SHADOW MASK FRAME FOR CRT earlier filed in the Korean Industrial Property Office on Apr. 10, 2000 and there duly assigned Ser. No. 2000-18564.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cathode-ray tube (CRT), and more particularly, to a flat cathode-ray tube that has a simplified process of connecting a shadow mask and a shadow mask frame that is solidified.
2. Description of the Background Art
Generally, a cathode-ray tube displays a picture by exciting a phosphor layer such that electron beams emitted from an electron gun lands on the phosphor layer through electron beam apertures of a shadow mask having a color selection function.
Only approximately 20% of the electron beam emitted from the electron gun pass through the electron beam apertures of the shadow mask to then land on the phosphor layer, and the remaining 80% collide with the shadow mask. The electron beams colliding with the shadow mask cause a doming phenomenon in which the shadow mask heated by the colliding electron beams experiences thermal deformation.
If the doming phenomenon occurs, the electron beams emitted later may not precisely land on the phosphor layer. Also, the shadow mask and the screen are formed to have a predetermined curvature, thereby narrowing the angle of viewing and distorting a picture at the periphery of the screen.
To solve the above-described problems, there has been developed a flat cathode-ray tube having a flat screen surface. The flat cathode-ray tube is constructed such that a panel where the phosphor layer is formed is formed in a flat type and the shadow mask is secured to the panel in a state in which a predetermined tension is applied to the shadow mask.
Japanese Patent Publication No. 7-296738, issued to Araya for Color Cathode-ray Tube discloses a flat cathode-ray tube having a shadow mask connected to a shadow mask frame. The shadow mask frame has a shadow mask supported to its one plane. The shadow mask has a plurality of holes, and is secured to the frame in a state in which a tension is applied thereto in every direction. A support member for supporting the lateral surfaces of the frame, is installed on the inner sides of the frame for the purpose of preventing restoration of the tension applied to the shadow mask.
The process of securing the shadow mask to the shadow mask frame will now be described briefly. In a state in which tension is applied to the whole surface of the shadow mask frame, the shadow mask is welded to the shadow mask frame. Then, in order to prevent the shadow mask from being deformed due to restoration of tension, rectangular panels are welded to the inner surface and rear surface of the shadow mask frame. Accordingly, the warping stress, by which the lateral surface of the shadow mask frame is warped inwardly, can be resisted, thereby maintaining the tensile strength of the shadow mask continuously.
However, since the cathode-ray tube is constituted by a plurality of structures, that is, the mask frame for primarily supporting the tensile strength of the shadow mask, and panels for supporting the mask frame, the configuration of the cathode-ray tube becomes complex, and a dispersion error in the design dimension may increase during the manufacture course thereof.
Also, since a welding process is employed in connecting the mask frame and an inner shield (not shown), the operational process becomes complicated, and much time and cost are required, resulting in poor manufacturability.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a flat cathode-ray tube (CRT) having an improved strength by welding a shadow mask frame using boards of many folds, an improved tensile strength of a shadow mask supported by cutting the corners of the shadow mask frame, and enabling a simplified assembling operation with an inner shield.
It is another object to have a cathode-ray tube assembly that prevents the deformation of the mask frame.
It is yet another object to have a cathode-ray tube assembly that reduces the effects of the doming phenomenon.
It is still yet another object to have a flat cathode-ray tube that delivers a very high quality image with reduced distortions.
Accordingly, to achieve the above objects, there is provided a flat cathode-ray tube assembly including a shadow mask having a plurality of electron beam holes, a shadow mask frame having multi-layered support members continuously connected, for supporting the shadow mask, and an inner shield connected to the shadow mask frame.
Preferably, the support member has an L-shaped cross section and has a vertical part connected to the shadow mask and a horizontal part bent and axially extending from the vertical part. Also, a plurality of holes into which clips for connecting the inner shield are preferably formed on the horizontal part. Further, one plane of the shadow mask is preferably connected to rising edges of the multiple-layered plane of the support member by welding. The respective layers of the support member are preferably made of materials having the same coefficient of thermal expansion.
Since the flat cathode-ray tube having the aforementioned configuration is fabricated by a support member of multiple boards, it is remarkably strong compared to the case of using a single-board support member. Also, since the corners of the support member is partially cut, the support member can be pressed with a predetermined force, thereby easily applying tension to the shadow mask supported thereby. Further, since the shadow mask frame is simply assembled with the inner shield using clips in the holes formed on the horizontal part thereof, the manufacturing process of the cathode-ray tube can be simplified.


REFERENCES:
patent: 4665338 (1987-05-01), Inaba et al.
patent: 5698938 (1997-12-01), Kim et al.
patent: 5898259 (1999-04-01), Reyal
patent: 7-296738 (1995-11-01), None

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