Funnel for color CRT

Details Funnel for color CRT Funnel for color CRT

2001-10-15

2003-09-02

Wong, Don (Department: 2821)

Electric lamp and discharge devices: systems

Cathode ray tube circuits

C315S366000, C313S47700R

Reexamination Certificate

active

06614189

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a funnel for a color CRT, and more particularly, to a funnel for a color CRT that is capable of reducing a deflection power as well as a leakage magnetic field by modifying a structure of a yoke portion in which a deflection yoke is mounted.
2. Description of the Background Art
FIG. 1
is a partially cut side view showing an internal construction of a color CRT, and
FIG. 2
is a sectional view taken along line A—A of
FIG. 1
, showing a structure of a yoke portion of a funnel of the color CRT in accordance with a conventional art.
With reference to
FIG. 1
, As shown in
FIG. 1
, a color CRT is formed with its external appearance by a panel
10
coated with a red, green and blue color fluorescent material
11
on the inner face thereof, and a funnel
20
sealed at the rear side of the panel
10
and maintaining an internal pressure in a high vacuum state.
A shadow mask
40
serving for color selection is mounted at the inner side of the panel
10
through the medium of a frame
30
.
An inner shield
60
for shielding a magnetic field such as an earth magnetic field so that an electron beam (B) injected from an electron gun
80
is not influenced by the magnetic field is mounted at a rear side of the frame
30
.
Especially, the funnel
20
includes a body portion
21
coupled to the panel
10
, a neck portion
23
into which the electron gun
80
is installed, and a yoke portion
25
in a cone shape formed between the body portion
21
and the neck portion
23
.
A deflection yoke
50
for deflecting the electron beam (B) injected from the electron gun
80
to the entire fluorescent surface
11
is mounted at the yoke portion
25
.
In the color CRT, as the electron beam (B) irradiated from the electron gun
80
is deflected in the horizontal and the vertical direction by a static magnetic field of the deflection yoke
50
, it collides with the fluorescent surface
11
formed at the inner surface of the panel
10
, radiating the fluorescent material, so that an image is reproduced.
A cut-out section of the yoke portion
25
of the funnel
20
is typically formed to have a circular structure. But, in this respect, in order to reduce a power consumption of the deflection yoke
50
, the maximum power consumption source, as shown in
FIG. 3
, a yoke portion
25
′ of a funnel
20
′ is formed to have a non-circular structure.
As a measure for minimizing the deflection power of the color CRT, the yoke portion
25
′ of the funnel
20
′ is designed in the following range.
With reference to
FIGS. 4 and 5
, on the assumption that a long axis length of the outer face of the yoke portion
25
′ is ‘H’, a short axis length of the outer face of the yoke portion
25
′ is ‘V’, a diagonal length of the outer face of the yoke portion
25
′ is ‘L’, &Dgr;H=L−H, &Dgr;V=L−V, &Dgr;HV=&Dgr;H+&Dgr;V, the yoke portion is designed in the range of 0.3<&Dgr;HV/L<0.6.
However, the conventional designing range of the yoke portion is designed to be optimized in a color CRT of which screen ratio is 4:3, it is hardly optimized to be adoptable to a high definition television having a screen ratio of 16:9.
In other words, reduction of a power consumption in the deflection yoke, the maximum power consumption source, of the typical color CRT is a critical matter. In this respect, however, in order to improve a luminance of the fluorescent material of the color CRT, an anode voltage for accelerating the electron beam should be resultantly increased, it is difficult to reduce the power consumption of the deflection yoke.
Especailly, in case of a color CRT having the screen ratio of 16:9 such as the HDTV, a higher deflection force than that of the CRT having the screen ratio of 4:3, and at this time, the deflection frequency should be raised, causing problems that a deflection power is increased and a deflection magnetic field is readily leaked outside the CRT because of the deflection force caused due to the high frequency.
In addition, in line with the strengthened regulation for the leakage magnetic field, a compensation coil is additionally installed to reduce the leakage magnetic field, which, however, makes the structure of the color CRT more complicate and increases the power consumption.
As a result, the designing range of the yoke portion
25
′ in accordance with the convention is not suitable to the color CRT having the screen ratio of 16:9.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a funnel for a color CRT that is capable of reducing a deflection power and a leakage magnetic field while satisfying a high luminance or a high frequency by optimizing a design range of a yoke portion in case that a screen ratio is about 16:9.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a color CRT of which a funnel has a body portion coupled to a panel, a neck portion in which an electron gun is installed and a yoke portion connecting the body portion and the neck portion and having a deflection mounted therein, wherein the outer face of the yoke portion satisfies a relational expression of 0.6<&Dgr;HV/L<0.71, of which ‘L’ indicates a diagonal length of an outer face of the yoke portion, ‘H’ indicates a long axis length of the outer face of the yoke portion, ‘V’ indicates a short axis length of the outer face of the yoke portion, &Dgr;H indicates a difference between the diagonal length ‘L’ and the long axis length ‘H’, &Dgr;V indicates a difference between the diagonal length ‘L’ and the short axis length ‘V’, &Dgr;HV indicates the sum of &Dgr;H and &Dgr;V.
In the funnel of a color CRT of the present invention, the outer face of the yoke portion satisfies a relational expression of 0.64<&Dgr;HV/L<0.71.
In the funnel of a color CRT of the present invention, the yoke portion is formed in an about square shape, and the corner portion is thicker than both side portions and upper and lower portions.
In the funnel of a color CRT of the present invention, a sectional area from a reference line to the outer face of the yoke portion is 900~1200 mm
2
.
To achieve the above objects, there is also provided a color CRT having a body portion coupled to a panel, a neck portion in which an electron gun is installed and a yoke portion formed to be connected between the body portion and the neck portion and in which a deflection coil is mounted, wherein the yoke portion satisfies a relational expression of 0.6<&Dgr;H′V′/L′<0.71, of which ‘L′’ indicates a diagonal length of an inner face of the yoke portion, ‘H′’ indicates a long axis length of the inner face of the yoke portion, ‘V′’ indicates a short axis length of the inner face of the yoke portion, &Dgr;H′ indicates a difference between the diagonal length ‘L′’ and the long axis length ‘H′’, &Dgr;V′ indicates a difference between the diagonal length ‘L′’ and the short axis length ‘V′’, &Dgr;H′V′ indicates the sum of &Dgr;H′ and &Dgr;V′.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 5859508 (1999-01-01), Ge et al.
patent: 6002203 (1999-12-01), Yokota et al.
patent: 6208068 (2001-03-01), Lee et al.
patent: 6335594 (2002-01-01), Park

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