Electric lamp and discharge devices – Cathode ray tube – Shadow mask – support or shield
Reexamination Certificate
1998-01-09
2001-02-13
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Shadow mask, support or shield
C313S402000
Reexamination Certificate
active
06188169
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an aperture grill supporting frame and a method for manufacturing thereof, more particularly to an aperture grill supporting frame which is used for an in-line cathode ray tube to support an aperture grill with a grid of longitudinal slits.
2. Prior Art
To take an example, the television receiver incorporates a cathode ray tube. As such cathode ray tube, the in-line cathode ray tube is well known in which three electron beams are arranged to be in-line, namely, arranged to form a row in a horizontal direction.
This in-line cathode ray tube is provided with a three-beam electron gun based on unit electron guns to emit three electron beams which are arranged in a horizontal line, a convergence electrode to converge the electron beams emitted from the electron gun, a deflecting yoke to deflect the electron beams, a color sorting mechanism having an aperture grill with a grid of longitudinal slits, and a glass bulb which has a phosphor screen which has its surface coated in longitudinal parallel lines with phosphors giving red, green and blue lights.
With this cathode ray tube, the electron beams emitted from the electron gun, after having been converged by the convergence electrode, are deflected by the deflecting yoke in horizontal and vertical directions in synchrony with horizontal and vertical synchronization signals, and are scanned over the whole surface of the phosphor screen.
The electron beams which have been deflected by the deflecting yoke have their unnecessary portion masked by the color sorting mechanism. Namely, the color sorting mechanism passes only the fraction of electron beams which have been designed to be directed onto the phosphor screen. The electron beams having passed the color sorting mechanism properly strike against red, blue and green phosphors, causing them to illuminate to display a color image on the screen.
The color sorting mechanism consists of an aperture grill with a grid of longitudinal slits, an aperture grill supporting frame which supports the aperture grill by stretching it in a horizontal direction, damper wires which are placed in contact with thin tapes constituting the aperture grill to give them axially acting forces, and damper springs which stretch both ends of damper wires.
FIG. 1
illustrates the aperture grill supporting frame
42
and aperture grill
41
.
FIG. 1A
gives a frontal view of the aperture grill supporting frame
42
and aperture grill
41
,
FIG. 1B
a lateral view of the aperture grill supporting frame
42
, and
FIG. 1C
a bottom view of the aperture grill supporting frame
42
and aperture grill
41
.
The aperture grill
41
is produced after a rolled plate material has been subject to photoetching to produce slits in the form of a grid of longitudinal lines, and parts between adjacent slits are occupied by thin tapes. Namely, the aperture grill
41
takes the form of an assembly of thin tapes. As will be described later, this aperture grill
41
is welded, while being kept stretched in a vertical direction or in a Y-axis direction, to the aperture grill supporting frame
42
. The damper wires are made of, for example, tungsten wire, and are placed such that their direction is normal to the long axes of the slits of the aperture grill
41
. Both ends of these damper wires are stretched by damper springs mounted to the aperture grill supporting frame
42
. By virtue of the tension from the damper springs, the damper wires are placed in contact with individual thin tapes constituting the aperture grill
41
to give a vertically acting force to each of the thin tapes. Thus, the damper wire prevents the thin tapes of aperture grill
41
from being put into vibration by, for example, a certain external vibrating source, through the friction generated by their contact with individual thin tapes. Namely, the damper wires exert a uniformly acting anti-vibration effect on the whole surface of the aperture grill
41
by giving uniformly acting forces on individual thin tapes of the aperture grill
41
.
The aperture grill supporting frame
42
consists of upper and lower frames
45
and
46
which together support the aperture grill
41
by stretching it in a horizontal direction, and side frames
47
and
48
which are connected to the upper and lower frames
45
and
46
at their ends. The upper and lower frames
45
and
46
have a cross-section in the form of an inverted L as shown in
FIG. 1B
, and are generally shaped as a rod.
The surfaces
45
a
and
46
a
(to be referred to as surfaces for welding hereinafter) of upper and lower frames
45
and
46
of aperture grill supporting frame
42
, through which the aperture grill
41
is welded to the supporting frame, have been so processed as to give a part of a columnar wall surface with a radius of R as is seen from
FIG. 1C
, and
FIG. 2A
which gives an enlarged view of part A of FIG.
1
C. Then, for example, on respective four points of the upper and lower frames
45
and
46
are applied pressures from a pressurizing mechanism
51
in the directions as indicated by arrows a and b of
FIG. 1A
so that the interval between the two frames may be reduced.
As a result, not only the upper frame
45
undergoes an elastic deformation in −Y direction as represented by the interrupted lines of
FIG. 1A
, but also the surfaces for welding
45
a
at its both ends experience elastic deformations in −Z direction with respect to the center of the frame, for example, as represented by the interrupted lines of FIG.
1
C. Further, not only the lower frame
46
undergoes an elastic deformation in +Y direction as represented by the interrupted lines of
FIG. 1A
, but also the surfaces for welding
46
a
at its both ends experience elastic deformations in −Z direction with respect to the center of the frame, for example, as represented by the dotted lines of FIG.
1
C. On the other hand, the side frame
47
undergoes an elastic deformation in +X and −Z directions as indicated by the interrupted lines of
FIGS. 1A and 1B
while the side frame
48
undergoes an elastic deformation in −X and −Z directions as indicated by the interrupted lines of
FIGS. 1A and 1B
. The aperture grill
41
is welded to the surfaces
45
a
and
46
a
for welding of the upper and lower frames
45
and
46
of aperture grill supporting frame
42
whose frames have been subject to such deformations as described above, and, after welding, the pressure from the pressurizing mechanism is released. As a result, the frames constituting the aperture grill supporting frame
42
, being relieved of pressures which force them to undergo elastic deformations, try to return to original states through their intrinsic elasticity, and this action gives a tension to stretch the aperture grill
41
in Y-axis direction, or in a vertical direction, and hence the aperture grill
41
becomes a tautly stretched mask.
On this tautly stretched aperture grill
41
is placed a damper wire
43
as indicated by
FIG. 2B
to intersect the long axis of a slit at right angles, and its both ends are stretched by damper springs
44
fastened thereto. Here, the aperture grill
41
is welded to the upper and lower frames
45
and
46
, while the latter are subject to elastic deformations, and, because these welded surfaces
45
a
and
46
a
with a form corespondent with a part of a columnar wall surface with a radius of R as described earlier are assembled as initially designed, the welded surfaces
45
a
and
46
a
being subject to elastic deformations do not actually give that designed form. Accordingly, forces N acting on the thin tapes constituting the aperture grill
41
are not uniform. Particularly at places where a gap c develops between the damper wire
43
and aperture grill
41
, the force N pressing the aperture grill
41
in an axial direction is weakened or lost. Hence, frictional forces acting between the thin tapes and damper wires
43
will not become uniform, and not be able to give an anti-vibration
Kananen Ronald P.
Patel Ashok
Rader Fishman & Grauer
Sony Corporation
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