Electric lamp and discharge devices – Cathode ray tube – Shadow mask – support or shield
Reexamination Certificate
2000-02-07
2002-01-15
O'Shea, Sandra (Department: 2875)
Electric lamp and discharge devices
Cathode ray tube
Shadow mask, support or shield
C313S402000, C445S030000
Reexamination Certificate
active
06339283
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a color selection mechanism used in a color cathode ray tube, a frame for use in the color selection mechanism, a cathode ray tube equipped with the color selection mechanism, and a method of manufacturing the frame for use in the color selection mechanism.
2. Description of the Related Art
As a color selection mechanism for use in a color cathode ray tube, for example, there is known a color selection mechanism
51
, called “an aperture grill,” such as that illustrated in FIG.
1
. This color selection mechanism
51
has provided therein a frame
56
for use in a color selection mechanism, whose skeletal structure is shaped like a framework, and which is hereinafter referred to simply as “a frame”. The frame
56
is composed of a pair of supporting members
52
and
53
that are arrayed in parallel in such a way as to oppose each other and elasticity-imparted members
54
and
55
, each of which is bridged over the corresponding ends of the supporting members
52
and
53
(and which sometimes for brevity are hereinafter referred to simply as “elastic members”). This frame
56
is constructed in such a form wherein a color sorting electrode thin plate (hereinafter referred to simply as “a thin plate”)
60
, having a large number of slit-like electron beam apertures (hereinafter referred to simply as “apertures”
59
) in one direction, i.e., in the horizontal direction of the screen, is mounted or bridged over the mutually opposing and parallel arranged supporting members
52
and
53
of the frame
56
.
The thin plate
60
is constructed in such a form wherein a large number of small-width and strip-like grid elements
58
each comprising a metal thin sheet are arrayed at prescribed intervals in said one direction; and the apertures
59
, each having an opening in the vertical direction of the screen are formed between the mutually adjoining grid elements
58
. The thin plate
60
is also constructed in such a form wherein the grid elements
58
are bridged over the supporting members
52
and
53
, with some extent of tension being imparted thereto by the elastic members
54
and
55
.
In this color selection mechanism
51
, in order to prevent the grid elements
58
from being vibrated, damper wires
57
are mounted in the array direction of the grid elements
58
, so as to contact with the surface of the thin plate
60
. The reference symbol
61
represents damper springs for imparting a tension to the damper wires
57
.
In addition, although not illustrated, springs for example are respectively attached to the supporting members
52
,
53
and the elastic members
54
,
55
. Through the intermediary of these springs, the color selection mechanism
51
is fixed to the panel of the body of the cathode ray tube.
The supporting members
52
,
53
in the long-side direction of the frame
56
and the elastic members
54
,
55
in the short-side direction thereof are connected together by welding. Both of these members are assembled in the form of parallel crosses to thereby construct the frame
56
.
FIG.
2
and
FIGS. 3A
to
3
D illustrate the schematic construction of a conventional frame
56
that is used in the color selection mechanism
51
of FIG.
1
.
As illustrated in
FIGS. 2 and 3A
to
3
D, the frame
56
is constructed in such a form wherein elemental members that comprise a pair of long-side frame members
52
,
53
and a pair of short-side elastic members
54
,
55
are assembled together in the form of parallel crosses. These both elemental members are connected together by welding, e.g., Tig welding (arc welding that is performed in the atmosphere of an inert gas by using metal such as tungsten as a welding electrode).
As illustrated in
FIG. 3A
, each of the supporting members
52
,
53
has a substantially L-shaped section, and is formed such that, as illustrated in
FIG. 3C
, the upper and bottom surfaces of each of these members have a prescribed radius of curvature.
As illustrated in
FIG. 3B
, each of the elastic members
54
,
55
is configured such that an angular member used as the elastic member
54
,
55
is bent at the positions near the ends thereof, becoming future joint portions. Each elastic member, as illustrated in
FIG. 3D
, is formed substantially into a shape of horizontally thrown U. And, the ends of each elastic member
54
,
55
are connected to the corresponding one-end bottom surfaces of the supporting members
52
,
53
by welding.
Welding is done with respect to four positions, respective left end and right end portions of the upper and lower supporting members
52
,
53
in FIG.
2
.
And, as illustrated in
FIG. 4A
an enlarged view of the joint portion and its neighborhood of the elastic member
54
,
55
, in with four surfaces
65
a
,
65
b
,
65
c
, and
65
d
corresponding to four sides of the end surface
65
, which becomes a future welded portion of the elastic member
54
,
55
, with one surface
65
d
being made weld-free. Namely, with this one surface
65
d
being kept not welded, a clearance is instead formed correspondingly thereto. And welding is done with respect to the remaining three surfaces
65
a
,
65
b
, and
65
c.
For example, as with the welded range and the welding direction illustrated in
FIG. 4B
, welding is done with respect to the three surfaces
65
a
,
65
b
, and
65
c
in this order.
As a result of this, in the post-welding state illustrated in
FIG. 5
, with the clearance remaining at the illustrated portion
66
, the inert gas that generates when doing welding has hitherto been removed from this clearance
66
.
However, when the clearance
66
that corresponds to the above-described weld-free portion is large, in a thereafter succeeding removing step of oxide scales that have occurred in an annealing step of the frame
56
for use in color selection mechanism, rust of the frame
56
, etc., there arises the problem that shot blast balls for use in this removal will be carried through the clearance
66
.
For this reason, 100% inspection is visually performed with respect to the entire frame
56
about the entry of the shot blast balls. In a case where shot blast balls remain within the clearance
66
, take-out of these shot blast balls is performed. In frame
56
from which shot blast balls have been removed is put into use.
However, even when inspection has been performed with respect to the entire frame
56
, by missing shot blast balls during the inspection, it is also possible that shot blast balls will be discovered in the clearance
66
in the course of the thereafter succeeding manufacturing process of the cathode ray tube.
When in this way having formed a cathode ray tube with shot blast balls remaining therein, for example, abnormal discharge may occur due to the shot blast balls when the cathode ray tube is operated. Namely, the shot blast balls contained therein may have serious effects on the withstand voltage characteristic of the cathode ray tube.
Also, it is possible that the rustproofing oil that is used in the rustproofing step will be carried into the clearance
66
. Usually, the rustproofing oil that has been carried in comes out from the clearance
66
and vaporizes when performing heat treatment in the annealing step (so-called “blackening”) of the frame.
However, in a case where the clearance
66
is narrow, even when entry of the rustproofing oil occurs, this oil does not come out from the clearance
66
and vaporize during the annealing step. Instead, there may occur a case where this oil comes out when vacuumization is done in the manufacturing step of the cathode ray tube, etc.
On the other hand, in a case where all of the four surfaces
65
a
,
65
b
,
65
c
, and
65
d
corresponding to the four sides of the end surface
65
of the elastic member
54
,
55
have been welded without providing a zone that is made weld-free, no clearance
66
is formed at the side portions of the end surface
65
.
When manufacturing the cathode ray tube with this clearance
66
not provided, the welding gas rem
Alavi Ali
Kananen Ronald P.
O'Shea Sandra
Rader & Fishman & Grauer, PLLC
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