Electric lamp and discharge devices – Cathode ray tube – Plural beam generating or control
Reexamination Certificate
2000-10-30
2002-11-05
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Plural beam generating or control
C313S417000, C313S444000, C313S457000, C313S460000
Reexamination Certificate
active
06476543
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a cathode ray tube, and in particular to a cathode ray tube having reliability enhanced by improving welding accuracy of an electrode fabricated by stacking and welding together a plurality of electrode members in an electron gun housed in its vacuum envelope.
Color cathode ray tubes such as a color picture tube and a display tube, which are typical cathode ray tubes, are widely used for reception of TV broadcast and monitors of various kinds of information processing equipment because of their high-definition image reproduction capability.
Color cathode ray tubes of such a kind have a vacuum envelope comprised of a panel, a neck and a funnel for connecting the panel and the neck, a phosphor screen formed on an inner surface of the panel, and an electron gun housed in the neck for projecting an electron beam toward the phosphor screen. Especially, widely used are color cathode ray tubes employing an in-line type electron for projecting a plurality of electron beams parallel with each other in a horizontal plane.
FIG. 10
is a side view of an essential part of an embodiment of a configuration of an in-line type electron gun used for a color cathode ray tube, viewed in a direction perpendicular to a direction of the in-line arrangement of electron beams. In
FIG. 10
, reference numeral
31
denotes cathodes,
32
is a first electrode serving as a control electrode,
33
is a second electrode serving as an accelerating electrode, and the cathodes
31
, the first electrode
32
and the second electrode
33
form an electron beam generating section.
Reference numeral
34
denotes a third electrode, and
35
is a fourth electrode. In this example, the fourth electrode
35
are formed of two tube-like electrodes
35
a
and
35
b
, and they serve as two focus electrodes. Reference numeral
36
denotes a fifth electrode, and the fifth electrode
36
and the tube-like electrode
35
b
of the fourth electrode
35
which forms a main lens therebetween. Reference numeral
37
denotes a shield cup, which is welded to the fifth electrode
36
. The cathodes
31
and the first to fifth electrodes
32
-
36
are spaced with predetermined spacings and fixed in the predetermined order by a pair of insulator support rods (multiform glasses)
38
. Reference numeral
39
denotes a stem, and the cathodes and the electrodes are supplied with display signals or operating voltages via stem pins
40
sealed through the stem
39
.
Three electron beams are generated by the electron beam generating section which is a triode section comprised of the cathodes
31
, the first electrode
32
and the second electrode
33
, and are accelerated and focused by the third electrode
34
, the fourth electrode
35
and the fifth electrode
36
such that the three electron beams are subjected to a desired focusing action by the main lens formed between opposing end faces of the fifth electrode
36
and the electrode
35
b
of the fourth electrode
35
and then directed toward the phosphor screen.
In this type of an electron gun, the first electrode
32
and the second electrode
33
are plate-like electrodes, and the third electrode
34
and the fourth electrode
35
are compound electrodes fabricated by stacking and welding together plural electrode members including a cup-shaped electrode member and a plate-like member.
FIGS.
11
A
1
,
11
A
2
,
11
B
1
,
11
B
2
,
11
C
1
and
11
C
2
are plan views and side views of electrode members forming the compound electrode shown in FIG.
10
. FIGS.
11
A
1
and
11
A
2
are plan and side views of a first electrode member
1
, respectively, FIGS.
11
B
1
and
11
B
2
are plan and side views of a second electrode member
2
, respectively, and FIGS.
11
C
1
and
11
C
2
are plan and side views of a third electrode member
3
, respectively. The first electrode member
1
and the third electrode member
3
are attached and welded by laser to the top and bottom surfaces of the second electrode member
2
, respectively.
The first electrode member
1
and the third electrode member
3
are cup-shaped electrode members having rims
1
b
and
3
b
, respectively, and are formed by a drawing press. The second electrode member
2
are a plate electrode thicker than the first electrode member
1
and the third electrode member
3
.
The first electrode member
1
is formed with a single opening (an electron beam-transmissive opening)
1
a
in a bottom at an end of its cup shape and the rim
1
b
at the other end of the cup shape. The rim
1
b
is formed with a protrusion
1
c
in a corner thereof for rotational alignment of the first electrode member
1
in an assembly or welding an electrical lead thereto for applying a voltage to the first electrode member
1
. Similarly, the third electrode member
3
is formed with a single opening (an electron beam-transmissive opening)
3
a
in a bottom at an end of its cup shape and the rim
3
b
at the other end of the cup shape. The rim
3
b
is formed with a protrusion
3
c
in a corner thereof for indicating a position of the third electrode member
3
in an assembly or welding an electrical lead thereto for applying a voltage to the third electrode member
3
.
The second electrode member
2
is formed with three electron beam-transmissive apertures
2
a
in its central portion on its major axis. The second electrode member
2
is fabricated by a simple punching which pierces the three apertures in a thick metal plate simultaneously with blanking, or trimming. An edge
2
b
is used for welding and is provided with tabs
2
c
approximately at centers at the respective long sides of the second electrode member
2
for being embedded into the insulator support rods (multiform glasses)
38
and thereby being fixed.
FIGS. 12A
,
12
B and
12
C are illustrations for explaining a structure of a compound electrode integrally assembled and its welded condition,
FIG. 8A
is a plan view of the compound electrode,
FIG. 12B
is a cross-sectional view of the whole structure of the compound electrode of
FIG. 12A
taken along line VIIIB—VIIIB of
FIG. 12A
, and
FIG. 12C
is an enlarged cross-sectional view of an essential part of a welded portion in a cross section of the compound electrode of
FIG. 12A
taken along line VIIIC—VIIIC of FIG.
12
A. In
FIG. 12A
, two positions corresponding to a pair of insulator support rods (multiform glasses)
38
are indicated by two-dot chain lines.
The first electrode member
1
and the third electrode member
3
are attached to the top and bottom surfaces of the second electrode member
2
, respectively, such that the edge of the rim
1
b
of the first electrode member
1
and the edge of the rim
3
b
of the third electrode member
3
are aligned with the edge
2
b
of the second electrode member
2
, and then they are welded together by irradiating a laser beam onto the edges of the interface between the adjacent electrode members. In
FIGS. 12A and 12C
, the weld points are denoted by “W→”.
As shown in
FIGS. 12A and 12B
, the first, second and third electrodes
1
,
2
,
3
are attached together, and then, as shown in
FIG. 12C
, they are welded together by irradiating a laser beam L horizontally onto the edges of the interface between the mutually adjacent electrode members. The laser welding in this case employs a multiple-beam multiple-spot welding method capable of welding two or more spots simultaneously. In FIG.
12
C, the weld points are denoted by circles “∘”.
The above-explained compound electrodes are not limited to one comprised of three electrode members as explained above, but are applicable to one comprised of a plate-like electrode member and a cup-shaped electrode member stacked and welded on the plate-like electrode member.
SUMMARY OF THE INVENTION
But, as shown in
FIG. 12D
, when the second electrode member
2
is punched out by use of a die
50
and a punch
51
, sloping surfaces
53
are produced at forward edges of the second electrode member
2
in a direction of travel of the punch
51
because its material flows in
Kagabu Ken
Konishi Yoshifumi
Mera Takeshi
Sudo Akihito
Clove Thelma Sheree
Patel Nimeshkumar D.
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