Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
1998-10-22
2001-08-14
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C313S414000
Reexamination Certificate
active
06273776
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing electrodes of an electron gun for a cathode ray tube and electrodes manufactured thereby, and more particularly, to a method for manufacturing electrodes of an electron gun by welding separate electrode members to each other, and electrodes manufactured thereby.
2. Description of the Related Art
In general, electrodes of an electron gun for a color cathode ray tube are manufactured by the steps of blanking, drawing, punching and swaging a metal sheet supplied in a strip shape, and the electrodes manufactured as above are assembled by using bead glass to be in a firmly assembled state and to form an electron gun. Among the processes for manufacturing the electrodes, the swaging step includes an action which decreases the thickness of the metal sheet to conform to a design value by pressing the metal sheet processed to have a predetermined shape. That is, the circumferential portion of a beam passing hole formed by punching is pressed to have a predetermined thickness.
The diameter of the beam passing hole and the thickness of its circumferential portion are maintained at predetermined design values in order to form an optical lens for converging an electron beam, and the thickness is relatively very thin. On the other hand, since the electrodes in itself are subject to mechanical and thermal stresses applied during manufacturing and assembling processes and thermal stresses produced by the electron beam when the electron gun as a finished product operates in the cathode ray tube, the electrodes must have a mechanical strength taking this fact into consideration. If the thickness of the circumferential portion of the beam passing hole is not formed as in design specifications due to the mechanical and thermal stresses applied to the electrodes and other reasons, it causes distortion of a beam path and finally results in degradation of the quality of the cathode ray tube. Therefore, in manufacturing the electrodes of the electron gun, the circumferential portion of the electron beam passing hole must conform to the normally very thin thickness design requirement, while the other portion must fulfill the contrary requisite of retaining relatively thick thickness to maintain the desired mechanical strength.
FIG. 1
shows a schematic section view illustrating the structure of electrodes and voltages applied to respective electrodes in a conventional electron gun.
Referring to
FIG. 1
, an electron gun includes three cathodes
2
, a control electrode
3
and a screen electrode
4
which constitute a triode, first, second, third, and fourth focusing lenses
5
,
6
,
7
, and
8
which constitute a main lens, and a final accelerating electrode
9
installed to face the fourth focusing lens
8
. Here the three cathodes
2
are disposed linearly, and three corresponding electron beam passing holes are formed in the electrodes linearly. In addition, means
7
a
,
7
h
,
8
a
and
8
h
for forming a quadruple lens are installed in the relatively facing surfaces of the third and fourth focusing electrodes
7
and
8
.
Further, a predetermined static voltage (VS) is applied to the screen electrode
4
and the second focusing electrode
6
, a focusing voltage (VF) higher than the static voltage (VS) is applied to the first and third focusing electrodes
5
and
7
, a dynamic focusing voltage (VD) taking the focusing voltage as a reference voltage is applied to the fourth electrode
8
, and an anode voltage (VA) higher than the above voltages is applied to the final accelerating electrode
9
.
FIG. 2
is a plan view of a conventional electrode,
FIG. 3
is a section view taken along line III—III of
FIG. 2
, and
FIG. 4
is a section view taken along line IV—IV of FIG.
2
. Such an electrode may be one or more of the control electrode
3
, the focusing electrodes and the final accelerating electrode
9
in FIG.
1
.
Referring to
FIG. 2
, an electrode comprises generally an elliptical flat portion
21
, and a side portion
22
extended in a cup shape from the flat portion
21
. Embedded portions
25
are extended from the side portion
22
, and have a shape as shown in FIG.
3
. When the electron gun is assembled with a plurality of electrodes, the embedded portions
25
are embedded in bead glass. Beam passing holes
24
arranged linearly are perforated in the flat portion
21
, the circumferential portions of the beam passing holes
24
are formed to wavy portions
23
. Thermal electrons emitted from the cathodes
2
in
FIG. 1
pass through the beam passing holes
24
.
The wavy portions
3
formed around the circumferential portions of the beam passing holes
24
have a function of preventing a mechanical force and a thermal expansion transferred through the electrodes themselves. That is, the wavy portions
3
buffer the mechanical force applied when the embedded portions
25
are embedded in the bead glass (not shown) in a frit state, and the thermal expansion caused by the heater (not shown) of the cathode
2
to prevent the displacement of the beam passing holes
24
. On the other hand, gas exhaust holes
27
are formed in the flat portion
21
, and in an exhaust step for exhausting air from the cathode ray tube, are utilized to evacuate the inner space of the cathode ray tube. In addition, assembly adjusting holes
28
formed in the side portion
22
are used in inspecting an assembly state of the electrodes.
FIG. 5
is an enlarged section view of the circumferential portion of the beam passing hole.
Referring to
FIG. 5
, the wavy portion
23
is formed in the circumferential portion of the beam passing hole
24
, the thickness (t
2
) of the portion in the vicinity of the beam passing hole
24
is relatively thinner than that (t
1
) of the other portion. In a conventional example, t
2
corresponds to about 74% of t
1
. The reason why the thickness (t
2
) is decided as above is for fulfilling the convergency characteristics of the electron beam in the optical lens formed by the electrode as described above, and the decrease in thickness is accomplished by the swaging process.
Decreasing the thickness of the electrode by the swaging process causes various problems in processes performed after the manufacture of the electrode. That is, since the thickness of the electrode is not uniform, thermal stresses are produced during a subsequent heat treatment as a subsequent process. Therefore, the thermal stresses may deform the shape of the electrode, and may change the position of the beam passing holes
24
. Since variations in the position of the beam passing holes
24
distorts the path of the electron beam emitted from the electron gun to scan a phosphor screen, it is the decisive cause of degradation in the quality of images produced by the cathode ray tube.
SUMMARY OF THE INVENTION
To solve the above problem, it is an objective of the present invention to provide an improved method for manufacturing electrodes of an electron gun for a cathode ray tube.
It is another objective of the present invention to provide a method for manufacturing electrodes of an electron gun for a cathode ray tube, in which respective electrode members are separately formed and are welded to each other to produce an electrode.
It is still another objective of the present invention to provide electrodes of an electron gun for a cathode ray tube manufactured by the improved method.
Accordingly, to achieve the above objective, there is provided a method for manufacturing electrodes of an electron gun for a cathode ray tube comprising the steps of preparing a first electrode member having beam passing holes, the circumferential portion of which has a predetermined thickness, and gas exhaust holes, preparing a second electrode member having a flat portion which has through holes formed to be larger than the beam passing holes and another gas exhaust holes formed to be the same as or larger than the gas exhaust holes, a side portion perpendicularly extended from the peripheral portion of the flat portion
Cha Yung-bae
Kim Yong-Hwan
Lee Song-hark
Gilman & Berner LLP
Hauptman Lowe
Ramsey Kenneth J.
Samsung Display Devices Co. Ltd.
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