Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
2001-03-16
2003-01-21
Bradley, P. Austin (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C313S417000, C313S482000, C313S456000
Reexamination Certificate
active
06509682
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a cathode ray tube, and in particular to a cathode ray tube capable of supporting an electron gun firmly within its neck portion.
Generally, an electron gun of a cathode ray tube is supported on a stem of the cathode ray tube and is fixed at a specified position within its neck portion by an electron gun supporting structure.
FIG. 5
is a schematic cross-sectional view of a conventional color cathode ray tube.
In
FIG. 5
, reference numeral
21
denotes a panel portion,
21
F is a faceplate,
22
is a neck portion,
23
is a funnel portion,
24
is a phosphor screen,
25
is a shadow mask,
26
is an internal magnetic shield,
27
is a deflection yoke,
28
is a stem,
29
is a three-beam in-line type electron gun,
30
is an electron beam, and
50
is an internal graphite coating.
A (a glass bulb) vacuum envelope of the color cathode ray tube comprises the panel portion
21
having the generally rectangular faceplate
21
F, the narrow cylindrical neck portion
22
housing the three-beam in-line type electron gun
29
, and the generally truncated-cone shaped funnel portion
23
connecting the panel portion
21
and the neck portion
22
. The phosphor screen
24
is formed on the inner surface of the faceplate
21
F of the panel portion
21
, and the shadow mask
25
having a large number of electron beam-transmissive apertures is fixed and closely spaced from the phosphor screen
24
within the panel portion
21
. The internal magnetic shield
26
is disposed within the funnel portion
23
, and the deflection yoke
27
is mounted around the outside of the funnel portion
23
. The in-line type electron gun
29
is supported on the stem
28
by an electron gun supporting structure described subsequently, and three electron beams
30
(only one of which is shown in
FIG. 5
) emitted from the electron gun
29
are deflected and scanned horizontally and vertically by the deflection yoke
27
, then pass through the electron beam-transmissive apertures in the shadow mask
25
, and then impinge upon the phosphor screen
24
.
The mechanism and operation of displaying a picture by the conventional cathode ray tube is well-known to those skilled in the art, and the explanation of those is omitted.
FIG. 6A
is a broken-away side view of the neck portion
22
of the conventional color cathode ray tube housing the in-line type electron gun
29
,
FIG. 6B
is an enlarged cross-sectional view of the neck portion
22
taken along line VIB—VIB of
FIG. 6A
,
FIG. 6C
is an enlarged cross-sectional view of a supporting member
36
taken along line VIB—VIB of
FIG. 6A
, and
FIG. 6D
is an enlarged cross-sectional view of the neck portion
22
taken along line VID—VID of FIG.
6
A.
FIG. 7
is an enlarged side view of the in-line type electron gun
29
of
FIG. 6A
supported on the stem
28
by the electron gun supporting structure
38
.
In
FIGS. 6A
to
6
C and
7
, reference numeral
31
denotes a cathode, reference character G
1
is a beam control electrode, G
2
is an accelerating electrode, G
3
is a focus electrode, G
4
is an anode, and reference numerals
33
A and
33
B are a pair of bead glasses. The cathode
31
, the beam control electrode G
1
, the accelerating electrode G
2
, the focus electrode G
3
and the anode G
4
are coaxially fixed on the pair of bead glasses
33
A,
33
B with their respective support tabs embedded in the bead glasses
33
A,
33
B. Reference numeral
291
denotes a shield cup,
32
is a heater,
341
,
342
and
343
are stem pins,
35
A and
35
B are mount supports,
36
is a supporting member,
37
are stem mounds. The same reference numerals as utilized in
FIG. 5
designate corresponding elements in
FIGS. 6A
to
6
D and
7
.
FIG. 6D
is an enlarged cross-sectional view of the neck portion
22
taken along line VID—VID of
FIG. 6A
, and illustrates an example of wiring between the stem pins and electrodes of the electron gun. The positions of the respective stem pins are arranged with an equal angular spacing of 25.7° on a pin circle of 15.24 mm in diameter, and the stem pins embedded in the respective stem pin positions are connected to the electrodes of the electron gun as shown in Table 1 below.
TABLE 1
PIN POSITION NOS.
ELECTRODES OF the ELECTRON GUN
#1
FOCUS ELECTRODE (when plural focus
electrodes are employed)
#2
FOCUS ELECTRODE G3
#3
no stem pin embedded
#4
no stem pin embedded
#5 (Ref. No. 343)
BEAM CONTROL ELECTRODE G1
#6
CATHODE FOR GREEN ELECTRON BEAM
#7
ACCELERATING ELECTRODE G2
#8 (Ref. No. 342)
CATHODE FOR RED ELECTRON BEAM
#9
HEATER
#10
HEATER
#11 (Ref. No. 341)
CATHODE FOR BLUE ELECTRON BEAM
#12
INTERNAL CONNECTION
#13
no stem pin embedded
#14
no stem pin embedded
As is apparent from TABLE 1, a stem pin for applying a high voltage of 5 kV to 10 kV to an electrode such as the focus electrode G
3
is spaced by two or more times a regular interval between two adjacent stem pins from adjacent stem pins for applying low voltages to prevent arcing between the high-voltage stem pin and the low-voltage stem pins, and for this reason no stem pins are embedded in the stem pin position #3, #4, #13 and #14.
In
FIGS. 6A and 7
, only the three stem pins
341
,
342
,
343
are shown for the sake of clarity, but it will be understood that in practice there are other stem pins for introducing into the neck portion
22
signals such as a video signal and voltages for forming and focusing of the electron beams
30
, as explained in connection with FIG.
6
D.
In
FIG. 7
, the cathode
31
, the beam control electrode G
1
, the accelerating electrode G
2
, the focus electrode G
3
, the anode G
4
, the heater
32
, and the bead glasses
33
A and
33
B are the constituent parts of the in-line type electron gun
29
, and the stem pins
341
,
342
,
343
, the mount supports
35
A,
35
B, the supporting member
36
form the electron gun supporting structure
38
.
As shown in
FIGS. 6B and 7
, mounds
37
are formed integrally with a disk portion of the stem
28
at the stem pin positions #1 to #14, and the stem pins including the stem pins
341
,
342
and
343
are sealed perpendicularly to and through the disk portion and the mounds
37
of the stem
28
at all the stem pin positions excluding the stem pin positions #3, #4, #13 and #14.
As shown in
FIG. 6B
, the in-line type electron gun
29
are mounted on the stem
28
such that the pair of bead glasses
33
A and
33
B indicated by broken lines are parallel with a line connecting the stem pins
341
and
342
embedded at the stem pin positions #11 and #8, respectively. A pair of mount supports
35
B and
35
A welded to the two stem pins
341
and
342
, respectively, are embedded in the bead glass
33
A at their ends of the mount supports
35
B and
35
A. The other bead glass
33
B has another mount support
35
B embedded therein such that the mount support
35
B is positioned symmetrically with the mount support
35
A welded to the stem pin
342
with respect to the axis X—X.
The two mount supports
35
B and
35
A corresponding to the two stem pins
341
,
342
are directly welded to the two stem pins
341
,
342
at their respective ends protruding from the bead glass
33
A. The mount support
35
B embedded in the bead glass
33
B cannot be welded directly to any stem pins because no stem pins are embedded in the stem pin positions #3 and #4 near the mount support
35
B for prevention of arcing as explained above, and therefore the end of the mount support
35
B protruding from the bead glass
33
B is welded to the stem pin
343
embedded at the stem pin position #5 via the supporting member
36
.
FIGS. 6E and 6F
are enlarged perspective views of the mount supports
35
A and
35
B, respectively.
As shown in
FIG. 6C
, the supporting member
36
has a generally C-shaped transverse cross section, and comprises a plate-like portion
360
and first and second bent portions
361
a
Ishinagawa Shinichi
Takahashi Yoshiaki
Antonelli Terry Stout & Kraus LLP
Bradley P. Austin
Hammond Briggitte R.
Hitachi , Ltd.
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