Cathode ray tube

Details Cathode ray tube Cathode ray tube

2000-06-01

2003-12-02

Patel, Nimeshkumar D. (Department: 2879)

Electric lamp and discharge devices

Cathode ray tube

Envelope

C220S00230A, C220S00210A

Reexamination Certificate

active

06657374

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cathode ray tube having a lightweight funnel and a lightweight panel.
2. Description of the Related Art
A schematic appearance of a cathode ray tube is shown in
FIG.
6
. In
FIG. 6
, D (mm) shows a diagonal axis length which is an effective dimension of a diagonal axis defined in EIAJ ED-2136A of the Standard of Electronic Industries Association of Japan.
FIG. 7
is a view showing a method of setting a diagonal axis length D of the cathode ray tube. In
FIG. 7
, a method
1
and a method
2
are shown. The method
1
can provide an effective shape (W, H, D: effective lengths of a major axis, a minor axis, and a diagonal axis shown in
FIG. 6
respectively) by adding a 30-degree length of an blend R of an inner wall surface to the center position of the blend R of the inner wall surface, while using an R shape of a corner portion and a center position of the R shape of the panel inner wall surface (IL, IS, ID: center positions of the blend R of the panel inner wall surface in respective sectional shapes along the major axis, the minor axis, and the diagonal axis shown in
FIG. 6
respectively). The method
2
can provide an effective diameter by using a contact point P of an inner curved surface Z=f(x,y) and the blend R, as shown in the right side in FIG.
7
.
A sectional shape taken along an A-A′ line in
FIG. 6
is shown in FIG.
8
. In
FIG. 8
,
1
a
denotes a panel;
11
, a face surface which is formed on the panel
1
a
and has a substantially square outer shape and on which the image is displayed;
12
, a blend R portion of an outer wall surface;
13
, a skirt portion which extends substantially vertically from all areas of an outer peripheral portion of the face surface
11
to the face surface
11
;
1
b
, a funnel which has a funnel shape whose outer shape of a widest open portion of the funnel shape has the same outer shape as the skirt portion
13
of the panel
1
a
;
14
, a sealing portion for connecting the panel
1
a
and the funnel
1
b
;
121
, an F
0
point which is located in the neighborhood of a joint between the blend R portion
12
and the face surface
11
;
122
, an F
1
point which is located in the neighborhood of a joint between the blend R portion
12
and the skirt portion
13
;
18
, a neck portion which is a part of the funnel
1
b
and into which the electron gun is installed;
17
, a yoke portion which is a part of the funnel
1
b
and onto which a deflection yoke for deflecting electron beams is fitted;
15
, a body portion which is a part of the funnel
1
b
as shown in FIG.
8
and extends to the sealing portion
14
connected to the panel; and
16
, a TOP OF ROUND which is an inflection point on a boundary line between the yoke portion
17
and the body portion
15
and is located at a position remote from a yoke reference line by 40 to 50 mm in the sealing portion direction. In this case, the yoke reference line is a reference line in a tube axis of the funnel, which is set forth in EIAJ ED-2134B.
As for the shape of the funnel
1
b
, respective dimensions of the sectional shape of the funnel
1
b
shown in
FIG. 9
are given in Table 1 as an example.
TABLE 1
Funnel Outer Shape
[mm]
Diagonal axis length
D
410 mm
460 mm
510 mm
Minor axis outer length
L1
147.09
164.14
184.44
Major axis outer length
L2
182.44
205.74
227.24
Diagonal axis outer length
L3
220.64
246.49
274.54
Sealing portion to
L4
154.1
183.7
198.7
Reference line
Reference line to Neck
L5
43.4
43.4
43.4
portion
Reference line to Top of
L6
43.4
45.03
45.03
Round
Total length (Reference
L7
324.5
354.1
369.1
value)
The outer shape of the funnel
1
b
shown in
FIG. 9
is connected smoothly from the neck portion
18
, which is formed as a pipe shape of less than &phgr;40 mm in parallel with the tube axis direction, to the cone-shaped yoke portion
17
, to which the deflection yoke is fitted and which is formed smoothly by using several R-shapes, and then connected to the sealing portion
14
via the TOP OF ROUND
16
.
Normally, if the glass bulb consisting of the panel
1
a
and the funnel
1
b
is designed, a maximum tensile vacuum stress which is generated when an inside of the glass bulb is made vacuous is decided from a viewpoint of reliability, especially a viewpoint of the delayed fracture performance, and then a thickness is decided by using the stress as a threshold value. In addition, portions at which the vacuum stress is generated to cause the reduction of the reliability are located in the neighborhood of the blend R portion
12
of the face surface
11
of the panel, and in many cases such vacuum stress is generated mainly on the F
0
point
121
or the F
1
point
122
which is located within a width of 20 mm from both end positions of the blend R.
First, thicknesses at the F
0
point
121
and the F
1
point
122
are decided in view of the maximum vacuum stress. Then, a thickness distribution of the skirt portion
13
is decided such that the crack of the glass, etc. are not generated in the heating process step contained in manufacturing steps of the glass bulb. Accordingly, thicknesses up to the sealing portion
14
are decided, whereby the thickness design of the panel
1
a
can be completed.
Then, a thickness of the funnel
1
b
is decided based on the thickness of the sealing portion
14
, whereby the shape design of the funnel
1
b
can be completed. That is, thicknesses of the body portion
15
and the yoke portion
17
are decided according to the thickness of the sealing portion
14
to be connected smoothly to the neck portion
18
.
For example, as for the aperture grille type cathode ray tube which has the panel
1
a
whose diagonal axis length D is 410 mm and to which a physically reinforcing layer is applied, and in which the maximum value of the stress generated on a surface of the panel
1
a
when the inside of the glass bulb is made vacuous is less than 8.85 MPa, and in which an outer shape R of the face surface
11
is about more than R 30000 mm, the center thickness of the panel
1
a
is set to about 12 mm, the width of the sealing portion
14
is set to about 9 mm, and the thickness of the body portion
15
is set to about 5.4 mm at the lowest minimum in the range from the B-B′ sectional shape to the C-C′ sectional shape of the body portion
15
shown in FIG.
8
.
In this case, the B-B′ sectional shape is located at a position which is a half of the funnel body portion in the height direction. Also, a sectional shape which is located just in the middle of the B-B′ sectional shape and the TOP OF ROUND to divide the height into two parts is set as the C-C′ sectional shape.
Thickness data of the glass bulb shape every diagonal axis length D are set forth in Table 2.
TABLE 2
Example 1
Example 2
Example 3
(D)
(410 mm)
(460 mm)
(510 mm)
Center thickness
12.0 mm 
13.0 mm 
14.0 mm 
Sealing surface
9.0 mm
9.0 mm
9.2 mm
thickness
Body portion center
5.4 mm
5.5 mm
5.5 mm
thickness
Here, the center thickness means a center thickness of the panel
1
a
, the sealing surface thickness means a thickness of the sealing portion
14
, and the body portion center thickness means a minimum value of the thickness (here, the thickness on the minor axis) in the range from the B-B′ sectional shape to the C-C′ sectional shape (positions corresponding to 50 to 75% of the length of the funnel body portion
15
along the tube axis direction) of the body portion
15
shown in FIG.
8
.
In the structure of the cathode ray tube in the related art, since the design is carried out in light of several points such as the blend R portion
12
, etc., such design depends largely upon the experience of the designer and thus the cathode ray tube has the unnecessary thickness which is naturally unnecessary. In particular, the cathode ray tube having a flat panel face tends to increase the thickness, and thus a weight of the cathode ray tube becomes heavy.
SUMMARY OF THE INVENTION
The present invention has been made to ov

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