Electric lamp or space discharge component or device manufacturi – Process – With testing or adjusting
Reexamination Certificate
1999-07-28
2001-07-24
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With testing or adjusting
C445S064000
Reexamination Certificate
active
06264520
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of and apparatus for sealing a color cathode-ray tube, and more particularly to a method of and apparatus for sealing a color cathode-ray tube used for the process of sealing the electron gun assembly of a color cathode-ray tube.
A color cathode-ray tube comprises a funnel-shaped glass bulb with a panel, or a vacuum envelope, and an in-line electron gun assembly inserted in the neck of the bulb in such a manner that it is held in a specific position.
FIG. 1
shows a color cathode-ray tube obtained after the electron gun assembly
12
has been inserted in the bulb
11
and the bulb has been sealed.
In such a color cathode-ray tube, when the electron gun assembly
12
that generates three electron beams for RGB, or red, green, and blue, is sealed, it is desirable that an imaginary line X—X passing through the center of each of three electron beam holes
12
r
,
12
g
, and
12
b
made in an electron gun electrode
12
a
shown in
FIG. 2
should be aligned with an imaginary line (a reference line in a horizontal plane) H—H in the direction of the major axis passing through the center of a rectangular screen of the bulb
11
shown in FIG.
1
.
FIG. 4
shows a state where imaginary line X—X does not align with imaginary line H—H and crosses the latter at an angle of &thgr;, or a misaligned state in a twisted manner.
For monitors used with the recent personal computers, the standard for rotation known as twist has become severer.
Imaginary line X—X and imaginary line H—H do not exist in reality. Therefore, in actual adjustment, imaginary line H—H is defined as a parallel line to a pad face
13
of the bulb
11
shown in FIG.
1
and imaginary line X—X is determined using one side face in the direction of the major axis of the electron gun assembly
12
of
FIG. 2
as a reference face. The electron gun assembly
12
is provided in the neck of the bulb
11
in such a manner that imaginary line H—H aligns with imaginary line X—X. Then, the air is exhausted from the bulb
11
. Thereafter, the neck is sealed.
A method of assembling a color cathode-ray tube by providing such an electron gun assembly
12
in the bulb
11
has been disclosed in, for example, Jpn. Pat. Appln. KOKOKU Publication No. 61-20106. In the assembly, the position of the electron gun assembly
12
is determined as described below in detail and provided in the neck.
As shown in
FIG. 1
, an electron gun electrode
12
a
shown in
FIG. 2
is connected electrically and mechanically to a stem section
16
with stem pins
15
provided in the lower part, forming an electron gun assembly
12
, which is provided in the bulb
11
. Specifically, as shown in
FIG. 3
, the electron gun electrode
12
a
is provided on the stem section
16
in such a manner that imaginary line X—X passing through three electron beam holes
12
r
,
12
g
, and
12
b
made in the electron gun electrode
12
a
crosses, at right angels, imaginary line Y—Y passing through a pair of top and bottom stem pins
15
a
,
15
a
serving as a reference. When the electron gun electrode
12
a
is connected to the stem section
16
, it is ideal that imaginary line X—X should cross imaginary line Y—Y accurately at right angles. In actual assembly, however, there arises a small twist error.
The position of the electron gun assembly
12
put together as described above is measured and inserted in the bulb
11
. When the electron gun assembly
12
is inserted in the bulb
11
, the electron gun assembly
12
is placed in a specific position. In the positioning, a pair of square holes
14
,
14
made in both side faces of the electron gun electrode
12
a
, one hole in each face is used. Specifically, a laser beam is emitted from one side of the pair of square holes
14
,
14
and pass through the square holes. Then, the diffraction images of the square holes
14
,
14
are sensed. When the diffraction images form a specific pattern, the electron gun assembly
12
is so set that it has a specific location with respect to the screen. Thereafter, the neck in which the electron gun assembly
12
has been provided is sealed.
In the method disclosed in Jpn. Pat. Appln. KOKOKU Publication No. 61-20106, an electron gun assembly
12
with a pair of square holes
14
,
14
in both side faces of an electron gun electrode
12
a
is mounted on a rotating adjustment table (not shown) as shown in FIG.
2
. The rotating adjustment table can rotate on the center axis Z—Z of the bulb
11
combined with the electron gun assembly
12
and is so set that it has a specific positional relationship with a holding unit (not shown) for holding the bulb
11
.
Next, a laser beam is generated in such a manner that the center axis Z—Z crosses the direction of optical axis at right angles. The laser beam is emitted from one side of the pair of square holes
14
,
14
. The laser beam passes through the pair of square holes
14
,
14
and is projected on a sensor (not shown). The sensor monitors the diffraction pattern formed as a result of the laser beam passing through the square holes
14
,
14
. The diffraction images are displayed on a monitor television. Then, the rotating adjustment table is manually rotated until the displayed diffraction images have formed a specific image, thereby adjusting the angle of the electron gun assembly
12
.
Thereafter, the bulb
11
is so held by the holding unit that imaginary line H—H of the bulb
11
is placed in a specific position at which line H—H aligns with the optical axis of the laser beams. In this state, the electron gun assembly
12
is inserted in the neck of the bulb
11
as shown in FIG.
1
. Thereafter, the electron gun assembly
12
is sealed in the bulb
11
by a burner (not shown).
In such an assembly method, the aligning of the direction of rotation of the electron gun assembly
12
is done by the operator who turns the adjusting screw serving as the driving mechanism of the rotating adjustment table, while watching a monitor television. Therefore, the result of adjustment varies greatly, depending on the operator. Consequently, it is difficult to seal the electron gun assembly
12
with high accuracy.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a method of and apparatus for sealing a color cathode-ray tube capable of making alignment at high speed with high rotation accuracy without variations in the result depending on the operator and of improving the quality of the color cathode-ray tube.
The foregoing object is accomplished by providing a color cathode-ray tube sealing method of positioning an electron gun assembly with respect to the screen of a color cathode-ray tube and sealing the assembly in the neck portion of the color cathode-ray tube, comprising the steps of: rotating the electron gun assembly on the tube axis of the color cathode-ray tube; emitting a laser beam from one of a pair of square holes facing each other made in the electron gun assembly, with the electron gun assembly in the rotated state; receiving, outside the other square hole, a diffraction pattern produced by the laser beam passed through the holes; aligning the electron gun assembly by stopping the rotation of the assembly when the received diffraction image has become a preset desired image.
While the electron gun assembly is being rotated on the tube axis of the color cathode-ray tube, the laser beam is emitted from one side to the pair of square holes made in the electron gun assembly. The resulting diffraction images are received and processed. The image-processed diffraction images are subjected to arithmetic operations. This enables highly accurate positioning to be done at high speed without variations in the result depending on the operator. As a result, it is possible to provide a color cathode-ray tube with high picture quality.
The state where the center-to-center distance or side-to-side distance between the zero-order diffraction image of the square hole and diffraction images of interference fringes of the first order or higher is the smallest is set a
Hirayama Kazumasa
Yamazaki Tatsuya
Yokoyama Shoichi
Yoshida Maki
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ramsey Kenneth J.
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