Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
1998-09-30
2002-06-11
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C313S044000, C220S00230A
Reexamination Certificate
active
06404119
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color cathode ray tube apparatus and a method for manufacturing a color cathode ray tube apparatus, and more specifically it relates to a color cathode ray tube apparatus that is suitable for mounting of a deflection yoke thereto, and a method of manufacturing the above-noted color cathode ray tube apparatus.
2. Description of Related Art
A color cathode ray tube apparatus
41
of the past, as shown in FIG.
16
and
FIG. 17
, is made up of a color cathode ray tube
42
and a deflection yoke
51
. The color cathode ray tube
42
is made up of a panel part
43
, onto the inside surface of which is formed a phosphor film
43
a
, a funnel part
47
, which includes a shadow mask structure
46
that includes a shadow mask
44
and a frame
45
, and a neck part
48
, which houses an electron gun structure
50
that emits 3 electron beams.
An electron beam
50
a
is deflected by a magnetic field from the deflection yoke
51
, passes through the shadow mask
44
, and causes light to be emitted by the phosphor film
43
a
, thereby displaying an image on the panel screen.
The phosphor film
43
a
on the inside surface of the panel part
43
is formed by phosphors for the three primary colors, red, green, and blue, and in order to cause these phosphors to emit light, an electron gun structure
50
, which includes three cathodes that emit an electron beam
50
a
, in an in-line arrangement, is housed within the neck part
48
.
In order to deflect the three electron beams
50
a
that are emitted from the electron gun structure
50
in the horizontal direction and the vertical direction, a deflection yoke
51
, which includes a horizontal deflection coil
51
a
and a vertical deflection coil
51
b
that generate a magnetic field, is attached to the region of the joint between the funnel part
47
and the neck part
48
.
The magnetic field that is generated by the deflection yoke deflects the electron beams
50
a
so as to display a desired image on the screen.
The deflection electrical power of the color cathode ray tube apparatus
41
is largely governed by the horizontal deflection electrical power of the deflection yoke
51
. This horizontal deflection power PH is established by the following equation, which expresses this deflection power as a function of the inner diameter Dc of the envelope inner surface of the deflection coil
51
a
and the length Lc of the deflection coil
51
a
that forms the deflection yoke
51
, the accelerating potential Eb applied to the electron gun
50
, the frequency fH of the horizontal deflection coil, and the horizontal deflection angle &thgr;H of the electron beam
50
a
.
PH∝fH×Dc×Eb×
sin
2
(&thgr;
H/
2)/
Lc
(1)
From the above-noted relationship, it can be seen that the making of the horizontal deflection power PH small is determined by the accelerating potential Eb that is applied to the electron gun structure
50
, the length Lc of the horizontal deflection coil
51
a
and the inner diameter Dc of the envelope thereof.
If the accelerating potential Eb is made small, the velocity of electrons which impinge on the phosphor film
43
a
of the panel part
43
is made small, so that the focus characteristics of the image formed with a reduced intensity worsen.
In a usual color cathode ray tube apparatus
41
, the accelerating potential Eb that is applied to the electron gun structure
50
is 18 kV or greater, and is usually approximately 25 kV. Note also that it is not desirable to make the length Lc of the horizontal deflection coil
51
a
large, as this makes the overall length of the color cathode ray tube apparatus
41
long, so that making the inner diameter Dc of the envelope surface small requires that the outer diameter of the neck part
48
be made small.
The making of the outer diameter of the neck part
48
small means that the outer diameter of the electron structure
50
housed therewithin would be made small, resulting in an increase in spherical aberration in the electron lens, this causing a deterioration in the focussing characteristics of the image.
For example, in accordance with Ludwig von Seidel's aberration theory, for a spherical aberration S
1
, a koma aberration S
2
, an astigmatism S
3
, an electron beam distance from the tube axis of Ya, and an electron gun structure radius of r, the following relationships obtain.
S
1
∝(
Ya/r
)
2
S
2
∝(
Ya/r
)
2
S
3
∝(
Ya/r
)
2
From the above relationships, by making the radius r of the electron gun structure
50
small, these aberrations S
1
, S
2
, and S
3
increase, the result leading to a deterioration in the focussing characteristics.
If the outer diameter of the electron gun structure
50
is increased as much as possible, so that it approaches the inner diameter of the neck part
48
, when a high voltage is applied sparking can be caused between the electron gun structure
50
and the neck part
48
.
Because of this, in setting various parameters in the desire to obtain the best possible image, an accompanying increase in the deflection power occurs.
In recent years, color cathode ray tube apparatuses, and particularly for use as terminal displays for personal computers and other data equipment, are experiences demands for not only larger size, decreased thickness, higher intensity, and greater resolution, but also for a reduction in energy consumption.
To satisfy these market requirements, for example with regard to power consumption, in view of the above-noted equations, a method that can be envisioned is that of making any one of the horizontal deflection frequency fH, the envelope surface inner diameter Dc, the accelerating potential Eb, and the horizontal deflection angle &thgr;H small, or one of making the length Lc of the horizontal deflection coil large.
However, with the increased application of color cathode ray tube apparatus for displays, there have been increasing demands from the marketplace with regard to functional items such as increased size, thinness, high intensity, high resolution and the like, as well as with regard to quality, it has become impossible to satisfy these demands by merely pursuing extensions of existing technologies.
That is, the above-noted horizontal deflection frequency fH, the envelope surface inner diameter Dc, the accelerating potential Eb and the horizontal deflection angle &thgr;H all become large, this leading to a trend to an increase in the horizontal deflection power PH.
This being the situation, one approach is to accommodate this by the accelerating potential Eb that is applied to the electron gun structure
50
, the length Lc of the horizontal deflection coil
51
a
, and the inner diameter Dc of the envelope thereof, which are adjustment factors.
For example, there has been a proposal for achieving operation with a small deflection power by making the boundary part of the funnel part and the neck part narrower than the outer diameter of the neck (refer to the Japanese Unexamined Patent Publication (KOKAI) No. 48-90673).
However, by making the outer diameter of the neck large so that the above-noted boundary part is relatively narrower, not only is a power savings not achieved, but also this proposal lacks practical usability, because of the increased difficult of attaching the deflection yoke.
Accordingly, in view of the drawbacks in the prior art as described above, a major object of the present invention is to provide a color cathode ray tube apparatus with a reduced power consumption, without sacrificing image quality.
A particular object of the present invention is to provide a color cathode ray tube apparatus in which the neck part is made of two parts having different outer diameters, a deflection yoke being disposed at a par thereof that has the smaller diameter.
Another object of the present invention is to provide a method of manufacturing a color cathode ray tube apparatus that includes the formation of a neck part having different outer diameters, and a method of attaching a deflection
Aibara Nobumitsu
Arai Shinji
Hidaka Tadachika
Ueda Masahiro
Yanai Yoshiaki
Guharay Karabi
NEC Corporation
Patel Nimeshkumar D.
Scully Scott Murphy & Presser
LandOfFree
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